摘要：Helical metal-organic frameworks(MOFs)were used as templates or precursors to fabricate helical carbon nanorods(HCNRs)for the first *** carbon contains many topological defects such as pentagonal or heptagonal carbons,which have the potential to facilitate oxygen reduction reactions(ORR).HCNRs show more positive onset/halfwave reduction potentials and higher limited current density than straight carbon nanorods(SCNRs).They also exhibit four-electron oxygen reduction in tests of ORR,while the alternative SCNRs prefer a two-electron reduction *** and theoretical studies reveal that these enhanced ORR activities can be attributed to pentagon/heptagon defects in *** work provides an effective strategy to synthesize helical,defect-rich carbon materials and opens up a new perspective for utilization of a spiral effect for the development of more effective electrocatalysts.

摘要：为了减少能量损耗且同时满足紧密纺和落棉系统的除尘要求,将单节48锭紧密纺风系统和小型化落棉风系统组合设计为一个风系统.通过试验对组合系统进行验证,并采用三维建模软件PROE与CFD软件FLUENT对系统进行三维数值模拟,分析了组合系统内部流场的风速、压力和流量的变化情况.结果表明:紧密纺系统测点平均风速为9 m/s,达到了紧密纺系统孔口风速要求;落棉系统测点平均风速为7.8 m/s,与落棉系统孔口风速要求相差了0.2 m/s,误差仅为2.5%,在误差允许范围内,说明该组合系统设计合理;风道内部风速和压力分布相对稳定,说明该组合系统稳定性较强,符合流体力学节点压力相等的设计理论.

摘要：芳纶/高强聚乙烯纤维混杂复合材料具有灵活的可设计性和较高的减重效率,设计制备了2种层间混杂、2种夹芯混杂和层内混杂共5种混杂结构的芳纶/高强聚乙烯纤维混杂复合材料层板,通过落锤冲击试验研究了混杂结构、高强聚乙烯纤维混杂含量对其冲击载荷、冲击弹性应变能、冲击损伤形貌等抗冲击性能的影响。结果表明,芳纶/高强聚乙烯纤维混杂复合材料层板载荷峰值均大于2种单一纤维复合材料层板,试样冲击正面与背面均为芳纶纤维的层间混杂层板冲击载荷峰值最大,冲击正面与背面均为高强聚乙烯纤维的混杂层板分层损伤严重;5种混杂结构层板吸收的能量均小于单一纤维层板,而弹性应变能均大于单一纤维层板。在冲击能量相近的情况下,层内混杂层板冲击后损伤面积最小;随着高强聚乙烯纤维混杂含量增加,载荷峰值先增大后减小,当高强聚乙烯纤维混杂含量约为40%时,层间混杂复合材料层板冲击载荷峰值最大。文中进一步分析了混杂复合材料层板的冲击损伤破坏机制,为低速冲击防护产品的研发提供一定设计依据。

摘要：As future soft robotic devices necessitate a level of complexity surpassing current standards,a new design approach is needed that integrates multiple systems necessary to synchronize the motions of soft actuators and the response of signals,thereby enhancing the intelligence of flexible ***,we propose a liquid crystal elastomer unit cell-based platform that organizes the cells in a group to create expandable *** unit cell behaves like a flexible module that can expand biaxially into a specific,stable,and controllable *** the unit cells in different manners results in an adaptable soft grasper,a half-adder for information processing,and a tunable phononic *** implies a high level of reconfigurability and scalability in both structures and functions by elegantly reassembling the unit *** design strategy has the potential to integrate multiple functions that traditional soft actuators cannot accommodate,providing a platform for developing intelligent soft robotics.

摘要：震害调查研究表明穿越活动断裂带隧道的破坏是极其严重的。以太原市城市轨道交通1号线一期工程区间隧道穿越交城断裂带为工程依托,通过Pasternak双参数地基模型建立力学分析模型并推导了正断层错动下地下管线纵向响应解析解,然后采用ABAQUS软件建立了三维精细化有限元模型。解析解计算结果与数值模拟计算结果吻合度较好,证明了解析解的正确性。最后,在设定的重点设防区域内采用节段衬砌+柔性接头组合形式,对比分析节段长度、接头纵向位置和柔性接头宽度对隧道结构整体减灾效果影响。结果表明:正断层错动下地下管线纵向响应的解析解计算结果可为重点设防区域的确定提供参考。采用节段衬砌+柔性接头组合形式可有效降低隧道结构的破坏程度和范围。正断层错动作用时,节段长度越短隧道结构破坏范围越小,柔性接头宽度的增加会降低隧道结构的破坏程度和范围,破坏区域集中在节段衬砌结构的端头部位。采用对缝模式设置柔性接头时可最大程度发挥接头的变形吸能作用,其减灾效果最优。研究可为穿越活动断裂带隧道工程采用节段+柔性接头组合形式的抗断设计和分析提供理论依据。

