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Search Results: 1 - 10 of 80797 matches for " Dichen Liu "
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The Study of Optimal Structure and Value of Dump Resistance in Direct-Drive Permanent Magnet Synchronous Generators  [PDF]
Jun Jia, Jie Zhao, Dichen Liu, Chen Cheng, Jun Wang, Linge Qi
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.24044
Abstract: This paper studied the direct-drive permanent magnet synchronous machine (permanent magnet synchronous generator, PMSG) Chopper optimal topology and resistance value. Compared the different Chopper circuit low voltage ride-through capability in the same grid fault conditions in simulation. This paper computes the dump resistance ceiling according to the power electronic devices and over-current capability. Obtaining the dump resistance low limit according to the temperature resistance allows, and calculating the optimal value by drop voltage in the DC-Bus during the fault. The feasibility of the proposed algorithm is verified by simulation results.
Component Analysis and Calculation for Social Benefits of UHV Assessment  [PDF]
Jingshan Luo, Dichen Liu, Jun Wu, Fan Gao, Qixin Wang, Kai Wang, Xuedong Zhu
Smart Grid and Renewable Energy (SGRE) , 2016, DOI: 10.4236/sgre.2016.710020
Abstract: With the rapid development of the UHV power grid, evaluation of the economic and social benefits of the UHV power grid is conducive to guiding the planning and construction of UHV power grid. At present economic benefit evaluation system of the UHV power grid is driving to maturity stage on the whole at home and abroad, but it invariably tends to regard social benefits as part of economic benefits, without evaluating social benefit separately. The social benefit evaluation model of UHV power grid is built in case of sufficient investigation. The differentials between social benefit and social cost are calculated respectively by three kinds of solutions according to the constructed social cost evaluation index system and social benefits evaluation index system, conclusion that UHV power grid transmission has better social benefits can be reached by contrastively analyzing the social three kinds of solutions corresponding to benefits. At last, the evaluation model and method are verified and analyzed through the analysis of engineering projects.
The effect of latency on bone lengthening force and bone mineralization: an investigation using strain gauge mounted on internal distractor device
Sekou Singare, Dichen Li, Yaxiong Liu, Zhongying Wu, Jue Wang
BioMedical Engineering OnLine , 2006, DOI: 10.1186/1475-925x-5-18
Abstract: Distraction tensions were investigated at different latency period in 36 rabbits using internal unilateral distractor. Strain gauges were prepared and attached to the distractor to directly assess the level of distraction tension during mandible lengthening. The tensile force environment of the mandible of rabbit during distraction was evaluated through in vivo experiments using two gauges.The animals were divided into 3 groups each containing 12 rabbits. Latency periods of 0, 4 and 7 days respectively were observed prior to beginning distraction. The distraction protocol consisted of a lengthening rate of 1 mm once daily for 8 days, followed by a consolidation phase of 2 weeks after which the animals were killed. Biopsies specimens were taken from the distracted area at the end of the distraction period. A non-distracted area of the mandible bone served as control. The specimens were analyzed by scanning electron microscopy to assess the ultrastructural pattern, and the bone mineralization.The resting tension acting on the distraction gap increases through distraction. The 7-day latency groups exhibit higher tension then those of 0-day and 4-days latency groups. Quantitative energy dispersive spectral analysis confirmed that immediate distractions were associated with lower calcium and phosphate atomic weight ratio.the latency periods could affect the bone lengthening tension and the bone mineralization process.Distraction osteogenesis is a surgical process for reconstruction of skeletal deformities. It involves gradual, controlled displacement of surgically created fractures, which results in simultaneous expansion of soft tissue and bone volume. It was first used in limb lengthening by Codivilla [1] in 1905, and later the use of this technique in canine mandible was first reported by Snyder et al [2]. In 1992 McCarthy et al. [3] demonstrated the clinical application of distraction osteogenesis technique in craniofacial skeleton for 4 young patients. To day, distr
LASER-INTERFEROMETRIC MULTICOORDINATE NANOPOSITIONING SYSTEM
多坐标激光干涉仪用于纳米定位系统中的研究

Liu Hongzhong,Zhao Wanhua,Li Dichen,Lu Bingheng,
刘红忠
,赵万华,李涤尘,卢秉恒

光子学报 , 2002,
Abstract: LM series multicoordinate laser-interferometer is used in nanopositioning system to realize synchromeasure.Its characteristics are smaller structure,little weight,laser lamp-house divided from interferometer and eliminating facts of vibration and heat.Its high resolution,large measuring space and intelligent analysis are fit for IC(Integrated circuit),micro-machine,biochip etc.manufacture equipment.The system is controlled by cups and realizes parellel control,high-speed real time positioning.
