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Surface tension of liquid metal: role, mechanism and application

Xi ZHAO, Shuo XU, Jing LIU

《能源前沿（英文）》 2017年 第11卷 第4期   页码 535-567 doi: 10.1007/s11708-017-0463-9

摘要： Surface tension plays a core role in dominating various surface and interface phenomena. For liquid metals with high melting temperature, a profound understanding of the behaviors of surface tension is crucial in industrial processes such as casting, welding, and solidification, etc. Recently, the room temperature liquid metal (RTLM) mainly composed of gallium-based alloys has caused widespread concerns due to its increasingly realized unique virtues. The surface properties of such materials are rather vital in nearly all applications involved from chip cooling, thermal energy harvesting, hydrogen generation, shape changeable soft machines, printed electronics to 3D fabrication, etc. owing to its pretty large surface tension of approximately 700 mN/m. In order to promote the research of surface tension of RTLM, this paper is dedicated to present an overview on the roles and mechanisms of surface tension of liquid metal and summarize the latest progresses on the understanding of the basic knowledge, theories, influencing factors and experimental measurement methods clarified so far. As a practical technique to regulate the surface tension of RTLM, the fundamental principles and applications of electrowetting are also interpreted. Moreover, the unique phenomena of RTLM surface tension issues such as surface tension driven self-actuation, modified wettability on various substrates and the functions of oxides are discussed to give an insight into the acting mechanism of surface tension. Furthermore, future directions worthy of pursuing are pointed out.

关键词： surface tension     liquid metal     soft machine     printed electronics     electrowetting     self-actuation    

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Unconventional hydrodynamics of hybrid fluid made of liquid metals and aqueous solution under applied fields

Xu-Dong ZHANG, Yue SUN, Sen CHEN, Jing LIU

《能源前沿（英文）》 2018年 第12卷 第2期   页码 276-296 doi: 10.1007/s11708-018-0545-3

摘要： The hydrodynamic characteristics of hybrid fluid made of liquid metal/aqueous solution are elementary in the design and operation of conductive flow in a variety of newly emerging areas such as chip cooling, soft robot, and biomedical practices. In terms of physical and chemical properties, such as density, thermal conductivity and electrical conductivity, their huge differences between the two fluidic phases remain a big challenge for analyzing the hybrid flow behaviors. Besides, the liquid metal immersed in the solution can move and deform when administrated with non-contact electromagnetic force, or even induced by redox reaction, which is entirely different from the cases of conventional contact force. Owing to its remarkable capability in flow and deformation, liquid metal immersed in the solution is apt to deform on an extremely large scale, resulting in marked changes on its boundary and interface. However, the working mecha- nisms of the movement and deformation of liquid metal lack appropriate models to describe such scientific issues via a set of well-established unified equations. To promote investigations in this important area, the present paper is dedicated to summarizing this unconventional hydrodynamics from experiment, theory, and simulation. Typical experimental phenomena and basic working mechanisms are illustrated, followed by the movement and deformation theories to explain these phenomena. Several representative simulation methods are then proposed to tackle the governing functions of the electrohydrodynamics. Finally, prospects and challenges are raised, offering an insight into the new physics of the hybrid fluid under applied fields.

关键词： liquid metal     hybrid fluid     hydrodynamics     surface tension     applied fields     self-actuation    

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A new method for boring of non-circular holes

ZHANG Kai, HU De-jin

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 456-460 doi: 10.1007/s11465-006-0058-3

摘要： A revolving electromagnetic actuation mechanism composed of an electromagnetic stator and an electromagnetic rotor has been developed for boring non-circular holes. The main component of the rotor is a flexure-hinged based flexible body. There are four pole-pair coils in the stator supplying actuation currents. The micro-displacement between the stator and rotor can be controlled by changing the currents applied in the pole-pair coils. Through linearization of the actuation force near the static action point, a linear relationship between the control current and the actuation force was established, and the synchronizing control method of the electromagnetic actuation mechanism is presented here. With two-factor analysis of the linearization error of the actuation force, the influences of control current and micro-displacement to the linearization error of the actuation force were studied. Then, the principle for designing the basic parameters of the magnetic actuation mechanism is put forward. The calibration of the mechanism indicates that the relationship between the micro-displacement of the rotor and the control current has linear characteristics in the required micro-displacement range. Simulation tests show that the turning radius of the rotor changes with the control current. The proposed mechanism can feasibly supply a controllable micro displacement to the boring bar.

