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Low power linear actuator for direct drive electrohydraulic valves

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第7期9卷 940-943页

作者： Yong LI Fan DING Jian CUI Qi-peng LI State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China School of Mechanical and Automobile Engineering Zhejiang University of Science and Technology Hangzhou 310023 China

This paper presents a bi-directional permanent-magnet linear actuator for directly driving electrohydraulic valves with low power consumption. Its static and dynamic performances were analyzed using the 2D finite element method,taking into account the nonlinear characterization and the eddy current loss of the magnetic material. The experiment and simulation results agree well and show that the prototype actuator can produce a force of ±100 N with the maximum power being 7 W and has linear characteristics with a positive magnetic stiffness within a stroke of ±1 mm. Its non-linearity is less than 1.5% and the hysteresis less than 1.5%. The actuator's frequency response(-3 dB) of the displacement reaches about 15 Hz,and the most significant factor affecting the dynamic performance is identified as the eddy current loss of the magnetic material.

关键词： Electrohydraulic valves Linear actuator Low power High pressure Positive magnetic stiffness

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Response of reed community to the environment gradientwater depth in the Yellow River Delta, China

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Frontiers in Biology 2008年第2期3卷 194-202页

作者： Baoshan CUI Xinsheng ZHAO Zhifeng YANG Bin CHEN Na TANG Xuejie TAN State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentBeijing Normal UniversityBeijing 100875China

We investigated and monitored a reed community in the *** on the bio-ecological characteristics and β-diversity of reed communities in different environmental gradients(mainly based on water depth)of the Yellow River Delta were collected through multianalysis,extremum analysis and β-diversity index *** accordance with the square sum of deviations(Ward)cluster analysis,10 sampling plots were divided into six types with the dominant plants in different plots varying according to the change in environmental *** dominant plants in these plots varied from aquatic plants to xerophytes and salt tolerant plants as water depth *** average height and diameter of the reeds at breast level were significantly correlated with the average water *** fitness curves of average density and coverage with average water depth were *** the average water depth was 0.3 m,the average density and coverage of reeds reached the apex value,while the height and diameter of the reeds at breast level increased with the water *** were obvious changes to the environmental gradient in the Yellow River *** transitional communities were also found to exist in the Yellow River Delta by β-diversity *** species appeared with the change in water *** occurrence of substitute species is determined by the function of common species between adjacent *** different functions of common species led to differences in community structure and function and differences in dominant *** result reflects the variations of species present in different habitats and directly reflects environmental *** values of β-diversity indices of adjacent plots were higher than those of nonadjacent *** are transition zones between the xerophytes and aquatic plants in the Yellow River *** an aquatic environment,the similarity of reed community is higher than that of xeromorphic *** β-diversity index can refl

关键词： reed β-diversity environmental gradient wetland the Yellow River Delta

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Temporal-spatial variation and the influence factors of precipitation in Sichuan Province,China

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Frontiers in Biology 2008年第2期3卷 236-240页

作者： Ruimin LIU Zhenyao SHEN State Key Laboratory of Environment Simulation and Pollution Control School of EnvironmentBeijing Normal UniversityBeijing 100875China

Precipitation is a key factor in the water *** the same time,precipitation is the focus of study in meteorology and climatology,ecological environmental assessment,non-point source pollution and so *** the temporal-spatial variation and the corresponding factors of precipitation has become the object of hydrology and *** on the annual precipitation data,we analyzed the spatial distribution of precipitation in Sichuan Province in China as well as the temporal-spatial variation and the corresponding influence factors *** results show that the amount of precipitation was abundant,but the spatial distribution was not consistent with it and the amount of precipitation gradually declined from the south-east to the north-west in Sichuan Province,***,the spatial distribution was different throughout the *** result of correlation analysis indicated that elevation,temperature and air pressure were three key factors affecting the amount and distribution of precipitation,and the correlation coefficients were 20.56,0.38 and 0.45 ***,the relationship between the slope of topography and precipitation were significantly negative and the average correlation coefficient was 20.28.

