检索结果-南通市图书馆

NURBS curve blending using extension

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

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第4期10卷 570-576页

作者： Yong-jin LIU rong-qi qiu Xiao-hui LIANG Tsinghua National Lab for Information Science and Technology Tsinghua University Beijing 100084 China State Key Lab of Virtual Reality Technology and Systems Beihang University Beijing 100191 China

Curve and surface blending is an important operation in CAD systems, in which a non-uniform rational B-spline （NURBS） has been used as the de facto standard. In local comer blending, two curves intersecting at that comer are first made disjoint, and then the third blending curve is added-in to smoothly join the two curves with G^1- or G^2-continuity. In this paper we present a study to solve the joint problem based on curve extension. The following nice properties of this extension algorithm are exploited in depth：（1） The parameterization of the original shapes does not change; （2） No additional fragments are created. Various examples are presented to demonstrate that our solution is simple and efficient.

关键词： Curve blending Curve fairing Curve extension Non-uniform rational B-spline (NURBS)

Evaluation of packet loss impairment on streaming video

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第Z1期7卷 131-136页

作者： RUI Hua-xia LI Chong-rong qiu Sheng-ke Network Research Center Tsinghua University Beijing 100084 China Network Research Center Tsinghua University Beijing 100084 China Network Research Center Tsinghua University Beijing 100084 China

Video compression technologies are essential in video streaming application because they could save a great amount of network resources. However compressed videos are also extremely sensitive to packet loss which is inevitable in today's best effort IP network. Therefore we think accurate evaluation of packet loss impairment on compressed video is very important. In this work, we develop an analytic model to describe these impairments without the reference of the original video (NR) and propose an impairment metric based on the model, which takes into account both impairment length and impairment strength. To evaluate an impaired frame or video, we design a detection and evaluation algorithm (DE algorithm) to compute the above metric value. The DE algorithm has low computational complexity and is currently being implemented in the real-time monitoring module of our HDTV over IP system. The impairment metric and DE algorithm could also be used in adaptive system or be used to compare diffeient error concealment strategies.

关键词： Packet loss, Video streaming, MPEG-2 video, Video quality, No-Reference

Attenuation of Metal Bioavailability in Acidic Multi-Metal Contaminated Soil Treated with Fly Ash and Steel Slag

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2012年第4期22卷 544-553页

作者： qiu Hao GU Hai-Hong HE Er-Kai WANG Shi-Zhong qiu rong-Liang School of Environmental Science and Engineering Sun Yat-sen UniversityGuangzhou 510275(China) Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology Guangzhou 510275(China)

A pot experiment was conducted with multi-metal （Pb, Cd, Cu, and Zn） contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes （fly ash and steel slag）. The efficiency of amendments- induced metal stabilization was evaluated by diffusive gradients in thin films （DGT）, sequential extraction, and plant uptake. The stability of remediation was assessed by an acidification test and by chemical equilibrium modeling. Addition of fly ash （20 g kg-1） and steel slag （3 g kg-1） resulted in similar increase in soil pH. Both amendments significantly decreased the concentrations of metals measured with DGT （CDGT） and the metal uptake by Oryza sativa L. Significant correlations were found between CDGT and the concentration of a combination of metal fractions （exchangeable, bound to carbonates, and bound to Fe/Mn oxides）, unraveling the labile species that participate in the flux of metal resupply. The capability of metal resupply, as reflected by the R （ratio of CDGT to pore water metal concentration） values, significantly decreased in the amended soils. The CDGT correlated well with the plant uptake, suggesting that DGT is a good indicator for bioavailability. Acidification raised the extractable metal concentration in amended soil but the concentration did not return to the pre-amendment level. Equilibrium modeling indicated that the soil amendments induced the precipitation of several Fe, A1 and Ca minerals, which may play a positive role in metal stabilization. Chemical stabilization with alkaline amendments could be an effective and stable soil remediation strategy for attenuating metal bioavailability and reducing plant metal uptake.

