JP5055561B2 - Hull Surrounding UEP Calculation Method - Google Patents

Description

  The present invention relates to a hull peripheral UEP calculation method for estimating and calculating UEP (Underwater Electric Potential) generated around a hull such as surface ships and submarines.

  When two metals having different ionization tendencies exist in the electrolytic solution, a potential difference is generated between the two metals, and an underwater electric field is generated. Looking at this for ships, the hull is composed of various dissimilar metals (the hull is steel, for example, and the propeller is copper, for example). A potential difference occurs, and an underwater electric field is generated. The underwater potential resulting from this underwater electric field is generally referred to as UEP.

  The metal in the hull, which has a high ionization tendency, becomes cations and dissolves in the seawater, so the metal in the hull corrodes. Therefore, as a means to prevent hull corrosion, the galvanic anode method in which sacrificial protective zinc is stretched around the hull instead of the hull, and current is applied to keep the hull potential constant to prevent corrosion. There is an external power supply anticorrosion system. Although these methods can prevent hull corrosion, UEP is generated in seawater around the hull in any method.

  In order to estimate and calculate the peripheral UEP around these hulls generated from the hull at an arbitrarily set position, it is first necessary to determine the position of the electrode serving as the current generation source of the hull and the current value between the electrodes. Conventionally, an engineer repeatedly changes the position of the hull electrodes and the current value between the electrodes, repeatedly calculates UEP using the electro-image method or boundary element method, and measures the surrounding UEP measured by the UEP sensor. The position of the hull electrode and the current value between the electrodes were determined so as to most closely match the values.

  Since the conventional method is basically manual calculation, it takes a lot of time and labor to determine the current value, and it is practically impossible to set a large number of electrodes. Also, the calculated current value must have a large error from the actual current value. In addition, the skill of the engineer greatly affects the results.

  The present invention has been made in recognition of such a situation, and the purpose of the invention is to calculate the peripheral UEP of the hull that can accurately estimate the UEP at an arbitrary position in a simple and short time regardless of the skill and experience of the engineer. It is to provide a method.

One aspect of the present invention is a hull periphery UEP calculation method. This method
A method for calculating a UEP generated by a hull,
An electrode position setting step for setting a plurality of electrode positions of the hull;
An electrode combination setting step of setting a predetermined number of electrode combinations selected from any two of the plurality of electrodes;
A virtual electrode position setting step for setting a plurality of virtual electrode positions in the electro-image method corresponding to each of the plurality of electrodes;
A calculation formula for the peripheral UEP of the hull by electro-image method based on the peripheral UEP of the hull measured by the UEP sensor outside the hull, and the relative positions of the plurality of electrodes, the plurality of virtual electrodes, and the UEP sensor. A current value calculation step for calculating a current value flowing between electrodes of the electrode combination set in the electrode combination setting step by an optimum parameter search method;
A UEP calculation step of estimating and calculating a peripheral UEP of the hull generated from the hull on an arbitrarily set estimation plane or estimation line based on the calculated current value.

  In a method of a certain mode, the UEP sensor may measure a potential difference between two points in at least one of X, Y, and Z directions orthogonal to each other as UEP.

  In the method of an aspect, the calculation formula based on the electric image method may represent the peripheral UEP of the hull as a potential difference between any two points.

  In the method of an aspect, the calculation formula based on the electric image method may represent the peripheral UEP of the hull as an integral of an electric field between any two points.

In some embodiments of the method,
The virtual electrode position set in the virtual electrode position setting step includes a position under the seabed and the sea surface,
The calculation formula based on the electric image method may include air conductivity, seawater conductivity, and conductivity under the seabed.

  In the method of an aspect, the optimal parameter search method may be a least square method.

  In the method of an embodiment, the optimal parameter search method may be a genetic algorithm.

  In the method of an embodiment, the optimum parameter search method may be a steepest descent method.

  In a method according to an aspect, the optimum parameter search method may be an annealing method.

