Control design of a de-weighting upper-limb exoskeleton: extended-based fuzzy

One of the most common issues to human is fatigue. A technology known as exoskeleton has been identified as one of the solutions to address this issue. However, there are two issues that need to be solved. One of them is the control approach. Hence, the main aim of this work, is to investigate the control design for upper-limb exoskeleton. An extended based fuzzy control is proposed to observe the effectiveness of the exoskeleton in dealing with human with different strength. Three conditions of human strength were applied. PID was used for a comparison purpose. It is shown that with the proposed control approach, the exoskeleton can assist human to achieve the desired trajectory accurately with a minimal amount of torque required

Control design of a de-weighting upper limb exoskeleton

One of the most common problems in humans is a muscle fatigue. Exoskeletons are known as one of the solution to deal with human muscle fatigue. However, several issues related to the development of exoskeletons for such a case have been identified. One of these is the control mechanism. Thus, the objective of this paper is to investigate development of a control strategy for the upper-limb exoskeleton. In this paper, a new control mechanism for an upper-limb exoskeleton is proposed. A fuzzy-based PD controller and PID are used in the proposed control mechanism, and a comparative assessment of the performance of both controllers is made. The results show that the control mechanism with fuzzy-based PD controller performs better than the PID controller in terms of trajectory tracking accuracy and control torque analysis

Fatigue behavior of kenaf fibre reinforced epoxy composites

Towards green material, fatigue life of epoxy and its unidirectional kenaf fibre reinforced epoxy composites were investigated. These specimens were hand lay-out made. The specimens were cycled to tension-tension fatigue loading at stress ratio of 0.5 and 5 Hz of frequency to determine the fatigue life and its life characteristic at given 5 stress levels. Fibre content ratios were found to affect fatigue life strongly on the low cycle fatigue regime as illustrated with stress level versus cycles to failure. It is found that kenaf fibre reinforced epoxy composites with higher fibre content posses higher load carrying capacity and degradation rates. The existing models developed by Mandell, Manson-Coffin and Hai-Tang were adopted to predict the fatigue life. Some of the models show minor similarities with the experimental data, but not universally applicable to predict the fatigue life when it comes with various amount of fibre volume

Impact of work values in promoting organizational citizenship behavior among academicians: The mediating roles of job satisfaction

Organizational citizenship behavior (OCB) has become an increasingly important aspect in improving organizational performance, employees’ work attitude and behavior. However, research that focuses on work values, work attitude and OCB is still limited specifically in higher education institution (HEI) setting. Higher education workers particularly academicians at present portray a high individualistic culture with lesser OCB due to a great pressure and demand existed in the setting. This paper aims to investigate how certain work values promote academicians’ organizational citizenship behavior and highlights the role of job satisfaction as a mediator between the aforementioned relationships. Work values in this study were looked at two aspects of terminal and instrumental. Meanwhile, OCB was looked at into two aspects namely OCB towards individual (OCBI) and organization (OCBO). This study population involved 460 academics retrieved from both private and public HEIs which were used a structural modelling approach in testing the hypotheses. The findings revealed that work values significantly predicted OCB. Both terminal and instrumental work values have a significant influence on academics’ degree of OCB. Job satisfaction on the other hand mediates the relationship between terminal work values and OCB. The implication of this paper related to theoretical, empirical and policy advancement in relation to OCB at work was included

Impact of Work Values in Promoting organizational citizenship behavior among academicians: The mediating roles of job satisfaction

Organizational citizenship behavior (OCB) has become an increasingly important aspect in improving organizational performance, employees' work attitude and behavior. However, research that focuses on work values, work attitude and OCB is still limited specifically in higher education institution (HEI) setting. Higher education workers particularly academicians at present portray a high individualistic culture with lesser OCB due to a great pressure and demand existed in the setting. This paper aims to investigate how certain work values promote academicians' organizational citizenship behavior and highlights the role of job satisfaction as a mediator between the aforementioned relationships. Work values in this study were looked at two aspects of terminal and instrumental. Meanwhile, OCB was looked at into two aspects namely OCB towards individual (OCBI) and organization (OCBO). This study population involved 460 academics retrieved from both private and public HEIs which were used a structural modelling approach in testing the hypotheses. The findings revealed that work values significantly predicted OCB. Both terminal and instrumental work values have a significant influence on academics' degree of OCB. Job satisfaction on the other hand mediates the relationship between terminal work values and OCB. The implication of this paper related to theoretical, empirical and policy advancement in relation to OCB at work was included

A DYNAMIC SIR MODEL FOR THE SPREAD OF NOVEL CORONAVIRUS DISEASE 2019 (COVID-19) IN MALAYSIA

The emergence of the first coronavirus disease 2019 (COVID-19) case in Malaysia has increased the number of infected cases. Hence, this study proposes a Susceptible-Infected-Recovery (SIR) epidemiological model of the COVID-19 epidemic to portray the outbreak's situation. The SIR model is numerically solved using the Fourth-order Runge-Kutta (RK4) method in Matlab®. The Euler method verifies that the graphical results of the SIR model are reliable and valid. In addition, this study analyses the stability of disease-free and endemic equilibriums of the SIR model by the Jacobian matrix. The results show the outbreak for phase 1 occurs in the first 100 days of the phase due to the increased infected cases in early March 2020. As for phase 2, the increases of infected cases in wave 2 make the outbreak occur throughout phase 2, with R0 being higher than phase 1. The infected population for phase 3 shows asymptotic behavior even though the infection rate increases, but the recovery rate is much higher than in phase 2. The local stability of the endemic equilibrium of all phases exists since the value of R0 is more than one. The system is locally asymptotic stable for all three phases since the obtained eigenvalues are real and negative

