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排序方式: 共有186条查询结果,搜索用时 328 毫秒
81.
LiLing Wang Alireza Azizi Roya Momen Tianlv Xu Steven R. Kirk Michael Filatov Samantha Jenkins 《International journal of quantum chemistry》2020,120(1):e26062
Next-generation quantum theory of atoms in molecules was applied to analyze, along an entire bond path, intramolecular interactions known to influence the photoisomerization dynamics of a light-driven rotary molecular motor. The 3D bond-path framework set B0,1 constructed from the least and most preferred directions of electronic motion, provided new insights into the bonding leading to different S1 state lifetimes including the first quantification of covalent character of a closed-shell intramolecular bond path. We undertook the first use of the stress tensor trajectory Tσ(s) analysis on selected nonadiabatic molecular dynamics trajectories with the electron densities obtained using the ensemble density functional theory method. The stress tensor Tσ(s) analysis was found to be well suited to follow the dynamics trajectories that included the S0 and S1 electronic states through the conical intersection and also provided to a new measure to assess the degree of purity of the axial bond rotation for the design of rotary molecular motors. 相似文献
82.
83.
84.
根据微小型球形飞行器的结构特点和工作原理,设计了一套基于ARM Cortex-M3 STM32F103RBT6微控制器的飞行控制系统,进行了主要模块的功能设计与性能分析,给出了研究结论与选型依据,还设计并完成了姿态传感器两轴转台实验和飞行器室内飞行试验。测试结果表明,该控制系统的姿态传感器姿态测量精度高,能够为飞行控制提供姿态参考信息;飞行器能够圆满实现空中悬停、低空机动等飞行动作,且空中飞行姿态稳定、实时、可靠。该飞行控制系统功能可靠、性能稳定,能够较好地满足微小型球形飞行器的飞行控制要求,具有一定的实用性与扩展性。 相似文献
85.
The free-vibration behavior of symmetrically laminated fiber-reinforced composite beams with different boundary conditions
is examined. The effects of shear deformation and rotary inertia, separately and/or in combination, on the free-vibration
properties of the beams are investigated. The finite-difference method is used to solve the partial differential equations
describing the free-vibration motion in each case. The effect of shear deformation on the natural frequencies is considerable,
especially for higher frequencies, whereas the influence of rotary inertia is less significant. The study includes comparisons
with results available in the literature. In addition, the impact of such factors as the span/depth ratio, fiber orientation,
stacking sequence, and material type on free vibrations of the composite beams is investigated.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 3, pp. 331–346, May–June, 2006. 相似文献
86.
采用离散单元数学模型对一充装量为50%的水平薄滚筒内S形二元颗粒体系的分离模式进行了数值模拟试验,研究了不同碰撞阻尼参数下的分离过程,分析了阻尼对分离过程及分离模式的影响.模拟结果表明阻尼对滚筒内颗粒的分离过程及分离模式影响很大,在S形二元颗粒体系水平薄滚筒内,阻尼可控制渗透和离析的协同作用以及自由表面层的流动形式,最终影响分离模式的形成;当阻尼太大时分离模式只能形成月亮模式,阻尼太小时可形成不明显的花瓣模式,只有当阻尼在适当的范围内,自由表面流动层形成雪崩流型式时,分离模式才会呈现规则的花瓣模式,试验结
关键词:
滚筒
模式形成
径向分离
离散单元法 相似文献
87.
Aainaa Izyan Nafsun Fabian Herz Eckehard Specht Viktor Scherer Siegmar Wirtz 《实验传热》2013,26(4):520-535
The influence of material properties on the contact heat transfer coefficient between the covered wall surface and the solid bed was investigated. The contact heat transfer coefficients were calculated from the measured radial and circumferential temperature profiles. Experiments were carried out with six different materials, including steel spheres, animal powder, cement clinker, quartz sand, glass beads, and expanded clay. The rotational speeds were varied from 1 to 6 rpm to evaluate the influence of rotational speed on the contact heat transfer coefficient. The measured contact heat transfer coefficients were compared with four models from the literature. 相似文献
88.
We derive general expressions for the sum rules of the eigenvalues of drums of arbitrary shape and arbitrary density, obeying different boundary conditions. The formulas that we present are a generalization of the analogous formulas for one dimensional inhomogeneous systems that we have obtained in a previous paper. We also discuss the extension of these formulas to higher dimensions. We show that in the special case of a density depending only on one variable the sum rules of any integer order can be expressed in terms of a single series. As an application of our result we derive exact sum rules for the homogeneous circular annulus with different boundary conditions, for a homogeneous circular sector and for a radially inhomogeneous circular annulus with Dirichlet boundary conditions. 相似文献
89.
为了提高关键链多项目缓冲管理的效率,首次提出了一种基于多项目双重风险共担的鼓缓冲设置方法。新方法从系统角度分析了多项目不同层级的风险共担作用,以同时落在在子项目关键链和多项目系统关键链上的系统关键活动工期占比为切入点对缓冲进行分层管理,抽取部分项目缓冲集中到系统层面,同时综合考虑风险独立因子以及鼓活动有效产出影响指数对鼓缓冲进行了定量设置。仿真结果表明,本文方法在多项目按时完工率、项目缓冲平均消耗率、系统关键链上鼓活动平均延误百分比、多项目系统总工期和成本这几个绩效方面的表现更优,提高了多项目系统的风险应对能力。 相似文献
90.
以制造企业H公司作为研究对象,以约束理论(简称TOC)为基础,运用TOC五步骤法、"鼓缓冲绳"生产计划与控制系统(简称DBR)等方法,对H公司生产系统系进行改进.通过改变排产方式、提升瓶颈工序产能等活动,使H公司在生产效率有了明显的改善.各项数据结果表明,H公司借助TOC实施的生产系统改善是有效而且成功的,验证了TOC约束理论在制造企业的有效性. 相似文献