ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT

1-12

Authors: G M Ngala, M B Oumarou, A B Muhammad, M Shuwa

Solar chimney power plant (SCPP) is a renewable energy facility that converts the potential energy in the Sun into kinetic energy and subsequently into electrical energy. The problem of global warming and electricity generation/distribution in Nigeria cannot be over emphasized; however with the vast land in the semi arid region and the potentials of the above technology, high prospects exist for solar chimney as it is a decentralized form of power generation. The aim of this paper was to theoretically evaluate the performance of the solar chimney power plant in semi-arid region of Nigeria, and estimate the amount of electrical energy that can possibly be generated. A mathematical model was used to estimate the amount of power generated, and determine the relationship between various meteorological and physical factors to the power produced. A solar chimney power plant with collector diameter of 700 m and chimney height of 700 m can produce up to 3000 MW of electricity.

24-36

Authors: A K Aremu, A S Duduyemi

Some relevant engineering properties of Àbèèrè (Picralima nitida) seeds are needed for the design of its processing equipments. The geometric, gravimetric and frictional properties of Àbèèrè seed in the moisture content ranges of 7.98% - 47.77% (wb) were investigated. The average length, width, thickness, arithmetic and geometric mean diameters, sphericity, surface area, volume, true and bulk densities and angles of repose increased from 28.76 – 30.75mm, 16.18 – 19.62mm, 5.75 – 7.15mm, 16.90 – 19.17mm, 13.81 – 16.11mm,0.48 – 0.53, 600.94 – 817.83mm2, 443.00 – 717.92mm3, 2.49×10-3 – 2.60×10-3g/mm3, 1.14×10-3 – 1.50×10-3g/mm3and 27.97o – 30.26o respectively as the moisture content increased from 7.98% to 47.77%. However, values for porosity decreased from 0.54 – 0.42. The static coefficient of friction of Àbèèrè increased linearly over the three material surfaces – plywood, stainless steel and glass – with increasing moisture content from 0.445 – 0.468, 0.286 – 0.384 and 0.357 – 0.389 respectively. The steel surface had the lowest static coefficient of friction whereas the plywood gave the highest value at all moisture content levels. The regression models developed for all the physical properties of the seeds had high coefficient of determination, R2.

50-61

Authors: U M B Mala, M H Ibrahim, S O Kassim, M A Terab

Due to the increasing use of images in industrial process, financial institutions, medical and military application, there is every need to achieve secure transmission and storage of digital images. Various methods have been investigated and developed to protect image data for personal privacy and encryption is probably the most obvious solution. This work presents an improvement on the existing Advanced Encryption Standard (AES) Algorithm by implementing it on VB.NET framework. Encryption time of AES was considered to be very long, especially when processing images using encryption key. Therefore, eliminating the use of encryption key will lead to reduced encryption time. Finally, comparisons made of the Improved AES Algorithm with the latest successful Algorithms in image encryption indicates that the Algorithms of Gamil and Pareek encrypts a Kilobyte of image at an average encryption time of 0.7 milliseconds and the average encryption time of the Improved AES is 0.3 milliseconds. This shows that the improvement has been successful.

77-88

Authors: A Dahiru, Muhammad Bashir Aminu

One of the challenges facing construction procurement performance is the failure to determine the risk related factors limiting its success. These risk factors can cause a significant increase in the procurement cost leading to an increase in the overall project cost. The purpose of this study is to identify and evaluate the risk factors influencing construction procurement performance with a view to achieve the overall project performance. The objectives are to establish a relative significance index score for the most important risk factors limiting the procurement performance of the projects. A self administered questionnaire was employed to the construction industry professionals for responses. A total of 78 questionnaires were distributed to these professionals (architects, quantity surveyors, engineers, and contractors) but 62 were returned and analyzed using influential index and later ranked in order of importance. Results of the analysis indicate a disparity in terms of ranking of the factors influencing construction procurement performance. Corruption related risk, conflict of interest, ineffective project technical feasibility, and lack of commitment to transparency were found to be the most significant factors limiting construction procurement performance. Communication barriers and unconfidential tender evaluation process were found to be the low weighted risk factors. The findings can serve as a supportive mechanism for risks management in public construction procurement management. Therefore, construction procurement personnel at all levels of government may find this study relevant, while improving construction procurement performance in the country. It is recommended that construction procurement system should be focused on risks related to corruption, conflict of interest, and effective technical feasibility for improving the overall project performance.

103-113

Authors: P Y Dibal, D E Mshelia

This paper presents the design of a lock-in amplifier micro-ohmmeter using Proteus VSM. To achieve a seamless complex design, it is usually better and easier to break the design task into stages and this paper used that approach in Proteus to achieve the task of designing the micro-ohmmeter. The paper introduced the concept of a micro-ohmmeter and its constituent segments. Each segment was analyzed at component level with appropriate mathematical equations. The result and implementation of each analysis was verified through simulation in Proteus. The paper makes a comparison between the theoretical operation of the circuit and the operational result obtained via the simulation. The comparison confirms that the design of the circuit using Proteus was successful due to the fact that the simulation results matched that of theory.

120-130

Authors: M M Odewole, O A Adesoye, S K Oyeniyi, A O Isiaka

A machine for dehulling fluted pumpkin seed (Telfairia occidentalis) was developed. The main objective of developing the machine was to provide a better substitute to traditional methods of dehulling the seed which contains edible oil of high medicinal and nutritional values. Traditional methods are full of drudgery, slow, injury prone and would lead to low and poor outputs in terms of quantity and quality of dehulled products. The machine is made of five major parts: the feed hopper (for holding the seeds to be dehulled before getting into the dehulling chamber), dehulling chamber (the part of the machine that impacts forces on seeds thereby causing fractures and opening of seeds coats for the delivery of the oily kernels), discharge unit (exit for oily kernels and seed coats after dehulling), the frame (for structural support and stability of all parts of the machine) and electric motor (power source of the machine).The development process involved design of major components (shaft diameter (20 mm), machine velocity (7.59 m/s), power requirement (3hp single phase electric motor) and structural support of mild steel angle iron), selection of construction materials and fabrication. ANSYS R14.5 machine design computer software was used to design the shaft and structural support; while other components were designed with conventional design method of using design equations. The machine works on the principle of centrifugal and impact forces. Performance evaluation was carried out after fabrication and 87.26%, 2.83g/s, 8.9% and 3.84%were obtained for dehulling efficiency, throughput capacity, percentage partially dehulled and percentage undehulled respectively.