Assessment of Liver Stiffness in Pediatric Fontan Patients Using Transient Elastography

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Becky Chen

2016-01-01

Full Text Available Background. Hepatic fibrosis is a potential complication following Fontan surgery and heralds long-term risk for cirrhosis. Transient elastography (TE is a rapid, noninvasive method to assess liver fibrosis by measuring liver stiffness. Objectives. To compare liver stiffness and liver biochemistries in pediatric Fontan patients with age- and sex-matched controls and to determine patients’ acceptance of TE. Methods. Patients were recruited from British Columbia Children’s Hospital. Twenty-two Fontan patients (15 males were identified. Demographic information and cardiac data were collected. TE was measured using size-appropriate probes. Results. The median age of the Fontan cohort was 13.7 (5.9–16.8 years. Time from Fontan surgery to TE was 9.6 (1.0–12.9 years. The median Fontan circuit pressure was 13 (11–14 mmHg. TE values were higher in Fontan patients versus controls (18.6 versus 4.7 kPa, p<0.001. There was no association between TE values and patient age (r=0.41, p=0.058, time since Fontan surgery (r=0.40, p=0.062, or median Fontan circuit pressure (CVP (r=0.35, p=0.111. Patients found TE to be nonpainful, convenient, and safe. Conclusions. TE is feasible to assess liver stiffness in children following Fontan surgery. Pediatric Fontan patients have markedly elevated liver stiffness values. TE may have important utility in liver care follow-up of pediatric Fontan patients.

Fontan fenestration closure and event-free survival.

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Imielski, Bartlomiej R; Woods, Ronald K; Mussatto, Kathleen A; Cao, Yumei; Simpson, Pippa M; Tweddell, James S

2013-01-01

The purpose of the present study was to evaluate the association of open and closed Fontan fenestration status with event-free survival. All patients who underwent a fenestrated Fontan procedure at our institution from January 1994 through June 2007 were reviewed. Patient information was obtained from the medical records. The patients were assigned to 1 of 2 study groups, open or closed, according to their most recent fenestration status. Clinically relevant morbid events were tabulated, and Kaplan-Meier event analysis was used to create event-free probability curves with log-rank comparisons. A total of 161 patients were classified as open and 51 as closed. The median interval to an event was 1.1 years (interquartile range, 0.1-3.3 years) after the Fontan procedure. The median interval to closure was 1.2 years (interquartile range, 0.7-3.3 years). The median interval to an event was 1.5 years (interquartile range, 0.1-4.6 years) in the closed group and 1.1 years (interquartile range, 0.1-3.3 years) in the open group. Event-free probability analysis revealed no significant difference between the 2 groups (P = .15). The median follow-up arterial oxygen saturation was greater in the closed group (96.0%; interquartile range, 94.0%-97.0%) than in the open group (91.0%; interquartile range, 86.0%-95.0%; P < .0001). Fenestration closure was associated with greater arterial oxygen saturation but not greater event-free survival. The interval to an event was slightly less than the interval to fenestration closure, suggesting potential merit in the evaluation of earlier fenestration closure. Adoption of specific fenestration management guidelines might help improve the overall outcomes and enhance the quality of future studies. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

[Failed transcatheter creation of fenestration in a Fontan patient with original fenestration closed by AngelWings septal occluder: a case report].

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Ohno, Atsuko; Hirotaka, Ishido; Kobayashi, Toshiki; Asano, Haruhiko; Kyo, Shunei; Senzaki, Hideaki

2007-10-01

The fenestrated Fontan procedure has helped to reduce the mortality and morbidity of pediatric patients who underwent the Fontan operation. We treated a patient (7-year-old, female) who had developed heart failure 1 year after fenestration closure using an AngelWings device, although the patient met the proposed criteria for test occlusion. Hemodynamic evaluation using the ventricular pressure-area relationship revealed that the patient had both systolic and diastolic dysfunction, which were difficult to recognize by conventional hemodynamic indices. We then tried to percutaneously create a fenestration using a Brockenbrough needle, but this procedure failed. The AngelWings device, which may have been covered by pseudointima (composed of fibroelastic tissue), was hard enough to break the Brockenbrough needle. Re-creating a fenestration after device closure in patients after the fenestrated Fontan operation appears to be difficult, so more accurate methods to predict Fontan physiology after fenestration closure are needed.

Fontan-associated protein-losing enteropathy and plastic bronchitis.

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Schumacher, Kurt R; Stringer, Kathleen A; Donohue, Janet E; Yu, Sunkyung; Shaver, Ashley; Caruthers, Regine L; Zikmund-Fisher, Brian J; Fifer, Carlen; Goldberg, Caren; Russell, Mark W

2015-04-01

To characterize the medical history, disease progression, and treatment of current-era patients with the rare diseases Fontan-associated protein-losing enteropathy (PLE) and plastic bronchitis. A novel survey that queried demographics, medical details, and treatment information was piloted and placed online via a Facebook portal, allowing social media to power the study. Participation regardless of PLE or plastic bronchitis diagnosis was allowed. Case control analyses compared patients with PLE and plastic bronchitis with uncomplicated control patients receiving the Fontan procedure. The survey was completed by 671 subjects, including 76 with PLE, 46 with plastic bronchitis, and 7 with both. Median PLE diagnosis was 2.5 years post-Fontan. Hospitalization for PLE occurred in 71% with 41% hospitalized ≥ 3 times. Therapy varied significantly. Patients with PLE more commonly had hypoplastic left ventricle (62% vs 44% control; OR 2.81, 95% CI 1.43-5.53), chylothorax (66% vs 41%; OR 2.96, CI 1.65-5.31), and cardiothoracic surgery in addition to staged palliation (17% vs 5%; OR 4.27, CI 1.63-11.20). Median plastic bronchitis diagnosis was 2 years post-Fontan. Hospitalization for plastic bronchitis occurred in 91% with 61% hospitalized ≥ 3 times. Therapy was very diverse. Patients with plastic bronchitis more commonly had chylothorax at any surgery (72% vs 51%; OR 2.47, CI 1.20-5.08) and seasonal allergies (52% vs 36%; OR 1.98, CI 1.01-3.89). Patient-specific factors are associated with diagnoses of PLE or plastic bronchitis. Treatment strategies are diverse without clear patterns. These results provide a foundation upon which to design future therapeutic studies and identify a clear need for forming consensus approaches to treatment. Copyright © 2015 Elsevier Inc. All rights reserved.

Quantification of hepatic flow distribution using particle tracking for patient specific virtual Fontan surgery

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Yang, Weiguang; Vignon-Clementel, Irene; Troianowski, Guillaume; Shadden, Shawn; Mohhan Reddy, V.; Feinstein, Jeffrey; Marsden, Alison

2010-11-01

The Fontan surgery is the third and final stage in a palliative series to treat children with single ventricle heart defects. In the extracardiac Fontan procedure, the inferior vena cava (IVC) is connected to the pulmonary arteries via a tube-shaped Gore-tex graft. Clinical observations have shown that the absence of a hepatic factor, carried in the IVC flow, can cause pulmonary arteriovenous malformations. Although it is clear that hepatic flow distribution is an important determinant of Fontan performance, few studies have quantified its relation to Fontan design. In this study, we virtually implanted three types of grafts (T-junction, offset and Y-graft) into 5 patient specific models of the Glenn (stage 2) anatomy. We then performed 3D time-dependent simulations and systematically compared the IVC flow distribution, energy loss, and pressure levels in different surgical designs. A robustness test is performed to evaluate the sensitivity of hepatic distribution to pulmonary flow split. Results show that the Y-graft design effectively improves the IVC flow distribution, compared to traditional designs and that surgical designs could be customized on a patient-by-patient basis.

Comparing Pre- and Post-Operative Fontan Hemodynamic Simulations: Implications for the Reliability of Surgical Planning

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Haggerty, Christopher M.; de Zélicourt, Diane A.; Restrepo, Maria; Rossignac, Jarek; Spray, Thomas L.; Kanter, Kirk R.; Fogel, Mark A.; Yoganathan, Ajit P.

2012-01-01

Background Virtual modeling of cardiothoracic surgery is a new paradigm that allows for systematic exploration of various operative strategies and uses engineering principles to predict the optimal patient-specific plan. This study investigates the predictive accuracy of such methods for the surgical palliation of single ventricle heart defects. Methods Computational fluid dynamics (CFD)-based surgical planning was used to model the Fontan procedure for four patients prior to surgery. The objective for each was to identify the operative strategy that best distributed hepatic blood flow to the pulmonary arteries. Post-operative magnetic resonance data were acquired to compare (via CFD) the post-operative hemodynamics with predictions. Results Despite variations in physiologic boundary conditions (e.g., cardiac output, venous flows) and the exact geometry of the surgical baffle, sufficient agreement was observed with respect to hepatic flow distribution (90% confidence interval-14 ± 4.3% difference). There was also good agreement of flow-normalized energetic efficiency predictions (19 ± 4.8% error). Conclusions The hemodynamic outcomes of prospective patient-specific surgical planning of the Fontan procedure are described for the first time with good quantitative comparisons between preoperatively predicted and postoperative simulations. These results demonstrate that surgical planning can be a useful tool for single ventricle cardiothoracic surgery with the ability to deliver significant clinical impact. PMID:22777126

The Fontan pathway: What's down the road?

International Nuclear Information System (INIS)

Khambadkone, Sachin

2008-01-01

The Fontan circulation results from routing of the systemic venous blood to the pulmonary circulation without a hydraulic source of a ventricle. Although a hypertrophied right atrium was thought to be essential for this circulation, the current form of the operation has neither the right atrium nor any valves in the venous circulation that is connected to the pulmonary arteries directly. Modifications in the operative model was one of the early steps in improving outcome. Use of fenestration, staging of Fontan completion and better perioperative management have led to a significant drop in mortality rates in the current era. Despite this, there is late attrition of patients with complications such as arrhythmias, ventricular dysfunction, and unusual clinical syndromes of protein-losing enteropathy (PLE) and plastic bronchitis. Management of failing Fontan includes a detailed hemodynamic and imaging assessment to treat any correctable lesions such as obstruction within the Fontan circuit, early control of arrhythmia and maintenance of sinus rhythm, symptomatic treatment for PLE and plastic bronchitis, manipulation of systemic and pulmonary vascular resistance, and Fontan conversion of less favorable atriopulmonary connection to extra-cardiac total cavopulmonary connection with arrythmia surgery. Cardiac transplantation remains the only successful definitive palliation in the failing Fontan patients

Thromboembolism and anticoagulation after Fontan surgery

OpenAIRE

Viswanathan, Sangeetha

2016-01-01

This review attempts to answer the common questions faced by a clinician regarding thromboembolism and thromboprophylaxis in patients following Fontan surgery. The review is in an easy to understand question and answer format and discusses the currently available literature on the subject in an attempt to arrive at practical clinically relevant solutions. Patients who have undergone the Fontan operation are at a high risk for thromboembolism. Based on available evidence, there is a strong rat...

Treatment of Children with Protein – Losing Enteropathy After Fontan and Other Complex Congenital Heart Disease Procedures in Condition with Limited Human and Technical Resources

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Bejiqi, Ramush; Retkoceri, Ragip; Zeka, Naim; Bejiqi, Hana; Vuqiterna, Armend; Maloku, Arlinda

2014-01-01

Background Protein-losing enteropathy (PLE) is a disorder characterized by abnormal and often profound enteric protein loss. It’s relatively uncommon complication of Fontan and other complex congenital heart disease (CCHD) procedures. Because of the complexity and rarity of this disease process, the pathogenesis and pathophysiology of protein-losing enteropathy remain poorly understood, and attempts at treatment seldom yield long-term success. Aim of presentation is to describe single centre experience in diagnosis, evaluation, management and treatment of children with protein-losing enteropathy after Fontan and other CCHD procedures in the current era and in centre with limited human and technical resources, follows with a comprehensive review of protein-losing enteropathy publications, and concludes with suggestions for prevention and treatment. Material and methodology Retrospectively we analyzed patients with CCHD and protein-losing enteropathy in our institution, starting from January 2000 to December 2012. The including criteria were age between two and 17 years, to have a complex congenital heart disease and available complete documentation of cardiac surgery under cardiopulmonary bypass. Results Of all patients we evaluated 18 cases with protein-losing enteropathy, aged 6 to 19 years (mean 14±9); there were three children who had undergone screening procedure for D-transposition, one Tetralogy of Fallot, and remaining 14 patients had undergone Fontan procedures; (anatomic diagnosis are: six with tricuspid atresia, seven with d-transposition, double outlet right ventricle and pulmonary atresia and two with hypoplastic left heart syndrome). The diagnosis of protein-losing enteropathy was made at median age of 5.6 years, ranging from 13 months to 15 years. Diagnosis was made using alpha 1-antitrypsin as a gold marker in stool. By physical examination in 14 patients edema was found, in three ascites, and six patients had pleural effusion. Laboratory findings

Anestesia en la operación de Fontan

Directory of Open Access Journals (Sweden)

Lincoln de la Parte Pérez

2002-12-01

Full Text Available La técnica de Fontan ofrece la primera operación fisiológica para la atresia tricuspídea (AT mediante la separación completa de las circulaciones sistémicas y pulmonar. Este proceder se basa en el principio de que la presión en la aurícula derecha es suficiente para garantizar un flujo sanguíneo adecuado a los pulmones, lo que hace innecesaria la función del ventrículo derecho. A partir de su introducción, existe una esperanza para los pacientes con un solo ventrículo y es un procedimiento cada vez más frecuente en el Servicio de Anestesia Cardiovascular. Esta realidad fue el motivo para presentar una revisión bibliográfica actualizada sobre la técnica anestésica que se debe emplear en este procedimiento quirúrgico.Fontan´s technique offers the first physiological operation for tricuspid atresia by complete separation of systemic and pulmonary circulation. This procedure is based on the principle that the right atrium pressure is enough to assure an adequate blood flow to the lungs, which makes the function of right ventricle unnecessary. After the introduction of this procedure, there is a hope for those patients with only one ventricle, therefore, this is an increasingly frequent technique applied in the cardiovascular anesthesia service. Such a reality was the main reason for presenting an updated literature review of the anesthetic technique that should be used in this surgical procedure.

Treatment of Children with Protein – Losing Enteropathy After Fontan and Other Complex Congenital Heart Disease Procedures in Condition with Limited Human and Technical Resources

OpenAIRE

Bejiqi, Ramush; Retkoceri, Ragip; Zeka, Naim; Bejiqi, Hana; Vuqiterna, Armend; Maloku, Arlinda

2014-01-01

Background Protein-losing enteropathy (PLE) is a disorder characterized by abnormal and often profound enteric protein loss. It’s relatively uncommon complication of Fontan and other complex congenital heart disease (CCHD) procedures. Because of the complexity and rarity of this disease process, the pathogenesis and pathophysiology of protein-losing enteropathy remain poorly understood, and attempts at treatment seldom yield long-term success. Aim of presentation is to describe single centre ...

Hemodynamic Effects of Ventricular Assist Device Implantation on Norwood, Glenn, and Fontan Circulation: A Simulation Study.

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Di Molfetta, Arianna; Amodeo, Antonio; Gagliardi, Maria G; Trivella, Maria G; Fresiello, Libera; Filippelli, Sergio; Toscano, Alessandra; Ferrari, Gianfranco

2016-01-01

The growing population of failing single-ventricle (SV) patients might benefit from ventricular assist device (VAD) support as a bridge to heart transplantation. However, the documented experience is limited to isolated case reports. Considering the complex and different physiopathology of Norwood, Glenn, and Fontan patients and the lack of established experience, the aim of this work is to realize and test a lumped parameter model of the cardiovascular system able to simulate SV hemodynamics and VAD implantation effects to support clinical decision. Hemodynamic and echocardiographic data of 30 SV patients (10 Norwood, 10 Glenn, and 10 Fontan) were retrospectively collected and used to simulate patients' baseline. Then, the effects of VAD implantation were simulated. Simulation results suggest that the implantation of VAD: (i) increases the cardiac output and the mean arterial systemic pressure in all the three palliation conditions (Norwood 77.2 and 19.7%, Glenn 38.6 and 32.2%, and Fontan 17.2 and 14.2%); (ii) decreases the SV external work (Norwood 55%, Glenn 35.6%, and Fontan 41%); (iii) decreases the pressure pulsatility index (Norwood 65.2%, Glenn 81.3%, and Fontan 64.8%); (iv) increases the pulmonary arterial pressure in particular in the Norwood circulation (Norwood 39.7%, Glenn 12.1% and Fontan 3%); and (v) decreases the atrial pressure (Norwood 2%, Glenn 10.6%, and Fontan 8.6%). Finally, the VAD work is lower in the Norwood circulation (30.4 mL·mm Hg) in comparison with Fontan (40.3 mL·mm Hg) and to Glenn (64.5 mL·mm Hg) circulations. The use of VAD in SV physiology could be helpful to bridge patients to heart transplantations by increasing the CO and unloading the SV with a decrement of the atrial pressure and the SV external work. The regulation of the pulmonary flow is challenging because the Pap is increased by the presence of VAD. The hemodynamic changes are different in the different SV palliation step. The use of numerical models

An international multicenter study comparing arrhythmia prevalence between the intracardiac lateral tunnel and the extracardiac conduit type of Fontan operations.

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Balaji, Seshadri; Daga, Ankana; Bradley, David J; Etheridge, Susan P; Law, Ian H; Batra, Anjan S; Sanatani, Shubayan; Singh, Anoop K; Gajewski, Kelly K; Tsao, Sabrina; Singh, Harinder R; Tisma-Dupanovic, Svjetlana; Tateno, Shigeru; Takamuro, Motoki; Nakajima, Hiromichi; Roos-Hesselink, Jolien W; Shah, Maully

2014-08-01

The study objective was to determine whether the extracardiac conduit Fontan confers an arrhythmia advantage over the intracardiac lateral tunnel Fontan. This multicenter study of 1271 patients compared bradyarrhythmia (defined as need for pacing) and tachyarrhythmia (defined as needing antiarrhythmic therapy) between 602 patients undergoing the intracardiac Fontan and 669 patients undergoing the extracardiac Fontan. The median age at the time of the Fontan procedure was 2.1 years (interquartile range, 1.6-3.2 years) for the intracardiac group and 3.0 years (interquartile range, 2.4-3.9) for the extracardiac group (P 30 days) bradyarrhythmia occurred in 105 patients (18%) in the intracardiac group and 63 patients (9%) in the extracardiac group (P 30 days) tachyarrhythmia occurred in 58 patients (10%) in the intracardiac group and 23 patients (3%) in the extracardiac group (P factoring time since surgery, more patients in the extracardiac group had early bradycardia (odds ratio, 2.9; 95% confidence interval, 1.8-4.6), with no difference in early tachycardia, late bradycardia, or late tachycardia. Overall arrhythmia burden is similar between the 2 groups, but the extracardiac Fontan group had a higher incidence of early bradyarrhythmias. There was no difference in the incidence of late tachyarrhythmias over time between the 2 operations. Therefore, the type of Fontan performed should be based on factors other than an anticipated reduction in arrhythmia burden from the extracardiac conduit. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

An Early Glenn Operation May be Associated with the Later Occurrence of Protein-Losing Enteropathy in Fontan Patients : Association of Early Glenn and Failing Fontan.

