摘要：There exist several difficulties in the design of monolithic high-shock three-axis accelerometer, such as high g overload, transverse overload and the cross coupling in three dimensions, etc. It is necessary to optimize the sensitivity to improve the performance of the accelerometer. For the monolithic high-shock three-axis accelerometer, the complexity of the sensitivity optimization is that it should consider not only the sensitivity difference between different axes but also the elimination of cross-coupling outputs, together with the natural frequency, structural integrity and high g overload. In this paper, the optimization process for decreasing the difference of the sensitivities between different axes of a monolithic high-shock three-axis piezoresistive accelerometer with single sensing element is established. The optimization is conducted in the condition of 100000 g acceleration by two methods-the method based on the optimization module of ANSYS and the ACO (ant colony optimization) method. The comparison between un-optimized and optimized models proves the efficiency of the optimization methods. In addition, the optimization results show that the ACO method combined with the FEA (finite element analysis) is much more efficient than the method based on the optimization module of ANSYS for the structural optimization problem. And the ACO method can be widely used in the optimization problem of the sensing elements with complicated structure.

摘要：Topology optimization is a powerful design approach that is used to determine the optimal topology in order to obtain the desired functional performance. It has been widely used to improve structural performance in engineering fields such as in the aerospace and automobile industries. However, some gaps still exist between topology optimization and engineering application, which significantly hinder the application of topology optimization. One of these gaps is how to interpret topology results, especially those obtained using the density framework, into parametric computer-aided design (CAD) models that are ready for subsequent shape optimization and manufacturing. In this paper, a new method for interpreting topology optimization results into stereolithography (STL) models and parametric CAD models is proposed. First, we extract the skeleton of the topology optimization result in order to ensure shape preservation and use a filtering method to ensure characteristics preservation. After this process, the distribution of the nodes in the boundary of the topology optimization result is denser, which will benefit the subsequent curve fitting. Using the curvature and the derivative of curvature of the uniform B-spline curve, an adaptive B-spline fitting method is proposed in order to obtain a parametric CAD model with the fewest control points meeting the requirement of the fitting error. A case study is presented to provide a detailed description of the proposed method, and two more examples are shown to demonstrate the validity and versatility of the proposed method.

摘要：Surface reconstruction from unorganized data points is a challenging problem in Computer Aided Design and Geometric *** this paper,we extend the mathematical model proposed by Jüttler and Felis(***.,17(2002), pp.135-152)based on tensor product algebraic spline surfaces from fixed meshes to adaptive *** start with a tensor product algebraic B-spline surface defined on an initial mesh to fit the given data based on an optimization *** measuring the fitting errors over each cell of the mesh,we recursively insert new knots in cells over which the errors are larger than some given threshold,and construct a new algebraic spline surface to better fit the given data *** algorithm terminates when the error over each cell is less than the *** provide some examples to demonstrate our algorithm and compare it with Jüttler's *** suggest that our method is effective and is able to produce reconstruction surfaces of high quality.

摘要：满足灌水均匀度设计标准与额定流量的滴灌毛管管径优化设计是滴灌毛管水力设计的重要内容。该文以流量偏差率为灌水均匀度设计标准,提出一种简易的滴灌毛管管径水力设计方法。通过改变单向和双向滴灌毛管流量偏差率解析公式的形式,提出一个新的管径设计参数。基于能坡线法,建立参数与坡降比参数的关系,并绘制和构建相关图形和计算公式。结果表明：当流量指数分别取值为1.75、1.69和1.00时,单向毛管管径的设计参数取值分别为-1～≤2.801,-1～≤2.859和-1～≤4;双向毛管管径的设计参数取值分别为0～≤3.143,0～≤3.183和0～≤4。满足流量偏差率设计标准和灌水器额定流量时,单向毛管管径将有1或2个设计值,双向毛管管径将有1、2或多个设计值。根据参数的取值范围,以坡降比参数为设计变量,推导了均匀坡下单向和双向毛管管径的计算公式。此外,进一步简化了滴灌毛管进口工作水头的计算公式。当已知设计流量,流量偏差率设计标准,毛管管长等参数时,可以按照设计步骤直接计算滴灌毛管管径和进口工作水头,无需进行任何复杂的试算。设计案例1表明在多数地形条件下,利用该文方法设计单向毛管的结果与传统方法设计结果的相对误差不超过4%;设计案例2表明该文方法设计双向毛管的结果与其他2种常用方法设计结果的最大相对误差为4%。因此,从工程实践角度,利用该方法设计的滴灌毛管管径和进口工作水头与其他传统方法设计结果非常接近。相比于传统设计方法,该方法简便实用,可以直接应用于滴灌工程设计。该研究可为改进滴灌毛管优化设计提供理论依据。

摘要：The strict avalanche criterion(SAC)is one of the most important cryptographic criteria for substitution boxes(S-boxes)used in many symmetric encryption ***,there are few constructive methods for S-boxes fulfilling the SAC until *** this paper,to construct S-boxes satisfying the SAC directly,we generalize the concatenation techniques of Boolean functions to *** the idea of concatenating small variable S-boxes,we present a simple yet effective construction method of S-boxes satisfying the ***,a simple example on how to construct SAC S-boxes with large input variables by small variables SAC S-boxes is given.

