A method for identifying the coverage range of a non - continuously distributed fire station

Abstract

The present invention is applicable to the field of fire safety technology and relates to a method for identifying the coverage range of discontinuous distribution of fire stations. By dividing cells according to the range of fire rescue demand points, the actual coverage area of the fire station can be effectively calculated. According to the coverage of demand points in the cells, it can be determined whether each cell is within the coverage range of the fire station. It takes into account the discontinuous distribution characteristics of the fire rescue coverage range and can dynamically and accurately identify each area within the coverage range according to the real-time road conditions. The fire department can divide the fire responsibility areas more scientifically, allocate rescue resources more reasonably, improve the utilization efficiency of fire resources, and provide an effective reference method for the optimal allocation and dispatching of fire rescue resources.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire safety, and particularly relates to a method for identifying the coverage range of non-continuously distributed fire stations. Background Art

[0002] Fire is a common accident disaster. Once it occurs, it often causes casualties and property losses, having a serious impact on society. Timely response and effective intervention in firefighting are crucial for reducing the damage caused by fires. Effectively identifying the coverage range of fire stations can more scientifically arrange the dispatching of fire resources and improve the fire response speed. Existing research and applications on the coverage range of fire rescue mainly rely on network analysis methods in geographic information systems. However, these methods usually default that the fire rescue responsibility areas are continuously distributed. The fire rescue area refers to the circumscribed street polygon of the circle defined in the "circular determination method". In fact, the coverage range of fire rescue is not continuously distributed. Due to the lack of a method for identifying the coverage range of non-continuously distributed fire stations, existing research and applications have ignored the non-continuous characteristics of the coverage range of fire stations, resulting in deficiencies in the division of fire rescue responsibility areas, resource allocation, and dispatching.

[0003] The patent application with the publication number CN101763605A provides a three-dimensional digital city fire prevention and control management system. By comprehensively using technologies such as GIS technology, VR technology, and GPS technology, it constructs a fire emergency command three-dimensional geographic information system based on twelve subsystems such as a three-dimensional geographic information system, a GPS satellite positioning and tracking system, a fire safety key unit management system, a traffic route analysis system, a wireless information service system, and a query and statistics system, realizing management functions such as querying the geographical situation of the fire accident site, analyzing the impact of the fire, distributing fire resources, dispatching fire resources, understanding the situation of the fire brigade, and selecting the fire marching route. This patent application also realizes the management of fire resource distribution and fire resource dispatching by constructing a geographic information system, and has the same drawbacks as the existing technology.

[0004] Therefore, how to provide a method for identifying the coverage range of non-continuously distributed fire stations to scientifically divide the fire responsibility area, reasonably allocate rescue resources, and improve the utilization rate of fire resources is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a method for identifying the coverage range of non-continuously distributed fire stations to solve the problems of unscientific division of fire responsibility areas, unreasonable allocation of fire rescue resources, and low utilization rate of fire resources in the existing technology.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for identifying the coverage range of discontinuous distribution of fire stations, including the following steps:

[0008] S10. Determine the number and locations of demand points within the coverage range of the fire station, and preprocess the collected data;

[0009] S20. Calculate the response time of the fire truck from the fire station to each demand point according to the time reduction coefficient and the driving time of ordinary vehicles, and determine whether the demand point is within the effective coverage range of the fire station according to the fire rescue response target value;

[0010] S30. Convert the geographical coordinates of the demand points into plane coordinates relative to the base point, then calculate the coordinate range of the cells according to the distribution of the plane coordinates of all demand points, and divide the cells;

[0011] S40. Determine whether the demand point is within the grid, calculate the demand point density of each cell, and determine whether the cell is effectively covered according to the ratio of the coverable points and non-coverable points within the cell;

[0012] S50. For cells with the same ratio of covered points and uncovered points, set them as transition cells; determine the coverage status of the central cell by checking the coverage of the neighboring cells of the transition cell;

[0013] S60. Use the depth-first search or breadth-first search algorithm to traverse all cells, identify and distinguish all contiguous coverable cell domains and zero-risk density cell domains;

[0014] S70. Traverse all coverable cell domains, find the coverable cell domains that are not directly adjacent to the fire station, and define them as rescue enclaves;

[0015] S80. Calculate the area of the rescue enclave and the total area of the cells in the coverage range of the fire station, and perform visual display in combination with the online map to display the service range of the fire station and the rescue enclave.

[0016] Further, in the step S10, the demand points include buildings, schools and hospitals, that is, locations with fire rescue requirements. The locations of the demand points are obtained through on-site investigations, viewing online maps, government public data, and historical fire records, and the collected data is removed of duplicate points and corrected for incorrect data.