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Unseld, Bettina; Stiller, Brigitte; Borth-Bruhns, Thomas; du Bois, Florian; Kroll, Johannes; Grohmann, Jochen; Fleck, Thilo

2017-08-01

Protein-losing enteropathy (PLE) and plastic bronchitis (PB) are major causes of long-term mortality after Fontan operation. The objective of this study was to determine early clinical risk factors before the onset of PLE and PB. In a cohort study, 106 Fontan patients between 2005 and 2013 were examined. A median of 5.3 (1.5-8.5) years later, follow-up questionnaires were used to group the patients in a PLE or PB group (n = 14) and a non-PLE/PB group (n = 92). Prevalence of PLE was 9.4% (n = 10) and of PB 3.8% (n = 4). At follow-up, five patients (4.7%) died of PLE or PB. Median age at death was 6.2 years (IQR 10.5, 95% CI 5.3-23.4). We observed no significant group differences in gender distribution (p = 0.73), ventricular morphology (p = 0.87), surgical technique (p = 0.64), conduit fenestration (p = 0.34), age at Fontan operation (p = 0.54), and need for diuretics (p = 0.56). Hypoplastic left heart syndrome was more frequent in the PLE/PB group 50 vs. 22.8% (p = 0.03) OR 3.4 (95% CI 1.1-10.8). The modified Glenn procedure was performed at a median age of 4 months (IQR 4.0) in the PLE/PB group versus 8 months (IQR 8.0) in the non-PLE/PB group (p = 0.01). The early Glenn procedure and hypoplastic left heart syndrome may be associated with the development of PLE and PB.

Immune Abnormalities in Fontan Protein-Losing Enteropathy: A Case-Control Study.

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Magdo, H Sonali; Stillwell, Terri L; Greenhawt, Matthew J; Stringer, Kathleen A; Yu, Sunkyung; Fifer, Carlen G; Russell, Mark W; Schumacher, Kurt R

2015-08-01

To comprehensively characterize the immunologic characteristics of patients with protein-losing enteropathy (PLE) post-Fontan and compare them with patients without PLE post-Fontan. Patients with PLE post-Fontan and age-matched controls post-Fontan were prospectively studied with laboratory markers of immune function. Infectious history was obtained by interview and chart review. The groups' demographics, cardiac history, immune characteristics, and infection history were compared using appropriate 2-group statistics. A total of 16 patients enrolled (8 patients with PLE and 8 controls). All patients with PLE had lymphopenia compared with 25% of controls (P = .01). All patients with PLE had markedly depressed CD4 T cell counts (median 58 cells/μL) compared with controls (median 450 cells/μL, P = .0002); CD4% was also low in the PLE group (12.3%) and normal in control (36.9%, P = .004). Both groups had mildly depressed CD8 T cells and normal to slightly elevated natural killer and B-cell subsets. A majority of patients with PLE (62.5%) had negative titers to measles, mumps, and rubella vaccination, compared with no control Fontan with a negative titer (P = .03). Despite profoundly low CD4 counts, the frequency of infection was not different between groups with no reported opportunistic infections. Patients with Fontan-associated PLE have extensive quantitative immune abnormalities, particularly CD4 deficiency. These immune abnormalities are similar to those found in non-Fontan patients with PLE caused by intestinal lymphangiectasia. Copyright © 2015 Elsevier Inc. All rights reserved.

Percutaneous transthoracic computed tomography-guided AICD insertion in a patient with extracardiac Fontan conduit.

LENUS (Irish Health Repository)

Murphy, Darra T

2011-02-01

Percutaneous pulmonary venous atrial puncture was performed under computed tomography guidance to successfully place an automated implantable cardiac defibrillator into a 26-year-old patient with extracardiac Fontan conduit who had presented with two out-of-hospital cardiac arrests. The procedure avoided the need for lead placement at thoracotomy.

Neurodevelopmental Outcome and Health-related Quality of Life in Children With Single-ventricle Heart Disease Before Fontan Procedure.

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Reich, Bettina; Heye, Kristina; Tuura, Ruth; Beck, Ingrid; Wetterling, Kristina; Hahn, Andreas; Hofmann, Karoline; Schranz, Dietmar; Akintürk, Hakan; Latal, Beatrice; Knirsch, Walter

2017-12-05

Neurodevelopmental impairment and impaired quality of life constitute a major source of morbidity among children with complex congenital heart disease, in particular for single-ventricle (SV) morphologies. Risk factors and quality of life determining clinical and neurodevelopmental outcome at 2 years of age are examined. In a 2-center cohort study, 48 patients with SV morphology (26 hypoplastic left heart syndrome and 22 other types of univentricular heart defect) have been examined before Fontan procedure between 2010 and 2015. Patients were assessed with the Bayley Scales of Infant and Toddler Development, Third Version (Bayley-III), and the Preschool Children Quality of Life (TAPQOL) questionnaire. A total of 44 patients underwent hybrid procedure (n = 25), Norwood procedure (n = 7), or shunt or banding procedure (n = 12) as first surgery before subsequent bidirectional cavopulmonary anastomosis (n = 48). Median cognitive, language, and motor composite scores on the Bayley-III were 100 (range 65-120), 97 (68-124), and 97 (55-124), respectively. The language composite score was significantly below the norm (P = 0.025). Risk factors for poorer neurodevelopmental outcome were prolonged mechanical ventilation, longer days of hospital stay, and more reinterventions (all P neurodevelopmental outcome of this high-risk patient population. Copyright © 2017 Elsevier Inc. All rights reserved.

Skeletal muscle abnormalities and exercise capacity in adults with a Fontan circulation.

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Cordina, Rachael; O'Meagher, Shamus; Gould, Haslinda; Rae, Caroline; Kemp, Graham; Pasco, Julie A; Celermajer, David S; Singh, Nalin

2013-10-01

The peripheral muscle pump is key in promoting cardiac filling during exercise, especially in subjects who lack a subpulmonary ventricle (the Fontan circulation). A muscle-wasting syndrome exists in acquired heart failure but has not been assessed in Fontan subjects. We sought to investigate whether adults with the Fontan circulation exhibit reduced skeletal muscle mass and/or metabolic abnormalities. Sixteen New York Heart Association Class I/II Fontan adults (30±2 years) underwent cardiopulmonary exercise testing and lean mass quantification with dual x-ray absorptiometry (DXA); eight had calf muscle (31)P magnetic resonance spectroscopy as did eight healthy age-matched and sex-matched controls. DXA results were compared with Australian reference data. Single tertiary referral centre. Peak VO2 was 1.9±0.1 L/min (66±3% of predicted values). Skeletal muscle mass assessed by relative appendicular lean mass index was significantly reduced compared with age-matched and sex-matched reference values (Z-score -1.46±0.22, pskeletal muscle mass correlated with poorer VO2 max (r=0.67, p=0.004). Overall, skeletal muscle mass T-score (derived from comparison with young normal reference mean) was -1.47±0.21; 4/16 Fontan subjects had sarcopenic range muscle wasting (T-score Muscle aerobic capacity, measured by the rate constant (k) of postexercise phosphocreatine resynthesis, was significantly impaired in Fontan adults versus controls (1.48±0.13 vs 2.40±0.33 min(-1), p=0.02). Fontan adults have reduced skeletal muscle mass and intrinsic muscle metabolic abnormalities.

Three cases of hepatocellular carcinoma in Fontan patients: Review of the literature and suggestions for hepatic screening

NARCIS (Netherlands)

Josephus Jitta, Djike; Wagenaar, Lodewijk J.; Mulder, Barbara J. M.; Guichelaar, Maureen; Bouman, Donald; van Melle, Joost P.

2016-01-01

The Fontan procedure has been used since 1971 as a palliative treatment for various (functionally) univentricular hearts. The systemic venous blood flows passively to the pulmonary arteries, without passing through a functional ventricle. This results in chronic systemic venous congestion, which may

Three cases of hepatocellular carcinoma in Fontan patients : Review of the literature and suggestions for hepatic screening

NARCIS (Netherlands)

Jitta, Djike Josephus; Wagenaar, Lodewijk J.; Mulder, Barbara J. M.; Guichelaar, Maureen; Bouman, Donald; Melle, van Joost P.

2016-01-01

The Fontan procedure has been used since 1971 as a palliative treatment for various (functionally) univentricular hearts. The systemic venous blood flows passively to the pulmonary arteries, without passing through a functional ventricle. This results in chronic systemic venous congestion, which may

Contractility-afterload mismatch in patients with protein-losing enteropathy after the Fontan operation.

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Ozawa, Hideto; Ueno, Takayoshi; Iwai, Shigemitsu; Kawata, Hiroaki; Nishigaki, Kyouichi; Kishimoto, Hidefumi; Sawa, Yoshiki

2014-10-01

This study aimed to clarify the relationship between onset of protein-losing enteropathy (PLE) and Fontan circulation, with special reference to the development of contractility-afterload mismatch. The PLE group comprised 9 patients who experienced PLE after undergoing the Fontan operation, and the control group consisted of 32 patients had did not experienced PLE more than 10 years after the Fontan operation. The study compared the pre- and postoperative values of arterial elastance (Ea), end-systolic elastance (Ees), and contractility-afterload mismatch (Ea/Ees). Furthermore, the variations in the values were examined during the preoperative, postoperative, and midterm postoperative periods in seven PLE patients who underwent cardiac catheterization at the onset of PLE and during the pre- and postintervention periods in three PLE patients who underwent surgical intervention to improve the Fontan circulation after the onset of PLE. Comparison of the values obtained before and after Fontan operations showed that the Ea values increased significantly in the PLE group. However, the pre- and postoperative Ees values did not differ in the two groups. During the postoperative period, Ea/Ees increased significantly, and the Ea and Ea/Ees values increased continuously until the onset of PLE in the PLE group. In the patients who underwent surgical intervention to improve the Fontan circulation after the onset of PLE, the Ea/Ees decreased significantly, and the serum albumin levels improved after the intervention. Contractility-afterload mismatch, mainly caused by the increase in the afterload of the systemic ventricle, may have an important role in the development of PLE after the Fontan operation.

Cross-sectional imaging of the Fontan circuit in adult congenital heart disease

International Nuclear Information System (INIS)

Lewis, G.; Thorne, S.; Clift, P.; Holloway, B.

2015-01-01

The Fontan circuit is the result of a palliative surgical procedure that is performed in patients with a functionally single ventricle cardiac anomaly. The success of this operation has resulted in an increasing population of adults with this anatomy and physiology. The purpose of this article is to familiarize the general radiologist with the expected anatomy and cross-sectional imaging findings, highlight special imaging considerations, and examine the common complications that are encountered in this group of patients

CT findings of plastic bronchitis in children after a Fontan operation

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Goo, Hyun Woo [University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Asan Medical Center, Seoul (Korea); Jhang, Won Kyoung; Kim, Young Hwee; Ko, Jae Kon; Park, In Sook [University of Ulsan College of Medicine, Department of Pediatric Cardiology, Asan Medical Center, Seoul (Korea); Park, Jeong-Jun; Yun, Tae-Jin; Seo, Dong-Man [University of Ulsan College of Medicine, Department of Pediatric Cardiac Surgery, Asan Medical Center, Seoul (Korea)

2008-09-15

Plastic bronchitis is a rare cause of acute obstructive respiratory failure in children. Life-threatening events are much more frequent in patients with repaired cyanotic congenital heart disease, and most frequent following a Fontan operation. Commonly, the diagnosis is not made until bronchial casts are expectorated. Detailed CT findings in plastic bronchitis have not been described. To describe the CT findings in plastic bronchitis in children after a Fontan operation. Three children with plastic bronchitis after a Fontan operation were evaluated by chest CT. Bronchial casts were spontaneously expectorated and/or extracted by bronchoscopy. Airway and lung abnormalities seen on CT were analyzed in the three children. CT demonstrated bronchial casts in the central airways with associated atelectasis and consolidation in all children. The affected airways were completely or partially obstructed by the bronchial casts without associated bronchiectasis. The airway and lung abnormalities rapidly improved after removal of the bronchial casts. CT can identify airway and lung abnormalities in children with plastic bronchitis after a Fontan operation. In addition, CT can be used to guide bronchoscopy and to monitor treatment responses, and thereby may improve clinical outcomes. (orig.)

Usefulness of peripheral vascular function to predict functional health status in patients with Fontan circulation.

Science.gov (United States)

Goldstein, Bryan H; Golbus, Jessica R; Sandelin, Angela M; Warnke, Nicole; Gooding, Lindsay; King, Karen K; Donohue, Janet E; Gurney, James G; Goldberg, Caren S; Rocchini, Albert P; Charpie, John R

2011-08-01

After the Fontan operation, patients are at a substantial risk of the development of impaired functional health status. Few early markers of suboptimal outcomes have been identified. We sought to assess the association between peripheral vascular function and functional health status in Fontan-palliated patients. Asymptomatic Fontan patients (n = 51) and age- and gender-matched healthy controls (n = 22) underwent endothelial pulse amplitude testing using a noninvasive fingertip peripheral arterial tonometry (PAT) device. Raw data were transformed into the PAT ratio, an established marker of vascular function. Cardiopulmonary exercise testing was performed using the Bruce protocol. In the Fontan cohort, 94% of patients were New York Heart Association functional class I and 88% had a B-type natriuretic peptide level of interquartile range 1.96 to 4.13 vs median 1.86, interquartile range 1.14 to 2.79, p = 0.03). The PAT ratio, a measure of reactive hyperemia, was lower in Fontan patients (median 0.17, interquartile range -0.04 to 0.44, vs median 0.50, interquartile range 0.27 to 0.74, p = 0.002). The key parameters of exercise performance, including peak oxygen consumption (median 28.8 ml/kg/min, interquartile range 25.6 to 33.2 vs median 45.5 ml/kg/min, interquartile range 41.7 to 49.9, p interquartile range 150 to 246 vs median 330, interquartile range 209 to 402 W, p <0.0001), were lower in Fontan patients than in the controls. The PAT ratio correlated with the peak oxygen consumption (r = 0.28, p = 0.02) and peak work (r = 0.26, p = 0.03). In conclusion, in an asymptomatic Fontan population, there is evidence of reduced basal peripheral arterial tone and vasodilator response, suggesting dysfunction of the endothelium-derived nitric oxide pathway. Vasodilator function appears to correlate with exercise performance. Copyright © 2011 Elsevier Inc. All rights reserved.

Creating a Fontan fenestration in a child with dextrocardia and interrupted inferior vena cava

Directory of Open Access Journals (Sweden)

Pradeepkumar Charlagorla

2016-01-01

Full Text Available Plastic bronchitis is a rare life-threatening complication of the Fontan operation. Transcatheter Fontan fenestration can ameliorate symptoms by decompressing elevated venous pressures. Transcatheter creation of a fenestration can be technically challenging in cases with complex venous anatomy. We report a case of a 5-year-old boy with heterotaxy, dextrocardia with unbalanced atrioventricular canal (AVC, atrial and visceral situs inversus, left-sided superior vena cava (SVC, and left-sided interrupted inferior vena cava (IVC with azygos continuation. With few modifications to the equipment, a successful Fontan fenestration with stent implantation was performed via transjugular approach. At 2-year follow-up, his symptoms of plastic bronchitis improved significantly.

Cardiac magnetic resonance and the need for routine cardiac catheterization in single ventricle patients prior to Fontan: a comparison of 3 groups: pre-Fontan CMR versus cath evaluation.

Science.gov (United States)

Fogel, Mark A; Pawlowski, Thomas W; Whitehead, Kevin K; Harris, Matthew A; Keller, Marc S; Glatz, Andrew C; Zhu, Winnie; Shore, David; Diaz, Laura K; Rome, Jonathan J

2012-09-18

This study investigated whether cardiac magnetic resonance (CMR) and echocardiography (echo) can replace catheterization (cath) for routine evaluation prior to Fontan and under what circumstances CMR and cath are used together. Routine cath prior to Fontan has been utilized for years; noninvasive methods, however, may be sufficient. This study reviews clinical data in 119 consecutive patients investigating 3 groups: those who underwent CMR alone (MR; n = 41), cath alone (C; n = 41), or both cath and CMR (C+M; n = 37) prior to Fontan. No clinically significant differences were noted in patient characteristics, hemodynamics, or clinical status prior to or after surgery between the C and MR groups. CMR added information in 82%. There were no discrepant findings between CMR and cath data in the C+M group. Diagnostic success was ≥95% in all groups. Of those undergoing Fontan completion, the C+M group had similar outcomes to C and MR; C and CMR were utilized in combination to assess aortopulmonary collaterals or the need for an intervention or evaluate its success. Echo could not delineate pulmonary arterial anatomy in 46% to 53% of patients. The C+M and C groups were exposed to 6.8 ± 4.1 mSv of radiation. Single ventricle patients not requiring an intervention can undergo successful Fontan completion with CMR and echo alone with similar short-term outcomes to C, which was used as a control, preventing an invasive test and exposure to radiation. CMR can add information in a significant number of patients. Cath and CMR are utilized together for interventions and assessment of aortopulmonary collaterals. Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

“Will she live a long happy life?” Parents' concerns for their children with Fontan circulation

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Karin du Plessis

2018-03-01

Full Text Available Background: Families of children at the worst end of the congenital heart disease endure a significant burden which is often not clearly delineated in the clinical literature. We examined the greatest concerns of parents whose children have a Fontan circulation. Methods: Parents (N = 107 of children in the Australian and New Zealand Fontan Registry completed online surveys with open-ended and closed questions. A qualitative method approach incorporating thematic analyses was used. Results: The greatest concerns for parents of a child with a Fontan circulation were centered on fear of death for their child and psychosocial well-being, followed by lesser themes around anti-coagulation use, pregnancy and financial burdens. Conclusions: Fear of death and the psychological well-being of their children were the main parental concerns. It highlights the need to clearly communicate information on outcomes to families, and the need for family-focused psychological interventions to improve the psychosocial functioning of both parents and young people. Keywords: Congenital heart disease, Fontan, Parents of children with a Fontan circulation, Qualitative research

Can endurance training improve physical capacity and quality of life in young Fontan patients?

Science.gov (United States)

Hedlund, Eva R; Lundell, Bo; Söderström, Liselott; Sjöberg, Gunnar

2018-03-01

Children after Fontan palliation have reduced exercise capacity and quality of life. Our aim was to study whether endurance training could improve physical capacity and quality of life in Fontan patients. Fontan patients (n=30) and healthy age- and gender-matched control subjects (n=25) performed a 6-minute walk test at submaximal capacity and a maximal cycle ergometer test. Quality of life was assessed with Pediatric Quality of Life Inventory Version 4.0 questionnaires for children and parents. All tests were repeated after a 12-week endurance training programme and after 1 year. Patients had decreased submaximal and maximal exercise capacity (maximal oxygen uptake 35.0±5.1 ml/minute per·kg versus 43.7±8.4 ml/minute·per·kg, pquality of life score (70.9±9.9 versus 85.7±8.0, pimproved their submaximal exercise capacity in a 6-minute walk test (from 590.7±65.5 m to 611.8±70.9 m, pquality of life (pimprove maximal exercise capacity. At follow-up, submaximal exercise capacity had increased further and improved quality of life was sustained. The controls improved their maximal exercise capacity (pquality of life after training. At follow-up, improvement of maximal exercise capacity was sustained. We believe that an individualised endurance training programme for Fontan patients improves submaximal exercise capacity and quality of life in Fontan patients and the effect on quality of life appears to be long-lasting.

