CN106376048A - Event-driven coal mine underground wireless sensor network system - Google Patents

Abstract

The invention discloses an event-driven coal mine underground wireless sensor network system which comprises a base station device and an underground node device. An underground node wireless communication module comprises a sending state, a receiving state and a hibernation state. Three working states of the underground node wireless communication module can be converted to each other. An event-driven wireless sensor network in operation determines whether to trigger an event and transmit data to a base station by monitoring and judging whether data exceed a threshold value. The system has the characteristics of high communication efficiency and low operation energy consumption. According to the invention, the system is combined with coal mine underground safety production needs; through reasonable threshold setting and an improved routing protocol, the number of times of invalid communication among nodes is remarkably reduced; the communication efficiency is improved; the energy consumption of the nodes is reduced; the service life of a network is prolonged; collected useless data are reduced; in the case of an accident or alarm, useful alarm data can be quickly extracted; the event-driven network technology is applied to coal mine underground safety monitoring; and the system is an efficient coal mine safety monitoring system.

Description

One kind is based on event driven wireless sensor network under coal mine system

Technical field

The present invention relates to a kind of be based on event driven wireless sensor network under coal mine system, concretely relate to Wireless sensor network, wireless communication field.

Background technology

Wireless sensor network (wsn) is a kind of up-to-date wireless monitor network technology of modern times intelligent automation, extensively uses In security monitoring fields such as personnel positioning, underground coal mine data acquisitions.Traditional underground coal mine real-time type wsn node carries energy Limited, large number of, replacing is difficult in maintenance, and therefore reducing energy consumption becomes the most key target in this system design process.For Solve problem above, this paper presents a kind of be based on event driven underground coal mine wsn system.

Based on event driven wsn in running by monitoring and differentiating whether data exceedes threshold value and decide whether Trigger event and to base station transmission data, it is high that it has a communication efficiency, the low characteristic of operation energy consumption.System of the present invention In conjunction with coal mine downhole safety Production requirement, the Routing Protocol after being arranged and improved by rational threshold value significantly reduces between node Invalid number of communications, improves communication efficiency, thus reducing node energy consumption, extends network life.And decrease to hash Collection, when having an accident or report to the police, can be with the useful alert data of rapid extraction.Will be based on event driven wsn technology It is applied in coal mine downhole safety monitoring, have great theory and reality meaning to lifting coal mine safety monitoring ability and level Justice.

Content of the invention

One kind of the present invention can substantially reduce inter-node communication based on event driven underground coal mine wsn system Number, thus reducing node energy consumption, extends network life.And decrease the collection to hash, when having an accident or report to the police When, can be with the useful alert data of rapid extraction.The present invention is achieved by the following technical solutions.

Described system mainly includes base station equipment and down-hole node device；It is characterized in that: base station equipment includes monitoring eventually End, dispatching desk, location-server, storage server and switch；Monitor terminal, dispatching desk, location-server, storage server All access backbone network, communicated by backbone network；Switch is the nucleus equipment of backbone network；Target node device includes processing Device, buzzer, energy supply module, methane content detection means, button, vibrations motor, temperature sensor, carbon monoxide sensing Device, wireless communication module；The equidistant interlaced arrangement of node device is in the both sides in tunnel.

The described workflow based on event driven wireless sensor network under coal mine system is as follows:

(1) sensor node state is divided into: send state, reception state and resting state.Three kinds of shapes of sensor node Can mutually change between state.When event does not trigger sensor node in a dormant state, when node monitors data exceedes threshold value When trigger event, be now subject to event driven node to enter sending mode；Node in a dormant state receives useful signal, Node can be made to proceed to reception state from resting state；It is in the node of transmission state or reception state, if within a period of time not Transmission signal, then this node be changed into resting state from transmission state or reception state.

