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Search Results: 1 - 10 of 70931 matches for " Yu Qiang "
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Evaluation of Fatigue Life of Semiconductor Power Device by Power Cycle Test and Thermal Cycle Test Using Finite Element Analysis  [PDF]
Kazunori Shinohara, Qiang Yu
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.212127
Abstract: To accurately predict the fatigue life of a power device, a fatigue life evaluation method that is based on the power cycle is presented in terms of an algorithm based on a combination of electrical analysis, heat analysis, and stress analysis. In literature, the fatigue life of power devices has been evaluated on the basis of the thermal cycle. This cycle is alternately repeated within a range from a high temperature to a low temperature. In an actual operating environment, however, a power device works in a power cycle that consists of being switched ON and OFF. To accurately predict the fatigue life cycle of a device, then, the evaluation should take account of this important aspect of the power cycle. To verify the utility of the evaluation method presented in this study, the results for a power cycle based on the combined use of electrical analysis, heat analysis, and stress analysis are compared to the results based on the thermal cycle, as found in the literature. Our conclusion is that the fatigue life cycle as estimated by the thermal cycle test is higher than that estimated by the power cycle.
Preparation for Graphite Materials and Study on Electrochemical Degradation of Phenol by Graphite Cathodes  [PDF]
Xiujuan Yu, Liwen Qiang
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.22011
Abstract: Nanographite flake through ultrasound dispersing expanded graphite which got by chemical oxidation and microwave puffing method have been prepared by natural flake graphite. The microstructures of natural flake graphite, expanded graphite and nanographite sheets were characterized by means of SEM, XRD, FTIR and Raman; the cathodes were made by NG, EG and nanographite, respectively; the electrolysis phenol was conducted by the diaphragm cell prepared cathode and the Ti/RuO2 anode. The results showed that the thickness of graphite flake was 18 nm, and the grain size and particle size decreased compared with the NG and EG; Nano-G showed the best electrochemical properties; in the diaphragm electrolysis system with the aeration conditions, the degradation rate of phenol reached 89.5% COD reached 81.3% under 120 min’s electrolysis, which was far above the degradation rate of phenol of EG cathode and NG cathode.
Study on the Optimization Path of Performance Appraisal from the Perspective of Motivating Employees’ Enthusiasm
—Take Lin Zhi Haobo Education Training Co., LTD as an Example

Yan He, Wei Zhang, Qiang Yu
Journal of Human Resource and Sustainability Studies (JHRSS) , 2018, DOI: 10.4236/jhrss.2018.63039
Abstract: The article takes Linzhi city perfect education as the object of performance appraisal. With a perfect education company to field visit investigation and using the methods such as interview, questionnaire investigation, the authors learn the existing problems in the company currently and they also find the causes of the problems. In order to develop staff progress review and convenient staff performance appraisal management, the authors complete the establishment of the balanced scorecard and the construction of key performance indicators (kpis) examination cycle model.
Research on Information Resource Integration of University Libraries under the Mode of Knowledge Management  [PDF]
Yu-Qiang Guo, Zheng-Yu Sha
Intelligent Information Management (IIM) , 2012, DOI: 10.4236/iim.2012.45030
Abstract: On the grounds of expounding the situation of university library knowledge management and according to the characteristics of knowledge management, the paper combines the development of resource integration of library of Wuhan University of Technology, and analyzes the objects, trends and innovation of resource integration under the mode of knowledge management.
Enantioselective Synthesis of Homo-N-Nucleosides Containing a 1,4-Dioxane Sugar Analog
Qiang Yu,Per Carlsen
Molecules , 2008, DOI: 10.3390/molecules13122962
Abstract: A dioxane homo-sugar analog, (2S,5S)-and (2R,5S)-5-[(4S)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-iodomethyl-1,4-dioxane was prepared from (2R,3R)-dimethyl tartrate, and further elaborated into the corresponding homo-N-nucleoside analogs by its reactions with uracil and adenine, respectively.
