Effect of Annealing on Machinability of Grey Cast Iron

This study investigates the influence of process parameter on machined cast iron under varying material strength and cutting conditions. The three process parameters considered in this study are spindle speed, feed rate and depth of cut. The cast iron bars were annealed and machined under both wet and dry cutting conditions. The signal-to-noise (S/N) ratio was used to analyze results generated, identify optimal process parameters (factors) and analyze the effect of these parameters on tool-tip temperature. Taguchi design of Minitab 18 was employed to optimize and analyze results. Results shows that the spindle speed was the most significant factor affecting tool-tip temperature reduction, followed by feed rate, while the depth of cut has least role to play on tool-tip temperature. Depth of cut and spindle speed both significantly influenced increment in material removal rate. The annealed cast iron bar had a better surface integrity than the Unannealed sample bars. Conclusively, the preferred condition for machining grey cast iron bar was annealed and wet machining condition

Design and Development of a Wear Testing Machine for Manufacturing Laboratories

Wear of parts during manufacturing processes is inevitable but controllable. Therefore, the critical study of wear in engineering components is vital because failure of components due to wear has resulted in loss of a great deal of fortune. This study was therefore an attempt to design and fabricate a wear testing machine, evaluate the performance of the machine and compare data obtained with existing ones. Materials for the various parts were carefully selected based on desirable properties and availability. Design calculations were made for the main shaft, compression spring, belt, pulley and electric motor. The post fabrication test was carried out on the machine to evaluate the performance of the machine and results gotten reported

PERFORMANCE EVALUATION OF ABESAN WASTEWATER TREATMENT PLANT

The performance of the Abesan wastewater treatment plant situated at the Abesan Low Cost Housing Estate, Abesan, Lagos had been evaluated. The treatment plant operates on biological treatment method (Activated Sludge Process) with an average wastewater inflow of 6 MLD has been considered for the case study. Thirty – six (36) grab samples of wastewater influent and effluent were collected over a period of six weeks during the dry and rainy seasons. The samples were analyzed for different wastewater quality variables. Average removal efficiencies of the measured parameters from the treated effluents were 96.3% for Chemical Oxygen Demand (COD), 93.3% for Biological Oxygen Demand (BOD), 92.4% for Total Suspended Solids (TSS), and 41.6% for Total Dissolved Solids (TDS) for the dry season. The rainy season average removal efficiency of the measured parameters were 96.8% for COD, 94.6% for BOD, 95.9% for TSS, and 38.6% for TDS. The values obtained for the dry season are lower than that obtained in the rainy season except for TDS. Most of the values of the effluent parameters exceeded the regulatory requirement of the Federal Environmental Protection Agency guideline for effluent limitation. The results obtained from this research conclude that regular routine de-silting and maintenance works of the plant be carried out to allow effective running of the plant

Vibrational properties of phonons in random binary alloys: An augmented space recursive technique in the k-representation

We present here an augmented space recursive technique in the k-representation which include diagonal, off-diagonal and the environmental disorder explicitly : an analytic, translationally invariant, multiple scattering theory for phonons in random binary alloys.We propose the augmented space recursion (ASR) as a computationally fast and accurate technique which will incorporate configuration fluctuations over a large local environment. We apply the formalism to $Ni_{55}Pd_{45}$, Ni_{88}Cr_12} and $Ni_{50}Pt_{50}$ alloys which is not a random choice. Numerical results on spectral functions, coherent structure factors, dispersion curves and disordered induced FWHM's are presented. Finally the results are compared with the recent itinerant coherent potential approximation (ICPA) and also with experiments.Comment: 20 pages, LaTeX, 23 figure

Phonons in random alloys: the itinerant coherent-potential approximation

We present the itinerant coherent-potential approximation(ICPA), an analytic, translationally invariant and tractable form of augmented-space-based, multiple-scattering theory in a single-site approximation for harmonic phonons in realistic random binary alloys with mass and force-constant disorder. We provide expressions for quantities needed for comparison with experimental structure factors such as partial and average spectral functions and derive the sum rules associated with them. Numerical results are presented for Ni_{55} Pd_{45} and Ni_{50} Pt_{50} alloys which serve as test cases, the former for weak force-constant disorder and the latter for strong. We present results on dispersion curves and disorder-induced widths. Direct comparisons with the single-site coherent potential approximation(CPA) and experiment are made which provide insight into the physics of force-constant changes in random alloys. The CPA accounts well for the weak force-constant disorder case but fails for strong force-constant disorder where the ICPA succeeds.Comment: 19 pages, 12 eps figures, uses RevTex

