SciengtexOpen Journal System
Not a member yet
112 research outputs found
Sort by
Stability analysis of three-dimensional thick rectangular plate using direct variational energy method
Get PDFThis study investigated the elastic static stability analysis of homogeneous and isotropic thick rectangular plates with twelve boundary conditions and carrying uniformly distributed uniaxial compressive load using the direct variational method. In the analysis, a thick plate energy expression was developed from the three-dimensional (3-D) constitutive relations and kinematic deformation; thereafter the compatibility equations used to resolve the rotations and deflection relationship were obtained. Likewise, the governing equations were derived by minimizing the equation for the potential energy with respect to deflection. The governing equation is solved to obtain an exact deflection function which is produced by the trigonometric and polynomial displacement shape function. The degree of rotation was obtained from the equation of compatibility which when equated to the deflection function and put into the potential energy equation formulas for the analysis were obtained after differentiating the outcome with respect to the deflection coefficients. The result obtained shows that the non-dimensional values of critical buckling load decrease as the length-width ratio increases (square plate being the highest value), this continues until failure occurs. This implies that an increase in plate width increases the probability of failure in a plate. Hence, it can be deduced that as the in-plane load on the plate increase and approaches the critical buckling, the failure in a plate structure is abound to occur. Meanwhile, the values of critical buckling load increase as the span-thickness ratio increases for all aspect ratios. This means that, as the span-thickness ratio increases an increase in the thickness increases the safety in the plate. It also indicates that the capacity of the plate to resist buckling decreases as the span-depth ratio increases. To establish the credibility of the present study, classical plate theory (CPT), refined plate theory (RPT) and exact solution models from different studies were employed to validate the results. The present works critical buckling load varied with those of CPT and RPT with 7.70% signifying the coarseness of the classical and refined plate theories. This amount of difference cannot be overlooked. The average total percentage differences between the exact 3-D study (Moslemi et al., 2016), and the present model using polynomial and trigonometric displacement functions is less than 1.0%. These differences being so small and negligible indicates that the present model using trigonometric and polynomial produces an exact solution. Thus, confirming the efficacy and reliability of the model for the 3-D stability analysis of rectangular plates
Design and Fabrication of a One Stand Hot Tandem Rolling Mill
Get PDFOver the years, metalworking processes have emerged as a promising paradigm to modify materials' intrinsic workability and microstructural evolution. However, due to the stringent requirement of the state-of-the-art, non-uniform original grain structure of the metal ingot comprising large columnar grains growth in the direction of solidification, resulting in brittleness, weak grain boundaries, shrinkage, porosity, etc. remain a major bottleneck. This paper proposes a novel metalworking process to overcome this challenge. In particular, a one-stand hot tandem rolling mill that can break the grain structure and destroy the boundaries having uniform grain structures is developed. The proposed one-stand hot tandem rolling mill was constructed using 60 mm diameter work rolls, 150 mm diameter backup rolls, 120 mm diameter spur gears, a 3 hp electric motor, and a 50 mm diameter shaft. The components were installed, and the roll was fixed at a roll gap of 60 mm. Experimental investigations using a 65 mm aluminium sheet metal at a draft of 5 mm per pass after heating the metal sheet above its re-crystallization temperature were performed to validate the superiority of the proposed model. Available results indicate a robust improvement in the toughness, strength, and resistance of materials. Specifically, the results showed an efficiency of 86 % at an average draft of 4.3mm per pass
Effect of the production processed effluence on the environment: A case study of a typical brewery industry in Nigeria
Get PDFThis study investigates the effect of the production processed effluence on the environment, a case study of a typical brewery industry in Nigeria. Production process effluence remains a major environmental challenge in the brewing industry. The brewing industry generates different waste that affects the environment. In this study, waste samples including spent grain, hot trub, spent yeast, and wastewater was collected and prepared. The waste samples were analysed for moisture, carbohydrate, protein, fat, fibre, ash, and energy contents using proximate analysis. The wastewater sample was analysed for pH, temperature, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TSD) and total suspended solids (TSS). The proximate analysis results showed %moisture (7.2, 9.37 & 8.82), %protein (20.16, 60.14 & 42.70), %carbohydrate (23.11, 20.0 & 36.13), %fat (6.30, 3.0 & 3.22), %fibre (38.27, 0 & 6.4), %ash (3.51, 5.43 & 2.10) and energy value (205.73, 89.25 & 246.51kcal/100g) for spent grain, hot trub and spent yeast respectively. The physicochemical analysis of the wastewater showed the value of pH (8.7), temperature (28.17oC), COD (2050.24mg/L), BOD (1247.23mg/L), TSD and TSS (255.32mg/L). Disposal of these wastes creates serious problems for the environment. Methods of mitigation include application in animal feed and biogas production, and treatment of wastewater before disposal. Integrated brewery processes for sustainable production are recommended
