Global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback

This paper presents both analytical and numerical studies on the global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback. Based on a detailed analysis of the stability switches of the trivial equilibrium of the system, the stability charts are given in a parameter space consisting of the time delay and the feedback gains. The center manifold reduction and the normal form method are used to study Hopf bifurcations with respect to the time delay. To gain an insight into the pe...     

Structure Characterization of Silk Fibroin Crystalline Domain Polypeptides Expressed in Escherichia coli

The molecular conformations of four silk fibroin crystalline analogues [GAGAG-X] 16(G,Gly;A,Ala;X=Ala,Ser,Tyr or Val,designated eGA,eGS,eGY or eGV),carried out using molecular design and expressed by Escherichia coil(E.coli),were evaluated by Raman spectra analysis.The abilities of forming β-sheet structure were determined by thioflavin T(ThT) fluorescence spectra analysis.In terms of molecular conformation,except eGY that could not form significant typical molecular conformation,eGS and eGV were mainly com...     

In-plane elastic stability of fixed parabolic shallow arches

The nonlinear behavior of fixed parabolic shallow arches subjected to a vertical uniform load is investigated to evaluate the in-plane buckling load.The virtual work principle method is used to establish the non-linear equilibrium and buckling equations.Analytical solutions for the non-linear in-plane symmetric snap-through and antisymmetric bifurcation buckling loads are obtained.Based on the least square method,an approximation for the symmetric buckling load of fixed parabolic arch is proposed to simplif...     

推进高校党建工作创新 加强青年教师队伍建设

高校教师,作为培养社会主义事业接班人的特殊而重要的群体,政治素质如何,将直接影响到高等教育的发展方向和学生培养的质量,关系到高校的发展和祖国的未来。因此,必须加强青年教师党建工作,建设一支高素质、高质量的青年教师队伍。本文从加强青年教师党建工作的重要意义及具体的方法和途径进行论述。     

以"理科实验班"为突破口全面推进我院教育教学改革

近年来,我院科研及学科创新体系的建设已取得较大的进展,如何利用这一优势来提高我院的教学质量,建立适合我院实际的教学创新体系,是一项艰巨而长期的工程.本文拟就我院首个"理科实验班"的开设为例,浅述我们的设想,以抛砖引玉,从深层次推动我院教育教学的改革.     

溶剂法合成亚磷酸二甲酯

以三氯化磷和甲醇为原料，用溶剂法合成了亚磷酸二甲酯，着重探讨了反应物的摩尔比、反应温度、反应时间和溶剂用量等对产品收率的影响，得出了优化的工艺条件。     

Auto-measuring System of 3-Dimensional Human Body

To realize the automation of fashion industry measuring, designing and manufacturing, the auto-measurement of 3D size of human body is of great importance.The auto-measurement system of 3D human body based on Charge Coupled Devices ( CCD) and infrared sensors is presented in this paper. The system can measure the bare size of human body that excludes the effect of clothing quickly and accurately.     

离子沟道自由电子激光的自发辐射谱

计算了离子沟道中的库仑场,在小振幅条件下导出了相对论性电子束的运动轨迹,运用麦迪定理研究了电子的自发辐射谱分布,并对结果进行了讨论.     

美国文化的霸权主义渊源和文化霸权主义

文章从分析美国文化中的使命观着手，揭示了美国文化霸权主义的渊源，内涵及表现，并指出了其不合理以及走向破产的必然性。     

非名牌高校实现可持续发展的几点思考

非名牌高校要完全摆脱旧有的教育模式，实现可持续发展，必须吸纳、兼容改革开放以来社会广泛认可的新思想、新观念，如效益观念、人本理念、品牌意识、法人观念、公关意识等，从而能以全新的思维方式迎接新世纪的挑战。