• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1941
  • 582
  • 218
  • 207
  • 182
  • 164
  • 70
  • 55
  • 49
  • 39
  • 38
  • 31
  • 19
  • 15
  • 12
  • Tagged with
  • 4431
  • 561
  • 459
  • 319
  • 315
  • 294
  • 286
  • 265
  • 204
  • 198
  • 198
  • 187
  • 179
  • 169
  • 167
  • 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.
111

Size Effect in the Electrical Conductivity of Bismuth

Vaughn, Bobby J. 08 1900 (has links)
If a physical dimension of a metallic specimen is comparable with, or smaller than, the mean free path of the conduction electrons, then the observed electrical conductivity will be less than that of a conventional bulk sample. This phenomenon is called a size effect, and is the result of electron scattering from the specimen surfaces. In the present investigation, measurements were made on electropolished monocrystalline specimens ranging from matchbox geometry to thick-film geometry in order to obtain further information on the size effect in bismuth at liquid helium temperatures.
112

CONSERVATION GENETICS OF PADDLEFISH: GENETIC EFFECTIVE POPULATION SIZE AND RANGEWIDE GENETIC STRUCTURE

Asher, Allison Marie 01 May 2019 (has links)
Paddlefish (Polyodon spathula) is a commercially and recreationally important species, with a native range that extends over 22 US states. This is a large, long-lived, highly mobile riverine species that has been negatively impacted by habitat fragmentation, historic overharvest, and hatchery supplementation. Dams are the primary cause of habitat fragmentation, blocking migration routes, flooding spawning grounds, and isolating populations. A common management action to mitigate the impacts of habitat fragmentation and maintain harvestable populations is hatchery propagation and stocking. Reduction in stock size, isolation of populations, and stocking can all negatively impact the genetic integrity of Paddlefish. I evaluated the impacts of isolation and hatchery supplementation on the effective population size (Ne) of Paddlefish as well as the range-wide genetic structure of Paddlefish.
113

Sample Size Determination in Auditing Accounts Receivable Using a Zero-Inflated Poisson Model

Pedersen, Kristen E 28 April 2010 (has links)
In the practice of auditing, a sample of accounts is chosen to verify if the accounts are materially misstated, as opposed to auditing all accounts; it would be too expensive to audit all acounts. This paper seeks to find a method for choosing a sample size of accounts that will give a more accurate estimate than the current methods for sample size determination that are currently being used. A review of methods to determine sample size will be investigated under both the frequentist and Bayesian settings, and then our method using the Zero-Inflated Poisson (ZIP) model will be introduced which explicitly considers zero versus non-zero errors. This model is favorable due to the excess zeros that are present in auditing data which the standard Poisson model does not account for, and this could easily be extended to data similar to accounting populations.
114

A comparison of some lot-sizing heuristic rules independent of EOQ-assumptions.

January 1986 (has links)
by Siu Wai-man, Raymond. / Bibliography: leaves 75-76 / Thesis (M.B.A.)--Chinese University of Hong Kong, 1986
115

The size distribution of plants and economic development

Bhattacharya, Dhritiman 01 July 2010 (has links)
The plant size distribution differs systematically across developed and developing countries. For example, in developing countries, less than one fifth of 1% of plants are large (employ 100 or more employees) and account for about one fifth of total employment. In sharp contrast, in developed countries, more than 1.6% of plants are large and account for more than two fifth of total employment. In this dissertation, I develop a model of plant size to account for the differences in the plant size distribution observed in the data. In the first chapter, I explore the link between plant size distribution and economic development. I also discuss the main features of the plant size distribution data. The purpose of this data set is to provide evidence of systematic differences in plant size distribution across developed and developing countries. In the second chapter, I present a dynamic employment choice model in a life cycle setting. Then I calibrate the benchmark model to match some key features of the U.S. plant size distribution. I find that my model can capture the critical features of U.S. plant size distribution, including the upper tail which accounts for the bulk of the employment and output in the U.S. economy. In the third chapter, I explore how exogenous differences in aggregate barriers to investment and technology across countries affect the plant size distribution. Results indicate that exogenous differences in aggregate barriers to investment and technology across countries can account for more than 50% of the variation in both the fraction of large plants and employment share in large plants across countries. For the same group of countries, exogenous differences in aggregate barriers also account for 36% of the variation in the mean size.
116

