Thermoelectric Properties of Heavy Rare Earth Filled Skutterudites Dy y Fe x Co4?x Sb12

Heavy rare earth element Dy-filled skutterudites (Dy _y Fe _x Co_4?x Sb₁₂) have been synthesized by a melting–quenching–annealing method and sintered by the spark plasma sintering technique. Our results suggest that single-phased Dy _y Fe _x Co_4?x Sb₁₂ compounds could be obtained when the Fe content is less than 1.5. The maximum filling fraction of Dy in skutterudites increases with increasing Fe content. We also found significant lattice expansion induced by Fe substitution at Co sites and Dy filling in the voids. The electrical conductivity, Seebeck coefficient, and thermal conductivity have been measured in the temperature range from 300?K to 800?K. The low-temperature Hall coefficient and carrier mobility are reported in the temperature range from 2.5?K to 300?K. The power factor for Dy _y Fe _x Co_4?x Sb₁₂ increases with increasing Fe content. A significant reduction in lattice thermal conductivity is observed in heavy rare earth element Dy-filled skutterudites due to the low localized vibrational frequency of Dy that effectively scatters low-frequency lattice phonons. The sample with composition Dy_0.41Fe_1.45Co_2.55Sb_12.28 has lattice thermal conductivity as low as 1.05?W?m^?1?K^?1 at room temperature. The thermoelectric figure of merit (ZT) reaches a maximum value of 0.67 at 750?K.     

云计算数据库的测试技术研究与应用

介绍了基于云计算的数据库产品的架构,针对云计算数据库在电信企业业务类型负载下的表现,重点分析了云计算数据库的测试技术标准,详细阐述了云计算数据库处理能力的衡量和评估方法。     

基于阵列滤波补偿装置的变频器谐波治理

本文简单分析了变频器谐波产生的机理,介绍了几种变频器谐波的抑制方法,通过比较和实践证明,介绍了一种T型结构无源滤波器,该滤波器由阵列电抗器和滤波电容器串并联组成,整体串于变频器等变流设备前端,对变频器产生的谐波有非常好的滤除效果,可以把变频器产生的电流畸变率控制到5%以内。     

组织光透明技术在骨透明化中的生物医学成像应用与展望

近年来组织光透明技术的飞速发展,为现代骨科临床基础研究带来了新的契机.组织光透明技术主要通过多种物理、化学手段,降低组织的光散射和光吸收,使光能在组织中更好地传播,从而增加光学成像的深度和对比度.结合多种荧光标记策略,实现更深层、更高分辨的骨组织及三维空间微结构信息,为突破骨这种高散射组织及骨疾病的分子影像学研究带来新...     

H.323呼叫模型的实现探讨

传统呼叫中心升级到IP网络呼叫中心，往往采用H．323协议。而采用H．323在IP网络呼叫中心实现CSTA呼叫模型有一定难度。本提出H．450和H．245两种实现方式，并对两进行分析和比较。     

New SAR image interpretation method of aircraft based on joint time-frequency analysis

With the continuous improvement of Synthetic Aperture Radar （SAR） resolution,interpreting the small targets like aircraft in SAR images becomes possible and turn out to be a hot spot in SAR application research.However,due to the complexity of SAR imaging mechanism,interpreting targets in SAR images is a tough problem.This paper presents a new aircraft interpretation method based on the joint time-frequency analysis and multi-dimensional contrasting of basic structures.Moreover,SAR data acquisition experiment is designed for interpreting the aircraft.Analyzing the experiment data with our method,the result shows that the proposed method largely makes use of the SAR data information.The reasonable results can provide some auxiliary support for the SAR images manual interpretation.     

城市应急联动系统GEIS

GEIS（Grid Based Emergency Inter-Act System）是一个基于主体网格的城市应急联动与社会综合服务系统，通过主体网格和通信系统将治安、消防、卫生急救、交通、公共设施，自然灾害等突发事件的应急联动与综合服务，调度集成在一个管理平台中，通过共享指挥平台和基础信息，实现统一接处警，统一指挥，联合行动，快速反应，为市民提供更加便捷的紧急救援及相关服务，为政府科学决策和处置各种紧急与灾害事件提供技术支持为城市公共安全提供技术保障。GEIS的一个突出优势是将范例推理（Case Base Reasoning,CBR）与规则推理（Rule Base Reasoning,RBR）两种人工智能技术相结合，实现了快速预案支持，为科学决策打下良好基础，目前，GEIS已经应用到抗洪抢险和交通事故处理中，效果表明它具有跨平台性好，稳定性强，响应速度快，易操作的独特优势。     

Self-Standing Covalent Organic Framework Membranes for H2/CO2 Separation

Covalent organic frameworks (COFs) are proposed as promising candidates for engineering advanced molecular sieving membranes due to their precise pore sizes, modifiable pore environment, and superior stability. However, COFs are insoluble in common solvents and do not melt at high temperatures, which presents a great challenge for the fabrication of COF-based membranes (COFMs). Herein, for the first time, a new synthetic strategy is reported to prepare continuous and intact self-standing COFMs, including 2D N-COF membrane and 3D COF-300 membrane. Both COFMs show excellent selectivity of H₂/CO₂ mixed gas (13.8 for N-COF membrane and 11 for COF-300 membrane), and especially ultrahigh H₂ permeance (4319 GPU for N-COF membrane and 5160 GPU for COF-300 membrane), which is superior to those of COFMs reported so far. It should be noted that the overall separation performance of self-standing COFMs exceeds the Robeson upper bound. Furthermore, a theoretical study based on Grand Canonical Monte Carlo (GCMC) simulation is performed to explain the excellent separation of H₂/CO₂ through COFMs. Thus, this facile preparation method will provide a broad prospect for the development of self-standing COFMs with highly efficient H₂ purification.     

某电磁屏蔽方舱的优化设计

介绍方舱舱体的屏蔽要求、屏蔽原理、屏蔽效能的测试及计算方法,对某电磁屏蔽方舱进行了测试,针对方舱的门屏蔽效能不足的问题进行了详细的分析,并提出改进建议,比对改进前后的测试结果,提出进一步优化设计的设想.     

一种选择多小波预滤波器的方法

提出了多小波(Multiwavelet)预滤波器的选择原则—预滤波和多小波变换对原数据不引入任何形式的信息损失或失真,该原则对应于预滤波器和多小波滤波器组在频域内能谱密度恒为常数．在此基础上,得到了常用多小波预滤波器应满足的必要条件．提出了用于数据压缩的预滤波器的选择方法,该方法以数据高低频成分分离的分离效率为选择准则．以此准则,给出了常用多小波的最佳预滤波器．仿真实例证实了这种方法的有效性．