• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 100
  • 31
  • 30
  • 29
  • 17
  • 9
  • 7
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 270
  • 40
  • 25
  • 23
  • 23
  • 22
  • 19
  • 17
  • 17
  • 17
  • 16
  • 15
  • 15
  • 14
  • 13
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Growth of Lattice-matched Ternary and Quaternary Compound Semiconductors on InP by Molecular Beam Epitaxy

Lai, Min-Feng 09 July 2002 (has links)
This work is to control the fluxes of the Ga, In and Al sources in our MBE system to grow lattice-matched InGaAs, InAlAs and InGaAlAs epi-layers on InP substrates. With the As overpressure condition in the MBE system, we can control the temperature of Ga K-cell to modulate the flux of Ga. In ideal situation, the flux of Ga has a direct ratio with the GaAs growth rate on GaAs substrate, so we can find the Ga flux dependence on temperature by measuring the RHEED oscillation frequency. From the growth rate data of InGaAs on GaAs substrate at lower In composition, the In flux was obtained by comparing the growth rate ratio to the GaAs case. In the same way, we can also get the flux of Al by the growth of AlAs or AlGaAs on GaAs substrate. With the results of flux experiment, we can modulate the temperature of Ga, In and Al K-cells to compose InGaAs, InAlAs and InGaAlAs lattice-matched on InP substrates. The epi-layer quality was examined by X-ray diffraction and photo-absorption spectrum. We have built the flux equations for the Ga, In and Al sources from the experiment data. With the In K-cell temperature at 833~836¢J, Ga(1) at 931¢J and Al at 1094¢J, we have grown ternary compound semiconductors of In0.532Ga0.468As and In0.523Al0.477As lattice-matched on InP substrates. When the In K-cell temperature at 833~836¢J, Ga(2) at 912¢J and Al at 1059¢J, a quaternary compound semiconductor of In0.527Ga0.245Al0.228As (Eg=1eV) lattice-matched on InP substrate was demonstrated.
12

Exploration Of Image Recognition On Specific Patterns and Research Of Sub-pixel Algorithm

Yang, Jeng-Ho 10 July 2002 (has links)
Image processing technologies are broadly applied on modern machine vision and industrial inspection , but there is usually a trade-off between accuracy and speed of inspection . We plan to solve the plight by two steps : 1.We will develop many major image processing methods such as image boundary¡Bto remove the noise¡Bpattern match , and so on . 2.We will focus on sub-pixel algorithm and boundary research to improve the image accuracy and processing time by software under limited hardware . As we know , pixel is the most basic element of an image , but we can divide one pixel into several smaller parts by mathematics ; in the meanwhile , the pixel accuracy can be improved . We will use algorithm to realize the goal in continuous way , and research on the flow of image recognition to find out a best flow for any specific image properties .
13

A Study and Implementation of Match Problem

Shyu, Jin-Hong 14 August 2003 (has links)
Match problem is a very practical problem. For example, distribution system of united examination today is a kind of match problem. However, it is very inconvenient to hand over preference card now. Person must leave for designate place to hand over preference card. Besides, Internet is in widespread use now. A lot of work has accomplished and achieved conveniently by the use of Internet, such as Internet filing tax, electronic document and so on. After the work electronic-based, the work efficiency and personal convenience will be increased. Therefore, this study is constructing a system, which combines handing over preference card with Internet and considering that the security of Internet. This can simplify the procedure of handing over preference card.
14

On the modular verification and design of firewalls

Bhattacharya, Hrishikesh 13 November 2012 (has links)
Firewalls, packet filters placed at the boundary of a network in order to screen incoming packets of traffic (and discard any undesirable packets), are a prominent component of network security. In this dissertation, we make several contributions to the study of firewalls. 1. Current algorithms for verifying the correctness of firewall policies use O(n[superscrip d]) space, where n is the number of rules in the firewall (several thousand) and d the number of fields in a rule (about five). We develop a fast probabilistic firewall verification algorithm, which runs in time and space O(nd), and determines whether a firewall F satisfies a property P. The algorithm is provably correct in several interesting cases -- notably, for every instance where it states that F does not satisfy P -- and the overall probability of error is extremely small, of the order of .005%. 2. As firewalls are often security-critical systems, it may be necessary to verify the correctness of a firewall with no possibility of error, so there is still a need for a fast deterministic firewall verifier. In this dissertation, we present a deterministic firewall verification algorithm that uses only O(nd) space. 3. In addition to correctness, optimizing firewall performance is an important issue, as slow-running firewalls can be targeted by denial-of-service attacks. We demonstrate in this dissertation that in fact, there is a strong connection between firewall verification and detection of redundant rules; an algorithm for one can be readily adapted to the other task. We suggest that our algorithms for firewall verification can be used for firewall optimization also. 4. In order to help design correct and efficient firewalls, we suggest two metrics for firewall complexity, and demonstrate how to design firewalls as a battery of simple firewall modules rather than as a monolithic sequence of rules. We also demonstrate how to convert an existing monolithic firewall into a modular firewall. We propose that modular design can make firewalls easy to design and easy to understand. Thus, this dissertation covers all stages in the life cycle of a firewall -- design, testing and verification, and analysis -- and makes contributions to the current state of the art in each of these fields. / text
15