[0017] Further, in the step S20, the time reduction coefficient is set as k t , with a value less than 1, and the response time T i of the fire truck from the fire station to the i-th demand point is expressed as follows:

[0018] T i= k t WT i '+ T pre , 0 < k t < 1

[0019] where T i ' is the driving time of a normal vehicle from the fire station to the demand point, and T pre is the time when the fire truck is ready to depart;

[0020] Let λ be the fire rescue response target value. Set T i ≤ λ for the demand points within the coverage range of the fire station, and denote the total number of points outside the range as C E , conversely, for the demand points where T i > λ, they are not within the coverage range of the fire station, and denote the total number of points within the range as C U , and the expression is as follows:

[0021]

[0022] where i is the total number of demand points, and 1 is the indicator function, which has a value of 1 when the condition in the parentheses is true, otherwise 0. When T i ≤ λ, point i is included in C E ; otherwise, when T i > λ, point i is included in C U .

[0023] Furthermore, the specific steps of step S30 are as follows:

[0024] S301. Find the longitude minimum coordinate and latitude minimum coordinate among all demand points by traversing the longitude and latitude of all demand points, and create a base point according to the longitude minimum coordinate and latitude minimum coordinate;

[0025] S302. Convert the longitude and latitude coordinates of each demand point into radians;

[0026] S303. Convert the geographical coordinates of all demand points into plane coordinates relative to a certain base point;

[0027] S304. Determine the relative position of each demand point to the origin and represent the coverage range of the demand point in the plane coordinates;

[0028] S305. Calculate the coordinate range of the cells according to the distribution of the plane coordinates of all demand points.

[0029] Furthermore, in step S40, let G be the grid divided for the entire range, and N g be the total number of cells in the grid, divided into m × n cells, with m cells in the x - direction and n cells in the y - axis direction. Each grid gij The lower left corner coordinates are (i, j). Determine whether the demand point (x i , y i ) is within the grid g ij The expression is as follows:

[0030] i ≤ x i < i + a

[0031] j ≤ y i < j + a

[0032] Each cell g ij ∈ G contains C gij demand points. Assume that the size of each cell g ij is consistent, all being a 2 . Define the demand point density in cell g ij as d gij . Then:

[0033]

[0034] The expression for whether a cell is effectively covered is as follows:

[0035]

[0036] Where P gU represents the proportion of non - coverable points in a certain cell, P gE represents the proportion of coverable points in a cell, C gU represents the number of non - coverable points in a cell, C gE represents the number of coverable points in a cell, C gij represents the total number of demand points in a cell. If P gU > P gE , it means that the cell is not within the coverable range of the fire station. If P gU < P gE , it means that the cell is within the coverable range of the fire station.

[0037] Furthermore, the specific steps of step S50 are as follows:

[0038] S501. If the proportion of covered points and non - covered points in the cell is the same, that is, P gU = P gE , then temporarily set the cell to a transitional state, defined as a transitional cell;

[0039] S502. By checking whether its neighboring cells are within the coverage range of the fire station, check the coverage of the surrounding c circles of neighboring cells of the central cell to determine whether the central cell is within the coverage range, where c represents traversing c circles of neighboring cells around the central cell of the traversal loop;

[0040] S503. Calculate the weight from the neighboring cells to the central cell, and calculate the number of weighted covered and uncovered cells;

[0041] S504. Determine the coverage status of the central cell according to the number of weighted covered and uncovered cells.

[0042] Further, in step S60, traverse all cells in a serpentine manner starting from the upper left cell of the grid, and determine the termination condition of the traversal according to the number of rows. If starting from the upper left corner and the number of rows is even, the traversal will terminate at the lower left corner; if the number of rows is odd, the traversal will terminate at the lower right corner. Repeat step S60 until all cells are traversed.

[0043] Further, in step S70, traverse each active demand cell domain, and check whether the location of the fire station is included in this area. If not, it is considered that this area belongs to a rescue enclave.

[0044] Further, in step S80, set an indicator function to represent whether the covered cell domain is directly adjacent to the fire station, and calculate the area of the rescue enclave and the total area of the cells in the coverage range of the fire station.

[0045] Further, in step S80, call the display map as the base map to improve the visualization effect.

[0046] Compared with the prior art, the method for identifying the coverage range of non - continuously distributed fire stations provided by the present invention has at least the following beneficial effects:

[0047] Existing research and applications have all ignored the non - continuity characteristics of the coverage range of fire stations, resulting in deficiencies in the division of fire - fighting and rescue responsibility areas, resource allocation, and scheduling. The process of the present invention is simple and the identification is accurate. By dividing cells according to the range of fire - fighting and rescue demand points, it can effectively calculate the actual coverage area of the fire station. According to the coverage of demand points in the cells, it can judge whether each cell is within the coverage range of the fire station, considering the non - continuous distribution characteristics of the fire - fighting and rescue coverage range, and can dynamically and accurately identify each area within the coverage range according to the real - time road conditions. The fire department can scientifically divide the fire - fighting responsibility area, allocate rescue resources more reasonably, improve the utilization efficiency of fire - fighting resources, and provide an effective reference method for the optimal allocation and scheduling of fire - fighting and rescue resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] To more clearly illustrate the solution of the present invention, the following will briefly introduce the figures required for the description of the embodiments. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0049] Figure 1 It is a flowchart of a method for identifying the coverage range of non - continuously distributed fire stations provided by an embodiment of the present invention;

