检索结果-南通市图书馆

Indium tin oxide nanosized composite powder prepared using waste ITO target

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2005年第3期24卷 277-282页

作者： LIU Jiaxiang gan Yong ZENG Shengnan The k.y Laboratory for Science and Technology of Controllable Chemical Reactions Ministry of Education College of Materials Science andEngineering Beijing University of Chemical Technology Beijing 100029 China

Indium tin oxide （ITO） nano-particles were prepared directly using waste ITO target, which had been coated by magnetron controlled sputtering. The waste ITO target was cleaned with de-ionized water, and then dissolved in acid, filtrated, neutralized, manipulated through azeotropic distillation and finally dried, and in this way the precursor of indium tin hydroxide was obtained. The nanosized rio composite powder was prepared after the precursor heat-treated at 500℃ for 2 h. TEM images show a narrow distribution of particle size is 5-20 nm and the particle size can be controlled. Its granule has a spherical shape and the dispersion of the particle is well. X-ray diffraction （XRD） patterns indicate the only cubic In2O3 phase in the ITO powder hot-treated at 500℃. The purity of ITO composite powder is 99.9907%. The content of radium within filtrate was detected by using the EDTA titration of determination of indium in the ITO powder and ITO target. Appropriate amount of SnCl4.5H2O was dissolved in the filtrate, and then ITO powder containing 10 wt.% SnO2 was successfully prepared by heat-treating.

关键词： waste ITO target nanosized ITO composite powder chemical technique microstructure

PN code acquisition algorithm in DS-UWB system based on threshold comparison criterion

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2009年第1期20卷 216-222页

作者： Qi Lina gan Zongliang Zhu Hongbo Coll. of Telecommunications & Information Engineering Nanjing Univ. of Posts and Telecommunication Nanjing 210003 P.R. China

The direct sequence ultra-wideband （DS-UWB） is a promising technology for short-range wireless communications. The UWB signal is a stream of very low power density and ultra-short pulses, and the great potential of DS-UWB depends critically on the success of timing acquisition. A rapid acquisition algorithm for reducing the acquisition time of the coarse pseudo-noise （PN） sequences is proposed. The algorithm utilizes the auxiliary sequence and bisearch strategy based on the threshold comparison criterion. Both theoretical analysis and simulation tests show that with the proposed search strategy and simple operations over the symbol duration at the receiver, the proposed algorithm can considerably reduce the acquisition time even as it maintains the PN sequence acquisition probability in the DS-UWB system over the dense multipath environment.

关键词： direct sequence ultra-wideband pseudo-noise code auxiliary sequence synchronization.

Macro liveness graph and liveness of ω-independent unbounded nets

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2015年第3期58卷 132-141页

作者： WANG ShouGuang gan MengDi ZHOU MengChu School of Information and Electronic Engineering Zhejiang Gongshang University k.y Laboratory of Embedded System and Service Computing Ministry of EducationTongji University Department of Electrical and Computer Engineering New Jersey Institute of Technology

Liveness is a basic property of a system and the liveness issue of unbounded Petri nets remains one of the most difficult problems in this *** work.proposes a novel method to decide the liveness of a class of unbounded generalized Petri nets calledω-independent unbounded nets,break.ng the existing limits to one-place-unbounded *** algorithm to construct a macro liveness graph(MLG)is developed and a critical condition based on MLG deciding the liveness ofω-independent unbounded nets is *** are provided to demonstrate its effectiveness.

