JP2019534466A - Material erosion monitoring system and method - Google Patents

Abstract

An improved system and method for assessing the condition of a material is disclosed. The systems and methods operate to utilize electromagnetic waves to identify defects and measure erosion profiles and thicknesses of various materials, including refractory materials. The system sufficiently reduces multiple reflections associated with the propagation of electromagnetic waves delivered to the material under evaluation, allowing detection of electromagnetic waves of interest reflected from remote discontinuities in the material. Designed as such. The systems and methods also utilize configurations and signal processing techniques that reduce clutter and allow separation of electromagnetic waves of interest. Furthermore, the launcher is impedance matched to the material under evaluation, and the feed mechanism is designed to reduce the multiple reflection effect and further suppress clutter.

Description

  The present invention relates to a system and method for assessing the condition of a material. More specifically, the present invention relates to a system and method (material interface using electromagnetic waves) for determining refractory bricks.

  Evaluation methods and systems exist in various industries to measure the properties of certain materials during and after molding. Surface properties, internal uniformity, and material thickness are some of the important properties that may need to be evaluated. In particular, the thickness of glass and plastic container walls using non-contact reflective and / or absorptive techniques by placing sensors and emitters that direct radiation towards the container is described in US Pat. Has been addressed in the prior art. However, these methods do not incur significant losses at the level of such radiation, or radiation that can pass through those materials without approaching just one of the external surfaces of such materials. The main purpose is to evaluate the thickness of the glass and plastic containers produced.

  On a larger scale, some industries such as the glass, steel and plastic industries use large furnaces to melt the raw materials used for processing. These furnaces can reach a length corresponding to the height of a 20-story building. Thus, they are a major asset for manufacturers in terms of cost and operational functionality. In order to minimize internal heat loss at high operating temperatures, these furnaces are constructed using refractory materials with very high melting temperatures and good thermal insulation properties to create a refractory melting chamber. However, the inner walls of the furnace refractory chamber are subject to deterioration during operation. The effects of this degradation include internal surface erosion, stress cracks, and diffusion of the refractory material into the molten material.

  At present, there is no established method for deterministically measuring the thickness and erosion profile of such furnace walls. As a result, the manufacturer can reduce the possibility of any possible leakage based on the manufacturer's experience with unexpected leakage of molten material through the furnace wall, or the expected life of the furnace, Experience any of the conservative shutdowns of the furnace. The life of the furnace is the refractory material, in addition to the years of operation, the average temperature of operation, the temperature rate of heating and cooling, the range of operating temperatures, the number of cycles of operation, and the weight and type of melting material used in the furnace Affected by several factors including the type and quality of Each of these factors suffers from uncertainties that make it difficult to produce an accurate estimate of the expected life of the furnace. In addition, at high temperatures, the flow of molten material, such as molten glass, erodes and degrades the inner surface of the refractory material and creates a high risk for molten glass leakage through the refractory wall. Major leaks of molten glass through gaps and cracks in the furnace wall may require at least 30 days of production disruption before the furnace can return to operating mode. This is because the furnace needs to be cooled, repaired and reignited. Furthermore, molten glass leakage can cause serious damage to equipment around the furnace and, most importantly, can endanger the health and lives of workers. For these reasons, in most cases, furnace overhaul occurs at a much faster time than is required. This leads to significant costs to manufacturers in terms of these initial investments and a reduction in production capacity over the operating life of the furnace.

  Another important issue is that the materials used to build the furnace refractory chamber can have internal defects that are not visible by surface inspection. This can lead to a shorter life of the furnace and can pose serious risks during the operation of the furnace. Thus, on the one hand, manufacturers of refractory materials want to have a means to evaluate materials during production so that they can limit the materials for building the furnace according to quality standards for supplying defect-free materials. Think. On the other hand, consumers who purchase refractory materials want to have a means to perform an internal inspection of such materials before building the furnace.

  Past efforts have been made using microwave signals to measure the thickness of materials such as furnace walls, as described in US Pat. However, these efforts faced certain challenges and limitations. In particular, attempts made to determine the furnace wall thickness of high temperature furnaces are generally due to the large signal loss involved in evaluating the inner surface of the refractory material, especially in relatively high frequency bands. It ended in failure. Similarly, in the relatively low frequency band, the signal still experiences loss and is limited in terms of the frequency band and resolution required for existing systems. Furthermore, in the placement of system components in close proximity to the surface of the refractory material being evaluated, spurious signal reflections make it difficult to separate the reflected signal of interest, and thus either the inner surface or the interior of such materials. Further complicates the assessment of conditions. The main approach is for the furnace walls to become more conductive as the temperature increases. Therefore, signals passing through the hot furnace walls experience significant losses that make these signals very difficult to detect.

  Thus, there remains a need in the art for systems and methods that allow remote assessment of the state of such refractory materials through measurements of propagating electromagnetic waves that avoid the problems of prior art systems and methods.

US Patent Application Publication No. 20130268237 US Pat. No. 6,198,293 US Patent Application Publication No. 20130144544

  Improved systems and methods for assessing the condition of materials are disclosed herein. One or more aspects of the exemplary embodiment provide advantages while avoiding the disadvantages of the prior art. The system and method operate to identify defects and measure erosion profiles and thicknesses of various materials, including refractory materials, using electromagnetic waves. To a degree sufficient to allow detection of electromagnetic waves of interest that reflect from remote discontinuities in the material, the system will reduce multiple reflections associated with the propagation of electromagnetic waves delivered to the material under evaluation. Designed. In addition, the system and method utilize structures and signal processing techniques that reduce clutter and enable separation of the electromagnetic waves of interest. In addition, the launcher used in the system is impedance matched to the material under evaluation and the feed mechanism is designed to mitigate the effects of multiple reflections to further suppress clutter.

  The system delivers electromagnetic waves to the close surface of the material being evaluated. Electromagnetic waves penetrate the material and reflect both from discontinuities inside the material as well as from remote surfaces in the vicinity of the material. The reflected electromagnetic wave is received and measured by a computer-based processor using a wave reflected from the near surface of the material as a reference. A computer-based processor determines the time delay between the reference wave and other reflected electromagnetic waves including unwanted clutter. If the intensity of the clutter is less than the intensity of the electromagnetic waves reflected from the remote discontinuities in the material, the computer-based processor identifies the peak intensity levels associated with these discontinuities and Determine the distance to the near surface of the material associated with the reference wave. One or more assessments over the area of material provide the thickness of the material and the location of defects within the material in each assessment, creating an erosion profile of the remote surface of the material.

  The system also includes an electromagnetic wave launcher designed and adapted to reduce multiple reflections that contribute significantly to the clutter received by the computer-based processor. The launcher provides a reduction in clutter levels to a degree sufficient to allow detection of electromagnetic waves of interest that would otherwise not be expected to be detected. The launcher can be used in the evaluation of a high temperature furnace fire wall to create an erosion profile of the surface of the inner wall of the operating furnace.

  A method for assessing conditions and measuring erosion profiles and various material thicknesses includes setting an electromagnetic launcher that conforms and is in close proximity to the outer surface of the material under evaluation. The method further includes transmitting electromagnetic waves into the material and measuring the magnitude and phase of the waveform reflected from the discontinuity from the material over the frequency band. The method converts the measured data to the time domain, calibrates the data to the distance domain, and inside the material under evaluation to determine the reflected electromagnetic wave of interest, particularly the thickness of such material. And identifying data associated with waves reflected from the remote surface.

  By significantly reducing the level of clutter caused by reflection and resonance of propagating electromagnetic waves, as compared to standard techniques, and by determining the location of remote discontinuities from the material under evaluation The system and method can identify defects and measure the erosion profile of remote surfaces of such materials.

  Numerous advantages of the present invention may be better understood by those skilled in the art with reference to the accompanying figures.

1 is a schematic diagram of an exemplary embodiment of a system that uses a rolled-edge electromagnetic wave launcher. FIG. It is a figure which shows the one aspect | mode of the electromagnetic wave launcher which has two roll edges concerning one Embodiment. It is a figure which shows the one aspect | mode of the electromagnetic wave launcher which has two roll edges concerning one Embodiment. It is a figure which shows the one aspect | mode of the electromagnetic wave launcher which has two roll edges concerning one Embodiment. It is a figure which shows the one aspect | mode of the electromagnetic wave launcher which has two roll edges concerning one Embodiment. It is a figure which shows the design of a supply transition part. It is a plot which shows the intensity | strength of the reflected electromagnetic wave of noise, clutter, and the interested according to the scenario based on a hypothesis. FIG. 7 is a plot showing noise, clutter, and intensity of reflected electromagnetic waves of interest when using a launcher with and without roll edges. FIG. It is a perspective view of the planar electromagnetic wave launcher which concerns on another embodiment. It is a perspective view of the planar electromagnetic wave launcher which has the curved edge which concerns on another embodiment. FIG. 6 is a schematic diagram of a method for calculating the thickness of a dielectric according to any embodiment of the invention. 1 is a perspective view of an electric small electromagnetic wave launcher according to an embodiment of the present invention.

  The following description is directed to specific embodiments of the invention and is intended to enable those skilled in the art to practice the invention and is not intended to limit the preferred embodiments. It is intended to serve as a specific example of the invention. Those skilled in the art will readily understand that the concepts and specific embodiments disclosed as a basis for modifying and designing other methods and systems may be readily used to accomplish the same objectives of the present invention. will do. Those skilled in the art will also appreciate that such equivalent set does not depart from the spirit and scope of the present invention in its broadest form.

