scholarly works

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Agricultural engineering education in Nigeria
(CIGR Journals, 2005-08) Mijinyawa, Y.
Early agricultural engineering services required on Nigerian farms were provided by civil engineers and agronomists some of who later retrained to form the first crops of Nigerian agricultural engineers. Agricultural engineering training was substantially done overseas until about the early 1960s when local opportunities started to be available. Agricultural engineering education started with training in farm mechanization laying emphasis on tractorization in the colleges of agriculture and polytechnics, and later expanded to cover all aspects of agricultural engineering. Agricultural engineering education in Nigeria is offered by the universities, polytechnics and colleges of agriculture. Ownership and funding of tertiary institutions include the federal and state governments, private individuals and religious organizations. Quality assurance is achieved through setting of minimum academic standards and occasional programme accreditations by the Nigerian universities commission, the national board for technical education and the council for the regulation of engineering in Nigeria. Agricultural engineers are engaged in virtually all sectors of the economy. This paper discuses the historical development of agricultural engineering education in Nigeria highlighting the entry requirements, training and regulations, professional bodies and the sectors where the products are making their contributions towards the national development. It concludes by calling on all stake holders to understand and appreciate the role of the profession in national development and give it the desired support.
Analysis of climatic factors for the selection of greenhouse glazing materials in Ilorin, Nigeria
(The Nigerian institution of Agricultural Engineers, 2011) Mijinyawa, Y.; Ajayi, S. A.
The effect of climate change in recent times has necessitated the need for a controlled environment for the cultivation of many crops which were hitherto cultivated under natural tropical condition. An appropriate method of accomplishing this is through the use of greenhouses which modify the environment to produce a micro-climate suitable for optimum plant growth. The successful use of greenhouses depends on the choice of appropriate glazing material. Tomatoes are precious crop demanded all year round but the production of which is being reduced by the effect of climate change. Desirous to increase the level of production, the study attempts to identify appropriate glazing material for greenhouse: for the production of tomatoes in Ilorin, Nigeria. Climatological data were collected from the Ilorin International Airport and analyzed in order to identify appropriate - covering materials for the development of greenhouse structures in Ilorin. Double layer polyethylene and white corrugated polyvinylchloride were the two glazing materials that have the lowest inner surface temperatures arid also satisfy the condition of heat load. To derive the maximum benefits of greenhouses, in addition to using these materials, Proper ventilation and shading of the greenhouses are recommended.
Appraiser of roadsid carpentry workshop in Iwo, Osun state, Nigeira
(2012) Adewole, N. A.; Bello, R. O.
Cardiovascular disease has been recognized as the world’s leading cause of death and disability accounting for about 40% of all human mortality. Cardiac arrhythmia is a name for a large family of cardiac behavior that shows abnormalities in the electrical behavior of the heart. Cardiac action potential depicts the electrical wave propagation within the heart. This work presented the mathematical modeling of the action potential within the human cardiovascular system. The electrical activity of the heart is best mathematically modeled by coupled systems of differentials equations consisting of ordinary differential equations(ODEs) and partial differential equations (PDEs), mainly reaction-diffusion types. These equations are non-linear and present themselves as stiff problem, hence, difficult to solve numerically. More so, whole heart simulation using these models is a challenging scientific computing problem due the complex geometry and small scale details of human heart. In this work, the bidomain model was adopted for the modeling due to its ability to reflect the actual wave propagation in the cardiac tissue. The bidomain model was coupled with FitzHugh-Nagumo’s ionic model and then discretized in time using the explicit forward Euler method. A 2-D Java-based computer program was developed to simulate the adopted model. The generated wave was compared with the theoretical standard. The obtained results are very useful in that they provided valuable information on cardiac arrhythmias
Assessing environmental impact of wastes from animal husbandary practices in a tropical environment
(Namik Kemal University, Faculty of Agriculture., 2011) Ewemoje, T. A.; Ewemoje, O. E.
