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Optimization of Artificial Viscosity in Production codes Based on Gaussian Regression Surrogate Models

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Communications on Applied Mathematics and Computation 2024年第3期6卷 1521-1550页

作者： Vitaliy Gyrya Evan Lieberman Mark Kenamond Mikhail Shashkov Applied Mathematics and Plasma Physics Theoretical DivisionMail Stop B284Los Alamos National LaboratoryLos AlamosNM 87545USA Continuum Models and Numerical Methods Group X-Computational Physics DivisionMail Stop F644Los Alamos National LaboratoryLos AlamosNM 87545USA Lagrangian codes Group X-Computational Physics DivisionMail Stop T086Los Alamos National LaboratoryLos AlamosNM 87545USA

To accurately model flows with shock waves using staggered-grid Lagrangian hydrodynamics, the artificial viscosity has to be introduced to convert kinetic energy into internal energy, thereby increasing the entropy across shocks. Determining the appropriate strength of the artificial viscosity is an art and strongly depends on the particular problem and experience of the researcher. The objective of this study is to pose the problem of finding the appropriate strength of the artificial viscosity as an optimization problem and solve this problem using machine learning (ML) tools, specifically using surrogate models based on Gaussian Process regression (GPR) and Bayesian analysis. We describe the optimization method and discuss various practical details of its implementation. The shock-containing problems for which we apply this method all have been implemented in the LANL code FLAG (Burton in Connectivity structures and differencing techniques for staggered-grid free-Lagrange hydrodynamics, Tech. Rep. UCRL-JC-110555, Lawrence Livermore National Laboratory, Livermore, CA, 1992, 1992, in Consistent finite-volume discretization of hydrodynamic conservation laws for unstructured grids, Tech. Rep. CRL-JC-118788, Lawrence Livermore National Laboratory, Livermore, CA, 1992, 1994, Multidimensional discretization of conservation laws for unstructured polyhedral grids, Tech. Rep. UCRL-JC-118306, Lawrence Livermore National Laboratory, Livermore, CA, 1992, 1994, in FLAG, a multi-dimensional, multiple mesh, adaptive free-Lagrange, hydrodynamics code. In: NECDC, 1992). First, we apply ML to find optimal values to isolated shock problems of different strengths. Second, we apply ML to optimize the viscosity for a one-dimensional (1D) propagating detonation problem based on Zel’dovich-von Neumann-Doring (ZND) (Fickett and Davis in Detonation: theory and experiment. Dover books on physics. Dover Publications, Mineola, 2000) detonation theory using a reactive burn model. We compare re

关键词： Optimization Artificial viscosity Gaussian regression surrigate model

Finger vein recognition using weighted local binary pattern code based on a support vector machine

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第7期11卷 514-524页

作者： Hyeon Chang LEE Byung Jun KANG Eui Chul LEE Kang Ryoung PARK division of Electronics and Electrical Engineering Dongguk University Electronics and Telecommunications Research Institute division of Fusion and Convergence of Mathematical Sciences the National Institute for Mathematical Sciences

Finger vein recognition is a biometric technique which identifies individuals using their unique finger vein patterns. It is reported to have a high accuracy and rapid processing speed. In addition, it is impossible to steal a vein pattern located inside the finger. We propose a new identification method of finger vascular patterns using a weighted local binary pattern (LBP) and support vector machine (SVM). This research is novel in the following three ways. First, holistic codes are extracted through the LBP method without using a vein detection procedure. This reduces the processing time and the complexities in detecting finger vein patterns. Second, we classify the local areas from which the LBP codes are extracted into three categories based on the SVM classifier: local areas that include a large amount (LA), a medium amount (MA), and a small amount (SA) of vein patterns. Third, different weights are assigned to the extracted LBP code according to the local area type (LA, MA, and SA) from which the LBP codes were extracted. The optimal weights are determined empirically in terms of the accuracy of the finger vein recognition. Experimental results show that our equal error rate (EER) is significantly lower compared to that without the proposed method or using a conventional method.

