On an Integrated Transfer Matrix method for multiply connected mufflers

The commercial automotive mufflers are generally of a complicated shape with multiply connected parts and complex acoustic elements. The analysis of such complex mufflers has always been a great challenge. In this paper, an Integrated Transfer Matrix method has been developed to analyze complex mufflers. Integrated transfer matrix relates the state variables across the entire cross-section of the muffler shell, as one moves along the axis of the muffler, and can be partitioned appropriately in order to relate the state variables of different tubes constituting the cross-section. The paper presents a generalized one-dimensional (1-D) approach, using the transfer matrices of simple acoustic elements, which are available from the literature. The present approach is robust and flexible owing to its capability to construct an overall matrix of the muffler with the transfer matrices of individual acoustic elements and boundary conditions, which can then be used to evaluate the transmission loss, insertion loss, etc. Results from the present approach have been validated through comparisons with the available experimental and three-dimensional finite element method (FEM) based results. The results show good agreement with both measurements and FEM analysis up to the cut-off frequency. (C) 2011 Elsevier Ltd. All rights reserved.

Self Repair in Circuits-Automating Open Fault Repair in Integrated Circuits Using Field-Induced Aggregation of Carbon Nanotubes

This paper presents studies on the use of carbon nanotubes dispersed in an insulating fluid to serve as an automaton for healing open-circuit interconnect faults in integrated circuits. The physics behind the repair mechanism is the electric-field-induced diffusion limited aggregation. On the occurrence of an open fault, the repair is automatically triggered due to the presence of an electric field across the gap. We perform studies on the repair time as a function of the electric field and dispersion concentrations with the above application in mind.

INST: An Integrated Steering Framework for Critical Weather Applications

Online remote visualization and steering of critical weather applications like cyclone tracking are essential for effective and timely analysis by geographically distributed climate science community. A steering framework for controlling the high-performance simulations of critical weather events needs to take into account both the steering inputs of the scientists and the criticality needs of the application including minimum progress rate of simulations and continuous visualization of significant events. In this work, we have developed an integrated user-driven and automated steering framework INST for simulations, online remote visualization, and analysis for critical weather applications. INST provides the user control over various application parameters including region of interest, resolution of simulation, and frequency of data for visualization. Unlike existing efforts, our framework considers both the steering inputs and the criticality of the application, namely, the minimum progress rate needed for the application, and various resource constraints including storage space and network bandwidth to decide the best possible parameter values for simulations and visualization.

Substrate integrated Lead-Carbon hybrid ultracapacitor with flooded, absorbent glass mat and silica-gel electrolyte configurations

Lead-Carbon hybrid ultracapacitors (Pb-C HUCs) with flooded, absorbent-glass-mat (AGM) and silica-gel sulphuric acid electrolyte configurations are developed and performance tested. Pb-C HUCs comprise substrate-integrated PbO2 (SI-PbO2) as positive electrodes and high surface-area carbon with graphite-sheet substrate as negative electrodes. The electrode and silica-gel electrolyte materials are characterized by XRD, XPS, SEM, TEM, Rheometry, BET surface area, and FTIR spectroscopy in conjunction with electrochemistry. Electrochemical performance of SI-PbO2 and carbon electrodes is studied using cyclic voltammetry with constant-current charge and discharge techniques by assembling symmetric electrical-double-layer capacitors and hybrid Pb-C HUCs with a dynamic Pb(porous)/PbSO4 reference electrode. The specific capacitance values for 2 V Pb-C HUCs are found to be 166 F/g, 102 F/g and 152 F/g with a faradaic efficiency of 98%, 92% and 88% for flooded, AGM and gel configurations, respectively.

Integrated parallelization of computations and visualization for large-scale applications

Critical applications like cyclone tracking and earthquake modeling require simultaneous high-performance simulations and online visualization for timely analysis. Faster simulations and simultaneous visualization enable scientists provide real-time guidance to decision makers. In this work, we have developed an integrated user-driven and automated steering framework that simultaneously performs numerical simulations and efficient online remote visualization of critical weather applications in resource-constrained environments. It considers application dynamics like the criticality of the application and resource dynamics like the storage space, network bandwidth and available number of processors to adapt various application and resource parameters like simulation resolution, simulation rate and the frequency of visualization. We formulate the problem of finding an optimal set of simulation parameters as a linear programming problem. This leads to 30% higher simulation rate and 25-50% lesser storage consumption than a naive greedy approach. The framework also provides the user control over various application parameters like region of interest and simulation resolution. We have also devised an adaptive algorithm to reduce the lag between the simulation and visualization times. Using experiments with different network bandwidths, we find that our adaptive algorithm is able to reduce lag as well as visualize the most representative frames.

Integrated magnetics based multi-port bidirectional DC-DC converter topology for discontinuous-mode operation

A new type of multi-port isolated bidirectional DC-DC converter is proposed in this study. In the proposed converter, transfer of power takes place through addition of magnetomotive forces generated by multiple windings on a common transformer core. This eliminates the need for a centralised storage capacitor to interface all the ports. Hence, the requirement of an additional power transfer stage from the centralised capacitor can also be eliminated. The converter can be used for a multi-input, multi-output (MIMO) system. A pulse width modulation (PWM) strategy for controlling simultaneous power flow in the MIMO converter is also proposed. The proposed PWM scheme works in the discontinuous conduction mode. The leakage inductance can be chosen to aid power transfer. By using the proposed converter topology and PWM scheme, the need to compute power flow equations to determine the magnitude and direction of power flow between ports is alleviated. Instead, a simple controller structure based on average current control can be used to control the power flow. This study discusses the operating phases of the proposed multi-port converter along with its PWM scheme, the design process for each of the ports and finally experimental waveforms that validate the multi-port scheme.

