检索结果-南通市图书馆

A triple-exposure color PIV technique for pressure reconstruction

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

Science China(Technological Sciences) 2017年第1期60卷 1-15页

作者： WANG ZhongYi gao qi WANG JinJun Key Laboratory of Fluid Mechanics Ministry of Education Beijing University of Aeronautics and Astronautics Beijing 100191 China

The study developed a triple-exposure color particle image velocimetry(TE-CPIV) technique associated with pressure reconstruction, and validated its feasibility. A light source with the three primary colors of red, green, and blue(R, G, and B) is produced in a time sequence by a liquid crystal display(LCD) projector. Particle images at three different instants under the color illuminations are captured in one snapshot using a color digital single-lens reflex(SLR) camera with a complementary metal-oxide semiconductor(CMOS) sensor. A contamination correction algorithm based on a specific calibration is performed on the different color layers(R layer, G layer, and B layer) of the raw color image to reduce the contaminated intensity of each color illumination on the other two color layers. The corrected intensity generates three new color layers, from which a standard cross-correlation process in the classical PIV method is used to obtain two velocity fields. Eventually, an instantaneous pressure field is reconstructed from the two velocity fields. The feasibility of TE-CPIV was tested by two experiments with a solid body rotation flow and a cylinder wake flow. The results show acceptable accuracy and robustness of the new technique. The idea of the TE-CPIV is believed to provide a simple and effective way of estimating a pressure field with low cost and high convenience.

关键词： triple exposures color PIV pressure reconstruction

FEM Simulation of the Hydrogen Diffusion in X80 Pipeline Steel During Stacking for Slow Cooling

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2014年第3期27卷 416-421页

作者： Zhenyi Huang qi shi Fuqiang Chen Yunfeng shi School of Metallurgical Engineering Anhui University of Technology Heavy Plate Mill Baoshan Iron and Steel Co. Ltd

The influence of temperature on the hydrogen diffusion behavior in X80 pipeline steel during stacking for slow cooling was studied using electrochemical penetration method, the temperature field and the hydrogen diffusion in this pipeline steel during stacking for slow cooling were simulated by ABAQUS finite element method （FEM） software. The results show that in this process there is a reciprocal relationship between the natural logarithm of hydrogen diffusion coefficient and temperature. The cooling rate decreases gradually with the increase of steel plate thickness. The hydrogen content is higher at high temperature （500-400 ℃） than that in low temperature region （300-100 ℃）. The FEM simulation results are consistent with the experimental ones, and the model can be used to predict the hydrogen diffusion behavior in industrial production of X80 pipeline steel.

关键词： X80 pipeline steel Stacking Slow cooling Hydrogen diffusion Finite element method (FEM) Electrochemical penetration

Cognition-Based Interactive Phases and Strategies in Teaching Academic Reading

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology 2017年第1期15卷 33-40页

作者： Zhao gao Shan gao qi Yang School of Foreign Languages University of Electronic Science and TechnologyChengdu 610054China

Academic English reading requires deeper cognitive involvement in addition to language proficiency and plays a vital role in moulding a critical mindset. However, cognitive progress is seldom targeted in classroom teaching. This study proposed a teaching method of three reading phases in terms of cognitive mechanism and communicative teaching *** university freshmen of non-English major participated in the study, who were taking the course of Academic English Reading in the 2nd semester. The data were collected from self-report Research Skills Assessment twice and semi-structured interview, and analyzed with paired sample t test and Pearson correlation. The results showed that 1） “critical thinking”, “organizing ideas”, and “finding information” were believed to improve significantly at the end of the course; 2） reading skill was associated with writing skill and the sense of “big picture” in self perception; 3） the cognition-based interactive reading instruction was acknowledged to be conducive to academic reading. It complements Academic English reading pedagogy by juxtaposing the need for both individual cognition and group interaction in classroom teaching.

