摘要：The thermal expansion coefficient(TEC)and thermal conductivity(k)of thermal fillers are key factors for designing thermal management and thermal protection composite *** to its unique advantages,hexagonal boron nitride(h-BN)is one of the most commonly used thermal ***,its TEC and k values are still unclear due to the inconsistency of characterization techniques and sample *** this work,these disputes were addressed using the quasi-harmonic approximation(QHA)method and phonon Boltzmann transport equation(BTE)theory based on the density functional theory(DFT),*** accuracy of our calculated TEC and k values was confirmed by previously reported experimental results,and the underlying physical principles were analyzed from the phonon *** TEC results show that the h-BN has small in-plane negative value and large cross-plane positive value,which are-2.4×10^(-6) and 36.4×10^(-6) K^(-1) at 300 K,*** the anisotropic TEC is mainly determined by the anisotropic isothermal bulk modulus and the low-frequency out-of-plane longitudinal phonon *** found that the convergence of cutoff radius and q-grid size have significant effect on the accuracy of k of *** results show that the in-plane k is much higher than the cross-plane k,and the values at 300 K are 286.6 and 2.7 W m^(-1) K^(-1),*** anisotropic phonon group velocity arising from the vibration behaviors of acoustic phonon modes should be primarily responsible for the anisotropic *** calculated TEC and k values will provide important references for the design of h-BN composite materials.

摘要：纳米技术在能源领域的应用为解决化石燃料的消耗和环境污染问题提供了新的契机.水滑石(LDHs)作为一类典型的阴离子黏土材料,其独特的组成、结构及形貌可调性,使其成为一类优秀的能源储存和转化材料.其中,将水滑石材料进行纳米阵列结构化设计,结合水滑石优异的物理化学性能和纳米阵列的结构特性,已经成为构建高性能电化学电极的重要方法.本文综述了水滑石基纳米阵列电极的合成及其在电化学能量储存和转化上的应用,并进一步讨论了水滑石纳米阵列材料在该领域面临的挑战和发展趋势.

摘要：本文根据中国纪录片的变革,中央电视台和上海电视台创办纪录片栏目的得与失,以及国内外的优秀纪录片制片人的市场经验,探讨中国纪录片市场化栏目的出路。

摘要：Hexagonal boron nitride(h-BN)ceramics have become exceptional materials for heat-resistant components in hypersonic vehicles,owing to their superior thermal stability and excellent dielectric ***,their densification during sintering still poses challenges for researchers,and their mechanical properties are rather *** this study,SrAl_(2)Si_(2)O_(8)(SAS),with low melting point and high strength,was introduced into the h-BN ceramics to facilitate the sintering and reinforce the strength and ***,BN-SAS ceramic composites were fabricated via hot press sintering using h-BN,SrCO_(3),Al_(2)O_(3),and SiO_(2) as raw materials,and effects of sintering pressure on their microstructure,mechanical property,and thermal property were *** thermal shock resistance of BN-SAS ceramic composites was *** show that phases of as-preparedBN-SAS ceramic composites are h-BN and h-SrAl_(2)Si_(2)O_(8).With the increase of sintering pressure,the composites’densities increase,and the mechanical properties shew a rising trend followed by a slight *** a sintering pressure of 20 MPa,their bending strength and fracture toughness are(138±4)MPa and(1.84±0.05)MPa·m^(1/2),*** sintered at 10 MPa exhibit a low coefficient of thermal expansion,with an average of 2.96×10^(-6) K^(-1) in the temperature range from 200 to 1200℃.The BN-SAS ceramic composites prepared at 20 MPa display higher thermal conductivity from 12.42 to 28.42 W·m^(-1)·K^(-1) within the temperature range from room temperature to 1000℃.Notably,BN-SAS composites exhibit remarkable thermal shock resistance,with residual bending strength peaking and subsequently declining sharply under a thermal shock temperature difference ranging from 600 to 1400℃.The maximum residual bending strength is recorded at a temperature difference of 800℃,with a residual strength retention rate of 101%.As the thermal shock temperature difference increase,the degree of oxida

