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This paper aims to propose an enhanced static model of commercial braided pneumatic artificial muscles (PAMs), which is fully analytical without the need for experimentally determined parameters.

To address the highly nonlinear issues of PAMs, the enhanced model is derived considering the irregular shapes close to their end-fittings, as well as the elastic energy stored in both their braids and rubber bladders. The hysteresis characteristics of PAMs are also explored by analyzing the friction in the crossovers of the interlacing braided strands, together with that between the strands and their surrounding bladders. The isobaric and isometric experiments of a commercial PAM are conducted to demonstrate the enhancement, and the model accuracy is evaluated and compared with some existing models in terms of root mean square errors (RMSEs). Additionally, the proposed model is simplified to facilitate the applications that entail high computational efficiency.

The proposed model agrees well with the experimental results, which indicates its viability to accurately predict the static behaviors. An overall RMSE of 5.24 N shows that the enhanced model is capable of providing higher accuracy than the existing analytical models, while keeping the modeling cost at a minimum.

The proposed model, taking account of non-cylindrical shapes, elastic energy and friction, succeeds in enhancing the static predictions of commercial PAMs. The fully analytical model may accelerate the development of novel PAM-based robots for high-precision control, while giving a deeper understanding of commercial PAMs.

The purpose of this paper is to develop an easily implemented and practical stabilizing strategy for the hardware-in-the-loop (HIL) system. As the status of HIL system in the ground verification experiment for space equipment keeps rising, the stability problems introduced by high stiffness of industrial robot and discretization of the system need to be solved ungently. Thus, the study of the system stability is essential and significant.

To study the system stability, a mathematical model is built on the basis of control circle. And root-locus and 3D root-locus method are applied to the model to figure out the relationship between system stability and system parameters.

The mathematical model works well in describing the HIL system in the process of capturing free-floating targets, and the stabilizing strategy can be adopted to improve the system dynamic characteristic which meets the needs of the practical application.

A method named 3D root-locus is extended from traditional root-locus method. And the improved method graphically displays the stability of the system under the influence of multivariable. And the strategy that stabilize the system with elastic component has a strong feasible and promotional value.

The purpose of this paper is to develop a set of ground experiment system to verify the basic functions of space effector and the capturing reliability of space end-effector for the free-floating target payload in the three-dimensional space. The development of ground experiment system for space end-effector is essential and significant, because it costs too much to launch a space robot or other spacecraft and carry out operation tasks in space. Owing to the negligible gravity in space, which is different from that in the ground environment, ground experiment system for space end-effector should have the capability of verifying the basic functions of space effector and the reliability of space end-effector in capturing the free-floating target payload in space.

The ground experiment system for space end-effector mainly adopts the hybrid simulation method, which includes the real hardware experiment and software simulation. To emulate the micro-gravity environment, the contact dynamics simulator is applied to emulating the motion state of the free-floating target payload, while the admittance control is used to realize the “soft” capturing of space end-effector to simulate the real situation in space.

With the gravity compensation, the influence of gravity is almost eliminated and the results meet the requirements of the experiment. In the ground experiment, the admittance control is effective and the actual motion state of space end-effector capturing the target in space can be simulated. The experiment results show that space end-effector can capture the free-floating target payload successfully and hopefully have the ability to capture a free-floating target in space.

The system can verify space end-effector capturing the free-floating target payload in three-dimensional space and imitate the motion of space end-effector capturing the free-floating target in space. The system can also be modified and improved for application in the verification of space robot capturing and docking the target, which is valuable for the ground verification of space applications.

The purpose of this paper is to solve the ground verification and test method for space robot system capturing the target satellite based on visual servoing with time-delay in 3-dimensional space prior to space robot being launched.

To implement the approaching and capturing task, a motion planning method for visual servoing the space manipulator to capture a moving target is presented. This is mainly used to solve the time-delay problem of the visual servoing control system and the motion uncertainty of the target satellite. To verify and test the feasibility and reliability of the method in three-dimensional (3D) operating space, a set of ground hardware-in-the-loop simulation verification systems is developed, which adopts the end-tip kinematics equivalence and dynamics simulation method.

The results of the ground hardware-in-the-loop simulation experiment validate the reliability of the eye-in-hand visual system in the 3D operating space and prove the validity of the visual servoing motion planning method with time-delay compensation. At the same time, owing to the dynamics simulator of the space robot added in the ground hardware-in-the-loop verification system, the base disturbance can be considered during the approaching and capturing procedure, which makes the ground verification system realistic and credible.