关键词： Sichuan Province precipitation geostatistics temporal-spatial variation

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System design and parameter matching for the new generation of hybrid electric city bus

System design and parameter matching for the new generation ...

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2008 SAE International Powertrains, Fuels and Lubricants Congress

作者： Xiaohua, Zeng Qingnian, Wang Dafeng, Song Weihua, Wang Jilin University State Key Laboratory of Automobile Dynamical Simulation China Renmin Street 5988 # ChangChun City China

In this paper, based on the research of the first generation of a hybrid electric city bus, principle researches have been offered on the parameters matching of the power-train and main components for the new generation of hybrid electric city bus. The vehicle system was designed integrated, and then simulation platform was developed and established. The dynamic and economy performance can be predicted based on the above work, results show that the designed hybrid electric city bus can meet the performance demands and validate rationality of the parameters matching. © 2008 SAE International.

关键词： Buses

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摩托车空气动力学数值模拟研究新进展

摩托车空气动力学数值模拟研究新进展

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2009年全国工业空气动力学学术会议

作者： Zhang Yingchao 张英朝 Li Jie 李杰 Zhang Zhe 张喆 State Key Laboratory of Automobile Dynamic Simulation Jilin University Changchun 130022 Jilin Pro 吉林大学汽车动态模拟国家重点实验室吉林省长春市130022

随着中国摩托车工业技术的进步，在国家节能减排的大环境下，摩托车的空气动力学逐渐被重视。首先介绍了摩托车空气动力学研究内容、评价方法、研究手段。根据摩托车空气动力学的研究需要，归纳总结了基于计算流体力学(CFD)的摩托车数... 详细信息

随着中国摩托车工业技术的进步，在国家节能减排的大环境下，摩托车的空气动力学逐渐被重视。首先介绍了摩托车空气动力学研究内容、评价方法、研究手段。根据摩托车空气动力学的研究需要，归纳总结了基于计算流体力学(CFD)的摩托车数值模拟的程序和方法。介绍了摩托车数值模拟的前处理、计算求解和后处理的关键问题的处理办法。对摩托车车体、摩托车及驾驶员及摩托车车身气动附件进行了数值模拟研究。对数值模拟的结果进行分析，通过流场的分析提出了一些摩托车空气动力学设计方面的建议。

关键词：摩托车空气动力学计算流体力学数值模拟

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Isolation of a Pseudomonas Stutzeri strain that degrades 1,2,4-trichlorobenzene and characterization of its degradative plasmid

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Frontiers of Environmental Science & Engineering 2008年第1期2卷 69-72页

作者： Lei SONG Hui WANG Hanchang SHI Hongying HU Environmental Simulation and Pollution Control State Key Joint Laboratory Department of Environmental Science and EngineeringTsinghua UniversityBeijing 100084China

The genetic information encoding metabolic pathways for xenobiotic compounds in bacteria often resides on catabolic *** aim of the present work was to know the location of the genes for degrading 1,2,*** this paper a 1,2,4-trichlorobenzene-degrading strain THSL-1 was isolated from the soil of Tianjin Chemical Plant using 1,2,4-trichlorobenzene as the sole carbon *** strain was identified as Pseudomonas stutzeri through morphologic survey and 16S rDNA sequence determination.A plasmid was discovered from strain THSL-1 by using the alkali lysis *** the plasmid was transformed into ***109 by the CaCl2 method,the transformant could grow using 1,2,4-trichlorobenzene as the sole carbon source and had the degradation function of 1,2,***,it could be deemed that the plasmid carried the degradative genes of 1,2,*** average size of the plasmid was finally determined to be 40.2 Kb using selectively three kinds of restricted inscribed enzymes(HindIII,BamHI,and XholI)for single cutting and double cutting the plasmid pTHSL-1,respectively.

关键词： 1,2,4-trichlorobenzene 16S rDNA degradative plasmid Pseudomonas sp.

