摘要：Microstructures and mechanical properties of dual-phase AlxCrMnFeCoNi (x=0.4, 0.5, 0.6, at.%) alloys were investigated. Thermomechanical processing leads to a microstructural evolution from cast dendritic structures to equiaxed ones, consisting of face-centered cubic (fcc) and body-centered cubic (bcc) phases in the two states. The volume fraction of bcc phase increases and the size of fcc grain decreases with increasing Al content, resulting in remarkably improved tensile strength. Specifically, the serrated flow occurring at the medium temperatures varies from type A+B to B+C or C as the testing temperature increases. The average serration amplitude of these Al-containing alloys is larger than that of CoCrFeNiMn alloy due to the enhanced pinning effect. The early small strain produces low-density of dislocation arrays and bowed dislocations in fcc grains while the dislocation climb and shearing mechanism dominate inside bcc grains. The cross-slip and kinks of dislocations are frequently observed and high-density-tangled dislocations lead to dislocation cells after plastic deformation with a high strain.

摘要：The CoCrFeNiMn high entropy alloy was produced by homogenization, cold rolling and recrystallization. The effects of thermomechanical processing on microstructures and tensile properties at different temperatures were investigated using X-ray diffractometry（XRD）, optical microscopy（OM）, scanning electron microscopy（SEM） and multi-functional testing machine. The results show that dendritic structures in cast alloy evolve into equiaxed grains after being recrystallized, with single face-centered cubic（FCC） phase detected. The most refined alloys, stemming from the highest rolling ratio（40%）, exhibit the highest strength due to the grain boundary strengthening, while the variation of elongation with temperature shows a concave feature. For the coarse-grained alloys, both the ductility and work hardening ability decrease monotonically with increasing temperature. Serrated flow observed at intermediate temperatures is attributed to the effective pinning of dislocations, which manifests the occurrence of dynamic strain hardening and results in the deterioration in ductility. Besides, dimples on the fracture surfaces indicate the typical ductile rupture mode.

摘要：针对轴流式涡轮部件结构复杂、精度要求高以及研制周期较长等特点,开展了基于三维光学扫描及逆向工程技术的小尺寸高性能轴流式涡轮部件逆向设计。通过非接触式三维结构光学扫描仪获取了涡轮整体叶盘及导向器实物的点云数据;在点云数据预处理及自动对齐的基础上,利用复杂型面三维重构技术,实现了部件的三维数字化模型重建;基于有限元分析开展了部件的气动性能及结构强度计算,验证了逆向设计轴流式涡轮部件的可行性;并通过进一步梳理总结,建立了轴流式涡轮部件逆向设计流程。结果表明,建立的轴流式涡轮部件逆向设计方法及流程可使得设计部件有效满足实际使用要求,显著缩短设计周期,能够为同类部件的设计提供指导和借鉴。

摘要：为探究硅锌配施对寒地水稻产量、品质及抗倒性的影响,明确高产优质的硅锌优化管理措施,采用二因素完全随机设计,进行3个硅肥水平下3个锌水平的试验研究。结果表明:A2处理水稻秧苗株高、根长差分别较对照显著提高8.0%、16.0%;A2处理地上部分与地下部分鲜重干重较对照分别提高4.8%、23.4%、0.3%、5.7%,差异达到显著或极显著水平;施硅能够提高各节间茎秆抗折力,A2处理抗倒伏指数与A1处理相比提高了15.5%。A2处理穗数、穗粒数、结实率、产量较A1处理分别提高5.3%、5.0%、6.4%、18.5%,随施锌增加穗数、产量呈增加趋势,但硅锌互作对产量及其构成因素不显著。B2、B3各节间抗折力随锌肥的施用增加而呈增加的趋势,抗倒伏指数随锌肥的施用呈增加趋势,但各处理间差异不显著。硅肥和锌肥最优指标施用量的组合为最优配比。

摘要：Four different welding sequences of double-pulse MIG welding were conducted for 6061-T6 aluminum alloy automobile bumpers by using nonlinear elastoplasticity finite element method based on ABAQUS *** post-welding residual stress and deformation were definitely different among the four welding *** results showed that the highest temperature in Solution A was approximately 200℃higher than the melting point of base *** residual stress was resulted from this large temperature gradient and mainly concentrated on the welding vicinity between beam and crash *** welding deformation primarily occurred in both of the contraction of two-ends of the beam and the self-contraction of crash *** with other welding sequences,the residual stress in Solution A was the smallest,whereas the welding deformation was the ***,the optimal sequence was Solution B because of the effective reduction of residual stress and good assembly requirements.

