• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1092
  • 203
  • 155
  • 150
  • 132
  • 67
  • 49
  • 41
  • 41
  • 31
  • 20
  • 16
  • 12
  • 11
  • 9
  • Tagged with
  • 2308
  • 302
  • 289
  • 279
  • 275
  • 274
  • 274
  • 273
  • 273
  • 231
  • 202
  • 184
  • 143
  • 130
  • 119
  • 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.
181

ONE-PEDAL-DRIVE AND REGENERATIVE BRAKING STRATEGY: STUDY ON VEHICLE DRIVABILITY AND ENERGY EFFICIENCY

Goretti Barroso, Daniel January 2024 (has links)
The shift towards electric transportation on a global scale is being primarily driven by regulatory requirements and market demand. The impact of the COVID-19 pandemic on air pollution, energy demand, and CO2 emissions has further accelerated this transition. This transformation necessitates the development of efficient electric propulsion systems, particularly for commercial vehicles. These systems not only have a positive environmental impact but also offer significant financial advantages to fleet owners due to lower overall costs. One of the major challenges in this transition is the design and calibration of regenerative braking strategies, especially for commercial vehicles that exhibit significant variations in weight. This weight difference between curb and gross vehicle weight is a common scenario in the commercial vehicle sector. This thesis introduces the Adaptive One-Pedal Drive (A-OPD) strategy, which is specifically tailored for electric commercial vehicles with varying weight profiles and lacking advanced drive-by-wire braking systems. The thesis focuses on the development and accurate assessment of a model-centric approach for electrified propulsion systems. This approach establishes a strong correlation between the model and physical data, demonstrating its reliability in estimating critical variables such as battery state-of-charge, battery terminal voltage, system high-voltage DC, and wheel torque, even under diverse driving conditions. This model-centric approach serves as a valuable tool for optimizing design and conducting tradeoff analyses, enabling efficient evaluation of energy efficiency and drivability. Selecting the most suitable electrified propulsion system architecture is a crucial decision. The thesis categorizes electrified propulsion system architectures based on their impact on vehicle performance, energy consumption, and total cost of ownership. This selection process involves a multidisciplinary approach that takes into account both technical and business requirements. The central research focus of this thesis centers on regenerative braking systems. It compares series and parallel configurations, traditional one-pedal-drive (OPD), and introduces an innovative Adaptive One-Pedal Drive (A-OPD). The A-OPD relies on vehicle running mass identification using the Recursive Least Square Filter (RLS) and weight classification. This A-OPD strategy significantly enhances energy efficiency in urban traffic scenarios, even when vehicles are partially loaded. It outperforms parallel regenerative braking systems by up to 50% while maintaining performance levels similar to the series regenerative braking strategy. This innovation represents a significant leap in energy efficiency for electric commercial vehicles without the need for complex electronic braking systems. In summary, this thesis advances our understanding of optimizing the performance of electric commercial vehicles. The A-OPD strategy proves to be a practical and valuable tool for enhancing energy efficiency, particularly in dense urban traffic, and it outperforms parallel regenerative braking systems. Utilizing model-in-the-loop and driver-in-the-loop simulations, this thesis offers a comprehensive framework for designing efficient electrified propulsion system architectures. / Thesis / Doctor of Philosophy (PhD)
182

Seeding Rate, Nitrogen Rate, and Planting Date of One-Irrigation Barley at Marana, 1987

Ottman, Mike, Ramage, Tom, Thacker, Gary 09 1900 (has links)
One-irrigation barleys were bred to be grown with only a single irrigation near planting time. To further our understanding of how to manage these new cultivars, one-irrigation barleys were grown at 4 seeding rates (20, 40, 60, and 80 lbs seed /A), 4 nitrogen rates (0, 50, 100, and 150 lbs/A), and 3 planting dates (Nov. 17, Dec. 15, and Jan. 22). Seeding rates 01 40 to 60 lbs seed/A resulted in the highest yields at the Dec. 15 planting date, comparing all planting dates combined. However, in individual analyses of the Nov. 17 and Jan. 22 planting dates, no significant differences in yield due to seeding rate were detected. Grain yield increased linearly with nitrogen rate at the Nov. 17 planting date, but was not influenced by nitrogen rate at the other planting dates. Yields were similar for the Nov. 17 and Dec. 15 planting dates, but decreased considerably in the Jan. 22 planting date due partially to lower head number. Grain yields of 2-22-9 were consistently higher than Seco this year.
183