A 12 V Substrate-Integrated PbO2-Activated Carbon Asymmetric Hybrid Ultracapacitor with Silica-Gel-Based Inorganic-Polymer Electrolyte

A 12 V Substrate-Integrated PbO2-Activated Carbon hybrid ultracapacitor (SI-PbO2-AC HUCs) with silica-gel sulfuric acid electrolyte is developed and performance tested. The performance of the silica-gel based hybrid ultracapacitor is compared with flooded and AGM-based HUCs. These HUCs comprise substrate-integrated PbO2 (SI-PbO2) as positive electrodes and high surface-area activated carbon with dense graphite-sheet substrate as negative electrodes. 12 V SI-PbO2-AC HUCs with flooded, AGM and gel electrolytes are found to have capacitance values of 308 F, 184 F, and 269 F at C-rate and can be pulse charged and discharged for 100,000 cycles with only a nominal decrease in their capacitance values. The best performance is exhibited by gel-electrolyte HUCs.

InSt: an integrated steering framework for critical weather applications

Online remote visualization and steering of critical weather applications like cyclone tracking are essential for effective and timely analysis by geographically distributed climate science community. A steering framework for controlling the high-performance simulations of critical weather events needs to take into account both the steering inputs of the scientists and the criticality needs of the application including minimum progress rate of simulations and continuous visualization of significant events. In this work, we have developed an integrated user-driven and automated steering framework InSt for simulations, online remote visualization, and analysis for critical weather applications. InSt provides the user control over various application parameters including region of interest, resolution of simulation, and frequency of data for visualization. Unlike existing efforts, our framework considers both the steering inputs and the criticality of the application, namely, the minimum progress rate needed for the application, and various resource constraints including storage space and network bandwidth to decide the best possible parameter values for simulations and visualization.

Design and analysis of integrated optic waveguide delay line for beamforming applications

This paper presents a new approach for Optical Beam steering using 1-D linear arrays of curved wave guides as delay line. The basic structure for generating delay is the curved/bent waveguide and hence its Analytical modelling involves evaluation of mode profiles, propagation constants and losses become important. This was done by solving the dispersion equation of a bent waveguide with specific refractive index profiles. The phase shifts due to S-bends are obtained and results are compared with theoretical values. Simulations in 2-D are done using BPM and Matlab.

Design of S bend waveguides for delay line applications in integrated optics

A novel scheme for generation of phase using optical delay lines is proposed. The design of the optical components in the circuit which includes the S bend waveguides and straight waveguide couplers are very important for integrated optics. Beam propagation Method and MatLab is employed for the design.

AFM cantilever with integrated piezoelectric thin film for micro-actuation

This work presents micro-actuation of atomic force microscopy (AFM) cantilevers using piezoelectric Zinc Oxide (ZnO) thin film. In tapping mode AFM, the cantilever is driven near its resonant frequency by an external oscillator such as piezotube or stack of piezoelectric material. Use of integrated piezoelectric thin film for AFM cantilever eliminates the problems like inaccurate tuning and unwanted vibration modes. In this work, silicon AFM cantilevers were sputter deposited with ZnO piezoelectric film along with top and bottom metallic electrodes. The self-excitation of the ZnO coated AFM cantilever was studied using Laser Doppler Vibrometer (LDV). At its resonant frequency (227.11 kHz), the cantilever displacement varies linearly with applied excitation voltage. We observed an increase in the actuation response (131nm/V) due to improved quality of ZnO films deposited at 200 degrees C.

Flexible Phynox Alloy with Integrated Piezoelectric Thin Film for Micro Actuation Application

In this paper, we report on the application aspect of piezoelectric ZnO thin film deposited on flexible phynox alloy substrate. Highly crystalline piezoelectric ZnO thin films were deposited by RF reactive magnetron sputtering and were characterized by XRD, SEM, AFM analysis. Also, the effective d(33) coefficient value measurement was performed. The actuator element is a circular diaphragm of phynox alloy on to which piezoelectric ZnO thin film was deposited. ZnO film deposited actuator element was firmly fixed inside a suitable concave perspex mounting designed specifically for micro actuation purpose. The actuator element was excited at different frequencies for the supply voltages of 2V, 5V and 8V. Maximum deflection of the ZnO film deposited diaphragm was measured to be 1.25 mu m at 100 Hz for the supply voltage of 8V. The developed micro actuator has the potential to be used as a micro pump for pumping nano liters to micro liters of fluids per minute for numerous biomedical and aerospace applications.

Analysis of integrated optofluidic lab-on-a-chip sensor based on refractive index and absorbance sensing

The analysis of a fully integrated optofluidic lab-on-a-chip sensor is presented in this paper. This device is comprised of collinear input and output waveguides that are separated by a microfluidic channel. When light is passed through the analyte contained in the fluidic gap, optical power loss occurs owing to absorption of light. Apart from absorption, a mode-mismatch between the input and output waveguides occurs when the light propagates through the fluidic gap. The degree of mode-mismatch and quantum of optical power loss due to absorption of light by the fluid form the basis of our analysis. This sensor can detect changes in refractive index and changes in concentration of species contained in the analyte. The sensitivity to detect minute changes depends on many parameters. The parameters that influence the sensitivity of the sensor are mode spot size, refractive index of the fluid, molar concentration of the species contained in the analyte, width of the fluidic gap, and waveguide geometry. By correlating various parameters, an optimal fluidic gap distance corresponding to a particular mode spot size that achieves the best sensitivity is determined both for refractive index and absorbance-based sensing.