Efficiency Evaluation and Performance Governance of Infrastructure Construction Based on DEA and Improved Neural Networks

Infrastructure construction is the carrier of regional economic development, and the rational use of urban construction land is an important basis that largely depends on the efficiency of urban infrastructure construction. However, due to the lack of effective integration between urban evaluation and management in infrastructure, the infrastructure performance evaluation system is not yet mature enough. Therefore, this article conducts efficiency evaluation and performance governance of infrastructure construction based on DEA and improved neural networks. Firstly, based on a comprehensive analysis of performance evaluation, the advantages and disadvantages of infrastructure construction were explored. Secondly, in the study of using DEA and improved neural networks to evaluate the efficiency of infrastructure construction, a performance evaluation index system for urban infrastructure construction was constructed from four aspects: input, output, effect, and activity. A systematic performance evaluation of urban infrastructure was conducted, and optimization suggestions were proposed accordingly.


Introduction
Rapid urbanization has led to deterioration of the ecological environment, degradation of ecological functions, and fragmentation of ecological space.Based on traditional grey infrastructure assessment, it is no longer able to meet the current needs of urban development, which is not conducive to the sustainable development of cities [1][2].Urban green infrastructure corresponds to gravy infrastructure, which can effectively solve the above problems and contribute to the sustainable development of cities.There is still a lack of clear evaluation and construction standards for the construction of urban green infrastructure.Due to the lack of evaluation standards, the construction standards for green infrastructure in some cities are not unified, and the construction level is uneven [3][4][5].Especially, the investment in funds is not proportional to the effectiveness, which can easily lead to waste of funds and urban land resources.Therefore, it is necessary to conduct relevant performance evaluations on the construction of urban green infrastructure, and promote the standardized construction and development of urban green infrastructure [6].Research on the concept of green infrastructure.At present, the academic community has conducted a lot of research on the concept of green infrastructure assessment, but it has not yet been unified [7][8][9].Webster, the Conservation Foundation of the United States, and the Forest Service of the Department of Agriculture each proposed the concept of green infrastructure.The Jane Hutton Federation believes that green infrastructure is a multifunctional green space network [10][11].Ahren from the University of Massachusetts believes that the resilience assessment of green infrastructure should be achieved through five strategies: diversity, multi-scale networks, multifunctional, modular, and adaptive design.These methods provide scientific theoretical guidance for the assessment and construction of green infrastructure [12][13][14].In addition, scholars used the super efficiency DEA-CCR model and the double difference method to measure the innovation performance of innovative cities, and analysed the influencing factors of urban innovation performance [15].With the intensification of the contradiction between human and land, the value concept and evaluation methods of green infrastructure have gradually been accepted by people.However, how to better integrate it into urban construction and management work is still an urgent problem to be explored and studied [16][17].The construction of future urban infrastructure will become an important content of urban evaluation.This article analyses and studies the current situation, problems, and paths of infrastructure evaluation, and takes a certain urban area as an example for analysis.This article attempts to find a suitable path for evaluating the performance of green infrastructure, and proposes relevant countermeasures and suggestions.At the same time, it can provide experience and reference for the construction of green infrastructure in other similar cities

Evaluation Method Based On DEA and Improved Neural Network
The economic efficiency of urban construction land utilization is determined by input consumption and output efficiency, with the characteristics of multiple inputs and outputs.The DEA method is precisely used to evaluate the performance or efficiency of complex systems with multiple inputs and outputs [18].This article reflects the relative efficiency of each decision-making unit through evaluation, as well as the degree of extensive or intensive use of construction land.The evaluation results in decision-making units being divided into DEA effective and non DEA effective, and the decision-making units can be ranked based on the value of efficiency.
Through projection analysis of software, relaxation variables can also be obtained, and the direction and magnitude of improvement can be pointed out for more extensive decision-making units. 2 There is no need to explicitly express the relationship between input and output variables, but to use the collected effective sample data and use linear programming principles to determine the production frontier of the system, thereby obtaining relevant information on the relative efficiency and improvement of each decision-making unit [19].
At the same time, there is no need to judge weights and estimate parameter coefficients to avoid human errors affecting the results, which has strong objectivity.
Finally, the normalized matrix is obtained: ) ( (7) This is a fractional programming problem that obtains the linear programming problem of (P) through the charges cooper transformation [20].