  For certain aspects of embodiments of the present invention, a material evaluation system is shown in FIG. The system is configured to evaluate the condition of the refractory material used as the furnace wall. Thus, the refractory material has an outer surface and an inner surface that is opposite the outer surface. The inner surface of the refractory material is proximate (ie, in contact with) a molten material such as glass, plastic, or steel, or any other material contained within the furnace. An electromagnetic (EM) wave launcher 10 including a feed end 12, a delivery end 14, and an extension 16 between adjacent feed end 12 and delivery end 14 is proximate to an area of the outer surface of the refractory material being evaluated. Be placed. The EM wave launcher 10 is designed to operate in a frequency band that is sufficiently large to cover the operating frequency band of the system. Specifically, as described in more detail below, the dimensions (width and height) of the orthogonal portion at the delivery end of the EM wave launcher 10, the length of the launcher (or alternatively the width of the induction angle and Height, as well as length), and the dielectric properties of the material occupying the volume inside the EM wave launcher 10 are shown in the EM wave launcher 10 for certain aspects of embodiments of the present invention, frequencies from 0.5 GHz to 10 GHz. All are selected to operate in a frequency band that is sufficiently large to cover the operating frequency band of the system. Similarly, the EM wave launcher 10 is designed to withstand the temperature range required for the outer surface, close to the furnace wall. In particular, the materials used to form the EM wave launcher 10 are such high in the EM wave launcher 10 (the area of the launcher that is exposed to the highest temperature, which is the area located in close proximity to the outer surface of the furnace). Selected to withstand the temperature. For example, the conductive material on the sides of the launcher and at the roll edge has a melting temperature point (including some suitable safety margin as may be selected by one skilled in the art) that is greater than the temperature of the outer surface of the furnace. Selected. Similarly, with respect to the dielectric occupying the launcher's internal volume, as described in more detail below, typical ceramic type materials withstand temperatures much higher than the maximum expected temperature of the outer surface of the furnace. For certain aspects of embodiments of the present invention, the dielectric substrate material also has properties similar to those of ceramic materials in terms of operating temperature. Finally, when a variable conductive material is used (again, as described in more detail below), the adhesive protective layer provides temperature separation to the variable conductive material. Using the EM wave launcher 10 for a surface having a temperature equal to 1600 ° F. in a few seconds that is sufficient to obtain the data needed for operation by selecting such materials It is preferable that However, during longer continuous operation, such materials would be able to withstand an ambient temperature limit of about 700 ° F. with surfaces reaching temperatures of up to about 1000 ° F.

  As used herein, “proximity” surface is also intended to refer to the outer surface of the material under evaluation that is proximate to the delivery end 14 of the EM wave launcher 10. Similarly, a “remote” surface is also intended to refer to the inner surface of the material under evaluation opposite the proximal surface that is in direct proximity to the delivery end 14 of the EM wave launcher 10. Thus, in the case of a furnace, the remote surface includes the inner surface of the outer wall of the furnace and the proximal surface includes the outer surface of the outer wall of the furnace.

  The supply end 12 includes a supply transition 18 that is electrically connected to a radio frequency (RF) transmission line, such as a coaxial cable 20. A computer-based processor 22 is also electrically connected to the coaxial cable 20. Thus, the coaxial cable 20 is electrically connected to the computer-based processor 22 at the first end and to the supply transition 18 at the second end. The coaxial cable 20 is selected to have a physical length from the computer-based processor 22 to the supply transition 18 so that between the first end and the second end of the coaxial cable 20. The propagation time of the propagating EM wave is greater than the propagation time of the EM wave from the supply transition 18 to the remote inner surface of the refractory material under evaluation and from there to the outer surface in the vicinity of the material. In other words, the propagation time of the EM wave propagating through the entire length of the coaxial cable 20 is reciprocated through the thickness of the refractory material to the propagation time of the EM wave propagating through the entire EM wave launcher 10. It is longer than the time obtained by adding the propagation time of the propagating EM wave.

  The computer-based processor 22 includes an RF subsystem 23, a signal processing subsystem, and executable computer code or software. The RF subsystem 23 is an adjustable signal source, at least one directional coupler, coherent, such as a voltage controlled oscillator or a frequency synthesizer, preferably operable in a frequency band anywhere from 0.25 GHz to 30 GHz. A detector, and at least one analog-to-digital converter. The signal processing subsystem includes data storage and data processing algorithms. Referring back to FIG. 1, note that the components of the computer-based processor 22 are not shown because these components are not as important in the description of this embodiment. Those skilled in the art will be able to have various arrangements of the RF subsystem 23 components, as well as additional components such as filters, impedance matching networks, amplifiers, non-coherent detectors, and other test equipment. It will be understood that it can be used as various methods for performing the RF subsystem 23 function of the computer-based processor 22 as known in

  The delivery end 14 of the EM wave launcher 10 is placed in physical contact with the refractory material to be evaluated. More specifically, the delivery end 14 physically conforms to the area of the adjacent surface of the refractory material with which the delivery end 14 is in physical contact (ie, the spacing between the delivery end 14 and the surface under inspection). It is desirable to be configured to minimize In other words, it is not desirable to have a gap or spacing greater than 2 mm between the surface of the delivery end 14 and the area of the adjacent surface of the refractory material where the delivery end 14 is in physical contact.

  The elongated portion 16 of the EM wave launcher 10 is desirably selected to have a physical length from the supply end 12 to the delivery end 14 so that the EM wave propagates from the supply end 12 to the delivery end 14. The propagation time of is greater than the propagation time of the EM wave propagating from the outer surface of the refractory material being evaluated to the remote, inner surface of the material. In other words, the propagation time of the EM wave propagating along the EM wave launcher 10 is desirably larger than the propagation time of the EM wave propagating through the thickness of the refractory material. Typical thickness values for furnace wall refractory materials range from 0.5 inches to 12 inches. Thus, depending on the target range for thickness measurement, the length of the extended portion 16 of the EM wave launcher 10 is typically somewhere in the range of 2 inches to 15 inches.

  2A-2D illustrate various aspects of one version of the EM wave launcher 10 used in FIG. In this embodiment, FIG. 2A shows an EM wave launcher 10 that is physically configured as a pyramid having a rectangular cross-section from the feed end 12 to the delivery end 16 with the two edges widened with the tip cut off. FIG. 2B and 2C are side views of the EM wave launcher 10 having a rectangular cross-sectional dimension of 0.2 inches × 0.13 inches at the feed end 12 and 2.5 inches × 4.25 inches at the delivery end 14. Indicates. Accordingly, the four side plates 24 a, 24 b, 24 c, and 24 d form the EM wave launcher 10. Each side plate 24a, 24b, 24c, and 24d is desirably made of a dielectric or conductive material. Typically, a conductive material is used that has a thickness in the range of 0.01 inches and 0.25 inches, more desirably between 0.05 inches and 0.1 inches. In the particular embodiment shown in FIG. 2D, a conductive material about 0.078 inches thick was used. Therefore, more specifically, the side plates 24a, 24b, 24c, and 24d of the EM wave launcher 10 form a surrounding structure that does not completely surround the internal volume of the EM wave launcher 10. The side plates 24 a, 24 b, 24 c and 24 d of the EM wave launcher 10 do not surround the internal volume at the supply end 12 and the delivery end 14 of the EM wave launcher 10.

  Referring again to FIG. 2A, in any cross-sectional view, the four edges 26 a, 26 b, 26 c and 26 d form a rectangular cross section of the EM wave launcher 10. The dimensions of such a rectangular cross-section of the EM wave launcher 10 are from the feed end 12 to transition points 28a, 28b, 28c, and 28d located along the elongated portion 16 between the feed end 12 and the delivery end 14. , Increase linearly. Thus, the shape of the EM wave launcher 10 corresponds to the shape of a uniform rectangular cross-sectional pyramid from the supply end 10 to the transition points 28a, 28b, 28c, and 28d. However, from transition points 28a, 28b, 28c, and 28d to the delivery end 14, the dimensions of the respective edges 26a and 26c opposite the rectangular cross section of the EM wave launcher 10 are as shown in FIG. 2D. , Increasing according to the curve described by the circular function with a radius of curvature of 0.78 inches. More specifically, the structure of the EM wave launcher 10 corresponds to the structure of a truncated pyramid of a rectangular cross section having opposite edges that extend into two ellipses or round into two ellipses. . Typical values for the thickness of the delivery end 14 may range between 0 and 0.25 inches. In this particular embodiment, delivery end 14 has a thickness of 0.078 inches. Similarly, the rounding of edges 26a and 26c begins at a point where the spacing between transition points 28a and 28b, or equivalently, between transition points 28c and 28d is 2.9 inches. Thus, transition points 28a, 28b, 28c, and 28d are located approximately 0.63 inches from delivery end 14.

  In addition, the EM wave launcher 10 is physically configured to have an impedance at the delivery end 14 that is well matched to the impedance of the proximal surface of the refractory material. The internal volume of the EM wave launcher 10 can be at least partially filled with a solid ceramic that is filled with a material having an impedance that matches well with a predetermined impedance of the refractory material during normal operating conditions of the furnace. This pre-determination can be obtained by measuring the dielectric properties of the refractory material at various temperatures using methods well known in the prior art. On the other hand, manufacturers of refractory materials can provide data on the dielectric properties of materials at various temperatures. These data may be used to determine the impedance of the material. The impedance of a refractory material is mainly determined by both the relative dielectric constant of the material and the dielectric loss tangent of the material. In general, the dielectric constant can range from 1 to 25 and depends on the specific type of material and the temperature of the material. Thus, the internal volume of the EM wave launcher 10 is partially or completely filled with a dielectric that fills a material with a dielectric constant similar to that of the refractory material, and is well matched to the impedance of the refractory material. Can do.

  The filling material used to fill the internal volume of the EM wave launcher 10 can be air, liquid, or solid. Desirably, the filler material is a mixture of solid powder or particulate material and the maximum size of each particle is no more than 10 percent of the wavelength of the EM wave propagating in the EM wave launcher 10 at the lowest frequency of operation. desired. More desirably, the filler material is a solid ceramic piece, such as a material that is adapted to fit within the interior volume of the EM wave launcher 10. Alternatively, the internal volume of the EM wave launcher 10 can be stratified from the supply end 12 to the delivery end 14 so that each layer is slightly different with respect to the dielectric constant of the filler material of any adjacent layer. A plurality of layers having different dielectric constants are arranged in an arrangement that is filled with a filling material having a dielectric constant and that adjusts the impedance from the supply end 12 step by step to the impedance of the refractory material evaluated at the delivery end 14. . Whenever necessary, lids or caps are placed at the supply end 12 and delivery end 14 to prevent filling material from exiting the internal volume of the EM wave launcher 10 during operation or operation of the EM wave launcher 10. . Those skilled in the art will appreciate that the cap disposed at the delivery end 14 has a dielectric property similar to that of the filler material to prevent substantial discontinuity to the EM wave propagating through the cap. Understand that must be created in. Similarly, the cap located at the supply end 12 must be made of a material according to the specific design of the supply transition 18.

