859 research outputs found

    The electron temperature of the inner halo of the Planetary Nebula NGC 6543

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    We investigate the electron temperature of the inner halo and nebular core regions of NGC 6543, using archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) images taken through narrow band [O III] filters. Balick et al. (2001) showed that the inner halo consists of a number of spherical shells. We find the temperature of this inner halo to be much higher (~15000 K) than that of the bright core nebula (~8500 K). Photo-ionization models indicate that hardening of the UV radiation from the central star cannot be the main source of the higher temperature in the halo region. Using a radiation hydrodynamic simulation, we show that mass loss and velocity variations in the AGB wind can explain the observed shells, as well as the higher electron temperature.Comment: 9 pages, 6 figures, to be published in A&

    Spatial map for thermal image processing at Wendelstein 7-X

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    Wendelstein 7-X is a Stellator fusion reactor prototype. Many experiments are currently being performed obtaining data from cameras located at different points of the reactor. In this project, image processing is applied to treat these data in order to analyze the behavior of the plasma and the temperature at each instant. Using the captured images, we study the physical reactor surface covered by every pixel so as to achieve which elements are overheating or to detect anomalies.Wendelstein 7-X es un prototipo de reactor de fusión Stellator. Actualmente se realizan experimentos en los que se obtienen datos a partir de cámaras situadas en diferentes puntos del reactor. En este proyecto se tratan estos datos aplicando conocimientos de procesamiento de imagen para obtener características que sirvan para analizar el comportamiento del plasma y la temperatura en cada instante. Utilizando las imágenes capturadas, se estudia cuál es la superfície física del reactor cubierta por el campo visual de cada pixel. De esta manera se puede saber qué elementos se están tratando para en un futuro saber si se están sobrecalentando o poder estudiar otro tipo de comportamientos.Wendelstein 7-X és un prototip de reactor de fusió Stellator. Actualment es realitzen experiments en els quals s'obtenen moltes dades a partir de càmeres situades a diferents punts del reactor. En aquest projecte es tracten aquestes dades aplicant coneixements de processament d'imatge per tal d'obtenir característiques que serveixin per analitzar el comportament del plasma i la temperatura en cada instant. D'aquesta manera, utilitzant les imatges capturades, es calcula quina superfície física del reactor és visualitzada pel camp visual de cada píxel i així poder saber quins elements del reactor s'estan tractant per veure en el futur si s'estan sobreescalfant o poder estudiar altres tipus de comportament

    A Comparative Analysis of International and Chinese Electronic Commerce Research

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    Due to the growth of the Internet and e-commerce, both practitioners and researchers are in the midst of a social, business and culture revolution. Internet and e-commerce related research has been developed and grown up by United States, but China has become one of the most exciting research areas. This literature review consists of 1044 journal articles published between 1993 and 2003 in fourteen International and Chinese journals. The articles are classified by a scheme that consists of four main categories: application areas, technological issues, support and implementation and others. Based on the classification and analysis of e-commerce related researches, we present the current state of International and Chinese research and discuss the differences between them

    X-Ray Diffraction (XRD) Characterization Methods for Sigma=3 Twin Defects in Cubic Semiconductor (100) Wafers

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    An X-ray defraction (XRD) characterization method for sigma=3 twin defects in cubic semiconductor (100) wafers includes a concentration measurement method and a wafer mapping method for any cubic tetrahedral semiconductor wafers including GaAs (100) wafers and Si (100) wafers. The methods use the cubic semiconductor's (004) pole figure in order to detect sigma=3/{111} twin defects. The XRD methods are applicable to any (100) wafers of tetrahedral cubic semiconductors in the diamond structure (Si, Ge, C) and cubic zinc-blend structure (InP, InGaAs, CdTe, ZnSe, and so on) with various growth methods such as Liquid Encapsulated Czochralski (LEC) growth, Molecular Beam Epitaxy (MBE), Organometallic Vapor Phase Epitaxy (OMVPE), Czochralski growth and Metal Organic Chemical Vapor Deposition (MOCVD) growth

    The Socialist Camp’s North Korean Medical Support and Exchange (1945-1958): Between Learning from the Soviet Union and Independent Course

