Investigation of Helical Pulse Forming Line

To investigate the feasibility for a helical line to be used as a pulse forming line （PFL）, the transmission characteristics of the helical transmission line is studied both theoretically and experimentally. The results indicate that it is feasible to employ a helical line as a long-pulse PFL, and the influence of its dispersion is negligible. Compared with a conventional coaxial PFL, the helical PFL with the same size can produce a longer pulse.

Properties and Stability of a Meso-Scale Line-Form Disturbance

By using the 3D dynamic equations for small- and meso-scale disturbances, an investigation is performed on the heterotropic instability （including symmetric instability and traversal-type instability） of a zonal line-like disturbance moving at any angle with respect to basic flow, arriving at the following results： （1） with linear shear available, the heterotropic instability of the disturbance will occur only when flow shearing happens in the direction of the line-like disturbance movement or in the direction perpendicular to the disturbance movement, with the heterotropic instability showing the instability of the internal inertial gravity wave; （2） in the presence of second-order non-linear shear, the disturbance of the heterotropic instability includes internal inertial gravity and vortex Rossby waves. For the zonal line-form disturbance under study, the vortex Rossby wave has its source in the second-order shear of meridional basic wind speed in the flow and propagates unidirectionally with respect to the meridional basic flow. As a mesoscale heterotropic instable disturbance, the vortex Rossby wave has its origin from the second shear of the flow in the direction perpendicular to the line-form disturbance and is independent of the condition in the direction parallel to the flow; （3） for general zonal line-like disturbances, if the second-order shear happens in the meridional wind speed, i.e., the second shear of the flow in the direction perpendicular to the line-form disturbance, then the heterotropic instability of the disturbance is likely to be the instability of a mixed Rossby-internal inertial gravity wave; （4） the symmetric instability is actually the instability of the internal inertial gravity wave. The second-order shear in the flow represents an instable factor for a symmetric-type disturbance; （5） the instability of a traversal-type disturbance is the instability of the internal inertial gravity wave when the basic flow is constant or only linearly sheared. With a second or nonlinear vertical shear of the basic flow taken into account, the instability of a traversal-type disturbance may be the instability of a mixed vortex Rossby - gravity wave.

Compact intense electron-beam accelerators based on high energy density liquid pulse forming lines

This paper provides a review of the compact intense electron-beam accelerators (IEBAs) based on liquid pulse forming lines (PFLs) that havebeen developed at the National University of Defense Technology (NUDT) in China. The history and roadmap of the compact IEBAs used todrive high-power microwave (HPM) devices at NUDT are reviewed. The properties of both de-ionized water and glycerin as energy storagemedia are presented. Research into the breakdown properties of liquid dielectrics and the desire to maximize energy storage have resulted in theinvention of several coaxial PFLs with different electromagnetic structures, which are detailed in this paper. These high energy density liquidPFLs have been used to increase the performance of IEBA subsystems, based on which the SPARK (Single Pulse Accelerator with spark gaps)and HEART (High Energy-density Accelerator with Repetitive Transformer) series of IEBAs were constructed. This paper also discusses howthese compact IEBAs have been used to drive typical HPM devices and concludes by summarizing the associated achievements and theconclusions that can be drawn from the results.

智能化生产线在高精度铝管成型制造中的应用实践

探讨了智能化生产线在高精度铝管成型制造中的应用实践,介绍了物联网、大数据分析、云计算平台、人工智能算法、自动化设备,以及信息物理系统,分析了高精度铝管的技术需求,包括尺寸精度、表面质量和力学性能等方面的要求,描述了智能化生产线的设计方案,涵盖了硬件配置和软件系统集成的具体内容。研究表明,智能化生产线的应用不仅能够提高生产效率和产品质量,还能降低运营成本,从而为制造业的转型升级提供了有力支持。

Free-form型机床的切齿优化(一)——优化模型的建立

分析了Free -from型机床的参数形式 ,并建立了优化的数学模型。该模型在原来二阶预控 ,三阶优化的基础上又进一步对 4阶参数进行优化 ,啮合性能进一步提高。利用参数线投影法 。

