摘要：To quantitatively identify the maintenance demand for each highway segments in the pavement maintenance scheme design,a mathematical model of uniform segment division was established and an approach of applying cluster analysis theory to the uniform segment division and evaluation of pavement maintenance demand was *** actual maintenance project of a highway carried out in Guangdong province was cited as an example to demonstrate the validity of the proposed *** is proved that the cluster analysis can eliminate human factors in classification without being constrained by the quantities of samples,considering multiple pavement distress indexes and the continuity of *** it is evident that cluster analysis is an efficient analytical tool in uniform segment division and evaluation of maintenance demand.

摘要：A new contact model of traveling wave ultrasonic motor (TWUSM) with a visco-elastic stator frictional layer was presented. In this model, the initial boundaries were revised, and the rotor revolution speed could be calculated iteratively. This model was compared with compliant slider and rigid stator model. The results of motor characteristics simulations showed that the motors based on this model would gain bigger stall torque. Then the friction and wear characteristics of two models were analyzed. The motors based on this model had lower coefficient of friction and better wear resistance.

摘要：详细说明了二维的不稳定的数字模拟被执行调查一块高力量的合成喷气致动器流动地和它的设计特征。同时，与致动器混合同轴的喷气的控制机理也被学习。第一，刺激频率(旋转速度) ，活塞排水量和它的出口槽宽度在控制能力和致动器的控制效率上有效果。与不变的模型和担心的参数一起，当旋转速度增加，致动器变得更合乎需要。在致动器的平均速度和最大的速度退出活塞排水量扩大或出口槽宽度减少的节增加。但是致动器总是不与更狭窄的出口展出好性能。第二，合成喷气也让“推”在同轴的喷气上完成，它导致涡度的变化和混合流动地的温度分发。最后，合成喷气致动器的雇用能完成显著地混合改进。

摘要：Crimping is widely adopted in the production of large-diameter submerged-arc welding pipes. Traditionally, designers obtain the technical parameters for crimping from experience or by trial and error through experiments and the finite element(FE) method. However, it is difficult to achieve ideal crimping quality by these approaches. To resolve this issue, crimping parameter design was investigated by multi-objective optimization. Crimping was simulated using the FE code ABAQUS and the FE model was validated experimentally. A welding pipe made of X80 high-strength pipeline steel was considered as a target object and the optimization problem for its crimping was formulated as a mathematical model and crimping was optimized. A response surface method based on the radial basis function was used to construct a surrogate model; the genetic algorithm NSGA-II was adopted to search for Pareto solutions; grey relational analysis was used to determine the most satisfactory solution from the Pareto solutions. The obtained optimal design of parameters shows good agreement with the initial design and remarkably improves the crimping quality. Thus, the results provide an effective approach for improving crimping quality and reducing design times.

摘要：钾离子电池在大规模储能方面具有广阔的前景.然而,缺乏合适的正极材料限制了其实际应用.此外,为钾离子电池合理设计先进的正极材料仍然面临挑战.本工作中,通过密度泛函理论计算,我们发现层状过渡金属氧化物中Fe-O键稳定性高于Co-O键.此外,Fe基层状氧化物中的钾离子迁移具有明显低于Co基氧化物的活化能垒.基于这一理论预测,我们成功合成了一种低成本的K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)正极,该正极显示出优异的结构稳定性和储钾性能,包括较长的循环寿命和高倍率性能.此外,所设计的K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)正极具有良好的全电池性能,放电容量约为75 mA h g^(-1),100次循环后容量保持率约为80%.在层状氧化物正极中,Fe比高成本Co具有更好的结构稳定性和钾离子扩散能力,这一发现为低成本和高性能钾离子电池层状正极的设计提供了新的思路.这项工作突出了以理论为指导的实验在筛选有前景的电池材料方面的可行性.

