多模激光束通过时间变化相位片变换的数值分析

根据衍射积分公式,对连续多模激光束通过随时间变化相位片的变换特性进行了数值模拟,详细地讨论了相位片单元尺寸和相位变化频率对多模光束光滑和能量分布的影响。数值模拟结果很好地解释了实验结果。     

原岩应力状态的正交异性球壳模型评价

本文提出正交异性球壳模型,按弹性理论建立了原岩应力解析式,该方法弥补了以往各向同性球壳模型的不中,可计算出任意深度的原岩应力状态,铅垂应力,平均水平应力,水平面内最大及最小正应力。解析结构与原岩应力实例测值高度吻合。     

Stress analysis of notched anisotropic finite plates under mechanical and hygrothermal loads

Summary Notch-induced stress concentrations in anisotropic composite materials depend on their directional material properties, especially for uniaxially reinforced composites with high-modulus fibres. The design of notched high-performance composites requires therefore a special proof of their notched strength, which includes the structural parameters of the fibre/matrix combination, fibre orientation and layer arrangement. The assessment of the effects of the finite outer boundary is of practical importance when dimensioning critical notched regions. An anisotropic plate with finite dimensions and a hole in its center will be used here to model stress concentrations. The calculation is based on conformal mappings combined with complex-valued stress functions. The outer boundary is described using point-matching and the least-squares method. The solutions are conducive to the assessment of the essential influencing factors of material properties, geometry and loads. Notched finite plates made of fibre/matrix composites, mainly carbon-fibre reinforced polymers, will be presented as illustrations. Received 29 June 1998; accepted for publication 22 October 1998     

Moving inclined load at boundary surface

Introduction Inmanyengineeringphenomenon,includingtheresponseofsolids,geologicalmaterialsand composites,theassumptionsofanisotropicbehaviormaynotcapturesomesignificantfeaturesof thecontinuumresponse.Theformulationandsolutionofanisotropicproblemsarefarmore difficultandcumbersomethanitsisotropiccounterpart.Inrecentyearstheelastodynamicresponse ofanisotropiccontinuumhasreceivedtheattentionofseveralresearchers.Inparticular, transverslyisotropicandorthotropicmaterials,whichmaynotbedistinguishedfrom…     

层合析参固支边界条件下的不稳定后屈曲分析

为了深入地研究复合材料层板所独具的后屈曲特性,利用能量变分原理和非线性几何方程建立了具有弹性约束的复合材料层板在面内载荷作用下的非线性稳定性控制方程组,并运用广义傅立叶级数法对其进行求解。重点分析了非对称层板在固支边界条件下的稳定性问题,发现层板在此条件下有可能存在非对称的失稳临界点和不稳定的后屈曲路径,进而构造了简化的物理模型进行解释,指出后屈曲的非对称性是由于结构关于Z轴不对称,而不稳定性是由于固支边界条件阻碍了前屈曲的发生。     

中厚板统计分析的随机边界元法

本文建立了分析含随机材料参数并具厚度不均匀性的中厚板问题的随机边界元法,基于Taylor级数展开技术,分析和到广义位移的均值和一阶偏差的积分方程,其中将材料参数的随机性和厚度的不均匀性作为等效荷载处理,从而得到广义边界位移或面力的均值和协方差,并进一步求出部点广义位移和内力的均值和协方差,最后用本文方法计算了两个数例,并对所得结果进行了分析,探讨。     

The application of heat conduction microcalorimetry to study the metabolism and pharmaceutical modulation of cultured mammalian cells

The heat produced by animal cells in culture can be used as the primary indicator of the kinetics of their metabolism because the scalar flux of it is a function of the metabolic flux. The validity of the relationship between heat and metabolism was demonstrated theoretically through the concept of thermal advancement and in experiments by the use of continuous cultures. This validation permitted the application of heat flux as a probe of the metabolic state of cells in culture. It consisted of an on-line heat conduction microcalorimeter that measures the instantaneous heat flow and dividing the smoothed signal with one obtained simultaneously using a dielectric spectrometer that records the change in capacitance as an estimate of the amount of viable biomass. In this mini-review, it is shown with Chinese hamster ovary cells (CHO320) genetically engineered to produce interferon-γ (IFN-γ) that heat flux is an early signal of deteriorating metabolism in cultures that produce considerable amounts of toxic lactate under fully aerobic conditions. The early detection favours the use of heat flux as the control variable in fed-batch cultures. This is a particularly useful finding in the context of the pharmaceutical industry because it will help to ensure the high fidelity of the cytokines, antibodies and vaccines produced in large-scale cultures. The monotonic relationship between the fluxes for heat and metabolism means that the enthalpy balance method can be employed to test the validity of the growth reaction for cells in culture. This showed that the crucial ratio between the substrates, glucose and glutamine, in the culture medium was incorrect at 5.5:1 instead of about 3:1, depending on the phase of the culture. Together with other changes to the medium composition, an improved formulation was made that ensured faster cell growth and greater specific rate (flux) of IFN-γ constitutive secretion while decreasing glucose utilisation and, most importantly, halving the excretion of lactate, that is toxic to the cells and harmful to the fidelity of their secondary products. Indirect calorimetry (oxygen uptake rate, OUR) is often favoured over the direct technique, but the former only measures aerobic metabolism. The environmental conditions in cultures favours lactate production even under fully aerobic conditions. Developments in measuring OUR mean that the stationary liquid phase balance can be used successfully to make the calorimetric:respirometric (CR) ratio a valuable tool in optimising cell culture to grow cells that synthesise the maximum amounts of the high fidelity secondary products.

Besides the value of heat flux in improving the cultures of animal cells producing heterologous products, three different techniques are examined that should be valuable in the testing the many compounds that are produced on a speculative basis as potential drugs. They are: (i) a thin-film thermopile transducer as an immunosensor; (ii) infra-red imaging of cells cultured in multi-well microtitre plates and (iii) integrated circuit (IC) calorimetry for small samples and low detection limit. One or more of these methods could well find favour with industry in the near future.     

层合板分叉方程的Lyapunov-Schmidt约化分析1999-11-17收稿.

在建立具有弹性约束的复合材料层板在面内载荷作用下的非线性稳定性控制方程组的基础上,利用分叉理论和泛函知识,对有限维的分叉方程进行了Lyapunov-Schmidt 约化,获得了三种典型的分叉图形式,并证明了当非齐次项等于零时必然发生分叉。     

State-vector equation with damping and vibration analysis of laminates

Based on the modified mixed Hellinger-Reissner(H-R)variational principle for elastic bodies with damping,the state-vector equation with parameters is directionally derived from the principle.A new solution for the harmonic vibration of simply supported rectangular laminates with damping is proposed by using the precise integration method and Muller method.The general solutions for the free vibration of underdamping,critical damp and overdamping of composite laminates are given simply in terms of the linear damping vibration theory.The effect of viscous damping force on the vibration of com- posite laminates is investigated through numerical examples.The state-vector equation theory and its application areas are extended.     

水波中弹性浮板的减振问题研究

基于线性水波理论和Mindlin厚板动力学理论,采用Wiener-Hopf方法,分析研究了水面上弹性浮板对水波的动响应及其减振问题．首先,在不考虑弹性联接情况下,将分析计算结果与前人的计算结果及实验数据进行了对比,验证了该方法的有效性．其次,基于该方法分析了连接浮板与水底的弹簧刚度与浮板振动响应各参数之间的关系,从而为超大型浮台系统的设计提供理论依据．