Internal and external match loads of university-level soccer players : a comparison between methods / Martinique Sparks

Sparks, Martinique January 2015 (has links)
A need exists to obtain accurate, reliable and valid data to assess the external and internal loads of soccer matches, especially as it relates to South African soccer teams. Consequently, the objectives of this study were firstly to determine the fatigue rates and patterns of a cohort of university-level soccer players during matches when using global positioning system (GPS) to quantify the high-intensity running performances in rolling 5-min periods. Secondly, to determine the influence of Yo-Yo intermittent recovery test level 1 (Yo- Yo IR1) determined training status of a cohort of university-level soccer players on fatigue patterns and rate during match play. Thirdly, to determine the positional-internal match loads of a cohort of university-level soccer players by making use of heart rates and the Yo-Yo IR1-determined threshold values. Lastly, to compare the match analysis results of different methods aimed at determining the external and internal match loads of a cohort of university-level soccer players. Selected groups of university-level soccer players (n = 10–13) were required to complete a 40-m maximum speed test and the Yo-Yo IR1 during a two-week period either before or after each analysed match. The heart rate (HR) values and GPS data of each player were recorded during league soccer matches. For the first and second objectives of the study players were categorised into three activity level categories (low, moderate and high) according to their activity levels of the first half of the match. Furthermore, their high-intensity running (> 3.7m/s) (HIR) was monitored in rolling 5-min periods. The low-activity group showed a small to moderate difference (p <0.05) in high-intensity running (HIR) at 5-min and 15-min after the peak period compared to the average 5-min period. The moderate-activity group showed a moderate difference (p <0.05) in HIR at 5-min after the peak period. The high-activity group showed moderate to large declines in distance covered between the first 15-min of the second half (103.9 m/min) compared to the first 15-min of the first half (122.5 m/min). They also showed small to moderate declines in HIR during the first 10-min of the second half (25.7 m/min) compared to the first half (34.1 m/min). The low-activity group showed a small decline in distance covered during the first 5-min of the second half (76.3 m/min) compared to the first half (87.7 m/min). Conversely the low-activity group showed a small to moderate increase in distance covered during the last 10-min of the second half (95.7 m/min) compared to the first half (84.4 m/min). The Yo-Yo IR1 was not significantly correlated with any of the variables associated with HIR. For the third objective of the study players’ heart rates that corresponded with the first and second ventilatory thresholds as obtained during a Yo-Yo IR1 were used to classify heart rates into low (LI HR zone), moderate (MI HR zone) and high-intensity zones (HI HR zone). Results showed that attackers spent more time in the LI HR zone (3386 s; 62%; p <0.05) than defenders (2155 s; 40%) and midfielders (2425 s; 42%). The attackers spent less time in the HI HR zone (260 s; 4%; p <0.05) than the defenders (964 s; 15%). Midfielders (2444 s; 44%) and defenders (2364 s; 41%) spent more time in the MI HR zone than attackers (1854 s; 44%). For the fourth objective of the study players’ individualised velocity and heart rate (HR) thresholds were determined from the 40-m maximum speed test and the Yo-Yo IR1. Results showed a large (r = 0.5; p ≤0.01) correlation between the time spent in the LIVZ (5017 ± 368 s) and the LI HR zone (2891 ± 1086 s), with the true correlation value that varied between moderate and large. Similarly, a moderate (r = 0.3; p ≤0.01) to large (r = 0.6; p ≤0.01) correlation was found between the relative (11.4 ± 3.7%) and absolute time (669 ± 223 s) spent in the MIVZ and the MI HR zone (41.0 ± 16.8% and 2253 ± 752 s). However, the true correlation value for the absolute time spent in the MI zone fell between the large to very large category, whereas the correlation for the relative time was small to moderate. There were no significant correlations (p ≤0.01) between the HIVZ and the HI HR zone. Although some correlations were found from the Spearman’s rank correlation, when adjusting for 2max O V• and Yo-Yo IR1 performance these correlations became non-significant. From these study results it is clear that the Yo-Yo IR1 and 40-m speed test show promise to be used as valid sports-specific field tests for determining ventilatory thresholds for each player, the heart rates that correspond to these thresholds and the different velocity thresholds. The authors therefore recommend that researchers use these methods in future to determine individualised HR and velocity zones in combination with the GPS analysis results to define both the internal and external match loads of soccer players. Results of these analyses could enable future coaches and sport scientists to develop match-specific conditioning programs that reflect both the internal and external demands of soccer matches / PhD (Human Movement Science), North-West University, Potchefstroom Campus, 2015
16