关键词： electromagnetic actuation     control method     displacement     flexible body     revolving electromagnetic    

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Exploring self-organization and self-adaption for smart manufacturing complex networks

《工程管理前沿（英文）》 2023年 第10卷 第2期   页码 206-222 doi: 10.1007/s42524-022-0225-1

摘要： Trends toward the globalization of the manufacturing industry and the increasing demands for small-batch, short-cycle, and highly customized products result in complexities and fluctuations in both external and internal manufacturing environments, which poses great challenges to manufacturing enterprises. Fortunately, recent advances in the Industrial Internet of Things (IIoT) and the widespread use of embedded processors and sensors in factories enable collecting real-time manufacturing status data and building cyber–physical systems for smart, flexible, and resilient manufacturing systems. In this context, this paper investigates the mechanisms and methodology of self-organization and self-adaption to tackle exceptions and disturbances in discrete manufacturing processes. Specifically, a general model of smart manufacturing complex networks is constructed using scale-free networks to interconnect heterogeneous manufacturing resources represented by network vertices at multiple levels. Moreover, the capabilities of physical manufacturing resources are encapsulated into virtual manufacturing services using cloud technology, which can be added to or removed from the networks in a plug-and-play manner. Materials, information, and financial assets are passed through interactive links across the networks. Subsequently, analytical target cascading is used to formulate the processes of self-organizing optimal configuration and self-adaptive collaborative control for multilevel key manufacturing resources while particle swarm optimization is used to solve local problems on network vertices. Consequently, an industrial case based on a Chinese engine factory demonstrates the feasibility and efficiency of the proposed model and method in handling typical exceptions. The simulation results show that the proposed mechanism and method outperform the event-triggered rescheduling method, reducing manufacturing cost, manufacturing time, waiting time, and energy consumption, with reasonable computational time. This work potentially enables managers and practitioners to implement active perception, active response, self-organization, and self-adaption solutions in discrete manufacturing enterprises.

关键词： cyber–physical systems     Industrial Internet of Things     smart manufacturing complex networks     self-organization and self-adaption     analytical target cascading     collaborative optimization    

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Optimal design of a linkage–cam mechanism-based redundantly actuated parallel manipulator

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 451-467 doi: 10.1007/s11465-021-0634-6

摘要： A redundantly actuated parallel manipulator (RAPM) with mixed translational and rotational degrees of freedom (DOFs) is challenged for its dimensionally homogeneous Jacobian modeling and optimal design of architecture. In this paper, a means to achieve redundant actuation by adding kinematic constraints is introduced, which reduces the DOFs of the end-effector (EE). A generic dimensionally homogeneous Jacobian is developed for this type of RAPMs, which maps the generalized velocities of three points on the EE to the joint velocities. A new optimization algorithm derived from this dimensionally homogeneous Jacobian is proposed for the optimal design of this type of RAPMs. As an example, this paper presents a spatial RAPM involving linkages and cam mechanisms. This RAPM has 4 DOFs and 6 translational actuations. The linkage lengths and the position of the universal joints of the RAPM are optimized based on the dimensionally homogeneous Jacobian.

关键词： redundant actuation     parallel manipulator     linkage–cam mechanism     Jacobian     optimal design    

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Emerging trends in self-healable nanomaterials for triboelectric nanogenerators: A comprehensive review

《能源前沿（英文）》   页码 727-750 doi: 10.1007/s11708-023-0896-2

摘要： A thorough analysis of triboelectric nanogenerators (TENGs) that make use of self-healable nanomaterials is presented in this review. These TENGs have shown promise as independent energy sources that do not require an external power source to function. TENGs are developing into a viable choice for powering numerous applications as low-power electronics technology advances. Despite having less power than conventional energy sources, TENGs do not directly compete with these. TENGs, on the other hand, provide unique opportunities for future self-powered systems and might encourage advancements in energy and sensor technologies. Examining the many approaches used to improve nanogenerators by employing materials with shape memory and self-healable characteristics is the main goal of this review. The findings of this comprehensive review provide valuable information on the advancements and possibilities of TENGs, which opens the way for further research and advancement in this field. The discussion of life cycle evaluations of TENGs provides details on how well they perform in terms of the environment and identifies potential improvement areas. Additionally, the cost-effectiveness, social acceptability, and regulatory implications of self-healing TENGs are examined, as well as their economic and societal ramifications.

