Characterizing the Rheology of Powders by studying dynamic avalanching of the powder

Avalanching of solids is an important multivariable dependent phenomenon that can be a valuable tool for characterization of solids flowability. Although avalanching by itself is primarily chaotic it appears that the fractal analysis of its avalanching mass data can yield very interesting and significant information that is of importance in determining suitability of a material in solids handling and pneumatic transport.     

Similarity criteria for Debye temperatures of simple solids at compression

A similarity criterion for the volume dependence of Debye temperatures of simple solids at compression is presented. It is shown that the volume dependences of the characteristic Debye temperatures of various solids fall on a single common curve in dimensionless coordinates. The validity of the model is tested on examples of solids with various types of interatomic forces – molecular crystal, ionic crystal, metals and covalent crystal.     

Flame spread and interactions in an array of thin solids in low-speed concurrent flows

Flame spread in an array of thin solids in low-speed concurrent flows was investigated and numerical solved. A previous steady, two-dimensional flame-spread model with flame radiation was employed and adapted in this work. The flame structures of spreading flames between parallel solids were demonstrated and some of the features were presented, including flow channelling effect and flame radiation interactions. The channelling effect is caused by flow confinement by the presence of the other solids; the flows through the hot combustion gases are accelerated downstream drastically. Radiation interactions between flames and solids contributed to a less heat-loss system, and radiation re-absorption by flames resulted in a larger flame with higher temperature, which increased the conductive heat fluxes to the solids and flame spread rate. Consequently, the extinction limit for the interacting flames is extended beyond the low-speed quenching limit for a single flame. The influence of the separation distance on the flame spread rate was also studied, which exhibits a non-monotonic behaviour. At larger separation distance, the flame spread rate increases with decreasing the separation distance owing to the channelling effect and radiation interactions. However, at very small separation distance, the flame spreading rate decreases with decreasing the distance because of the limited space for thermal expansion and flow résistance between solids.     

Calculation of statistical entropic measures in a model of solids

In this work, a one-dimensional model of crystalline solids based on the Dirac comb limit of the Krönig–Penney model is considered. From the wave functions of the valence electrons, we calculate a statistical measure of complexity and the Fisher–Shannon information for the lower energy electronic bands appearing in the system. All these magnitudes present an extremal value for the case of solids having half-filled bands, a configuration where in general a high conductivity is attained in real solids, such as it happens with the monovalent metals.     

Relaxation and Creep of Dry Bulk Solids

In former investigations it has been shown that creep (constant stress, altering strain) and relaxation (constant strain, decreasing stress) can be observed with dry bulk solids. Both effects are covered when investigating the time dependent behaviour of bulk solids where time dependence can also mean an increase of the deformation resistance with increasing deformation rate. In this paper the investigated time dependent effects do not include time consolidation. The effects of creep and relaxation are often neglected for bulk solids because in many applications the influence of these time dependent behaviours is of minor importance. A deeper insight into the bulk solids flow characteristics and mechanisms can only be obtained when time dependence is taken into consideration.     

Photoacoustic spectroscopy of solids

The opto- or photo-acoustic effect used in gas analysis has been extended to the study of solids. This technique provides a simple method for obtaining information about optical absorptions and subsequent de-excitations in solids.     

Nonlinear surface acoustic waves: realization of solitary pulses and fracture

A laser-based technique for the contact-free generation and detection of strongly nonlinear surface acoustic wave (SAW) pulses with amplitudes limited by the materials strength has been developed. The effects of nonlinear propagation of short elastic surface pulses with finite strength in isotropic solids, such as fused quartz, anisotropic solids, such as silicon, and dispersive media were investigated. Solitary surface wave propagation was observed in layered structures for normal and anomalous dispersion. In addition, a SAW-based method for evaluating the critical fracture stress of anisotropic brittle solids, such as single crystal silicon, is introduced.     

