LAUTECH Journal of Engineering and Technology (LAUJET)
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SIGNAL FADING IN MOBILE COMMUNICATION:REVIEW
Get PDFFor six years of introduction of mobile communication in Nigeria though highly celebrated but has led to frustration on the part of customers/subscribers. These arise from myriads of poor interconnectivity to the signal fading. According to alberto et al., (2002) the ultimate goal of any communication (e.g. mobile) system is to provide error-free communication. This paper reviews different causes of signal fading experienced in mobile communication and how these problems can be combated in order to achieve reliable and effective information transfers. The reviews highlighted different methods in solving problems of fading in mobile communication. In this work, special focus on space diversity techniques was applied to combat fading in Nigeria. The exposition of this technique as well as different theories and calculations on path loss propagation and antenna spacing prediction were presented
EFFECT OF SOME PROCESSING VARIABLES ON ANGLE OF REPOSE AND COEFFICIENT OF FRICTION OF DRIED FERMENTED CASSAVA GRANULES
Get PDFThe angle of repose and coefficient of friction gain importance during food and handling, storage, processing and during process of designing these type of machines. Therefore, this study was conducted to investigate the effect of some processing variables; drying temperatures, dewatering pressure, size reduction and fermentation period on angle of repose and coefficient of friction of dried fermented cassava crumbles. A 24 factorial experiment was designed to investigate the experiment of these variables on the coefficient of friction and angle of repose. Each variables was examined at two levels; drying temperature (500c and 800c), dewatering pressure (5mpa and 10mpa), size reduction (hammer mill and renting in water) and fermentation periods (3 days and 5 days) yielding 16 experimental samples. The data were statistically analyzed using yates algorithm. The results obtained showed that the coefficient of friction on wood is higher than the coefficient of friction on steel. A change in drying temperature from 500c to 800c increase coefficient of friction by 19% on wood, while hammer milling the fresh cassava root before fermentation increase the coefficient of friction on steel by 7.5%. all the two, three, and four interaction effect were pulled together to test the significance at 1% level on steel ,while only drying temperature was significant at 1% level on wood. However, it was found that a change in fermentation days from 3days to five days reduces the angle of repose by 10%
ENERGY AND EXERGY ANALYSES OF A 220MW STEAM POWER PLANT
Get PDFThis study presents a thermodynamic analysis of a 220MW thermal plant using its design and operating data. The plant was simulated using HYSYS version 3.2 simulator software. The whole plant was sectionalised into three, each comprising of different units to determine the contribution of each unit to the efficiency and irreversibility of the plant. The maximum exergy loss of 168MW was in the boiler unit. The energetic and exergetic efficiencies were studied for different parameters such as turbine inlet temperature and pressure and fuel flow rate. The overall efficiency of the plant in terms of the first law of thermodynamics (energetic) was 24.1% and the second law analysis (exergetic) was 23.3%
DEVELOPMENT OF A TRAY DRYER FOR FRUITS AND VEGETABLES USING ZIG-ZAG AIR FLOW CONFIGURATION
Get PDF Post harvest losses in fruits and vegetables in developing countries like Nigeria is high due to poor storage and processing facilities. The use of cabinet dryer for dehydration of fruits and vegetables to improve their shelf life has a drawback of non-uniformity in drying along the length of trays. Hence an effort was made to solve this problem by using a zigzag air flow pattern configuration. A cabinet dryer of capacity21kg/batch was designed and developed. The dryer was tested with okra slices using zigzag air flow pattern configuration. At an air flow rate of 8.8m3/s and 600c it took about 9 hours to reduce the moisture content from 79.55% (w.b) to 6.03%(w.b). Results obtained showed that drying of the okra slices took place in the falling rate period. The drying efficiency of the dryer was found to be 70%
COMPARATIVE COST OF ANALYSIS OF ENERGY UTILIZATION FROM PHCN AND CAPTIVE POWER GENERATORS :- CASE OF A BEVERAGE INDUSTRY
No full textEnergy and its effective utilization are a paramount importance especially in this era of ever increasing demand for energy coupled with incessant interruption of power supply from the national grid. This study investigated the financial implications of incessant power outages by power holding company of Nigeria PHCN.
In this survey work, 7up bottling company Ilorin was used as a case study. For this fair assessment, data on energy used for three consecutive years i.e. 2004, 2005 and 2006 were collected. The sources of energy used were identified and evaluated. Specifically, the study compared the use of diesel through the use of 3 captive power generators and electricity supplied by PHCN. The data collected was processed and analysed. The cost of obtaining electrical energy from each source of supply was also calculated.
From the study, it was found out that, the percentage of PHCN to diesel energy used for years 2004, 2005 and 2006 were 61%,7.76%and 76.08% respectively. In the similar manner, the corresponding values obtained for percentage energy supplied by captive power generators (diesel) were 39%, 29.4%, and 23.92% for 2004,2005 and 2006 respectively. The study also revealed that, the average cost of the product using electricity supplied by PHCN and diesel during outages is N1.66 per litre of the products, while energy cost per litre of the product without interruption in supply by PHCN is N0.625. However, if the company had relied on diesel alone, the cost of product per litre would have been #2.498.
