196,125 research outputs found
Comparative analysis of neutronics/thermal-hydraulics multi-scale coupling for LWR analysis
Full text linkThe aim of the research described in this paper is to perform consistent comparative analyses of two different approaches for coupling of two-scale, two-physics phenomena in reactor core calculations. The physical phenomena of interest are the neutronics and the thermal-hydraulics core behaviors and their interactions, while the spatial scales are the “global” (assembly/channel-wise) and the “local” (pin/sub-channel-wise). The objective is three-fold: qualification of coupled code systems by consistent step-by-step cross-comparison (in order to understand the prediction deviations in both neutronics and thermal-hydraulics parameters); assessment of fine scale (local/subchannel-wise) thermal-hydraulic effects; and evaluation of the impact of on-line modeling of interactions of the two spatial scales. The reported work is within the cooperation between the Universidad Politécnica de Madrid (UPM), Spain and the Pennsylvania State University (PSU), USA. The paper first presents the two multi-scale coupled code systems followed by cross-comparisons for steady state calculations. Selected results are discussed to highlight some of the issues involved in comparative analysis of coupled multi-scale simulations. The transient comparisons are subject of future work and publications
Assessment of CTF boiling transition and critical heat flux modeling capabilities using the OECD/NRC BFBT and PSBT benchmark databases
Full text linkThe need to refine models for best-estimate calculations, based on good-quality experimental data, has been expressed in many recent meetings in the field of nuclear applications. The modeling needs arising in this respect should not be limited to the currently available macroscopic methods but should be extended to next-generation analysis techniques that focus on more microscopic processes. One of the most valuable databases identified for the thermalhydraulics modeling was developed by the Nuclear Power Engineering Corporation (NUPEC), Japan. From 1987 to 1995, NUPEC performed steady-state and transient critical power and departure from nucleate boiling (DNB) test series based on the equivalent full-size mock-ups. Considering the reliability not only of the measured data, but also other relevant parameters such as the system pressure, inlet sub-cooling and rod surface temperature, these test series supplied the first substantial database for the development of truly mechanistic and consistent models for boiling transition and critical heat flux. Over the last few years the Pennsylvania State University (PSU) under the sponsorship of the U.S. Nuclear Regulatory Commission (NRC) has prepared, organized, conducted and summarized the OECD/NRC Full-size Fine-mesh Bundle Tests (BFBT) Benchmark. The international benchmark activities have been conducted in cooperation with the Nuclear Energy Agency/Organization for Economic Co-operation and Development (NEA/OECD) and Japan Nuclear Energy Safety (JNES) organization, Japan. Consequently, the JNES has made available the Boiling Water Reactor (BWR) NUPEC database for the purposes of the benchmark. Based on the success of the OECD/NRC BFBT benchmark the JNES has decided to release also the data based on the NUPEC Pressurized Water Reactor (PWR) subchannel and bundle tests for another follow-up international benchmark entitled OECD/NRC PWR Subchannel and Bundle Tests (PSBT) benchmark. This paper presents an application of the joint Penn State University/Technical University of Madrid (UPM) version of the well-known subchannel code COBRA-TF, namely CTF, to the critical power and departure from nucleate boiling (DNB) exercises of the OECD/NRC BFBT and PSBT benchmark
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
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
From taxuspine X to structurally simplified taxanes with remarkable P-Glycoprotein inhibitory activity
No full textThree simplified “non-natural” natural taxanes, related to taxuspine X, were synthetized and assayed as P-glycoprotein (P-gp) inhibitors. One of them (6) proved to be a very efficient P-gp inhibitor with an IC50 = 7.2 × 10−6 M. In addition, to rationalize biological data, a pharmacophoric model was built through a ligand-based approach. This model represents the first example of a pharmacophore, which describes interactions of taxanes with P-gp
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Studies toward Taxuspine X, a potent Multidrug - Resistance Reversing Agent, via ring closing metathesis strategy
No full textThe synthesis of bicyclic 3,8-secotaxane diterpenoids, which includes Taxuspine U and X, has been achieved through an approach that involves a ring closing metathesis reaction as key step for the macrocycle formation
Stereoselective synthesis of advanced intermediates en route to Taxuspine U and X: a study of macrocyclization via ring closing metathesis to highly constrained twelve-membered rings
No full textThe stereoselective synthesis of an advanced intermediate of Taxuspine U and X has been accomplished using a ring closing metathesis strategy. The feasibility of ring closing metathesis in synthesizing highly constrained and functionalized macrocycles has been demonstrated provided the appropriate substrate structure and substitution pattern are chosen. © 2006 Elsevier Ltd. All rights reserved
Studies towards the synthesis of the bicyclic 3,8-secotaxanediterpenoid system using a ring closing metathesis strategy
No full textMolecular modelling studies on the interations between taxanes and tubulins, developed by us, revealed that modified Taxuspines U and X could adopt a conformation similar to that of the bioactive conformation of paclitaxel and could be well accommodated within the proposed model. Accordingly, simplified Taxuspine U and X analogues have been rationally desig ned and their bicyclic 3,8-secotaxane diterpenoids intermediates have been synthesized through an approach that involves ring closing metathesis (RCM) as the key step for the macrocycle formation. Extensive studies on RCM have been performed using chemically diverse substrates, outlining the influence in the macrocyclization of the presence and position of functionalities, the molecular constraints and the importance of the site of ring closure
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