阅读说明：本技术 一种近海区域方形人工鱼礁空间布局优化方法 (Offshore area square artificial fish reef spatial layout optimization method ) 是由 孙涛 舒安平 秦际平 杨薇 朱家品 于 2021-11-02 设计创作，主要内容包括：本发明公开了一种近海区域方形人工鱼礁空间布局优化方法,包括以下步骤：制作方形鱼礁单体模型；建立正方形单位鱼礁；选择与水流方向平行的对角线上的三个鱼礁组为实验对象,设置了4种不同的鱼礁组间距条件；通过水槽实验获取到的数据,整理得到不同空间布局下的各个评价指标数据；采用客观赋权法中的熵值法作为单位鱼礁流场效应评价的赋权方法；基于水动力学的单位鱼礁布局方案评价；基于水动力学和经济成本的单位鱼礁布局方案评价；根据上述两种方案评价的评价结果,综合考虑生态效益与经济成本,最终确定最佳的布局优化方案。本发明的优点是：造价均减少,所影响的流场范围面积分别增大。以更少的经济投入获得了更大的生态效益。(The invention discloses a spatial layout optimization method of a square artificial fish reef in an offshore area, which comprises the following steps: manufacturing a square fish reef monomer model; building a square unit fish reef; selecting three fish reef groups on a diagonal line parallel to the water flow direction as an experimental object, and setting 4 different fish reef group spacing conditions; data obtained through a water tank experiment are arranged to obtain each evaluation index data under different spatial layouts; an entropy method in an objective weighting method is adopted as a weighting method for evaluating the flow field effect of the unit fish reef; evaluating a unit fish reef layout scheme based on hydrodynamics; evaluating a unit fish reef layout scheme based on hydrodynamics and economic cost; and according to the evaluation results of the two schemes, ecological benefit and economic cost are comprehensively considered, and the optimal layout optimization scheme is finally determined. The invention has the advantages that: the manufacturing cost is reduced, and the area of the affected flow field is respectively increased. Greater ecological benefits are obtained with less economic investment.)

1. A spatial layout optimization method for a square artificial fish reef in an offshore area is characterized by comprising the following steps:

step 1, manufacturing a square fish reef monomer model by using organic glass according to a geometric scale of 50: 1.

And 2, establishing square unit fish reefs which are distributed in the water tank bottom plate, wherein 15 square fish reef monomer reef models form a group of square unit fish reefs, a group of fish reef groups are respectively arranged at four corners and the center of each unit fish reef, and the group of fish reef groups consists of three square fish reef monomer reef models and are arranged in a shape of Chinese character 'pin'.

And 3, selecting three fish reef groups on a diagonal line parallel to the water flow direction as an experimental object. During the experiment, square fish reef unit fish reef comprises 9 monomer reefs, and every group is 3 monomer reefs that are the article font and arrange, has set up 4 different fish reef interbank apart from the condition.

Step 4, sorting the data obtained through the water tank experiment to obtain each evaluation index data under different spatial layouts; totally selecting 11 evaluation indexes, wherein the number of the upflow indexes is 5, and the evaluation indexes comprise maximum upflow speed, upflow average speed, upflow maximum height, upflow maximum length and upflow total area; back vortex indexes are 3, including the maximum height of the back vortex, the maximum length of the back vortex and the total area of the back vortex; 2 turbulence intensity indexes are provided, including the average longitudinal turbulence intensity and the average vertical turbulence intensity of the whole flow field; the economic cost index is 1, and the cost of the unit fish reef is per square meter; selecting an extreme value processing method to carry out dimensionless operation on the evaluation index of the flow field effect of the fish reef unit;

and 5, adopting an entropy method in an objective weighting method as a weighting method for evaluating the flow field effect of the unit fish reef, wherein the weighting method comprises the following steps:

(1) constructing a multi-object and multi-index matrix; let n objects (n) in the evaluation index system₁，n₂，…，n_n) M indices (m)₁，m₂，…，m_m) Let the j-th index (j-1, 2, 3.., m) of the i-th evaluation object (i-1, 2, 3.., n) take the value of X_ijConstructing an original index data matrix X:

