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Dissertations / Theses on the topic 'Symmetrical Designs'
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1
Raaphorst, Sebastian. "Branch-and-cut for symmetrical ILPs and combinatorial designs." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26749.
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Many combinatorial problems can be formulated as a 0-1 integer linear program (0-1 ILP), which consists of an objective function subject to linear constraints over 0-1 variables. A method called branch-and-cut has been successfully used to attack ILPs, but ILPs are still difficult to solve in practice.
The problems we investigate demonstrate large numbers of equivalent (isomorphic) solutions. We are only interested in generating one solution from each equivalence class. To accomplish this, we study and extend a method by Margot [22] that avoids con sidering unnecessary partial solutions by generating an isomorph-free search tree. We implement a branch-and-cut library, and solve combinatorial design problems involving t-designs, packings, coverings and intersecting set systems.
We experimentally analyze the strengths and limitations of our algorithms and determine when it is efficient to use isomorph-free branch-and-cut. Our framework generates new results and reproduces, in competitive time, existing ones.
2
O'Reilly, Regueiro Eugenia. "Flag-transitive symmetric designs." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401667.
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Sasian, Alvarado Jose Manuel. "Imagery of the bilateral symmetrical optical system." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184628.
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A brief study of the imagery of the bilateral symmetric optical system is presented. This study has been developed with a theoretical structure similar to that of the rotationally symmetric optical system and can be considered a generalization. It provides a simple, clear understanding of the main features of the imagery of the optical systems under consideration. and gives useful design insight. Some design examples are provided that illustrate the use and value of the theory developed.
4
Walker, Alan. "Symmetrical Speech: Qualitative Textual Analysis In Humanist Digital Design." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1492772935620825.
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5
Dawson, Edward Pyle. "Design and cryptanalysis of symmetric ciphers." Thesis, Queensland University of Technology, 1991.
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6
York, Nathan S. "Design of a phase sampled interferometry antenna using the robust symmetrical number system." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA387462.
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Thesis (M.S. in Applied Physics) Naval Postgraduate School, Dec. 2000.Thesis advisor(s): Cooper, Alfred W. "December 2000." Includes bibliographical references (p. 145-148). Also available in print.
7
Papandreou, Panayiotis. "Design and prototype development of an optimum symmetrical number system direction finding array." Thesis, Monterey, California. Naval Postgraduate School, 1997. http://hdl.handle.net/10945/8239.
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Approved for public release; distribution in unlimited.One method of estimating the direction of an electromagnetic source is based on phase comparison. In this thesis the design and fabrication of a prototype antenna to demonstrate a new DF antenna architecture is described. Four antenna elements are grouped into three pairs with element spacing according to a set of symmetrical number system pairwise relatively prime moduli (m1 = 3, m2 = 4, m3=5). The phase difference between each pair of elements is a symmetrical folding waveform that is determined using a mixer. The output voltage from each pair is amplitude analyzed using a small comparator ladder. In each channel, the symmetrically folding waveform, folds in accordance with the channel modulus and thus, only requires a precision according to that modulus. A high resolution DF is achieved after the N different SNS moduli are used and the results of these low-precision channels are recombined to yield the direction of arrival. The frequency of operation of the prototype is 8.5 GHz. Results based on measured and simulated data are resented
8
Henricksen, Matthew. "Design, Implementation and Cryptanalysis of Modern Symmetric Ciphers." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16055/1/Matt_Henricksen_Thesis.pdf.
Full textAbstract:
The main objective of this thesis is to examine the trade-offs between security and
efficiency within symmetric ciphers. This includes the influence that block ciphers
have on the new generation of word-based stream ciphers. By incorporating
block-cipher like components into their designs, word-based stream ciphers have
experienced hundreds-fold improvement in speed over bit-based stream ciphers,
without any observable security degradation. The thesis also emphasizes the importance of keying issues in block and stream ciphers, showing that by reusing components of the principal cipher algorithm in the keying algorithm, security
can be enhanced without loss of key-agility or expanding footprint in software memory.
Firstly, modern block ciphers from four recent cipher competitions are surveyed and categorized according to criteria that includes the high-level structure of the block cipher, the method in which non-linearity is instilled into each round, and the strength of the key schedule. In assessing the last criterion, a classification
by Carter [45] is adopted and modified to improve its consistency.
The classification is used to demonstrate that the key schedule of the Advanced Encryption Standard (AES) [62] is surprisingly flimsy for a national standard. The claim is supported with statistical evidence that shows the key schedule suffers from bit leakage and lacks sufficient diffusion. The thesis contains a replacement key schedule that reuses components from the cipher algorithm, leveraging existing analysis to improve security, and reducing the cipher's implementation footprint while maintaining key agility. The key schedule is analyzed from the perspective of an efficiency-security tradeoff, showing that the new schedule rectifies an imbalance towards e±ciency present in the original.
The thesis contains a discussion of the evolution of stream ciphers, focusing on
the migration from bit-based to word-based stream ciphers, from which follows a commensurate improvement in design flexibility and software performance. It examines the influence that block ciphers, and in particular the AES, have had upon the development of word-based stream ciphers. The thesis includes a concise literature review of recent styles of cryptanalytic attack upon stream ciphers.
Also, claims are refuted that one prominent word-based stream cipher, RC4, suffers from a bias in the first byte of each keystream.
The thesis presents a divide and conquer attack against Alpha1, an irregularly clocked bit-based stream cipher with a 128-bit state. The dominating aspect of the divide and conquer attack is a correlation attack on the longest register. The internal state of the remaining registers is determined by utilizing biases in the clocking taps and launching a guess and determine attack. The overall complexity of the attack is 261 operations with text requirements of 35,000 bits and memory requirements of 2 29.8 bits.
MUGI is a 64-bit word-based cipher with a large Non-linear Feedback Shift Register (NLFSR) and an additional non-linear state. In standard benchmarks, MUGI appears to su®er from poor key agility because it is implemented on an
architecture for which it is not designed, and because its NLFSR is too large relative to the size of its master key. An unusual feature of its key initialization algorithm is described. A variant of MUGI, entitled MUGI-M, is proposed to
enhance key agility, ostensibly without any loss of security.
The thesis presents a new word-based stream cipher called Dragon. This cipher uses a large internal NLFSR in conjunction with a non-linear filter to produce 64 bits of keystream in one round. The non-linear filter looks very
much like the round function of a typical modern block cipher. Dragon has a native word size of 32 bits, and uses very simple operations, including addition, exclusive-or and s-boxes. Together these ensure high performance on modern day processors such as the Intel Pentium family.
