Acoustic-Emission Analysis of the Accumulation of Bulk Damage to Solid Bodies

Using the proposed concept, we developed a model for quantitative evaluation of the bulk damage to solid bodies in a plastically deformed volume by acoustic-emission signals. This model takes into account the principle of linear summation of damages and the solution in displacements of the dynamic problem of the formation of an isolated normal tensile microcrack in the zone of intense plastic strains. The main scientific propositions of the model are corroborated by the results of experimental investigations and published data.     

Stagnation Points in Flows about Solid Bodies

A possible first step in determining the flow about a steadily advancing ship is to consider the ship plus its mirror image in the undisturbed free surface. If the ship has a bulbous bow, the question may be asked whether a stagnation point can be expected not only at the intersection of the stem and the undisturbed surface, but also at some point on the stem near the bulb. In analogous two-dimensional situations the latter could not happen. That it can happen in three dimensions is shown here by the example of two dipoles situated perpendicularly to an oncoming flow. Both two- and three dimensional versions are considered. The conditions under which these stagnation points can occur in three dimensions are determined and the reason why this does not happen in two dimensions is explained.     

多功能热泵空调与热水负荷调节的理论分析与试验研究

为了解决多功能热泵空调兼制热水工况时热泵的能量输出与热水负荷和空调负荷之间的平衡问题,就必须根据空调或热水的负荷的变化对热水换热量和空调换热量进行能量调节.首先,对现有的几种能量调节方式进行了分析,针对各自的优缺点,提出了一种新的变流量调节方式,并进行了理论可行性分析;然后进行试验研究,实验结果表明,增加热水换热器循环水流量能加大热水换热量、减少空调换热量;降低热水换热器循环水流量能减少热水换热量、加大空调换热量.因此,可采用以满足空调负荷为控制目标,通过变热水换热器循环水流量的方式对热水和空调的热量分配进行动态调节.     

几种典型凸轮裹包执行机构的从动系统运动规律的理论分析

详细分析了裹包执行机构的正弦型和正切型从动系统的运动规律，用数学方法对运动规律进行了详尽的理论分析。     

Theoretical Analysis on Common Stabilizers for Nitrate Solid Propellants

Density functional theory (DFT) B3LYP method and 6-311G** basis set were employed to study 19 kinds of stabilizers in nitrate solid propellant, including newly developed AK2, M1 M5, STAB-1, and normal aromatic amine stabilizers, such as o-nitrodiphenylamine (2-NDPA), diphenylamine (DPA), dimethyldiphenyl urea (C2), diethyl diphenyl urea (EC), and N-(2-methoxyethyl) p-nitroaniline (MENA). Calculations were conducted in acidity and basicity, dissociation energy (2.68-4.85 eV), Wiberg bond indexes (WBI) and nucleus-independent chemical shift (NICS) (32.80-49.89), and electron affinity (0.067-0.839 eV) and energy gap (3.286-5.891 eV) to verify stabilizers- nucleophilicity, molecular stability, aromaticity and the ability to attract electrons, respectively. Based on results above, the stabilizer with the best ability can be proposed.     

Evaluation of the Rate of Change of Transfer Potentials in Porous Solid Bodies

A formula for calculating the potential diffusivity of energy in porous solid bodies has been obtained, which made it possible to express the velocity of propagation of the energy field in the form of a relation of the type of an equation of heat conduction with a constant coefficient. Under the same boundary conditions, the velocity of propagation of the energy field is intermediate in value between the velocities of propagation of the temperature and concentration fields.     

变频空调系统的理论分析及实验研究

变频空调器是由变频压缩机驱动的空调系统 ,压缩机通过变频调节其转速使压缩机单位时间内的排气量变化 ,从而达到调节制冷量的目的。本文提出了变频空调器制冷系统的原理和设计方法 ,具体给出了制冷量和压缩机频率的关系方程 ,并从理论和实验两方面对变频空调器制冷系统进行了分析 ,得到了频率曲线图 ,为变频空调器制冷系统的设计提供了依据。     

New Discrete Model of Plastic Deformation of Solid Bodies

Materials Science - We compare the dislocation model with a new discrete model of plasticity. According to the previously proposed model, a crystal lattice with spherically symmetric potential of...     

波浪与两相连浮体的相互作用

应用边界积分方程方法研究了波浪与2个相连三维浮体的相互作用问题。计算中考虑了浮体相互间的水动力干涉，通过联立各浮体的运动方程以及运动连续条件求得浮体运动量。计算了2个铰连接漂浮方箱组成的系统，同Newman的结果进行了对比,当入射波的频率不在系统的自振频率附近时，结果与Newman的结果吻合良好，在自振频率附近时，铰接点处的转角和垂向位移都发生快速变化，而Newman未提到这一现象。     

户式变频冷水机组空调系统综合匹配分析及实验研究

本文把户式变频冷水机组空调系统复杂的综合匹配关系进行了简化，建立了综合匹配关系式，分析了综合匹配的关键因素，设计了匹配实验装置及方法，并进行了实例实验研究，为该类空调系统的优化设计提供理论分析方法及实验参考结果。     

Thermodynamic Analysis of Water Interaction with Excipient Films

The interaction of water with excipients that can form moisture-protective coatings was examined earlier by the application of theoretical models. In this study, thermodynamic analysis of water-excipient film systems has been performed to elucidate the mechanistic details of the water-excipient interaction. Partial molal free energies, enthalpies, and entropies were computed for films of lipidic (glyceryl behenate, GB) and polymeric (polyvinyl alcohol, PVA) coating excipients using the temperature dependence of the adsorption process. The analysis of free energy changes showed that excipient films were not inert participants in the water sorption process. The isoteric heats of adsorption confirmed that water formed hydrogen bonds with the excipient films and allowed estimation of number of hydrogen bonds per water molecule. This result also provided the reason for hysteresis during drying. A comparative evaluation of the application of theoretical models and thermodynamic analysis revealed that results obtained from both approaches were not always complementary. An exponential relationship was found to exist between sorption microrate constants and water activity for the PVA films at all temperatures.     

重力再循环制冷系统理论分析与实验研究

重力再循环制冷系统相比于普通直接膨胀制冷系统具有蒸发温度越低,效率优势越显著,以及可获取更低库内温度。本文结合重力再循环系统工作原理重新绘制了匹配的压焓图,将重力再循环系统的热力循环过程在压焓图上分两个循环进行分析,通过分析制冷剂流动过程中的流动阻力,得到系统中各部分压力变化趋势,并通过搭建重力再循环制冷系统进行实验研究,结果表明,获得的各状态点的压力与理论分析结果较为吻合。最后与直接膨胀供液制冷系统的运行结果对比,在不同蒸发温度下重力再循环制冷系统的COP最多可提升19%,且在-30℃温度条件下,COP达到1.07。     

温度对金刚石刀具影响的理论模型和实验分析

为减小大型金属反射镜在金刚石车削中,刀具的热变形对加工精度的影响,研究了金刚石刀具在温度影响下的热变形规律,结合俄罗斯在热力学方面的研究成果,根据金刚石晶体和刀体的热膨胀系数和导温系数的不同,建立了刀具变形量随温度变化的理论计算模型,并采用高精度的热像仪和电感测微仪记录刀具的温度变化和变形量,发现当温度从23．4℃升高到32．1℃时,刀具变形量达到1．48μm．     

Studying the Mutual Influence of a Set of Strikers during Simultaneous High-Velocity Entry into Water

Technical Physics Letters - High-velocity motion of a set of supercavitating kinetic strikers during their simultaneous entry into water has been experimentally studied. A special experimental...