摘要：本文在海马体的启发下设计了一种与光照时长相关的记忆器件.与常规的持续性正/负电导不同,基于类网状二硫化钼沟道层的记忆器件表现出随光照时长逐渐降低的正光电导.由于光照下缺陷诱导的捕获陷阱会在阳极附近形成耗尽层,导致局部电场畸变,从而使载流子分离效率净降低,该器件表现出随光照时长先增加后降低的光响应,而且再次光激发的响应电流低于前一次光激发的电流,即再次光激发读出电流与前一次光照时长相关.因此在405 nm激光光照下该器件可用于光照时长编码和模拟压力诱导下的完整记忆行为包括记忆编码、存储和再检索.此外,通过再引入450 nm激光可以实现光照时长编码的加密与解密,同时也可以进一步模拟压力引发的相应激素对记忆的影响.

摘要：It is presented in this paper that the new design and its analysis of finite difference domaindecomposition algorithms for the two-dimensional heat equation,and the numerical results have shownthe stability and accuracy of the algorithms,where Saul'yev asymmetric schemes have been used atthe interface *** Algorithm Ⅱ in this paper has further extended those developed by Dawsonand the others,Zhang and Shen.

摘要：Nanogenerators were first demonstrated by deflecting aligned ZnO nanowires using a conductive atomic force microscopy(AFM)*** output of a nanogenerator is affected by three parameters:tip normal force,tip scanning speed,and tip *** this work,systematic experimental studies have been carried out to examine the combined effects of these three parameters on the output,using statistical design of experiments.A statistical model has been built to analyze the data and predict the optimal parameter *** an AFM tip of cone angle 70°coated with Pt,and ZnO nanowires with a diameter of 50 nm and lengths of 600 nm to 1μm,the optimized parameters for the nanogenerator were found to be a normal force of 137 nN and scanning speed of 40μm/s,rather than the conventional settings of 120 nN for the normal force and 30μm/s for the scanning speed.A nanogenerator with the optimized settings has three times the average output voltage of one with the conventional settings.

摘要：探索具有深紫外相位匹配能力的新型非线性光学材料是当前研究热点.本文从硼氧阴离子框架出发,发现由π共轭BO_(3)基团组成一维(BO_(2))∞链的电子离域导致了极化特性增强,可实现非线性光学性能的优化.据此,本文预测了以(BO_(2))∞链为阴离子框架的CaBO_(2)F体系.重点研究了三种能量最低的结构CaBO_(2)F-Ⅰ,CaBO_(2)F-Ⅱ和CaBO_(2)F-Ⅲ,设计了热力学上可进行的反应路径.第一原理计算表明,CaBO_(2)F-Ⅰ,CaBO_(2)-F-Ⅱ和CaBO_(2)F-Ⅲ具有较宽的带隙,合适的双折射(0.076–0.108@1064 nm)和较大的倍频系数(2.1–2.7×KDP).其中,计算得到CaBO_(2)F-Ⅰ的最短相位匹配波长在约为195 nm(基于HSE06带隙修正剪刀算符),证明了含有定向电子离域的(BO_(2))∞链是深紫外非线性光学材料的潜在阴离子框架.本文通过将机理研究与验证性的结构预测相结合实现了自上而下设计深紫外非线性光学结构模板,该研究为探索新型非线性光学材料提供了新的策略.

摘要：Cobalt nanoparticles(NPs)catalysts are extensively used in heterogeneous catalytic reactions,and the addition of alkali metal promoters is a common method to modulate the catalytic performance because the catalyst's surface structures and morphologies are sensitive to the addition of ***,the underlying modulation trend remains ***,the adsorption of alkali metal promoters(Na and K)on the surfaces of face-centered-cubic(FCC)and hexagonal-closest packed(HCP)polymorphous cobalt was systematically investigated using density functional ***,the effect of alkali promoters on surface energies and nanoparticle morphologies was revealed on the basis of Wulff *** FCC-Co,the exposed area of the(111)facet in the nanoparticle increases with the adsorption coverage of alkali metal ***,the(311),(110),and(100)facets would disappear under the higher adsorption coverage of alkali *** HCPCo,the Wulff morphology is dominated by the(0001)and(1011)facets and is independent of the alkali metal adsorption *** work provides insights into morphology modulation by alkali metal promoters for the rational design and synthesis of cobalt-based nanomaterials with desired facets and morphologies.