Finally, a set of guidelines is provided for designing and implementing symmetric ciphers on modern processors, using the Intel Pentium 4 as a case study. Particular attention is given to understanding the architecture of the processor,
including features such as its register set and size, the throughput and latencies of its instruction set, and the memory layouts and speeds. General optimization rules are given, including how to choose fast primitives for use within the cipher. The thesis describes design decisions that were made for the Dragon cipher with respect to implementation on the Intel Pentium 4.
Block Ciphers, Word-based Stream Ciphers, Cipher Design, Cipher Implementa-
tion, -
9
Henricksen, Matthew. "Design, Implementation and Cryptanalysis of Modern Symmetric Ciphers." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16055/.
Full textAbstract:
The main objective of this thesis is to examine the trade-offs between security and efficiency within symmetric ciphers. This includes the influence that block ciphers have on the new generation of word-based stream ciphers. By incorporating block-cipher like components into their designs, word-based stream ciphers have experienced hundreds-fold improvement in speed over bit-based stream ciphers, without any observable security degradation. The thesis also emphasizes the importance of keying issues in block and stream ciphers, showing that by reusing components of the principal cipher algorithm in the keying algorithm, security can be enhanced without loss of key-agility or expanding footprint in software memory. Firstly, modern block ciphers from four recent cipher competitions are surveyed and categorized according to criteria that includes the high-level structure of the block cipher, the method in which non-linearity is instilled into each round, and the strength of the key schedule. In assessing the last criterion, a classification by Carter [45] is adopted and modified to improve its consistency. The classification is used to demonstrate that the key schedule of the Advanced Encryption Standard (AES) [62] is surprisingly flimsy for a national standard. The claim is supported with statistical evidence that shows the key schedule suffers from bit leakage and lacks sufficient diffusion. The thesis contains a replacement key schedule that reuses components from the cipher algorithm, leveraging existing analysis to improve security, and reducing the cipher's implementation footprint while maintaining key agility. The key schedule is analyzed from the perspective of an efficiency-security tradeoff, showing that the new schedule rectifies an imbalance towards e±ciency present in the original. The thesis contains a discussion of the evolution of stream ciphers, focusing on the migration from bit-based to word-based stream ciphers, from which follows a commensurate improvement in design flexibility and software performance. It examines the influence that block ciphers, and in particular the AES, have had upon the development of word-based stream ciphers. The thesis includes a concise literature review of recent styles of cryptanalytic attack upon stream ciphers. Also, claims are refuted that one prominent word-based stream cipher, RC4, suffers from a bias in the first byte of each keystream. The thesis presents a divide and conquer attack against Alpha1, an irregularly clocked bit-based stream cipher with a 128-bit state. The dominating aspect of the divide and conquer attack is a correlation attack on the longest register. The internal state of the remaining registers is determined by utilizing biases in the clocking taps and launching a guess and determine attack. The overall complexity of the attack is 261 operations with text requirements of 35,000 bits and memory requirements of 2 29.8 bits. MUGI is a 64-bit word-based cipher with a large Non-linear Feedback Shift Register (NLFSR) and an additional non-linear state. In standard benchmarks, MUGI appears to su®er from poor key agility because it is implemented on an architecture for which it is not designed, and because its NLFSR is too large relative to the size of its master key. An unusual feature of its key initialization algorithm is described. A variant of MUGI, entitled MUGI-M, is proposed to enhance key agility, ostensibly without any loss of security. The thesis presents a new word-based stream cipher called Dragon. This cipher uses a large internal NLFSR in conjunction with a non-linear filter to produce 64 bits of keystream in one round. The non-linear filter looks very much like the round function of a typical modern block cipher. Dragon has a native word size of 32 bits, and uses very simple operations, including addition, exclusive-or and s-boxes. Together these ensure high performance on modern day processors such as the Intel Pentium family. Finally, a set of guidelines is provided for designing and implementing symmetric ciphers on modern processors, using the Intel Pentium 4 as a case study. Particular attention is given to understanding the architecture of the processor, including features such as its register set and size, the throughput and latencies of its instruction set, and the memory layouts and speeds. General optimization rules are given, including how to choose fast primitives for use within the cipher. The thesis describes design decisions that were made for the Dragon cipher with respect to implementation on the Intel Pentium 4. Block Ciphers, Word-based Stream Ciphers, Cipher Design, Cipher Implementa- tion, -
10
May, Lauren Jeanette. "Design, analysis and implementation of symmetric block ciphers." Thesis, Queensland University of Technology, 2002.
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11
Broughton, Wayne Jeremy Wilson R. M. Wilson R. M. "Symmetric designs, difference sets, and autocorrelations of finite binary sequences /." Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-09052007-084407.
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12
Katsaounis, Parthena I. "Equivalence of symmetric factorial designs and characterization and ranking of two-level Split-lot designs." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1164176825.
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13
Oleinik, James Roy. "Symmetric multimodal interaction applied to database design and normalization." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61176.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 104).
A normal conversation between two people is typically multimodal, using both speech and gestures to effect communication. It is also symmetric because there is two-way multimodal interaction between the two parties. In contrast, when a human interacts with a computer, it is done through a strict and limited interface, usually a keyboard or mouse. Unlike the human-human conversation, this interaction is neither multimodal nor symmetric. The goal of this thesis is to empower computers to carry out symmetric, multimodal dialogues with humans, thereby providing a more natural human-computer interaction. To do so, we modified and extended Adler's Multimodal Interactive DialOgue System (MIDOS) to be a more flexible and domain-independent platform for supporting symmetric, multimodal interaction. We built an application that utilizes MIDOS in order to design and implement a normalized relational database, and then demonstrate the application's capabilities by using it to design the database for an after-action report wiki.
by James Roy Oleinik.
M.Eng.
14
McKague, Matthew. "Design and Analysis of RC4-like Stream Ciphers." Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/1141.
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RC4 is one of the most widely used ciphers in practical software applications. In this thesis we examine security and design aspects of RC4. First we describe the functioning of RC4 and present previously published analyses. We then present a new cipher, Chameleon which uses a similar internal organization to RC4 but uses different methods. The remainder of the thesis uses ideas from both Chameleon and RC4 to develop design strategies for new ciphers. In particular, we develop a new cipher, RC4B, with the goal of greater security with an algorithm comparable in simplicity to RC4. We also present design strategies for ciphers and two new ciphers for 32-bit processors. Finally we present versions of Chameleon and RC4B that are implemented using playing-cards.
15
Yoon, Youngshik. "The optical design and tolerancing of high performance optical systems exploiting aspheric and diffractive-refractive hybrid optical components." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/8324.
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16
Long, Sihui. "Peptidominicry : design, synthesis and conformational study of C₂-symmetric oligoureas." Lexington, Ky. : [University of Kentucky Libraries], 2006. http://lib.uky.edu/ETD/ukychem2006d00445/DISSERTATION.pdf.
