A. Vimala Juliet

Multi band microstrip patch antenna for satellite communication

A wideband micro strip patch antenna is designed for satellite communication. It achieves multi-band functionality through the array technique. The proposed antenna generates circular polarization and good radiation efficiency. The implementation of array technique provides better efficiency. It is a 2×3 array pattern with Microstrip line feed. It operates about C and X bands efficiently.

Design and simulation of touch mode MEMS capacitive pressure sensor

This paper presents the design and simulation of a capacitive pressure sensor system for biomedical applications. Employing the Micro Electro Mechanical Systems (MEMS) technology, high sensor sensitivities and resolutions have been achieved. This report provides initial data on the design and simulation of such a sensor. Capacitive sensing uses the diaphragm deformation-induced capacitance change. The sensor composed of a polysilicon diaphragm that deflects due to pressure applied over it. Applied pressure deflects the 2 µm diaphragm changing the capacitance between the Silicon substrate and the polysilicon diaphragm. The simulation of the MEMS capacitive pressure sensor in touch mode achieves good linearity and large operating pressure range. Intellisuite software is used for modeling and simulating of MEMS capacitive pressure sensor to optimize the design, improve the performance and reduce the time of fabricating process of the device.

Performance analysis of DOA and AODV routing protocols with black hole attack in MANET

The collection of mobile nodes without infrastructure known as the mobile adhoc network has its nodes that moves independently towards all directions in the network thereby changing the network topology frequently. In MANET, whenever the node that is identified as source need to transfer data to the receiving node which resides out of coverage area, source node uses intermediate nodes. We use DOA protocol for the purpose of connectivity in such large scale networks for better data transmission. In such case, if a malicious node enters into the MANET, packet loss occur leading to performance degradation. The secure transfer of information via large scale wireless network is a challenging issue. In this paper we analyzed two routing protocols used in large scale network; the DOA and AODV routing protocols and injected them using black hole attack and evaluated its quality parameters like packet delivery ratio and average end to end delay. The network was simulated using NS2 and the performances of the protocols were compared for its efficiency.

AN ENHANCED ROUTE FAILURE RECOVERY MODEL FOR MOBILE AD HOC NETWORKS

In Mobile Ad Hoc Networks (MANET), change in topology of the network occurs due to the mobility factor of the nodes leading to the extension in size of the network. The extension of network size happens due to the entry of nodes into the network. As the topology changes, link failure between the nodes takes place due to several reasons like channel interference and dynamic obstacles etc that give rise to severe performance degradation. In traditional AODV, the link failure is overcome by re-routing from the source node which is a time consuming process that increases the overhead of the nodes. Also in case of multiple link failures, there are chances for loss of data packet. Maintaining the performance of the network dynamically during link failure, specifically in case of long data transfer such as the stream of voice data, is a challenging problem. In order to overcome such performance related issues, we developed the Local Link Failure Recovery algorithm (LLFR) for Ad hoc networks that establishes recovery from link failures spontaneously at the point of link breakage. In such cases, a reliable link failure recovery is the main criteria that will determine the performance of the network in terms of Quality of Service (QoS). The LLFR is deployed in each node collects RREP in the RREP Buffer Table (RBT) stack in the highest order of signal strength, which gets triggered during link failures. Once a link failure is detected, the intermediate node searches for an alternate path around the faulty area by choosing the first RREP that is stacked in the RBT and establishes a new route to the intended destination for sending the data packets without any time delay. The simulation results show that the performance parameters like packet delivery ratio, throughput, average end to end delay and routing overhead are better compared to the traditional AODV and other link failure recovery techniques.

