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  • 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.
51

Multiple spatial resolution image change detection for environmental management applications

Pape, Alysha Dawn 15 December 2006 (has links)
Across boreal forests and resource rich areas, human-induced change is rapidly occurring at various spatial scales. In the past, satellite remote sensing has provided a cost effective, reliable method of monitoring these changes over time and over relatively small areas. Those instruments offering high spatial detail, such as Landsat Thematic Mapper or Enhanced Thematic Mapper (TM or ETM+), typically have small swath widths and long repeat times that result in compositing intervals that are too large to resolve accurate time scales for many of these changes. Obtaining multiple scenes and producing maps over very large, forested areas is further restricted by high processing costs and the small window of acquisition opportunity. Coarse spatial resolution instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS) or the Advanced Very High Resolution Radiometer (AVHRR) typically have short revisit times (days rather than weeks), large swath widths (hundreds of kilometres), and in some cases, hyperspectral resolutions, making them prime candidates for multiple-scale change detection research initiatives. <p>In this thesis, the effectiveness of 250m spatial resolution MODIS data for the purpose of updating existing large-area, 30m spatial resolution Landsat TM land cover map product is tested. A land cover polygon layer was derived by segmentation of Landsat TM data using eCognition 4.0. This polygon layer was used to create a polygon-based MODIS NDVI time series consisting of imagery acquired in 2000, 2001, 2002, 2003, 2004 and 2005. These MODIS images were then differenced to produce six multiple-scale layers of change. Accuracy assessment, based on available GIS data in a subregion of the larger map area, showed an overall accuracy as high as 59% with the largest error associated with change omission (0.51). The Cramers V correlation coefficient (0.38) was calculated using the GIS data. This was compared to the results of an index-based Landsat change detection, Cramers V=0.67. This thesis research showed that areas greater than 15 hectares are adequately represented (approximately 75% accuracy) with the MODIS-based change detection technique. The resulting change information offers potential to identify areas that have been burned or extensively logged, and provides general information on those areas that have experienced greater change and are likely suitable for analysis with higher spatial resolution data.
52

Finns det ett positivt samband mellan svenska börsbolags utdelningsandel och deras resultattillväxt? : En kvantitativ studie på Sveriges största börsbolag

Blomqvist, Daniel, Jonsson, Gustaf January 2012 (has links)
Problembakgrund och problemdiskussion: Företagens utdelningar är av intresse för investerare ur ett flertal synvinklar. De ger aktieägaren en direktavkastning på investerat kapital, men beskrivs också kunna förklara ett företags framtida prestationer. För de teorier som presenterats inom det företagsekonomiska området finns de som förespråkar både positiva och negativa samband kring utdelningars effekt på företagets resultattillväxt. De senaste åren har nya empiriska studier som visar på motsatta samband presenterats. Tidigare studier tillsammans med att forskning ej hittats för den svenska marknaden har ökat författarnas intresse kring det samband som resulterat i följande problemformulering. Problemformulering: Finns det ett positivt samband mellan svenska börsbolags utdelningsandel och deras resultattillväxt? Syfte: Studiens syfte är att förklara om det finns ett positivt samband mellan utdelningsandel och framtida tillväxt i resultat för urvalet av svenska företag listade vid Large Cap på Nasdaq OMX Stockholm vid utförandet av studien, våren 2012. Studien inkluderar även ett motsvarande test av aggregerade värden för Sveriges 70 mest omsatta aktier, i indexet Thomson Reuters Country Index Sverige. Dessa resultat jämförs därefter med varandra för att stärka ett samband som förväntas vara positivt och är direkt relaterad till studiens problemformulering. Teori: Tidigare empirisk forskning som grundar sig i resultaten av Arnott och Asness (2003) och efterföljande forskning inom ämnet har denna studie, i mån av kunskap och tidshorisont, försökt replikera. Tillsammans utgår studierna från teorier av Lintner (1956) om företagens optimala utdelningsandel, Modigliani &amp; Miller (1961) med teorin om utdelningars irrelevans och Gordons (1962) teori om företagsvärdering givet konstant tillväxttakt. Slutligen Myers (1984) Pecking Order theory om finansieringsalternativ. Metod: Studiens genomförs med en kvantitativ metod. Undersökningsperioden är 1983 till 2010, med tidsperioder om ett-, tre- och fem år, för vilka företag i urvalet, Large Cap, ur populationen Nasdaq OMX Stockholm. Den statistiska undersökningen har genomfört med en multilinjär regressionsmodell för vilka oberoende variabler undersökt förhållandet till dem beroende variabeln, resultattillväxt. Empiri, Analys &amp; Slutsats: Resultatet visar ett positivt samband mellan utdelningsandel och resultattillväxt för de noterade företagen på Large Cap, 2012. Studiens resultat har tydliga likheter med de utfall som tidigare empirisk forskning presenterat och likaså det positiva samband som återfinns för variablerna utdelningsandel och resultattillväxt. För den svenska marknaden kan huvudhypotesen bekräftas och därmed ett positivt förhållande som besvarar studiens problemformulering för tidshorisonten 1983-2010.
53

