摘要：为了保障岩溶突水隧道施工和运营安全,基于弹性梁模型,应用突变理论建立岩溶突水顶板在动力扰动下失稳的双尖点突变模型;综合考虑围岩性质、静水压力、动力扰动等因素,分析岩溶突水隧道顶板的失稳机制和破坏条件,建立其失稳突变的判别方程,并采用Matlab软件编程,求解顶板的最小安全厚度;同时,为了避免当静水压力过大时,突变理论公式的不合理性,单独计算仅在静水压力的情况下的最小安全厚度,并取两者计算值中的更大值。结果表明:隔水岩体是否保持稳定是由岩体内外因素共同决定的;岩体跨度越长,岩体最小安全厚度越大;岩体弹性模量越大,岩体最小安全厚度越小。在振动频率一定时,爆破荷载越大,岩体最小安全厚度越大;在爆破荷载的大小一定时,爆破振动的频率越大,岩体最小安全厚度越小;静水压力越大,岩体最小安全厚度越大。该岩溶突水隧道顶板安全厚度计算方法具有可行性与较高的准确性。

摘要：探究铲钻倒棱几何参数对钻削温度的影响,为铲钻倒棱刃口的参数选择提供参考。通过有限元仿真模拟铲钻钻削过程的温度场得到倒棱角度和倒棱宽度对钻削温度的影响规律。为了验证仿真模拟结果,使用红外热像仪测量钻削过程中切屑温度,并通过光学显微镜观察切屑表面形貌,分析钻削温度随着倒棱刃口几何参数变化的原因。研究结果表明,最高钻削温度区域出现在倒棱面及其附近的前刀面,钻削温度随着倒棱宽度的增大呈现先增大再减小的趋势。随着倒棱角度的增大,钻削温度呈先增大后减小最后再增大的趋势。在设计倒棱刃口时,倒棱宽度应该选择0.1mm<b≤0.3mm,倒棱角度选择10°<γ≤20°,这样可使铲钻刀片具有良好的散热性能。倒棱宽度和倒棱角度的增大加剧了刀—屑的摩擦,导致钻削温度升高,同时也提高了铲钻刀片的散热能力。

摘要：研究新兰伯恩磨耗设备试验参数(载荷、试样速度、滑移率和滑石粉落粉速度)与胶料磨耗状态的关系,通过观察胶料表面磨纹在不同磨耗参数下的情况,分析橡胶的磨耗机理。结果表明:载荷与磨耗速度具有较高的正相关性;试样速度与单位时间磨耗速度具有较高的相关性,但与单位距离磨耗速度基本无相关性;滑移率与磨耗速度的相关性较高,随着滑移率的增大,样品表面的磨纹愈发清晰,磨屑聚集情况逐渐加重;落粉速度与磨耗速度的关系相对复杂,当落粉速度小于0.3 cm^(3)·min^(-1)时,两者的相关性较低;当落粉速度为0.3~0.6 cm^(3)·min^(-1)时,磨耗速度随着落粉速度的增大而增大,此时可观察到样品表面磨屑的生长过程;当落粉速度大于0.6 cm^(3)·min^(-1)时,磨耗速度随着落粉速度的增大而迅速减小。

摘要：Fail-safe topology optimization is valuable for ensuring that optimized structures remain operable even under damaged *** selectively removing material stiffness in patches with a fixed shape,the complex phenomenon of local failure is modeled in fail-safe topology *** this work,we first conduct a comprehensive study to explore the impact of patch size,shape,and distribution on the robustness of fail-safe *** findings suggest that larger sizes and finer distribution of material patches can yield more robust fail-safe ***,a finer patch distribution can significantly increase computational costs,particularly for 3D *** keep computational efforts tractable,an efficient fail-safe topology optimization approach is established based on the framework of multi-resolution topology optimization(MTOP).Within the MTOP framework,the extended finite element method is introduced to establish a decoupling connection between the analysis mesh and the topology description *** examples demonstrate that the developed methodology is 2 times faster for 2D problems and over 25 times faster for 3D problems than traditional fail-safe topology optimization while maintaining similar levels of robustness.