ESTIMATION OF RESIDUAL CONTACT PRESSURE IN HYDRAULICALLY EXPANDED CRA-LINED PIPE

The mechanically bonded CRA-lined pipe is developed to meet the need forcorrosion-resistant alloy steel pipe. Residual contact pressure at the interface of lined pipe isimportant factor that governs the quality of lined pipe. A simplified theoretical method ispresented to predict the residual contact pressure created by hydraulic pressure. The calculatingequation related hydro-forming pressure to the residual contact pressure between two metal faces isderived. And the validation of the proposed equation is accomplished by comparing its result tothose obtained by experimental investigation.

电网的分散负荷安全域及其应用(二):线路静态失稳的边界-本质-形态及负荷安全域的稳定裕度

交流线路承载的静态稳定边界问题一直悬而未决。负荷安全域可约束线路压差、维持多级电网电压安全水平,但稳定裕度未知。传统静态功角稳定与电压稳定的概念、机理及分析方法都不相同。研究发现,针对线路两种静态稳定可形成统一的概念、机理,而全网静态稳定的充要条件是每条支路都满足静态稳定。基于线路的复变量状态方程,得到末端的复功率-电压(即P_(j)-Q_(j)-U_(j))、复功率-功角(即P_(j)-Q_(j)-θ_(ij))的独立方程;通过可解条件分析、偏导证明,得到唯一的P_(j)-Q_(j)稳定边界及其特征,证明两种失稳的同质性;通过解析几何分析,推导U_(j)和θ_(ij)的稳定边界及其特征,得到符合实际情况的失稳形态解释。基于P_(j)-Q_(j)稳定边界,提出线路负荷安全域的稳定裕度指标以及电压安全水平的修正方法。理论验证基于首端参考系线路模型分析的可行性,提出电网上下级拓扑的稳定域匹配方法。最后,基于状态可观性判据、方程独立性以及平衡点生成原理,分析线路功-角特性的局限性。算例表明,所提的稳定边界、稳定域匹配方法都与PSASP程序收敛性结果吻合。在新能源大量接入导致线路潮流波动性大的背景下,该研究更具理论价值及现实意义。

Perfect Combination of Architectural Functions and Flow Lines: Study on Roof Garden of Frank Gehry's Walt Disney Concert Hall

By exploring the space and the design techniques of roof garden in Frank Gehry's Walt Disney Concert Hall, this paper made further research on the combination of architectural functions and pedestrian fl ow lines, and attempted to summarize the unique design techniques of Frank Gehry by analyzing his works, improve and develop design theories of roof garden, and attract more attention from the public to roof garden design.

Construction of Thin Concrete Lined Walls for Three Gorges Shiplock

With high rock slope in shiplock area, thin reinforced concrete lining walls are constructed for the shiplock system. The construction technology involves much complicated structures in formwork, frequent interference due to crossover working procedures, tight time schedule, high quality of reinforced concrete and showcase appearance requirements, hidden troubles affecting construction safety. With above-mentioned factors in consideration, a single-side-separated sliding formwork technology advanced from past sliding formwork experiences has been developed and applied successfully. This new technology is beneficial in quick and safe operation, capable to assure best quality and appearance of shiplock concrete works, and has filled up the gap in terms of construction sliding formwork in our country.

浅析高地下水位区域渠道衬砌形式

高地下水位渠道衬砌的施工难度大、周期长,通过优化衬砌形式可大大降低施工难度和施工周期。现阶段的高地下水位渠道多采用刚性和柔性衬砌两种形式,通过对格宾石笼衬砌、现浇混凝土板衬砌两种形式的水利条件、施工条件、投资情况等进行综合比选,最终确定渠道全断面采用格宾石笼衬砌。在新疆地区,许多渠道目前仍为土渠,在改建过程中,适当降低格宾石笼的厚度,可为类似的改建和新建项目提供借鉴和参考。

