1,720,957 research outputs found
Conceptual Design of an Annular-Fueled Superheat Boiling Water Reactor
No full textThe conceptual design of an annular-fueled superheat boiling water reactor (ASBWR) is
outlined. The proposed design, ASBWR, combines the boiler and superheater regions into
one fuel assembly. This ensures good neutron moderation throughout the reactor core. A
single fuel design is used in the core. Each annular fuel element, or fuel tube, is cooled
externally by boiling water and internally by steam. Fuel pellets are made of low enrichment
UO2, somewhat higher than the traditional BWR fuel enrichment. T91 and Inconel 718 are
selected as candidates for the cladding material in view of their excellent physical properties
and corrosion resistance. The fuel-cladding gap is filled with pressurized helium gas, like
the existing lighter water reactor fuels. The ASBWR fuel assembly contains sixty annular
fuel elements and one square water rod (occupying a space of four fuel elements) in an 8 by
8 square array. Annular separators and steam dryers are utilized and located above the core
in the reactor vessel. Reactor internal pumps are used to adjust the core flow rate. Cruciform
control rods are used to control the reactivity of the core, but more of them may be needed
than a traditional BWR in view of the harder spectrum.
The major design constraints have been identified and evaluated in this work. The ASBWR
is found promising to achieve a power density of 50 kW/L and meet all the main safety
requirements. This includes a limit on the minimum critical heat flux ratio, maximum fuel
and cladding operating temperatures, and appropriate stability margin against density wave
oscillations.
At the expected superheated steam of 520 °C, the plant efficiency is above 40%, which is
substantially greater than the efficiency of 33 to 35% that today’s generation of LWRs can
achieve. In addition to generating electricity, the ASBWR may also be useful for liquid fuel
production or other applications that require high temperature steam.
The uncertainties about this design include the performance of cladding materials under
irradiation, the attainment of desirable heat transfer ratio between the external andinternal
coolant channels throughout the fuel cycle, and the response to the traditional transients
prescribed as design basis events.U.S. Nuclear Regulatory CommissionMasdar Institute of Science and Technolog
Behavior of Thesis and Dissertation Research Information Management: From the Perspective of Personal Information Management
No full text本研究之目的是瞭解研究生在「學位論文研究」之情境下，如何管理個人的電子式論文研究資料，以促進日後的再利用。據此研究目的所提出之三大研究問題包括：(1)研究生如何管理論文相關電子資料？(2)「學位論文研究」情境之影響？(3)研究生對「論文相關電子資料管理」之態度為何？解答所提出之研究問題，並且回應研究目的，研究者規劃了兩個研究階段：在研究階段一採用質性取向之訪談、輔助性觀察以蒐集實徵研究資料，深入探討論文資料管理行為，訪談對象共有12位，分別為5位博士（生）及7位碩士（生），皆來自不同的學科領域；在研究階段二則採用網路問卷以擴大瞭解研究生對論文資料之管理經驗，並彌補訪談資料之缺口，總計回收214份有效問卷，填答者有四成來自科學領域，三成來自社會領域，二成來自人文領域，且幾乎都是平日有上網習慣之碩士生。合質量並行之研究結果，本研究的重要發現與結論如下：「論文資料管理行為」方面，研究生為了管理論文相關電子資料所進行之活動共有22種，這些活動分別表現出保存、組織、已知資訊搜尋及後設管理等四種特徵。研究生管理論文資料時，可能遭遇保存問題、組織問題、已知資訊搜尋問題及載體與工具問題等四大管理障礙，必須加倍投入管理成本，或重新建立管理策略方能有所改善。響「論文資料管理行為」之情境因素共有16項，這些因素分別表現出研究所生態、學位論文研究歷程、設備及資訊物件等四種特徵，並且分別對「論文資料管理行為」之不同層面帶來影響。其中「論文研究任務」因素對於「學位論文相關電子資料」（論文資料集合）產生顯著影響，多數受訪者在主要分類（第一階層之子資料夾）中，都設置了「參考文獻」、「論文正文」、「報告用投影片」以及「研究資料」等資料夾。究生普遍認知到「論文資料管理」之重要性，並且指出「組織」之目的就是為了便於「已知資訊搜尋」。多數研究生都能夠對自己的管理方式感到滿意，並且對論文資料之使用記憶有相當之自信。對於所使用之載體與工具，研究生經常感到不甚滿意，無論他們是否熟悉電腦科技。如果研究生在評估後發現，所投入的組織成本（時間、注意力、體力、金錢）未必能夠回收對等的效益，可能對論文資料之「組織」表現出一種「堪用即可」之態度。一方面，研究生的「資料夾目錄結構」分別有「集中式」和「扁平式」兩種不同結構型態，而他們對「整理資料的時間點」之偏好，亦可分為「預先組織」和「延遲組織」兩種不同策略，這種「分歧性」適足以說明個人資訊管理行為中的「成本交換」現象。合前述研究結果，本研究建議一般電腦使用者和研究生在資料累積初期便著手開始整理，並且養成隨時監控、定期整理的習慣；建議學校、系所與學術圖書館分別針對資訊組織之概念性技能、電腦工具技能，為研究生開設論文資料管理技能講座；未來相關研究可進一步探索不同情境下之PIM最佳實務，並採用本研究所提出之「學位論文相關電子資料管理行為」概念架構予以分析、解釋；最後，建議個人資訊系統之設計者和服務提供者，以個人資訊行為模式與個人資訊管理之困難為基礎，思考設計與服務之方向，並且為電腦技能弱勢者開發更親和的友善介面和即時化的使用協助服務，造福真正需要軟體協助的人。The purpose of this study is to investigate personal information management (PIM) behavior with electronic information in context of thesis and dissertation researches (TDR). Three research questions are proposed, (1) how does a graduate/doctoral student manage his/her electronic information of thesis? (2) how does the context of TDR influence a person’s PIM behavior? (3) what is the viewpoint of a graduate/doctoral student to PIM of TDR electronic information?wo stages were carried out. In first stage, we collected qualitative data by the method of interview and observed participants’ behaviors as well. The object was to understand participants’ PIM behaviors of TDR. 5 doctoral students and 7 graduate students in different disciplinary were recruited. In second stage, we collected quantitative data through an online questionnaire survey. The object was to verify the qualitative data and increase the credibility of the study. 