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Search Results: 1 - 10 of 109849 matches for " Ning Zhang "
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Comparative Review of QoS-Aware On-Demand Routing in Ad Hoc Wireless Networks  [PDF]
Ning Zhang, Alagan Anpalagan
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.24038
Abstract: In this paper, a representative set of QoS models and QoS-aware on-demand routing protocols are reviewed with emphasis on their ability to support QoS in mobile ad-hoc networks (MANETs) possibly used in WSNs. In particular IntServ, DiffServ, FQMM, and SWAN QoS models are reviewed followed by different QoS-aware on-demand routings in MANETs from different perspectives such as the challenges, classifications, algorithmic aspects in QoS provisions. Tradeoff in providing support to real time (RT) and best effort (BE) traffic is highlighted. Finally, a detailed and comprehensive comparison table is provided for better understanding of QoS provision in MANETs.
Simulation and Analysis on Winding Deformation of a Power Transformer in Current Transformer Connecting Manner  [PDF]
Lanqin Geng, Ning Zhang
Journal of Power and Energy Engineering (JPEE) , 2015, DOI: 10.4236/jpee.2015.34001
Abstract:

Transformer winding deformation?is one of the main types of transformer faults. To check if a power transformer is being under winding deformation, the transformer can be connected in a current transformer during its testing. A transformer winding simulating model is set up under this connecting manner. Then the simulation has been performed with?current source which is the frequency sweep power. The simulation results show that the winding deformation can be reflected effectively with current source method.?This method lays the foundation for the realization of on-line monitoring and diagnosis of the transformer neutral directly grounded side winding.

Spectral Element Simulation of Rotating Particle in Viscous Flow  [PDF]
Don Liu, Ning Zhang
Journal of Applied Mathematics and Physics (JAMP) , 2016, DOI: 10.4236/jamp.2016.47132
Abstract:

Spectral element methods (SEM) are superior to general finite element methods (FEM) in achieving high order accuracy through p-type refinement. Owing to orthogonal polynomials in both expansion and test functions, the discretization errors in SEM could be reduced exponentially to machine zero so that the spectral convergence rate can be achieved. Inherited the advantage of FEM, SEM can enhance resolution via both h-type and p-type mesh-refinement. A penalty method was utilized to compute force fields in particulate flows involving freely moving rigid particles. Results were analyzed and comparisons were made; therefore, this penalty-implemented SEM was proven to be a viable method for two-phase flow problems.

Alcohol Taxes and Birth Outcomes
Ning Zhang
International Journal of Environmental Research and Public Health , 2010, DOI: 10.3390/ijerph7051901
Abstract: This study examines the relationships between alcohol taxation, drinking during pregnancy, and infant health. Merged data from the US Natality Detailed Files, as well as the Behavioral Risk Factor Surveillance System (1985–2002), data regarding state taxes on beer, wine, and liquor, a state- and year-fixed-effect reduced-form regression were used. Results indicate that a one-cent ($0.01) increase in beer taxes decreased the incidence of low-birth-weight by about 1–2 percentage points. The binge drinking participation tax elasticity is ?2.5 for beer and wine taxes and ?9 for liquor taxes. These results demonstrate the potential intergenerational impact of increasing alcohol taxes.
The Picard group of the loop space of the Riemann sphere
Ning Zhang
Mathematics , 2006,
Abstract: The loop space of the Riemann sphere consisting of all C^k or Sobolev W^{k,p} maps from the circle S^1 to the sphere is an infinite dimensional complex manifold. We compute the Picard group of holomorphic line bundles on this loop space as an infinite dimensional complex Lie group with Lie algebra the first Dolbeault group. The group of Mobius transformations G and its loop group LG act on this loop space. We prove that an element of the Picard group is LG-fixed if it is G-fixed; thus completely answer the question by Millson and Zombro about G-equivariant projective embedding of the loop space of the Riemann sphere.
A class of holomorphic self-maps of the loop space of P^n
Ning Zhang
Mathematics , 2014,
Abstract: The loop space LP^n of the complex projective space P^n consisting of all C^k or Sobolev W^{k,p} maps S^1 \to P^n is an infinite dimensional complex manifold. We identify a class of holomorphic self-maps of LP^n, including all automorphisms.
Holomorphic line bundles on the loop space of the Riemann sphere
Ning Zhang
Mathematics , 2002,
Abstract: The loop space LP_1 of the Riemann sphere consisting of all C^k or Sobolev W^{k,p} maps from the circle S^1 to P_1 is an infinite dimensional complex manifold. The loop group LPGL(2,C) acts on LP_1. We prove that the group of LPGL(2,C) invariant holomorphic line bundles on LP_1 is isomorphic to an infinite dimensional Lie group. Further, we prove that the space of holomorphic sections of these bundles is finite dimensional, and compute the dimension for a generic bundle.
Simulation of Snow Drift and the Effects of Snow Particles on Wind
Jie Zhang,Ning Huang
Modelling and Simulation in Engineering , 2008, DOI: 10.1155/2008/408075
Abstract: Coupled equations between wind and saltating particles are presented for a stable wind blowing over an infinite plane bed and the equations are solved for a simplified particle-bed impact process. The calculated results show that the saltating snow particles strongly affect the velocity distribution of the wind, causing a deviation from a logarithmically distributed wind velocity profile. The average height and length of saltating snow particle trajectories exponentially increase as the friction velocity increases; the ejected snow number flux and the streamwise snow transport rate also increase as the friction velocity increases.
Alcohol Policy, Social Context, and Infant Health:?The Impact of Minimum Legal Drinking Age
Ning Zhang,Eric Caine
International Journal of Environmental Research and Public Health , 2011, DOI: 10.3390/ijerph8093796
Abstract: Objective: The minimum legal drinking age (MLDA) was increased in the U.S. in the late 1980s in an effort to reduce intoxication-associated injuries, especially those related to motor vehicle accidents. This paper explores distal (secondary) effects of changing MLDA on indices of infant health, and whether changes in drinking behaviors or birth composition contributed to these effects. Methods: State- and year-fixed-effects models are used to analyze the relationship between MLDA, drinking behaviors, and birth outcomes. We studied the effects of different MLDA (age 18, 19, 20, or 21 years) when potential mothers were 14 years old by merging two population-based datasets, the Natality Detailed Files and the Behavioral Risk Factor Surveillance System between 1985 and 2002. Results: A MLDA of 18 years old (when potential mothers were 14 years old) increased the prevalence of low birth weight, low Apgar scores, and premature births. Effects were stronger among children born to black women compared with white women. Moreover, a younger MLDA was associated with an increasing proportion of very young and high school dropouts for black women. Furthermore, older MLDA laws at age 14 years decreased the prevalence of binge drinking among black women . Conclusions: Increasing the MLDA had longer term, distal impacts beyond the initially intended outcomes, specifically on birth outcomes (particularly among infants born to black women) as well as school drop-outs and binge drinking patterns among black young females. The older MLDA, intended initially to reduce problematic drinking behaviors, appeared to alter broader social contexts that influenced young women during their early childbearing years.
Random Failure Number and Replacement Cycle
设备故障次数与经济更新时间

ZHANG Ning,
张宁

系统工程理论与实践 , 1999,
Abstract: In the paper, the stochastic process of the failure number is studied in following the line of modelling the dynamic equation for the failure number on the basis of the distribution of the failure time. A mathematical programming model is further proposed by minimzing the total cost for the replacement cycle. An example is used to illustrate its application of the approach.
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