检索结果-内蒙古大学图书馆

Switching architecture for CMOS exponential function generators eliminating squarer/multiplier circuits

ELECTRONICS LETTERS 2014年第4期50卷 258-259页

作者： Ray, S. Hella, M. M. Rensselaer Polytech Inst Dept Elect Comp & Syst Engn Troy NY 12180 USA

A switching architecture for exponential function generators in submicron CMOS technology is proposed. The architecture is based on second-order rational approximation of exponential functions and can be realised usin... 详细信息

关键词： COMPLEMENTARY metal oxide semiconductors DIGITAL electronics logarithmic functions TRANSCENDENTAL functions SIGNAL generators

来源：评论

学校读者我要写书评

暂无评论

Doppler radar microphone with logarithmic square-law detector

引用

ELECTRONICS LETTERS 2016年第12期52卷 1061-1062页

作者： Aumann, H. M. Emanetoglu, N. W. Univ Maine Dept Elect & Comp Engn Orono ME 04420 USA

A Doppler radar based microphone is similar to an acoustic microphone except that it detects vibrations rather than sound. A microphone with a logarithmic square-law detector for monitoring honeybees is described. The performance of a logarithmic square-law detector is compared with a more conventional zero-intermediate frequency (IF), direct down conversion receiver. It is shown that unavoidable coupling between the transmitter and receiver as well as stationary clutter have the same effect in the square-law receiver as the local oscillator signal and mixer have in the direct down conversion receiver. The theoretical output of either configuration is formally the same. Both receiver designs were implemented in a low-cost, low-power radar microphone operating in the unlicensed 5.8 GHz industrial, scientific and medical band. The use of a logarithmic square-law detector resulted in a significant simplification of the radar microphone design as well as a 10 dB improvement in signal-to-noise ratio.

关键词： Doppler radar logarithmic functions Nonlinear oscillators Honeybees Beekeepers

来源：评论

学校读者我要写书评

暂无评论

A Mathematical Method for Eliminating Spin Losses in Toroidal Traction Drives

引用

MATHEMATICAL PROBLEMS IN ENGINEERING 2015年第1期2015卷 1-10页

作者： Li, Qingtao Wu, Jie Li, Hua Yao, Jin Sichuan Univ Sch Mfg Sci & Engn Chengdu 610065 Peoples R China

The efficiency of the original Toroidal continuously variable transmission (CVT) is limited due to the spin losses caused by the different speed distribution in the contact area. To overcome this drawback, this paper replaces the original working surface with a new surface derived from a differential equation and proposes a novel logarithmic CVT. Equations and ranges of the transmission ratio range, half-cone-angle, and conformity ratio, which are essential geometrical parameters of the logarithmic CVT, are derived. A set of geometrical parameters is further recommended. With such geometrical parameters, the transmission ratio range of the logarithmic CVT is as wide as that of the Half-Toroidal CVT. The two types of CVTs are compared with each other in terms of efficiency based on a widely accepted computational model. The results show that efficiency of the logarithmic CVT is higher than that of Half-Toroidal CVT except for some particular situations because of the thrust bearing losses.

关键词： TRACTION drives CONTINUOUS functions DIFFERENTIAL equations logarithmic functions PARAMETERS (Statistics)

来源：评论

学校读者我要写书评

暂无评论

Distinguishing Analyte from Noise Components in Mass Spectra of Complex Samples: Where to Cut the Noise?

引用

ANALYTICAL CHEMISTRY 2014年第7期86卷 3308-3316页

作者： Zhurov, Konstantin O. Kozhinov, Anton N. Fomelli, Luca Tsybin, Yury O. Ecole Polytech Fed Lausanne Biomol Mass Spectrometry Lab CH-1015 Lausanne Switzerland

Fourier transform mass spectrometry (FTMS) enables comprehensive analysis of complex molecular mixtures. Given the broad intensity ranges of components in the mass spectra, it is imperative to accurately determine a noise threshold level above which peak assignments will be made. Conventionally, to find the threshold level, the "N sigma" approach or an equivalent rule is used. However, the "N sigma" approach cannot be applied to mass spectra stored with partially removed noise (reduced-profile mode). It is also not directly applicable to mass spectra acquired in the absorption mode with removed negative spectral amplitudes. Moreover, N value selection is normally made based on a rule of thumb, meaning that the calculated threshold level may be biased. Here, we present a noise thresholding method which addresses these limitations for analysis of mass spectra of complex molecular mixtures. The introduced data-dependent thresholding method involves analysis of the distribution of logarithmic intensity of all peaks, including noise and analyte, for a given mass spectrum. Selected method applications include FTMS analysis of crude oil fractions as well as tandem MS analysis of intact proteins.

