摘要：A novel robust controller is proposed in this study to realize the precise motion control of a cell puncture mechanism(CPM)driven by piezoelectric ceramics(PEAs).The entire dynamic model of CPM is constructed based on the Bouc–Wen model,and the nonlinear part of the dynamic model is optimized locally to facilitate the construction of a robust controller.A model-based,nonlinear robust controller is constructed using time-delay estimation(TDE)and fractional-order nonsingular terminal sliding mode(FONTSM).The proposed controller does not require prior knowledge of unknown disturbances due to its real-time online estimation and compensation of unknown terms by using the TDE *** controller also has finite-time convergence and high-precision trajectory tracking capabilities due to FONTSM manifold and fast terminal sliding mode-type reaching *** stability of the closed-loop system is proved by Lyapunov stability *** simulation and hardware-in-loop simulation experiments of CPM verify that the proposed controller outperforms traditional terminal sliding mode controllers,such as the integer-order or model-free *** proposed controller can also continuously output without chattering and has high control *** embryo is used as a verification target to complete the cell puncture *** the engineering application perspective,the proposed control strategy can be effectively applied in a PEA-driven CPM.

摘要：Parallel mechanisms（PMs） have been used as skeletons or end-effectors in various advanced manufacturing equipment. Compared with their serial counterparts, PMs offer high rigidity, good dynamic response, and large payload capability.

摘要：借助Walsh矩阵严格正交性,通过类Walsh矩阵构造和随机列重排生成多相码严格正交性空间域,利用遗传算法从中选取低相关旁瓣量信号组.该方法保证了设计的信号间严格正交性,降低了遗传算法搜索空间.遗传算法代价函数选取为自相关峰值旁瓣量、互相关峰值量以及"和信号"(所有发射信号空间叠加之和)相关峰值旁瓣量之和,"和信号"相关输出为实际信号处理的综合输出,其旁瓣量的高低直接影响雷达对目标的检测性能.仿真结果验证了该方法在保证低自相关旁瓣量和低互相关量的同时,能够设计出信号间符合严格正交性和低综合输出旁瓣量的信号组.

摘要：In this paper, the topological pressure is preserved under some semi conjugates, and a formula of computing topological pressure by use of periodic points for positively expansive continuous map with specification is given.

摘要：In the classical multiprocessor scheduling problems, it is assumed that the problems are considered in off\|line or on\|line environment. But in practice, problems are often not really off\|line or on\|line but somehow in between. This means that, with respect to the on\|line problem, some further information about the tasks is available, which allows the improvement of the performance of the best possible algorithms. Problems of this class are called semi on\|line ones. The authors studied two semi on\|line multiprocessor scheduling problems, in which, the total processing time of all tasks is known in advance, or all processing times lie in a given interval. They proposed approximation algorithms for minimizing the makespan and analyzed their performance guarantee. The algorithms improve the known results for 3 or more processor cases in the literature.

摘要：For the ever-growing demand of advanced lithium-ion batteries, it is highly desirable to grow self-supported micro-/nanostructured arrays on metal substrates as electrodes directly. The in-situ growth of electrode materials on the conducting substrates greatly simplifies the electrode fabrication process without using any binders or conductive additives. Moreover, the well-ordered arrays closely connected to the current collectors can provide direct electron transport pathways and enhanced accommodation of strains arisen from lithium ion lithiation/delithiation. This article summarizes our recent work on design and construction of lithium-ion battery electrodes on metal substrates. An aqueous solution-based process and a microemulsion-mediated process have been respectively presented to control the kinetic and thermodynamic processes for the micro-/nanostructured array growth on metal substrates, with particular attention to CuO nanorod arrays and microcog arrays successfully prepared on Cu foil substrates. They can be directly used as binder-free electrodes to build advanced lithium-ion batteries with high energy, high safety and high stability.

摘要：Owing to the tremendous advantages and unique well-defined nanoscale structure,polyhedral oligomeric silsesquioxanes(POSS)have received considerable interest in the design of novel organic-inorganic hybrid nanomaterials with all manner of prominent capabilities,which is rec-ognized as a new generation of promising materials for advanced applications of material sci-ence,engineering science and biomedical *** from the recent progress in combi-nation of controlled/living polymerization and emerging click chemistry,POSS-based hybrid ma-terials with ingenious design,versatile topological structure and sophisticated multifunctionality have been successfully fabricated and developed into abundant well-defined hybrid nanostruc-tures with desired physicochemical ***-made amphiphilic molecular design and nanosized hybrid architecture provide opportunities for the self-assembly of POSS-based hybrid materials with unique hierarchical morphologies in selective *** the in-depth understanding of structure-properties relationship,POSS-based hybrid materials can achieve the modulation of precise control of self-assembling process and multi-purpose applications with improved material *** this review,we summarize the recent advances of POSS-based hybrid materials in molecular design,self-assembly behavior in solutions and poten-tial biomedical applications with main concerns on drug delivery,gene therapy,bioimaging and tissue engineering ***,future directions and remaining challenges for further advance-ment of POSS-based hybrid materials are proposed and discussed.

摘要：疲劳是机械结构最普遍的失效模式之一。自1854年第一次提出"Fatigue"(疲劳)概念以来,相关研究已有160余年的历程,逐步形成了以疲劳研究为基础的机械结构强度理论与技术,推动机械结构从经验设计走向安全设计。本文回顾了结构疲劳研究的缘起及发展历程,总结了典型失效案例对疲劳基础研究的促进作用和里程碑式成果,基于文献统计分析了最近50年本领域的代表性进展、研究热点与发展趋势。研究表明,尽管经历了百余年的不懈努力,疲劳极限、损伤易感基因、裂尖主控机制、蠕变-疲劳交互和安全系数的物理本质等仍是困扰人们的难题。数据科学和大数据技术的兴起,为突破数据驱动的疲劳寿命预测方法、诠释疲劳损伤物理机制和建立极端条件下的高端装备疲劳可靠性设计技术提供了新的途径。

摘要：Introduction and research overview Recently,increasing need for organ transplantation and lack of donated organs have led to the rapid development of new technologies for artificial organ *** the era of burgeoning breakthroughs around 3D bioprinting technologies,the personalization of organs and medicine is an ongoing nice vision[1–5].As one of the leading laboratories in the interdisciplinary field of materials,manufacturing and bioengineering,the Biofabrication(3D Bioprinting)Research Laboratory at Sichuan University has been engaging in the research on customized regenerativemedicine since 2012.

摘要：Time-resolved MeV ultra-fast electron diffraction (UED) is a powerful tool for structure dynamics studies. In this paper, we present a design of a MeV UED facility based on a photocathode RF gun at Tsinghua University. Electron beam qualities are optimized with numerical simulations, indicating that resolutions of 250 fs and 0.01 , and bunch charge exceeding 105 electrons are expected with technically achievable machine parameters. Status of experiment preparation is also presented.