Ge衬底上GaInP2 材料的生长研究

采用自制的低压金属有机化学汽相淀积LP-MOCVD设备, 在(100)面偏(110)面 9°的Ge单晶衬底上外延生长了GaInP2材料,研究了生长温度 、Ⅴ/Ⅲ比、生长速率等生长参数对GaInP2材料的表面形貌和固相组分的影响.结果表明,当GaInP2材料的生长温度为650～680℃,生长速率为25～35 nm/min,Ⅴ/Ⅲ为180～220时,获得了满足级联电池的GaInP2材料.     

基于顾客低碳行为偏好的选址-路径-库存集成优化模型与算法

针对自愿减排驱动下的顾客低碳行为偏好对选址-路径-库存决策的影响进行研究。首先推导了顾客低碳行为偏好下的市场需求函数和价格函数,并构建了考虑单位产品碳排放量和经济成本的多目标选址-路径-库存优化模型,通过对多目标优化模型的求解可得碳排放量和经济成本间的Pareto解集。在此基础上,定义了碳配额税的概念,可得顾客低碳行为偏好和碳配额税下的总收益函数。最后通过数值分析给出了自愿减排和监管减排两种机制共同作用下的企业减排方案和灵敏度分析。     

Thermal Analysis of Vertical Upward Flame Spread and Dripping Behaviors of Polystyrene Foams at Different Altitudes

In order to reveal the effect of altitude on the flame spread and dripping behaviors of PS foams a series of upward flame spread experiments was carried out on the plateau area of Lhasa and the plain area of Hefei. It was found that, during the flame spread process, extinction occurred on the plateau for expanded polystyrene (EPS) and extruded polystyrene (XPS) foams while, on the plain, the flame spread could be well sustained and, at longer times, even acceleration was observed. Due to the increase of smoke generation, resulting in decreases of the flame heat flux and oxygen concentration in air entrainment on the plateau, the burning and heat transfer were not efficient in Lhasa, making extinction occur. A larger angle for the pyrolysis front of EPS and XPS on the plateau was another important factor promoting extinction. The mass of dripping PS in the pool fire zone was also studied for different thicknesses of PS at the two altitudes. The maximum dripping mass of EPS or XPS was much larger for thicknesses of 4 cm and 5 cm than for 2 cm and 3 cm, attributed to the melting PS dripping to the pool fire zone directly making the effect of attaching to the wall weaken.     

Abwärme als Energiequelle

Die Verstromung von Abwärme ist ein vielversprechender Ansatz zur Steigerung der Energieeffizienz vieler Prozesse. Hierfür bietet die Thermoelektrik große Vorteile in Bezug auf Systemkomplexität, Wartungsfreiheit und Langzeitstabilität. In den letzten Jahren wurden neue, effizientere thermoelektrische Materialien entwickelt. Auch die Aufbautechnik wurde verbessert. Auf dieser Basis werden nun thermoelektrische Module in Systemen verschiedener Anwendungen erprobt. Dazu zählen Fahrzeuge, Blockheizkraftwerke und die industrielle Abwärmenutzung zum Beispiel in Stahlwerken. Durch Produktion im industriellen Maßstab kann die Thermoelektrik zukünftig so wirtschaftlich werden, dass sie auf vielen Anwendungsgebieten einen spürbaren Beitrag zur Senkung der CO₂‐Emissionen leistet.     

EAST真空室内巡视系统的真空性能研究分析

介绍了EAST真空室内巡视系统(IVVS)系统对EAST真空室第一壁进行巡检操作的工作原理,并基于系统部分材料出气率测试对其真空性能进行了分析。获得了在有效抽速为1064L•s^–1的条件下,IVVS系统试验样机所采用的真空容器的极限真空度为3.37×10^–3Pa。为优化IVVS真空性能,结合材料放气率试验,将部分材料更换为放气率低的材料,对系统进行烘烤处理,并对其中的相关结构提出了优化方案。优化后系统的真空性能有明显提高,在同等抽速条件下的极限真空度在1×10^–4Pa范围内,能够满足EAST接受的真空环境要求。此外,抽气机组增添低温泵可以更进一步提高系统的真空性能。     

基于牛顿迭代法高温光谱温度和发射率的反演研究

针对基于光谱数据进行温度与发射率分离过程中存在的n个方程包含n+1个未知数这一欠定问题,提出利用牛顿迭代法来实现材料表面真温及发射率的反演计算,通过给定温度和发射率初值,利用泰勒级数的线性项建立迭代公式,通过迭代得到温度和发射率的近似解。分别利用理论热辐射谱和腔黑体的实验数据进行验证,结果表明,任意给定温度和发射率初值均可获得与真实温度接近的计算温度值,相对误差小于0.09。发射率反演结果与真实发射率线形一致,当温度和发射率初值越接近真实温度和发射率时,发射率反演结果越精确。该方法消除了发射率假定模型限制,有望应用于高温及超高温下各种材料真实温度和光谱发射率研究。     

Large deflections of non-prismatic nonlinearly elastic cantilever beams subjected to non-uniform continuous load and a concentrated load at the free end

This work studies large deflections of slender,non-prismatic cantilever beams subjected to a combined loading which consists of a non-uniformly distributed continuous load and a concentrated load at the free end of the beam.The material of the cantilever is assumed to be nonlinearly elastic.Different nonlinear relations between stress and strain in tensile and compressive domain are considered.The accuracy of numerical solutions is evaluated by comparing them with results from previous studies and with a laboratory experiment.     

基于分子动力学模拟的多晶结构微观热-力耦合行为的计算

基于分子动力学模拟,建立了一套可用于表征微观下多晶结构热-力耦合行为的算法框架。该算法的要点是将连续模型和分子模拟耦合起来,并使守恒定律在微观连续模型和原子层次上都得到满足,与利用传统的连续介质力学建立晶界与晶粒的本构方程相比,本模型中的连续流是通过原子模型准确计算得到的,从而避免了使用经验的本构方程。     

Planar Strain Measurements on Wood Specimens

Wood specimens have been tested for compressive loading in the longitudinal direction. Planar deformation was recorded by means of video extensometry on the specimen surfaces. A post processing routine was developed to calculate stress and strain values from the sampled data. The routine made use of mathematical framework used in the finite element method. Material parameters were detected by means of an optimization algorithm, and the determined linear elastic parameters were in general found to be in good agreement with values given in literature. The utilized method offers simultaneous average values for active, passive and shear strains from the measured area. Moduli of elasticity, Poisson’s ratios and shear deformation can thus be evaluated. In addition, the variation of the three strain components over the area is measured. The results can therefore be used for quantification of material inhomogeneity and are further suitable for direct comparison with numerically computed strains comprising non-uniform strain fields. Since video extensometry does not require any physical contact with the specimen, measurements can be undertaken until failure. The present method offers thus an efficient and relatively accurate way to measure and evaluate the material characteristics of anisotropic and inhomogeneous materials like wood.     

The neglected pillar of material computation

Many novel forms of computational material have been suggested, from using slime moulds to solve graph searching problems, to using packaging foam to solve differential equations. I argue that attempting to force such novel approaches into the conventional Universal Turing computational framework will provide neither insights into theoretical questions of computation, nor more powerful computational machines. Instead, we should be investigating matter from the perspective of its natural computational capabilities. I also argue that we should investigate nonbiological substrates, since these are less complex in that they have not been tuned by evolution to have their particular properties. Only then we will understand both aspects of computation (logical and physical) required to understand the computation occurring in biological systems.