关键词： FOURIER transform spectroscopy NOISE -- Measurement TANDEM mass spectrometry AMPLITUDE estimation logarithmic functions

来源：评论

学校读者我要写书评

暂无评论

A refined interpretation of the logarithmic structure function law in wall layer turbulence

引用

PHYSICS OF FLUIDS 2006年第6期18卷 65112-1-65112-页

作者： Davidson, P. A. Krogstad, P. -A. Nickels, T. B. Univ Cambridge Dept Engn Cambridge CB2 1PZ England Norwegian Univ Sci & Technol Dept Energy & Proc Engn N-7491 Trondheim Norway Univ Cambridge Dept Engn Cambridge CB2 1PZ England

It has been shown recently that the real-space equivalent of the k(-1) law for near-wall turbulence is a logarithmic law for the second-order longitudinal structure function, (r)=u(*)(2)(A+B ln(r/y)). Here y is the di... 详细信息

It has been shown recently that the real-space equivalent of the k(-1) law for near-wall turbulence is a logarithmic law for the second-order longitudinal structure function, <(Delta u)(2)>(r)=u(*)(2)(A+B ln(r/y)). Here y is the distance from the wall, u(*) is the shear velocity, A and B are coefficients of order unity and r is measured in the streamwise direction. In this paper we provide theoretical arguments to suggest that, in the limit of large Reynolds number, B is a universal constant while A is of the form A=A(')-B ln(P/epsilon), where A(') is a universal constant and P and epsilon are the rates of production and dissipation of energy, respectively. Hence A is a weak, universal, function of y. Two independent sets of data are examined and it is shown that, to within experimental error, our predictions are consistent with the data.

关键词： logarithmic functions LOGARITHMS TURBULENCE FLUID dynamics REYNOLDS number

来源：评论

学校读者我要写书评

暂无评论

Data gathering with tunable compression in sensor networks

引用

IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2008年第2期19卷 276-287页

作者： Yu, Yang Krishnamachari, Bhaskar Prasanna, Viktor K. Applicat Res Ctr Motorola Labs Schaumburg IL 60196 USA Univ So Calif Dept Elect Engn Los Angeles CA 90089 USA

We study the problem of constructing a data gathering tree over a wireless sensor network in order to minimize the total energy for compressing and transporting information from a set of source nodes to the sink. This problem is crucial for advanced computationally intensive applications, where traditional "maximum" in-network compression may result in significant computation energy. We investigate a tunable data compression technique that enables effective trade-offs between the computation and communication costs. We derive the optimal compression strategy for a given data gathering tree and then investigate the performance of different tree structures for networks deployed on a grid topology, as well as general graphs. Our analytical results pertaining to the grid topology and simulation results pertaining to the general graphs indicate that the performance of a simple greedy approximation to the Minimal Steiner Tree (MST) provides a constant-factor approximation for the grid topology and good average performance on the general graphs. Although, theoretically, a more complicated randomized algorithm offers a polylogarithmic performance bound, the simple greedy approximation of MST is attractive for practical implementation.

关键词： DATA transmission systems SENSOR networks TOPOLOGY STEINER systems APPROXIMATION theory ALGORITHMS logarithmic functions

来源：评论

学校读者我要写书评

暂无评论

Agreement, Precision, and Accuracy of Epifluorescence Microscopy Methods for Enumeration of Total Bacterial Numbers

引用

APPLIED AND ENVIRONMENTAL MICROBIOLOGY 2010年第6期76卷 1981-1991页

作者： Seo, Eun-Young Ahn, Tae-Seok Zo, Young-Gun Kangwon Natl Univ Dept Environm Sci Chunchon 200701 South Korea

To assess interchangeability of estimates of bacterial abundance by different epifluorescence microscopy methods, total bacterial numbers (TBNs) determined by most widely accepted protocols were statistically compared. Bacteria in a set of distinctive samples were stained with acridine orange (AO), 4'-6-diamidino-2-phenylindole (DAPI), and BacLight and enumerated by visual counting (VC) and supervised image analysis (IA). Model II regression and Bland-Altman analysis proved general agreements between IA and VC methods, although IA counts tended to be lower than VC counts by 7% on a logarithmic scale. Distributions of cells and latex beads on polycarbonate filters were best fitted to negative binomial models rather than to Poisson or log-normal models. The fitted models revealed higher precisions of TBNs by the IA method than those by the VC method. In pairwise comparisons of the staining methods, TBNs by AO and BacLight staining showed good agreement with each other, but DAPI staining had tendencies of underestimation. Although precisions of the three staining methods were comparable to one another (intraclass correlation coefficients, 0.97 to 0.98), accuracy of the DAPI staining method was rebutted by disproportionateness of TBNs between pairs of samples that carried 2-fold different volumes of identical cell suspensions. It was concluded that the TBN values estimated by AO and BacLight staining are relatively accurate and interchangeable for quantitative interpretation and that IA provides better precision than does VC. As a prudent measure, it is suggested to avoid use of DAPI staining for comparative studies investigating accuracy of novel cell-counting methods.