(2) according to safety regulations in coal mine, by the gas density of wherein defined, carbonomonoxide concentration, temperature etc. refers to safely Target 80% is set to threshold value of warning, and in production operation, Monitoring Data exceedes threshold value of warning and then triggers early warning event, and base station is to net In network, all nodes send signal, concept transfer mode of operation, improve node data upload frequencies.Will be each in safety regulations in coal mine The danger threshold being set to event triggering of safety index, in production operation, Monitoring Data exceedes danger threshold and then triggers danger Event, concept transfer mode of operation, improves node data upload frequencies and emergency plan for accidents is opened by mine.Described node work Operation mode includes: normal state, alert status and precarious position, and specific works step is as follows:

(a) by the original state that normal state is network, all node institutes Monitoring Data in whole network under normal state Less than threshold value of warning, in the network when wsn is in normal state, each node uploads a secondary data in every 10 minutes.

B () when a node institute Monitoring Data any in wsn is more than threshold value of warning and is less than danger threshold, then wsn is by state Switch to alert status.The node being issued to threshold value of warning in alert status opens real-time Transmission pattern, and other are not up to early warning The node of threshold value uploads a secondary data in every 30 seconds.When in wsn, all node institutes Monitoring Data numerical value drops to below threshold value of warning simultaneously Keep 20 minutes then wsn return to normal state, also can be artificial when node monitors value data returns to below threshold value of warning Sending instruction to network makes it recover normal state.

(c) precarious position: when a node institute Monitoring Data any in wsn reaches danger threshold, then state is switched to by wsn Precarious position.Now in network, all nodes open real-time Transmission mode of operation immediately, until Monitoring Data is less than danger threshold Shi Fangke passes through artificial instruction to network transmission and is gone out.

(3) Routing Protocol: the design according to underground coal mine node deployment position characteristics, by modified model leach clustering routing Agreement is used in the driving wsn of downhole event.

The design, according to underground coal mine node deployment position characteristics, modified model leach clustering route protocol is used for down-hole In event driven wsn.

Leach agreement cluster head random-selection node in a circulating manner, the energy load of whole network is evenly distributed to In each sensor node, thus reducing network energy resource consumption, the purpose of raising network entirety life span.But in reality The cluster head node that in the application of border, wsn chooses may be distributed relatively uneven, to randomly generate leader cluster node number in the entire network It cannot be guaranteed that in optimum range, thus cause network energy consumption load distribution not good.In the establishment stage of leach algorithm, cluster head Choose mainly by node produce 0 to 1 between random number determine, whether contrast random number reaches threshold value t (n), if section Point random number is more than t (n), then this node becomes the member node of epicycle, otherwise as leader cluster node.T (n) such as formula (1) Gained:

$t\left(n\right)=\left\{\begin{array}{cc}\frac{p}{i-p\[r\mathrm{mod}\left(\frac{1}{p}\right)\]}& n\&element;g\\ 0& otherwise\end{array}\right.---\left(1\right)$

Wherein, p is the ratio of leader cluster node number and non-leader cluster node number, and r represents election wheel number；G is in nearest 1/p wheel In be never elected as the node set of cluster head.

From formula (1), the leader cluster node of leach election does not consider the dump energy of node, if being chosen as cluster head Residue energy of node is very few, then this cluster head is just by premature death, thus affecting the network life of whole wsn.And leach algorithm Do not relate to cluster head is uniformly distributed problem, if cluster head distribution is excessively concentrated, can waste Internet resources in a large number.Therefore, adopt Following method given threshold:

$t\left(n\right)=\frac{p}{1-p\[r\mathrm{mod}\left(\frac{1}{p}\right)\]}\×\[\frac{0.7n_{live}{e}_c}{{\mathrm{\σ}}_{i=1}^{n_{live}}{e}_c\[i\]}+\frac{0.3{\mathrm{\σ}}_{i=1}^{n_{live}}{d}_{tobs}\[i\]}{d_{tobs}\×n_{live}}\]$

In formula, n_liveFor remaining surviving node number, e_cFor residue energy of node, d_tobsDistance for node to base station.Work as section Dump energy e of point_cBigger, t (n) will increase therewith, then the probability that the big node of dump energy is elected as cluster head increases；Separately Outward, when nodal distance base station farther out when, node be elected as cluster head probability less it is therefore prevented that cluster head marginalisation distribution.