Isotope effect on the transition temperature TcT_c in Fe-based superconductors: the current status

The results of the Fe isotope effect (Fe-IE) on the transition temperature $T_c$ obtained up to date in various Fe-based high temperature superconductors are summarized and reanalyzed by following the approach developed in [Phys. Rev. B 82, 212505 (2010)]. It is demonstrated that the very controversial results for Fe-IE on $T_c$ are caused by small structural changes occurring simultaneously with the Fe isotope exchange. The Fe-IE exponent on $T_c$ [$\alpha_{\rm Fe}=-(\Delta T_c/T_c)/(\Delta M/M)$, $M$ is the isotope mass] needs to be decomposed into two components with the one related to the structural changes ($\alpha_{\rm Fe}^{\rm str}$) and the genuine (intrinsic) one ($\alpha_{\rm Fe}^{\rm int}$). The validity of such decomposition is further confirmed by the fact that $\alpha_{\rm Fe}^{\rm int}$ coincides with the Fe-IE exponent on the characteristic phonon frequencies $\alpha_{\rm Fe}^{\rm ph}$ as is reported in recent EXAFS and Raman experiments.Comment: 7 pages, 4 figures. The paper is partially based on the results published in [New J. Phys. 12, 073024 (2010) = arXiv:1002.2510] and [Phys. Rev. B 82, 212505 (2010) = arXiv:1008.4540

An Experimental Investigation of Influence of Relative Humidity on Thermal Performances of a Parabolic Trough Solar Concentrator

Solar energy is considered by many as a highly prospective alternative energy source due to its ability to meet a significant portion of the world's energy demand. The effectiveness of a solar concentrator depends on operational and atmospheric conditions. This paper presents an experimental analysis of the influence of humidity coupled with inclination angle and mass flow rate on the performance of a parabolic trough solar concentrator.  The parabolic trough solar collector underwent experimental testing at the LAUTECH engineering facility in Ogbomoso. It possesses a collector length of 2.1m, an aperture width of 1.2m, an adjustable rim angle of 75o, 90o, and 105o, a focal length of 30 cm, a 10-liter storage reservoir, and variable flow rates of 0.0004 m3/s, 0.0008 m3/s, and 0.0012 m3/s. Temperatures were measured using a 12-channel temperature recorder (SD data logger), solar radiation was measured using a solar meter, relative humidity was measured using an environment meter,  and water was used as the working fluid. Thermal performance analysis was conducted to ascertain the impact of relative humidity coupled with tilt angle, mass flow rate, and weather conditions on the solar concentrator's effectiveness. The findings reveals that at higher mass flow rates and a 90° tilt angle, the system has a greater thermal efficacy with weather elements such as solar intensity and relative humidity. Parabolic trough concentrators' performance is determined by the amount of solar intensity focused onto a receiver tube and high humidity in the air reduces the quantity of direct solar radiation that reaches the concentrator and high relative humidity reduces the thermal effectiveness of the system. While relative humidity may not be the main factor influencing the performance of a parabolic trough concentrator, its effects on thermal efficiency and heat exchange should be taken into account when designing and operating such solar thermal systems, especially in environments with varying humidity levels. Keywords Parabolic Trough Collector, Heat loss, Thermal efficiency, Humidity. DOI: 10.7176/JEES/14-2-05 Publication date:March 31st 202

ERGONOMICS INVESTIGATION OF MUSCULOSKELETAL DISORDER AMONG THE WORKFORCE OF WASTE MANAGEMENT INDUSTRY IN NIGERIA

The objective of this study is to undertake an Ergonomic Scrutiny of Desecrate Management Industry. Ten (10) employees of the parking and collection department of Kim Waste Management Authority (KWMA) were selected. Their activities were video and recorded while working and their different postures were analyzed using Rapid Entire Body Assessment (REBA) and Rapid Upper Limb Assessment (RULA). Result showed that 10% were at medium risk; 40% were at high risk and 50% were at very high risk for the workers in KWMA. It as discovered that workers are subjected to Musculoskeletal Disorder (MSDs) as a result of the postures adopted during the work process