Synthesis of Polynucleotide Analogs Containing a Polyvinyl Alcohol Backbone
Qiang Yu,Per Carlsen
Molecules , 2008, DOI: 10.3390/molecules13030701
Abstract: Water soluble homo-base polynucleotide analogues were synthesized in whichpolyvinyl alcohol and partially phosphonated polyvinyl alcohol constituted the backbones,onto which were grafted uracil or adenine via 1,3-dioxane spacers formed by acetalformation with the 1,3-diol moieties in PVA. The resulting adenine-PVA polynucleotideanalogs exhibited hyperchromic effects, which was not the case for the correspondinguracil compounds. Mixtures of the adenine- and aracil PVA-phosphate polynucleotideanalogs in solutions exhibited characteristic S-shaped UV-absorbance vs temperature andmelting curves with melting points at approximately 40 oC.
Synthesis of a Novel Benzoyl Adenosine Analog Containing a 1, 4-Dioxane Sugar Analog and the Synthesis of a Corresponding Uracil Adenine Dinucleotide
Qiang Yu,Per Carlsen
Molecules , 2011, DOI: 10.3390/molecules16053985
Abstract: Adenosine analogs in which the sugar unit was replaced by a 1,4-dioxane sugar equivalent, were prepared by coupling the 1,4-dioxane sugar analog as its anomeric acetates, with N6-benzoyl protected adenine. The 1,4-dioxane system was obtained in an enantioselective synthesis from (R,R)-dimethyl tartrate. Using standard phosphorimidite methodology, the adenine analog was further reacted with a 1,4-dioxane uridine analog to give the corresponding, protected dinucleotide, set-up for further condensation into larger oligonucleotides.
On the Occupational Career Planning for College Secretary
Lanlan Liu,Qiang Yu
Economic Management Journal , 2012,
Abstract: With the deepening reform of higher education, the profession of being college secretary has also been standardized and improved. College secretary must formulate proper occupational career plan according to his or her own characteristcs, realize the significance and necessity of career planning, and pay attention to career orientation and initiative taking, clear stage target so as to construct a reasonable knowledge structure, develop professional capabilities, and to obtain a better and extended career.
Inverse Photoelectrochemical Cell
Qiang Yu,Chuanbao Cao
Physics , 2013,
Abstract: The splitting of water with sunlight using photoelectrochemical cell (PEC) to produce hydrogen is a promising avenue for sustainable energy production. The greatest virtue of PEC is that it uses sunlight as the only source to split water, but its efficiencies are still quite low due to poor performances of the available materials (such as SrTiO3). Consequently, another way of PEC research has been developed. By simultaneously using sunlight and electricity as energy source, PEC can get a larger current at a lower voltage, i.e., hydrogen can be made under the voltage below 1.23V, the minimum voltage required by electrolysis of water. But so far the efficiencies of the mainstream materials (such as TiO2) remain low. Where is the future development direction of PEC? Here we propose a new PEC model. Its operating principle is quite the opposite of the aforesaid conventional PEC, that is, the previous photoanode/photocathode is converted into the present photocathode/photoanode. It can also obtain high current under low voltage, even near zero voltage in extreme conditions. A basic single configuration and an improved n-p configuration were designed. We reselected materials for photoelectrodes, and confirmed its feasibility successfully. Two preliminary results were obtained from two contrasts: whether compared with water electrolysis or conventional PEC water splitting, the inverse PEC showed promising superiority.
Phase transitions and elementary excitations in spin-1 Bose gases with Raman induced spin-orbit coupling
Zeng-Qiang Yu
Physics , 2015,
Abstract: We study the ground state phase diagram and the quantum phase transitions in spin-1 Bose gases with Raman induced spin-orbit coupling. In addition to the Bose-Einstein condensates with uniform density, three types of stripe condensation phases that simultaneously break the U(1) and the translation symmetry are identified in presence of spin-dependent interactions. The transitions between these phases are characterized by the spin magnetization and different crystalline orders, and the occurrences of the various tricritical points are predicted. The excitation spectra in the plane-wave phase and the zero-momentum phase show rich roton-maxon structures, and their instabilities indicate the tendency to develop crystalline orders. We propose the atomic gas of $^{23}$Na could be a candidate for observing the stripe condensate with high contrast fringes.
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