M. Mofazzal Hossain

Performance evaluation of symmetric encryption algorithm in MANET and WLAN

The demand for adequate security to electronic data system grows high over the decades. As the security issue also impact on the performance analysis of the wireless network, data encryption is necessary for sending and receiving information secretly over the network. Since 1970s, Data Encryption Standard (DES) has received a substantial amount of attention from academic cryptanalysts. However, in 1998 it has been proved insecure and on October 2000, National Institute of Standards and Technology (NIST) announced that the Rijndael algorithm has been selected as the Advance Encryption Standard (AES).Our algorithm is based on AES. In this paper, we examine the performance of our new cipher in MANET and wireless LAN networks and make a performance comparison with that of AES.

Modeling and numerical analysis of thermal treatment of granulated porous particles by induction plasma

In this paper it is aimed to describe the modeling and numerical analysis of thermal treatment of granulated porous particles by induction plasma. To investigate the heat exchange dynamics between plasma and particles during the flight of granulated porous particles through the hot plasma, a plasma-particle interactive flow model has been developed. This model solves the conservation equations to predict the temperature and flow fields of plasma, under local thermal equilibrium (LTE) conditions, and then computes the injected particles trajectories, temperature and size histories, and the particle source terms to incorporate the particle loading effects. It is found that the size and dose of injected particles greatly affect the particle trajectory and temperature, and hence the heat transfer to particles at higher powder feed-rate.

Synthesis of TiO 2 Nano-particles by Pulse Modulated Induction Thermal Plasma: a Numerical Investigation

Nanoparticles offer superior characteristics and features compared to its mass counterparts of the similar composition. Among different routes of nanoparticles synthesis, pulse modulated inductive thermal plasma offers some distinct advantages. In this work, a fluid-flow model for plasma-particle interaction has been described adopting pulse modulated inductive thermal plasma. After solving the model numerically, the particle and plasma parameters (temperature contour and velocity of plasma, temperature, velocity and diameter of particles) have been calculated. It is found that flow rate of carrier gas has insignificant effects on the temperature profile of plasma. It is also found that for a pulse modulated power of 14/10 kW and for a 6 lpm (liter per minute) carrier-gas flow-rate, most of the Ti particles completely evaporated within the torch region.

Design of a high efficiency ultrathin CdTe/CdS p-i-n solar cell with optimized thickness and doping density of different layers

Due to the lowest EBPT (energy payback time) and less emitter of GHG (greenhouse gases), it is crucial to enhance the efficiency of CdTe photovoltaic cells. In this paper, a high efficiency CdTe/CdS p-i-n heterostructure solar cell is designed and the performance of the cell is investigated using 1D AMPS (1 dimensional analysis of microelectronic and photonic structures) simulator. The cell consists of a TCO layer (ZnO), a window layer (n-type CdS), an intrinsic layer (CdTe), an absorber layer (p-type CdTe) and a highly doped CdTe as a back surface field (BSF) layer. After the optimization of layer thicknesses and doping densities of different layers, we obtained a conversion efficiency of 26.74% for a total cell thickness of 2.7 m. It is also found that the conversion efficiency can be increased by simply increasing the thickness of intrinsic layer. At 1.5 AM solar irradiance, the proposed cell structure earned a Voc of 1.10 V, a Jsc of 27.29 mA.cm−2, and a fill factor of 89.1%, corresponding to an overall conversion efficiency of 26.74%.

A new planar printed antenna with band-notch characteristics for UWB applications

This paper presents a new small-size microstrip-fed UWB (ultra wideband) planar monopole antenna with band notch properties. The presented antenna comprises of trapezoid shape with tapered end radiating patch and a 50Ω microstrip line that are etched on the upper surface of the FR-4 substrate whereas the ground plane is etched on the bottom surface of the substrate. The antenna covers the UWB frequency range and the radiation pattern looks like similar to a monopole antenna. With the insertion of a U-shaped slot, the notch characteristics can incorporate in the proposed design which can reject the frequency band 5-6 GHz. Simulation results validate that the antenna is feasible for UWB applications due to its compactness and stable radiation pattern and gain.

Comparative performance study of short and long induction plasma torches: A numerical approach

In developing the ITP (induction thermal plasma) source for the thermal modification of micro-particles, it is crucial to comprehensively explore the effects of plasma torch dimensions, effects of plasma discharge conditions and particle parameters. Considering the plasma-particle interactions and particle loading impacts, a interactive flow model for argon-oxygen mixed-gas plasma is developed to investigate the performances of short (ST:138 mm) and long (LT:190 mm) induction plasma torches. Solving the model numerically using control volume algorithm, we predicted the plasma isotherm, injected particles temperature history, trajectory, velocity and diameter at any location along its flight path for both the torches. In this model, the plasma is in local thermal equilibrium (LTE) i.e the temperatures of electron and heavy particle (ion or neutral particle) are the same. From the plasma isotherms of argon-oxygen, it is observed that higher plasma temperature (around 8000K at the torch exit) is obtained in short torch, compared with that of in long torch (around 5000 K at the torch exit). It has also been noticed that more particle diameter shrinkage is occurred in short torch than that of long torch.

Electromagnetic wave propagation characteristics in single walled metallic carbon nanotube

The metallic single walled carbon nanotubes have been proposed as a promising inter connector in intra-chip and inter-chip packaging applications as well as passive devices for future generation terahertz IC (Integrated Circuit) technology, due to their superior electrical and thermal properties compared with those of copper. In this paper a theoretical investigation is carried out to predict phase and group velocities and the attenuation characteristics of single walled metallic carbon nanotubes (SWCNTs), and bundled SWCNTs in the terahertz regime. The expressions for attenuation constant, phase constant, phase velocity, and group velocity have been derived using transmission line theory. It is found that the predicted phase and group velocities in single SWCNT, bundled SWCNTs are strongly frequency dependent and increases with frequency. It is also noticed that the group velocity decreases after having a peak at around 100 GHz for both single SWCNT and bundled SWCNT.

Effects of carrier gas flow-rate and oxygen admixture ratio on particle parameters in Ar-O 2 plasma

Taking into account the strong plasma-particle interactions and particle loading effects, a model of plasma-particle interaction of argon-oxygen plasma has been developed for the numerical predict the particle temperature, velocity, trajectory and plasma temperature isotherm during the in-flight treatment. In this model the conservative equations solves the conservative equations to predict the plasma trajectories under local thermal equilibrium condition. It is found that the carrier gas flow-rate strongly affects the particle temperature and the admixture ratio of oxygen to argon affects the plasma temperature isotherm as well as the particle temperature.

Detection ability of parametric faults in Analog circuits using CBT concept and its Test limitations

This paper represents the CBT (Co-efficient-based Test) technique to determine parametric faults mainly for a higher order low pass filter. We found that by varying signal to noise ratio as well as considering noise generated by all the elements, results a different transfer function. And from the coefficient value of that deviated transfer function, it is easy to detect faults also in practical cases. Noise generated by capacitances is also considered in the present work.