Over the last decade, the demand for privacy and data confidentiality in communication and storage processes have increased exponentially. Cryptography can be the solution for this demand. However, the critical issue occurs when there is a need for computing publicly on sensitive information or delegating computation to untrusted machines. This must be done in such a way that preserves the information privacy and accessibility. For this reason, we need an encryption algorithm that allows computation on information without revealing details about them. In 1978 Rivest, Adleman and Dertouzos raised a crucial question: can we use a special privacy homomorphism to encrypt the data and do an unlimited computations on it while it remains encrypted without the necessity of decrypting it? Researchers made extensive efforts to achieve such encryption algorithm. In this paper, we introduce the implementation of the CRT-based somewhat homomorphic encryption over the integers scheme. The main goal is to provide a proof of concept of this new and promising encryption algorithm. / Graduate

Hyperthermophiles grow optimally at 80 ??C and above, and many of them have the ability to utilize various carbohydrates as carbon source and produce ethanol as an end product. Alcohol dehydrogenase (ADH) is a key enzyme responsible for alcohol production, catalyzing interconversions between alcohols and corresponding ketones or aldehydes. ADHs from hyperthermophiles are of great interests due to their thermostability, high activity and enantioselectivity. The gene encoding ADH from hyperthermophilic archaeon Thermococcus guaymasensis was cloned, sequenced and over-expressed. DNA fragments of the genes encoding the ADHs were amplified directly from the corresponding genomic DNA by combining the use of conventional and inverse PCRs. The entire gene was detected to be 1092 bp and the deduced amino acid sequence had a total of 364 amino acids with a calculated molecular mass of 39463 Dalton. The enzyme belonged to the family of zinc-containing ADHs with catalytic zinc only. It was verified that the enzyme had binding motifs of catalytic zinc only (GHEX2GX5GX2V, residues 62-76) and coenzyme NADP (GXGX2G, residues 183-188). The tertiary structural modeling showed two typical domains, one catalytic domain close to amino-terminal (N-terminal) end and one coenzyme-binding domain close to carboxy-terminal (C-terminal) end. Since its codon usage pattern seemed to be different from that of Escherichia coli, the enzyme was over-expressed in the E. coli codon plus strain using pET-30a vector. The recombinant enzyme was detected to be soluble and active (1073 U/mg), which was virtually the same to the native enzyme (1049 U/mg). The recombinant ADH possessed almost identical properties with the native enzyme. The optimal pHs for ethanol oxidation and acetaldehyde reduction were 10.5 and 7.5 respectively, while the activity for alcohol oxidation was much higher than that of aldehyde reduction. The enzyme activity was inhibited in the presence of 100 ??M Zn2+ in the assay mixture and it has a half-life of 6 hours after exposure to air. Thermotoga hypogea is an extremely thermophilic anaerobic bacterium capable of growing at 90 ??C. The gene encoding an alcohol dehydrogenase from T. hypogea was cloned, sequenced and over-expressed. The gene sequence (1164 bp) was obtained successfully by sequencing all the DNA fragments amplified from PCR. The deduced amino acid sequence was found to have high degrees of identity (~72%) to iron-containing ADHs from Thermotoga species and harbored typical iron and NADP-binding motifs, Asp195His199His268His282 and Gly39Gly40Gly41Ser42, respectively. The structural modeling showed that N-terminal domain of ThADH contained ??/??-dinucleotide-binding motif and its C-terminal domain was ??-helix-rich region including iron-binding motif. The gene encoding T. hypogea ADH was functionally expressed in E. coli using the vector pET-30a. The recombinant protein was expressed optimally in E. coli grown in the presence of 1 mM ferrous and induced by 0.4-0.6 mM IPTG. The recombinant enzyme was found to be soluble, active and thermostable, and had a subunit size of 43 kDa revealed by SDS-PAGE analyses. The native ADH from T. hypogea was purified to homogeneity for comparative analysis using a three-step liquid chromatography while the recombinant ADH over-expressed in E. coli was isolated by a simpler procedure including one-hour heat treatment. The activity of the purified recombinant enzyme was 69 U/mg and presented almost identical properties with the native enzyme. The optimal pHs for ethanol oxidation and acetaldehyde reduction were 11.0 and 8.0 respectively, while activity for alcohol oxidation were higher than that of aldehyde reduction. The enzyme was oxygen sensitive and it had a half-life (t1/2) of 20 minutes after exposed to air. The enzyme remained 50% activity after incubation at 70 ??C for 2 hours. Successful high-level expression of T. hypogea ADH in E. coli will significantly facilitate further study on the catalytic mechanism of iron-containing ADHs. In summary, both zinc- and iron-containing ADHs from two hyperthermophiles were successfully cloned, sequenced and overexpressed in mesophilic host E. coli, and such a high-level expression of ADH genes provides possibilities for three dimensional structural analysis by X-ray crystallography and enzyme modification by mutagenesis, which will help further explore mechanisms of catalysis and protein thermostability of iron and zinc-containing ADHs and their potential applications in biotechnology.

