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Plastic pollution causes serious environmental issues and endangers the health of humans and animals in both land and aquatic environments. Despite the fact that Nigeria produces hundreds of tons of plastic waste every day, a greater proportion still finds its way back into the ecosystem because only a small portion of it is recycled. Nigeria's growing production of single-use plastics and careless disposal of plastic waste into the land and ocean are the main causes of the country's growing plastic pollution problems.. For this reason, recycling and reusing plastics is necessary to lessen the harmful effects that plastic utilization has on both human and the environment.. Plastics can be recycled into filaments used in 3D printing also known as additive manufacturing. In this study, a plastic filament extrusion machine for waste plastic was designed and developed with the aim of recycling high-density polyethene, thereby lessening the negative environmental effects that come with disposing of it.. The basic components of the extruder comprised of a hopper, screw, barrel, die, and motor system. Temperature, oxygen, and shear stress all cause the plastics to deteriorate during the extrusion of plastics for filament.. Thus, this study examined the impact of different extrusion temperatures on the filament quality made from high-density polyethylene polyethene (HDPE). The plastic pellets melt and flow into the die as a result of friction between them and the barrel surface and the heat generated by the heating bands. Plastic filament was extruded with a combination of optimal pellet compression, temperatures between 150 and 230 degrees Celsius, and a gradual increase in the pressure of the molten pellets inside the barrel.. Melted plastic adhered itself to the barrel at low temperatures but turned to char at high temperature. Consequently, in order to produce quality 3D filament using HDPE, it is imperative to maintain acceptable temperature conditions. Based on the results, the extruder produced excellent filament suitable for 3D printing at 200 °C. The results of this study emphasize the significance of temperature regulation during the extrusion process in order to guarantee the intended filament quality. [ABSTRACT FROM AUTHOR]

The present three wheeled scooter taxi (TWST) that are widespread in Africa and Asian Countries are fuel economical and inexpensive. However, they are unstable due to their schematic layout. This instability places limitation on the usage of the vehicle. Researchers have investigated the rollover and lateral stabilities of this vehicle, including the effect of vibration on the comfort of the riders. However, not much work has been done on the impact of vibration on the stability of the vehicle. These instabilities could be induced by trenches, potholes, uneven and ungraded roads that are prevalent in developing countries. Therefore, this work modelled and analysed the effect of vibration on a TWST using a standard road bump as reference point. The results proved the vehicle to be unstable in the vicinity of excitation frequency of 15.95rad/sec and spring constant of 68,600N/m due to resonance. This would affect safety of life and property. Therefore, it would be appropriate for some of the manufacturers of these vehicles to provide for enough safety margins in the design and selection of springs where the vehicles are rollover and laterally unstable. This will enhance the vehicle safety and receptivity. [ABSTRACT FROM AUTHOR]

Three-wheeled scooter taxi (TWST) that is currently prevalent in developing countries, is fuel efficient and cheap. It is used mainly for commercial purposes, also as a means of reducing unemployment and tackling poverty. However, the vehicle is unstable and prone to accidents due to its design configuration. The aim of this research work is to investigate the lateral stability of TWST due to Tyre-Road Forces. Therefore, lateral stability equations for three-wheeled vehicle (TWV) were developed and used in the analysis of TWST based on parametric values obtained from static test. The results showed that the vehicle is stable with respect to lateral stability, which is in line with what was obtained from literature, thereby validating the models with the driver alone. However, with two or more occupants the vehicle became unstable. Possible ways of eliminating this instability were discussed. The static test procedure, if adopted and legislated upon, would significantly enhance safety of life and properties of stakeholders in developing countries. [ABSTRACT FROM AUTHOR]

This paper presents the ergonomic evaluation of a manually operated village-level cashew nut shelling machine. A manually operated cashew nut cracking machine was evaluated. Fifty subjects took part in the study, with physiological, postural, and subjective measurements being taken. Comfort Questionnaire for cashew nut cracking machine (CQC) was also evaluated. Using the machine resulted in postural discomfort. The perception of the subjects as per the efficiency of the machine was neutral; 50% accepted that the machine is efficient, while the other 50% were unsatisfied. Following a participatory ergonomic process and using appropriate anthropometric measurements, an improved, adjustable prototype was developed. The lever arm was designed based on 5th percentile of the subjects; blades were welded into the cracking lid to reduce the amount of impact force used for cracking, so as to reduce crushing of the nuts. Also the ergonomic seat and worktable allow posture change from sitting to standing. Other features include; feeding tray, foot rest. The work surface height is made to be 100 mm below the elbow height. i.e. 1200 mm. The length of the work table (work space) was designed to accommodate 95th percentile of the Bicromial breadth of the subjects. The foot and the knee room was 150 mm. The cracking machine is bolted to the worktable, so that it can be easily disassembled. The study demonstrated how ergonomics can play an important role in reducing drudgery and improving user satisfaction and acceptability in technology development and transfer in developing country. [ABSTRACT FROM AUTHOR]

