ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT

1-7

Authors: M Isiaka

This study was carried out to assess the quality of solar dried tomato flakes by determining its safety, nutritive value and wholesomeness. In order to determine the safety of the dried tomato, the bacteria and mould loads were determined using three sliced thicknesses of solar energy dried samples. Two different types of agar culture media were used to culture the released bacteria and mould cells. Ascorbic acid and proximate tests were carried out to determine the nutritional value of the dried product as compared with the fresh products. To determine the wholesomeness of the dried product, the organoleptic properties in terms of colour (appearance) and taste (flavour) were examined and compared with those of three other tomato products. Results showed that the mean viable bacteria count ranged from 9 to 13 colonies/ml with the 25 mm thickness giving the highest value, followed by 20 mm thickness and the least value was from 15 mm thickness. The same pattern was observed for mould infection. The infection range for the three slice thicknesses was within the recommended safe limit of ≤30 colony forming unit/ml for bacteria and mould counts in food products. There was substantial drop in ascorbic acid content from 28.2 mg/100 g for fresh ripe tomato to as low as 13.6 mg/100 g for dried tomato of 25 mm slice thickness and highest value of 20.6 mg/100 g for 20 mm thickness. The results for organoleptic properties showed the tomato dried by solar energy dryer is superior to the other tomato products.

17-26

Authors: P Y Dibal

This paper deals with the design of a MOD-6 synchronous counter using VHDL (VHSIC Hardware Description Language). The VHSIC stands for Very High Speed Integrated Circuit. Using this approach, the behaviour of the counter is the most important aspect of the design. In the first section, the paper introduced counters in general, and their areas of specialization, like frequency synthesizers. The synchronous counter was then introduced, stating the behaviour of the flip-flops that make the counter. The modulus of a counter was defined. In the second section, the Xilinx ISE (Integrated Simulation Environment) and the ISIM (Integrated Simulator) were presented and briefly described with their respective snapshots. The structure of a typical VHDL code was presented, which included LIBRARY, ENTITY, and ARCHITECTURE. Each of these structures was then briefly described. The main work in this paper was then presented. The count sequence steps were stated as 120→3→5→7→6→4"> . VHDL was used to model the counter to count through six steps, outputting count values according to desired steps. The hardware implementation of the design was presented, where the implementation process was described, with a supporting diagram, followed by the floor-planning technique, in which the PORTS described in the VHDL design were assigned to the physical pins of the XC3S1000 FPGA (Field Programmable Gate Array) chip. The final steps of the hardware implementation process were then presented. These include bitstream generation and download to target device. The third section of the paper presented the results obtained. Simulation/timing results of the design were presented, showing the output of the counter at each state with respect to the clock signal. The result of the synthesis of the design was presented, which showed the FPGA area with the exact location of the pins on the FPGA chip. Finally, the fourth section presented the conclusion arrived at, in respect of the design that was carried out.

37-50

Authors: C J Ejieji, M Olayaki-Luqman

Eleven years of daily wind records were analyzed for the estimation of available wind energy for water pumping at three selected locations in Northern Nigeria, namely Jos, Kano and Sokoto. This formed the basis for investigating the economics of the use of an imported small wind pump under a deregulated energy market environment. The estimated available energy for water pumping at the installation height of 9m was 190 kwh/m2/yr for Jos, 225 kwh/m2/yr for Kano and 348 kwh/m2/yr for Sokoto. The monetary value of the available wind energy was considered as saved energy cost. The saved cost was obtained in terms of the unsubsidized cost of the petrol and diesel that an internal combustion engine (ICE) would consume to produce energy equivalent to the available wind energy. At the prevailing interest and inflation rates of 21.96 % and 12.1% respectively, and unsubsidized prices of N 131.32/l and N 140.23/l for petrol and diesel respectively, investment in the wind pump was not found to be economically competitive relative to using a pump with ICE prime mover at the three locations unless the cost of the pump was subsidized. For Sokoto, the estimated subsidy for initial cost of the wind pump required for the investment to be competitive relative to the use of a pump driven by a petrol ICE was 16%. Relative to a pump driven by a diesel ICE, the required subsidy was 24%. The corresponding subsidy estimates for Kano were 48 % and 51 % respectively. For Jos, it was 56% relative to the use of a pump driven by a petrol ICE and 60 % relative to that driven by a diesel ICE. Considering the potential environmental and social and environmental benefits however, subsidy support by government for local manufacturing of the pumps was recommended since shipping cost and custom tariff constituted over 36% of the initial cost of the wind pump.

69-81

Authors: I Mustapha, M K Dikwa, B U Musa, M Abbagana

Many Solar PV modules exhibit significant loss in their expected performance due to variations in weather conditions such as ambient temperature and solar irradiance which result in inaccurate prediction of the module performance in the field. Obviously, the Standard Test Conditions (STC) and the Nominal Operating Cell Temperatures (NOCT) do not represent real operating conditions of PV module at the site of installation. This paper evaluates the performance of commercially used polycrystalline solar photovoltaic module KD 315 under Maiduguri-Nigeria weather conditions. The model of the PV module was implemented using a MATLAB program and the model parameters are evaluated using daily data of temperature and solar irradiance obtained from Maiduguri for a period of one year. Simulation results confirm that current generated is directly proportional to solar irradiance and is almost independent of temperature. The voltage of the module decreases by about 0.5% per degree centigrade temperature increase. It was found that the power produced by the panel is dependent on the solar irradiance and ambient temperature. The manufacturer’s maximum power of 315 W was achieved during the sunniest month. Thus the photovoltaic module exhibited good performance in the region under study.

90-95

Authors: I S Aji, E James, A Ejovwoke, D A Mshelia

Labor input in manual cassava chips processing is very high and product quality is low. This paper presents the design and construction of an electrically operated cassava slicing machine that requires only one person to operate. Efficiency, portability, ease of operation, corrosion prevention of slicing component of the machine, force required to slice a cassava tuber, capacity of 10 kg/min and uniformity in the size of the cassava chips were considered in the design and fabrication of the machine. The performance of the machine was evaluated with cassava of average length and diameter of 253 mm and 60 mm respectively at an average speed of 154 rpm. The machine produced 5.3 kg of chips of 10 mm length and 60 mm diameter in 1 minute. The efficiency of the machine was 95.6% with respect to the quantity of the input cassava. The chips were found to be well chipped to the designed thickness, shape and of generally similar size. Galvanized steel sheets were used in the cutting section to avoid corrosion of components. The machine is portable and easy to operate which can be adopted for cassava processing in a medium size industry.