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Search Results: 1 - 10 of 29924 matches for " SHI Quan "
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On the number of large triangles in the Brownian triangulation and fragmentation processes
Quan Shi
Mathematics , 2014,
Abstract: The Brownian triangulation is a random compact subset of the unit disk introduced by Aldous. For $\epsilon>0$, let $N(\epsilon)$ be the number of triangles whose sizes (measured in different ways) are greater than $\epsilon$ in the Brownian triangulation. We determine the asymptotic behaviour of $N(\epsilon)$ as $\epsilon \to 0$. To obtain this result, a novel concept of "large" dislocations in fragmentations has been proposed. We develop an approach to study the number of large dislocations which is widely applicable to general self-similar fragmentation processes. This technique enables us to study $N(\epsilon)$ because of a bijection between the triangles in the Brownian triangulation and the dislocations of a certain self-similar fragmentation process. Our method also provides a new way to obtain the law of the length of the longest chord in the Brownian triangulation. We further extend our results to the more general class of geodesic stable laminations introduced by Kortchemski.
Policy Based Self-Adaptive Scheme in Pervasive Computing  [PDF]
Jian Quan OUYANG, Dian Xi SHI, Bo DING, Jin FENG, Huai Min WANG
Wireless Sensor Network (WSN) , 2009, DOI: 10.4236/wsn.2009.11008
Abstract: Nowadays, application systems in pervasive computing have to be self-adaptive, which means adapting themselves to dynamic environments. Our aim is to enable systematic development of self-adaptive compo-nent-based applications. The paper first introduces a novel policy based framework for self-adaptive scheme in pervasive computing. Then the proposed policy ontology and policy language are well expressive and eas-ily extensible to support the design of policy which is based on the Separation of Concerns principle. Fur-thermore, the context-driven event channel decouples the communication between the suppliers and con-sumers for asynchronous communication. The proposed framework can provide both a domain-independent and a flexible self-adaptation solution.
Detection and attribution of abrupt climate changes in the last one hundred years

Zhang Wen,Wan Shi-Quan,

中国物理 B , 2008,
Abstract: Based on physical backgrounds, the four time series of the Guliya (Tibetan plateau) ice core (GIC) \textit{$\delta $}$^{18}$O, and three natural factors, i.e. the rotation rate of earth, sunspots, and El Nino--Southern Oscillation (ENSO) signals, are decomposed into two hierarchies, i.e. more and less than 10-year hierarchies respectively, and then the running $t$-test is used to reanalyse the data before and after filtering with the purpose of investigating the contribution of natural factors to the abrupt climate changes in the last one hundred years. The results show that the GIC \textit{$\delta $}$^{18}$O evolved with a quasi-period of 7--9 years, and the abrupt climate changes in the early 1960s and in the period from the end of the 1970s to the beginning of the 1980s resulted from the joint effect of the two hierarchies, in other words, the two interdecadal abrupt changes of climate in the last one hundred years were global. The interannual variations of ENSO and sunspots were the important triggering factors for the abrupt climate changes in the last one hundred years. At the same time, the method of Information Transfer (IT) is employed to estimate the contributions of ENSO signals and sunspots activities to the abrupt climate changes, and it is found that the contribution of the interannual variation of ENSO signals is relatively large.
Spatiotemporal Urban Land Use Changes in the Changzhutan Region of Hunan Province in China  [PDF]
Bin Quan, Zhikun Xiao, M. J. M. R?mkens, Yijun Bai, Shi Lei
Journal of Geographic Information System (JGIS) , 2013, DOI: 10.4236/jgis.2013.52014
Abstract:

The Changzhutan region in the north-central part of Hunan Province in China has experienced a rapid urbanization in the past few decades that has led to substantial changes in its environment. In 2007, the National Development and Reform Commission of China designated the metropolitan district of Changsha City, Zhuzhou City, and Xiangtan City of this region as the fourth National Demonstration Area where economic development should be implemented in harmony with resource-saving and environment-friendly land use practices. The research, focus of this article will be on quantifying the spatial pattern of urban land use change which not only can provide an assessments and predictions of future environmental effects, but also will serve as a scientific basis for the development of urban sustainability. This paper integrates historical Landsat TM imagery, geographical information system (GIS) and socioeconomic data to determine the spatiotemporal urban land use dynamics and conversion of land use in response to the rapid urbanization of a select group of cities in China from 1990 to 2007. The approach is based on Principle Component Analysis to determine and model the relationship between the socioeconomic factors and land use/cover change (LUCC) for identifying the driving forces. The results indicate that land cover of the Changzhutan region mainly consists of forestland and cropland which accounted for about 93% of the total land area. During the 1990-2007 study period, the urban areas and water bodies increased by 46,297 ha and 775 ha, respectively, while forestland, cropland, and grassland decreased appreciably by 22,580 ha, 21,808 ha, and 5618 ha,

Discussion on the Factors Affecting the Stability of Microgrid Based on Distributed Power Supply  [PDF]
Ye Xu, Zhao-hong Shi, Jin-quan Wang, Peng-fei Hou
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B254
Abstract:

This paper summarizes the advantages of application of micro grid, analyzes the structure of microgrid, and discusses the factors, which are important to the stable operation of micro grid. The factors include the technology of power matching, harmonic suppression and the stability of electronic cascaded systems etc.