关键词： triboelectric nanogenerator (TENG)     self-healable nanomaterials     self-powered devices     energy    

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Modular structure of a self-reconfigurable robot

FEI Yanqiong, DONG Qinglei, ZHAO Xifang

《机械工程前沿（英文）》 2007年 第2卷 第1期   页码 116-119 doi: 10.1007/s11465-007-0020-z

摘要： This paper proposes a novel, hermaphroditic, and lattice self-reconfigurable modular robot. Each module is composed of a center body a cubic part and six sides that can rotate independently. There are two holes and two extensible pegs on each side. The rotary motion of each side and the extensible motion of the pegs are generated by a motor connected to a reducer, using a cone-shaped gear, belt, clutch, etc. The structure of the module is compact, and has space to extend further.

关键词： compact     self-reconfigurable modular     hermaphroditic     cone-shaped     clutch    

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Signal separation technology for diphase opposition giant magnetostrictive self-sensing actuator

Xinhua WANG, Shuwen SUN, Jian ZHEN, Qianyi YA, Deguo WANG,

《机械工程前沿（英文）》 2010年 第5卷 第2期   页码 176-183 doi: 10.1007/s11465-010-0001-5

摘要： The structure and principle of a new type of a diphase opposition giant magnetostrictive self-sensing actuator is introduced. A bridge analysis model based on variable inductance is established. Dynamic balance separation technology for the giant magnetostrictive self-sensing actuator comes true by the least means square (LMS) self-adapting algorithm. The scheme design of one important part of the circuit with the real-time separation circuit of the dynamic balance signal based on a digital signal processor is obtained. The part of the signal separated circuit is designed, which includes logarithmic-antilog practical multiplication circuit, amplifying circuit, filter circuits, and amplifier circuit. Based on the embedded system simulation software—PROTUES, the simulation effect of the circuit that separates the sensing signal from the mixed signals is obvious, which indicates that the circuit can rapidly and stably work. Moreover, the structure is simple, reliable, and meets the practical requirement.

关键词： giant magnetostrictive material (GMM) self-sensing actuator     least means square (LMS) self-adapting algorithm     design of self-adaptive circuit    

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Behaviour of self-centring shear walls——A state of the art review

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 53-77 doi: 10.1007/s11709-022-0850-0

摘要： The application of unbonded post-tensioning (PT) in structural walls has led to the development of advanced self-centring (rocking) shear wall systems that has significant advantages, including accelerated construction due to the incorporation of prefabricated elements and segmental construction for different materials (e.g., concrete, masonry, and timber), reduced residual drifts, and little damage upon extreme seismic and wind loads. Concrete, masonry, and timber are often used for the construction of unbonded PT structural wall systems. Despite extensive research since the 1980s, there are no well-established design guidelines available on the shear wall configuration with the required energy dissipation system, joint’s locations and acceptance criteria for shear sliding, confinement, seismic performance factors, PT loss, PT force range and residual drifts of shear walls subjected to lateral loads. In this research a comprehensive state-of-the-art literature review was performed on self-centring shear wall system. An extensive study was carried out to collect a database of 100 concrete, masonry, and self-centring shear wall tests from the literature. The established database was then used to review shear walls’ configurations, material, and components to benchmark requirements applicable for design purposes. The behaviour of concrete, masonry and timber shear walls were compared and critically analysed. The general behaviour, force-displacement performance of the walls, ductility, and seismic response factors, were critically reviewed and analysed for different self-centring wall systems to understand the effect of different parameters including configurations of the walls, material used for construction of the wall (concrete, masonry, timber) and axial stress ratio. The outcome of this research can be used to better understand the behaviour of self-centring wall system in order to develop design guidelines for such walls.

关键词： self-centring shear walls     rocking walls     energy dissipation     seismic performance factors     PT loss     residual drift    

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Recycled glass replacement as fine aggregate in self-compacting concrete

Yasser SHARIFI, Mahmoud HOUSHIAR, Behnam AGHEBATI

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 419-428 doi: 10.1007/s11709-013-0224-8

摘要： With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal by replacement of waste glass with concrete composition materials. Due to differences in mixture design, placement and consolidation techniques, the strength and durability of Self Compacting Concrete (SCC) may be different than those of conventional concrete. Therefore, replacement of waste glass with fine aggregate in SCC should deeply be investigated compared to conventional concretes. The aim of the present study is to investigate the effect of glass replacement with fine aggregate on the SCC properties. In present study, fine aggregate has been replaced with waste glass in six different weight ratios ranging from 0% to 50%. Fresh results indicate that the flow-ability characteristics have been increased as the waste glass incorporated to paste volume. Nevertheless, compressive, flexural and splitting strengths of concrete containing waste glass have been shown to decrease when the content of waste glass is increased. The strength reduction of concrete in different glass replacement ratios is not remarkable, thus it can be produced SCC with waste glass as fine aggregate in a standard manner.

