Search results

The purpose of this study is to develop a robotic hand–arm system for on-orbit servicing missions at the Tiangong-2 (TG-2) Space Laboratory.

The hand–arm system is mainly composed of a lightweight arm, a dexterous hand, an electrical cabinet, a global camera, a hand–eye camera and some human–machine interfaces. The 6-DOF lightweight arm and the 15-DOF dexterous hand adopt the modular design philosophy that greatly reduces the design cycle and cost. To reduce the computational burden on the central controller and simplify system maintenance, an electrical system which has a hierarchical structure is introduced.

The prototypical operating experiments completed in TG-2 space laboratory demonstrate the performance of the hand–arm system and lay foundations for the future applications of space manipulators.

The main contributions of this paper are as follows a robotic hand–arm system which can perform on-orbit servicing missions such as grasping the electric drill, screwing the bolt, unscrewing J599 electrical connector has been developed; a variable time step motion plan method is proposed to adjust the trajectories of the lightweight arm to reduce or eliminate the collision force; and a dexterous hand uses the coordinated grasp control based on the object Cartesian stiffness to realize stable grasp. To solve the kinematic mapping from the cyber glove commands to the dexterous hand, a fingertip-position-based method is proposed to acquire precise solutions.

The purpose of this paper is to study the dynamic modeling and controller design for the series element actuator (SEA) joints. The robot equipped with SEA joints is a strong coupling, nonlinear, highly flexible system, which can prevent itself from damaging by the accidental impact and the people to be injured by the robot.

Based on the torque source model, the authors built a dynamic model for the SEA joint. To improve the accuracy of this model, the authors designed an elastic element into the joint and implemented the vector control for the joint motor. A control method of combined PD controller and back-stepping was proposed. Moreover, the torque control could be transformed into position control by stiffness transformation.

The established model and the proposed method are verified by the position and torque control experiments. The experimental results show that the dynamic model of the SEA joint is accurate and the proposed control strategies for the SEA joint are reasonable and feasible.

The main contribution of the paper is as follows: designing an elastic element with high linearity to improve the model accuracy of the SEA joint. The control strategy-based back-stepping method for the SEA joint is proposed to increase the robustness of the controller.

Uncovering the relationship between Industry 4.0 (I4.0) technologies and circular economy (CE) practices is critical not only for implementing CE but also for leveraging I4.0 to achieve sustainable development goals. However, the potential connection between them – especially how different I4.0 technologies may influence various CE practices – remains inadequately researched. The purpose of this study was to quantitatively explore the impacts of various I4.0 technologies on CE practices.

A mixed method consisting of a systematic literature review, content analysis, and social network analysis was adopted. First, 266 articles were selected and mined for contents of I4.0 technologies and CE practices; 27 I4.0 technologies and 21 CE practices were identified. Second, 62 articles were found that prove the positive influence of I4.0 technologies on CE practices, and 124 relationships were identified. Third, based on evidence supporting the link between I4.0 technologies and CE practices, a two-mode network and two one-mode networks were constructed, and their network density and degree centrality indicators were analyzed.

I4.0 technologies have a low application scope and degree for promoting CE. The adoption of a single I4.0 technology has limited effect on CE practices, and wider benefits can be realized through integrating I4.0 technologies. The Internet of Things (IoT), additive manufacturing, big data and analytics, and artificial intelligence (AI) are among the top technologies promoting CE implementation and reduction and recycling were identified as the main mechanism. The integration of these technologies is the most popular and effective. Twelve CE practices were identified to be the most widely implemented and supported by I4.0 technologies.

First, only journal articles, reviews, and online publications written in English were selected, excluding articles published in other languages. Therefore, the results obtained only represent a specific group of scholars, which may be fragmented to a certain extent. Second, because the extraction of the impact of I4.0 on CE mainly relies on a manual literature review, this paper only provides the statistics of the number of publications involving relationships, while lacking the weight measurement of relationships.

A comprehensive, quantitative, and visual analysis method was employed to unveil the current implementation levels of I4.0 technologies and CE practices. Further, it was explored how different I4.0 technologies can affect various CE aspects, how different I4.0 technologies are integrated to promote CE realization, and how various CE practices are implemented simultaneously by I4.0 technologies.