[0050] Figure 2 It is a schematic diagram of the preliminary visualization result of a method for identifying the coverage range of non - continuously distributed fire stations provided by an embodiment of the present invention. Specific implementation manners

[0051] To facilitate the understanding of the present invention, the present invention will be described more comprehensively with reference to the relevant accompanying drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0053] The present invention provides a method for identifying the coverage range of non - continuously distributed fire stations, which is applied to the research and application process of the coverage range of fire rescue. The method for identifying the coverage range of non - continuously distributed fire stations includes the following steps:

[0054] S10. Determine the number and location of demand points within the coverage range of the fire station, and pre - process the collected data;

[0055] S20. Calculate the response time of the fire truck from the fire station to each demand point according to the time reduction coefficient and the driving time of an ordinary car, and determine whether the demand point is within the effective coverage range of the fire station according to the fire rescue response target value;

[0056] S30. Convert the geographical coordinates of the demand points into plane coordinates relative to the base point, then calculate the coordinate range of the grid cells according to the distribution of the plane coordinates of all demand points, and divide the grid cells;

[0057] S40. Determine whether the demand point is within the grid, calculate the demand point density of each cell, and judge whether the cell is effectively covered according to the ratio of the covered points and non - covered points within the cell;

[0058] S50. For cells with the same proportion of covered and uncovered points, set them as transitional cells; determine the coverage status of the central cell by checking the coverage of the neighboring cells of the transitional cells.

[0059] S60. Use the depth-first search or breadth-first search algorithm to traverse all cells, identify and distinguish all contiguous coverable cell domains and zero-risk density cell domains.

[0060] S70. Traverse all coverable cell domains, find the coverable cell domains that are not directly adjacent to the fire station, and define them as rescue enclaves.

[0061] S80. Calculate the area of the rescue enclave and the total area of the cells within the coverable range of the fire station, and perform visual display in combination with the online map to show the service range of the fire station and the rescue enclave.

[0062] The process of the present invention is simple and the identification is accurate. The fire department can allocate rescue resources more reasonably, improve the utilization efficiency of fire resources, and provide an effective reference method for the optimal allocation and scheduling of fire rescue resources.

[0063] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0064] The present invention provides a method for identifying the coverable range of non-continuously distributed fire stations, which is applied to the research and application process of the coverable range of fire rescue, and combines Figure 1 with Figure 2 . In this embodiment, the method for identifying the coverable range of non-continuously distributed fire stations includes the following steps:

[0065] S10. Determine the number and locations of the demand points within the coverage of the fire station, and preprocess the collected data.

[0066] Specifically, assume that there are n demand points within a circular range with a radius of L km centered on a certain fire station. The value range of L is determined according to the fire rescue response time T i and the possible driving speed of the fire truck. Generally speaking, the coverage of fire stations in urban areas is about 4 to 6 kilometers, while the coverage of fire stations in rural or suburban areas is wider because the population and building density in the suburbs are relatively low, and the coverable range of fire stations can reach 8 to 10 kilometers or farther. The demand points refer to potential fire risk points such as buildings, schools, and hospitals. The locations of the demand points can be obtained through on-site investigations, viewing online maps, government public data, historical fire records, etc. Preprocess the collected data to remove duplicate points and correct incorrect data.

[0067] In this embodiment, it is assumed that the potential coverage radius of a certain urban fire station A is 5 km, which is determined based on the fire rescue response time, the driving time of the fire truck, and the distance from the fire station to the demand point. Considering the urban traffic conditions and road conditions, the location information of the demand points is collected by means of on-site investigation, viewing online maps such as Baidu Maps, government public data, historical fire records, etc. The collected demand point data is preprocessed to remove duplicate points, correct incorrect longitude and latitude information, etc., to ensure the accuracy and effectiveness of the data. According to the coverage radius of 5 km of fire station A, all demand points within the coverage range are determined. It is assumed that there are n demand points within 5 km.

[0068] S20. Calculate the response time of the fire truck from the fire station to each demand point according to the time reduction coefficient and the driving time of an ordinary vehicle, and determine whether the demand point is within the effective coverage range of the fire station according to the fire rescue response target value;

[0069] Specifically, the driving time T of an ordinary vehicle from a certain starting point to a certain ending point based on real-time traffic data can be obtained by calling online maps, GIS services, etc. i ', when performing an emergency task, other vehicles should give way to the fire truck, so the driving time T of the fire truck from the fire station to the demand point i should be less than the driving time T of a normal vehicle i '. Set a time reduction coefficient k t , and the value of the reduction coefficient is less than 1.