Assessment of the impact of large CRTs and flat panel monitors on productivity and quality in an insurance company

Johnson, Michael Federico 12 April 2006 (has links)
This field study evaluates the impact of replacing existing 17-inch Cathode Ray Tube (CRT) monitors with 19 and 21-inch CRT monitors and 18.1-inch Flat Panel Displays (FPDs) on matrices of productivity, visual comfort, and physical discomfort among 30 employees within a large insurance company (Policy Service and Claims). Metrics were analyzed over a five (5) month period. During Phase One (initial eight weeks) of the study, metrics were gathered weekly on 17-inch CRT monitors to establish a baseline of data on productivity, visual comfort and physical discomfort. During Phase Two (12 weeks), each subject used the 19-inch CRT, 21-inch CRT and 18.1-inch FPD for two weeks, respectively interspersed with other subjects in the study utilizing 17-inch monitors for the same time period. Initially, it appears that the 19-inch monitor enables users to enter more keystrokes per hour ( x19 =1894) than its 17-inch counterpart ( x17=1721) which would be a productivity enhancement. However, this value is not statistically significant (p>0.34). Analysis of additional performance metrics yielded similar results (p>0.2). The users’ level of visual comfort increased with all test display units over their existing 17-inch counterpart (p<0.023), but the data was not meaningful due to the minute difference between their mean values (&#8710;<0.75). Physical discomfort metrics were analyzed among all of the monitor treatments. Most employees were relatively comfortable through the duration of the study. Mean values across all physical discomfort metrics measured were less than one on a Borg scale of zero to ten, but none of the values among treatments were significant (p>0.31). Anecdotally, the users preferred the larger monitors.
54

Suggestions for dealership development to suit needs of a new kind of John Deere customer: a study of

Pospeshnova, Maria Alexandrovna 16 August 2006 (has links)
The purpose of this study was to identify a new group of customers of agricultural machinery manufacturers and these customers’ needs and suggestions. The study also sought to offer suggestions to the John Deere Company for dealership education and development programs for John Deere dealerships. The following objectives were used to guide the study: 1) To describe demographics of “large property owners,” 2) To describe “large property owners’” needs and wants for the farm equipment dealership, and 3) To generate suggestions for dealership development to suit the needs of “large property owners.” The need for the study was identified by the John Deere Company to learn more about a new growing market and to prepare the dealerships for adoption of the change. The sampling frame consisted of “large property owners” whose names were randomly selected from county tax rolls of six selected counties in the Dallas/Fort Worth metroplex area. A mailed instrument was sent to a sample of 1,000 potential participants. Respondents totaled 205, with 174 instruments usable as they were complete or nearly complete. The study revealed important facts about “large property owners,” which were considered while creating a list of recommendations for the John Deere Company. Before “large property owners’” needs could be examined, the John Deere dealerships had to be considered. Two kinds of dealerships can present agricultural equipment of different powers at two different locations: agricultural equipment dealerships and Commercial and Consumer Equipment (C&CE) dealerships. Presenting equipment in two different locations may not suit small farmers’ needs or their desire for convenience. “Large property owners’” needs in a wider range of equipment at one dealership location, more convenient locations, and other characteristics were examined.
55

Epidemic modelling : SIRS models /

Dolgoarshinnykh, Regina G. January 2003 (has links)
Thesis (Ph. D.)--University of Chicago, Department of Statistics, August 2003. / Includes bibliographical references. Also available on the Internet.
56

The role of language and culture in large-scale assessment : a study of the 2009 Texas Assessment of Knowledge and Skills