Diamond-Structured Photonic Crystals with Graded Air Spheres Radii
Qingxuan Liang,Dichen Li,Haoxue Han
Materials , 2012, DOI: 10.3390/ma5050851
Abstract: A diamond-structured photonic crystal (PC) with graded air spheres radii was fabricated successfully by stereolithography (SL) and gel-casting process. The graded radii in photonic crystal were formed by uniting different radii in photonic crystals with a uniform radius together along the Г?Х direction. The stop band was observed between 26.1 GHz and 34.3 GHz by reflection and transmission measurements in the direction. The result agreed well with the simulation attained by the Finite Integration Technique (FIT). The stop band width was 8.2 GHz and the resulting gap/midgap ratio was 27.2%, which became respectively 141.4% and 161.9% of the perfect PC. The results indicate that the stop band width of the diamond-structured PC can be expanded by graded air spheres radii along the Г?Х direction, which is beneficial to develop a multi bandpass filter.
The Model of Mobile Knowledge Services System in the Management of Complex Cluster Project  [PDF]
Yong Liu, Bingxin Liu
iBusiness (IB) , 2011, DOI: 10.4236/ib.2011.31006
Abstract: Cluster projects are projects of large-scale or with huge investment, such as Beijing 2008 Olympic Games and Shanghai 2010 Expo. A lot of on-site management works are involved in the process of cluster project management, especially the treatment of sudden accidents which would produce plenty of knowledge and experience. As cluster project on-site management spots change frequently, knowledge produced by mobile workers in the process of on-site management is hard to be saved into the knowledge repository on time. It may cause a knowledge distortion or even missing. On the other hand, in the process of cluster project management, a lot of knowledge is required by on-site workers to deal with on-site activities. However, due to lack of effective mechanisms for knowledge communion, they often face the risk of making wrong decisions. To solve the problems of knowledge management and acquisition in the process of cluster project on-site management, this paper presents a system model for mobile knowledge service.
The Collusion Deterrence with Prisoner’s Dilemma  [PDF]
Aidong Liu, Jinfang Liu
Journal of Service Science and Management (JSSM) , 2010, DOI: 10.4236/jssm.2010.34053
Abstract: I tried to present a new method to prevent collusion through employing two auditors at the same time and inspiring them provide true report by exploiting their prisoner’s dilemma. But I found this method cannot be put into practice because of the high cost. So I analyzed whether sending the second auditor in a probability, a low cost method, can deter the audit collusion. I find sending the second auditor in a probability, enforcing the rigidly lawful punishment and perfecting the reward mechanism can prevent audit collusion. I also find the auditor’s ethical constraint do good to prevent collusion and the charger of state assets management can play the same role as the real owner of the state-owned enterprise in deterring collusion. This finding provides theory support for the government to implement the publicly audit bidding and random double auditing system on state-owned enterprise. The supervision of PCAOB on auditors is also the operation of this theory.
Using Insulation in China’s Buildings: Potential for Significant Energy Savings and Carbon Emission Reductions  [PDF]
Guoliang Liu, Hans Liu
Low Carbon Economy (LCE) , 2011, DOI: 10.4236/lce.2011.24027
Abstract: Most old residential and commercial buildings in China are not insulated or not to new standards. This is true even in regions with very cold winters or regions with very hot summers. The insulation in new buildings is very poor relative to North American standards. However, insulating the exterior walls, attic roofs, and foundation walls to new standards of buildings in China would reduce the need for heating and air conditioning, and thus would save roughly 200 million tons of coal each year. This in turn would lead to a reduction in CO2 emissions of about 510 million tons per year, which is equal to about 8.4% of China’s total carbon emissions in 2006. The use of insulation in buildings will help homeowners save money, help China save energy and help the environment all at the same time. Insulation will provide a continued payback to the homeowner, not only in dollars and cents, but also by providing a more enjoyable and comfortable living environment for many years.
An Elementary Introduction to Training the Postgraduates for Professional Degrees in Oil and Gas Engineering  [PDF]
Qingyou Liu, Zhibin Liu
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.326126
Abstract: The demand of the talents in petroleum engineering of petroleum enterprises is analyzed in this paper according the current situation of the engineering education. The four levels of the professional talents needed by the petroleum enterprises are specified, which makes it clear that what the purpose and orientation of the higher education in petroleum engineering should be. The qualities of the petroleum engineers are discussed specifically and it is pointed out that the training of the postgraduate for professional degree in oil and gas engineering should be the cradle of the petroleum engineers. A training schedule is listed in this paper based on the discussion, including curriculum provision, practice link, thesis and training mode, which will be a pathfinder of the education of the professional degree graduate student in oil and gas engineering. Moreover, the practice can provide useful experience for the training and education of different type of graduates.
Overall Framework and Module of Distribution Network Coordinated Planning Considering Distributed Generation  [PDF]
Qianjin LIU, Huanghuang LIU
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.51B006
Abstract: Combining with the characteristics of China's energy and the strategy of sustainable development, analyzing the pros and cons which caused by the appearance of DG and their operation connecting to grid, this paper points out that the two sides can achieve win-win under a reasonable combination between DG and distribution system, so as to optimize the allocation of resources, improve the utilization ratio of resource, and obtain maximum social benefit, harmoniously promote the development of power industry, economy and environment. As a word, this paper puts forward a new model of distribution network planning including DG and brings in penalty factorto guide the investment and construction of DG. Last of all, this paper presents the adoption of the coordination development coefficients which is to evaluate the power planning.
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