  It should be noted that any combination of the above-described constituent elements and a representation obtained by converting the expression of the present invention between apparatuses and systems are also effective as an aspect of the present invention.

  According to the present invention, current value calculation and UEP estimation calculation can be automated, so UEP at an arbitrary position can be accurately estimated and calculated in a short time regardless of the skill and experience of an engineer. . Further, the number of electrodes is not substantially limited. Furthermore, since the current value between the electrodes can be grasped, it is also effective in applications such as canceling the peripheral UEP around the hull by forcibly applying a reverse current.

The flowchart which shows the flow of the surrounding UEP calculation method of the hull which concerns on embodiment of this invention. FIG. 6 is an explanatory diagram illustrating an example of arrangement of virtual electrodes in an electrode combination t (a combination of hull electrodes P ₀ ^{t +} and P ₀ ^t− ) of an electric image method.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  FIG. 1 is a flowchart showing a flow of a hull periphery UEP calculation method according to an embodiment of the present invention. Here, an example in which the least square method is used as the optimum parameter search method used when calculating the current value between the electrodes is shown. Each step is basically realized by the cooperation of a computer and software. Details will be described below.

  First, the peripheral UEP of the hull is measured by a UEP sensor installed in the sea or on the seabed, and the relative position between the hull center and the UEP sensor is measured by a positioning system such as GPS (Global Positioning System) (STl). The UEP sensor is configured to measure a potential difference between two points. Here, with respect to the coordinate axes, the center of the hull is defined as the origin, the forward direction of the tail line is defined as the X axis, the right lateral direction is defined as the Y axis, and the vertical downward direction is defined as the Z axis.

Subsequently, the following data is input (ST2).

  In addition, although the space | interval of each axial direction both ends of a triaxial UEP sensor is set to l (m), the space | interval may not be the same about each axial direction. Moreover, it is also possible to use a 1-axis UEP sensor or a 2-axis UEP sensor instead of the 3-axis UEP sensor. In this case, only the data in the 1-axis direction or the 2-axis direction is input as the UEP measurement data. However, the calculation accuracy of the later-described expansion coefficient is higher when the 2-axis UEP sensor is used than the 1-axis UEP sensor and the 3-axis UEP sensor is used rather than the 2-axis UEP sensor. Further, the number of 1-axis to 3-axis UEP sensors may be one, or two or more. As the number of UEP sensors is increased, the calculation accuracy of the expansion coefficient described later increases.

  Subsequently, the positions of a plurality of electrodes in the hull are set (ST3). The position of the electrode can be arbitrarily set. For example, it may be determined depending on the position of the protective zinc, dissimilar metal, electrode of the external power source anticorrosion device, etc., or equivalently disposed in the front and rear of the hull (the bow and stern). May be.

  Only tt electrode combinations in which any two of the set electrodes are selected are set (ST4). A current path flowing from one electrode to two or more electrodes or a current path flowing from two or more electrodes to one electrode can also be set. Next, the positive / negative (current input side and output side) between the two electrodes is also determined from the ionization tendency of the electrode material.

Next, the order nn of the virtual electrode in the electric image method is set (ST5). Here, FIG. 2 shows an arrangement example of the virtual electrodes in the electrode combination t (the combination of the hull electrodes P ₀ ^{t +} and P ₀ ^t− ) of the electric imaging method. As shown in this figure, in order 1, the following virtual electrodes are created.

In the order n, the following virtual electrodes are created.

Thus, every time the order increases by 1, the number of virtual electrodes increases by four. This virtual electrode is created for all electrode combinations (ST6). The coordinate information of each electrode is as follows.

Subsequently, the electrical conductivity σ _{A of} air, the electrical conductivity σ _{W of} seawater, and the electrical conductivity σ _G under the seabed are input (ST7).

  Here, in order to calculate UEP between two arbitrary points, there are a method of calculating the difference between the two points after obtaining the potential between the two points, and a method of integrating the electric field between the two points. First, the calculation formula in the electric image method using the method of calculating the potential difference between two points will be shown.