(2) dimensionless raw data, eliminating dimension influence, and calculating characteristic proportion or contribution (p) of ith evaluation object under jth index_ij)：

Wherein Z_ijRepresents the score of the ith evaluation object under the j index;

(3) calculating the entropy (e) of the jth index_j)：

In the formula, ln is a natural logarithm,e_j≥0

(4) calculating the difference coefficient (g) of the j index_j)：

g_j＝1-e_j (4)

Normalizing the difference coefficient, and calculating the weight (W) of the j index_j)：

(5) Calculating the comprehensive score (Y) of each index of the ith evaluation object_i)：

Step 6, evaluating a unit fish reef layout scheme based on hydrodynamics;

selecting the flow field effect of the unit fish reef at four intervals as evaluation objects, wherein each object comprises 5 samples with different flow rates; selecting up-flow, back vortex and turbulence intensity indexes related to hydrodynamic force without bringing economic cost indexes into the indexes, calculating 10 evaluation indexes according to the steps of an entropy method to obtain the weight and comprehensive score of each evaluation index, and performing comparative analysis to obtain an optimal result;

step 7, evaluating a unit fish reef layout scheme based on hydrodynamics and economic cost;

selecting the flow field effect of the unit fish reef at four intervals as evaluation objects, wherein each object comprises 5 samples with different flow rates; selecting 11 evaluation indexes in the step 1, carrying out corresponding calculation according to the specific steps of an entropy method to obtain the weight and the comprehensive score of each evaluation index, and carrying out comparative analysis to obtain an optimal result;

step 8, optimizing the layout scheme;

and according to the evaluation results of the hydrodynamic unit fish reef layout scheme evaluation and the hydrodynamic and economic unit fish reef layout scheme evaluation, comprehensively considering the ecological benefit and the economic cost, and finally determining the optimal layout optimization scheme.

Technical Field

The invention relates to the technical field of artificial fish reef optimization, in particular to a spatial layout optimization method for a square artificial fish reef in an offshore area.

Background

The artificial fish reef is widely applied to the engineering construction of various oceans and pastures in China with good marine ecological restoration and fishery resource maintenance functions, and becomes a facility foundation for the construction of the oceans and pastures. With the increasingly prominent construction effect of the artificial fish reef, more and more coastal areas open the current situation of large-scale feeding. The square multifunctional composite ecological reef is a square structure which is manually placed in a natural water area environment and is used for repairing and optimizing the water area ecological environment, the reef body structure is complex (a bait culture net cage and a plate type attachment medium are arranged in the reef body), the bait culture body structure is latticed, shells are filled in the reef body structure, the attachment surface area of organisms is greatly increased, and the attachment of the organisms is favorable for providing good habitat for growth, reproduction, bait taking and enemy avoidance for stichopus japonicus, fishes and the like. The net cage has good creep resistance, is stable and firm, and can not fall off due to long-term stress denaturation.

Before the artificial fish reef is put into the ocean, reasonable planning is carried out, and a configuration mode suitable for a target area and a target species is selected, because the construction of the artificial fish reef is a process with huge and irreversible capital investment, if the expected effect cannot be achieved after the artificial fish reef is put into the ocean, the artificial fish reef cannot be removed, even marine garbage can be generated to cause damage to the ocean environment, and economic loss can be caused. The influence range, flow state distribution, hydrodynamic force characteristics and the like of a flow field generated after the artificial fish reef is thrown are different due to the type, structural shape, scale size, layout and range of the thrown fish reef and the difference of the original flow field of a throwing place, so that the current advantages and disadvantages of the flow field effect of different artificial fish reefs are mostly descriptive researches, namely, the strength, scale and the like of an upwelling flow and a back vortex flow are correspondingly described according to experimental phenomena or numerical simulation results, and the conclusion of a specific advantage and disadvantage degree is obtained after system evaluation by a certain method is lacked.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for optimizing the spatial layout of a square artificial fish reef in the offshore area.

In order to realize the purpose, the technical scheme adopted by the invention is as follows:

a spatial layout optimization method for a square artificial fish reef in an offshore area comprises the following steps:

step 1, manufacturing a square fish reef monomer model by using organic glass according to a geometric scale of 50: 1.