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Improvement of detection method of Cryptosporidium and Giardia in reclaimed water

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Frontiers of Environmental Science & Engineering 2008年第3期2卷 380-384页

作者： Tong ZHANG Xing XIE Hongying HU Yudong SONG Qianyuan WU Zusheng ZONG Environmental Simulation and Pollution Control State Key Joint Laboratory Department of Environmental Science and EngineeringTsinghua UniversityBeijing 100084China

Cryptosporidium and Giardia are two typical species of pathogenic protozoans that seriously endanger water *** works indicated that detection of Cryptosporidium and Giardia with modified United states Environmental Protection Agency(USEPA)method-1623 using a membrane filtration-elution for sample concentration attained better recovery and lower cost compared to the USEPA *** improvements of membrane filtration-elution step as well as immunomagnetic separation(IMS)steps were investigated and an optimized method for detection of Cryptosporidium and Giardia in wastewater reclamation system was recommended in this *** experimental results show that an overnight soak of the membrane after scraping and vortex agitation before elution could enhance and stabilize the *** turbidity to 4 NTU by adding kaolin clay before filtration could effectively improve the recovery of low-turbidity *** the concentrate after centrifugation and twice acid dissociation both reduced the impact of water quality to protozoan *** in different water samples were determined by this optimized method,and the recovery of Cryptosporidium and Giardia were above 70% and 80%respectively,much higher than the acceptance of method-1623.

关键词： concentration Cryptosporidium Giardia immunomagnetic separation(IMS) wastewater reuse

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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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2008 IEEE Vehicle Power and Propulsion Conference, VPPC 2008

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

ISBN: (纸本)9781424418497

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. © 2008 IEEE.

关键词： Electromagnetic waves

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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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2008 IEEE Vehicle Power and Propulsion Conference, VPPC 2008

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

ISBN: (纸本)9781424418497

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 15kW ASD system validates the effectiveness of the proposed design method. © 2008 IEEE.

关键词： Software design

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Vertical characteristics of the Hani terrace paddyfield ecosystem in Yunnan,China

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Frontiers in Biology 2008年第3期3卷 351-359页

作者： Baoshan CUI Zheyuan YOU Min YAO School of Environment Beijing Normal UniversityBeijing 100875China State Key Joint Laboratory of Environmental Simulation and Pollution Control Beijing 100875China

The Hani terrace paddyfield in Yunnan Province,China is categorized as a‘constructed wetland’under the Lamsar Convention *** Hani terrace paddyfield ranges from an altitude of 144 to 2000 m above sea level(ASL)in the southern slopes of the Ailao Mountains,angling down at a range of 15°to 75°.In this study,we investigated the ecosystem of the terrace paddyfields in the Mengpin and Quanfuzhuang administrative villages located at the center of the cultural heritage conservation district in the Hani terrace *** Hani terrace paddyfield ecosystem structure is"forest-village-terrace paddyfield-river"in the order of descending *** and water samples were sequen-tially taken from forests,villages and the terrace paddy-fields to be able to study the vertical characteristics of Hani’s terrace ***_(4)-P and NH_(3)-N in water were measured to test for water *** soil nutrient factors were tested,including organic material(OM),char and nitrogen ratio(C/N),pH,total nitrogen(TN),total phosphorus(TP),available phosphorus(AP),and available potassium(AK).Soil quality was also eval-uated using the characteristics of the soil nutrient *** changes in the landscape,wetland types,wetland plants,hydrology and soil nutrients were *** showed that:(1)Hani’s terrace paddyfield can be divided into five types of wetlands;the rice varieties and cultivation patterns vary in each type of wetland.(2)Hani’s terrace paddyfield has a great capacity for water conservation and a strong ability to purify *** impoundage of Hani’s terrace paddyfield is about 5050 m^(3)/hm^(2).Contaminants in the terrace paddyfield soils decrease exponentially with the decline in altitude.(3)Comparison of soil quality in five different land use types indicates decreasing soil quality from forest to terrace land to terrace paddyfield to water *** for headwater soil,single factors such as OM,TN and TP,and the comp

关键词： Hani’s terrace paddyfield wetland landscape wetland types wetland water wetland soil vertical characteristics

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