  FIG. 3 shows the design of the supply transition 18 using a cap 30 formed of a shell of conductive material having a thickness of about 0.1 inch. Cap 30 is surrounded by a shell to form an air-filled cavity and has a semi-circular cross section of a first dimension and a rectangular cross section of a second dimension that is perpendicular to said first dimension. . In this embodiment, the semi-circular cross-section is defined by a semi-circular portion 32 having an inner radius of about 0.75 inches and a straight portion of about 1.6 inches, where the straight portion of about 1.6 inches is a gap. A rectangular section having a width of about 1.6 inches and a length of about 1.3 inches, the first section 34a and the second section 34b having substantially the same dimensions separated by 35 Defined by another straight line (not shown in FIG. 3).

  The cap 30 has a first circular opening on one side of the semi-circular portion 32 that is just large enough to allow the coaxial cable 20 to enter the inside of the cavity. The outer conductor 36 of the coaxial cable 20 is electrically connected to both the semicircular portion 32 of the cap 30 and the conductive side plate 24 a of the EM wave launcher 10 at the supply end 12. The pin or probe 38 is formed by extending the central conductor of the coaxial cable 20 beyond the conductor outside the coaxial cable 20 inside the cavity, in which case the length of the pin is about 0.1. Inches. Similarly, the gap 35 of the cap 30 defines a second opening that separates the straight portion 34a from the straight portion 34b. The size of the gap 35 is large enough to just allow the tip of the cut end of the EM wave launcher 10 closer to the supply end 12 to fit into the cavity. In this embodiment, the side plates 24a and 24c of the EM wave launcher 10 are made of a conductive material. Therefore, the side plate 24a of the EM wave launcher 10 is electrically connected to the second portion 34b, and the side plate 24c of the EM wave launcher 10 is electrically connected to the first portion 34a. Similarly, the conductor 36 outside the coaxial cable 20 is electrically connected to the first portion 34a. Further, the pin 38 is electrically connected to the second portion 34b. Thus, the EM wave launcher 10 can be excited by the pin 38 of the coaxial cable 20 in a cavity-backed feeding pin configuration. Typically, the pin 38 is positioned at a distance from the cap equal to a quarter wavelength corresponding to the center frequency of the frequency band of the EM wave propagating along the EM wave launcher 10.

  One skilled in the art will appreciate that the semi-circular portion 32 can be shaped according to various configurations such as an ellipse, a plane, or other smooth function. Similarly, one or more portions of the cap 30 can be removed in certain structures and the cavities can be filled with a dielectric. Further, the dimensions of the straight portions 34a and 34b may be designed in combination with the supply end 12 of the EM wave launcher 10 to reduce undesirable resonance effects.

Operation According to a further aspect of embodiments of the present invention, the method using the material evaluation system of FIG. 1 is based on the principle of EM wave propagation. The computer-based processor 22 controls a tunable RF signal source that operates in a frequency band that suitably passes through the refractory material with a sufficiently low loss, which frequency band is preferably Is a frequency band somewhere between 0.25 GHz and 30 GHz, more preferably somewhere between 0.25 GHz and 10 GHz. The RF signal source excites at least one propagation mode within the EM wave launcher 10 so that a plurality of EM waves can propagate from the supply end 12 to the transmission end 14 in the frequency band of interest. Is transmitted to the supply transition section 18. The band of the EM wave propagating in the EM wave launcher 10 is normally selected to be 2 GHz at the lowest as required by the user.

  Upon reaching the EM wave launcher 10, the RF signal source from the computer-based processor 22 propagates the EM field of the RF signal source propagating along the coaxial cable 20 in a propagation mode EM activated inside the EM launcher 10. Due to the adaptation to the field, the supply transition 18 will experience an initial discontinuity. This initial discontinuity causes a reflection of some of the RF signal source back to the computer processor 22.

  Furthermore, when the EM wave propagating along the EM wave launcher 10 reaches the proximal, outer surface of the refractory material, the first portion of the EM wave passes through the proximal, outer surface of the material, and the remote of the material. Propagating inside the material until it reaches the inner surface. The second part of the EM wave is reflected back from the outer surface, close to the refractory material, to the EM wave launcher 10, and a portion of the reflected EM wave propagates until it reaches the computer processor 22. When the first part of the EM wave reaches the remote, inner surface of the refractory material, the third part of the EM wave may pass through the molten material contained within the furnace and the interior of the molten material Propagate to. The fourth part of the EM wave reflects back from the remote, inner surface of the refractory material back to the EM wave launcher 10, and a portion of the reflected EM wave propagates until it reaches the computer processor 22. The second part of the EM wave reflects as a result of the wave propagating through a media discontinuity between the internal volume of the EM wave launcher 10 at the delivery end 14 and the refractory material. Similarly, the fourth part of the EM wave reflects as a result of the wave propagating through a media discontinuity between the refractory material and the molten material.

  Furthermore, EM waves propagating through the refractory material can experience discontinuities due to the presence of non-uniform areas or defects inside the refractory material. Thus, some of the EM waves are reflected back from the defects inside the refractory material back to the EM wave launcher 10 and some of the reflected EM waves propagate until reaching the computer processor 22.

  Furthermore, EM waves propagating along the EM wave launcher 10 experience further edge discontinuities at the delivery end 14. More specifically, the edge discontinuity, as shown in FIG. 2A, is a medium in which the wave surrounds the inner volume of the EM wave launcher 10 at the delivery end 14 and the edge surface, such as the outer surface, in the vicinity of the refractory material. And at the edges 26a, 26b, 26c, and 26d corresponding to the delivery end 14, as a result of propagating through a media discontinuity between the EM wave launcher 10, such as air. Accordingly, a part of the EM wave is reflected from the edge back to the EM wave launcher 10, and a part of the reflected EM wave propagates until reaching the computer processor 22.

  Further, the EM wave reflected from the edges 26a, 26b, 26c, and 26d corresponding to the sending end 14 reaches one or more of the other edges a plurality of times, due to reflection of the plurality of edges of the EM wave, It may create undesirable “resonance” or “reflection” effects. Eventually, some of the plurality of reflected EM waves reach the computer processor 22.

  Similarly, any reflected waves within the refractory material, within the EM wave launcher 10 or between the supply end 12 and the computer processor 22 may cause the outer surface, the delivery end 14, and the proximity of the refractory material. Affected by any discontinuity at the supply end 12. In other words, the discontinuous effect is the direction of propagation of the EM wave, either from the computer processor 22 to the remote, inner wall of the refractory material, or from the refractory material, from the inner wall to the computer processor 22. Regardless, it can affect the propagation of EM waves. Thus, multiple EM wave reflections can occur that can create resonance effects and can adversely affect the ability of the computer processor 22 to detect the reflected EM waves of interest. In other words, there are inherently multiple spurious signals or unwanted EM wave reflections that can cause serious performance problems in the material evaluation system. A commonly used term for the combined effect of such spurious signals, or unwanted EM wave reflections, is “clutter”.

  In particular, the first EM wave of interest for assessing the condition of the refractory material is the original reflected EM wave from the discontinuity between the delivery end 14 and the outer wall in the vicinity of the refractory material; Establishing a reference for determining the thickness of the refractory material or determining the location of defects within the material. The second EM wave of interest is the original reflected EM wave from the discontinuity between the remote wall of the refractory material, the inner wall and the molten material inside the furnace, and determines the thickness of the refractory material To do. The third EM wave of interest is the original reflected EM wave from the defect discontinuity inside the refractory material and determines the position of the defect.

  Correspondingly, several different elements are the main factors for the overall clutter of the system. The first element corresponds to the reflected RF signal from the supply transition 18 to the computer-based processor 22. The second element corresponds to multiple RF signal reflections or resonances between the supply transition 18 and the computer-based processor 22. The third element corresponds to reflected EM waves from the edges 26a, 26b, 26c, and 26d at the delivery end 14 to the computer-based processor 22. The fourth element corresponds to multiple edge reflections or resonances of the EM wave from the edges 26a, 26b, 26c, and 26d at the delivery end 14 to the computer-based processor 22. The fifth element corresponds to multiple reflections or resonances of the EM wave reaching the computer-based processor 22 between the proximal outer wall of the refractory material and the remote inner wall of the refractory material. . The sixth element corresponds to multiple reflections or resonances of EM waves reaching the computer-based processor 22 between the defects inside the refractory material and the outer walls in the vicinity of the refractory material. The seventh element corresponds to multiple reflections or resonances of EM waves reaching the computer-based processor 22 between the defects inside the refractory material and the remote, inner wall of the refractory material. The eighth element corresponds to multiple reflections or resonances of the EM wave reaching the computer-based processor 22 between the supply end 12 and the adjacent, outer wall of the refractory material. The ninth element corresponds to multiple reflections or resonances of EM waves that reach the computer-based processor 22 between the supply transition 18 and the supply end 12.

  In this embodiment, the RF signal or EM wave received by the computer-based processor 22 is the in-phase (I) and quadrature (Q) components of the received RF signal or EM wave relative to the reference version of the original RF signal source. Can be passed through a coherent detector that provides a voltage proportional to, so that both magnitude and relative phase can be measured. A reference version of the original RF signal source is provided by samples obtained using a directional coupler. The analog-to-digital converter outputs digital data proportional to the I and Q voltage outputs of the coherent detector. The digital data is then read, recorded and processed by a computer based processor 22. The computer-based processor 22 further calibrates the processed data and displays the results to the user. The computer-based processor 22 generates executable computer code configured to measure received reflected EM waves to generate frequency domain data and convert the frequency domain data to time domain data. Have. In addition, the computer-based processor 22 calibrates the time domain data to the distance domain data, identifies peaks in the distance domain profile associated with the EM wave of interest reflecting from the refractory material, and generates the EM wave of interest. Determine the progress of.

