Performance of treated and untreated asymmetric polysulfone hollow fiber membrane in series and cascade module configurations for CO2/CH4 gas separation system

This study investigates the effects of one-, two- and three-stage membrane system configurations in series arrangement for theCO2/CH4 separation for both untreated and treated membranes. Asymmetric polysulfone hollow fiber membranes were fabricated from 33 wt.% of polysulfone polymer using dry/wet phase inversion process. The produced membranes were characterized by pure gas permeation experiments, Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), density measurement and Thermogravimetric Analysis (TGA). For both untreated and treated membranes, the pressure-normalized flux of CO2 decreased with increasing of the membrane stages. In addition, the selectivities of asymmetric hollow fiber membrane showed a more constant trend with feed pressure. Treated membrane exhibited lower pressure-normalized flux than untreated membranes due to skin layer densification which increased the transport resistance, thus lead to the reduction in pressure-normalized fluxes. Among all the three configurations studied, two-stage membrane configuration showed the most constant trend in term of selectivity. However, three-stage cascade configuration produced the highest CO2/CH4 selectivity especially when tested at low feed pressure range. Effect of stage cut on feed pressure showed an increasing trend with increasing of CO2 and CH4 feed pressure for all configurations. This is due to the increase of the permeation driving force, which caused the passage of larger amounts of more permeable gas through the membrane. This study showed that, three-stage cascade configuration exhibited the smallest stage cut values thus produced higher purity of CO2 in permeate stream

Priority-grouping method for parallel multi-scheduling in Grid

With the advent in multicore computers, the scheduling of Grid jobs can be made more effective if scaled to fully utilize the underlying hardware, and parallelized to benefit from the exploitation of multicores. The fact that sequential algorithms do not scale with multicore systems nor benefit from parallelism remains a major obstacle to scheduling in the Grid. As multicore systems become ever more pervasive in our computing lives, over reliance on such systems for passive parallelism does not offer the best option in harnessing the benefits of their multiprocessors for Grid scheduling. An explicit means of exploiting parallelism for Grid scheduling is required. The Group-based Parallel Multi-scheduler, introduced in this paper, is aimed at effectively exploiting the benefits of multicore systems for Grid scheduling by splitting jobs and machines into paired groups and independently scheduling jobs in parallel from those groups. We implemented two job grouping methods, Execution Time Balanced (ETB) and Execution Time Sorted then Balanced (ETSB), and two machine grouping methods, Evenly Distributed (EvenDist) and Similar Together (SimTog). For each method, we varied the number of groups between 2, 4 and 8. We then executed the MinMin Grid scheduling algorithm independently within the groups. We demonstrated that by sharing jobs and machines into groups before scheduling, the computation time for the scheduling process drastically improved by magnitudes of 85% over the ordinary MinMin algorithm when implemented on a HPC system. We also found that our balanced group based approach achieved better results than our previous Priority based grouping approach

QoS within Business Grid Quality of Service (BGQoS)

Differences in domain QoS requirements have been an obstacle to utilising Grid Computing for main stream applications. While the resource could potentially provide potentially vital services as well as providing significant computing and storage capabilities, the lack of high level QoS specification capabilities has proven to be a hindrance. Business Grid Quality of Service (BGQoS) is a QoS model for business-oriented applications on Grid computing systems. BGQoS defines QoS at a high level facilitating an easier request model for the Grid Resource Consumer (GRC) and eliminates confusion for the Grid Resource Provider in supplying the appropriate resources to meet the GRC requirements. It offers high level QoS specification within multi-domain environments in a flexible manner. Employing component separation and dynamic QoS calculation, it provides the necessary tools and execution environment for a scalable set of requirements tailoring to specific domain demands and requirements. Moreover, through reallocation, the model provides the insurance that all QoS requirements are met throughout the execution period, including migrating tasks to different resources if necessary. This process is not random and adheres to a set of conditions which ensures that task execution and resource allocation happen when and in accordance with execution requirements. This paper focuses on BGQoS’ flexibility and QoS capability. More specifically, the concentration is on core operations within BGQoS and the methods used in order to deliver a sustained level of QoS which meets the GRC’s requirements while being versatile and flexible such that it can be tailored to specific domains. This paper also presents an experimental evaluation of BGQoS. The evaluation investigates the behaviour and performance of the separate operations and components within BGQoS, and moreover, it presents an investigation and comparison between the different operations and their effect on the full model

Group-based parallel multi-scheduler for grid computing

With the advent in multicore computers, the scheduling of Grid jobs can be made more effective if scaled to fully utilize the underlying hardware, and parallelized to benefit from the exploitation of multicores. The fact that sequential algorithms do not scale with multicore systems nor benefit from parallelism remains a major obstacle to scheduling in the Grid. As multicore systems become ever more pervasive in our computing lives, over reliance on such systems for passive parallelism does not offer the best option in harnessing the benefits of their multiprocessors for Grid scheduling. An explicit means of exploiting parallelism for Grid scheduling is required. The Group-based Parallel Multi-scheduler, introduced in this paper, is aimed at effectively exploiting the benefits of multicore systems for Grid scheduling by splitting jobs and machines into paired groups and independently scheduling jobs in parallel from those groups. We implemented two job grouping methods, Execution Time Balanced (ETB) and Execution Time Sorted then Balanced (ETSB), and two machine grouping methods, Evenly Distributed (EvenDist) and Similar Together (SimTog). For each method, we varied the number of groups between 2, 4 and 8. We then executed the MinMin Grid scheduling algorithm independently within the groups. We demonstrated that by sharing jobs and machines into groups before scheduling, the computation time for the scheduling process drastically improved by magnitudes of 85% over the ordinary MinMin algorithm when implemented on a HPC system. We also found that our balanced group based approach achieved better results than our previous Priority based grouping approach

