基于多目标优化的乘客电梯理想速度运行曲线确定方法

目的研究一种借助多目标优化模型求得电梯理想速度曲线的确定方法,解决乘客电梯快速性和舒适性问题．方法分析电梯实际运行方式,构建理想速度曲线组合模式;结合实际及相关国家标准,建立求取理想速度曲线参数的多目标优化模型;借助多目标遗传算法NS-GA-Ⅱ解得理想速度曲线参数的Pareto解集,并基于偏好进行区域划分．结果通过对电梯速度曲线参数的多目标优化求解,获得不同偏好的乘客电梯理想速度曲线．结论不同偏好、不同额定速度下电梯理想速度曲线对比分析结果表明,基于多目标优化的乘客电梯理想速度曲线确定方法在兼顾电梯运行的快速性及舒适性要求的同时为技术人员提供了多种可供选择的运行速度控制模式;对额定速度不高于3．5m／s的乘客电梯,其理想速度曲线可省去直线加速段以降低速度控制模式的复杂性．     

微信对高校共青团工作的影响及对策研究

随着信息技术的快速发展,以微信为代表的新媒体发展迅猛,微信一方面为高校共青团工作提供了更为方便快捷的通道,另一方面也对高校共青团工作的管理者提出了严峻的挑战。高校共青团应正确分析微信对工作带来的影响,努力寻求微信息时代背景下以微信为代表的高校共青团工作对策,不断提高高校共青团工作的影响力。     

液膜法提取废水中Cr3+相界面反应的热力学研究

选择新型的超分子化合物——对叔丁基杯[4]芳烃乙酸作为活性载体,研究了采用乳状液膜法分离废水中Cr3 的界面反应方程式及反应的热力学性质。研究表明液膜外相界面的反应符合阳离子交换机理,液膜内相界面的反应为氧化还原反应;得到了外相界面及内相界面反应的平衡常数K分别为2.45×10-4、1027.5(30℃时),反应焓△H分别为69.9、-159.4 kJ.mol-1,反应自由焓△G分别是-25.0、-159.4 kJ.mol-1,反应熵△S分别是316.4、75.531 kJ.mol-1K-1。     

鄂尔多斯盆地低渗-致密气藏水平井全生命周期开发技术及展望

基于鄂尔多斯盆地天然气开发实践,系统描述了低渗-致密气藏地质特征。依据水平井开发的主要对象、技术参数和生产指标等因素,将水平井开发历程划分为实践探索、攻关试验、规模应用和优化提升4个阶段。详细阐述了鄂尔多斯盆地水平井开发的技术内涵,系列开发技术包括多学科甜点优选技术、多层系大井丛整体部署技术、多专业融合导向技术、精细化压裂改造技术以及全生命周期生产管理。综合评价了不同气藏水平井的开发效果及潜力,认为致密气水平井具有良好的开发效果和前景;明确了加强多学科全过程联合研究是水平井技术发展的主要方向,也是实现低品位天然气资源规模、效益开发的关键。今后面对深、薄、低丰度等更为复杂的开发对象,将针对性地优化、提升苏里格等老气田水平井技术,攻关形成庆阳、宜川等新气田水平井配套技术,超前储备页岩气、煤层气等新型天然气资源水平井有效开发技术,为鄂尔多斯盆地天然气上产及稳产提供技术保障。     

Thermally activated giant piezoelectricity and enhanced interface elastic strain-mediated magnetoelectric coupling

Perovskite materials with compositions in the vicinity of the steep morphotropic phase boundary (MPB) exhibit various intriguing properties including giant piezoelectricity and large dielectric constant. Aside from composition, the phase configuration of the perovskites is also strongly related to the ambient temperature. Here, we report a giant piezoelectricity of 10 980 pm/V at 93°C in the 0.7Pb(Mg_1/3Nb_2/3)O₃-0.3PbTiO₃ (PMN-PT) single crystals which is more than five times larger than that at room temperature. The enhanced piezoelectricity can be attributed to the instability of the thermally induced tetragonal phase which can be converted to the orthorhombic phase by the external electric field in the <011> oriented single crystal. The transverse piezoelectricity has been investigated by measuring the electric-field-dependent ferromagnetic resonance (FMR) field in the CoFeB/PMN-PT magnetoelectric (ME) heterostructures. The ME coupling coefficient has been increased from 49.3 to 476 Oe cm/kV as temperature increased from 25 to 90°C. The findings reveal that both longitudinal and transverse piezoelectricity in the PMN-PT single crystals can be greatly enhanced by proper setting of ambient temperature, indicating an effective route for the design of strain-mediated tunable devices with ultralow driving voltage.     