  Thus, the computer-based processor 22 can determine the relative time delay between the received RF signal or received EM wave and the original RF signal source. The time domain data can be used to determine the relative time of arrival of each EM wave of interest and clutter elements. Of particular importance is that any EM wave of interest is received during the time interval between the arrival of the first EM wave of interest and the arrival of the second EM wave of interest, used as a reference. It is to be done. In other words, any information about the state of the refractory material arrives at the computer-based processor 22 during the time interval. Thus, only the clutter elements that can arrive during this time interval in the computer-based processor correspond to the second, third, fourth, sixth, eighth, and ninth clutter elements. Is the clutter element.

  Further, the propagation time of the EM wave propagating throughout the length of the coaxial cable 20 is varied throughout the EM wave launcher 10 including the propagation time of the EM wave propagating back and forth through the thickness of the refractory material. By selecting the length of the coaxial cable 20 to be greater than the propagation time of the propagating EM wave, the plurality of reflections corresponding to the second clutter element are delayed from any EM wave of interest by the computer. Arrives at the base processor 22. Similarly, the length of the elongated portion 16 of the EM wave launcher 10 is such that the propagation time of the EM wave propagating along the EM wave launcher 10 is greater than the propagation time of the EM wave propagating through the thickness of the refractory material. By selecting the length, the plurality of reflections corresponding to the eighth clutter element arrive at the computer-based processor 22 later than any EM wave of interest.

  The effect of the resonance generated by the sixth clutter element, ie the resonance of the EM wave arriving at the computer-based processor 22 between the defect inside the refractory material and the outer wall in the vicinity of the refractory material, The computer-based processor 22 arrives at the same interval time as the EM wave of interest only if it is positioned closer to the outer wall, closer to the refractory material than the remote inner wall of the refractory material. However, this effect is only noticeable when defects are present at a distance from the outer wall in close proximity of the material that is less than half the thickness of the material. One skilled in the art will appreciate that measurements at multiple frequencies and known signal processing techniques can determine when this situation occurs.

  As shown in FIG. 3, the utilization of the supply transition supported by the cavity in this embodiment is the effect of the ninth clutter element, ie the EM wave of interest between the supply transition 18 and the supply end 12. EM wave resonances that can reach the computer-based processor 22 at the same time interval may be reduced. Due to the inherent broadband conditions of the EM wave launcher 10, the important quarter wavelength distance is difficult to maintain across the entire frequency band of operation. Thus, the effect of resonance is still significant but can be partially eliminated.

  Therefore, the most relevant and simultaneously the most difficult clutter elements to remove from the system are those for edges 26a, 26b, 26c, and 26d at the delivery end 14. These are the third and fourth clutter elements as described above.

  The executable computer code of the computer-based processor 22 is based on the known speed of the EM wave that travels along the coaxial cable 20 and the EM wave launcher 10 and travels through the refractory material under evaluation. The area data can be calibrated to the distance area data. Also, the reference or zero distance value corresponds to the transition between the delivery end 14 of the EM wave launcher 10 and the outer surface in the vicinity of the refractory material. FIG. 4 shows a plot of received EM wave magnitude as a function of distance in a computer-based processor 22. This shows the situation expected in the system shown in FIG. 1 and there are defects inside the refractory material. In determining the EM wave of interest in the computer-based processor 22, the effect of the clutter element can be significant. The solid curve represents the magnitude of the EM wave of interest plus system noise. The dashed curve represents the size of the clutter with system noise added. Note also that the distance interval of interest is only a distance corresponding to the thickness of the refractory material, in this case about 6 inches. If the size of the cluttered with noise is approximately the same or greater than the magnitude of the EM wave of interest associated with both the defect and the thickness of the refractory material, as shown in FIG. Waves cannot be detected by the computer-based processor 22. Thus, the EM wave of interest associated with a defect in a refractory material, schematically illustrated at a distance of 4 inches in FIG. 4, and the EM wave of interest associated with a remote, inner wall of the material, schematically illustrated at a distance of 6 inches. Neither can be detected due to the effect of clutter. Therefore, the thickness of the refractory material cannot be determined. In this case, the magnitude of the EM wave of interest associated with the outer surface in the vicinity of the refractory material is above the magnitude of the noisy clutter, so it is associated with the outer surface in the vicinity of the refractory material. Only the magnitude of the EM wave of interest can be determined. However, it is not very useful to determine the magnitude of only the EM wave of interest associated with the outer surface in the vicinity of the material.

  It is therefore very important to reduce the size of the cluttered with noise to a level below the thickness of the refractory material from which the defect or material condition can be determined and the magnitude of the EM wave of interest. is there. Typically, in most applications involving the evaluation of refractory materials, the clutter is so large that the material evaluation system becomes unreliable and generally cannot determine the condition of the material. In addition, known techniques such as those based on subtraction of reflected EM wave measurements obtained at various locations on the furnace wall surface are not effective in reducing clutter. The reason for the ineffectiveness of the technique is the variability of the clutter component associated with each of the measurements, due to variations in the surface temperature, dielectric loss tangent, and EM wave launcher 10 and furnace wall surface placement from measurement to measurement. is there.

  1 and 2 show a design of the EM wave launcher 10 that significantly reduces clutter elements for the edges 26a, 26b, 26c, and 26d at the delivery end 14. FIG. As indicated above, the clutter elements associated with edges 26a, 26b, 26c, and 26d at the delivery end 14 are most relevant to suppression from the system and at the same time are the most difficult clutter elements. FIG. 5 shows actual measurement data for a 10 inch thick refractory material attached to a running furnace. In this case, the thickness of the refractory wall is selected to be free of defects, and there are no reflected EM waves from the defects and reflected EM waves from the remote, inner surface of the furnace wall are computer-based processors. It is selected to decay without reaching 22. Thus, FIG. 5 shows only the measurement results of clutter plus noise for an EM wave launcher 10 having a roll edge and a substantially similar EM wave launcher 10 having no roll edge. The solid curve represents the magnitude of clutter plus noise in the time domain data processed using the EM wave launcher 10 having a roll edge as described above. The dashed curve represents the magnitude of clutter plus noise when a substantially similar EM wave launcher 10 without roll edges is used. As shown in FIG. 4, the effect of using an EM wave launcher with a roll edge is the area where the reflected EM waves of interest related to the outer surface of the furnace wall are expected to appear, eg, time In a region exceeding 1 nanosecond, clutter plus noise is reduced by about 20 dB to 30 dB or more.

  Another advantage of using an EM wave launcher with a roll edge is to reduce clutter plus noise by as much as 10 dB for reflected EM waves of interest associated with the outer surface of the furnace wall in close proximity. Also, since the system noise is substantially the same in both cases, when using the EM wave launcher 10 with and without roll edges, the clutter plus noise reduction seen in FIG. , Mainly corresponds to the reduction of clutter level.

  With respect to FIG. 1 where a single EM wave launcher 10 is used, such a system is commonly referred to as a monostatic structure. An additional EM wave launcher 10 may be added only to receive reflected EM waves. In such a structure, commonly known as a bistatic structure, a first “active” EM wave launcher 10 is used to deliver EM waves to the material under evaluation, as shown in FIG. It is done. A second “passive” EM wave launcher 10 is positioned adjacent to the first EM wave launcher 10. The second EM wave launcher 10 only receives reflected EM waves. Thus, the reflected EM wave returns to the computer-based processor 22 using a path different from the path used for the transmitted EM wave. This provides an inherent separation between the transmitted EM wave and the received EM wave. Unlike FIG. 1, this bistatic structure separates the transmitted and received EM waves that originate from and toward the computer-based processor 22 for coherent detection of reflected EM waves. No additional components such as directional couplers are required.

  In the bistatic structure, the center point of the virtual plane including the transmission end 14 of the first EM wave launcher 10 is as close as possible to the corresponding center point of the plane including the transmission end 14 of the second EM launcher 10. Preferably, both delivery ends are arranged to conform in contact with the adjacent, outer surface of the refractory material. One reason for the desired minimal separation between EM wave launchers in this structure is that the distance carried by the reflected EM wave is shorter and requires less loss. The second reason is that the second EM wave launcher can receive more reflected EM waves, particularly those EM waves that reflect at an angle close to 180 ° with respect to the transmitted EM wave. Further, in order to receive a reflected EM wave having substantially the same electric field polarization as the transmitted EM wave, the direction of the first EM wave launcher 10 relative to the second EM wave launcher 10 is The edges 24a, 24b, 24c, and 24d at the transmission end 14 of the first EM wave launcher 10 are substantially parallel to the edges 24a, 24b, 24c, and 24d at the transmission end 14 of the second EM wave launcher 10. Can be selected. A person skilled in the art will recognize that the relative direction of the first EM wave launcher 10 relative to the second EM wave launcher 10 is cross-polarization, cross-polarization, or any combination thereof compared to the electric field polarization of the transmitted EM wave. It will be appreciated that it may need to be tuned to receive reflected EM waves having substantially the desired electric field polarization. Further, the second EM wave launcher is not required to be the same or similar to the first EM wave launcher.

  With respect to a further aspect of the present invention in which transverse electromagnetic field (TEM) waves are used exclusively, the EM wave launcher 10 can be configured to have only two opposing side plates made of a conductive material. In other words, in the first structure, only the side plates 24a and 24c are made using a conductive material. In the second structure, only the side plates 24b and 24d are made using a conductive material. The desired thickness dimensions for these two different structures are the same as for a structure with four conductive side plates, as shown in FIG. Thus, more specifically, the first group of two opposite side plates of the EM wave launcher 10 is made of a conductive material, and the second group of two opposite side plates may be removed. May be made of dielectric materials, or other materials as known in the prior art, or simply replaced by opposing surfaces of a solid filled dielectric material such as a ceramic.