关键词： Finger vein recognition Support vector machine (SVM) Weight Local binary pattern (LBP)

A study of real-world micrograph data quality and machine learning model robustness

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npj Computational Materials 2021年第1期7卷 1463-1473页

作者： Xiaoting Zhong Brian Gallagher Keenan Eves Emily Robertson T.Nathan Mundhenk T.Yong-Jin Han Materials Science division Lawrence Livermore National LaboratoryLivermoreCAUSA Center for Applied Scientific Computing Lawrence Livermore National LaboratoryLivermoreCAUSA Defense Technologies Engineering division Lawrence Livermore National LaboratoryLivermoreCAUSA Computational Engineering division Lawrence Livermore National LaboratoryLivermoreCAUSA

Machine-learning(ML)techniques hold the potential of enabling efficient quantitative micrograph analysis,but the robustness of ML models with respect to real-world micrograph quality variations has not been carefully *** collected thousands of scanning electron microscopy(SEM)micrographs for molecular solid materials,in which image pixel intensities vary due to both the microstructure content and microscope instrument *** then built ML models to predict the ultimate compressive strength(UCS)of consolidated molecular solids,by encoding micrographs with different image feature descriptors and training a random forest regressor,and by training an end-to-end deep-learning(DL)*** show that instrument-induced pixel intensity signals can affect ML model predictions in a consistently negative *** a remedy,we explored intensity normalization *** is seen that intensity normalization helps to improve micrograph data quality and ML model robustness,but microscope-induced intensity variations can be difficult to eliminate.

关键词： instrument image eliminate

End-stage renal disease is associated with increased post endoscopic retrograde cholangiopancreatography adverse events in hospitalized patients

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World Journal of Gastroenterology 2018年第41期24卷 4691-4697页

作者： Tarek Sawas Fateh Bazerbachi Samir Haffar Won K Cho Michael J Levy John A Martin Bret T Petersen Mark D Topazian Vinay Chandrasekhara Barham K Abu Dayyeh division of Gastroenterology and Hepatology Mayo Clinic Department of Gastroenterology Digestive Center for Diagnosis and Treatment division of Gastroenterology and Hepatology Georgetown University Medstar Washington Hospital Center

AIM To determine if end-stage renal disease (ESRD) is a risk factor for post endoscopic retrograde cholangio-pancreatography (ERCP) adverse events (AEs). METHODS We performed a retrospective cohort study using the Nationwide Inpatient Sample (NIS) 2011-2013. We identified adult patients who underwent ERCP using the International Classification of Diseases 9^(th) Revision (ICD-9-CM). Included patients were divided into three groups: ESRD, chronic kidney disease (CKD), and control. The primary outcome was post-ERCP AEs including pancreatitis, bleeding, and perforation determined based on specific ICD-9-CM codes. Secondary outcomes were length of hospital stay, in-hospital mortality, and admission cost. AEs and mortality were compared using multivariate logistic regression *** There were 492175 discharges that underwent ERCP during the 3 years. The ESRD and CKD groups contained 7347 and 39403 hospitalizations respectively, whereas the control group had 445424 hospitalizations. Post-ERCP pancreatitis (PEP) was significantly higher in the ESRD group (8.3%) compared to the control group (4.6%) with adjusted odd ratio (aOR) = 1.7 (95% CI: 1.4-2.1, ~aP < 0.001). ESRD was associated with significantly higher ERCP-related bleeding (5.1%) compared to the control group 1.5% (aOR = 1.86, 95%CI: 1.4-2.4, ~aP < 0.001). ESRD had increased hospital mortality 7.1% vs 1.15% in the control OR = 6.6 (95%CI: 5.3-8.2, ~aP < 0.001), longer hospital stay with adjusted mean difference (aMD) = 5.9 d (95% CI: 5.0-6.7 d, ~aP < 0.001) and higher hospitalization charges aMD = $+82064 (95%CI: $68221-$95906, ~aP < 0.001). CONCLUSION ESRD is a risk factor for post-ERCP AEs and is associated with higher hospital mortality. Careful selection and close monitoring is warranted to improve outcomes.

关键词： End-stage renal disease Nationwide Inpatient Sample Endoscopic retrograde cholangiopancreatography

Papillary thyroid cancer and inflammatory bowel disease:Is there a relationship?

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World Journal of Gastroenterology 2013年第7期19卷 1079-1084页

作者： Irene S Sonu Wojciech Blonski Ming Valerie Lin James Lewis Faten Aberra Gary R Lichtenstein division of Internal Medicine Stanford University Hospital and ClinicsStanfordCA 94305United States division of Internal Medicine UHS Wilson Medical CenterJohnson CityNY 13790United States division of Digestive Diseases University of CincinnatiCincinnatiOH 45229United States division of Gastroenterology Hospital of the University of PennsylvaniaUniversity of Pennsylvania School of MedicinePhiladelphiaPA 19103United States

