摘要：Chiral cyclic amino alcohols with contiguous stereocenters are key building blocks in the synthesis of bioactive molecules and *** cascade biocatalysis represents an attractive method for the synthesis of chiral molecules bearing multiple stereocenters from readily available *** we reported an artificial cascade biocatalysis comprising an epoxide hydrolase,an alcohol dehydrogenase,and a reductive aminase or an amine *** can be utilized to access all four stereoisomers of 2-aminocyclohexanol with two contiguous stereocenters in high yields(up to 95%)and excellent stereoselectivity(up to 98%de)starting from readily available cyclohexene oxide without isolation of the ***,the biocatalytic cascade has been successfully extended to the production of structurally diverse 2-(alkylamino)cyclohexanols by replacing ammonia with different organic amines.

摘要：为高效控制汽车前围板振动噪声,弥补传统材料抑制低频振动性能的不足及易燃、环保性能低的缺陷,设计一种基于Kagome点阵的局域共振型夹芯超材料,建立单胞结构的有限元模型,计算并分析其能带结构、带隙产生机理和弹性波传播特性,以及关键几何参数对带隙频段的影响,利用正交实验极差分析法(Statistical Product and Service Software Automatically,SPSSAU)对关键几何参数进行优化,同时开展基于该材料的汽车前围板隔振性能的研究。研究表明,所设计的Kagome点阵夹芯超材料能够实现低频带隙;增加圆块厚度和半径会使带隙频段整体向低频方向移动,且拓宽低频带隙;减小韧带宽度会使带隙频段向低频区域移动,且使带隙宽度减小。将优化后的Kagome点阵夹芯超材料应用于汽车前围板,可明显提高其隔振性能。

摘要：A flexure hinge is a major component in designing compliant mechanisms that o ers unique possibilities in a wide range of application fields in which high positioning accuracy is required. Although various flexure hinges with di erent configurations have been successively proposed, they are often designed based on designers' experiences and inspirations. This study presents a systematic method for topological optimization of flexure hinges by using the level set method. Optimization formulations are developed by considering the functional requirements and geometrical constraints of flexure hinges. The functional requirements are first constructed by maximizing the compliance in the desired direction while minimizing the compliances in the other directions. The weighting sum method is used to construct an objective function in which a self-adjust method is used to set the weighting factors. A constraint on the symmetry of the obtained configuration is developed. Several numerical examples are presented to demonstrate the validity of the proposed method. The obtained results reveal that the design of a flexure hinge starting from the topology level can yield more choices for compliant mechanism design and obtain better designs that achieve higher performance.

摘要：This paper describes a novel model known as the shadow obstacle model to generate a realistic comer-tuming behavior in crowd simulation. The motivation for this model comes from the observation that people tend to choose a safer route rather than a shorter one when turning a comer. To calculate a safer route, an optimization method is proposed to generate the corner-turning rule that maximizes the viewing range for the agents. By combining psychological and physical forces together, a full crowd simulation framework is established to provide a more realistic crowd simulation. We demonstrate that our model produces a more realistic comer-turning behavior by comparison with real data obtained from the experiments. Finally, we per- form parameter analysis to show the believability of our model through a series of experiments.

摘要：造型艺术是一切视觉和空间艺术的集合,是不断流变的文化活体。不同文明体在不同的历史时期都有自己的造型艺术,有其独特的艺术观念与表达形式,同时也带有那个时代技术文明的印迹。面对信息全球化、万物互联、人工智能大数据与多学科交叉融合的当代社会,造型艺术不能固守传统边界,而须紧跟时代发展步伐,融入新思想、注入新技术、拓展新的艺术表现形式,方能葆有鲜活而动人的活力。

摘要：Chitin is a structural component of fungal cell walls but is absent in vertebrates,mammals,and *** synthase is thus an attractive molecular target for developing *** on the structure of its donor substrate,UDP-N-acetyl-glucosamine,as well as the modelled structure of the bacterial chitin synthase NodC,we designed a novel scaffold which was then further optimized into a series of chitin synthase *** most potent inhibitor,compound 13,exhibited high chitin synthase inhibitory activity with an IC（50） value of 64.5 μmol/L All of the inhibitors exhibited antifungal activities against the growth of agriculturally-destructive fungi,Fusarium graminearum,Botrytis *** Colletotrichum *** work presents a new scaffold which can be used for the development of novel fungicides.