  Further, instead of being made using a conductive material, the EM wave launcher 10 may be separately provided with at least two opposing side plates on which a material having variable conductivity is disposed. Those skilled in the art will appreciate the use of one or more coatings of conductive material applied to the dielectric that fills the inner volume of the EM wave launcher 10 with a desired profile of variable conductivity along the side plate. It will be understood that it can be used to achieve Alternatively, a film of uniform thickness and variable conductivity can be placed between the supply end 12 and the delivery end 14. More specifically, the variable conductive material may be disposed on at least the side plates 24a and 24c, or at least on the side plates 24b and 24d. In this alternative embodiment, the internal volume of the EM wave launcher 10 is filled with a solid dielectric, preferably ceramic. The variable conductive film is disposed on the two opposing side surfaces of the dielectric from the supply end 12 to the delivery end 14 to form the side plates 24a, 24b, 24c, and 24d of the EM wave launcher 10. In this construction, the first end of the various conductive materials is positioned closer to the supply end 12 and the second end of the variable conductive material is positioned closer to the delivery end 14. . Thus, the electromagnetic wave propagates through the EM wave launcher 10 within a region partially surrounded by the variable conductive material, and the conductivity is a function of the distance from the point on the variable conductive material to the delivery end 14. fluctuate. Alternatively, multiple portions of the conductive film, each having variable conductivity, are arranged sequentially from lower conductivity to higher conductivity, as a function of the distance from the first to the last of the portions An increasing conductive profile can be created. The thickness of each individual layer of conductive film is preferably in the range between 0.001 inch and 0.1 inch.

  Typically, sheet resistance characterizes the degree of conductivity of a thin film layer of uniform thickness material. Larger sheet resistance corresponds to lower conductivity and vice versa. In the structure just described, the sheet resistance of the variable conductive material is such that the second end of the variable conductive material closer to the delivery end 14 from the first end of the variable conductive material closer to the supply end 12. To the end, it increases according to an exponential function.

  In particular, the minimum value of the sheet resistance of the variable conductive material at the first end closer to the supply end 12 is preferably less than 1 ohm / square. More desirably, the minimum value of the sheet resistance is the same as the sheet resistance of a conductive material such as copper or silver. On the other hand, the maximum value of the sheet resistance of the variable conductive material at the second end, closer to the delivery end 14, is preferably somewhere in the range between 50 ohms / square and 1000 ohms / square. . More desirably, the minimum value of the sheet resistance is the same as the sheet resistance of a dielectric such as ceramic. In other words, the variable conductive material acts as a conductive material that is closer to the supply end 12 and transitions in steps to have the desired maximum sheet resistance value as the variable conductive material approaches the delivery end 14. To do. This variable conductive profile provides a significant reduction in EM wave reflection from the edge at the delivery end 14. Thus, the variable conductive profile provides a significant reduction in clutter resulting from EM waves reflecting from the edge at the delivery end 14.

  The variable conductive profile described above is almost the same for each of the at least two opposing side plates 24a and 24c or 24b and 24d of the EM wave launcher 10. However, one skilled in the art will appreciate that different profiles within each side plate can be used. In general, the sheet resistance profile of a variable conductive material may increase according to a step, elliptic function, exponential function, or a smooth transition function, or any combination thereof, and the variable conductivity closer to the feed end 12. It can be designed to reduce clutter from the first end of material to the second end of the variable conductive material closer to the delivery end 14.

  An important problem with using a resistive film placed relatively close to the delivery end 14 is that, under normal operating conditions, the refractory material reaches a temperature of several hundred degrees Celsius on the outer surface, close to the furnace. Is to get. The delivery end 14 is in physical contact with the hot material. Therefore, often the film can be physically damaged unless protected. The conductive film can be sandwiched between two layers of high temperature adhesive to protect the film. This three-layer structure is disposed on the surface of at least two opposite side surfaces of the dielectric filling the internal volume of the EM wave launcher 10 from the supply end 12 toward the delivery end 14, and the side plate 24 a of the EM wave launcher 10. And 24c can be formed. In this embodiment, the dielectric and the three-layer structure were cured at a temperature of about 300 degrees Celsius for 2 hours. Desirably, each of the film and adhesive layers has a thickness ranging anywhere between 0.001 inches and 0.01 inches. More desirably, the adhesive layer has electrical properties similar to those of the dielectric. In addition, high temperature ceramic cement or other corresponding material may be placed on top of the three-layer structure for enhanced protection. Thus, compact packaging not only protects the film from physical damage due to the high temperatures experienced by the delivery end 14 and from handling during installation and operation of the EM wave launcher 10. Provided to keep the film in place during operation. A person skilled in the art can use various types of commercially available adhesives and cement materials, which are generally at temperatures in the range of 200 to 500 degrees Fahrenheit 1 It will be appreciated that it has a time to cure between 3 hours and 3 hours.

  Since the effect of configuring the EM wave launcher 10 using a variable conductive material as described above is significant in reducing clutter elements related to the edge of the transmission end 14 of the EM wave launcher 10, the variable conductivity can be reduced. Embodiments using materials may not require a widened or rolled edge at the delivery end 14. Thus, either the first structure using a roll-edge EM launcher or the second structure using an EM wave launcher with at least two side plates of variable conductive material can greatly enhance edge reflection in most applications. Can be used to reduce Of course, the third structure, which combines both techniques for reducing edge reflections, provides further improvements to the material evaluation system.

  The delivery end 14 of the EM launcher 10 may extend according to the outer surface topology of the material being evaluated. Alternatively, the roll edge at the delivery end 14 of the EM wave launcher 10 may be a circular function or other that extends sufficiently smoothly away from the transition points 28a, 28b, 28c, and 28d to reduce the effects of edge reflections. Can follow functions.

  The entire material evaluation system may be packaged into a single portable unit where the operator initiates EM wave transmission over the frequency band by enabling the switch. More specifically, the entire material evaluation system may be enclosed in a single portable unit. The unit can evaluate the condition of the furnace wall at a single point and record the information in its internal memory. Alternatively, an EM wave launcher with a subset of the components of the material evaluation system is only for delivering EM waves and for measuring, recording and storing the intensity and phase of the EM waves to the EM wave launcher. Can be integrated into a single assembly. Subsequently, the stored data is stored in a computer-based processor to determine the condition of the material under evaluation and ultimately measure the thickness using a portable memory drive or by a flexible cable. 22 can be transmitted. Alternatively, the data can be transmitted wirelessly in real time or at a convenient opportunity. In addition, the portable unit includes data processing components and a display that displays the thickness of the furnace wall and / or the distance from the adjacent surface outside the refractory material to the discontinuities incorporated into the material under evaluation. obtain. The portable unit may be designed to manually scan the furnace wall area while measuring at multiple locations. In addition, the EM wave launcher 10 can be used periodically to evaluate one or more of the materials under evaluation, or to continuously monitor the condition of the material under evaluation, It can be permanently installed and fixed on the outer, proximal surface. Alternatively, the area of the proximate surface outside the material under evaluation may move the EM wave launcher during operation while maintaining physical contact with the proximate surface outside the material under evaluation. Can be scanned.

  The RF front end of the RF subsystem 23 of the computer-based processor 22 may be integrated with the supply transition 18 of the EM wave launcher 10. In other words, the coaxial cable 20 is no longer required and can be removed from the system. In this situation, any multiple reflections between the RF front end and the supply transition 18 will arrive at the computer-based processor 22 before any of the reflected EM waves of interest. Alternatively, the coaxial cable 20 is arranged according to a predetermined physical route to produce the maximum stability of the RF signal or EM wave traveling through the cable. Further, such stability can be achieved by physically attaching the cable to the support structure so as to minimize any movement of the coaxial cable 20. Similarly, preventing coaxial cable 20 from following a route that requires the cable to bend beyond a certain angle from a straight route can help reduce the overall clutter of the system.

  Those skilled in the art will recognize that the EM wave launcher 10 is comprised of antennas, waveguides, dielectrics, conductive materials, materials with variable conductivity, metamaterials, or different geometric arrangements thereof. It will be understood that a plurality of devices and materials may be implemented in a variety of structures, including one or more, in any combination.

  In particular, FIG. 6 shows a preferred structure of a planar EM wave launcher 60 that includes a bow tie antenna having a first layer 62a of conductive material and a second layer 62b of conductive material, the edges of both layers 62a and 62b. Are linearly tapered to have a triangle and are disposed on the top surface of the dielectric substrate 64. The EM wave launcher 60 is commonly referred to as a “balanced unbalanced transformer” and is supplied by a balanced-unbalanced device that adapts the impedance of the unbalanced transmission line, such as a coaxial cable, to the input impedance of the bowtie antenna. In this structure, the input impedance of the bow tie antenna is substantially matched to the impedance of the outer surface in the vicinity of the refractory material. The substrate 64 has a back side surface in which a layer of conductive material is placed over the back side surface to form a ground plane, and two openings that allow the balun to feed the bow tie antenna. Have. Usually, as is well understood by those skilled in the art, these openings are made through the minimum dimensions or thickness of the substrate 64, as well as allowing the wire to pass through each opening, and the layers At a point at its closest distance, in this case about 0.1 inch, just large enough to electrically connect the balun to each layer 62a and 62b. In this structure, the dimensions of the substrate 64 are 4 inches long, 3 inches wide, and 0.27 inches thick. Each layer 62a, 62b has a maximum width of about 2.7 inches and a length of about 1.95 inches. The thickness of each layer 62a, 62b is unique to the foregoing corresponding to the film or coating of conductive material applied to the dielectric substrate. Further, the substrate 64 may have a dielectric constant somewhere between 1 and 150 and a dielectric loss tangent somewhere between 0 and 1.

