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Turnover and loss of nitrogenous compounds during composting of food wastes

Frontiers of Environmental Science & Engineering 2008年第2期2卷 251-256页

作者： Yanmei YANG Xiangfeng ZHANG Zhifeng YANG Beidou XI Hongliang LIU College of River and Ocean Engineering Chongqing Jiaotong UniversityChongqing 400074China State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentBeijing Normal UniversityBeijing 100875China Chinese Research Academy of Environmental Sciences Beijing 100012China

Few people have so far explored into the research of the dynamics of various nitrogenous compounds(including water-soluble nitrogen)in composting of food *** study aimed to investigate the solid-phase nitrogen,water-soluble nitrogen,nitrogen loss together with ammonia volatilization in the process of food wastes composting.A laboratory scale static aerobic reactor in the experiment was employed in the composting process of a synthetic food waste,in which sawdust was used as the litter *** the experiment,oxygen was supplied by continuous forced ventilation for 15 *** results have shown that the concentrations of total nitrogen and organic nitrogen decrease significantly in the composting process,whereasNH_(4)^(+)-N concentration increases together with little fluctuation in NO_(3)^(-)-*** composting,the total content of the water-soluble nitrogen compounds in the compost greatly increased,the total nitrogen loss amounted to 50% of the initial nitrogen,mainly attributed to ammonia volatilization.56.7% of the total ammonia volatilization occurred in the middle and late composting of the thermophilic *** suggested that the control at the middle and late composting of thermophilic stage is the key to nitrogen loss in the food waste compost.

关键词： composting nitrogen transformation nitrogen loss ammonia volatilization

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Instantaneous energy balancing in three-level neutral point clamped converters

Instantaneous energy balancing in three-level neutral point ...

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IEEE Conference on Vehicle Power and Propulsion (VPPC)

作者： Lu Ting Zhengming Zhao Liqiang Yuan Shuping Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China. State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Instantaneous energy balancing plays an important role in power electronics conversion. The unbalance of electromagnetic energy not only debases the system performance but also decreases the reliability and efficiency of the conversion. In this paper, instantaneous energy balancing problems in three-level neutral point clamped (NPC) converters are classified and discussed. Typical examples and their usual solutions of each kind of problems are expounded and compared. In the end of this paper, limitations and disadvantages of traditional methods are analyzed, and electromagnetic field method is summarized as the new trend to analyze electromagnetic energy transmission and exchange. The method using electromagnetic field theory is emphasized to be the better approach to solve the aforementioned energy balancing problems.

关键词： Voltage control Capacitors Open loop systems Pulse width modulation converters Power electronics Energy storage Switching converters Power system simulation Power system reliability Electromagnetic analysis

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The impacts of agricultural and rural economic policy system on agricultural non-point source pollution in China

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Journal of Environmental Science and Engineering 2008年第5期2卷 59-63页

作者： LIU Fang SHEN Zhen-yao GONG Yong-wei State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Beijing Normal University Beijing 100875 China

Agricultural and rural economic policy system is one main driving force for the evolvement of agricultural Non-Point Source （NPS） pollution. In this paper, the main policies that influence agricultural NPS pollution are chosen, and a method to evaluate the impacts of agricultural and rural economic policy system on agricultural NPS pollution is brought forward. According to this, the questions about how and to what degree the policy system influence on agricultural NPS pollution are discussed.

关键词： agricultural and rural economic policy system agricultural non-point source pollution impact analysis

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A novel Modbus RTU-based communication system for adjustable speed drives

A novel Modbus RTU-based communication system for adjustable...

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IEEE Conference on Vehicle Power and Propulsion (VPPC)

作者： Hu Sideng Zhao Zhengming Zhang Yingchao Wang Shuping State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781424418480

The communication protocol is important for applying adjustable speed drive (ASD) systems to an industry network. This paper proposes a novel scheme of communication system for the ASD system based on Modbus protocol. The most remarkable advantage of the approach lies in the tradeoff between performance and economic cost for a power converter system. The overall system is built on master-slave structure and easy for interacting with other networks. An additional study on the cyclic redundancy check (CRC) in Modbus RTU is introduced to obtain the optimization design in the actual application and the optimization method in software design is also presented. The performance of the communication system obtained from experiment conducted on the 15 kW ASD system validates the effectiveness of the proposed design method.

