A Compact CPW-Fed Planar Stacked Circle Patch Antenna for Wideband Applications

The article investigates the performance of planar and compact CPW-fed microstrip patch antenna that offers 10 dB impedance bandwidth over the wide frequency range between 2.59 and 7.61 GHz. The parametric analysis of various design variables is included to acquire the final design of proposed antenna. The prototype exemplary of designed antenna is experimentally tested to obtain the return loss, VSWR, radiation response and gain characteristics. The close agreement is acquired between simulated and experimental results.The projected antenna has compact size of 0.61λ₀ × 0.44λ₀ × 0.027λ₀ mm³ and offers a 10 dB wide impedance bandwidth of 5.02 GHz. Thus, it may be considered suitable for variety of wireless applications including WLAN, Wi-MAX, fixed satellite services, wireless point-to-point applications etc.

     

Enhancement in electrical performance of indium gallium zinc oxide-based thin film transistors by low temperature thermal annealing

We have studied the characteristics of transparent bottom-gate thin film transistors (TFTs) using In–Ga–Zn–O (IGZO) as an active channel material. IGZO films were deposited on SiO₂/Si substrates by DC sputtering techniques. Thereafter, the bottom-gate TFT devices were fabricated by depositing Ti/Au metal pads on IGZO films, where the channel length and width were defined to be 200 and 1000 μm, respectively. Post-metallization thermal annealing of the devices was carried out at 260, 280 and 300 °C in nitrogen ambient for 1 h. The devices annealed at 280 °C have shown better characteristics with enhanced field-effect mobility and high on–off current ratio. The compositional variation of IGZO films was also observed with different annealing temperatures.     

A GA based audio steganography with enhanced security

In the current internet community, secure data transfer is limited due to its attack made on data communication. So more robust methods are chosen so that they ensure secured data transfer. One of the solutions which came to the rescue is the audio Steganography. “A GA Based Audio Steganography with enhanced security” is one propose system which is based on audio Steganography and cryptography, ensures secure data transfer between the source and destination. Here we present a novel, principled approach to resolve the remained problems of substitution technique of audio Steganography. We use most powerful encryption algorithm (RSA) to encrypt message in the first level of security, which is very complex to break. In the second level, we use a more powerful GA based LSB (Least Significant Bit) Algorithm to encode the encrypted message into audio data. Here encrypted message bits are embedded into random and higher LSB layers, resulting in increased robustness against noise addition. The robustness specially would be increased against those intentional attacks which try to reveal the hidden message and also some unintentional attacks like noise addition as well. On the other hand, to reduce the distortion, GA operators are used. The basic idea behind this paper is maintained randomness in message bit insertion into audio data for hiding the data from hackers and multi-objective GA is used to reduce distortion.     

QoS evaluation of energy-efficient ML-MAC protocol for wireless sensor networks

Power management is an important issue in wireless sensor networks (WSNs) because wireless sensor nodes are usually battery powered, and an efficient use of the available battery power becomes an important concern specially for those applications where the system is expected to operate for long durations. This necessity for energy efficient operation of a WSN has prompted the development of new protocols in all layers of the communication stack. If the radio transceiver is the most power consuming component of a typical sensor node, large gains can be achieved at the link layer where the medium access control (MAC) protocol controls the usage of the radio transceiver unit.     