Dumping of decaying wastes from animal pen as soil conditioners and pen wash water for irrigation is a common practice in developing countries. Releasing wastes to land and water may affect biological, chemical and physical properties of soils, plants and water. Hence, this paper assesses pollution effects of untreated animal husbandry wastes in tropical environment. Samplings were done on a daily basis over a 6-weeks period from the University of Ibadan Teaching and Research Farm which had been in operation for over 25-years. Assessing the degree of pollution was performed on the basis of Nitrate, Phosphorous, Potassium and Magnesium measurements in dump yard soil samples with average values ranging 0.38-0.40, 0.54-0.86, 0.16-0.37, and 0.58- 1.05 mg/I respectively. These values are higher than recommended FEPA standard, which makes the wastewater and slurries unsuitable for irrigated farming. Consumption of soluble nitrates and nitrites at this concentration could result to health problems such as methemoglobin. The pH of feacal discharge, wastewater, dump yard Soil being 6.5, 5.8, and 6.2 respectively were acidic. Heavy metals; Manganese and Iron ranged between 191-324 and 1.3-2.3 mg/kg respectively. Presence of heavy metals and trace elements in excess of FEPA/WHO recommended standards makes both feacal discharges and wastewater unsuitable for use as manure. Values of BODs, DO, and Temperature ranged 1350-1420mg/l, 0.55-0.75mg/l, and 27.0-0-33.5°C respectively. Observed high BODs and low DO values at an average temperature of 28-33°C fall short of the WHO water standard for irrigation, this is indicative of high polluting power of the wastewater.
Assessment of crop storage structures in Swaziland
(CIGR Journals, 2006-10) Mijinyawa, Y.; Mwinjilo, M.; Dlamini, P.
A survey was carried out to identify the types of crops popularly stored, the structures commonly used and problems experienced with produce storage in the Kingdom of Swaziland. Respondents included operators of government storage facilities, non-governmental organizations providing food relief, millers, large-scale farms, homesteads and artisans who fabricate metal tanks. Maize, the national staple food, was stored by all homesteads essentially for family consumption. It was the commercial staple crop, the major raw material for the millers and the produce commonly distributed as food aid by the non-governmental organizations. Significant quantities of groundnut, beans, sweetpotatoes, jugobeans and cowpeas were also stored. The crop storage structures found in use were metal silos, bags, platforms, cribs, metal tanks, concrete tanks, warehouses/rooms/old houses, metal/plastic drums, earthen/metal pots, plastic/metal buckets, bottles and tins. Metal silos and warehouses were the predominant structures used for large scale storage. The most common storage structure for maize by smallscale farmers was the metal tank as reported by 78.8% of respondents followed by cribs for both drying and storage (76.3%) and bags for the storage of maize, beans and groundnuts (65.7%) Moisture penetration and condensation, moulding, caking, insect infestation and rusting were some of the problems experienced with metal silos and tanks. In addition to these, the cracking of the solder used at the joints was a common problem with metal tanks. Bags often got torn by rodents that infested the produce. The absence of rodent guards in platforms and cribs encouraged rodent attack on produce stored in these structures. The use of inadequate –sized members and overloading often resulted in buckling and collapse of cribs and platforms. Losses of produce through these sources are a major problem. Remedial measures adopted towards solving these problems included the use of weevil and other types of tablets for produce storage, replacement of rusted and broken parts. The use of rodent glue and cats were also employed as control measures. About 48.2%,35.7%, 70.3% and 81.2% of the respondents expressed satisfaction with the use of bags, platforms, cribs and metal tanks respectively. These groups and those who rated them as unsatisfactory requested for intervention by way of arresting the problems identified with existing storage structures and provision of new ones. The use of rat guards on cribs and platforms should be emphasized; riveted joints on metal tanks should be appropriately spaced to provide structural stability and the amount of solder to minimise or eliminate cracking used.
Assessment of injuries in small scale sawmill industry of South Western Nigeria
(CIGR Journals, 2010-03) Bello, S. R.; Mijinyawa, Y.
