Tribological behaviour of graphite/date palm fibres reinforced epoxy composites

Natural fibres are becoming alternative candidates to synthetic fibres because of their environmental and economic advantages. In this study, the mechanical and the tribological performance of epoxy composites (ECs) based on date palm fibres (DPFs) was evaluated and compared with neat epoxy (NE). The work is divided into three stages: fibre optimisation, graphite optimisation and final composite selection. Different fibre diameters (0.3–0.7 mm) and concentration of sodium hydroxide (NaOH) (zero to nine per cent) were used in preparing the fibre. For optimisation purposes, the interfacial adhesion between the DPFs and the epoxy matrix was studied using a new fragmentation technique that considers the influence of the NaOH treatment and the fibre diameter. At this stage, the results revealed that NaOH treatment significantly influences both the fibre strength and the fibre interfacial adhesion. Six per cent NaOH exhibited the optimum concentration to gain good mechanical properties for the EC, since it can maintain good interfacial adhesion, while maintaining good fibre strength. In the second stage, the influence of the graphite weight presentation on ECs was evaluated from a mechanical and tribological perspective. Different weight percentages were used in the sample preparation (zero to seven per cent) for tensile, hardness and adhesive wear experiments. In the first part of this study, ultimate tensile strength and modulus of elasticity values and fracture morphology are determined. In the second part, specific wear rate, friction coefficient, interface temperature and surface morphology of the composites are determined. The results are discussed to gain the optimum mixing ratio of graphite with epoxy. The results revealed that there is a significant influence of the weight fraction of the graphite on both mechanical and tribological performance of the composites. Intermediate weight percentage of three weight per cent graphite in the EC was considered the optimum from both mechanical and tribological performance, since there is a slight reduction in the tensile properties and significant improvement to the hardness, wear and frictional characteristics. The modification on the wear track roughness significantly controlled the wear and frictional behaviour of the composites. Micrographs of the worn surface showed different wear mechanisms, depending on the content of the graphite in the composites. Softening and fragmentation appeared with low content of graphite presence in the composite, since there was no sign of aggregation or detachments of fillers. From the second stage on the graphite percentage in the composite, it was concluded that three weight per cent of graphite in the ECs represents the optimum content from mechanical and tribological perspectives. In the third stage, the mechanical and tribological performance of the ECs based on three weight per cent graphite, DPF and three weight per cent graphite plus DPF are discussed and compared with NE. Further, the tribological performance of the composites is discussed, considering two different adhesive wear techniques: block on ring (BOR) and block on disk (BOD). This stage revealed that DPF is able to improve the mechanical properties of the ECs with no signs of pull out or debonding of the fibres. The main fracture mechanism was breakage in the fibre, fracture in the resinous regions and micro-cracks with graphite presence in the composites. Further, the addition of the three weight per cent of the graphite into the date fibre/ECs contributed to the improvement of the ECs; the fibres assisted in strengthening the surface, while the graphite generated the lubricant film transfer. Tribological experimental configuration significantly controlled the wear behaviour of the composite; the wear performance worsened under BOD compared to BOR because of the high thermo-mechanical loading in the case of BOD compared to BOR

Development of a Decision Making Model for the Assessment of Electricity Demand Side Management in the State of Kuwait

