Ce mémoire aborde le problème de la détection de visages à partir d'une image compressée. Il touche également à un problème connexe qui est la qualité des standards de compression et l'estimation de celle-ci. Ce mémoire est organisé sous la forme d'une introduction générale sur la détection de visages et de deux articles soumis à des conférences internationales. Le premier article propose une amélioration de la méthode classique pour comparer la qualité de deux standards. Le deuxième propose une méthode de décompression spécialisée pour faire fonctionner le détecteur de visages de Viola-Jones dans le domaine compressé.

Présentement, les pylônes à treillis en acier sont les structures supportant les lignes électriques qui sont les plus présentes dans les réseaux existants. Ces types de structures représentent une solution économique qui permettent de franchir des portées très grandes tout en étant très faciles à construire. Bien qu'elles soient souvent considérées comme inesthétiques, il y a fort à parier qu'elles seront encore utilisées dans les conceptions nouvelles du fait qu'elles possèdent des atouts importants. Les pylônes à treillis en acier sont majoritairement constitués de cornières qui possèdent l'avantage de pouvoir être assemblées facilement ce qui diminue ainsi de beaucoup les problèmes de construction. Il est donc d'un intérêt primordial de maîtriser cette composante structurale des pylônes à treillis en acier et de connaître l'efficacité de ses principales normes de calcul. Ce mémoire se consacre donc à vouloir comparer les différentes normes en lien avec l'approche colonne (approche de calcul ne demandant pas d'intégrer la flexion due aux excentricités des connexions dans les calculs) pour le calcul des cornières simples en compression, à ailes égales. Le projet de recherche tente aussi de faire mieux comprendre le comportement non linéaire des membrures afin qu'éventuellement on puisse prédire plus précisément le comportement post-élastique des pylônes à treillis en acier. Les objectifs de ce projet de recherche sont donc: (1) d'effectuer des essais expérimentaux sur des cornières simples en compression (membrures contreventements), à ailes égales, dans un environnement structural de pylône à treillis, afin de comparer les résultats de résistances avec ceux de l'application des normes suivantes, selon une approche de calcul colonne: CSA S16-01, AISC-LRFD (2005), ASCE (Manuel 10-97), CSA S37-01 et EUROCODE 3; (2) de décrire le comportement non linéaire des cornières à l'étude. Le contenu de ce mémoire permet d'affirmer que la norme ASCE 10-97 semble être la méthode la plus appropriée pour la conception des contreventements dans les pylônes à treillis. En général, il permet aussi de constater que le comportement non linéaire des cornières semble pouvoir être raisonnablement bien prévisible.

Aujourd'hui, les pylônes à treillis en acier sont les structures les plus utilisées dans les réseaux de transport de l'énergie électrique en Amérique du Nord. Ces structures présentent un intérêt au niveau de leur coût et de leur facilité de l'assemblage lors de la construction. Néanmoins, l'acier demeure un matériau corrodable. Dès leur mise en service, les lignes de transport d'énergie vieillissent et se corrodent. Certaines des structures existantes ont été construites il y a plus de 70 ans et la plupart de ces structures servent toujours, malgré leur vie utile estimée a 50 ans. Afin d'établir un programme de réparation et de maintenance efficient pour ces structures âgées, il est essentiel, dans un premier temps, d'évaluer leur état. L'évaluation de leur état est une tâche très fastidieuse à cause du manque d'information précise et de la nature complexe de la détérioration possible. De plus, certains éléments structuraux sont enfouis. Il est donc à propos de se questionner sur le comportement des fondations des pylônes à treillis dans le futur. Il faut tout d'abord identifier le problème et prouver que certaines fondations des pylônes en service peuvent être affectées par la corrosion. Il est pertinent de déterminer comment repérer les pylônes qui sont plus sujet au développement de la corrosion au niveau de leur fondation. Il faut ensuite évaluer à quel point la corrosion affecte la capacité structurale de la fondation selon son niveau de développement, donc de déterminer la capacité résiduelle d'une cornière corrodée. C'est dans cette optique que la Chaire de recherche CRSNG/HQTÉ a proposé un projet de maîtrise visant à approfondir les connaissances sur l'état des membrures de pylônes enfouies des pylônes à treillis en acier et d'évaluer leur intégrité structurale. Le présent projet de maîtrise tente d'éclaircir ces points d'investigation par ses objectifs qui sont de déterminer les paramètres influençant la corrosion des fondations de pylônes existants et d'être en mesure d'évaluer les possibilités de corrosion dans le futur et de déterminer la capacité résiduelle des cornières corrodées en compression.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / In this work, a scalable perceptual JPEG2000 encoder that exploits properties of the human visual system (HVS) is presented. The algorithm modifies the final three stages of a conventional JPEG2000 encoder. In the first stage, the quantization step size for each subband is chosen to be the inverse of the contrast sensitivity function (CSF). In bit-plane coding, two masking effects are considered during distortion calculation. In the final bitstream formation step, quality layers are formed corresponding to desired perceptual distortion thresholds. This modified encoder exhibits superior visual performance for remote sensing images compared to conventional JPEG2000 encoders. Additionally, it is completely JPEG2000 Part-1 compliant, and therefore can be decoded by any JPEG2000 decoder.