AIM:To formally study age of diagnosis of papillary thyroid cancer(PTC) in inflammatory bowel disease(IBD) patients and evaluate the prevalence of PTC in IBD patients compared to a control *** that patients with IBD are more likely to be diagnosed with PTC than a control population.A retrospective cohort analysis was performed using the University of Pennsylvania Health System's electronic *** from 1998-2009 were included in the search,and patients in the cohort were selected based on ICD-9 *** criteria included the diagnosis of Crohn's disease(CD) or ulcerative colitis(UC) and the concurrent diagnosis of thyroid cancer in comparison to a control *** these methods 912 patients with CD and 1774 with UC were compared to 1638 diverticulitis and 19 447 asthma *** were performed using corrected chisquare *** primary outcome for this study was the diagnosis of *** to conduct this study was obtained by the Institutional Review Board at the University of ***:The mean age was 47.5 years(range:18-102 years) and 66% patients were *** analysis of variance model was used to compare the age of PTC diagnosis between the CD,UC,asthma and diverticulitis groups,and a statistically significant difference in age at PTC diagnosis was noted across all groups(F = 6.35,df = 3,P = 0.0006).The age of PTC diagnosis in CD patients was statistically significantly lower than UC,asthma,and diverticulitis patients(average PTC diagnosis age for CD 25,UC 49,asthma 45,diverticulitis 63).After covarying for sex and age in 2009,the difference in age at PTC diagnosis remained statistically significant(F = 4.13,df = 3,P = 0.0089).A total of 86 patients were diagnosed with *** patients(0.5%) with UC were diagnosed with *** with UC were not shown to be more likely to develop PTC [odds ratio(OR):1.544,95%CI 0.767-3.108] compared to asthma *** patients(0.4%) with CD were

关键词： Papillary thyroid cancer Inflammatory bowel disease Crohn disease Ulcerative colitis

Diabetes mellitus as a risk factor for gastrointestinal cancer among American veterans

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World Journal of Gastroenterology 2009年第42期15卷 5274-5278页

作者： M Mazen Jamal Eugene J Yoon Kenneth J Vega Mehrtash Hashemzadeh Kenneth J Chang division of Gastroenterology Veterans Affairs(VA) Medical CenterLong BeachCA 90822United States division of Gastroenterology Department of Internal MedicineCollege of MedicineUniversity of CaliforniaIrvine Medical CenterOrangeCA 92868United States division of Gastroenterology University of Florida/JacksonvilleJacksonvilleFL 32207United States

AIM:To assess the risk of biliary and pancreatic cancers in a large cohort of patients with type 2 diabetes mellitus(DM) .METHODS:Eligibility for this study included patients with type 2 DM(ICD-9 code 250.0) who were discharged from Department of Veteran Affairs hospitals between 1990 and ***-matched control patients without DM were selected from the same patient treatment files during the same *** information included age,sex and *** diagnoses included known risk factors based on their ICD-9 *** multivariate logistic regression,the occurrence of biliary and pancreatic cancer was compared between case subjects with DM and controls without ***:A total of 1172496 case and control subjects were *** mean age for study and control subjects was 65.8 ± 11.3 and 64.8 ± 12.6 years,*** frequency of pancreatic cancer in subjects with DM was increased(0.9%) in comparison to control subjects(0.3%) with an OR of 3.22(95% CI:3.03-3.42) .The incidence of gallbladder andextrahepatic biliary cancers was increased by twofold in diabetic patients when compared to *** OR and 95% CI were 2.20(1.56-3.00) and 2.10(1.61-2.53) ,***:Our study demonstrated that patients with DM have a threefold increased risk for developing pancreatic cancer and a twofold risk for developing biliary cancer.

关键词： Diabetes mellitus Pancreatic neoplasms Adenocarcinoma Gallbladder neoplasms

Why are we performing fewer cholecystectomies for mild acute biliary pancreatitis?Trends and predictors of cholecystectomy from the National Readmissions Database(2010–2014)

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Gastroenterology Report 2019年第5期7卷 331-337,I0002页

作者： Sushil Kumar Garg Fateh Bazerbachi Shashank Sarvepalli Shounak Majumder Shanthi Swaroop Vege division of Gastroenterology and Hepatology Mayo ClinicRochesterMNUSA division of Gastroenterology Massachusetts General HospitalBostonMAUSA Department of Hospital Medicine Cleveland ClinicClevelandOHUSA

