• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 30
  • 16
  • 16
  • 16
  • 16
  • 16
  • 16
  • 7
  • 6
  • 3
  • 3
  • 2
  • 2
  • 1
  • Tagged with
  • 85
  • 29
  • 20
  • 14
  • 10
  • 10
  • 10
  • 10
  • 10
  • 10
  • 9
  • 9
  • 9
  • 8
  • 8
  • 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.
1

Sediment accumulation and retention in the littoral zone of lakes

Benoy, Glenn A. January 1997 (has links)
Submerged macrophyte beds provide a secondary realm of accumulation in lakes. Particles otherwise destined to reside in the deep-water profundal zone are intercepted by nearshore macrophyte communities that attenuate wave and current energy. The microenvironment found inside submerged macrophyte beds can be substantially more quiescent than that of the open-water, allowing for fine particles to be deposited out of the water column. Together with larger, eroded inorganic sediments and coarse organic particles, these materials comprise the sediments underlying macrophyte communities. / Thirty-four littoral sites were sampled in Lake Memphremagog (Quebec-Vermont) to quantify the role of morphometry (littoral slope and site exposure) and macrophyte beds (mean biomass and biomass density) on the accumulation of sediments. An established historical marker, stable Pb, was used to date the sediments (approx. 110 years) and calculate rates of accumulation (SARs). Identifiable stable Pb profiles were obtained at two-thirds of the sites confirming the utility and robustness of littoral sediment core analysis. Multiple regression analyses showed that macrophyte parameters were the best predictors of SARs. Macrophyte mean biomass and biomass density were clearly most important in predicting the volume (total SAR) and organic content (organic SAR) of the sediments ($R sp2=0.57 rm to 0.76$, $P<0.001$). The same macrophyte parameters, however, poorly predicted the bulk (mainly inorganic) accumulation of sediments. Biomass density was solely related to the long-term accumulation of stable Pb in the sediments supporting empirical models that credit growth form as an important factor explaining among species or among weedbed variability in sediment-plant tissue elemental concentrations. The quantification of SARs will benefit both lakewide modeling of nutrient and contaminant budgets, and the understanding of littoral succession and its contribution to lake ontogeny.
2

Heat transfers in Lake Memphremagog

De Margerie, Sylvain, 1954- January 1982 (has links)
No description available.
3

Optimisation de dispositifs FDSOI pour la gestion de la consommation et de la vitesse : application aux mémoires et fonctions logiques / FDSOI devices optimization to power and speed management : application to memory and logic function