BACKGROUND:Sequential compression devices (SCDs) are commonly used for thromboprophylaxis in postoperative patients but compliance is often poor. We investigated causes for noncompliance, examining both hospital and patient related factors.METHODS:100 patients undergoing inpatient urologic surgery were enrolled. All patient had SCD sleeves placed preoperatively. Postoperative observations determined SCD compliance and reasons for non-compliance. Patient demographics, length of stay, inpatient unit type, and surgery type were recorded. At discharge, a patient survey gauged knowledge and attitudes regarding SCDs and bother with SCDs. Statistical analysis was performed to correlate SCD compliance with patient demographics / patient knowledge and attitudes regarding SCDs / and patient self-reported bother with SCDs.RESULTS:Observed overall compliance was 78.6%. The most commonly observed reasons for non-compliance were SCD machines not being initially available on the ward (71% of non-compliant observations on post-operative day 1) and SCD use not being restarted promptly after return to bed (50% of non-compliant observations for entire hospital stay). Mean self-reported bother scores related to SCDs were low, ranging from 1-3 out of 10 for all 12 categories of bother assessed. Patient demographics, knowledge, attitudes and bother with SCD devices were not significantly associated with non-compliance.CONCLUSIONS:Patient self-reported bother with SCD devices was low. Hospital factors, including SCD machine availability and timely restarting of devices by nursing staff when a patient returns to bed, played a greater role in SCD non-compliance than patient factors. Identifying and addressing hospital related causes for poor SCD compliance may improve postoperative urologic patient safety.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Systems & Processes Engineering Corporation (SPEC) compared compression and decompression algorithms and developed optimal forms of lossless and lossy compression for hyperspectral data. We examined the relationship between compression-induced distortion and additive noise, determined the effect of errors on the compressed data, and showed that the data could separate targets from clutter after more than 50:1 compression.

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / Lempel-Ziv-Welch (LZW) algorithm is a popular data compaction technique that has been adopted by CCITT in its V.42bis recommendation and is often implemented in association with the V.32 standard for 9600 bps modems. It has also been implemented as Microcom Networking Protocol (MNP) Level 7, where it goes by the name of Enhanced Data Compression. LZW compacts data by encoding frequently occurring input strings with a single output symbol. The algorithm automatically generates a string dictionary for each symbol at each end of the transmission path. The amount of compaction that can be derived with the LZW algorithm varies with the type of data being transmitted and the efficiency by which table entries can be indexed. Table indexing is usually implemented by use of a hashing table. Although some manufacturers advertise a 4-to-1 gain in throughput, this seems to be an extreme case. This paper documents a implementation of the exact ZLW algorithm. The results presented in this paper are significantly less, typically on the order of 1-to-2 for ASCII text, with substantially less compaction for pre-compacted files or files containing random bit patterns. The efficiency of the LZW algorith on ASCII text is shown to be a function of dictionary size and block size. Although fewer transmitted symbols are required for larger dictionary tables, the additional bits required for the symbol index is marginally greater than the efficiency that is gained. The net effect is that dictionary sizes beyond 2K in size are increasingly less efficient for input data block sizes of 10K or more. The author concludes that the algorithm could be implemented as a direct table look-up rather than through a hashing algorithm. This would allow the LZW to be implemented with very simple firmware and with a maximum of hardware efficiency.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The older F16 jet fighters are currently being flight tested to evaluate the upgraded electronics for aircraft avionics, flight control and weapons systems. An instrumentation system capable of recording three different video signals, recording four Military- Standard-1553B (Mil-Std-1553B) data streams, recording one PCM stream, transmitting the PCM stream, and transmitting two video signals was needed. Using off the shelf equipment, the F16 instrumentation system was design to meet the electronic specifications, limited available space of a small jet fighter, and limited space in the SBand frequency range.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper presents the results of installing a distributed feedback (DFB) laser transmitter and the appropriate optical receiver in an operational site. Frequencies from 1435 to 2400 megahertz are transported intact from a remote site to a local site. From the theoretical calculations, 10 dB of dynamic range may need to be recovered by the use of an automatic gain circuit. The actual device is a delight, needing no additional circuitry to meet specifications. Predictions of performance were made from calculations. The installed system was measured for 1 dB compression point and for figure of merit.

In spite of the presence of much research in the field of foldable structures whose applications have covered most of the requirements of academic and practical aspects of life, there is still a wide domain in which to undertake further studies. One of the required studies is to invest in foldable structures for the process of temporary accommodation. This study endeavours to find solutions for folding pyramidal shapes constructed from stiff panels that can be used as an upper part of temporary accommodation units, e.g., roofs. Several attempts have been made to find a mechanism that realises the folding of a three-dimensional pyramid. These attempts led to suggest a design that represents an initial solution for folding the pyramid. It was taken into consideration in this design that the structure should deploy strain free when the thickness of its panels is not considered. Trigonometry was used to find mathematical equations that can be used to identify the lengths and angles of the proposed design plates. These equations theoretically proved the validity of the proposed mechanism. The proposed design was applied to construct an actual model formed with thick panels. Considering the panel thickness of the model plates led to amendments and improvements to the proposed design. Two actual models were experimentally tested to make sure that they achieve the design concepts in the processes of full folding and deployment. The models were also tested in the laboratory to make sure of the integrity of the panel hinges and resistance of the elements to external loading. The model was constructed in a simulation program in order to verify the foldability of the design, folding efficiency and absence of strain or collisions during the process of folding and deployment at all stages.