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Thesis (Ph. D.)--University of Kentucky, 2006.Title from document title page (viewed on July 18, 2006). Document formatted into pages; contains xx, 156 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 150-155).
17
Long, Sihui. "PEPTIDOMIMICRY: DESIGN, SYNTHESIS AND CONFORMATIONAL STUDY OF C2-SYMMETRIC OLIGOUREAS." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/295.
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Mimicking the structure and even the function of an ??-peptide with artificial chainmolecules such as ??-peptides, ??-peptides and other unnatural oligomers has shown early success.The structural similarities between natural peptides and oligoureas lead to the belief that C2-symmetric oligoureas could be a good candidate for peptidomimicry. Molecular modelingindicates that both homochiral (all monomers have the same absolute configuration) andalternate chiral (absolute configuration of the residues alternate) C2-symmetric oligoureas canform helix- and sheet-like structures in solution conditionally.Several C2-symmetric 1,2-diamines were chosen as the building blocks for the synthesisof chiral oligoureas, and all diamines except for one were prepared in lab. Homochiral andheterochiral oligoureas based on the same diamine or mixed diamines were synthesized in thesolution phase, growing a chain by adding one unit at a time to one terminus or two units at atime to both termini with 4-nitrophenoxycarbonyl (PNP)- activated and t-butoxycarbonyl (Boc)- protected diamines as the intermediates. All the chiral oligoureas were purified by eitherrecrystallization and /or column chromatography and/ or HPLC and characterized by NMR andMALDI-MS. For some oligoureas, crystal structures were obtained. Fragment condensation wasattempted to improve the efficiency of the synthesis, but this approach led to cyclized oligoureasinstead of the desired concatenated residues.Conformational studies of chiral oligoureas were done in both the solid state and thesolution state. The crystal structures of some homochiral oligoureas and some alternate chiraloligoureas indicate that both helix-like structures and extended structures exist for these C2-symmetric oligoureas. NMR and Circular Dichroism (CD) were used to study the conformationof oligoureas in solution, but the conformational study by NMR was not conclusive. CD studyshowed that these oligoureas have multiple conformations in solution and that some of theconformations are sensitive to solvents and temperature. Also, short homochiral and alternatechiral oligoureas based on trans-1,2-diaminocyclohexane (DACH) exhibit signs of cooperativebehavior in solution as gauged by a series of experiments.
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陳眞良 and Chun-leung Chan. "New design methods for two-dimensional circularly symmetric digital filters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31231068.
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Chan, Chun-leung. "New design methods for two-dimensional circularly symmetric digital filters /." [Hong Kong : University of Hong Kong], 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12350813.
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Miao, Jingwei. "Ka-band 2D Luneburg Lens Design with Glide-symmetric Metasurface." Thesis, KTH, Elektroteknisk teori och konstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214611.
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A Luneburg lens is a beam former that has two focal points where one isat the surface and the other lies at innity. It is a cheap passive steerableantenna at high frequencies. In this thesis, a 2D at-prole Luneburglens with all-metal structure is designed for Ka band. Commercial softwareCST Microwave Studio Suite and Ansys Electronic Desktop (HFSS)are used for simulations.The lens is composed of two glide-symmetric metasurface layers with asmall gap in between. The high order symmetry, glide symmetry, couldprovide ultra wide band property for the lens. Each layer contains manyunit cells. Dierent unit cells are tested in this thesis to nd the best solutiontaking into account both electromagnetic properties and the easinessof manufacturing. A are is designed to achieve better matching betweenthe air gap of the lens and free space. A self-designed waveguide feedingis also used, including a transition from coaxial cable to TE10 mode ofrectangular waveguide at the focus of the lens.The prototype will be built in the future and measurements will be doneto compare with simulation results in this thesis.En Luneburg-lins ar en lobformare som har tva fokalpunkter, en vid linsensyta och en i oandligheten. Den ar en billig passiv styrbar antenn vidhoga frekvenser. I detta examensarbete konstrueras en plan Luneburg-linsi metall for Ka-bandet. De kommersiella programvarorna CST MicrowaveStudio Suite och Ansys Electronic Desktop (HFSS) anvands for elektromagnetiskasimuleringar.Linsen bestar av tva glidsymmetriska metaytor med ett litet mellanrum.En hogre ordnings symmetri, glidsymmetri, kan ge linsen ultrabred bandbredd.Metaytorna bestar av ett stort antal enhetsceller. Olika typer avenhetsceller testas for att hitta den basta losningen med hansyn till badeelektromagnetiska egenskaper och tillverkningsbarhet. En tvadimensionellhornstruktur konstrueras for att uppna god matchning mellan linsens luftgapoch frirymd. En vagledarmatning designas ocksa, inklusive overgangfran koaxialledning till TE10-moden i en rektangular vagledare, som anslutertill linsens fokalpunkt.En prototyp kommer att byggas i ett senare skede och matningar gorasfor att jamfora med simuleringsresultaten i detta examensarbete.
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Doughty, Jeffrey Jon. "Symmetric Near-Field Probe Design and Comparison to Asymmetric Probes." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/390.
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Tip Enhanced Near-field Optical Microscopy (TENOM) is a method for optically imaging at resolutions far below the diffraction limit. This technique requires optical nano-probes with very specialized geometries, in order to obtain large, localized enhancements of the electromagnetic field, which is the driver behind this imaging method. Traditional methods for the fabrication of these nano-probes involve electrochemical etching and subsequent FIB milling. However, this milling process is non-trivial, requiring multiple cuts on each probe. This requires multiple rotations of the probe within the FIB system, which may not be possible in all systems, meaning the sample must be removed from vacuum, rotated by hand and placed back under vacuum. This is time consuming and costly and presents a problem with reproducibility. The method presented here is to replace multiple cuts from a side profile with a small number of cuts from a top down profile. This method uses the inherent imaging characteristics of the FIB, by assigning beam dwell times to specific locations on the sample, through the use of bitmap images. These bitmaps are placed over the sample while imaging and provide a lookup table for the beam while milling. These images are grayscale with the color of each pixel representing the dwell time at that pixel. This technique, combined with grayscale gradients, can provide probes with a symmetric geometry, making the system polarization independent.
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Kim, Sang-Mok. "Sets of type-(1,n) in symmetric designs and aperiodic perfect maps." Thesis, Royal Holloway, University of London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248007.
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Hamdy, Ragi A. R. "Design, analysis and control of a bi-directional self-starting symmetrical two-phase switched reluctance machine." Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/1244.
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Yamane, Shinichi. "A New Design Methodology for Extending Symmetrical Input Ranges in Four-Quadrant Low Voltage CMOS Multipliers." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1421163501.
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Ögren, Jim. "PLL design for inverter grid connection : Simulations for ideal and non-ideal grid conditions." Thesis, Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-156145.
