检索结果-南通市图书馆

Reaction of Crossed Diperoxidation Between Cyclic Ketones and Alkyl Ketones

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

Chemical Research in Chinese Universities 2002年第4期18卷 412-413页

作者： XU wei-liang FU Cheng-ling Organic Chemistry Group Huajiachi SectionZhejiang UniversityHangzhou 310029P.R.China

The reaction of crossed diperoxidation between the cyclic ketones and the alkyl ketones was investigated. The reaction is a competing in different ketones. It is slightly favorable to resulting in crossed ketone diper... 详细信息

关键词： Synthesis Crossed diperoxidation Crossed ketone diperoxide

Symmetry and monotonicity of positive solutions to Schr?dinger systems with fractional p-Laplacians

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2022年第1期37卷 52-72页

作者： MA ling-wei ZHANG Zhen-qiu School of Mathematical Sciences Tianjin Normal UniversityTianjin 300387China School of Mathematical Sciences and LPMC Nankai UniversityTianjin 300071China

In this paper,we first establish narrow region principle and decay at infinity theorems to extend the direct method of moving planes for general fractional p-Laplacian *** virtue of this method,we investigate the qualitative properties of positive solutions for the following Schrodinger system with fractional p-Laplacian{(-△)^(s)_(p)u+au^(p-1)=f(u,v),(-△)^(t)_(p)v+bv(p-1)=g(u,v),where 0

关键词： fractional p-Laplacian Schr?dinger systems direct method of moving planes radial symmetry monotonicity nonexistence

Multi-instance partial-label learning: towards exploiting dual inexact supervision

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第3期67卷 48-61页

作者： wei TANG weijia ZHANG Min-ling ZHANG School of Computer Science and Engineering Southeast University Key Laboratory of Computer Network and Information Integration (Southeast University) Ministry of Education School of Information and Physical Sciences The University of Newcastle

Weakly supervised machine learning algorithms are able to learn from ambiguous samples or labels, e.g., multi-instance learning or partial-label learning. However, in some real-world tasks, each training sample is associated with not only multiple instances but also a candidate label set that contains one groundtruth label and some false positive labels. Specifically, at least one instance pertains to the ground-truth label while no instance belongs to the false positive labels. In this paper, we formalize such problems as multi-instance partial-label learning(MIPL). Existing multi-instance learning algorithms and partial-label learning algorithms are suboptimal for solving MIPL problems since the former fails to disambiguate a candidate label set, and the latter cannot handle a multi-instance bag. To address these issues, a tailored algorithm named MIPLGP, i.e., multi-instance partial-label learning with Gaussian processes, is *** first assigns each instance with a candidate label set in an augmented label space, then transforms the candidate label set into a logarithmic space to yield the disambiguated and continuous labels via an exclusive disambiguation strategy, and last induces a model based on the Gaussian processes. Experimental results on various datasets validate that MIPLGP is superior to well-established multi-instance learning and partial-label learning algorithms for solving MIPL problems.

关键词： machine learning multi-instance partial-label learning multi-instance learning partial-label learning Gaussian processes

SnO_2 hollow nanospheres assembled by single layer nanocrystals as anode material for high performance Li ion batteries

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2015年第1期26卷 124-128页

作者： wei wei ling-Xiao Song Lin Guo School of Chemistry and Chemical Engineering Shangqiu Normal University School of Chemistry and Environment Beijing University of Aeronautics & Astronautics College of Chemistry and Molecular Engineering Zhengzhou University

SnO2 hollow nanospheres were successfully synthesized via a facile one-step solvothermal *** show that the as-prepared SnO2 spheres are of hollow structure with a diameter at around 50 nm,and especially,the shell of the spheres is assembled by single layer SnO2 *** surface area of the material reaches up to 202.5 m^2/*** an anode material for Li ion batteries,the sample exhibited improved electrochemical performance compared with commercial SnO2 *** cycled at high current rate of 0.5 C,1 C and 0.5 C for 20 cycles,respectively,the electrode can maintain a capacity of 509 mAh/*** suitable shell thickness/diameter ratio endows the good structural stability of the material during cycling,which promises the excellent cycling performance of the *** large surface area and the ultra thin shell ensure the high rate performance of the material.

关键词： SnO2 Hollow nanospheres Single layer Li ion batteries

Catalytic performance and reaction mechanisms of NO removal with NH_(3) at low and medium temperatures on Mn-W-Sb modified siderite catalysts

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2022年第5期34卷 126-139页

作者： Guihuan Yao Yuliang wei Keting Gui Xiang ling School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211816China School of Energy and Environment Southeast UniversityNanjing 210096China