Analysis and Optimization of Sensitivity of a MEMS Peizoresistive Pressure Sensor

This paper presents a MEMS Piezoresistive pressure sensor which utilizes a circular shaped polysilicon diaphragm with a nanowire to enhance the sensitivity of the pressure sensor. The polysilicon nanowire is fabricated in such a way that it forms a bridge between the circular polysilicon diaphragm and the substrate. The high Piezoresistive effect of Silicon nanowires is used to enhance the sensitivity. A circular polysilicon nanowire piezoresistor was fabricated by means of reactive ion etching. This paper describes the performance analysis, structural design and fabrication of piezoresistive pressure sensor using simulation technique. The polysilicon nanowire pressure sensor has a circular diaphragm of 500nm radius and has a thickness about 10nm. Finite element method (FEM) is adopted to optimize the sensor output and to improve the sensitivity of the circular shaped diaphragm of a polysilicon nanowire Piezoresistive pressure sensor. The best position to place the Polysilicon nanowires to receive maximum stress was also considered during the design process..The fabricated polysilicon nanowire has high sensitivity of about 133 mV/VKPa.

Toxic gas sensor using resonant frequency variation in micro-cantilever

Our world is facing some drastic changes in the climatic conditions due to the heating effect caused by various greenhouse gases and is increasing at an uncontrolled rate. The people working underground are generally caught unawares of the hazardous gas emission around the locality. Hence an effective sensing and communicating system is required to effectively monitor and alert the neighborhood to save them. This paper aims in finding out a way to quantitatively measure the hazardous gas molecules. The gravimetric sensor works by absorbing the chemical in a polymer, which alters the overall mass of the sensing element i.e a cantilever, thereby its resonant frequency. Here a micro-cantilever beam is fabricated using selective coatings on the surface to selectively absorb the hazardous gases. As the gases are absorbed the mass increases and hence resonant frequency changes. This change in frequency gives the measure of the quantity of gas present in that environment. The major expected advantage of this technique would be the portability, sensitivity, repeatability and economic cost of the sensor that is used.

Measuring Low Frequency Vibration Using MEMS Based Accelerometer

High sensitivity and low noise floor is a prerequisite to micro-g vibration measurement. The effects of environmental sensitivities, such as base strain, thermal transients, and caustic noise may be significant. Attention should be paid, when measuring low-g acceleration using DC response accelerometers to the direction of earth’s gravity.

Mathematical Modeling of Neuro-Controlled Bionic Arm

A neuro-controlled bionic arm will be able to allow an amputee to move his or her prosthetic arm as if it is a real limb simply by thinking. The arm also empowers patients with more natural movement, greater range of motion and restores lost function. To design a system which connects the brain to the arm through nerves is possible only when the system will have good control and accuracy. By proper designing, a brain can communicate directly with artificial arms. Essentially, the design should allow greater control of the arm by decoding the signals sent by the muscles so that a patient thinks to bend his/her wrist and wrist bends. Similarly they can think to rotate wrist and their wrist rotates.

Experimental analysis of thermoelectric generator using solar energy

In this paper, the performance of a 4×4 cm2 Bismuth Telluride based thermoelectric generator with 126 thermocouples connected in series is analyzed experimentally under different environmental conditions. The hot junction of the thermoelectric generator is exposed to solar and candle heat and the cold side is exposed to atmosphere. With the hot junction temperature of 53°C and cold junction temperature of 32°C, the output voltage, current and power are measured as 0.35V, 0.042A and 0.014W respectively. The hot junction of the thermoelectric generator is then exposed to solar concentrator heat and the cold side is exposed to ice. With the hot junction temperature of 100.2°C and cold junction temperature of 2.9°C, the output voltage, and power are measured as 2.96V, 0.1083A and 0.319W respectively. The power output is increased by 30.5%. The power density is 2.11μ Wcm-2 °C-2.

A Novel Design Approach of Reconfigurable Patch Antenna for Wireless Applications

In this paper we have proposed an innovative design for a reconfigurable micro strip patch antenna for wireless applications. It has a central patch antenna operating at 7.5 GHz called as driven patch; with two adjacent wing patches which when connected with the central patch reconfigure the operating frequency to 5.5 GHz and 2.9 GHz. The design is performed by using 3D electromagnetic simulator HFSS considering ideal MEMS switches.