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In this report a phase locked loop (PLL) system for grid voltage phase tracking has been investigated. The grid voltage phase angle contains critical information for connecting a power plant, such as a wave energy converter, to the grid. A synchronous reference frame PLL system with PI-regulator gains calculated with the symmetrical optimum method has been designed and simulations in SIMULINK have been made. For ideal grid conditions the phase angle was tracked fast and accurate. For non-ideal conditions the phase angle was tracked but with less accuracy, due to slow dynamics of the system, but still within acceptable margins. In order to test this system further it has to be implemented in a control system and tested when connected to the grid.
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Yilmaz, Yildiz Elif. "Experimental Design With Short-tailed And Long-tailed Symmetric Error Distributions." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605191/index.pdf.
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One-way and two-way classification models in experimental design for both balanced and unbalanced cases are considered when the errors have Generalized Secant Hyperbolic distribution. Efficient and robust estimators for main and interaction effects are obtained by using the modified maximum likelihood estimation (MML) technique. The test statistics analogous to the normal-theory F statistics are defined to test main and interaction effects and a test statistic for testing linear contrasts is defined. It is shown that test statistics based on MML estimators are efficient and robust. The methodogy obtained is also generalized to situations where the error distributions from block to block are non-identical.
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Castro, Jose M. "Design and Application of Anti-Symmetric Grating for Optical Communication Systems." Diss., Tucson, Arizona : University of Arizona, 2006. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1662%5F1%5Fm.pdf&type=application/pdf.
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Gorski, Michael [Verfasser], and Stefan [Akademischer Betreuer] Lucks. "Cryptanalysis and Design of Symmetric Primitives / Michael Gorski ; Betreuer: Stefan Lucks." Weimar : Professur Mediensicherheit, 2010. http://d-nb.info/111534238X/34.
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Gorski, Michael Verfasser], and Stefan [Akademischer Betreuer] [Lucks. "Cryptanalysis and Design of Symmetric Primitives / Michael Gorski ; Betreuer: Stefan Lucks." Weimar : Professur Mediensicherheit, 2010. http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20101130-15267.
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Cuthbert, James. "High performance non-symmetric multi-h CPFSK modulator and demodulator design." Doctoral thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/21325.
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The continuity properties of the CPFSK signal at it's symbol-period boundaries reveals an inherent memory contained in the transmitted signal. This is utilized as an error correction property. Furthermore, it was shown that the Multi-h CPFSK construction can be accomplished through the combination of a block constructing the memoryless component of the signal and either a block of digital logic circuitry or a continuous phase encoder constructing the memory component. The implementation of the first method was seen to function through simulations performed by using the TESLA simulation package. An extensive search for good Multi-h CPFSK h-sets was performed. The criteria for determining the performance of these h-sets was the Probability of Error gains over Minimum Shift Keying. The method of search was novel to this work. Specifically, a genetic search algorithm known as the Population Based Incremental Learning algorithm was utilized. The algorithm was implemented through the C++ programming language Faster error correction convolutional decoding algorithms were reviewed. Certain decoders exhibit lighter hardware demands, and in specific applications, are less susceptible to erasure problems. The Fano algorithm was selected as the best alternative to the Viterbi algorithm and was modified for the CPFSK implementation. The functionality of the implementation was tested using a C++ simulation. Various structures used to implement the synchronization and demodulation of Multi-hCPFSK were investigated. The most comprehensive structure that could be found was a scheme developed by Premji and Taylor using maximum likelihood techniques. This scheme was selected as it can be easily modified for the use with the large state, high speed implementation of non-symmetric Multi-h CPFSK investigated in this thesis. The PBIL algorithm was found to be an efficient method for finding good h-sets with large numbers of phase states. Theoretical gains over MSK using this method were found to be significant. It was concluded that the Fano decoder is highly applicable to the demodulator structure proposed in this thesis and is a preferred alternative to the Viterbi decoder under specific circumstances.
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Bivigou, Koumba Achille Mayelle. "Design, Synthesis and Characterisation of Amphiphilic Symmetrical triblock copolymers by the RAFT process : their self-organisation in dilute and concentrated aqueous solutions." Phd thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/3954/.
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This work presents the synthesis and the self-assembly of symmetrical amphiphilic ABA and BAB triblock copolymers in dilute, semi-concentrated and highly concentrated aqueous solution. A series of new bifunctional bistrithiocarbonates as RAFT agents was used to synthesise these triblock copolymers, which are characterised by a long hydrophilic middle block and relatively small, but strongly hydrophobic end blocks. As hydrophilic A blocks, poly(N-isopropylacrylamide) (PNIPAM) and poly(methoxy diethylene glycol acrylate) (PMDEGA) were employed, while as hydrophobic B blocks, poly(4-tert-butyl styrene), polystyrene, poly(3,5-dibromo benzyl acrylate), poly(2-ethylhexyl acrylate), and poly(octadecyl acrylate) were explored as building blocks with different hydrophobicities and glass transition temperatures.
The five bifunctional trithiocarbonates synthesised belong to two classes: the first are RAFT agents, which position the active group of the growing polymer chain at the outer ends of the polymer (Z-C(=S)-S-R-S-C(=S)-Z, type I). The second class places the active groups in the middle of the growing polymer chain (R-S-C(=S)-Z-C(=S)-S-R, type II). These RAFT agents enable the straightforward synthesis of amphiphilic triblock copolymers in only two steps, allowing to vary the nature of the hydrophobic blocks as well as the length of the hydrophobic and hydrophilic blocks broadly with good molar mass control and narrow polydispersities. Specific side reactions were observed among some RAFT agents including the elimination of ethylenetrithiocarbonate in the early stage of the polymerisation of styrene mediated by certain agents of the type II, while the use of the RAFT agents of type I resulted in retardation of the chain extension of PNIPAM with styrene. These results underline the need of a careful choice of RAFT agents for a given task.
The various copolymers self-assemble in dilute and semi-concentrated aqueous solution into small flower-like micelles. No indication for the formation of micellar clusters was found, while only at high concentration, physical hydrogels are formed. The reversible thermoresponsive behaviour of the ABA and BAB type copolymer solutions in water with A made of PNIPAM was examined by turbidimetry and dynamic light scattering (DLS). The cloud point of the copolymers was nearly identical to the cloud point of the homopolymer and varied between 28-32 °C with concentrations from 0.01 to 50 wt%. This is attributed to the formation of micelles where the hydrophobic blocks are shielded from a direct contact with water, so that the hydrophobic interactions of the copolymers are nearly the same as for pure PNIPAM.
Dynamic light scattering measurements showed the presence of small micelles at ambient temperature. The aggregate size dramatically increased above the cloud point, indicating a change of aggregate morphology into clusters due to the thermosensitivity of the PNIPAM block.
