高频变压器漏电感简化计算方法

绕组高频效应使高频变压器漏感参数具有复杂的频变特性.但传统算法并未考虑漏磁的频变特性导致计算精度较差,而现代计算方法单纯地套用Dowell公式,并且没有考虑不同绕组结构的漏磁分布特性,导致公式通用性较低,在实际工程中难以使用.本文在对高频变压器实际漏磁分布模型分析的基础上,提出一种高频漏磁分布等效变换模型,并基于磁链分...     

超声红外热波成像在CFRP板螺栓孔损伤检测的研究

螺栓连接由于可靠性高、承载能力强等优势广泛应用于复合材料连接,但螺栓孔处的应力集中作用使其易产生损伤破坏,且工程应用中很多复合材料螺栓连接件无法卸载,传统检测方法较难对螺栓孔损伤进行识别.本文使用超声红外热波检测的方法对复合材料螺栓连接件进行损伤识别,通过仿真研究复合材料螺栓孔裂纹和分层损伤的生热特征,分析了螺栓以及螺栓预紧力对螺栓孔损伤生热特征的影响,并设计实验对仿真结论进行了较好的验证.研究显示当螺栓孔损伤区域超出螺帽覆盖的范围,超声红外热波检测法能快速有效检测螺栓紧固件损伤,结合图像识别方法可以有效提取损伤信息,而且该方法对不同大小的螺栓预紧力以及螺栓与被连接件之间的摩擦生热影响有着良好的适应性.     

电压对Zr-4合金Na2SiO3−(NaPO3)6−K2ZrF6体系微弧氧化膜性能的影响

在Na2SiO3?(NaPO3)6?K2ZrF6体系中采用微弧氧化法以Zr-4合金为基材制备出陶瓷膜层.利用扫描电镜、粗糙度仪、X射线衍射仪、X射线光电子能谱仪和电化学工作站研究了电压对膜层结构与性能的影响.结果表明,膜层表面呈典型"火山口"形貌,电压升高后膜层粗糙度与致密层厚度增加.膜层主要由单斜氧化锆相(m-ZrO...     

具身形态学：基于身体行为的计算性几何

文章从建筑形式的具身性本质出发，分析了多重身体维度下行为规律与建筑空间几何的关联性。文章进一步聚焦计算性几何的范畴，通过对基于数字化技术的行为研究进行综述，对行为规律的“几何化”路径进行了分析。在此基础上，文章通过一系列研究和实践案例，总结出从行为规律逆向推导建筑空间几何的计算性设计方法，并讨论了基于“行为几何”的设计应用场景，拓展了基于建筑与身体关系的形态认知和操作边界。     

Simulation study of the thermal insulation performance of a vacuum-insulated tube inside an electrically heated device

To realize stable heating of a heated cigarette while effectively controlling the outer-wall temperature of an electric heating-type appliance, a vacuum-insulated tube (VIT) is currently widely used for thermal insulation against the heating element. The effects of the critical parameters of the VIT, gases at different pressures, wall thickness, and material on its thermal insulation performance, were simulated using Fluent to provide guidance on the structure and performance optimization of the EHD. When the absolute pressure of gas in the VIT was <0.5 Pa, increasing the degree of vacuum did not improve the thermal insulation performance. The thermal insulation performance of VITs made from different materials (stainless steel, copper, aluminium, brass, and titanium alloy) was closely related to the emissivity and thermal conductivity of the material. Stainless steel yielded better overall thermal insulation owing to its low thermal conductivity and emissivity. Highly emissive materials, such as brass and titanium alloy, contributed to higher heat transfers through the radiation inside the vacuum chamber and external radiation from the VIT, decreasing the thermal insulation performance of the VIT. Stainless steel VITs yielded an improved thermal insulation performance as the wall thickness decreased, but at the cost of decreased mechanical stability. For a wall thickness of 0.05–0.30 mm, stainless steel yielded the best structural stability. VITs with different wall thicknesses were made from stainless steel, copper, and aluminium, and the thermal insulation performance and structural stability of the EHD were optimized.     