  In a general evaluation of the material, the top surface of the substrate 64, including the bowtie antenna, transmits reflected EM waves back to the computer-based processor 22 and to send EM waves originating from the computer-based processor 22 into the fire wall. For reception, it is placed in conformity with the outer surface of the refractory material in proximity. One skilled in the art will appreciate that layers 62a and 62b may be implemented using a variable conductive material as described in previous embodiments of EM wave launcher 10. Similarly, the shape of the layers 62a and 62b may be other than a triangular shape with straight edges, curved edges that follow a specific function, or a combination thereof.

  Similarly, FIG. 7 includes a first plane part 64a, a first curved edge part 64b, a second curved edge part 64c, a second plane part 64d, and a third plane part 64e. FIG. 7 shows the structure for the planar EM wave launcher 60 of FIG. The first planar portion 64a has a first dimension along the width of the substrate 64 to reach the width of the substrate 64, in this case about 3 inches, and in this case transition points 66a and 66b, And the second dimension along the length of the substrate 64 to reach transition points 66a, 66b, 66c, and 66d, where the distance between transition points 66c and 66d is about 4 inches. , Extending across the plane from the bowtie supply area.

  As the first curved edge 64b and the second curved edge 64c extend along the length of the substrate 64 from the bowtie antenna feed point, the portions 64b and 64c become 1/4 of the circumference. Follow the circular path with a radius of curvature of about 1.6 inches, and curve toward the back surface of the substrate 64 to reach transition points 68a, 68b, 68c, and 68d. In other words, the distance along the curved path of the substrate 64 between the transition points 66a and 68a is about 2.51 inches. This is substantially the same distance between transition points 66b and 68b, between transition points 66c and 68c, and between transition points 66d and 68d. Similarly, this is the same length of portion 64b and portion 64c along the curved path of substrate 64. At transition points 68a and 68c, the second planar portion 64d begins to extend the length of the substrate 64 by about 0.5 inches. Accordingly, at transition points 68b and 68d, the third planar portion 64e begins to extend the length of the substrate 64 by about 0.5 inches. Therefore, the second plane part 64d and the third plane part 64e are substantially orthogonal to the first plane part 64a.

  In the structure shown in FIGS. 6 and 7, the most powerful clutter element corresponds to multiple reflections at the edge of the bowtie antenna. The dimension of the curved edge of the structure of FIG. 7 is selected to increase the propagation time of the EM wave propagating over the surface of the substrate 64, which time is remote from the outer surface from the outer surface in the vicinity of the refractory wall. The propagation time of the EM wave propagating to the inner surface is longer. Thus, the clutter effect associated with multiple reflections of EM waves from the edge of the bow tie antenna is greatly reduced. Those skilled in the art will appreciate that in the structure of FIG. 7, the edges of layers 64b and 64c may be tapered to follow an elliptical function, an exponential function, a smooth transition function, or any combination thereof. right. Further, the length of the portions 64d and 64e can be adjusted for the ultimate purpose of reducing clutter.

  Furthermore, in each of the foregoing structures, those skilled in the art will understand that a particular single signal processing method may be selected according to the estimated thickness of the material being evaluated. For example, a signal processing method based on a Fourier transform can be used to process data received by a computer-based processor 22, particularly with respect to evaluation of walls with a thickness greater than 6 inches. On the other hand, signal processing methods based on super-resolution algorithms are desirable for the evaluation of walls with thicknesses less than 3 inches. Alternatively, a hybrid signal processing method comprising one or more single signal processing methods may be used according to further factors including system operation and bandwidth frequency, furnace operation temperature, and the type and quality of the refractory material. Can be.

  Similarly, in each of the foregoing structures, the delivery end of the EM wave launcher 10 is impedance matched to the material under evaluation as described elsewhere herein, further helping to suppress clutter.

  For each of the foregoing structures, the method shown in FIG. 8 for determining the thickness of the material under evaluation, such as a refractory material, may be performed according to the following.

  1. In step 810, installing the EM wave launcher by locating the delivery end of the EM wave launcher in conformity with and proximate to the proximity surface outside the material under evaluation to maximize physical contact. Where maximizing physical contact corresponds to minimizing the gap between the delivery end of the EM wave launcher and the adjacent surface outside the material under evaluation, During operation of the EM wave launcher, the EM wave is delivered to an adjacent surface outside the material under evaluation.

  2. Next, in step 820, EM waves are transmitted from the EM wave launcher to the outer surface of the material under evaluation by exciting the EM wave propagation mode into the EM wave launcher over the transmission frequency band, and accordingly Generating an EM wave propagating into the EM wave launcher from the supply end of the EM wave launcher to the transmission end of the EM wave launcher over the frequency band;

  3. Next, in step 830, measure the intensity and phase of the EM wave into the EM wave launcher over the frequency band as a result of propagation into the outer surface of the material being evaluated by the EM wave launcher. Step to do.

  4). Next, in step 840, store the measured intensity and phase frequency domain data of the EM wave into the EM wave launcher.

  5). Next, transmitting the recorded frequency domain data in step 850 to a computer-based data processor.

  6). Next, in step 860, the frequency domain data recorded by performing a mathematical inverse Fourier transform or other model-based inverse spectral transformation method using a computer-based data processor is converted into time domain data. Step to convert to.

  7). Next, in step 870, the time domain data is calibrated to distance domain data according to the known or estimated phase velocity of the EM wave in the material under evaluation, and the noise level of the calibrated distance domain data A reference point is defined in the profile of the distance region corresponding to the physical length between the supply end of the EM wave launcher and the outer surface of the material being evaluated, the adjacent surface, based on the peak value above the clutter plus A step in which a reference point may be associated with an EM wave that reflects from a near surface outside the material under evaluation into an EM wave launcher.

  8). Next, in step 880, data for the calibrated distance region to identify a peak value between the reference point and the known original thickness of the material under evaluation above the clutter plus the noise level. Wherein the peak value may be associated with an EM wave reflecting from a remote surface into the EM wave launcher inside the material under evaluation.

  9. Finally, in step 890, determining the distance from the peak value identified in step 880 to the reference point, which distance is the thickness of the material under evaluation (proximity outside the material under evaluation). Corresponding to the distance between the surface and the remote surface inside the material under evaluation).

  For those skilled in the art, the steps shown above are the implementation of a material evaluation system for a particular structure and measurement equipment, operating frequency band, EM wave launcher type, operating conditions, ambient environment, and a given use case. It will be appreciated that other constraints such as the available area and location for can be adjusted accordingly. In particular, the required EM wave intensity and phase measurements over a high dynamic range (which may exceed 90 dB) can be achieved in several ways, such as through the use of a network analyzer, S11 of the S parameter (scattering parameter) can be measured using the structure (single device that both emits EM wave and receives EM wave) or bistatic structure (transmits EM wave over frequency band) S21 of the S parameter can be measured using the first device and the second device receiving the EM wave.

  Furthermore, those skilled in the art, while evaluating calibrated distance region data, have an intermediate peak value that exceeds the clutter plus the noise level as EM waves reflected from nearby surfaces outside the material under evaluation. It will be appreciated that it may appear between the associated reference point and the peak value associated with the EM wave reflected from the remote surface inside the material under evaluation. It is understood that the intermediate peak value may be associated with a defect in the material under evaluation that exists between the near surface and the remote surface inside the material under evaluation, outside the material under evaluation.

  Further, calibrating time domain data to distance domain data includes subtraction of delay times (distances) associated with EM wave launchers and cables. In addition, the effect of frequency dispersion of the EM wave launcher and the material under evaluation is similar to the material under evaluation, if necessary, by measuring the measured data of the material under evaluation through a process well known to those skilled in the art. By normalizing another set of measured data corresponding to a reference structure according to a non-limiting example of a known property and thickness of the material, it can be eliminated.

  Furthermore, it should be noted that the material evaluation system of FIG. 1 operates in the frequency domain by transmitting EM waves at specific frequencies within the frequency band of interest. The recorded frequency domain data is then converted into time domain data for subsequent processing. However, the system may be implemented to operate in the time domain. Preferably, in the time domain operation mode, the EM wave launcher is capable of transmitting a plurality of frequency domain EM waves, so that the time domain representation of the plurality of EM waves is a short duration RF waveform, eg, , Gaussian, Rayleigh, Hermite, Laplacian pulse, etc., or a combination thereof.

  Alternatively, the EM wave launcher may provide such a type of pulse directly by a time domain RF waveform generator, and more preferably, the duration of the RF waveform is 5 nanoseconds or less. In this way, the EM wave launcher transmits and receives time domain pulses, the system measures the amplitude and arrival time of those pulses, stores the measured data, and stores the stored data in the time domain computer base. To the processing unit. Next, the time domain data is calibrated to the distance domain data, and by evaluating the calibrated area data, the location of the defect on the remote surface inside the material under evaluation is identified, and the material under evaluation Can be determined.

  In each of the above-described configurations, the length of the extended portion of the EM wave launcher 10 between the supply end 12 and the delivery end portion farthest from the supply end 12 is appropriately selected to be long enough to Multiple reflections corresponding to other clutter elements and other potential multiple reflections reach the computer-based processor 22 clearly behind any EM wave of interest. Under this circumstance, the propagation time of the EM wave propagating along the EM wave launcher 10 is much longer than the propagation time of the EM wave propagating through the thickness of the refractory material under evaluation.

  Thus, in the configuration of the EM wave launcher 10, the most important are the reception time of the EM wave of interest reflected from the remote discontinuity of the material under evaluation and the reflection from the adjacent surface of the material under evaluation. It is possible to distinguish the reception time of the spurious signal. Therefore, the length of the extended portion 16 of the EM wave launcher 10 between the supply end 12 and the transmission end portion farthest from the supply end 12 can be shortened. The shortened length is chosen to be short enough so that multiple reflections corresponding to the eighth clutter element and other potential multiple reflections including at least a portion of those corresponding to the fourth clutter element, To reach the computer-based processor faster than the EM wave of interest. In this case, the propagation time of the EM wave propagating along the EM wave launcher 10 is far greater than the propagation time of both the EM wave propagating through the thickness of the refractory material under evaluation and the multiple reflection from the delivery end 14. Short.

