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Tempering Heat Treatment Effects on Steel Welds

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Journal of Minerals and Materials Characterization and Engineering 2011年第8期10卷 755-764页

作者： A.V. Adedayo S.A. Ibitoye O.O. oluwole Materials Science and Engineering Department Obafemi Awolowo University Ile-IfeNigeria Mechanical Engineering Department University of Ibadan Ibadan Nigeria

This paper reports investigations made on the tempering heat treatment effects on steel welds. The properties of the weld investigated were hardness value and toughness. Micro examination of the samples was also done with optical microscopy. Four (4) different grades of steel rods in 10mm diameter were obtained. The range of the carbon contents of the steel rods was from 0.16 wt% C to 0.33 wt % C. From each grade of the steel materials, grooved specimen of about 150 mm were prepared. The grooves were then filled to create welds using arc welding. A set of the resulting welds were then subjected to tempering heat treatment. The hardness values and toughness of the welds were determined. The microstructural analyses of the welds were carried out as well. The results show that hardness and toughness were dependent on the carbon content. There was also significant microstructural modification due to heat treatment.

关键词： Welding Tempering Heat treatment Hardness Toughness Microstructure

Investigations into Optimization Models of Crude Oil Distillation Column in the Context of Feed Stock and Market Value

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Advances in Chemical Engineering and Science 2012年第4期2卷 474-480页

作者： Lekan T. Popoola Jamiu A. Adeniran Solomon O. akinola Department of Chemical Engineering Ladoke Akintola University of Technology Ogbomoso Nigeria Department of Computer Engineering Afe Babalola University Ado-Ekiti Nigeria Department of Petroleum and Chemical Engineering Afe Babalola University Ado-Ekiti Nigeria

This paper proposes optimization models of crude oil distillation column for both limited and unlimited feed stock and market value of known products prices. The feed to the crude distillation column was assumed to be crude oil containing naphtha gas, kerosene, petrol and diesel as the light-light key, light key, heavy key and heavy-heavy key respectively. The models determined maximum concentrations of heavy key in the distillate and light key in the bottom for limited feed stock and market condition. Both were impurities in their respective positions of the column. The limiting constraints were sales specification concentration of light key in the distillate [ ], heavy key in the bottom [ ] and an operating loading constraint of flooding above the feed tray. For unlimited feed stock and market condition, the optimization models determined the optimum separation [ and ] and feed flow rate that would give maximum profit with minimum purity sales specification constraints of light key in the distillate and heavy key in the bottom as stated above. The feed loading was limited by the reboiler capacity. However, there is need to simulate the optimization models for an existing crude oil distillation column of a refinery in order to validate the models.

关键词： Feed Stock Crude Oil Distillation Column Constraints Market Condition Reboiler Crude Composition Optimization

Factors Associated with Compliance with Infection Control Guidelines in the Management of Labour by Healthcare Workers at Mulago Hospital, Uganda

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Open Journal of Nursing 2019年第7期9卷 697-723页

作者： Grace Komuhangi Nwana Uchechukwu Kevin Ilori oluwole Felex Lydia Kabiri School of Nursing and Midwifery Clarke International University Kampala Uganda Department of Public Health Victoria University Kampala Uganda Department of Behavioral Science Islamic University of Uganda Kampala Uganda Department of Nursing College of Health Sciences Makerere University Kampala Uganda

Globally, infections acquired during childbirth contribute to one tenth of the maternal deaths annually [1] [2]. Factors predisposing to high risks of puerperal infections include non-compliance with Standard Precautions of Infection Control (SPIC), unhygienic births by unskilled birth attendants, multiple vaginal examinations, prolonged labour and premature rapture of membranes [1]. The main purpose of this study was to determine factors associated with compliance to standard precautions of infection control the management of labour by healthcare workers in Mulago Hospital to generate information, which may be used in infection control and prevention practices. A cross-sectional study utilizing a quantitative approach was conducted among 115 healthcare workers. Consecutive sampling was done to include respondents in the study. Data were collected by direct observation and researcher administered questionnaires. Data were coded and entered into the computer using SPSS version 20 with programmed quality control checks. Descriptive data analyses, frequencies, cross tabulations and logistic regression analysis were the major statistical methods used. 103 healthcare workers were involved in the study, where 74% were females. Overall compliance was at 52%, although it varied across domains. The majority of the healthcare workers (95.1%) did not comply with hand hygiene. Being a male was associated with low compliance scores a cross most domains. One of the hospital factors which was significantly associated with compliance to hand hygiene was having had an in-service training with p = 0.008 and p = 0.012 at multivariate analysis. Overall compliance to standard precautions of infection control was low compared to the Centre for Disease Control (CDC) recommendation. The findings in this study provide insight into individual and hospital related factors associated with compliance with standard precautions of infection control in the management of labour. There is an urgent

关键词： Compliance Standard Precautions of Infection Control Labour Healthcare Workers