Body injuries sustained in sawmill industry as a result of miII activities in Ondo, Oyo and Osun states in the Western part of Nigeria was investigated. Nigeria Sawmill Industries are essentially distributed between small, medium and large scale in the proportion of 81%: 13%: 6% respectively (RMROC, 2003). A survey involving the use of questionnaire, participatory approaches, on-the-spot assessments and interviews were used as tools for investigation. A total of 140 injury cases were recorded among 64 workers from investigated sawmills.The data collected were subjected to descriptive statistics. Results indicated that mill workers suffers highest injury rate of 83% while moving logs to mill from log yard or stack while timber stacking accident is the least at 36%. Other accident cases recorded include; log transport to the mill is 22%, milling operation 41% and maintenance accident 38%. Injuries occurring to body area include upper limb injuries (Neck and head, arm, wrist, hand and shoulder) 68%, back and lower back injuries 58%, and less prominent lower limb (Legs, knees and ankle) injuries at 13%.
Assessment of Kwara state tractor hiring unit
(The Nigerian institution of Agricultural Engineers, 2010) Mijinyawa, Y.; Adebayo, S.
A survey was undertaken to assess the Kwara State Tractor Hiring Unit using fleet of equipment, personnel and workshop facilities, and its impact on the farming populace in the state as assessment criteria. The study adopted the use of a questionnaire and interview schedules, focused group discussion and personal observation for data collection. Records available at the headquarters of the unit provided additional source of information. The unit has a total of 38 tractors which comprises of 29 Ursus 5312, six New Holland 5635, three heavy duty tractors, 22 disc ploughs, seven mouldboard ploughs, 18 disc harrows, eight disc ridgers, 10 trailers, two rice shellers, five multipurpose shellers, two maize shellers and one fourwheel drive jeep car. Majority (81%) of the equipment were functional, a few (13%) required minor repairs to be used on the farm and 6% were scraps. The unit has neither a workshop nor an implement shed thus exposing the machinery to inclement weather. Personnel in the unit are adequate but the maintenance culture is service driven. There has been a general increase in farm sizes since the introduction of the unit even though only a few farmers have been able to access the services rendered by the unit. Several reasons accounted for the limited beneficiaries from the activities of the unit prominent among which are inability to raise the cost of hiring, delay in service delivery, remoteness of farms and small holdings.The unit has great potentials for improving the agricultural productivity of the state if the equipment available can be effectively utilized. Towards achieving this, it is recommended that a functional workshop and implement sheds be provided at the headquarters and area offices, the activities should be decentralized while adopting a regular maintenance culture. As an agency of the government, there should be adequate funding by the state government.
Assessment of noise levels generated in some feed mills in Ibadan, Nigeria
(Emerging Academy Resources, 2012) Mijinyawa, Y.; Ogbue, C. R.; Arosoye, O. E.
The recent upsurge in the demand for livestock and poultry products in Ibadan has resulted in increased demand for feeds resulting in expanding and increasing feedmills. Feedmills generate substantial level of noise which could be injurious to workers and remedial measures are best taken with knowledge of the level of noise exposure. This study aimed at establishing the level of noise exposure of feed mill workers in Ibadan using a structured questionnaire and noise level meter to obtain relevant data. The noise levels generated in the feed mills ranged from 82.5 - 113.9 dB while most of the employees work between 8-10 hours daily for six days in a week and in some of the mills, the employees work all days of the week. The noise levels and exposure periods in many of the mills were above the code specification of a maximum noise level of 85dB over an 8-hour working period. There is no provision of noise control devices for the workers in most of the mills and in the few cases where they are provided, the workers rarely use them. Towards ensuring a safe working environment, noise control devices should be provided for all workers in the mills and their use enforced, machines should be regularly maintained so as to reduce warbling of components which increase the noise generated and employers should consider the reduction in working period in order to minimize the noise exposure period.
Assessment of noise levels generated in swine production units in Ibadan, Nigeria
(Asian Researching Publishing Network(ARPN), 2012-08) Mijinyawa, Y.; Alege, F. P.