Lima Gonzalez, Cynthia Esperanza 09 September 2013 (has links)
The inclusion of all students in large-scale assessment mandated by the No Child Left Behind (2003) requires that these large-scale assessments be developed to allow all students to show what they know, and that the results are comparable and equitable across diverse cultural and linguistic populations. This study examined the validity of the 5th grade 2009 Science Texas Assessment of Knowledge and Skills (TAKS) for diverse cultural and linguistic groups. The student groups considered for this study were selected based on all the possible combinations of three variables: ethnicity--White and Hispanic, test language--English and Spanish, and Limited English Proficiency (LEP) classification. Validity was assessed at the item and construct levels, and was analyzed from a psychometric, cultural and linguistic stance. At the item level, Differential Item Function (DIF) was conducted using the Mantel-Haenszel procedure. The presence of biased items was revealed for all pairwise group comparisons; with a high number of DIF items between groups which differed in English proficiency (approximately 50% of the test items), and a low number of DIF items between groups which only differ in ethnicity (approximately 15% of the test items). However, an analysis of the Item Characteristic Curves (ICCs), revealed that items classified by the Mantel-Haenszel procedure as advantaging the LEP groups, did so for students at low proficiency levels; while the advantage at high proficiency levels was for non-LEP groups. At the construct level, the structure of the English version of the TAKS was compared across three student groups using Confirmatory Factor Analysis with Multiple Groups. The hypothesized structure based on the TAKS blueprint, was rejected for the Group conformed by White, non-LEP students (MLM[subscript x]²[subscript(734)] = 1042.110; CFI= 0.845; RMSEA= 0.020); but, it was a good fit for Hispanic, non-LEP (MLM[subscript x]²[subscript(734)] = 819.356; CFI= 0.980; RMSEA= 0.011) and LEP (MLM[subscript x]²[subscript(734)] = 805.124; CFI= 0.985; RMSEA= 0.010) Groups. The results obtained from this study call to reinterpret the achievement gap observed in TAKS scores between the populations considered, and highlight the need for further development of guidelines that can better help to develop fair large-scale tests for all students. / text
57

Measuring the Universe with High-Precision Large-Scale Structure

Mehta, Kushal Tushar January 2014 (has links)
Baryon acoustic oscillations (BAOs) are used to obtain precision measurements of cosmological parameters from large-scale surveys. While robust against most systematics, there are certain theoretical uncertainties that can affect BAO and galaxy clustering measurements. In this thesis I use data from the Sloan Digital Sky Survey (SDSS) to measure cosmological parameters and use N-body and smoothed-particle hydrodynamic (SPH) simulations to measure the effect of theoretical uncertainties by using halo occupation distributions (HODs). I investigate the effect of galaxy bias on BAO measurements by creating mock galaxy catalogs from large N -body simulations at z = 1. I find that there is no additional shift in the acoustic scale (0.10% ± 0.10%) for the less biased HODs (b < 3) and a mild shift (0.79% ± 0.31%) for the highly biased HODs (b > 3). I present the methodology and implementation of the simple one-step reconstruction technique introduced by Eisenstein et al. (2007) to biased tracers in N-body simulation. Reconstruction reduces the errorbars on the acoustic scale measurement by a factor of 1.5 - 2, and removes any additional shift due to galaxy bias for all HODs (0.07% ± 0.15%). Padmanabhan et al. (2012) and Xu et al. (2012) use this reconstruction technique in the SDSS DR7 data to measure Dᵥ(z = 0.35)(rᶠⁱᵈs/rs) = 1356 ± 25 Mpc. Here I use this measurement in combination with measurements from the cosmic microwave background and the supernovae legacy survey to measure various cosmological parameters. I find the data consistent with the ΛCDM Universe with a flat geometry. In particular, I measure H₀ = 69.8 ± 1.2 km/s/Mpc, w = 0.97 ± 0.17, Ωk = -0.004 ± 0.005 in the ΛCDM, wCDM, and oCDM models respectively. Next, I measure the effect of large-scale (5 Mpc) halo environment density on the HOD by using an SPH simulation at z = 0, 0.35, 0.5, 0.75, 1.0. I do not find any significant dependence of the HOD on the halo environment density for different galaxy mass thresholds, red and blue galaxies, and at different redshifts. I use the MultiDark N-body simualtion to measure the possible effect of environment density on the galaxy correlation function ℰ(r). I find that environment density enhances ℰ(r) by ∽ 3% at scales of 1 – 20h⁻¹Mpc at z = 0 and up to ∽ 12% at 0.3h⁻¹Mpc and ∽ 8% at 1 - 4h⁻¹Mpc for z = 1.
58