关键词： acidification chemical stabilization diffusive gradients in thin films (DGT) heavy metal remediation

Physical and chemical effects of phosphorus-containing compounds on laminar premixed flame

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第9期27卷 360-373页

作者： Yongfeng Yin Yong Jiang rong qiu and Caiyi Xiong state Key Laboratory ofF ire Science University of Science and Technology of ChinaHefei 230026China

Phosphorus-containing compounds are the promising halon alternatives for flame inhibitions. However, some literatures suggested that the phosphorus-related inhibitors may behave as the unfavorable ones that will increase the burning velocity under lean-burn conditions, and this indeed posed potential threats to the fire prevention and fighting. To seek deeper insights into the reaction process, a numerical investigation was actualized to study the phosphorus-related effects on methane-air flames. By replacing a phosphorus-related inhibitor with the corresponding decomposed molecules, the detailed promoting and inhibiting effects of combustion were separated from the general chemical effect. A comparative study was carried out to identify the interaction between the two effects under different combustion conditions. It is observed that the promoting effect becomes the dominant factor during the reaction process when the equivalence ratio is smaller than 0.60. In this lean-burn condition, the exothermic reactions were faster than the others within the reaction chains due to the reduction of radical recombination in hydrocarbon oxidation. The results are believed to be useful for the further application and improvement of flame inhibitors.

关键词： phosphorus-containing compounds flame inhibition chemical effect burning velocity

Neuroprotective effects of receptor imidazoline 2 and its endogenous ligand agmatine

在线全文

学校读者我要写书评

暂无评论

Neuroscience Bulletin 2006年第3期22卷 187-191页

作者： Wei-Wen qiu rong-Yuan ZHENG Department of Neurology the First Affiliated Hospital of Wenzhou Medical College Wenzhou 325000 China

Receptor imidazoline 2 （I2） is one of the imidazoline receptors with high affinity for [^3H]-idazoxan. Receptor I2, being classified into I2A and I28 subtypes, is mainly localized to the outer membrane of mitochondria in liver, kidney and brain. Receptor I2, displaying high similarity of sequence with monoamine oxidase-B （MAO-B）, is structurally related to MAO-B, but the I2 imidazoline binding site （IEBS） with ligand is distinct from the catalytic site of MAO-B. Agmatine is the endogenous ligand of receptor I2. Accumulating evidence have revealed that the activation of receptors I2 may produce neuroprotective effects by increasing expression of glial fibriUary acidic protein （GFAP） in astrocytes, inhibiting activity of MAO, reducing calcium overload in cells. Agmatine exerts neuroprotection against ischemia-hypoxia, injury, glutamateinduced neurotoxicity by activating imidazoline receptors, blocking N-methyl-D-aspartate （NMDA） receptor, inhibiting all isoforms of nitric oxide synthase （NOS）, and selectively blocking the voltage-gated calcium channels （VGCC）. It would be expected that agmatine is one of the potential neuroprotective agents.

关键词： receptor imidazoline ligand agmatine neuroprotection

Specific Heat of a Two-Layer Magnetic Superlattice

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2009年第11期52卷 969-973页

作者： qiu rong-Ke LIANG Jing ZHAO Jian YING Cai-Hong Shenyang University of Technology Shenyang 110023 China

The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one *** is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,theapplied magnetic field,and the temperature all affect the specific heat of these *** both the ferromagneticand ferrimagnetic superlattices,the specific heat decreases with increasing the spin quantum number,the absolutevalue of interlayer exchange coupling,intralayer exchange coupling,and anisotropy,while it increases with increasingtemperature at low *** an applied magnetic field is enhanced,the specific heat decreases in the two-layerferromagnetic superlattice,while it is almost unchanged in the two-layer ferrimagnetic superlattice at low fieldrange at low temperatures.

