ASSESSMENT OF CFD CODES USED IN NUCLEAR REACTOR SAFETY SIMULATIONS

BRIAN L. SMITH 한국원자력학회 2010 Nuclear Engineering and Technology Vol.42 No.4

Following a joint OECD/NEA–IAEA–sponsored meeting to define the current role and future perspectives of the application of Computational Fluid Dynamics (CFD) to nuclear reactor safety problems, three Writing Groups were created, under the auspices of the NEA# working group WGAMA*, to produce state-of-the-art reports on different aspects of the subject. The work of the second group, WG2, was to document the existing assessment databases for CFD simulation in the context of Nuclear Reactor Safety (NRS) analysis, to gain a measure of the degree of quality and trust in CFD as a numerical analysis tool, and to take initiatives to extend the existing databases. The group worked over the period of 2003-2007 and produced a final state-ofthe-art report. The present paper summarises the material gathered during the study, illustrating the points with a few highlights. A total of 22 safety issues were identified for which the application of CFD was considered to potentially bring real benefits in terms of better understanding and increased safety. A list of the existing databases was drawn up and synthesised, both from the nuclear area and from other parallel, non-nuclear, industrial activities. The gaps in the technology base were also identified and discussed. In order to initiate new ways of bringing experimentalists and numerical analysts together, an international workshop -- CFD4NRS (the first in a series) -- was organised, a new blind benchmark activity was set up based on turbulent mixing in Tjunctions,and a Wiki-type web portal was created to offer online access to the material put together by the group giving the reader the opportunity to update and extend the contents to keep the information source topical and dynamic.

ASSESSMENT OF CFD CODES USED IN NUCLEAR REACTOR SAFETY SIMULATIONS

Smith, Brian L. Korean Nuclear Society 2010 Nuclear Engineering and Technology Vol.42 No.4

Following a joint OECD/NEA-IAEA-sponsored meeting to define the current role and future perspectives of the application of Computational Fluid Dynamics (CFD) to nuclear reactor safety problems, three Writing Groups were created, under the auspices of the NEA working group WGAMA, to produce state-of-the-art reports on different aspects of the subject. The work of the second group, WG2, was to document the existing assessment databases for CFD simulation in the context of Nuclear Reactor Safety (NRS) analysis, to gain a measure of the degree of quality and trust in CFD as a numerical analysis tool, and to take initiatives to extend the existing databases. The group worked over the period of 2003-2007 and produced a final state-of-the-art report. The present paper summarises the material gathered during the study, illustrating the points with a few highlights. A total of 22 safety issues were identified for which the application of CFD was considered to potentially bring real benefits in terms of better understanding and increased safety. A list of the existing databases was drawn up and synthesised, both from the nuclear area and from other parallel, non-nuclear, industrial activities. The gaps in the technology base were also identified and discussed. In order to initiate new ways of bringing experimentalists and numerical analysts together, an international workshop -- CFD4NRS (the first in a series) -- was organised, a new blind benchmark activity was set up based on turbulent mixing in T-junctions, and a Wiki-type web portal was created to offer online access to the material put together by the group giving the reader the opportunity to update and extend the contents to keep the information source topical and dynamic.

Online Implementation of DynaMIT: A Prototype Traffic Examination and Prediction Program

Byungkyu(Brian) Park,이조영,Devi M. Pampati,Brian L. Smith 대한토목학회 2008 KSCE JOURNAL OF CIVIL ENGINEERING Vol.12 No.2

This paper presents a pilot study of conducting an online implementation of DynaMIT, one of traffic estimation and prediction(TrEP) programs developed by an MIT research team with the support from the U.S. Federal Highway Administration, in HamptonRoads, VA, U.S.A. As a first step, a test-bed network was cbefore evaluating the performance of the online implementation of DynaMIT. Based on the online implementation of DynaMIT forthree days, it was found that DynaMIT showed fairly good performance on the estimation and prediction of the sensor counts withthe root mean square normalized (RMSN) error ranges betwen 0.15 and 0.25 for estimations, and 0.25 and 0.4 for predictions. Eventhough speed and travel times showed some discrepancies, further investigations indicated that the performance of DynaMIT can besignificantly improved with adequately calibrated supply parameters.