This paper aims to report the conductivity measurement of ten different surfactant-free microemulsions (SFMEs)

The variations of electrical conductivity as a function of water volume fraction are examined at one constant alcohol (or DMF, ethyl lactate, γ-valerolactone)/water, alcohol (or DMF, ethyl lactate, γ-valerolactone)/oil volume ratios for each sample.

Most of the results are consistent with percolation character. The conductive mechanism of these SFMEs is discussed by the percolation model, and it is found that it might be described with the static percolation model below the percolation threshold.

Our report gives a systematic research on the percolation mechanism of as many species of SFMEs as possible by the theoretical models

This study aims to fabricate a novel electromagnetic interference (EMI) shielding composite aerogel with both thermal insulation and high temperature warning functions.

An emerging bio-based polypyrrole (PPy) gel/Fe₃O₄/calcium alginate (PFC) EMI shielding composite aerogel was prepared by freeze-drying and in situ polymerization method. First, Fe₃O₄/calcium alginate (CA) aerogel was obtained by freeze-drying the Fe₃O₄/CA mixture. Then, PPy/Fe₃O₄/CA was obtained by synthesizing PPy on the surface of CA/Fe₃O₄ aerogel through in situ polymerization. Finally, PPy/Fe₃O₄/CA was immersed in porphyrin solution (cross-linking agent) to get the final PFC EMI shielding composite aerogel.

Due to the matched impedance between Fe₃O₄ and PPy, the EMI shielding performance of PFC composite aerogel can reach up to −8 dB. In addition, the PFC EMI shielding composite aerogel also shows excellent self-extinguishing and thermal insulation properties. After leaving the flame, the burning PFC aerogel is quickly extinguished. When the PFC aerogel is placed on the heating plate at 230 °C, the temperature on the side of the aerogel away from the heating plate is only 90.3 °C after 5 min of heating. The electrical resistance of the PFC composite aerogel can be reduced from 3.62 × 104 O to 5 × 102 O to trigger the warning light after 3 s of exposure to the alcohol lamp flame. This reversible thermal resistance response characteristic can be used to give an early warning signal when the PFC encounters high temperature or flame.

This work provides a novel strategy for designing a multifunctional EMI shielding composite aerogel with repeatable high temperature warning performance. This PFC composite aerogel shows potential applications in the prevention of material combustion in high temperature electromagnetic environments.

Previous research has yielded inconsistent findings of the effects that task conflict has on creative outcomes, with some research finding a negative relationship but others holding a positive or even no significant relationship. Drawing on the too-much-of-a-good-thing effect approach, this paper aims to investigate the curvilinear relations between task conflict and creative idea generation as well as the mediating role of task reflexivity and the moderating role of task complexity.

Two studies were carried out to test the proposed relationship. In Study 1, multisource and lagged data collected from 533 employees and 140 corresponding supervisors were used to test the curvilinear relationship between task conflict and creative idea generation as well as the moderating effect of task complexity. In Study 2, the authors extended the findings by exploring the mediating effect of task reflexivity using a matched sample of 350 employees and 99 corresponding supervisors.

Task conflict had an inverted U-shaped relationship with creative idea generation, and task reflexivity partially mediated this relationship. Besides, this association was moderated by task complexity such that the curvilinear relationship was more pronounced for tasks with lower complexity.

This study was more or less contaminated by common method variance because some variables were derived from the same sources. Also, task conflict might be necessitated to differentiate and more situational variables should be considered to draw a complete picture.

Managers should undertake conflict management according to the levels of task conflict and task complexity. At a lower degree of task conflict, managers might motivate employees to think more about task-related issues; at higher levels of task conflict, managers should act as conflict mediators to reduce the underlying negative effects, especially for simple tasks.

These findings could help us understand the boundary conditions under, and the underlying mechanisms by, which task conflict has an impact on creative idea generation.

This paper aims to present a kinematics performance analysis and control for a continuum robot based on a dynamic model to achieve control of the robot.