High-performance multilayer WSe2 field-effect transistors with carrier type control

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Nano Research 2018年第2期11卷 722-730页

作者： Pushpa Raj Pudasaini akinola Oyedele Cheng Zhang Michael G. Stanford Nicholas Cross Anthony T. Wong Anna N. Hoffman Kai Xiao Gerd Duscher David G. Mandrus Thomas Z. Ward Philip D. Rack Department of Materials Science and Engineering University of Tennessee Knoxville USA Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge USA Bredesen Center for Interdisciplinary Research and Graduate Education University of Tennessee Knoxville USA Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge USA

In this stud high-performance multilayer WSe2 field-effect transistor （FET） devices with carrier type control are demonstrated via thickness modulation and a remote oxygen plasma surface treatment. Carrier type control in multilayer WSe2 FET devices with Cr/Au contacts is initially demonstrated by modulating the WSe2 thickness. The carrier type evolves with increasing WSe2 channel thickness, being p-type, ambipolar, and n-type at thicknesses 〈 3, - 4, and 〉 5 nm, respectively. The thickness-dependent carrier type is attributed to changes in the bandgap of WSe2 as a function of the thickness and the carrier band offsets relative to the metal contacts. Furthermore, we present a strong hole carrier doping effect via remote oxygen plasma treatment. It non-degenerately converts n-type characteristics into p-type and enhances field-effect hole mobility by three orders of magnitude. This work demonstrates progress towards the realization of high-performance multilayer WSe2 FETs with carrier type control, potentially extendable to other transition metal dichalcogenides, for future electronic and oDtoelectronic alpplications.

关键词： transition metaldichalcogenide field-effect transistors carrier control plasma treatment carrier mobility

Potentials of Arbuscular Mycorrhiza Fungus in Tolerating Drought in Maize (<i>Zea mays</i>L.)

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American Journal of Plant Sciences 2014年第6期5卷 779-786页

作者： Odunayo Joseph Olawuyi Adegboyega Christopher Odebode busayo Joshua Babalola Ezekiel Taiwo Afolayan Chidinma Pauline Onu Biology Department Federal College of Education Abeokuta Abeokuta Nigeria Department of Biosciences and Biotechnology Babcock University Ilisan-Remo Lagos Nigeria Department of Botany University of Ibadan Ibadan Nigeria

Maize is one of the most important cereal crops widely grown for food, feed, and fodder/forage throughout the world in a range of agroecological environments. Drought stress continues to haunt the maize farmers across south western part of Nigeria, thereby leading to low quantity of this essential staple food in the market. Efforts have been made to enhance the growths and yields in maize by investigating the influence of Arbuscular mycorrhizal fungus (Gigaspora gigantea) on the tolerance of maize to drought stress. The experiment was conducted in the teaching and research farm of Babcock University, Ilishan-Remo, Nigeria. The experiment was laid out in a complete randomized design with four replicates. Data were collected on eight morphological drought related characters. The objective of this research work was to evaluate the morpho-agronomic responses and potential of Gigaspora gigantea colonization in maize drought tolerance, and also to select parents in maize breeding for improved yield related components. The combined analysis of variance showed significant (P 0.05) treatment effect on majority of the traits evaluated. The treatments of Arbuscular Mycorrhiza Fungus (AMF) produced significant higher growth related traits suggesting that AMF treated plants had higher potential in influencing the tolerance to drought. Accession 3 was considered best for most of the traits studied and can be selected as parents in maize breeding for yield related components.

关键词： Maize Gigaspora gigantea Drought Stress Tolerance Growth Yields

Quantitative Evaluation of Cyber-Attacks on a Hypothetical School Computer Network

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Journal of Information Security 2019年第3期10卷 103-116页

作者： Akinjide A. akinola Adeyemi A. Adekoya Ayoade O. Kuye Abiodun Ayodeji University of Lagos Lagos Nigeria Virginia State University Petersburg VA USA University of Port Harcourt Port Harcourt Nigeria Nuclear Power Plant Development Directorate Nigeria Atomic Energy Commission Abuja Nigeria

This paper presents the attack tree modeling technique of quantifying cyber-attacks on a hypothetical school network system. Attack trees are constructed by decomposing the path in the network system where attacks are plausible. Considered for the network system are two possible network attack paths. One network path represents an attack through the Internet, and the other represents an attack through the Wireless Access Points (WAPs) in the school network. The probabilities of success of the events, that is, 1) the attack payoff, and 2) the commitment of the attacker to infiltrate the network are estimated for the leaf nodes. These are used to calculate the Returns on Attacks (ROAs) at the Root Nodes. For Phase I, the “As Is” network, the ROA values for both attack paths, are higher than 7 (8.00 and 9.35 respectively), which are high values and unacceptable operationally. In Phase II, countermeasures are implemented, and the two attack trees reevaluated. The probabilities of success of the events, the attack payoff and the commitment of the attacker are then re-estimated. Also, the Returns on Attacks (ROAs) for the Root Nodes are re-assessed after executing the countermeasures. For one attack tree, the ROA value of the Root Node was reduced to 4.83 from 8.0, while, for the other attack tree, the ROA value of the Root Node changed to 3.30 from 9.35. ROA values of 4.83 and 3.30 are acceptable as they fall within the medium value range. The efficacy of this method whereby, attack trees are deployed to mitigate computer network risks, as well as using it to assess the vulnerability of computer networks is quantitatively substantiated.

