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This research aims at the designing and implementation of an Automatic Voltage Regulator (AVR) with higher precision and hysteresis. AC power supplied by PDB (Power development board) in Bangladesh is subjected to variation from time to time. Moreover in rural areas supplied voltage remains lower than specified. This causes a considerable threat to the sophisticated electronic devices like computer, refrigerator, television etc. So ensuring the input voltage to remain in a tolerable pre-specified limit has become a necessity in rural as well as some urban areas. Current systems available locally lacks precision and suffers the problem of oscillating between two output voltage and hence creating surge at the output which can damage valuable electronics. This research handled both shortcomings and introduced in the tolerable range of 215-237 volt using several taps. Hysteresis has been introduced while changing from one level to other and thus preventing oscillation.

The main objective of this work is to design and construct a PoE switch based system: to control electric appliances such as light, fan, heater, washing machine, motor, TV, etc. and simultaneously data communication facility. Especially PoE switch can manage power and data separately by a splitter which motivated the need to research into it not only for industrial application but also for domestic use or home use. Power is use for controlling devices and data is for communication purpose. This system will play an important role for the elderly and physically disabled people to control their home appliances in intuitive and flexible way through Wi-Fi and internet. This system is password protected so only authorized person can control any sensitive electrical appliances. Most commercially available home automation systems are used only for control purpose. But by our proposed PoE based system we can control electrical appliances as well as data communication by the same switch port.

A pot experiment was conducted to study the growth response of Indian spinach (Basella alba L) to biogas plant residues. There were seven treatments comprising of control, recommended NPK fertilizer and biogas plant residues (BPR) @ 10, 20, 30, 40 and 50 ton ha -1 . The treatments were arranged in a randomized complete block design with three replications. Results indicated that number of leaves; plant height and root length and dry weight of shoot and root obtained with recommended NPK fertilizer were statistically similar to those with control treatment except for number of leaves at 60 DAS. Application of biogas plant residues up to 30 ton ha -1 produced similar number of leaves and plant height compared to control and recommended NPK fertilizer at 30 DAS. At 60 DAS, a significantly higher number of leaves and root length was found with above 20 ton ha -1 biogas plant residues and plant height with above 10 ton ha -1 biogas plant residues than control and recommended NPK fertilizer. Fresh weight of shoot and root found with recommended fertilizer dose were significantly higher than that with the control but lower than that with biogas plant residues above 30 ton ha -1 and 10 ton ha -1 , respectively. Biogas plant residues at 30 ton ha -1 and above gave higher shoot and root dry weight than control and recommended NPK fertilizer. However, there were no significant differences between BPR40 and BPR50 for growth parameters of Indian spinach. The study recommends 40 ton ha -1 of biogas plant

A field experiment was conducted in the crop field of the Department of Soil Science, University of Chittagong, Bangladesh to study the effects of biogas plant residues, poultry manure and NPK fertilizer on growth and yield of ladies finger (Abelmoschus esculentus L Moench). There were six treatments - control (no fertilizer/poultry manure/compost), full NPK @ 120 kg N ha -1 , 60 kg P ha -1 and 80 kg K ha -1 , full biogas plant residues(BPR) @ 30 ton ha -1 , 50% NPK+ 50% BPR, full poultry manure (PM) @ 30 ton ha -1 , 50% NPK+ 50% PM. The treatments were arranged in randomized block design with three replications. The data collected were number of leaves, plant height, fruit length, fruit circumference, number of fruits and fruit yield. The results showed that full NPK fertilizer did not significantly increase the growth and yield of ladies finger over control. Compared to control addition of full poultry manure and its combination with NPK fertilizer resulted in 6.28 to 7.29 fold increases in yield. Relatively lower yields (0.34-0.17 fold) were obtained in treatments with biogas plant residues compared to treatments with poultry manure. Our result indicate that poultry manure can be used in combination with the application of inorganic fertilizers for better growth and yield of ladies finger in the valley soils of Chittagong.