The study of compaction or solids conveying in a screw extruder has been carried out majorly on the straight screws using the plug flow analysis. Despite this, the analysis of the straight screw appears to be complex as contained in existing literatures based on the force and torque balance. The tapered screw, which is considered to be an effective option for biomass compaction, introduces greater complications because the geometry is constantly changing. In this study, a method based on the traction and retardation mechanism of friction is developed for a fully unwound screw channel utilizing only the force balances. The procedure has been used to carry out a parametric analysis of the tapered screw extruder for a screw press biomass briquetting machine. The taper angle was considered to significantly increase the pressure developed in the extruder depending on the length of the compaction zone. The optimum taper angle has also been found to be dependent on the frictional coefficient of the biomass material with enclosing surfaces and ranges between 2° and 4°. [ABSTRACT FROM AUTHOR]

The utilization of biomass for heat and power generation has aroused the interest of most researchers especially those of energy. In converting solid fuel to a usable form of energy, pyrolysis plays an integral role. Understanding this very important phenomenon in the thermochemical conversion processes and representing it with appropriate mathematical models is vital in the design of pyrolysis reactors and biomass gasifiers. Therefore, this study presents analytical solutions to the kinetic and the heat transfer equations that describe the slow pyrolysis of a biomass particle. The effects of Biot number, temperature and residence time on biomass particle decomposition were studied. The results from the proposed analytical models are in good agreement with the reported experimental results. The developed analytical solutions to the heat transfer equations which have been stated to be "analytically involved" showed average percentage error and standard deviations 0.439 and 0.103 from the experimental results respectively as compared with previous model in literature which gives average percentage error and standard deviations 0.75 and 0.106 from the experimental results respectively. This work is of great importance in the design of some pyrolysis reactors/units and in the optimal design of the biomass gasifiers. [ABSTRACT FROM AUTHOR]

This paper presents a survey of cybercafes in a developing country to reveal their design pitfalls and propose appropriate solutions to the observed problems based on ergonomic principles. These cybercafes provide Internet services to communities but the concern is to make the work convenient at the computer workplace and comfortable at work thus reducing the risk of musculoskeletal injury and minimising energy expended at work. A survey was conducted in fourteen cybercafes using questionnaires, personal interviews and actual field measurements. Ergonomic analysis revealed that cybercafe chairs are the major pitfalls of the café design: they are often too short with no arm rests and with insufficient backrests. Chairs are also stationary as opposed to being mobile with rollers. Customers' leg positioning under the table is restricted and the workspace is too small. Also, the top of computer monitors often is above eye level for an average height customer. Since very little documentation exists on the subject in developing countries, the work opens a gate of opportunities for those in the cybercafé business with financial constraints to implement standard designs. The work also complements the dearth of expertise in the area since many towns in Nigeria do not have the required expertise for cybercafé design and construction. [ABSTRACT FROM AUTHOR]

There is an increasing worldwide interest in the effective utilisation of municipal solid wastes as an avenue of reducing its high cost of clearing. Municipal solid wastes are usefully converted into a medium grade fuel (biogas) to reduce its nuisance value to the environment. In this paper, the potential of vegetable (putriscible) component of municipal solid wastes was examined in terms of biogas production. The vegetable component of the waste was used as substrate in a batch-fed 200 dm³ capacity anaerobic digester, which was consecutively loaded with a 10-20 kg ranged weight of vegetable. The total solid (TS) of substrate was 8-10% over a retention period of 40 days. The temperature of the substrate during bio-digestion was maintained within 29°C and 33°C. The average biogas yield varied from 5.15 dm³/kgTS to 5.83 dm³/kgTS. From the digestion experiments, a regression equation, called the municipal solid wastes energy value model, was derived. This model estimates the biogas production from municipal solid wastes. For the predictive model formulation, a relationship between retention time and the daily/total biogas yield was explored. The polynomial function significantly represents the models formulated for the different quantity of substrate loaded. This strongly suggests that the polynomial series is best suited to predict the relationship between retention time and the quantity of substrate loaded for the experiment. This tool is useful in optimising biogas production from energy materials, and requires further validation and refinement. Hopefully, this study advances this increasingly growing area of municipal solid wastes research. [ABSTRACT FROM AUTHOR]