Nano-satellite attitude control system based on adaptive neuro-controller

The current research focuses on designing of an intelligent controller for attitude control system (ACS) of nano-satellite. The nanosatellite namely Innovative Satellite (InnoSAT) was organized by Agensi Angkasa Negara (ANGKASA) to attract the interest of Malaysian universities in satellite development.In this study, an intelligent controller based on Hybrid Multi Layered Perceptron (HMLP) network was developed. The network used model reference adaptive control (MRAC) system as a control scheme to control a time varying systems where the performance specifications are given in terms of a reference model.The Weighted Recursive Least Square (WRLS) algorithm will adjust the controller parameters to minimize error between the plant output and the model reference output.The objective of this paper is to analyze the tracking performance of ANC based on HMLP network and ANC based on standard MLP network for controlling a satellite attitude. The simulation results indicate that ANC based on HMLP network gave better performance than ANC based on standard MLP network

Crosstalk improvement of polymer in glass thermo-optical multimode interference switch

A new structural design of combined variable optical attenuator (VOA) and optical switch has been proposed in this paper. The design is based on the multimode interference (MMI) architecture and it has been demonstrated for crosstalk improvement of optical switch. The device operates by manipulating thermo-optic (TO) effect that naturally existed in all optical waveguide material. By applying a polymer on glass material platform, the optimized VOA with optical attenuation of 21.52 dB has been achieved with applied power of 36.4 mW. The simulation result shows that the VOA helps to achieve significant improvements of optical switch performance particularly in crosstalk reduction up to 89.66%

Chlorella vulgaris modulates hydrogen peroxide-induced dna damage and telomere shortening of human fibroblasts derived from different aged individuals

The objective of this study was to investigate the modulatory effect of Chlorella vulgaris on cultured fibroblast cells derived from young and old aged individuals focusing on DNA damage, telomere length and telomerase activity. Dose-response test of the algal extract on cells in both age groups revealed that optimum viability was observed at a concentration of 50 μg/ml. Results obtained showed that Chlorella vulgaris exhibited protective effects against H2O2-induced oxidative stress as shown by the reduction in damaged DNA caused by H2O2 treatment (

User friendly system for the visually impaired in learning Al-Quran

This study presents a method to enable the visually impaired Muslim to learn and read the Al-Quran using Braille Display with software help. The system reads the database which contains all verses of Al-Quran and user will need to select the verse and ayah to read. Besides that, this system can be used in a class to teach visually impaired students to learn Al-Quran. Every word or character typed by the instructor in the main Braille Panel will be transmitted to the sub Braille Panel that is connected to the main Braille Panel. The selected verse of Al-Quran and ayah will also generate an index before being transmitted to the Braille Panel. The index will be transmitted to the Braille Display for people to touch and read the display. A user friendly Graphical User Interface (GUI) will be used to fulfill the ergonomics for the visually impaired user's physical capabilities. Several approaches are used to design and implement the interface for the visually impaired like speech or sound output and Braille display. The Braille codes can be displayed using the Braille panel. The design interface and structure of the system for the visually impaired users in learning Al-Quran is presented

Failure of woven fiber glass epoxy composite under charpy impact loading

Woven glass fiber reinforced epoxy composite at 55 vol% fiber content was fabricated using conventional hand lay-up method. The impact strength of the prepared samples were measured under Charpy impact test at +50oC and - 50oC temperature. The fractured surface of composite samples were investigated using scanning electron microscope. The impact energy for samples fractured at +50oC was at 380 KJm-2 whereas the low temperature of - 50oC showed impact energy of 178 KJm-2. The high plastic deformation from the sample tested at +50oC is the evidence from the high amount of absorbed energy compared to -50oC which revealed lower deformation. At this subzero temperature, the increased brittleness produced extensive matrix cracking and fiber splitting. However, scanning electron fractograph at +50oC showed mixed failure mode of large delaminations, fiber splitting and matrix cracking. The impact values of 380 KJm-2 and 178 KJm-2 tested at +50oC and -50oC respectively would suggest that this composite is suitable to replace steel for impact applications and is safe to be used at both high and low environmental temperatures

An Inquiry on the Affordability of Legal Services and the Appropriateness of the Regular Courts for Consumer Redress in Nigeria

Abstract The paper assessed the appropriateness of the regular courts for consumer redress in Nigeria in view of delays, and the cost of legal services before the ordinary courts. The paper adopted a phenomenological qualitative research approach in exploring the perspectives and experience of government officials and other private bodies involved in consumer protection and consumer redress. Twenty face-to-face interviews were conducted, transcribed and thematically analysed. The study found that legal services are not affordable to the consumers and that the ordinary courts are inappropriate for consumer dispute resolution. The research participants were limited to officials of consumer protection, products standard setting agencies, legal aid, academics, and heads of consumer organizations. The participants excluded the ordinary consumer of goods and services in the country. The study recommends the establishment of a cheap, simple and expeditious redress mechanism for redressing the widespread consumer injustice in the country. A wellfunded legal aid scheme to bridge the gap between the poor consumer and the justice system is equally suggested. This study is the first attempt at qualitatively exploring in-depth the appropriateness of the justice delivery system for consumer redress in Nigeria