检索结果-内蒙古大学图书馆

Low-density parity check coded orthogonal frequency division multiplexing for PLC in non-Gaussian noise using LLRs derived from effective noise probability density functions

引用

IET COMMUNICATIONS 2017年第16期11卷 2425-2432页

作者： Al-Rubaye, Ghanim A. Tsimenidis, Charalampos C. Johnston, Martin Newcastle Univ Sch Elect & Elect Engn Merz Court Newcastle Upon Tyne NE1 7RU Tyne & Wear England

In this study, the performance of irregular low-density parity check (LDPC) coded orthogonal frequency division multiplexing (COFDM) utilising 4096 quadrature amplitude modulation (4096-QAM) is investigated over multipath power-line communication (PLC) channel. The effective complex-valued ratio distributions of the noise samples at the zero-forcing equaliser output considering both frequency-selective multipath PLCs, background and impulsive noise are derived, in addition to the condition for optimum detection of 4096-QAM and the bit error rate (BER). Moreover, the performance of the LDPC decoder is improved by computing the log-likelihood ratios (LLRs) required for soft decoding based on the derived probability density functions. Numerical results obtained using the newly derived LLRs demonstrate a significant performance improvement compared to the conventional receiver that uses blanking impulsive noise mitigation method and LLR computed based on the Gaussian distribution. Furthermore, EXtrinsic Information Transfer chart analysis demonstrates that the proposed approach requires fewer iterations for convergence compared to the conventional receiver. Finally, utilising channel bandwidth of 22.4MHz, the proposed system offers an improvement of 111Mbps over the conventional system to reach a maximum data throughput of 256Mbps for a signal-to-noise ratio of 39dB and BER of 10(-5).

关键词： parity check codes OFDM modulation carrier transmission on power lines probability Gaussian distribution quadrature amplitude modulation error statistics low-density parity check coded orthogonal frequency division multiplexing LPDC OFDM quadrature amplitude modulation multipath power-line communication channel complex-valued ratio distributions zero-forcing equaliser frequency-selective multipath PLC bit error rate BER log-likelihood ratios LLR probability density functions Gaussian distribution blanking impulsive noise mitigation method extrinsic information transfer chart analysis bandwidth 22 4 MHz

来源：评论

学校读者我要写书评

暂无评论

Experimental determination of adsorption energies, adsorption isotherms, probability density functions, and lateral molecular interactions on C_XH_Y/CaO systems

引用

JOURNAL OF CHROMATOGRAPHY A 2003年第2期1018卷 213-223页

作者： Margariti, S Siokos, V Roubani-Kalantzopoulou, F Natl Tech Univ Athens Sch Chem Engn Athens 15780 Greece

Reversed-flow gas chromatography (RF-GC) is extended to the measurements of the probability density function for the adsorption energies as well as the differential energies of adsorption due to lateral interactions of molecules adsorbed on different heterogeneous solid surfaces. All these calculations are based on a non-linear adsorption isotherm model as it is well accepted that the linear one is inadequate for substances such as these used in this work. Thus, some new important physicochemical parameters have been obtained for the characterization of the heterogeneous systems studied. The adsorbent used in this study was calcium oxide. The adsorption of many significant hydrocarbons was investigated. With these systematic experiments under conditions which are similar to the atmospheric ones, an extrapolation of the results obtained to "real" atmospheres with a high degree of confidence is possible. (C) 2003 Published by Elsevier B.V.

关键词： gas chromatography reversed-flow inverse gas chromatography probability density functions molecular interactions adsorption isotherms adsorption energies

来源：评论

学校读者我要写书评

暂无评论

ASSUMED AND EVOLUTION probability density-functions IN SUPERSONIC TURBULENT COMBUSTION CALCULATIONS

引用

JOURNAL OF PROPULSION AND POWER 1995年第6期11卷 1132-1138页

作者： BAURLE, RA HSU, AT HASSAN, HA NYMA INC COMPUTAT PHYS SECT CLEVELAND OH 44142 USA

The objective of this investigation is to compare the use of assumed probability density function (PDF) approaches for modeling supersonic turbulent reacting flowfields with the more elaborate approach where the PDF evolution equation is solved, previous calculations using assumed PDFs have shown modest improvements in the prediction of mean flow variables when compared with experimental data, However, these PDFs were unable to predict the higher order correlations with any reasonable degree of accuracy. Solving the evolution equation for the PDF did show slight improvements in these correlations when compared with experiment, but at a substantial cost in computer storage and time, Both approaches yielded comparable mean now quantities.

