Augmented infinitesimal perturbation analysis: An alternate explanation

Augmented infinitesimal perturbation analysis (APA) was introduced by Gaivoronski [1991] to increase the purview of the theory of Infinitesimal Perturbation Analysis (IPA). In reference [Gaivoronski 1991] it is shown that an unbiased estimate for the gradient of a class of performance measures of DEDS represented bygeneralized semi-Markov processes (GSMPs) (cf. [Glynn 1989] can be expressed as a sum of an IPA-estimate and a term that takes into account the event order changes. In this paper we present an alternate approach to establishing the result of Gaivoronski, and from this we derive a necessary and sufficient condition for the validity of the IPA algorithm for this class of performance measures. Finally we validate our results by simulation examples.This research was supported by the National Science Foundation under grant number ECS-85-15449, Office of Naval Research Grants Nos. N00014-90-K-1093 and N00014-89-J-1023 and by Army Grant No. DAAL-03-86-K-0171.     

U型管埋地换热器三维传热模型及实验对比分析

针对U型管埋地换热器的传热特点,考虑了两管脚之间的相互影响,建立起非稳态传热模型。采用数值解法对该理论模型进行了求解,并将结果与实验值进行了对比分析,发现两者变化趋势一致,但理论计算结果比实验测试值低,其中的一个重要原因是因为换热器与土壤间的热交换不是纯导热过程,还应该进一步考虑土壤中热湿迁移等因素的影响。     

聚对苯二甲酸丁二醇酯增韧改性研究进展

阐述了聚对苯二甲酸丁二醇酯(PBT)的结构特点、特性及PBT增韧改性的主要方法,其中以聚烯烃、橡胶弹性体应用最为广泛而,无机组分聚合物体系增韧则是一种较新的方法,可以同时达到增韧增强的目的。     

带通滤波器谐振功率特性分析与研究

通过多个不同拓扑结构带通滤波器并联等效电路,系统地分析了影响滤波器谐振功率特性的主要因素:无载Qu值、相对带宽和主耦合系数以及交叉耦合.同时结合群时延理论解释了相对带宽和主耦合系数对谐振功率特性的影响,针对交叉耦合对滤波器内部三腔、四腔交叉耦合结构中关键谐振腔谐振功率特性的影响,利用相位方法进行了定性的分析.最后,对一款包含三腔交叉耦合结构的TM模式介质滤波器的谐振腔功率进行了耦合测试,得到的测试曲线与电路分析的结果相吻合.     

Hydriding-dehydriding kinetics and the microstructure of La- and Sm-doped NaAlH4 prepared via direct synthesis method

By directly introducing LaCl₃, La₃Al₁₁, SmCl₃, SmAl₃ into NaAlH₄ system using one-step synthesis method, the effects of these additives on NaAlH₄ were systematically investigated with regard to hydriding and dehydriding properties. Results showed that the materials doped with aluminide exhibit similar kinetics to the chloride-doped NaAlH₄. The apparent activation energy E_a of doped NaAlH₄ were calculated to be 86.4-93.0 kJ/mol and 96.1-99.3 kJ/mol for the first and second dehydrogenation step respectively by using Kissinger’s approach, much lower than those of pristine NaAlH₄. A reversible hydrogen capacity of 4.8 wt% can be achieved for the La₃Al₁₁- and SmAl₃-doped NaAlH₄, which is 10-20% higher than chloride-doped NaAlH₄. Investigations on the phase evolvement and microstructure in the cycling in LaCl₃- and La₃Al₁₁-doped NaAlH₄ clearly demonstrate that La species is presented as the form of La-Al nanoclusters in the materials. The combination of hydrogen storage properties and the microstructures unequivocally reveal that the in situ formed rare-earth-Al species play a crucial rule in catalyzing the chloride-doped NaAlH₄.     

基于滑动窗口和卷积神经网络的可穿戴人体活动识别技术

由于缺少统一人体活动模型和相关规范,造成已有可穿戴人体活动识别技术采用的传感器类别、数量及部署位置不尽相同,并影响其推广应用.该文在分析人体活动骨架特征基础上结合人体活动力学特征,建立基于笛卡尔坐标的人体活动模型,并规范了模型中活动传感器部署位置及活动数据的归一化方法;其次,引入滑动窗口技术建立将人体活动数据转换为RG...     

Hierarchical yolk-shell structured Li-rich cathode boosting cycling and voltage stabled LIBs

Despite the high energy density of lithium-rich(Li-rich)cathodes,their implementation is hampered by the unsatisfied rate capacity and poor cycling performance ...     

OSL剂量计在辐射防护监测中的应用

本文主要介绍了光致发光(OSL)剂量计的原理、测量系统的刻度、质控和检定方法,并与田湾核电站的TLD剂量计进行了比对,比较说明OSL剂量计相对于TLD剂量计的优点,提示OSL剂量计具有巨大优势和广泛的应用前景。     

塔中北部奥陶系层序地层模型的建立

塔中坡折带是油气勘探的重点区块,但层序划分及坡折带之下的研究程度很低。在塔中29井划分出83m相当于良里塔格组沉积时期的地层,重新建立起塔中北部奥陶系层序地层模型;对地震相进行了研究,塔中北部斜坡奥陶系良里塔格组发育3个地震相,从南到北是"平行连续反射相"、"杂乱丘状反射相"、"连续强反射相",分别代表碳酸盐岩台地、台缘礁滩复合体、密集段沉积;重新厘定了地震解释方案,对重点地震剖面进行了解释,认为晚奥陶世良里塔格组沉积之后,塔中北部斜坡主要遭受风化剥蚀,坡折带之下则接受了巨厚的"黑被子"中下部沉积。在塔中42井以东地区,良里塔格组坡折带前缘"三角带"是礁滩体的一部分,溶蚀孔洞发育,是值得探索的一个新领域。