The study concluded that, though, electricity supplied by PHCN is cheaper, the company would have lost about 47.86% of its expected profit, if the company had depended solely on the power supplied by PHCN due to incessant interruption in her supply
LOAD MANAGEMENT AUTOMATION FOR ELECTRIC POWER SYSTEM OPERATION CONTROL IN NIGERIA
Get PDFThis research work is borne out of the interest to examine whether poor system operation control is what is responsible for power instability in Nigeria. The author researched into the system operation control of the power holding company of Nigeria centralized at the national control centre in Osogbo, Osun State, Nigeria. The control centre was visited and the operation control engineers interviewed on the operation mode of the system. The information obtained was analyzed based on the available theoretical guides and the level of success recorded so far by the method. The result of the analysis reveals that a virile and more reliable system for load management need be discovered for effective system operation and increased overall power availability. A load management automation system was designed which has the ability to compare the power allocated and the instantaneous power being consumed by the regional stations and then instruct any station that is consuming excess to cut down the amount of power corresponding to the difference within the limit of stability factor of the system at which the system automatically effect the command if no action is taken by the station. The system is believed to have what is required to prevent under-frequency system collapse
STORAGE STABILITY INDICES FOR MAIZE FLOUR
Get PDFMaize has maintained an important position in the dietary habits of many people in developing countries. It becomes low moisture food when processed into flour although it may still be susceptible to deleterious effect of exogenous (fungi, bacteria and insects) factors whose activities are climatic dependent after processing to flour. However ,one of the central areas of research in food processing is to ensure quality stability of food items or products in storage structures in order to conserve the nutritional composition and ensure its availability during the off season periods.
In attempts to ensure durability for maize flour, an analysis of moisture sorption data was undertaken to determine storage environment boundaries and moisture content levels at which the activities of exogenous factors will be inhabited for the flour under tropical practical storage conditions.
Consequently, water activity (aw) range of 0.5 to 0.61 and moisture contents of 6.66 to 7.22(%,dry basis) was estimated to ensure quality stability for maize flour, when storage structures are exposed to a tropical situation of temperature 270c to 400 c and water activity of 0.10 to 0.80. Bet monolayer moisture content varied between 3.47 and 4.59%, dry basis. The information can benefit stake holders in the maize processing sector to ensure the availability of high quality flour as a food ingredient in various forms and for industrial utilisation. This has high tendency to improve customer’s satisfaction and invariably provoke growth in the profit margin of the food processing factor
A WEIGHT CHECKER BASED ON DIGITAL TECHNIQUE
Get PDFRecent advances in digital computer and digital communications systems have led to a corresponding growing interest in digital weight techniques because of engineering advances offered by digital systems over its analogue counterpart. In this work, a digital weight checker liquid crystal display has been designed. The weight checker uses linear voltage differential transformer (LVDT) transducer in which position of displacement of spiral is proportional to the output voltage of transducer. Its accuracy and provision of constant impedance with infinite resolution makes it suitable for most applications. The system has its range from 0 to 20v corresponding to 0 to 20kg
THE QUALITY ATTRIBUTES OF GARI SOLD IN SOUTHWESTERN NIGERIA
Get PDFWork on the quality attributes of gari sold in southwestern Nigeria is reported .This was with a view to determine the extent to which the product has conformed to FAO standards. Ten samples of gari were randomly collected from five markets within the study area. The proximate composition and physical properties of the sample were determined using standard methods and data were analysed statistically. Results showed the crude fibre content ranged between 1.00-1.90%, moisture content 8.5-14.5%,ash content 0.24-1.97%,carbohydrate content 80.91%-87.4%,swelling capacity(29.70-57.40),water absorption capacity 3.85-6.10g/g, bulk density 2.39-2.79g/cm3 and ph 5.50-6.60. The statistical analysis of the physicochemical properties of the samples showed variations at p?0.05 level of significance in the properties of the samples within the same market . The crude fiber and moisture content of sample 1 and 4 respectively were not significantly different (p?0.05) from the recommended FAO standard at 95% confident level. The nutritional compositions of gari though highly variable fall for all the quality assessed were lower than the recommended FAO standard except for the moisture content of samples 2 and 6 which were significantly higher at 95% confidence level . In conclusion, there is the need ,for enlightenment of all stakeholders to ensure the attainment and maintenance of the minimum quality standards for gari sold in the markets as recommended by FAO
SIMULATION OF CASSAVA GRATING SYSTEMS FOR COTTAGE INDUSTRIES
Get PDFThe paper presents a simulation of cassava grating system. Processing of gari is a job for women but its techniques of operation have witness measures of changes in Nigeria. There exist versions of mathematical graters that are powered either by electric motors or small internal combustion engine. This paper describes mathematical model that simulates optimum cassava grating system for various processing cottage capacity and the power source used in the cottage industry. A computer program written in a basic language computes the appropriate size of grater for a given processing cottage capacity and the source of power required at various cost associated with grating operation ;fixed cost, variable cost and timeliness cost; system’s hour requirement; cost of the system and the least cost grating system. The model thus developed was tested on some selected gari processing cottage industries with varying processing cottage capacities. The cost requirement and the associated components of grating system for grating cassava at varying cottage processing capacity up to about 10 ha of crop service area was evaluated in Bida, Nigeria. The least cost involved for different system was determined