1,530 research outputs found
The effect of surface treatment on composite interface, tensile properties and water absorption of suger palm fiber/polypropylene composites
The rising concern towards environmental issues besides the requirement for more flexible polymer-based material has led to increasing of interest in studying about green composite. Sugar palm fiber (SPF) is a versatile fiber plant employed with wide range of application such as in automotive, packaging and buildings construction. This research was aimed to study the effect of surface treatment on composite interface, tensile properties and water absorption of sugar palm fiber/polypropylene (SPFPP) composite by using different surface treatments such as silane (Si), atmospheric glow discharge plasma (Agd) and maleic anhydride (Ma). Silane treatment was carried out by using immersion method, the Agd plasma was conducted using polymerization and lastly polypropylene grafted maleic anhydride by using melting approach. The SPFPP composite was prepared by using injection moulding with fiber content varied from 10-30wt%. The effect of interface enhancement on morphology, mechanical properties and water uptakes of SPFPP composites were then investigated by using FfIR, FESEM, tensile test and water absorption test. Overall, the outcome shows that aJl types of surface treatments had improved the interface of SPFPP composite, thus improving its tensile properties compared to the benchmark untreated SPFPP (UtSPFPP) composites and polypropylene. The 30wt% Ma-SPFPP composite shows the highest improvement in tensile properties with 58% and 27% increase in the respective Young's Modulus and tensile strength value compared to Ut-SPFPP composite, while 10wt% Ma-SPFPP composite shows the smallest reduction in elongation compared to Neat PP. On the other hand, the 30wt% Si-SPFPP composite shows the lowest water absorption with 20% reduction respective to Ut-SPFPP composite. In conclusion, the surface treatments have proven succesfull in enhancing the natural fiber-polymer interface and improve the tensile properties of SPFPP composite with Ma-SPFPP shows the highest improvement, foJlowed by Agd-SPFPP and Si-SPFPP composites
The effect of surface treatment on composite interface, tensile properties and water absorption of suger palm fiber/polypropylene composites
The rising concern towards environmental issues besides the requirement for more flexible polymer-based material has led to increasing of interest in studying about green composite. Sugar palm fiber (SPF) is a versatile fiber plant employed with wide range of application such as in automotive, packaging and buildings construction. This research was aimed to study the effect of surface treatment on composite interface, tensile properties and water absorption of sugar palm fiber/polypropylene (SPFPP) composite by using different surface treatments such as silane (Si), atmospheric glow discharge plasma (Agd) and maleic anhydride (Ma). Silane treatment was carried out by using immersion method, the Agd plasma was conducted using polymerization and lastly polypropylene grafted maleic anhydride by using melting approach. The SPFPP composite was prepared by using injection moulding with fiber content varied from 10-30wt%. The effect of interface enhancement on morphology, mechanical properties and water uptakes of SPFPP composites were then investigated by using FfIR, FESEM, tensile test and water absorption test. Overall, the outcome shows that aJl types of surface treatments had improved the interface of SPFPP composite, thus improving its tensile properties compared to the benchmark untreated SPFPP (UtSPFPP) composites and polypropylene. The 30wt% Ma-SPFPP composite shows the highest improvement in tensile properties with 58% and 27% increase in the respective Young's Modulus and tensile strength value compared to Ut-SPFPP composite, while 10wt% Ma-SPFPP composite shows the smallest reduction in elongation compared to Neat PP. On the other hand, the 30wt% Si-SPFPP composite shows the lowest water absorption with 20% reduction respective to Ut-SPFPP composite. In conclusion, the surface treatments have proven succesfull in enhancing the natural fiber-polymer interface and improve the tensile properties of SPFPP composite with Ma-SPFPP shows the highest improvement, foJlowed by Agd-SPFPP and Si-SPFPP composites
Nonlinear H ∞ optimal control scheme for an underwater vehicle with regional function formulation
A conventional region control technique cannot meet the demands for an accurate tracking performance in view of its inability to accommodate highly nonlinear system dynamics, imprecise hydrodynamic coefficients, and external disturbances. In this paper, a robust technique is presented for an Autonomous Underwater Vehicle (AUV) with region tracking function. Within this control scheme, nonlinear H∞ and region based control schemes are used. A Lyapunov-like function is presented for stability analysis of the proposed control law. Numerical simulations are presented to demonstrate the performance of the proposed tracking control of the AUV. It is shown that the proposed control law is robust against parameter uncertainties, external disturbances, and nonlinearities and it leads to uniform ultimate boundedness of the region tracking error
The mediating effect of the employee commitment on the relationship between recruitment process and organizational performance in UAE organisations
The UAE employment market has a higher rate of turnover; besides some studies revealed that the recruitment process is slow and weakly prepared. The high rate of turnover can negatively affect the organizations’ performance in the UAE; therefore, revealing the causes can contribute to overcoming the problem and avoiding the weak recruitment practices, which will improve the performance and strengthen the UAE economy. Therefore, this study is an empirical examination by surveying the 34 companies of the Fujairah National Group (FNG) to examine the mediating role of employee commitment on the relationship between the recruitment process and organizational performance. Social exchange theory (SET) assumes that encouragement activities undertaken between an organization and its employees generate organizational commitment. The proposed conceptual model has the recruitment process as the independent variables, employees’ commitment as the mediating variable, and organizational performance as the dependent variables. The quantitative research approach has been used, and the study applied a cross-sectional survey method; and the unit of analysis of this study is the companies of the Fujairah National Group (FNG), which includes 34 working companies. The population of the study is the employees who involve in the recruitment and selection process in all companies. This includes human resource employees, besides supervisors, managers, and senior managers in all departments, and the estimated population is 1075. The technique used for this study is quota sampling because the population is classified into nine different quotas. The face-to-face direct collection is applied by visiting the target companies and asks the available participants on the chosen companies to fill up a printed copy of the questionnaire. The final valid data set has 366 respondents. The proposed model of this particular study has four regression models, in which 15 relationships are tested by using the significance level value with the path coefficient analysis. Overall, 12 hypotheses are accepted, and three are rejected. The three rejected hypotheses are related to the variable job analysis. Future work is advised to explore why the job analysis is not an antecedent of organizational performance in the UAE
The causal effects of baldrige excellence framework and lean in the Malaysian electrical and electronics manufacturing industry
The aim of this research is to construct a comprehensive performance measurement
model using the 2019-2020 Baldrige excellence framework criteria that examines the
Malaysian Electrical and Electronics (E&E) industry. The criteria in this framework
are leadership, strategy, customers, measurement, analysis and knowledge
management (MAKM), workforce, operations and results. The previous study in the
context of Business Excellence (BE) was focused more on aspects of quality
management, organisational context, company performance but it often excluded the
deployment of continuous improvement tools. Based on the research gaps, this
research would like to assert the potency of the leadership of Baldrige setting as a
driver that contributes positively to the Lean practice and BE elements of the company.
