The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is...The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is proposed for the differential unitary space-time modulation （DUSTM） system. In the first step, the data sequence is estimated by conventional unitary space-time demodulation （DUSTD） and differentially encoded again to produce an initial estimate of the transmitted symbol stream. In the second step, the initial estimate of the symbol stream is utilized to initialize an expectation maximization （EM）-based iterative detector. In each iteration, the most recent detected symbol stream is employed to estimate the channel, which is then used to implement coherent sequence detection to refine the symbol stream. Simulation results show that the proposed detection scheme performs much better than the conventional DUSTD after several iterations.展开更多
The audit expectation gap is critical to the auditing profession because the greater the unfulfilled expectations from the public, the lower is the credibility, earning potential and prestige associated with the work...The audit expectation gap is critical to the auditing profession because the greater the unfulfilled expectations from the public, the lower is the credibility, earning potential and prestige associated with the work of auditors. The aim of this paper is to uncover the causes of an audit expectation gap. It is revealed that the existence of an audit expectation gap is due to complicated nature of an audit function; conflicting role of auditors; retrospective evaluation of auditors＇ performance; time lag in responding to changing expectation; and self-regulation process of the auditing profession.展开更多
The numerical characteristics of fuzzy numbers include the optimistic value, pessimistic value, expected value, and the variance. We mainly provide the calculation formulae of several numerical characteristics of fuzz...The numerical characteristics of fuzzy numbers include the optimistic value, pessimistic value, expected value, and the variance. We mainly provide the calculation formulae of several numerical characteristics of fuzzy numbers based on credibility measure. Especially, the variance of symmetric fuzzy numbers is formulated, and a super bound for the variance of fuzzy numbers is presented. Meanwhile, some conclusions relative to credibility measure, optimistic and pessimistic values are also given.展开更多
Fly ash has congregated considerable attention as a potential reinforcement for aluminum matrix composites(AMCs)to enhance selective properties and reduce the cost of fabrication.However,poor machinability of such AMC...Fly ash has congregated considerable attention as a potential reinforcement for aluminum matrix composites(AMCs)to enhance selective properties and reduce the cost of fabrication.However,poor machinability of such AMCs limits their application.The present study focuses on the preparation of cenosphere fly ash reinforced Al6061alloys by compo casting method.X-ray diffraction analysis of the prepared AMCs exposes the presence of cenosphere particles without any formation of other intermetallic compounds.In this study,electrical discharge machining(EDM)was engaged to examine the machinability of the prepared metal matrix composite(MMCs).The measured performance characteristics for the various combinations of input process parameters were considered to be MRR,EWR and SR.Face centered central composite design(CCD)of response surface method(RSM)was employed to design the number of experimental trials required and a hybrid approach of grey-based response surface methodology(GRSM)was imposed for predicting the optimal combination of processing parameter in EDM process.Generous improvement was observed in the performance characteristics obtained by employing both the optimal setting of machining parameters.The optical3D surface profile graphs of the ED machined surface also revealed the improvement in surface quality and texture employing the optimal processing conditions proposed by hybrid GRSM approach.展开更多
We represent the exponential moment of the Brownian functionals under a nonlinear expectation according to the solution to a backward stochastic differential equation.As an application,we establish a large deviation p...We represent the exponential moment of the Brownian functionals under a nonlinear expectation according to the solution to a backward stochastic differential equation.As an application,we establish a large deviation principle of the Freidlin and Wentzell type under the corresponding nonlinear probability for diffusion processes with a small diffusion coefficient.展开更多
基金The National Natural Science Foundation of China(No60572072,60496311)the National High Technology Research and Development Program of China (863Program) (No2006AA01Z264)+1 种基金the National Basic Research Program of China (973Program) (No2007CB310603)the PhD Programs Foundation of Ministry of Educa-tion of China (No20060286016)
文摘The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is proposed for the differential unitary space-time modulation （DUSTM） system. In the first step, the data sequence is estimated by conventional unitary space-time demodulation （DUSTD） and differentially encoded again to produce an initial estimate of the transmitted symbol stream. In the second step, the initial estimate of the symbol stream is utilized to initialize an expectation maximization （EM）-based iterative detector. In each iteration, the most recent detected symbol stream is employed to estimate the channel, which is then used to implement coherent sequence detection to refine the symbol stream. Simulation results show that the proposed detection scheme performs much better than the conventional DUSTD after several iterations.
文摘The audit expectation gap is critical to the auditing profession because the greater the unfulfilled expectations from the public, the lower is the credibility, earning potential and prestige associated with the work of auditors. The aim of this paper is to uncover the causes of an audit expectation gap. It is revealed that the existence of an audit expectation gap is due to complicated nature of an audit function; conflicting role of auditors; retrospective evaluation of auditors＇ performance; time lag in responding to changing expectation; and self-regulation process of the auditing profession.
文摘The numerical characteristics of fuzzy numbers include the optimistic value, pessimistic value, expected value, and the variance. We mainly provide the calculation formulae of several numerical characteristics of fuzzy numbers based on credibility measure. Especially, the variance of symmetric fuzzy numbers is formulated, and a super bound for the variance of fuzzy numbers is presented. Meanwhile, some conclusions relative to credibility measure, optimistic and pessimistic values are also given.
文摘Fly ash has congregated considerable attention as a potential reinforcement for aluminum matrix composites(AMCs)to enhance selective properties and reduce the cost of fabrication.However,poor machinability of such AMCs limits their application.The present study focuses on the preparation of cenosphere fly ash reinforced Al6061alloys by compo casting method.X-ray diffraction analysis of the prepared AMCs exposes the presence of cenosphere particles without any formation of other intermetallic compounds.In this study,electrical discharge machining(EDM)was engaged to examine the machinability of the prepared metal matrix composite(MMCs).The measured performance characteristics for the various combinations of input process parameters were considered to be MRR,EWR and SR.Face centered central composite design(CCD)of response surface method(RSM)was employed to design the number of experimental trials required and a hybrid approach of grey-based response surface methodology(GRSM)was imposed for predicting the optimal combination of processing parameter in EDM process.Generous improvement was observed in the performance characteristics obtained by employing both the optimal setting of machining parameters.The optical3D surface profile graphs of the ED machined surface also revealed the improvement in surface quality and texture employing the optimal processing conditions proposed by hybrid GRSM approach.
基金supported by National Natural Science Foundation of China (Grant No.10921101)WCU program of the Korea Science and Engineering Foundation (Grant No. R31-20007)National Science Foundation of US (Grant No. DMS-0906907)
文摘We represent the exponential moment of the Brownian functionals under a nonlinear expectation according to the solution to a backward stochastic differential equation.As an application,we establish a large deviation principle of the Freidlin and Wentzell type under the corresponding nonlinear probability for diffusion processes with a small diffusion coefficient.