Kuwait’s per capita electrical energy consumption is among the largest in the world, reaching 13,663 kWh per person in 2011. The electricity demand in Kuwait is increasing, which requires additional investments in power generation. A particular challenge in Kuwait is the peak demand in summer, when extreme heat increases air conditioning loads. Peak demand reached 11,220 MW in 2011, with a fast growth rate averaging 5.6% over the last decade and a maximum production capacity of around 14,720 MW. It is not possible to cope with this demand simply by increasing generation capacity. Therefore, the only alternative available to Kuwait is to control electricity demand via demand-side management. The main objective of this research is to assess and select the optimal demand- side management (DSM) technologies for buildings in the governmental sector (office, religious and school buildings) and to investigate the key factors in the evaluation process. To achieve the research objective, a model was proposed using multi-criteria decision-making techniques to enable the forecasting and comparison of DSM alternatives that are suitable for buildings. The developed model includes environmental, economic, technical and social considerations. The research methodology is based on three main phases. Phase 1: Data collection through a mail questionnaire that was sent to 42 experts for the identification of criteria and demand-side management alternatives. Phase 2: Screening and narrowing of the data collected in Phase 1 using a set of questionnaires, including the identification of potential DSM alternatives and criteria suitable for further analysis. This phase was performed through the Delphi process, taking into consideration the opinions of 28 experts. Phase 3: Use of Multi-criteria Decision Making (MCDM) techniques, namely the Analytic Hierarchy Process (AHP) and Fuzzy Analytic Hierarchy Process (FAHP), to evaluate and rank the identified DSM alternatives and criteria. This was done using pairwise comparisons of 17 experts to evaluate the criteria and alternatives for the buildings (office, religious and school). The research showed that the experts identified six alternative technologies and five criteria for the selection and evaluation of governmental buildings (office, religious and school). After performing the three phases of this research project, a set of criteria and alternatives were ranked based on the information gathered from every group of experts. It was found that reduction in consumption, capital cost and ease of implementation were the three most recommended criteria for the selection of DSM technologies in Kuwait government buildings while high efficiency lighting and programmable thermostats were identified as the most recommended DSM technologies for these buildings. An important aspect of this research is that unlike engineering approaches which sometimes depend on expensive test equipment or, often for building design, expensive computer modelling exercises, the proposed framework can be easily adopted by anyone without any significant financial cost. The FAHP approach was also tested and its results compared with those of AHP. There was a slight difference between using AHP and FAHP in terms of ranking the criteria and alternatives but that the difference barely affects the ranking. It was found that the AHP provides a convenient MCDM approach for solving the complex problem of selecting the optimal DSM options for buildings. The contributions of this thesis are the development of a novel framework for systematic selection and ranking of DSM technologies in different types of buildings using the Delphi method and AHP; the identification of the most important DSM technologies and criteria for their selection for three types of governmental buildings in Kuwait; and establishing that results from using AHP and FAHP for the selection of appropriate DSM measures in these buildings are almost identical, so use of AHP is likely to be sufficient in most building studies of this type

Principles to enable comprehensive national marine ecosystem status assessments from disparate data: The state of the marine environment in Kuwait

This paper presents an approach for preparing a comprehensive national marine ecosystem assessment and its application to the marine and coastal areas of the State of Kuwait. The approach is based on a set of principles to enable diverse data sources, of differing data quality and salience, to be combined into a single coordinated national assessment of marine ecosystem status to support the implementation of ecosystem-based management. The approach enables state assessments for multiple components of the marine ecosystem to be undertaken in a coordinated manner, using differing methods varying from quantitative to qualitative assessments depending on data and indicator availability. The marine ecosystem assessment is structured according to 6 major themes: i) Biodiversity, ii) Commercial Fisheries, iii) Food and Water Quality for Human Health, iv) Environmental Pollution, v) Eutrophication and Harmful Algal Blooms, and vi) Coastal Process and Oceanography. Comprehensive ecosystem assessments are an essential part of implementing the ecosystem approach, however detailed data directly related to clear, specified numerical management targets covering all aspects of a marine ecosystem are rarely available. The development of a State of the Marine Environment Report (SOMER) for Kuwait demonstrate that a coordinated comprehensive ecosystem assessment can be conducted using disparate data, and in relation to partially specified regulatory management objectives. The Kuwait SOMER highlighted the issues of coastal pollution, particularly sewage for human health and the environment. It shows that the rapid urbanization of Kuwait has led to significant changes in the ecology, with clear impacts on coral reef health, the availability of nesting locations for turtles and habitats for migratory birds. Long-term changes in nutrient input, via waste water and modified freshwater inputs is resulting in demonstrable impacts on a range of marine species and habitats within Kuwait marine waters. It also supports the move towards a regional approach required due to transboundary properties of many of the ecosystem components, drivers and pressures

Tuberculosis suspicion and knowledge among private and public general practitioners: Questionnaire Based Study in Oman

