264 research outputs found
Index-based placement and distributed generation sizing based on heuristic search
Transmission loss, voltage regulation and voltage drop are three main issues in distribution system. In recent years, distributed generations (DG) installation approaches have been addressed widely in many parts of the world. Depending on their operating characteristics and location, DG can significantly affect the power losses and voltage profile in distribution system. Thus, prior to the installation of DG into a system, offline study is a priori so that under-compensation and over-compensation can be avoided. This paper presents a method for DG placement based on a voltage stability index, while its sizing is optimally identified using an optimization technique in order to minimize power losses in the distribution system. The proposed technique was tested on an IEEE 10 radial distribution system. As for the DG sizing, an optimization technique based on approximate method (AM) is used and indicated promising results
Analytical study of flexible stimulation waveforms in muscle fatigue reduction
This paper presents the analytical study of flexible stimulation waveforms in muscle fatigue reduction for functional electrical stimulator (FES)-assisted hemiplegic muscle activities. The major challenge of muscle contraction induced by FES is early muscle fatigue which greatly limits activities such as FES-assisted standing and walking. The fixed stimulation pattern applied on a same motor unit has resulted the motor unit to be overworked and fatigue easily. Therefore, in this work, the stimulus parameters, which include the pulse width duration and the frequency were varied to create a few flexible stimulation waveforms using MATLAB/Simulink. The pulse width duration was modulated from 100µs – 500µs to generate five types of flexible stimulation waveforms such as Rectangular, Trapezoidal, Ramp Up, Ramp Down and Triangular. Concurrently, a few ranges of stimulus frequency were also used, which include 20Hz, 30Hz and 50Hz. The generated flexible stimulation waveforms were applied onto a humanoid muscle model to investigate and analyse the muscle output response and early muscle fatigue reduction. From the conducted simulation results and analyses, it was observed that flexible stimulation waveforms such as Triangular, Ramp Up and Ramp Down could reduce early muscle fatigue phenomenon by having lower average of negative slope, in the range of 0.012 to 0.013 for the muscle fitness. In contrast, the Rectangular and Trapezoidal shapes were found to have higher negative slope of muscle fitness in the range of 0.028 to 0.031. The Ramp Down shape was found to have the lowest average of negative slope (0.012) while Rectangular was found to have the highest average of negative slope (0.031). Therefore, it can be concluded that flexible stimulation waveforms such Ramp Down, Ramp Up and Triangular shapes could reduce early muscle fatigue phenomenon with Ramp Down shape having the highest muscle fatigue reduction
Political influences and investors’ perceived risk: a preliminary study
The objective of the study is to discuss the effects of political influence on investors’ perceived risk under the political connected firms. Under the Malaysian political environment, relationship based of economic system which commonly practiced by most of the listed firms would enhance the needs of politician to participate as directors of the firm in order to ensure the firm’s survival in competitive industry. The effects of systematic exchange of favours between politician and firms has led to the arguments of political hypotheses in governance literature. As supported under the helping hand effects, empirical evidences have shown a favourable impact on firms accounting value and market based-performance due to the government favours and bailed-out to connected firms. However, the government obligations towards the people in social and political agenda have exacerbated the rent-seeking activities of political directors in realising the objectives. Moreover, due to the increasing number of cases reported involving high political figures in allegations of misallocation of firm’s resources and abuse of power in the 1MDB (1Malaysia Development Berhad), manipulation of stock figures and forgery of signatures of board members for a numbers of transactions in FGV (Felda Global Ventures Holdings Berhad), the credibility of politicians to perform his duties as firms’ director to maximising the shareholders’ wealth is questioned. As a consequence, a negative perception on the government may lead to inefficient capital market thus impair the investors’ confidence in future investment
Characterization of industrial by-products as asphalt paving material