Gastrointestinal haemorrhage due to lymphangiectasia caused by protein-losing enteropathy in the Fontan circulation.

Science.gov (United States)

Gras, Pauline; Gottrand, Frédéric; Godart, François

2017-10-01

We report the case of a 14-year-old boy with severe protein-losing enteropathy after Fontan surgery that led to lymphangiectasia, which caused gastrointestinal haemorrhage and required invasive treatment to stop the bleeding. Through this case and a review of the literature on protein-losing enteropathy after Fontan surgery, we highlight a rare and serious presentation of the disease and the difficulties of diagnosis and management.

Endothelin receptor antagonism in single ventricle physiology with fontan palliation: A systematic review and meta-analysis

Directory of Open Access Journals (Sweden)

Gwendolyn Derk

2015-04-01

Conclusions: Bosentan was found to be a safe and well tolerated endothelin receptor antagonist in Fontan patients over 3–6 months of therapy. Bosentan use was associated with improved functional capacity. Future studies with larger sample size and longer duration are warranted to examine the long-term safety and efficacy of endothelin blockade in Fontan physiology.

Fontan Surgical Planning: Previous Accomplishments, Current Challenges, and Future Directions.

Science.gov (United States)

Trusty, Phillip M; Slesnick, Timothy C; Wei, Zhenglun Alan; Rossignac, Jarek; Kanter, Kirk R; Fogel, Mark A; Yoganathan, Ajit P

2018-04-01

The ultimate goal of Fontan surgical planning is to provide additional insights into the clinical decision-making process. In its current state, surgical planning offers an accurate hemodynamic assessment of the pre-operative condition, provides anatomical constraints for potential surgical options, and produces decent post-operative predictions if boundary conditions are similar enough between the pre-operative and post-operative states. Moving forward, validation with post-operative data is a necessary step in order to assess the accuracy of surgical planning and determine which methodological improvements are needed. Future efforts to automate the surgical planning process will reduce the individual expertise needed and encourage use in the clinic by clinicians. As post-operative physiologic predictions improve, Fontan surgical planning will become an more effective tool to accurately model patient-specific hemodynamics.

Trasplante después del Fontan. Aspectos quirúrgicos

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Juan-Miguel Gil-Jaurena

2016-09-01

Conclusiones: Trasplantar a pacientes con Fontan previo es un reto. Podemos anticipar variantes en cada una de las 5 anastomosis previstas. Es recomendable obtener tejido extra del donante (aorta y arco, vena cava superior e innominada, pericardio. Los resultados pueden superponerse a otras series de trasplante cardiaco.

Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery.

Science.gov (United States)

Khairy, Paul; Fernandes, Susan M; Mayer, John E; Triedman, John K; Walsh, Edward P; Lock, James E; Landzberg, Michael J

2008-01-01

To better define determinants of mortality in patients with univentricular physiology, a database registry was created of patients born in 1985 or earlier with Fontan surgery who were followed up at Children's Hospital Boston. A total of 261 patients, 121 of whom (46.4%) were women, had a first Fontan surgery at a median age of 7.9 years: right atrium-to-pulmonary artery connection in 135 (51.7%); right atrium to right ventricle in 25 (9.6%); and total cavopulmonary connection in 101 (38.7%). Over a median of 12.2 years, 76 (29.1%) died, 5 (1.9%) had cardiac transplantation, 5 (1.9%) had Fontan revision, and 21 (8.0%) had Fontan conversion. Perioperative mortality decreased steadily over time and accounted for 68.4% of all deaths. In early survivors, actuarial freedom from death or transplantation was 93.7%, 89.9%, 87.3%, and 82.6% at 5, 10, 15, and 20 years, respectively, with no significant difference between right atrium to pulmonary artery versus total cavopulmonary connection. Late deaths were classified as sudden in 7 patients (9.2%), thromboembolic in 6 (7.9%), heart failure-related in 5 (6.7%), sepsis in 2 (2.6%), and other in 4 (5.2%). Most sudden deaths were of presumed arrhythmic origin with no identifiable predictor. Independent risk factors for thromboembolic death were lack of antiplatelet or anticoagulant therapy (hazard ratio [HR], 91.6; P=0.0041) and clinically diagnosed intracardiac thrombus (HR, 22.7; P=0.0002). Independent predictors of heart failure death were protein-losing enteropathy (HR, 7.1; P=0.0043), single morphologically right ventricle (HR, 10.5; P=0.0429), and higher right atrial pressure (HR, 1.3 per 1 mm Hg; P=0.0016). In perioperative survivors of Fontan surgery, gradual attrition occurs predominantly from thromboembolic, heart failure-related, and sudden deaths.

Experimental investigation of the effects of inserting a bovine venous valve in the inferior vena cava of Fontan circulation

Science.gov (United States)

Santhanakrishnan, Arvind; Johnson, Jacob; Kotz, Monica; Tang, Elaine; Khiabani, Reza; Yoganathan, Ajit; Maher, Kevin

2012-11-01

The Fontan procedure is a palliative surgery performed on patients with single ventricle (SV) congenital heart defects. The SV is used for systemic circulation and the venous return from the inferior vena cava (IVC) and superior vena cava (SVC) is routed to the pulmonary arteries (PA), resulting in a total cavopulmonary connection (TCPC). Hepatic venous hypertension is commonly manifested in the Fontan circulation, leading to long-term complications including liver congestion and cirrhosis. Respiratory intrathoracic pressure changes affect the venous return from the IVC to the PA. Using a physical model of an idealized TCPC, we examine placement of a unidirectional bovine venous valve within the IVC as a method of alleviating hepatic venous hypertension. A piston pump is used to provide pulsatility in the internal flow through the TCPC, while intrathoracic pressure fluctuations are imposed on the external walls of the model using a pair of linear actuators. When implanted in the extrathoracic position, the hepatic venous pressure is lowered from baseline condition. The effects of changing caval flow distribution and intrathoracic pressure on TCPC hemodynamics will be examined.

Simulation of Ventricular, Cavo-Pulmonary, and Biventricular Ventricular Assist Devices in Failing Fontan.

Science.gov (United States)

Di Molfetta, Arianna; Amodeo, Antonio; Fresiello, Libera; Trivella, Maria Giovanna; Iacobelli, Roberta; Pilati, Mara; Ferrari, Gianfranco

2015-07-01

Considering the lack of donors, ventricular assist devices (VADs) could be an alternative to heart transplantation for failing Fontan patients, in spite of the lack of experience and the complex anatomy and physiopathology of these patients. Considering the high number of variables that play an important role such as type of Fontan failure, type of VAD connection, and setting (right VAD [RVAD], left VAD [LVAD], or biventricular VAD [BIVAD]), a numerical model could be useful to support clinical decisions. The aim of this article is to develop and test a lumped parameter model of the cardiovascular system simulating and comparing the VAD effects on failing Fontan. Hemodynamic and echocardiographic data of 10 Fontan patients were used to simulate the baseline patients' condition using a dedicated lumped parameter model. Starting from the simulated baseline and for each patient, a systolic dysfunction, a diastolic dysfunction, and an increment of the pulmonary vascular resistance were simulated. Then, for each patient and for each pathology, the RVAD, LVAD, and BIVAD implantations were simulated. The model can reproduce patients' baseline well. In the case of systolic dysfunction, the LVAD unloads the single ventricle and increases the cardiac output (CO) (35%) and the arterial systemic pressure (Pas) (25%). With RVAD, a decrement of inferior vena cava pressure (Pvci) (39%) was observed with 34% increment of CO, but an increment of the single ventricle external work (SVEW). With the BIVAD, an increment of Pas (29%) and CO (37%) was observed. In the case of diastolic dysfunction, the LVAD increases CO (42%) and the RVAD decreases the Pvci, while both increase the SVEW. In the case of pulmonary vascular resistance increment, the highest CO (50%) and Pas (28%) increment is obtained with an RVAD with the highest decrement of Pvci (53%) and an increment of the SVEW but with the lowest VAD power consumption. The use of numerical models could be helpful in this innovative

Quantitative echocardiographic measures in the assessment of single ventricle function post-Fontan: Incorporation into routine clinical practice.

Science.gov (United States)

Rios, Rodrigo; Ginde, Salil; Saudek, David; Loomba, Rohit S; Stelter, Jessica; Frommelt, Peter

2017-01-01

Quantitative echocardiographic measurements of single ventricular (SV) function have not been incorporated into routine clinical practice. A clinical protocol, which included quantitative measurements of SV deformation (global circumferential and longitudinal strain and strain rate), standard deviation of time to peak systolic strain, myocardial performance index (MPI), dP/dT from an atrioventricular valve regurgitant jet, and superior mesenteric artery resistance index, was instituted for all patients with a history of Fontan procedure undergoing echocardiography. All measures were performed real time during clinically indicated studies and were included in clinical reports. A total of 100 consecutive patients (mean age = 11.95±6.8 years, range 17 months-31.3 years) completed the protocol between September 1, 2014 to April 29, 2015. Deformation measures were completed in 100% of the studies, MPI in 93%, dP/dT in 55%, and superior mesenteric artery Doppler in 82%. The studies were reviewed to assess for efficiency in completing the protocol. The average time for image acquisition was 27.4±8.8 (range 10-62 minutes). The average time to perform deformation measures was 10.8±5.5 minutes (range 5-35 minutes) and time from beginning of imaging to report completion was 53.4±13.7 minutes (range 27-107 minutes). There was excellent inter-observer reliability when deformation indices were blindly repeated. Patients with a single left ventricle had significantly higher circumferential strain and strain rate, longitudinal strain and strain rate, and dP/dT compared to a single right ventricle. There were no differences in quantitative indices of ventricular function between patients 10 years post-Fontan. Advanced quantitative assessment of SV function post-Fontan can be consistently and efficiently performed real time during clinically indicated echocardiograms with excellent reliability. © 2016, Wiley Periodicals, Inc.

Fontan-associated protein-losing enteropathy and heart transplant: A Pediatric Heart Transplant Study analysis.

Science.gov (United States)

Schumacher, Kurt R; Gossett, Jeffrey; Guleserian, Kristine; Naftel, David C; Pruitt, Elizabeth; Dodd, Debra; Carboni, Michael; Lamour, Jacqueline; Pophal, Stephen; Zamberlan, Mary; Gajarski, Robert J

2015-09-01

Post-Fontan protein-losing enteropathy (PLE) is associated with significant morbidity and mortality. Although heart transplantation (HTx) can be curative, PLE may increase the risk of morbidity before and after HTx. This study analyzed the influence of PLE influence on waiting list and post-HTx outcomes in a pediatric cohort. Fontan patients listed for HTx and enrolled in the Pediatric Heart Transplant Study from 1999 to 2012 were stratified by a diagnosis of PLE, and the association of PLE with waiting list and post-HTx mortality, rejection, and infection was analyzed. Compared with non-PLE Fontan patients (n = 260), PLE patients listed for HTx (n = 96) were older (11.9 years vs 7.6 years; p = 0.003), had a larger body surface area (1.1 m(2) vs 0.9 m(2); p = 0.0001), had lower serum bilirubin (0.5 vs 0.9 mg/dl; p = 0.01), lower B-type natriuretic peptide (59 vs 227 pg/ml; p = 0.006), and were less likely to be on a ventilator (3% vs 13%; p = 0.006). PLE patients had lower waiting list mortality than non-PLE Fontan patients (p PLE was not independently associated with increased post-HTx mortality at any time point. In this multicenter cohort, the diagnosis of PLE alone was not associated with increased waiting list mortality or post-HTx morbidity or mortality. Given the limitations of our data, this analysis suggests that PLE patients in the pediatric age group have outcomes similar to their non-PLE counterparts. Additional multicenter studies of PLE patients with targeted collection of PLE-specific information will be necessary to fully delineate the risks conferred by PLE for HTx. Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

What Limits Cardiac Performance during Exercise in Normal Subjects and in Healthy Fontan Patients?

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André La Gerche

2010-01-01

Full Text Available Exercise is an important determinant of health but is significantly reduced in the patient with a univentricular circulation. Normal exercise physiology mandates an increase in pulmonary artery pressures which places an increased work demand on the right ventricle (RV. In a biventricular circulation with pathological increases in pulmonary vascular resistance and/or reductions in RV function, exercise-induced augmentation of cardiac output is limited. Left ventricular preload reserve is dependent upon flow through the pulmonary circulation and this requires adequate RV performance. In the Fontan patient, the reasons for exercise intolerance are complex. In those patients with myocardial dysfunction or other pathologies of the circulatory components, it is likely that these abnormalities serve as a limitation to cardiac performance during exercise. However, in the healthy Fontan patient, it may be the absence of a sub-pulmonary pump which limits normal increases in pulmonary pressures, trans-pulmonary flow requirements and cardiac output. If so, performance will be exquisitely dependent on pulmonary vascular resistance. This provides a potential explanation as to why pulmonary vasodilators may improve exercise tolerance. As has recently been demonstrated, these agents may offer an important new treatment strategy which directly addresses the physiological limitations in the Fontan patient.

Fontan-associated protein-losing enteropathy and plastic bronchitis: characterizing current-era risk factors, course, and progression

Science.gov (United States)

Schumacher, Kurt R.; Stringer, Kathleen A.; Donohue, Janet E.; Yu, Sunkyung; Shaver, Ashley; Caruthers, Regine L.; Zikmund-Fisher, Brian J.; Fifer, Carlen; Goldberg, Caren; Russell, Mark W.

2015-01-01

Objective Characterize the medical history, disease progression, and treatment of current-era patients with the rare diseases Fontan-associated protein losing enteropathy (PLE) and plastic bronchitis (PB). Study Design A novel survey that queried demographics, medical details, and treatment information was piloted and placed online via a Facebook portal allowing social media to power the study. Participation regardless of PLE or PB diagnosis was allowed. Case control analyses compared patients with PLE and PB to uncomplicated control Fontan patients. Results The survey was completed by 671 subjects including 76 with PLE, 46 with PB, and 7 with both. Median PLE diagnosis was 2.5 years post-Fontan. Hospitalization for PLE occurred in 71% with 41% hospitalized ≥ 3 times. Therapy varied significantly. PLE patients more commonly had hypoplastic left ventricle (62% vs 44% control; OR 2.8, 95% CI 1.4–5.5), chylothorax (66% vs 41%; OR 3.0, CI 1.6–5.3), and cardiothoracic surgery in addition to staged palliation (17% vs 5%; OR 4.3, CI 1.6, 11.2). Median PB diagnosis was 2 years post-Fontan. Hospitalization for PB occurred in 91% with 61% hospitalized ≥3 times. Therapy was very diverse. PB patients more commonly had chylothorax at any surgery (72% vs 51%; OR 2.5, CI 1.2–5.1) and seasonal allergies (52% vs 36%; OR 2.0, CI 1.0–3.9). Conclusions Patient-specific factors are associated with diagnoses of PLE or PB. Treatment strategies are diverse without clear patterns. These results provide a foundation upon which to design future therapeutic studies and identify a clear need for forming consensus approaches to treatment. PMID:25661406

A surrogate based multistage-multilevel optimization procedure for multidisciplinary design optimization

OpenAIRE

Yao, W.; Chen, X.; Ouyang, Q.; Van Tooren, M.

2011-01-01

Optimization procedure is one of the key techniques to address the computational and organizational complexities of multidisciplinary design optimization (MDO). Motivated by the idea of synthetically exploiting the advantage of multiple existing optimization procedures and meanwhile complying with the general process of satellite system design optimization in conceptual design phase, a multistage-multilevel MDO procedure is proposed in this paper by integrating multiple-discipline-feasible (M...

Hepatic blood flow distribution and performance in conventional and novel Y-graft Fontan geometries: a case series computational fluid dynamics study.

Science.gov (United States)

Yang, Weiguang; Vignon-Clementel, Irene E; Troianowski, Guillaume; Reddy, V Mohan; Feinstein, Jeffrey A; Marsden, Alison L

2012-05-01

A novel Y-shaped baffle has been proposed for the Fontan operation with promising initial results. However, previous studies have relied either on idealized models or a single patient-specific model. The objective of this study is to comprehensively compare the hemodynamic performance and hepatic blood flow distribution of the Y-graft Fontan baffle with 2 current designs using multiple patient-specific models. Y-shaped and tube-shaped grafts were virtually implanted into 5 patient-specific Glenn models forming 3 types of Fontan geometries: Y-graft, T-junction, and offset. Unsteady flow simulations were performed at rest and at varying exercise conditions. The hepatic flow distribution between the right and left lungs was carefully quantified using a particle tracking method. Other physiologically relevant parameters such as energy dissipation, superior vena cava pressure, and wall shear stress were evaluated. The Fontan geometry significantly influences the hepatic flow distribution. The Y-graft design improves the hepatic flow distribution effectively in 4 of 5 patients, whereas the T-junction and offset designs may skew as much as 97% of hepatic flow to 1 lung in 2 cases. Sensitivity studies show that changes in pulmonary flow split can affect the hepatic flow distribution dramatically but that some Y-graft and T-junction designs are relatively less sensitive than offset designs. The Y-graft design offers moderate improvements over the traditional designs in power loss and superior vena cava pressure in all patients. The Y-graft Fontan design achieves overall superior hemodynamic performance compared with traditional designs. However, the results emphasize that no one-size-fits-all solution is available that will universally benefit all patients and that designs should be customized for individual patients before clinical application. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

New insights into the aspects of pulmonary diffusing capacity in Fontan patients

DEFF Research Database (Denmark)

Idorn, Lars; Hanel, Birgitte; Jensen, Annette S

2014-01-01

by 48.3 ± 17.4% in the Fontan group and by 20.2 ± 13.9% in the control group (p = 0.001). In a multiple linear regression analysis including the explanatory variables of surgical data and exercise data at rest and peak exercise, the resting cardiac index was an independent predictor of the diffusing...

Evaluation of blood flow distribution asymmetry and vascular geometry in patients with Fontan circulation using 4-D flow MRI

International Nuclear Information System (INIS)

Jarvis, Kelly; Markl, Michael; Schnell, Susanne; Barker, Alex J.; Garcia, Julio; Chowdhary, Varun; Carr, James; Lorenz, Ramona; Rose, Michael; Robinson, Joshua D.; Rigsby, Cynthia K.

2016-01-01

Asymmetrical caval to pulmonary blood flow is suspected to cause complications in patients with Fontan circulation. The aim of this study was to test the feasibility of 4-D flow MRI for characterizing the relationship between 3-D blood flow distribution and vascular geometry. We hypothesized that both flow distribution and geometry can be calculated with low interobserver variability and will detect a direct relationship between flow distribution and Fontan geometry. Four-dimensional flow MRI was acquired in 10 Fontan patients (age: 16 ± 4 years [mean ± standard deviation], range: 9-21 years). The Fontan connection was isolated by 3-D segmentation to evaluate flow distribution from the inferior vena cava (IVC) and superior vena cava (SVC) to the left and right pulmonary arteries (LPA, RPA) and to characterize geometry (cross-sectional area, caval offset, vessel angle). Flow distribution results indicated SVC flow tended toward the RPA while IVC flow was more evenly distributed (SVC to RPA: 78% ± 28 [9-100], IVC to LPA: 54% ± 28 [4-98]). There was a significant relationship between pulmonary artery cross-sectional area and flow distribution (IVC to RPA: R"2=0.50, P=0.02; SVC to LPA: R"2=0.81, P=0.0004). Good agreement was found between observers and for flow distribution when compared to net flow values. Four-dimensional flow MRI was able to detect relationships between flow distribution and vessel geometry. Future studies are warranted to investigate the potential of patient specific hemodynamic analysis to improve diagnostic capability. (orig.)