[0070] The driving time T between the fire station and the i-th demand point can be calculated by the following expression, where T i is the time when the fire truck is ready to depart (in seconds). pre T

[0071] T i =k t ·T i '+T pre , 0 < k t < 1

[0072] Furthermore, in this embodiment, let λ be the fire rescue response target value, in seconds. It is set that the demand points where T i ≤λ are within the coverage range of the fire station, and the total number of these points is denoted as C E . Conversely, the demand points where T i >λ are not within the coverage range of the fire station, and the total number of these points is denoted as C U . As shown in the following expression, i is the total number of demand points, and 1 is the indicator function, whose value is 1 when the condition in the parentheses is true, otherwise 0. When T iWhen λ is less than or equal to, point i is included in C E ; otherwise, when T i is greater than λ, point i is included in C U .

[0073]

[0074] In this embodiment, it is assumed that the response target time of the fire station is 300 seconds (5 minutes), that is, the time for the fire truck to reach the scene from the start of preparation should not exceed 300 seconds. There are the following several demand points and their corresponding response times (in seconds):

[0075] Point A: Response time 250 seconds;

[0076] Point B: Response time 350 seconds;

[0077] Point C: Response time 180 seconds;

[0078] Point D: Response time 400 seconds;

[0079] Judging according to the rules:

[0080] The response times of Point A and Point C are less than 300 seconds, so they are considered to be points within the service coverage of the fire station, that is, they are located within the coverage range of the fire station;

[0081] The response times of Point B and Point D are greater than 300 seconds, so they are considered to be points that cannot be covered by the fire station;

[0082] Therefore, the total number C E of points located within the coverage range of the fire station is 2 (Point A and Point C), while the total number C U of points that cannot be covered is 2 (Point B and Point D).

[0083] S30. Convert the geographical coordinates of the demand points into plane coordinates relative to the base point, then calculate the coordinate range of the cells according to the distribution of the plane coordinates of all demand points, and divide the cells;

[0084] Specifically, the specific steps of step S30 are as follows:

[0085] S301. Create a base point. By traversing the longitude and latitude of all demand points, find the point with the smallest longitude coordinate among all demand points. Its geographical coordinates are (lat i , lng base ), and then find the point with the smallest latitude coordinate. Its geographical coordinates are (lat base , lng j ). Create a base point according to the above content. The expression is as follows:

[0086] latbase = min{lat1, lat2,..., lat N}

[0087] lng base = min{lng1, lng2,..., lng N}

[0088] S302. Convert the latitude and longitude coordinates of each demand point into radians. Use θ i , φ i to represent the latitude and longitude after conversion to radians respectively. The expressions are as follows:

[0089]

[0090] S303. According to the geographical coordinates of all demand points, convert them into plane coordinates (x i , y i ) relative to a certain base point. Use the haversine function to calculate the distance of each demand point relative to the base point. Let (θ i , φ i ) represent the latitude and longitude of the i-th point in the dataset, where i = 1, 2,..., N, and N is the total number of demand points. For each point (θ i , φ i ), calculate the plane coordinates (x i , y i ) of each demand point relative to the base point.

[0091] x i represents the distance of point i relative to the base point on the x-axis. It is the distance between the longitude φ i of the current point and the longitude φ base of the base point, while keeping the latitude θ base unchanged. y i represents the distance of point i relative to the base point coordinates on the y-axis. It is the distance between the latitude θ i of the current point and the latitude θ base of the base point, while keeping the longitude φ base unchanged. The expressions are as follows, where γ is the radius of the earth (6371 km). The expressions are as follows:

[0092]

[0093] Thus, the plane coordinates (x i , y i ) of all demand points can be calculated. According to the plane coordinates (x i , y i ) of each demand point i, calculate the relative position of each demand point to the base point. Set the base point coordinates as the origin coordinates (0, 0) in the plane coordinates.

[0094] S304. Determine the relative position of each demand point with respect to the origin and represent the coverage range of the demand point in the plane coordinates. According to x i , y i the relative position of each demand point (x i , y i ) with respect to the origin (0, 0) can be determined, and then the coverage range of the demand point can be represented in the plane coordinates.

[0095] S305. Calculate the x and y coordinate ranges of the cells according to the planar coordinate distribution of all demand points i. Set the size of each cell to be a 2 square meters. That is, the side length of each cell is a meters. Divide the total range covered by the planar coordinates of the demand points into cells. 0 and xmax are the minimum and maximum coordinate values of the points in the x-axis direction, and 0 and y max are the minimum and maximum coordinate values of the points in the y-axis direction respectively. According to the cell size and the coordinate range, use the following expressions to calculate the boundaries of the cells, x array and y array are the sequences of cell boundary coordinates in the x and y directions respectively, starting from the minimum coordinate and at intervals of the cell size a until exceeding the maximum coordinate.

