Thesis (M.S.)--State University of New York at Binghamton, Electrical Engineering Dept., 2006. / Includes bibliographical references.

Modular Multiplication is a time-consuming arithmetic operation because it involves multiplication as well as division. Modular exponentiation can be performed as a sequence of modular multiplications. Speeding the modular multiplication increases the speed of modular exponentiation. Modular exponentiation and modular multiplication are heavily used in current cryptographic systems. Well-known cryptographic algorithms, such as RSA and Diffie-Hellman key exchange, require modular exponentiation operations. Elliptic curve cryptography (ECC) needs modular multiplication. Information security is increasingly becoming very important. Encryption and Decryption are very likely to be in many systems that exchange information to secure, verify, or authenticate data. Many systems, like the Internet, cellular phones, hand-held devices, and E-commerce, involve private and important information exchange and they need cryptography to make it secure. There are three possible solutions to accomplish the cryptographic computation: software, hardware using application-specific integrated circuits (ASICs), and hardware using field-programmable gate arrays (FPGAs). The software solution is the cheapest and most flexible one. But, it is the slowest. The ASIC solution is the fastest. But, it is inflexible, very expensive, and needs long development time. The FPGA solution is flexible, reasonably fast, and needs shorter development time. Montgomery multiplication algorithm is a very smart and efficient algorithm for calculating the modular multiplication. It replaces the division by a shift and modulus-addition (if needed) operations, which are much faster than regular division. The algorithm is also very suitable for a hardware implementation. Many designs have been proposed for fixed precision operands. A word-based algorithm and the scalable Montgomery multiplier based on this algorithm have been proposed later. The scalable multiplier can be configured to meet the design area-time tradeoff. Also, it can work for any operand precision up to the memory capacity. In this thesis, we develop a prototyping environment that can be used to verify the functionality of the scalable Montgomery multiplier on the circuit level. All the software, hardware, and firmware components of this environment will be described. Also, we will discuss how this environment can be used to develop cryptographic applications or test procedures on top of it. We also present two FPGA designs of the processing unit of the scalable Montgomery multiplier. The FPGA design techniques that have been used to optimize these designs are described. The implementation results are analyzed and the designs are compared against each other. The FPGA implementation of the first design is also compared against its ASIC implementation. / Graduation date: 2003

Telomeres are specialized nucleoprotein structures found at the end of eukaryotic chromosomes. The telomere DNA in humans is composed of the sequence "5'-TTAGGG-3'" tandemly repeated in a stretch of 5-30kb of double stranded DNA. TTAGGG Repeat Factor 2 (TRF2) is a telomere DNA binding protein that has a critical role in telomere end protection. The current model for telomere protection by TRF2 is through its ability to remodel telomeres into looped higher-order structures, called the t-loop, which sequesters the end from DNA damage sensors. Since telomeres are known to be comprised of nucleosomal chromatin, it is important to determine how TRF2 binds to and affects the structure of nucleosomal arrays. The ability of TRF2 to bind to unusual DNA structures such as the t-loop and the single stranded/double (ss/ds) stranded telomere DNA junction may facilitate its binding to DNA in the form of nucleosomal arrays and promote higher-order chromatin structures. In this study, we have reconstituted a 2kb DNA fragment containing 550bp of telomere DNA into nucleosomal arrays and tested the binding of full-lengthTRF2 and four truncation mutants to telomeric nucleosomal arrays. Our data indicates that TRF2 and its truncation mutants bind to telomere nucleosomal arrays as well as it binds to telomere DNA. We used a novel electrophoretic technique, Analytical Agarose Gel Electrophoresis (AAGE), to measure changes in surface charge density, hydrodynamic radius, and conformational flexibility of DNA and nucleosomal arrays upon protein binding. Our results indicate that the C-terminal DNA binding Myb/SANT domain of TRF2 might be rearranging nucleosomal structure through either nucleosome sliding, unwrapping, or changing the arrangement of the linker DNA, while the N-terminal basic DNA binding region is causing nucleosomal arrays compaction. Instead of significant compaction, histone-free DNA undergoes DNA condensation and self-association. This activity is observed with the full-length protein and all regions of the protein, with the exception of TRF2-DBD, participate in the process. We speculate that the ability of TRF2-DBD to rearrange nucleosomal structure and N-terminal basic region to cause nucleosomal fiber compaction may allow TRF2 to promote t-loop formation in the context of chromatin. We propose that TRF2, possessing all the features, has a new role at telomeres as a chromatin architectural protein.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Cognitive radio networks require the use of computational resources to reconfigure transmit/receive parameters to improve communication quality of service or efficiency. Recent emergence of smart phones has made these resources more accessible and mobile, combining sensors, geolocation, memory and processing power into a single device. Thus, this work examines an integration of a smart phone into a complex radio network that controls the beam direction of a phased array using a conventional method, but utilizes the phone's internal sensors as an enhancement to generate beam direction information, Bluetooth channel to relay information to control circuitry, and Global Position System (GPS) to track an object in motion. The research and experiments clearly demonstrate smart phone's ability to utilize internal sensors to generate information used to control beam direction from a phased array. Computational algorithms in a network of microcontrollers map this information into a DC bias voltage which is applied to individual phase shifters connected to individual array elements. To test algorithms and control theory, a 4 by 4 microstrip patch array is designed and fabricated to operate at a frequency of 2.4 GHz. Simulations and tests of the array provide successful antenna design results with satisfactory design parameters. Smart phone control circuitry is designed and tested with the array. Anechoic test results yield successful beam steering capability scanning 90 degrees at 15 degree intervals with 98% accuracy in all cases. In addition, the system achieves successful beam steering operable over a bandwidth of 100 MHz around resonance. Furthermore, these results demonstarate the capability of the smart phone controlled system to be used in testing further array formations to achieve beam steering in 3-Dimensional space. It is further noted that the system extends capabilities of integrating other control methods which use the smart phone to process information.