And 2, establishing square unit fish reefs which are distributed in the water tank bottom plate, wherein 15 square fish reef monomer reef models form a group of square unit fish reefs, a group of fish reef groups are respectively arranged at four corners and the center of each unit fish reef, and the group of fish reef groups consists of three square fish reef monomer reef models and are arranged in a shape of Chinese character 'pin'.

And 3, selecting three fish reef groups on a diagonal line parallel to the water flow direction as an experimental object. During the experiment, square fish reef unit fish reef comprises 9 monomer reefs, and every group is 3 monomer reefs that are the article font and arrange, has set up 4 different fish reef interbank apart from the condition.

And 4, acquiring data through a water tank experiment, and sorting to obtain each evaluation index data. Totally selecting 11 evaluation indexes, wherein the number of the upflow indexes is 5, and the evaluation indexes comprise maximum upflow speed, upflow average speed, upflow maximum height, upflow maximum length and upflow total area; back vortex indexes are 3, including the maximum height of the back vortex, the maximum length of the back vortex and the total area of the back vortex; 2 turbulence intensity indexes are provided, including the average longitudinal turbulence intensity and the average vertical turbulence intensity of the whole flow field; the economic cost index is 1, and the cost of the unit fish reef is per square meter. And (4) selecting an extreme value processing method to carry out dimensionless transformation on the evaluation index of the flow field effect of the fish reef in unit.

And 5, adopting an entropy method in an objective weighting method as a weighting method for evaluating the flow field effect of the unit fish reef, wherein the weighting method comprises the following steps:

(1) and constructing a multi-object and multi-index matrix. Let n objects (n) in the evaluation index system₁，n₂，…，n_n) M indices (m)₁，m₂，…，m_m) Let the j-th index (j-1, 2, 3.., m) of the i-th evaluation object (i-1, 2, 3.., n) take the value of X_ijConstructing an original index data matrix X:

(2) dimensionless raw data, eliminating dimension influence, and calculating characteristic proportion or contribution (p) of ith evaluation object under jth index_ij)：

Wherein Z_ijAnd represents the score of the ith evaluation object under the j index.

(3) Calculating the entropy (e) of the jth index_j)：

In the formula, ln is a natural logarithm,e_j≥0

(4) calculating the difference coefficient (g) of the j index_j)：

g_j＝1-e_j (4)

Normalizing the difference coefficient, and calculating the weight (W) of the j index_j)：

(5) Calculating the comprehensive score (Y) of each index of the ith evaluation object_i)：

Step 6, evaluating a unit fish reef layout scheme based on hydrodynamics;

selecting the flow field effect of the unit fish reef at four intervals as an evaluation object, wherein each object comprises 5 samples with different flow rates. And selecting up-flow, back vortex and turbulence intensity indexes related to hydrodynamic force without bringing economic cost indexes into the indexes, calculating 10 evaluation indexes according to the steps of an entropy method, obtaining the weight and comprehensive score of each evaluation index, and performing comparative analysis to obtain an optimal result.

Step 7, evaluating a unit fish reef layout scheme based on hydrodynamics and economic cost;

selecting the flow field effect of the unit fish reef at four intervals as an evaluation object, wherein each object comprises 5 samples with different flow rates. And (3) selecting 11 evaluation indexes in the step (1), correspondingly calculating according to the specific steps of the entropy method to obtain the weight and the comprehensive score of each evaluation index, and carrying out comparative analysis to obtain the optimal result.

Step 8, optimizing the layout scheme;

and according to the evaluation results of the hydrodynamic unit fish reef layout scheme evaluation and the hydrodynamic and economic unit fish reef layout scheme evaluation, comprehensively considering the ecological benefit and the economic cost, and finally determining the optimal layout optimization scheme.