关键词： Variable speed drives Protocols Cyclic redundancy check Communication industry Power system economics Power generation economics Costs Master-slave Design optimization Application software

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Intelligent controller for LEDs lighting systems supplied by batteries

Intelligent controller for LEDs lighting systems supplied by...

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IEEE Conference on Vehicle Power and Propulsion (VPPC)

作者： Bo Feng Zhengming Zhao Yingchao Zhang Dejia Zhou Liqiang Yuan State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

LED lighting system supplied by batteries is one of effective solutions to vehicle and photovoltaic lighting systems. In order to improve lighting performance and prolong the life of LEDs and batteries, this paper proposes a novel intelligent controller for LED lighting systems. Stage constant current (SCC) control strategy is proposed, which determines the optimal working current of LEDs (I ref ) according to their ambient temperature and the capacity of batteries. For implementing SCC control strategy, a new control algorithm of double current loops and feedforward (DCLF) control is proposed based on Boost converter with constant current source. Both output current and inductor current are used as feedback control variables and input voltage is employed as feedforward compensation in the proposed algorithm. simulations have been conducted using PSIM software; and based on that, a 50 W photovoltaic LED lighting system has been developed to implement a serial of comparative experiments. The results show the advantages and validity of DCLF algorithm, such as excellent dynamic performance and good robustness.

关键词： Lighting control control systems Light emitting diodes LED lamps Photovoltaic systems Solar power generation Battery powered vehicles Optimal control Temperature control Inductors

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Ecological thresholds of Suaeda salsa to the environmental gradients of water table depth and soil salinity

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Acta Ecologica Sinica 2008年第4期28卷 1408-1418页

作者： Baoshan, Cui Qiang, He Xinsheng, Zhao State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Beijing Normal University Beijing 100875 China

The responses of Suaeda salsa to the environmental gradients of water table depth and soil salinity in the Yellow River Delta, China were analyzed from the aspect of ecological thresholds which were developed from the Gaussian model. Based on the correlation analysis of population biomass, density, height, coverage and abundance of Suaeda salsa, population biomass was selected as the population index for further analysis. The results indicated that the optimum water table depth for the growth of Suaeda salsa was about -0.42 m, the ecological thresholds were from -0.92 m to 0.08 m, and the optimum ecological thresholds were from -0.67 m to -0.17 m. To the soil salinity gradient, the optimum was about 12.71 g/kg, the ecological thresholds were from 5.17 g/kg to 20.25 g/kg, and the optimum ecological thresholds were from 8.94 g/kg to 16.48 g/kg. However, the effect of water-salinity interaction seemed to be important to the growth of Suaeda salsa, which was discussed through analyzing the water table depth-soil salinity relationship and their interactions. By using Ward cluster analysis and Gamma distances, 69 sampling sites were classified into 7 kinds of Suaeda salsa communities. It was found that there was a remarkable response of the community structure of Suaeda salsa to the water table depth and soil salinity gradients, which can be a switchover from xeromorphic and saline-alkali plants to limnophytes, and vice versa. © 2008 Ecological Society of China.

关键词： ecological threshold Gaussian model Suaeda salsa wetland Yellow River Delta

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simulation and analysis of roll stability for heavy tractor semi-trailers

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Jilin Daxue Xuebao (Gongxueban)/Journal of Jilin University (Engineering and Technology Edition) 2008年第SUPPL. 2期38卷 5-10页

作者： Mai, Li Zong, Chang-Fu Gao, Yue Huang, Chao-Sheng College of Mechanical Science and Engineering Jilin University Changchun 130022 China State Key Laboratory of Automobile Dynamics Simulation Jilin University Changchun 130022 China Research and Development Centre FAW Changchun 130022 China

Dealing with this question, this research sets up eight-freedom vehicle dynamic model with adjustable speed and simulates roll stability with different vehicle speeds under step steering input in Matlab/simulink, then analyses the vehicle speeds and structure parameters effect on roll stability. The simulation result shows that the drive axle of tractor lifts off firstly, result in the vehicle rollover when the speed or steering angle exceeds threshold values;the roll stability of heavy tractor semitrailers can be promoted by enlarging track, reducing the center height of sprung mass, enhancing roll stiffness of trailer suspension, reducing roll stiffness of tractor suspension.