This study presents a new process to fabricate gapless triangular micro-lens array (GTMA). The process includes optical simulation with tracepro, UV lithography, photoresist reflow process, Ni electroplating and hot embossing technique. After photoresist triangular column array is defined using UV lithography, reflow process is applied to melt photoresist triangular column array into the shape of triangular micro-lens array. With this reflowed triangular micro-lens array, Ni is deposited and covered uniformly on the triangular micro-lens array using electroplating. The growth rate of Ni is controlled at electroplating current density of 1 Ampere Square Decimeter (ASD; A/dm2). After this electroplating process is finished, a mold of GTMA is obtained, which is served as primary mold. Subsequently, with passivation technique applied on this mold¡¦s surface, electroplating process is applied again to obtain a secondary mold. Next, this secondary mold is served as master for the subsequent hot embossing process to replicate the GTMA pattern onto polymeric material PMMA and PET sheet. The mold with stiffness and hardness plays an important role in GTMA hot embossing process. In addition, this GTMA used as optical film can offer a 100 % fill factor and a simulation of optical coupling efficiency of 66.7% to improve luminance of backlight module (BLM). In addition, this study presents the fabricated molds of GTMA with different aspect-ratio about 0.109 and 0.133. The optical measurement of BLM shows that this optical film of GTMA pattern with aspect-ratio about 0.109 can increase 15.1% of luminance and with aspect-ratio about 0.133 can increase 22.1% of luminance.

Design of antenna arrays for present day requirements has to take into account both mechanical and electrical aspects. Mechanical aspects demand the antennas to have low profile, non-protruding structures, structures compatible to aerodynamic require­ments and so on. Electrical aspects may introduce several constraints either due to. technical reasons or due to readability conditions in practice. Thus, arrays of modern requirements may not fall into the category of linear or planar arrays. Further, due to the nearby environment, the elements will generate complicated individual patterns. These issues necessitate the analysis and synthesis of antenna arrays which are arbi­trary as far as the orientation, position or the element pattern are concerned. Such arrays which may be called arbitrary arrays are being investigated in this thesis. These investigations have been discussed as different aspects as indicated below: Radiation Characteristics of Arbitrary Arrays Radiation fields of an arbitrarily oriented dipole are obtained. Such fields are plotted for typical cases. Further, methods for transforming the electromagnetic fields are discussed. Having obtained the field due to an arbitrary element, the fields due to an arbitrary array are obtained. Factors controlling the radiation fields, like, the curvature in the array and element pattern are investigated. Radiation patterns of circular and cylindrical arrays are plotted. Synthesis of a Side Lobe Topography Requirements of a narrow beam pattern generated by an antenna array are identified. A problem of synthesizing such a pattern using an arbitrary array is formulated. The envelope of the side lobe region which may be called, the side lobe topography (sit), is included in the computation of the covariance matrix. This problem which has been formulated as a problem of minimizing a quadratic function subjected to a system of linear constraints is solved by the method of Lagrangian multipliers. An iterative procedure is used to satisfy all the requirements of the pattern synthesis. The procedure has been validated by synthesizing linear arrays and is used to synthesize circular and parabolic arrays. Patterns with tapered sit, Taylor-like sit have been synthesized. Asymmetric patterns are also synthesized. Role of sit is brought out. Shaped Beam Synthesis Synthesis of shaped broad beams is discussed. Amplitude constraints are formulated. Phase distribution is linked with the phase centre. Quadratic problems thus formu­lated are solved by the Lagrangian method of undetermined multipliers. An iterative procedure is made use of to synthesize flat topped beams as well as cosecant squared-patterns using linear arrays as well as circular arrays. Reasonable excitation dynamic has been obtained. Optimum phase centres obtained by trial and error are made use of. Effects of the Frequency and Excitation on the Synthesized Patterns In general, synthesized patterns can be sensitive towards any specific parameter either excitation or to frequency or any such parameter. Several methods can be used to observe these issues. In this thesis, these effects are also studied. Using a specific array configuration, to synthesize a specified radiation pattern, frequency is changed by 10% from the design frequency and the pattern is computed. Similarly, excitation phase distribution is rounded to the nearest available phase distribution using a digital phase shifter (say 8 bit) and the resulting pattern is computed. Further, excitation dynamic is also controlled by boosting the amplitudes of the array elements which are less than the permissible (i.e. the maximum excitation/allowed dynamic). Effects of these variations are also recorded. It appears that reasonable patterns can be obtained, in spite of significant variations in these parameters in most of the cases. Reconfigurable Arbitrary Arrays It would be very useful if a single array configuration can be used for different ap- plications. This may be either for the different phases of a single application or for different applications that may be required at different times. Attempts are made to synthesize a variety of patterns from a single array. Such arrays which may be called as reconfigurable arrays can be of much use. Obviously, the excitations are different for different patterns. Both narrow beams, as well as shaped broad beams, with different side lobe topographies have been synthesized using a single array.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Dec. 14, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Electrical and Computer Engineering, University of Alberta." Includes bibliographical references.

Thesis (M.S.)--University of Florida, 2002. / Title from title page of source document. Includes vita. Includes bibliographical references.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Harry Tyrer. Includes bibliographical references.