关键词： Reading classroom skill proficiency interview thinking acknowledged instruction comprehension cognition

Event-triggered robust MPC of nonlinear cyber-physical systems against DoS attacks

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2022年第1期65卷 22-38页

作者： qi SUN Jicheng CHEN Yang shi Department of Mechanical Engineering University of Victoria

This paper proposes an event-triggered robust nonlinear model predictive control(NMPC) framework for cyber-physical systems(CPS) in the presence of denial-of-service(Do S) attacks and additive disturbances. In the framework, a new robustness constraint is introduced to the NMPC optimization problem in order to deal with additive disturbances, and a packet transmission strategy is designed for NMPC such that Do S attacks can be tackled. Then, an event-triggered mechanism, which accommodates Do S attacks occurring in the communication network, is proposed to reduce the communication cost for resource-constrained CPSs. Besides, we prove that the NMPC algorithm is recursively feasible and the closed-loop system is input-to-state practical stable under some sufficient conditions. Simulation examples and comparisons are conducted to show the effectiveness of the proposed NMPC algorithm.

关键词： cyber-physical systems nonlinear model predictive control event-triggered mechanism robust control denial-of-service attacks

同方期刊数据库

Construction of Soluble Mamu-B~*1703,a Class I Major Histocompatibility Complex of Chinese Rhesus Macaques,Monomer and Tetramer Loaded with a Simian Immunodeficiency Virus Peptide

在线全文

学校读者我要写书评

暂无评论

Cellular & Molecular Immunology 2009年第2期6卷 117-122页

作者： Dongyun Ouyang Xiaoying Wang Xianhui He Lihui Xu Huanjing shi qi gao He Guo Institute of Tissue Transplantation and Immunology College of Life Science and Technology Jinan University. Guangzhou 510632. China Institute of Bioengineering College of Life Science and Technology Jinan University Guangzhou 510632 China

Chinese-descent rhesus macaques have become more prevalent for HIV infection and vaccine investigation than Indian-origin macaques. Most of the currently available data and reagents such as major histocompatibility complex （MHC） class I tetramers, however, were derived from Indian-origin macaques due to the dominant use of these animals in history. Although there are significant differences in the immunogenetic background between the two macaque populations, they share a few of common MHC class I alleles. We reported in this study the procedure for preparation of a soluble Mamu-B＊1703 （a MHC class I molecule of Chinese macaques） monomer and tetramer loaded with a dominant simian immunodeficiency virus （SIV） epitope IW9 （IRYPKTFGW） that was identified to be Mamu-B＊1701-restricted in Indian macaques. The DNA fragment encoding the Mamu-B＊1703 extracellular domain fused with a BirA substrate peptide （BSP） was amplified from a previously cloned cDNA and inserted into a prokaratic expression vector. In the presence of the antigenic peptide IW9 and light chain β2-microglobulin, the expressed heavy chain was refolded into a soluble monomer. After biotinylation, four monomers were polymerized as a tetramer by phycoerythrin-conjugated streptavidin. The tetramer, having been confirmed to have the right conformation, was a potential tool for investigation of antigen-specific CD8^＋ T-lymphocytes in SIV vaccine models of Chinese macaques. And our results also suggested that some antigenic peptides reported in Indian-origin macaques could be directly recruited as ligands for construction of Chinese macaque MHC tetramers.

关键词： Mamu-B* 17 MHC class I rhesus macaque tetramer

Dynamics modeling and pressure control of composites tape winding system based on LQSMC

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第2期33卷 740-748页

作者： qi HONG Yaoyao shi Danni LU The Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of Education Northwestern Polytechnical UniversityXi’an 710072China

Pressure fluctuations during the composite fiber winding process seriously affect the produces compactness strength,fatigue resistance,stress uniformity,and resin *** accuracy of pressure control systems is affected by nonlinear disturbances,such as friction,parameter perturbation,and measurement noise.A robust control algorithm based on linear quadratic optimal control and sliding mode control(LQSMC)is proposed to overcome these *** method is based on the system state space expression and linear quadratic optimal *** state space model of the system is improved by using a Kalman filter and control input for state estimation,and a new sliding surface equation is *** ameliorated control algorithm exhibits good performance and can effectively suppress sliding mode control(SMC)*** and experimental results show that LQSMC offers high control precision,much stronger antiinterference,and robustness,which can effectively improve the positioning and tracking accuracy of a pressure control system compared with linear quadratic optimal control(LQC).The winding pressure control precision is improved by 45%to 50%.The results show that the porosity of composite fiber tape winding products decreased thanks to our method.