Evaluation of blood flow distribution asymmetry and vascular geometry in patients with Fontan circulation using 4-D flow MRI

Energy Technology Data Exchange (ETDEWEB)

Jarvis, Kelly; Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Northwestern University, Department of Biomedical Engineering, McCormick School of Engineering, Chicago, IL (United States); Schnell, Susanne; Barker, Alex J.; Garcia, Julio; Chowdhary, Varun; Carr, James [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Lorenz, Ramona [University Medical Center Freiburg, Department of Radiology, Freiburg (Germany); Rose, Michael [Ann and Robert H. Lurie Children' s Hospital of Chicago, Department of Medical Imaging, Chicago, IL (United States); Robinson, Joshua D. [Northwestern University, Department of Pediatrics, Feinberg School of Medicine, Chicago, IL (United States); Ann and Robert H. Lurie Children' s Hospital of Chicago, Division of Cardiology, Chicago, IL (United States); Rigsby, Cynthia K. [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Ann and Robert H. Lurie Children' s Hospital of Chicago, Department of Medical Imaging, Chicago, IL (United States)

2016-10-15

Asymmetrical caval to pulmonary blood flow is suspected to cause complications in patients with Fontan circulation. The aim of this study was to test the feasibility of 4-D flow MRI for characterizing the relationship between 3-D blood flow distribution and vascular geometry. We hypothesized that both flow distribution and geometry can be calculated with low interobserver variability and will detect a direct relationship between flow distribution and Fontan geometry. Four-dimensional flow MRI was acquired in 10 Fontan patients (age: 16 ± 4 years [mean ± standard deviation], range: 9-21 years). The Fontan connection was isolated by 3-D segmentation to evaluate flow distribution from the inferior vena cava (IVC) and superior vena cava (SVC) to the left and right pulmonary arteries (LPA, RPA) and to characterize geometry (cross-sectional area, caval offset, vessel angle). Flow distribution results indicated SVC flow tended toward the RPA while IVC flow was more evenly distributed (SVC to RPA: 78% ± 28 [9-100], IVC to LPA: 54% ± 28 [4-98]). There was a significant relationship between pulmonary artery cross-sectional area and flow distribution (IVC to RPA: R{sup 2}=0.50, P=0.02; SVC to LPA: R{sup 2}=0.81, P=0.0004). Good agreement was found between observers and for flow distribution when compared to net flow values. Four-dimensional flow MRI was able to detect relationships between flow distribution and vessel geometry. Future studies are warranted to investigate the potential of patient specific hemodynamic analysis to improve diagnostic capability. (orig.)

A surrogate based multistage-multilevel optimization procedure for multidisciplinary design optimization

NARCIS (Netherlands)

Yao, W.; Chen, X.; Ouyang, Q.; Van Tooren, M.

2011-01-01

Optimization procedure is one of the key techniques to address the computational and organizational complexities of multidisciplinary design optimization (MDO). Motivated by the idea of synthetically exploiting the advantage of multiple existing optimization procedures and meanwhile complying with

AngioVac Aspiration for Paradoxical Emboli Protection through a Fenestrated Fontan During Central Venous Thrombus Manipulation

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Al-Hakim, Ramsey, E-mail: ralhakim@mednet.ucla.edu [University of California, Department of Radiology, Division of Interventional Radiology (United States); Patel, Komal, E-mail: kdpatel@mednet.ucla.edu [University of California, Department of Anesthesiology, Division of Cardiothoracic Anesthesiology (United States); Moriarty, John M., E-mail: jmoriarty@mednet.ucla.edu [University of California, Department of Radiology, Division of Interventional Radiology (United States)

2015-06-15

This case reports describes a 39-year-old female with a history of surgically repaired hypoplastic left heart syndrome who presented with a left peripherally inserted central catheter (PICC) with associated large volume subclavian and brachiocephalic vein thrombus. Due to the presence of a right-to-left shunt via a fenestrated Fontan, there was clinical concern for a paradoxical embolism during removal of the PICC. The AngioVac aspiration system was successfully utilized to aspirate thromboemboli from the level of the proximal Glenn shunt during manipulation and removal of the PICC. This is the first reported case to demonstrate the safe and effective use of the AngioVac aspiration system for protection of paradoxical emboli through a cardiac right-to-left shunt during a procedure at high risk for thromboembolism.

Oral budesonide treatment for protein-losing enteropathy in Fontan-palliated patients.

Science.gov (United States)

Schumacher, Kurt R; Cools, Michael; Goldstein, Bryan H; Ioffe-Dahan, Viktoriya; King, Karen; Gaffney, Diane; Russell, Mark W

2011-10-01

Protein-losing enteropathy (PLE) is a rare complication of Fontan palliation associated with significant morbidity and mortality. It is characterized by the loss of serum proteins into the intestinal lumen, and its pathophysiology likely involves enteral inflammation. Budesonide, an oral steroid, is an attractive treatment option because of its potent enteral activity and minimal systemic side effects. A single-center, retrospective review of Fontan-palliated PLE patients treated with oral budesonide for 6 months or longer was performed. The patient characteristics reviewed were demographics, anatomic diagnosis, budesonide treatment (dose and duration), other medications and therapeutic interventions, hospitalizations, serum albumin levels, medical complications, and patient status at the time of follow-up assessment. The study enrolled 10 patients representing 228 patient-months of on-therapy follow-up evaluation. Serum albumin levels increased after initiation of budesonide for 90% of the patients, and clinical evidence of fluid overload improved for 60% of them. Symptomatic improvement was reported in 80% of the cases. During the treatment period, 50% of the patients met the primary end point of death or cardiac transplantation. In this series of PLE patients, oral budesonide therapy was associated with significant symptomatic improvement and sustained increases in serum albumin. However, budesonide therapy may not alter the long-term outcome for patients with advanced PLE.

Quantification of ventricular unloading by 3D echocardiography in single ventricle of left ventricular morphology following superior cavo-pulmonary anastomosis and Fontan completion – a feasibility study

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Deepa Sasikumar

2017-01-01

Conclusions: We provide preliminary information on 3DE volume data of single ventricle of LV morphology and the pattern of unloading after SCPA and Fontan operation. Immediate significant volume unloading occurred after SCPA which tended to catch-up after 3 months, whereas continued fall in ventricular volume with time was noted after Fontan.

Towards a Tissue-Engineered Contractile Fontan-Conduit: The Fate of Cardiac Myocytes in the Subpulmonary Circulation.

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Daniel Biermann

Full Text Available The long-term outcome of patients with single ventricles improved over time, but remains poor compared to other congenital heart lesions with biventricular circulation. Main cause for this unfavourable outcome is the unphysiological hemodynamic of the Fontan circulation, such as subnormal systemic cardiac output and increased systemic-venous pressure. To overcome this limitation, we are developing the concept of a contractile extracardiac Fontan-tunnel. In this study, we evaluated the survival and structural development of a tissue-engineered conduit under in vivo conditions. Engineered heart tissue was generated from ventricular heart cells of neonatal Wistar rats, fibrinogen and thrombin. Engineered heart tissues started beating around day 8 in vitro and remained contractile in vivo throughout the experiment. After culture for 14 days constructs were implanted around the right superior vena cava of Wistar rats (n = 12. Animals were euthanized after 7, 14, 28 and 56 days postoperatively. Hematoxylin and eosin staining showed cardiomyocytes arranged in thick bundles within the engineered heart tissue-conduit. Immunostaining of sarcomeric actin, alpha-actin and connexin 43 revealed a well -developed cardiac myocyte structure. Magnetic resonance imaging (d14, n = 3 revealed no constriction or stenosis of the superior vena cava by the constructs. Engineered heart tissues survive and contract for extended periods after implantation around the superior vena cava of rats. Generation of larger constructs is warranted to evaluate functional benefits of a contractile Fontan-conduit.

Controller tuning with evolutionary multiobjective optimization a holistic multiobjective optimization design procedure

CERN Document Server

Reynoso Meza, Gilberto; Sanchis Saez, Javier; Herrero Durá, Juan Manuel

2017-01-01

This book is devoted to Multiobjective Optimization Design (MOOD) procedures for controller tuning applications, by means of Evolutionary Multiobjective Optimization (EMO). It presents developments in tools, procedures and guidelines to facilitate this process, covering the three fundamental steps in the procedure: problem definition, optimization and decision-making. The book is divided into four parts. The first part, Fundamentals, focuses on the necessary theoretical background and provides specific tools for practitioners. The second part, Basics, examines a range of basic examples regarding the MOOD procedure for controller tuning, while the third part, Benchmarking, demonstrates how the MOOD procedure can be employed in several control engineering problems. The fourth part, Applications, is dedicated to implementing the MOOD procedure for controller tuning in real processes.

Echocardiographic characteristics in Fontan patients before the onset of protein-losing enteropathy or plastic bronchitis.

Science.gov (United States)

Du Bois, Florian; Stiller, Brigitte; Borth-Bruhns, Thomas; Unseld, Bettina; Kubicki, Rouven; Hoehn, René; Reineker, Katja; Grohmann, Jochen; Fleck, Thilo

2018-01-01

It was this study's objective to evaluate the echocardiographic characteristics and flow patterns in abdominal arteries of Fontan patients before the onset of protein-losing enteropathy (PLE) or plastic bronchitis (PB). In this retrospective cohort investigation, we examined 170 Fontan patients from 32 different centers who had undergone echocardiographic and Doppler ultrasound examinations between June 2006 and May 2013. Follow-up questionnaires were completed by 105 patients a median of 5.3 (1.5-8.5) years later to evaluate whether one of the complications had occurred since the examinations. A total of 91 patients never developed PLE or PB ("non-PLE/PB"); they were compared to 14 affected patients. Eight of the 14 patients had already been diagnosed with "present PLE/PB" when examined. Six "future PLE/PB" patients developed those complications later on and were identified on follow-up. The "future PLE/PB" patients presented significantly slower diastolic flow velocities in the celiac artery (0.1 (0.1-0.5) m/s vs 0.3 (0.1-1.0) m/s (P = .04) and in the superior mesenteric artery (0.0 (0.0-0.2) m/s vs 0.2 (0.0-0.6) m/s, P = .02) than the "non-PLE/PB" group. Median resistance indices in the celiac artery were significantly higher (0.9 (0.8-0.9) m/s vs 0.8 (0.6-0.9) m/s, (P = .01)) even before the onset of PLE or PB. An elevated flow resistance in the celiac artery may prevail in Fontan patients before the clinical manifestation of PLE or PB. © 2017 Wiley Periodicals, Inc.

Challenges of management and therapy in patients with a functionally single ventricle after Fontan operation.

Science.gov (United States)

Trojnarska, Olga; Ciepłucha, Aleksandra

2011-01-01

Forty years ago, Fontan and Baudet performed the first life-saving operation on a patient with a functionally single ventricle. This multi-stage procedure established the connection between systemic venous circulation and pulmonary arteries. As a consequence, the pulmonary circulation is supplied in a passive way, whereas the single ventricle pumps the blood into the systemic circulation only. Over the years, the technique of creating the abovementioned vascular connections has undergone several modifications. Due to the fundamental non-physiological hemodynamic relations between arterial pulmonary and systemic venous pressures, numerous complications can be observed in these patients including: supraventricular arrhythmias, thromboemboli, hepatic dysfunction, protein-losing enteropathy, heart failure, worsening cyanosis, systemic venous collateralization, and pulmonary arteriovenous malformations, as well as connective tissue lesions in bronchi. Although based on an ingenious concept, the operation remains of a palliative character. Occasionally, heart transplantation is the ultimate resolution. Pharmacological therapy, and surgical conversion, often appear to be ineffective. However, this procedure has enabled many patients to reach adulthood and enjoy their lives to the full. This fact poses a great challenge for cardiologists wishing to become more knowledgeable and experienced as regards such patients, if we are not to waste such fabulous surgical achievements.

Efficient Reanalysis Procedures in Structural Topology Optimization

DEFF Research Database (Denmark)

Amir, Oded

This thesis examines efficient solution procedures for the structural analysis problem within topology optimization. The research is motivated by the observation that when the nested approach to structural optimization is applied, most of the computational effort is invested in repeated solutions...... on approximate reanalysis. For cases where memory limitations require the utilization of iterative equation solvers, we suggest efficient procedures based on alternative termination criteria for such solvers. These approaches are tested on two- and three-dimensional topology optimization problems including...

Procedure and methodology of Radiation Protection optimization

International Nuclear Information System (INIS)

Wang Hengde

1995-01-01

Optimization of Radiation Protection is one of the most important principles in the system of radiation protection. The paper introduces the basic principles of radiation protection optimization in general, and the procedure of implementing radiation protection optimization and methods of selecting the optimized radiation protection option in details, in accordance with ICRP 55. Finally, some economic concepts relating to estimation of costs are discussed briefly

Analysis and optimization of blood-testing procedures.

NARCIS (Netherlands)

Bar-Lev, S.K.; Boxma, O.J.; Perry, D.; Vastazos, L.P.

2017-01-01

This paper is devoted to the performance analysis and optimization of blood testing procedures. We present a queueing model of two queues in series, representing the two stages of a blood-testing procedure. Service (testing) in stage 1 is performed in batches, whereas it is done individually in

Practice Variation in Single-Ventricle Patients Undergoing Elective Cardiac Catheterization: A Report from the Congenital Cardiac Catheterization Project on Outcomes (C3PO).

Science.gov (United States)

Goldstein, Bryan H; Holzer, Ralf J; Trucco, Sara M; Porras, Diego; Murphy, Joshua; Foerster, Susan R; El-Said, Howaida G; Beekman, Robert H; Bergersen, Lisa

2016-01-01

The objective of this study was to investigate variation in practice surrounding elective cardiac catheterization in patients with single-ventricle (SV) congenital heart disease. Patient and procedural characteristics and outcomes during SV catheterization were collected prospectively from eight centers using a web-based registry (Congenital Cardiac Catheterization Project on Outcomes). We attempted to identify a population of elective procedures by limiting the cohort in case type and timing. Cases were then stratified by stage of SV palliation (pre-bidirectional cavopulmonary anastomosis [pre-BCPA], pre-Fontan and post-Fontan) and limited by age. Subcohort analysis was performed by mode of airway management (assisted vs. spontaneous ventilation). Institutional variation was assessed. Between 2/2007 and 6/2010, 1459 (10.1%) of 14 467 cases in the registry met the inclusion and exclusion criteria, including 326 pre-BCPA, 571 pre-Fontan and 562 post-Fontan procedures. Median patient age was 0.4 (interquartile range 0.3, 0.5), 2.6 (1.0, 3.4) and 9.6 (5.2, 15.4) years and weight was 5.6 (4.8, 6.4), 12.2 (10.5, 14), and 26.3 (16.6, 51.8) kg in the pre-BCPA, pre-Fontan and post-Fontan cohorts, respectively. Cases were more commonly diagnostic in the pre-BCPA cohort (57%) whereas they were more commonly interventional in the pre-Fontan (69%) and post-Fontan (77%) cohorts. At least one adverse event (AE) occurred in 210 cases (14.4%) overall, including 20% of pre-BCPA, 11% of pre-Fontan and 14% of post-Fontan catheterizations. Mode of airway management was associated with statistically significant, but clinically small differences in hemodynamic measures in the pre- and post-Fontan cohorts, but not in the pre-BCPA group. Considerable practice variation exists across centers with variability in airway management, AE rate, case type, interventions performed and fluoroscopy time, in all SV cohorts. Elective catheterization in SV patients, frequently performed with

A procedure for multi-objective optimization of tire design parameters

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Nikola Korunović

2015-04-01

Full Text Available The identification of optimal tire design parameters for satisfying different requirements, i.e. tire performance characteristics, plays an essential role in tire design. In order to improve tire performance characteristics, formulation and solving of multi-objective optimization problem must be performed. This paper presents a multi-objective optimization procedure for determination of optimal tire design parameters for simultaneous minimization of strain energy density at two distinctive zones inside the tire. It consists of four main stages: pre-analysis, design of experiment, mathematical modeling and multi-objective optimization. Advantage of the proposed procedure is reflected in the fact that multi-objective optimization is based on the Pareto concept, which enables design engineers to obtain a complete set of optimization solutions and choose a suitable tire design. Furthermore, modeling of the relationships between tire design parameters and objective functions based on multiple regression analysis minimizes computational and modeling effort. The adequacy of the proposed tire design multi-objective optimization procedure has been validated by performing experimental trials based on finite element method.

Usefulness of the Guglielmi detachable coil for embolization of a systemic venous collateral after Fontan operation: A case report.

Science.gov (United States)

Sonomura, Tetsuo; Ikoma, Akira; Kawai, Nobuyuki; Suenaga, Tomohiro; Takeuchi, Takashi; Suzuki, Hiroyuki; Uchita, Shunji; Nakai, Motoki; Minamiguchi, Hiroki; Kishi, Kazushi; Sato, Morio

2012-09-28

Embolization of collateral veins is often treated with rigid coils (Gianturco and interlocking detachable coils type). However, when dealing with tortuous and dilated collateral veins, there is a high risk for technical failure and coil migration due to inflexibility of the coils. To safely and successfully solve this problem, Guglielmi detachable coils (GDC) can be used for embolization. Their flexibility allows for easy navigation in tortuous veins, low risk of unintended coil release or coil migration, and safe deployment. A 12-year-old girl with a single ventricle had severe cyanosis and a low exercise tolerance 5 years after Fontan procedure. The symptoms were caused by a tortuous and dilated collateral from the left phrenic vein into the left pulmonary vein, forming a right-to-left shunt. The collateral, which had a large diameter and high flow, and therefore a high risk of coil migration, was successfully embolized with 8 GDC. There were no complications such as coil migration or cerebral infarction. Transcatheter embolization increased her systemic oxygen saturation from 81%-84% to 94%-95%, and increased her ability to exercise. The embolization procedure using flexible GDC was low risk compared with other rigid coil embolization techniques when performing embolization of tortuous and dilated collateral veins.

Impact of empiric nesiritide or milrinone infusion on early postoperative recovery after Fontan surgery: a randomized, double-blind, placebo-controlled trial.

