On adaptive sliding mode control without switching gain overestimation

This paper presents some further results on adaptive sliding mode control (ASMC) for a class of nonlinear systems with bounded uncertain parameters. Given a large initial tracking error, current ASMC design generally produces an unnecessarily large switching gain, consequently leading to a serious chattering problem or a large‐amplitude control jump for the continuous counterpart. To solve such an overadaptation problem, the switching gain adaptation mechanism is first analyzed in this paper, and the adaptation induced by the initial tracking error is suggested to be removed. Then, by exploiting the global sliding mode feature of time‐varying sliding mode control and integral sliding mode control, we present two effective methodologies for ASMC design. The proposed ASMC algorithms ensure that there is no overestimation of the switching gain and the system response is not slowed down when a small switching gain is generated. The validity of the proposed methods is verified by both theoretical analysis and simulation results. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and physicochemical characterization of amphiphilic block copolymer self‐aggregates formed by poly(ethylene glycol)‐block‐poly(ϵ‐caprolactone)

Diblock copolymers with different poly(ε‐caprolactone) (PCL) block lengths were synthesized by ring‐opening polymerization of ε‐caprolactone in the presence of monomethoxy poly(ethylene glycol) (mPEG‐OH, MW 2000) as initiator. The self‐aggregation behaviors and microscopic characteristics of the diblock copolymer self‐aggregates, prepared by the diafiltration method, were investigated by using ¹H NMR, dynamic light scattering (DLS), and fluorescence spectroscopy. The PEG–PCL block copolymers formed the self‐aggregate in an aqueous environment by intra‐ and/or intermolecular association between hydrophobic PCL chains. The critical aggregation concentrations of the block copolymer self‐aggregate became lower with increasing hydrophobic PCL block length. On the other hand, reverse trends of mean hydrodynamic diameters were measured by DLS owing to the increasing bulkiness of the hydrophobic chains and hydrophobic interaction between the PCL microdomains. The partition equilibrium constants (K_v) of pyrene, measured by fluorescence spectroscopy, revealed that the inner core hydrophobicity of the nanoparticles increased with increasing PCL chain length. The aggregation number of PCL chain per one hydrophobic microdomain, investigated by the fluorescence quenching method using cetylpyridinium chloride as a quencher, revealed that 4–20 block copolymer chains were needed to form a hydrophobic microdomain, depending on PCL block length. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3520–3527, 2006     

无三苯CR/SBS/MMA/BA自交联鞋用胶粘剂的研制

采用复合引发剂 ,以N 羟甲基丙烯酰胺 (NAM )及丙烯酸 (AA)为功能单体 ,与CR、苯乙烯 丁二烯嵌段共聚物 (SBS)、甲基丙烯酸甲酯 (MMA)和丙烯酸丁酯 (BA)进行多元共混接枝共聚 ,再配以混合型增粘树脂 ,研制出不含苯、甲苯和二甲苯 (简称三苯 )自交联环保型鞋用胶粘剂。探讨了SBS用量、MMA/BA配比、功能单体NAM及AA用量对胶粘剂粘合性能的影响。结果表明 ,CR/SBS/MMA/BA/AA/NAM自交联型接枝胶粘剂对非极性鞋材的粘合性能明显优于CR/MMA/BA三元接枝胶和CR/SBS/MMA/BA四元接枝胶。     

Effect of Resins on Asphaltene Self‐Association and Solubility

In previous studies, asphaltenes and resins have been treated as two distinct fractions of a crude oil. The asphaltenes were assumed to be the only self‐associating fraction. However, there is evidence that resins also participate in this self‐association. In this study, molar masses of mixtures of asphaltenes and resins were measured with vapour pressure osmometry. Precipitation from the same mixtures dispersed in solutions of toluene and pentane were also measured. The data were modelled with previously developed self‐association and precipitation models. Model results with asphaltenes and resins characterized as a single distribution and as individual components are compared. The data and the modelling suggest that asphaltenes and resins are better characterized as a single distribution of self‐associating components.     