Performance Evaluation of Infrastructure Construction
The basic principles to be followed when constructing a performance indicator system for green infrastructure construction are: 1) The principle of scientificity, guided by the concept of ecological civilization construction, constructs a relevant scientific indicator system.
2) The principle of comprehensiveness is based on the perspectives of input, output, activities, and effects.Starting from the ecological system of mountains, rivers, forests, fields, lakes, and grasslands, the phase is determined based on the definition of urban green infrastructure.
3) The principle of representativeness is to select indicators that accurately reflect the characteristics of urban green infrastructure construction as much as possible.Drawing on relevant scholars' research on performance evaluation [21], the infrastructure construction performance evaluation indicator system is divided into target layer, criterion layer, and indicator layer.A total of 14 indicators are selected based on four aspects: input, output, effectiveness, and activity.In terms of investment, there are three specific indicators: expenditure on park green space construction funds in financial funds, land area for green infrastructure projects, and total investment in green infrastructure projects.The output includes three specific indicators: urban green space rate, urban greenway length, and green infrastructure area [22].The effectiveness includes four specific indicators: the proportion of days with good air quality throughout the year, PM2.5 concentrations, urban sewage treatment rate, and harmless treatment rate of urban household waste.The activity includes four specific indicators: spatial control, standard development, public participation, and evaluation feedback.Data collection: Relevant data on urban construction and environmental protection in a certain district from 2013 to 2019.The expenditure on park green space construction funds, land area for green infrastructure projects, and total investment in green infrastructure projects in the financial budget come from data from the development and reform departments and statistical departments.The data on urban green space rate, urban greenway length, and green infrastructure area come from data from departments such as construction and environmental protection.Space control, standard formulation, public participation, and evaluation feedback are evaluated by collecting relevant information from natural resources and construction departments or conducting interviews.After systematic organization, four qualitative indicators of the project are scored through expert consultation, and each item is scored on a 10-point scale.
By using methods such as mean square deviation and range standardization, the input performance, output performance, effectiveness performance, activity performance, and comprehensive performance of green infrastructure in a certain area in different years were calculated, and the final calculation results are shown in Table 1.The comprehensive performance level of urban green infrastructure in this area shows an "inverted Vshaped" development trend.Figure 1 shows the comprehensive performance results of urban green infrastructure from 2013 to 2019.The performance evaluation calculation results show that from 2013 to 2019, the comprehensive performance level of urban green infrastructure showed a trend of first increasing and then decreasing, similar to an "inverted V-shaped" change.From 2013 to 2018, with the acceleration of construction, continuous improvement of planning and design, and the gradual establishment of a low-carbon oriented development model for new areas, the comprehensive performance level of urban green infrastructure showed an upward trend, and the development index increased by 230 times from 0.004 in 2013 to 0.9275 in 2018.However, with the continuous improvement of public infrastructure, the peak period of green infrastructure construction has gradually disappeared, and in 2019, due to the impact of the macroeconomic environment, the comprehensive performance level of urban green infrastructure has shown a downward trend.In the future, urban green infrastructure will gradually shift from large-scale urban green infrastructure construction to small-scale urban green infrastructure construction, gradually increasing the coverage of urban green infrastructure and improving the accessibility of urban residents to green infrastructure.Figure 2 shows the performance of each sub item of urban green infrastructure from 2013 to 2019.There is a significant difference in the performance development level of various sub items of urban green infrastructure in this urban area.As shown in Figure 2, from 2013 to 2019, the development trends of input performance, output performance, effectiveness performance, and activity performance of urban green infrastructure varied, showing certain differences.From the overall trend of changes in various sub indicators, there has been a sustained growth trend from 2013 to 2018, which is closely related to the accelerated construction of green infrastructure, major urban parks, wetland projects, and urban green space construction.In 2019, as the construction process of large-scale urban green infrastructure projects slowed down, the investment in funds decreased, and the output performance also decreased.Due to the significant results of urban green infrastructure construction in the early stage, the effectiveness and activity performance showed a stable growth trend due to the inertia of growth.

Conclusion
This article analyses the connotation of ecological civilization and the theory of green infrastructure, and draws on current cases related to the evaluation and construction of green infrastructure to analyse the current development status and problems.It scientifically proposes the overall performance evaluation and optimization construction ideas of green infrastructure.The comprehensive performance level of urban green infrastructure shows an inverted "V" shaped development trend, and the comprehensive performance level of urban green infrastructure shows a trend of first increasing and then decreasing, similar to an "inverted V" shaped change.In addition, although this article has made some discussions on this, further detailed analysis is needed in terms of the basic theory and specific evaluation framework construction of ecological civilization and green infrastructure.

Figure 1 .
Figure 1.The comprehensive performance results of urban green infrastructure from 2013 to 2019

Figure 2 :
Figure 2: Performance of Urban Green Infrastructure Components from 2013 to 2019

Table 1
Calculation Results of Green Infrastructure Assessment in a District from 2013 to 2019