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Search Results: 1 - 10 of 124735 matches for " Pei Wang "
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The Experimental Techniques in Ian McEwan’s Atonement  [PDF]
Jie Han, Pei Wang
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.36024
Abstract: Ian McEwan, together with Martin Amis, is now the best-known and controversial contemporary British novelist. Atonement is regarded as the best of McEwan books and is shortlisted for the Booker Prize. It displays features of modernism and postmodernism, with the application of stream of consciousness, multiple voices, montage and flashbacks, becoming increasingly experimental in form.
Research on Blanket Jamming to Beidou Navigation Signals Based on BOC Modulation  [PDF]
Pei Wang, Xiaochun Lu, Rui Wang
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2016, DOI: 10.4236/ijcns.2016.95012
Abstract: Aiming at the issue of influence of blanket jamming on performances of Beidou navigation signals, through studying Beidou signals based on the BOC modulation technology, establishing a blanket jamming mathematical model, and performing modeling and simulation on multiple jamming technologies, to attain the jamming curves of time domains and frequency domains of Beidou signals, and the correlation curve of the signal-to-jamming rate and the bit error rate under blanket jamming, and thus realizing evaluation on the jamming performance.
Formalization of Evidence: A Comparative Study
Pei Wang
Journal of Artificial General Intelligence , 2009, DOI: 10.2478/v10229-011-0003-7
Abstract: This article analyzes and compares several approaches of formalizing the notion of evidence in the context of general-purpose reasoning system. In each of these approaches, the notion of evidence is defined, and the evidence-based degree of belief is represented by a binary value, a number (such as a probability), or two numbers (such as an interval). The binary approaches provide simple ways to represent conclusive evidence, but cannot properly handle inconclusive evidence. The one-number approaches naturally represent inconclusive evidence as a degree of belief, but lack the information needed to revise this degree. It is argued that for systems opening to new evidence, each belief should at least have two numbers attached to indicate its evidential support. A few such approaches are discussed, including the approach used in NARS, which is designed according to the considerations of general-purpose intelligent systems, and provides novel solutions to several traditional problems on evidence.
Editorial: What Makes JAGI Special
Pei Wang
Journal of Artificial General Intelligence , 2009, DOI: 10.2478/v10229-011-0001-9
Solving real time evolution problems by constructing excitation operators
Pei Wang
AIP Advances , 2012, DOI: 10.1063/1.3701702
Abstract: In this paper we study the time evolution of an observable in the interacting fermion systems driven out of equilibrium. We present a method for solving the Heisenberg equations of motion by constructing excitation operators which are defined as the operators A satisfying [ H , A ] =λ A . It is demonstrated how an excitation operator and its excitation energy λ can be calculated. By an appropriate supposition of the form of A we turn the problem into the one of diagonalizing a series of matrices whose dimension depends linearly on the size of the system. We perform this method to calculate the evolution of the creation operator in a toy model Hamiltonian which is inspired by the Hubbard model and the nonequilibrium current through the single impurity Anderson model. This method is beyond the traditional perturbation theory in Keldysh-Green's function formalism, because the excitation energy λ is modified by the interaction and it will appear in the exponent in the function of time.
A Suggestion for Modification of Vafa-Witten Theory
Pei Wang
Physics , 1995, DOI: 10.1016/0370-2693(96)00363-2
Abstract: Using the Mathai-Quillen formalism we reexamine the twisted N=4 supersymmetric model of Vafa-Witten theory. Smooth out the relation between the supersymmetric action and the path integral representation of the Thom class.
The breakdown of the zeroth law of thermodynamics and the definition of temperature in small quantum systems
Pei Wang
Physics , 2012,
Abstract: We study two small quantum systems coupled to the same reservoir which is in thermal equilibrium. By studying the particle density and the energy density in the two systems before and after they contact each other, we find that the two systems are not in thermal equilibrium with each other. Our result shows that the zeroth law of thermodynamics is broken in small quantum systems at low temperatures. Therefore, the traditional way of defining temperature fails due to the breakdown of the transitive relation of thermal equilibrium. Then we show a different way of defining temperature by attaching an auxiliary site, which plays the role of a thermometer, to the small quantum system.
Local temperature and chemical potential inside a mesoscopic device driven out of equilibrium
Pei Wang
Physics , 2011, DOI: 10.1088/1742-5468/2011/09/P09029
Abstract: In this paper we introduce a method of calculating the local temperature and chemical potential inside a mesoscopic device out of equilibrium. We show how to check the conditions of local thermal equilibrium as the whole system is out of equilibrium. Especially we study the onsite chemical potentials inside a chain coupled to two reservoirs at a finite voltage bias. In the presence of disorder we observe a large fluctuation in onsite chemical potentials, which can be suppressed by the electron-electron interaction. By taking average with respect to the configurations of disorder, we recover the classical picture where the voltage drops monotonously through the resistance wire. We prove the existence of local intensive variables in a mesoscopic device which is in equilibrium or not far from equilibrium.
Decoherence of the two-level system coupled to a fermionic reservoir and the information transfer from it to the environment
Pei Wang
Physics , 2010,
Abstract: We study the evolution of reduced density matrix of an impurity coupled to a Fermi sea after the coupling is switched on at time $t=0$. We find the non-diagonal elements of the reduced density matrix decay exponentially, and the decay constant is the impurity level width $\Gamma$. And we study the information transfer rate between the impurity and the Fermi sea, which also decays exponentially. And the decay constant is $k\Gamma$ with $k=2\sim 4$. Our results reveal the relation between information transfer rate and decoherence rate.
The excitation operator approach to non-Markovian dynamics of quantum impurity models in the Kondo regime
Pei Wang
Physics , 2012, DOI: 10.1140/epjb/e2013-40702-2
Abstract: We present a numerical method for studying the real time dynamics of a small interacting quantum system coupled to an infinite fermionic reservoir. By building an orthonormal basis in the operator space, we turn the Heisenberg equation of motion into a system of linear differential equations, which is then solved iteratively by constructing excitation operators. The application of our method depends on a layer structure in the operator space, which help us to turn an infinite linear system into a series of small systems. We apply the method to investigate the decoherence dynamics of quantum impurity models in the Kondo regime with a non-Markovian reservoir. Taking full account of environmental back-actions and electron-electron interactions, we find that the coexistence of the Kondo correlation and a non-Markovian reservoir induces coherence ringings, which will be suppressed by either driving the system away from the particle-hole symmetric point or changing the reservoir into a Markovian one.
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