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Simulation Using Sensitivity Analysis of a Product Production Rate Optimization Model of a Plastic Industry

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Open Journal of Energy Efficiency 2013年第3期2卷 139-142页

作者： Mala abba-Aji Vincent Ogwagwu Bukar Umar Musa Department of Electrical and Electronics Engineering University of Maiduguri Maiduguri Nigeria Department of Mechanical Engineering University of Maiduguri Maiduguri Nigeria Federal University of Technology Minna Nigeria

This study analyzes the sensitivity analysis using shadow price of plastic products. This is based on a research carried out to study optimization problem of BOPLAS, a plastic industry in Maiduguri, North eastern Nigeria. Simplex method of Linear programming is employed to formulate the equations which were solved by using costenbol software. Sensitivity analysis using shadow price reveals that the price of wash hand bowls is critical to the net benefit (profit) of the company.

关键词： Sensitivity Analysis Simplex Method Linear Programming Optimization

To mask or not to mask:Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic

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Infectious Disease Modelling 2020年第1期5卷 293-308页

作者： Steffen E.Eikenberry Marina Mancuso Enahoro Iboi Tin Phan Keenan Eikenberry Yang Kuang Eric Kostelich abba B.Gumel School of Mathematical and Statistical Sciences Arizona State UniversityTempeAZ85287USA

Face mask use by the general public for limiting the spread of the COVID-19 pandemic is controversial,though increasingly recommended,and the potential of this intervention is not well *** develop a compartmental model for assessing the communitywide impact of mask use by the general,asymptomatic public,a portion of which may be asymptomatically *** simulations,using data relevant to COVID-19 dynamics in the US states of New York and Washington,suggest that broad adoption of even relatively ineffective face masks may meaningfully reduce community transmission of COVID-19 and decrease peak hospitalizations and ***,mask use decreases the effective transmission rate in nearly linear proportion to the product of mask effectiveness(as a fraction of potentially infectious contacts blocked)and coverage rate(as a fraction of the general population),while the impact on epidemiologic outcomes(death,hospitalizations)is highly nonlinear,indicating masks could synergize with other nonpharmaceutical ***,masks are found to be useful with respect to both preventing illness in healthy persons and preventing asymptomatic *** mask adoption scenarios,for Washington and New York state,suggest that immediate near universal(80%)adoption of moderately(50%)effective masks could prevent on the order of 17e45%of projected deaths over two months in New York,while decreasing the peak daily death rate by 34e58%,absent other changes in epidemic *** very weak masks(20%effective)can still be useful if the underlying transmission rate is relatively low or decreasing:InWashington,where baseline transmission is much less intense,80%adoption of such masks could reduce mortality by 24e65%(and peak deaths 15e69%),compared to 2e9%mortality reduction in New York(peak death reduction 9e18%).Our results suggest use of face masks by the general public is potentially of high value in curtailing community transmission and the burden

关键词： Face mask Non-pharmaceutical intervention Cloth mask N95 respirator Surgical mask SARS-CoV-2 COVID-19

Development and Evaluation of the Mechanical Properties of Coconut Fibre Reinforced Low Density Polyethylene Composite

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Open Journal of Composite Materials 2022年第3期12卷 83-97页

作者： Ahmed Mohammed Bukar Abubakar Mohammed El-Jummah abba Alhaji Hammajam Department of Mechanical Engineering University of Maiduguri Maiduguri Nigeria

This research work developed and evaluated the mechanical properties of coconut fibre reinforced low density polyethylene (LPDE) composite material. The effect of fibre loading on the mechanical properties: tensile, flexural, and impact of the developed composite material have been investigated. Also carried out was the effect of fibre loading on the water absorptivity of the developed material. Sample categories of the developed composite were prepared by varying the fibre contents by weight at 0%, 10%, 20%, and 30%. The aim is to reduce the excessive waste disposal of LDPE materials that are largely found in the form of disposed water package materials (or pure water sachets) that usually affects the environment in the form of pollution. The water retting process was applied in extracting and cleaning fibre (or coir), while the mixed coir-LDPE (or developed composite material) was prepared by Compression Moulding Technique (CMT). The tensile and flexural properties were tested using Hounsfield Monsanto Tensometer (type w) while the impact properties were tested using the Charpy Impact testing machine. The microstructure of the composite was investigated using Scanning Electron Microscopy (SEM). The fractured surface morphology of the composite samples indicated a homogeneous mixture of the coir fibre and LDPE matrix. However, weak interfacial bonding between the coir fibre and LDPE matrix was also observed. The analysis of the water absorptivity showed that the developed composite materials have low water absorptivity at low fibre loading. However, at higher fibre loading, the water absorptivity increases significantly.