<p>Abstract</p> <p>Background</p> <p>Early detection of smear positive TB cases by smear microscopy requires high level of suspicion of TB among primary care physicians. The objective of this study is to measure TB suspicion and knowledge among private and public sector general practitioners using clinical vignette-based survey and structured questionnaire.</p> <p>Methods</p> <p>Two questionnaires were distributed to both private and public GPs in Muscat Governorate. One questionnaire assessed demographic information of the respondent and had 10 short clinical vignettes of TB and non-TB cases. The second questionnaire had questions on knowledge of TB, its diagnosis, treatment, follow up and contact screening based on Ministry of Health policy. TB suspicion score and TB Knowledge score were computed and analyzed.</p> <p>Results</p> <p>A total of 257 GPs participated in the study of which 154 were private GPs. There was a significant difference between private and public GPs in terms of age, sex, duration of practice and nationality. Among all GPs, 37.7% considered TB as one of the three most likely diagnoses in all 5 TB clinical vignettes. Private GPs had statistically significantly lower TB suspicion and TB knowledge scores than public GPs.</p> <p>Conclusion</p> <p>In Oman, GPs appear to have low suspicion and poor knowledge of TB, particularly private GPs. To strengthen TB control program, there is a need to train GPs on TB identification and adopt a Private Public Mix (PPM) strategy for TB control.</p

Diversification Benefits of Shari’ah Compliant Equity ETFs in Emerging Markets

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Previous studies on the performance of Islamic finance and banking have been more comparative than experimental when it comes to the role and effect of Islamic (Shari'ah compliant) assets in a conventional setting. This paper investigates whether Shari'ah compliant exchange-traded funds (ETFs) have potential diversification benefits to a volatile portfolio of conventional investments in emerging markets. The results suggest that such assets not only improve the risk-adjusted returns of portfolios but also receive proportionally higher weight during crisis periods. Hence, institutional investors should consider the ‘religion effect’ when they manage their assets, given the evidence regarding the outperformance of Shari'ah compliant equity relative to their conventional peers

Do Islamic indices provide diversification to bitcoin? A time-varying copulas and value at risk application

This is an accepted manuscript of an article published by Elsevier in Pacific-Basin Finance Journal on 08/04/2020, available online: https://doi.org/10.1016/j.pacfin.2020.101326 The accepted version of the publication may differ from the final published version.© 2020 The emergence of new asset classes offers avenues to international investment community however understanding relationship between any two assets in a single portfolio is important. We investigate the risk dependence between daily Bitcoin and major Islamic equity markets spanning over from July 2010 to March 2018. We start by examining long memory properties of Bitcoin and sampled Islamic indices and report significant results. The residuals from fractionally integrated models are then used in bivariate time invariant and time varying copulas to investigate dependence structure. Among all Islamic indices, DJIUK, DJIJP and DJICA exhibit time varying dependence with Bitcoin. In addition, we apply VaR, CoVaR and ΔCoVaR as risk measure to examine spillover between Bitcoin and Islamic equity markets. VaR of Bitcoin exceeds from VaR of Islamic indices and CoVaR of both Islamic and Bitcoin exceeds their respective VaR, suggesting presence of risk spillover between each other. Our results also report asymmetry between downside and upside ΔCoVaR suggesting implications for investors with different risk preferences. Finally, the diversification benefits indicate that Islamic equity market serves as an effective hedge in a portfolio along with Bitcoin.Accepted versio

Shintoism

يتحدث هذا البحث عن الدين الرسمي للشعب اليابان

Community Translation in the Sultanate of Oman: "A Soft Force" in the Fight against COVID-19

Translation, in modern Oman, serves as an essential means of communication between the Arabic-speaking Omanis and other individuals of smaller linguistic and ethnic communities working or residing in the country. The purpose of translation in such situations is to empower linguistically disempowered individuals within Oman and ensure that they are adequately informed and that they actively participate in the country’s development. Yet, there have been very few studies that deal specifically with community translation in Oman and in the wider Arab world. The lack of a translation governing body and Omani translation scholars' tendency to focus on literary and technical translation in Oman are some of the factors that have kept community translation very much on the margins of translation. The aim of this contribution, therefore, is to address some of the issues pertaining to community translation in the Sultanate of Oman. In particular, it focuses on the long-standing relationship between translation and communication within Oman and how translation plays a pivotal role in the development of the country, given the fact that Oman, like other countries in the Arabian Peninsula, relies to a great extent on skilled expatriate workforce in various fields. In particular, this contribution investigates the role community translation has played in the fight against COVID-19 in the Sultanate of Oman. The effects of this pandemic are serious particularly in a country where around 40% of its population comes from different parts of the world and the majority of whom do not speak Arabic, the official language of the country, nor do they speak or read English, the language of business in Oman. During such times, community translation becomes crucial

The Treatment of Terms Relating to Islam and the Arab World in English Dictionaries