Particles in the eastern Pacific ocean : their distribution and effect upon optical parameters

Carder, Kendall L. 30 September 1969 (has links)
The distribution of particles in the Eastern Pacific Ocean was investigated from 2 January to 14 February, l969, on the YALOC-69 cruise of Oregon State University. The size distributions were well fitted by the two-parameter Weibull distribution function, with a predominant number of them nearly exponential in distributional shape. Although particles smaller in diameter than 1i could not be measured, extrapolation of the Weibull distribution into the small particle range indicated the median particle diameter was smaller than 1μ. Measurements of light scattering were taken simultaneously with the particle size determinations. A linear relationship between the total particulate surface area and the volume scattering function, β(45°) was indicated, as well as between β(45°)/β(135°) and the mean particle diameter of distributions sharing a common shape parameter. Five different characteristic distributional shapes were found which typified all but a few of the distributions. No direct relationship was found between the distributional shapes and the water types encountered on the cruise. The first-order exponential shapes of the size distributions suggest that a detrital decay mechanism of the larger particles (i. e. phytoplankton) could be a dominant factor in determining the small particle end of oceanic particle distributions. / Graduation date: 1970
117

Formation of secondary organic particulate matter by reactions of gas phase organic compounds with aerosol particles /

Zhang, Jin. January 2004 (has links)
Thesis (M.Sc.)--York University, 2004. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 117-120). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL:http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss&rft%5Fval%5Ffmt=info:ofi/fmt:kev:mtx:dissertation&rft%5Fdat=xri:pqdiss:MQ99407
118

Partiformning och beläggning av artiklar i produktionssystem

Bornholm, Martin, Samuelsson, Gustaf, Pavic, Robert January 2012 (has links)
Sammanfattning På grund av ökad konkurrens måste företag öka sin konkurrenskraft. Ett sätt för företag att öka sin konkurrenskraft är att utnyttja de resurser de besitter på ett mer effektivt sätt. Hur ett producerande företag styr sin produktion påverkar hur effektivt de utnyttjar sitt produktionssystem, lager och personal. Ett företag kan styra sin produktion genom att välja hur de partiformar och belägger de artiklar som utnyttjar ett produktionssystem.  Syftet med det här arbetet är att öka förståelsen för hur en modell för partiformning och beläggning av artiklar med varierande efterfrågan i ett produktionssystem där kapacitetsbrist råder kan se ut. Arbetet är en fallstudie där partiformning och beläggning av artiklar i ett produktionssystem analyseras. Kvalitativ forskning har bedrivits för att nå en djup förståelse för problemet. I arbetet beskrivs teorier om flöden, planering, partiformning och beläggning. Empirisk data som nämns i arbetet är beskrivningar av fallstudiens produktionssystem, de artiklar som produceras i systemet och planeringsprocessen företaget i fallstudien använder vid partiformning och beläggning. I analysen undersöks hur väl olika teorier passar för planering, partiformning och beläggning av fallstudiens produktionssystem. Genom en allmän diskussion om hur de beskrivna teorierna påverkar ett produktionssystems förmåga att ta tillvara på begränsad kapacitet och hantera varierande efterfrågan av artiklar nås en ökad förståelse för hur en modell kan se ut. De slutsatser som dras i arbetet är att partiformning och beläggning som sker för att optimera flödet kan öka effektiviteten i resursutnyttjandet. Ett sätt att optimera flödet är att belägga den resurs som anses vara kritisk först, beläggningen av den kritiska resursen styr därefter beläggningen av övriga produktionssystemet. Fler slutsatser som dras i arbetet är att en modell för partiformning och beläggning av artiklar med varierande efterfrågan i ett produktionssystem där kapacitetsbrist råder bör vara dynamisk. För att skapa en dynamisk modell kan beläggning och partiformning ske parallellt, det vill säga att partistorleken för en artikel påverkar beläggningen av en resurs, vilket i sin tur bör påverka partistorleken för resterande artiklar.
119

