Engineering Commons^™

A Study Of Probability Distributions Of Dct Coefficients In Jpeg Compression, Gopal Thirumalai Narayanan

Theses

The Discrete Cosine Transform (DCT) used in JPEG compression has shown excellent energy compaction properties that rival that of the ideal Karhunen-Loève Transform. Lossy compression in JPEG is achieved by distorting 8x8 block DCT coefficients through quantization. It has been shown in literature that DC block DCT coefficients are Gaussian probability distributed and AC block DCT coefficients are Generalized Normal probability distributed.

In this investigation, three probability density models for individual modes of non- quantized AC block DCT coefficients are evaluated and are used as basis for the derivation of probability distributions for quantized block DCT coefficients. The suitability of …

Papr Reduction In Ofdm Communications With Generalized Discrete Fourier Transform, Sertac Sayin

Theses

The main advantage of Generalized Discrete Fourier Transform (GDFT) is its ability to design a wide selection of constant modulus orthogonal code sets, based on the desired performance metrics mimicking the engineering specs of interest. One of the main drawbacks of Orthogonal Frequency Division Multiplexing (OFDM) systems is the high Peak to Average Power Ratio (PAPR) value which is directly related to power consumption of the system. Discrete Fourier Transform (DFT) spread OFDM technology, also known as Single Carrier Frequency Division Multiple Access (SCFDMA), which has a lower PAPR value, is used for uplink channel.

In this thesis, the PAPR …

A Comparison Of Software Engines For Simulation Of Closed-Loop Control Systems, Sanket D. Nikam

Theses

A wide array of control system design and simulation software engines is available in market. It includes MATLAB-Simulink, LabVIEW, Maple-MapleSim, Scilab-Scicos, VisSim and Mathematica-Control Professional Suite (CPS). Among all of them MATLAB-Simulink is dominant and widely used software engine. The main aim of this study is to implement different state space control methods for non-linear Furuta pendulum system in each one of them and to compare performance against MATLAB-Simulink.

Different parameters like learning curve, interoperability, flexibility, control design tools, documentation and tech support are considered for efficiency comparison. It is shown that MapleSim has multi-body intuitive physical modeling (acausal) approach …

Power Flow In Railway Electrification Power System, Sisi Li

Theses

This thesis discusses aspects of the design of the railway electrification system (RES) and in particular the electric distribution system for a 2x25 kV railway power system.

The analysis of Railway Power Supplies (RPS) presents a unique type of load flow problem which is characterized by its constant moving loads, dynamically changing load types (constant current/constant power), and its specialized network structure. The autotransformer power supply system with double track was the system studied in this thesis.

The details of the system studied were provided by Caltrain (California Commuter Rail) for a planned high speed extension to Caltrain system. A …

Study Of Methods To Predict Voltage Collapse, Niki Patel

Theses

One of the problems that must be addressed for a secure power system operation is the voltage collapse problem. The ever increasing size and connectivity of the power grid have lead to making the problem more multifarious. Widespread blackouts, similar to the one that occurred in the northeast in August 2003, could result from failure to address the problem.

This thesis presents an overview of the voltage collapse problem and reviews some existing methods to calculate voltage collapse indicators.

Thevenin and Maximum Power Transfer Theorems are used to provide indicators of the proximity of the system to voltage collapse. The …

A Fpga/Dsp Based Ultrasound System For Tumor Detection, Ashish Ravindra Ratnakar

Theses

This work presents a method of detection of size and location of tumor using ultrasound transmission. The system utilizes Quantitative Ultrasound (QUS) which means sending an ultrasound signal from a transmitter and receiving it at multiple receivers. This received signal is analyzed for echogenic as well as echolucent tumors to differentiate between the two along with non-tumorous sample and also for delay, signal distortion to determine the size/location of the tumor.

This analysis is further implemented using Field Programmable Gate Array (FPGA) and Digital Signal Processor (DSP) technologies. The proposed detection system utilizes Low Transient Pulse (LTP) technique. In this …

A Fpga/Dsp Design For Real-Time Fracture Detection Using Low Transient Pulse, Akash Mathur

Theses

This work presents the hardware and software architecture for the detection of fractures and edges in materials. While the detection method is based on the novel concept of Low Transient Pulse (LTP), the overall system implementation is based on two digital microelectronics technologies widely used for signal processing: Digital Signal Processor (DSP) and Field Programmable Gate Array (FPGA). Under the proposed architecture, the DSP carries out the analysis of the received baseband signal at a lower rate and hence can be used for large number of signal channels. The FPGA's master clock runs at a higher frequency (62.5MHz) for the …

Sparse Representation For Audio Noise Removal Using Zero-Zone Quantizers, Neha Mittal

Theses

In zero zone quantization, bins around zero are quantized to a zero value. This kind of quantization can be applied on orthogonal transforms to remove the unwanted or redundant signal. Transforms reveal structures and properties of a signal and hence careful application of a zero zone over the transform coefficients leads to noise removal. In this thesis, such quantizers are applied over Discrete Fourier Transform and Karhunen Loeve Transform coefficients separately, and outputs compared. Further, the localization of the zero zones to certain frequencies leads to better performance in terms of noise removal. PEAQ (Perceptual Evaluation of Audio Quality) scores …