摘要：A quasistatic homogenized projection is made to characterize the effective cohesive zone behavior for rough-surface adhesion. In the context of the homogenized projection, the traction versus separation relation for the homogenized cohesive zone （HCZ） of a rough interface can be highly oscillatory due to instabilities during microscopic adhesion and decohesion processes. The instabilities are found to occur not only individually but also collectively among the adhesive micro-asperity contacts, leading to extensive energy dissipation. Based on the behaviors of the HCZ relations, a framework for describing instability-induced energy dissipation in rough-surface adhesion is proposed to elucidate the effect of roughness on apparent interface adhesion. Two non- dimensional parameters, α related to roughness morphology and n related to flaw distribution, are identified to be most crucial for controlling the energy dissipation. For an interface with a shallow roughness and a strong intrinsic adhesive strength, the interface adhesion can be stronger if we make it rougher （reducing α） or lower its flaw density （increasing n）. The HCZ projection method can be potentially extended and employed to bridge the apparent adhesion from intrinsic adhesion properties for engineering surfaces with multi-scale shallow roughness.

摘要：The historiographical mandate of the term antiquarianism has increased dramatically in recent *** its original European context,the term referred to the investigations of the things undertaken by antiquaries,those who pursued remote knowledge by exploring the connections between material traces and historical texts.

摘要：In this paper I will discuss certain elements of Eisenstein＇s later film theory and general aesthetic of the 1930s and 1940s. I will select a few elements in his theoretical interests that seem to be Marxist, with comments on one kind of imagination of the utopian. I will ask about some peculiarities in his very distinctive film and aesthetic theories, which could be read as interventions in official Soviet aesthetic theory, but are not only that.

摘要：Beveloid gears,also known as conical gears,gain more and more importance in industry practice due to their abilities for power transmission between parallel,intersected and crossed ***,this type of gearing with crossed axes has no common plane of action which results in a point contact and low tooth ***,a geometry design approach assuming line contact is developed to analyze the tooth engagement process of crossed beveloid gears with small shaft angle for marine transmission *** loaded gear tooth contact behavior is simulated by applying a quasi-static analysis to study the effects of gearing parameters on mesh *** the proposed method,a series of sensitivity analyses to examine the effects of critical gearing parameters such as shaft angle,cone angle,helix angle and profile-shift coefficient on the theoretical gear mesh is *** parametric analysis of pitch cone design shows that the dominant design parameters represented by the angle between the first principle directions（FPD） and normal angular factor are more sensitive to the shaft and cone angles than they are to the helix *** theoretical contact path is highly sensitive to the profile-shift coefficient,which is determined from the theoretical tooth contact *** FPD angle is found to change the distribution of contact pattern,contact pressure and root stress as well as the translational transmission error and the variation of the mesh stiffness *** contact pattern is clearly different between the drive and coast sides due to different designed FPD ***,a practical experimental setup for marine transmission is performed and tooth bearing test is conducted to demonstrate the proposed design *** experimental result compared well with the *** of this study yield a better understanding of the geometry design and loaded gear mesh characteristics for crossed beveloid gears used in marine trans

摘要：Existing active magnetic bearings （AMBs） operate in the linear region of the magnetic material flux density, which limits the utilization of the bearing capacity. In order to increase the utilization of the bearing capacity and enhance the performance of the AMB system, this paper develops a method for designing high performance linear feedback laws. The resulting feedback laws allow the AMB to operate in its nonlinear region and hence improve the closed-loop performance. We first establish an approximate nonlinear AMB current force response model, and place this nonlinear curve inside a sector formed by two piecewise linear lines. Based on the linear line segments in these two piecewise linear lines, we determine the maximum disturbance that can be tolerated by solving an optimization problem with linear matrix inequality （LMI） constraints. For a given level of disturbance under the maximum tolerable disturbance, we formulate and solve the problem of designing the linear feedback that achieves the highest level of disturbance rejection as another LMI problem. Both g2 disturbances and g disturbances are considered. Finally, we illustrate our design by both simulation and experimental results.

摘要：随着光通信、光信息处理技术等的快速发展,非线性光学材料越来越受到学术界与工业的关注。与无机非线性光学材料相比,有机非线性光学材料具有响应时间短、易于加工和高非线性系数等优点。其中, 4-(4-二甲氨基苯乙烯基)甲基吡啶对甲苯磺酸盐(DAST)是人工设计的一种具有非中心对称性和较强极化率的有机非线性材料。大量理论和实验结果表明, DAST具有高二阶光学非线性系数、高电光系数、大双折射率差和低介电常数等特性,能够产生更快、更强的光学非线性响应,还具有优异的太赫兹波发射及吸收性能,是目前综合性能最优、应用最广、最具研究价值的非线性有机材料。近年光谱研究显示, DAST还表现出各向异性的太赫兹光谱特性。文章系统地总结了DAST晶体在太赫兹波发射、二次谐波产生、电光探测和电光调制等众多领域的国内外研究成果,还概括了我们团队近期在DAST基薄膜、太赫兹光谱、光电特性、超材料等新领域的研究进展。此外,还提出将准相位匹配法用于DAST晶体研究、利用电场或自组装膜诱导生长DAST晶体等新思路。对DAST成果的总结和梳理,将促进非线性DAST有机材料在电光调制器、频率转换器、 THz探测器等重要领域的应用与理论研究,使其能够更加广泛地应用在光通信、光信息处理、军事技术等重要领域。