Lacome: a cross-platform multi-user collaboration system for a shared large display

Liu, Zhangbo 05 1900 (has links)
Lacome is a multi-user cross-platform system that supports collaboration in a shared large screen display environment. Lacome allows users to share their desktops or application windows using any standard VNC server. It supports multi-user concurrent interaction on the public shared display as well as input redirection so users can control each other's applications. La-come supports separate types of interaction through a Lacome client for window management tasks on the shared display(move, resize, iconify, de-iconify) and for application interactions through the VNC servers. The system architecture provides for Publishers that share information and Navigators that access information. A Lacome client can have either or both, and can initiate additional Publishers on other VNC servers that may not be Lacome clients. Explicit access control policies on both the server side the client side provide a flexible framework for sharing. The architecture builds on standard cross-platform components such as VNC and JRE. Interaction techniques used in the window manager ensure simple and transparent multi-user interactions for managing the shared display space. We illustrate the design and implementation of Lacome and provide insights from initial user experience with the system.
59

Development and implementation of robust large deformation and contact mechanics capabilities in process modelling of composites

Osooly, Amir 05 1900 (has links)
Autoclave processing of large scale, one-piece structural parts made of carbon fiber-reinforced polymer composite materials is the key to decreasing manufacturing costs while at the same time increasing quality. Nonetheless, even in manufacturing simple flat parts, residual strains and stresses are unavoidable. For structural design purposes and to aid in the assembly procedures, it is desirable to have proven numerical tools that can be used to predict these residual geometrical and material properties in advance, thus avoid the costly experimental trial and error methods. A 2-D finite element-based code, COMPRO, has previously been developed in-house for predicting autoclave process-induced deformations and residual stresses in composite parts undergoing an entire cure cycle. To simulate the tool-part interaction, an important source of residual deformations/stresses, COMPRO used a non-zero thickness elastic shear layer as its only interface option. Moreover, the code did not account for the large deformations and strains and the resulting nonlinear effects that can arise during the early stages of the cure cycle when the material is rather compliant. In the present work, a contact surface employing a penalty method formulation is introduced at the tool-part interface. Its material-dependent parameters are a function of temperature, degree of cure, pressure and so forth. This makes the stick-slip condition plus separation between the part and the tool possible. The large displacements/rotations and large shear strains that develop at the early stages of the cure cycle when the resin has a very low elastic modulus provided the impetus to include a large strain/deformation option in COMPRO. A new “co-rotational stress formulation” was developed and found to provide a robust method for numerical treatment of very large deformation/strain problems involving anisotropic materials of interest here. Several verification and validation examples are used to calibrate the contact interface parameters and to demonstrate the correctness of implementation and the accuracy of the proposed method. A number of comparisons are made with exact solutions, other methods, other experiments and the same models in other commercial codes. Finally, several interesting cases are examined to explore the results of COMPRO predictions with the added options.
60

Ecology, behavior, and biological characteristics of juvenile lake sturgeon, Acipenser fulvescens, within an impounded reach of the Winnipeg River, Manitoba, Canada

Barth, Cameron Charles 31 August 2011 (has links)
The lake sturgeon, Acipenser fulvescens, was once abundant throughout Canada and the United States, however, high commercial harvests and habitat alterations have dramatically reduced most populations. The species was extirpated from many rivers that it once inhabited, and has been designated as threatened or endangered throughout its range. Currently, few healthy lake sturgeon populations remain and the species is receiving considerable attention with respect to its protection and recovery. Although considerable effort is underway to conserve the species, several factors, including over-harvest and habitat alteration, pollution and a general lack of understanding about lake sturgeon ecology and behavior continue to hamper recovery efforts. This thesis examined the ecology and behavior of juvenile lake sturgeon within a 41 km long impounded section of the Winnipeg River, a large river in the Canadian Shield, over a three-year period (2006 – 2008). Habitat preferences, species associations, diet, and movement were described on a seasonal basis. Biological characteristics were also described for juvenile lake sturgeon within the study area. Studies presented in this thesis are among the first conducted for juveniles of this species in the Hudson Bay drainage basin, and from large riverine environments in general. Results are important, not only for improving our understanding of lake sturgeon at the juvenile life history stage, but for facilitating further research. In particular, future research studies identified in the final chapter have the potential to enhance our understanding of factors influencing mortality during the early life history stages of the lake sturgeon, and therefore, greatly enhance recovery efforts.

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