关键词： ferromagnetic and ferrimagnetic superlattice specific heat anisotropy spin quantum numbers interlayer and intralayer exchange couplings applied magnetic field

A Fuzzy-based Methodology for an Aggregative Environmental Risk Assessment of Restored Soil

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2014年第2期24卷 220-231页

作者： WANG Shi-Zhong ZHAO Zhi-Hao XIA Bing qiu Hao J.L.MOREL qiu rong-Liang School of Environmental Science and Engineering Sun Yat-sen University Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology Laboratoire Sols et Environnement UMR 1120 ENSAIA-INPL/INRA

Environmental risks pertaining to contaminated soils have been well studied,while little attention has been paid to the risks of the soils after remediation. In this study,a concept model developed based on fuzzy set theory was applied to evaluate the uncertainties of three risk indicators,namely,plant growth,groundwater safety and human health,of a restored site that had been previously polluted by heavy metals. The concept model classified the grade and importance of risk factors by an 11-level ranking system and was able to yield a comprehensive risk result rather than multi-risk results for complex risk indicators. Modeling results showed that the risks to the three indicators were effectively reduced after the remediation. Moreover,great sensitivity of the risks was found related to the weight distribution among the three risk indicators. In general,the risks of both polluted and restored soils to the environment were in the order of groundwater safety > plant growth > human health. The model was proved to solve the problems of multi-risk results due to complex risk indicators that previously encountered by other researchers,which made it helpful in decision-making and management of restored soils.

关键词： fuzzy set theory heavy metals remediated risk assessment weight distribution

Bending mechanical property and failure mechanisms of woven carbon fiber-reinforced aluminum alloy composite

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2016年第12期35卷 915-919页

作者： qiu-rong Yang Jin-Xu Liu Shu-Kui Li Teng-Teng Wu School of Materials Science and Engineering Beijing Institute of Technology

Copper-coated woven carbon fiber-reinforced aluminum alloy composite was prepared by spark plasma sintering （SPS）. Microstructure, three-point bending mechanical property, and the failure mechanisms of the composite were investigated. Microstructure observation shows that the carbon fibers bond compactly with matrix alloy. Compared with the matrix aluminum alloy, the bending strength, ductility, fracture energy, and cracking resistance of the composite are evidently improved. Microstructure analyses reveal that the high specific strength of carbon fibers and transfer of stress from matrix alloy to carbon fibers are responsible for the increase of the composite bending strength. The expanding of cracks is restrained, and cracking resistance of the composite is improved by adding woven carbon fiber. Attributed to the carbon fibers＇ debonding, cracks deflection, and multipath propagation mechanisms, the fracture energy of the composite increases.

关键词： Carbon fibers Aluminum alloy Composites Bending strength Mechanisms

Multidimensional biomarkers for multiple system atrophy:an update and future directions

在线全文

学校读者我要写书评

暂无评论

Translational Neurodegeneration 2023年第1期12卷 357-373页

作者： Linlin Wan Sudan Zhu Zhao Chen rong qiu Beisha Tang Hong Jiang Department of Neurology Xiangya HospitalCentral South UniversityChangsha 410008China Department of Neurology The Third Xiangya HospitalCentral South UniversityChangsha 410013China Key Laboratory of Hunan Province in Neurodegenerative Disorders Central South UniversityChangsha 410008China National Clinical Research Center for Geriatric Disorders Xiangya HospitalCentral South UniversityChangsha 410008China Department of Radiology Xiangya HospitalCentral South UniversityChangsha 410008China Hunan International Scientific and Technological Cooperation Base of Neurodegenerative and Neurogenetic Diseases Changsha 410008China School of Computer Science and Engineering Central South UniversityChangsha 410083China National International Collaborative Research Center for Medical Metabolomics Central South UniversityChangsha 410008China

Multiple system atrophy(MSA)is a fatal progressive neurodegenerative *** are urgently required for MSA to improve the diagnostic and prognostic accuracy in clinic and facilitate the development and monitoring of disease-modifying *** recent years,significant research efforts have been made in exploring multidimensional biomarkers for ***,currently few biomarkers are available in *** this review,we systematically summarize the latest advances in multidimensional biomarkers for MSA,including biomarkers in fluids,tissues and gut microbiota as well as imaging *** directions for exploration of novel biomarkers and promotion of implementation in clinic are also discussed.

关键词： Multiple system atrophy Biomarker Fluid Tissue Gut microbiota Imaging