The Temporal Effect of Mobility on Path Length in MANET

Ad hoc network consists of a set of identical nodes that move freely and independently and communicate among themselves via wireless links. The most interesting feature of this network is that they do not require any existing infrastructure of central administration and hence is very suitable for temporary communication links in an emergency situation. This flexibility, however, is achieved at a price of communication uncertainty induced due to frequent topology changes. In this article, we have tried to identify the system dynamics using the proven concepts of time series modeling. Here, we have analyzed variation of path length between a particular source destination pair nodes over a fixed area for different mobility patterns under different routing algorithm. We have considered four different mobility models—(i) Gauss-Markov mobility model, (ii) Manhattan Grid mobility model and (iii) Random Way Point mobility model and (iv) Reference Point Group mobility model. The routing protocols under which, we carried out our experiments are (i) Ad hoc On demand Distance Vector routing (AODV), (ii) Destination Sequenced Distance Vector routing (DSDV) and (iii) Dynamic Source Routing (DSR). The path length between two particular nodes behaves as a random variable for all mobility models for all routing algorithms. The pattern of path length for every combination of mobility model and for every routing protocol can be well modeled as an autoregressive model of order p i.e. AR(p). The order p is estimated and it is found that most of them are of order unity only. We also calculate the average path length for all mobility models and for all routing algorithms.     

A design approach of higher oscillation VCO made of CS amplifier with varying active load

This article proposes a design approach of common source (CS) amplifier based Voltage Controlled Oscillator (VCO) to derive higher oscillation frequency. The working feature is such that, the active load of CS amplifier is varied to modulate the flow of current based on a bias circuit steered by an external controlled voltage (V_ctrl), which controls the delay of each stage and thereby regulates the oscillation frequency. The circuit is designed and analyzed on Cadence Virtuoso platform at a supply voltage of 1.2 V for 90 nm CMOS to read a device footprint of 0.105 mm², which offers a power burn and frequency of 2.092 mW and 9.21 GHz respectively with a phase noise and output noise of − 137.9 dBc/Hz and − 168.40 dB at 1 MHz offset frequency. To justify the reliability of the circuit we have conducted worst case analysis by considering effect of power delivery network (PDN) and corner variation along with 500 runs of Monte Carlo. The design is also introduced under 28 nm UMC to validate its scalability with technology trends.

     

Batch and bulk removal of a triarylmethane dye, Fast Green FCF, from wastewater by adsorption over waste materials

De-Oiled Soya, an agricultural waste material and Bottom Ash a waste of power plants, have been used as adsorbents for the removal and recovery of a triarylmethane dye Fast Green FCF from wastewater. Batch studies have been carried by observing the effects of pH, temperature, concentration of the dye, amount of adsorbents, sieve size of adsorbent, contact time, etc. Graphical correlation of various adsorption isotherm models like, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich have been carried out for both the adsorbents. The adsorption over both the materials has been found endothermic and feasible in nature. Various thermodynamic parameters, such as, Gibb's free energy, entropy and enthalpy of the on-going adsorption process have been calculated. The kinetic studies suggest the process following pseudo first order kinetics and involvement of particle diffusion mechanism. The bulk removal of the dye has been carried out by passing the dye solution through columns of Bottom Ash and De-Oiled Soya and saturation factor of each column has been calculated. Attempts have also been made to recover the dye by eluting dilute NaOH through the columns.     

Tuning temperature-dependent microstructural properties of tungsten oxide thin films for acetone sensor

Journal of Materials Science: Materials in Electronics - In this paper, the physical properties of thermally evaporated tungsten oxide thin films and their performance towards acetone sensors are...     

Near UV emission and p-type conductivity in Zn1−xLixO and Zn1−xNaxO nanomaterial system

The nanomaterial system Zn_1−xLi_xO and Zn_1−xNa_x  O (0?x?0.15$0?x?0.15$) were synthesized by controlled solid state reaction. XRD analysis showed well formed wurtzite structure of average particle size about 50 nm and change in lattice parameters due to incorporation of group I element in ZnO lattice. SEM exhibited formation of nanorods. Hall effect measurement of Zn_1−xLi_xO and Zn_1−xNa_xO system showed p-type conductivity which varied with concentration of Li and Na. Photoluminescence showed strong emission peak in near UV at 3.11 eV (398 nm) and negligible visible emission. The PL peak positions in Zn_1−xLi_xO and Zn_1−xNa_xO nearly coincide which suggest very similar recombination mechanism in Li and Na doped ZnO nanocrystals. The results hold potential for fabrication of ZnO based near UV LEDs.