Design and Testing of a Cupola Furnace for Micheal Okpara University of Agriculture, Umudike

The need to recycle and productively reuse the abundant scrap metals in the country led to this paper. The task therein focused on a design aimed at the modi cation and re-fabrication of an existing cupola furnace in-situ at the Engineering Workshop of Michael Okpara University of Agriculture, Umudike (MOUAU) in Abia State, Nigeria. From the design, 0.00129m3/s volume of air supplied to the cupola furnace with an available volumetric capacity of 0.01378m3 at the rate of 32963.58W/m2 produced an estimated melting heat of 89113.5KJ/hr with a melting rate of 123kg/hr for the complete combustion of the fuel utilizing a mass of charge of material of 123kg. These parameters as compared for the already existing cupola at the Workshop gave the volume of air supplied as 0.000257m3/s at the rate of 285973.05W/m2 with the melting rate capacity of 67952.25kJ/hr and a melting rate of 101.2kg/hr, respectively. Consequently, the fuel analysis performed showed that the stoichiometric air/fuel ratio obtained was 11.39, while the eciency of the cupola furnace was calculated as 67% against the 50.02% value of the already existing one in-situ at the Workshop. This represents an increase of about 16.98% in eciency from the already existing and modi ed cupola used as standard for the present study. It is thus recommended that this novelty design be used as a foundation for building bigger furnaces and for the sensitisation of students' awareness in foundry technology and practices.Keywords: furnace lining, refractory materials, critical radius of insulation, furnace fuel, heat transfer, cupola zone

Energy and Economic Losses Due to Constant Power Outages in Nigeria

This study assesses the economic implication of electricity self-generation in Nigeria. In this regard, energy and exergetic utilization efficiencies of 19 representative generators and gas turbines from Afam power station were assessed based on real data obtained through survey of companies, oral interview, individuals and also experiments carried out during the course of the study. Energy and exergy analyses were conducted to study the variations of energy and exergetic efficiencies for petrol, diesel and natural gas generators. Energy and exergetic efficiencies for the generators were found to be the same. Energy/exergetic efficiencies were in the range of 0.19% to 16.20% and the average energy/exergetic efficiencies for diesel, petrol and natural gas generators were found to be 9.59%, 4.43% and 0.27%, respectively. The results of the analysis also show that the economic losses associated with self-generation of electricity is high. Compared to an average Power Holding Company of Nigeria, tariff of N12.20/kWh, the average costs of self-generation for petrol, diesel and natural gas generators were found to be N46.30/kWh, N47.74/kWh and N6.44/kWh, while the average cost rates of exergy losses were found to be N1,076.34, N114,165.34 and N238,810.76, respectively. The study also suggested some solutions to Nigeria’s constant power outages. Therefore, it is expected that the results of this study will be helpful to an average Nigerian in understanding the Naira losses associated with the use of generators. These will also assist energy policy makers and governments at all levels in developing highly applicable and productive planning for future energy policies in Nigeria

Plasma Perturbations and Cosmic Microwave Background Anisotropy in the Linearly Expanding Milne-like Universe

We expose the scenarios of primordial baryon-photon plasma evolution within the framework of the Milne-like universe models. Recently, such models find a second wind and promise an inflation-free solution of a lot of cosmological puzzles including the cosmological constant one. Metric tensor perturbations are considered using the five-vectors theory of gravity admitting the Friedmann equation satisfied up to some constant. The Cosmic Microwave Background (CMB) spectrum is calculated qualitatively.Comment: 20 page

On fractionality of the path packing problem

In this paper, we study fractional multiflows in undirected graphs. A fractional multiflow in a graph G with a node subset T, called terminals, is a collection of weighted paths with ends in T such that the total weights of paths traversing each edge does not exceed 1. Well-known fractional path packing problem consists of maximizing the total weight of paths with ends in a subset S of TxT over all fractional multiflows. Together, G,T and S form a network. A network is an Eulerian network if all nodes in N\T have even degrees. A term "fractionality" was defined for the fractional path packing problem by A. Karzanov as the smallest natural number D so that there exists a solution to the problem that becomes integer-valued when multiplied by D. A. Karzanov has defined the class of Eulerian networks in terms of T and S, outside which D is infinite and proved that whithin this class D can be 1,2 or 4. He conjectured that D should be 1 or 2 for this class of networks. In this paper we prove this conjecture.Comment: 18 pages, 5 figures in .eps format, 2 latex files, main file is kc13.tex Resubmission due to incorrectly specified CS type of the article; no changes to the context have been mad

