A Study of Aerodynamic Performance of a Contra Rotating Axial Compressor Stage

This article presents an experimental investigation into the effect of speed ratio and axial spacing between contra-rotors on the aerodynamic performance of a contra-stage. The traverses of flow structure and pressure variation are examined at upstream of the first and the second rotor to illustrate the effect of speed ratio and axial spacing on the aerodynamic performances. The traverse results are analysed to obtain relative total head loss and blade element efficiency of the contra-rotors. The reveals that the aerodynamics of a contra-stage is significantly affected by the speed ratio as well as the axial spacing between contra-rotors

Intuitionistic Fuzzy Soft Set Theory and Its Application in Medical Diagnosis

For finding coherent and logical solution to various real life problems containing uncertainty, impreciseness and vagueness, fuzzy soft set theory is gaining importance. Later on a theoretical study of the intuitionistic fuzzy soft set was developed. The combination of intuitionistic fuzzy set and intuitionistic fuzzy soft set are more useful for application point of view in the field wherever uncertainty due to vagueness appear in more complex form. In the present communication the concepts of fuzzy soft set and Intuitionistic fuzzy soft Set are defined as hybridization of fuzzy set and soft set theory. A new method of application of intuitionistic fuzzy soft set is studied in Medical Diagnosis following Sanchez’s approach. A hypothetical case study is also discussed in brief using the proposed method

A Study of Aeroacoustic Performance of a Contra-Rotating Axial Flow Compressor Stage

The paper reports of an experimental investigation into the aeroacoustic performance of a contra-rotating axial flow compressor stage having a hub-tip ratio of 0.66. Aerodynamic superiority of a contra-stage is examined from the point of view of higher pressure rise, increased through flow and rotating stall suppression. Measurements of sound pressure level and real-time analysis of the noise signals is reported for two axial gap between the rotors on the aeroacoustic performance is discussed. The study reveals that the axial gap between the rotors significantly affects the aeroacoustic performance of a contra-stage

Static Analysis of Electrostatically Actuated Micro Cantilever Beam

AbstractElectrostatically actuated micro devices experience a fundamental limit on their stable travel range due to a phenomenon called as the pull-in Instability. Accurate determination of pull-in parameters (pull-in displacement and pull-in voltage) is vital in the design of electrostatic micro actuators. A systematic method of analysis of prismatic type of electrostatic beam is discussed in this paper. Using Galerkin method static analysis is carried out. Behaviour of interaction of nonlinear electrostatic force with linear restoring force of the micro cantilever beam is studied. Static analysis using COMSOL multiphysics finite element package is done to validate the results. The results are also compared with existing literature

Crack Detection in Cantilever Beam by Frequency based Method

AbstractDuring the last few decades, intense research on the detection of crack using the vibration based techniques has been done and various approaches have been developed by researchers. In the present paper, detection of the crack presence on the surface of beam-type structural element using natural frequency is presented. First two natural frequencies of the cracked beam have been obtained experimentally and used for detection of crack location and size. Detected crack locations and size are compared with the actual results and found to be in good agreement. Also, the effect of the crack location and the crack depth on the natural frequency is presented

Modelling and Analysis of Emitter Geolocation using Satellite Tool Kit

This paper considers geolocation of a stationary radio frequency emitter which is being steered by multiple antennas installed on a geostationary satellite using received signal strength metric. The difference in the signal strengths is measured by the antennas and subsequently plotted as lines of position on the surface of the earth. Intersection of these two or more lines of position indicates the location of the terrestrial radio frequency transmitters. This problem is appropriately modelled using a satellite tool kit that simulates the space environment involving satellites, antennas, emitters, etc in a realistic and integrated manner. Accuracy and size of the geolocation area depend on the distance between emitters and the receiver and also on the contour widths geometry. Results of geolocation accuracy are compared by installing the radio frequency emitter at increasing latitudes and at varying contour widths. It is observed that the emitters placed at lower latitudes and having smaller contour widths provided higher accuracy in geolocation that validates the proposed formulation

Dry Etching of GaAs to Fabricate Via-Hole Grounds in Monolithic Microwave Integrated Circuits

This study investigates the dry etching of 60 mm dia, 200 mm deep holes for fabrication of through substrate via holes for grounding monolithic microwave integrated circuits (MMICs), on 3-inch dia semiinsulating GaAs wafer using RIE and ICP processes with CFC and non-CFC gas chemistry, respectively. The effect of various process parameters on GaAs etch rate and resultant etch profile was investigated. Two kinds of masks, photoresist and Ni, were used to etch GaAs and performance was compared by investigating effect on etch rate, etch depth, etch profile, and surface morphology. The etch profile, etch depth, and surface morphology of as-etched samples were characterised by scanning electron microscopy. The desired 200 mm deep strawberry profile was obtained at 40 mTorr for both RIE and ICP processes with an etch rate of ~1.3 mm/min and ~4 mm/min respectively. Ni metal mask was used for RIE process due to poor photoresist selectivity, whereas ICP process utilised photoresist as mask. The vias were then metallised by depositing a thin seed layer of Ti/Au (1000 Å) using radio frequency sputtering and Au (~5 mm) electroplated to connect the frontside pad and back side ground plane. The typical parasitic inductance offered by these via for RIE and ICP processes was ~76 pH and 83 pH respectively, which is well within the acceptable limits. The developed process was finally integrated to in-house MMIC production line.Defence Science Journal, 2009, 59(4), pp.363-370, DOI:http://dx.doi.org/10.14429/dsj.59.153

Quantization of adiabatic pumped charge in the presence of superconducting lead

We investigate the parametric electron pumping of a double barrier structure in the presence of a superconducting lead. The parametric pumping is facilitated by cyclic variation of the barrier heights $x_1$ and $x_2$ of the barriers. In the weak coupling regime, there exists a resonance line in the parameter space $(x_1,x_2)$ so that the energy of the quasi-bound state is in line with the incoming Fermi energy. Levinson et al found recently that the pumped charge for each pumping cycle is quantized with $Q=2e$ for normal structure when the pumping contour encircles the resonance line. In the presence of a superconducting lead, we find that the pumped charge is quantized with the value $2e$