The increase in pork consumption globally in recent times has led to a corresponding increase in pig production with more people being employed in the industry to provide the needed services. Pigs are known to generate a lot of noise which could constitute a potential health hazard and against which remedial measures must be taken. The establishment of the levels of noise generated in piggery production units and their possible consequences on the workers in such units was the main objective of this study. The research execution consisted of a simple survey among piggery workers to obtain information relevant to noise generation and effect; and physical measurement of the levels of noise generated in selected piggery farms in Ibadan, Nigeria. The survey revealed that workers spend between 3-6 hours daily within the units and wear no noise protective devices. The levels of noise generated in the farms ranged from 95-103 dB (A) and especially during feeding period and other activities. The duration of these noises which are mainly intermittent ranged from 30 to 150 minutes. These levels of noise and the periods for which they last are above the maximum levels of 99 dB (A) over a period of 19 and 140 minutes specified by NIOSH and OSHA respectively. Swine workers in Ibadan, Nigeria are exposed to excessive occupational noise hazards and remedial measures are desirable in order to protect them. The provision of Personal Hearing Protective Devices (PHPDs), adequate medical check-ups as well as use of personal noise dosimeters for the swine workers and good housing structures and facilities for the animals are recommended.
Assessment of pollution effect of direct use of poultry faecal waste in fish ponds
(2006) Ogedengbe, K; Ewemoje, T. A.
The performance of some environmental parameters in fish pond of 1.5ha at the National Institute For Freshwater Fisheries Research (NlFER) in New Bussa, Kainji dam resulting from the direct utilization of fresh poultry faecal waste as fish food was assessed along with three other ponds; South West Pond One (SWP1) using wheat offal, dough, maggot plus some poultry waste as fish feed and South West Pond Two (SWP2) using 100% concentrate, wheat offal and dough as fish feed. A Natural Water Pond (NWP) containing some fishes was also used as control pond along with SWPI and SWP2 to assess the pond at NIFER labeled Northern Pond ( NP). Environmental parameters of water quality in fish pond that are considered important in the assessment study are Dissolved Oxygen (DO); PH Value; Turbidity; Temperature, and 5-day Biological Oxygen Demand (BOD5). The temperature range is between 26-35C throughout the assessment work and this correspond with the optimum temperature for warm water fish growth. PH value of the study ponds fall within the excellent range. Also, turbidity in NP and SWP1 are very good thereby promoting effective ecosystem while SWP2 and NWP turbidity values are rather on the high side, hence photosynthesis is slightly affected. Dissolved Oxygen (DO) for the four ponds fall within 5-12 mg/l which is excellent for fish culture in ponds. BOD5 in the ponds is fairly high due to heavy manure loading with the exception of SWP2 which uses only concentrates as feed. NWP sources have the highest BODs value of 3.3 mg/l due to recharge from runoff water. From this assessment work it is evident that the direct utilization of poultry faecal waste as fish feed in fish ponds has great prospects if well monitored.
Assessment of the Edo State of Nigeria tractor hiring services
(CIGR Journals, 2006-03) Mijinyawa, Y.; Kisaiku, O.O.
A study was undertaken to assess the tractor-hiring unit of Edo state, Nigeria. The criteria used were fleet of equipment, personnel and workshop facilities and its impact on the farming populace in the state. The study adopted the use of a questionnaire and interview schedules. Among the information requested from the respondents were access to services rendered by the unit and increment in farm sizes. Records available at the headquarters and zonal offices of the unit provided additional sources of information. The unit has seven Steyr, 18 Fiat and nine Massey Ferguson tractors, eight ploughs, 17 harrows, seven tipping trailers, two boom sprayers, one fertilizer spreader, three maize shellers, two rotary slashers, one drilling machine, two ridgers and a pick-up van which are located in the various zones of the unit. Most of these equipment are either functional or require minor repairs to be used on the field. There is sufficient number of tractors but insufficient implements to fully utilize them. Workshop facilities and personnel are inadequate. The maintenance culture adopted is customer motivated. This is not a good practice as it has resulted in about 12% of the equipment being abandoned as scraps. There has been a general increase in farm sizes since the introduction of the unit. Some old time peasant farmers have been able to increase the sizes of their cultivated farmlands from below 2.5ha to between 5 and 10ha, while the aggressive new entrants have also been able to establish sizeable farms of over 25ha. This has considerably increased their economic fortunes. Some farmers have however not benefited from the activities of the unit. Three reasons account for this, and these are inability to raise the cost of hiring, the remoteness of their farms, which make them inaccessible to farm machinery and their small holdings, usually below 2.5ha, for which the use of farm machinery is unprofitable. The unit has great potentials for improving the agricultural productivity of the state if the equipment available can be effectively utilized. Recommendations made towards achieving this goal include adoption of regular maintenance culture; staff recruitment, retraining and motivation; upgrading of workshop facilities and establishment of new ones in the zones, and adequate funding by the state government.