基于ABAQUS的输电线找形与分裂导线模拟研究

架空输电线是输电塔-线体系的重要组成部分,但由于几何非线性特征强,难以直接得到输电线的初始形态。基于ABAQUS有限元分析软件,提出更新形状法和更新张力法两种输电线找形方法,建立单导线模型作为算例进行分析与对比。研究结果表明,两种找形方法均具有很高的精确性,而在操作性和适用范围方面存在区别。由于新建输电线路的需求,分裂导线越来越多地被应用于输电线路中,考虑间隔棒与分裂导线间的耦合作用,提出一种分裂导线的模拟方法,可以实现分裂导线的精细模拟,并通过简化模型和精细化模型的动力特性对比,验证模拟的准确性。提出的输电线找形方法和分裂导线模拟方法可以为输电线路精确建模和分析提供参考。

基于PLC的可降解塑料片材成型自动化生产线设计

塑料片材是塑料制品中的重要组成部分,然而现有的塑料片材生产线自动化程度较低,原料主要成分为聚乙烯,难以降解。据此,采用一种新型的可降解塑料作为原料,但此原料是粉状料,无法适用于传统的粒状送料装置;由于其特点是通过挤出后离模发泡的方式成型为片材,并且原料对温度要求较高,传统挤出机无法使用此料生产。因而根据此原料特性和加工工艺设计由送料系统、挤出成型系统、牵引滚压系统、分切冲孔系统及夹取码垛系统组成的可降解塑料片材成型生产线,使用PLC和触摸屏对控制系统的硬软件进行设计。以平均生产节拍作为参考指标,此自动化产线生产效率提高了26.5%,为可降解塑料产品的规模应用提供了技术支撑。

三维自由弯曲成形管材损伤形式及成形质量对比试验研究

针对三维自由弯曲成形过程中成形装备的模具材料与管材材料匹配性差、管材弯曲成形时表面损伤严重的问题,为了提高管材成形质量,减轻表面损伤程度,研究了不同摩擦条件下管材损伤形式。对不同内衬材料与管材的摩擦副进行了摩擦试验,并基于试验结果对金属试样进行了表面形貌观察分析,获得了不同内衬材料对金属试样造成的损伤机制,分析得出了不同内衬材料与不同管材之间的最优匹配组,完成了三维自由弯曲成形装备模具内衬材料的优化,并进行了管材自由弯曲成形对比试验研究。结果表明,铝合金管材在钨钢内衬模具成形后、不锈钢管材在氧化锆内衬模具成形后的表面光洁无划伤,表面成形质量得到有效改善,同时发现适当减小偏心距、增大成形推进速度可以进一步改善管材表面成形质量。

非匹配负载固态平板Blumlein线的初步设计与输出性能研究

为满足强流介质壁加速器对高倍压比脉冲形成线的研制需求,设计了一种非匹配负载平板固态脉冲形成线(Blumlein线)。首先使用电磁仿真程序研究了平板Blumlein线各参数对输出脉冲宽度的影响,设计并研制了4种形成线进行实验验证;其次利用仿真与实验结合,分析了层叠Blumlein线输出性能下降的主要原因,并提出解决方法;最后对多级Blumlein线的输出性能进行了仿真研究。结果表明:薄平板形成线在非匹配负载工作状态下的耦合作用影响显著,是导致层叠Blumlein线输出性能下降的主要原因;采用对向堆叠结构可有效降低耦合作用、提高波形质量,对向堆叠的20级层叠Blumlein线在1 V输入下可输出峰值33 V、脉宽154 ns的长脉冲,平均倍压比大于1.6,波动±3%的平顶占比37.3%。多级Blumlein线的仿真结果表明,设计的S型平板Blumlein线在多级叠加下具有较好的非匹配负载输出性能,可满足强流介质壁加速器的需求。