  FIG. 9 shows a perspective view of an electric miniature EM wave launcher 90 comprising a supply end 92 and a delivery end 94. In particular, the length between the supply end 92 and the delivery end 94 is such that multiple EM wave reflections between the delivery end 94 and the supply end 92 arrive much earlier than any EM wave of interest. Selected short enough. Similarly, multiple EM wave reflections from the adjacent outer wall of the refractory material under evaluation (not shown) will arrive much earlier than any EM wave of interest.

  Supply end 92 includes a supply transition 96 that is electrically connected to a radio frequency (RF) transmission line (not shown) via a coaxial connector 98. In this configuration, the supply transition unit 96 is configured by a supply unit (coaxial cable-fed cavity-backed feed) supported by a coaxial cable supply cavity. In particular, the supply transition part 96 is formed by an air-filled box made of a conductive material having a rectangular cross section in each direction of the box. The design characteristics of the supply transition section 96 corresponding to the supply section supported by the coaxial cable supply cavity having a rectangular cross-section are well known in the prior art, and the design characteristics of the supply transition section 18 described with reference to FIG. Is equivalent to One skilled in the art will appreciate that the RF transmission line electrically connected to the supply transition 96 may include a coaxial cable, coplanar waveguide, stripline, or microstrip. In an alternative configuration, the coplanar waveguide is impedance matched and configured to connect directly to at least one component of the RF transmitter or RF receiver.

  In addition, the EM wave launcher 90 can be used instead of the EM wave launcher 10 shown in the above-described embodiment. More specifically, in this embodiment, the EM wave launcher 90 is configured by a modified pyramid-shaped horn antenna having a rectangular cross section. The EM wave launcher 90 structurally includes a first flare plate 91a and a second flare plate 91b disposed on the opposite side of the plate 91a, like the standard pyramid-shaped horn antenna. Two opposing smaller plates have been removed. In this configuration, the first and second flare plates 91a and 91b are made of a conductive material.

  The thickness of the first and second flare plates 91a, 91b at the delivery end 94 defines a first edge 93a and a second edge 93b, and each of the first edge 93a and the second edge 93b is The length may be in the range of 0.01 to 1 inch. Importantly, prior art EM wave launchers such as standard horn antennas typically have a flare plate thickness to length ratio of generally less than 5%. However, in a preferred configuration, the first and second flare plates 91a, 91b are uniform in thickness and have a thickness to length ratio in the range of 15% to 85%. Each edge 93a, 93b is at least 0.25 inches long, so that the EM wave propagating along the EM wave launcher with the discontinuity is smoothed to a third at the delivery end 94. Reaches the edge 93c.

  More preferably, one or more edges of the first and second flare plates 91a, 91b at the delivery end 94 may be elliptical functions or other as described above with reference to FIGS. 1 and 2A-2D, for example. It may be rounded according to the smooth function. Most preferably, at least a portion of one or more edges of the first and second flare plates 91a, 91b at the delivery end 94 (including or corresponding to the edges 93a, 93b adjacent or opposite). Edge) has a roll edge configuration.

  Alternatively, the first and second flare plates 91a, 91b need not have a uniform thickness from the supply end 92 to the delivery end 94, and may have a variable thickness profile. If the thickness of the first and second flare plates 91a, 91b is variable, the preferred thickness profile will gradually increase in thickness in each of the first and second flare plates 91a, 91b, and the delivery end. It has the thickest part in 94 edge 93a, 93b. Further, as described above with reference to FIGS. 2A to 2D, the first and second flare plates 91a and 91b of the EM wave launcher 90 are made of a material having a variable conductivity instead of being made of a conductive material. You may have.

  In the specific configuration shown in FIG. 9, from the supply end 92 to the delivery end 94 in the volume region where the EM wave propagates in the EM launcher, that is, between the first flare plate 91a and the second flare plate 91b. In between, it is filled with the dielectric 95, and the dielectric 95 may be any of gas, liquid, or solid. Preferably, dielectric 95 is a solid material having an impedance that substantially matches the predetermined impedance of the refractory material under normal operating conditions of the furnace.

  More preferably, the volume region defined by the dielectric 95 is larger than the volume region described above, and the EM wave propagates in the EM wave launcher and the portion 95a of the dielectric 95 and the corresponding opposite portion (not shown). At least partially projects only from the side surfaces of the first and second flare plates 91a, 91b extending from the supply end 92 to the delivery end 94. Therefore, the edge 95b of the dielectric 95 is aligned with the edges 93a and 93b, and the side surface of the EM wave launcher 90 at the transmission end 94 and the edges 93a, 93b, 93c, and 95b are all in the same plane. Most preferably, the portion 95a of the dielectric 95 and the corresponding identical opposing portion (not shown) of the dielectric 95 have symmetrical protrusions on either side of the EM wave launcher 90 from the supply end 92 to the delivery end 94. Each protrusion has a wedge shape with a feed end 92 having a thick end of at least 0.05 inches. The configuration of the dielectric 95 is to mitigate multiple reflections of EM waves from the edges of the flare plates 91a, 91b, and to couple EM waves to and from external devices and other components. Contribute to.

  Those skilled in the art will recognize that dielectric 95, portion 95a, and corresponding identical opposing portion (not shown) each have a different shape, size, and material.

  Preferably, the EM wave launcher 90 is designed to operate in the frequency range of 0.25 GHz to 6 GHz. As a result, the dimensions (width and height) of the rectangular cross-section at the delivery end 94 of the EM wave launcher 90, the length of the EM wave launcher 90, and the dielectric properties of the dielectric 95 are all well known in the art. The EM wave launcher is selected to be operable within this frequency range. Furthermore, the EM wave launcher 90 is designed to allow the required operating temperature range near the outer surface of the furnace wall.

  Optionally, the EM wave launcher 90 may be a stand-alone (monostatic) or an array of two or more units (multistatic) as described above with reference to FIG. 1 and as is well known in the art. Can be used in configuration. Similarly, the EM wave launcher 90 may be part of an entire material evaluation system packaged in a single portable unit, a single handheld unit, or integrated into a single assembly as described above.

  In general, the various configurations and methods described above can be implemented to collect measurement data directly as part of a time domain based material evaluation system. Accordingly, one or more time domain pulses are transmitted and the corresponding reflected pulses are recorded for data processing and material evaluation. In particular, referring to FIG. 9, the EM wave launcher 90 may be implemented to operate in a time domain based material evaluation system. In this case, the length of the flare plates 91a and 91b is preferably dimensioned so that the propagation time of the transmission pulse from the supply end 92 to the transmission end 94 of the EM wave launcher 90 is less than 1 nanosecond.

  Although various embodiments have been described by way of example, it is to be understood that the terminology used is intended to be illustrative rather than restrictive. Any of the embodiments disclosed herein can include one or more aspects of other embodiments. Particular embodiments are set forth to illustrate some of the principles of the invention so that those skilled in the art can practice the invention. Obviously, many modifications and variations of the present invention are possible in light of the above disclosure, and the invention will be specifically described within the scope of the appended claims and their legal equivalents. It can implement by another aspect.

Claims (44)