Assessment of the noise level generated during ploughing and harrowing operations in Ibadan Nigeria
(Asian Researching Publishing Network, 2012-08) Mijinyawa, Y.; Akiyemi, B. A.
In an attempt to meet the food demand by the ever increasing human population, the use of machines in the performance of agricultural operations is increasingly being emphasized. Two of the most common operations for which machines are used on the farm are ploughing and harrowing. Tractor operators who perform these functions are known to spend long period of time working with the machines and various implements which generate substantial noise. Exposure to excessive noise could be harmful to human health if not regulated. The focus of this study was to investigate the level of noise to which tractor operators are exposed during ploughing and harrowing operations using MF260 and MF 265 tractors the noise level generated varied from 88.6 to 89.4dBA for ploughing and 86.5 to 88.4 dBA for harrowing. These levels are more than the recommended level of 85dB which indicate that the operators are under threat from noise and precautionary measures are desirable. A good maintenance culture especially the lubrication of parts to reduce noise, the use of ear protector such as ear muffs and plugs and cabins on tractors are recommended as ways by which the noise exposure could be minimized.
Assessment of the strength and sorption properties of Nigerian made wood plastic composites
(Research for development in Forestry, 2012-04) Adefisan, O. O.; Adesope, A.
The strength and sorption properties of Nigerian made wood plastic composites used as building components were assessed. Results obtained indicated that the composites generally had low strength values and were dimensionally stable. The wood plastic composites can only be used for non-structural purposes in both interior snd exterior applications
Assessment of tractor hiring services in Lagos State
(The Nigerian Society of Engineers, 2001) Akinoso, R.; Mijinyawa, Y.
Various agricultural mechanization techniques have been introduced to aid crop production. One of such is intensive use of tractors. Expensive capital and maintenance costs have limited the private ownership of tractors by Nigerian farmers. To promote the use and availability of tractors for farmers, tractor-hiring units were established. Tractor hiring units rent out tractors and other farm implements to farmers at affordable prices. Contrary to expectation, the aim of the program had been defeated due to technical laxity, poor management and the current economic situation of the country. Recognizing the necessity of tractor hiring units, efforts are made on ways of improving performances. Good organization and proper management are needed for effective operation.
Bamboo resource in Ibadan and environs; utilizations, opportunities and challenges
(Depatment of Forest Resources Management, University of Ibadan, Nigeria, 2009) Adewole, N. A.
This paper reports the mode of harvest, treatment, current uses, cost and constraints to production of furniture and allied product from bamboo as well as the marketing potentials of such products in lbadan, Oyo state, Nigeria and Environs, About 264 respondents comprising farmers, allied furniture makers, marketers and consumers, construction workers, researchers and forestry employees were selected from the eleven LGAs in Ibadan, Oyo State, Nigeria and Environs. Data collected was subjected to descriptive statistical analysis. Bamboo was found in homestead farms and forests. It is free for public use and traditional harvesting techniques still applied in the study area. Bambusa vulgaris, Schrad was found to by respondents to be the most prominent specie. They were also observed by respondents to be relevant in round and un-treated form for making local beds (18.2%), construction purpose (48.2%), as firewood (28.4%), stacking stand and others (5.2%). Large market opportunities exist for bamboo furniture and related products provided the impediment to its use. viz: lack of technological knowhow, equipment and enlightenment can be removed .This study established that bamboo resources in Ibadan and environ if properly harness can expand job opportunities and provide livelihood to large segments of rural/semi-urban populations in the study area.