Coexistence of strong nematic and superconducting correlations in a two-dimensional Hubbard model
Shi-Quan Su,Thomas A. Maier
Physics , 2011, DOI: 10.1103/PhysRevB.84.220506
Abstract: Using a dynamic cluster quantum Monte Carlo approximation, we study a two-dimensional Hubbard model with a small orthorhombic distortion in the nearest neighbor hopping integrals. We find a large nematic response in the low-frequency single-particle scattering rate which develops with decreasing temperature and doping as the pseudogap region is entered. At the same time, the d-wave superconducting gap function develops an s-wave component and its amplitude becomes anisotropic. The strength of the pairing correlations, however, is found to be unaffected by the strong anisotropy, indicating that d-wave superconductivity can coexist with strong nematicity in the system.
Ethyl 3-methyl-4-oxo-4,5-dihydro-1H-pyrrolo[2,3-d]pyridazine-2-carboxylate
Shi-Quan Chen,Kai Jiang,Shi-Fan Wang
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536809055081
Abstract: The title compound, C10H11N3O3, was synthesized by the reaction of 3,5-bis(ethoxycarbonyl)-2-formyl-4-methyl-1H-pyrrole and hydrazine hydrate. The angle between the pyrrole ring and the pyridazinone ring is 0.93 (9)°. In the crystal, intermolecular N—H...O and N—H...N hydrogen-bond interactions link the molecules into a two-dimensional network.
Male and Female Adult Population Health Status in China: A Cross-Sectional National Survey
Jing Shi, Meina Liu, Qiuju Zhang, Mingshan Lu, Hude Quan
BMC Public Health , 2008, DOI: 10.1186/1471-2458-8-277
Abstract: The Chinese Third National Health Services Survey was conducted in 2003 to collect information about health status and quality of life from randomly selected residents. Of the 193,689 respondents to the survey (response rate 77.8%), 139,831 (69,748 male and 70,083 female) respondents who were 18 years of age or older were analyzed.Among the respondents, fewer males than females rated their overall wellbeing as being poor or very poor (4.8% versus 6.2%), reported illness in the last 2 weeks (14.1% versus 17.4%), presence of physician diagnosed chronic disease (15.0% versus 17.7%) and at least one functional problem in seven items of the quality of life (26.9% versus 32.8%). More males than females were currently smoking (52.4% versus 3.4%) and drank alcohol more than three times per week (16.5% versus 1.1%). Physically inactive rate was similar between males and females (85.8% versus 87.0%). Fewer rural respondents reported chronic disease than urban respondents (13.0% versus 19.9% for males and 15.5% versus 22.8% for females). In all seven items of the quality of life measured, rural respondents reported less problems than urban respondents (26.2% versus 28.7% for males and 32.0% versus 34.7% for females).Males had better health status than females in terms of self-perceived wellbeing, presence of illness, chronic disease, and quality of life. However, smoking and frequent alcohol drinking was more prevalent among males than that among females. In contrast with the social-economic gradient in health commonly found in the literature, the wealthier urban population in China was not found to be healthier than the rural population in terms of physician diagnosed chronic disease.China's population of 1.3 billion accounts for 20% of the world population, making it the most populated country in the world. With rapid economic growth and globalization, Chinese people's lifestyle has been changing dramatically towards being more physically inactive, eating more fast food, and
Geochemical significance of the relative enrichment of pristane and the negative excursion of δ13CPr across the Permian-Triassic Boundary at Meishan, China
Chunjiang Wang,Yimei Liu,Hongxiu Liu,Lei Zhu,Quan Shi
Chinese Science Bulletin , 2005, DOI: 10.1007/BF03182673
Abstract: Changes in the distribution of isoprenoid hydrocarbons and in δ13Ckero or δ13CPr across the section from the Changxing Formation to the lower Yinkeng Formation at Meishan (the GSSP of PTB) are studied, in which a relative enrichment of pristane and a sharp shift in both δ13Ckero and δ13Cmole near the boundary are revealed. A possible mechanism for the abnormal accumulation of pristane near PTB is suggested: Lipids in some marine animals and their metabolites, rich in pristane, can be preserved and accumulate in some suitable depositing facies under certain special conditions, such as the catastrophic death of animals and/or developing of an anoxic water column, and thus the pristane enrichment occurs in the sediment. The occurrences of isoprenoid enrichment and high Pr/Ph ratios have been found in other typical marine anoxic sediments accompanied by mass extinction in various extent during the most important geological periods, such as Late Ordovician, end of Devonian, Early Jurassic and Late Cretaceous. These occurrences support to a certain extent the above mechanism that interprets the genesis of a high Pr/Ph ratio in some typical marine anoxic sediments. The synchronous sharp negative shifts in δ13Cmole, δ13Ckero and δ13Ccarb from Beds 24 to 26 of the Meishan profile indicate that a sudden and strong variation of carbon source in the atmosphere-ocean system occurred during the quick but equable evolution from the end-Permian to Early Triassic, and the coupling between the pristane enrichment and negative shift in δ13Ckero and δ13CPr may well indicate the importance of the release of methane hydrates and marine anoxia in the end-Permian mass extinction.
Identification of acephenanthrylene and aceanthrylene in aerosol and its environmental implication
Quan Shi,TieGuan Wang,NingNing Zhong,ZhiHuan Zhang,YaHe Zhang
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0075-1
Abstract: Acephenanthrylene and aceanthrylene in aromatic fraction of aerosols were identified by means of online hydrogenation gas chromatography mass spectrometry(GCMS). Compared aerosols from various sources, acephenanthrylene and aceanthrylene were ubiquitously present in urban aerosol. High concentration of acephenanthrylene and aceanthrylene were found in agricultural biomass and coal combustion particles. However, it is difficult to detect in exhaust from gasoline and diesel engine, dustfall, waste water, soil, and sediment. Combustion emissions were considered the major source of acephenanthrylene and aceanthrylene, which can be used as a potential molecular marker for the source pollution in urban aerosols.
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