arXiv subjects

Yong Wang

Publications and source records attributed to Yong Wang.

At least 649 records · Page 36Linked to original sources

arXiv2013

A Formal Model of QoS-Aware Web Service Orchestration Engine

QoS-aware applications can satisfy not only the functional requirements of the customers, but also the QoS requirements. QoS-aware Web Service orchestration translates the QoS requirements of the customers into those of its component Web Services. In a system viewpoint, we discuss issues on QoS-aware Web Service orchestration and design a typical QoS-aware Web Service orchestration engine called QoS-WSOE. More importantly, we establish a formal model of QoS-WSOE based on actor systems theory. Within the formal model, we use a three-layered pyramidal structure to capture the requirements of the customers with a concept named QoS-Aware WSO Service, characteristics of QoS-WSOE with a concept named QoS-Aware WSO System, and structures and behaviors of QoS-WSOE with a concept named QoS-Aware WSO Behavior. Conclusions showing that a system with QoS-Aware WSO Behavior is a QoS-Aware WSO System and further can provide QoS-Aware WSO Service are drawn.

cs.SE↗

arXiv2013

A Survey on Formal Methods for Web Service Composition

Web Service Composition creates new composite Web Services from existing Web Services which embodies the added values of Web Service technology and is a key technology to solve cross-organizational business process integrations. We do a survey on formal methods for Web Service Composition in the following way. Through analyses of Web Service Composition, we establish a reference model called RM-WSComposition to capture elements of Web Service Composition. Based on the RM-WSComposition, issues on formalization for Web Service Composition are pointed out and state-of-the-art on formal methods for Web Service Composition is introduced. Finally, we point out the trends on this topic. For convenience, we use an example called BuyingBooks to illustrate the concepts and mechanisms in Web Service Composition.

cs.SE↗

arXiv2013

Formal Model of Web Service Composition: An Actor-Based Approach to Unifying Orchestration and Choreography

Web Service Composition creates new composite Web Services from the collection of existing ones to be composed further and embodies the added values and potential usages of Web Services. Web Service Composition includes two aspects: Web Service orchestration denoting a workflow-like composition pattern and Web Service choreography which represents an aggregate composition pattern. There were only a few works which give orchestration and choreography a relationship. In this paper, we introduce an architecture of Web Service Composition runtime which establishes a natural relationship between orchestration and choreography through a deep analysis of the two ones. Then we use an actor-based approach to design a language called AB-WSCL to support such an architecture. To give AB-WSCL a firmly theoretic foundation, we establish the formal semantics of AB-WSCL based on concurrent rewriting theory for actors. Conclusions that well defined relationships exist among the components of AB-WSCL using a notation of Compositionality is drawn based on semantics analysis. Our works can be bases of a modeling language, simulation tools, verification tools of Web Service Composition at design time, and also a Web Service Composition runtime with correctness analysis support itself.

cs.SE↗

arXiv2013

An Axiomatization for Quantum Processes to Unifying Quantum and Classical Computing

We establish an axiomatization for quantum processes, which is a quantum generalization of process algebra ACP (Algebra of Communicating Processes). We use the framework of a quantum process configuration $\langle p, \varrho\rangle$, but we treat it as two relative independent part: the structural part $p$ and the quantum part $\varrho$, because the establishment of a sound and complete theory is dependent on the structural properties of the structural part $p$. We let the quantum part $\varrho$ be the outcomes of execution of $p$ to examine and observe the function of the basic theory of quantum mechanics. We establish not only a strong bisimularity for quantum processes, but also a weak bisimularity to model the silent step and abstract internal computations in quantum processes. The relationship between quantum bisimularity and classical bisimularity is established, which makes an axiomatization of quantum processes possible. An axiomatization for quantum processes called qACP is designed, which involves not only quantum information, but also classical information and unifies quantum computing and classical computing. qACP can be used easily and widely for verification of most quantum communication protocols.

cs.LO↗

arXiv2013

Demonstration of surface transport in a hybrid Bi2Se3/Bi2Te3 heterostructure

In spite of much work on topological insulators (TIs), systematic experiments for TI/TI heterostructures remain absent. We grow a high quality heterostructure containing single quintuple layer (QL) of Bi2Se3 on 19 QLs of Bi2Te3 and compare its transport properties with 20 QLs Bi2Se3 and 20 QLs Bi2Te3. All three films are grown on insulating sapphire (0001) substrates by molecular beam epitaxy (MBE). In situ angle-resolved photoemission spectroscopy (ARPES) provides direct evidence that the surface state of 1 QL Bi2Se3 / 19 QLs Bi2Te3 heterostructure is similar to the surface state of the 20 QLs Bi2Se3 and different with that of the 20 QLs Bi2Te3. In ex situ transport measurements, the observed linear magnetoresistance (MR) and weak antilocalization (WAL) of the hybrid heterostructure are similar to that of the pure Bi2Se3 film and not the Bi2Te3 film. This suggests that the single Bi2Se3 QL layer on top of 19 QLs Bi2Te3 dominates its transport properties.