Although the algorithm after improvement reduces cluster head marginalisation distribution to a certain extent, do not solve to choose in network The problem of good cluster head quantity.In order to obtain the optimal number of cluster head, the present invention proposes and is applied to underground coal mine long and narrow tunnel ring The optimum cluster head quantity choosing method in border.Assume that wsn often takes turns k cluster head of generation, k is related to as an important systematic parameter The energy loss of whole network and life span.The optimum value that the present invention to calculate k using the energy consumption model of in figure is (such as Shown in Fig. 3).

e_s(c, d) represents the energy consumption of discharger；e_rC () represents the energy consumption of reception device.e_elec* c represent radiating circuit with The energy consumption of receiving circuit, circuit total energy consumption is directly proportional to data package size c.Introduce slow fading d², rapid fading d⁴, μ_ampPut for signal The permanent ginseng of big device.If transmitting-receiving two-end distance threshold value is d₀, it is typically set to cluster center to the maximum distance on cluster side, less than d₀Make With slow fading model (fs), otherwise use rapid fading model (mp).

In signals transmission, each node sends the packet of lbit in current time slots, and transmission range is d, then sensor is sent out The energy loss of injection device is:

$e_s(c,d)=\left\{\begin{array}{cc}{\mathrm{le}}_{elec}+{\mathrm{l\&mu;}}_{fs}{d}^2& d<d_0\\ {\mathrm{le}}_{elec}+{\mathrm{l\&mu;}}_{mp}{d}^4& d\&le;d_0\end{array}\right.---\left(2\right)$

The energy loss of reception device is:

e_r(c)=le_elec(3)

Assume have n node to be evenly distributed in the long and narrow tunnel for s for the down-hole gross area, if there being k cluster in network, In each cluster, average nodal number is n/k, including a leader cluster node and n/k-1 cluster member, data fusion can consume e_da Represent.The energy consumption of cluster head node is made up of three parts: understands that the energy consumption receiving cluster member transmission data is le by formula (3)_elec ((n/k) -1), the total energy consumption that cluster inner tuft head node data merges is le_da(n/k) it is assumed that data fusion here is melted for perfection Close.Cluster head issues the energy loss of lower base station the data after mergingTherefore leader cluster node often takes turns consumed energy For:

$e_{ch}={\mathrm{le}}_{elec}(\frac{n}{k}-1)+{\mathrm{le}}_{da}\left(\frac{n}{k}\right)+{\mathrm{le}}_{elec}+{\mathrm{l\&mu;}}_{mp}{d}_{tobs}^4---\left(4\right)$

Wherein d_tobsRepresent cluster head to the distance of base station.

The energy sending data consumption to cluster head in every frame from formula (3) each cluster member is:

$e_{non-ch}={\mathrm{le}}_{elec}+{\mathrm{l\&mu;}}_{fs}{d}_{toch}^2---\left(5\right)$

Wherein d_tochRepresent cluster member to the distance of leader cluster node.In network, each cluster occupied area is about s/k.Assume section The probability density of point distribution in cluster is ρ (x, y), and each leader cluster node is located at cluster center, then d² _tochAverage be:

$e\&lsqb;d_{toch}^2\&rsqb;=\&integral;\&integral;d_{toch}^2\mathrm{\&rho;}(x,y)d\mathrm{\&sigma;}=\&integral;\&integral;(x^2+y^2)\mathrm{\&rho;}(x,y)dxdy$

