2016 volumne 37卷 Issue 02
2016 Issue02
Xiao Junming, Zhou Qian, Qu Boyang, Wei Xuehui
Abstract: The energy supply of power system is very important to modern society, and the scientific and effective solution to the problem of environmental economic dispatch of power system is the guarantee of energy supply. The multi-objective evolutionary algorithm has unique advantages in solving the problem of environmental economic dispatch of power system. This paper presses In chronological order, the multi-objective evolutionary algorithm is first introduced, and then the application of the multi-objective evolutionary algorithm in the power system environmental economic dispatching problem is discussed. The direction of development is prospected.
Zhang Duanjin; Liu Xue; Fan Xin
Abstract: The filtering problem of networked control system with time-varying delay is studied, and an H∞ filter is designed to keep the time-varying delay system stable. Based on the Delta operator, the design method of continuous domain can be directly applied to the design of discrete domain. Firstly, the network control system with time-varying delay is modeled, and the filter error system is constructed. Then, the useful time delay item that is often neglected is retained by using the Lyapunov-Krasovskii functional method, and the H∞ filter of the network control system The performance analysis of the error system is carried out, and then a sufficient condition for making the filtering error system asymptotically stable is given through a set of linear matrix inequalities, and the design method and derivative expression of the H∞ filter are obtained. Finally, the method is shown by a numerical example. validity.
Zhang Hengyan; Senior Zhongwen, Li Wenlong, Song Weiwei, Huang Ling
Abstract: The tracking controller design problem of observer-based uncertain TS fuzzy system is studied. Using TS fuzzy method to model the nonlinear controlled object with uncertainty, for a given reference model representing the expected state of the system, in the system state Under the condition that the unmeasurable and uncertain items meet the bounded conditions, the parallel distributed compensation method (parallel distributed compensation) is used to design the fuzzy controller based on the observer to ensure the tracking of the reference model state and suppress the influence of disturbance on the tracking error. The Lyapunov stability theorem and Schull’s complement lemma transform the design problem of the tracking controller into a feasible solution problem of a set of linear matrix inequalities. This method is simple and practical, and the simulation examples have verified the effectiveness and correctness.
Wang Jiechang, Qun Kang, Peng Jinzhu
Abstract: Use the fireworks algorithm (fireworks algorithm, FWA) to optimize the extreme learning machine (extreme learning machine, ELM). First, the fireworks algorithm undergoes multiple iterations to determine M optimal fireworks, and the RMSE of the extreme learning machine test sample is used as the fireworks algorithm The fitness function of each iteration achieves the effect of optimizing the input weight matrix and hidden layer deviation of the extreme learning machine. Finally, the output matrix is ​​obtained according to the generalized inverse. The test results of the one-dimensional sinC function show that the fireworks algorithm optimizes the limit The learning machine can achieve higher accuracy with fewer nodes in the hidden layer, which is 29.58% lower than the test error of the extreme learning machine. On the basis of the above, the fitting experiment of the Gaussian normal distribution function was done to verify that The fireworks algorithm optimizes the extreme learning machine to have better fitting performance than the extreme learning machine.
Xu Tian, Chen Xiaoqiang
Abstract: The distributed photovoltaic power generation system is affected by the installation direction and angle, and is in different light conditions at all times. The power generation system using conventional centralized and string electrical structures is prone to hot spot problems, and some batteries in low light conditions Affect the performance of the whole system, so that the maximum power point tracking efficiency is greatly reduced. In the analysis of the actual roof lighting conditions, a parallel multi-branch distributed photovoltaic power generation system is proposed. Aiming at the electrical characteristics of the parallel multi-branch structure, An active clamp converter is selected for analysis, and an experimental model is built in the MATLAB environment for simulation analysis. The simulation results show that the system can effectively improve the anti-shading performance of the system.