Most of the recent research is focusing on the utilization of industrial by-products in road construction. The intention is not only to mitigate the problem of waste being dumped to the landfills but to encourage their use as construction material without compromising quality and performance of the road. Steel slag and bottom ash are the industrial by-products generated in large quantity by industry. This study investigates the characteristics of steel slag and bottom ash to be utilized as aggregate in asphalt pavement. Both materials were characterized in terms of physical, chemical and morphological characteristics compared to the conventional granite aggregate. The results revealed that both materials have much potential to be used as aggregate in asphalt mix. The bottom ash was observed weaker in terms of strength, but the steel slag was found much stronger than the granite. The morphological structure of bottom ash and steel slag disclosed that these are made up of porous and rough-edged granular particles with slightly higher water absorption
Geochemistry characterisation of marine clay
In evaluating a suitable type of stabiliser, investigating geochemical characteristics is important for improving the properties of soil. This paper assessed the geochemistry of marine clay samples collected from Batu Pahat, Johor, Malaysia. The parameters investigated were pH, loss on ignition (LOI) and the quantities of sulphate, chloride, nitrate and carbonate ions. The results revealed that the clay was an acidic soil with pH of 3.25 and containing 8% of organic matter. The clay also contained 6,071 mg/l, 281 mg/l and 22 mg/l of sulphate, chloride and nitrate ions, respectively. Sulphate and chloride ions from acid rain and decomposed organic matters are the leading causes of acidity found in clay. Further investigation of the physical properties of the soil further indicated that it belonged to a group of clay having high plasticity (CH) and is unsuitable for construction purposes in its natural condition. The concentration of sulphate ions in the clay sample also advocated that the soil is not suitable to be stabilised using cement or lime due to the risk of the formation of a complex compound of calcium sulphoaluminate hydrate (ettringite). Additionally, the sulphate in the marine clay is likely to attack the concrete of the foundation of future infrastructures that may be built in the study area
Measurement and QCD analysis of double-differential inclusive jet cross sections in pp collisions at s = 8 \backslashsqrt{s}=8 TeV and cross section ratios to 2.76 and 7 TeV
A measurement of the double-differential inclusive jet cross section as a function of the jet transverse momentum p T and the absolute jet rapidity |y| is presented. Data from LHC proton-proton collisions at s = 8 \backslashsqrt{s}=8 TeV, corresponding to an integrated luminosity of 19.7 fb−1, have been collected with the CMS detector. Jets are reconstructed using the anti-k T clustering algorithm with a size parameter of 0.7 in a phase space region covering jet p T from 74 GeV up to 2.5 TeV and jet absolute rapidity up to |y| = 3.0. The low-p T jet range between 21 and 74 GeV is also studied up to |y| = 4.7, using a dedicated data sample corresponding to an integrated luminosity of 5.6 pb−1. The measured jet cross section is corrected for detector effects and compared with the predictions from perturbative QCD at next-to-leading order (NLO) using various sets of parton distribution functions (PDF). Cross section ratios to the corresponding measurements performed at 2.76 and 7 TeV are presented. From the measured double-differential jet cross section, the value of the strong coupling constant evaluated at the Z mass is α S(M Z)þinspace=þinspace0.1164 −þinspace0.0043 +þinspace0.0060 , where the errors include the PDF, scale, nonperturbative effects and experimental uncertainties, using the CT10 NLO PDFs. Improved constraints on PDFs based on the inclusive jet cross section measurement are presented
Synthesis of (cinnamate-zinc layered hydroxide) intercalation compound for sunscreen application
Background:
Zinc layered hydroxide (ZLH) intercalated with cinnamate, an anionic form of cinnamic acid (CA), an efficient UVA and UVB absorber, have been synthesized by direct method using zinc oxide (ZnO) and cinnamic acid as the precursor.
Results:
The resulting obtained intercalation compound, ZCA, showed a basal spacing of 23.9 Å as a result of cinnamate intercalated in a bilayer arrangement between the interlayer spaces of ZLH with estimated percentage loading of cinnamate of about 40.4 % w/w. The UV–vis absorption spectrum of the intercalation compound showed excellent UVA and UVB absorption ability. Retention of cinnamate in ZLH interlayers was tested against media usually came across with sunscreen usage to show low release over an extended period of time. MTT assay of the intercalation compound on human dermal fibroblast (HDF) cells showed cytotoxicity of ZCA to be concentration dependent and is overall less toxic than its precursor, ZnO.
Conclusions:
(Cinnamate-zinc layered hydroxide) intercalation compound is suitable to be used as a safe and effective sunscreen with long UV protection effect
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
Evaluation of BRCA1 and BRCA2 mutations and risk-prediction models in a typical Asian country (Malaysia) with a relatively low incidence of breast cancer
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