关键词： Stiffness

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Investigation and analysis of the influence of magnetic wedges on high voltage motors performance

Investigation and analysis of the influence of magnetic wedg...

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2008 IEEE Vehicle Power and Propulsion Conference, VPPC 2008

作者： Wang, Shuping Zhao, Zhengming Yuan, Liqiang Wang, Buyao Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China Anhui Electric Power Research Institute Corporation Company Ltd. Department of XiangTan Electric Machine Xiangtan China

ISBN: (纸本)9781424418497

To weaken the pulsation of the harmonic magnetic field and improve the wave of the air-gap magnetic field in high voltage motors because of their open slots, magnetic slot wedge should be imbedded into the slot opening. In the paper, through analyzing the air-gap magnetic field distribution of large-scale motors affected by embedding magnetic slot wedges in open slots, the influence of magnetic slot wedge on the motor parameters and performance is discussed in theory. The finite element analysis (FEA) and the experiment results were given, which not only proves the validity of the analysis in the paper, also through the simulation results the proper parameters of magnetic slot wedges for best performance of motors were concluded, which provides a theoretical reference for the manufacturers when choosing or processing magnetic slot wedges. © 2008 IEEE.

关键词： Finite element method

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Modelling the Carrying Capacity of Urban Ecosystem

Modelling the Carrying Capacity of Urban Ecosystem

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The 2nd International Conference on Bioinformatics and Biomedical Engineering(iCBBE 2008)(第二届生物信息与生物医学工程国际会议)

作者： Linyu Xu Zhifeng Yang Wei Li State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Beijing Normal University Beijing China

The urban ecosystem is a Social-Economic-Natural Complex consisting of human beings and their surrounding. Because resources and environmental quality are crucial to the existence and development of an urban ecosystem, the development of an urban ecosystem is necessarily built on the basis of interactions among environmental carrying capacity (ECC), resource carrying capacity (RCC) and social-economic development capacity (SEDC). A single component's capacity should not be studied without considering the integrity of the whole system. In this paper, the concept of 'Compound carrying capacity' (CCC) is introduced and studied as an index of the interactions among ECC, RCC and SEDC, as a basis for meeting the challenges of urban sustainable development and eco-city building. Using this index, it is discussed in both theory fundamentals and quantitative models how these three kinds of capacity function to sustain the urban ecosystem. The concept of CCC is introduced to improve the comprehensive understanding of this system's structure and functions. Compared with traditional concepts, the CCC of the urban ecosystem includes the ability to develop and thus is characterized by being more dynamic. This dynamism shows in the ability of cities to respond when put under pressure. Clearly, this dynamic is not endless, both environmental, resource and social-economic development capacities have limits. A comparative study of urban ecosystems and the human immune systems shows that both systems have similar features. Thus, the CCC model is discussed in this paper in light of the biology immunity theory. In this it is assumed that the urban ecosystem is the material input and its main function is to offer eco-services. The extent of these services is dependent on both the intrinsic carrying capacity and the acquired carrying capacity of the urban ecosystem. The methodology for both calculation and adjustment mechanism of the CCC is outlined, with reference to the urban ecosystem

关键词： Urban Ecosystem Carrying capacity Guangzhou

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Application of the Export Coefficient Model in Estimating Nutrient Pollution of Dahuofang Reservoir Drainage Basin, Daliao River, China

Application of the Export Coefficient Model in Estimating Nu...

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International Conference on Bioinformatics and Biomedical Engineering (ICBBE)

作者： Rui-min Liu Meng-chang He Xiu-juan Wang State Key Laboratory Of Environ. Simulation and Pollution Control School of Environment Beijing Normal University Beijing China

In this paper, using export coefficient model and RS and GIS techniques, the NPS pollution load of Drainage Basin of Dahuofang Reservoir in the year 2000 was estimated, and its spatial distribution was simulated. Results indicates that the total nitrogen load is 3.90X103 tons, and that of total phosphorus is 1.57X102 tons, in which cropland, Qingyuan County and Xinbin County are important contributories. Analysis on the intensity load of NPS pollution shows that Xinbin County is the highest NPS pollution load areas, and these areas should be paid more attention in the future.

关键词： Water pollution Reservoirs Rivers Geographic Information Systems Nitrogen Analytical models Remote sensing Water resources Data processing Predictive models

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