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A hyper-heuristic cost optimisation approach for Scientific Workflow Scheduling in cloud computing
No full textEffective management of Scientific Workflow Scheduling (SWFS) processes in a cloud environment remains a challenging task when dealing with large and complex Scientific Workflow Applications (SWFAs). Cost optimisation of SWFS benefits cloud service consumers and providers by reducing temporal and monetary costs in processing SWFAs. However, cost optimisation performance of SWFS approaches is affected by the inherent nature of the SWFA as well as various types of scenarios that depend on the number of available virtual machines and varied sizes of SWFA datasets. Cost optimisation performance of existing SWFS approaches is still not satisfactory for all considered scenarios. Thus, there is a need to propose a dynamic hyper-heuristic approach that can effectively optimise the cost of SWFS for all different scenarios. This can be done by employing different meta-heuristic algorithms in order to utilise their strengths for each scenario. Thus, the main objective of this paper is to propose a Completion Time Driven Hyper-Heuristic (CTDHH) approach for cost optimisation of SWFS in a cloud environment. The CTDHH approach employs four well-known population-based meta-heuristic algorithms, which act as Low Level Heuristic (LLH) algorithms. In addition, the CTDHH approach enhances the native random selection way of existing hyper-heuristic approaches by incorporating the best computed workflow completion time to act as a high-level selector to dynamically pick a suitable algorithm from the pool of LLH algorithms after each run. A real-world cloud based experimentation environment has been considered to evaluate the performance of the proposed CTDHH approach by comparing it with five baseline approaches, i.e. four population-based approaches and an existing hyper-heuristic approach named Hyper-Heuristic Scheduling Algorithm (HHSA). Several different scenarios have also been considered to evaluate data-intensiveness and computation-intensive performance. Based on the results of the experimental comparison, the proposed approach has proven to yield the most effective performance results for all considered experimental scenarios
Spin-coating technique to investigate structural and optical properties of nano and micro cubic-like photonic LiNbO3 under annealing temperature effect
No full textLithium Niobate (LiNbO3) nano and micro structures are deposited on glass substrates by sol-gel method. The nanostructures are deposited at 3000 RPM for 30 s, and annealed at different temperatures, 400, 500 and 600 °C. These samples are characterized and analyzed by Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD) and Ultra-Violet visible (UV–vis) spectrophotometer, respectively. The results show an importance of increasing the annealing temperatures, which indicate that the structure will be enhanced and more crystallize to become more regular. The measured lattice constants, energy gaps and refractive index give good accordance with the experimental results
Post-War waste composition: Household waste management in Misrata City, Libya
No full textWaste generation and its composition reflect activities of a society, due to the fact that it is driven by socio-economic interactions, political structure, and social security. However, changes to waste composition may go unnoticed, except where a database on household solid waste (HSW) is available. Libyan cities were devastated by the scourge of war due to the "Arab spring". This necessitates planning and development to tackle waste management. This study aims to determine the composition of household solid waste in Misrata, Libya, to generate waste stream data that eludes most post-war cities in North Africa and Middle East, which can be used to plan and subsequently manage waste collection services, treatment options, and disposal methods. Discrete classification and direct measurement of HSW from selected families (30) in Misrata were utilized to assess waste composition and changes across households. 400 questionnaires were distributed to residents to determine public perception and its correlation to waste composition. The results confirmed that the highest amount of HSW generated was organic waste, which accounts for 52 %, followed by 20.7%, 16% and 5.9% generated from miscellaneous waste, plastics, and paper wastes, respectively. Metals and glass reported the lowest HSW components, at 3.9% and 1.5%, respectively. The survey component of the study indicated that more than 70% of the respondents claimed that recyclable items are increasing, especially plastics, due to changes in life style and income
Radon transform of auditory neurograms: a robust feature set for phoneme classification
No full textClassification of speech phonemes is challenging, especially under noisy environments, and hence traditional speech recognition systems do not perform well in the presence of noise. Unlike traditional methods in which features are mostly extracted from the properties of the acoustic signal, this study proposes a new feature for phoneme classification using neural responses from a physiologically based computational model of the auditory periphery. The two-dimensional neurogram was constructed from the simulated responses of auditory-nerve fibres to speech phonemes. Features of neurogram images were extracted using the Discrete Radon Transform, and the dimensionality of features was reduced using an efficient feature selection technique. A standard classifier, Support Vector Machine, was employed to model and test the phoneme classes. Classification performance was evaluated in quiet and under noisy conditions in which test data were corrupted with various environmental distortions such as additive noise, room reverberation, and telephone-channel noise. Performances were also compared with the results from existing methods such as the Mel-frequency cepstral coefficient, Gammatone frequency cepstral coefficient, and frequency-domain linear prediction-based phoneme classification methods. In general, the proposed neural feature exhibited a better classification accuracy in quiet and under noisy conditions compared with the performance of most existing acoustic-signal-based methods
Is Khat chewing habit a risk factor for occlusal caries progression?