214 questionnaires were valid.e proposed 22 types PIM activities of TDR electronic information, which could be induced into four facets, including Storage, Organizing, Known-item Searching, and Meta-Management. Moreover, a graduate/doctoral student had to invest more in management or re-build the management strategy to figure out the difficulties such as the problem of storage, organizing, known-item searching, and tool using he/she might encounter. 16 contextual elements was supposed to make influence on PIM activities of TDR, which could be induced into four facets, including Academic Environment, TDR Process, Facilities, and Information items.e also found that most students were aware of the importance of PIM in the process of TDR. They believed that they will take advantage of “Organized information” to refind the known-items quickly. But if they thought the cost of organizing information was too much, they just want to solve immediate problems. In general, students were proud of the ways of management. Moreover, they were often disappointed at the tools for PIM.e suggest users periodically monitor and organize their personal information. For college and academic libraries, it is suggested to establish courses of PIM skills, including conceptual skills of information management and computer softwares. For PIM researchers, “the best practice of PIM in different contexts” and “when to do meta-management” are valuable research issues. Finally, for PIM system designers and service providers, it is important to think of patterns of PIM behaviors in different contexts and help people with poor computer skills.中文摘要 ibstract iii次 v目次 vii目次 viii一章 緒論 1一節 研究背景 1二節 研究目的與研究問題 3三節 研究範圍與限制 4四節 名詞解釋 5二章 文獻分析 7一節 「個人資訊管理」研究之概述 7二節 個人資訊管理行為研究 19三節 學位論文研究情境與研究資料管理 27三章 研究設計與實施 30一節 研究取向與範圍 30二節 研究階段一：訪談及觀察 31三節 研究階段二：問卷調查 33四節 研究實施流程 34四章 訪談與觀察結果分析 38一節 「管理活動」與「問題」面向 43二節 「情境」面向 67三節 「個人因素」面向 85五章 問卷調查結果分析 95一節 填答者背景與論文資料管理經驗 95二節 主要變項之交叉分析 110三節 綜合討論 116六章 結論與建議 119一節 重要研究發現 119二節 結論 123三節 建議 126考文獻 130錄一 訪談綱要 137錄二 學位論文相關電子資料之管理行為調查問卷 13
Thermal Hydraulic Analysis of a Low Enrichment Uranium Core for the MIT Research Reactor
No full textThe MIT research reactor (MITR) is converting from the existing high enrichment
uranium (HEU) core to a low enrichment uranium (LEU) core using a high-density
monolithic UMo fuel. The design of an optimum LEU core for the MIT reactor is
evolving. The objectives of this study are to benchmark the in-house computer code for
the MITR, and to perform thermal hydraulic analyses in support of the LEU design
studies. The in-house multi-channel thermal-hydraulics code, MULCH-II, was developed
specifically for the MITR. This code was validated against PLTEMP for steady-state
analysis, and against RELAP5 and temperature measurements for the loss of primary
flow transient. The benchmark analysis results showed that the MULCH-II code is in
good agreement with other computer codes and experimental data, and hence it is used as
the main tool for this study.
Various fuel configurations are evaluated as part of the LEU core design optimization
study. The criteria adopted for the LEU thermal hydraulics analysis in this study of the
limiting safety system settings (LSSS), are to prevent onset of nucleate boiling during
steady-state operation, and to avoid a clad temperature excursion during the loss of flow
transient.
In ranking the LEU core design options, the primary parameter is a low power peaking
factor in order to increase the LSSS power and to decrease the maximum clad
temperature during the transient. The LEU fuel designs with 15 to 18 plates per element,
fuel thickness of 20 mils, and a hot channel factor less than 1.76 are shown to comply
with the thermal-hydraulic criteria. The steady-state power can potentially be higher than
6 MW, which was requested in the power upgrade submission to the Nuclear Regulatory
Commission.United States. Dept. of Energy. (Reduced Enrichment for Research and Test Reactors Program
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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