No abstract

Local Governments (LGs), the third tier of government in Nigeria, are expected to maintain infrastructure facilities at the grass root level but most rural communities in Southwest Nigeria are characterized by poorly maintained roads. This study assessed conditions of Moveable Rural Road Maintenance Equipment (MRRME) under LGs in Southwest Nigeria vis-a-vis the safety levels on the rural roads. The study measured, impacts of roads conditions on commercial drivers/riders (cdr) and, level of usage of MRRME for the roads. Questionnaires were used to measure: accident rates and impacts among 250 cdr on 9 selected rural roads; Maintenance Performance Measures (MPM) of MRRME among 430 Senior Technical Officers (STOs) and Senior Finance Offices (SFOs) in 84 LG secretariats. The conditions of MRRME were carried out using observational method. More than 72% of cdr were involved in one crash or another and 89% of them attributed this to bad roads. Less than 26% of MRRME was functional with weak plans/tools put in place for correct maintenance program leading to a high level of MRRMEs’ failures and total neglect. T-test t (428) = -5.146, p = 0.421) found that the opinions of STOs (poor ratings for MPM policy implementation) were not different from that of the SFO. There is the need for safety attitudinal change among cdr. LGs also need empowerment to ensure proper maintenance of MRRME and enhances their availability. These measures among other will reduce accidents death counts on Nigeria rural roads.

The process industry has always been faced with the challenging tasks of determining the overall unavailability of safety instrumented systems (SISs). The unavailability of the safety instrumented system is quantified by considering the average probability of failure on demand. To mitigate these challenges, the IEC 61508 has established analytical formulas for estimating the average probability of failure on demand for K-out-of-N (KooN) architectures. However, these formulas are limited to the system with identical components and this limitation has not been addressed in many researches. Hence, this paper proposes an unavailability model based on Markov Model for different redundant system architectures with non-identical components and generalised formulas are established for non-identical k-out-of-n and n-out-of-n configurations. Furthermore, the proposed model incorporates undetected failure rate and evaluates its impact on the unavailability quantification of SIS. The accuracy of the proposed model is verified with the existing unavailability methods and it is shown that the proposed approach provides a sufficiently robust result for all system architectures.

Inefficiency in energy usage has led to the subject of energy harvesting which simply means recycling dissipated waste energy into another useful form of energy. This paper presents the harvesting of waste thermal energy from household heat sources (kerosene stove and generator exhaust pipe) as an electrical energy. Thermoelectric generator (TEG) modules (TGM-161-1.2-2.0) and aluminium heat sinks were constructed and placed close to the heat sources for waste heat harvesting. The hot and cold side temperatures of the TEG modules were measured along with the corresponding output voltages and currents, while the power and energy harvested were estimated. The harvesting of energy from the stove yielded means of 1.532 ± 0.091 V, 0.388 ± 0.003 A, 0.597 ± 0.039 W and 536.87 ± 34.98 J, subject to an average temperature difference of 84.59 ± 3.64 °C. For the generator exhaust pipe, average values of 1.28 ± 0.074 V, 0.285 ± 0.007 A, 0.367 ± 0.029 W and 330.62 ± 26.15 J with an average temperature difference of 62.31 ± 4.88 °C were achieved. The obtained results agreed with previous studies on energy harvesting using TEG modules. This work revealed the potential of waste heat energy harvesting using TEG technology.

The Couple Tank (CT) system remains as a benchmark to investigate and test new emerging control schemes in the process industry since its dynamic emulates many factual system in the field of process control. In this paper, we examine the performance evaluation of two control algorithms, proportional derivative controller (PD) and proportional-integral-derivative controller (PID). The dynamics of the CT system is experimentally derived by system identification method and validated with a mathematical model that depicts the dynamic behaviour of the coupled tank system. Furthermore, the control schemes are expanded on the model obtained through system identification method. The simulation results showed that the PD controller did not meet all the specified control objectives. To improve the response an integral controller was incorporated to the PD controller and the response was compared to that of the PID controller and uncompensated system. The results revealed that the PID controller satisfied all the control goals. However, the PD controller was more satisfactory in terms of time response criteria.