Jiang Zheng, Zhou Yong, Chen Xuemei, Lu Nawei
Abstract: In order to improve the accuracy and speed of power quality monitoring, a monitoring device with FPGA as the core of processing and control is designed. The hardware part mainly includes signal acquisition unit, communication unit, power supply unit, etc. In terms of software, the embedded NIOS Ⅱ is customized on the FPGA. The core optimizes the data parallel processing process, builds a phase-locked frequency multiplication module and an FFT harmonic analysis algorithm module in the FPGA chip, and realizes synchronous sampling and analysis of power quality data. The test shows that the device has fast response speed and high measurement accuracy. High performance and good real-time performance, in line with national standards on power quality monitoring.
Yan Xinfang; Yan Jingjing; Feng Yan
Abstract: In order to balance the energy consumption of nodes in the network, a hierarchical clustering algorithm—GPHCA is proposed. This algorithm adopts the dual cluster head mode, and uses the particle swarm optimization algorithm to search for two nodes with large energy and small average distance to cluster members as the main cluster head. and the sub-cluster head to balance the burden of the cluster head on the two nodes; in the selection of the gateway, the energy and the total distance of the forwarding path are considered at the same time, so that the final selected gateway can be balanced in terms of energy and delay. The simulation results show that, The GPHCA algorithm can effectively prolong the life cycle of the network.
Chen Tiejun, Cai Jinshou, Guo Li
Abstract: Aiming at the defect that wavelet analysis cannot make full use of the unique geometric features of the data itself when dealing with multi-dimensional graphics, the second generation of curvelet transform (SGCT) method is used to process face images, and the image with the largest standard deviation is selected. Scale layer coefficients are used to complete the feature extraction of face images, and combined with data dimensionality reduction based on bidirectional two-dimensional principal component analysis (B2DPCA), a hybrid voting mechanism-based extreme learning machine (voting Extreme learning machine, VELM) face recognition algorithm. By comparing with the classification results of other algorithms, it is proved that the algorithm has a higher recognition accuracy.
Zhao Hongliang1,Wu Di1,Weng Kangrong1,Hu Guanqi2
Abstract: Coarse and unevenly distributed second phases exist in cast-rolled pure aluminum-based negative electrode foil blanks, and homogenization annealing has an important influence on the size and distribution of second phases in the blank. The effects of annealing temperature and holding time on pure aluminum The effect of the size and distribution of the second phase in the cold-rolled blank of negative electrode foil. The results show that: when the holding time is 10 h, with the increase of annealing temperature, the curved band-shaped FeAl eutectic phase gradually dissolves and spheroidizes, and the strip-like β ( FeAlSi) phase decomposes into short rods, and when the temperature rises to 550 °C, the needle-like phase FeAl3 begins to precipitate; when the annealing temperature is 520 °C, with the extension of annealing time, the proportion of the coarse second phase decreases continuously, and then tends to The cold-rolled cast-rolled pure aluminum-based negative electrode foil blank with a cold-rolled deformation rate of 38.5% can obtain a relatively uniform structure after being annealed at 520°C for 10 h.
Lu Guangxi, Zhou Chongguan, Shao Kang, Xin Xiaoyang
Abstract: The influence of different intermediate annealing processes on the bending and forming properties of AA5052-H32 finished plate produced by high-throughput continuous casting and rolling technology was studied by means of microstructure analysis and performance detection. The results showed that optimizing the intermediate annealing process can effectively improve the finished product. The formability of the plate, after the intermediate annealing at 480℃×8h, the bending performance of the finished plate is the best, and the formability is improved; The splitting effect of the matrix is ​​reduced and the formability is improved.