Internal and external match loads of university-level soccer players : a comparison between methods / Martinique Sparks

Sparks, Martinique January 2015 (has links)
A need exists to obtain accurate, reliable and valid data to assess the external and internal loads of soccer matches, especially as it relates to South African soccer teams. Consequently, the objectives of this study were firstly to determine the fatigue rates and patterns of a cohort of university-level soccer players during matches when using global positioning system (GPS) to quantify the high-intensity running performances in rolling 5-min periods. Secondly, to determine the influence of Yo-Yo intermittent recovery test level 1 (Yo- Yo IR1) determined training status of a cohort of university-level soccer players on fatigue patterns and rate during match play. Thirdly, to determine the positional-internal match loads of a cohort of university-level soccer players by making use of heart rates and the Yo-Yo IR1-determined threshold values. Lastly, to compare the match analysis results of different methods aimed at determining the external and internal match loads of a cohort of university-level soccer players. Selected groups of university-level soccer players (n = 10–13) were required to complete a 40-m maximum speed test and the Yo-Yo IR1 during a two-week period either before or after each analysed match. The heart rate (HR) values and GPS data of each player were recorded during league soccer matches. For the first and second objectives of the study players were categorised into three activity level categories (low, moderate and high) according to their activity levels of the first half of the match. Furthermore, their high-intensity running (> 3.7m/s) (HIR) was monitored in rolling 5-min periods. The low-activity group showed a small to moderate difference (p <0.05) in high-intensity running (HIR) at 5-min and 15-min after the peak period compared to the average 5-min period. The moderate-activity group showed a moderate difference (p <0.05) in HIR at 5-min after the peak period. The high-activity group showed moderate to large declines in distance covered between the first 15-min of the second half (103.9 m/min) compared to the first 15-min of the first half (122.5 m/min). They also showed small to moderate declines in HIR during the first 10-min of the second half (25.7 m/min) compared to the first half (34.1 m/min). The low-activity group showed a small decline in distance covered during the first 5-min of the second half (76.3 m/min) compared to the first half (87.7 m/min). Conversely the low-activity group showed a small to moderate increase in distance covered during the last 10-min of the second half (95.7 m/min) compared to the first half (84.4 m/min). The Yo-Yo IR1 was not significantly correlated with any of the variables associated with HIR. For the third objective of the study players’ heart rates that corresponded with the first and second ventilatory thresholds as obtained during a Yo-Yo IR1 were used to classify heart rates into low (LI HR zone), moderate (MI HR zone) and high-intensity zones (HI HR zone). Results showed that attackers spent more time in the LI HR zone (3386 s; 62%; p <0.05) than defenders (2155 s; 40%) and midfielders (2425 s; 42%). The attackers spent less time in the HI HR zone (260 s; 4%; p <0.05) than the defenders (964 s; 15%). Midfielders (2444 s; 44%) and defenders (2364 s; 41%) spent more time in the MI HR zone than attackers (1854 s; 44%). For the fourth objective of the study players’ individualised velocity and heart rate (HR) thresholds were determined from the 40-m maximum speed test and the Yo-Yo IR1. Results showed a large (r = 0.5; p ≤0.01) correlation between the time spent in the LIVZ (5017 ± 368 s) and the LI HR zone (2891 ± 1086 s), with the true correlation value that varied between moderate and large. Similarly, a moderate (r = 0.3; p ≤0.01) to large (r = 0.6; p ≤0.01) correlation was found between the relative (11.4 ± 3.7%) and absolute time (669 ± 223 s) spent in the MIVZ and the MI HR zone (41.0 ± 16.8% and 2253 ± 752 s). However, the true correlation value for the absolute time spent in the MI zone fell between the large to very large category, whereas the correlation for the relative time was small to moderate. There were no significant correlations (p ≤0.01) between the HIVZ and the HI HR zone. Although some correlations were found from the Spearman’s rank correlation, when adjusting for 2max O V• and Yo-Yo IR1 performance these correlations became non-significant. From these study results it is clear that the Yo-Yo IR1 and 40-m speed test show promise to be used as valid sports-specific field tests for determining ventilatory thresholds for each player, the heart rates that correspond to these thresholds and the different velocity thresholds. The authors therefore recommend that researchers use these methods in future to determine individualised HR and velocity zones in combination with the GPS analysis results to define both the internal and external match loads of soccer players. Results of these analyses could enable future coaches and sport scientists to develop match-specific conditioning programs that reflect both the internal and external demands of soccer matches / PhD (Human Movement Science), North-West University, Potchefstroom Campus, 2015
17

