EUSpace
Not a member yet
791 research outputs found
Sort by
Parametric and Quantitative Analysis on the Development of Shell and Tube Heat Exchanger
Get PDFThe importance of mini shell and tube heat exchangers (STHEs) in industrial and other engineering applications cannot be underestimated. Hence, based on the problems associated with the design of STHEs, a mini STHE was developed for transfer of heat between two fluids without mixing on the laboratory scale using locally available materials and technology based on an optimized LMTD technique. The performance of the heat exchanger was assessed and evaluated to determine the optimum combination of design parameters. Copper was utilized for the tube side fluid due to its higher thermal conductivity and anti-microbial property, while galvanized steel was used for the shell side fluid due to its cost and corrosion resistance. Parametric studies were carried out on STHE design parameters to obtain an optimal design for efficiency and effectiveness after relevant design considerations. Experimental results were validated with quantitative models, and it was discovered that both DellBelaware and Engineering Science Data Unit (ESDU) approaches produced the optimal results required for the selection of shell side and tube fluid film coefficients, respectively over other correlations. In conclusion, the values of parameters of interest were also presented after rigorous mathematical calculations at optimal level and probable recommendations were later mad
Performance and Security of Group Signature in Wireless Networks
Get PDFA Group signature protocol is a cryptographic scheme that decouples a user identity and location from
verification procedure during authentication. In a group signature scheme, a user is allowed to generate
signatures on behalf of other group members but identity and location information of the signer is not known by
a verifier. This ensures privacy, authentication and unlinkability of users. Although group signature is expensive
to implement, its existential anonymity, non-repudiation and untraceablility properties make it attractive
especially for resources-constrained devices in wireless network. A general group signature scheme usually
contains six basic phases: setup (or key generation), join, message signing (or signature generation), signature
verification, open and user revocation. In this paper, an evaluation of the performance of group signature based
on three of the phases mentioned above is considered and its security in wireless networks examined. The key
generation, signing and verification algorithms are implemented in Java 8. A proof of security of group signature by implication is also presented
Genotoxicity Evaluation of Landfill Solid Waste Leachates from a Waste Dumpsite in Lagos State, Nigeria using the Allium cepa Assay
Get PDFThe management of municipal landfill’s leachate is considered one of the most
significant environmental issues. Potential mutagenic and genotoxic effects of
solid waste leachates (SWL) were investigated using the Allium cepa root meristematic cells assay technique. In Allium root growth inhibition test, experimental onion bulbs were cultivated in various concentrations of the SWL and
distilled water was used as a negative control. The root tips from the treated bulb
were processedby orcein squash technique after 72 h. The mean lengths of root
bundles were obtained andeffective concentration (EC) values calculated. Some
of the physicochemical properties of the WL were also determined. The A. cepa
assay was carried out at concentrations of 0.05, 0.1, 2.0, 5, 10, 20, 50 and 100%
of the WL. There was a statistically different (p < 0.05), concentrationdependent inhibition of onion root growth and mitotic index, and induction of
chromosomal aberrations in the onion test. The results of the physicochemical
analysis revealed that the concentrations of some parameters were above the
maximum permissible limit set by the world health organization (WHO) and
could partly be correlated with the toxicity of wastewater. The landfill leachates
pose a risk to human health and the environment in general. Hence, ecotoxicity/genotoxicity assays would be useful in leachate risk assessment when coupled
with physicochemical analysis
Adoption of Massive Open Online Courses (MOOC) for Librarians' Professional Development in Africa
Get PDFLibrarian development is the process of constantly strengthening professional attainment, broadening academic knowledge, and enhancing skills. This chapter explores how Massive Open Online Courses (MOOCs), can be used as continuing professional development of a librarian. This chapter narrates how MOOCs may offer a librarian an opportunity to upgrade their skills or further their education. It explains the benefits and challenges of the adoption of MOOCs for continuing professional development in developing countries and how this can be applied in developing economies. The major benefits of MOOCs to librarians are to help in professional and personal learning, but most librarians who wish to experience progressive career-development are yet to ascertain this fact. The chapter concludes that librarians have the opportunity to leverage this technology to improve their relevant professional skills in the 21st century. It is also established that the adoption and use of MOOCs among professional librarians in Africa is low as in advanced countries