关键词： Self Compacting Concrete (SCC)     recycle glass     fine aggregate     fresh and hardened properties    

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Effect of calcium lactate on compressive strength and self-healing of cracks in microbial concrete

Kunamineni VIJAY, Meena MURMU

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 515-525 doi: 10.1007/s11709-018-0494-2

摘要： This paper presents the effect on compressive strength and self-healing capability of bacterial concrete with the addition of calcium lactate. Compared to normal concrete, bacterial concrete possesses higher durability and engineering concrete properties. The production of calcium carbonate in bacterial concrete is limited to the calcium content in cement. Hence calcium lactate is externally added to be an additional source of calcium in the concrete. The influence of this addition on compressive strength, self-healing capability of cracks is highlighted in this study. The bacterium used in the study is and was added to both spore powder form and culture form to the concrete. spore powder of 2 million cfu/g concentration with 0.5% cement was mixed to concrete. Calcium lactates with concentrations of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% of cement, was added to the concrete mixes to test the effect on properties of concrete. In other samples, cultured with a concentration of 1×10 cells/mL was mixed with concrete, to study the effect of bacteria in the cultured form on the properties of concrete. Cubes of 100 mm×100 mm×100 mm were used for the study. These cubes were tested after a curing period of 7, 14 and 28 d. A maximum of 12% increase in compressive strength was observed with the addition of 0.5% of calcium lactate in concrete. Scanning electron microscope and energy dispersive X-ray spectroscopy examination showed the formation of ettringite in pores; calcium silicate hydrates and calcite which made the concrete denser. A statistical technique was applied to analyze the experimental data of the compressive strengths of cementations materials. Response surface methodology was adopted for optimizing the experimental data. The regression equation was yielded by the application of response surface methodology relating response variables to input parameters. This method aids in predicting the experimental results accurately with an acceptable range of error. Findings of this investigation indicated the influence of added calcium lactate in bio-concrete which is quite impressive for improving the compressive strength and self-healing properties of concrete.

关键词： calcium lactate     bacillus subtilis     compressive strength     self-healing of cracks    

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Computational fluid dynamic analysis of flutter characteristics for self-anchored suspension bridges

ZHU Zhiwen, WANG Zhaoxiang, CHEN Zhengqing

《结构与土木工程前沿（英文）》 2008年 第2卷 第3期   页码 267-273 doi: 10.1007/s11709-008-0034-6

摘要： This paper outlines the essentials and procedures of computational fluid dynamics (CFD) simulation applicable to evaluating flutter derivatives of bridge decks. An arbitrary Lagrangian-Eulerian (ALE) description of the flow around the moving rigid box girder combined with the finite volume discretization and multi-grid algorithm is presented. The proposed methods are employed to identify flutter derivatives of the bridge deck of the Sanchaji Self-anchored Suspension Bridge. The results agree well with ones from wind tunnel tests. It demonstrates accuracy and efficiency of the present method.

关键词： discretization     computational     description     Self-anchored Suspension     simulation applicable    

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Effects of solvents and temperature on spherulites of self-assembled phloroglucinol tristearate

Yawen Yao, Sabine Rosenfeldt, Kai Zhang

《化学科学与工程前沿（英文）》 2020年 第14卷 第3期   页码 389-396 doi: 10.1007/s11705-019-1911-3

摘要： Herein, phloroglucinol tristearate (PhgTS) was used to study the crystallization process due to its unique symmetric structure containing a benzene ring and three aliphatic chains. Spherulites of crystallized PhgTS from four solvents under diverse conditions were analyzed in detail and their formation process was studied. Maltese cross is shown by PhgTS spherulites obtained from aprotic solvents via polarized optical microscopy. In comparison, no Maltese cross can be observed from branch-like crystals formed from protic solvents. Independent on the microscaled morphology, lamellae were found to be the basic blocks constructing both PhgTS spherulites and branch-like crystals, which were formed predominantly by stacked PhgTS molecules. Although differential characters of the solvents did not affect the formation of lamellas, the solvents played a crucial role in the formation of self-assembled microscaled morphologies. In particular, the morphologies of spherulites were strongly affected by the concentration of PhgTS solutions, surrounding temperature and evaporation rate of solvents. Generally, a higher concentration of PhgTS led to more homogeneous spherulites, a lower evaporation rate resulted in more compact spherulites, and a higher surrounding temperature generated preferentially more ring-banded spherulites of PhgTS.

