检索结果-南通市图书馆

Rare nanoparticles shine colors with low-power STED

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2022年第7期11卷 1324-1326页

作者： xinzhu Xu Peng xi College of Future Technology Peking UniversityBeijingChina

The effect of cascade amplified depletion in lanthanide upconversion systems boosts their own emission bands inhibition,which facilitates multi-color nanoscopy with only one pair of low-power NIR CW lasers.

关键词： Rare lanthanide bands

Dynamic Adsorption of Toluene on Hierarchical Porous Carbons with Varying Pore Structure

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 Wuhan University of Technology(Materials Science) 2021年第2期36卷 189-195页

作者： YAN xi SINOPEC Research Institute of Safety Engineering Qingdao 266071China

Hierarchical porous carbon material(MMC)was successfully fabricated via hard template synthesis method by carbonization of furfury alcohol within the template(MCM-41).The prepared MMC was studied with characterization methods including scanning electron microscopy(SEM),transmission electron microscopy(TEM),nitrogen adsorption-desorption analyses,and infrared spectral analysis(FTIR).To investigate kinetics of toluene adsorption of hierarchical porous carbon materials,the adsorption performances of these carbon samples with varying pore structure(MC-1,MMC,MMHPC)were analyzed via dynamic *** the Langmuir model and Freundlich equation were employed to correspond with adsorption isotherms to study the adsorption *** experimental results demonstrate that the Langmuir model is more appropriate to describe the adsorption *** capacities of toluene adsorption follow the order of MMCng *** saturation time,interconnected hierarchical pore channels,and large specific surface area make MMC also a promising material for VOCs *** data reveal that the pore channel structure,rational pore distribution,high surface area and reasonable amounts of surface oxygen groups are the main factors contributed to excellent toluene adsorption performance,which proposes theoretical basis for hierarchical porous carbon materials to further engineering application.

关键词： hierarchical porous carbon toluene adsorption pore structure

Application of ionic liquids as a catalyst in the synthesis of polyvinyl butyral(PVB) polymer

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2016年第1期27卷 145-148页

作者： xi-xi Qin Zhi-Lin Cheng College of Chemistry and Chemical Engineering Yangzhou University

Polyvinyl butyral（PVB） polymer was successfully synthesized using ionic liquid（IL） catalyst. The synthesis of PVB was achieved by acetalization of polyvinyl alcohol（PVA） and butyraldehyde（BA） in the presence of [HMIM]~＋HSO_4^-IL catalyst. The FT-IR,~1H NMR, DSC, GPC and SEM characterizations were used to analyze the structure and properties of PVB. The effects of the concentration of PVA in water and the number of reuse cycles on the acetalization degree were investigated. The results indicated that the maximum acetalization degree of PVB obtained using [HMIM]~＋HSO_4^-IL catalyst was up to 72%. The comparison of the commercial PVB and the PVB obtained using [HMIM]~＋HSO_4^-IL catalyst showed that the self-made PVB has a larger molecular weight, higher viscosity, and higher acetalization degree than the commercial PVB.

关键词： Ionic liquids Catalyst PVB Acetalization degree

MLP training in a self-organizing state space model using unscented Kalman particle filter

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1期24卷 141-146页

作者： Yanhui xi Hui Peng School of Information Science and Engineering Central South University College of Electrical and Information Engineering Changsha University of Science and Technology

Many Bayesian learning approaches to the multi-layer perceptron （MLP） parameter optimization have been proposed such as the extended Kalman filter （EKF）. This paper uses the unscented Kalman particle filter （UPF） to train the MLP in a self- organizing state space （SOSS） model. This involves forming augmented state vectors consisting of all parameters （the weights of the MLP） and outputs. The UPF is used to sequentially update the true system states and high dimensional parameters that are inherent to the SOSS moder for the MLP simultaneously. Simulation results show that the new method performs better than traditional optimization methods.

关键词： multi-layer perceptron (MLP) Bayesian method self-organizing state space (SOSS) unscented Kalman particle filter(UPF).

Chronic liver disease is universal in children with biliary atresia living with native liver

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2017年第43期23卷 7776-7784页

作者： Way Seah Lee Sik Yong Ong Hee Wei Foo Shin Yee Wong Chen xi Kong Ru Bin Seah Ruey Terng ng Department of Paediatrics University Malaya Medical Centre Paediatrics and Child Health Research Group University Malaya