Compared with the prior art, the invention has the advantages that:

by adopting an entropy method, the balance problem of ecological benefit and capital investment in artificial fish reef construction is discussed by combining flow field effect quantitative analysis and economic cost index accounting of fish reefs of different scales and units, and the putting layout of a typical artificial fish reef is optimized and adjusted from the perspective of quantitative evaluation, so that better ecological benefit and economic benefit are achieved. Provides a new thought and technical support for theoretical research and actual construction of the artificial fish reef. The unit fish reefs and the unit reef groups after the spatial layout is adjusted have the advantages that the flow field effect is enhanced compared with the original distance, the number and the cost of the monomer reefs are reduced, the area of the affected flow field range is increased, more ecological benefits are obtained with less economic investment, and better living environments are created for more marine organisms.

Drawings

FIG. 1 is a schematic structural diagram of a square fish reef monomer reef model according to an embodiment of the invention, wherein (a) is a front view, (b) is a left side view, (c) is a top view, and (d) is a perspective view;

FIG. 2 is a schematic diagram of a square unit fish reef structure according to an embodiment of the invention;

FIG. 3 is a schematic diagram illustrating unit fish reef placement among different fish reef sets according to an embodiment of the invention;

FIG. 4 is a comprehensive scoring chart for evaluating the flow field effect of the square fish reef unit based on hydrodynamics in the embodiment of the invention;

FIG. 5 is a comprehensive scoring graph for evaluating the flow field effect of the square fish reef unit based on hydrodynamics and economic cost according to the embodiment of the invention;

FIG. 6 is a comparison of a square fish reef unit according to an embodiment of the present invention before and after adjustment, wherein (a) is an original design interval and (b) is an adjusted interval;

fig. 7 is a comparison diagram of the square fish reef unit reef cluster before and after adjustment, in which (a) is an original design interval and (b) is an adjusted interval;

FIG. 8 is a graph comparing the longitudinal flow velocity distribution of the square fish reef unit according to the embodiment of the invention; wherein (a) is arranged without fish reefs, and (b) is arranged with fish reefs at intervals of 1.25L.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings by way of examples.

In the embodiment, a unit fish reef of a square artificial fish reef to be thrown in the eastern Bay of Bohai sea is taken as a research object, an experiment is carried out in a multifunctional circulating water tank in a key laboratory of the department of hydrosand science education of the environmental academy of university of Beijing, and PIV technology is adopted to simulate hydrodynamic processes of a flow field of the single fish reef under 5 flow rates and 4 arrangement intervals (scaling by taking an original interval L as a reference), so that characteristic values of flow field effects of upward flow, back vortex and the like of the square artificial fish reef under different spatial layouts and hydrodynamic characteristics of flow rate distribution, turbulence intensity characteristic and the like are obtained, on the basis, the flow field effects of the square artificial fish reef under different intervals are comprehensively evaluated by adopting an entropy method, and the optimal selection is carried out after comparative analysis, so that reference is provided for the spatial layout of the artificial fish reef.

The method comprises the following specific steps:

step 1, manufacturing a square fish reef monomer model by using organic glass (according to the principle of similar roughness). The actual dimensions of the square fish reef are 3.5m long, 3.5m wide and 1.5m high, and the dimensions of the single reef model manufactured according to the geometric scale 50:1 are 0.07m long, 0.07m wide and 0.03m high. Three views and a schematic diagram of the square reef monomer reef model are shown in fig. 1.

And 2, establishing square unit fish reefs which are distributed in the water tank bottom plate, wherein 15 square fish reef monomer reef models form a group of square unit fish reefs, the side length of each unit fish reef is 50m, a group of fish reef groups are respectively arranged at four corners and the center of each unit fish reef, and each group of fish reef groups consists of three square fish reef monomer reef models and is arranged in a shape of Chinese character 'pin'. The spacing between the groups of fish reef at the four corners and the central group of fish reefs was about 19.50m as shown in fig. 2.

And 3, selecting three fish reef groups on a diagonal line parallel to the water flow direction as an experimental object. During the experiment, square fish reef unit fish reef comprises 9 monomer reefs, and every group is 3 monomer reefs that are the article font and arrange, and the interval is 1 times the long 70mm of reef between the monomer reef, and the interval of fish reef group is about 390mm, marks as L, reduces and enlarges on this basis, has set up 4 different fish reef inter-group apart from conditions, is L1 for 0.75L for 293mm respectively, and L2 for 1.00L for 390mm, and L3 for 1.25L for 488mm, and L4 for 1.50L for 585mm specifically puts the mode as shown in fig. 3.

