Performance Improvisation of Cantilever-type Silicon Micro AccelerationSensors Using Stress Concentration Regions Technique

Acceleration sensors find applications in missile and competent munitions subsystems.Cantilever-type sensor's sensitivity and bandwidth are dependant on material properties of  thecantilever and structure of proof mass. It is always desired to design a sensor as sensitive aspossible but also maintaining higher bandwidth. In piezoresistive (cantilever-type) accelerometers,various techniques were employed by designers to enhance their sensitivity and bandwidth.Most of these techniques are usually focused on shape and size of either cantilever or proofmass. This paper presents a concept of creating stress concentration regions (SCRs) on thecantilever for enhancing its sensitivity. Five types of structures were simulated to study thebehaviour of piezoresistive sensors with SCRs implementation. Use of SCRs results in substantialincrease in the sensitivity, which is of the order of 1.85 times the nominal sensitivity. It was aimedat maximising sensor's performance factor, which is the product of sensor bandwidth andsensitivity. This study gives new dimension to the ways of improving performance of cantilever-type inertial piezoresistive sensor

Optimising Performance of a Cantilever-type Micro Accelerometer Sensor

A technique for optimising performance of cantilever-type micro acceleration sensor hasbeen developed. Performance of a sensor is judged mainly by its sensitivity and bandwidth.Maximising product of these two important parameters of inertial sensors helps to optimise thesensor performance. It is observed that placement of a lumped mass (add-mass) on the sensor'sproof-mass helps to control both sensitivity and the first resonant frequency of the cantileverstructure to the designer's choice. Simulation and modelling of various dimensions of rectangularstructures for acceleration sensor with this novel add-mass technique are discussed. CoventorwareMEMSCAD has been used to model, simulate, and carry out FEM analysis. A simple analyticalmodel is discussed to elaborate the mechanics of cantilever-type micro accelerometer. Thecomparison of the results obtained from analytical model and the finite element simulations revealthese to be in good agreement. The advantages of this technique for choosing the two mostimportant sensor parameters (i.e., sensitivity and bandwidth) of an inertial sensor are brought out

Co-Simulation of IBC Type PFC Converter with Fuzzy Logic Controller

Many electronic power systems use bridge rectifiers, which are nonlinear, resulting in low power factor activity and high harmonic distortion due to the existence of nonlinear devices. To conform to harmonic standard requirements, longer device lifetime, and smooth operation of other devices in the system, power factor correction is required in these devices. The proposed system with an input power supply linked to a bridge rectifier which transforms ac to dc in this analysis, which is then linked to an Interleaved Boost Converter (IBC) with two parallel boost converters. The Interleaved Boost Converter uses Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) to work with the switches. The proportional controller gain has the effect of minimizing the time of increase and does not remove the error of steady-state. The result of removing the steady-state error is an integral control gain but deteriorate the transient response. The fuzzy controller takes inputs from the actual signals feedback values. Using the membership functions in the fuzzification method, the data provided to the fuzzy system is transformed into linguistic variables. To evaluate the performance, a series of rules that mimic the decision-making process of the human expert running the machine is then implemented using such inference mechanisms. Finally, a defuzzification block that transforms the output to a crisp value in such a manner that both structures are consistent. The proposed method is implemented using the software of MATLAB/Simulink and PSIM. The co-simulation result shows that the power factor achieved here is 0.9988, the Total Harmonic Distortion (THD) maintained is less than 5% and the average efficiency concluded here is 98% respectively. To verify the feasibility of the proposed scheme, a prototype model of a 5kW IBC type PFC converter is developed which is converting 230V AC input voltage to 400V DC output voltage, is implemented using a Microchip IC dsPIC33FJ16GS504. The experimental results are satisfactory, which uncover that a power factor is 0.9992 (close to unity), THD is 4.11; less than 5% and 98% overall efficiency at 100 kHz switching frequency, 230Vrms input voltage. With the higher performance, as a result, topology with high switching frequency makes a more compact, but costlier converter

Article 4 Usher Syndrome: Case Reports of Two Siblings

ABSTRACT Background: Usher syndrome is a rare autosomal recessive disorder characterized by congenital sensory neural deafness and progressive visual loss secondary to retinitis pigmentosa. There are three different types of Usher syndrome. Retinitis pigmentosa is the main ophthalmic manifestation shared by all three. Differences in auditory and vestibular function are the distinguishing feature

Experimental Investigations of Alpha Particle Irradiation of Natural Nickel

Attempts have been made to measure the activity in irradiated natural Ni material induced by α-particles in the energy range 10-40 MeV followed by stack foil activation technique. Activity induced has been determined through the cross-sections obtained from various reactions for 58Ni(α, p)61Cu, 58Ni(α,  pn)60Cu, 60Ni(α, p2n)61Cu, 60Ni(α, n)63Zn, 60Ni(α, 2n)62Zn,61Ni(α, 3n)62Zn and 61Ni(α, 2n)63Zn in α+natNi interaction at different beam energies has been found to vary from 10-26 microns

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV

The Lambda(b) differential production cross section and the cross section ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Lambda(b) decays reconstructed in the exclusive final state J/Psi Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and Lambda to proton pion, using a data sample corresponding to an integrated luminosity of 1.9 inverse femtobarns. The product of the cross section times the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls faster than that of b mesons. The measured value of the cross section times the branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06 +/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are statistical and systematic, respectively.Comment: Submitted to Physics Letters