关键词： Coconut Fibre Low Density Polyethylene Composite Mechanical Properties Water Absorptivity

The Green Composites: Millet Husk Fiber (MHF) Filled Poly Lactic Acid (PLA) and Degradability Effects on Environment

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Open Journal of Composite Materials 2019年第3期9卷 300-311页

作者： abba Alhaji Hammajam Abubakar Mohammed El-Jummah Zahari Nur Ismarrubie Department of Mechanical Engineering University of Maiduguri Maiduguri Nigeria Department of Mechanical and Manufacturing Engineering Universiti Putra Malaysia Serdang Selangor Malaysia

This study provides an overview on green composites degradability. Practically, the main drawbacks of using natural fibers are their poor dimensional stability, degradability and high degree of moisture absorption. While, end use of product from natural fiber filled or reinforced composites has become subject of concern to material engineers and scientist. The major properties of natural fiber reinforced polymer composites are greatly dependent on the hydrophilic tendency and dimensional stability of the fibers used, morphology aspect ratio for long fiber, while voids for powder fibers. The effects of chemical treatments on cellulosic fibers that are used as reinforcements for thermoplastics were studied. The chemical source for the treatments is alkalization. The significance of chemically-treated natural fibers is seen through the improvement of mechanical properties. The untreated fiber composites degrade faster in municipal soil compared to treated fiber composites.

关键词： Degradability Composite Fibers Poly Lactic Acid Millet Husk

Integration of Remote Sensing and GIS in Studying Land Cover Trends and Conditions in the Middle Ziz Oasis,Morocco

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International Journal of Geosciences 2013年第7期4卷 1018-1023页

作者： Ali Essahlaoui abba Mohamed Eddahby Lhou Faouzi Mohamed Larabi Abdelkader Research Group“Water Sciences and Environmental Engineering” Laboratory of Geo-Engineering and EnvironmentFaculty of SciencesMy Ismail UniversityMeknesMorocco Laboratory LIMEN“Water Resources&Information Technology” Mohammadia School of EngineersRabatMorocco Department of Geology Faculty of SciencesDhar El MahrazFezMorocco

A better understanding of the changing patterns of land use and vegetation cover is a major concern for countries whose ecosystems are under severe degradation. Indeed, the dynamics of land have direct implications on the availability of natural resources. The palm grove, of oases of Errachidia region, plays an important role in the environmental, social and economic of this region. This research was conducted in the Ziz middle, which is affected by changes in the conditions and composition of land cover change. The application of remote sensing, geographic information systems and satellite imagery analysis with multi-temporal and spatial land use provides, for territorial managers, data updated and improved and a synopsis for effective management of natural resources. This research explores the possibility of identifying, monitoring and mapping land use change and land use on the dynamics of the palm grove in the past 40 years. Satellite images used are Landsat images and multi-temporal dates (MSS (1972), TM (1987), ETM + (2001, 2006 and 2011). These images were georeferenced and radiometrically corrected. In our study, the use of vegetation indices NDVI, SAVI and MASAVI, highlight the magnitude of changes in vegetation cover between 1972 and 2011. A regressive pronounced canopy is generally recognized in the Middle Ziz. This decline is explained by the combined effect of anthropic action (urbanization) and climatic conditions.