One-Irrigation Barley Observations in Graham and Cochise Counties, 1987

Clark, Lee, Young, Deborah, Schwennesen, Eric 09 1900 (has links)
A series of experimental plots was planted because ranchers, conservationists, farmers and homeowners in southeastern Arizona were interested in knowing more about one -irrigation barleys. The results of these observations are contained in this paper.
184

Yield and Water Use of Barley Cultivars Compared Under an Irrigation Water Gradient at Marana, 1987

Ottman, Mike, Ramage, Tom, Brown, Paul, Thacker, Gary 09 1900 (has links)
This study was initiated to determine how barley cultivars perform outside the environment for which they were selected. Also, a comparison was made of water use by a one-irrigation barley with water use of a commercial cultivar selected for high yield conditions. Six barley cultivars bred for differing growing conditions (Westbred Gustoe and Westbred Barcott - high input; Arivat and Prato - medium input; and, Seco and 2-22-9 - low input) were compared under 12 water regimes delivered by a line -source sprinkler system. Water use of Seco, a one-irrigation barley, and Westbred Gustoe, a commercial barley, was monitored with a neutron probe. The barley cultivars bred for high, medium, and low input conditions performed best in their respective optimum water levels with the exceptions of Westbred Barcott and Prato. Westbred Barcott (high input) yielded relatively well over all water levels, and Prato (medium input), performed similar to a high input barley. Seco (low input) used slightly less water than Westbred Gustoe (high input), primarily due to its earlier maturity. The water extraction pattern with depth was similar for both cultivars due to the frequent shallow irrigations applied in this study. The water extraction pattern of Seco needs to be investigated under one- irrigation conditions.
185

Cross-border price convergence: the case of the MERCOSUR

Samaniego Ruiz Diaz, Adriana January 1900 (has links)
Master of Arts / Department of Economics / Yang M. Chang / This paper empirically examines whether there is a tendency for trade-induced price convergence - in other words if price differences among city pairs separated by a border decline with increased levels of trade. The paper examines the prices of goods in cities across Brazil and Paraguay after the implementation of MERCOSUR. Evidence of a border effect - the failure of the law of one price - between Brazil and Paraguay is found. However, the data show that since the beginning of MERCOSUR, price dispersion between Brazil and Paraguay is less for those goods that are traded more between these partners.
186

Packaging systems decision makin; to assure cost efficient transports

Abubakr, Raowa, Patel, Pooja January 2016 (has links)
No description available.
187

A Cryptographic Attack: Finding the Discrete Logarithm on Elliptic Curves of Trace One

Bradley, Tatiana 01 January 2015 (has links)
The crux of elliptic curve cryptography, a popular mechanism for securing data, is an asymmetric problem. The elliptic curve discrete logarithm problem, as it is called, is hoped to be generally hard in one direction but not the other, and it is this asymmetry that makes it secure. This paper describes the mathematics (and some of the computer science) necessary to understand and compute an attack on the elliptic curve discrete logarithm problem that works in a special case. The algorithm, proposed by Nigel Smart, renders the elliptic curve discrete logarithm problem easy in both directions for elliptic curves of so-called "trace one." The implication is that these curves can never be used securely for cryptographic purposes. In addition, it calls for further investigation into whether or not the problem is hard in general.
188

I belong to the theatre : the play and the process

Andrews, Sydney 26 October 2010 (has links)
The purpose of my thesis is to create one-person show lasting approximately twenty minutes. The following paper contains the step-by-step process of developing this piece of work, audience reactions to the final performance, and thoughts on continuing the process in hope of sharing the play with other communities. / text
189