摘要：中国元素中富含鲜明的中华文化传统精髓,自然成为现代广告传播中的表现点,也取得了良好的传播效果。但是由于外在的文化差异、内在的中国元素内涵科学性和对中国元素创意的运用方面存在不足,也在一定程度上阻隔了中国元素广告的传播。

摘要：Varicocele repair in adolescent remains controversial. Our aim is to identify and combine clinical trials results published thus far to ascertain the efficacy of varicocelectomy in improving testis volume and semen parameters compared with nontreatment control. A literature search was performed using Medline, Embase and Web of Science, which included results obtained from meta-analysis, randomized and nonrandomized controlled studies. The study population was adolescents with clinically palpable varicocele with or without the testicular asymmetry or abnormal semen parameters. Cases were allocated to treatment and observation groups, and testis volume or semen parameters were adopted as outcome measures. As a result, seven randomized controlled trials （RCTs） and nonrandomized controlled trials studying bilateral testis volume or semen parameters in both treatment and observation groups were identified. Using a random effect model, mean difference of testis volume between the treatment group and the observation group was 2.9 ml （95% confidence interval [CI]： 0.6, 5.2; P 〈 0.05） for the varicocele side and 1.5 ml （95% CI- 0.3, 2.7; P 〈 0.05） for the healthy side. The random effect model analysis demonstrated that the mean difference of semen concentration, total semen motility, and normal morphology between the two groups was 13.7 x 106 ml-1 （95% CI： -1.4, 28.8; P= 0.075）, 2.5% （95% CI：-3.6, 8.6; P= 0.424）, and 2.9% （95% CI： -3.0, 8.7; P= 0.336） respectively. In conclusion, although varicocelectomy significantly improved bilateral testis volume in adolescents with varicocele compared with observation cases, semen parameters did not have any statistically significant difference between two groups. Well-planned, properly conducted RCTs are needed in order to confirm the above-mentioned conclusion further and to explore whether varicocele repair in adolescents could improve subsequently spontaneous pregnancy rates.

摘要：多电平换流器中,一般采用变压器实现每个全桥模块门极驱动电路和电源之间的隔离和绝缘。该文基于超声波式非接触电能传输技术,提出电声电型非电气接触式全桥模块门极隔离电源,它主要包括发射换能器、接收换能器、亚克力棒传输介质和补偿电路。分别给出声电、电声换能器和传输介质的设计依据,介绍了换能器的等效电路,采用COMSOL软件对压电换能器进行仿真并介绍了压电换能器的最简等效电路。详细叙述了补偿电路的设计方法,包括发射侧补偿电路的设计方法和接收侧补偿电路的设计方法。搭建实验平台,验证了补偿电路的有效性,对比了超声波式非接触电能传输技术和磁感应式非接触电能传输技术的抗电磁干扰能力。实验表明,该文设计的隔离电源可以有效地为门极驱动电路供电,使全桥模块正常工作,与磁感应式门极驱动电源相比,具有抗电磁干扰强的特点,适用于电磁环境复杂的各种门极驱动场合。

摘要：针对六自由度高超声速飞行器的飞行控制问题,本文提出了基于非线性动态逆和线性反馈方法建立主控制系统,应用L1自适应控制理论设计辅助控制系统以提升控制性能的设计方案.首先,对高超音速飞行器模型的速度和姿态角控制通道建立非线性动态逆系统.在这一基础上,采用线性二次型(linear quadratic, LQ)方法设计线性反馈控制器,作为主控制系统完成指令信号的跟踪.其次,应用L1自适应控制方法设计辅助控制器,以提升控制系统在不确定性存在情况下的性能.仿真结果显示,辅助控制系统能有效提升跟踪控制的精度,提高系统的鲁棒性,并且在输入扰动、气动参数不确定性、参数变化、控制功能部分失效等情况下可取得良好的指令跟踪效果.