Best distribution and plotting positions of daily maximum flood estimation at Ona River in Ogun-Oshun River Basin, Nigeria
(International Commission of Agricultural and Biosystems Engineering, 2011) Ewemoje, T. A.; Ewemooje, O. S.
The paper discusses how Normal, Lognormal, and log-Pearson type 3 distributions were investigated as distributions for modelling at-site annual. maximum flood flows using the Hazen, Weibull, and California plotting positions at Ogun-Oshun river basin in Nigeria. All the probability distributions when matched with Weibull plotting position gave similar values near the center of the distribution but varied considerably in the tails. The Weibull plotting position when matched with Normal, Log-normal and Log Pearson Type III probability distributions gave the highest Coefficient of determinations of 0.967, 0.987, and 0.986 respectively. Hazen plotting position gave minimal errors with the RMSE of 6.988, 6.390, and 6.011 for Normal, Log-normal, and Log-Pearson Type III probability distributions respectively. This implies that, predicting statistically using Hazen plotting position, the central tendency of predicted values to deviate from observed flows will be minimal for the period under consideration. Minimum absolute differences of 2.3516 and 0.5763 at 25- and 50-year return periods' were obtained under the Log-Pearson Type III distribution when matched with Weibull plotting position, while an absolute difference of 0.2338 at 100-year return period was obtained under the Log-Pearson Type 1II distribution when matched with California .plotting position. Comparing the probability distributions, Log-Pearson Type III distribution with the least absolute differences for all the plotting positions is the best distribution among the three for Ona River under Ogun-Osun river basin study location.
CAUSES OF ROOF FAILURE AND MODELLING OF PITCHED ROOF BLOW -OFF IN SOUTHWESTERN NIGERIA
(2011-08) ADESOGAN, S. O.
The increasing incidences of roof failures especially blow-off in recent times in Southwestern Nigeria has become worrisome in view of the damage done to adjacent structures and danger posed to building occupants and owners. There is the urgent need to devise methods to curtail failures and minimize the incidences of blow-off. This study was designed to investigate the causes and patterns of roof failures, recommend curtailment measures and develop a model to predict roof blow-off. Using purposive sampling technique, a survey of 3,780 roofs spread across Ekiti (450), Lagos (450), Ondo (360), Ogun (570), Osun (780) and Oyo (1,170) states was undertaken to establish the causes and patterns of roof failure. During the survey, timber samples at the point of roof construction (780), and those from failed (2000) and unaffected roofs (1000) were collected for moisture content determination in accordance with American Standard for Testing Materials (ASTM) D442 while the common nails used in construction were subjected to corrosion test in accordance with ASTM 1977. The integrity of nail joints was tested in accordance with ASTM 1761. Physical measurements of attic space and ambient temperatures, roof slopes, building dimensions and orientation were taken and combined with topography and courtyard effect to develop aerodynamic model to predict roof blow-off. The model was validated using post-model survey captured data. Data were analysed using descriptive statistics and regression analysis. Causes of roof failures included poor workmanship (30.5%), materials inadequacies (18.6%), design errors (14.8%), roof geometry (14.0%), topographical location (11.8%), age and environment (10.3%). Timber’s moisture contents were 12.0% to 24.0% during construction. Natural seasoning of these moisture contents to 7.0% in service, induced stresses on roof members. Temperature fluctuations between 20.0oC and 40.0oC promoted moisture condensation and dimensional changes in roofs’ wooden members. Poorly fitted joints reduced joint load from 103.1 ± 8.3 kg to 82.6 ± 5.1 kg. Nail diameter reduced from 21 ± 0.2 mm to 14.7 ± 0.3 mm within 90 days of exposure to water indicating potential reduction in joint strength. Blow-off occurred when ≤ 0; where MR and MO are resisting and overturning moments respectively. The model revealed that while gable roof could be adequate at the plain, hip roof with pitch angle between 40o and 60o would be appropriate on 5o and 10o slope hills respectively, with coefficient of multiple regression of 0.91 (p < 0.05). The model also revealed that optimum pitch angle was 55o and presence of courtyard reduced the wake and drag effects on roof. There were no statistical differences between the roof blow-off model predictions and post model survey data. The overturning moments for the rest were also greater than the resisting moment but they did not experience blow-off because of adequate anchorage of the sill. Roof failures in Southwestern Nigeria were caused by weakened joints resulting from corroded nails, interface gaps and wind effect. Remedial measures could include appropriate building orientation, proper anchorage, high pitch and adequate openings.