关键词： Morocco Remote Sensing GIS Ziz Watershed Dynamic of Land Use NDVI

Epidemiology of co-infections in pregnant women living with human immunodeficiency virus 1 in rural Gabon:a cross-sectional study

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Infectious Diseases of Poverty 2023年第4期12卷 83-92页

作者： Saskia Dede Davi Dearie Glory Okwu Marc Luetgehetmann Frederique Mbang abba Martin Aepfelbacher Lillian Rene Endamne Ayodele Alabi Rella Zoleko-Manego Ghyslain Mombo-Ngoma Saidou Mahmoudou Marylyn Martina Addo Michael Ramharter Johannes Mischlinger Centre of Tropical Medicine Bernhard-Nocht Institute for Tropical Medicine and I.Department of MedicineUniversity Medical Center Hamburg-EppendorfHamburgGermany German Centre for Infection Research Partner Site Hamburg-Lübeck-Borstel-RiemsHamburg-Lübeck-Borstel-RiemsHamburgGermany Centre de Recherches Médicales de Lambaréné LambarénéGabon Saskia Dede DaviDearie Glory OkwuFrederique Mbang AbbaAyodele Center for Diagnostics Institute of Medical MicrobiologyVirology and HygieneUniversity Medical Center Hamburg-Eppendorf(UKE)HamburgGermany Albert-Schweitzer Hospital LambarénéGabon Department of Parasitology Leiden University Medical CenterAlbinusdreefThe Netherlands Department for Clinical Immunology of Infectious Diseases and I.Department of Medicine University Medical Center Hamburg-EppendorfHamburgGermany

Background There is no recent epidemiological data on HIV infection in Gabon,particularly in pregnant *** close this gap,an HIV-prevalence survey was conducted among Gabonese pregnant women,followed by a cross-sectional case-control study in which the prevalence of various co-infections was compared between HIV-positive and HIV-negative pregnant *** Between 2018 and 2019,data for the HIV-prevalence survey were collected retrospectively in 21 Gabonese antenatal care centres(ANCs).Subsequently,for the prospective co-infection study,all HIV-positive pregnant women were recruited who frequented the ANC in Lambarénéand a comparator sub-sample of HIV-negative pregnant women was recruited;these activities were performed from February 2019 to February *** mean number of coinfections was ascertained and compared between HIV-positive and HIV-negative ***,the odds for being co-infected with at least one co-infection was evaluated and compared between HIV-positive and HIV-negative *** HIV-positivity was 3.9%(646/16,417)among pregnant women.183 pregnant women were recruited in the co-infection study.63%of HIV-positive and 75%of HIV-negative pregnant women had at least one *** was a trend indicating that HIV-negative women were more often co-infected with sexually transmitted infections(STIs)than HIV-positive women[mean(standard deviation,SD):2.59(1.04)vs 2.16(1.35),respectively;P=0.056];this was not the case for vector-borne infections[mean(SD):0.47(0.72)vs 0.43(0.63),respectively;P=0.59].Conclusions Counterintuitively,the crude odds for concomitant STIs was lower in HIV-positive than in HIV-negative *** change of magnitude from the crude to adjustedOR is indicative for a differential sexual risk factor profile among HIV-positive and HIV-negative women in this *** might potentially be explained by the availability of sexual health care counselling for HIV-positive women within the framework of the nati

关键词： HIV Cross-sectional study Pregnancy Sexually transmitted infections Gabon

An Approach to Energy Saving and Cost of Energy Reduction Using an Improved Efficient Technology

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Open Journal of Energy Efficiency 2015年第4期4卷 61-68页

作者： Abubakar Kabir Aliyu abba Lawan Bukar Jamilu Garba Ringim Abubakar Musa Faculty of Electrical Engineering Centre of Electrical Energy System Johor Bahru Malaysia Department of Electrical Engineering Faculty of Engineering University of Maiduguri Maiduguri Nigeria Federal Airport Authority of Nigeria Katsina Nigeria Department of Electrical Engineering Faculty of Engineering Ahmadu Bello University Zaria Nigeria