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    This study focused on the socialist camp’s North Korean medical support and its effects on North Korean medical field from liberation to 1958. Except for the Soviet assistance from liberation to the Korean War, existing studies mainly have paid attention to the ‘autonomous’ growth of the North Korean medical field. The studies on the medical support of the Eastern European countries during the Korean War have only focused on one-sided support and neglected the interactions with the North Korean medical field. Failing in utilizing the materials produced in North Korea has led to the omission of detailed circumstances of providing support. Since the review of China’s support and the North Korea-China medical exchanges has been concentrated in the period after the mid-1950s, the impacts of China’s medical support on North Korea during the Korean War period and the post-war recovery period have not been taken into account. In terms of these limitations, this study examined the medical activities by the Socialist camp of the Eastern European countries in North Korea after the Korean War. The medical aid teams from Hungary, Romania, Bulgaria, Czechoslovakia, Poland, and East Germany that came to North Korea in the wake of the Korean War continued to stay in North Korea after the war to build hospitals and train medical personnel. In the hospitals operated by these countries, cooperative medical care with North Korean medical personnel and medical technology education were conducted. Moreover, medical teams from each country in North Korea held seminars and conferences and exchanged knowledge with the North Korean medical field staffs. These activities by the Socialist countries in North Korea provided the North Korean medical personnel with the opportunity to directly experience the medical technology of each country. China’s support was crucial to North Korea’s ‘rediscovery’ of Korean medicine in the mid-1950s. After the Korean War, North Korea began to apply the Chinese-Western medicine integration policy, which was performed in China at that time, to the North Korean health care field through China’s medical support and exchanges. In other words, China’s emphasis on Chinese medicine and the integration of the Chinese-Western medicine were presented as one of the directions for medical development of North Korea in the 1950s, and the experiences of China in this process convinced North Korea that Korean medicine policy was appropriate. The decision-makers of the North Korean medical policies, who returned to North Korea after studying abroad in China at that time, actively introduced the experiences from China and constantly sought to learn about them. This study identified that a variety of external stimuli had complex impacts on the North Korean medical field in the gap between ‘Soviet learning’ in the late 1940s and the ‘autonomous’ medical development since the 1960s. The North Korean medical field was formed not by the unilateral or dominant influences of a single nation but by the stimulation from many nations and the various interactions in the process

    Use of Blended Learning for Effective Implementation of English-medium Instruction in a Non-English Higher Education Context

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    Although researchers agree with the strengths of an English-medium instruction (EMI) in addressing internationalization of a non-English higher education (HE) context, its implementation in classrooms has been widely criticized, mostly because of ineffective delivery of course content and a lack of evidence of English improvement. Grounded upon a critical review of the current state of internationalization of Korean HE and the subsequent examination of supplementary interview data from 15 college students who have taken EMI courses, this study proposes a model which integrates critical factors of EMI into one framework. This model aims at guiding the EMI policy from initiation to implementation. A major feature of this model is blended learning as a strategy to address the shortcomings of current EMI in this context and to facilitate the allocation of diverse online materials to scaffold EMI instruction. The benefits of the approach are presented from the perspectives both of policy-makers and of classroom participants.clos

    Transparent actuator made with few layer graphene electrode and dielectric elastomer, for variable focus lens

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    A transparent dielectric elastomer actuator driven by few-layer-graphene (FLG) electrode was experimentally investigated. The electrodes were made of graphene, which was dispersed inN-methyl-pyrrolidone. The transparent actuator was fabricated from developed FLG electrodes.The FLG electrode with its sheet resistance of 0.45 kΩ/sq (80 nm thick) was implemented to mask silicone elastomer. The developed FLG-driven actuator exhibited an optical transparency of over 57% at a wavenumber of 600 nm and produced bending displacement performance ranging from 29 to 946 μm as functions of frequency and voltage. The focus variation was clearly demonstrated under actuation to study its application-feasibility in variable focus lens and various opto-electro-mechanical devices

    Direct measurement of mechanical vibrations of the 4-rod RFQ at the HLI

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    In this paper, we present a new haptic interface, called active skin , which is configured with a tactile sensor and a tactile stimulator in single haptic cell, and multiple haptic cells are embedded in a dielectric elastomer. The active skin generates a wide variety of haptic feel in response to the touch by synchronizing the sensor and the stimulator. In this paper, the design of the haptic cell is derived via iterative analysis and design procedures. A fabrication method dedicated to the proposed device is investigated and a controller to drive multiple haptic cells is developed. In addition, several experiments are performed to evaluate the performance of the active skin
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