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1

Reactive solute transport in blood flow through a permeable capillary

Debnath S., Roy A. K., Bég O. A.

Archives of Mechanics

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2022

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Vol. 74, nr 2-3

173--200

EN

The present analysis discusses the solute transport process in a steady 2D (axial and radial) laminar flow of blood through a permeable, finite length capillary. Blood is treated as a homogeneous Newtonian fluid and the solute is absorbed at the capillary wall with a linear irreversible reaction rate. The velocity profile is obtained by a regular perturbation technique, whereas the transport coefficients depicted by the Gill generalized dispersion model are solved numerically. A number of different scenarios are considered, namely transport with no-reaction, weak absorption, strong absorption, low filtration or high filtration, etc. In the initial stages, the temporal behaviour of the dispersion coefficient is identical to those cases when there is no radial velocity. For the combined effect of radial and axial velocities, however, the dispersion coefficient is lower for a high absorption rate than for a weak absorption rate. Diffusion is accelerated with higher values of filtration coefficient. Owing to the opposite effects of radial diffusion and radial velocity, the solute particles require more time to reach the steady state. The analysis finds applications in, for example, reactive nutrient and pharmacological transport in capillary hemodynamics.

2

Analysis and simulation of different types of power amplifiers used in electromagnetic levitation system

Debnath S., Biswas P. K., Das U.

Journal of Power Technologies

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2018

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Vol. 98, nr 2

220--227

EN

The objective of this paper is time and frequency response analysis of single quadrant and two-quadrant power amplifiers by using MATLAB SIMULINK, PSPICE and PSIM based software used in the electromagnetic levitation system. The power amplifier plays a key role in controlling the electromagnetic levitation system, controlling the current as well as the force between electromagnet and rail. Here the power amplifier is used to convert a fixed DC voltage to an adjustable DC output voltage. Different kinds of power amplifiers have been proposed for the electromagnetic levitation system. In this paper, only buck and asymmetrical converters are simulated in the simulation software. The exciting current of the electromagnet is controlled by the power amplifier, which controls the air gap and force between actuator and rail in a closed loop manner. PSPICE is an analog and digital circuit simulation software. PSIM is a general-purpose analog and digital electronic circuit simulator. It is also used for simulation and design software for power electronics, motor drives, and dynamic system simulation. SIMULINK is the graphic user interface software from MATLAB which helped us prepare the model of the various power systems, power electronics and control system.

3

A comparative study between load and No-load condition of Brushless DC Motor drives by using MATLAB

Das U., Biswas P. K., Debnath S.

Journal of Power Technologies

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2018

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Vol. 98, nr 3

281--286

EN

In this paper an extensive comparative performance study is carried out between No-load and load condition of an open loop model of a Brushless Direct Current (BLDC) Motor drive fed from a two-level voltage source inverter (VSI) under 120-degree conduction mode, using simulations in a MATLAB based software environment. BLDC motors are currently growing in popularity and replacing the brush motor in many applications, as they can be used in both low and high-speed vehicle systems and also in servo drives. The high reliability, torque to inertia ratio, high efficiency, high power density, ease of control and mainly the brushless operation make BLDC motors superior to others. It has a permanent magnet as a rotor with a balanced 3-phase armature in its stator. The armature winding is driven by a power electronics inverter which is switched in synchronism with the rotor position, sensed by an optical encoder or a Hall Effect sensor. It is found that torque ripple can be minimized by tuning the value of rotor position, no load condition and trapezoidal armature phase current. The different performance parameters for no-load and load condition of the BLDC motor such as phase voltages, phase currents, speed, electromagnetic torque, d and q axis current and rotor position etc. are determined in MATLAB environment.