Iron-based catalysts have been explored for selective catalytic reduction(SCR)of NO due to environmentally benign characters and good SCR ***-W-Sb modified siderite catalysts were prepared by impregnation method based on siderite ore,and SCR perfor-mance of the catalysts was *** catalysts were analyzed by X-ray diffrac-tion,H_(2)-temperature-programmed reduction,Brunauer-Emmett-Teller,Thermogravimetry-derivative thermogravimetry and in-situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS).The modified siderite catalysts calcined at 450℃ mainly consist of Fe_(2)O_(3),and added Mn,W and Sb species are amorphous.3Mn-5W-1.5Sb-siderite catalyst has a wide temperature window of 180-360℃ and good N_(2) selectivity at low ***-situ DRIFTS results show NH_(4)^(+),coordinated NH_(3),NH_(2),NO_(3)^(-)species(bidentate),NO_(2)-species(nitro,nitro-nitrito,monodentate),and adsorbed NO_(2) can be discovered on the sur-face of Mn-W-Sb modified siderite catalysts,and doping of Mn will enhance adsorbed NO_(2) formation by synergistic catalysis with Fe^(3+).In addition,the addition of Sb can inhibit sulfates formation on the surface of the catalyst in the presence of SO_(2) and H_(2)***-dependent in-situ DRIFTS studies also indicate that both of Lewis and Br?nsted acid sites play a role in SCR of NO by ammonia at low *** mechanism of NO removal on the 3Mn-5W-1.5Sb-siderite catalyst can be discovered as a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms with three reaction *** mechanism of NO,oxidized by synergistic catalysis of Fe^(3+)and Mn^(4+/3+)to form NO_(2) among three pathways,reveals the reason of high NO_(x) conversion of the catalyst at medium and low temperatures.

关键词： Iron-based catalysts Mn-W-Sb In-situ diffused reflectance infrared Fourier transform spectroscopy Reaction mechanism Siderite Low and medium temperature

Electron-beam-induced Surface Reconstructing in Vermicular Alumina

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2017年第4期32卷 888-892页

作者：熊焰 liu wei wang ling Collaborative Innovation Center for Green Light-weight Materials and Processing Hubei Province Key Laboratory of Green Materials for Light Industry Hubei University of Technology W.han 430068 China

The surface reconstructing of vermicular alpha-alumina exposed under electron-beam irradiation was investigated by a scanning electron microscope with 0.5 keV beam energy and by a transmittance electron microscope at room temperature and 90 K, respectively. The in-situ recorded results showed that the present electron-beam-induced surface reconstructing was both electron dose and temperature dependent and accompanied by bulk shape change. The surface reconstruction was explained by an Auger decay process, in which surface composition constancy was proposed by the equilibrium between electron stmulated reduction of Al2O3 and oxidation of aluminum by desorbed oxygen from bulk.

关键词： surface reconstruction electron irradiation alumina

Call admission control scheme for real-time services in packet-switched OFDM wireless networks

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2008年第1期15卷 80-84页

作者： HU Nan WU wei-ling School of Information Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

A call admission control scheme is proposed for real-time services in packet-switched orthogonal frequency division multiplexing （OFDM） wireless cellular networks. The main idea of the proposed scheme is to use maximum acceptance ratio to maintain maximum channel utilization for real-time services according to the desired packet-level and call- level quality-of-service （QoS） requirements. The acceptance ratio is periodically adjusted by using a time discrete Markov chain and Wiener prediction theory according to the varying traffic load. Extensive simulation results show that this algorithm maintains high channel utilization, even as it guarantees packet-level and call-level QoS requirements for real-time services.

关键词： call admission control OFDM packet transmission delay

Image edge detection based on pulse coupled neural network and modulus maxima in non-subsampled contourlet domain

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2018年第3期25卷 55-64页

作者： Hu ling Chang Xia Qian wei School of Mathematics and Information Science North Minzu University

Edge is the intrinsic geometric structure of an image. Edge detection methods are the key technologies in the lleld of image processing. In this paper, a multi-scale image edge detection method is proposed to effectively extract image geometric features. A source image is decomposed into the high frequency directional sub-bands coefficients and the low frequency sub-bands coefficients by non-subampled contourlet transform （NSCT）. The high frequency sub-bands coefficients are used to detect the abundant details of the image edges by the modulus maxima （MM） algorithm. The low frequency sub-band coefficients are used to detect the basic contour line of the image edges by the pulse coupled neural network （PCNN）. The final edge detection image is reconstructed with detected edge information at different scales and different directional sub-bands in the NSCT domain. Experimental results demonstrate that the proposed method outperforms several state-of-art image edge detection methods in both visual effects and objective evaluation.

关键词： edge detection modulus maxima pulse coupled neural network wavelet transform non-subsampled contourlet transform

Interference-aware uplink transmission schemes for multicell MIMO system

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2012年第1期19卷 11-17页

作者： LI Liang QIU ling wei Guo Wireless Information Network Laboratory University of Science and Technology of ChinaHefei 230027China

In this paper we consider interference-aware uplink transmission schemes for multicell multiple-input multiple-output （MIMO） system. Unlike conventional transmission schemes without considering the interference probably caused to other cell, we jointly optimize the transceiver beamforming vectors to maximize the desired signals while removing the intercell interference. Specifically, for a two-cell system where each transmitter is equipped with two antennas, we derive the closed-form expression for the transmit scheme called coordinated beamforming （CBF） via generalized-eigen analysis. Moreover, when asymmetric interference is considered, we give a balancing beamforming （BBF） scheme where the interfering transmitter is to strike a compromise between maximizing the desired signal and minimizing the generated interference. Simulation results show that both schemes perform better than conventional schemes under different scenarios.

关键词： interference-aware MIMO system coordinated beamforrning interference alignment