ALGORITHM FOR SELF-TUNING THE PID CONTROLLER

An algorithm for self-tuning the PID controller to the second order systems is proposed in this paper. The proposed self-tuning procedure was developed according to the maximum stability degree criterion, the criterion that permits to achieve the high stability degree, good performance and robustness of the system. According to the proposed algorithm, the controller can be tuned according to the parameters that characterize the process and they can be determinate from the experimental response of the open loop system. To demonstrate the efficiency of proposed procedure of self-tuning the PID controller, the computer simulation was performed and the obtained results were compared with Haeri’s method, maximum stability degree method with iterations and parametrical optimization method. According to the developed algorithm, it was performed the control of the thermal regime in the oven.

Experimental and Numerical Study on Strength of Concrete Slabs under High Speed Projectiles

Concrete elements under high-speed projectiles effect has an increasing interest recently. Understanding to what extent the concrete can resists the effect of projectiles, very necessary in design structures in order to save the occupants. The objective of this study is to develop improved numerical model for predicting dynamic response of RC slabs under HSP attack. The present study presents a total of 12 concrete slabs casted and tested under plain and steel reinforcement. Parameters investigated were slab thickness, (50 mm, 100 mm, and 150 mm) and projectile type. Dynamic simulation was performed also and the results obtained have been discussed and compared with experimental response. Generally, it was concluded that penetration depth was controlled by target thickness regardless the steel reinforcement. Good alignment achieved between numerical and experimental date with respect to penetration depth and crater vale.

Models for Estimating the Hearing Threshold of Quarry Workers at High Frequencies

It is widely known that quarry industry has great importance in developing countries, such as Nigeria. There is paucity of information regarding effects of noise experienced by quarry workers during their working time. Therefore, this study investigated the influence of age of workers, years of exposure of workers and noise level of the machine used in quarry on hearing threshold. A factorial design of experiment was employed for the investigation. Two hundred and four quarry workers volunteered for this study from four quarries in South western Nigeria. Emitted noise, which quarry workers were exposed to during machinery operation, was measured with a digital sound level meter and workers hearing threshold was measured in an audiogram sound proofing testing booth at standard conditions. Predicted models were established from experimental design to determine main and interactions effects towards the response (hearing threshold). These were statistically analysed using analysis of variance (ANOVA). All terms of the models were significant at p<0.05. The best fitted model was at 4kHz (R2 = 0.639, p<0.05). The magnitudes of the main effect of the factors are in ascending order of noise level >years of exposure>age. The analysis of the experimental response indicated that there is no interaction of any factors on the hearing threshold. It can be concluded that age, years of exposure and noise level have main effects at various capacities at different frequency to predict the hearing threshold of the quarry workers. This work determined the factors and the predicted model to spell out safe hearing threshold of quarry workers that fitted for the job at a particular noisy workstation as well as ensuring comfortable, safe and effective workstation design.