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Search Results: 1 - 10 of 48461 matches for " Yi Zheng "
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A Study on Service Marketing of University Libraries in the New Media Environment  [PDF]
Yi Zheng, Lan Du
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.611016
Abstract: As the technical support and communication platform, new media plays a critical role in the construction and service of digital libraries. Furthermore, it has become an imperative form for libraries to carry out service marketing and promotion, demonstrating the expansion of services in libraries. The article expounds the inevitability of university library service marketing under the new media environment, proposes marketing strategy, and finally enumerates the specific application of various new media technologies in the service marketing of university libraries.
文化漫游与精神家园——当代中国文化散文的公共语境 (Cultural Tours and the Spiritual Home: On Yu Qiuyu and Contemporary Chinese Cultural Essays)
Yi Zheng
PORTAL : Journal of Multidisciplinary International Studies , 2007,
Abstract: The essay explores the public social dimension of the “great cultural essays” as a popular post-socialist genre. It looks into the genre’s emergence and popularity as part of the making of a middleclass taste in contemporary China and its claim to a re-imagined cultural national inheritance. In particular, the discussion focuses on the example of essayist Yu Qiuyu and examines the implications of his successful transformation of an obsolete historical “Culture” into a desirable commodity that offers spiritual home to the aspiring and successful of a “Greater China”.
Review of fluctuational electrodynamics and its applications to radiative momentum, energy and entropy transport
Yi Zheng
Physics , 2014,
Abstract: Quantum and thermal fluctuations of electromagnetic fields, which give rise to Planck's law of blackbody radiation, are also responsible for van der Waals and Casimir forces, as well as near-field radiative energy transfer between objects. Electromagnetic waves transport energy, momentum, and entropy. For classical thermal radiation, the dependence of the above mentioned quantities on the temperature is well-known mainly due to Planck's work. When near-field effects, namely the collective influence of diffraction, interference, and tunneling of waves, become important, Planck's theory is no longer valid. Of momentum, energy, and entropy transfer, the role of near-field effects on momentum transfer between two half-spaces separated by a vacuum gap (van der Waals pressure in the vacuum gap) was first determined by Lifshitz, using Rytov's theory of fluctuational electrodynamics in 1956. Subsequently, Dzyaloshinskii, Lifshitz, and Pitaevskii, employing sophisticated methods from quantum field theory, generalized Lifshitz' result for van der Waals pressure in a vacuum layer to the case of van der Waals pressure in a dissipative layer between two half-spaces. The influence of near-field effects on radiative transfer was appreciated only in the late 1960s and, subsequently, in the last two decades because of the enhancement in radiative transfer due to electromagnetic surface waves. The role played by near-field effects on entropy transfer has not been investigated so far, at least when the temperature distribution is non-uniform.
Analysis of Dual-beam Asymmetrical Torsional Bi-Material Cantilever for Temperature Sensing Applications
Yi Zheng
Physics , 2012,
Abstract: An extremely sensitive temperature measurement MEMS device is developed based on the principle of structural deflection in a bi-material cantilever caused by a difference in thermal expansion coefficients. A dual-beam asymmetrical geometry is used to produce a torsional response from the device. An analytical model is developed to predict the performance and optimize the free parameters of the device. In this work, it is performed to analyze the flexural and torsional eigenfrequencies as well as confirm the theoretical predictions of DC and AC response. Lastly, a procedure is developed to allow fabrication of the device using equipment available in the Columbia University clean room.