Land Tenure Systems and Agricultural Productivity in Nigeria: A Case of Rice Production
Get PDFThis study examined land tenure systems and rice productivity in Nigeria. Primary data were used for the study. Data were collected with the aid of a well-structured questionnaire. A four-stage sampling technique was used to select a total sample size of three hundred and forty-nine (349) rice farmers for the study. Data were analysed using descriptive statistics, total factor productivity, and the Stochastic production frontier model. The study revealed that a large portion of the land (over 94%) used for rice production was acquired through inheritance mode of land acquisition and communal type of land tenure system widely practised. The result of total factor productivity indicated that 62.18% of the rice farmers were at a sub-optimal productivity level. The results of the stochastic production frontier function revealed that seed (P< 0.10), and fertilizer application (P<0.01) were the significant factors influencing the technical efficiency of rice production in the study area. Based on the findings, the study recommends that the current land use act and policy should be amended to prevent concurrent grabbing of agricultural land for non-agricultural purposes to enhance the availability and accessibility of land for agriculture
Analysis of critical imposed load of plate using variational calculus
Get PDFThis work studied the critical load analysis of rectangular plates, carrying uniformly distributed loads utilizing direct variational energy calculus. The aim of this study is to establish the techniques for calculating the critical lateral imposed loads of the plate before deflection attains the specified maximum threshold, qiw as well as its corresponding critical lateral imposed load before the plate reaches an elastic yield point. The formulated potential energy by the static elastic theory of the plate was minimized to get the shear deformation and coefficient of deflection. The plates under consideration are clamped at the first and second edges, free of support at the third edge and simply supported at the fourth edge (CCFS). From the numerical analysis obtained, it is found that the critical lateral imposed loads (qiw and qip) increase as the thickness (t) of plate increases, and decrease as the length to width ratio increases. This suggests that as the thickness increases, the allowable deflection improves the safety of the plate, whereas an increase in the span (length) of the plate increases the failure tendency of the plate structure
Design and Implementation of a Vehicle Tracking Mechanism using Wireless Network Infrastructure
Get PDFThis study presents the design and implementation of a vehicle tracking system with the goal of assisting victims of road accidents in obtaining prompt assistance from the rescue team. This is accomplished by sending tracking data to the rescue team's mobile equipment. The system was developed utilising available electronics components, installed in a vehicle. Accident situations were recreated by dropping loads of different sizes from a height and loads linked to a rope to shatter the glass on the automobile in order to determine the minimal impart energy necessary to break the glass and the likelihood of a catastrophic accident. If an accident occurs, the GPS engine sends the coordinates of the crash site to the rescue team's mobile equipment through the SIM900 module's GSM engine over a GSM frequency for tracking. The system's tracking accuracy was determined using a standard GPS device, the GERMIN GPSMAP78s, to get the GPS coordinates of the scene and tracking them using the Google map API. When tracked using Google map, the tracking information obtained, when compared with the GARMIN GPSMAP78s, were exact, indicating that proposed device is capable of transmitting accurate tracking information in a short period of time, thereby saving lives
An empirical investigation of lead-acid battery desulfation using a high-frequency pulse desulfator