The electricity consumption in commercial places like universities has tremendously increased recently. Modern and advanced energy efficient appliances are highly needed to substitute the conventional ones. Energy saving is of great important instead of its wastage, as utilizing the energy efficiently reduces the cost of energy. Energy consumption varies for commercial building due to several factors such as electrical appliance usage, electrical appliance type, management, etc. Due to the advancement in technology, there are new emergence appliances that are of high efficiency and have less energy consumption. A case study is conducted on selected five tutorial rooms, level 4 buildings in the Faculty of Electrical Engineering 19 A, Universiti Teknologi Malaysia. The paper proposes new emergence equipments with high efficiency and less power consumption to replace the existing ones. A survey is conducted on the number of electrical appliances used for each of the tutorial rooms, time table for each tutorial room and the Tenaga Nasional Berhad pricing and tariff are taken into consideration in the analysis of the energy consumption and the cost of energy. This paper aims at reducing the amount of energy consumption by replacing the existing electrical equipments with high efficient electrical equipments;it also tends to reduce the cost of energy paid to the utility. By observing the results, it shows that the proposed efficient electrical equipments are more efficient, less power consumption and less cost compared to the existing electrical equipments.

关键词： Energy Efficiency Payback Period Energy Saving Energy Auditing Energy Efficiency Measures

The Synthesis of Diaminoanthraquinone Coloured Cross Linked Epoxy Resins and Their Application in Paint and Selected Polymers

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Open Journal of Applied Sciences 2014年第1期4卷 13-21页

作者： Zwahruddeen Muhammad Salisu Mohammed Kabir Yakubu Peter Obinna Nkeonye Hamza abba Department of Chemistry Ahmad Bello University Zaria Nigeria Department of Textile Science and Technology Ahmadu Bello University Zaria Nigeria National Research Institute for Chemical Technology (NARICT) Zaria Nigeria

Novel polymeric pigments were synthesized in xylene by cross linked epoxy resin with 1,4 and 1,5-diaminoanthraquinones, by varying weight fractions from 5% to 20% of the diaminoanthraquinone derivatives. FTIR, UV and solubility tests were carried out. The pigments were then used to colour PLA, PMMA, PE and also in emulsion paints using polyvinyl alcohol as binder. Their light fastness, surface drying time and surface hardening time were assessed. It was found that λmax of the 1,4-diaminoanthraquinone shifted towards longer wavelength after the cross linkage, in contrast to the 1,5-diaminoanthraquinone which suffered a blue shift. However in all the cases, the λmax was not affected by the weight fractions of the anthraquinones, but the absorptivity coefficients was significantly increased as the weight fractions of the anthraquinones increased. The light fastness properties of the coloured plastics varied from 4 to 7, indicating a trend of increase with the weight fractions of the anthraquinones. Similar observations were seen with the emulsion paints produced. In all the cases, the 1,4-diaminoanthraqunione produced better result.

关键词： Epoxy Resin Diaminoanthraquinone Derivatives Chromophore Pigments

Experimental Investigation on the Thermal Properties of Gypsum Plaster-Rice Husk Ash Composite

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Open Journal of Composite Materials 2022年第4期12卷 131-138页

作者： Nuhu Caleb Amulah Abubakar Mohammed El-Jummah abba Alhaji Hammajam Usman Ibrahim Department of Mechanical Engineering Faculty of Engineering University of Maiduguri Maiduguri Nigeria Department of Mechanical Engineering Faculty of Engineering Nigerian Army University Biu Nigeria Department of Mechanical Engineering Faculty of Engineering Ramat Polytechnic Maiduguri Nigeria

This experimental investigation aims at evaluating the thermal properties of rice husk ash (RHA)—filled gypsum plaster composite for potential applications, as insulating materials. The thermal conductivities of composites of gypsum plaster reinforced with RHA at 0%, 10%, 20%, 30%, and 40% volume fractions were determined experimentally using Lee’s disc method. The experimental results show that integrating RHA reduces the thermal conductivity of gypsum plaster and improves its insulation capacity. The results obtained from the experiments were compared with the Rule of Mixture Model, Maxwell Model, and Russell Model. It was observed that the thermal conductivities obtained from experiments and the theoretical models decreased with an increase in the volume fraction of RHA. The errors associated with the models with respect to experimental results are on the average of 28.7% for Mixture Rule, 31.6% for Russel Model, and 18.8% for the Maxwell Model. An agricultural waste like RHA can be beneficially used for the preparation of composites and, due to improved insulation capability, these composites can be used for applications such as insulation boards and sheathing, hardboard, ceilings of roofs, decorations, etc.

关键词： Rice Husk Ash Thermal Conductivity Gypsum Plaster Lee’s Disc Method Agricultural Waste