嗜酸氧化亚铁硫杆菌驯化条件的研究

随着办研究氧化亚铁硫杆菌结果表明,最佳培养温度为30℃左右,最佳生长pH为2.0～2.5,最佳生长初始Fe2＋浓为0115mol/L左右,在进行细菌培养时接种量取10%比较恰当。低pH值和高浓度Fe2＋驯化后,在培养温度30℃、初始pH值1.5、初始Fe2＋浓度25g/L条件下,氧化亚铁硫杆菌仍能保持一定的Fe2＋氧化活性,6天Fe2＋氧化率可达82.28%,Fe2＋平均氧化速率达3.43g/L/d,pH值的变化是先上升后下降,最后稳定在1.81。     

“主动适应”：从教育规律视角的认识

当现代大学越来越成为国家实力和国家综合竞争力的象征和标志时,“主动适应”,即大学人才培养主动适应经济社会发展的需要,或大学主动为经济社会发展服务,似乎更多关注现代大学承载的社会责任,而相应较少关注高等教育的规律。然而,“主动适应”是高等教育的办学理念,因而应从高等教育规律上进行认识和把握。     

变通理论在商务英语翻译中的应用

商务英语是一门由"商务"与"英语"有机融合的学科。国际商务英语在词法、句法和风格上的特殊性和针对性说明传统的"全译"已经不能满足现实的需求,而变通翻译理论对一些己经存在的变译现象给出合理的解释,弥补了"全译"的不足。文章试从商务英语翻译入手举例认识变通翻译理论,通过对变通翻译理论的阐述,诠释其在实际翻译工作中的应用。     

水分胁迫下高羊茅幼苗的生理适应性

采用不同浓度PEG6000模拟水分胁迫处理6种高羊茅幼苗,测定了胁迫72 h后叶片叶绿素含量、相对电导率、丙二醛含量、超氧化物歧化酶和过氧化物酶活性等抗旱指标,以综合评价6种高羊茅的抗旱能力。综合分析可知,6种高羊茅的苗期抗旱能力最强的是阳光宝贝。     

Requirements model driven adaption and evolution of Internetware

Today’s software systems need to support complex business operations and processes.The development of the web-based software systems has been pushing up the limits of traditional software engineering methodologies and technologies as they are required to be used and updated almost real-time,so that users can interact and share the same applications over the internet as needed.These applications have to adapt quickly to the diversified and dynamic changing requirements in the physical,technological,economical and social environments.As a consequence,we are expecting a major paradigm shift in software engineering to reflect such changes in computing environment in order to better address the fundamental needs of organisations in this new era.Existing software technologies,such as model driven development,business process engineering,online(re-)configuration,composition and adaptation of managerial functionalities are being repurposed to reduce the time taken for software development by reusing software codes.The ability to dynamically combine contents from numerous web sites and local resources,and the ability to instantly publish services worldwide have opened up entirely new possibilities for software development.In retrospect to the ten years applied research on Internetware,we have witnessed such a paradigm shift,which brings about many changes to the developmental experience of conventional web applications.Several related technologies,such as cloud computing,service computing,cyber-physical systems and social computing,have converged to address this emerging issue with emphasis on different aspects.In this paper,we first outline the requirements that the Internetware software paradigm should meet to excel at web application adaptation;we then propose a requirement model driven method for adaptive and evolutionary applications;and we report our experiences and case studies of applying it to an enterprise information system.Our goal is to provide high-level guidelines to researchers and practitioners to meet the challenges of building adaptive industrial-strength applications with the spectrum of processes,techniques and facilities provided within the Internetware paradigm.     

OpenCOPI: middleware integration for Ubiquitous Computing

In this paper, we present OpenCOPI (Open COntext Platform Integration), a Service-Oriented Architecture-based middleware platform that supports the integration of services provided by distinct sources, ranging from services offered by simple systems to more complex services provided by context-provision middleware. OpenCOPI offers selection and composition mechanisms to, respectively, select and compose services provided by different sources, considering applications of both Quality of Service and Quality of Context requirements. It also offers an adaptation mechanism that enables to adapt the application execution due to service failures, service quality fluctuation and user mobility. OpenCOPI allows the definition of applications in a higher abstraction level by the specification of a semantic workflow that contains abstract activities. This paper illustrates the use of OpenCOPI in an application from the Gas & Oil Industry and it also shows the evaluation of the main mechanisms of OpenCOPI: the service selection, composition, adaptation and workflow execution.