Simulating the mechanical response of amorphous solids using atomistic methods

The study of elasticity, plasticity and failure in non-crystalline solids has greatly benefitted from the application of atomic scale simulation. This “colloquium paper" reviews the ways in which a variety of computational approaches have been used to elucidate the atomic scale phenomena that control the mechanics of amorphous solids. The constitutive theories that have been developed for describing mechanical response are briefly reviewed, as well as the prospects for testing the assumptions of these theories using simulation. We list what we believe to be the most pressing open questions for substantiating these theoretical approaches, and ultimately for understanding and predicting the mechanical responses of amorphous solids.     

固体光学常数的计算物理

本文延伸通常的固体电子结构计算,根据通常计算所得到的微观物理量以计算固体光学常数等宏观物理量.并以金属Gd为例,给出了简化模型下计算出的理论吸收谱.     

关於固体的现實应力空间

固体不能在一切应力状态下无限受力这意味着只是某一部份应力空间对固体有现实意义。本文所谓“固体的现实应力空间”即指此一部份应力空间而言。在恒温状态下,固体的现实压力空间成何形状?其组成及性质如何?这个问题到现在为止甚至没有一个具体的概念。本文主要引用两方面的理论,结合起来分析这一个重要问题:一为作者前文中所得理论分析结论;一为弥氏(von-Mise)塑性方程。本文分析说明:在恒温状态下,固体之现实应力空间为钟形,对称于流体静应力轴,钟顶在纯张力象限,为最低位能状态、弹性柱、塑性区域断、裂钟面及一未知曲面所构成。此钟形应力空间之构造及性质,明确地反映了一固体在一切应力状态之可塑性与不可塑性,符合于现存实验事实及工业经验所提供的概念。钟形应力空间的构造与性质,提供合符事实而且理论概念明确的条件以作各种变形过程之分类。对固体现实应力空间问题提出一个具体明确的概念,本文是第一次。     

The chemical hardness of molecules and the band gap of solids within charge equilibration formalisms

This work finds that different charge equilibration methods lead to qualitatively different responses of molecules and solids to an excess charge. The investigated approaches are the regular charge equilibration (QE), the atom-atom-charge transfer (AACT), and the split-charge equilibration (SQE) method. In QE, the hardness of molecules and the band gap of solids approaches zero at large particle numbers, affirming the claim that QE induces metallic behavior. AACT suffers from producing negative values of the hardness; moreover valence and conduction bands of solids cross. In contrast to these methods, SQE can reproduce the generic behavior of dielectric molecules or solids. Moreover, first quantitative results for the NaCl molecule are promising. The results derived in this work may have beneficial implications for the modeling of redox reactions. They reveal that by introducing formal oxidation states into force field-based simulations it will become possible to simulate redox reactions including non-equilibrium contact electrification, voltage-driven charging of galvanic cells, and the formation of zwitterionic molecules.     

粉粒体两相流的电容层析成象测量

粉粒体系统中的固相浓度分布的在线测量是十分困难的问题．电容层析成象技术是一种近年来发展起来的非侵入式快速浓度场测量技术．它不干扰流场，不受流动中颗粒浓度、加速度、不透明等因素的制约．本文讨论其测量原理、应用、近期进展、存在的主要问题及其解决的对策．     

快重离子在固体中引起的电子发射

简要介绍了快重离子与固体相互作用研究的状况和快重离子引起固体电子发射的机制 ,讨论了电子能损导致原子位移的 3种微观模型 ,即“库仑爆炸”模型、“热峰”模型和“激发排斥”模型 ,简述了研究电子发射的实验测量装置和测量方法 ,讨论了总电子发射产额与电子能损的关系以及靶俄歇电子和快传输电子测量在电子激发诱发辐照损伤微观机制研究中的应用 ,并介绍了重离子在 C靶中产生的离子径迹处的电子温度和聚丙稀靶中离子径迹势的提取方法. The recent progresses in experimental and theoretical studies of the collision between swift heavy ion and solids as well as electron emission induced by swift heavy ion in solids were briefly reviewed. Three models, Coulomb explosion, thermal spike and repulsive long lived states, for interpreting the atomic displacements stimulated by the electronic energy loss were discussed. The experimental setup and methods for measuring the electron emission from solids were described ...     