Hypothesis each cluster in tunnel is approximately the rectangular area of an a width of a, the then a length of s/ in this region (ka).In substitution State formula to obtain:

$e\&lsqb;d_{toch}^2\&rsqb;=\mathrm{\&rho;}\underset{-\frac{a}{2}}{\overset{\frac{a}{2}}{\&integral;}}\underset{\frac{s}{-2ka}}{\overset{\frac{s}{2ka}}{\&integral;}}{x}^2+y^{2}dxdy=\mathrm{\&rho;}(\frac{s^3}{12k^3{a}^2}+\frac{{\mathrm{sa}}^2}{12k})---\left(6\right)$

Because ρ (x, y) (5) is non-uniform probability distribution, then ρ=(1/ (s/k)).Substitute into formula (6) to simplify:

$e\&lsqb;d_{toch}^2\&rsqb;=\frac{y^2}{12k^2{a}^2}+\frac{a^2}{12}---\left(7\right)$

Again formula (7) is substituted into formula (5) to obtain

$e_{non-ch}={\mathrm{le}}_{elec}+{\mathrm{l\&mu;}}_{fs}(\frac{s^2}{12k^2{a}^2}+\frac{a^2}{12})---\left(8\right)$

So, energy loss in every frame for each cluster is:

e_cluster=e_ch+((n/k)-1)e_non-ch≈e_ch+(n/k)e_non-ch(9)

Again formula (4) and formula (8) are substituted into formula (9), the energy summation of the loss in every frame for all clusters is:

$e_{total}=k*e_{cluster}=l(2e_{elec}n+e_{da}n+{\mathrm{k\&mu;}}_{mp}{d}_{tobs}^4+{\mathrm{\&mu;}}_{fs}n(\frac{s^2}{12k^2{a}^2}+\frac{a^2}{12}\left)\right)$

By to e_totalDerivation set to 0 after can obtain optimal value:

$k_{opt}=\sqrt[3]{\frac{{\mathrm{\&mu;}}_{fs}{s}^{2}n}{6a^2{\mathrm{\&mu;}}_{mp}{d}_{tobs}^4}}$

(4) accident related data extracts: the data that base station receives adds state and node label when being stored in data base, At wsn, state tag and node label data are set to 0 in normal state, and when wsn is in alert status, all nodes upload The state tag data of data be set to 1；The node label data that Monitoring Data exceedes danger threshold is set to 1.When wsn is in danger During dangerous state, the state tag data of the data that all nodes upload is set to 2；Monitoring Data exceedes the node label of danger threshold Data is set to 2.When dangerous can occur by both label rapid extraction down-hole in called data the data of all wsn and The data of Dangerous Place wireless senser occurs, and quickly clears casualty data structure.

Complete based on event driven wireless sensor network under coal mine system through aforementioned four step.

Beneficial effect: the present invention is that one kind is based on event driven underground coal mine wsn system, based on event driven wsn In node energy consumption control strategy by effective life cycle extending network, event driven is ensured that by appropriate design simultaneously Wsn, in the monitoring capacity of clutch, improves critical data extraction rate.Adaptation coal is proposed on the basis of original Routing Protocol The selection algorithm of the optimum cluster head quantity of ore deposit subsurface environment, has higher adaptive faculty for long and narrow landform.The present invention also designs Have an accident or Monitoring Data numerical value close to danger threshold when wsn coping strategy.The design of the present invention is not reducing peace Improve underground coal mine wsn network life in the case of full property, be to ensure that wireless supervisory control system can when Environment of Mine Disaster occurs The key effectively implemented.

Brief description

Accompanying drawing is that in the present invention, one kind is based on event driven wireless sensor network under coal mine system schematic.

Fig. 1 is based on event driven wsn node working mode figure

Fig. 2 threshold value and the graph of a relation of node working condition

The energy consumption model figure of Fig. 3 transmitting and receiving device

Specific embodiment

The present invention will be further described with reference to the accompanying drawings and examples and describes in detail.

