防爆工程车刚-柔耦合虚拟样机关键技术研究

为了对防爆工程车进行动态仿真研究,就需要建立一个符合车辆特性和工况的虚拟样机模型。通过理论分析,将工程车虚拟样机分为刚性体系统和柔性体系统两类,共同组成了刚-柔耦合的多体系统虚拟样机。对系统关键部件和技术进行建模和研究,为同类型车辆的虚拟样机建模和研究提供了理论参考。     

乡村振兴背景下的村镇建设思考

乡村振兴战略和实施乡村建设行动对村镇建设提出更高、更全面的要求.村镇建设品质提升需要多方位的技术支撑,在村镇建设各专业领域的研究应用基础上,把握我国村镇建设现状需求,从村镇规划、防灾减灾、绿色建造体系、节能和清洁能源利用、人居环境提质以及智慧村镇管理等方面提出研究方向和重点解决的关键技术,为全面支撑宜居村镇建设提供坚实的基础,助力国家战略,实现乡村振兴,推进乡村建设行动健康发展.     

Enantioselective Synthesis of 4H‐Pyrans Through Organocatalytic Asymmetric Formal [3+3] Cycloadditions of 2‐(1‐Alkynyl)‐2‐alken‐1‐ones with β‐Keto Esters

4H‐Pyran units are frequently present in molecules with significant biological and pharmaceutical activities. Herein, we present the first enantioselective formal [3+3] cycloaddition between 2‐(1‐alkynyl)‐2‐alken‐1‐ones and β‐keto esters catalyzed by a cyclohexyldiamine‐based thiourea‐tertiary amine bifunctional catalyst. Under the mild and eco‐friendly conditions, a wide range of polysubstituted 4H‐pyrans were obtained in moderate yields with good enantioselectivities.

     

分时电价下梯级水电站日优化调度模型的探讨

梯级水电站日优化调度模型在考虑电网负荷要求和梯级水电站各机组的振动区的前提下,采用电网允许的峰平谷负荷比约束日内各时段的出力,达到了减少机组起停次数的目的。模型采用动态定出力求解,以梯级电站发电收入最大化为目标,并用实例对此模型进行了计算。计算过程和结果表明,动态定出力求解时间短,优化结果与目前的电网需求相一致。     

红枣乳酸发酵饮料的研制

以红枣为原料，经乳酸发酵制成发酵饮料。通过对产品的工艺条件进行试验，得出枣浆最佳发酵条件为：接种量5％，发酵温度42℃，培养时间6h，乳糖1％，蔗糖12％；稳定剂添加量为：琼脂0.15％，黄原胶0．09％，海藻酸钠0．06％，杀菌条件：温度85℃，时间10min，最终使饮料的pH值调到3．7。     

环锭纺纱全流程机器人自动化生产关键技术

针对环锭纺纱全流程自动化生产工艺与工业机器人的深度集成问题,提出了环锭纺纱生产线布局仿真优化方法,构建了生产线协同调度模型,详细阐述了配棉排包、精梳机自动喂棉卷和筒纱外观检测等关键工艺机器人应用场景,提出了以信息互联互通技术为核心的信息集成管控策略,建立了工艺、生产计划、质量、设备及物流一体化智能管控系统,形成了环锭纺纱生产线全流程智能管理模式,实现了基于纱管的纺纱质量追溯。结果表明:所使用的任务调度方法有效提升了相关工序的生产效率,设计的纺纱工艺机器人打通了配棉排包等工艺流程断点,相关技术应用后企业综合生产效率提升22.65%,运营成本降低40%,形成纺纱行业智能化转型典型案例并已向行业推广。     

Exploration of the oxygen transport behavior in non-precious metal catalyst-based cathode catalyst layer for proton exchange membrane fuel cells