应用于金属固体的四参数通用状态方程

提出一种能精确考虑固体结合能的四参数通用状态方程, 并且在高压和膨胀区域都具有正确的行为, 不会出现物理上不正确的振荡现象. 新方程可以将Vinet方程和普遍化Lennard-Jones (GLJ) 方程作为特例包括于其中. 将新方程与文献中的典型方程应用于32种金属固体, 结果表明新方程在给出正确结合能数据的同时, 能够很好的拟合实验压缩数据. 结果还表明, 多数金属的相互作用具有短程相互作用的性质, 但是结合能较大相互作用的强度较强.     

任意维固体的热力学性质的研究

精确地计算了n维固体的热力学函数、热容,讨论了极端高、低温近似时的结果;并将不同维数的热力学性质统一地由一组公式表达了出来.     

Equation of state for inert gas solids

The equation of state is a fundamental relation to analyse the thermophysical properties of different class of solids and it plays a key role in basic and applied condensed matter physics research. A lot of work has been done in the field of ionic solids, minerals and metals but a very little work is done in the field of inert gas solids. Most of the equations of state failed to explain the properties of inert gas solid because of their abnormal behavior in the low temperature range. In the present paper, Singh-Gupta equation of state has been used to study the properties of these solids. The results obtained using these equations have shown a good agreement with available experimental results. Thus it is shown that these equations of states successfully explain the behavior of inert gas solids.      

General qualifications for the sign of thermal expansion coefficients at low temperatures

It is shown by arguments of plausibility that when interatomic forces include mainly central two body interactions, then the sign of the thermal expansion coefficient for isotropic solids at low temperature can be negative only for solids that lack symmetry of inversion. It is deduced that for RbBr and RbI, angular three-body forces play an important role in the nearest neighbor interactions.     

Irradiation-induced amorphization processes in nanocrystalline solids

A theoretical model is suggested which describes irradiation-induced amorphization in nanocrystalline solids, using the rate theory approach. In the framework of the model, interfaces (grain boundaries) cause the two basic effects on irradiation-induced damage and amorphization processes in nanocrystalline solids where the volume fraction of the interfacial phase is extremely large. First, amorphization is enhanced in nanocrystalline solids, because high-density ensembles of interfaces essentially contribute to the total energy of the crystalline state and thereby provide a shift in the energetics of amorphization. Second, interfaces serve as effective sinks of irradiation-produced point defects and thereby hamper amorphization driven by defect accumulation. The competition between these effects is described by kinetic equations for densities of point defects in nanoscale grains in nanocrystalline solids under irradiation treatment. This competition is shown to be responsible for the specific behavior of irradiated nanocrystalline solids, which is different from that of their coarse-grained counterparts. The suggested model accounts for the experimental data reported in the literature.PACS 61.46.+w; 61.72.Cc; 61.80.Az     

炉顶凸起对6分离器CFB气固流动的影响

本文在6分离器CFB冷态试验台上,研究了炉顶凸起空间对气固流动的影响。利用差压法测量炉膛颗粒浓度轴向分布,采用光纤探针测量不同位置的颗粒浓度和速度的径向分布,通过积料法测量6分离器的颗粒循环流率。通过试验结果的分析,得到炉顶凸起空间内的颗粒运动特性,以及不同凸起高度时的炉膛环核流动特性和颗粒外循环特性。本文的研究对大型多分离器布置CFB锅炉的结构优化设计具有参考意义。     

On the Lindemann law of melting of solids

The Lindemann law of melting has been investigated by lattice dynamics. It is found that the law is not universal so far as the Lindemann parameter is concerned, and is structure and interaction dependent. This holds separately for each class of solids having similar structure and inter-particle interaction; i.e. the parameter has one value for all solids possessing the same structure as well as interparticle interaction.