(1) as shown in figure 1, being divided into sensor node according to the working condition of wireless communication module: send state, reception State and resting state.Can mutually change between three kinds of states of sensor node.

(2) trigger event when threshold value is exceeded based on certain node monitors data of event driven underground coal mine wsn, now Entered sending mode by this node event driven；Node in a dormant state receives useful signal, can make node from not Dormancy state proceeds to reception state；It is in the node of transmission state or reception state, if non-transmission signal within a period of time, should Node is changed into resting state from transmission state or reception state.

(3) according to safety regulations in coal mine, by the gas density of wherein defined, carbonomonoxide concentration, temperature etc. refers to safely Target 80% is set to the threshold value of warning of wsn, and in production operation, Monitoring Data exceedes threshold value of warning and then triggers early warning event, base station To in network, all nodes send signal, concept transfer mode of operation, improve node data upload frequencies.By safety regulations in coal mine The danger threshold being set to event triggering of middle items safety index, in production operation, Monitoring Data exceedes danger threshold and then triggers Hazard event, concept transfer mode of operation, improves node data upload frequencies and emergency plan for accidents is opened by mine.First will Normal state is the original state of network, and in whole network under normal state, all node institutes Monitoring Data is less than threshold value of warning, In the network when wsn is in normal state, each node uploads a secondary data in every 10 minutes；When the monitored number of a node any in wsn According to more than threshold value of warning and be less than danger threshold, then wsn state is switched to alert status.It is issued to early warning threshold in alert status The node of value opens real-time Transmission pattern, and the node that other are not up to threshold value of warning uploads a secondary data in every 30 seconds.When institute in wsn Have node institute Monitoring Data numerical value drop to below threshold value of warning and keep 20 minutes then wsn return to normal state, also can section Point Monitoring Data numerical value returns to artificially makes it recover normal state to network transmission instruction during below threshold value of warning.When in wsn Any node institute Monitoring Data reaches danger threshold, then state is switched to precarious position by wsn.Now all nodes in network Open real-time Transmission mode of operation immediately, instruction can be sent by artificial to network when Monitoring Data is less than danger threshold Gone out.

(4) Routing Protocol of event driven wsn is designed according to content of the invention (4) Routing Protocol part.

(5) state tag and node label data are set to 0, when wsn is in alert status to wsn in normal operation When, the state tag data of the data that all nodes upload is set to 1；The node label data that Monitoring Data exceedes danger threshold is put For 1.When wsn is in the hole, the state tag data of the data that all nodes upload is set to 2；Monitoring Data exceedes danger The node label data of dangerous threshold value is set to 2.When dangerous can occur by both label rapid extraction down-hole in called data The data of all wsn and the data that Dangerous Place wireless senser occurs, and quickly clear casualty data structure.

The above is the better embodiment of the present invention, and is not the restriction to embodiments of the present invention. For those of ordinary skill in the field, the change of other multi-forms can also be made on the basis of the above description And variation.Here the embodiment having cannot be exhaustive more.Every belong to that technical scheme amplified out aobvious And the change being clear to or change still in protection scope of the present invention row.

Claims (4)

1. a kind of be based on event driven wireless sensor network under coal mine system, described system mainly include base station equipment and Down-hole node device；It is characterized in that: base station equipment includes monitor terminal, dispatching desk, location-server, storage server and friendship Change planes；Monitor terminal, dispatching desk, location-server, storage server all access backbone network, are communicated by backbone network；Hand over The nucleus equipment changed planes as backbone network；Target node device includes processor, buzzer, energy supply module, methane content inspection Survey device, button, vibrations motor, temperature sensor, carbon monoxide transducer, wireless communication module；Node device is equidistant Interlaced arrangement is in the both sides in tunnel.