关键词： discrete event system(DES) Petri nets complex systems liveness property analysis

Nonlinear magnetic network.models for flux-switching permanent magnet machines

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第3期59卷 494-505页

作者： zhang gan hua wei cheng ming School of Electrical Engineering Southeast University Nanjing 210096 China

In this paper, firstly, a basic nonlinear magnetic network.model considering iron saturations is proposed for a three-phase 12-stator-slot/10-rotor-pole flux-switching permanent magnet(FSPM) machine. This model is built under cylindrical coordinates and enables the open-circuit air-gap flux-density distributions, phase permanent magnet(PM) flux-link.ge, and electromotive-force(EMF) to be predicted with acceptable accuracy. However, large discrepancies are found in the predictions of armature inductances. Then, the basic model is modified by tak.ng into account the localized saturation effect. As a result, the electromagnetic performance can be predicted more accurately, especially for the air-gap flux-density distributions. Furthermore, two improved models are proposed by adding bypass-bridge branches in stator network. to enhance the calculating accuracy of both saturated and unsaturated armature inductances. Finally, the predicted results from the four magnetic network.models are validated by both 2D finite element analysis(FEA) and experimental measurements on a machine prototype. Overall, comparisons indicate that the model with bypass-bridge branches between stator teeth and back.irons exhibits best performances.

关键词： air-gap flux density finite element analysis flux switching nonlinear magnetic network permanent magnet

Two-dimensional iron-porphyrin sheet as a promising catalyst for oxygen reduction reaction: a computational study

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2017年第19期62卷 1337-1343页

作者： gan Luo Yu Wang Yafei Li Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials Jiangsu Key Laboratory of New Power BatteriesSchool of Chemistry and Materials ScienceNanjing Normal University

The development of non-platinum(Pt) oxygen reduction reaction(ORR) catalysts with high activity and low cost is of great importance for large-scale commercialization of fuel cells. By means of density functional theory(DFT) computations, we theoretically identified that two-dimensional(2D) iron-porphyrin(Fe-Pp) sheet, in which the active Fe sites are distributed regularly and separately, is an appealing candidate. The pristine Fe-Pp sheet exhibits considerably high catalytic activity and four-electron selectivity for ORR. Especially, the adsorption of ORR intermediates on Fe-Pp sheet can be significantly weak.ned by the addition of axial cyanogen(CN) ligand, resulting in pronouncedly enhanced ORR activity. More interestingly, the d band center of CN attached Fe-Pp(Fe-Pp-CN) sheet can be further tuned by applying the external tensile or compressive strain, leading to an enhancement or suppression of ORR catalytic performance. In particular, under a small biaxial tensile strain of 2%, the ORR activity of Fe-Pp-CN sheet is even higher than that of Pt and reaches to the top of activity volcano. Our studies open new ways to design effective non-Pt ORR catalysts for fuel cell technology.

关键词： ElectrocatalystORR2D matedals DFT computations

Distribution-based CFAR detectors in SAR images

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2006年第4期17卷 717-721页

作者： gan Rongbing Wang Jianguo National Electronic Warfare Lab Chengdu 610036 P.R.China School of Electronic Engineering Univ. of Electronic Science and Techndogy Chengdu 610054 P. R. China

As traditional two-parameter constant false alarm rate （CFAR） target detec-tion algorithms in SAR images ignore target distribution, their performances are not the best or near best. As the resolution of SAR images increases, small targets present more pixels in SAR images. So the target distribution is of much significance. Distribution-based CFAR detection algorithm is presented. We unite the pixels around the test cell, and estimate the distribution of test cell by them. Generalized Lik.lihood Ratio Test （GLRT） is used to deduce the detectors. The performance of the distribution-based CFAR （DBCFAR） detectors is analyzed theoretically. False alarms of DBCFAR detection are fewer than those of CFAR at the same detection rate. Finally experiments are done and the results show the performance of DBCFAR is out of conventional CFAR. False alarms of DBCFAR detection are concentrated while those of CFAR detection are dispersive.

关键词： synthetic aperture radar (SAR) target detection constant false alarm rate (CFAR) generalized lik.lihood ratio test (GLRT).