[0096] x array = {0, a, 2a,..., x max + r}

[0097] y array = {0, a, 2a,..., y max + r}

[0098] 0 < r ≤ a, where r is any real number greater than 0 and less than or equal to a

[0099] In this embodiment, assume that there are the following planar coordinates (in meters) of N demand points in a certain area:

[0100] Point 1: (86, 250)

[0101] Point 2: (150, 200)

[0102] Point 3: (200, 300)

[0103] …

[0104] Point N: (250, 350)

[0105] Divide this area into cells with a size of 50 meters × 50 meters. First, determine the minimum and maximum coordinate values of these points in the x-axis and y-axis directions: Assume that the minimum coordinate value in the x-axis direction is 86 (the x-coordinate of point 1), and the maximum coordinate value is 250 (the x-coordinate of point N); the minimum coordinate value in the y-axis direction is 200 (the y-coordinate of point 1), and the maximum coordinate value is 350 (the y-coordinate of point N).

[0106] According to the cell size and coordinate range, in the x-axis direction, the number of cells is (250 - 86) / 50 + 1 = 4 (round up the calculation result, here r is 1); in the y-axis direction, the number of cells is (350 - 200) / 50 + 1 = 4.

[0107] Therefore, divide this area into 16 cells in 4 rows and 4 columns, and the size of each cell is 50 meters × 50 meters.

[0108] S40. Determine whether the demand point is within the grid, calculate the demand point density of each cell, and determine whether the cell is effectively covered according to the ratio of coverable points and non-coverable points within the cell;

[0109] Specifically, the specific steps of step S40 are as follows:

[0110] S401. Let G be the grid divided for the entire range, N g be the total number of cells in the grid, divided into m × n cells, with m cells in the x-direction and n cells in the y-axis direction. The lower left corner coordinates of each grid g ij are (i, j), and the following expression can be used to determine whether the demand point (x i , y i ) is within the grid g ij .

[0111] i ≤ x i < i + a

[0112] j ≤ y i < j + a

[0113] Each cell g ij ∈G contains C gij demand points. For each cell g ij , C gij is the number of demand points in cell g ij . In this embodiment, it is set that the size of each cell g ij is the same, all a 2 . If a higher demand point density in a larger range is required, a larger a can be selected. a generally ranges from 50 to 150 meters (the width of general buildings). Define cell g ijThe demand point density in it is d gij , and the expression is as follows:

[0114]

[0115] S402. Traverse all cells, filter out all cells with non-zero density, calculate the ratio of coverable points and non-coverable points in each cell, and determine whether the cell is within the coverable range of the fire station. Use P gU to represent the ratio of non-coverable points in a certain cell, and use P gE to represent the ratio of coverable points in a cell. C gU is the number of non-coverable points in a cell, and C gE represents the number of coverable points in a cell. C gij is the total number of demand points in a cell. According to the ratio of coverable points and non-coverable points in the cell, determine whether the cell is within the coverable range of the fire station. As shown in the following expression, if in this cell, P gU >P gE , it means that this cell is not within the coverable range of this fire station. On the contrary, P gU <P gE , then it means that this cell is within the coverable range of the fire station.

[0116]

[0117] S50. For cells with the same ratio of coverable points and non-coverable points, set them as transitional cells; determine the coverage status of the central cell by checking the coverage of the neighbor cells of the transitional cells;

[0118] Specifically, the specific steps of step S50 are as follows:

[0119] S501. For cells with the same ratio of coverable points and non-coverable points, set them as transitional cells. If the ratio of coverable points and non-coverable points in the cell is the same, that is, P gU =P gE , then temporarily set this cell to a transitional state and define it as a transitional cell;

[0120] S502. Process the transitional cells. By checking whether their neighbor cells are within the coverable range of the fire station, check the coverage of the surrounding c circles of neighbor cells (if traversing and looping through the neighbor cells in one circle around cannot determine the coverage of the central cell, then consider traversing and looping through the neighbor cells in two circles) to determine whether this central cell is within the coverable range. For a certain transitional cell g ij , for the c-th circle of neighbor cells, set N c,ijDenote the set of the c-th ring of neighbor cells around the central cell. Here, c represents traversing the c-th ring of neighbor cells around the central cell. When c = 1, it means traversing the neighbor cells in one ring around the central cell. If the coverage situation of the central cell cannot be determined through the initial traversal, continue to traverse to the neighbor cells in the second ring.

[0121] S503. Calculate the weight from the neighbor cell to the central cell, and calculate the weighted number of covered and uncovered cells. Let w c,ij be the weight from the c-th ring neighbor cell g c,ij to the central cell g ij . The expression of w c,ij is as follows. It is a linear function based on distance. In the formula, is the distance from the central cell g ij to the cells in the c-th ring. Assume that the coverage status of each cell is represented by a variable, where being covered is 1 and not being covered is 0. Denote this variable as S ij . The expression is as follows. β is an adjustment parameter, and β usually takes values between 0 and . It is used to control the influence of distance on the weight, and the weight decreases as the distance increases.