Study on Horizontal Relative Diffusion in the Troposphere and Lower Stratosphere
Study on Horizontal Relative Diffusion in theTroposphere and Lower Stratosphere

Zheng Yi,

大气科学进展 , 2000,
Abstract: The behaviour of relative diffusion theory and Gifford’s random-force theory for long-range atmospheric diffusion is examined. When a puff scale is smaller than the Lagrangian length scale, √2KTL, an accelerative relative diffusion region exists, i.e., σy∝ t 3/2. While the puff diffusion enters a two-dimensional turbulence region, in which the diffusion scale is larger than 500 km, or time scale is larger than 1 day, divergence and convergence are main cause of horizontal diffusion. Between the two above-mentioned regimes, diffusion deviation is given by σy = √2KT. The large-scale horizontal relative diffusion parameters were obtained by analyzing the data of radioactive cloud width collected in air nuclear tests. This work is sponsored by the National Natural Science Foundation of China under Grant No. 49505064. The author would like to thank Prof. Chen Jiayi Department of Geophysics of Peking University and Dr. Cai Xiaoming School of Geography and Environmental Sciences of Birmingham University for their helpful discussions.
What Supported the Growth of China’s Air Transport Industry from 1955 to 2011?  [PDF]
Xingwu Zheng, Yi Zhang, Wei Lu
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.61007
Abstract: China’s civil aviation industry experienced an average annual growth rate of over 16% for traffic turnover during 1955-2011. It is important to identify the role of capital and labor inputs as well as total factor productivity (TFP) in China’s civil aviation industry during this period of time. First, the inputs of capital stock and labor as well as the output of traffic turnover in China’s air transport industry are measured. Next, the constrained E-G two-stage estimation of the CD production function is used to calculate the capital and labor elasticities and TFP, which provides the necessary basis for the estimation of the growth sources in China’s air transport industry from 1955 to 2011. The results show that the growth of China’s civil aviation industry has depended on the capital factor input and that TFP has played an increasingly important role. Furthermore, the results also indicate that private sources have been crucial for improving the TFP after the 2002 reform.
Autonomous Inspection Robot for Power Transmission Lines Maintenance While Operating on the Overhead Ground Wires
Zheng Li,Yi Ruan
International Journal of Advanced Robotic Systems , 2011,
Abstract: This paper describes the development of a mobile robot capable of clearing such obstacles as counterweights, anchor clamps, and torsion tower. The mobile robot walks on overhead ground wires in 500KV power tower. Its ultimate purpose is to automate to inspect the defect of power transmission line. The robot with 13 motors is composed of two arms, two wheels, two claws, two wrists, etc. Each arm has 4 degree of freedom. Claws are also mounted on the arms. An embedded computer based on PC/104 is chosen as the core of control system. Visible light and thermal infrared cameras are installed to obtain the video and temperature information, and the communication system is based on wireless LAN TCP/IP protocol. A prototype robot was developed with careful considerations of mobility. The new sensor configuration is used for the claw to grasp the overhead ground wires. The bridge is installed in the torsion tower for the robot easy to cross obstacles. The new posture plan is proposed for obstacles cleaning in the torsion tower. Results of experiments demonstrate that the robot can be applied to execute the navigation and inspection tasks.