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The aim of this thesis is to explain the typology of civilian control in Taiwan during Chen Shui-bian era and to explain the correlation between that particular type of civilian control and the perception of China threat among civilian groups. The establishment of civilian control in most cases is seen as either a result or a consequence of democratization process or the transformation from authoritarian to democratic society. The assessment on the case of Taiwan is no different. In this logic of thinking, the establishment of a democratic or objective civilian control is considered as the main goal. An objective civilian control, according to Huntington, has several prerequisites such as military disengagement from politics, full military submission to civilian authority, and, most importantly, the establishment of professional military. Critics to Huntington ideals usually revolve around the necessity to have a clear disengagement of the military from politics. Drawing from Huntington and his critics, I propose three indicators to categorize civilian control into objective and subjective. Those are the military autonomy, which is a direct result of the existence of a clear set of boundaries between military and civilian areas or roles, the existence or inexistence of intra-civilian rivalry, and the existence or inexistence of interpenetration. Using those indicators, my assessment on Taiwan during Chen Shui-bian era finds out that the military autonomy did exist with the adoption of the twin defense laws, the existence of an acute intra-civilian rivalry, and the existence of civilian penetration into military area. This civilian penetration itself was a result of an overt-concentration of roles into civilian hands, which leaving the military in a very limited role and powerless position, and the intra-civilian rivalry which drove both Chen’s government and pan-blue opposition to use military issues as bargaining chip to strengthen their political position. In conclusion, instead of having an objective civilian control, Taiwan under Chen Shui-bian was suffering from a subjective civilian control. To answer the question of why such an opposite result appeared, from what is supposed to be the result of the democratization process, I argue that the divergent of perception on China threat among civilian is among the factors that explain such a contradiction. Most assessment on the issue of civilian control in Taiwan is focusing on the identity politics as the explaining factor. In this thesis, I argue that the identity politics is necessary but not sufficient to explain the contradictory result. The divergent perception on China threat among civilian serves as the foundation to explain the political behavior of political parties in Taiwan. Due to this differing perception, political parties could not find a congruent understanding of external threat that makes any defense related issue became a political issue. / The aim of this thesis is to explain the typology of civilian control in Taiwan during Chen Shui-bian era and to explain the correlation between that particular type of civilian control and the perception of China threat among civilian groups. The establishment of civilian control in most cases is seen as either a result or a consequence of democratization process or the transformation from authoritarian to democratic society. The assessment on the case of Taiwan is no different. In this logic of thinking, the establishment of a democratic or objective civilian control is considered as the main goal. An objective civilian control, according to Huntington, has several prerequisites such as military disengagement from politics, full military submission to civilian authority, and, most importantly, the establishment of professional military. Critics to Huntington ideals usually revolve around the necessity to have a clear disengagement of the military from politics. Drawing from Huntington and his critics, I propose three indicators to categorize civilian control into objective and subjective. Those are the military autonomy, which is a direct result of the existence of a clear set of boundaries between military and civilian areas or roles, the existence or inexistence of intra-civilian rivalry, and the existence or inexistence of interpenetration. Using those indicators, my assessment on Taiwan during Chen Shui-bian era finds out that the military autonomy did exist with the adoption of the twin defense laws, the existence of an acute intra-civilian rivalry, and the existence of civilian penetration into military area. This civilian penetration itself was a result of an overt-concentration of roles into civilian hands, which leaving the military in a very limited role and powerless position, and the intra-civilian rivalry which drove both Chen’s government and pan-blue opposition to use military issues as bargaining chip to strengthen their political position. In conclusion, instead of having an objective civilian control, Taiwan under Chen Shui-bian was suffering from a subjective civilian control. To answer the question of why such an opposite result appeared, from what is supposed to be the result of the democratization process, I argue that the divergent of perception on China threat among civilian is among the factors that explain such a contradiction. Most assessment on the issue of civilian control in Taiwan is focusing on the identity politics as the explaining factor. In this thesis, I argue that the identity politics is necessary but not sufficient to explain the contradictory result. The divergent perception on China threat among civilian serves as the foundation to explain the political behavior of political parties in Taiwan. Due to this differing perception, political parties could not find a congruent understanding of external threat that makes any defense related issue became a political issue.