Zhan Zili, Li Yafeng, Chen Xiangyu, Chen Kecheng
Abstract: 0.02Pb(Sb0.5Nb0.5)O3-0.98Pb1-2xBaxSrx(Zr0.53Ti0.47)O3 piezoelectric ceramics (where x=0.02,0.03,0.04,0.05) were prepared by traditional solid-state sintering method. The different The effect of Ba, Sr composite doping amount and sintering temperature on the structure and electrical properties of ceramics. The results show that when x = 0.04 and the sintering temperature is 1260 ℃, the performance of piezoelectric ceramics is the best, where d33 = 615 pC/N, ε33/ε0=2224, tanδ=2.11%; then install the ceramic chip of this formula into the sensor, test its charge sensitivity, maximum lateral sensitivity ratio and maximum linearity error, the charge sensitivity is 2.72 pC/(m s-2) , the maximum lateral sensitivity ratio is less than 5%, and the maximum linear error is 2.97%, which meets the requirements for the use of general vibration test type sensors.
Feng Qiuxia1,Yu Peng2,Wang Jing2,Li Xiaoqian2
Abstract: In order to improve the gas-sensing response of ZnO to acetone, yttrium-doped ZnO nanofibers were prepared by electrospinning using a precursor solution made of PVP/Zn(NO3) 6H2O/Y(NO3)3 6H2O, etc. The prepared pure ZnO and doped ZnO samples were characterized by XRD, SEM and other characterization methods. The prepared pure ZnO and yttrium-doped ZnO nanofibers were made into resistive gas sensors. The gas sensor test results showed that Y Doping effectively improves the sensitivity of ZnO nanofibers to acetone gas. At 440 °C, it has a good response to 1×10-6-200×10-6 (volume fraction) acetone, and the response time is 14-40 s. The recovery time is 20-55 s, the response value to 100×10-6 acetone is about 70 (S=Ra/Rg), and it has good selectivity to ethanol, ammonia, methanol, formaldehyde, toluene and benzene. At the same time, the sensitivity mechanism of the material to acetone was analyzed.
Liu Xinlu1,Wang Wen1,Pan Yong2,Shao Shengyu2,Munning2
Abstract: Aiming at the suddenness and uncertainty of the increasingly prominent public safety and production safety issues, a toxic gas detection system combining surface acoustic wave sensor array and Internet of Things technology is proposed, and the design of the toxic gas detection system is given. The feasibility of the system is verified from two aspects of Internet of Things technology and surface acoustic wave technology. The system uses ZigBee communication technology and GPS positioning means, and uses 4-channel surface acoustic wave sensor arrays coated with different sensitive films and corresponding The data processing algorithm realizes the detection and alarm of toxic gases such as H2S and SO2, and establishes a mature sensor network for easy positioning. The system has achieved the expected design goal through experimental verification.
Zhuang Huimin; Yang Ping; He Wenlong
Abstract: With the widespread application of artificial freezing method in subway construction, controlling post-construction thaw settlement has become a difficult problem to be solved for soft ground freezing. Taking the typical soft soil layer of Suzhou Metro as the research object, through laboratory experiments, it is concluded that under different water replenishment conditions The open thaw settlement coefficient of undisturbed soil is greater than that of closed thaw settlement coefficient; under unloading and pressure before melting, the thaw settlement coefficient decreases exponentially with the increase of upper load; The thaw-sedimentation coefficient becomes larger after soil remodeling, and the difference increases with the increase of the soil sensitivity; for unsaturated clay and muddy silty clay, there is a critical relationship between the thaw-sedimentation coefficient and dry density under open freeze-thaw conditions. The dry density corresponds to the minimum thaw settlement coefficient of the soil.
Li Haitao1,Su Jingwen1,Wei Dongdong2,Zhang Qisheng1,Chen Guo1
Abstract: Axial compression tests in three directions were carried out on large-scale recombined bamboo specimens, and the relationship between the failure mechanism and the measured parameters was discussed. The failure process in all directions goes through the elastic stage, elastic-plastic stage, plastic stage and failure stage; however, the failure stages are different. The final failure forms of the specimens under compression in all directions are relatively similar, and the main cracks along the diagonal direction appear in both. The measured compressive strength, elastic modulus, and Poisson’s ratio along the grain direction are the largest, and the dispersion is large; the compressive strength in the grain direction I is slightly greater than that in the grain direction II, but the elastic modulus and Poisson’s ratio are both It is smaller than the value corresponding to the transverse direction II. Based on the test results, the corresponding relationship between the compressive strength, elastic modulus and Poisson’s ratio in each direction is given.
