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Enhanced ozonation of dichloroacetic acid in aqueous solution using nanometer ZnO powders

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Journal of Environmental Sciences 2010年第10期22卷 1527-1533页

作者： Xu Zhai Zhonglin chen Shuqing Zhao He Wang Lei yang State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental Engineering Harbin Institute of Technology Harbin 150090 China. Forestry Institute Northeast Forestry University Harbin 150090 China

Nanometer zinc oxide （ZnO） powders were used as a catalyst to enhance the ozonation for the degradation of dichloroacetic acid （DCAA） in aqueous solution. The batch experiments were carded out to investigate the effects of key factors such as catalyst dosage, ozone dosage, solution pH and tert-butyl alcohol （t-BuOH） on the degradation efficiency of DCAA. Density functional theory （DFT） was adopted to explore the mechanism of generating hydroxyl radical （＇OH） on the ZnO surface. The results showed that adsorption and ozonation processes were not effective for DCAA removal, and the addition of ZnO catalyst improved the degradation efficiency of DCAA during ozonation, which caused an increase of 22.8% for DCAA decomposition compared to the case of ozonation alone after 25 min. Under the same experimental conditions, the DCAA decomposition was enhanced by increasing catalyst dosage from 100 to 500 mg/L and ozone dosage from 0.83 to 3.2 mg/L. The catalytic ozonation process is more pronounced than the ozonation process alone at pH 3.93, 6.88, and 10. With increasing the concentration of t-BuOH from 10 to 200 rag/L, the degradation of DCAA was significantly inhibited in the process of catalytic ozonation, indicating that ZnO catalytic ozonation followed ＂OH reaction mechanism. Based on the experimental results and DFT analysis, it is deduced that the generation of ＂OH on the ZnO surface is ascribed to the adsorption of molecule ozone followed by the interaction of adsorbed ozone with active sites of the catalyst surface. It is also concluded that ZnO may be an effective catalyst for DCAA removal, which could promote the formation of .OH derived from the catalytic decomposition of ozone.

关键词： dichloroacetic acid catalytic ozonation density functional theory hydroxyl radical

Wave propagation of laminated composite plates via GPU-based wavelet finite element method

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Science China(Technological Sciences) 2017年第6期60卷 832-843页

作者： ZUO Hao yang ZhiBo SUN Yu XU CaiBin chen XueFeng School of Mechanical Engineering Xi 'an Jiaotong University Xi 'an 710049 China State Key Laboratory for Manufacturing Systems Engineering Xi 'an 710049 China

This paper presents a novel parallel implementation technology for wave-based structural health monitoring (SHM) in laminated composite plates. The wavelet-based B-spline wavelet on he interval (BSWI) element is constructed according to Hamilton’s principle, and the element by element algorithm is parallelly executed on graphics processing unit (GPU) using compute unified device architecture (CUDA) to get the responses in full wave field accurately. By means of the Fourier spectral analysis method,the Mindlin plate theory is selected for wave modeling of laminated composite plates while the Kirchhoff plate theory predicts unreasonably phase and group velocities. Numerical examples involving wave propagation in laminated composite plates without and with crack are performed and discussed in detail. The parallel implementation on GPU is accelerated 146 times comparing with the same wave motion problem executed on central processing unit (CPU). The validity and accuracy of the proposed parallel implementation are also demonstrated by comparing with conventional finite element method (FEM) and the computation time has been reduced from hours to minutes. The damage size and location have been successfully determined according to wave propagation results based on delay-and-sum (DAS). The results show that the proposed parallel implementation of wavelet finite element method (WFEM) is very appropriate and efficient for wave-based SHM in laminated composite plates.

关键词： wave propagation laminated composite plates wavelet finite element method parallel implementation structural health monitoring

Mn-Ce-Nb-O_x/P84 catalytic filters prepared by a novel method for simultaneous removal of particulates and NO

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Journal of Rare Earths 2019年第3期37卷 273-281页

作者： Bo yang Qiong Huang Mindong chen Yuesong Shen Shemin Zhu Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET) Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control School of Environmental Science and Engineering Nanjing University of Information Science & Technology Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM) College of Materials Science and Engineering Nanjing Tech University