The ground verification experiment system includes the real controller of space manipulator, the eye-in-hand camera and the dynamics simulator, which can veritably simulate the capturing process based on the visual servoing in space and consider the effect of time delay and the free-floating base disturbance.

The purpose of this paper is to present the design and experiment of a universal space-saving end-effector for multi-task operations.

The universal end-effector is equipped with capture and actuation transmission capabilities with two corresponding subsystems, which are highly integrated systems of mechanics, electronics and sensors. A trefoil-shaped capture system is developed for closed envelop. The worm gear pair is adopted for self-locking and space-saving, and it is used in a unique manner for three grapple chains’ synchronous motion. The combination of optimal straight path linkage and pantograph mechanism is proposed in the transmission system. The electrical structure and the multi-sensory system provide the foundation for control strategy.

Simulations and experiments demonstrated characteristics of the universal end-effector. The compliance of the manipulator guaranteed the achievement of “soft capture” by the end-effector. Due to the self-locking property, the end-effector and the grapple interface could keep rigid connection when powered off.

The design process takes practical requirements into consideration. Through experiments, it is proved that the proposed end-effector can be used for the multi-task operations with corresponding tools.

Among end-effectors with operation function, the misalignment tolerance (MT) is originally regarded as a key factor. The adoptions of the worm gear pair and the linkage make it space-saving compared to conventional designs.

The purpose of this paper is to develop a combined method for three-dimensional incompressible flow and heat transfer by the spectral collocation method (SCM) and the artificial compressibility method (ACM), and further to study the performance of the combined method SCM-ACM for three-dimensional incompressible flow and heat transfer.

The partial differentials in space are discretized by the SCM with Chebyshev polynomial and Chebyshev–Gauss–Lobbatto collocation points. The unsteady artificial compressibility equations are solved to obtain the steady results by the ACM. Three-dimensional exact solutions with trigonometric function form and exponential function form are constructed to test the accuracy of the combined method.

The SCM-ACM is developed successfully for three-dimensional incompressible flow and heat transfer with high accuracy that the minimum value of variance can reach. The accuracy increases exponentially along with time marching steps. The accuracy is also improved exponentially with the increasing of nodes before stable accuracy is achieved, while it keeps stably with the increasing of the time step. The central processing unit time increases exponentially with the increasing of nodes and decreasing of the time step.

It is difficult for the implementation of the implicit scheme by the developed SCM-ACM. The SCM-ACM can be used for solving unsteady impressible fluid flow and heat transfer.

The SCM-ACM is applied for two classic cases of lid-driven cavity flow and natural convection in cubic cavities. The present results show good agreement with the published results with much fewer nodes.

The combined method SCM-ACM is developed, firstly, for solving three-dimensional incompressible fluid flow and heat transfer by the SCM and ACM. The performance of SCM-ACM is investigated. This combined method provides a new choice for solving three-dimensional fluid flow and heat transfer with high accuracy.

The purpose of this paper is to investigate the influence of the potential of hydrogen (pH) and dissolved oxygen in artificial seawater on the passivation behavior of 316L stainless steel.

The corrosion behavior was studied by using electrochemical measurements such as electrochemical impedance spectroscopy and polarization curve. The passive films were characterized with X-ray photoelectron spectroscopy.

The polarization resistance of the passive film decreases as the pH value drops ascribed to the formation of much more point defects. The donor carrier concentration (ND) in the passive film formed in the deaerated condition is lower than that in aerated conditions. Nevertheless, this phenomenon is the opposite when the pH value is 1 due to the significant decrease of Fe oxides/hydroxides coupled with the stable content of Cr oxides/hydroxides species. In addition, the compositional variation of the passive film also leads to the changes of its semiconductor properties from N-type to bipolar type.

This paper shows the variation of polarization resistance, corrosion potential, passive film composition and semiconductor properties with the pH value and dissolved oxygen. The results can serve as references to the further study on crevice corrosion of 316L in seawater.

This paper aims to deliberate the significant impacts caused by the COVID-19 pandemic on small and medium enterprises (SMEs). It also discusses SMEs’ practical approaches to capitalise on the renewed opportunity in the new normal by expanding their businesses regionally and globally. This paper also discusses the tactical and strategic interventions SMEs need to take to charge forward.

