Adaptive synchronization of chaotic Colpitts circuits against parameter mismatches and channel distortions

In this work, synchronization of chaotic Colpitts circuits, using adaptive controllers to combat circuit parameter mismatches and channel distortions, is studied by numerical simulations. Synchronization errors caused by different main circuit components are compared, and compensation for time-constant and time-varying circuit parameter mismatches is demonstrated. Different kinds of channel distortions, including time-constant and time-varying channel attenuation, Additive White Gaussian Noise (AWGN) are all investigated by numerical simulations and discussed. Simulation results indicated that the synchronization performance of chaotic Colpitts circuits can be greatly improved by applying adaptive controllers when parameter mismatches and channel attenuation are considered as time-constant or time-varying, but have no obvious enhancements regarding the effect on AWGN channel.     

股票市场数据的统计实证分析

多元统计分析方法是研究股票价格的一般方法,本文利用统计分析方法考察并确定上市公司与股票价格相关的基本因素,利用聚类分析与因子分析两种分析方法来进行实例研究,并判断出各公司股票质量特征,为投资者的投资提供科学严谨的建议。     

大学之道:求学问是,引领未来——反思大学的服务职能

学生素质的格式化和大学教育的职业化表明,社会似乎更重视学生的“动手能力”和“短期适应能力”,忽视学生的发展后劲和创新能力。对此,我们不能不看到,作为社会分工的产物,作为教育的顶层组织,大学不能一般地定位于“面向”未来,大学还必须本着超脱的姿态和高度的社会责任感,引领未来社会的发展。引领未来需要新人,塑造新人离不开求学问是。因此,大学应该且只能通过“求学问是,树人铸魂,引领未来”而通往大学之道。求学问是,是大学与技工学校等其他教育机构的根本区别;树人铸魂,是大学区别于其他社会机构的核心要素;而引领未来,是“教育必须面向未来”这一原理的体现,也是大学释放其批判功能的体现。因此,引领未来是大学的灵魂,是大学职能的回归与当代化。     

孕育还是新生：大学职能评析

大学（高等学校）职能（功能）与高等教育功能（职能）有什么样的区分，对此学术界争论颇多。在评析近年来对大学职能演变研究的基础上，提出了大学职能的概念及特征，指出大学职能是处在孕育阶段还是已经新生，应以发展的眼光、正确的时空观、辩证的思想和协调的观点来判断。     

Simple model for gas holdup and liquid velocity of annular photocatalytic external-loop airlift reactor under both bubble and developing slug flow

Based on the momentum conservation approach, a theoretical model was developed to predict the superficial liquid velocity, and a correlation equation was established to calculate the gas holdup of an annular external- loop airlift reactor(AELAR)in the bubble flow and developing slug flow pattern. Experiments were performed by using tap-water and silicone oil with the viscosity of 2.0 mm²/s(2cs-SiO)and 5.0 mm²/s(5cs-SiO)as liquid phases. The effects of liquid viscosity and flow pattern on the AELAR performance were investigated. The predictions of the proposed model were in good agreement with the experimental results of the AELAR. In addition, the comparison of the experimental results shows that the proposed model has good accuracy and could be used to predict the gas holdup and liquid velocity of an AELAR operating in bubble and developing flow pattern.     

Nobel Prize in Physics 2006

The discovery of the cosmic microwave background radiation in 1965 was a defining moment in the history of cosmology — the science that deals with the universe as a whole, its origin, evolution and future. This discovery was recognized with Nobel Prizes to Penzias and Wilson in 1978. The Nobel Prize in Physics for 2006 further acknowledged the importance of the study of this background radiation. The precise measurement of the spectrum of this radiation and its variation across the sky have helped our understanding of the evolution of structures in the universe. This article explains these discoveries and their importance. T Padmanabhan is a professor at IUCAA, Pune. He is interested in all aspects of theoretical physics, and especially in those in which gravity plays a role.     

Noise assisted directed motion at the molecular level — 2

The term noise is used to describe fluctuations about the mean deterministic stationary value of a physical quantity. It is now being increasingly realised that noise is an important ingredient to bring order in dynamical processes. Though it appears counterintuitive, noise seems to help in directing transport processes in biological systems at the molecular level. In Part 2 of the article, we discuss some more examples of noise assisted directed motion.     

吉登斯的社会福利思想

吉登斯认为福利国家面临的风险是人为风险，福利国家的危机是风险管理危机，并非简单的财政危机。据此，他提出要彻底改革英国的消极福利政策为积极福利政策，强调“无责任即无权利”的新原则，主张个人，集体和国家共同建设社会投资型国家。     

创新创业教育是适应时代和发展之需——关于把创新创业教育作为高职教育必修课的思考(之一)

伴随着经济全球化和社会主义市场经济体制的建立,我们进入了新的创新创业时代。这一时代的一个鲜明特点是各种竞争日趋激烈,生存和发展的竞争尤为突出,其实质是创新创业力的竞争。高职教育如何发挥优势,打造特色?开展创新创业教育是时代和现实的必然要求,是高职教育教学改革的重要内容,是高职院校学生自我发展的迫切需要,是高职院校服务社会职能的重要体现,是新时期思想政治工作结合着经济工作一道去做的题中应有之义。