Microscopic and Macroscopic Growth Rates of Fatigue Cracks in Steels and Alloys under the Influence of Crack Closure

On the basis of the experimental data, we show that the difference between the macroscopic and microscopic fatigue crack growth rates in the second section of the kinetic diagram of fatigue fracture is caused by the effect of crack closure within the limits of its existence. We establish the relationships between the macroscopic and microscopic fatigue crack growth rates and the structure of the material in the second section of the diagram for various values of the load ratio with regard for the effect of crack closure and propose a procedure of examination of the fracture processes in structural materials based on the analysis of microscopic and macroscopic fatigue crack growth rates.     

建筑墙体表面传热系数辨识研究

对实验房间南向墙体内表面中心区域的换热过程进行实验，发现当风速在0－5．5m/s之间时，表面传热系数在8－18W（m^2.K）之间波动，而风向对墙体表面传热系数影响不大；用辅助变量法分析墙体表面传热过程，并结合实验推导出墙体表面传热系数。模型的预测结果与实测结果吻合良好。     

非关联双模场对Kerr介质中电子绝热跃迁转移现象的影响

本文研究了充满Kerr介质的高Q腔中非关联双模相干态场与级联三能级原子非共振相互作用情况下,电子的绝热跃迁转移现象与非关联场之间的关系。数值计算显示:级联三能级原子在与非关联双模相干态的相互作用下,该现象依然存在,但呈现不同于原子与关联场相互作用的新特征。     

大长径比自旋弹箭横向自振特性的有限元计算方法与结果分析

本文研究大长径比自旋弹箭在飞行时横向振动的自振特性。本文将转子动力学应用于弹道学 ,采用有限元法 ,建立自旋弹箭横向振动自振特性方程。同时给出了计算方法。利用该方程和该方法 ,开发了相应的计算程序。通过数值计算 ,可给出细长旋转弹箭飞行时的进动转速和临界转速 ,以及相应的位移和角度振型。利用该程序 ,进行了实例计算和分析。     

复合形法优化内河航道重力式护岸

采用复合形优化法,结合《港口及航道护岸工程设计与施工规范》中推荐的抗滑、抗倾稳定的分项系数计算方法,并考虑了内河航道船形波等作用的影响效应,对重力式护岸断面进行了优化。     

轻型钢骨结构低层住宅设计荷载分析

本文讨论了北美低层钢骨结构住宅结构设计的荷载问题，包括各类荷载的取值和计算方法，以及荷载组合模式，并提出了在我国相关规范没有出台前，在国内进行设计时应该注意的一些问题。     

燃烧—气体容量法测定冶金石灰中的二氧化碳

冶金石灰是石灰石经过工业煅烧的产品。其二氧化碳含量低，且经过高温煅烧后基本不含有机物。无需按照《石灰石、白云石化学分析国家标准中二氧化碳的化学分析方法》中用酸进行试样分解，只需在1200℃高温中灼烧，使石灰中残留的或煅烧后吸收空气中二氧化碳而形成的碳酸盐分解，象通常测定含碳耐火材料中二氧化碳那样，采用气体容量法进行测定。     

A continuum-based modeling of MEMS devices for estimating their resonant frequencies

A continuum-based modeling of coupled electrostatics-structure interactions is presented for the frequency computations of MEMS devices. The present general formulation of electrostatics accounting for free space is validated first by specializing it to one-dimensional uniform motion of conducting surfaces and comparing the resulting electrostatics to conventional lumped models. The general coupled electrostatics-structure interactions are then applied for the prediction of resonant frequencies of MEMS devices due to bias-voltage changes and temperature variations. Comparisons of predicted resonant frequencies obtained by the present coupled electrostatics-structure interaction models with experimental results available in the literature demonstrate that the proposed continuum-based interaction modeling yields high-confidence predictions of resonant frequencies of MEMS devices.     

The Clausius inequality corrected for heat transfer involving radiation

The objective of this paper is to prove that the Clausius inequality must be re-stated to have general applicability for heat transfer involving radiative fluxes. The integrand (đQ/T) of the Clausius expression applies to heat conduction and convection, but does not hold for most radiative transfer scenarios, with the exception of reversible infinitesimal net blackbody radiation transfer. In other cases involving radiative transfer, the equality holds for a cycle even though irreversible heat addition by radiative transfer occurs. This is without the erroneous presumption of entropy destruction anywhere in the cycle. Thus, the Clausius inequality indicates reversibility for a cycle that includes an irreversible process. Further, in some radiative cases the quantity đQ/T, where T is the boundary temperature, is not the entropy transfer at the system boundary, and in fact, primarily represents entropy production within the system. It is also clear that in another case considered, the quantity đQ/T had no physical meaning whatsoever. Consequently, the Clausius expression has been re-stated so that it is applicable to cycles with processes involving any form of heat transfer. A new integrand (đQ_cc/T + đS_Net,Rad) is presented, allowing the Clausius inequality to generally apply to all heat transfer scenarios. The work in this paper emphasizes the need to re-state other fundamental equations allowing applicability to all heat transfer processes, and draws attention to the unique character of radiative entropy calculations.     

Cooling and Solidification of Melted Drops in an Immiscible Cooling Medium

The cooling and solidification of melted drops during their movement in an immiscible cooling medium is widely employed for granulation in the chemical industry, and a study of these processes to provides a basis for the design of the granulation tower height and the temperature of the cooling medium is reported. A physical model of the cooling and solidification of the drop is established and the numerical calculation is performed. The influences of the key factors in the solidification, i.e., Bi number, drop diameter, temperature of the cooling medium, etc. are presented. The cooling and solidification during wax granulation in a water‐cooling tower and during urea granulation in an air‐cooling tower (spraying tower) are described in detail. Characteristics of the solidification and temperature distribution within the particle at different times are shown. The model and calculations can be used for structure design of the granulation tower and optimization of the operation parameters.