面料性能对A字裙坐姿起皱形态的影响

着装褶皱对服装外观有重要影响,常见的褶皱评价指标及传统的二维图像处理技术无法准确、全面反映三维起褶状态。因此,文章利用三维扫描技术对坐姿下A字裙形成的褶皱从褶皱区域、褶皱类型、褶皱大小和褶皱尖锐度四方面建立了一系列新指标,运用单因素方差分析比较了不同种类面料间的褶皱形态差异,并探究了面料性能与褶皱形态指标之间的相关性。研究结果表明,不同面料成分的A字裙在坐姿下形成的褶皱形态各异,其中棉类与其他面料之间各方面差异最为明显。此外,经密、抗弯刚度、褶皱回复性等面料性能对褶皱形态各指标有着不同程度的影响。研究结果可为面料选择及服装三维仿真提供参考。

金属封严环数字孪生几何模型框架的开发与应用

金属封严环广泛应用于航空发动机密封系统,其型面成形质量对飞行器高性能、高可靠服役具有重要影响。然而,薄壁、复杂的异形截面与封闭的环形结构等导致其在几何质量检测方面存在以下问题:其一,成形结果严重依赖于破坏性抽样终检,实际产品均未经过完整质量检测;其二,成形过程无几何质量检测手段,无法及时发现成形缺陷,轮廓几何数据的缺失,使工艺优化设计困难。因此,提出一种金属封严环数字孪生几何模型框架,该框架包括:物理空间、虚拟空间、交互空间与服务,可提供在机测量平台标定、截面轮廓测量、点云数据预处理、截面几何特征计算、三维数模快速构建、三维型面动态测量与偏差计算等连续成形质量在线检测技术,建立起反映金属封严环成形过程中变化的数字孪生几何模型,从而为金属封严环成形质量的检测、分析、预测以及后续工艺优化设计所需的基础数据获取等提供支撑。在此基础上,研制了在线检测模拟试验装置与数字孪生软件,介绍了金属封严环数字孪生几何模型的应用情况。

项目教学法在自动化生产线课程教学中的运用

项目教学法以独立项目为载体,学生在收集信息、设计方案、实施项目的过程中不仅掌握教学知识,而且提升自主探究能力、合作学习能力和创新创造能力。文章以自动化生产线课程为例,首先,介绍课程教学中应用项目教学法的重要意义。随后,从教学实践出发,概述创设情境、细分任务、小组合作、考核评价等教学环节的实施要点。最后,总结应用项目教学法的经验,如坚持以学生为中心原则、围绕课程内容设计项目等,为专业课教学中发挥项目教学法优势和构建高效课堂提供有益帮助。

电触头组件焊接成形工艺及模具设计

以料厚1.2 mm的某电触头组件为研究对象,确定其焊接自动线成形工艺,并设计了1副级进模,模具可实现与焊接机同步自动化生产,在压力机上实现凸模快换。经实际生产验证:模具结构合理,组件成形良好,银点焊接无开裂,为类似组件焊接的自动生产线模具设计提供参考。

影响抽水蓄能电站高压水道衬砌形式选择多因素分析

抽水蓄能电站建设的关键技术问题之一是渗流控制。论文分析了气候等自然地理条件对抽水蓄能电站输水系统所在山体水文地质条件的影响,讨论了钢筋混凝土衬砌及围岩中地下水可能的渗透模式,提出在补水困难、降雨量偏少、岩体质量差、地下水深埋较大的地区,抽水蓄能电站高压水道采用钢衬具有一定的合理性。在高压水道衬砌形式的技术经济综合比选时,建议除了考虑常规的地质条件,还应关注补水工程投入、降雨量等自然地理因素。上述认识对类似工程设计具有一定借鉴作用。

圆锥滚子球基面的立式无磁磨削

圆锥滚子立式球基面无磁磨削具有效率高、导盘不偏载且方便多工位布局的优点,在滚子制造领域日益受到重视。针对该磨削方式,分析了球基面的磨削成形原理、砂轮轴线与滚子公转轴线错位的必要性、隔离盘转速波动及其影响等,结果表明:该磨削方式不存在原理性加工误差,其砂轮轴线与滚子公转轴线有必要错位,从而使砂轮工作面由球面变为圆环面,实现了滚子球基面的线接触磨削;隔离盘转速存在波动,将进料管设置在距离磨削区尽量远的位置并对隔离盘设置转动阻尼,有利于避免隔离盘转速波动产生的负面影响。