2. system according to claim 1 is it is characterised in that the State Transferring of node and threshold value choice phase, Routing Protocol Establishment stage and casualty data extract the stage.Described State Transferring is as follows with the workflow of threshold value choice phase:

(1) sensor node state is divided into: send state, reception state and resting state.Three kinds of states of sensor node it Between can mutually change.When event does not trigger, sensor node in a dormant state, touches when node monitors data exceedes threshold value The event of sending out, is now subject to event driven node to enter sending mode；Node in a dormant state receives useful signal, can make Node proceeds to reception state from resting state；It is in the node of transmission state or reception state, if not transmitting within a period of time Signal, then this node be changed into resting state from transmission state or reception state.

(2) according to safety regulations in coal mine, by the gas density of wherein defined, carbonomonoxide concentration, the safety index such as temperature 80% is set to threshold value of warning, and in production operation, Monitoring Data exceedes threshold value of warning and then triggers early warning event, and base station is in network All nodes send signal, concept transfer mode of operation, improve node data upload frequencies.By peace every in safety regulations in coal mine It is set to the danger threshold of event triggering all referring to target, Monitoring Data exceedes danger threshold and then triggers dangerous thing in production operation Part, concept transfer mode of operation, improves node data upload frequencies and emergency plan for accidents is opened by mine.Described node work Pattern includes: normal state, alert status and precarious position, and specific works step is as follows:

A (), by the original state that normal state is network, in whole network under normal state, all node institutes Monitoring Data is less than Threshold value of warning, in the network when wsn is in normal state, each node uploads a secondary data in every 10 minutes.

B () when a node institute Monitoring Data any in wsn is more than threshold value of warning and is less than danger threshold, then state is switched by wsn For alert status.The node being issued to threshold value of warning in alert status opens real-time Transmission pattern, and other are not up to threshold value of warning Every 30 seconds of node upload a secondary data.When in wsn, all node institutes Monitoring Data numerical value drops to below threshold value of warning and keeps 20 minutes then wsn return to normal state, also can be when node monitors value data returns to below threshold value of warning artificially to net Network sends instruction makes it recover normal state.

(c) precarious position: when a node institute Monitoring Data any in wsn reaches danger threshold, then state is switched to danger by wsn State.Now in network, all nodes open real-time Transmission mode of operation immediately, until Monitoring Data is less than danger threshold when side Can be gone out to network transmission instruction by artificial.

3. described in, Routing Protocol establishment stage comprises the following steps:

The design, according to underground coal mine node deployment position characteristics, modified model leach clustering route protocol is used for downhole event In driving wsn.

Leach agreement cluster head random-selection node in a circulating manner, the energy load of whole network is evenly distributed to each In sensor node, thus reducing network energy resource consumption, the purpose of raising network entirety life span.But answer actual Possible distribution is relatively uneven in the entire network for the cluster head node chosen with middle wsn, and the leader cluster node number randomly generating can not Ensure in optimum range, thus causing network energy consumption load distribution not good.In the establishment stage of leach algorithm, the choosing of cluster head Take mainly by node produce 0 to 1 between random number determine, contrast random number whether reach threshold value t (n), if node with Machine number is more than t (n), then this node becomes the member node of epicycle, otherwise as leader cluster node.T (n) such as formula (1) gained:

Wherein, p is the ratio of leader cluster node number and non-leader cluster node number, and r represents election wheel number；G be nearest 1/p wheel in from It is not elected as the node set of cluster head.

From formula (1), the leader cluster node of leach election does not consider the dump energy of node, if being chosen as the node of cluster head Dump energy is very few, then this cluster head is just by premature death, thus affecting the network life of whole wsn.And leach algorithm is not Relate to cluster head is uniformly distributed problem, if cluster head distribution is excessively concentrated, can waste Internet resources in a large number.Therefore, using as follows Method given threshold:

In formula, n_liveFor remaining surviving node number, e_cFor residue energy of node, d_tobsDistance for node to base station.When node Dump energy e_cBigger, t (n) will increase therewith, then the probability that the big node of dump energy is elected as cluster head increases；In addition, When nodal distance base station farther out when, node be elected as cluster head probability less it is therefore prevented that cluster head marginalisation distribution.