cond-mat.mes-hall↗

arXiv2013

Polarization Controlled Ohmic to Schottky Transition at a Metal/Doped Ferroelectric Interface

Ferroelectric polar displacements have recently been observed in conducting electron-doped BaTiO3. The co-existence of a ferroelectric phase and conductivity opens the door to new functionalities which may provide a unique route for novel device applications. Using first-principles methods and electrostatic modeling we explore the effect that the switchable polarization of electron-doped BaTiO3 (n-BaTiO3) has on the electronic properties of the SrRuO3/n-BaTiO3 (001) interface. Ferroelectric polarization controls the accumulation or depletion of electron charge at the interface, and the associated bending of the n-BTO conduction band determines the transport regime across the interface. The interface exhibits a Schottky tunnel barrier for one polarization orientation, whereas an Ohmic contact is present for the opposite polarization orientation, leading to a large change in interface resistance associated with polarization reversal. Calculations reveal a large (five orders of magnitude) change in the interface resistance as a result of polarization switching.

cond-mat.mtrl-sci↗

arXiv2013

Momentum-Resolved Electronic Relaxation Dynamics in D-wave Superconductors

Motivated by recent development in time-resolved angle-resolved photoemission spectroscopy (trARPES) for d-wave superconductors, we analyze the non-equilibrium relaxation dynamics of the laser pulse excited sample within the scenario of two-temperature model. It is shown that the main features reported in the trARPES technique may be understood within this phenomenological picture. The momentum dependence of the excited quasiparticle density and the relaxation rate is associated with the dynamics of the nodal d-wave superconducting gap, and the fluence dependence of the relaxation rate is related to the recombination process of quasiparticles into Cooper pairs.

cond-mat.supr-con↗

arXiv2013

Continuous Double Auction Mechanism and Bidding Strategies in Cloud Computing Markets

Cloud computing has been an emerging model which aims at allowing customers to utilize computing resources hosted by Cloud Service Providers (CSPs). More and more consumers rely on CSPs to supply computing and storage service on the one hand, and CSPs try to attract consumers on favorable terms on the other. In such competitive cloud computing markets, pricing policies are critical to market efficiency. While CSPs often publish their prices and charge users according to the amount of resources they consume, auction mechanism is rarely applied. In fact a feasible auction mechanism is the most effective method for allocation of resources, especially double auction is more efficient and flexible for it enables buyers and sellers to enter bids and offers simultaneously. In this paper we bring up an electronic auction platform for cloud, and a cloud Continuous Double Auction (CDA) mechanism is formulated to match orders and facilitate trading based on the platform. Some evaluating criteria are defined to analyze the efficiency of markets and strategies. Furthermore, the selection of bidding strategies for the auction plays a very important role for each player to maximize its own profit, so we developed a novel bidding strategy for cloud CDA, BH-strategy, which is a two-stage game bidding strategy. At last we designed three simulation scenarios to compare the performance of our strategy with other dominating bidding strategies and proved that BH-strategy has better performance on surpluses, successful transactions and market efficiency. In addition, we discussed that our cloud CDA mechanism is feasible for cloud computing resource allocation.

cs.DC↗

arXiv2013

Influence of Quantum and Thermal Noise on Spin-Torque-Driven Magnetization Switching

We apply a recently developed quantum theory of spin transfer torque to study the effect of the quantum noise in spin transfer process on the magnetization switching in spin-torque-driven devices. The quantum noise induces considerable fluctuation of the switching time at zero temperature. By including the thermal noise, the temperature dependence of the expectation value and standard deviation of the switching time are obtained in the Monte Carlo simulations, and the results are fitted to an effective first passage model. We expect that the predictions here are observable in the single-shot measurement experiments.

cond-mat.mes-hall↗

arXiv2013

Overlapping Community Detection in Complex Networks using Symmetric Binary Matrix Factorization

Discovering overlapping community structures is a crucial step to understanding the structure and dynamics of many networks. In this paper we develop a symmetric binary matrix factorization model (SBMF) to identify overlapping communities. Our model allows us not only to assign community memberships explicitly to nodes, but also to distinguish outliers from overlapping nodes. In addition, we propose a modified partition density to evaluate the quality of community structures. We use this to determine the most appropriate number of communities. We evaluate our methods using both synthetic benchmarks and real world networks, demonstrating the effectiveness of our approach.

cs.SI↗

arXiv2013

Dirac Operators with Torsion and the Noncommutative Residue for Manifolds with Boundary