摘要：植被护坡技术愈来愈多地应用于边坡治理,不仅降低了工程成本,达到了固土护坡的作用,而且防止水土流失、保护生态、美化环境,使人类与自然和谐发展。介绍了植被护坡的发展,分析了植被在护坡中的作用,论述了植被护坡工程技术体系、设计框架及景观设计。

摘要：为解决卷接机组接装纸切刀切割过程中存在的因胶垢处理不及时造成接装纸切不断、错动歪斜,人工清洁润滑切刀劳动强度大等问题,设计了一套三工位接装纸切刀自动润滑清洁系统。该系统由3个毛刷通过工位旋转完成清洁润滑工作,3个工位包括工作工位、清洁工位和润滑工位,其旋转直径均为φ119 mm,在电控系统控制下相互配合完成接装纸切刀的自动润滑清洁工作,刮刀和毛刷进给量可调。应用效果表明:①该系统可完成清洁润滑切刀、毛刷自清洁和润滑剂施加工作,并可适用于PASSIM和PROTOS机型。②安装润滑清洁系统的PASSIM卷接机组,废品烟支减少78.2支/天,夹胶块烟支减少1.2支/天,节省毛刷更换时间约120 min/d,降低了操作人员的劳动强度,避免了操作安全隐患,有效提高了设备运行效率。

摘要：以八轮180°回转电差速AGV为主要研究对象,建立了车辆运动学模型、车辆在给定合成角度及合成轮速下各轮子转向角度及轮速对应关系;依据轨迹规划设计结果,构建了前后控制点路径跟踪控制算法,讨论了前后轴控制点目标角度及目标速度计算方法。试验结果表明,车辆在选定运行模式下的速度及转向角度跟踪控制效果良好,整个运行过程车辆运行平稳,最大运行偏差在运行允许范围内,停车偏差小,验证了该算法的有效性。

摘要：珠饰作为人类重要佩饰,自远古之时起就深受人们喜爱。珠饰是出土文物中数量最多、材质最丰富、持续时间最长的一类器物,是古代经济贸易和文化交流的重要物证。采用便携式拉曼光谱仪对长沙五里牌M9东汉墓出土的宝石珠饰进行了原位无损分析,确认这些珠饰由绿柱石族的海蓝宝石、透绿柱石以及显晶质石英的透明水晶、黄水晶制成。相似的海蓝宝石珠饰、龟形饰、海螺形饰和系领珠广泛出土于岭南地区如合浦、广州汉墓,以及东南亚克拉地峡、南亚次大陆等多个地区。我们认为这批宝石珠饰是由南亚或东南亚经海上丝绸之路输入的舶来品,研究结果进一步确立了长沙为海上丝绸之路内陆段贸易和消费的重要节点,并为探讨长江中游地区与东南亚、南亚的文化贸易往来和友好交往提供了新的重要研究材料。

摘要：在变电站现场开展GIS内电压互感器误差校验时,会面临试验一次回路长、GIS管道电容量随管道长短变化等问题,现有试验设备操作复杂且效率低下。通过研究升压试验操作时不同电感补偿方案的影响因素,设计研制了标准电压互感器与带中压补偿试验变压器一体化试验设备,并将其固定安装于新型现场互感器校验车。试验设备使用SF6气体作为绝缘介质。升压装置采用谐振试验变压器,并与标准电压互感器装配于同一气室内部。标准电压互感器设计了特殊结构用于改善系统的不均匀电场分布问题,同时提升了设备使用带中压补偿试验变压器的补偿效果。标准电压互感器与升压器同室对测量结果影响等技术难题得到了有效解决。试验设备配合电动可调电抗器进行试验操作,满足了500 k V电压等级GIS内电压互感现场全电压检测要求,具有可靠性高、操作简便等优点。

摘要：利用热压烧结法制备了梯度型陶瓷—金属复合材料,并对其静态压缩性能和动态冲击压缩性能进行了测试。结果表明:梯度型复合材料具有明显的各向异性,其平行于梯度面的力学性能优于垂直于梯度面的力学性能。复合材料是应变率敏感的材料,随着应变速率的增加,其屈服强度先增高后降低,而其单位体积吸收的能量则呈上升的趋势。