Subdivision Surface based One-Piece Representation

Lai, Shuhua 01 January 2006 (has links)
Subdivision surfaces are capable of modeling and representing complex shapes of arbi-trary topology. However, methods on how to build the control mesh of a complex surfaceare not studied much. Currently, most meshes of complicated objects come from trian-gulation and simplification of raster scanned data points, like the Stanford 3D ScanningRepository. This approach is costly and leads to very dense meshes.Subdivision surface based one-piece representation means to represent the final objectin a design process with only one subdivision surface, no matter how complicated theobject's topology or shape. Hence the number of parts in the final representation isalways one.In this dissertation we present necessary mathematical theories and geometric algo-rithms to support subdivision surface based one-piece representation. First, an explicitparametrization method is presented for exact evaluation of Catmull-Clark subdivisionsurfaces. Based on it, two approaches are proposed for constructing the one-piece rep-resentation of a given object with arbitrary topology. One approach is to construct theone-piece representation by using the interpolation technique. Interpolation is a naturalway to build models, but the fairness of the interpolating surface is a big concern inprevious methods. With similarity based interpolation technique, we can obtain bet-ter modeling results with less undesired artifacts and undulations. Another approachis through performing Boolean operations. Up to this point, accurate Boolean oper-ations over subdivision surfaces are not approached yet in the literature. We presenta robust and error controllable Boolean operation method which results in a one-piecerepresentation. Because one-piece representations resulting from the above two methodsare usually dense, error controllable simplification of one-piece representations is needed.Two methods are presented for this purpose: adaptive tessellation and multiresolutionanalysis. Both methods can significantly reduce the complexity of a one-piece represen-tation and while having accurate error estimation.A system that performs subdivision surface based one-piece representation was im-plemented and a lot of examples have been tested. All the examples show that our ap-proaches can obtain very good subdivision based one-piece representation results. Eventhough our methods are based on Catmull-Clark subdivision scheme, we believe they canbe adapted to other subdivision schemes as well with small modifications.
190

Dietary and genetic influences on neural tube defects

Fathe, Kristin Renee 16 September 2014 (has links)
Neural tube defects (NTDs) are a world health issue, affecting approximately 1 in every 1000 live births. These congenital defects arise from the improper closure of the neural tube during development, resulting in significant, life-threatening malformations of the central nervous system. Although it has been observed that supplementing women of child-bearing age with folates greatly decreases the chances of having an NTD affected baby, unfortunately these defects still occur. It is accepted that these complex disorders arise from a combination of genetic, environmental, and dietary influences. One such dietary influence is the one-carbon metabolism metabolite, homocysteine. Homocysteine is a byproduct of methylation reactions in the cell that exists in an inverse homeostasis with folate. Homocysteine can also undergo a transformation that allows it to then react with exposed lysine or cysteine residues on proteins, in a process known as N-homocysteinylation or S-homocysteinylation respectively. High levels of homocysteine have been long correlated with many disease states, including NTDs. One potential mechanism by which homocysteine confers its negative effects is through protein N-homocysteinylation. Here, a novel and high-throughput assay for N-homocysteinylation determination is described. This assay is shown to be accurate with mass spectrometry then shown to be biologically relevant using known hyperhomocysteinemia mouse models. This assay was then applied to a cohort of neural tube closure staged mouse embryos with two different genetic mutations that have previously been shown to predispose mice to NTDs. The genotypes explored here are mutations to the LRP6 gene and the Folr1 gene, both of which have been described as folate-responsive NTD mouse models. It was seen that maternal diet and embryonic genotype had the largest influence on the developmental outcome of these embryos; however, the inverse relationship between folate and homocysteine seemed to be established at this early time point, emphasizing the importance of the balance in one-carbon metabolism. One of these genes, LRP6, was then explored in a human cohort of spina bifida cases. Four novel mutations to the LRP6 gene were found and compared to the mouse model used in the previous study. One of the mutations found in the human population was seen to mimic that of the LRP6 mouse model, therefore expanding the potential of this NTD model. / text

Page generated in 0.0506 seconds