关键词： Composites tape winding Dynamics modeling Kalman filter LQSMC Pressure control

Equilibrium scour depth at offshore monopile foundation in combined waves and current

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2014年第5期57卷 1030-1039页

作者： qi WenGang gao FuPing Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences

Unlike the pier scour in bridge waterways,the local scour at offshore monopile foundations should take into account the effect of wave-current *** the condition of wave-current coexistence,the water-soil interfacial scouring is usually coupled with the pore-pressure dynamics inside of the *** aforementioned wave/current-pile-soil coupling process was physically modeled with a specially designed flow-structure-soil interaction *** results indicate that superimposing a current onto the waves obviously changes the pore-pressure and the flow velocity at the bed around the *** concomitance of horseshoe vortex and local scour hole around a monopile proves that the horseshoe vortex is one of the main controlling mechanisms for scouring development under the combined waves and *** on similarity analyses,an average-velocity based Froude number(Fra)is proposed to correlate with the equilibrium scour depth(S/D)at offshore monopile foundation in the combined waves and *** empirical expression for the correlation between S/D and Fra is given for predicting equilibrium scour depth,which may provide a guide for offshore engineering practice.

关键词： monopile pore-pressure scour depth combined waves and current Froude number

An East Asian Monsoon in the Mid-Pliocene

在线全文

学校读者我要写书评

暂无评论

Atmospheric and Oceanic Science Letters 2012年第6期5卷 449-454页

作者： YAN qing ZHANG Zhong-shi gao Yong-qi Nansen-Zhu International Research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Bjerknes Centre for Climate Research UniResearch Bergen 5007 Norway Nansen Environmental and Remote Sensing Center Bergen 5006 Norway

In this study, the authors simulate the East Asian climate changes in the mid-Pliocene (～3.3 to 3.0 Ma BP) with the Community Atmosphere Model version 3.1 (CAM3.1) and compare the simulated East Asian monsoon with paleoclimate data. The simulations show an obvious warming pattern in East Asia in the mid-Pliocene compared with the pre-industrial climate, with surface air temperature increasing by 0.5 4.0°C. In the warm mid-Pliocene simulation, the East Asian Summer Monsoon (EASM) becomes stronger, while the East Asian Winter Monsoon (EAWM) is similar relative to the pre-industrial climate. Compared with the paleoclimate data, our simulations depict the intensified EASM well but cannot reproduce the weakened EAWM. This model-data discrepancy may be attributed to the uncertainty in the reconstructed mid-Pliocene sea surface temperature.

关键词： East Asian monsoon mid-Pliocene warm period paleoclimate data

Context-aware location discovery exchange in a ubiquitous environment

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6期19卷 73-78页

作者： LIU qi gao Feng Jiangsu Engineering Center of Network Monitoring Nanjing University of Information Science & Technology School of Information Science and Technology Shijiazhuang Tiedao University

It becomes challenging in order to represent, discover and exchange location information in a ubiquitous environment due to dynamic movement and interaction between mobile nodes inside. In this paper, a new method is presented in order to make location information context-aware so that organizing the format of location information and maintaining the communication between direct connected nodes in a ubiquitous environment is enabled. The structure of a contextual location information repository and a context information communication protocol is manipulated to implement the proposed features. According to the simulation results in network simulator version2 （NS2）, the new method has depicted good discovery success ~nd consumed efficient service discovery bandwidth. Other network traffic, i.e. transmission control protocol, （TCP） has been simulated in the scenarios but the new location-aware method has shown its robustness with continuous context discovery process.

关键词： context-aware ubiquitous computing location-aware service discovery