Science.gov (United States)

Costello, John M; Dunbar-Masterson, Carolyn; Allan, Catherine K; Gauvreau, Kimberlee; Newburger, Jane W; McGowan, Francis X; Wessel, David L; Mayer, John E; Salvin, Joshua W; Dionne, Roger E; Laussen, Peter C

2014-07-01

We sought to determine whether empirical nesiritide or milrinone would improve the early postoperative course after Fontan surgery. We hypothesized that compared with milrinone or placebo, patients assigned to receive nesiritide would have improved early postoperative outcomes. In a single-center, randomized, double-blinded, placebo-controlled, multi-arm parallel-group clinical trial, patients undergoing primary Fontan surgery were assigned to receive nesiritide, milrinone, or placebo. A loading dose of study drug was administered on cardiopulmonary bypass followed by a continuous infusion for ≥12 hours and ≤5 days after cardiac intensive care unit admission. The primary outcome was days alive and out of the hospital within 30 days of surgery. Secondary outcomes included measures of cardiovascular function, renal function, resource use, and adverse events. Among 106 enrolled subjects, 35, 36, and 35 were randomized to the nesiritide, milrinone, and placebo groups, respectively, and all were analyzed based on intention to treat. Demographics, patient characteristics, and operative factors were similar among treatment groups. No significant treatment group differences were found for median days alive and out of the hospital within 30 days of surgery (nesiritide, 20 [minimum to maximum, 0-24]; milrinone, 18 [0-23]; placebo, 20 [0-23]; P=0.38). Treatment groups did not significantly differ in cardiac index, arrhythmias, peak lactate, inotropic scores, urine output, duration of mechanical ventilation, intensive care or chest tube drainage, or adverse events. Compared with placebo, empirical perioperative nesiritide or milrinone infusions are not associated with improved early clinical outcomes after Fontan surgery. http://www.clinicaltrials.gov. Unique identifier: NCT00543309. © 2014 American Heart Association, Inc.

Improving the efficiency of aerodynamic shape optimization procedures

Science.gov (United States)

Burgreen, Greg W.; Baysal, Oktay; Eleshaky, Mohamed E.

1992-01-01

The computational efficiency of an aerodynamic shape optimization procedure which is based on discrete sensitivity analysis is increased through the implementation of two improvements. The first improvement involves replacing a grid point-based approach for surface representation with a Bezier-Bernstein polynomial parameterization of the surface. Explicit analytical expressions for the grid sensitivity terms are developed for both approaches. The second improvement proposes the use of Newton's method in lieu of an alternating direction implicit (ADI) methodology to calculate the highly converged flow solutions which are required to compute the sensitivity coefficients. The modified design procedure is demonstrated by optimizing the shape of an internal-external nozzle configuration. A substantial factor of 8 decrease in computational time for the optimization process was achieved by implementing both of the design improvements.

A PROCEDURE FOR DETERMINING OPTIMAL FACILITY LOCATION AND SUB-OPTIMAL POSITIONS

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P.K. Dan

2012-01-01

Full Text Available

ENGLISH ABSTRACT: This research presents a methodology for determining the optimal location of a new facility, having physical flow interaction of various degrees with other existing facilities in the presence of barriers impeding the shortest flow-path as well as the sub-optimal iso-cost positions. It also determines sub-optimal iso-cost positions with additional cost or penalty for not being able to site it at the computed optimal point. The proposed methodology considers all types of quadrilateral barrier or forbidden region configurations to generalize and by-pass such impenetrable obstacles, and adopts a scheme of searching through the vertices of the quadrilaterals to determine the alternative shortest flow-path. This procedure of obstacle avoidance is novel. Software has been developed to facilitate computations for the search algorithm to determine the optimal and iso-cost co-ordinates. The test results are presented.

AFRIKAANSE OPSOMMING: Die navorsing behandel ‘n procedure vir die bepaling van optimum stigtingsposisie vir ‘n onderneming met vloei vanaf ander bestaande fasiliteite in die teenwoordigheid van ‘n verskeidenheid van randvoorwaardes. Die prodedure lewer as resultaat suboptimale isokoste-stigtingsplekke met bekendmaking van die koste wat onstaan a.g.v. afwyking van die randvoorwaardlose optimum oplossingskoste, die prosedure maak gebruik van ‘n vindingryke soekmetode wat toegepas word op niersydige meerkundige voorstellings vir die bepaling van korste roetes wat versperring omseil. Die prosedure word onderskei deur programmatuur. Toetsresultate word voorgehou.

Postoperative evaluation of surgical procedures in congenital heart disease with MR imaging

International Nuclear Information System (INIS)

Seelos, K.C.; Kersting-Sommerhoff, B.; Higgins, C.B.

1989-01-01

This paper reports on a study in which electrocardiographically gated spin-echo MR imaging was used to evaluate 23 patients with congenital heart disease who had undergone Waterston (n = 3), Potts (n = 2), Senning (n = 3), Fontan (n = 3), Rastelli (n = 4), Damus (n = 1) and Jatene (n = 7) procedures. Surgical shunts, conduits, or baffles were identified correctly in all patients. Patency, atresia and hypoplasia of central pulmonary arteries (PAs) as well as postoperative complications (focal stenosis of PAs, thrombosed pseudoaneurysm, intramural abscess) were diagnosed. MR findings were corroborated with angiography, echocardiography, and surgery. Narrowing of the right ventricular outflow tract and focal compression of the proximal PAs were recognized as specific complications of the Jatene procedure. MR imaging appears to be effective for the postoperative evaluation of surgical procedures used for congenital heart disease

A procedure for multi-objective optimization of tire design parameters

OpenAIRE

Nikola Korunović; Miloš Madić; Miroslav Trajanović; Miroslav Radovanović

2015-01-01

The identification of optimal tire design parameters for satisfying different requirements, i.e. tire performance characteristics, plays an essential role in tire design. In order to improve tire performance characteristics, formulation and solving of multi-objective optimization problem must be performed. This paper presents a multi-objective optimization procedure for determination of optimal tire design parameters for simultaneous minimization of strain energy density at two distinctive zo...

Optimization of procedure for calibration with radiometer/photometer

International Nuclear Information System (INIS)

Detilly, Isabelle

2009-01-01

A test procedure for the radiometer/photometer calibrations mark International Light at the Laboratorio de Fotometria y Tecnologia Laser (LAFTA) de la Escuela de Ingenieria Electrica de la Universidad de Costa Rica is established. Two photometric banks are used as experimental set and two calibrations were performed of the International Light. A basic procedure established in the laboratory, is used for calibration from measurements of illuminance and luminous intensity. Some dependent variations of photometric banks used in the calibration process, the programming of the radiometer/photometer and the applied methodology showed the results. The procedure for calibration with radiometer/photometer can be improved by optimizing the programming process of the measurement instrument and possible errors can be minimized by using the recommended procedure. (author) [es

Comparison of echocardiographic and cardiac magnetic resonance imaging measurements of functional single ventricular volumes, mass, and ejection fraction (from the Pediatric Heart Network Fontan Cross-Sectional Study).

Science.gov (United States)

Margossian, Renee; Schwartz, Marcy L; Prakash, Ashwin; Wruck, Lisa; Colan, Steven D; Atz, Andrew M; Bradley, Timothy J; Fogel, Mark A; Hurwitz, Lynne M; Marcus, Edward; Powell, Andrew J; Printz, Beth F; Puchalski, Michael D; Rychik, Jack; Shirali, Girish; Williams, Richard; Yoo, Shi-Joon; Geva, Tal

2009-08-01

Assessment of the size and function of a functional single ventricle (FSV) is a key element in the management of patients after the Fontan procedure. Measurement variability of ventricular mass, volume, and ejection fraction (EF) among observers by echocardiography and cardiac magnetic resonance imaging (CMR) and their reproducibility among readers in these patients have not been described. From the 546 patients enrolled in the Pediatric Heart Network Fontan Cross-Sectional Study (mean age 11.9 +/- 3.4 years), 100 echocardiograms and 50 CMR studies were assessed for measurement reproducibility; 124 subjects with paired studies were selected for comparison between modalities. Interobserver agreement for qualitative grading of ventricular function by echocardiography was modest for left ventricular (LV) morphology (kappa = 0.42) and weak for right ventricular (RV) morphology (kappa = 0.12). For quantitative assessment, high intraclass correlation coefficients were found for echocardiographic interobserver agreement (LV 0.87 to 0.92, RV 0.82 to 0.85) of systolic and diastolic volumes, respectively. In contrast, intraclass correlation coefficients for LV and RV mass were moderate (LV 0.78, RV 0.72). The corresponding intraclass correlation coefficients by CMR were high (LV 0.96, RV 0.85). Volumes by echocardiography averaged 70% of CMR values. Interobserver reproducibility for the EF was similar for the 2 modalities. Although the absolute mean difference between modalities for the EF was small (<2%), 95% limits of agreement were wide. In conclusion, agreement between observers of qualitative FSV function by echocardiography is modest. Measurements of FSV volume by 2-dimensional echocardiography underestimate CMR measurements, but their reproducibility is high. Echocardiographic and CMR measurements of FSV EF demonstrate similar interobserver reproducibility, whereas measurements of FSV mass and LV diastolic volume are more reproducible by CMR.

Abdominoplasty for Ladd's procedure: optimizing access and esthetics

African Journals Online (AJOL)

Abdominoplasty for Ladd's procedure: optimizing access and esthetics. Rachel Aliotta, Neilendu Kundu, Anthony Stallion, Christi Cavaliere. Abstract. Rotational anomalies occur when there is an abnormal arrest of rotation in the embryonic gut during development. The characteristic population affected is considered to be ...

Measurement of pulmonary vascular resistance of Fontan candidates with pulmonary arterial distortion by means of pulmonary perfusion imaging

International Nuclear Information System (INIS)

Park, In-Sam; Mizukami, Ayumi; Tomimatsu, Hirofumi; Kondou, Chisato; Nakanishi, Toshio; Nakazawa, Makoto; Momma, Kazuo

1998-01-01

We measured the distribution of blood flow to the right (R) and left lung (L) by means of pulmonary perfusion imaging and calculated pulmonary vascular resistance (Rp) in 13 patients, whose right and left pulmonary artery pressures were different by 2 to 9 mmHg due to pulmonary arterial distortion (5 interruption, 8 stenosis). The right lung/left lung blood flow ratio was determined and from the ratio and the total pulmonary blood flow, which was determined using the Fick's principle, the absolute values of right and left pulmonary blood flow were calculated. Using the right and left pulmonary blood flow and the right and left pulmonary arterial pressures, right and left pulmonary vascular resistance were calculated, separately. Vascular resistance of the whole lung (Rp) was then calculated using the following equation. 1/(Rp of total lung)=1/(Rp of right lung)+1/(Rp of left lung). Rp calculated from this equation was 1.8+/-0.8 U·m 2 and all values were less than 3 U·m 2 (range 0.3-2.8). Rp estimated from the conventional method using the total pulmonary blood flow and pulmonary arterial pressures, without using the right/left blood flow ratio, ranging from 0.4 to 3.8 U·m 2 and 5 of 13 patients showed Rp>3 U·m 2 . All patients underwent Fontan operation successfully. These data indicated that this method is useful to estimate Rp and to determine the indication of Fontan operation in patients with pulmonary arterial distortions. (author)

Numerical Procedure for Optimizing Dye-Sensitized Solar Cells

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Mihai Razvan Mitroi

2014-01-01

Full Text Available We propose a numerical procedure consisting of a simplified physical model and a numerical method with the aim of optimizing the performance parameters of dye-sensitized solar cells (DSSCs. We calculate the real rate of absorbed photons (in the dye spectral range Grealx by introducing a factor β<1 in order to simplify the light absorption and reflection on TCO electrode. We consider the electrical transport to be purely diffusive and the recombination process only to occur between electrons from the TiO2 conduction band and anions from the electrolyte. The used numerical method permits solving the system of differential equations resulting from the physical model. We apply the proposed numerical procedure on a classical DSSC based on Ruthenium dye in order to validate it. For this, we simulate the J-V characteristics and calculate the main parameters: short-circuit current density Jsc, open circuit voltage Voc, fill factor FF, and power conversion efficiency η. We analyze the influence of the nature of semiconductor (TiO2 and dye and also the influence of different technological parameters on the performance parameters of DSSCs. The obtained results show that the proposed numerical procedure is suitable for developing a numerical simulation platform for improving the DSSCs performance by choosing the optimal parameters.

Right atrium and superior vena cava pressure measurements in a novel animal model to study one and a half ventricle repair as compared to Fontan type procedure

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Anil Bhattarai

2017-01-01

ventricle repair, as compared to Fontan type procedure.

Aerial photogrammetry procedure optimized for micro uav

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T. Anai

2014-06-01

Full Text Available This paper proposes the automatic aerial photogrammetry procedure optimized for Micro UAV that has ability of autonomous flight. The most important goal of our proposed method is the reducing the processing cost for fully automatic reconstruction of DSM from a large amount of image obtained from Micro UAV. For this goal, we have developed automatic corresponding point generation procedure using feature point tracking algorithm considering position and attitude information, which obtained from onboard GPS-IMU integrated on Micro UAV. In addition, we have developed the automatic exterior orientation and registration procedure from the automatic generated corresponding points on each image and position and attitude information from Micro UAV. Moreover, in order to reconstruct precise DSM, we have developed the area base matching process which considering edge information. In this paper, we describe processing flow of our automatic aerial photogrammetry. Moreover, the accuracy assessment is also described. Furthermore, some application of automatic reconstruction of DSM will be desired.

Time Optimal Synchronization Procedure and Associated Feedback Loops

CERN Document Server

Angoletta, Maria Elena; CERN. Geneva. ATS Department

2016-01-01

A procedure to increase the speed of currently used synchronization loops in a synchrotron by an order of magnitude is presented. Beams dynamics constraint imposes an upper limit on excursions in stable phase angle, and the procedure presented exploits this limit to arrive in the synchronized state from an arbitrary initial state in the fastest possible way. Detailed corrector design for beam phase loop, differential frequency loop and final synchronization loop is also presented. Finally, an overview of the synchronization methods currently deployed in some other CERN’s machines is provided, together with a brief comparison with the newly proposed time-optimal algorithm.

Procedural Optimization Models for Multiobjective Flexible JSSP

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Elena Simona NICOARA

2013-01-01

Full Text Available The most challenging issues related to manufacturing efficiency occur if the jobs to be sched-uled are structurally different, if these jobs allow flexible routings on the equipments and mul-tiple objectives are required. This framework, called Multi-objective Flexible Job Shop Scheduling Problems (MOFJSSP, applicable to many real processes, has been less reported in the literature than the JSSP framework, which has been extensively formalized, modeled and analyzed from many perspectives. The MOFJSSP lie, as many other NP-hard problems, in a tedious place where the vast optimization theory meets the real world context. The paper brings to discussion the most optimization models suited to MOFJSSP and analyzes in detail the genetic algorithms and agent-based models as the most appropriate procedural models.

Optimization by GRASP greedy randomized adaptive search procedures

CERN Document Server

Resende, Mauricio G C

2016-01-01

This is the first book to cover GRASP (Greedy Randomized Adaptive Search Procedures), a metaheuristic that has enjoyed wide success in practice with a broad range of applications to real-world combinatorial optimization problems. The state-of-the-art coverage and carefully crafted pedagogical style lends this book highly accessible as an introductory text not only to GRASP, but also to combinatorial optimization, greedy algorithms, local search, and path-relinking, as well as to heuristics and metaheuristics, in general. The focus is on algorithmic and computational aspects of applied optimization with GRASP with emphasis given to the end-user, providing sufficient information on the broad spectrum of advances in applied optimization with GRASP. For the more advanced reader, chapters on hybridization with path-relinking and parallel and continuous GRASP present these topics in a clear and concise fashion. Additionally, the book offers a very complete annotated bibliography of GRASP and combinatorial optimizat...

Recurrent protein-losing enteropathy and tricuspid valve insufficiency in a transplanted heart: a causal relationship?

Science.gov (United States)

Aggarwal, Sanjeev; Delius, Ralph E; Walters, Henry L; L'Ecuyer, Thomas J

2012-01-01

This case report describes a toddler who developed a protein-losing enteropathy (PLE) 4 years after orthotopic heart transplantation (OHT). He was born with a hypoplastic left heart syndrome for which he underwent a successful Norwood procedure, a Hemi-Fontan palliation, and a Fontan palliation at 18 months of age. Fifteen months following the Fontan operation, he developed a PLE and Fontan failure requiring OHT. Four years after OHT, he developed a severe tricuspid regurgitation and a PLE. His PLE improved after tricuspid valve replacement. It is now 2 years since his tricuspid valve replacement and he remains clinically free of ascites and peripheral edema with a normal serum albumin level. His prosthetic tricuspid valve is functioning normally. © 2011 Wiley Periodicals, Inc.

Beyond the drugs : non-pharmacological strategies to optimize procedural care in children

NARCIS (Netherlands)

Leroy, Piet L.; Costa, Luciane R.; Emmanouil, Dimitris; van Beukering, Alice; Franck, Linda S.

2016-01-01

Purpose of review Painful and/or stressful medical procedures mean a substantial burden for sick children. There is good evidence that procedural comfort can be optimized by a comprehensive comfort-directed policy containing the triad of non-pharmacological strategies (NPS) in all cases, timely or

A new approach of optimization procedure for superconducting integrated circuits

International Nuclear Information System (INIS)

Saitoh, K.; Soutome, Y.; Tarutani, Y.; Takagi, K.

1999-01-01

We have developed and tested a new circuit simulation procedure for superconducting integrated circuits which can be used to optimize circuit parameters. This method reveals a stable operation region in the circuit parameter space in connection with the global bias margin by means of a contour plot of the global bias margin versus the circuit parameters. An optimal set of parameters with margins larger than these of the initial values has been found in the stable region. (author)

A practical optimization procedure for radial BWR fuel lattice design using tabu search with a multiobjective function

International Nuclear Information System (INIS)

Francois, J.L.; Martin-del-Campo, C.; Francois, R.; Morales, L.B.

2003-01-01

An optimization procedure based on the tabu search (TS) method was developed for the design of radial enrichment and gadolinia distributions for boiling water reactor (BWR) fuel lattices. The procedure was coded in a computing system in which the optimization code uses the tabu search method to select potential solutions and the HELIOS code to evaluate them. The goal of the procedure is to search for an optimal fuel utilization, looking for a lattice with minimum average enrichment, with minimum deviation of reactivity targets and with a local power peaking factor (PPF) lower than a limit value. Time-dependent-depletion (TDD) effects were considered in the optimization process. The additive utility function method was used to convert the multiobjective optimization problem into a single objective problem. A strategy to reduce the computing time employed by the optimization was developed and is explained in this paper. An example is presented for a 10x10 fuel lattice with 10 different fuel compositions. The main contribution of this study is the development of a practical TDD optimization procedure for BWR fuel lattice design, using TS with a multiobjective function, and a strategy to economize computing time

Development of multidisciplinary design optimization procedures for smart composite wings and turbomachinery blades

Science.gov (United States)

Jha, Ratneshwar

Multidisciplinary design optimization (MDO) procedures have been developed for smart composite wings and turbomachinery blades. The analysis and optimization methods used are computationally efficient and sufficiently rigorous. Therefore, the developed MDO procedures are well suited for actual design applications. The optimization procedure for the conceptual design of composite aircraft wings with surface bonded piezoelectric actuators involves the coupling of structural mechanics, aeroelasticity, aerodynamics and controls. The load carrying member of the wing is represented as a single-celled composite box beam. Each wall of the box beam is analyzed as a composite laminate using a refined higher-order displacement field to account for the variations in transverse shear stresses through the thickness. Therefore, the model is applicable for the analysis of composite wings of arbitrary thickness. Detailed structural modeling issues associated with piezoelectric actuation of composite structures are considered. The governing equations of motion are solved using the finite element method to analyze practical wing geometries. Three-dimensional aerodynamic computations are performed using a panel code based on the constant-pressure lifting surface method to obtain steady and unsteady forces. The Laplace domain method of aeroelastic analysis produces root-loci of the system which gives an insight into the physical phenomena leading to flutter/divergence and can be efficiently integrated within an optimization procedure. The significance of the refined higher-order displacement field on the aeroelastic stability of composite wings has been established. The effect of composite ply orientations on flutter and divergence speeds has been studied. The Kreisselmeier-Steinhauser (K-S) function approach is used to efficiently integrate the objective functions and constraints into a single envelope function. The resulting unconstrained optimization problem is solved using the

Design Procedure for High-Speed PM Motors Aided by Optimization Algorithms

Directory of Open Access Journals (Sweden)

Francesco Cupertino

2018-02-01

Full Text Available This paper considers the electromagnetic and structural co-design of superficial permanent magnet synchronous machines for high-speed applications, with the aid of a Pareto optimization procedure. The aim of this work is to present a design procedure for the afore-mentioned machines that relies on the combined used of optimization algorithms and finite element analysis. The proposed approach allows easy analysis of the results and a lowering of the computational burden. The proposed design method is presented through a practical example starting from the specifications of an aeronautical actuator. The design procedure is based on static finite element simulations for electromagnetic analysis and on analytical formulas for structural design. The final results are validated through detailed transient finite element analysis to verify both electromagnetic and structural performance. The step-by-step presentation of the proposed design methodology allows the reader to easily adapt it to different specifications. Finally, a comparison between a distributed-winding (24 slots and a concentrated-winding (6 slots machine is presented demonstrating the advantages of the former winding arrangement for high-speed applications.