Total Synthesis of the Tumor-Associated Carbohydrate Antigen Lewis A Lewis X Hexasaccharide and Selected Fragments

Mickael, Guillemineau 13 August 2012 (has links)
Carbohydrates constitute the most abundant class of natural products in the living world and they play various roles. They are notably involved in cell-cell interactions and immune reactions. It has been observed that tumor cells express, on their surface, unusual oligosaccharides named Tumor-Associated Carbohydrate Antigen (TACA). One TACA of interest to our research group is the Lewis A Lewis X hexasaccharide that is displayed on the surface of squamous lung carcinoma cells. Since carbohydrates are involved in immune reactions and can be recognized by antibodies, it becomes possible to design a carbohydrate-based vaccine against these tumor cells. This thesis describes the total synthesis of the TACA Lewis A Lewis X hexasaccharide and the preparation of two fragments: one tetra- and one pentasaccharide. These molecules were prepared as hexyl and aminohexylglycosides. In addition, the hexasaccharide was synthesized as a disulfide. This diversity of these synthons will allow conjugation to a protein, analysis by nuclear magnetic resonance techniques, and immobilization on gold of the antigen. Without doubt, this work is a significant contribution to the development of an anti cancer vaccine as it constitutes the first stage of the process.
18

Įvairaus meistriškumo futbolininkų kontaktinių veiksmų rezultatyvumas / The results of contact actions of football players with different skills

Butkus, Darius 11 August 2011 (has links)
Taktiniai, tame tarpe dvikovos, puolimo ir gynybos veiksmai, yra vienas iš pagrindinių faktorių, įtakojančių galutiniam rungtynių rezultatui. Per ilgalaikį futbolo sporto šakos vystymosi laikotarpį keitėsi taktinės sistemos, puolimo ir gynybos akcentai, tobulėjo futbolininkų technika ir taktika. Mokslininkai savo tyrimais daug pasiekė didindami sportininkų morfofiziologines ir psichologines galimybes. Todėl gerėjant futbolininkų fiziniam parengtumui nepaprastai padidėjo žaidimo sparta. Futbolininkų taktinio parengimo lygis priklauso nuo to, kaip jie įsisavinę taktikos priemones, formas ir rūšis. Taktikos priemonės - tai visi technikos veiksmai ir jų atlikimo būdai, formos - individualūs, grupiniai, komandiniai veiksmai, rūšys - puolimo ir gynybos taktika, yra tyrinėta ir spręstina mokslinė problema. Tyrimo tikslas – stebėti ir analizuoti futbolininkų kontaktinius veiksmus įvairaus lygio rungtynėse, įvertinti jų efektyvumą. Buvo taikyti 4 tyrimo metodai: literatūros šaltinių analizė ir apibendrinimas, pedagoginis stebėjimas, palyginamoji analizė, matematinė statistika. Brazilijos r. dvikovų skaičius siekia iki 200, iš jų 103 pozityvios ir 97 negatyvios dvikovos. Efektyvumas 51.5 proc. Prancūzijos r. dvikovų skaičius siekia 233, iš jų 124 pozityvios ir 108 negatyvios dvikovos. Efektyvumas 53.2 proc. Lietuvos rinktinės dvikovų skaičius siekia 160, iš jų 76 pozityvios ir 84 negatyvios dvikovos. Efektyvumas 47 proc. FK „Ekranas“ komandos vidutinis dvikovų skaičius per rungtynes... [toliau žr. visą tekstą] / Tactical, including duel, attack and defence actions is one of the crucial indicators influencing the final result of a competition. In a long run of football development the tactical systems, attack and defence focuses has been changing, the techniques of football players improved. The scientists with their research works achieved a lot in increasing morpho physiological and psychological abilities. That is why when physical abilities of the football players improve, the speed of playing enlarged immensely. The level of tactical preparation of football players depend upon the possessing tactical tools, forms and kinds. Tactical tools are all technical actions and their ways of implementation, forms – individual, group, team actions, and kinds – attack and defence technique and all this makes the science scope which has to be analysed and solved. The aim of the analysis is to observe and analyse contact activities of football players at the matches of various level and to evaluate their efficiency. 4 methods of analysis were used: the analysis of literature sources and summarising, pedagogical observing, comparative analysis, mathematical statistics. . In the ranking of the world countries the number of combats reaches 200, out of it 103 are positives and 97 are negative ones. Brazil takes 51.5 pct. In the ranking of France countries the number of combats reaches 233, out of it 124 are positive and 108 are negative ones. Effectiveness takes 53.2 pct. The number of... [to full text]
19