Noël, Jean-Philippe 14 December 2011 (has links)
Avec la percée des téléphones portables et des tablettes numériques intégrant des fonctions avancées de traitement de l'information, une croissance exponentielle du marché des systèmes sur puce (SoC pour System On Chip en anglais) est attendue jusqu'en 2016. Ces systèmes, conçus dans les dernières technologies nanométriques, nécessitent des vitesses de fonctionnement très élevées pour offrir des performances incroyables, tout en consommant remarquablement peu. Cependant, concevoir de tels systèmes à l'échelle nanométrique présente de nombreux enjeux en raison de l'accentuation d'effets parasites avec la miniaturisation des transistors MOS sur silicium massif, rendant les circuits plus sensibles aux phénomènes de fluctuations des procédés de fabrication et moins efficaces énergétiquement. La technologie planaire complètement désertée (FD pour Fully depleted en anglais) SOI, offrant un meilleur contrôle du canal du transistor et une faible variabilité de sa tension de seuil grâce à un film de silicium mince et non dopé, apparaît comme une solution technologique très bien adaptée pour répondre aux besoins de ces dispositifs nomades alliant hautes performances et basse consommation. Cependant pour que cette technologie soit viable, il est impératif qu'elle réponde aux besoins des plateformes de conception basse consommation. Un des défis majeurs de l'état de l'art de la technologie planaire FDSOI est de fournir les différentes tensions de seuils (VT) requises pour la gestion de la consommation et de la vitesse. Le travail de recherche de thèse présenté dans ce mémoire a contribué à la mise en place d'une plateforme de conception multi-VT en technologie planaire FDSOI sur oxyde enterré mince (UTB pour Ultra Thin Buried oxide en anglais) pour les nœuds technologiques sub-32 nm. Pour cela, les éléments clefs des plateformes de conception basse consommation en technologie planaire sur silicium massif ont été identifiés. A la suite de cette analyse, différentes architectures de transistors MOS multi-VT FDSOI ont été développées. L'analyse au niveau des circuits numériques et mémoires élémentaires a permis de mettre en avant deux solutions fiables, efficaces et de faible complexité technologique. Les performances des solutions apportées ont été évaluées sur un chemin critique extrait du cœur de processeur ARM Cortex A9 et sur une cellule SRAM 6T haute densité (0,120 µm²). Egalement, une cellule SRAM à quatre transistors est proposée, démontrant la flexibilité au niveau conception des solutions proposées. Ce travail de recherche a donné lieu à de nombreuses publications, communications et brevets. Aujourd'hui, la majorité des résultats obtenus ont été transférés chez STMicroelectronics, où l'étude de leur industrialisation est en cours. / Driven by the strong growth of smartphone and tablet devices, an exponential growth for the mobile SoC market is forecasted up to 2016. These systems, designed in the latest nanometre technology, require very high speeds to deliver tremendous performances, while consuming remarkably little. However, designing such systems at the nanometre scale introduces many challenges due to the emphasis of parasitic phenomenon effects driven by the scaling of bulk MOSFETs, making circuits more sensitive to the manufacturing process fluctuations and less energy efficient. Undoped thin-film planar fully depleted silicon-on-insulator (FDSOI) devices are being investigated as an alternative to bulk devices in 28nm node and beyond, thanks to its excellent short-channel electrostatic control, low leakage currents and immunity to random dopant fluctuation. This compelling technology appears to meet the needs of nomadic devices, combining high performance and low power consumption. However, to be useful, it is essential that this technology is compatible with low operating power design platforms. A major challenge for this technology is to provide various device threshold voltages (VT), trading off power consumption and speed. The research work presented in this thesis has contributed to the development of a multi-VT design platform in FDSOI planar technology on thin buried oxide (UTB) for the 28nm and below technology nodes. In this framework, the key elements of the low power design platform in bulk planar technology have been studied. Based on this analysis, different architectures of FDSOI multi-VT MOSFETs have been developed. The analysis on the layout of elementary circuits, such as standard cells and SRAM cells, has put forward two reliable, efficient and low technological complexity multi- strategies. Finally, the performances of these solutions have been evaluated on a critical path extracted from the ARM Cortex A9 processor and a high-density 6T SRAM cell (0.120µm²). Also, an SRAM cell with four transistors has been proposed, highlighting the design flexibility brought by these solutions. This thesis has resulted in many publications, communications and patents. Today, the majority of the results obtained have been transferred to STMicroelectronics, where the industrialization is in progress.
4

Sediment accumulation and retention in the littoral zone of lakes

Benoy, Glenn A. January 1997 (has links)
No description available.
5

Heat transfers in Lake Memphremagog

De Margerie, Sylvain, 1954- January 1982 (has links)
No description available.
6

Erstellung eines Marketingkonzepts für die Nutzung eines ehemaligen TEE-Triebwagens (BR VT 601)

El-Tattan, Anuar January 2008 (has links) (PDF)
This diploma thesis analyzes and evaluates potential utilization scenarios for a former Trans Europ Express VT 601, the flagship of the German Federal Railways from the fifties to the late eighties. The introduction of the Trans Europ Express (TEE) ushered in a new era of Intra-European passenger traffic and was the beginning of increased private and business travel mainly between the founding countries Germany, Italy, France, Suisse and the Netherlands. Because of its outstanding performance, comfort and reliability the TEE upheld its enormous popularity for more than thirty years of use before it was replaced by the Eurocity (EC) in 1987. Today, 50 years after its maiden trip, the last remaining privately held TEE VT 601 is intended to be recreated as a luxury train in a new design. For this purpose, this work investigates alternative stationary and mobile utilization scenarios and assesses them from a financial and qualitative point of view. The results show potential weaknesses of this project primarily because of the high costs involved in the restructuring process. Furthermore a recommended strategic course of action is given in order to provide the involved decision-makers with appropriate ideas of how to successfully establish a strong position in the luxury travel market. (author's abstract) / Series: Schriftenreihe des Instituts für Transportwirtschaft und Logistik - Verkehr
7