关键词： probability density functions Compressibility Turbulent Combustion Reynolds Averaged Navier Stokes Turbulence Models Courant Friedrichs Lewy Continuity Equation Convection Supersonic Reacting Flow Computing

来源：评论

学校读者我要写书评

暂无评论

Acquisition of probability density functions using a simple acousto-optic system

引用

OPTICAL ENGINEERING 1999年第7期38卷 1160-1165页

作者： Mehrl, DJ Markov, D Soni, TS Texas Tech Univ Dept Elect Engn Lubbock TX 79409 USA

We present a simple acousto-optic-based system useful for acquiring time-averaged probability density functions of arbitrary signals. A heuristic analysis is presented as well as experimental results that are shown to... 详细信息

关键词： acousto-optics probability density functions

来源：评论

学校读者我要写书评

暂无评论

Translating CFC-based piston ages into probability density functions of ground-water age in karst

引用

JOURNAL OF HYDROLOGY 2006年第3-4期330卷 735-747页

作者： Long, Andrew J. Putnam, Larry D. US Geol Survey Rapid City SD 57702 USA

Temporal age distributions are equivalent to probability density functions (PDFs) of transit time. The type and shape of a PDF provides important information related to groundwater mixing at the well or spring and the complex nature of flow networks in karst aquifers. Chlorofluorocarbon (CFC) concentrations measured for samples from 12 locations in the karstic Madison aquifer were used to evaluate the suitability of various PDF types for this aquifer. Parameters of PDFs could not be estimated within acceptable confidence intervals for any of the individual sites. Therefore, metrics derived from CFC-based apparent ages were used to evaluate results of PDF modeling in a more general approach. The ranges of these metrics were established as criteria against which families of PDFs could be evaluated for their applicability to different parts of the aquifer. Seven PDF types, including five unimodal and two bimodal models, were evaluated. Model results indicate that unimodal models may be applicable to areas close to conduits that have younger piston (i.e., apparent) ages and that bimodal models probably are applicable to areas farther from conduits that have older piston ages. The two components of a bimodal PDF are interpreted as representing conduit and diffuse flow, and transit times of as much as two decades may separate these PDF components. Areas near conduits may be dominated by conduit flow, whereas areas farther from conduits having bimodal distributions probably have good hydraulic connection to both diffuse and conduit flow. (c) 2006 Elsevier B.V. All rights reserved.

关键词： karst aquifer carbonate aquifer age dating age distributions chlorofluorocarbons CFC ground-water tracers probability density functions

来源：评论

学校读者我要写书评

暂无评论

Reconstruction of one-dimensional chaotic maps from sequences of probability density functions

引用

NONLINEAR DYNAMICS 2015年第3期80卷 1373-1390页

作者： Nie, Xiaokai Coca, Daniel Univ Sheffield Dept Automat Control & Syst Engn Sheffield S1 3JD S Yorkshire England

In many practical situations, it is impossible to measure the individual trajectories generated by an unknown chaotic system, but we can observe the evolution of probability density functions generated by such a system. The paper proposes for the first time a matrix-based approach to solve the generalized inverse Frobenius-Perron problem, that is, to reconstruct an unknown one-dimensional chaotic transformation, based on a temporal sequence of probability density functions generated by the transformation. Numerical examples are used to demonstrate the applicability of the proposed approach and evaluate its robustness with respect to constantly applied stochastic perturbations.

关键词： Chaotic maps Inverse Frobenius-Perron problem Nonlinear systems probability density functions

来源：评论

学校读者我要写书评

暂无评论

Evaluation of probability density functions in precipitation models for the Pacific Northwest

引用

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 1998年第3期34卷 617-627页

作者： Duan, JF Selker, J Grant, GE Oregon State Univ Dept Bioresource Engn Corvallis OR 97331 USA USDA Pacific NW Res Stn Forest Sci Lab Corvallis OR 97331 USA