CAUSES OF ROOF FAILURE AND MODELLING OF PITCHED ROOF BLOW -OFF IN SOUTHWESTERN NIGERIA
(2011-08) ADESOGAN, SUNDAY OLUFEMI
The increasing incidences of roof failures especially blow-off in recent times in Southwestern Nigeria has become worrisome in view of the damage done to adjacent structures and danger posed to building occupants and owners. There is the urgent need to devise methods to curtail failures and minimize the incidences of blow-off. This study was designed to investigate the causes and patterns of roof failures, recommend curtailment measures and develop a model to predict roof blow-off. Using purposive sampling technique, a survey of 3,780 roofs spread across Ekiti (450), Lagos (450), Ondo (360), Ogun (570), Osun (780) and Oyo (1,170) states was undertaken to establish the causes and patterns of roof failure. During the survey, timber samples at the point of roof construction (780), and those from failed (2000) and unaffected roofs (1000) were collected for moisture content determination in accordance with American Standard for Testing Materials (ASTM) D442 while the common nails used in construction were subjected to corrosion test in accordance with ASTM 1977. The integrity of nail joints was tested in accordance with ASTM 1761. Physical measurements of attic space and ambient temperatures, roof slopes, building dimensions and orientation were taken and combined with topography and courtyard effect to develop aerodynamic model to predict roof blow-off. The model was validated using post-model survey captured data. Data were analysed using descriptive statistics and regression analysis. Causes of roof failures included poor workmanship (30.5%), materials inadequacies (18.6%), design errors (14.8%), roof geometry (14.0%), topographical location (11.8%), age and environment (10.3%). Timber‟s moisture contents were 12.0% to 24.0% during construction. Natural seasoning of these moisture contents to 7.0% in service, induced stresses on roof members. Temperature fluctuations between 20.0oC and 40.0oC promoted moisture condensation and dimensional changes in roofs‟ wooden members. Poorly fitted joints reduced joint load from 103.1 ± 8.3 kg to 82.6 ± 5.1 kg. Nail diameter reduced from 21 ± 0.2 mm to 14.7 ± 0.3 mm within 90 days of exposure to water indicating potential reduction in joint strength. Blow-off occurred when ≤ 0; where MR and MO are resisting and overturning moments respectively. The model revealed that while gable roof could be adequate at the plain, hip roof with pitch angle between 40o and 60o would be appropriate on 5o and 10o slope hills respectively, with coefficient of multiple regression of 0.91 (p < 0.05). The model also revealed that optimum UNIVERSITY OF IBADAN LIBRARY xviii pitch angle was 55o and presence of courtyard reduced the wake and drag effects on roof. There were no statistical differences between the roof blow-off model predictions and post model survey data. The overturning moments for the rest were also greater than the resisting moment but they did not experience blow-off because of adequate anchorage of the sill. Roof failures in Southwestern Nigeria were caused by weakened joints resulting from corroded nails, interface gaps and wind effect. Remedial measures could include appropriate building orientation, proper anchorage, high pitch and adequate openings. Keywords: Roof failure, Blow-off, Pitched Roof, Modeling, Southwestern Nigeria Word Count: 497 words
Challenges of sustaining wood industries and raw material supply in Nigerian depressed economy
(Forests and Forest Products Society, Department of Forest Resources Management, University of Ibadan, Nigeria, 2012) Adewole, N. A.
