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Uniformly Most Powerful Invariant Test and Its Application
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作者 张双林 沙秋英 周文海 《Northeastern Mathematical Journal》 CSCD 2001年第1期13-20,共8页
The authors consider the uniformly most powerful invariant test of the testing problems (Ⅰ) H 0: μ′Σ -1 μ≥CH 1: μ′Σ -1 μ<C and (Ⅱ) H 00 : β′X′Xβσ 2≥CH 11 : β′X′Xβσ 2<C u... The authors consider the uniformly most powerful invariant test of the testing problems (Ⅰ) H 0: μ′Σ -1 μ≥CH 1: μ′Σ -1 μ<C and (Ⅱ) H 00 : β′X′Xβσ 2≥CH 11 : β′X′Xβσ 2<C under m dimensional normal population N m(μ, Σ) and normal linear model (Y, Xβ, σ 2) respectively. Furthermore, an application of the uniformly most powerful invariant test is given. 展开更多
关键词 invariant test uniformly most powerful test improved estimator uniformly most accurate confidence bound
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Fast BSC-based algorithm for near-field signal localization via uniform circular array 被引量:1
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作者 SU Xiaolong LIU Zhen +3 位作者 SUN Bin WANG Yang CHEN Xin LI Xiang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2022年第2期269-278,共10页
In this paper,we propose a beam space coversion(BSC)-based approach to achieve a single near-field signal local-ization under uniform circular array(UCA).By employing the centro-symmetric geometry of UCA,we apply BSC ... In this paper,we propose a beam space coversion(BSC)-based approach to achieve a single near-field signal local-ization under uniform circular array(UCA).By employing the centro-symmetric geometry of UCA,we apply BSC to extract the two-dimensional(2-D)angles of near-field signal in the Van-dermonde form,which allows for azimuth and elevation angle estimation by utilizing the improved estimation of signal para-meters via rotational invariance techniques(ESPRIT)algorithm.By substituting the calculated 2-D angles into the direction vec-tor of near-field signal,the range parameter can be conse-quently obtained by the 1-D multiple signal classification(MU-SIC)method.Simulations demonstrate that the proposed al-gorithm can achieve a single near-field signal localization,which can provide satisfactory performance and reduce computational complexity. 展开更多
关键词 near-field signal uniform circular array(UCA) beam space conversion(BSC) improved estimation of signal parame-ters via rotational invariance techniques(ESPRIT) 1-D multiple signal classification(MUSIC) parameter estimation
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Improving Accuracy of Estimating Two-Qubit States with Hedged Maximum Likelihood 被引量:1
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作者 殷琪 项国勇 +1 位作者 李传锋 郭光灿 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第3期1-5,共5页
As a widely used reconstruction algorithm in quantum state tomography, maximum likelihood estimation tends to assign a rank-deficient matrix, which decreases estimation accuracy for certain quantum states. Fortunately... As a widely used reconstruction algorithm in quantum state tomography, maximum likelihood estimation tends to assign a rank-deficient matrix, which decreases estimation accuracy for certain quantum states. Fortunately, hedged maximum likelihood estimation (HMLE) [Phys. Rev. Lett. 105 (2010)200504] was proposed to avoid this problem. Here we study more details about this proposal in the two-qubit case and further improve its performance. We ameliorate the HMLE method by updating the hedging function based on the purity of the estimated state. Both performances of HMLE and ameliorated HMLE are demonstrated by numerical simulation and experimental implementation on the Werner states of polarization-entangled photons. 展开更多
关键词 MLE Improving Accuracy of Estimating Two-Qubit States with Hedged Maximum Likelihood
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The role of zonal flows in reactive fluid closures
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作者 jan weiland 《Plasma Science and Technology》 SCIE EI CAS CSCD 2018年第7期41-49,共9页
We will give an overview of results obtained by our reactive fluid model. It is characterised as a fluid model where all moments with sources in the experiment are kept. Furthermore, full account is taken for the high... We will give an overview of results obtained by our reactive fluid model. It is characterised as a fluid model where all moments with sources in the experiment are kept. Furthermore, full account is taken for the highest moments appearing in unexpanded denominators also including full toroidicity. It has been demonstrated that the strength of zonal flows is dramatically larger in reactive fluid closures than in those which involve dissipation. This gives a direct connection between the fluid closure and the level of excitation of turbulence. This is because zonal flows are needed to absorb the inverse cascade in quasi 2D turbulence. This also explains the similarity in structure of the transport coefficients in our model with a reactive closure in the energy equation and models which have a reactive closure because of zero ion temperature such as the Hasegawa-Wakatani model. Our exact reactive closure unifies several well-known features of tokamak experiments such as the L-H transition, internal transport barriers and the nonlinear Dimits upshift of the critical gradient for onset of transport. It also gives transport of the same level as that in nonlinear gyrokinetic codes. Since these include the kinetic resonance this confirms the validity of the thermodynamic properties of our model. Furthermore, we can show that while a strongly nonlinear model is needed in kinetic theory a quasilinear model is sufficient in the fluid description. Thus our quasilinear fluid model will be adequate for treating all relevant problems in bulk transport. This is finally confirmed by the reproduction by the model of the experimental power scaling of the confinement time Te ~ P-2/3. This confirms the validity of our reactive fluid model. This also gives credibility to our ITER simulations including the H-mode barrier. A new result is here, that alpha heating strongly reduces the slope of the H-mode barrier. This should significantly reduce the effects of ELM's. 展开更多
关键词 turbulent transport improved mixing length estimates zonal flows toroidicity
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Integration of GPS with a WiFi high accuracy ranging functionality
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作者 Khalid NUR Shaojun FENG +1 位作者 Cong LING Washington OCHIENG 《Geo-Spatial Information Science》 SCIE EI 2013年第3期155-168,共14页
High accuracy seamless positioning is required to support a vast number of applications in varying operational environments.Over the last few years,the global positioning system(GPS)has become the de facto technology ... High accuracy seamless positioning is required to support a vast number of applications in varying operational environments.Over the last few years,the global positioning system(GPS)has become the de facto technology for positioning applications.However,its performance is limited in indoor and dense urban environments due to multipath as well as signal attenuation and blockage.A number of techniques integrating GPS with other positioning technologies have been developed to address the limitations of standalone GPS in these difficult environments.While most of the developed techniques cover the outages of GPS in such environments,they do not provide acceptable performance,in terms of positioning accuracy,especially for some mission-critical(e.g.safety)applications.This paper proposes a tightly coupled(i.e.in the measurement domain)GPS/WiFi integration method which,in addition to addressing GPS outages,improves the overall positioning accuracy to the meter-level,thus satisfying the requirements of a number of location based services and intelligent transport systems applications.The performance of the proposed GPS/WiFi integration method is assessed for a number of scenarios in a simulation environment for an identified dense urban area in London,UK. 展开更多
关键词 GPS integration time estimation WIFI improved FOCUSS for Arrival Time Estimation(IFATE) Time Difference of Arrival(TDOA) WLAN IEEE802.11g
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