Although the algorithm after improvement reduces cluster head marginalisation distribution to a certain extent, do not solve to choose optimal cluster in network The problem of head quantity.In order to obtain the optimal number of cluster head, the present invention proposes and is applied to underground coal mine long and narrow tunnel environment Optimum cluster head quantity choosing method.Assume that wsn often takes turns k cluster head of generation, k is related to entirely as an important systematic parameter The energy loss of network and life span.The present invention to calculate the optimum value of k (as Fig. 3 using the energy consumption model of in figure Shown).

e_s(c, d) represents the energy consumption of discharger；e_rC () represents the energy consumption of reception device.e_elec* c represents radiating circuit and reception The energy consumption of circuit, circuit total energy consumption is directly proportional to data package size c.Introduce slow fading d², rapid fading d⁴, μ_ampFor signal amplifier Permanent ginseng.If transmitting-receiving two-end distance threshold value is d₀, it is typically set to cluster center to the maximum distance on cluster side, less than d₀Using slow Fading model (fs), on the contrary use rapid fading model (mp).

In signals transmission, each node sends the packet of lbit in current time slots, and transmission range is d, then sensor emission dress The energy loss put is:

The energy loss of reception device is:

e_r(c)=le_elec(3)

Assume have n node to be evenly distributed in the long and narrow tunnel for s for the down-hole gross area, if there being k cluster in network, each In cluster, average nodal number is n/k, including a leader cluster node and n/k-1 cluster member, data fusion can consume e_daRepresent. The energy consumption of cluster head node is made up of three parts: understands that the energy consumption receiving cluster member transmission data is le by formula (3)_elec((n/ K) -1) total energy consumption that, cluster inner tuft head node data merges is le_da(n/k) it is assumed that data fusion here is to be perfectly combined. Cluster head issues the energy loss of lower base station the data after mergingTherefore leader cluster node is often taken turns consumed energy and is:

Wherein d_tobsRepresent cluster head to the distance of base station.

The energy sending data consumption to cluster head in every frame from formula (3) each cluster member is:

Wherein d_tochRepresent cluster member to the distance of leader cluster node.In network, each cluster occupied area is about s/k.Assume that node exists In cluster, the probability density of distribution is ρ (x, y), and each leader cluster node is located at cluster center, then d² _tochAverage be:

Hypothesis each cluster in tunnel is approximately the rectangular area of an a width of a, the then a length of s/ in this region (ka).Substitute into above-mentioned public affairs Formula obtains:

Because ρ (x, y) (5) is non-uniform probability distribution, then ρ=(1/ (s/k)).Substitute into formula (6) to simplify:

Again formula (7) is substituted into formula (5) to obtain

So, energy loss in every frame for each cluster is:

e_cluster=e_ch+((n/k)-1)e_non-ch≈e_ch+(n/k)e_non-ch(9)

Again formula (4) and formula (8) are substituted into formula (9), the energy summation of the loss in every frame for all clusters is:

By to e_totalDerivation set to 0 after can obtain optimal value:

4. the job step that casualty data described in extracts the stage is as follows:

The data that base station receives adds state and node label when being stored in data base, state mark in normal state at wsn Sign and node label data is set to 0, when wsn is in alert status, the state tag data of the data that all nodes upload is put For 1；The node label data that Monitoring Data exceedes danger threshold is set to 1.When wsn is in the hole, all nodes upload The state tag data of data be set to 2；The node label data that Monitoring Data exceedes danger threshold is set to 2.In called data When the data of all wsn and Dangerous Place wireless senser occur when dangerous can occur by both label rapid extraction down-hole Data, and quickly clear casualty data structure.