AIM To examine the medical status of children with biliary atresia(BA) surviving with native *** In this cross-sectional review,data collected included complications of chronic liver disease(CLD)(cholangitis in the preceding 12 mo,portal hypertension,variceal bleeding,fractures,hepatopulmonary syndrome,portopulmonary hypertension) and laboratory indices(white cell and platelet counts,total bilirubin,albumin,international normalized ratio,alanine aminotransferase,aspartate aminotransferase,γ-glutamyl transpeptidase). Ideal medical outcome was defined as absence of clinical evidence of CLD or abnormal laboratory indices. RESULTS Fifty-two children [females = 32,62%; median age 7.4 years,n = 35(67%) older than 5 years] with BA(median age at surgery 60 d,range of 30 to 148 d) survived with native liver. Common complications of CLD noted were portal hypertension(40%,n = 21; 2 younger than 5 years),cholangitis(36%) and bleeding varices(25%,n = 13; 1 younger than 5 years). Fifteen(29%) had no clinical complications of CLD and three(6%) had normal laboratory indices. Ideal medical outcome was only seen in 1 patient(2%). CONCLUSION Clinical or laboratory evidence of CLD are present in 98% of children with BA living with native livers after hepatoportoenterostomy. Portal hypertension and variceal bleeding may be seen in children younger than 5 years of age,underscoring the importance of medical surveillance for complications of BA starting at a young age.

关键词： Biliary atresia Medical status Chronic liver disease

Evaluation of drag force on a nonuniform particle distribution with a meshless method

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

Particuology 2011年第3期9卷 288-297页

作者： xi Wang Changfu You Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Thermal Engineering Tsinghua University Beijing 100084 China

A meshless Element-Free Galerkin （EFG） method was used to directly simulate the fluidization process in two dimensions. The drag force on particles was obtained by integrating the stress and shear forces on the particle surfaces. The results show that meshless methods are capable of dealing with real particle collisions, thus are superior to most mesh-based methods in reflecting the fluidization process with frequent particle collisions and suitable void fractions. Particle distribution greatly influences the drag coefficients even for the same voidage, that is, there are large differences in the average drag coefficients between nonuniform and uniform particle distributions. Different compacting directions also have different regu- larities, so conventional formulas such as ＇Wen and Yu＇ and ＇Felice＇ models have some deviations in such nonuniform distributions. To evaluate the influence of the nonuniformity, the drag force in multiple particle systems was simulated by using nonuniformity coefficients, Cvx and Cvy, to quantitatively describe the nonuniform distribution in different directions. Drag force during fluidization can be successfully evaluated by the use of Cvx alone.

关键词： Meshless method Drag force Nonuniform particle distribution Nonuniformity coefficient

Type Synthesis of Walking Robot Legs

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2018年第1期31卷 53-65页

作者： Da xi Feng Gao State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University

Walking robots use leg structures to overcome obstacles or move on complicated terrains. Most robots of current researches are equipped with legs of simple structure. The specific design method of walking robot legs is seldom studied. Based on the generalized-function(GF) set theory, a systematic type synthesis process of designing robot legs is introduced. The specific mobility of robot legs is analyzed to obtain two main leg types as the goal of *** synthesis problem is decomposed into two stages, actuation and constraint synthesis by name,corresponding to the combinatorics results of linear Diophantine equations. Additional restrictions are discussed to narrow the search range to propose practical limb expressions and kinematic-pair designs. Finally, all the fifty-one leg structures of four subtypes are carried out, some of which are chosen to make up robot prototypes, demonstrating the validity of the method. This paper proposed a novel type synthesis methodology, which could be used to systematically design various practical robot legs and the derived robots.

关键词： Type synthesis Robot leg GF set Number synthesis Linear Diophantine equation

Resilient predictive control for a class of uncertain time-delay systems

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2007年第2期18卷 334-340页

作者： Zhang Qunliang xi Yugeng Dept. of Automation Shanghai Jiaotong Univ. Shanghai 200240 P.R. China

In practice, gain perturbations of controllers which axe caused by actuator degradation and other reasons often lead to performance degradation. They are capable of violating the closed-loop stability. For a system with constrained inputs, the actual controllers might exceed their limits because of gain perturbations. By the reason, this article considers the problem of resilient predictive control for a class of uncertain time-delay systems. By describing the gain perturbation as a time-varying uncertainty, the sufficient conditions to ensure the closedloop stability and the input constraints are derived. Additionally, an approach to design the resilient predictive controllers is presented in terms of LMI. Finally, the simulation shows that the proposed approach is very effective.

关键词： Gain perturbations Constraints Resilient predictive controllers Stability.

ON SOLUTIONS OF MATRIX EQUATION AXAT ＋ BYBT=C

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2005年第1期23卷 17-26页

作者： Yuan-beiDeng xi-yanHu ICMSEC AcademyofMathematicsandSystemSciencesChineseAcademyofSciencesBeijing100080China CollegeofMathematicsandEconometrics HunanUniversityChangsha310082China

By making use of the quotient singular value decomposition (QSVD) of a matrix pair,this paper establishes the necessary and sufficient conditions for the existence of and the expressions for the general solutions of the linear matrix equation AXA^T+BYB^T=C with the unknown X and Y, which may be both symmetric, skew-symmetric, nonnegativede finite, positive definite or some cross combinations respectively. Also, the solutions of some optimal problems are derived.

关键词： matrix equation matrix norm QSVD constrained condition optimal problem