The Mn-Ce-Nb-O_x/P84 catalytic filter for removal of particulates and NO simultaneous was prepared by a novel method(foam coating method). The process parameters including the concentrations of PTFE emulsion, particle size of catalyst and calcination temperature for preparation of catalytic filters were analyzed. In addition, the physical properties and performance for removal of NO(NH_3-SCR) and particulates of Mn-Ce-Nb-O_x/P84 catalytic filter prepared under the optimized parameters, were also systematic studied. Results show that the process parameters had significant influences on stability and performance of catalytic filter, The Mn-Ce-Nb-O_x/P84 catalytic filter prepared by foam coating method under the optimized parameters, has satisfactory physical properties and catalytic performance for removal of NO and particulates at 140-220 ℃. The NO removal efficiency of catalytic filter can reach95.3% at 200 ℃ as the catalyst loading amount is 450 g/m^2, Moreover,the dust removal efficiency of MnGe-Nb-O_x/P84 catalytic filter reaches as high as 99.98%, and the PM2.5 removal efficiency also reaches99.98%. The anti-sulfur performance of Mn-Ce-Nb-O_x catalytic filter is also attractive, after injecting150 ppm SO_2, the NO removal efficiency still retains up to 85%. It is indicated that the foam coating method can not only make a bond of high strength between catalyst and filter, but also make the catalytic filter possessing an excellent and stable performance for removal of NO and particulates.

关键词： Foam coating method Simultaneous removal Mn-Ce-Nb-O_x/P84 catalytic filters NO Particulates Preparation method

Self-Compensating Displacement Sensor Based on Hydramatic Structured Transducer and Fiber Bragg Grating

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Photonic Sensors 2015年第4期5卷 351-356页

作者： Shimeng chen Yun LIU Xiuxin LIU yang ZHANG Wei PENG College of Physics and Optoelectronics Engineering Dalian University of Technology Dalian 116024 China

An optical fiber displacement sensor with a large measuring range for simultaneous displacement and temperature measurement is presented in this paper. We developed a specific transducer based on the piston and hydraumatic structure to realize a large displacement measurement, which combined the large measuring range and high precision into a single sensor system. The spectrum showed two reflection peaks used to compensate for cross-sensitivity in the displacement detection. This displacement sensor can linearly work in a large measuring displacement range greater than 45 mm with a high sensitivity of 0.036nm/mm. The sensor we reported can be developed for real-time displacement monitoring in many industrial environments such as the mechanical shape or liquid level monitoring.

关键词： Hydraumatic structured transducer large measuring range temperature compensating optical fibersensor displacement

A Fast Insertion Tabu Search with Conflict-Avoidance Heuristic for the Multisatellite Multimode Crosslink Scheduling Problem

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Tsinghua Science and Technology 2024年第3期29卷 843-862页

作者： Weiyi yang Lei He Xiaolu Liu Weican Meng Yingwu chen College of Systems Engineering National University of Defense TechnologyChangsha 410000China Beijing Institude of Tranking and Telecommunication Technology Beijing 100000China

An agile earth-observing satellite equipped with multimode cameras capable of transmitting observation data to other satellites is developed to rapidly respond to requests with multiple observation *** gives rise to the Multisatellite Multimode Crosslink Scheduling(MMCS)problem,which involves allocating observation requests to agile satellites,selecting appropriate timing and observation modes for the requests,and transmitting the data to the ground station via the satellite communication ***,a mixed integer programming model is introduced to include all complex time and operation *** solve the MMCS problem,a two-stage heuristic method,called Fast insertion Tabu Search with Conflict-avoidance(FTS-C)heuristic,is *** the first stage,a conflict-avoidance insertion algorithm is designed to generate a high-quality initial solution by considering the requests transmission and ***,the tabu search-based second stage optimizes the initial ***,an extensive empirical study based on a real-world situation demonstrates that FTS-C can generate a solution with higher quality in less time than other state-of-the-art algorithms and the CPLEX solver.

关键词： earth observation satellites scheduling tabu search heuristic data transmission and download mixedinteger programming model

Performance analysis of a solar-aided power generation(SAPG) plant using specific consumption theory

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Science China(Technological Sciences) 2016年第2期59卷 322-329页

作者： HOU HongJuan WANG MengJiao yang YongPing chen Si HU Eric National Thermal Power Engineering and Technology Research Center North China Electric Power University University of Kentucky Power and Energy Institute of Kentucky School of Mechanical Engineering University of Adelaide