摘要：文章研究了广告宣传的公司治理效应,结果表明广告宣传能够通过提升股票流动性完善公司治理,这一结果既为广告宣传的研究和实践提供了全新的视角,也为广告宣传作为上市公司外部治理机制提供了实证经验。文章证实,与一般类型的公司相比,危机型公司的广告宣传能够在更大程度上完善公司治理。因此,上市公司的广告宣传应在现有关注产品市场和品牌知名度的基础上充分考虑治理效应,以更好地优化资源配置。

摘要：该文以双笼转子无刷双馈感应发电机为主要研究对象。为了解决不平衡电网电压带来的功率绕组(power winding,PW)定子绕组功率脉动和电流不平衡的问题,设计了简化矢量控制策略,对PW侧谐波功率和负序电流进行抑制。此外,通过建立控制绕组(control winding,CW)电流统一表达式,对各个控制目标之间的关系进行了数学推导和理论分析。在此基础上,建立了PW电流不平衡度约束条件下,针对PW有功功率脉动幅值和无功功率脉动幅值的多目标控制数学模型。并采用粒子群算法进行求解,对CW统一电流表达式中的系数进行优化,计算CW参考电流值从而实现多目标控制。最后在双笼转子无刷双馈感应发电机实验平台上,对所提出的控制策略的有效性和理论推导的正确性进行了验证。

摘要：针对目前微电网控制器成本较高、标准各异、集成度低和缺乏具有实际操作性的能量管理策略等问题,设计了一种集计量监控和能量管理一体化的园区微电网中央控制器。采用基于ARM的嵌入式系统硬件平台,模块化设计。考虑到园区企业用能需求,开发了具有园区特色的能量管理策略,给出一种基于三次指数平滑法的需量预测方法并利用储能系统来进行需量管理,在不影响企业办公生产的同时降低用电成本。通过搭建物理实验平台对中央控制器的功能和能量管理策略进行了验证,具有较好的实用性。

摘要：在轨光学相机探测图像数字仿真系统可为空间相机的方案设计、信息处理算法研究与验证及地面性能测试等提供技术支持。本文根据在轨光学相机测量原理与工作环境,建立了空间目标的相对运动学与反射光学特征模型、相机成像模型以及背景恒星成像模型;分析了相机测量噪声及相机探测灵敏度并在仿真中考虑了干扰因素对成像质量的影响,完成了现有星表中背景恒星的视星等,根据相机的探测波段范围进行了仪器星等的等效计算(探测星等>9 mV,计算误差<10%),提高了仿真图像的逼真度;最后,根据相机工作原理设计了仿真流程,应用Visual C++与Open×GL技术实现了仿真软件并根据具体的在轨光学相机CCD与光学系统参数对探测图像生成方法进行了仿真验证。结果表明,该系统能够满足空间相机研制与性能测试的要求。

摘要：由于具有三维空腔结构及良好的应用前景,穴醚逐渐成为超分子研究领域的热点之一.近年来,我们课题组设计合成了一系列基于双间苯-32-冠-10穴醚主体分子,并利用这些穴醚分子构筑了不同的超分子组装体.首先,将双硫代四硫富瓦烯(STTFS)引入到穴醚的第三个臂上,成功构筑了具有氧化还原响应性的穴醚主体分子.该穴醚与客体间的解离-穿环过程可以利用STTFS的氧化态来进行控制;其次,设计合成了两种含有P=O官能团桥连的穴醚,在固态结构中得到了近似线型和Z字型的不同超分子聚[2]准轮烷;最后,合成了具有两种不同性质空腔的柱[5]芳烃稠合穴醚主体分子,该穴醚通过正交作用同时络合两个不同的客体分子.基于两种不同主客体作用力,我们构筑了一种新型的超分子聚合物.以上研究为分子器件和超分子材料的进一步研究奠定了良好的基础.