A research area that has recently gained great interest is the development of network architectures relating to the tracking of wireless VoIP devices. This is particularly so for architectures based on the popular Session Initiation Protocol (SIP). Previous work, however, in this area does not consider the impact of combined VoIP and tracking on the capacity and call set-up time of the architectures. Previous work also assumes that location information is always available from sources such as GPS, a scenario that rarely is found in practice. The inclusion of multiple positioning systems in tracking architectures has not been hitherto explored. It is the purpose of this thesis to design and test SIP-based architectures that address these key issues. Our first main contribution is the development of a tracking-only SIP based architecture. This architecture is designed for intermittent GPS availability, with wireless network tracking as the back-up positioning technology. Such a combined tracking system is more conducive with deployment in real-world environments. Our second main contribution is the development of SIP based tracking architectures that are specifically aimed at mobile wireless VoIP systems. A key aspect we investigate is the quantification of the capacity constraints imposed on VoIP-tracking architectures. We identify such capacity limits in terms of SIP call setup time and VoIP QoS metrics, and determine these limits through experimental measurement and theoretical analyses. Our third main contribution is the development of a novel SIP based location tracking architecture in which the VoIP application is modified. The key aspect of this architecture is the factor of two increase in capacity that it can accommodate relative to architectures utilizing standard VoIP. An important aspect of all our tracking architectures is the Tracking Server. This server supplies the location information in the event of GPS unavailability. A final contribution of this thesis is the development of novel particle-filter based tracking algorithms that specifically address the GPS intermittency issue. We show how these filters interact with other features of our SIP based architectures in a seamless fashion.

Includes bibliographical references (p. 207-232) / xxii, 232 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Due to the rapid deployment of modern over-the-horizon radars, antenna/sensor position errors may be present and, since the antennas have a simple and cost-effective design, mutual coupling may also be present. These imperfections, which can degrade radar performance, form the basis of the investigation. Also calibrates the receiving array of the Jindalee over-the-horizon radar (located in Central Australia) using echoes from meteor trails. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1998

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Current best-effort packet-switched Internet is not a perfect environment for real-time applications such as transmitting voice-over the network (Voice Over Internet Protocol or VOIP). Due to the unlimited concurrent access to the Internet by users, the packet loss problem cannot be avoided. Therefore, the VOIP based applications encompass problems such as "voice quality degradation caused by lost packets". The effects of lost packets are fundamental issues in real-time voice transmission over the current unreliable Internet. The dropped packets have a negative impact on voice quality and concealing their effects at the receiver does not deal with all of the drop consequences. It has been observed that in a very lossy network, the receiver cannot cope with all the effects of lost packets and thereby the voice will have poor quality. At this point the Active Networks, a relatively new concept in networking, which allows users to execute a program on the packets in active nodes, can help VOIP regenerate the lost packets, and improve the quality of the received voice. Therefore, VOIP needs special voice-packing methods. Based on the measured packet loss rates, many new methods are introduced that can pack voice packets in such a way that the lost packets can be regenerated both within the network and at the receiver. The proposed voice-packing methods could help regenerate lost packets in the active nodes within the network to improve the perceptual quality of the received sound. The packing methods include schemes for packing samples from low and medium compressed sample-based codecs (PCM, ADPCM) and also include schemes for packing samples from high compressed frame-based codecs (G.729). Using these packing schemes, the received voice has good quality even under very high loss rates. Simulating a very lossy network using NS-2 and testing the regenerated voice quality by an audience showed that significant voice quality improvement is achievable by employing these packing schemes. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1147315 / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2004

Includes bibliographical references (p. 207-232) / xxii, 232 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Due to the rapid deployment of modern over-the-horizon radars, antenna/sensor position errors may be present and, since the antennas have a simple and cost-effective design, mutual coupling may also be present. These imperfections, which can degrade radar performance, form the basis of the investigation. Also calibrates the receiving array of the Jindalee over-the-horizon radar (located in Central Australia) using echoes from meteor trails. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1998

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.