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Search Results: 1 - 10 of 23260 matches for " Zhiman He "
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A Two-Dimensional Cloud Model for Condition Assessment of HVDC Converter Transformers
Jian Li,Zhiman He,Youyuan Wang,Jinzhuang Lv,Linjie Zhao
Energies , 2012, DOI: 10.3390/en5010157
Abstract: Converter transformers are the key and the most important components in high voltage direct current (HVDC) power transmission systems. Statistics show that the failure rate of HVDC converter transformers is approximately twice of that of transformers in AC power systems. This paper presents an approach integrated with a two-dimensional cloud model and an entropy-based weight model to evaluate the condition of HVDC converter transformers. The integrated approach can describe the complexity of HVDC converter transformers and achieve an effective assessment of their condition. Data from electrical testing, DGA, oil testing, and visual inspection were chosen to form the double-level assessment index system. Analysis results show that the integrated approach is capable of providing a relevant and effective assessment which in turn, provides valuable information for the maintenance of HVDC converter transformers.
Influences of Corrosive Sulfur on Copper Wires and Oil-Paper Insulation in Transformers
Jian Li,Zhiman He,Lianwei Bao,Lijun Yang
Energies , 2011, DOI: 10.3390/en4101563
Abstract: Oil-impregnated paper is widely used in power transmission equipment as a reliable insulation. However, copper sulphide deposition on oil-paper insulation can lead to insulation failures in power transformers. This paper presents the influences of copper sulfur corrosion and copper sulphide deposition on copper wires and oil-paper insulation in power transformers. Thermal aging tests of paper-wrapped copper wires and bare copper wires in insulating oil were carried out at 130 °C and 150 °C in laboratory. The corrosive characteristics of paper-wrapped copper wires and bare copper wires were analyzed. Dielectric properties of insulation paper and insulating oil were also analyzed at different stages of the thermal aging tests using a broadband dielectric spectrometer. Experiments and analysis results show that copper sulfide deposition on surfaces of copper wires and insulation paper changes the surface structures of copper wires and insulation paper. Copper sulfur corrosion changes the dielectric properties of oil-paper insulation, and the copper sulfide deposition greatly reduces the electrical breakdown strength of oil-paper insulation. Metal passivator is capable of preventing copper wires from sulfur corrosion. The experimental results are helpful for investigations for fault diagnosis of internal insulation in power transformers.
DDA Simulations of Large Flume Tests and Large Landslides Triggered by the Wenchuan Earthquake  [PDF]
Qingqing Yang, Zhiman Su, Fei Cai
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.26043
Abstract:

This paper presents some numerical simulations using Discontinuous Deformation Analysis (DDA). First, DDA was applied to reproduce a series of granular flows released in a large flume. The comparison between simulated velocity and that measured in the tests demonstrates the effectiveness of DDA on description of kinematic behavior of blocky assembly. Simulated results were highly sensitive to the shape and angularity of blocky elements. Employing unrealistic block might result in different behavior from real situation. Second, three large landslides triggered by the Wenchuan earthquake were simulated. A well agreement with field data was obtained if apparent friction coefficient determined by post-analysis was adopted.