Background:Current guidelines recommend cholecystectomy for patients with mild acute biliary pancreatitis(MABP)during the index admission because it is associated with better *** this study,we aimed to assess national trends in cholecystectomy during index admissions for MABP and to identify factors associated with cholecystectomy completion and 30-day ***:Using diagnostic codes and the National Readmissions Database,we identified patients admitted with MABP between 2010 and *** in cholecystectomy rates were computed on the basis of various *** conducted a multivariable analysis to identify factors associated with 30-day readmission and cholecystectomy during the same ***:We identified 255,695 unique index MABP cases(41.3%male)and the 30-day readmission rate was 12.6%.Overall,43.8%underwent cholecystectomy and 25%underwent endoscopic retrograde cholangiopancreatography(ERCP)with *** observed a decreasing trend in both procedures during the study period(P<0.001).In multivariate analysis,odds of 30-day readmission were reduced for patients undergoing ERCP with sphincterotomy(odds ratio,0.78;95%confidence interval,0.74–0.84)or cholecystectomy(odds ratio,0.37;95%confidence interval,0.35–0.39).Conclusions:For patients with MABP,cholecystectomy or ERCP with sphincterotomy during the index admission decreased the risk of 30-day *** this benefit and national guidelines recommending cholecystectomy during the index MABP admission,the rate of cholecystectomies performed nationally decreased during the study *** research is needed to understand the implications and reasons underlying this deviation from guidelines.

关键词： cholecystectomy mild acute biliary pancreatitis National Readmissions Database endoscopic retrograde cholangiopancreatography

The Chinese Export Boom:An Examination of the Detailed Trade Data

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China & World Economy 2013年第1期21卷 64-90页

作者： Brett Berger Robert F.Martin division of International Finance Board of Governors of the Federal Reserve System Global Monetary and Sovereign Markets Division of International FinanceBoard of Governors of the Federal Reserve System

From 2000 to 2007, Chinese exports grew at a phenomenal pace. Our paper uses finely detailed Chinese export data （8-digit Harmonized Commodity Description and Coding System codes） combined with US trade data to explore how this was achieved. Although general explanations such as China ~ exchange rate policy no doubt played a role, we find that sector-specific stories, effective Chinese industrial policy and fortuitous timing were more critical The detailed trade data reveal that ＂＇new ＂＇ technology goods, such as cell phones, LCD screens and laptops, played a key role. Finally, we use the data to examine the relationship between Chinese exports and global manufacturing, in particular US manufacturing employment. We find that competition from China in both domestic and foreign markets likely contributed to a significant decline in USA manufacturing employment, but that relatively low US investment and slow GDP growth in the US following the 2001 recession played an equally important role.

关键词： China export manufacturing trade

Trends in the rates of hospitalizations for acute stroke among patients over 90 years of age with atrial fibrillation in the United States： from 2005 to 2014

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Journal of Geriatric Cardiology 2017年第9期14卷 547-552页

作者： Ghanshyam PS Shantha Amgad Mentias Musab Alqasrawi Abdul Qazi Chakradhari Inampudi Kongkiat Chaikriangkrai Abhishek Deshmuk Steven Bailin Michael Giudici Alexander Mazur division of Cardiovascular Medicine University of Iowa Hospitals and Clinics lowa City lowa USA Mayo Clinic Rochester MN USA

Background Acute stroke （AS） rates in patients over 90 years of age （very elderly） with atrial fibrillation （AF） in the United States（US） are not known. We assessed trends in hospitalizations for AS among very elderly with AF in the US from 2005 to 2014. Methods Weused the nationwide inpatient sample （NIS） from the USA; 2005-2014. AF and AS diagnoses were abstracted using international classifica-tion of diseases, 9th Revision, clinical modification （ICD-9-CM） codes. Results From 2005 to 2014, 3,606,073 hospitalizations of veryelderly with AF were reported. Of these, 188,948 hospitalizations （141,822 hospitalizations in women and 47,126 hospitalizations in men）had AS as the primary diagnosis. Age adjusted AS hospitalizations increased in the total cohort （3217/million in 2005 to 3871/million in2014）, in women （3540/million in 2005 to 4487/million in 2014） and in men （2490/million in 2005 to 3173/million in 2014）（P 〈 0.001）.Anticoagnlation rates increased in women （8% in 2005 to 19.9% in 2014） and in men （8.9% in 2005 to 21.6% in 2014）. AS rates, thoughnumerically lower than the total cohort, showed an increasing trend in anticoagnlated patients as well （all anticoagulated patients： 212/millionin 2005 to 513/million in 2014; anticoagulated women： 224/million in 2005 to 529/million in 2014, anticoagnlated men： 184/million in 2005to 518/million in 2014）. Conclusions There is an increasing trend in AS hospitalizations among nonagenarians with AF in the US despiteimproving utilization of anticoagulants in this patient population. The etiologies driving this alarming trend are unclear and require fur-ther study.

关键词： Anticoagulation Atrial fibrillation Nonagenarian Stroke