The present study also integrating the Lean practices with Baldrige excellence
framework to predict operations and the results of company performance. This
integration may bridge the literature gap whereby the past studies have been conducted
Lean, BE and operational performance individually. BE outcomes were achieved in
both financial and non-financial performance metrics and the BE Models, Leadership
theory and Lean model also guided the theoretical framework. The study also
employed stratified random sampling from four sub-sectors of the E&E industry. A
total of 156 respondents responded to the survey questionnaire from 488 companies
that were sampled. This equates to a 32.0% response rate. The collected data were
analysed using SPSS 23.0 and SmartPLS 3.3.2. The analysis found significant and
positive relationships between strategy, operations and Lean practices on the
achievement of BE. The results of this study promoted a better understanding of the
BE in the E&E industry and its implications for activities concerning Lean practices,
thus contributing to a wider body of knowledge. The survey instrument which
combining Lean and BE was validated in this research can be reused in the other
manufacturing sector studies on the initiatives deployment to predict business
performance. Therefore, it contributes to the methodology perspective. The findings
v
of the research can become a reference, which can help the company focus on the right
things in promoting excellence in their organisation and then pursuing BE Awards.
Practical adoption of leadership and Lean practices may improve infrastructural
decision areas of manufacturing strategy and the outcomes of this study may also be
beneficial to policy makers of the Malaysian government and agencies such as
Malaysia Productivity Corporation (MPC) and Ministry of International Trade and
Industry (MITI). The scope of this study was limited because it was restricted to the
Malaysia’s E&E industry only. As a suggestion, future research could be conducted
by involving other industries
Task-space dynamic control of underwater robots
This thesis is concerned with the control aspects for underwater tasks performed by
marine robots. The mathematical models of an underwater vehicle and an underwater
vehicle with an onboard manipulator are discussed together with their associated
properties.
The task-space regulation problem for an underwater vehicle is addressed where the
desired target is commonly specified as a point. A new control technique is proposed
where the multiple targets are defined as sub-regions. A fuzzy technique is used to
handle these multiple sub-region criteria effectively. Due to the unknown gravitational
and buoyancy forces, an adaptive term is adopted in the proposed controller.
An extension to a region boundary-based control law is then proposed for an underwater
vehicle to illustrate the flexibility of the region reaching concept. In this novel
controller, a desired target is defined as a boundary instead of a point or region. For a
mapping of the uncertain restoring forces, a least-squares estimation algorithm and the
inverse Jacobian matrix are utilised in the adaptive control law.
To realise a new tracking control concept for a kinematically redundant robot, subregion
tracking control schemes with a sub-tasks objective are developed for a UVMS.
In this concept, the desired objective is specified as a moving sub-region instead of a
trajectory. In addition, due to the system being kinematically redundant, the controller
also enables the use of self-motion of the system to perform sub-tasks (drag
minimisation, obstacle avoidance, manipulability and avoidance of mechanical joint
limits)
Task priority control of underwater intervention systems: Theory and applications
This paper presents a unifying task priority control architecture for underwater vehicle manipulator systems. The proposed control framework can be applied to different operative scenarios such as waypoint navigation, assisted teleoperation, interaction, landing and grasping. This work extends the results of the TRIDENT and MARIS projects, which were limited to the execution of grasping actions, to other applications taken from the DexROV and ROBUST projects. In particular, simulation results show how the control framework can be used, for example, for pipeline inspection scenarios and deep sea mining exploration
A Frequency-Limited Adaptive Controller for Underwater Vehicle-Manipulator Systems under Large Wave Disturbances
© 2018 IEEE. Standard adaptive control approaches may not be able to sufficiently stabilize underwater vehicle-manipulator systems (UVMSs) when wave disturbances are large, leading to high-frequency oscillations of large amplitude in its dynamic model parameters. Such parameters bring about undesired oscillations in the vehicle body control and state. This paper extends a frequency-limited adaptive control approach to the vehicle body. An auxiliary model is obtained from the approximated model through a low-pass filter and is used to reduce the problematic oscillations. The resultant stable vehicle body is a necessary premise for successful end-effector tracking. In addition, this paper proposes a sufficient condition of the control gains for guaranteed asymptotical stability of the controlled robotic system. Numerical simulations have demonstrated the effectiveness of the presented approach, compared to the standard adaptive control
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