Step 4, quantizing the dimensionless of the index;

and (4) arranging the data obtained through the water tank experiment to obtain each evaluation index data under different spatial layouts. Totally selecting 11 evaluation indexes, wherein the upflow indexes comprise 5 indexes including maximum upflow speed (m/s), upflow average speed (m/s), upflow maximum height (mm), upflow maximum length (mm) and upflow total area (mm)²) (ii) a Back vortex index is 3, including maximum height (mm) of back vortex, maximum length (mm) of back vortex and total area (mm) of back vortex²) (ii) a The turbulence intensity indexes are 2, including the average longitudinal turbulence intensity (m/s) and the average vertical turbulence intensity of the whole flow fieldDegree (m/s); the economic cost index is 1, and the cost is per square meter of the unit fish reef (Yuan/m)²). And (4) selecting an extreme value processing method to carry out dimensionless transformation on the evaluation index of the flow field effect of the fish reef in unit.

Step 5, an entropy optimization method;

an entropy method in an objective weighting method is adopted as a weighting method for evaluating the flow field effect of a unit fish reef, and the method comprises the following specific steps:

(1) and constructing a multi-object and multi-index matrix. Let n objects (n) in the evaluation index system₁，n₂，…，n_n) M indices (m)₁，m₂，…，m_m) Let the j-th index (j-1, 2, 3.., m) of the i-th evaluation object (i-1, 2, 3.., n) take the value of X_ijConstructing an original index data matrix X:

(2) dimensionless raw data, eliminating dimension influence, and calculating characteristic proportion or contribution (p) of ith evaluation object under jth index_ij)：

(3) Calculating the entropy (e) of the jth index_j)：

In the formula (I), the compound is shown in the specification,e_j≥0

(4) calculating the difference coefficient (g) of the j index_j)：

g_j＝1-e_j (4)

The difference coefficient is normalized to the value of the difference coefficient,calculating the weight (W) of the jth index_j)：

(5) Calculating the comprehensive score (Y) of each index of the ith evaluation object_i)：

Step 6, evaluating a unit fish reef layout scheme based on hydrodynamics;

and selecting the flow field effect of the unit fish reef at 4 intervals as evaluation objects, wherein each object comprises 5 samples with different flow rates. When the evaluation is carried out based on hydrodynamic characteristics, only the ascending flow, back vortex and turbulent fluctuation intensity indexes related to hydrodynamic force are selected, and economic cost indexes are not included, so that the total number of evaluation indexes is 10;

the average value of the weight of the evaluation index at five design flow rates is used as the final weight of the square fish reef flow field effect evaluation index (Table 1)

TABLE 1 evaluation index weight system for flow field effect of square fish reef unit

According to the determined index weight system, calculation is carried out according to the specific steps of the entropy method, the evaluation score of each interval under five design flow velocities is calculated, in order to facilitate the comparative analysis of the flow field effect evaluation results of different intervals, finally, the arithmetic mean value of the five flow velocities is adopted as the comprehensive score of the flow field effect evaluation of each interval, and the final evaluation result is shown in table 2.

TABLE 2 evaluation score and ranking of flow field effect of square fish reef unit

FIG. 4 shows the final score of the comprehensive evaluation of the flow field effect of the square fish reef units at the four intervals, and it can be seen that the comprehensive score at the four intervals is from large to small, namely 1.25L >1.00L >0.75L >1.50L, and the scores at the two intervals of 1.25L and 1.00L are significantly higher than 0.75L and 1.50L, the sum of the scores of the two previous intervals exceeds 2 times of the sum of the scores of the two latter intervals, but the score of 1.25L is only 0.0039 higher than 1.00L, the two intervals are at the same level, the difference is small, and meanwhile, the score has a maximum value at the interval of 1.15L through refined simulation interpolation. In conclusion, from the experimental point of view, the research suggests that the square fish reef unit fish reef is actually put in, and the distance between the square fish reef unit fish reefs is enlarged by 15% on the basis of the original design distance.

