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The resource utilization of building waste in urban sustainable environment governance is significant, in view of the status of construction waste recycling; this article built a reverse logistics planning model in urban building waste from the perspective of a closed supply chain by means of a hybrid nonlinear programming model. Combining the simulated annealing algorithm with memory function and the genetic algorithm with global convergence performance, a new genetic simulated annealing algorithm is presented to optimize the model. The empirical study was then made for the system to verify the feasibility of the model. The proposed new planning method and its detailed steps can provide a meaningful reference value for resource utilization of building waste in urban sustainable environment governance.

The variable spraying technology includes two categories: premixed drugs and online mixed drugs. The operators need to be in contact with pesticides in the premixed operation, which is harmful to the operators. Meanwhile it has the disadvantages of large amount of pesticides and environmental pollution. In order to solve this problem, an injection-type online mixed drug spray control system for variable spraying and width control was designed. The required water flow and liquid flow can be set according to user settings or prescription drawings to change the spray concentration in real time. It can mix pesticides as needed and accurately spray pesticides. The injection type online drug mixing control system uses the liquid medicine injection method. This system injects the liquid medicine into the water solvent pipeline for mixing when the water flow rate is stable. a model for the mixing ratio of water solvent and liquid flow was established. Using PID control algorithm to control electric regulating valve to adjust water solvent flow. Real-time detection technology of high-precision drug liquid flow and micro-control method of drug pump are adopted to realize detection and control of drug injection volume. The mixture ratio range measurement showed that the mixing ratio was 10:1-270:1. The spray volume consistency test showed that the spray volume of the four nozzles was generally consistent. The mixed concentration detection is performed under different mixing ratios of the system, and the spatial variation coefficient is less than 5%. It shows that the mixed drug spray control system has better uniformity and stability.

Tornado is one of the most hazardous external natural events which should be taken into account in the siting, design and safety evaluation of nuclear power plants. The tornado hazard has been assessed for a nuclear power plant located in the Southeast China in this paper. Using the original Fujita scale and grading by a number of experts, intensities of the tornado segments have been determined. The design-basis tornado wind speed, parameters and missiles generated have been evaluated following the methodology listed in the hChinese Nuclear Safety Guide HAD101/10. The results show that the overall cumulative frequency and intensity of tornadoes in the site area is not in a logarithm-linear relationship. The expected annual tornado occurrence frequencies of various F scales have been estimated by fitting higher intensity samples. The resulting wind speed corresponding to an exceedance frequency of 10-7 per year seems to be sensitive to the fitting samples. Considering the uncertainties, the intensity and frequency of tornadoes in the survey area, the ultimate design-basis tornado wind speed is taken to be 70.4 m/s, which is the lower limit wind speed of F3 scale. Moreover current problems in tornado hazard assessment in China are discussed.

AgCdO electric contact material is widely used in low voltage industries, such as contactors, electric relays, switches and miniature circuit breaker, therefore it is called “the universal material”. This material is mainly prepared by internal oxidization and it has good machining properties and ani-welding resistance. In this paper, AgCdO(12) electrical contact materials with different oxide particle sizes (0.8, 1.2, 1μm) will be prepared. Besides, the microstructure, mechanical properties and electrical properties of different AgCdO(12) materials will be investigated. It is expected to provide reference for research and design of electrical contact materials.

The variable spraying technology includes premixed drugs and online mixed drugs. The operators need to be in contact with pesticides in the premixed operation.It is harmful to the operators.Meanwhile it has the disadvantages of large amount of pesticides and environmental pollution. In order to solve this problem, an injection-type online mixed drug spray control system for variable spraying and width control was designed.In this paper, a novel injection-type online mixing pesticide control system is designed to solve this problem for variable spray and width control. The mixing ratio of water solvent flow and the pesticide flow is adjusted in real-time spraying by using a sprayer equipped with the proposed online mixing pesticide control system according to the specific prescription map. The concentration of pesticide at the nozzle is controllable consequently. The real-time dynamic response test and the steady state error test were carried out during the pesticide injection. Results show that the steady state error of the proposed system with using DMC strategy is no more than 5%. The uniformity of the mixed pesticide was tested under different mixing ratios of the system, and the calculated spatial variation coefficient is less than 5%. It shows that the injection-type online mixing pesticide control system has better mixing uniformity.

It is necessary to establish the longitudinal dynamic model of the tractor for the cruise control system to design a fixed speed control algorithm according to the characteristics of the model and the external disturbance characteristics. Aiming at the complexity of the longitudinal power transmission system of the tractor, this paper uses the modular mechanism modeling and the experimental data modeling to establish the longitudinal dynamic model of the tractor. Due to the nonlinearity of the longitudinal dynamics system, the inverse model method is used to linearize the model, which is convenient for the design of control structure and control algorithm of the standard cruise control system. The longitudinal dynamics model is simulated on Simulink, and the model is verified by real vehicle under driving condition. Comparing the simulation data with the experimental data, the results show that the model can accurately reflect the longitudinal dynamics characteristics of tractor, and can meet the requirements for the design of cruise control system.