High cost has undoubtedly become the biggest obstacle to the commercialization of proton exchange membrane fuel cells (PEMFCs), in which Pt-based catalysts employed in the cathodic catalyst layer (CCL) account for the major portion of the cost. Although non-precious metal catalysts (NPMCs) show appreciable activity and stability in the oxygen reduction reaction (ORR), the performance of fuel cells based on NPMCs remains unsatisfactory compared to those using Pt-based CCL. Therefore, most studies on NPMC-based fuel cells focus on developing highly active catalysts rather than facilitating oxygen transport. In this work, the oxygen transport behavior in CCLs based on highly active Fe-N-C catalysts is comprehensively explored through the elaborate design of two types of membrane electrode structures, one containing low-Pt-based CCL and NPMC-based dummy catalyst layer (DCL) and the other containing only the NPMC-based CCL. Using Zn-N-C based DCLs of different thickness, the bulk oxygen transport resistance at the unit thickness in NPMC-based CCL was quantified via the limiting current method combined with linear fitting analysis. Then, the local and bulk resistances in NPMC-based CCLs were quantified via the limiting current method and scanning electron microscopy, respectively. Results show that the ratios of local and bulk oxygen transport resistances in NPMC-based CCL are 80% and 20%, respectively, and that an enhancement of local oxygen transport is critical to greatly improve the performance of NPMC-based PEMFCs. Furthermore, the activity of active sites per unit in NPMC-based CCLs was determined to be lower than that in the Pt-based CCL, thus explaining worse cell performance of NPMC-based membrane electrode assemblys (MEAs). It is believed that the development of NPMC-based PEMFCs should proceed not only through the design of catalysts with higher activity but also through the improvement of oxygen transport in the CCL.     

Performance and degradation of metal-supported solid oxide fuel cells with impregnated electrodes

Metal-supported solid oxide fuel cells (MS-SOFCs) containing porous 430L stainless steel supports, YSZ electrolytes and porous YSZ cathode backbones are fabricated by tape casting, laminating and co-firing in a reducing atmosphere. Nano-scale Ni and La_0.6Sr_0.4Fe_0.9Sc_0.1O_3−δ (LSFSc) coatings are impregnated onto the internal surfaces of porous 430L and YSZ, acting as the anode and the cathode catalysts, respectively. The resulting MS-SOFCs exhibit maximum power densities of 193, 418, 636 and 907 mW cm⁻² at 650, 700, 750 and 800 °C, respectively. Nevertheless, a continuous degradation in the fuel cell performance is observed at 650 °C and 0.7 V during a 200-h durability measurement. Possible degradation mechanisms were discussed in detail.     

GGSN协议的一个流程问题分析及改进

在网关GPRS(通用无线分组业务)支持节点(GGSN)项目与服务GPRS支持节点(SGSN)项的集成测试中发现了GGSN相关协议的一处流程交互的定义的缺陷,该缺陷导致在异常的流程处理中大量垃圾上下文的生成,并使得GGSN与SGSN两侧信息产生较大的不一致,这些不一致的信息将在较长时间影响系统的后续运行并产生运行错误.本文分析了此流程缺陷产生的原因并对相应流程提出一种改进的方法.实验环境下的测试结果表明,对协议做这样的改进可以完全解决这一问题并保证工程实现的高效性.     

Thermal degradation and fire performance of wood treated with PMUF resin and boron compounds

Plantation Chinese fir wood was modified by low molecular weight phenol melamine urea formaldehyde (PMUF) resin, boron compounds (BB), and the mixture of PMUF/BB (PMUF‐BB), followed by a curing step. The fire performance and thermal degradation of wood was measured by limiting oxygen index instrument, cone calorimeter, and simultaneous thermal analysis. The results showed that the limiting oxygen index increased to 50.7%, 43.5%, and 55.0% for BB, PMUF, and PMUF‐BB samples, respectively. The PMUF resin decreased the heat release rate of wood but increased the total heat release compared with the control samples. The thermal analysis results demonstrated that PMUF resin enhanced the thermal stability of wood, however, had little impact on the residual chars. Combinative treatment with boron compounds could substantially reduce the fire risk for PMUF‐modified wood, making them especially useful for application in public settings.