The rheological behaviour of the amphiphilic BAB triblock copolymers demonstrated the formation of hydrogels at high concentrations, typically above 30-35 wt%. The minimum concentration to induce hydrogels decreased with the increasing glass transition temperatures and increasing length of the end blocks. The weak tendency to form hydrogels was attributed to a small share of bridged micelles only, due to the strong segregation regime occurring.
In order to learn about the role of the nature of the thermoresponsive block for the aggregation, a new BAB triblock copolymer consisting of short polystyrene end blocks and PMDEGA as stimuli-responsive middle block was prepared and investigated. Contrary to PNIPAM, dilute aqueous solutions of PMDEGA and of its block copolymers showed reversible phase transition temperatures characterised by a strong dependence on the polymer composition. Moreover, the PMDEGA block copolymer allowed the formation of physical hydrogels at lower concentration, i.e. from 20 wt%. This result suggests that PMDEGA has a higher degree of water-swellability than PNIPAM.Die Arbeit behandelt die Synthese und das Selbstorganisationsverhalten von neuen funktionellen symmetrischen "stimuli-responsiven" Triblockcopolymeren ABA und BAB in wässrigen verdünnten und höher konzentrierten Lösungen. Neue symmetrische, bifunktionelle Bistrithiocarbonate wurden als RAFT-Agentien benutzt, um Triblockcopolymere mit langen hydrophilen (A) Innen- und kurzen hydrophoben (B) Außenblöcken zu synthetisieren. Als hydrophile A Blöcke wurden Poly(N-isopropylacrylamid) PNIPAM und Poly(methoxy diethylene glykol acrylat) PMDEGA benutzt, während als hydrophobe Blöcke B Poly(4-tert-butyl styrol), Polystyrol, Poly(3,5-dibromo benzyl acrylat), Poly(2-ethylhexyl acrylat), und Poly(octadecyl acrylat) als Bausteine mit unterschiedlicher Glasübergangstemperatur untersucht wurden. Die Selbstorganisation von ABA und BAB Copolymeren in Wasser mit A Blöcken aus PNIPAM wurde anhand von Trübungsphotometrie, dynamischer Lichtstreuung (DLS) und Rheologie untersucht. Die amphiphilen Blockcopolymere sind direkt wasserlöslich. Bei Konzentrationen von 0.01 bis 50 wt% zeigen Trübungsmessungen bei den Blockcopolymeren wie bei den Homopolymeren eine Übergangstemperatur bei 28-32 °C. Zurückzuführen ist dies auf die Bildung von Mizellen, bei der die hydrophoben Blöcke von einem direkten Kontakt mit Wasser abgeschirmt werden. DLS zeigt kleine Mizellen bei niedrigen Temperaturen und Aggregate mit großem hydrodynamischem Durchmesser bei Temperaturen oberhalb der Übergangstemperatur. Die rheologische Untersuchung von BAB Polymeren zeigt die Bildung von Hydrogelen bei höheren Konzentrationen (über 30-35 wt%). Die minimal benötigte Konzentration, bei der die von Hydrogelen auftreten, nimmt mit wachsender Glasübergangstemperatur ab, und nimmt mit der Länge der hydrophoben Blöcke B zu. Im Unterschied zu PNIPAM zeigen wässrige Lösungen von PMDEGA und seinen Blockcopolymeren reversible Übergangstemperaturen abhängig von der chemischen Struktur. Außerdem bilden PMDEGA Blockcopolymere Hydrogele bei niedriger Konzentration (ab 20 wt%). Dieses Ergebnis deutet darauf hin, dass PMDEGA stärker Wasser bindet als PNIPAM.
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Shin, Dong Ku. "Minimum-weight design of symmetrically laminated composite plates for postbuckling performance under in-plane compression loads." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07282008-135134/.
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Vargas, Catalan Ernesto. "Design and Manufacturing of a Rotationally Symmetric Cold Gas Nozzle in Silicon." Thesis, Uppsala universitet, Ångström Space Technology Centre (ÅSTC), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182199.
Full textAbstract:
In this master thesis, the goal was to devise design patterns and a fabrication processfor manufacturing a 3-D rotationally symmetric converging-diverging cold gasmicronozzle in silicon.The report explains the theory of etching and the methods involved. The work beginswith calculations and simulations of the etching processes. The chosen etch techniqueutilizes so called microloading and reactive ion etching lag effects, which essentially arephenomena where the etch rate can be adjusted by breaking up mask features intosubpatterns, and the etch depth for a given recipe and time can be made to differlocally. The subpatterns consisted of very small rectangles and triangles withalternating concentration. Five different recipes for the reactive ion etching weretried, where the coil power, platen power, pressure, temperature and time wasvaried.Etch rates could be made to differ locally depending on the concentration ofsubpatterns within the mask feature. The etch rates were also affected by the recipeparameters such as coil power, platen power, and pressure. High coil and platenpower increased the etch rate, while high pressure reduced the etch rate. The platenpower also affected the surface roughness.A solution for reducing misalignment problems in the future for the fusion bondingprocess resulted in the proposed moiré patterns that were made to showmisalignments down to 0.2 μm.Through scanning electron microscopy, the Nozzle 5_4_2 was concluded to have themost rotationally symmetric cross section at both the throat and the outlet. It hasthroat diameter of 31.1 μm with a depth of 34.2 μm and an outlet diameter of146.4 μm with a depth of 113.2 μm
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Zhao, Mingrui, and Manish Keswani. "Fabrication of Radially Symmetric Graded Porous Silicon using a Novel Cell Design." NATURE PUBLISHING GROUP, 2016. http://hdl.handle.net/10150/614761.
Full textAbstract:
A contactless method using a novel design of the experimental cell for formation of porous silicon with morphological gradient is reported. Fabricated porous silicon layers show a large distribution in porosity, pore size and depth along the radius of the samples. Symmetrical arrangements of morphology gradient were successfully formulated radially on porous films and the formation was attributed to decreasing current density radially inward on the silicon surface exposed to Triton (R) X-100 containing HF based etchant solution. Increasing the surfactant concentration increases the pore depth gradient but has a reverse effect on the pore size distribution. Interestingly, when dimethyl sulfoxide was used instead of Triton (R) X-100 in the etchant solution, no such morphological gradients were observed and a homogeneous porous film was formed.
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Cutler, Steven. "Implementation of a Variable Duty Factor Controller on a Six-Legged Axi-Symmetric Walking Robot." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2887.
