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Design and experimental study of a passive power-source-free stiffness-self-adjustable mechanism

Yuwang LIU, Dongqi WANG, Shangkui YANG, Jinguo LIU, Guangbo HAO

《机械工程前沿（英文）》 2021年第16卷第1期页码 32-45 doi: 10.1007/s11465-020-0604-4

摘要： Passive variable stiffness joints have unique advantages over active variable stiffness joints and are currently eliciting increased attention. Existing passive variable stiffness joints rely mainly on sensors and special control algorithms, resulting in a bandwidth-limited response speed of the joint. We propose a new passive power-source-free stiffness-self-adjustable mechanism that can be used as the elbow joint of a robot arm. The new mechanism does not require special stiffness regulating motors or sensors and can realize large-range self-adaptive adjustment of stiffness in a purely mechanical manner. The variable stiffness mechanism can automatically adjust joint stiffness in accordance with the magnitude of the payload, and this adjustment is a successful imitation of the stiffness adjustment characteristics of the human elbow. The response speed is high because sensors and control algorithms are not needed. The variable stiffness principle is explained, and the design of the variable stiffness mechanism is analyzed. A prototype is fabricated, and the associated hardware is set up to validate the analytical stiffness model and design experimentally.

关键词： variable stiffness mechanism stiffness self-regulation bionic robot modeling

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Self-generation of machining precision and its realization in lapping of super precision solid balls

ZHANG Bopeng

《机械工程前沿（英文）》 2008年第3卷第3期页码 348-353 doi: 10.1007/s11465-008-0065-7

摘要： This paper presents the principle of self-generation of machining precision by explaining its basic concept and five necessary conditions for forming a system with self-organization capability. A self-generation system is a kind of system with self-organization capability. The self-generation of machining precision for solid balls with super precision is emphatically explained. From the viewpoint of self-organization, there are three types of systems including system 1 with the self-regulation capability, 2 with the self-determination capability of goals, and 3 with the self-organization capability. Although they are all closed loop control systems, they have different constructions and functions. Necessary conditions for achieving self-generation of machining precision are given. Establishment of the system for machining solid balls with super precision is discussed. Self-generation of machining precision for solid balls with super precision on the basis of the capability of self-removal of errors is presented. Self-generation includes the ability of self-removal of errors for solid balls, convergence of self-removal of errors, self-generation of precision, and self-generating system for the given.

关键词： self-generation necessary self-regulation capability viewpoint Necessary

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Climate change and its consequences for water and wastewater management

Peter A. WILDERER

《环境科学与工程前沿（英文）》 2009年第3卷第1期页码 1-1 doi: 10.1007/s11783-009-0001-z

摘要： Life, in combination with solar radiation and abiotic processes, is most probably the reason why liquid water has existed on Earth for over billions of years, and the global mean temperature has remained in a life-enabling range. Efforts to limit or even reverse global warming must be derived from the knowledge of the Earth’s complex life-support system. In this context, the balance between liquid and gaseous water plays a crucial role, and water management becomes an important field of innovation and action, globally, on the scale of watersheds but also on the very local level. Cascading use, reuse, and temporary storage of water in urban settings must be considered to limit over-extraction of water from natural resources, and to maintain the life supporting function of ecosystems. At the same time, public health requirements, cost efficiency, and reliability demands are to be met.

关键词： ecosystem management tools self-regulation urbanization water-climate relationship water reuse

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Radial electromagnetic type unbalance vibration self-recovery regulation system for high-end grinding

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0763-1

摘要： Modern rotating machines, which are represented by high-end grinding machines, have developed toward high precision, intelligence, and high durability in recent years. As the core components of grinding machine spindles, grinding wheels greatly affect the vibration level during operation. The unbalance vibration self-recovery regulation (UVSRR) system is proposed to suppress the vibration of grinding wheels during workpiece processing, eliminating or minimizing the imbalance. First, technical principles and the system composition are introduced. Second, the balancing actuator in the UVSRR system is analyzed in detail. The advanced nature of the improved structure is presented through structure introduction and advantage analysis. The performance of the balancing actuator is mutually verified by the theoretical calculation of torque and software simulation. Results show that the self-locking torque satisfies the actual demand, and the driving torque is increased by 1.73 times compared with the traditional structure. Finally, the engineering application value of the UVSRR system is verified by laboratory performance comparison and actual factory application. The balancing speed and effect of the UVSRR system are better than those of an international mainstream product and, the quality of the workpieces machined in the factory improved by 40%.