Recent work has found that a one-parameter Weibull model of wet day precipitation amount based on the Weibull distribution provides a better fit to historical daily precipitation data for eastern U.S. sites than other one-parameter models. The general two-parameter Weibull distribution was compared in this study to other widely used distributions for describing the distribution of daily precipitation event sizes at 99 sites from the U.S. Pacific Northwest. Surprisingly little performance was sacrificed by reducing the two-parameter Weibull to a single-parameter distribution. Advantages of the single-parameter model included requiring only the mean wet day precipitation amount for calibration, invertibility for simulation purposes, and ease of analytical manipulation. The fit of the single-parameter Weibull to the 99 stations included in this study was significantly better than other single-parameter models tested, and performed as well as the widely endorsed, more cumbersome, two-parameter gamma model. Both the one-and two-parameter Weibull distributions are shown to have L-moments that are consistent with historical precipitation data, while the ratio of L-skew and L-variance in the gamma model is inconsistent with the historical record by this measure. In addition, it was found that the two-parameter gamma distribution was better fit using the method of moments estimators than maximum likelihood estimates. These findings suggested that the distribution in precipitation among sites in the Pacific Northwest with dramatically different settings are nearly identical if expressed in proportion to the mean site event size.

关键词： meteorology/climatology precipitation model probability density functions Pacific Northwest surface water hydrology simulation

来源：评论

学校读者我要写书评

暂无评论

MODELING OF SUPERSONIC TURBULENT COMBUSTION USING ASSUMED probability density-functions

引用

JOURNAL OF PROPULSION AND POWER 1994年第6期10卷 777-786页

作者： BAURLE, RA ALEXOPOULOS, GA HASSAN, HA N CAROLINA STATE UNIV RALEIGH NC 27695 USA

Recent calculations of turbulent supersonic reacting shear flows using an assumed multivariate beta probability density function (PDF) resulted in reduced production rates and a delay in the onset of combustion. This result is not consistent with available measurements. Earlier work was based on a one-equation turbulence model that required a specification of the Length scale, PDFs that did not yield Favre-averaged quantities, and the gradient diffusion assumption. The present work incorporates a two-equation turbulence model based on a kappa-omega formulation, a PDF that yields Favre averages, and relaxes the gradient diffusion assumption. Results suggest that the form of the assumed multivariate PDF and the gradient diffusion assumption are the main causes of the discrepancy.

关键词： probability density functions Turbulent Combustion Turbulence Models Reynolds Averaged Navier Stokes Direct Numerical Simulation Conservation Equations Shear Layers Turbulent Flow Angle of Attack Sensitivity Analysis

来源：评论

学校读者我要写书评

暂无评论

Approximation of probability density functions via location-scale finite mixtures in Lebesgue spaces

引用

COMMUNICATIONS IN STATISTICS-THEORY AND METHODS 2023年第14期52卷 5048-5059页

作者： Nguyen, TrungTin Chamroukhi, Faicel Nguyen, Hien D. McLachlan, Geoffrey J. Normandie Univ UNICAEN LMNO CNRS F-14000 Caen France La Trobe Univ Sch Engn & Math Sci Dept Math & Stat Melbourne Vic Australia Univ Queensland Sch Math & Phys Brisbane Qld Australia

The class of location-scale finite mixtures is of enduring interest both from applied and theoretical perspectives of probability and statistics. We establish and prove the following results: to an arbitrary degree of accuracy, (a) location-scale mixtures of a continuous probability density function (PDF) can approximate any continuous PDF, uniformly, on a compact set;and (b) for any finite p >= 1, location-scale mixtures of an essentially bounded PDF can approximate any PDF in L-p, in the L-p norm.

关键词： Mixture models approximation theory uniform approximation probability density functions

来源：评论

学校读者我要写书评

暂无评论

Identification of Stochastically Perturbed Autonomous Systems from Temporal Sequences of probability density functions

引用

JOURNAL OF NONLINEAR SCIENCE 2018年第4期28卷 1467-1487页

作者： Nie, Xiaokai Luo, Jingjing Coca, Daniel Birkin, Mark Chen, Jing Univ Leeds Leeds Inst Data Analyt Leeds LS2 9JT W Yorkshire England Univ Sheffield Dept Automat Control & Syst Engn Sheffield S1 3JD S Yorkshire England Fudan Univ Acad Engn & Technol Inst AI & Robot Shanghai 200433 Peoples R China Univ Warwick Warwick Med Sch Coventry CV4 7AL W Midlands England

The paper introduces a method for reconstructing one-dimensional iterated maps that are driven by an external control input and subjected to an additive stochastic perturbation, from sequences of probability density f... 详细信息

关键词： Nonlinear systems probability density functions Frobenius-Perron operator Stochastic dynamical systems

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：