Optimized procedure for calibration and verification multileaf collimator from Elekta Synergy accelerator

International Nuclear Information System (INIS)

Castel Millan, A.; Perellezo Mazon, A.; Fernandez Ibiza, J.; Arnalte Olloquequi, M.; Armengol Martinez, S.; Rodriguez Rey, A.; Guedea Edo, F.

2011-01-01

The objective of this work is to design an optimized procedure for calibration and verification of a multileaf collimator used so as to allow the EPID and the image plate in a complementary way, using different processing systems. With this procedure we have two equivalent alternative as the same parameters obtained for the calibration of multileaf Elekta Synergy accelerator.

Pregnancy in complex CHD: focus on patients with Fontan circulation and patients with a systemic right ventricle.

Science.gov (United States)

Khan, Abigail; Kim, Yuli Y

2015-12-01

The majority of children with congenital heart disease (CHD) now survive into adulthood, and many women with CHD want to pursue pregnancy. Pregnancy represents a complex issue for the CHD care provider. It requires balancing the interests of the woman against the risk to her health during pregnancy, while also factoring in the long-term risks to her health and the risk to her fetus. Our knowledge about this subject has been historically limited by lack of data regarding the outcome of pregnancy in CHD; however, in recent years, more data have begun to emerge. In this review, we will summarise what is known about risk assessment in pregnant CHD patients. We provide a framework for healthcare providers managing pregnancy in this population, with focus on the systemic right ventricle and the Fontan operation.

Successful diuretics treatment of protein-losing enteropathy in Noonan syndrome.

Science.gov (United States)

Mizuochi, Tatsuki; Suda, Kenji; Seki, Yoshitaka; Yanagi, Tadahiro; Yoshimoto, Hironaga; Kudo, Yoshiyuki; Iemura, Motofumi; Tanikawa, Ken; Matsuishi, Toyojiro

2015-04-01

There are few reports on successful high-dose spironolactone treatment of refractory protein-losing enteropathy (PLE) caused by Fontan procedure. We report successful diuretics treatment with spironolactone and furosemide at standard dose, of refractory PLE in a patient with Noonan syndrome and repaired congenital heart disease. This is the first successful application of diuretics treatment in a patient with refractory PLE without Fontan procedure. This case illustrates that diuretics treatment can be the first-line treatment of PLE regardless of the causative physiology, and can be effective in refractory PLE with Noonan syndrome. © 2015 Japan Pediatric Society.

Optimization of wet digestion procedure of blood and tissue for selenium determination by means of 75Se tracer

International Nuclear Information System (INIS)

Holynska, B.; Lipinska, K.

1977-01-01

Selenium-75 tracer has been used for optimization of analytical procedure of selenium determination in blood and tissue. Wet digestion procedure and reduction of selenium to its elemental form with tellurium as coprecipitant have been tested. Recovery of selenium obtained with the use of optimized analytical procedure amounts up 95% and precision is equal to 4.2%. (author)

Cardiopulmonary Exercise Testing in Fontan Patients With and Without Isomerism (Heterotaxy) as Compared to Patients With Primary Ciliary Dyskinesia and Subjects With Structurally Normal Hearts

DEFF Research Database (Denmark)

Loomba, Rohit S; Danduran, Michael; Nielsen, Kim G

2017-01-01

with and without isomerism. We have now compared these finding with those from patients with primary ciliary dyskinesia, as many patients with isomerism have ciliary dyskinesia. We identified patients having the Fontan circulation with and without isomerism who had undergone cardiopulmonary exercise testing......, comparing the findings from healthy individuals undergoing exercise, and a comparable number of individuals with primary ciliary dyskinesia but no congenital heart disease. We were able to include a total of 68 patients in our study, with 17 in each of the four groups. Cardiopulmonary exercise testing...

The human error rate assessment and optimizing system HEROS - a new procedure for evaluating and optimizing the man-machine interface in PSA

International Nuclear Information System (INIS)

Richei, A.; Hauptmanns, U.; Unger, H.

2001-01-01

A new procedure allowing the probabilistic evaluation and optimization of the man-machine system is presented. This procedure and the resulting expert system HEROS, which is an acronym for Human Error Rate Assessment and Optimizing System, is based on the fuzzy set theory. Most of the well-known procedures employed for the probabilistic evaluation of human factors involve the use of vague linguistic statements on performance shaping factors to select and to modify basic human error probabilities from the associated databases. This implies a large portion of subjectivity. Vague statements are expressed here in terms of fuzzy numbers or intervals which allow mathematical operations to be performed on them. A model of the man-machine system is the basis of the procedure. A fuzzy rule-based expert system was derived from ergonomic and psychological studies. Hence, it does not rely on a database, whose transferability to situations different from its origin is questionable. In this way, subjective elements are eliminated to a large extent. HEROS facilitates the importance analysis for the evaluation of human factors, which is necessary for optimizing the man-machine system. HEROS is applied to the analysis of a simple diagnosis of task of the operating personnel in a nuclear power plant

Optimization of exposure procedures for sub-quarter-micron CMOS applications

Science.gov (United States)

Hotta, Shoji; Onozuka, Toshihiko; Fukumoto, Keiko; Shirai, Seiichiro; Okazaki, Shinji

1998-06-01

We investigated various exposure procedures to minimize the Critical Dimension (CD) variation for the patterning of sub- quarter micron gates. To examine dependence of the CD variation on the pattern pitch and defocus conditions, the light intensity profiles of four different mask structures: (1) a binary mask with clear field, (2) a binary mask with dark field, (3) a phase-edge type phase-shifting mask (a phase-edge PSM) with clear field, and (4) a halftone phase- shifting mask (a halftone PSM) were compared, where exposure wavelength was 248 nm and numerical aperture (NA) of KrF stepper was 0.55. For 200-nm gate patterns, dependence of the CD variation on the pattern pitch and defocus conditions was minimized by a phase-edge PSM with clear field. By optimizing the illumination condition for a phase-edge PSM exposure, we obtained the CD variation of 10 nm at the minimum gate pitch of 0.8 micrometer and the defocus condition of plus or minus 0.4 micrometer. Applying the optimized exposure procedure to the device fabrication process, we obtained the total CD variation of plus or minus 27 nm.

Procedures for finding optimal layouts of vehicle components with respect to durability

Energy Technology Data Exchange (ETDEWEB)

Eschenauer, H.A.; Idelberger, H. [Univ. of Siegen (Germany); Bieker, G.; Rottler, A. [Bombardier, Siegen-Netphen (Germany); Weinert, M. [Ford Motor Comp., Cologne (Germany)

2007-07-01

When designing complete systems or system components, it is of vital importance for the manufacturers to optimally fulfill the continuously increasing demands pertaining to safety, durability, reduction of energy consumption, noise reduction, improvement of comfort, accuracy, etc. This applies to all types of traffic and transportation systems like rail vehicles, automobiles, airplanes and ships. By combining structural analysis and simulation methods with optimization algorithms, required specifications can be met faster and more reliably, and hence the production development cycles can be substantially reduced. This paper shall give an overview on results of a method with the features of a damage approximation as precisely as possible on the one hand and, on the other hand, a load-time history with few different load cycles so that a nonlinear calculation can be performed in the shortest possible time. Simulations with rigidly and elastically modeled components like bogie frames or carbodies show that depending on the type of modeling substantial differences may occur with respect to dynamic behavior and the interaction quantity between the bodies. This aspect has to be taken into consideration for quantitatively sufficient fatigue strength and durability calculation. Mathematical optimization procedures are in general an efficient tool to guarantee the optimal fulfillment of all required design objectives and constraints in all stages of the design process. Some of the procedures are illustrated at two examples (bogie frame, carbody). (orig.)

Radiological protection in coronary procedures. Is it sufficient with the practices optimizations?

International Nuclear Information System (INIS)

Cotelo, Elena D.

2001-01-01

The number of percutaneous transluminal coronary procedures (PTCA) per million inhabitants in Uruguay is similar to the one obtained in developed countries. Between 1995 and 1999, PTCA procedures increased by 86 %. Despite the 'Fondo Nacional de Recursos' finances the Interventional Cardiology (IC) procedures of 90 % inhabitants, the number of IC procedures on people of public hospital is lower than that on people from private hospitals. All the 6 IC facilities are in the capital of the country. The number of IC procedures increases while decrease s the distance between the hospital and the capital. This study also shows that no one facility performs quality control tests, the 50% of the X-ray equipment is more than 10 years and, the IC staff does not have Radiation Protection education. We conclude that it is necessary to establishing as soon as possible, Quality Assurance Programmes. Despite the objective of this work was to obtain information to optimize the IC procedures, results shows that it is necessary to include the Principle of Justification of the procedures in Radiation Protection education for the IC staff. (author)

Optimal decision procedures for satisfiability in fragments of alternating-time temporal logics

DEFF Research Database (Denmark)

Goranko, Valentin; Vester, Steen

2014-01-01

We consider several natural fragments of the alternating-time temporal logics ATL*and ATL with restrictions on the nesting between temporal operators and strate-gicquantifiers. We develop optimal decision procedures for satisfiability in these fragments, showing that they have much lower complexi...

Evaluation and optimization of the man-machine interface in nuclear power plants using the HEROS procedure in PSA

International Nuclear Information System (INIS)

Richei, A.; Koch, M.K.; Unger, H.; Hauptmanns, U.

1998-01-01

For the probabilistic evaluation and optimization of the man-machine-system a new procedure is developed. This and the resulting expert system, which is based on the fuzzy set theory, is called HEROS, an acronym for Human Error Rate Assessment and Optimizing System. There are several existing procedures for the probabilistic evaluation of human errors, which have several disadvantages. However, in all of these procedures fuzzy verbal expressions are often used for the evaluation of human factors, also in the best known procedures. This use of verbal expressions for describing performance-shaping factors, enabling the evaluation of human factors is the basic approach for HEROS. A model of a modem man-machine-system is the basis of the procedure. Results from ergonomic studies are used to establish a rule-based expert system. HEROS simplifies the importance analysis for the evaluation of human factors, which is necessary for the optimization of the man-machine-system. It can be used in all areas of probabilistic safety assessment. The application of HEROS in the scope of accident management procedures and the comparison with the results of other procedures as an example for the usefulness and substantially more extensive applicability of this new procedure will be shown. (author)

Subgrid-scale scalar flux modelling based on optimal estimation theory and machine-learning procedures

Science.gov (United States)

Vollant, A.; Balarac, G.; Corre, C.

2017-09-01

New procedures are explored for the development of models in the context of large eddy simulation (LES) of a passive scalar. They rely on the combination of the optimal estimator theory with machine-learning algorithms. The concept of optimal estimator allows to identify the most accurate set of parameters to be used when deriving a model. The model itself can then be defined by training an artificial neural network (ANN) on a database derived from the filtering of direct numerical simulation (DNS) results. This procedure leads to a subgrid scale model displaying good structural performance, which allows to perform LESs very close to the filtered DNS results. However, this first procedure does not control the functional performance so that the model can fail when the flow configuration differs from the training database. Another procedure is then proposed, where the model functional form is imposed and the ANN used only to define the model coefficients. The training step is a bi-objective optimisation in order to control both structural and functional performances. The model derived from this second procedure proves to be more robust. It also provides stable LESs for a turbulent plane jet flow configuration very far from the training database but over-estimates the mixing process in that case.

An automatic procedure for optimizing fuel loading in consideration of the effect of burnup nonuniformity in assembly

International Nuclear Information System (INIS)

Wang Guoli.

1988-01-01

The effect of burnup nonuniformity across the assembly on optimizing fuel loading in core is investigated. Some new rules which can be used for optimizing fuel loading in the core are proposed. New automatic procedure for optimizing fuel loading in the core is described

Core design optimization by integration of a fast 3-D nodal code in a heuristic search procedure

Energy Technology Data Exchange (ETDEWEB)

Geemert, R. van; Leege, P.F.A. de; Hoogenboom, J.E.; Quist, A.J. [Delft University of Technology, NL-2629 JB Delft (Netherlands)

1998-07-01

An automated design tool is being developed for the Hoger Onderwijs Reactor (HOR) in Delft, the Netherlands, which is a 2 MWth swimming-pool type research reactor. As a black box evaluator, the 3-D nodal code SILWER, which up to now has been used only for evaluation of predetermined core designs, is integrated in the core optimization procedure. SILWER is a part of PSl's ELCOS package and features optional additional thermal-hydraulic, control rods and xenon poisoning calculations. This allows for fast and accurate evaluation of different core designs during the optimization search. Special attention is paid to handling the in- and output files for SILWER such that no adjustment of the code itself is required for its integration in the optimization programme. The optimization objective, the safety and operation constraints, as well as the optimization procedure, are discussed. (author)

Core design optimization by integration of a fast 3-D nodal code in a heuristic search procedure

International Nuclear Information System (INIS)

Geemert, R. van; Leege, P.F.A. de; Hoogenboom, J.E.; Quist, A.J.

1998-01-01

An automated design tool is being developed for the Hoger Onderwijs Reactor (HOR) in Delft, the Netherlands, which is a 2 MWth swimming-pool type research reactor. As a black box evaluator, the 3-D nodal code SILWER, which up to now has been used only for evaluation of predetermined core designs, is integrated in the core optimization procedure. SILWER is a part of PSl's ELCOS package and features optional additional thermal-hydraulic, control rods and xenon poisoning calculations. This allows for fast and accurate evaluation of different core designs during the optimization search. Special attention is paid to handling the in- and output files for SILWER such that no adjustment of the code itself is required for its integration in the optimization programme. The optimization objective, the safety and operation constraints, as well as the optimization procedure, are discussed. (author)

Development of an optimized procedure bridging design and structural analysis codes for the automatized design of the SMART

International Nuclear Information System (INIS)

Kim, Tae Wan; Park, Keun Bae; Choi, Suhn; Kim, Kang Soo; Jeong, Kyeong Hoon; Lee, Gyu Mahn

1998-09-01

In this report, an optimized design and analysis procedure is established to apply to the SMART (System-integrated Modular Advanced ReacTor) development. The development of an optimized procedure is to minimize the time consumption and engineering effort by squeezing the design and feedback interactions. To achieve this goal, the data and information generated through the design development should be directly transferred to the analysis program with minimum operation. The verification of the design concept requires considerable effort since the communication between the design and analysis involves time consuming stage for the conversion of input information. In this report, an optimized procedure is established bridging the design and analysis stage utilizing the IDEAS, ABAQUS and ANSYS. (author). 3 refs., 2 tabs., 5 figs

Optimal Procedure for siting of Nuclear Power Plant

International Nuclear Information System (INIS)

Aziuddin, Khairiah Binti; Park, Seo Yeon; Roh, Myung Sub

2013-01-01

This study discusses on a simulation approach for sensitivity analysis of the weights of multi-criteria decision models. The simulation procedures can also be used to aid the actual decision process, particularly when the task is to select a subset of superior alternatives. This study is to identify the criteria or parameters which are sensitive to the weighting factor that can affect the results in the decision making process to determine the optimal site for nuclear power plant (NPP) site. To perform this study, we adhere to IAEA NS-R-3 and DS 433. The siting process for nuclear installation consists of site survey and site selection stages. The siting process generally consists of an investigation of a large region to select one or more candidate sites by surveying the sites. After comparing the ROI, two candidate sites are compared for final determination, which are Wolsong and Kori site. Some assumptions are taken into consideration due to limitations and constraints throughout performing this study. Sensitivity analysis of multi criteria decision models is performed in this study to determine the optimal site in the site selection stage. Logical Decisions software will be employed as a tool to perform this analysis. Logical Decisions software helps to formulate the preferences and then rank the alternatives. It provides clarification of the rankings and hence aids the decision makers on evaluating the alternatives, and finally draw a conclusion on the selection of the optimal site

Optimal Procedure for siting of Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Aziuddin, Khairiah Binti; Park, Seo Yeon; Roh, Myung Sub [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

2013-10-15

This study discusses on a simulation approach for sensitivity analysis of the weights of multi-criteria decision models. The simulation procedures can also be used to aid the actual decision process, particularly when the task is to select a subset of superior alternatives. This study is to identify the criteria or parameters which are sensitive to the weighting factor that can affect the results in the decision making process to determine the optimal site for nuclear power plant (NPP) site. To perform this study, we adhere to IAEA NS-R-3 and DS 433. The siting process for nuclear installation consists of site survey and site selection stages. The siting process generally consists of an investigation of a large region to select one or more candidate sites by surveying the sites. After comparing the ROI, two candidate sites are compared for final determination, which are Wolsong and Kori site. Some assumptions are taken into consideration due to limitations and constraints throughout performing this study. Sensitivity analysis of multi criteria decision models is performed in this study to determine the optimal site in the site selection stage. Logical Decisions software will be employed as a tool to perform this analysis. Logical Decisions software helps to formulate the preferences and then rank the alternatives. It provides clarification of the rankings and hence aids the decision makers on evaluating the alternatives, and finally draw a conclusion on the selection of the optimal site.

Structural analysis and optimization procedure of the TFTR device substructure

International Nuclear Information System (INIS)

Driesen, G.

1975-10-01

A structural evaluation of the TFTR device substructure is performed in order to verify the feasibility of the proposed design concept as well as to establish a design optimization procedure for minimizing the material and fabrication cost of the substructure members. A preliminary evaluation of the seismic capability is also presented. The design concept on which the analysis is based is consistent with that described in the Conceptual Design Status Briefing report dated June 18, 1975

Estimating cellular parameters through optimization procedures: elementary principles and applications

Directory of Open Access Journals (Sweden)

Akatsuki eKimura

2015-03-01

Full Text Available Construction of quantitative models is a primary goal of quantitative biology, which aims to understand cellular and organismal phenomena in a quantitative manner. In this article, we introduce optimization procedures to search for parameters in a quantitative model that can reproduce experimental data. The aim of optimization is to minimize the sum of squared errors (SSE in a prediction or to maximize likelihood. A (local maximum of likelihood or (local minimum of the SSE can efficiently be identified using gradient approaches. Addition of a stochastic process enables us to identify the global maximum/minimum without becoming trapped in local maxima/minima. Sampling approaches take advantage of increasing computational power to test numerous sets of parameters in order to determine the optimum set. By combining Bayesian inference with gradient or sampling approaches, we can estimate both the optimum parameters and the form of the likelihood function related to the parameters. Finally, we introduce four examples of research that utilize parameter optimization to obtain biological insights from quantified data: transcriptional regulation, bacterial chemotaxis, morphogenesis, and cell cycle regulation. With practical knowledge of parameter optimization, cell and developmental biologists can develop realistic models that reproduce their observations and thus, obtain mechanistic insights into phenomena of interest.