Full textAbstract:
Hexplorer is a six-legged walking robot developed at the University of Waterloo. The robot is controlled by a network of seven digital signal processors, six of which control three motors each, for a total of 18 motors. Brand new custom electronics were designed to house the digital signal processors and associated circuitry. A variable duty factor wave gait, developed by Yoneda et al. was simulated and implemented on the robot. Simulation required an in-depth kinematic analysis that was complicated by the mechanical design of parallel mechanism comprising the legs. These complications were handled in both simulation and implementation. However, due to mechanical issues Hexplorer walked for only one or two steps at a time.
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Naman, Garry Zamani. "Design and development of symmetric reflective compound parabolic concentrator (SRCPC) for power generation." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3286.
Full textAbstract:
This thesis presents a detailed design, simulation, optical performance, construction and experimental validation carried out on a novel non-imaging static symmetric reflective compound parabolic concentrator (SRCPC). By considering the seasonal variation of the sun’s position, a concentrating Photovoltaic (CPV) system with precise acceptance angle and low concentrating ratio will be an ideal alternative to conventional flat plate photovoltaic (PV) modules in harvesting the power from the sun. The SRCPC is a suitable choice well designed to achieve optimum precise acceptance angles and concentration ratio for this purpose. The optical performance theory study shows that a truncated symmetric reflective CPC with acceptance half-angles of 0° and 10° (termed as SRCPC-10) is the optimum design when compared with the symmetric reflective CPC designs with acceptance half-angles of 0° and 15° and 0° and 20° in Penryn and higher latitudes. An increase in the range of acceptance angles decreases the concentration ratio but an increase in the range of acceptance angles is achieved by truncating the concentrator profile which will reduce its cost as well. Ray tracing simulations indicates that the SRCPC-10 exhibited the maximum optical efficiency and steady slope compared with others. The simulated maximum optical efficiency of the SRCPC was found to be 94%. In addition, the SRCPC-10 was found to have a more uniform intensity distribution at the receiver and a total daily-monthly energy collection compared to the other designs. Thermal modelling of the CPV system with the SRCPC-10 concentrator shows that the solar cell operating temperature can reach up to 70°C for irradiance of 1000W/m2 at an ambient temperature of 25° at a wind velocity of 2.5m/s. The integration of the thermal management system is able to control and maintain the temperature to 29°C. The modelled thermal and electrical efficiencies were 47% and 15% respectively with a heat transfer coefficient of 54.29W/m2K thereby bringing the system efficiency to 62%. The maximum power of the SRCPC-10 when characterised in an indoor controlled environment using solar simulator was 5.96W at 1000W/m2 at a cooling flow rate of 0.0079L/s with average conversion efficiency of 8.97%. The maximum power at 1200W/m2 and 0.031L/s was 7.14W with conversion efficiency of 10.57%. The maximum increase in efficiency from non-cooling to cooling is 2.54%. The efficiency increased because of cooling is relatively 40%. The outdoor characterisation (validation) of the SRCPC-10 shows that the maximum power was 7.4W at 1206W/m2 on a sunny day. The maximum electrical conversion efficiency of the SRCPC-10 in outdoor conditions was found to be 10.96%. These results revealed that this designed SRCPC-10 is capable of collecting both direct and diffuse radiation to generate power. Therefore, the SRCPC-10 could be used to provide a solution to the increasing demand on electricity to the energy mix, leaving a clean environment for future developments.
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Shu, Xiaohua. "BLOCK DESIGNS UNDER AUTOCORRELATED ERRORS." Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/154927.
Full textAbstract:
StatisticsPh.D.
This research work is focused on the balanced and partially balanced incomplete block designs when observations within blocks are correlated. The topic for this dissertation was motivated by a problem in pharmaceutical research, when several treatments are allocated to individuals, and repeated measurements are taken on each individual. In that case, there is correlation among the observations taken on the same individual. Typically, it is reasonable to assume that the observations within individual close to each other are highly correlated than observations that are far away from each other. It is also reasonable to assume that the correlation between any two observations within each individual is same. We have characterized balanced and partially balanced incomplete block designs when observations within blocks are autocorrelated. In Chapter 3, we have provided an explicit expression for the average variance of estimated elementary treatment contrasts for designs obtained by Type I and II series of orthogonal arrays, under autocorrelated errors, and compared them with the corresponding balanced incomplete block designs with uncorrelated errors. The relative efficiency of balanced incomplete block design compared to the corresponding balanced incomplete block design obtained by Types I and II series of orthogonal array under autocorrelated errors does not depend on the number of treatments (v) and is an increasing function of the block size (k). When orthogonal arrays of Type I or Type II do not exist for a given number of treatments, we provided alternative partially balanced designs with autocorrelated errors. In Chapter 4, we rearranged the treatments in each block of symmetric balanced incomplete block designs and used them with autocorrelated error structure of the plots in a block. The C-matrix of estimated treatment effects under autocorrelation was given and the relative efficiency of symmetric balanced incomplete block designs with independent errors compared to the autocorrelated designs is given. In Chapter 5, we discussed the compound symmetry correlation structure within blocks. An explicit expression of the average variance of designs obtained by Type I and II series of orthogonal arrays and symmetric balanced incomplete block designs under compound symmetric errors has been provided and compared them with the corresponding balanced incomplete block designs with uncorrelated errors. Finally, the relative efficiencies of these designs with autocorrelated errors vs. compound symmetric error structure are given
Temple University--Theses
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Lorenzetto, Tommaso <1996>. "C3-symmetric triphenylenes based designer surfactants: synthesis, aggregation and catalytic properties studies." Master's Degree Thesis, Università Ca' Foscari Venezia, 2020. http://hdl.handle.net/10579/18368.
Full textAbstract:
In this MD Thesis the synthesis of C3-symmetric triphenylene derivatives were performed and largely improved, to achieve water-soluble aromatic compounds bearing hydrophilic sulfonated moieties or PEG chains. Such molecules were obtained from hexahydroxytriphenylenes, using less hazardous reagents and conditions compared to previous ones. The products showed amphiphilic behaviour and were employed directly as catalysts in water or combined with transition metal catalysts to perform cross-coupling reactions. While the anionic surfactant showed lower catalytic activities compared to commercial surfactants, the neutral PEG derivative turned out to improve cross-coupling reactions, observing in many cases enhanced yields and easy product isolation, representing a promising new designer surfactant for future developments.
1H NMR and DOSY experiments at different concentrations were employed to investigate the aggregation properties of these amphiphiles in water, and SANS experiments in collaboration with Dr. Mondelli from ILL Grenoble further enabled to ascertain the size and structure of the micelles.
The lockdown period was conveniently employed to collect recent literature regarding innovative designer surfactants and their application in organic synthesis processes, leading to the preparation of a mini-review manuscript under the guidance of Proff. Fabris and Scarso on the field of “designer surfactants” that has recently published in Catalysis Science and Technology.