Desenvolvimento e aplicação de um software cristalográfico com protocolo de acesso a um banco de dados distribuído

Utuni, Vegner Hizau dos Santos [UNESP] 13 April 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:32:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-04-13Bitstream added on 2014-06-13T20:23:08Z : No. of bitstreams: 1 utuni_vhs_dr_araiq.pdf: 1401616 bytes, checksum: 9b101e8602c8294ef048247253081576 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Desde a revolução provocada pela segunda geração de computadores ocorrida por volta de 1960 e que permitiu a disseminação dos computadores para os diversos setores da sociedade, vem acontecendo uma evolução na capacidade de processamento dos chips e conseqüentemente no conceito de software. Em se tratando especificamente de softwares científicos, esse incremente no volume e velocidade de processamento de dados torna possível a aplicação de modelos físicoquímicos cada vez mais complexos. Em 1969, o cristalógrafo Hugo Rietveld criou um método que utiliza este novo paradigma tecnológico e que hoje é conhecido como método de Rietveld. Desenvolvido especificamente para o refinamento de dados de difração raios X de amostra policristalinas, passou a ser utilizado em todas as áreas da pesquisa em novos materiais. Para uma boa estabilidade do processo de refinamento é necessário fornecer ao modelo uma aproximação inicial de cada fase que compõe a amostra. Esta exigência é necessária para permitir a estabilidade do processo iterativo que irá ajustar os dados experimentais à função teórica, característica que obriga a uma dependência de bancos de dados especializados. O processo de refinamento utilizando o método de Rietveld é complexo e não linear o que implica necessariamente no uso de um software. Esta característica aliada à dependência de bancos de dados cristalográficos justifica a utilização da nova tecnologia de bancos de dados distribuídos, qualidade desejável e de grande interesse para a comunidade científica. Um banco de dados distribuído permite que os vários softwares que empregam o método de Rietveld troquem entre si as informações necessárias para iniciar um refinamento. O gerenciamento deste banco de dados é feito de forma automática pelo próprio software sem interferência humana. A viabilidade da hipótese da utilização... / Since the revolution occurred for the second generation of computers in the 1960 and that it allowed the computers dissemination for the diverse sectors of the society, consequently it comes happening a development in the capacity of chips processing and in the software concept. Specifically treating to scientific software, the volume and processing speed of data increasing becomes possible the application of more complexes physical-chemistry models. In 1969, the crystallographer Hugo Rietveld created a method that uses this new technological paradigm and that today is known as the Rietveld method. Developed specifically to the refinement of polycrystalline X-ray diffraction data, it passed to be used in all areas of the research in new materials. For a good stability of the refinement processes it is necessary to supply to the model an initial approach of each phase that composes the sample. This condition is necessary to allow the stability of the iterative process that will go to adjust the experimental data to the theoretical function, characteristic that it compels to a dependence of specialized data bases. The refinement process using the Rietveld method is complex and not linear which implies necessarily in the use of a software. This characteristic in combination to the dependence of a crystallographic data bases strongest justified the use of the new technology of distributed data bases, desirable quality and of great interest for the scientific community. A distributed data base allows that the several software that using the Rietveld method change information between itself necessary to initiate the refinement process. The management of this data base is made automatically without human interference. The hypothesis viability of the use of a P2P network with CIF archives was demonstrated through the Hera software implementation. New algorithms to automatize the creation... (Complete abstract click electronic access below)
20

Geologic Mapping of The Changgo Dome in Southern Tibet Using ASTER Imagery

Folfas, Andrew Paul 13 November 2008 (has links)
No description available.

Page generated in 0.0367 seconds