Stochastic Gravity: Theory and Applications

Whereas semiclassical gravity is based on the semiclassical Einstein equation with sources given by the expectation value of the stress-energy tensor of quantum fields, stochastic semiclassical gravity is based on the Einstein-Langevin equation, which has in addition sources due to the noise kernel. In the first part, we describe the fundamentals of this new theory via two approaches: the axiomatic and the functional. In the second part, we describe three applications of stochastic gravity theory. First, we consider metric perturbations in a Minkowski spacetime, compute the two-point correlation functions of these perturbations and prove that Minkowski spacetime is a stable solution of semiclassical gravity. Second, we discuss structure formation from the stochastic gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in the gravitational background of a black hole and describe the metric fluctuations near the event horizon of an evaporating black holeComment: 100 pages, no figures; an update of the 2003 review in Living Reviews in Relativity gr-qc/0307032 ; it includes new sections on the Validity of Semiclassical Gravity, the Stability of Minkowski Spacetime, and the Metric Fluctuations of an Evaporating Black Hol

Increasing Iron and Zinc in Pre-Menopausal Women and Its Effects on Mood and Cognition: A Systematic Review.

Iron and zinc are essential minerals often present in similar food sources. In addition to the adverse effects of frank iron and zinc-deficient states, iron insufficiency has been associated with impairments in mood and cognition. This paper reviews current literature on iron or zinc supplementation and its impact on mood or cognition in pre-menopausal women. Searches included MEDLINE complete, Excerpta Medica Database (EMBASE), psychINFO, psychARTICLES, pubMED, ProQuest Health and Medical Complete Academic Search complete, Scopus and ScienceDirect. Ten randomized controlled trials and one non-randomized controlled trial were found to meet the inclusion criteria. Seven studies found improvements in aspects of mood and cognition after iron supplementation. Iron supplementation appeared to improve memory and intellectual ability in participants aged between 12 and 55 years in seven studies, regardless of whether the participant was initially iron insufficient or iron-deficient with anaemia. The review also found three controlled studies providing evidence to suggest a role for zinc supplementation as a treatment for depressive symptoms, as both an adjunct to traditional antidepressant therapy for individuals with a diagnosis of major depressive disorder and as a therapy in its own right in pre-menopausal women with zinc deficiency. Overall, the current literature indicates a positive effect of improving zinc status on enhanced cognitive and emotional functioning. However, further study involving well-designed randomized controlled trials is needed to identify the impact of improving iron and zinc status on mood and cognition

Interaction imaging with amplitude-dependence force spectroscopy

Knowledge of surface forces is the key to understanding a large number of processes in fields ranging from physics to material science and biology. The most common method to study surfaces is dynamic atomic force microscopy (AFM). Dynamic AFM has been enormously successful in imaging surface topography, even to atomic resolution, but the force between the AFM tip and the surface remains unknown during imaging. Here, we present a new approach that combines high accuracy force measurements and high resolution scanning. The method, called amplitude-dependence force spectroscopy (ADFS) is based on the amplitude-dependence of the cantilever's response near resonance and allows for separate determination of both conservative and dissipative tip-surface interactions. We use ADFS to quantitatively study and map the nano-mechanical interaction between the AFM tip and heterogeneous polymer surfaces. ADFS is compatible with commercial atomic force microscopes and we anticipate its wide-spread use in taking AFM toward quantitative microscopy

Stochastic Gravity: Theory and Applications

Whereas semiclassical gravity is based on the semiclassical Einstein equation with sources given by the expectation value of the stress-energy tensor of quantum fields, stochastic semiclassical gravity is based on the Einstein-Langevin equation, which has in addition sources due to the noise kernel.In the first part, we describe the fundamentals of this new theory via two approaches: the axiomatic and the functional. In the second part, we describe three applications of stochastic gravity theory. First, we consider metric perturbations in a Minkowski spacetime: we compute the two-point correlation functions for the linearized Einstein tensor and for the metric perturbations. Second, we discuss structure formation from the stochastic gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in the gravitational background of a quasi-static black hole.Comment: 75 pages, no figures, submitted to Living Reviews in Relativit

Overweight and obesity status from the prenatal period to adolescence and its association with non- alcoholic fatty liver disease in young adults: cohort study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/16/bjo16199-sup-0005-ICMJES2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/15/bjo16199-sup-0012-ICMJES12.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/14/bjo16199_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/13/bjo16199-sup-0010-ICMJES10.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/12/bjo16199-sup-0002-TableS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/11/bjo16199.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/10/bjo16199-sup-0007-ICMJES4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/9/bjo16199-sup-0008-ICMJES5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/8/bjo16199-sup-0006-ICMJES3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/7/bjo16199-sup-0003-AppendixS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/6/bjo16199-sup-0011-ICMJES11.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/5/bjo16199-sup-0013-ICMJES13.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/4/bjo16199-sup-0014-ICMJES14.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/3/bjo16199-sup-0001-FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/2/bjo16199-sup-0009-ICMJES6.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/1/bjo16199-sup-0004-ICMJES1.pd