Subsequently, a calculation formula in the electric image method using the method of integrating the electric field between two arbitrary points will be shown.

In the above formulas 5 to 10,
It is.

The above formulas 5 to 10 are generally
It can be expressed as. Therefore, if it is possible to obtain a current value I _t flowing between the electrodes of each electrode combination t, it becomes possible to estimate calculating the potential difference E ^k between any two points. Note that the current value I _t according to the method of calculating the difference between the two sought after potential between two points by the number 5-7, the current value I _t is by way of integrating the electric field between two points by the number 8-10 It will be the same.

  The function of the position in Equation 12 is calculated based on the measurement data of the relative position between the hull center and the UEP sensor and each electrode position (ST8). Next, a least squares determinant is created (ST9).

The determinant is
Next, by solving this current value I _t flowing between the electrodes the electrode combination is calculated (ST10). Here, an example in which the least square method is used for the optimum parameter search method is shown, but ST9 is another method such as genetic algorithm (GA), steepest descent method, annealing method (SA), etc. even using known optimal parameter search method can calculate a current value I _t.

  Next, an estimation plane or an estimation line is set (ST11), and a function of the position at each set point j on the estimation plane or the estimation line is calculated (ST12).

UEP at each set point j
(ST13).

  According to the present embodiment, since the calculation of the current value and the estimation calculation of UEP are automated, even if there are many electrodes, the current value between the electrodes can be easily and quickly regardless of the skill and experience of the technician. And UEP at an arbitrary position can be accurately estimated and calculated. In addition, since the current value between the electrodes can be grasped, it is also effective in applications such as canceling the peripheral UEP around the hull by forcibly applying a reverse current.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way.

5 hull

Claims (9)

A method for calculating UEP (Underwater Electric Potential) generated by a hull,
An electrode position setting step for setting a plurality of electrode positions of the hull;
An electrode combination setting step of setting a predetermined number of electrode combinations selected from any two of the plurality of electrodes;
A virtual electrode position setting step for setting a plurality of virtual electrode positions in the electro-image method corresponding to each of the plurality of electrodes;
A calculation formula for the peripheral UEP of the hull by electro-image method based on the peripheral UEP of the hull measured by the UEP sensor outside the hull, and the relative positions of the plurality of electrodes, the plurality of virtual electrodes, and the UEP sensor. A current value calculation step for calculating a current value flowing between electrodes of the electrode combination set in the electrode combination setting step by an optimum parameter search method;
A hull peripheral UEP calculation method comprising: a UEP calculation step of estimating and calculating a peripheral UEP of the hull generated from the hull on an arbitrarily set estimation plane or estimation line based on the calculated current value.   The hull peripheral UEP calculation method according to claim 1, wherein the UEP sensor measures a potential difference between two points in at least one of X, Y, and Z directions orthogonal to each other as a UEP.   3. The method of calculating a surrounding UEP for a hull according to claim 1 or 2, wherein the calculation formula based on the electric image method represents the surrounding UEP of the hull as a potential difference between any two points.   The method of calculating a surrounding UEP for a hull according to claim 1 or 2, wherein the calculation formula based on the electric image method represents the surrounding UEP of the hull as an integral of an electric field between two arbitrary points. The virtual electrode position set in the virtual electrode position setting step includes a position under the seabed and the sea surface,
5. The method for calculating a surrounding UEP for a hull according to any one of claims 1 to 4, wherein the calculation formula based on the electric image method includes an electrical conductivity of air, an electrical conductivity of seawater, and an electrical conductivity under the seabed.   The hull periphery UEP calculation method according to claim 1, wherein the optimum parameter search method is a least square method.   6. The hull peripheral UEP calculation method according to claim 1, wherein the optimum parameter search method is a genetic algorithm.   6. The hull peripheral UEP calculation method according to claim 1, wherein the optimum parameter search method is a steepest descent method.   6. The hull peripheral UEP calculation method according to claim 1, wherein the optimum parameter search method is an annealing method.