关键词： UVSRR system radial electromagnetic type vibration suppression performance simulation engineering application

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装备系统故障自愈原理研究

高金吉

《中国工程科学》 2005年第7卷第5期页码 43-48

摘要：

装备故障可否在其运行中得到控制或自行消除？故障能否像人和动物的疾病一样可以“自愈”？在系统科学的指导下，移植现代医学“自主调理”治疗原理，包括免疫、防御、代偿、自修复和适应等，可以用来指导研究装备自愈原理及工程应用；重点研究了以故障预防和消除为目标的装备系统自愈调控原理，为研制出具有自愈功能的新一代装备提供科学依据。

关键词：装备系统故障自愈原理故障自愈调控诊断主动控制

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细胞行为在基质刚性和纳米拓扑结构上的生物物理调控 Review

Yong Yang, Kai Wang, 顾晓松,Kam W. Leong

《工程（英文）》 2017年第3卷第1期页码 36-54 doi: 10.1016/J.ENG.2017.01.014

摘要：

细胞外基质(ECM) 的刚性和纳米拓扑结构影响生物体发育及生理和病理进程因此，这些生物物理特征被用于调节细胞黏附铺展至增殖、分化的各种细胞行为。描述细胞行为的生物物理调节对合理设计新型生物材料植入物和医疗装置十分关键已有学者就基质刚和纳米拓扑结构特征对细胞行为的影响分别进行了综述，然，刚和纳米拓扑结构与细胞行为的交织影响尚未有人总结。此次，我们首次综述了基质刚性和纳米拓扑结构对细胞行为的影响，然后聚焦于生物物理信号从整合素到细胞核的细胞内传，并试图将细胞行为的细胞外调节与基质的生物物理学特征联系在起最后，我们讨论了在剖析细胞行为的生物物理调节和将基质的刚和纳米拓扑结构生物力学特转化到组织工程和再生医学时存在的挑战

关键词：细胞外基质刚性纳米拓扑结构黏附配体细胞行为

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Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

《机械工程前沿（英文）》 2021年第16卷第4期页码 711-725 doi: 10.1007/s11465-021-0647-1

摘要： The safety of human–robot interaction is an essential requirement for designing collaborative robotics. Thus, this paper aims to design a novel variable stiffness actuator (VSA) that can provide safer physical human–robot interaction for collaborative robotics. VSA follows the idea of modular design, mainly including a variable stiffness module and a drive module. The variable stiffness module transmits the motion from the drive module in a roundabout manner, making the modularization of VSA possible. As the key component of the variable stiffness module, a stiffness adjustment mechanism with a symmetrical structure is applied to change the positions of a pair of pivots in two levers linearly and simultaneously, which can eliminate the additional bending moment caused by the asymmetric structure. The design of the double-deck grooves in the lever allows the pivot to move freely in the groove, avoiding the geometric constraint between the parts. Consequently, the VSA stiffness can change from zero to infinity as the pivot moves from one end of the groove to the other. To facilitate building a manipulator in the future, an expandable electrical system with a distributed structure is also proposed. Stiffness calibration and control experiments are performed to evaluate the physical performance of the designed VSA. Experiment results show that the VSA stiffness is close to the theoretical design stiffness. Furthermore, the VSA with a proportional–derivative feedback plus feedforward controller exhibits a fast response for stiffness regulation and a good performance for position tracking.

关键词： variable stiffness actuator variable stiffness module drive module symmetrical structure double-deck grooves expandable electrical system

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SALL4 maintains self-renewal of porcine pluripotent stem cells through downregulation of OTX2