Spread enhancement for firefly algorithm with application to control mechanism of exoskeleton system

Firefly algorithm (FA) is a swarm intelligence based algorithm for global optimization and has widely been used in solving problems in many areas. The FA is good at exploring the search space and locating the global optimum, but it always gets trapped at local optimum especially in case of high dimensional problems. In order to overcome such drawbacks of FA, this paper proposes a modified variant of FA, referred to as spread enhancement strategy for firefly algorithm (SE-FA), by devising a nonlinear adaptive spread mechanism for the control parameters of the algorithm. The performance of the proposed algorithm is compared with the original FA and one variant of FA on six benchmark functions. Experimental and statistical results of the approach show better solutions in terms of reliability and convergence speed than the original FA especially in the case of high-dimensional problems. The algorithms are further tested with control of dynamic systems. The systems considered comprise assistive exoskeletons mechanism for upper and lower extremities. The performance results are evaluated in comparison to the original firefly and invasive weed algorithms. It is demonstrated that the proposed approaches are superior over the individual algorithms in terms of efficiency, convergence speed and quality of the optimal solution achieved

Characteristics of human spermatozoa harvested in culture media with and without serum proteins

This study was aimed to determine the efficiency of synthetic protein-free media in spermatozoa washing, preparation and retention of the activity of washed spermatozoa over short periods in vitro. Normozoospermic semen samples (n = 71) were equally apportioned and washed using synthetic protein-free medium (PFM), minimum essential medium + HSA (MEM) or commercial protein-containing medium (CPC). Washed spermatozoa were cultured in vitro using PFM, MEM or CPC media and held for 24 hrs at 4°C, 15°C, 22°C or 37°C. Spermatozoa activity was evaluated at 0 hr, 4 to 7 hrs and 24 hrs post-wash. The effects of PFM on spermatozoa motility, vitality, membrane integrity and DNA fragmentation level were not significantly different from that of MEM and CPC media at 0 hr, 4 to 7 hrs and 24 hrs post-wash in vitro. Synthetic PFM, MEM and CPC retained spermatozoa activity highest when specimen were held at 22°C and it was significantly higher (p 0.05) were noted in spermatozoa DNA fragmentation (SDF) levels when specimen were held at 22°C or 37°C at 4 to 7 hrs and also after 24 hrs post-wash in vitro in all media. The use of synthetic PFM as an alternative to the commercial protein-containing media in human spermatozoa washing and preparation procedure for an efficient and safer (Assisted Reproduction Technology) ART outcome. Spermatozoa activity can be successfully retained at room temperature post-wash over short periods; spermatozoa may lose viability rapidly if held for long hours at 37°C in all media

Computer skills for empowering orphans and vulnerable children (OVC) in Malaysia

Orphans and vulnerable children (OVC) can be defined as children who lost their parents due to AIDS. OVC may lose interest in school due to poverty, emotional and parental sickness or death. These reasons may lead OVC to have low self-esteem and lack of computer skills. Therefore, it is significant for the community to provide educational support for OVC. Computer skill can be defined as a life skill in today’s world. However, OVC have limited access to learn computer skills due to hardship in life. University Putra Malaysia (UPM) took up the initiative to transfer knowledge of computer skills program to OVC. This article evaluates the impact of OVC in Malaysia to learn computer skills. Finding shows 50% of the participants responded to have an interest in and high motivation to learn computer skills. It proves that university community can have the ability to provide educational support to OVC

Habitual dietary fibre intake and lifestyle characteristics in relation to functional constipation among adults in Malaysia

The World Health Organization (WHO) and the Food and Agriculture Organization (FAO) recommend consuming at least 25 g of dietary fibre daily. Adults with low fibre intake have an increased constipation risk. However, little research has been done on the habitual dietary fibre intake and lifestyle characteristics of functional constipation in Malaysian adults. Thus, the purpose of this study is to determine the dietary fibre intake, lifestyle characteristics, and functional constipation of adults in Malaysia, as well as the association between habitual dietary fibre intake, lifestyle characteristics, and functional constipation. About 318 adults between the ages of 18 and 59 participated and were asked to complete an online questionnaire consisting of three major parts. The components are as follows: i) the assessment of dietary fibre intake by using a semi-quantitative dietary fibre food frequency questionnaire; ii) the assessment of lifestyle factors; and iii) the determination of functional constipation via the Wexner Constipation Scoring System. SPSS 25 was used to analyse the data at a significance level of 0.05. The results indicated that the majority of adults consumed dietary fibre in amounts less than 25 g per day (84.6%). About 97.5% of adults have a healthy lifestyle, and only 2.8% of adults in this study faced constipation. There was no significant association between habitual dietary fibre intake and lifestyle characteristics (p=0.614) or between habitual dietary fibre intake and functional constipation among adults in Malaysia (p=0.147). Continued efforts are needed to increase dietary fibre intake among the adult population