Cassava Bio-Ethanol Development in Nigeria and Its Food Security Considerations
Get PDFCritics of Nigeria’s cassava bio-ethanol production policy have argued that its development will have severe food security implications in the country. Our paper takes a critical look at cassava feedstock and landmass requirements necessary to meet the policy focus. We also considered the cassava production targets of the national cassava production targets and their landmass requirements. We determined that if production targets alone were the basis for analysis, then cassava utilisation as feedstock in the biofuel initiative would compromise food security as production requirements are about 17-25% of cassava production targets in the country. However, if the basis of analysis was landmass utilisation, cassava utilisation as bio-ethanol feedstock would not necessary compromise food security as less than 2% of arable land and less than 4% of cultivated land would be required to produce the cassava required to meet bio-ethanol feedstock requirements. In fact the total land area required to produce the feedstock and meet national production targets are less than 10% of arable land and 20% of cultivated land. Hence government and other key player of the cassava production system can be encouraged to open up the available land for greater production of cassava for the market
Numerical Simulation and Modeling of UNSA91060 for Heat Transfer in Four-Stroke ICE Cylinder Head
Get PDFThis work concerns heat transfer principles in four strokes ICE from modeling and simulation standpoint.Heat transfer is one of a number of indispensable tools in studying of ICEs, due to its influence on decisive parameters of operation like temperature and pressure inside the cylinder. It is safe to say that modeling of the engine heat transfer is among the most complex problems for engineers. Application of numerical methods to predict the heat transfer in a cylinder of reciprocating ICEs is a process of high importance, which was recognized from the earliest stages of their development. This is done to examine performance optimization and design improvement in order to meet nowadays demands exhibited on the engines. This present study focuses on a 3-D transient state temperature distribution analysis on a gasoline engine model via formulated of models, simulating using FEM in-built in the COMSOL Multiphysics software 4.3a to determine the temperature distribution and gradient of the engine cylinder head model. The number of degrees of freedom solved for were 32685 in 383 s (12 minutes, 20 seconds) in the mesh optimization. From the result obtained it was discovered that the heat transfer in the combustion chamber of the ICE varies with time. Thus, it took the engine 10 minutes to complete a cycle vis-a-vis transfer of heat after combustion and that the heat transfer starts after 30 seconds of combustion. In addition, the temperature of the cylinder dropped from 1273.2 K to 301 K over a period of 10 minute.Self-sponsore
Corporate Social Responsibility in Conflict Management: The Perspective of the Niger Delta, Nigeria
No full textThe perennial conflict in the Niger Delta region of Nigeria has taken its toll on the smooth operation of oil companies, their peaceful coexistence with their host communities and by extension, the Nigerian economic survival, which depends largely on oil revenues. The impact of oil exploration activities has resulted in negative consequences on the environment and human life manifest in massive destruction and disruption of farming activities, unproductiveness of farmlands, reduction of fishing in the waterways and increased poverty of the inhabitants of the oil producing communities. These have led to negative reactions by host communities, leading to conflicts characterized by protests, kidnapping of oil expatriates and destruction of oil facilities. All of these could have been avoided or mitigated through appropriate corporate social responsibility (CSR) in view of the fact that it is a veritable strategy for managing conflicts between oil companies and their host communities. It is on this basis that this paper examines the place of CSR as a strategy which oil companies can adopt for managing conflicts in their Niger Delta host communities. The paper conceptualizes conflict, identifies its types and causes, discusses the concept of CSR and examines its application by oil companies in managing the conflicts in the Niger Delta. The paper concludes that although the oil companies are engaging in forms of CSR as a strategy to manage the crisis, such CSR programmes have been inadequate, ineffectively planned and implemented. It recommends a proactive approach to planning and executing CSR programmes and projects as well as identification of key stakeholders in order to involve them in the planning and execution of such programmes
