Multimedia Protection using Content and Embedded Fingerprints (Electronics Project)

Improved digital connectivity has made the Internet an important medium for multimedia distribution and consumption in recent years. At the same time, this increased proliferation of multimedia has raised significant challenges in secure multimedia distribution and intellectual property protection.
This dissertation examines two complementary aspects of the multimedia protection problem that utilize content fingerprints and embedded collusion-resistant fingerprints. The first aspect considered is the automated identification of multimedia using content fingerprints, which is emerging as an important tool for detecting copyright violations on user generated content websites. A content fingerprint is a compact identifier that captures robust and distinctive properties of multimedia content, which can be used for uniquely identifying the multimedia object.
In this dissertation, we describe a modular framework for theoretical modeling and analysis of content fingerprinting techniques. Based on this framework, we analyze the impact of distortions in the features on the corresponding fingerprints and also consider the problem of designing a suitable quantizer for encoding the features in order to improve the identification accuracy. The interaction between the fingerprint designer and a malicious adversary seeking to evade detection is studied under a game-theoretic framework and optimal strategies for both parties are derived.
We then focus on analyzing and understanding the matching process at the fingerprint level. Models for fingerprints with different types of correlations are developed and the identification accuracy under each model is examined. Through this analysis we obtain useful guidelines for designing practical systems and also uncover connections to other areas of research.
A complementary problem considered in this dissertation concerns tracing the users responsible for unauthorized redistribution of multimedia. Collusion-resistant fingerprints, which are signals that uniquely identify the recipient, are proactively embedded in the multimedia before redistribution and can be used for identifying the malicious users. We study the problem of designing collusion resistant fingerprints for embedding in compressed multimedia. Our study indicates that directly adapting traditional fingerprinting techniques to this new setting of compressed multimedia results in low collusion resistance. To withstand attacks, we propose an anti-collusion dithering technique for embedding fingerprints that significantly improves the collusion resistance compared to traditional fingerprints.

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Airline Reservation System in VB.net (Computer Project)

 This is a complete application for airline reservation programmed in VB.net

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Microfabrication and Analysis of Manifold Microchannel Coolers for Power Electronics (Mechanical Project)

This research presents the analysis and realization of a single phase high performance manifold microchannel cooler for improving the thermal and hydrodynamic performance of multi-chip power electronic modules. This heat exchanger, microfabricated directly into the substrate, enables higher power density electronic products by more efficiently removing the high levels of heat generated.

The improved thermal performance and efficiency of the heat exchanger is demonstrated using both numerical and experimental techniques. The improved heat removal is due to the reduction in the number of packaging layers between the device and the heat exchanger and by improvement in convective heat transfer.

In addition, the efficiency of the device is enhanced by minimizing fluid pressure drop through the use of large manifold channels to transport fluid to the cooling area and smaller crossover microchannels in the active cooling area. This combination of channels also improves the uniformity of the temperature distribution across the device.

The manifold microchannel coolers were fabricated and tested both with and without electrical isolation between the chip and the coolant. Experimentally, the coolers without electrical isolation demonstrated thermal resistivity values as low as 0.06 K/(W/cm2), which is up to a 50X improvement over a standard power package with significant size and weight reduction. The coolers with an incorporated aluminum nitride electrical isolation layer experimentally demonstrated up to a 15X improvement.

In addition to experimental results, the interaction between the manifold channels and multiple microchannels was numerically modeled and compared to simpler, one-dimensional approximations based on the Hagen-Poiseuille equation. The comparison shows that the one-dimensional model, while under-predicting total pressure drops, can provide insight into the effect of varying dimensions on system performance. The numerical models were used to identify the impact of varying dimensions across the entire length of the cooler, and a sensitivity analysis was performed with respect to system pressure drop, thermal resistance and uniformity. Additionally, large microchannel velocity gradients, some larger than 10X, were observed along the length of the device which impacts the chip non-uniformity. The simulations showed that when comparing the manifolded design to a comparable straight microchannel cooler, there is a 38X reduction in system pressure drop for similar thermal performance.

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Low Power Smartdust Receiver with Novel Applications and Improvements of an RF Power Harvesting Circuit (Electronics Project)

Smartdust is the evolution of wireless sensor networks to cubic centimeter dimensions or less. Smartdust systems have advantages in cost, flexibility, and rapid deployment that make them ideal for many military, medical, and industrial applications.
This work addresses the limitations of prior works of research to provide sufficient lifetime and performance for Smartdust sensor networks through the design, fabrication and testing of a novel low power receiver for use in a Smartdust transceiver. Through the novel optimization of a multi-stage LNA design and novel application of a power matched Villard voltage doubler circuit, a 1.0 V, 1.6 mW low power On-Off Key (OOK) receiver operating at 2.2 GHz is fabricated using 0.13 um CMOS technology.
To facilitate data transfer in adverse RF propagation environments (1/r^3 loss), the chip receives a 1 Mbps data signal with a sensitivity of -90 dBm while consuming just 1.6 nJ/bit. The receiver operates without the addition of any external passives facilitating its application in Smartdust scale (mm^3) wireless sensor networks. This represents an order of magnitude decrease in power consumption over receiver designs of comparable sensitivity.
In an effort to further extend the lifetime of the Smartdust transceiver, RF power harvesting is explored as a power source. The small scale of Smartdust sensor networks poses unique challenges in the design of RF power scavenging systems. To meet these challenges, novel design improvements to an RF power scavenging circuit integrated directly onto CMOS are presented. These improvements include a reduction in the threshold voltage of diode connected MOSFET and sources of circuit parasitics that are unique to integrated circuits.
Utilizing these improvements, the voltage necessary to drive Smartdust circuitry (1 V) with a greater than 20% RF to DC conversion efficiency was generated from RF energy levels measured in the environment (66 uW). This represents better than double the RF to DC conversion efficiency of the conventional power matched RF energy harvesting circuit. The circuit is integrated directly onto a 130 nm CMOS process with no external passives and measures only 300 um by 600 um, meeting the strict form factor requirement of Smartdust systems.

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