Browsing by Subject "Electrical and Computer Engineering"

Now showing 1 - 4 of 4
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    Computational study of confined states in quantum dots by an efficient finite difference method.
    (2010-01) Butt, Salman
    Semiconductor quantum dot systems have gained more attention in quantum computation and optoelectronic applications due to the ease of bandstructure tailoring and three-dimensional quantum confinement. Thus, an accurate solution of energy bandstructure within the quantum dot is important for device design and performance evaluation. In this paper, the solutions of bandstructures of quantum dot systems are presented by implementing finite difference technique. To illustrate our analysis procedure, various configurations of quantum dot systems were taken into account. In order to improve the calculation efficiency of the finite difference solution in terms of time and memory consumption, uneven divisions for the quantum dot confinement region were used. In addition, we identified the optimum combination of divisions for each geometrical configuration. Eventually, the eigenstate wavefunctions and eigenvalues were obtained by directly solving the eigen-value problems. Overall, the generated results agreed consistently with the published results obtained by other solution techniques.
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    Design of a fourth-order continuous-time delta-sigma A/D modulator with clock jitter correction.
    (2009-10) Chang, Hairong
    In recent years, there has been growing interest in both industry and academia to use delta-sigma A/D converters for wideband wireless communication applications. Continuous-time (CT) delta-sigma modulators (ΔΣM) are of particular importance, mainly due to their advantages in terms of low power consumption, low noise, high speed and inherent anti-aliasing filtering capability. However, they are much more sensitive to clock jitters than their digital-time (DT) counterparts, limiting their practical applications. In this project, we present a CT delta-sigma modulator design that can significantly reduce the clock jitter effects. A top-down methodology is utilized starting from the system-level design, and then followed by circuit-level design. In the system-level design, key design challenges are addressed and various non-ideal effects including clock jitter effects are modeled with MATLAB/SIMULINK to determine the specifications for each building block. In particular, it is shown that a simple fixed-width return-to-zero (RZ) current feedback technique can effectively reduce the SNR loss caused by clock jitters. System-level simulation outputs are then used as input constraints for the circuit-level design, which consists of a 1.5V CT ΔΣM in IBM 0.13μm process compatible for use with the WCDMA technology. The building blocks include operational transconductance amplifiers (OTAs), comparator, return-to-zero logic circuit, digital-to-analog (DAC) current feedback blocks and summing block. Circuit design and layout were completed using Cadence Design Systems software. Simulations show that this ΔΣM circuit has a SNR of 65.5dB for a 0.1V input at 468.75kHz.
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    Heart murmur detection/classification using Cochlea-like pre-processing.
    (2010-01) Ahmad, Waqas
    Accurate detection and classification of pathological heart murmurs by auscultation has been a challenge for physicians for a long time. Many research efforts have been made to apply artificial intelligence (AI) for rigorous detection/classification of heart murmurs but reported success rates have been low. All of the current AI techniques rely on converting the heart sounds to electrical signals and processing those signals via electronic circuitry of AI for murmur detection and classification. In this research, we have used a novel approach to pre-process the electrical heart sound signals by altering the electrical signal in a similar way as is done by human cochlea before they go to AI for murmur detection/classification. Cochlea-like pre-processing changes the spectral contents of the heart sound signal to enhance the murmur information which can then be detected and classified more accurately by AI circuitry. We have designed a heart murmur detection/classification system based upon this approach and have tested this system using simulated heart sounds of various murmur types. Our test results show that this approach significantly improves heart murmur detection/classification accuracy.
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    Vehicle driver message alert system using DSRC/WAVE and bluetooth.
    (2009-12) Roodell, Beau Duane
    To save lives and prevent injuries on roadways, inter-vehicle communication as well as communication between vehicles and roadside is required. Intelligent Transportation system (ITS) is a mission of the US department of transportation which focuses on intelligent vehicles, intelligent infrastructure and the creation of an intelligent transportation system through integration with and between these two components. Dedicated Short Range Communications (DSRC) is a tool approved for licensing by the FCC in 2003 which promises to partially fulfill this mission. This research utilizes DSRC infrastructure to communicate the traffic safety information available at the roadside to a Bluetooth enabled cell phone inside the vehicle. A major objective of this research project was to design, build and demonstrate a wireless communication interface device which can act as a traffic-safety-information transportation agent between the DSRC vehicle radio unit and a Bluetooth enabled cell phone inside a vehicle. By having this interface device along with the DSRC radio unit in a vehicle as a separate entity or integrated with a DSRC unit, any driver will be able to receive the valuable traffic safety messages on his Bluetooth enabled cell phone. The system prototype was designed and built. The demonstration was given for multiple road and traffic scenarios by successfully transmitting the traffic safety messages to the Bluetooth enabled cell phone. This prototype system can be used as a building block for a diverse array of traffic safety applications.