Bayesian Probabilistic Framework for Damage Identification of Steel Truss Bridges under Joint Uncertainties
Wei Zheng,Yi Yu
Advances in Civil Engineering , 2013, DOI: 10.1155/2013/307171
Abstract: The vibration-based structural health monitoring has been traditionally implemented through the deterministic approach that relies on a single model to identify model parameters that represent damages. When such approach is applied for truss bridges, truss joints are usually modeled as either simple hinges or rigid connections. The former could lead to model uncertainties due to the discrepancy between physical configurations and their mathematical models, while the latter could induce model parameter uncertainties due to difficulty in obtaining accurate model parameters of complex joint details. This paper is to present a new perspective for addressing uncertainties associated with truss joint configurations in damage identification based on Bayesian probabilistic model updating and model class selection. A new sampling method of the transitional Markov chain Monte Carlo is incorporated with the structure’s finite element model for implementing the approach to damage identification of truss structures. This method can not only draw samples which approximate the updated probability distributions of uncertain model parameters but also provide model evidence that quantify probabilities of uncertain model classes. The proposed probabilistic framework and its applicability for addressing joint uncertainties are illustrated and examined with an application example. Future research directions in this field are discussed. 1. Introduction Steel truss bridges are commonly used in the highway system. Those truss bridges are typically composed of slender steel members connected at truss joints. The truss joints may take various types or configurations. During their long-term operations, steel truss bridges may become deteriorated (such as development of fatigue cracks and corrosions) due to increased volumes of traffic and adverse environment impacts. Such deterioration or damage could pose serious threats to the safe operation of bridges if its development cannot be identified in a timely manner. Researchers have explored various approaches for effectively detecting the development of deterioration or damages of truss structures at their early stages through implementing vibration-based structural health monitoring (SHM), which typically relies on vibration measurements and structural models to identify model parameters that represent extents and locations of damages. Gao et al. [1, 2] had proposed an approach of diagnosis locating vector (DLV) for damage identification of steel truss structures by using distributed computing strategy (DCS). They verified this
An Improved Unscented Particle Filter with Global Sampling Strategy
Yi-zheng Zhao
Journal of Computational Engineering , 2014, DOI: 10.1155/2014/175820
Abstract: Particle filter (PF) has many variations and one of the most popular is the unscented particle filter (UPF). UPF uses the unscented Kalman filter (UKF) to generate particles in the PF framework and has a better performance than the standard PF. However, UPF suffers from its high computation complexity because it has to execute UKF to each particle to obtain proposal distribution. This paper gives an improved UPF aiming at reducing the computation complexity of the algorithm. In comparison to the standard UPF, the new strategy generates proposal distribution from the mean and covariance value of the whole particles instead of from each particle. Thus the improved algorithm utilizes the characteristics of the whole particles and only needs to perform UKF algorithm once to get the proposal distribution at each time step. Experimental results show that, compared to standard UPF, the improved algorithm reduces the time consumption greatly almost without performance degradation. 1. Introduction Nonlinear and non-Gaussian filtering has a wide range of applications in many fields [1–3]. Among the many methods that have been proposed in the literature for these applications, particle filter (PF) has become one of the most popular. For decades PF has been applied to a variety of problems, such as computer vision, signal processing [4], target tracking [5], and financial pricing [6]. However when designing a PF a major problem is to choose a proper proposal distribution of the particles. Due to the fact that the particles are drawn from this distribution, and the weight values of particles are also related to this distribution, the performance of a PF is strongly influenced by the choice of the proposal distribution. To design better proposal distributions, several techniques based on linearization have been proposed. In one method, an extended Kalman filter (EKF) is used to generate the proposal distribution, and this is known as extended Kalman PF (EKPF). However, the linearization operation in EKPF introduces modeling errors, which can yield large estimation errors if the system is highly nonlinear [7]. To overcome this problem, a more accurate PF was proposed using unscented Kalman filter (UKF) to generate the proposal distribution [8]. The UKF can accurately compute the mean and covariance of nonlinear systems up to the second order of the Taylor series expansions. This type of particle filter using UKF to generate proposal distribution is known as the unscented particle filter (UPF). The UKF produces proposal distributions that exhibit a larger support
A Green's function formalism of energy and momentum transfer in fluctuational electrodynamics
Arvind Narayanaswamy,Yi Zheng
Physics , 2013, DOI: 10.1016/j.jqsrt.2013.01.002
Abstract: Radiative energy and momentum transfer due to fluctuations of electromagnetic fields arising due to temperature difference between objects is described in terms of the cross-spectral densities of the electromagnetic fields. We derive relations between thermal non-equilibrium contributions to energy and momentum transfer and surface integrals of tangential components of the dyadic Green's functions of the vector Helmholtz equation. The expressions derived here are applicable to objects of arbitrary shapes, dielectric functions, as well as magnetic permeabilities. For the case of radiative transfer, we derive expressions for the generalized transmissivity and generalized conductance that are shown to obey reciprocity and agree with theory of black body radiative transfer in the appropriate limit.
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