Thermal stability and performance of optimized ZrCx diffusion barriers in ceramic coating systems for ATF applications

Surface-modified Zr alloy claddings with advanced ceramic coatings are promising materials for accident-tolerant fuel (ATF) systems to meet stringent safety regulations concerning light water reactors. The applications of ceramic coatings are, however, limited as a result of inferior thermal stability when used in conjunction with Zircaloy-4 (Zry-4) substrates. Herein, the thermal stability of sub-stoichiometric zirconium carbide barrier layers as a function of composition was studied. Integrated ceramic coatings comprising ZrC_0.55 diffusion barriers and a Cr₂AlC top layer were synthesized via a magnetron sputtering method. After rapid thermal annealing, the ZrC_0.55 barrier layer having a thickness of 0.5 μm effectively prevented the inter-diffusion between Cr₂AlC and the Zry-4 substrate, thereby ensuring retention of the structural integrity of the integrated ceramic coating system for ATF applications.     

Preparation and tribological behavior of polytetrafluoroethylene/metal mesh composites with sandwich structure

Polytetrafluoroethylene (PTFE) owns an excellent self-lubricating performance, but its wear rate is very high due to the large-scale spalling of the matrix in the friction. In this paper, A new kind of PTFE composites with sandwich structure was prepared by layer-press technology, whose middle layer is filled with metal mesh. The influence of the mesh structure and mesh density of middle metal layer on tribological properties of composites were researched in detail. The results revealled that the metal mesh located in the composites can efficiently prevent the large-scale spalling of PTFE, which induces the sample of PTFE/500# plain woven dutch metal mesh (PTFE-500#PWD) to have a lower wear rate (9 × 10⁻⁵ mm³/Nm) and COF (0.106) under the fixed experimental condition. The prepared PTFE/metal mesh composites reveal excellent anti-friction and anti-wear performance, which can be used to fabricate a new kind of self-lubricating materials.     

碳纳米管补强丁苯橡胶/聚氯乙烯共混物的研究

研究碳纳米管用量对丁苯橡胶（SBR）/聚氯乙烯（PVC）共混物性能的影响。结果表明：碳纳米管微观呈长条状聚集态,聚集体由大量碳纳米管纠缠而成,碳纳米管直径为10～35 nm;随着碳纳米管用量的增大,SBR/PVC共混物的FL,Fmax和Fmax－FL逐渐增大,t10和t90呈缩短趋势,硬度、定伸应力、拉伸强度和撕裂强度逐渐增大,拉断伸长率逐渐减小,当碳纳米管用量为10份时,SBR/PVC共混物的物理性能较优;SBR/PVC共混物的储能模量和损耗模量随着应变的增大而减小,随着碳纳米管用量的增大而增大,损耗因子随着应变的增大而增大,随着碳纳米管用量的增大而呈减小趋势。     

碳酸钠浓度对X70钢腐蚀行为的影响

用塔菲尔极化曲线法、阳极动电位扫描法和交流阻抗法研究了X70钢在不同浓度Na_2CO_3溶液中的腐蚀行为,结果表明,随着Na_2CO_3浓度的增加,腐蚀速率先减小后增大,自腐蚀电位先正移后负移。当Na_2CO_3浓度较低时,交流阻抗谱表现为一个容抗弧和一个感抗弧。而当Na_2CO_3浓度增大到0．1mo1/L时,X70钢开始钝化,交流阻抗谱表现为一个容抗弧。当浓度继续增大时,钝化性能下降。     

液相渗Si提高TiAl基合金的高温抗氧化性

使用液相Al—Si合金对TiAl基合金进行表面渗Si处理，可明显增强TiAl基合金的高温抗氧化性．经1273K，100h的恒温氧化后，不同的表面涂层使合金在40—100h之间的氧化速率降低了2个数量级，恒温氧化100h后的最终氧化皮脱落量也减少3个数量级．液相渗Si使TiAl基合金表面高温抗氧化性能得到大幅度改善，其根本原因是Si与TiAl中的元素Ti结合，降低了Ti的活度，相对增强了涂层中元素Al的活度，而且涂层中Al的绝对含量也得到明显提高，这些均抑制了高温氧化过程中TiO2的生成，涂层最外层形成了致密的Al2O3氧化膜．