The Revolution of Communication Media and Its Impact on Education  [PDF]
Lei He, Jian He
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.38014
Abstract: Medium means “middle” originally. When it is used as an academic term in communication theory, it would be a bridge of information exchange between two agents. The more advanced medium is, the richer amount of information it can carry. And then the communicating way changes. The way of thinking changes, too. This paper firstly analyzed the development of communication process and the corresponding changes in media, and then discussed the major impact on education re- form in different media. Each of the change will affect the media choice of teaching strategies and teaching effectiveness. Especially when the information media are used in education, much more information changing happens than ever before. People can learn with auditory, vision, tactus, olfaction, and so on. “Communication” became one of the most important keywords in the study sup- ported by information technology.
The Relevant Inferences of Electrodynamics under Non-Void Backgrounds  [PDF]
An He
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105713
Abstract:
The paper was based on the definition of time-rate, and founded the general transformation between reference systems that background had different standard of time, and the self-consistent theoretical system has been formed to promote the classical electrodynamics. According to the principle, more discussion about the relationship between structure of time-rate in space and physical properties in its own area (gravity, centrifugal force, acceleration system) was presented. In view of the above, the paper expounded the role of macro mechanism of gravity and inertia force, and unified them finally. The possibility of tremendous instantaneous acceleration has been put forward.
On the Performance of the Principle of Equitable and Reasonable Utilization in the Practice of the Utilization of Transboundary Water Resources  [PDF]
Yanmei HE
iBusiness (IB) , 2009, DOI: 10.4236/ib.2009.11007
Abstract: The principle of equitable and reasonable utilization is the fundamental one of International Water Law, which is generally established by international water treaties and soft law documents. It is better performed in the practice of the utilization of transboundary water resources. China can use it to participate in the development and utilization of Mekong river basin equitably.
On Legal Regulation of the Alienation of Science and Technology  [PDF]
Shiqing He
Beijing Law Review (BLR) , 2011, DOI: 10.4236/blr.2011.23012
Abstract: The alienation of science & technology is a kind of abnormal phenomenon coming from the research or use of science & technology. It makes science & technology from the tool that serves and brings benefit to human into the power that controls and harms human, so the regulation of the alienation of science & technology is the requirement of the sound development of science & technology, and the socio-economic progress, as well as the improvement of people's living standards. Law is the primary measure to regulate the alienation of science & technology. The legal regulation is the fundamental way because it provides the value orientation, the norms of behavior, the rational allocation of resources and the reward and punishment mechanism for the control of the alienation of science & technology. In China, The alienation of science & technology has gradually come into being and has increasingly been serious with the development of science & technology since the reform and open policy has been implemented. The legal regulation of the alienation of science & technology is an important component of the modernization construction, its promotion asks to be guided by scientific concept on development, firm the legal foundation, strengthen the responsibility of the government and bring the corrective function of judicature into full play.
Textual Metaphor from the Non-Finite Clausal Perspective  [PDF]
Qingshun He
Open Journal of Modern Linguistics (OJML) , 2013, DOI: 10.4236/ojml.2013.34039
Abstract: Grammatical metaphor in the Hallidayan sense only comprises ideational and interpersonal metaphors, while Martin and others propose the inclusion of textual metaphor. Based on metafunctions of Systemic Functional Linguistics, this paper analyzes the current discussions of textual metaphor, pointing out that some textual metaphors by Martin and others are in essence representations of ideational and interpersonal metaphors in text, and some are not in accordance with the principles of grammatical metaphor. Four types of textual metaphor with double functions are proposed from the perspective of non-finite clause relators; they are (1) elaborative non-finite clauses, (2) extensive and enhancing non-finite clauses without relators, (3) extensive and enhancing non-finite clauses with prepositions as relators, and (4) enhancing non-finite clauses with prepositionalized non-finite verbs.
Chinese Topic Chains: An Analysis of the Topic Chains Used in Fortress Besieged  [PDF]
Yuanxiu He
Open Journal of Modern Linguistics (OJML) , 2013, DOI: 10.4236/ojml.2013.34044
Abstract:

The functional typologists divide the languages in the world into two groups, one is the subject-prominent language group and the other is the topic-prominent group. English belongs to the subject-prominent language and Chinese to the topic-prominent language. This paper aims to discuss and summarize the types and functions of topic chains on the basis of analyzing the topic chains used in the novel Fortress Besieged written by Chinese famous writer Zhongshu Qian.

Positive Solutions for Singular Boundary Value Problems of Coupled Systems of Nonlinear Differential Equations  [PDF]
Ying He
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.29102
Abstract:

We establish the existence of positive solutions for singular boundary value problems of coupled systems \"\"

The proof relies on Schauder’s fixed point theorem. Some recent results in the literature are generalized and improved.




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