Numerical analysis of lift-based in-pipe turbine for predicting hydropower harnessing potential in selected water distribution networks for waterlines optimization
Get PDFThe research models and simulates in-pipe turbine hydropower harnessing possibilities in water distribution networks of the sites under investigation considering in-pipe lift-based spherical turbine. The
hydrofoil profile of the turbine is generated using National Advisory Committee for Aeronautics
(NACA) aerofoil generator. Consequently, a Computer-Aided Design (CAD) model of the in-line liftbased spherical turbine is then developed and simulated, based on the peak and lean period of the volumetric discharge rates using commercial computational fluid dynamics software (Autodesk Simulation
CFD ). The time series of power outputs are computed from the time series of discharge variations. A liftbased spherical turbine with NACA 0020 foil cross-section appears appropriate for extraction of energy in
the water distribution pipelines. Furthermore, the minimum and maximum percentage head loss due to
insertion of the turbine is about 1.94% at lean flow rates and 9.70% at the peaks for 250 mm pipelines. The
available power was found out to depend on the density of the turbine blades material, flow rate, and the
pipe diameter. The estimated lean and the peak electric power are about 415 and 1663 W, respectively,
using aluminium foil blades while stainless steel foil produces about 242 and 1080 W in the 250 mm
pipe
MECHANICAL STRENGTH DETERMINATION OF CRUSHED STONE AGGREGATE FRACTION FOR ROAD PAVEMENT CONSTRUCTION (CASE STUDY: SELECTED QUARRIES IN WESTERN NIGERIA)
Get PDFIn this research work, the mechanical strength of crushed stone aggregate fractions for road
pavement construction in Western Nigeria was assessed. Samples of crushed stone aggregates
were collected from nine (9) representative quarries spread across the states in Western
Nigeria.The physical and mechanical properties of the aggregates were evaluated. The results
were then compared with the specifications in international standards (BS and ASTM
Standards). All the aggregate samples met the required limit for Loose Density, Water
Absorption, Aggregate Crushing Value (ACV) and Aggregate Impact Value (AIV) tests.
Aggregates samples from Samchase, Kopek, CCECC and SaliwaYetidipe quarries have flakiness
indices exceeding the permissible limit (29.5%, 25.7%, 27.9% and 34.5% respectively). Hi-Tech
and Western quarries samples have elongation indices of 44.5% and 40.3% respectively which
are higher than the permissible limit. The two samples that failed Aggregate Abrasion Value test
(AAV) are Hi-Tech and Western quarries, having 30.8% and 30.4% respectively. These two
aggregates samples have AAV less than 35% which means they are still good for pavement
construction only if the appropriate guidelines are followed (since any aggregate with AAV more
than 35% is deemed weak for pavement construction). The study concluded that aggregates from
Julius Berger quarry have the highest mechanical strength
A study on the relationship between cash-flow and financial performance of insurance companies: Evidence from a developing economy
No full textThe study examines the relationship between cash flow and financial performance of
insurance companies in a developing economy – Nigeria. Using time series data for the period 2009-2014,
twenty seven listed insurance firms in Nigeria were selected as sample size. The study uses both descriptive
and inferential statistics to determine the relationship among the variables. It also employs the series of
diagnostic tests to ensure stability of the time series used as well as to ensure the model meets the assumption
of ordinary list square. The findings reveal that cash flow was observed to determine insurance firms’
financial performance and is statistically significant. Cash flow from operating activities was observed to
significantly increase financial performance of insurance companies in the period examined. Cash flow from
financing activities was found to increase the financial performance of the sampled insurance firms, but was
not statistically significant. The size of the insurance company did not increase the financial performance of
the insurance firms and was also not statistically significant. The paper recommends that managers in
insurance firm should regularly change the extent at which cash is spent to avoid negative cash flow position
as well as financial crisis. Adequate investment appraisal is really a concern that insurance firms need to
take into consideration when customers are taking up insurance coverage. The costs have to be weighed
against the benefits accruable thereto