To analyze the motion characteristics of the robot, its kinematics model is derived by the geometric analysis method, and the influence of the configuration parameters of the robot on workspace is investigated. Moreover, the dynamic model is established by the principle of virtual work to analyze the mapping relationship among the bending shape, the forces/torques applied to the robot. To achieve better control of the robot, a control strategy for continuum robot based on the dynamic model is put forward.

Results of the simulations and experiments verify the proposed continuum structure and motion model, the maximum position error is 5.36 mm when the robot performs planar bending motion and the average position error of the robot in spatial circular motion is 5.84 mm. The proposed model can accurately describe the deformation movement of the robot and realize its motion control with a few position errors.

The kinematics analysis and control model proposed in this paper can achieve precise control of the robot, which can be used as a reference for the motion planning and shape reconstruction of continuum robot.

The paper aims to find the correlation between the microparameters and the macroparameters of the soil. The study aims to calibrate the macroscale and microscale parameters of rolling resistance contact models to successfully apply the discrete element method to do some research of the geotechnical problem.

The paper opted for an exploratory study using the PFC3D to simulate the triaxial tests that include more than 50 cases and the coupling analysis method, which considering several effect of various factors.

The paper provides a quantitative relationship between the macroparameters and microparameters of the rolling resistance linear model and a method for fast calibration of macroscopic parameters is proposed and verified by a triaxial test example.

This paper provides the quantitative relationship of micro and macroparameters in the rolling resistance linear model by studying a single factor and considering the coupling effect of various factors and a fast method for the calibration of microparameters based on the rolling resistance linear model is proposed.

The aim of this paper is to research the acceptance mechanism of building information modeling (BIM) technology and to explore the differences among Architecture/Engineering/Construction (A/E/C) professionals with different individual characteristics. The proposed acceptance mechanism of BIM technology is intended to be used by industry stakeholders to propose decisions and measures, and improve the degree of BIM adoption.

Traditional hypothesis testing is adopted by the current study to empirically research the specific mechanism of A/E/C professionals accepting BIM technologies. In the one phase, a conceptual model based on technology acceptance model (TAM) and technology organization environment (TOE) theory was established and a large-scale questionnaire survey was conducted. In the other phase, structural equation modeling (SEM) was used to analyze acquired sample data, so as to empirically test the validity of the proposed linkage.

The results show first that perceived ease of use has no significant influence on perceived usefulness, and perceived usefulness has no significant effect on behavior intention as well. Second, BIM technical features and government BIM policies have positive effects on perceived usefulness, BIM technical features and organization supports have positive effects on perceived ease of use. Third, the BIM acceptance mechanism of A/E/C professionals is diverse from respondents with different characteristics, e.g. regions and working time.

The authors highlight the large sample size, as well as the nationwide context, of the questionnaire survey. Meanwhile, acceptance differences among A/E/C professionals with different demographic characteristics have been clarified using profound data and t-test. The findings of this study enrich the research on the acceptance mechanism of BIM technology, and contribute to relevant stakeholders taking targeted measures to promote the effective application of BIM technology nationwide.

The purpose of this study is to address these questions. Word-of-mouth (WOM) is increasingly important in business-to-business (B2B) decision-making. Yet, research on this topic is rather limited, and often borrows from business-to-consumer (B2C) WOM literature. The question remains as to whether these assumptions realistically occur in B2B WOM. Specifically, this study explores the following questions: What value does B2B WOM have? Why do social media influencers in B2B engage in WOM? What type(s) of social media influencers spread WOM in B2B?

To address these questions, this study adopts a qualitative research strategy. This study focuses on industry analysts in information technology markets who often influence the buying decisions of customers through their expertise and recommendations of technology solutions. Based on interviews with these influencers, this study explicates B2B WOM, an area the authors know much less of in comparison to B2C WOM.

This study reveals differences in who spreads WOM within B2B, their roles, key features of their content and how they spread WOM. Second, this study demonstrates the types of actors spreading WOM in B2B in relation to the type of WOM and how it actually influences B2B markets.

This study broadens the current definition of WOM and, specifically, showcases WOM not only as amplifying messages but as a means to co-create the market itself with vendors and clients. This research offers several contributions to the B2B WOM literature and influencer practice.