Wei Xinli, Li Minghui, Ma Xinling, Hou Zhonglan, Meng Xiangrui, Yan Yanwei
Abstract: The experimental research on the organic Rankine cycle low-grade thermal power generation system with self-designed centripetal turbine as the expander shows that the (exergy) loss of the evaporator is the largest, followed by the condenser and the centripetal turbine. When the inlet pressure of the turbine is 0.397 MPa and the inlet temperature is 100.58°C, the evaporator (exergy) loss is 3.81 kW, accounting for 50.64% of the total (exergy) loss, and the condenser and turbine (exergy) losses are 2.88 and 0.82 kW, accounting for 38.25% and 10.89% respectively. On the basis of the experiment, using Aspen7.3 to simulate the impact of adding regenerator on system performance, the results show that: when the heat source temperature and evaporation temperature are constant, the thermal power of the ORC system with regenerator Performance is better than basic ORC system.
Li Yu
Abstract: Taking the construction frame of a long-span continuous girder bridge as the engineering background, the original drawings and load schemes were checked by using finite element software. , horizontal support beams, and steel pipe columns were designed, and the strength and stability of each component of the designed construction frame were checked with finite element software. The results showed that: under the premise of ensuring cost economy, the designed bridge construction frame The bearing capacity has been greatly improved to meet the requirements of bridge construction.
Qin Dongchen, Du Peng
Abstract: Large-scale box parts are widely used in mechanical equipment. They are mainly designed based on traditional experience, and the structure is bulky. Using the SIMP variable density method, with the goal of minimizing compliance and volume as constraints, the topology optimization of large-scale box parts is established. Mathematical model. Using density filtering and gray filtering to solve the problem of numerical instability in the process of topology optimization. Using the OC criterion to solve the topology structure under different load conditions, and obtaining the new structure of large box parts through structural synthesis, and using finite The feasibility and practicability of the structure are verified by the meta-method, which provides a useful guidance for the structural design of large box parts.
Zheng Yuanxun, Li Tong
Abstract: In order to eliminate the conflict points of roundabouts, reduce the traffic flow in the weaving area and the driving distance of left-turn and U-turn vehicles, it is proposed on the basis of the existing satellite island roundabouts: change a single roundabout to an inner and outer double roundabout; change the satellite The diversion method of the island roundabout. Based on this, the conceptual design of the satellite island embedded double roundabout is carried out. The satellite-shaped intersection can not only retain the advantages brought by the satellite-island roundabout, but also eliminate the conflict points when vehicles drive from the satellite island to the center island. Vehicles drive clockwise around the central island (contrary to conventional driving habits) and some road sections drive in the opposite direction, so as to improve the traffic capacity of the road section.
Sun Xiaohong, Zhang Lin, Li Wenyang, Guo Minqiang
Abstract: A cadmium telluride thin film solar cell with a double filling ratio rectangular grating structure was designed. The cadmium telluride thin film solar cell with a rectangular grating and a double filling ratio rectangular grating in the incident wavelength range of 250-1000nm was analyzed using the finite-difference time domain method. The absorption efficiency is analyzed. The experimental results show that: compared with the flat absorbing layer, the absorption efficiency of the single filling ratio and double filling ratio rectangular grating structure is greatly improved; the absorption rate of the double filling ratio rectangular grating in the entire visible range is overall It is improved, and its average absorption rate of visible light is at least 10% higher than that of the flat plate type. It can be seen that by optimizing the structure of the solar cell absorption layer, the random reflection of photons in the grating increases the action time and distance of light in the absorption layer, improving The photoelectric conversion efficiency of thin film solar cells.
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