In contrast to a traditional coal-fired power generation plant where steam extracted from a turbine is used to preheat the feedwater in all preheating stages, a solar-aided power generation(SAPG) plant uses solar heat to replace a part or all of the extracted steam in one or more preheating stages. The performance of an SAPG plant with different replacements is investigated in this study by using specific consumption theory(SCT). Fuel-specific and cost-specific consumption models for SAPG plants are built based on the SCT. A typical 330 MW coal-fired power plant is used as the study case. The performance of the SAPG plant in terms of specific consumption, with steam obtained from the first through the eighth(except for the fourth) stages of extraction replaced by solar heat, is compared with that of the reference coal-fired power plant. The fuel-specific consumption of the SAPG plant is determined to be lower than that of the reference coal-fired power plant. The fuel-specific consumption accrual distribution in SAPG plants is used to assess the effect of each individual replacement. Effective strategies to reduce the specific costs of the SAPG and coal-fired power plants are proposed based on the results of this study.

关键词： solar-aided power generation specific consumption theory fuel-specific consumption cost-specific consumption

Electromechanical Fields Near a Circular PN Junction Between Two Piezoelectric Semiconductors

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Acta Mechanica Solida Sinica 2018年第2期31卷 127-140页

作者： Yixun luo Ruoran cheng Chunli Zhang Weiqiu chen Jiashi yang Department of Engineering Mechanics Zhejiang University Hangzhou 310027 Zhejiang China Department of Mechanical and Materials Engineering University of Nebraska-Lincoln Lincoln NE 68588-0526 USA Soft Matter Research Center (SMRC) Zhejiang University Hangzhou 310027 China Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Hangzhou 310027 China

We study electromechanical fields near the interface between a circular piezoelectric semiconductor cylinder and another piezoelectric semiconductor in which it is embedded. The cylinder is p-doped. The surrounding material is n-doped. The phenomenological theory of piezoelectric semiconductors consisting of the equations of piezoelectricity and the conservation of charge for holes and electrons is used. The theory is linearized for small carrier concentration perturbations. An analytical solution is obtained, showing the formation of a PN junction near the interface. Various electromechanical fields associated with the junction are calculated. The effects of a few physical parameters are examined.

关键词： Piezoelectric semiconductors Cylinder Carriers PN junction Electromechanical coupling

Research on Threshold Adjustment Algorithm in Adaptive Modulation and Coding

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The Journal of China Universities of Posts and Telecommunications 2006年第2期13卷 15-19页

作者： FAN chen chen Mei-ya SU Li-jun yang Da-cheng School of Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 P.R. China

Adaptive Modulation and Coding （AMC） has gained a lot of attentions in the research of High Speed Downlink Packet Access （HSDPA）. The idea is to adapt the transmission to the fast changing channel conditions by the use of different Modulation and Coding Schemes （MCS）. This paper presents an adaptive AMC algorithm and introduces a theoretical analysis model in order to to investigate its throughput and Frame Error Rate （FER）. Subject to the given FER target, our numerical and link level simulation results both show that our algorithm outperforms other existing adaptive algorithms.

关键词： adaptive modulation and coding threshold adjust markov model HSDPA

Progress on RE2O3-Mo/W matrix secondary emitter materials

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Science China(Technological Sciences) 2017年第10期60卷 1439-1446页

作者： WANG JinShu DONG LiRan LIU Wei yang Fan chen ShuQun School of Materials Science and Engineering Beijing University of Technology Beijing 100124 China

Two types of secondary emitter materials, the rare earth oxides(RE_2O_3) doped Mo cermet cathodes and the Y_2O_3-W matrix pressed cathode, are introduced in this paper. According to the calculation results, Y_2O_3 exhibits the best secondary emission property among Y_2O_3,La_2O_3,CeO_2 and lu_2O_3. The rare earth oxides co-doped Mo cathodes in which Y_2O_3 is the main active substance exhibit better secondary emission property than single RE_2O_3 doped Mo cathode. The results obtained by the Monte-Carlo calculation method show that the secondary electron emission property is strongly related to the grain size of the cathode. The decreasing of the grain size reduces the positive charge effect of the rare earth oxide due to the electrons supplement from the metal to the rare earth oxide, whereby the secondary electrons are easier to escape into the vacuum. Y_2O_3 is introduced into Ba-W cathode to fabricate a pressed Y_2O_3-W matrix dispenser cathode. The result indicates that the secondary emission yield of the Ba-W cathode increases from 2.13 to 3.51 by adding Y_2O_3, and the thermionic emission current density(J_0) could reach 4.18 A/cm^2 at 1050 ℃b.

关键词： rare earth oxide molybdenum tungsten cathode