No full textBackgrounds: People in Yemen and in East African countries chew khat more than five hours daily. Objectives: The aim of this study was to assess the relationship between khat and occlusal caries progression. Methods: A cohort study was carried out among 98 Yemeni khat chewers and 101 non-chewers aged 18-35 years old with early occlusal caries lesions. All participants answered questions on socio-demographic, khat , oral hygiene , sugar intake, and oral health knowledge at baseline. All posterior teeth with an early enamel lesion on occlusal surfaces detected by visual inspection at baseline were also subjected to DIAGNOdent assessment to confirm early lesion (DIAGNOdent reading 13-24). Participants were re-examined after 12 weeks. Caries progression was considered to occur when the DIAGNOdent reading was >25. Data were analyzed using Relative risk, Mann-Whitney U test, a Wilcoxon Signed-Rank test and logistic regression analysis. Results: Occlusal caries progression incidence between khat chewers and non-chewers, with the relative risk was 1.68. There was no significant difference in occlusal caries progression on chewing side and non-chewing side among khat chewers. Khat chewing was a statistical predictor for those with low income. Conclusion: Khat is a risk factor for occlusion caries progression among low income group
Independent determinants of periodontitis in Yemeni adults: A case-control study
No full textObjectives: The relative importance of risk factors of periodontitis varies from one population to another. In this study, we sought to identify independent risk factors of periodontitis in a Yemeni population. Methods: One hundred and fifty periodontitis cases and 150 healthy controls, all Yemeni adults 30-60 years old, were recruited. Sociodemographic data and history of oral hygiene practices and oral habits were obtained. Plaque index (PI) was measured on index teeth. Periodontal health status was assessed using Community Periodontal Index (CPI) and Clinical Attachment Loss (CAL) according to WHO. Periodontitis was defined as having one or more sextants with a CPI score ≥ 3. Multiple logistic regression modelling was employed to identify distal, intermediate and proximal determinants of periodontitis, while ordinal regression was used to identify those of CAL scores. Results: In logistic regression, PI score was associated with the highest odds of periodontitis (OR = 82.9) followed by cigarette smoking (OR = 12.8), water pipe smoking (OR = 10.2), male gender (OR = 3.4) and age (OR = 1.19); on the other hand, regular visits to the dentist (OR = 0.05), higher level of education (OR = 0.37) and daily dental flossing (OR = 0.95) were associated with lower odds. Somewhat similar associations were seen for CAL scores (ordinal regression); however, qat chewing was identified as an additional determinant (OR = 4.69). Conclusion: Water pipe smoking is identified as a risk factor of periodontitis in this cohort in addition to globally known risk factors. Adjusted effect of qat chewing is limited to CAL scores, suggestive of association with recession
Effect of Cobalt Catalyst Confinement in Carbon Nanotubes Support on Fischer-Tropsch Synthesis Performance
No full textPre-treating the multi-walled carbon nanotubes (CNTs) support by refluxing in 35 vol% nitric acid followed by heating at the temperature of 600 to 900 °C resulted in the formation of defects on the CNTs. Increasing the temperature of the pre-treatment of the CNTs from 600 °C to 900 °C, enhanced the fraction of cobalt-oxide nanoparticles encapsulated in the channels of CNTs from 31% to 70%. The performance of Co/CNTs in Fischer-Tropsch synthesis (FTS) was evaluated in a fixed-bed micro-reactor at a temperature of 240 °C and a pressure of 2.0 MPa. The highest CO conversion obtained over Co/CNTs. A.900 was 59% and it dropped by ~3% after 130 h of time-on-stream. However, maximum CO conversion using Co/CNTs. A.600 catalysts was 28% and it decreased rapidly by about 54% after 130 h of time-on-stream. These findings show that the combined acid and thermal pre-treatment of CNTs support at 900 °C has improved the stability and activity of the Co/CNTs catalyst in FTS
