摘要：An orthogonal experiment scheme was designed to investigate the effects of the Cu content,compaction pressure,and sintering temperature on the microstructures and mechanical and thermal properties of(30−50)wt.%Cu/Invar bi-metal matrix composites fabricated via spark plasma sintering(SPS).The results indicated that as the Cu content increased from 30 to 50 wt.%,a continuous Cu network gradually appeared,and the density,thermal conductivity(TC)and coefficient of thermal expansion of the composites noticeably increased,but the tensile strength *** increase in the sintering temperature promoted the Cu/Invar interface diffusion,leading to a reduction in the TC but an enhancement in the tensile strength of the *** compaction pressure comprehensively affected the thermal properties of the *** 50wt.%Cu/Invar composite sintered at 700℃ and 60 MPa had the highest TC(90.7 W/(m·K)),which was significantly higher than the TCs obtained for most of the previously reported Cu/Invar composites.

摘要：为解决光电催化分解水反应器中气泡长时间附着于光电极表面,从而导致有效活化面积减少和产气效率下降的问题,构建耦合振动系统的光电分解水制氢气泡动力学可视化实验平台,提出通过给电极施加不同振幅和频率振动以加速气泡脱离光电极表面的方法。首先,记录静止电极表面单个气泡演化过程中的电信号和几何参数;然后,对比不同频率及振幅下气泡生长过程中电流和电势的变化情况;最后,分析振动对气泡几何特性的影响。研究结果表明:振动频率和振幅的增加能够提高反应过程中的光电流,降低电势,使得反应阻力下降;增加振动频率和振幅均能显著减小气泡脱离尺寸,从而加速气泡的脱离;当振动频率为70 Hz时,施加振动后气泡的脱离直径比无振动时最大减小了321μm,减小幅度约为48%;施加振动后,气泡直径为生长时间的幂函数,且气泡生长依次受惯性和化学反应控制。该研究可为光电催化分解水反应器的优化设计提供新思路。

摘要：The conventional optical system design employs combinations of different lenses to combat aberrations, which usually leads to considerable volume and weight. In this Letter, a tailored design scheme that exploits state-of-the-art digital aberration correction algorithms in addition to traditional optics design is investigated. In particular, the proposed method is applied to the design of refractive telescopes by shifting the burden of correcting chromatic aberrations to software. By enforcing cross-channel information transfer in a post-processing step, the uncorrected chromatic aberrations are well-mitigated. Accordingly, a telescope of F-8, 1400 mm focal length, and 0.14° field of view is designed with only two lens elements. The image quality of the designed telescope is evaluated by comparing it to the equivalent designs with multiple lenses in a traditional optical design manner, which validates the effectiveness of our design scheme.

摘要：研究了不同推介模式下网络零售商的广告策略问题,通过Nash静态博弈方法求解无推介、单向推介以及双向推介三种模式下零售商均衡零售价格、广告努力水平及利润。研究发现:无推介情况下,两零售商均衡广告策略为同时投入广告。单向推介情况下,若利润分享比例较小,则两零售商同时投入广告;若利润分享比例较大,则随着广告成本系数的增大,两零售商均衡广告策略从仅有被推介零售商投入广告转变为同时投入广告。双向推介情况下,若广告成本系数较小,则两家零售商都不投入广告;若广告成本系数较大,则两家零售商同时投入广告。此外,还分析了零售商均衡广告策略下的推介动力问题。

摘要：针对目前中央空调系统运行无效能耗较高、炎热季节能耗巨大的现状,从整个系统的运行模式上探讨了无效能耗的成因,研究需要解决的关键技术。为此开发了一套中央空调系统节能装置。从理论上建立了系统运行的动态数学模型,设定优化运行模式。在智能控制技术的支持下,使中央空调系统按最优模式运行,以达到既保持舒适性要求又节能省电的目的。对装置的节电率进行了比对实测,结果为22.6%,并逐一分析了测试结果。结果表明,装置在南方地区具有广阔的市场前景。

摘要：Intelligent structures like zero Poisson’s ratio(ZPR)cellular structures have been widely applied to the engineering fields such as morphing wings in recent decades,owing to their outstanding characteristics including light weight and low effective modulus. In-plane and out-of-plane mechanical properties of ZPR cellular structures are investigated in this paper. A theoretical method for calculating in-plane tensile modulus,in-plane shear modulus and out-of-plane bending modulus of ZPR cellular structures is proposed,and the impacts of the unit cell geometrical configurations on in-plane tensile modulus,in-plane shear modulus and out-of-plane bending modulus are studied systematically based on finite element(FE)simulation. Experimental tests validate the feasibility and effectiveness of the theoretical and FE analysis. And the results show that the in-plane and out-of-plane mechanical properties of ZPR cellular structures can be manipulated by designing cell geometrical parameters.

摘要：简述了某一曲轴连杆铸件的结构特点,采用顺序凝固理论和均衡凝固理论设计两种工艺方案,通过对比,结果表明,运用大孔出流,均衡凝固理论设计的浇注系统,采用暗冒口配合冷铁工艺,可以有效解决厚大球铁件生产中的铸造缺陷。

摘要：本文设计搭建了一套用于稻谷烘干的生物质能源利用系统,并对系统进行了性能测试与分析。该系统采用稻壳压制成颗粒燃烧产生高温烟气,利用斯特林机发电后,再通过两级换热器将烟气余热回收以加热助燃空气和产生烘干稻谷的热空气。系统采用LabVIEW程序监测并采集各种运行参数,基于此对系统的能源利用率、(?)效率和运行特性进行分析。结果表明,该系统能够在满足稻谷烘干作业的基础上,提供高品质电能,提高稻谷烘干过程中的能源利用效率和(?)效率。

摘要：为了能有效地拓宽压气机的失稳裕度,在一台跨声轴流压气机上进行了基于介质阻挡放电(DBD)等离子体激励扩稳的实验研究.实验中分别选取了正弦交流电源和纳秒脉冲电源提供激励,并在跨声压气机40%设计转速和65%设计转速下对其扩稳效果和效率进行了对比分析.结果表明:在40%设计转速时,正弦交流电源和纳秒脉冲电源均能有效拓宽压气机流量范围,其中正弦交流电源激励方式能够使压气机综合失速裕度改善(SMI)达到15.33%.在65%设计转速时,两种激励方式的扩稳效果明显减弱,此时纳秒脉冲电源激励方式的扩稳效果更好.在压气机效率方面,纳秒脉冲电源对压气机设计点的效率影响更小,在40%设计转速时甚至能略微提升其设计点效率.实验结果表明,合理地选择激励方式有助于提高等离子体激励的扩稳效果,为实际压气机中基于介质阻挡放电等离子体激励扩稳措施的设计提供参考.

摘要：研究一类执行器可能发生部分故障的不确定多时滞离散切换系统的滑模可靠控制问题。针对每个子系统设计相应的拟积分型切换面,保证系统状态轨迹从开始时刻就位于切换面上。利用Lyapunov稳定性理论和线性矩阵不等式技术给出滑模动态系统鲁棒渐近稳定的充分条件,进而给出可实现的滑模可靠切换控制器的设计方案。最后用仿真例子说明设计方法的有效性。