Relationship between Key Variables in Penile Plethysmograph and Viewing Time Measures of Sexual Arousal in Sex Offending Adult Males

Cloyd, Lisa Loewinger 11 December 2007 (has links)
Penile plethysmography is amongst the best measures for prediction of sexual recidivism and has been extensively researched. However, there are a variety of criticisms regarding use of penile plethysmography (PPG), including financial investment, significant training needs, lack of standardization, intrusive nature of the measure, extensive time for testing, and inability to use PPG with all groups of sexual offenders (e.g., women and adolescents). Viewing time has been studied, though not as extensively as PPG, regarding detection of sexual interest. This study examined the relationship between Monarch 21 PPG and Affinity viewing time variables, including responses to individual stimuli, a sex deviance differential, and a sex deviance ratio. It was predicted that there would be a significant positive correlation between key variables of the Monarch 21 PPG and Affinity. Overall, the associations found between the Monarch 21 PPG and the Affinity were significant, although the magnitudes of the associations were modest. When considering sexual deviance ratios and differentials (as is typically utilized in PPG literature), there was a small, but significant association between the Monarch 21 PPG and the Affinity. Consequently, it is recommended that more research be done comparing these two sets of measures, further evaluating the Affinity and its' predictive validity, and examining the complex arousal pattern shapes, rather than focusing only on a series of discrete variables.
8

Nitrogen retention in freshwater ecosystems

Saunders, Darla L. January 2000 (has links)
Given the prominent role of nitrogen in the eutrophication of aquatic systems, recent increases in nitrogen loading to freshwaters are of concern. A comparison of nitrogen retention in freshwaters in North America and Europe shows that wetlands retain the greatest proportion of their nitrogen load, followed by lakes and then rivers. A comparison of the relative importance of nitrogen retention mechanisms found denitrification to be responsible for the greatest proportion followed by nitrogen sedimentation and then uptake by aquatic plants. A more in-depth examination of denitrification in the littoral sediments of Lake Memphremagog in Quebec, using the N2 flux technique, found an average denitrification rate of 111 mumol N m-2 h-1. Denitrification rates were positively related to the % organic matter of the sediment, temperature and macrophyte biomass density and negatively related to depth. These results, in combination with a review of the literature indicate that denitrification rates are higher in littoral than profundal sediments.
9

Stability of a Normal Heterosexual Female Response to Affinity 2.0

Harmon, Kara L. 22 March 2007 (has links)
The purpose of the current study was to evaluate the temporal stability of a normal heterosexual female response to the Affinity 2.0, a newly standardized viewing time (VT) instrument that purports to measure sexual interest. Participants were 120 female undergraduate and graduate students from a private university (mean age = 21.67 years) who met inclusion criteria of non-pedophilic interest/history, identified as “Exclusively Heterosexual" on the Kinsey Scale, and who took the Affinity 2.0 both at test and at retest (approximately two weeks later). Participants also filled out a questionnaire following the retest composed of demographic questions, a shortened version of the Marlowe-Crowne Desirability Scale-10 [M-C 2(10)], and declared their sexual interest on the Kinsey Scale. Pearson correlation coefficients (PPMCC), Spearman's Rho correlation coefficients, and a Chi-Square Goodness of Fit Test were all utilized to assess the temporal stability of the sample's response to Affinity 2.0. All PPMCC and Spearman's Rho correlations for VT were statistically significant at the p < .01 level; while practical significance for PPMCC could only be considered moderate as best (range of r =.28 - .63), Spearman's Rho correlations (range of r =.41 - .65) were stronger and approached practical significance. The existence of an overall distinct and discernable VT response pattern was apparent as the sample demonstrated identical categorical VT preferences both test and retest. These results were consistent with results from previous VT studies (Quinsey, Rice, Grant & Reid, 1993; Wright & Adams, 1994; Quinsey, Ketsetzis, Earls, & Karamanoukian, 1996). In addition, this VT pattern was found to be stable from test to retest as assessed by a Chi-Square Goodness of Fit Test. An unexpected finding was the presence of elevated VT for adult and juvenile female images. Implications, limitations, and future studies are discussed.
10

Nitrogen retention in freshwater ecosystems

Saunders, Darla L. January 2000 (has links)
No description available.

Page generated in 0.0287 seconds