摘要：针对拖拉机发动机供油结构进行了优化设计和试验研究。首先,介绍了拖拉机发动机供油系统的组成部分和工作原理,分析了供油系统存在的问题;然后,提出了一种改进的供油结构设计方案,并基于响应面法进行优化试验。试验结果表明:通过分析得到优化结果为转速3 000 r/min、旋转油道直径6 mm、油路压力120 MPa,此时理论摩擦功耗为60.09%,端泄流量为0.602,满足生产要求。研究结果为拖拉机发动机供油系统的优化设计提供了参考依据,具有一定的理论和实际意义。

摘要：Developing excellent pseudocapacitive electrodes with long cycle,high areal capacity and large rate has been challenged.3 D printing is an additive manufacture technique that has been explored to construct microelectrodes of arbitrary geometries for high-energy–density *** comparison with conventional electrodes with uncontrollable geometries and architectures,3 D-printed electrodes possess unique advantage in geometrical shape,mechanical properties,surface area,especially in ion transport and charge ***,a desirable 3 D electrode with ordered porous structures can be elaborately designed by 3 D printing technology for improving electrochemical capacitance and rate *** this work,a designed,monolithic and ordered multi-porous 3 D Cu conductive skeleton was manufactured through 3 D direct ink writing technique and coated with Cu O nanosheet arrays by an in situ electro-oxidation *** from the highly ordered multiporous nature,the 3 D-structured skeleton can eff ectively enlarge the surface area,enhance the penetration of electrolyte and facilitate fast electron and ion *** a result,the 3 D-printed Cu deposited with electro-oxidation-generated CuO(3 DP Cu@Cu O)electrodes demonstrates an ultrahigh areal capacitance of 1.690 F cm^(-2)(38.79 F cm^(-3))at a large current density of 30 m A cm^(-2)(688.59 m A cm^(-3)),excellent lifespan of 88.20%capacitance retention after 10,000 cycles at 30 m A cm^(-2) and superior rate capability(94.31%retention,2-30 m A cm^(-2)).This design concept of 3 D printing multi-porous current collector with hierarchical active materials provides a novel way to build high-performance 3 D microelectrodes.

摘要：Not confined to a certain point,such as waveform,this paper systematically studies the low-intercept radio frequency(RF)stealth design of synthetic aperture radar(SAR)from the system *** study is carried out from two *** the first level,the maximum low-intercept range equation of the conventional SAR system is deduced firstly,and then the maximum low-intercept range equation of the multiple-input multiple-output SAR system is *** the second level,the waveform design and imaging method of the low-intercept RF SAR system are given and verified by ***,the main technical characteristics of the lowintercept RF stealth SAR system are given to guide the design of low-intercept RF stealth SAR system.

摘要：为提高海上货物转运的安全性,提出基于绳牵引并联装置的六自由度波浪补偿机构结构设计方案。以4级海况为背景,增大工作空间为目的,在补偿需求和抗摆约束下,使用Matlab软件求解多组不同参数机构在横摇和纵摇方向的力旋量可行工作空间与动平台抗摆轨迹,逐一对比分析优化机构参数,最终通过样机实验验证了仿真结论的正确性,证明了4级海况下机构具有足够的波浪补偿能力并可完全消除负载摆动。

摘要：为了实现房屋的折叠与展开并满足其受力需求,在传统剪支铰折叠结构的基础上,提出一种新型杆式折叠结构。首先,对新型杆式折叠结构进行设计和优化,采用螺旋理论对其进行自由度分析。同时,建立高度为2.2 m的ABAQUS有限元模型,对其施加平面内竖向荷载,获得不同铰接约束次数、钢材强度等级、销轴孔径、槽钢立柱壁厚、杆件宽度条件下折叠结构的初始刚度、极限承载力和破坏模式。最后,对折叠结构进行稳定性分析,提出了设计建议。结果表明:当折叠结构展开后高宽比为1/√2时,可以达到最大折叠率;折叠结构展开过程中机构自由度为1,当折叠结构完全展开并施加一定铰接约束后结构自由度为负值;次要受力杆件、销轴孔径对结构初始刚度和极限承载力影响不大;提高钢材强度等级、槽钢立柱壁厚、主要受力构件宽度可提高结构初始刚度和极限承载力,但是其值过高时会导致结构发生失稳破坏;为避免结构失稳,可通过促进塑性铰形成和将特定杆件改为箱形截面两种途径来实现。