摘要：将具有高迁移率和强分子间作用的液晶小分子引入有机光伏器件活性层中被认为是一种提升光电转换效率的有效策略.不同于常规的认识,本文展示了“弱结晶材料同样能优化活性层形貌和提升光伏器件效率”的三元有机光伏器件调控新策略.本文设计合成了两个基于苯并二呋喃给体单元的液晶小分子Z1和Z2,发现具有无序堆积特性的Z2基三元有机光伏器件展现出了更高的光电转换效率(Z2:PM6:BTP-eC9,PCE:18.12%;Z2:PM6:Y6,PCE:17.66%)和更优异的器件稳定性.而基于高度有序的Z1的三元有机光伏器件却表现出明显降低的能量转换效率.光电器件和活性层薄膜形貌的协同表征说明Z2基三元体异质结薄膜的高光电效率主要归因于其更优的电荷传输效率和更合适的相分离尺度.该研究工作展示的有机光伏器件第三组分的调控新策略对新型高效光伏器件的制备具有重要的指导意义.

摘要：The development of a high-performance cemented carbide drill bit is of great significance to the reduction of rock drilling-cost. The non-smooth features of a biological surface provide an insight into how they can obtain low friction and good wear resistance with evolving surface morphology. By analyzing the mechanism of the surface of a dung beetle for reducing soil wear and adherence, we design a cemented carbide drill bit with a bionic surface, which is expected to have superior anti-wearing and anti-sticking properties for drilling the soft coal seam. Inspired from the characteristics of the head and pronotum surface of the dung beetle, optimized non-smooth surface of the drill bit was constructed. The working performance of this innovative drill was experimentally tested. With comparative experiments under the identical drilling conditions, the wear rates, drilling times of conventional drills and bionic drills were measured. Compared with the conventional counterpart, the drill designed exhibits better performance in reducing wear and sticking drilling-breaks, therefore achieving higher levels of efficiency. The diameter of the dome and pit on the bit surface is in the range of 0.8–1.2 mm, and the bionic drill bits could get better performance with preferable drilling speeds and wear rates.

摘要：本文提出了一种考虑几何非线性的三维连续体结构显式拓扑优化方法.采用移动可变形孔洞(MMV)方法描述结构,具有设计变量少、可与CAD系统无缝集成的优点.此外,由于结构拓扑描述模型与有限元分析模型之间解耦,在有限元分析中可以直接删除孔洞区域的冗余自由度,从根本上解决有限变形拓扑优化因弱单元引起的收敛性问题,同时显著提高了有限元分析的计算效率.数值算例验证了该方法的有效性,结果表明:(1)无论单工况还是多工况载荷作用下,几何非线性对三维结构的最优拓扑构型均具有显著影响;(2)优化后的几何非线性结构可以充分利用大位移和小应变来降低结构柔顺度;(3)几何非线性拓扑优化应评估优化设计的临界失稳荷载,以保证结构服役的安全性.

摘要：Cardiovascular diseases are the leading cause of morbidity and mortality throughout the world underlining the importance of efficient treatments including disease modeling and drug discovery by cardiac tissue ***,the predictive power of these applications is currently limited by the immature state of the ***,we developed gelatin hydrogels chemically crosslinked by genipin,a biocompatible crosslinker,as cell culture *** rat cardiomyocytes appear synchronous beatingwithin 2 days after seeding on ***,we applied the electrical stimulation as a conditioning treatment to promote the maturation of cardiomyocytes cultured on the *** results show that electrical stimulation improves the organization of sarcomeres,establishment of gap junctions,calcium-handling capacity and propagation of pacing signals,thereby,increase the beating velocity of cardiomyocytes and responsiveness to external *** above system can be applied in promoting physiological function maturation of engineered cardiac tissues,exhibiting promising applications in cardiac tissue engineering and drug screening.

摘要：Lithium-sulfur(Li-S)batteries are promising next-generation high energy density batteries but their practical application is hindered by several key problems,such as the intermediate polysulfide shuttling and the electrode degradation caused by the sulfur volume *** acts as one of the most essential components to build the electrodes of Li-S batteries,playing vital roles in improving the performance and maintaining the integrity of the cathode structure during cycling,especially those with high sulfur *** date,tremendous efforts have been devoted to improving the properties of binders,in terms of the viscosity,elasticity,stability,toughness and conductivity,by optimizing the composition and structure of polymer ***,the binder modification endows them strong polysulfide trapping ability to suppress the shuttling and decreases the swelling to maintain the porous structure of *** this review,we summarize the recent progress on the binders for Li-S batteries and discuss the various routes,including the binder combination use,functionalization,in-situ polymerization and ion cross-linking,etc.,to enhance their performance in stabilizing the cathode,building the high sulfur loading electrode and improving the cyclic *** last,the design principles and the problems in further applications are also highlighted.