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Jovanovic, Philipp [Verfasser], Martin [Akademischer Betreuer] Kreuzer, and Ilia [Akademischer Betreuer] Polian. "Analysis and Design of Symmetric Cryptographic Algorithms / Philipp Jovanovic. Betreuer: Martin Kreuzer ; Ilia Polian." Passau : Universität Passau, 2015. http://d-nb.info/1079066969/34.
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Ströbel, Michael. "A design and implementation framework for symmetric multi-attribute negotiation intermediation in electronic markets /." Zürich : ADAG Copy, 2002. http://www.gbv.de/dms/zbw/356857174.pdf.
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Arnberg, Philip, and Petersson Oscar Barreira. "Design of a Maxwell Fish-Eye Lens in PCB Technology With a Glide-Symmetric Metasurface." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254263.
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The aim of this project is to design a cost-effective planar Maxwell fish-eye lens in PCB technology operating at the center frequency 5 GHz with a bandwidth of 20 %. An approach to design a cost-effective lens is to use a metasurface, which is commonly realized as a periodic structure of unit cells. In this project, a study was made by comparing different unit cells and considering the effect of applying glide symmetry to the unit cells. Comparing different unit cells withand without glide symmetry demonstrates that glide symmetry is necessary to achieve a 20 % bandwidth. Introducing glide symmetry showed a reduction in dispersive behavior, an increaseof isotropy and effective refractive index. Simulations of the full lens show a functioning lens with a power transfer of 67 % at 5.46 GHz. In conclusion, glide symmetry will improve the performance of the lens and is necessary to fulfill the requirement of a 20 % bandwidth.
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Al-Bahily, Khalid A. "Design and synthesis of new C1 and C2-symmetric ansa-metallocene catalysts for isotactic-polypropylene formation." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3061.
Full textAbstract:
Several ansa C1-symmetric cyclopentadienyl-fluorenyl metallocenes based on
zirconium have been prepared with different substituents at position 3 on the
cyclopentadienyl ring. Isotactic polypropylene production from these systems depends
highly on the size of these substituents. Therefore, large groups such as 1-methyl-4-tbutylcyclohexyl
(metallocene 6), 1-methyl-cyclohexyl (metallocene 7), 1,3,3,5-
tetramethylcyclohexyl (metallocene 8), and 2,3,4-trimethyl-3-pentyl (metallocene 9)
have been investigated. In combination with methylaluminoxane (MAO), they showed
good activity and produced high molecular weight of isotactic polypropylene. In terms
of the tacticity of the polymers, metallocene 6 made the best isotactic polypropylene
with ~88% mmmm pentad content. Also, it has been found that if the size of this
substituent is large as in 2,3,4-trimethyl-3-pentyl (metallocene 9), then it will block the
polymerization active site which will deactivate the metallocene.
New synthetic pathways for the synthesis of cyclopentadienyl-fluorenyl
metallocenes based on titanium have been achieved. Anchoring these types of ligands
onto titanium by following the conventional method of using TiCl4 in the metallation
step has failed for the production of Me2C(3-(diphenylmethyl)-C5H3)(C13H8)TiCl2
(metallocene 12), Ph2C(C5H4)(C13H8)TiCl2 (metallocene 14), and
Ph2C(C5H4)(C13H8)TiMe2 (metallocene 15); this is possibly due to the high reactivity of
TiCl4. Therefore, TiCl4·2THF has been prepared and used in that step to produce these
new titanocenes with good yields.
A new ansa-C2-symmetric substituted bis-indenyl metallocene for isotactic
polypropylene production has been successfully prepared. It is known that ansa-C2-
symmetric metallocenes are good catalysts for isotactic polypropylene production, but in
general, their synthesis suffers from the production of the meso Cs-stereoisomer of these
catalysts, which generally produces only atactic polypropylene. Therefore, the meso
stereoisomers must be removed and this is considered a loss of the material that
increases the cost of the catalysts. Addition of bulky substituents on the indenyl groups
as in Me2Si(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indenyl)2ZrCl2 (metallocene 5)
has prevented the meso stereoisomer production. 5/MAO produces isotactic
polypropylene with up to ~80% mmmm pentad content.
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Nguyen, Truong Quang Vaidyanathan P. P. "Design and implementation of linear-phase and/or pairwise-symmetric perfect-reconstruction fir multirate filter banks /." Diss., Pasadena, Calif. : California Institute of Technology, 1989. http://resolver.caltech.edu/CaltechETD:etd-11102005-091115.
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Adekunle, Andrew A. "Design and analysis of light-weight symmetric cryptographic frameworks and constructs for secure packet mode wireless communication." Thesis, University of Greenwich, 2012. http://gala.gre.ac.uk/9806/.
Full textAbstract:
This thesis reports research undertaken to address the deficiencies that existing standardised cryptographic constructs exhibit when securing packet mode wireless communication in WSN. The aim of the research is to devise innovative cryptographic frameworks, which will facilitate design and implementation of light-weight symmetric cryptographic modular constructs. Four cryptographic frameworks have been devised and block cipher based light-weight constructs using the frameworks have been designed and benchmarked against contemporary standard constructs. The constructs introduced in this dissertation, proved to be better suited to providing secure packet mode data communication, in applications utilising wireless networks consisting of characteristically constrained nodes. The four proposed frameworks are: - The Zone-based framework for data packet integrity and authentication security services is proposed and described. The Quicker Block Chaining (QBC) family of message authentication constructs designed using the framework, are shown, via software simulation, to operate with better efficiency (i.e. uses fewer instruction cycles) than similar contemporary standard constructs and with a comparable level of security. - The Hybrid Encryption Mode (HEM) framework for data packet confidentiality security service is proposed and described. The HEM framework facilitated the design of constructs that provide probabilistic, randomising and tweakable encryption. - The Joint Cypher Mode (JCM) framework for authenticated encryption with associated-data (AEAD) security service is proposed and described. The range of constructs designed using the JCM framework, are shown, via software simulation and practical deployment, to Design and Analysis of Light-weight Symmetric Cryptographic Frameworks and Constructs for Secure Packet Mode Wireless Communication operate with better efficiency (i.e. uses fewer instruction cycles) than contemporary standard constructs. - The Joint Authenticated Combined Mode (JACM) framework for authenticate authenticated-encryption with associated-data (AAEAD) security service is proposed and described. The new AAEAD secure packet paradigm addresses a limitation and cryptographic protection failure of the standardised AEAD secure packet paradigm, in communication scenarios when untrustworthy intermediary forwarding nodes are utilised to authenticate and relay packets. The outcomes of the research undertaken are relevant to practitioners and cryptographic engineers that require symmetric cryptographic light-weight constructs for providing secure packet mode communications. It is shown that the resulting light-weight symmetric cryptographic constructs are better suited to providing secure packet mode wireless networked communication.