关键词： BACTERIA -- Research MICROSCOPY CELL culture IMAGE analysis logarithmic functions CELL suspensions COMPARATIVE studies CASE-control method REGRESSION analysis

来源：评论

学校读者我要写书评

暂无评论

A new approach for atmospheric correction of MODIS imagery in turbid coastal waters: a case study for the Pearl River Estuary

引用

REMOTE SENSING LETTERS 2014年第3期5卷 249-257页

作者： He, Quanjun Chen, Chuqun Chinese Acad Sci South China Sea Inst Oceanol State Key Lab Trop Oceanog Guangzhou Guangdong Peoples R China Guangdong Prov Meteorol Bur Guangzhou Meteorol Satellite Ground Stn Guangzhou Guangdong Peoples R China Univ Chinese Acad Sci Grad Sch Beijing Peoples R China

The algorithms for atmospheric correction (AC) of Moderate Resolution Imaging Spectroradiometer (MODIS) data may yield negative water-leaving radiances in highly turbid coastal waters along the Pearl River Estuary of China. This failure of AC can be attributed to the high reflectance from the suspended sediments in the near-infrared (NIR) bands, which results in an overestimate of the aerosol scattering and hence overcorrection in the visible bands. In this letter, a new shortwave infrared extrapolation (SWIRE) method is presented for Terra-MODIS data. The Rayleigh-corrected reflectances in the SWIR bands (1.24, 1.64, and 2.13 mu m) are used to determine an exponential function with respect to wavelength, which is used to correct the NIR bands (0.748 and 0.869 mu m) for sediment scattering and hence estimate the aerosol scattering reflectances in these bands. Then the Gordon and Wang AC approach is applied. The performance of this new SWIRE algorithm is demonstrated using two examples centred on the Pearl River Estuary, with the results showing that the new approach can improve the AC for these turbid waters.

关键词： TRANSCENDENTAL functions SUSPENDED sediments SPECTRORADIOMETER SPECTROPHOTOMETERS logarithmic functions

来源：评论

学校读者我要写书评

暂无评论

Constant-Space P Systems with Active Membranes

引用

FUNDAMENTA INFORMATICAE 2014年第1-2期134卷 111-128页

作者： Leporati, Alberto Manzoni, Luca Mauri, Giancarlo Porreca, Antonio E. Zandron, Claudio Univ Milano Bicocca Dipartimento Informat Sistemist & Comunicaz I-20126 Milan Italy

We show that a constant amount of space is sufficient to simulate a polynomial-space bounded Turing machine by P systems with active membranes. We thus obtain a new characterisation of PSPACE, which raises interesting questions about the definition of space complexity for P systems. We then propose an alternative definition, where the size of the alphabet and the number of membrane labels of each P system are also taken into account. Finally we prove that, when less than a logarithmic number of membrane labels is available, moving the input objects around the membrane structure without rewriting them is not enough to even distinguish inputs of the same length.

关键词： POLYNOMIALS BOUNDS (Mathematics) COMPUTATIONAL complexity logarithmic functions REWRITING systems (Computer science)

来源：评论

学校读者我要写书评

暂无评论

H∞ Filtering for Discrete-Time Nonlinear Singular Systems with Quantization

引用

MATHEMATICAL PROBLEMS IN ENGINEERING 2017年 2017卷 1-9页

作者： Feng, Yifu Li, Zhi-Min Chang, Xiao-Heng Jilin Normal Univ Coll Math Siping 136000 Jilin Peoples R China Wuhan Univ Sci & Technol Sch Informat Sci & Engn Wuhan 430081 Hubei Peoples R China Bohai Univ Coll Engn Jinzhou 121003 Liaoning Peoples R China

This paper investigates the problem of H-infinity filtering for class discrete-time Lipschitz nonlinear singular systems with measurement quantization. Assume that the system measurement output is quantized by a static, memoryless, and logarithmic quantizer before it is transmitted to the filter, while the quantizer errors can be treated as sector-bound uncertainties. The attention of this paper is focused on the design of a nonlinear quantized H-infinity filter to mitigate quantization effects and ensure that the filtering error system is admissible (asymptotically stable, regular, and causal), while having a unique solution with a prescribed H-infinity noise attenuation level. By introducing some slack variables and using the Lyapunov stability theory, some sufficient conditions for the existence of the nonlinear quantized H-infinity filter are expressed in terms of linear matrix inequalities (LMIs). Finally, a numerical example is presented to demonstrate the effectiveness of the proposed quantized filter design method.

关键词： DISCRETE-time systems LIPSCHITZ spaces GEOMETRIC quantization logarithmic functions NONLINEAR analysis LYAPUNOV functions

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：