Development of an information literate school community: Perceived roles and practices of teacher librarians
No full textThe research investigates the perceived roles and practices of teacher librarians in developing an Information Literate School Community (ILSC). The study employs a survey method, which was based on a set of an ILSC benchmarks developed by Henri (1995). A web-based questionnaire was e-mailed to 148 teacher librarians from Malaysian secondary schools in which their School Resource Centers (SRCs) received 4 and 5 stars rating for the year 2015 SRCs evaluation. The result showed that the teacher librarians rated 11 roles as being important, however they acknowledged that they have successful (very much) in executing only one task in their practice that is they "ensure that teachers are efficient library users". Teacher librarians evaluated the information services as very important and at the same time, they thoroughly practiced their roles as the stakeholder in terms of delivering and providing information services to the school community. The finding also revealed that the integration of ICT was recorded as having the highest mean gap between perceived roles and practices. This indicated that although teacher librarians had placed integrating ICT as an important role, there was still a lack of practice. Furthermore, this study has attempted to bridge the apparent divide in the practices of information literacy and the perception of the role in developing an ILSC
Influence of Precursor Concentration and Temperature on the Formation of Nanosilver in Chemical Reduction Method
No full textNanosilver particles (NSPs) were produced by the reduction of silver nitrate using glucose as reducer, poly (vinyl pyrrolidone) as stabilizer and sodium hydroxide as reaction enhancer. Two parameters were investigated which are silver nitrate concentration (0.1 M, 0.5 M and 1.0 M) and reaction temperature (60°C and 80°C). Through spectral analysis using ultraviolet-visible spectrophotometer (UV-vis), all the samples recorded the maximum peak in the range of 384-411 nm which verified the formation of NSPs. TEM images showed the nanoparticles have spherical shape with the size range of 25-39 nm. Particle size and zeta potential analysis recorded the hydrodynamic size of nanoparticles in the range of 85-105 nm and the zeta potential ranging from -25 to -30 mV, under the pH value of 8. X-ray diffraction analysis showed that the NSPs have face center cubic (FCC) structure. All the produced NSPs surprisingly showed ferromagnetic-like behaviour based on the magnetization curves. FTIR result confirmed the presence of poly (vinyl pyrrolidone) on the NSPs surface. Furthermore, at the reaction temperature 60°C, the crystallite size, physical size as well as hydrodynamic size increased as the precursor concentration increased from 0.1 M to 0.5 M. However, as the precursor concentration further increases to 1.0 M, the size become smaller due to incomplete reduction process. In contrast, at 80°C, the sizes was gradually increased as the precursor concentration increases up to 1.0 M. In terms of controlled precursor concentration, the crystallite size and physical size become smaller as the temperature increases
Enhancing Temperature Sensitivity Using Cyclic Polybutylene Terephthalate- (c-PBT-) Coated Fiber Bragg Grating
No full textA polybutylene terephthalate (c-PBT) coating for enhancing the temperature sensitivity of a fiber Bragg grating- (FBG-) based sensor is proposed and demonstrated. The coating is seen to increase the sensitivity of the proposed sensor by a factor of approximately 11 times as compared to a bare FBG, giving a Bragg wavelength shift of 0.11 nm/°C with an operating temperature ranging from 30°C to 87°C. The proposed sensor is also easy to fabricate as compared to other similarly coated FBG sensors, giving it a significant advantage for field applications with the added advantage of being easily reformed to fit various housings, making it highly desirable for multiple real-world applications