Dual-stage gain-clamped erbium-doped fiber amplifier with fiber Bragg grating

We demonstrate a dual-stage gain-clamped erbiumdoped fiber amplifier. The first-stage amplifier consists of a short length of erbium-doped fiber to produce low noise figures. The second-stage is constructed from a counter-propagating ringlaser, in which the signals and the lasing wavelength propagate in the opposite direction. The lasing wavelength is selected via a reflective-type of fiber Bragg grating. The gain-clamping mechanism can be adjusted by either changing the fiber Bragg grating reflectivity or center wavelength. The noise figure penalty is about 1.5 dB for the gain-clamping value from 11 dB to 20.5 dB. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA

OSNR variation of multiple laser lines in Brillouin-Raman fiber laser

We report experimental results demonstrating the variation of optical signal-to-noise ratio (OSNR) of laser lines in Brillouin-Raman fiber laser against Raman pump power (RPP) variation. The reduction of OSNR is attributed to the spectral broadening of laser lines depending on the RPP. The spectral broadening is owing to the effect of the interaction between laser lines and turbulent waves (nonlinear interaction between longitudinal cavity modes).In our experiment, the worst OSNR is obtained at 650 mW RPP as a result of maximum spectral broadening when the Brillouin pump wavelength is fixed at 1555 nm. On the other hand, the OSNR improvement is obtained for RPP beyond 650 mW due to the effect of red-shift, the Raman peak gain is shifted away from the laser lines generated around 1555 nm thus reduces the spectral broadening effect

The Usability of E-learning Platforms in Higher Education: A Systematic Mapping Study

The use of e-learning in higher education has increased significantly in recent years, which has led to several studies being conducted to investigate the usability of the platforms that support it. A variety of different usability evaluation methods and attributes have been used, and it has therefore become important to start reviewing this work in a systematic way to determine how the field has developed in the last 15 years. This paper describes a systematic mapping study that performed searches on five electronic libraries to identify usability issues and methods that have been used to evaluate e-learning platforms. Sixty-one papers were selected and analysed, with the majority of studies using a simple research design reliant on questionnaires. The usability attributes measured were mostly related to effectiveness, satisfaction, efficiency, and perceived ease of use. Furthermore, several research gaps have been identified and recommendations have been made for further work in the area of the usability of online learning

Modelling and force tracking control for newly type configuration of magneto-rheological damper

The objective of this paper is to model hysteresis behaviour of new MR damper configuration by using nonparametric model approaches. The approaches are nonparametric linearised data-driven (NPLDD) single input model, non-parametric linearised data-driven (NPLDD) double input model, and simple polynomial model. The modelling is developed to ensure the force of MR damper is tracked to any input force. The NPLDD model is developed based on look-up table while the polynomial model is developed based on curve fitting from the experimental results and consists of a pair of subsystems namely positive and negative acceleration which corresponds to the upper and lower curves. From the simulation results, the NPLDD double input model shows better performance in describing non-linear hysteresis behaviour of the MR damper compared with others. By using the NPLDD model, a force tracking based on PI controller has been developed. It is verified that the NPLDD model together with the PI control strategy has the capability to track the desired damping force well

Assessment on stationarity of EMG signals with different windows size during isotonic contractions

In order to analyse surface electromyography (EMG) signals, it is necessary to extract the features based on a time or frequency domain. These approaches are based on the mathematical assumption of signal stationarity. Stationarity of EMG signals is thoroughly examined, especially in isotonic contractions. According to research, conflicting results have been identified depending on varying window sizes. Therefore, in this study, the authors endeavoured to determine the suitable window size to analyse EMG signals during isotonic contractions utilising stationary tests, reverse arrangement (RA), and modified reverse arrangement (MRA). There were slight differences in the average percentages of signal stationarity for RA and MRA tests in 100 ms, 500 ms, and 1000 ms window sizes. However, there was none for the 200 ms window size. On average, a window size of 200 ms provided stationary information with 88.57% of EMG signals compared to other window sizes. This study also recommended the MRA test to determine EMG signals stationarity for future studies, as the performances were better in comparison to RA tests. However, the following recommendation is only valid for window sizes greater than 200 ms. For a real-time application, the size of the analysis window together with the processing time should be less than 300 ms and a window size of 200 ms is applicable for isotonic contractions

