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This study discusses the tracking trajectory issue of the exoskeleton under the bounded disturbance and designs an useful tracking trajectory control method to solve it. By using the proposed control method, the tracking error can be successfully convergence to the assigned boundary. Meanwhile, the chattering effect caused by the actuators is already reduced, and the tracking performance of the pneumatic artificial muscles (PAMs) elbow exoskeleton is improved effectively.

A prescribed performance sliding mode control method was developed in this study to fulfill the joint position tracking trajectory task on the elbow exoskeleton driven by two PAMs. In terms of the control structure, a dynamic model was built by conforming to the adaptive law to compensate for the time variety and uncertainty exhibited by the system. Subsequently, a super-twisting algorithm-based second-order sliding mode control method was subjected to the exoskeleton under the boundedness of external disturbance. Moreover, the prescribed performance control method exhibits a smooth prescribed function with an error transformation function to ensure the tracking error can be finally convergent to the pre-designed requirement.

From the theoretical perspective, the stability of the control method was verified through Lyapunov synthesis. On that basis, the tracking performance of the proposed control method was confirmed through the simulation and the manikin model experiment.

As revealed by the results of this study, the proposed control method sufficiently applies to the PAMs elbow exoskeleton for tracking trajectory, which means it has potential application in the actual robot-assisted passive rehabilitation tasks.

China’s workforce is currently experiencing increased career-related stress. Employee stock ownership plans (ESOPs) may be used to help employees overcome these challenges. Little is known about how ESOPs affect employee career development. The purpose of this paper is to investigate the relationship between ESOPs and employee career sustainability and provide guidance for corporate management.

The authors employed a multiple linear regression model using a sample of 614 companies that implemented ESOPs between July 2014 and September 2017.

Employees’ career development benefited when ESOP funds originated from employee compensation and self-raised funds, and when the plan’s stock came from a source other than the secondary market. Career development also improved when employees and senior executives held a higher proportion of a firm’s total shares. In addition, the benefits to employee career development were greater in manufacturing enterprises, non-state-owned enterprises, and in Southern China.

This study combined individual and organization research using person–organization fit theory and demonstrated that well-designed ESOPs are beneficial for career stability and sustainability. This work was based on data from Chinese companies; future studies could usefully investigate the effects of ESOPs in other countries and their particular impact in technology-intensive industries.

Decision makers in firms or government can use ESOPs to address employees’ career-related stress and challenges, especially during industry transformation.

The paper fills a gap in ESOPs research by showing the positive effects of ESOPs on career development.

High-quality development of marine economy is a new concept put forward in response to the current national strategy in China. The purpose of this paper is to thoroughly understand the connotation and significance of high-quality development of marine economy through literature review, and further analyze the prospects for further research.

The authors first use the information visualization technology of CiteSpace to present a systematic review of the published literature from 2010 to 2019. Then, the authors analyze the researches on high-quality development of marine economy in terms of connotation, evaluation dimension, development path and guarantee mechanism.

Analysis results show that there is still insufficient understanding of the differences and links between the high-quality development of marine economy and the construction of marine power, intelligent ocean and transparent ocean.

Based on a thorough understanding of the subject, this paper puts forward the direction of further research on evaluation index system, path design scheme and policy system construction for high-quality development of marine economy.

The purpose of this paper is to develop the efficiency of styrene-acrylate (SA) emulsions for polymer cement waterproof coatings with improved bacteria resistance and mechanical properties.

For effective bacteria resistance and excellent mechanical properties, various concentrations of methacryloxyethylhexadecyl dimethylammonium bromide (MHDB) were synthesised and incorporated into SA emulsions. The properties of SA emulsions modified with MHDB were characterised and compared with those of unmodified ones according to the formulations of polymer cement waterproof coatings.