摘要：加权本质无振荡(weighted essentially non-oscillatory, WENO)格式是用于求解双曲守恒律方程和对流占优问题的一类高精度数值方法. WENO格式设计的思想是在解的光滑区域中获得高阶数值精度,而在解的间断附近保持本质无振荡的性质.以这种思想设计的有限差分和有限体积高精度WENO格式在计算流体力学等领域中得到了广泛应用.本文首先回顾WENO格式设计的基本思想和性质,简要介绍近年来WENO格式研究方面的一些进展,并阐述US-WENO (unequal-sized WENO)格式、MR-WENO (multi-resolution WENO)格式和HWENO (Hermite WENO)格式的构造策略.此外,本文还介绍高精度WENO格式在结构网格和非结构网格上的一些进展,展望这些高精度格式在多个领域中的应用以及未来的发展趋势.

摘要：爆炸问题的高精度数值模拟在武器弹药设计及毁伤评估、工业重大爆炸灾害等国防和民用问题中具有重要的理论价值和应用前景.本文对近十几年来爆炸力学高精度计算的研究作了回顾与评述,结合作者近年来的研究工作,着重总结了高精度数值模拟保正性、高精度边界条件、自适应网格技术和多物质界面处理等方面的研究进展.推广并发展了WENO格式和RKDG格式,构造了守恒型高精度保正计算格式,在复杂爆轰波问题的数值模拟中很好地解决了出现负密度和负压强的问题,清晰地捕捉了爆轰波阵面结构和流动特征;提出了基于笛卡尔网格的高精度Inverse Lax-Wendroff复杂边界处理方法,该方法通过Inverse Lax-Wendroff获得一阶的法向偏导数值,所有其他的高阶法向偏导数值由五阶WENO类型的外插方法获得,实现了含复杂边界爆轰问题的高精度数值模拟,并具有较好的稳定性和鲁棒性;将后验误差估计方法应用于求解Euler方程中,采用网格的后验误差作为细分的判据,网格细分时在空间上利用高阶WENO插值,时间上采用Hermite插值.对于不需要细分的网格,本文采用点对点的直接赋值方法进行合并;发展了多介质界面处理的Local Level Set方法,对计算域内速度场进行修正,有效避免了速度场间断在求解界面位置时引起的误差;将GFM(ghost fluid method)和RGFM(real ghost fluid method)界面处理方法相结合,避免了GFM方法处理物质界面强间断时引入的虚假物理解,克服了RGFM方法处理弱间断时,重复求解Riemann问题引起的计算资源浪费.最后,对爆炸力学高精度计算的发展前沿进行了展望.

摘要：实施科学是一门研究方法的学科,旨在实践和政策中促进循证干预措施的系统实施,进而改善健康。尽管实施研究需要高质量的证据,但实施策略的随机试验往往存在较为严重的局限性。这些局限性包括存在偏倚风险、缺乏理论运用、缺乏描述实施策略标准术语、局限于实施结局以及不充分报告。本文旨在对实施策略随机试验的设计、实施和报告提供指导,以提升循证实施科学。由研究人员、卫生政策制订者和实践者组成的国际小组整合了构建随机试验方法的重要文献和实施科学的最新进展。本文为实施策略随机试验的主要内容提供指导,包括试验目的阐明、试验中人员招募和保留策略、随机设计的选择、实施科学理论和框架的使用、测量(结局指标)、样本量计算、伦理审查和试验报告。本文也关注了实施试验中需要特别重视或调整的主题。为了推进实施策略随机试验的严格开展和报告,我们建议将本指南作为研究人员、卫生保健和公共卫生政策制订者或实践者、研究资助者和期刊编辑的参考资料。

摘要：Optical control of exotic properties in strongly correlated electron materials is very attractive owing to their potential applications in optical and electronic ***,we demonstrate a vertical heterojunction made of a correlated electron oxide thin film VO_(2) and a conductive 0.05 wt% Nb-doped TiO_(2) single crystal,whose metal-insulator transition(MIT)across the nanoscale heterointerface can be efficiently modulated by visible light *** magnitude of the MIT decreases from ~350 in the dark state to ~7 in the illuminated state,obeying a power law with respect to the light power *** junction resistance is switched in a reversible and synchronous manner by turning light on and *** optical tunability of it is also exponentially proportional to the light power density,and a 320-fold on/off ratio is achieved with an irradiance of 65.6 mW cm^(-2) below the MIT *** the VO_(2) thin film is metallic above the MIT temperature,the optical tunability is remarkably weakened,with a one-fold change remaining under light *** results are co-attributed to a net reduction(~15 meV)in the apparent barrier height and the photocarrier-injection-induced metallization of the VO_(2) heterointerface through a photovoltaic effect,which is induced by deep defect level transition upon the visible light irradiance at low ***,the optical tunability is minimal,resulting from the quite weak modulation of the already metallic band structure in the Schottky-type junction above the MIT *** work enables a remotely optical scheme to manipulate the MIT,implying potential uncooled photodetection and photoswitch applications.