关键词： Cyber-Attack Quantitative Vulnerability Assessment Attack Trees Return on Attack Countermeasures

A Block-Preconditioned Inexact Linear Solver for Computing the Complex Eigenpairs of a Large Sparse Matrix

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Journal of Applied Mathematics and Physics 2018年第2期6卷 429-445页

作者： Richard Olatokunbo akinola Stephen Yakubu Kutchin Ayodeji Sunday Ayodele Kingsley Obiajulu Muka Department of Mathematics Faculty of Natural Sciences University of Jos Jos Nigeria Department of Mathematics University of Benin Benin Nigeria

In computing eigenpairs of the matrix pencil, one obtains a linear system of equations. In this work, we show how a block triadiagonal preconditioner in GMRES can be used to solve a large sparse unsymmetric system of equations inexactly using a fixed and decreasing tolerance. While the fixed tolerance solver converged superlinearly to the eigenvalue of interest, the decreasing one converged quadratically. This surpasses an earlier result which converged harmonically.

关键词： Preconditioner Superlinear Convergence Quadratic Convergence Eigenvalues

Empirical Evidence for a Descriptive Model of Principles of Information Security Course

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Journal of Information Security 2020年第4期11卷 177-188页

作者： Adeyemi A. Adekoya Aurelia M. Donald Somasheker Akkaladevi Akinjide A. akinola Virginia State University Petersburg VA USA University of Lagos Lagos Nigeria

The purpose of this study is to examine the nature and content of the rapidly evolving undergraduate Principles of Information/Cybersecurity course which has been attracting an ever-growing attention in the computing discipline, for the past decade. More specifically, it is to provide an impetus for the design of standardized principles of Information/Cybersecurity course. To achieve this, a survey of colleges and universities that offer the course was conducted. Several schools of engineering and business, in universities and colleges across several countries were surveyed to generate necessary data. Effort was made to direct the questionnaire only to Computer Information System (CIS), Computer Science (CS), Management Information System (MIS), Information System (IS) and other computer-related departments. The study instrument consisted of two main parts: one part addressed the institutional demographic information, while the other focused on the relevant elements of the course. There are sixty-two (62) questionnaire items covering areas such as demographics, perception of the course, course content and coverage, teaching preferences, method of delivery and course technology deployed, assigned textbooks and associated resources, learner support, course assessments, as well as the licensure-based certifications. Several themes emerged from the data analysis: (a) the principles course is an integral part of most cybersecurity programs;(b) majority of the courses examined, stress both strong technical and hands-on skills;(c) encourage vendor-neutral certifications as a course exit characteristic;and (d) an end-of-course class project, remains a standard requirement for successful course completion. Overall, the study makes it clear that cybersecurity is a multilateral discipline, and refuses to be confined by context and content. It is envisaged that the results of this study would turn out to be instructive for all practical purposes. We expect it to be one of the m

关键词： Benchmark Cybersecurity Descriptive Model Survey results Certifications Common-Body-of-Knowledge Empirical Evidence Principles of Information/Cybersecurity Course Tools Deployed

Computational Modelling of Cholera Bacteriophage with Treatment

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Open Journal of Epidemiology 2015年第3期5卷 172-186页

作者： Daniel S. Mgonja Estomih S. Massawe oluwole Daniel Makinde Mathematics Department University of Dar es Salaam Dar es Salaam Tanzania Faculty of Military Science Stellenbosch University Stellenbosch South Africa

This paper examines the computational modelling of cholera bacteriophage with treatment. A nonlinear mathematical model for cholera bacteriophage and treatment is formulated and analysed. The effective reproduction number of the nonlinear model system is calculated by next generation operator method. By using the next generation matrix approach, the disease-free equilibrium is found to be locally stable at threshold parameter less than unity and unstable at threshold parameter greater than unity. Globally, the disease free equilibrium point is not stable due to existence of forward bifurcation at threshold parameter equal to unity. Stability analysis and numerical simulations suggest that the combination of bacteriophage and treatment may contribute to lessening the severity of cholera epidemics by reducing the number of Vibrio cholerae in the environment. Hence with the presence of bacteriophage virus and treatment, cholera is self-limiting in nature.

关键词： Cholera Bacteriophage Treatment Vibrio cholerae Equilibrium Stability Effective Reproduction Number