Ning WANG, Sile WANG, Yaxian WANG, Yuanxing CAI, Fan YANG, Huayan WANG

《农业科学与工程前沿（英文）》 2019年第6卷第1期页码 81-92 doi: 10.15302/J-FASE-2017180

摘要：

Sall4 as one of the spalt family members contains several alternative splicing variants, which are differentially expressed and has a key role in maintaining pluripotent stem cells. However, the molecular features and function of SALL4 have not been well elucidated in porcine induced pluripotent stem cells (piPSCs). In this study, we identified splice variants and found two splicing variants through analysis of the porcine transcriptome data derived from piPSCs. SALL4A was only detected in piPSCs but SALL4B was globally expressed in porcine tissues and piPSCs. The level of SALL4B was significantly reduced when piPSCs differentiation occurred, however, the expression of SALL4A was not affected, indicating that SALL4B may be essential for the maintenance of piPSCs self-renewal. Overexpression of SALL4A and SALL4B in PEF cells could significantly stimulated expression of endogenous pluripotent genes, when SALL4B significantly promoted OCT4 expression. Conversely, SALL4A significantly promoted KLF4 expression. Additionally, both SALL4A and SALL4B could repress promoter activity in a dose-dependent manner. Conversely, OTX2 also negatively regulated SALL4 expression. These observations indicate that a negative feedback regulatory mechanism may exist between SALL4 and OTX2, which is useful for the maintenance of the self-renewal of piPSCs.

关键词： OTX2 pluripotency pig SALL4 transcription regulation

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Comparison of indices for stiffness performance evaluation

Giuseppe CARBONE, Marco CECCARELLI,

《机械工程前沿（英文）》 2010年第5卷第3期页码 270-278 doi: 10.1007/s11465-010-0023-z

摘要： This paper addresses the problem of a numerical evaluation of the stiffness performance for multibody robotic systems. An overview is presented with basic formulation concerning indices that are proposed in literature. New indices are also outlined. Stiffness indices are computed and compared for a case study. Results are used for comparing the effectiveness of the stiffness indices. The main goal is to propose a performance index describing synthetically the elastostatic response of a multibody robotic system and also for design purposes.

关键词： robotics stiffness performance indices

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Moving policy and regulation forward for single-use plastic alternatives

《环境科学与工程前沿（英文）》 2021年第15卷第3期 doi: 10.1007/s11783-021-1423-5

摘要： Single-use plastics are often used once or cannot be reused for extended periods. They are widely consumed with the rapid development of social economy. The waste generated by single-use plastics threatens ecosystem health by entering the environment and ultimately restricts sustainable human development. The innovation of sustainable and environmentally friendly single-use plastic alternative materials and the joint participation of governments, enterprises and the public are promising technologies and management approaches that can solve the problem of single-use plastics wastes. The development of single-use plastic alternative products can be promoted fundamentally only by improving relevant legislation and standards, providing differentiated industrial policies, encouraging scientific and technological innovation and expanding public participation.

关键词： Single-use plastic alternatives Policy Regulation Sustainable development

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板形计法的定义及实验应用

张进之,段春华,朱健勤

《中国工程科学》 2001年第3卷第12期页码 47-51

摘要：

板形测控数学模型、解析板形刚度理论和板形板厚协调规律的综合称为板形计法。采用两种实验方式验证了板形计法的正确性和实用性，其一是通过轧铝板实验，计算轧机板形刚度和轧件板形刚度，由实测铝板凸度验证板形刚度方程；其二是由CVC板形控制热连轧机实测数据，用离线计算自适应系数的方法验证板形测控数学模型。

关键词：板形计法板形刚度方程测控数学模型后计算自适应

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Phase transition regulation and caloric effect

《能源前沿（英文）》 2023年第17卷第4期页码 463-477 doi: 10.1007/s11708-023-0860-1

摘要： Solid state refrigeration based on caloric effect is regarded as a potential candidate for replacing vapor-compression refrigeration. Numerous methods have been proposed to optimize the refrigeration properties of caloric materials, of which single field tuning as a relatively simple way has been systemically studied. However, single field tuning with few tunable parameters usually obtains an excellent performance in one specific aspect at the cost of worsening the performance in other aspects, like attaining a large caloric effect with narrowing the transition temperature range and introducing hysteresis. Because of the shortcomings of the caloric effect driven by a single field, multifield tuning on multicaloric materials that have a coupling between different ferro-orders came into view. This review mainly focuses on recent studies that apply this method to improve the cooling performance of materials, consisting of enlarging caloric effects, reducing hysteresis losses, adjusting transition temperatures, and widening transition temperature spans, which indicate that further progress can be made in the application of this method. Furthermore, research on the sign of lattice and spin contributions to the magnetocaloric effect found new phonon evolution mechanisms, calling for more attention on multicaloric effects. Other progress including improving cyclability of FeRh alloys by introducing second phases and realizing a large reversible barocaloric effect by hybridizing carbon chains and inorganic groups is described in brief.