&lt;p&gt;Abstract: This article investigates the treatment of vocabulary items relating to Islam and the Arab world in three major English dictionaries: Longman Dictionary of Contemporary English, New Oxford Dictionary of English, and Merriam-Webster's Collegiate Dictionary. The three dictionaries are compared with regard to their inclusion of 73 Arabic items (including loanwords) used in texts on Islam and the Middle East at the Google news file. With religion as theme, eight of these terms have been examined and compared across their entries in these three dictionaries to determine the closeness of the lexicographic description of these terms to their original meanings among native speakers of Arabic and to detect, from these speakers' viewpoint, any deficiencies in the defining language of their respective entries. The examination of the definitions of terms relating to Islam and the Arab world in the three dictionaries has revealed a number of pitfalls that may require editorial reconsideration. These include circularity, insufficient information, negative contexts, very general definitions, ambiguity, incomplete information, narrow definitions and encyclopedic re-dundancy.&lt;/p&gt;&lt;p&gt;Keywords: ARABIC LOANWORDS, CULTURAL TERMS, DEFINITION, ISLAM, REPRE-SENTATION, LEXICOGRAPHY&lt;/p&gt;&lt;p&gt;Opsomming: Die behandeling van terme betreffende Islam en die Arabie-se wêreld in Engelse woordeboeke. Hierdie artikel ondersoek die behandeling van woordeskatitems betreffende Islam en die Arabiese wêreld in drie vooraanstaande Engelse woor-deboeke: Longman Dictionary of Contemporary English, New Oxford Dictionary of English, en Merriam-Webster's Collegiate Dictionary. Die drie woordeboeke word vergelyk met betrekking tot hul opname van 73 Arabiese items (insluitende leenwoorde) wat in tekste oor Islam en die Midde-Ooste in die Google-nuuslêers gebruik word. Met godsdiens as tema, is agt van hierdie terme ondersoek en vergelyk met hul inskrywing in dié drie woordeboeke om die nabyheid vas te stel van die leksiko-grafiese omskrywing van hierdie terme aan hul oorspronklike betekenisse onder moedertaalspre-kers van Arabies, en om vanuit hierdie sprekers se gesigspunt enige gebreke op te spoor in die definisietaal van hul onderskeie inskrywings. Die ondersoek van die definisies van terme betreffende Islam en die Arabiese wêreld in die drie woordeboeke het 'n aantal slaggate blootgelê wat moontlik redaksionele heroorweging nodig maak. Dit sluit in sirkulariteit, onvoldoende inligting, negatiewe kontekste, baie algemene definisies, dubbelsinnigheid, onvolledige inligting, beperkte definisies en ensiklopediese oortolligheid.&lt;/p&gt;&lt;p&gt;Sleutelwoorde: ARABIESE LEENWOORDE, KULTURELE TERME, DEFINISIE, ISLAM, VERTEENWOORDIGING, LEKSIKOGRAFIE&lt;/p&gt

Postpartum Depression Prevalence and Associated Factors: An Observational Study in Saudi Arabia

Background and Objectives: Postpartum depression (PPD) is a psychological disorder in women who recently gave birth. It can present as mild to severe depression. Multiple studies across the globe have used the Edinburgh Postnatal Depression Scale to reveal the factors that affect the prevalence of PPD. Results from various published studies showed a high prevalence of PPD in Saudi Arabia. The objective of this study is to investigate the major factors that increase PPD and other associated factors. Materials and Methods: An observational cross-sectional study was carried out at primary healthcare centres and military hospitals in Al Kharj. The study measured the rate of PPD among Saudi women during the postpartum period. We studied 279 women aged 19&ndash;45 (mean age 31.91, SD &plusmn; 6.45) in their postpartum period and followed up to 2 months after delivery. Results: The prevalence of PPD in our cohort was 32.8%. Multivariate logistic regression analysis showed that previous depression diagnosis (p = 0.001), lower education status (p = 0.029), unemployment (p = 0.014), and delivery disposition of C-section (p = 0.002) remained associated with an increased risk of developing PPD. Conclusions: The increasing number of Saudi women with PPD demonstrates that it is a highly prevalent condition. PPD affects not only the health of the mother but also that of her baby and other family members. Our results showed that the history of diagnosed depression, lower education status, unemployment, and delivery disposition of C-sections were independent predictors of PPD development. Raising awareness and controlling the vulnerable factors could decrease the high risk of its effects