Get PDFThe major cause of deterioration in lead-acid batteries is sulfation. There are patents on the use of high-frequency pulse desulfators to desulfate lead-acid batteries. Also, many products available in the market worldwide claim to use this technique to effectively desulfate lead-acid batteries that deteriorate due to sulfation. But there are little or no systematic studies to evaluate the performance of these products to know whether they do what their manufacturers claim. This research, therefore, aims at empirically evaluating one of such products. Four fully charged 100 Ampere-hour Valve Regulated Lead-Acid Gel batteries were discharged with an electronic-load battery discharger to ascertain their capacities. Thereafter, a high-frequency pulse desulfator was connected to desulfate the battery bank consisting of the four batteries. The battery bank was connected to be charged at the same time by a photovoltaic system. The desulfation experiment lasted for ten weeks but the batteries were tested to know their capacities after two, six, and ten weeks. The results show that the desulfation device works in desulfating lead-acid batteries as there are different degrees of improvement on the capacity of all the batteries. The percentage improvement in the capacity of the batteries is 89.5%, 75.9%, 1.6% and 1.4%, for batteries 1, 2, 3 and 4, respectively
Statistical prediction of the drying behavior of blanched ginger rhizomes
Get PDFARS-680 environmental chamber was employed in this study to determine the drying behavior of sliced ginger rhizomes. Blanched and unblanched treated ginger rhizomes were considered at drying temperature of 40 °C for a period of 2 – 24 h. Linear and non-linear regression analyses were employed to establish the correlation that exits between the drying time and the moisture ratio. Correlation analysis, root mean square error (RMSE) and standard error of estimate (SEE) analysis were chosen in selecting the best thin layer drying models. Higher values of determination coefficient (R2) show goodness of fit and lower values of SEE implies better correlation; and RMSE values were also utilized in determining the goodness of fit. The drying data of the variously treated ginger samples were fitted into the twelve thin layer drying models and the data obtained were fitted by multiple non-linear regression technique. Blanched treated sample exhibited a better drying behavior losing about 82.87 % moisture content compared with unbleached sample that lost about 62.03 % of moisture content. Two-term exponential drying model proved to be the most suitable model for predicting the drying behavior of ginger rhizome. The model exhibited high R2 values of 0.9349-0.9792 (which are close to unity) for both blanched and unbleached samples. Also, it recorded relatively low values of RMSE and SEE (3.6865 - 2.0896 and 3.6564-2.7486 respectively) for both treatments.  
Design and Fabrication of Centrifugal Blower using Locally Sourced Materials
No full textThis paper deals with the design and fabrication of a centrifugal blower. A backwards-curved blower was employed in the study, because the backwards-inclined blower is highly efficient, operates at approximately twice the speed of a forward-curved air blower, and is suitable for high-state pressure applications. The design consideration and analysis concerned within this study is for a single-stage centrifugal blower with capacity, Q (0.317m3/min) at a pressure, P (10,000Pa), head, H (61.87m), and shaft speed, N (1450rpm). The lowest air volumetric rate of 0.073 m3s-1 was obtained at closing the inlet (85%), the impeller speed (400rpm), and the air volumetric rate (0m3s-1) at closing the inlet (100%) for all the impeller speeds. The highest air volumetric (0.379m3s-1) was obtained at closing the inlet (0%) and impeller speed (960rpm). The impeller speed of 400rpm with a static pressure value of 47.03Pa, can be computed as the pressure value at 960rpm (i.e., 40.07Pa), indicating a 17% deviation (difference of 6.96 Pa). The highest total efficiency achieved is on closing the inlet of 50% and the impeller speed of 960rpm was attained at about 9.93%, whereas the lowest total efficiency on all the impeller speeds is achieved at the closing inlet of 0%. The result shows that the centrifugal blower was efficient over a wide range of flows. The blower provides a small unit of footprints with a good turn-down capacity
Development of a horizontal three bladed windmill with vortex tubes
Get PDFResearchers have been continuously searching for the most readily available means of producing electricity without any negative effect on the environment. Renewable source of energy like solar energy, hydro electric energy, biomass and wind energy has been considered as the alternative. Wind energy among others is rated the best renewable sources of energy because it’s level of environmental friendliness. In this paper, a horizontal windmill was designed, fabricated and its performance evaluated with two types of vortices and without a vortex. The component parts of the mills are towel, blades, shafts, base, tail vain and vortex. During the design of the windmill, consideration was given to the size, area of the blade and the blade material that produce maximum speed. The performance evaluation was carried out to compare the performance of the mill with the solid vortex, gap vortex and without vortex. The result of the evaluation reflects that the solid vortices have the highest wind speed irrespective of time of the day and with an optimum wind speed of 5.04 m/s. Also, the wind mill performed at a higher efficiency with the vortex compare to when it was running without vortex.