关键词： phase transition regulation caloric effect solid state refrigeration

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New nonlinear stiffness actuator with predefined torque‒deflection profile

《机械工程前沿（英文）》 2023年第18卷第1期 doi: 10.1007/s11465-022-0721-3

摘要： A nonlinear stiffness actuator (NSA) could achieve high torque/force resolution in low stiffness range and high bandwidth in high stiffness range, both of which are beneficial for physical interaction between a robot and the environment. Currently, most of NSAs are complex and hardly used for engineering. In this paper, oriented to engineering applications, a new simple NSA was proposed, mainly including leaf springs and especially designed cams, which could perform a predefined relationship between torque and deflection. The new NSA has a compact structure, and it is lightweight, both of which are also beneficial for its practical application. An analytical methodology that maps the predefined relationship between torque and deflection to the profile of the cam was developed. The optimal parameters of the structure were given by analyzing the weight of the NSA and the mechanic characteristic of the leaf spring. Though sliding friction force is inevitable because no rollers were used in the cam-based mechanism, the sliding displacement between the cam and the leaf spring is very small, and consumption of sliding friction force is very low. Simulations of different torque‒deflection profiles were carried out to verify the accuracy and applicability of performing predefined torque‒deflection profiles. Three kinds of prototype experiments, including verification experiment of the predefined torque‒deflection profile, torque tracking experiment, and position tracking experiment under different loads, were conducted. The results prove the accuracy of performing the predefined torque‒deflection profile, the tracking performance, and the interactive performance of the new NSA.

关键词： compliant actuator nonlinear stiffness actuator nonlinear spring predefined torque−deflection profile

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The function and regulation of OTU deubiquitinases

Jiansen Du, Lin Fu, Yingli Sui, Lingqiang Zhang

《医学前沿（英文）》 2020年第14卷第5期页码 542-563 doi: 10.1007/s11684-019-0734-4

摘要： Post-translational modification of cellular proteins by ubiquitin regulates numerous cellular processes, including cell division, immune responses, and apoptosis. Ubiquitin-mediated control over these processes can be reversed by deubiquitinases (DUBs), which remove ubiquitin from target proteins and depolymerize polyubiquitin chains. Recently, much progress has been made in the DUBs. In humans, the ovarian tumor protease (OTU) subfamily of DUBs includes 16 members, most of which mediate cell signaling cascades. These OTUs show great variation in structure and function, which display a series of mechanistic features. In this review, we provide a comprehensive analysis of current progress in character, structure and function of OTUs, such as the substrate specificity and catalytic activity regulation. Then we discuss the relationship between some diseases and OTUs. Finally, we summarize the structure of viral OTUs and their function in immune escape and viral survival. Despite the challenges, OTUs might provide new therapeutic targets, due to their involvement in key regulatory processes.

关键词： ubiquitin OTU deubiquitinases structure function regulation

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Mechanical design, modeling, and identification for a novel antagonistic variable stiffness dexterous

《机械工程前沿（英文）》 2022年第17卷第3期 doi: 10.1007/s11465-022-0691-5

摘要： This study traces the development of dexterous hand research and proposes a novel antagonistic variable stiffness dexterous finger mechanism to improve the safety of dexterous hand in unpredictable environments, such as unstructured or man-made operational errors through comprehensive consideration of cost, accuracy, manufacturing, and application. Based on the concept of mechanical passive compliance, which is widely implemented in robots for interactions, a finger is dedicated to improving mechanical robustness. The finger mechanism not only achieves passive compliance against physical impacts, but also implements the variable stiffness actuator principle in a compact finger without adding supererogatory actuators. It achieves finger stiffness adjustability according to the biologically inspired stiffness variation principle of discarding some mobilities to adjust stiffness. The mechanical design of the finger and its stiffness adjusting methods are elaborated. The stiffness characteristics of the finger joint and the actuation unit are analyzed. Experimental results of the finger joint stiffness identification and finger impact tests under different finger stiffness presets are provided to verify the validity of the model. Fingers have been experimentally proven to be robust against physical impacts. Moreover, the experimental part verifies that fingers have good power, grasping, and manipulation performance.

关键词： multifingered hand mechanism design robot safety variable stiffness actuator