Engineering drives social, economic and human development and underpins our knowledge of society and infrastructures. It is a major factor in innovation and in the rise and fall of civilization. The challenge of sustaining wood industries and the supply of wood as raw material in Nigeria at this era of economic depression is considered an engineering challenge. It is believed that engineers are specifically trained to defy challenges in order to attain a set goal. Hence, this paper is devoted to reviewing impact of economic depression on wood supply to Nigerian wood sector and accompanying challenges to engineers. The way out was enumerated to include the development of alternative raw material from array of Non-Timber Forest Products (NTFPs) to complement wood supply, development of capacity for local fabrication of wood working machines and continue research on means of developing local methodologies and engineers are to also re-focused to adapt and domesticate modern technologies. If our nation can properly harness its resources and engineering, we would certainly be able to stay afloat of the present troubled economy.
CHARACTERISATION OF FUEL BRIQUETTES FROM Gmelina arborea (Roxb) SAWDUST AND MAIZE COB PARTICLES USING Cissus populnea GUM AS BINDER
(2012-11) OYEDEMI, T. I.
Large quantities of agricultural and mill residues which are generated annually in Nigeria constitute environmental health hazards. Densification of these residues which is a major way of converting them to high quality fuel has not been adequately studied in Nigeria. The objective of this study was to develop and evaluate a system for briquetting and combusting Gmelina arborea sawdust and maize cob particles. Gmelina arborea Sawdust (GS) was obtained from a small-scale sawmill in Ibadan while maize cobs were obtained from Oja – Oba market, Ibadan and milled. Moisture Contents (MC) and Bulk Densities (BD) of GS and Maize Cob Particles (MCP) were determined. Gum extracted from Cissus populnea stems was evaluated for its suitability as binding agent for fuel briquettes. The viscosity of the crude gum powder was determined at concentrations of 1-10 % (w/v). A manual briquetting machine and a briquetting stove were developed and evaluated. Briquetting of the GS and MCP was done at gum concentrations of 1-30 % (w/w) and pressure levels of 1.5-5.0MPa using 0.6 mm fine and 1.18 mm coarse particles. Briquette stability was measured in terms of linear expansion with time (1-10080 minutes) while the Compressive Strength (CS), Durability Index (DRI) and Water Resistance Index (WRI) were determined in accordance with ASABE standards. Briquette burn rate and thermal efficiency of the stove were determined using the standard water boiling test. Data were analysed using ANOVA. The MC and BD of GS (10.0 % and 150.0 kg/m3) were higher than those of MCP (9.0 % and 134.0 kg/m3). The gum yield of C. populnea was 1.40±0.05 % at 12.60±0.02 % MC. There was positive correlation between gum concentration and viscosity (R2=0.958). The piston press type briquetting machine produced 50.0 mm diameter and 60.0 mm long hollow cylindrical briquettes and gave a maximum through-put of 0.6 kg/h. The combustion chamber of the clay-lined steel stove accommodated a maximum of 5 briquettes. Minimum gum contents required for durable briquette production were 10.0% and 15.0% for GS and MCP respectively. Increase in binder concentration enhanced the linear expansion of both Gmelina arborea Sawdust Briquette (GSB) and Maize Cob Briquette (MCB) with the increase more pronounced in the MCB than GSB. There was significant difference (p<0.001) in the CS and WRI of the briquettes whereas there was no significant difference (p>0.05) between the DRI values. The strongest and most durable briquettes were obtained using fine particle size at a pressure of 1.5 MPa and 25.0% gum content. The burning rate of GSB was 0.800±0.003 kg/h while that of MCB was 1.000±0.018 kg/h. There was no significant difference (p>0.05) in their burn rate values. However, it took more time to boil one litre of water with GSB (22-24 min) than MCB (16-18 min). Maximum thermal efficiency of the stove was 38.0 %. Cissus populnea gum was suitable for the production of briquettes from Gmelina sawdust and maize cob particles. However, Gmelina arborea Sawdust Briquettes were stronger and more durable but less efficient in combustion than Maize Cob Briquettes.