The SA emulsions modified with MHDB exhibited significant enhancement of bacteria resistance and mechanical properties over the unmodified ones. The positive quaternary nitrogen and long-chain alkyl groups of MHDB in SA emulsions could attract phospholipid head groups of bacterial and insert them into the cell wall, which results in biomass leak and bactericidal effect. Moreover, MHDB as a softened monomer was beneficial to the synthesis of SA copolymer with low glass-transition temperature (T_g), then the copolymer and cement would form a more compact film which was the main reason for the enhancement of mechanical properties.

The modifier MHDB was synthesised from diethylaminoethyl methacrylate (DEAM) and 1-bromohexadecane. Besides, the congeners of MHDB could be synthesised from DEAM and 1-bromododecane, 1-tetradecyl dromide, 1-octadecyl bromide, etc. In addition, the efficiency of other modifications into SA emulsions for antibacterial polymer cement waterproof coatings could be studied as well.

The method provided a practical solution for the improvement of water-based antibacterial acrylate polymer cement waterproof coatings.

The method for enhancing bacteria resistance and mechanical properties of the waterproof coating was novel and valuable.

This paper aims to propose a generalized finite element technique that can accurately approximate the solution of the flexural-shear cantilever model of wall-frame structures proposed by Heidebrecht and Stafford Smith.

This approach adopts scaled monomials as enrichment functions, and they are highly effective in accurately capturing the solution of the problem, as it consists of smooth functions such as polynomials, hyperbolic and trigonometric functions. Several numerical experiments are performed on the static and modal analyses of the flexural-shear cantilever wall-frame structures using the proposed generalized finite element method (GFEM), and their accuracies are compared with those obtained using the standard finite element method.

The proposed GFEM is able to achieve theoretical convergence rates of the static and modal analyses, which are, in principle, identical to those of the standard FEM, for various polynomial orders of its shape functions such as quadratic, cubic and quartic orders. The proposed GFEM with quartic enrichment functions can provide more accurate solutions than the standard FEM, and thus can be effectively used at the initial design stage of high-rise wall-frame structures.

This work is the first paper where the GFEM is applied to the analysis of high-rise wall-frame structures, and the developed technique can be used as a good analysis tool at the initial design stage.

The purpose of this paper is to enable autonomous door-opening with unknown geometrical constraints. Door-opening is a common action needed for mobile manipulators to perform rescue operation. However, it remains difficult for them to handle it in real rescue environments. The major difficulties of rescue manipulation involve contradiction between unknown geometrical constraints and limited sensors because of extreme physical constraints.

A method for estimating the unknown door geometrical parameters using coordinate transformation of the end-effector with visual teleoperation assists is proposed. A trajectory planning algorithm is developed using geometrical parameters from the proposed method.

The relevant experiments are also conducted using a manipulator suited to extreme physical constraints to open a real door with a locked latch and unknown geometrical parameters, which demonstrates the validity and efficiency of the proposed approach.

This is a novel method for estimating the unknown door geometrical parameters with coordinate transformation of the end-effector through visual teleoperation assists.

Green innovation strategy is not only a new idea to achieve green development but also the inevitable choice for enterprises to upgrade. At present, the research on the driving forces of green innovation strategy mainly focus on direct impact of single factor, lacking the overall consideration of internal and external environment. At the same time, research on the contingency effect of top management’s environmental awareness is scarce. This paper aims to explore how external environment pressures (policy pressures and market pressures) and internal environment driving force (innovation resources and innovation capability) make enterprises to choose green innovation strategy with moderating effect of top management’s environmental awareness.

Based on the sample of 216 enterprises, this paper explores the relationship between policy pressure, market pressure, innovation resources, innovation capability and the green innovation strategy with moderating effect of top management’s environmental awareness from inside and outside driving angle.