A system for evaluating the condition of a material,
An electromagnetic launcher and a computer-based processor,
The electromagnetic wave launcher has a first supply end and a second delivery end,
The first supply end includes a feeding mechanism that excites electromagnetic waves that can propagate through the electromagnetic wave launcher,
The second delivery end sufficiently reduces a plurality of reflections and probe ringing of the electromagnetic wave propagating through the delivery end to detect an electromagnetic wave of interest reflected from a remote discontinuity in the material. Physically configured to allow,
The electromagnetic launcher is physically configured at the second delivery end to have an impedance that substantially matches the impedance of the proximal surface of the material;
The electromagnetic wave launcher enables the reception of the electromagnetic wave of interest reflected from the remote discontinuity of the material within a sufficient period of time from the reflected electromagnetic wave of interest and the adjacent surface of the material. Adapted to distinguish from reflected spurious signals,
The delivery end is adapted to accommodate an area of the proximal surface of the material;
The computer-based processor has executable computer code,
The executable computer code is:
Measuring the reflected electromagnetic waves of interest to generate frequency domain data;
Converting the frequency domain data into time domain data;
Calibrating the time domain data to distance domain data;
Identifying peaks in the distance domain profile associated with the electromagnetic wave of interest reflected from the material;
Determining the travel distance of the electromagnetic wave of interest reflected from the material;
Configured to perform including,
system. The electromagnetic wave launcher further includes a pyramidal horn antenna having a rectangular cross section,
The pyramidal horn antenna is
A first flare plate and a second flare plate disposed on the opposite side of the first flare plate;
The first flare plate is
A plane portion and two flare portions along opposite side edges of the plane portion of the first flare plate;
The second flare plate is
A flat portion, and two flare portions along opposite side edges of the flat portion of the second flare plate;
The system of claim 1.   The system of claim 2, wherein a thickness of at least one of the first flare plate and the second flare plate is variable.   The system of claim 2, wherein a thickness to length ratio of at least one of the first flare plate and the second flare plate is in the range of 15% to 85%. At least a portion of the volume region between the first flare plate and the second flare plate includes a dielectric;
The dielectric is
Extending beyond the two flare portions along the opposing side edges of the planar portion of at least one of the first flare plate and the second flare plate;
The system according to claim 2. Calibrating the time domain data to the distance domain data
Executed by the executable computer code based on a known velocity of the electromagnetic wave of interest traveling through the material;
The system of claim 1.   The computer-based processor is adapted to visually display information about the state of the material based on the travel distance of the electromagnetic wave of interest reflected from the material. The described system.   The system of claim 1, wherein the state of the material is the thickness of the material.   The system of claim 1, wherein the state of the material is a defect in the material.   The system of claim 1, wherein the electromagnetic wave launcher and at least one other component of the system are integrated into a single unit.   The system of claim 1, wherein the second delivery end has at least one edge that physically conforms to extend away from the area to be evaluated of the proximal surface of the material.   The system of claim 11, wherein the edge has a smooth roll edge configuration. The volume region in the electromagnetic wave launcher includes a dielectric,
In the volume region, the electromagnetic wave is configured to propagate between the delivery end and the supply end.
The system of claim 1. The electromagnetic wave launcher is formed by using a variable conductivity material disposed between the first supply end and the second delivery end,
The conductivity variable material has a first end closer to the first supply end and a second end closer to the second delivery end;
The conductivity increases as a function of the distance from a point in the conductivity variable material to the second end of the conductivity variable material closer to the second delivery end of the electromagnetic wave launcher;
The system of claim 1.   The first supply end is adapted to reduce clutter that would otherwise be present in the system by sufficiently reducing multiple reflections of the excited electromagnetic wave at the first supply end. The system of claim 1.   The system of claim 15, wherein the first supply end further comprises a pin supported by a cavity. The first supply end further includes a supply transition section,
The supply transition unit electrically connects a radio frequency transmission line to the first supply end;
The system of claim 1.   The system of claim 17, wherein the radio frequency transmission line is configured to electrically connect to at least one component selected from the group consisting of a radio frequency receiver and a radio frequency transmitter.   The system of claim 1, further comprising an RF subsystem that generates electromagnetic waves in a frequency range between 0.25 GHz and 30 GHz.   The electromagnetic wave launcher reduces the reception of the spurious signal reflected from the adjacent surface of the material by a sufficient period of time, thereby reducing the reflected electromagnetic wave of interest and the spurious reflected from the adjacent surface of the material. The system of claim 1, wherein the system is adapted to distinguish from a signal.   The electromagnetic wave launcher discriminates between the reflected electromagnetic wave of interest and the electromagnetic wave reflected from the part of the electromagnetic wave launcher by shortening reception of the electromagnetic wave reflected from the part of the electromagnetic wave launcher by a sufficient period. The system of claim 1, wherein the system is adapted to: A method for evaluating the condition of a material,
Providing an electromagnetic wave launcher comprising a first supply end and a second delivery end, comprising:
The first supply end includes a feeding mechanism that excites electromagnetic waves that can propagate through the electromagnetic wave launcher,
The second delivery end can sufficiently detect multiple reflections and probe ringing of the electromagnetic wave propagating through the delivery end to detect an electromagnetic wave of interest reflected from a remote discontinuity in the material. Is physically configured to
The electromagnetic launcher is physically configured at the second delivery end to have an impedance that substantially matches the impedance of the proximal surface of the material;
The electromagnetic wave launcher enables the reception of the electromagnetic wave of interest reflected from the remote discontinuity of the material within a sufficient period of time, and the reflected surface of interest and the proximity surface of the material. Adapted to distinguish from spurious signals reflected from
The delivery end is adapted to accommodate an area of the proximal surface of the material;
Providing said electromagnetic wave launcher a.
Placing the delivery end of the electromagnetic wave launcher adjacent to conform to the area to be evaluated on the adjacent surface of the material; b
Delivering a plurality of electromagnetic waves propagating within a predetermined frequency range to the area to be evaluated of the adjacent surface of the material; c.
Detecting the electromagnetic wave of interest within the predetermined frequency range; and d.
Determining a state of the material based on a determined travel distance of the electromagnetic wave of interest reflected from a remote discontinuity of the material; and
Including a method.   23. The method of claim 22, wherein the travel distance of the electromagnetic wave of interest is determined based on a travel time of the electromagnetic wave of interest.   24. The method of claim 23, wherein the travel time of the electromagnetic wave of interest is sufficiently longer than the travel time of the spurious signal, thereby allowing time separation of the electromagnetic wave of interest from the spurious signal.   23. The method of claim 22, wherein a time domain representation of the plurality of electromagnetic waves propagating within a predetermined frequency range corresponds to a short duration pulse radio frequency waveform.   26. The method of claim 25, wherein the short duration radio frequency waveform is selected from the group consisting of a Gaussian pulse, a Rayleigh pulse, a Hermite pulse, a Laplacian pulse, and combinations thereof.   26. The method of claim 25, wherein the duration of the pulse of the radio frequency waveform is 5 nanoseconds or less. Determining the state of the material comprises:
Measuring a time-domain data set relating to the detected electromagnetic wave of interest;
Calibrating the time domain data to distance domain data; and
Identifying a peak in the distance domain data for the electromagnetic wave of interest reflected from the remote discontinuity of the material; c.
Determining a travel distance of the electromagnetic wave of interest reflected from the remote discontinuity of the material; d.
Determining a length of a distance from the near surface of the material to the remote discontinuity of the material based on the travel distance of the electromagnetic wave of interest reflected from the remote discontinuity of the material. e,
The method of claim 22, further comprising:   29. The method of claim 28, wherein calibrating the time domain data to the distance domain data is performed based on a known propagation velocity of the electromagnetic wave of interest through the material. Determining the state of the material comprises:
Measuring a data set relating to the detected electromagnetic wave of interest;
Providing a first means for storing the data set; b.
Providing a computer-based data processor for processing the data set to evaluate the state of the material;
Transferring the data set from the first means to the computer-based data processor;
Processing the data set by at least one signal processing method; and e.
The method of claim 22, further comprising:   31. The method of claim 30, further comprising processing the data set utilizing a signal processing method selected according to the material properties to be evaluated.   24. The method of claim 22, wherein the state of the material is the thickness of the material.   The method of claim 22, wherein the frequency range is between 0.25 GHz and 30 GHz. A method for evaluating the condition of a material,
Providing an electromagnetic wave launcher comprising a first supply end and a second delivery end, comprising:
The first supply end includes a feeding mechanism that excites electromagnetic waves that can propagate through the electromagnetic wave launcher,
The second delivery end sufficiently reduces multiple reflections and probe ringing of the electromagnetic wave propagating through the delivery end to detect a radio frequency waveform of interest reflected from a remote discontinuity in the material. Physically configured to allow
The electromagnetic launcher is physically configured at the second delivery end to have an impedance that substantially matches the impedance of the proximal surface of the material;
The electromagnetic wave launcher enables the reception of the reflected radio frequency waveform of interest and the material by allowing reception of the radio frequency waveform of interest reflected from the remote discontinuity of the material within a sufficient period of time. Adapted to distinguish from spurious signals reflected from said proximity surface of
The delivery end is adapted to accommodate an area of the proximal surface of the material;
Providing said electromagnetic wave launcher a.
Placing the delivery end of the electromagnetic wave launcher adjacent to conform to the area to be evaluated on the adjacent surface of the material; b
Transmitting a radio frequency waveform to the area to be evaluated of the adjacent surface of the material; c.
Detecting the radio frequency waveform of interest d;
Determining the state of the material based on a determined travel distance of the radio frequency waveform of interest reflected from a remote discontinuity of the material; and
Including a method.   35. The method of claim 34, wherein the radio frequency waveform has a short duration and is selected from the group consisting of a Gaussian pulse, a Rayleigh pulse, a Hermite pulse, a Laplacian pulse, and combinations thereof.   36. The method of claim 35, wherein the duration of the radio frequency waveform is 5 nanoseconds or less.   35. The method of claim 34, wherein the travel distance of the radio frequency waveform of interest is determined based on a travel time of the radio frequency waveform of interest.   38. The progression time of the radio frequency waveform of interest is sufficiently longer than the progression time of the spurious signal, thereby allowing time separation of the radio frequency waveform of interest from the spurious signal. The method described. Determining the state of the material comprises:
Measuring a time domain data set for the detected radio frequency waveform of interest; a.
Calibrating the time domain data to distance domain data; and
Identifying a peak in the distance domain data relating to the radio frequency waveform of interest reflected from the remote discontinuity of the material; c.
Determining a travel distance of the radio frequency waveform of interest reflected from the remote discontinuity of the material;
Determine the length of the distance from the near surface of the material to the remote discontinuity of the material based on the travel distance of the radio frequency waveform of interest reflected from the remote discontinuity of the material Step e.
35. The method of claim 34, further comprising:   40. The method of claim 39, wherein calibrating the time domain data to the distance domain data is performed based on a known propagation velocity of the radio frequency waveform of interest through the material. Determining the state of the material comprises:
Measuring a data set relating to the detected radio frequency waveform of interest; a.
Providing a first means for storing the data set; b.
Providing a computer-based data processor for processing the data set to evaluate the state of the material;
Transferring the data set from the first means to the computer-based data processor;
Processing the data set by at least one signal processing method; and e.
35. The method of claim 34, further comprising:   42. The method of claim 41, further comprising processing the data set utilizing a signal processing method selected according to properties of the material to be evaluated.   35. The method of claim 34, wherein the state of the material is the thickness of the material. A system for evaluating the state of a material,
An electromagnetic wave launcher having a supply end including a power feeding mechanism for exciting electromagnetic waves;
A computer-based processor having executable computer code;
With
The electromagnetic wave launcher sends the electromagnetic wave into the near surface of the material,
The electromagnetic wave launcher is physically configured to sufficiently reduce multiple reflections of the transmitted electromagnetic wave to allow detection of an electromagnetic wave of interest reflected from a remote discontinuity of the material;
The electromagnetic wave launcher is adapted to conform to an area of the proximal surface of the material and is physically configured to have an impedance that substantially matches the impedance of the proximal surface of the material;
The electromagnetic wave launcher delays the reception of the electromagnetic wave of interest reflected from the remote discontinuity of the material by a sufficient period of time, thereby causing the reflected electromagnetic wave of interest and a spurious signal reflected from the material. And is adapted to identify
The executable computer code is:
Measuring the reflected electromagnetic waves of interest to generate frequency domain data;
Converting the frequency domain data into time domain data;
Calibrating the time domain data to distance domain data;
Identifying peaks in the distance domain profile associated with the electromagnetic wave of interest reflected from the material;
Determining the travel distance of the electromagnetic wave of interest reflected from the material;
Configured to perform including,
system.