[0122]

[0123]

[0124] is the weighted number of covered cells, representing the weighted number of covered cells among the c-th ring neighbor cells. For each neighbor cell, if it is covered, multiply it by the corresponding weight w c,ij and sum them up. The expression is as follows:

[0125]

[0126] represents the weighted number of uncovered cells, representing the weighted number of uncovered cells among the c-th ring neighbor cells. The calculation method is similar to that of . The expression is as follows:

[0127]

[0128] S504. Determine the coverage status of the central cell according to the weighted number of covered and uncovered cells. If then the central cell g ij is within the coverable range of the fire station; if then the central cell g ij is an uncovered cell; if Then, it is necessary to check the second - layer neighbor cells and repeat step S503, so that all transitional cells can be processed, and finally only coverable cells and non - coverable cells remain.

[0129] S60. Use the depth - first search or breadth - first search algorithm to traverse all cells, identify and distinguish all contiguous coverable cell regions and zero - risk - density cell regions;

[0130] Specifically, the specific steps of step S60 are as follows:

[0131] S601. Traverse the grid in a snake - like pattern, and define three direction vectors, Δg right = [1, 0] is used to represent moving one cell to the right, Δg left = [-1, 0] represents moving one cell to the left, Δg down = [0, 1] represents moving one cell downwards;

[0132] S602. Start traversing all cells in a snake - like pattern from the top - left cell of the grid, and initialize two sets: S low for storing low - risk interest cells, S active for storing coverable cells. Set a variable direction to represent the current moving direction, and the initial value is set to check horizontally to the right. The initialization expressions are as follows:

[0133] direction initial = Δg right = [1, 0]

[0134] i = 0, j = n - 1

[0135] During the traversal process, according to the row number i and column number j and the current direction, determine whether to change the direction. Whenever the end of a row is traversed, the traversal direction will change. If the current direction is to the right and reaches the right end of the row (i = m - 1), or the current direction is to the left and reaches the left end of the row i = 0, then after moving down one row i' = i + 1, change the horizontal traversal direction. The specific traversal logic expressions are as follows:

[0136] · Traverse to the right: if direction = [1, 0] ∩ i < m - 1, then i' = i + 1

[0137] · Traverse to the left: if direction = [-1, 0] ∩ i > 0, then i' = i - 1

[0138] · Reaching the boundary and changing the direction:

[0139] if direction = [1,0] ∩ i = m - 1, then j' = j - 1, direction = [-1,0]

[0140] if direction = [-1,0] ∩ i = 0, then j' = j - 1, direction = [1,0]

[0141] S603. Determine the termination condition for traversal based on the number of rows. In the case of snake-shaped traversal, if starting from the upper left corner and the number of rows is even, the traversal will terminate at the lower left corner; if the number of rows is odd, the traversal will terminate at the lower right corner. The termination condition expression is as follows:

[0142]

[0143] S604. Repeat step S603 until all cells are traversed, ensuring that all cells are stored in the set S active and S low ;

[0144] S605. Search algorithms such as depth-first search (DFS) or breadth-first search (BFS) can be used to traverse all cells. Each cell is regarded as a node, and each node has four direct neighbors (up, down, left, right). Starting from a certain starting node, explore deeply along a path until it can no longer continue, and then backtrack to the previous node to continue exploring other paths. During the process of traversing all cells, continuous cells of the same type can be identified. When visiting a cell, all unvisited neighbors of this cell will be recursively visited. Starting from the starting node, all cells connected to it can be visited, and then continuous regions are formed. According to the distinguishable coverable cells and zero-risk density cells previously distinguished, all continuous coverable cell regions and zero-risk density cell regions can be identified and distinguished;

[0145] S606. Define continuous cell regions and distinguish zero-risk density cell regions and coverable cell regions. In this embodiment, continuous cells are defined as cell region A (m) , m represents the number of cells included in the cell region. Define the region composed of the cells in the recorded set S low as the zero-risk density cell region, and define the region composed of the cells in the recorded set S active as the coverable cell region.

[0146] S607. Exclude some small cell areas that have fire rescue requirements but no demand points are detected, and determine the zero-risk density cell areas. Only when the number of cells contained in a cell area reaches a certain threshold is the area considered to belong to the zero-risk density cell area and does not require fire rescue. Specifically, set a quantity threshold N g ·p, where p is a proportionality coefficient between 0 and 1 and can be adjusted according to the actual situation. For example, if you want to screen low-risk areas more strictly, you can choose a smaller proportionality coefficient. If the number of cells contained in a cell area is greater than or equal to the quantity threshold N g ·p, then this area is classified as a zero-risk density cell area and is considered an area that does not need to be covered by fire rescue. In this embodiment, only when m≥N g ·p, this area is classified into a set A (m) , and the expression is as follows. In the subsequent calculations, the zero-risk density cell area is represented by A U(m) and the coverable cell area is represented by A E(m) . The zero-risk density cell area is not considered within the scope that needs to be covered by fire rescue.