Partitioning and mapping in embedded multiprocessor architectures in the presence of constraints

The paper focuses on the problem of partitioning and mapping parallel programs onto heterogeneous embedded multiprocessor architectures for real-time applications. Such applications present unique constraints and challenges. In addition to heterogeneity, the proposed partitioning and mapping algorithms satisfy memory, task throughput, task placement, intertask communication bandwidth, and co-location constraints. They do so for architectures that utilize circuit-switched (rather than packet-switched) interprocessor communication and optimize latency and throughput in addition to load-balancing. Finally, these mapping algorithms make use of knowledge of the local scheduling discipline to accommodate real-time scheduling constraints. Our focus is on unstructured parallel programs that fall into one of two classes: (i) the class of computations characteristic of control applications in a real-time environment where tasks execute concurrently, periodically exchanging information, and (ii) pipelined computation graphs found in sensor data processing applications. The algorithms are implemented in a set of tools that operate with commercial CASE tools at one end, and present an interface to multiprocessor simulators at the other end. Collectively, the algorithms form a significant component of an interactive design environment for the development and mapping of real-time embedded parallel programs. The paper describes the algorithms, the encapsulating toolset, and presents an example of their application to an existing embedded application—an Autonomous Underwater Vehicle application.     

磁致变刚度原理的气动软体致动器设计与试验

软体机器人友好的人机交互特性使其在柔性抓取、生物医疗等领域有着广泛的应用前景。针对软体机器人“柔有余而刚不足”的缺陷，提出了一种具有快速、可逆变刚度能力的磁气混合驱动软体致动器。基于磁流变效应，设计了以磁流变弹性体材料作为基体的单自由度纤维增强型磁气混合软体致动器，并给出了软体致动器的浇注制造工艺。构建了磁-力耦合模型，分析磁流变弹性体中的刚度影响关系。基于自主开发的刚度测试平台，试验结果表明：设计开发的软体致动器可以在气压和磁场作用下实现可变刚度混合驱动，通过增加磁场强度可以明显提升软体致动器的刚度，最高可提高约40%。软体致动器末端位置控制实验结果表明：通过磁场激励作用，可将软体致动器携带负载的位姿保持能力提高1.4倍，具有动载荷下的位置保持驱动能力，调节响应时间小于1.5 s。     

Fixturing technology and system for thin-walled parts machining: a review

During the overall processing of thin-walled parts (TWPs), the guaranteed capability of the machining process and quality is determined by fixtures. Therefore, reliable fixtures suitable for the structure and machining process of TWP are essential. In this review, the key role of fixtures in the manufacturing system is initially discussed. The main problems in machining and workholding due to the characteristics of TWP are then analyzed in detail. Afterward, the definition of TWP fixtures is reinterpreted from narrow and broad perspectives. Fixture functions corresponding to the issues of machining and workholding are then clearly stated. Fixture categories are classified systematically according to previous research achievements, and the operation mode, functional characteristics, and structure of each fixture are comprehensively described. The function and execution mode of TWP fixtures are then systematically summarized and analyzed, and the functions of various TWP fixtures are evaluated. Some directions for future research on TWP fixtures technology are also proposed. The main purpose of this review is to provide some reference and guidance for scholars to examine TWP fixtures.     

Fabrication and mechanical properties of self‐reinforced polyester composites by double covered uncommingled yarn

Self‐reinforced poly(ethylene terephthalate) (srPET) composites composed of double covered uncommingled yarn that was prepared through cowrap spinning were hot pressed using a film stacking technique. The optimal consolidation temperature for manufacturing lamina was determined to be 240°C and resulting in the adequate impregnation and reinforcing structural integrity. The srPET laminates that had a plain structure exhibited the excellent tensile responses, whereas those with a twill weaving structure had the highest impact energy absorption. In the plain fabric, there were more interlace points and a higher crook degree of wrap and weft yarns in the periodic unit cell, resulting in more clamp force on the yarns at the interlace points during stretching and more elongation. The srPET composites prepared using basket‐weaving structural fabric broke apart and resulted in the lowest impact energy, which can be attributed to the larger gap between two interweaving points that creates a weak path. A strong influence from the weaving structure was observed for the α relaxation of the composites. T_α shifted to a higher temperature because the reinforcing of the fibers and the structural integrity was more effective. POLYM. COMPOS., 37:3331–3340, 2016. © 2015 Society of Plastics Engineers