Optimized in vitro procedure for assessing the cytocompatibility of magnesium-based biomaterials.

Science.gov (United States)

Jung, Ole; Smeets, Ralf; Porchetta, Dario; Kopp, Alexander; Ptock, Christoph; Müller, Ute; Heiland, Max; Schwade, Max; Behr, Björn; Kröger, Nadja; Kluwe, Lan; Hanken, Henning; Hartjen, Philip

2015-09-01

Magnesium (Mg) is a promising biomaterial for degradable implant applications that has been extensively studied in vitro and in vivo in recent years. In this study, we developed a procedure that allows an optimized and uniform in vitro assessment of the cytocompatibility of Mg-based materials while respecting the standard protocol DIN EN ISO 10993-5:2009. The mouse fibroblast line L-929 was chosen as the preferred assay cell line and MEM supplemented with 10% FCS, penicillin/streptomycin and 4mM l-glutamine as the favored assay medium. The procedure consists of (1) an indirect assessment of effects of soluble Mg corrosion products in material extracts and (2) a direct assessment of the surface compatibility in terms of cell attachment and cytotoxicity originating from active corrosion processes. The indirect assessment allows the quantification of cell-proliferation (BrdU-assay), viability (XTT-assay) as well as cytotoxicity (LDH-assay) of the mouse fibroblasts incubated with material extracts. Direct assessment visualizes cells attached to the test materials by means of live-dead staining. The colorimetric assays and the visual evaluation complement each other and the combination of both provides an optimized and simple procedure for assessing the cytocompatibility of Mg-based biomaterials in vitro. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Optimization of wet digestion procedure of blood and tissue for selenium determination by means of 75Se tracer

International Nuclear Information System (INIS)

Holynska, B.; Lipinska-Kalita, K.

1977-01-01

Selenium-75 tracer has been used for optimization of analytical procedure of selenium determination in blood and tissue. Wet digestion procedure and reduction of selenium to its elemental form with tellurium as coprecipitant have been tested. It is seen that the use of a mixture of perchloric and sulphuric acid with sodium molybdenate for the wet digestion of organic matter followed by the reduction of selenium to its elementary form by a mixture of stannous chloride and hydroxylamine hydrochloride results in very good recovery of selenium. Recovery of selenium obtained with the use of optimized analytical procedure amounts to 95% and precision is equal to 4.2%. (T.I.)

Optimization of the semiautomated Macdonald and Savage procedure

International Nuclear Information System (INIS)

Kuvik, V.; Vrbova, L.

1990-06-01

Several topics concerning the Macdonald and Savage (MD/S) procedure used for the potentiometric determination of plutonium were included in the programme of Analytical Services requested form CCL Rez. One part of the work was focussed on eliminating the variations of the Pu results and titems. The sulfuric reagent should be aged at least for one week. The optimal composition of the sulfuric reagent is 2M sulfuric acid + 0.2M sulfuric acid + 0.25 cerous nitrate. The excess of 0.002 N permanganate may vary between 0.016 and 0.1 ml. A variation of 0.02M oxalic acid between 0.08 and 0.14 ml is acceptable. The presence of Ga results in a slight positive bias of the Pu determination at ratio. Ga/Pu = 0.25. 3 refs, 18 tabs

Systematic and efficient side chain optimization for molecular docking using a cheapest-path procedure.

Science.gov (United States)

Schumann, Marcel; Armen, Roger S

2013-05-30

Molecular docking of small-molecules is an important procedure for computer-aided drug design. Modeling receptor side chain flexibility is often important or even crucial, as it allows the receptor to adopt new conformations as induced by ligand binding. However, the accurate and efficient incorporation of receptor side chain flexibility has proven to be a challenge due to the huge computational complexity required to adequately address this problem. Here we describe a new docking approach with a very fast, graph-based optimization algorithm for assignment of the near-optimal set of residue rotamers. We extensively validate our approach using the 40 DUD target benchmarks commonly used to assess virtual screening performance and demonstrate a large improvement using the developed side chain optimization over rigid receptor docking (average ROC AUC of 0.693 vs. 0.623). Compared to numerous benchmarks, the overall performance is better than nearly all other commonly used procedures. Furthermore, we provide a detailed analysis of the level of receptor flexibility observed in docking results for different classes of residues and elucidate potential avenues for further improvement. Copyright © 2013 Wiley Periodicals, Inc.

Use of Ventricular Assist Device in Univentricular Physiology: The Role of Lumped Parameter Models.

Science.gov (United States)

Di Molfetta, Arianna; Ferrari, Gianfranco; Filippelli, Sergio; Fresiello, Libera; Iacobelli, Roberta; Gagliardi, Maria G; Amodeo, Antonio

2016-05-01

Failing single-ventricle (SV) patients might benefit from ventricular assist devices (VADs) as a bridge to heart transplantation. Considering the complex physiopathology of SV patients and the lack of established experience, the aim of this work was to realize and test a lumped parameter model of the cardiovascular system, able to simulate SV hemodynamics and VAD implantation effects. Data of 30 SV patients (10 Norwood, 10 Glenn, and 10 Fontan) were retrospectively collected and used to simulate patients' baseline. Then, the effects of VAD implantation were simulated. Additionally, both the effects of ventricular assistance and cavopulmonary assistance were simulated in different pathologic conditions on Fontan patients, including systolic dysfunction, diastolic dysfunction, and pulmonary vascular resistance increment. The model can reproduce patients' baseline well. Simulation results suggest that the implantation of VAD: (i) increases the cardiac output (CO) in all the three palliation conditions (Norwood 77.2%, Glenn 38.6%, and Fontan 17.2%); (ii) decreases the SV external work (SVEW) (Norwood 55%, Glenn 35.6%, and Fontan 41%); (iii) increases the mean pulmonary arterial pressure (Pap) (Norwood 39.7%, Glenn 12.1%, and Fontan 3%). In Fontan circulation, with systolic dysfunction, the left VAD (LVAD) increases CO (35%), while the right VAD (RVAD) determines a decrement of inferior vena cava pressure (Pvci) (39%) with 34% increment of CO. With diastolic dysfunction, the LVAD increases CO (42%) and the RVAD decreases the Pvci. With pulmonary vascular resistance increment, the RVAD allows the highest CO (50%) increment with the highest decrement of Pvci (53%). The single ventricular external work (SVEW) increases (decreases) increasing the VAD speed in cavopulmonary (ventricular) assistance. Numeric models could be helpful in this challenging and innovative field to support patients and VAD selection to optimize the clinical outcome and personalize the therapy

Multi-objective Optimization of Departure Procedures at Gimpo International Airport

Science.gov (United States)

Kim, Junghyun; Lim, Dongwook; Monteiro, Dylan Jonathan; Kirby, Michelle; Mavris, Dimitri

2018-04-01

Most aviation communities have increasing concerns about the environmental impacts, which are directly linked to health issues for local residents near the airport. In this study, the environmental impact of different departure procedures using the Aviation Environmental Design Tool (AEDT) was analyzed. First, actual operational data were compiled at Gimpo International Airport (March 20, 2017) from an open source. Two modifications were made in the AEDT to model the operational circumstances better and the preliminary AEDT simulations were performed according to the acquired operational procedures. Simulated noise results showed good agreements with noise measurement data at specific locations. Second, a multi-objective optimization of departure procedures was performed for the Boeing 737-800. Four design variables were selected and AEDT was linked to a variety of advanced design methods. The results showed that takeoff thrust had the greatest influence and it was found that fuel burn and noise had an inverse relationship. Two points representing each fuel burn and noise optimum on the Pareto front were parsed and run in AEDT to compare with the baseline. The results showed that the noise optimum case reduced Sound Exposure Level 80-dB noise exposure area by approximately 5% while the fuel burn optimum case reduced total fuel burn by 1% relative to the baseline for aircraft-level analysis.

Optimization of digitization procedures in cultural heritage preservation

Science.gov (United States)

Martínez, Bea; Mitjà, Carles; Escofet, Jaume

2013-11-01

The digitization of both volumetric and flat objects is the nowadays-preferred method in order to preserve cultural heritage items. High quality digital files obtained from photographic plates, films and prints, paintings, drawings, gravures, fabrics and sculptures, allows not only for a wider diffusion and on line transmission, but also for the preservation of the original items from future handling. Early digitization procedures used scanners for flat opaque or translucent objects and camera only for volumetric or flat highly texturized materials. The technical obsolescence of the high-end scanners and the improvement achieved by professional cameras has result in a wide use of cameras with digital back to digitize any kind of cultural heritage item. Since the lens, the digital back, the software controlling the camera and the digital image processing provide a wide range of possibilities, there is necessary to standardize the methods used in the reproduction work leading to preserve as high as possible the original item properties. This work presents an overview about methods used for camera system characterization, as well as the best procedures in order to identify and counteract the effect of the lens residual aberrations, sensor aliasing, image illumination, color management and image optimization by means of parametric image processing. As a corollary, the work shows some examples of reproduction workflow applied to the digitization of valuable art pieces and glass plate photographic black and white negatives.

Optimization of procedures for mercury-203 instrumental neutron activation analysis in human urine

Energy Technology Data Exchange (ETDEWEB)

Blotcky, A J; Claassen, J P [Nebraska Univ., Omaha, NE (United States). Medical Center; Fung, Y K [Nebraska Univ., Lincoln, NE (United States). Dept. of Chemistry; Meade, A G; Rack, E P [Nebraska Univ., Lincoln, NE (United States)

1995-08-01

Mercury, a known neurotoxin, has been implicated in etiology and pathogenesis of such disease states as Alzheimer`s and Parkinson`s diseases. There is concern that the exposure to mercury vapor released from dental amalgam restorations is a potential health hazard. Measurement of mercury concentrations in blood or urine may be useful in diagnosis of mercury poisoning and in assessing the extent exposure. This study describes the optimization of pre-neutron activation analysis procedures such as sampling, selection of irradiation and counting vials and acid digestion in order to minimize mercury loss via volatilization and/or permeation through containers. Therefore, the determination of mercury can be complicated by these potential losses. In the optimized procedure 20mL of urine was spiked with three different concentrations of mercury, digested with concentrated nitric acid, and placed in polypropylene vials for irradiation and counting. Analysis was performed by subtracting the Se-75 photopeak contribution to the 279 keV Hg-203 photopeak and applying the method of standard additions. Urinary mercury concentrations in normal human subjects were determined to be of the order of 10ng/mL. (author). 22 refs., 1 fig., 5 tabs.

Optimization of procedures for mercury-203 instrumental neutron activation analysis in human urine

International Nuclear Information System (INIS)

Blotcky, A.J.; Claassen, J.P.

1995-01-01

Mercury, a known neurotoxin, has been implicated in etiology and pathogenesis of such disease states as Alzheimer's and Parkinson's diseases. There is concern that the exposure to mercury vapor released from dental amalgam restorations is a potential health hazard. Measurement of mercury concentrations in blood or urine may be useful in diagnosis of mercury poisoning and in assessing the extent exposure. This study describes the optimization of pre-neutron activation analysis procedures such as sampling, selection of irradiation and counting vials and acid digestion in order to minimize mercury loss via volatilization and/or permeation through containers. Therefore, the determination of mercury can be complicated by these potential losses. In the optimized procedure 20mL of urine was spiked with three different concentrations of mercury, digested with concentrated nitric acid, and placed in polypropylene vials for irradiation and counting. Analysis was performed by subtracting the Se-75 photopeak contribution to the 279 keV Hg-203 photopeak and applying the method of standard additions. Urinary mercury concentrations in normal human subjects were determined to be of the order of 10ng/mL. (author). 22 refs., 1 fig., 5 tabs

Challenges of univentricular physiology in heterotaxy.

Science.gov (United States)

Jacobs, Marshall L; Mavroudis, Constantine

2011-04-01

Patients with heterotaxy syndrome exhibit an extensive constellation of congenital cardiac malformations, making these patients a challenging group to manage surgically. Many of these patients' hearts do not lend themselves to separation of the pulmonary and systemic circulations except by some modification of the Fontan procedure. Palliative procedures early in life are directed at creating a satisfactory balance of pulmonary and systemic blood flow and at the same time ensuring unobstructed pulmonary venous return. Early conversion from parallel pulmonary and systemic circulations to superior cavopulmonary connections is important, to reduce volume work of the systemic ventricle. Heterotaxy patients are generally considered a high-risk population with respect to eventual Fontan procedure. It is important to appreciate the unique and variable anatomy of the sinus node and conduction system and the potential for occult pulmonary venous obstruction, atrioventricular valve regurgitation, and recurrent cyanosis, which may be related to the development of pulmonary arteriovenous malformations.

Optimization procedures in mammography: First results

International Nuclear Information System (INIS)

Espana Lopez, M. L.; Marcos de Paz, L.; Martin Rincon, C.; Jerez Sainz, I.; Lopez Franco, M. P.

2001-01-01

Optimization procedures in mammography using equipment with a unique target/filter combination can be carried out through such diverse factors as target optical density, technique factors for exposure, screen film combination or processing cycle, in order to obtain an image adequate for the diagnosis with an acceptable risk benefit balance. Diverse studies show an increase in the Standardised Detection Rate of invasive carcinomas with an increase in the optical density among others factors. In our hospital an optimisation process has been established, and as previous step, the target optical density has been increased up to 1,4 DO. The aim of this paper is to value the impact of optical density variation as much in the quality of image as in the entrance surface dose and the average dose to the glandular tissue, comparing them with the results obtained in a previous study. The study has been carried out in a sample of 106 patients, with an average age of 53,4 years, considering 212 clinical images corresponding to the two projections of a same breast with an average compressed thickness of 4,86 cm. An increase of 16,6% on the entrance surface dose and 18% on the average dose to the glandular tissue has been recorded. All the clinical images has been evaluated for the physician as adequate for diagnosis. (Author) 16 refs

Performance evaluation of different types of particle representation procedures of Particle Swarm Optimization in Job-shop Scheduling Problems

Science.gov (United States)

Izah Anuar, Nurul; Saptari, Adi

2016-02-01

This paper addresses the types of particle representation (encoding) procedures in a population-based stochastic optimization technique in solving scheduling problems known in the job-shop manufacturing environment. It intends to evaluate and compare the performance of different particle representation procedures in Particle Swarm Optimization (PSO) in the case of solving Job-shop Scheduling Problems (JSP). Particle representation procedures refer to the mapping between the particle position in PSO and the scheduling solution in JSP. It is an important step to be carried out so that each particle in PSO can represent a schedule in JSP. Three procedures such as Operation and Particle Position Sequence (OPPS), random keys representation and random-key encoding scheme are used in this study. These procedures have been tested on FT06 and FT10 benchmark problems available in the OR-Library, where the objective function is to minimize the makespan by the use of MATLAB software. Based on the experimental results, it is discovered that OPPS gives the best performance in solving both benchmark problems. The contribution of this paper is the fact that it demonstrates to the practitioners involved in complex scheduling problems that different particle representation procedures can have significant effects on the performance of PSO in solving JSP.

Optimization of a Multi-Step Procedure for Isolation of Chicken Bone Collagen

OpenAIRE

Cansu, ?mran; Boran, G?khan

2015-01-01

Chicken bone is not adequately utilized despite its high nutritional value and protein content. Although not a common raw material, chicken bone can be used in many different ways besides manufacturing of collagen products. In this study, a multi-step procedure was optimized to isolate chicken bone collagen for higher yield and quality for manufacture of collagen products. The chemical composition of chicken bone was 2.9% nitrogen corresponding to about 15.6% protein, 9.5% fat, 14.7% mineral ...

Protein losing enteropathy secondary to a pulmonary artery stent

Directory of Open Access Journals (Sweden)

Narayanswami Sreeram

2012-01-01

Full Text Available A 2-year-old patient with hypoplastic left heart syndrome presented 6 months following Fontan completion with protein-losing enteropathy (PLE. He had undergone stent implantation in the left pulmonary artery after the Norwood procedure, followed by redilation of the stent prior to Fontan completion. Combined bronchoscopic and catheterization studies during spontaneous breathing confirmed left bronchial stenosis behind the stent, and diastolic systemic ventricular pressure during expiration of 25 mm Hg. We postulate that the stent acts as a valve, against which the patient generates high expiratory pressures, which are reflected in the ventricular diastolic pressure. This may be the cause of PLE.

A materials selection procedure for sandwiched beams via parametric optimization with applications in automotive industry

International Nuclear Information System (INIS)

Aly, Mohamed F.; Hamza, Karim T.; Farag, Mahmoud M.

2014-01-01

Highlights: • Sandwich panels optimization model. • Sandwich panels design procedure. • Study of sandwich panels for automotive vehicle flooring. • Study of sandwich panels for truck cabin exterior. - Abstract: The future of automotive industry faces many challenges in meeting increasingly strict restrictions on emissions, energy usage and recyclability of components alongside the need to maintain cost competiveness. Weight reduction through innovative design of components and proper material selection can have profound impact towards attaining such goals since most of the lifecycle energy usage occurs during the operation phase of a vehicle. In electric and hybrid vehicles, weight reduction has another important effect of extending the electric mode driving range between stops or gasoline mode. This paper adopts parametric models for design optimization and material selection of sandwich panels with the objective of weight and cost minimization subject to structural integrity constraints such as strength, stiffness and buckling resistance. The proposed design procedure employs a pre-compiled library of candidate sandwich panel material combinations, for which optimization of the layered thicknesses is conducted and the best one is reported. Example demonstration studies from the automotive industry are presented for the replacement of Aluminum and Steel panels with polypropylene-filled sandwich panel alternatives

An optimization procedure for borehole emplacement in fractured media

International Nuclear Information System (INIS)

Billaux, D.; Guerin, F.

1998-01-01

Specifying the position and orientation of the 'next borehole(s)' in a fractured medium, from prior incomplete knowledge of the fracture field and depending on the objectives assigned to this new borehole(s), is a crucial point in the iterative process of site characterization. The work described here explicitly includes site knowledge and specific objectives in a tractable procedure that checks possible borehole characteristics, and rates all trial boreholes according to their compliance with objectives. The procedure is based on the following ideas : Firstly, the optimization problem is strongly constrained, since feasible borehole head locations and borehole dips are generally limited. Secondly, a borehole is an 'access point' to the fracture network. Finally, when performing a flow or tracer test, the information obtained through the monitoring system will be best if this system detects the largest possible share of the flow induced by the test, and if it cuts the most 'interesting' flow paths. The optimization is carried out in four steps. 1) All possible borehole configurations are defined and stored. Typically, several hundred possible boreholes are created. Existing boreholes are also specified. 2) Stochastic fracture networks reproducing known site characteristics are generated. 3) A purely geometrical rating of all boreholes is used to select the 'geometrically best' boreholes or groups of boreholes. 4) Among the boreholes selected by the geometrical rating, the best one(s) is chosen by simulating the experiment for which it will be used and checking flowrates through possible boreholes. This method is applied to study the emplacement of a set of five monitoring boreholes prior to the sinking of a shaft for a planned underground laboratory in a granite massif in France (Vienne site). Twelve geometrical parameters are considered for each possible borehole. A detailed statistical study helps decide on the shape of a minimization function. This is then used

General optimization procedure towards the design of a new family of minimal parameter spin-component-scaled double-hybrid density functional theory.