[0147] A (m) = A U(m) + A E(m)

[0148] A U(m) = {g 11 , g 12 ,..., g ij}

[0149] m≥N g ·p, p∈(0, 1)

[0150] g 11 , g 12 ,..., g ij ∈ G

[0151] In this embodiment, all zero-risk density cells will form several cell areas. A threshold is set to determine whether a cell area is large enough to be recognized as a zero-risk density cell area. Assuming that according to geographical features and the number of cells, the threshold is set to 5% of the total number of cells in the grid, that is, m≥N g ·5%. Only when the number of cells in a certain zero-risk density cell area reaches the quantity threshold is it classified as a zero-risk density cell area and is considered that the area does not require fire rescue.

[0152] S70. Traverse all coverable cell areas, find the coverable cell areas that are not directly adjacent to the fire station, and define them as rescue enclaves;

[0153] Specifically, in this embodiment, each active demand cell area is traversed to check whether the location of the fire station is included in this area. If not, this area is considered a rescue enclave. For each A n ∈A E(m) , it is checked whether there exists (x i , y i ) ∈ A n such that (x i , y i ) = (x f , y f ). If no such cell exists, this area A n is considered a rescue enclave, that is, there does not exist (x i , y i ) ∈ A n such that (x i , y i ) = (x f , y f ).

[0154] S80. Calculate the area of the rescue enclave and the total area of the cells within the coverage range of the fire station, and combine with the online map for visual display to show the service range of the fire station and the rescue enclave.

[0155] Specifically, the JavaScript API (Application Programming Interface) of the online map is used to call and display the map as the base map to improve the visualization effect. The online map API is an interface that provides map services and data, allowing developers to embed and display maps in web pages or applications and perform customized development. To call the map as the base map, it is necessary to register on the online map open platform and obtain an API key. This key is the credential for calling the online map service. Then, the JavaScript library of the online map API is introduced in the HTML page. Next, the obtained key is used to initialize the map, create a map instance, and set the location of the fire station as the center point coordinates of the map and an appropriate zoom level.

[0156] As Figure 2 shown, after the map is initialized, according to the calculated cell status of the fire rescue coverage range, different gray scale markings are made on the map. The cells within the coverage range and those outside the coverage range are distinguished by different colors. The zero-risk density cell area is not given any color.

[0157] Furthermore, in this embodiment, an indicator function is set to represent whether the coverable cell area is directly adjacent to the fire station. Calculate the area of the rescue enclave and the total area of the cells within the coverage range of the fire station. Set an indicator function I(g) to represent whether the coverable cell area is directly adjacent to the fire station. The expression is as follows:

[0158]

[0159] The area A of the rescue enclave Ex is calculated by the following expression:

[0160]

[0161] The total area of the cells within the coverage range of the fire station is calculated by the following expression, where N gE represents the total number of all cells within the coverage range, and AgE represents the total area of the cells within the coverage range of the fire station.

[0162] A gE = a 2 ·N gE

[0163] The fire rescue coverage range and the uncovered range are represented on the cells. Using an online map as the base map, the fire coverage range and the uncovered areas are marked with different colors in the cells on the map. This can visually display the service range of the fire station, and at the same time, rescue enclaves and rescue blind spots are discovered.

[0164] Compared with the prior art, the method for identifying the discontinuous distribution of the fire station coverage range in the above embodiments is that existing research and applications have ignored the discontinuous characteristics of the fire station coverage range, resulting in deficiencies in the division of fire rescue responsibility areas, resource allocation, and scheduling. The process of the present invention is simple and the identification is accurate. By dividing cells according to the range of fire rescue demand points, the actual coverage area of the fire station can be effectively calculated. According to the coverage situation of demand points in the cells, it can be judged whether each cell is within the coverage range of the fire station. It considers the discontinuous distribution characteristics of the fire rescue coverage range, and can dynamically and accurately identify each area within the coverage range according to the real-time road conditions. The fire department can scientifically divide the fire responsibility area, allocate rescue resources more reasonably, improve the utilization efficiency of fire resources, and provide an effective reference method for the optimal allocation and scheduling of fire rescue resources.

[0165] Obviously, the embodiments described above are only the preferred embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are shown in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing specific embodiments, or perform equivalent replacements on some of the technical features. Any equivalent structure made by using the content of the specification and drawings of the present invention, directly or indirectly applied in other related technical fields, is equally within the scope of protection of the present invention patent.