The resource-based view of the firm (Barney, 1991) is used to explain how SMEs develop a sustainable competitive advantage in the new normal. The resource-based view focuses on the link between strategy and firm internal resources. Drawing from the resource-based view of the firm, internal analysis of the resources that are regarded as sources of competitive advantage controlled by the SMEs is imperative in today’s business environment. Based on the resource-based view theory, this paper focuses on reinventing SME’s strategies in the new normal to foster sustainability.

Post-COVID-19 pandemic, SMEs must essentially be dynamic, forward-looking and transformational in capturing the regional and global markets’ opportunities. They need to sharpen their internal competencies and realign their effective business strategy in seizing the vast opportunities in the international markets.

How SMEs respond to COVID-19 has important implications for subsequent performance in the new normal. This study focuses on the different potential SMEs’ reactions to COVID-19 and how their strategy affects SMEs performance and fosters sustainability in the new normal.

The sustainability of SMEs is critical for the nation’s socio-economy. This study offers a holistic view of how SMEs respond to their challenges and help them choose the right business options.

This paper’s contents are solidly based on accumulated evidence, observation and critical arguments on the impacts caused by the COVID-19 pandemic that caused numerous challenges faced by the SMEs, with a specific focus on SMEs operating in Malaysia.

Cryptocurrency, an important application of blockchain technology, has gradually circulated, and its use has become widespread. While cryptocurrency is growing rapidly, potential risks are simultaneously emerging. Users thus may abandon their usage behavior of cryptocurrency, hindering the future development of cryptocurrency. While prior studies focus more on the intention to use cryptocurrency in the pre-adoption phase, less studies pay attention to discontinuance usage intention in the post-adoption phase. To fill this knowledge gap, this stfudy aims to explore factors that cause discontinuance usage intention regarding cryptocurrency.

Based on the net valence framework theoretically grounded on the theory of reason action, a dilemmatic dual-factor model is proposed to figure out cryptocurrency users' discontinuance usage intention from the perceived risk and perceived benefit. This study identifies four potential risks and three potential benefits that affect perceived risk and benefit. The model with nine hypotheses were developed, and research data were collected by a survey method. A total of 343 valid responses were received, and PLS-SEM with SmartPLS was utilized to test the nine hypotheses, with seven hypotheses supported empirically.

Our findings demonstrate that financial, legal and operational risks are critical to increase users' perceived risk, and perceived usefulness and seamless transactions play important roles in enhancing users' perceived benefit. Moreover, while perceived risk can increase users' discontinuance usage intention to cryptocurrency, perceived benefit can mitigate such intention.

This study contributes nascent knowledge to the literature by examining factors that influence discontinuous usage intention in regard to cryptocurrencies, to firms that have issued or attempted to issue cryptocurrencies and to the potential users of cryptocurrencies by adjusting the mode of operation and investment strategies and reducing user costs, achieving a win-win situation for firms and users.

As the application of gamification is gaining great attention and has grown increasingly, thousands of these applications can be easily obtained from mobile phone stores, thus causing intensified competition and discontinuance of use accordingly. Besides, though understanding what factors influence the discontinuance of use of information systems (ISs) is critical for theoretical as well as practical reasons, studies pertaining to the saliency of the final phase, termination of an IS, are still limited. As such, the purpose of this paper is to propose a holistic view to fulfill the above-mentioned research gaps based on the expectation-confirmation model with other salient factors such regret, habit and gamification app values.

The context of a fitness gamification app is investigated. A total of 210 valid responses were received, and structural equation modeling was applied for data analysis.

The findings of this paper are as follows: among all factors influencing discontinuance intention, regret is the strongest, habit is second and gamification is third; among all factors affecting user satisfaction, gamification app value is the strongest, confirmation is second, perceived usefulness (PU) and perceived ease of use are third and regret is the last one; for factors influencing users’ habits, satisfaction is the strongest, following by PU and frequency of prior use; confirmation negatively influences the degree of regret; and confirmation positively influences PU.

This study highlights the important determinants influencing users’ discontinuance intentions in the context of gamification apps by incorporating two overlooked factors, regret and habit. Besides, this study suggests that app designers can not only increase user’s perceived value through external cooperation with other alternatives, but can be through internal enhancement with diverse services development as well.