Feasibility Assessment of a Smartphone-Based Application to Estimate Road Roughness

Huanghui Zeng,Hyungjun Park,Brian L. Smith,Emily Parkany 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

Transportation agencies spend significant resources to collect pavement roughness data using profiler vans. A potential alternativeto collect functionally equivalent data at a significantly lower cost and higher level of temporal resolution is to use existingaccelerometers in smartphones as the “set” of sensors. In this research, a prototype smartphone application was developed toinvestigate the feasibility of such an approach. Acceleration data were collected using a prototype application running on Androidtablets on two routes in Virginia. The analysis results show that the proposed smartphone application can generate consistent data setsfrom different data collecting runs. In addition, the average of the collected data sets is found to be highly correlated with theInternational Roughness Index data collected by the Virginia Department of Transportation using profiler vans. Also, a sample sizeanalysis revealed that most pavement sections require fewer than 12 data collecting trips at a 50 Hz sampling rate while fewer than 16trips are required for a rate of 10 Hz. Finally, a preliminary benefit assessment for Virginia showed that the proposed smartphoneapplication approach allows for collection of comparable roughness data for more roadways, more frequently with significantly less cost.

De novo assembly of haplotype-resolved genomes with trio binning

Koren, Sergey,Rhie, Arang,Walenz, Brian P,Dilthey, Alexander T,Bickhart, Derek M,Kingan, Sarah B,Hiendleder, Stefan,Williams, John L,Smith, Timothy P L,Phillippy, Adam M Nature Publishing Group 2018 Nature biotechnology Vol.36 No.12

Postoperative Low-Dose Tranexamic Acid After Major Spine Surgery: A Matched Cohort Analysis

Lauren K. Dunn,Ching-Jen Chen,Davis G. Taylor,Kamilla Esfahani,Brian Brenner,Charles Luo,Thomas J. Buell,Sarah N. Spangler,Avery L. Buchholz,Justin S. Smith,Christopher I. Shaffrey,Edward C. Nemergut 대한척추신경외과학회 2020 Neurospine Vol.17 No.4

Objective: This was a retrospective, cohort study investigating the efficacy and safety of continuous low-dose postoperative tranexamic acid (PTXA) on drain output and transfusion requirements following adult spinal deformity surgery. Methods: One hundred forty-seven patients undergoing posterior instrumented thoracolumbar fusion of ≥3 vertebral levels at a single institution who received low-dose PTXA infusion (0.5–1 mg/kg/hr) for 24 hours were compared to 292 control patients who did not receive PTXA. The cohorts were propensity matched based on age, sex, American Society of Anesthesiologist physical status classification, body mass index, number of surgical levels, revision surgery, operative duration, and total intraoperative TXA dose (n=106 in each group). Primary outcome was 72-hour postoperative drain output. Secondary outcomes were number of allogeneic blood transfusions. Results: There was no significant difference in postoperative drain output in the PTXA group compared to control (660±420 mL vs. 710±490 mL, p=0.46). The PTXA group received significantly more crystalloid (6,100±3,100 mL vs. 4,600±2,400 mL, p<0.001) and red blood cell transfusions postoperatively (median [interquartile range]: 1 [0–2] units vs. 0 [0–1] units; incidence rate ratio [95% confidence interval], 1.6 [1.2–2.2]; p=0.001). Rates of adverse events were comparable between groups. Conclusion: Continuous low-dose PTXA infusion was not associated with reduced drain output after spinal deformity surgery. No difference in thromboembolic incidence was observed. A prospective dose escalation study is warranted to investigate the efficacy of higher dose PTXA.