高度非对称二元系超额焓的简化计算

焓超额焓是化学工业中混合与分离过程的重要热力学性质。由于超额焓的实验测定比较困难且不具有连续性;因此,国内外都对混合物超额焓的理论计算进行了大量的研究。同时,状态方程法在混合物超额焓的计算中也得到日益广泛的研究。计算体系也从常压体系扩展到高压体系以及...     

微孔压电弹性动力学的能量原理

根据古典阴阳互补和现代对偶互补的基本思想,通过作者早已提出一条简单而统一的新途径,系统地建立了微孔压电弹性动力学的能量原理,给出一个重要的以卷积表示的积分关系式,可以认为,在力学上它是广义虚功原理的表式,从该式出发,不仅能得到微孔压电弹性动力学的虚功原理和互等定理,而且通过作者所给出的一系列广义Legendre变换,能系统地导出成互补关系的11类变量、9类变量、6类变量和3类变量简化Gurtin型变分原理的泛函,同时,通过这条新途径,还能清楚地阐明这些原理之间的内在联系。     

扩散抛物化Navier-Stokes方程数值解法评述

20世纪60年代末期在边界层理论基础上发展起来的各种简化Navier-Stokes (N-S)方程(统称为扩散抛物化N-S方程)及其算法, 较为彻底地解决了无黏流及黏流的相互干扰问题, 并为高雷诺数大型复杂黏性流场的数值模拟开辟了新的途径. 本文将系统地评述这一领域的主要成果, 包括各种简化N-S模型的优缺点; 数学奇性及正则化方法; 代表性的数值解法以及最近几年的新进展.      

Measurement of the ground state 2n pickup probability for 28Si+68Zn and its role in sub-barrier fusion enhancement

The ground state and excited state transfer yields for the 2-neutron pickup channel in the ²⁸Si+⁶⁸Zn system have been measured explicitly. The recoil mass separator at the nuclear Science Centre, New Delhi was used for the measurement. A NaI(T1) detector was used for detecting the deexcitation γ’s from the transfer products. The kinematic coincidence technique was employed for the transfer measurement. Simplified coupled channels calculations show that out of all transfer channels the major contribution to the sub-barrier enhancement comes from the ground state 2 neutron pickup channel with a ground state Q-value of+1.83 MeV.     

Simplified Synthesis of Biomass-Derived Si/C Composites as Stable Anode Materials for Lithium-Ion Batteries

Synthesis of silicon/carbon (Si/C) composites from biomass resources could enable the effective utilization of agricultural products in the battery industry with economical as well as environmental benefits. Herein, a simplified process was developed to synthesize Si/C from biomass, by using a low-cost agricultural byproduct “rice husk (RH)” as a model. This process includes the calcination of RH for SiO₂/C and the reduction of SiO₂/C by Al in molten salts at a moderate temperature. This process does not need the removal of carbon before thermal reduction of SiO₂, which is thought to be necessary to avoid the formation of SiC at elevated temperatures. Thus, carbon derived from biomass can be directly used for Si/C composites for anode materials. The resultant Si/C shows a high reversible capacity of 1309 mAh g⁻¹ and long cycle life (300 cycles). This research advocates a new and simplified strategy for the synthesis of RH-based biomass-derived Si/C, which is beneficial for low-cost, environmentally friendly, and green energy storage applications.     

含裂纹梁非线性静动力特性及简化动力学建模Static and dynamic behaviour of cracked beam and simplified dynamic model

主要研究裂纹对梁结构动力特性的影响规律,进而为含裂纹梁结构状态监测提供理论依据。首先,对裂纹影响区域进行分析,建立含裂纹梁二维接触非线性有限元模型,阐明含裂纹梁具有拉压不同刚度的静力特性;其次,通过对机理模型的分析,指出拉压不同刚度会引起轴向与弯曲的耦合振动;然后,通过非线性动力学分析方法研究其动力特性,观察到含裂纹梁在冲击荷载下会产生轴向与弯曲的耦合振动现象,并指出这种轴向与弯曲耦合振动的一个重要特征是轴向振动频谱图中含有弯曲振动基频的两倍频成分;最后,通过引入非线性弹簧建立一种新颖的含裂纹梁简化动力学模型,通过与精细有限元分析对比,验证了模型的合理性。该简化动力学模型将接触非线性问题转换为材料非线性问题,避免了费时的接触非线性动力学求解过程。     

简化平面应变土体模型的精度研究及适用性分析

以严格平面应变解为基础,对简化平面应变土体模型即三个单元Voigt体串联模型的精度进行了研究.在各有关影响因素(如土体剪切模量、密度、剪切波速及结构物截面尺寸等)变化条件下,就两种模型土体作用于结构物交界面上的复刚度的实部和虚部分别进行了对比研究,全面地分析了两种模型复刚度的差异性,并进一步对桩顶受纵向激振力作用下的频域及时域动力响应进行了求解,研究了两种模型下桩顶动力响应的差别.结果表明,对土体复刚度而言,在大多数情况下,简化平面应变模型具有足够的精度,可以满足一般工程应用的需要;对桩顶频域响应和时域响应而言,简化平面应变模型已具有较高的精度,其误差可以忽略,具有很强的工程适用性,为该模型在相关领域的应用提供了坚实的理论依据.     

冲击载荷下软钢梁早期响应的数值模拟和简化模型

冲击载荷作用下，梁的早期响应既有弹性变形也有塑性变形，两者相互耦合．有限元数值模拟的结果表明，弹性弯曲波的传播是梁早期变形的主要机制，刚塑性简化理论预言的初始阶段中梁的“移行塑性铰”实际上是不存在的．本文提出的弹性 理想塑性简化模型可以很好地模拟固支软钢梁的早期响应     

Calibration error analysis of electro-optical detection systems

We present detailed analysis of calibration process error for electro-optical detection systems, which can be simplified as the plane rotation around a non-orthogonal axis. By means of octonions it firstly proves that the plane rotation around a non-orthogonal axis can be decomposed into rotations around two perpendicular axes. The rotation is further divided into three steps, and the calibration error is hence discussed and obtained. The simulation and test results indicate that there are large calibration errors in calibration process. The pointing error can be effectively improved after separating error components, which provides a more accurate set data for further comDensation.