Effect of tungsten oxide on ceria nanorods to support copper species as CO oxidation catalysts

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2021年第1期39卷 43-50,I0002页

作者： Yu'nan Li Lin gan Rui Si Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and School of Material Science and EngineeringHubei UniversityWuhan 430062China Zhangjiang Laboratory Shanghai Synchrotron Radiation FacilityShanghai 201204China

In this work.tungsten oxide with different concentrations(0,0.4 at%,2.0 at%and 3.2 at%)was introduced to the ceria nanorods via a deposition-precipitation(DP)approach,and copper species of ca.10 at%were sequentially anchored onto the modified ceria support by a similar DP *** aim of the study was to investigate the effect of the amount of tungsten oxide(0,0.4 at%,2.0 at%,and 3.2 at%)modifier on the copper-ceria catalysts for CO oxidation reaction and shed light on the structure-activity *** the aids of multiple characterization techniques including N2 adsorption,high-resolution transmission electron microscopy(HRTEM),powder X-ray diffraction(XRD),X-ray absorption fine structure(XAFS),and temperature-programmed reduction by hydrogen(H2-TPR)in combination with the catalytic performance for CO oxidation reaction,it is found that the copper-ceria samples maintain the crystal structure of the fluorite fcc CeO2 phase with the same nanorod-lik. morphology with the introduction of tungsten oxide,while the textural properties(the surface area,pore volume and pore size)of ceria support and copper-ceria catalysts are changed,and the oxidation states of copper and tungsten are k.pt the same as Cu2+and W6+before and after the reaction,but the introduction of tungsten oxide(WO3)significantly changes the metal-support interaction(transfer the CuOx clusters to Cu-[Ox]-Ce species),which delivers to impair the catalytic activity of copper-ceria catalysts for CO oxidation reaction.

关键词： Copper catalyst Ceria Tungsten oxide CO oxidation Structure-activity relationship Rare earths

Maximal-minimal correlation atoms algorithm for sparse recovery

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2013年第4期24卷 579-585页

作者： Wei gan Luping Xu Hua Zhang School of Electronic Engineering Xidian University

A new iterative algorithm is proposed to reconstruct an unk.own sparse signal from a set of projected measurements. Unlik. existing greedy pursuit methods which only consider the atoms having the highest correlation with the residual signal, the proposed algorithm not only considers the higher correlation atoms but also reserves the lower correlation atoms with the residual signal. In the lower correlation atoms, only a few are correct which usually impact the reconstructive performance and decide the reconstruction dynamic range of greedy pursuit methods. The others are redundant. In order to avoid redundant atoms impacting the reconstructive accuracy, the Bayesian pursuit algorithm is used to eliminate them. Simulation results show that the proposed algorithm can improve the reconstructive dynamic range and the reconstructive accuracy. Furthermore, better noise immunity compared with the existing greedy pursuit methods can be obtained.

关键词： compressive sensing (CS) correlation atom Bayesian hypothesis sparse reconstruction.

Second-order phase correction of NMR spectra acquired using linear frequency-sweeps

在线全文

学校读者我要写书评

暂无评论

Magnetic Resonance Letters 2022年第1期2卷 1-8,I0002页

作者： Zhehong gan Ivan Hung National High Magnetic Field Laboratory 1800 East Paul Dirac DriveTallahasseeFL32310USA

NMR spectra acquired with experiments using frequency-sweeps such as the wide-band uniform-rate smooth truncation(WURST)spin-echo and Carr-Purcell-Meiboom-Gill(CPMG)sequences cannot be absorptively phased by using only conventional zerothand first-order phase *** of phase correction up to the secondorder is described for obtaining absorptive spectra,which have more desirable line shapes and noise properties than magnitude *** relationship of the second-order phase to the parameters of frequency sweeps is *** second-order phasing in the frequency-domain is equivalent to a point spread in the time-domain *** application of second-order phase correction is demonstrated with a wideline 35Cl CPMG spik.let spectrum.

关键词： Second-order phase Noise Line shape Absorptive Dispersive Frequency sweep CHIRP WURST Adiabatic Broadband CPMG Spin-echo Wideline ^(35)Cl