Step 7, evaluating a unit fish reef layout scheme based on hydrodynamics and economic cost;

and selecting the flow field effect of the unit fish reef at 4 intervals as evaluation objects, wherein each object comprises 5 samples with different flow rates. When the unit fish reef is evaluated according to the layout scheme, the economic cost is brought into an evaluation index system in addition to the consideration of hydrodynamic characteristics such as the flow field effect of the artificial fish reef.

The amount of empty square occupied by the square individual fish reef to be thrown in the artificial fish reef construction area in the Liaodong bay is 18.375 empty m³The cost of each empty square is 499.32 yuan/empty m³In the experiment, the single fish reef consists of 9 single reefs, and the total cost is 82575.045 yuan in actual putting. And (3) selecting proper experimental section lengths according to the design of each interval, unifying the widths of the experimental sections into the width of the water tank, calculating the area of the experimental sections, converting the area into an actual area according to a geometric scale of 50:1, and finally dividing the actual total manufacturing cost by the actual area to obtain an economic cost index of the square fish reef artificial fish reef flow field effect evaluation system, namely the manufacturing cost of each square meter of the unit fish reef, wherein the specific result is shown in table 3.

TABLE 3 economic cost evaluation index for square fish reef unit fish reef flow field effect

According to the dimensionless result of the square fish reef evaluation index, the weight of each evaluation index under five design flow rates is obtained according to the calculation steps of the entropy method, and the arithmetic mean value of the weights of the evaluation indexes under the five design flow rates is used as the final weight of the square fish reef flow field effect evaluation index (table 4).

TABLE 4 evaluation index weight system for flow field effect of square fish reef unit

And calculating the evaluation score of each interval under five design flow velocities according to the determined index weight system and the specific steps of the entropy method, taking the arithmetic mean of the five flow velocity scores as the comprehensive score of the flow field effect evaluation of each interval, and finally obtaining the evaluation result shown in the table 5.

TABLE 5 evaluation score and ranking of flow field effect of square fish reef unit fish reef

Fig. 5 shows the final scores of the flow field effect of the square fish reef unit at four intervals in consideration of the economic cost, and the total score of the four intervals is shown from large to small: the combined scores for the flow field effects of 1.25L >1.00L >1.50L >0.75L, 1.25L are 1.048 times, 2.026 times and 2.130 times 1.00L, 1.50L and 0.75L, respectively. Meanwhile, the score has a maximum value at the distance of 1.15L through refined simulation interpolation. In conclusion, from the theoretical and practical perspectives, the research comprehensively considers ecological benefits and economic cost, and proposes that the square fish reef unit is expanded by 15% on the basis of the original design interval when the square fish reef unit is put in practice.

Step 8, optimizing the layout scheme;

according to the evaluation results of the two sets of evaluation systems, ecological benefits and economic costs are comprehensively considered, 25% of the distance between fish reef sets is enlarged on the basis of the original distance when square fish reef units are actually put in the sea of yellow Bohai sea, the distance between the fish reef sets is about 22.43m, and the side length of the square fish reef units is about 56.75m (figure 6). The square fish reef unit reef cluster is composed of five unit reefs, the distance between the five unit reefs is 100m, and the schematic diagram before and after adjustment is shown in fig. 7. As can be seen from table 6, the flow field effect of the adjusted unit fish reefs and unit reef groups is enhanced compared with the original spacing, the number and cost of the individual reefs are reduced by 10%, the area of the affected flow field range is increased by 10% and 5%, and the area of the affected flow field range is increased by 29% and 14% under the condition of the same number and cost of the individual reefs, so that a better living environment can be created for more marine organisms; FIG. 8 shows a comparison graph of longitudinal flow velocity distribution of square fish reef units.

TABLE 6 comparison of square fish reef layout before and after adjustment

It will be appreciated by those of ordinary skill in the art that the examples described herein are intended to assist the reader in understanding the manner in which the invention is practiced, and it is to be understood that the scope of the invention is not limited to such specifically recited statements and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.