The effect of stock repurchase on market liquidity ¡V Empirical evidence from Taiwanese listed firms

Li, Chung-ho 02 June 2010 (has links)
¡@¡@Treasury stock system allows listed companies to buy back their own shares in the open market. In general, when the company announced stock repurchase event, investors are optimistic about the prospects of the company. Therefore, the company's stock price usually rises. But will investors buy more stocks, leading to increased liquidity of stocks? This study combines with stock repurchase and liquidity to investigate the impact of stock repurchase on liquidity. Further events will be studied by different factors stratified, including firm size, stock price, industry, the purpose of stock repurchase, the proportion of execution, the holding ratio of insiders and institutional investors. By using three types of liquidity measures, the study is to observe the changes of liquidity of stocks in the different situations. ¡@¡@After conducting mean difference in pair-sample test, the empirical results indicate that the sample stocks in the stock repurchase announcement, the outcome supports liquidity increase hypothesis. In terms of the stratification factors, the smaller of the company size or lower stock price will help increase the liquidity of the stock in the market. Non-electronics sector, aims to buy back equity write-off shares can improve market liquidity. Higher or lower percentage of insider ownership shares in¡@companies will lead to the increase of stock liquidity. Higher holding shares proportion of institutional investor in companies will increase liquidity. The amount of execution ratio is of no factors, but the liquidity of the stock repurchase still supports the liquidity increase hypothesis.
120

Study on Wave Field with Caisson on Multiple Porous Layers

Chou, Chun-ting 07 September 2010 (has links)
In the study, wave reflection, transmission, and energy dissipation with a caisson-type breakwater have been investigated experimentally. Three different sizes of grain are used to construct the porous base, they are 16mm, 25mm, and 35mm, respectively.Single and double layers of porous base are considered. Hydraulic test, porous media choice is glass ball.Wave conditions must be consistent with the scope of the linear wave theory. Two different depths are used to construct,they are 40 cm and 72 cm. Do a single trial of all size. Double size 16mm and 35mm diameter glass ball is a test. Recording the test process, and then analyze energy consumption. Water area's characteristics and pore area's characteristics are calculated by the Newton¡¦s method and the Ward¡¦s method. It is the substitute for the dispersion equation is also correct. During the course of a series, the draft of caisson is deeper, the convergence is harder. But the increase and decrease the mode number or the draft, and sometimes increase the possible of convergence. As the number of cutting layer are more complex than other predecessors, particularly in the large number of required mode, when the composition of the matrix of boundary conditions greater complexity. In the caisson area calculated pore velocity, or on behalf of the later is very large, so it's easy in the solution process, generate positive infinity or negative infinity error. As the caisson-type breakwater with a shorter wavelength, the frictional resistance influences bigger. At this time, reflectance and transmittance has the Drop tendency.When the wavelength is longer, the frictional resistance influences smaller. Most of the energy reflection because the caisson of less permeable. The caisson-type breakwater got the wave force to increase. The effect is bad in the Wave force reduced. If the static water surface above the pore structure, the caisson-type breakwater can be reduction of about 30% to 40% off the energy. If the static water surface under the pore structure, the caisson-type breakwater wave damping efficiency is better. Usually remove 30% to 70% energy. Sometimes, it¡¦s up to about 90%.Reflectivity of the caisson breakwater is larger, but the transmissivity is lower. For the waters behind the breakwater, the protective effect is significant. Transmissivity trend is arranged according to media size. As the media size smaller, the transmissivity is smaller, the reflectivity is higher. At the same depth, double-size model compared with other single-size model of the wave forces reduced is better. Whether long or short period, double-size model's performance is relatively stable. Except to a long cycle time, the wave damping efficiency has a larger range. Other cycles are at the lower position.

Page generated in 0.0338 seconds