An odor sensor was developed for the detection of volatile organic compounds (VOCs). The responsive elements of the odor sensor used in the study were: seven types of metal-porphyrine; Reichardt’s Dye (R-Dye) and six pH indicators. The characteristics of responsive elements of the odor sensor have been described. Under the conditions of hydrophobic polymers, there were various responses for low hydrophobic gases and under the conditions of hydrophilic polymers, there were multi-responses for the gases of high hydrophobe. The present study of the odor sense system with basic function of odor sense confirmed the above description.

Investigation and evaluation of the pressure flushing through storage reservoir

Samad  Emamgholizadeh, M. Bina, M. Fathi-Moghadam and M. Ghomeyshi

When a dam is constructed on the rivers, it causes the sediments settle in the reservoir. Therefore, the initial storage of the reservoir would reduce and it will have negative effects on the operation of the reservoir. Considering the importance of this issue, different methods for control of sedimentation and maintenance of dams are used. These methods include: watershed management, dredging, density current venting and flushing. In flushing methods, the previously deposited sediment would be flushed from the reservoir by opening of the outlets. In the pressure flushing the amount of the flushed sediments depend on many parameters such as water depth on the bottom outlets, discharge released through bottom outlets, the size of the outlets, the geometry of the reservoir, the size and the kind of the deposited of the sediments in the reservoir. In this study, the effects of discharge released from the bottom outlets and the water depth on the bottom outlets was investigated using three sizes of non-cohesive sediments (fine, medium and coarse). Laboratory experiments were carried out to investigate the flushing processes during pressure flushing. A physical model was constructed in the Hydraulic Laboratory, Water Sciences Engineering Collage, University of Shahid Chamran, Ahwaz, Iran. The results of the experiments indicated that the flushed sediment increased with the decrease of reservoir’s water depth and with increasing of discharge from outlet. Similarly, under same conditions the flushed sediment increased when the size of sediment changed from coarse sediment to fine sediment.

Direct torque control of induction motor drive based on random position svpwm for reduction of acoustical noise

Y.V. Siva Reddy and M. Vijay Kumar

Direct Torque Control (DTC) is known to produce fast and robust response in induction motors. However, during steady state, notable torque, flux and current pulsations will occur which are reflected in speed estimation, speed response and also in increased acoustical noise. This paper introduces a new direct torque control method based on random position space vector pulse width modulation (RPSVPWM). In the proposed method each of the three phase pulses is located randomly in each switching sequence interval without corrupting the switching sequences for space vector modulation.  Simulation studies have been carried out for different operating conditions of the drive system and compared with those of the conventional method.

Effect of high-pressure coolant Jet on grinding temperature, chip and surface roughness in grinding AISI-1040 Steel

N. R. Dhar, A.T. Siddiqui and M. H. Rashid

Grinding can be described as a multi-tooth metal cutting operation in which material is generally removed by shearing and ploughing in the form of micro sized chips by the abrasive grits of the grinding wheel. As a result, high temperature is produced in the grinding zone due to large negative rake and high cutting speed of the grinding wheel. Suitable cutting fluid is employed to reduce the temperature through cooling and lubrication in the cutting zone. As conventionally applied cutting fluid is unable to enter into the chip tool interface, the interface temperature is reduced to some extent. However, high-pressure coolant (HPC) jet effectively reduces cutting zone temperature entering into chip tool interface maintaining a good surface integrity. The present work investigates the role of high-pressure coolant jet on chip formation, grinding zone temperature and surface roughness in grinding AISI-1040 steel. The experimental results indicate significant reduction in cutting temperature on application of high-pressure coolant, which enables favorable chip formation and a better surface integrity for the finished work piece.

Decolorization behavior of Azo Dye with various co-substrate dosages under granular activated Carbon-biofilm configured packed column operation

Soon-An Ong, Eiichi Toorisaka, Makoto Hirata and Tadashi Hano

The objective of this study was to investigate the decolorization behavior of Acid Orange 7 (AO7) with different dosages of co-substrates under granular activated carbon-biofilm configured packed column (BGAC-packed column) operation. The spent granular activated carbon (GAC) was immobilized with azo dye-degrading microbes through attachment and then the GAC-biofilm was packed into a column. The system was fed with 3 l of AO7-containing wastewater for operation time of 24 h/batch. With initial 500mg/l of AO7 concentration, it was observed that complete decolorization was achieved in all runs although the co-substrates added into the BGAC-packed column system reduced until to zero. The kinetic data obtained from the removals of AO7 and COD could be explained by the autocatalytic kinetic model and Monod kinetic model, respectively. 

Simulation of water hammer flows with unsteady friction factor

Mimi Das Saikia and Arup Kumar Sarma

The problems of unsteady flow are frequently encountered in hydraulic power plant having a long conduit without the provision of surge tank due to sudden closing of the turbine valve. The velocity in water hammer situation fluctuates within the pipe from significantly high to an extremely low value with change in its direction after some interval of time. As a result there will be tremendous fluctuation in the wall friction along with the discharge and the pressure head. Transient analysis of the pipe flow is often more important than the analysis of the steady state operating conditions that engineers normally use to withstand these additional loads resulting from rapid valve closures water hammer situations. A numerical model “UNSTD_FRIC_ WH” using MOC and Barr’s explicit friction factor has been presented here for solution of the transient flow situations of water hammer where there is a provision of computation of the transient frictions along with the pressure and discharges at a particular pipe section. Assessment of friction factors at any section in this unsteady transient flow condition also clearly indicates the effectiveness of using variable friction factor in contrast to the steady state friction as in the available numerical models. Damping of pressure and discharge with time after valve closure due to friction of the pipe are clearly illustrated by “UNSTD_FRIC_WH” model. It is well applicable for all flow conditions ranging from laminar to turbulent.