Fuzzy logic for walking patterns based on surface electromyography signals with different membership functions

Classifying walking patterns is important in developing assistive robotic devices, especially for lower limb rehabilitation. Recently, Fuzzy Logic (FL) controllers have successfully been applied in grasping and control system for upper limb based on surface Electromyography (EMG) signals. Therefore, this paper evaluates the performance of FL with different membership functions in discriminating walking phases (e.g, stance and swing phases). The accuracy of two widely used membership functions (MF) like triangular and Gaussian is compared to identify their behavior for detecting the phases of walking. In this study, the MATLAB and Simulink toolboxes are used to examine the performance of each MF. Our findings show Gaussian MF gained better performance than the triangular MF with 90% of classification accuracy. Therefore, the Gaussian MF could be the best solution to classify the walking phases in this work

The effect of values on the perception of sustainable efforts towards event greening

Values are general guides to behaviour from the principles and fundamental convictions which are the standards by which particular good or desirable actions are judged. Every facet of human existence such as health, diet, leisure, quality of life, every day practices; production, consumption, education, research, politics, and societal values are touched by global environmental change. The flourishing of life on earth can be enjoyed when human goods—life, love, liberty, the freedom to pursue a meaningful existence is aligned with the environment around us. Efforts to save the planet remains to be seen from a societal paradigm shift that is taking place. However, it cannot be determined whether the transformation is comprehensive or fast enough. A socially shared cognitive-normative framework in values, norms, beliefs, and strategies typically entails new principles of social organization in the paradigm shift. A significant impact on everyday thinking and practices in substantial parts of the world is a result from sustainability ideas, norms, and values that permeate an ever-increasing part of modern life. This is occurring not only in developed countries but also in developing ones such as Malaysia. The emerging sustainability paradigm is being established by a process of multiple initiatives facilitated by collective learning of new values, ideas, and practices through associations, communities, business, and political networks. There are not only values and beliefs shifting, some reordering of priorities such as governance reforms and innovations, and changes in many daily practices as well. The higher values indicate greater image transfer on the state of the environment. As such, higher values indicate stronger intentions towards environmental issues. The aim of this study is the attendees’ perception on efforts from event organizers to implement sustainable practices in event management and to explore event attendees’ perception of sustainable efforts towards event greening. The focus of this research is to investigate the relationships between the proposed psychological components of values and the influences on perception of attendees on sustainable efforts towards event greening

Theorizing event attendees behavior to increase the demand for sustainable events

Efforts to include sustainable elements to produce green events are deemed critical in recent development of the event management field. However, there are challenges to plan and implement an event that depicts the essential elements that could be characterized as a green event. Basically, the idea of an event with sustainable elementsneed to integrate the three most important concerns regarding the environment, economic and social issues in the process of creating the event. The attendees of event must be educated and nurtured on the importance of having a green event. In the education process of the human element, it is fundamental to look at two important aspects of behavior and belief of individuals, their perception and attitude towards the concept of a green event. Therefore, this study used Theory of Planned Behavior (TPB) in theorizing and developing a new model so as to understand the antecedents that focuses on the behavior of attendees. This model is unique in a sense that it represents the new dimensions of awareness both from the perspective of ecological and environmental which will result in and understanding of the individual behavior and their perception towards sustainable events. As a result of this research, effective strategies could be developed, training and seminars designed to educate the attendees so that this could influence their behavior to positively support events with green credentials. This could also be a contribution to the government in fulfilling the objectiveof the National Key Economic Areas (NKEAs) to create more green events using sustainability issues as an attraction in event tourism. The main objective of this study is to identify the attendees' behavior towards green events to determine the demand for sustainable events. The methodology used is a combination of quantitative and qualitative measures. The findings of this research will help to discover extensive event management knowledge with the key result area of application in sustainability and green technology initiatives