关键词： phloroglucinol     tristearate     aprotic and protic solvent     self-assembly     spherulites    

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Estimating moment capacity of ferrocement members using self-evolving network

Abdussamad ISMAIL

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 926-936 doi: 10.1007/s11709-019-0527-5

摘要： In this paper, an empirical model based on self-evolving neural network is proposed for predicting the flexural behavior of ferrocement elements. The model is meant to serve as a simple but reliable tool for estimating the moment capacity of ferrocement members. The proposed model is trained and validated using experimental data obtained from the literature. The data consists of information regarding flexural tests on ferrocement specimens which include moment capacity and cross-sectional dimensions of specimens, concrete cube compressive strength, tensile strength and volume fraction of wire mesh. Comparisons of predictions of the proposed models with experimental data indicated that the models are capable of accurately estimating the moment capacity of ferrocement members. The proposed models also make better predictions compared to methods such as the plastic analysis method and the mechanism approach. Further comparisons with other data mining techniques including the back-propagation network, the adaptive spline, and the Kriging regression models indicated that the proposed models are superior in terms prediction accuracy despite being much simpler models. The performance of the proposed models was also found to be comparable to the GEP-based surrogate model.

关键词： ferrocement     moment capacity     self-evolving neural network    

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Investigations concerning seismic response control of self-anchored suspension bridge with MR dampers

YANG Menggang, HU Jianhua

《结构与土木工程前沿（英文）》 2008年 第2卷 第1期   页码 43-48 doi: 10.1007/s11709-008-0011-0

摘要： To mitigate the seismic response of self-anchored suspension bridges, equations of motion governing the coupled system of bridge- magneto-rheological (MR) dampers subject to seismic excitation are formulated by employing the phenomenological model of MR dampers. A corresponding computer program is developed and employed for studying the seismic response control of a self-anchored suspension bridge with a main span of 350 m. The effect of variable current and number of dampers on seismic response control is investigated. The numerical results indicate the longitudinal displacement of the tower top and bridge girder decrease with the increase in input current and number of MR dampers attached longitudinally at the tower-girder connections, and the internal forces of the tower are effectively attenuated as well. It appears that small electronic current (0.5 A in this study) may sufficiently attenuate the seismic responses for practical engineering applications.

关键词： longitudinal displacement     corresponding computer     excitation     phenomenological     self-anchored suspension    

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标题 作者 时间 类型 操作

Surface tension of liquid metal: role, mechanism and application

Xi ZHAO, Shuo XU, Jing LIU

期刊论文

Unconventional hydrodynamics of hybrid fluid made of liquid metals and aqueous solution under applied fields

Xu-Dong ZHANG, Yue SUN, Sen CHEN, Jing LIU

期刊论文

A new method for boring of non-circular holes

ZHANG Kai, HU De-jin

期刊论文

Exploring self-organization and self-adaption for smart manufacturing complex networks

期刊论文

Optimal design of a linkage–cam mechanism-based redundantly actuated parallel manipulator

期刊论文

Emerging trends in self-healable nanomaterials for triboelectric nanogenerators: A comprehensive review

期刊论文

Modular structure of a self-reconfigurable robot

FEI Yanqiong, DONG Qinglei, ZHAO Xifang

期刊论文

Signal separation technology for diphase opposition giant magnetostrictive self-sensing actuator

Xinhua WANG, Shuwen SUN, Jian ZHEN, Qianyi YA, Deguo WANG,

期刊论文

Behaviour of self-centring shear walls——A state of the art review

期刊论文

Recycled glass replacement as fine aggregate in self-compacting concrete

Yasser SHARIFI, Mahmoud HOUSHIAR, Behnam AGHEBATI

期刊论文

Effect of calcium lactate on compressive strength and self-healing of cracks in microbial concrete

Kunamineni VIJAY, Meena MURMU

期刊论文

Computational fluid dynamic analysis of flutter characteristics for self-anchored suspension bridges

ZHU Zhiwen, WANG Zhaoxiang, CHEN Zhengqing

期刊论文

Effects of solvents and temperature on spherulites of self-assembled phloroglucinol tristearate

Yawen Yao, Sabine Rosenfeldt, Kai Zhang

期刊论文

Estimating moment capacity of ferrocement members using self-evolving network

Abdussamad ISMAIL

期刊论文

Investigations concerning seismic response control of self-anchored suspension bridge with MR dampers

YANG Menggang, HU Jianhua

期刊论文