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He, Bing. "Architecture Design and Performance Optimization of Wireless Mesh Networks." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1275923221.
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Liang, Yun-Fu, and 梁耘輔. "Design of a Food Recognition System by Symmetrical Windows." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/95464002150838699991.
Full textAbstract:
碩士國立雲林科技大學
資訊工程系碩士班
101
Recently, a food recognition system using a SPIN descriptor has been proposed. The SPIN descriptor is extracted by circular windows with color histograms, and it has demonstrated good performance in recognizing rotated food images. However, one descriptor is not enough for distinguishing between certain foods, such as foods of a similar color. Therefore, we propose a food recognition system with various descriptors:bag-of-SURF, Haralick’s, and HSV. These descriptors are extracted from a food region with a circular window.Then, these descriptors are classified using an SVM(Support Vector Machine). In the experiments, we estimated descriptors with a circular window and a square window in our system and found that thedescriptor with the circular window had the best performancein our proposed system. It achieved a 98.66% recognition rate with the HSV-Haralick’s descriptor. In addition, when the descriptor was reduced to half-dimension, it achieved a 98% recognition rate and a 48.24% increase in speed in the stage of feature extraction.
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Yang, Jian-jhe, and 楊建哲. "A novel design of polishing tool for axially symmetrical surface." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/36126727723517076927.
Full textAbstract:
碩士國立中山大學
機械與機電工程學系研究所
94
This thesis is to develop a novel polishing tool system fitted for convex and concave symmetrical surface of combined surface. There are two design goals in this system. First, this system can be used to polish a concave or convex cone surface with various dimensions and angle cones by adjusting its geometric feature of structure. Second, this polishing tool is expected to have high life expectancy in real applications. Because of the advantages, an efficiency and controllable polishing system would be developed.An inference process, based on a top-down planning strategy, was used to obtain the concept design of polishing tool. There are two major parts in the structure of polishing tool system. The first one is its elastic structure. Both its geometric configuration and loading applied at work are adjustable. The second one is the polishing tool of cylindrical shape. With this specific geometric feature, the effect of tool wear on polishing rate is minimized. The finite element method was adopted to analyze the deformation characteristics of the elastic structure. Accordingly, an optimal design about the shape and dimension of elastic structure was determined. The experimental study showed that the developed polishing system had the property of high repeatability in machining rate. It was also demonstrated that the machining rate of system was insensitive to the tool wear during the polishing process. This advantage may allow this system to gain significant benefit in reducing the need of tool replacement. Finally, it was shown that the experimental trends of machining rate due to the change of applied load or polishing speed followed that of cylindrical polishing system. Both of them can be properly predicted based on the lubricating theories.
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Sie, Chang-Ying, and 謝昌穎. "The Symmetrical Gait Design for Quadruped Robot with Waist Joint." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/s3p538.
Full textAbstract:
碩士國立虎尾科技大學
自動化工程研究所
102
This paper discusses the design of a gait pattern for quadruped robot which has waist joint. First, the investigation of kinematics characteristics of suitable gait for quadruped robot which possesses waist joint is performed. In here, the trot gait is used as the basic gait pattern for the development of such gait with symmetrical motion pattern. In this paper, the appropriate coordination systems for generating the kinematic of the gait control are also introduced. Restrictions are added to the kinematics model to simplify the movement of the joints due to increased waist motion in order for solving the inverse kinematics problem. Also, two full leg standing states are placed into the trot gait pattern to improve the stability and to avoid the work space overlapping which generally cause the interference between legs. Further analysis of compensation of the workspace offsets of legs due to the waist joint movement is studied. The advantages of increasing the walking stride and the stability with this gait design are highlighted. The proposed gait is first simulated by using the LabVIEWR program to visualize the stabilities of motion control under various speed setting. The field test results by gathering the data of the robot using the developed gait and the general Wave gait are compared and show the advantages of the proposed gait in smoothness, stability, and effective of the speed control.
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Chou, Chia-Hung, and 周家宏. "Analysis and Design A Symmetric Coupler." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/39181033175173394646.
Full textAbstract:
碩士國立雲林科技大學
電機工程系
103
This thesis proposes novel designs of branch-line and rat-race couplers. As compared with conventional couplers, whose structures are symmetric with respect to both the horizontal and vertical plane of symmetry (POS), the couplers proposed here are symmetric with respect to only the horizontal POS. This leads to three, instead of two, possibly different characteristic impedances (Z1, Z2, and Z3) and electrical lengths (θ1, θ2, and θ3) required for the new designs. The additional impedance Z3 can be used to adjust the circuit bandwidth. In the analysis, even and odd circuit analyses were first applied to find the corresponding ABCD matrices, which were subsequently transformed into scattering matrices. From such analyses, scattering parameters of the entire coupler and the required characteristic impedances can be determined. For validation, we have designed and fabricated six single-band couplers, all with the same center frequency of 2.45 GHz. These circuits include branch-line and rat-race couplers with the power ratios of 1:1, 2:1, and 3:1, summing up to six of them. For applications where two communication bands are required in the same circuit, dual-band brand-line and rat-races couplers were also designed and fabricated in this study. For the former, the center frequencies are 0.9/2.45 GHz, and for the latter, 0.915/2.45 GHz. To achieve dual-band operations, each transmission-line sections in the previous designs were replaced with three sections, the middle of which was further substituted with an all-pass coupled-line section. Formulas available in the literature were applied to find the appropriate lengths and characteristic impedances for the three sections in order to obtain the prescribed ratio of the dual operating bands. The circuit simulator Microwave office and full-wave simulator IE3D were both employed to carry the simulations. The circuits were designed and fabricated using either R04003 or FR4 substrates, and measured using an Agilent E5071C vector analyzer. Results showed that the simulation agree reasonably well with the measurement. Keywords：All-pass coupled line、Ring coupler、Branch line coupler
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Hung, Yu-Chieh, and 洪毓傑. "Design and Implementation of symmetrical Half-bridge converter with Zero Voltage Switching." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/59760879057834465507.
Full textAbstract:
碩士國立臺北科技大學
電機工程系碩士班
91
This objective of this thesis is to design and implement a symmetrical half-bridge converter with zero-voltage switching. The design specifications include: 48 V for input and 3.3 V for output, and 100 W. It is well known that hard switching converter is with some issues, including high switching losses and significant Electro-Magnetic Interference (EMI). These issues can be coped with using soft switching technique. Moreover, the voltage un-balance issue for the input capacitors of half-bridge converter is also investigated in this thesis. A novel technique to deal with this issue is presented in the thesis. The designed symmetrical half-bridge converter with zero-voltage switching, is implemented and the experimental results are used to verify the design. Experimental results show that the design converter achieve zero switching and balanced input voltage for input capacitors in the whole operation range.