Bo Li, Bo Yuan, Shuai Tang, Yuwen Mao, Dongmei Zhang, Changyun Huang and Bilian Tan
This paper aims to investigate weight-climbing assistance strategy for the biomechanical design of passive knee-assisting exoskeleton (PKAExo) and evaluate a designed PKAExo which…
Abstract
Purpose
This paper aims to investigate weight-climbing assistance strategy for the biomechanical design of passive knee-assisting exoskeleton (PKAExo) and evaluate a designed PKAExo which stores energy when the knee joint flexes and releases the energy to assist ascending when the knee joint extends.
Design/methodology/approach
The authors constructed theoretic modeling of human weight-climbing to analyze characteristics of knee angle and moment. They then conducted camera-based movement analysis, muscle strength and endurance tests and surface electromyography (sEMG) measures to verify the relationship of knee angle and moment with both stair height and load weight. Afterwards, the authors proposed an assistant strategy for passive knee assistance, then gave out designed PKAExo and conducted mechanical experiment to test the knee-assisting torque. Finally, the authors conducted comparison experiment based on measuring the sEMG signals of knee extensor to verify the assistance effect of the PKAExo for weight-climbing.
Findings
The knee extensor produces the maximum force during weight-climbing, and the muscle force provided by knee extensor has significant increasing rate along with the stair height. Thus, the assistance torque of PKAExo is designed to increase nonlinearly along with increasing knee angle. It stores energy when knee flexes and assists when knee extends. Both the mechanical experiment and comparison experiment have demonstrated that the PKAExo is able to provide nonlinear assistance torque for weight-climbing, thus decreasing the average maximum load of knee extensor by about 21 per cent, reducing muscle fatigue and enhancing wearer’s weight-climbing ability.
Originality/value
The authors construct theoretic maximum force model produced by knee extensor for weight-climbing in static situation and conduct a series of experiments to verify and revise the model, which is the fundamental reference for knee-assisting mechanism designed for weight-climbing. The authors have also provided and validated an assistant strategy and the mechanism based on the biomechanical analysis, which aims to translate wearer’s energy-providing mode form high load to mid-low load by storing energy when knee flexes and assisting when knee extends. The PKAExo decreases the maximum load of knee extensor, reduces muscle fatigue and helps people to easily climb with load.
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Keywords
Zhiqiang Ye, Zhi Zhang and Songlian Tang
The purpose of this paper is to test the relationship between stock dividends policy and liquidity of ex ante announcement to improve the traditional stock dividends liquidity…
Abstract
Purpose
The purpose of this paper is to test the relationship between stock dividends policy and liquidity of ex ante announcement to improve the traditional stock dividends liquidity hypothesis.
Design/methodology/approach
The authors examine a sample of 2,088 which matching stocks between having stock dividends policy and having no dividends policy during 1999-2012 in Chinese listed firms. Using the multiple liner regression, the authors empirically tests the relationship between the possibility, payout ratio and timing choice of stock dividends and the liquidity of ex ante announcement.
Findings
The authors find that the possibility of stock dividends policy has negative relationship with liquidity, and the relationship of stock dividends and liquidity of ex ante announcement is influenced by the time choice of stock dividends.
Originality/value
This paper study the reason of stock dividends policy from the perspective of liquidity and improve the traditional stock dividends liquidity hypothesis.
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This study investigates whether corporate executives, who are university alumni, influence each other's firm corporate social responsibility (CSR) performance.
Abstract
Purpose
This study investigates whether corporate executives, who are university alumni, influence each other's firm corporate social responsibility (CSR) performance.
Design/methodology/approach
Drawing on social network theory, the authors hypothesise that a firm's CSR performance is positively associated with its peer firms' average CSR performance when the executives of the firm and its peer firms are university alumni. The study employs data from 1,685 listed firms and 4,906 executives who graduated from 585 different universities in China and runs multivariate regressions.
Findings
The results reveal a sizeable university peer influence on CSR performance. Such influence is even stronger for executives who graduated from elite universities (e.g. 985 or 211 universities), and universities or programmes that provide more opportunities for alumni reunions or networking (e.g. MBAs/EMBAs). Executives who are more influential in making firm decisions (e.g. CEOs/CFOs), as well as firms that are more likely to mimic the behaviour of others, also show higher degrees of university peer influence.
Practical implications
The results highlight the role of education in ethical decision-making.
Originality/value
This study documents evidence on a new determinant of firm CSR performance. The study sheds light on the impact of non-institutionalised personal ties, for example, university alumni networks, on CSR performance.
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This paper aims to investigate the feasibility of adding macro-textures to triangle meshes for additive manufacturing (AM) focusing on possible time and quality issues in both…
Abstract
Purpose
This paper aims to investigate the feasibility of adding macro-textures to triangle meshes for additive manufacturing (AM) focusing on possible time and quality issues in both software processing and part fabrication.
Design/methodology/approach
A demonstrative software tool was developed to apply user-selected textures to existing meshes. The computational procedure is a three-dimensional extension of the solid texturing method used in computer graphics. The tool was tested for speed and quality of results, considering also the pre- and post-processing operations required. Some textured meshes were printed by different processes to test build speed and quality.
Findings
The tool can handle models with realistic complexity in acceptable computation times. Parts are built without difficulties or extra-costs achieving a good aesthetic yield of the texture.
Research limitations/implications
The tool cannot reproduce sample patterns but requires the development of a generation algorithm for different type of textures. Mesh processing operations may take a long time when very fine textures are added to large parts.
Practical implications
Direct texturing can help obtain parts with aesthetic or functional textures without the need for surface post-treatments, which can be especially difficult and expensive for plastic parts.
Originality/value
The proposed method improves the uniformity and consistency of textures compared to existing approaches, and can support future systematic studies on the detail resolution of AM processes.