In this paper, we get the Kastler-Kalau-Walze theorem associated to Dirac operators with torsion on compact manifolds with boundary. We give two kinds of operator-theoretic explanations of the gravitational action in the case of 4-dimensional compact manifolds with flat boundary. Furthermore, we get the Kastler-Kalau-Walze type theorem for four dimensional complex manifolds associated with nonminimal operators.

math-ph↗

arXiv2013

A Quantum Approach of Meso-Magnet Dynamics with Spin Transfer Torque

We present a theory of magnetization dynamics driven by spin-polarized current in terms of the quantum master equation. In the spin coherent state representation, the master equation becomes a Fokker-Planck equation, which naturally includes the spin transfer and quantum fluctuation. The current electron scattering state is correlated to the magnet quantum states, giving rise to quantum correction to the electron transport properties in the usual semiclassical theory. In the large spin limit, the magnetization dynamics is shown to obey the Hamilton-Jacobi equation or the Hamiltonian canonical equations.

cond-mat.mes-hall↗

arXiv2013

Noncommutative Residue and Dirac operators for Manifolds with the Conformal Robertson-Walker metric

In this paper, we prove a Kastler-Kalau-Walze type theorem for 4-dimensional and 6-dimensional spin manifolds with boundary associated with the conformal Robertson-Walker metric. And we give two kinds of operator theoretic explanations of the gravitational action for boundary in the case of 4-dimensional manifolds with flat boundary. In particular, for 6-dimensional spin manifolds with boundary with the conformal Robertson-Walker metric, we obtain the noncommutative residue of the composition of $π^+D^{-1}$ and $π^+D^{-3}$ is proportional to the Einstein-Hilbert action for manifolds with boundary.

math.DG↗

arXiv2013

Layer Antiferromagnetic State in Bilayer Graphene : A First-Principle Investigation

The ground state of bilayer graphene is investigated by the density functional calculations with local spin density approximation. We find a ground state with layer antiferromagnetic ordering, which has been suggested by former studies based on simplified model. The calculations prove that the layer antiferromagnetic state (LAF) is stable even if the remote hopping and nonlocal Coulomb interaction are included. The gap of the LAF state is about 1.8 meV, comparable to the experimental value. The surface magnetism in BLG is of the order of $10^{-2} μ_B /nm^2 $.

cond-mat.mes-hall↗

arXiv2012

Global well-posedness of the compressible bipolar Euler-Maxwell system in R^3

We first construct the global unique solution by assuming that the initial data is small in the H^3 norm but its higher order derivatives could be large. If further the initial data belongs to \Dot{H}^{-s} (0\le s<3/2) or \dot{B}_{2,\infty}^{-s} (0< s\le3/2), we obtain the various decay rates of the solution and its higher order derivatives. As an immediate byproduct, the L^p-L^2 (1\le p\le 2) type of the decay rates follow without requiring the smallness for L^p norm of initial data. In particular, the decay rate for the difference of densities could reach to (1+t)^{-13/4} in L^2 norm.

math.AP↗

arXiv2012

High pressure effect on structure, electronic structure and thermoelectric properties of MoS$_2$

We systematically study the effect of high pressure on the structure, electronic structure and transport properties of 2H-MoS$_2$, based on first-principles density functional calculations and the Boltzmann transport theory. Our calculation shows a vanishing anisotropy in the rate of structural change at around 25 GPa, in agreement with the experimental data. A conversion from van der Waals(vdW) to covalent-like bonding is seen. Concurrently, a transition from semiconductor to metal occurs at 25 GPa from band structure calculation. Our transport calculations also find pressure-enhanced electrical conductivities and significant values of the thermoelectric figure of merit over a wide temperature range. Our study supplies a new route to improve the thermoelectric performance of MoS$_2$ and of other transition metal dichalcogenides by applying hydrostatic pressure.

cond-mat.mtrl-sci↗

arXiv2012

The well-posedness of the compressible non-isentropic Euler-Maxwell system in R^3

We first construct the global unique solution by assuming that the initial data is small in the $H^3$ norm but the higher order derivatives could be large. If further the initial data belongs to $\Dot{H}^{-s}$ ($0\le s<3/2$) or $\dot{B}_{2,\infty}^{-s}$ ($0< s\le3/2$), we obtain the various decay rates of the solution and its higher order derivatives. In particular, the decay rates of the density and temperature of electron could reach to $(1+t)^{-13/4}$ in $L^2$ norm.

math.AP↗

arXiv2012

Optimal Control of Stochastic Magnetization Dynamics by Spin Current

Fluctuation-induced stochastic magnetization dynamics plays an important role in magnetic recording and writing. Here we propose that the magnetization dynamics can be optimally controlled by the spin current to minimize or maximize the Freidlin-Wentzell action functional of the system hence to increase or decrease the happening probability of the rare event. We apply this method to study thermal-driven magnetization switching problem and to demonstrate the advantage of the optimal control strategy.

cond-mat.mes-hall↗