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.

摘要：插花作为室内装饰之一种,是中国一个重要的传统艺术门类。中国插花传统,经历了由富丽到清雅的艺术历程。唐以前重富丽,宋代重清雅。宋人的清雅之好,确立了一种艺术范式,并直接影响到以后整个插花艺术的发展。

摘要：经典克拉尼图形(Chladni patterns,CP)是特征向量的视觉表示,在振动分析、乐器设计、粒子操纵和分离等领域中具有广泛的应用.均质结构通常会表现出高度规则化的CP,这限制它们的应用场景.因此,实现面向应用来逆向设计结构的CP是非常重要的,而这可以通过使用拓扑优化来实现CP的逆向设计.本研究提出了一种使用基于密度的拓扑优化算法来设计结构CP的方法.优化列式中,给出了描述图形的指标函数,并以最小化特征向量和目标CP之间的误差构建了优化目标.数值结果表明,所提出的方法可以为指定的单阶或多阶CP生成新颖的材料分布.这表明了本文所提出的方法能够实现CP的精确定制设计,进一步为面向应用的需求提供了更多选择.

摘要：为铲钻倒棱刃口的设计、开发和应用提供参考,建立考虑倒棱刃口几何参数的铲钻钻削力模型。基于正交切削理论,引入材料因刃口挤压产生形变的几何系数,建立倒棱刃口铲钻相对于主切削刃方向的切向力和法向力模型,根据铲钻切削刃的实际加工计算出铲钻的轴向力和扭矩。考虑分屑槽对铲钻钻削力的影响,使用变形系数代替剪切角和摩擦系数。采用有限元模拟铲钻钻削过程,进行铲钻的钻削力测试实验,得到铲钻的轴向力、扭矩,并将倒棱刃口铲钻的钻削力与锋利刃口的钻削力进行对比。研究结果表明:建立的钻削力理论公式适用于计算倒棱刃口铲钻轴向力和扭矩的计算,得到了倒棱刃口宽度和角度对铲钻钻削力的影响规律;设计铲钻刀具倒棱刃口时,铲钻刃口的倒棱宽度选择0.1 mm,倒棱角度选择10°或30°可以获得较低的钻削力。

摘要：The covalent attachment of protein-resistant polymers to therapeutic proteins is a widely used method for extending their in vivo half-lives; however, the effect of molecular weight of polymer on the in vitro and in vivo functions of protein-polymer conjugates has not been well elucidated. Herein we report the effect of molecular weight of poly（oligo（ethylene glycol） methyl ether methacrylate） （POEGMA） on the in vitro and in vivo properties of C-termi- nal interferon-alpha （IFN）-POEGMA conjugates. Increasing the molecular weight of POEGMA decreased the in vitro activity of IFN-ct but increased its thermal stability and in vivo pharmacokinetics. Intriguingly, the in vivo antitumor efficacy of IFN-a was increased by increasing the POEGMA molecular weight from ca. 20 to 60 kDa, but was not further increased by increasing the molecular weight of POEGMA from ca. 60 to 100 kDa due to the neutralization of the improved pharmacokinetics and the reduced in vitro activity. This finding offers a new viewpoint on the molecular size rationale for designing next-generation protein-polymer conjugates, which may benefit patients by reducing admin- istration frequency and adverse reactions, and improving therapeutic efficacy.

摘要：3K行星齿轮减速器的啮合齿轮副存在齿侧间隙,使得传动链中引入了传动间隙,导致传动精度降低以及换向冲击。为消除3K行星齿轮减速器的传动间隙,利用3K行星齿轮传动中行星架不参与力矩传递的特性,提出了一种柔性行星架以消除传动间隙,并通过仿真分析验证了所提消隙机构的有效性。通过配齿及效率优化实现了高效的正向和反向传动。研制样机并进行了传动精度、滞回特性、正弦响应误差、正向传动效率、反向传动效率以及反向启动扭矩测试,结果验证了所提柔性行星架对消除3K行星齿轮减速器传动间隙、提高传动精度和传动效率以及提高反向传动性能的有效性。