7,945 research outputs found

    On Electrical Equivalence of Aperture-Body and Transmission-Cavity Resonance Phenomena in Subwavelength Conducting Aperture Systems from an Equivalent Circuit Point of View

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    For a narrow slit structure backed by a conducting strip which is taken as a representative example of an aperture-body resonance (ABR) problem, the transmission resonance condition (i.e., condition for maximum power transmission) and the transmission width (i.e., normalized maximum transmitted power through the slit) are found to be the same as those for narrow slit coupling problem in a thick conducting screen, which is designated as a transmission-cavity resonance (TCR) problem. From a viewpoint of equivalent circuit representation for the transmission resonance condition and the funneling mechanism, the ABR and the TCR problems are thought to be essentially of the same nature.Comment: 14 pages, 3 figure

    The Forecasting Ability of Money Market Fund Managers and its Economic Value

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    The model proposed by Merton(1981) to determine the value of forecasting ability is adapted to investigate whether money market fund managers successfully anticipate changes in the yield curve by adjusting the average maturity of their portfolios in the right direction. The potential economic value of such behavior is assessed, and it is shown that if the portfolios of all money market funds were aggregated it would appear that managers are good forecasters even if individually they possess insignifcant forecasting ability. At the same time, the economic value of the aggregate portfolio will be diminished because of the reduced net change in average maturity. Thus, diversifying into many money market funds will not attain the gain that could be realized if an individual manager had a forecasting ability equal to the quality of the average forecast.A sample of 34 money market funds is investigated. Analysis suggests that a small fraction of the funds exhibited forecasting skills, but even they generated negligible economic value because the changes in their portfolios average maturity were too small.There appears to be no relationship between forecasting ability and economic success of money market funds as measured by asset size and growth.

    A Cultural Perspective on Motivation Factors Affecting Exhibition Participation

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    With increasing global competitions, more opportunities transcending national boundaries may exist for the exhibition organizers and participants. This study offered an integrated approach to understanding how various motivation factors affect the participation in exhibition. The literature review included an introduction of push/pull motivation theories as one of the most representative motivation theories. The factor analysis of survey results supported the categorization of push/pull factors in exhibition industry. The paper concluded that the factor analysis procedures yielded the motivation factor dimensions with similar natures and four underlined motivation dimensions of exhibition participation were labeled. Furthermore, the cultural difference between Western and Eastern participants was examined to employ differentiated strategies in promoting exhibitions

    Development of a generalised compositional multiphase model for flow and transport in porous media

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    PhD ThesisFresh water is one of the most important natural resources. However, like other natural resources, the usable water is limited while the demand for water increases as industrialization proceeds and the population grows. What makes matters worse is that water resources are being reduced by pollution. Groundwater is an important water resource. However, in many countries, it has not been fully developed yet, either because of sufficient surface water sources, technical problems, or geographical conditions. Generally groundwater is relatively clean and is better protected from pollutants than surface water. Thus groundwater is an important subject for water engineers and scientists who have focused on its development and protection. In both cases, research into the movement of pollutants plays an important role in the effective exploitation of groundwater. Recently hydrologists concerned with groundwater pollution have studied multiphase flows in the subsurface because many pollution problems are characterized by multiphase contamination. The simplest multiphase pollution problem is solute transport in the unsaturated zone. More complex multiphase pollution problems involve organic matter such as petroleum products discharged to use oil. Since many of organic products are essential to our normal life and industry, the potential for groundwater pollution by them is significant unless they are controlled properly. In multiphase problems, the organic compounds may form their own flows that are distinct from the subsurface water flow but partly dissolve with the water phase and cause low concentration long term pollution of the water phase. There have been many efforts dedicated to predicting the movement of pollutants. A lot of mathematical and numerical models have been developed with the aid of laboratory and field works. However almost all models have been developed to solve a few restricted scenarios. Model users are obliged to invest considerable time in understanding the various models; their numerical accuracy and coding.The purpose of this study is to categorize the pollution patterns in the subsurface and to develop a numerical model that can be applicable to a wide variety of subsurface contamination. The general primary variables and generalizing procedures are employed to make the numerical model applicable to various pollution patterns. Many kinds of tracers can be used to know the behaviors of fluid phases in the subsurface. Because the model is able to describe partitioning of mass of a component among fluid phases, tracer problems also can be simulated by the model

    Earnings and Dividend Announcements is there a Corroboration Effect?

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    We examine abnormal stock returns surrounding contemporaneous earnings and dividend announcements in order to determine whether investors evaluate the two announcements in relation to each other.We find that there is a statistically significant interaction effect.The abnormal return corresponding to any earnings or dividend announcement depends upon the value of the other announcement. This evidence suggests the existence of a corroborative relationship between the two announcements. Investors give more credence to unanticipated dividend increases or decreases when earnings are also above or below expectations, and vice versa.

    Applying Statistical Post-Editing to English-to-Korean Rule-based Machine Translation System

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