Claims

1. A method for identifying the coverage range of a non - continuously distributed fire station, characterized in that, It includes the following steps: S10. Determine the number and locations of demand points within the coverage of the fire station, and preprocess the collected data; S20. Calculate the response time of the fire truck from the fire station to each demand point according to the time reduction coefficient and the travel time of an ordinary car, and judge whether the demand point is within the effective coverage of the fire station according to the fire rescue response target value; In the step S20, the time reduction coefficient is set to k t , where the value is less than 1, and the response time T of the fire truck traveling from the fire station to the i-th demand point i is expressed as follows: T i = k t ·T i '+ T pre , 0 < k t < 1 Among them, T i ' is the driving time of a normal vehicle from the fire station to the demand point, and T pre is the time when the fire truck is ready to depart; Let λ be the fire rescue response target value, and set T i The demand points where i ≤ λ are within the coverage range of the fire station, and the total number of points not within the range is denoted as C E , conversely, for T i > λ, the demand points are not within the coverage range of the fire station, and the total number of points within the range is denoted as C U The expressions are as follows: where i is the total number of demand points, 1 is the indicator function which has a value of 1 when the condition in the parentheses is true and 0 otherwise, and point i is included in C when T i ≤ λ E ; otherwise, when T i > λ U ; S30. Convert the geographic coordinates of the demand points into plane coordinates relative to the base point, then calculate the coordinate range of the cells according to the distribution of the plane coordinates of all demand points, and divide the cells; The specific steps of step S30 are as follows: S301. Find the minimum longitude coordinate and the minimum latitude coordinate among all demand points by traversing the longitude and latitude of all demand points, and create a base point according to the minimum longitude coordinate and the minimum latitude coordinate; S302. Convert the longitude and latitude coordinates of each demand point into radians; S303. Convert the geographic coordinates of all demand points into plane coordinates relative to a certain base point; S304. Determine the relative position of each demand point to the origin, and represent the coverage range of the demand point in the plane coordinates; S305. Calculate the coordinate range of the cells according to the distribution of the plane coordinates of all demand points; S40. Judge whether the demand point is within the grid, calculate the demand point density of each cell, and judge whether the cell is effectively covered according to the ratio of the coverable points and non-coverable points within the cell; In step S40, let G be the grid divided for the entire range, and N g be the total number of cells in the grid, divided into m×n cells, with m cells in the x direction and n cells in the y axis direction. The lower left corner coordinates of each grid g ij are (i,j). The expression for determining whether the demand point (x i ,y i ) is within the grid g ij is as follows: i ≤ x i <i + a j ≤ y i <j + a Each cell g ij ∈ G contains C gij demand points. Set the size of each cell g ij to be consistent, all being a 2 , and define the demand point density in cell g ij as d gij , then: The expression for whether the cell is effectively covered is as follows: Among them, P gU represents the proportion of non-coverable points in a certain cell, P gE represents the proportion of coverable points in a cell, C gU represents the number of non-coverable points in a cell, C gE represents the number of coverable points in a cell, C gij represents the total number of demand points in a cell. If P gU >P gE , it means that the cell is not within the coverable range of the fire station. If P gU <P gE , it indicates that the cell is within the coverable range of the fire station; S50. For cells with the same ratio of covered points and uncovered points, set them as transition cells; determine the coverage status of the central cell by checking the coverage of the neighboring cells of the transition cell; The specific steps of step S50 are as follows: S501. If the ratio of covered points to uncovered points in a cell is the same, i.e., P gU = P gE , then temporarily set this cell to a transitional state and define it as a transitional cell; S502. Check whether the central cell is within the coverable range by checking whether its neighboring cells are within the coverable range of the fire station, and check the coverage of the surrounding c circles of neighboring cells of the central cell. c represents traversing and cycling through c circles of neighboring cells around the central cell; S503. Calculate the weight from the neighboring cell to the central cell, and calculate the number of weighted coverable and uncovered cells; S504. Judge the coverage status of the central cell according to the number of weighted coverable and uncovered cells; S60. Use the depth-first search or breadth-first search algorithm to traverse all cells, identify and distinguish all contiguous coverable cell domains and zero-risk density cell domains; S70. Traverse all coverable cell domains, find coverable cell domains that are not directly adjacent to the fire station, and define them as rescue enclaves; Traverse each active demand cell domain, check whether the location of the fire station is included in the active demand cell domain, if not, then consider this area as a rescue enclave; S80. Calculate the area of the rescue enclave and the total area of the cells within the coverable range of the fire station, and combine with the online map for visual display to show the service range of the fire station and the rescue enclave.

2. The method for identifying the coverage range of a non - continuously distributed fire station according to claim 1, wherein In the step S10, the demand points include buildings, schools, and hospitals, that is, the locations where there is a need for fire rescue. The locations of the demand points are obtained through on-site investigations, viewing online maps, government open data, and historical fire records, and the collected data is de-duplicated and incorrect data is corrected.

3. A method for identifying the coverage range of a non - continuously distributed fire station according to claim 1, characterized in that In the step S60, starting from the upper left cell of the grid, all cells are traversed in a snake-like manner, and the termination condition of the traversal is determined according to the number of rows. If starting from the upper left corner and the number of rows is even, the traversal will terminate at the lower left corner; if the number of rows is odd, the traversal will terminate at the lower right corner. The step S60 is repeated until all cells are traversed.

4. The method for identifying the coverage range of a non - continuously distributed fire station according to claim 1, wherein, In the step S80, an indicator function is set to represent whether the cell domain that can be covered is directly adjacent to the fire station, and the area of the rescue enclave and the total area of the cells in the coverage range of the fire station are calculated.

5. A method for identifying the coverage range of a non - continuously distributed fire station according to claim 4, characterized in that, In the step S80, the display map is called as the base map to improve the visualization effect.

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