The results of the hierarchical regression model show, first, the driving effect of factors in the external environment. The coercive policy has an inverted U-shaped impact on the green innovation strategy. The incentive policy and the market pressure both have a significant positive impact on the green innovation strategy. Second, the driving effect of factors in the internal environment. The innovation capability has a significant positive impact on the green innovation strategy. The innovation resources have no significant impact on the green innovation strategy. Third, the moderating effect of top management’s environmental awareness. The relationship between the green innovation strategy and the coercive policy is stronger when the top management’s environmental awareness higher. The relationship between the green innovation strategy and the market pressure is stronger when the top management’s environmental awareness higher. The relationship between the green innovation strategy and the innovation resources is stronger when the top management’s environmental awareness higher. Otherwise, the relationship between the green innovation strategy and the innovation capability is weaker when the top management’s environmental awareness higher. And there is no significant change about the relationship between the green innovation strategy and the incentive policy when the top management’s environmental awareness higher.

First, the authors have promoted the integrated research on the drivers of the enterprise’s green innovation strategy. From the perspective of internal and external environment driving forces, this paper analyzes the key factors influencing the decision-making of the green innovation strategy. Second, the study has contributed to the strategic choice theory. This paper studies the driving mechanism of the green innovation strategy from a new perspective of the strategic choice theory.

This paper aims to mainly discuss how to suppress the disturbances accurately and effectively in the wind energy conversion system (WECS) of the direct drive surface mount permanent magnet synchronous generator (SPMSG).

The disturbances in wind energy conversion system have seriously negative influence on the maximum power tracking performance. Therefore, a model predictive control (MPC) method of model compensation active disturbance rejection control (ADRC) strategy in parallel connection is designed, which optimizes the speed tracking performance compared with the existing control strategy of MPC and ADRC in series connection. Based on the traditional ADRC, a multi parameter model compensation ADRC strategy is added to better estimate the disturbances. At the same time, a torque feedback strategy is added to compensate the disturbances caused by load torque and further optimize the speed loop tracking performance.

The simulation results show that the designed control method has advantages than the traditional control method in compensating the disturbances and tracking the maximum power more effectively.

The simulation results show that the designed control method is superior to the traditional proportional control method, which can better compensate the internal and external disturbances and track the maximum power more effectively.

This paper aims to provide new perspectives on the integration of East Asian stock markets and the dynamic volatility transmission to the Bitcoin market utilising daily data from 2014 to 2020.

The authors undertake comprehensive analyses of the dependency dynamics, systemic risk and volatility spillover between major East Asian stock and Bitcoin markets. The authors employ a vine-copula-CoVaR framework and a VAR-BEKK-GARCH method with a Wald test.

(a) With exception of KS11 and N225; HSI and SSE; HSI and KS11, which have moderate dependence, dependencies among other markets are low. In terms of tail risk, the upper tail risk is more significant in capturing strong common variation. (b) Two-way and asymmetric risk spillover effects exist in all markets. The Hong Kong and Japanese stock markets have significant risk spillovers to other markets, and quite notably, the Chinese stock market is the largest recipient of systemic risk. However, the authors observe a more significant risk spillover from the Chinese stock market to the Bitcoin market. (c) The VAR-BEKK-GARCH results confirm that the Korean market is a significant emitter of volatility spillovers. The Bitcoin market does provide diversification benefits. Interestingly, the Chinese stock market has an intriguing relationship with Bitcoin. (d) An increase in spillovers in East Asia boosts spillovers to Bitcoin, but there is no intuitive effect of Bitcoin spillovers on East Asian spillovers.

For the first time, the authors examine the dynamic linkage between Bitcoin and the major East Asian stock markets.

The purpose of this paper is to use the wavelet neural network and genetic algorithm to study the effects of polyalphaolefin, TMP108 and OCP0016 on the kinematic viscosity, viscosity index and pour point of lubricating oil.

Wavelet neural network is used to train the known samples, test the unknown samples and compare the obtained results with those obtained with a traditional empirical formula.

It is found that the wavelet neural network prediction value is closer to the experimental value than the traditional empirical formula calculation value.

The results show that the wavelet neural network can be used to study the physical and chemical indexes of lubricating oil.