Science.gov (United States)

Roch, Loïc M; Baldridge, Kim K

2017-10-04

A general optimization procedure towards the development and implementation of a new family of minimal parameter spin-component-scaled double-hybrid (mSD) density functional theory (DFT) is presented. The nature of the proposed exchange-correlation functional establishes a methodology with minimal empiricism. This new family of double-hybrid (DH) density functionals is demonstrated using the PBEPBE functional, illustrating the optimization procedure to the mSD-PBEPBE method, and the performance characteristics shown for a set of non-covalent complexes covering a broad regime of weak interactions. With only two parameters, mSD-PBEPBE and its cost-effective counterpart, RI-mSD-PBEPBE, show a mean absolute error of ca. 0.4 kcal mol -1 averaged over 66 weak interacting systems. Following a successive 2D-grid refinement for a CBS extrapolation of the coefficients, the optimization procedure can be recommended for the design and implementation of a variety of additional DH methods using any of the plethora of currently available functionals.

Automated procedure for selection of optimal refueling policies for light water reactors

International Nuclear Information System (INIS)

Lin, B.I.; Zolotar, B.; Weisman, J.

1979-01-01

An automated procedure determining a minimum cost refueling policy has been developed for light water reactors. The procedure is an extension of the equilibrium core approach previously devised for pressurized water reactors (PWRs). Use of 1 1/2-group theory has improved the accuracy of the nuclear model and eliminated tedious fitting of albedos. A simple heuristic algorithm for locating a good starting policy has materially reduced PWR computing time. Inclusion of void effects and use of the Haling principle for axial flux calculations extended the nuclear model to boiling water reactors (BWRs). A good initial estimate of the refueling policy is obtained by recognizing that a nearly uniform distribution of reactivity provides low-power peaking. The initial estimate is improved upon by interchanging groups of four assemblies and is subsequently refined by interchanging individual assemblies. The method yields very favorable results, is simpler than previously proposed BWR fuel optimization schemes, and retains power cost as the objective function

A derived heuristics based multi-objective optimization procedure for micro-grid scheduling

Science.gov (United States)

Li, Xin; Deb, Kalyanmoy; Fang, Yanjun

2017-06-01

With the availability of different types of power generators to be used in an electric micro-grid system, their operation scheduling as the load demand changes with time becomes an important task. Besides satisfying load balance constraints and the generator's rated power, several other practicalities, such as limited availability of grid power and restricted ramping of power output from generators, must all be considered during the operation scheduling process, which makes it difficult to decide whether the optimization results are accurate and satisfactory. In solving such complex practical problems, heuristics-based customized optimization algorithms are suggested. However, due to nonlinear and complex interactions of variables, it is difficult to come up with heuristics in such problems off-hand. In this article, a two-step strategy is proposed in which the first task deciphers important heuristics about the problem and the second task utilizes the derived heuristics to solve the original problem in a computationally fast manner. Specifically, the specific operation scheduling is considered from a two-objective (cost and emission) point of view. The first task develops basic and advanced level knowledge bases offline from a series of prior demand-wise optimization runs and then the second task utilizes them to modify optimized solutions in an application scenario. Results on island and grid connected modes and several pragmatic formulations of the micro-grid operation scheduling problem clearly indicate the merit of the proposed two-step procedure.

Design of an X-band accelerating structure using a newly developed structural optimization procedure

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiaoxia [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Fang, Wencheng; Gu, Qiang [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhao, Zhentang, E-mail: zhaozhentang@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

2017-05-11

An X-band high gradient accelerating structure is a challenging technology for implementation in advanced electron linear accelerator facilities. The present work discusses the design of an X-band accelerating structure for dedicated application to a compact hard X-ray free electron laser facility at the Shanghai Institute of Applied Physics, and numerous design optimizations are conducted with consideration for radio frequency (RF) breakdown, RF efficiency, short-range wakefields, and dipole/quadrupole field modes, to ensure good beam quality and a high accelerating gradient. The designed X-band accelerating structure is a constant gradient structure with a 4π/5 operating mode and input and output dual-feed couplers in a racetrack shape. The design process employs a newly developed effective optimization procedure for optimization of the X-band accelerating structure. In addition, the specific design of couplers providing high beam quality by eliminating dipole field components and reducing quadrupole field components is discussed in detail.

Package of procedures for the decision of optimization tasks by the method of branches and borders

OpenAIRE

Nestor, Natalia

2012-01-01

The practical aspects of realization of method of branches and borders are examined. The structure of package of procedures is pointed for implementation of basic operations at the decision of optimization tasks. A package is projected as a programmatic kernel which can be used for the various tasks of exhaustive search with returning.

Optimization of the procedure for the synthesis of calcium lactate pentahydrate in laboratory and semi-industrial conditions

Directory of Open Access Journals (Sweden)

Ušćumlić Gordana S.

2009-01-01

Full Text Available This paper is concerned on the development of the optimal laboratory procedure for the synthesis of calcium lactate pentahydrate and the application of obtained results in a project for a semi-industrial installation for its production. Calcium lactate is used as an additive in numerous food and pharmaceutical products. Basically, it has to satisfy quality requirements. That was the reason why the procedure for its synthesis had to be optimized in aspects of selection of reactants, their molar ratio, necessary laboratory equipment, reactant addition order, working temperature, isolation of final product from the reaction mixture, yield and product quality. A semi-industrial installation for the production of calcium lactate pentahydrate is projected on the basis of the results of this investigation. The importance of this investigation arises from the fact that this salt is not produced in Serbia and the complete quantity (about 20 t per year is imported.

A TOTP-based enhanced route optimization procedure for mobile IPv6 to reduce handover delay and signalling overhead.

Science.gov (United States)

Shah, Peer Azmat; Hasbullah, Halabi B; Lawal, Ibrahim A; Aminu Mu'azu, Abubakar; Tang Jung, Low

2014-01-01

Due to the proliferation of handheld mobile devices, multimedia applications like Voice over IP (VoIP), video conferencing, network music, and online gaming are gaining popularity in recent years. These applications are well known to be delay sensitive and resource demanding. The mobility of mobile devices, running these applications, across different networks causes delay and service disruption. Mobile IPv6 was proposed to provide mobility support to IPv6-based mobile nodes for continuous communication when they roam across different networks. However, the Route Optimization procedure in Mobile IPv6 involves the verification of mobile node's reachability at the home address and at the care-of address (home test and care-of test) that results in higher handover delays and signalling overhead. This paper presents an enhanced procedure, time-based one-time password Route Optimization (TOTP-RO), for Mobile IPv6 Route Optimization that uses the concepts of shared secret Token, time based one-time password (TOTP) along with verification of the mobile node via direct communication and maintaining the status of correspondent node's compatibility. The TOTP-RO was implemented in network simulator (NS-2) and an analytical analysis was also made. Analysis showed that TOTP-RO has lower handover delays, packet loss, and signalling overhead with an increased level of security as compared to the standard Mobile IPv6's Return-Routability-based Route Optimization (RR-RO).

A TOTP-Based Enhanced Route Optimization Procedure for Mobile IPv6 to Reduce Handover Delay and Signalling Overhead

Science.gov (United States)

Shah, Peer Azmat; Hasbullah, Halabi B.; Lawal, Ibrahim A.; Aminu Mu'azu, Abubakar; Tang Jung, Low

2014-01-01

Due to the proliferation of handheld mobile devices, multimedia applications like Voice over IP (VoIP), video conferencing, network music, and online gaming are gaining popularity in recent years. These applications are well known to be delay sensitive and resource demanding. The mobility of mobile devices, running these applications, across different networks causes delay and service disruption. Mobile IPv6 was proposed to provide mobility support to IPv6-based mobile nodes for continuous communication when they roam across different networks. However, the Route Optimization procedure in Mobile IPv6 involves the verification of mobile node's reachability at the home address and at the care-of address (home test and care-of test) that results in higher handover delays and signalling overhead. This paper presents an enhanced procedure, time-based one-time password Route Optimization (TOTP-RO), for Mobile IPv6 Route Optimization that uses the concepts of shared secret Token, time based one-time password (TOTP) along with verification of the mobile node via direct communication and maintaining the status of correspondent node's compatibility. The TOTP-RO was implemented in network simulator (NS-2) and an analytical analysis was also made. Analysis showed that TOTP-RO has lower handover delays, packet loss, and signalling overhead with an increased level of security as compared to the standard Mobile IPv6's Return-Routability-based Route Optimization (RR-RO). PMID:24688398

Optimization of instrumental neutron activation analysis method by means of 2k experimental design technique aiming the validation of analytical procedures

International Nuclear Information System (INIS)

Petroni, Robson; Moreira, Edson G.

2013-01-01

In this study optimization of procedures and standardization of Instrumental Neutron Activation Analysis (INAA) methods were carried out for the determination of the elements arsenic, chromium, cobalt, iron, rubidium, scandium, selenium and zinc in biological materials. The aim is to validate the analytical methods for future accreditation at the National Institute of Metrology, Quality and Technology (INMETRO). The 2 k experimental design was applied for evaluation of the individual contribution of selected variables of the analytical procedure in the final mass fraction result. Samples of Mussel Tissue Certified Reference Material and multi-element standards were analyzed considering the following variables: sample decay time, counting time and sample distance to detector. The standard multi-element concentration (comparator standard), mass of the sample and irradiation time were maintained constant in this procedure. By means of the statistical analysis and theoretical and experimental considerations it was determined the optimized experimental conditions for the analytical methods that will be adopted for the validation procedure of INAA methods in the Neutron Activation Analysis Laboratory (LAN) of the Research Reactor Center (CRPq) at the Nuclear and Energy Research Institute (IPEN - CNEN/SP). Optimized conditions were estimated based on the results of z-score tests, main effect and interaction effects. The results obtained with the different experimental configurations were evaluated for accuracy (precision and trueness) for each measurement. (author)

Soft Tissue Surgical Procedures for Optimizing Anterior Implant Esthetics

Science.gov (United States)

Ioannou, Andreas L.; Kotsakis, Georgios A.; McHale, Michelle G.; Lareau, Donald E.; Hinrichs, James E.; Romanos, Georgios E.

2015-01-01

Implant dentistry has been established as a predictable treatment with excellent clinical success to replace missing or nonrestorable teeth. A successful esthetic implant reconstruction is predicated on two fundamental components: the reproduction of the natural tooth characteristics on the implant crown and the establishment of soft tissue housing that will simulate a healthy periodontium. In order for an implant to optimally rehabilitate esthetics, the peri-implant soft tissues must be preserved and/or augmented by means of periodontal surgical procedures. Clinicians who practice implant dentistry should strive to achieve an esthetically successful outcome beyond just osseointegration. Knowledge of a variety of available techniques and proper treatment planning enables the clinician to meet the ever-increasing esthetic demands as requested by patients. The purpose of this paper is to enhance the implant surgeon's rationale and techniques beyond that of simply placing a functional restoration in an edentulous site to a level whereby an implant-supported restoration is placed in reconstructed soft tissue, so the site is indiscernible from a natural tooth. PMID:26124837

Optimizing Travel Time to Outpatient Interventional Radiology Procedures in a Multi-Site Hospital System Using a Google Maps Application.

Science.gov (United States)

Mandel, Jacob E; Morel-Ovalle, Louis; Boas, Franz E; Ziv, Etay; Yarmohammadi, Hooman; Deipolyi, Amy; Mohabir, Heeralall R; Erinjeri, Joseph P

2018-02-20

The purpose of this study is to determine whether a custom Google Maps application can optimize site selection when scheduling outpatient interventional radiology (IR) procedures within a multi-site hospital system. The Google Maps for Business Application Programming Interface (API) was used to develop an internal web application that uses real-time traffic data to determine estimated travel time (ETT; minutes) and estimated travel distance (ETD; miles) from a patient's home to each a nearby IR facility in our hospital system. Hypothetical patient home addresses based on the 33 cities comprising our institution's catchment area were used to determine the optimal IR site for hypothetical patients traveling from each city based on real-time traffic conditions. For 10/33 (30%) cities, there was discordance between the optimal IR site based on ETT and the optimal IR site based on ETD at non-rush hour time or rush hour time. By choosing to travel to an IR site based on ETT rather than ETD, patients from discordant cities were predicted to save an average of 7.29 min during non-rush hour (p = 0.03), and 28.80 min during rush hour (p travel time when more than one location providing IR procedures is available within the same hospital system.

Vortex Flow in the Right Atrium Surrogates Supraventricular Arrhythmia and Thrombus After Atriopulmonary Connection-Type Fontan Operation: Vortex Flow Analysis Using Conventional Cine Magnetic Resonance Imaging.

Science.gov (United States)

Shiina, Yumi; Inai, Kei; Takahashi, Tatsunori; Shimomiya, Yamato; Ishizaki, Umiko; Fukushima, Kenji; Nagao, Michinobu

2018-02-01

We developed a novel imaging technique, designated as vortex flow (VF) mapping, which presents a vortex flow visually on conventional two-dimensional (2D) cine MRI. Using it, we assessed circumferential VF patterns and influences on RA thrombus and supraventricular tachycardia (SVT) in AP connection-type Fontan circulation. Retrospectively, we enrolled 27 consecutive patients (25.1 ± 9.2 years) and 7 age-matched controls who underwent cardiac MRI. Conventional cine images acquired using a 1.5-Tesla scanner were scanned for axial and coronal cross section of the RA. We developed "vortex flow mapping" to demonstrate the ratio of the circumferential voxel movement at each phase to the total movement throughout a cardiac cycle towards the RA center. The maximum ratio was used as a magnitude of vortex flow (MVF%) in RA cine imaging. We also measured percentages of strong and weak VF areas (VFA%). Furthermore, in 10 out of 27, we compared VF between previous CMR (3.8 ± 1.5 years ago) and latest CMR. Of the patients, 15 had cardiovascular complications (Group A); 12 did not (Group B). A transaxial image showed that strong VFA% in Group A was significantly smaller than that in Group B or controls. A coronal view revealed that strong VFA% was also smaller, and weak VFA% was larger in Group A than in Group B or controls (P < 0.05, and P < 0.05). Maximum MVF% in Group A was significantly smaller than in other groups (P < 0.001). Univariate logistic analyses revealed weak VFA% on a coronal image, and serum total bilirubin level as factors affecting cardiovascular complications (Odds ratio 1.14 and 66.1, 95% CI 1.004-1.30 and 1.59-2755.6, P values < 0.05 and < 0.05, respectively). Compared to the previous CMR, smaller maximum VMF%, smaller strong VFA%, and larger weak VFA% were identified in the latest CMR. Circumferentially weak VFA% on a coronal image can be one surrogate marker of SVT and thrombus in AP connection-type Fontan circulation. This simple VF

A TOTP-Based Enhanced Route Optimization Procedure for Mobile IPv6 to Reduce Handover Delay and Signalling Overhead

Directory of Open Access Journals (Sweden)

Peer Azmat Shah

2014-01-01

Full Text Available Due to the proliferation of handheld mobile devices, multimedia applications like Voice over IP (VoIP, video conferencing, network music, and online gaming are gaining popularity in recent years. These applications are well known to be delay sensitive and resource demanding. The mobility of mobile devices, running these applications, across different networks causes delay and service disruption. Mobile IPv6 was proposed to provide mobility support to IPv6-based mobile nodes for continuous communication when they roam across different networks. However, the Route Optimization procedure in Mobile IPv6 involves the verification of mobile node’s reachability at the home address and at the care-of address (home test and care-of test that results in higher handover delays and signalling overhead. This paper presents an enhanced procedure, time-based one-time password Route Optimization (TOTP-RO, for Mobile IPv6 Route Optimization that uses the concepts of shared secret Token, time based one-time password (TOTP along with verification of the mobile node via direct communication and maintaining the status of correspondent node’s compatibility. The TOTP-RO was implemented in network simulator (NS-2 and an analytical analysis was also made. Analysis showed that TOTP-RO has lower handover delays, packet loss, and signalling overhead with an increased level of security as compared to the standard Mobile IPv6’s Return-Routability-based Route Optimization (RR-RO.

Optimization of instrumental neutron activation analysis method by means of 2{sup k} experimental design technique aiming the validation of analytical procedures

Energy Technology Data Exchange (ETDEWEB)

Petroni, Robson; Moreira, Edson G., E-mail: rpetroni@ipen.br, E-mail: emoreira@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2013-07-01

In this study optimization of procedures and standardization of Instrumental Neutron Activation Analysis (INAA) methods were carried out for the determination of the elements arsenic, chromium, cobalt, iron, rubidium, scandium, selenium and zinc in biological materials. The aim is to validate the analytical methods for future accreditation at the National Institute of Metrology, Quality and Technology (INMETRO). The 2{sup k} experimental design was applied for evaluation of the individual contribution of selected variables of the analytical procedure in the final mass fraction result. Samples of Mussel Tissue Certified Reference Material and multi-element standards were analyzed considering the following variables: sample decay time, counting time and sample distance to detector. The standard multi-element concentration (comparator standard), mass of the sample and irradiation time were maintained constant in this procedure. By means of the statistical analysis and theoretical and experimental considerations it was determined the optimized experimental conditions for the analytical methods that will be adopted for the validation procedure of INAA methods in the Neutron Activation Analysis Laboratory (LAN) of the Research Reactor Center (CRPq) at the Nuclear and Energy Research Institute (IPEN - CNEN/SP). Optimized conditions were estimated based on the results of z-score tests, main effect and interaction effects. The results obtained with the different experimental configurations were evaluated for accuracy (precision and trueness) for each measurement. (author)

Procedure-specific pain management and outcome strategies

DEFF Research Database (Denmark)

Joshi, Girish P; Schug, Stephan A; Kehlet, Henrik

2014-01-01

Optimal dynamic pain relief is a prerequisite for optimizing post-operative recovery and reducing morbidity and convalescence. Procedure-specific pain management initiative aims to overcome the limitations of conventional guidelines and provide health-care professionals with practical recommendat......, optimizing fluid therapy and optimizing post-operative nursing care with early mobilization and oral feeding are utilized....... recommendations formulated in a way that facilitates clinical decision making across all the stages of the perioperative period. The procedure-specific evidence is supplemented with data from other similar surgical procedures and clinical practices to balance benefits and risks of each analgesic technique...

Survival comparison of the Ross procedure and mechanical valve replacement with optimal self-management anticoagulation therapy: propensity-matched cohort study.

Science.gov (United States)

Mokhles, M Mostafa; Körtke, Heinrich; Stierle, Ulrich; Wagner, Otto; Charitos, Efstratios I; Bogers, Ad J J C; Gummert, Jan; Sievers, Hans-Hinrich; Takkenberg, Johanna J M

2011-01-04

It is suggested that in young adults the Ross procedure results in better late patient survival compared with mechanical prosthesis implantation. We performed a propensity score-matched study that assessed late survival in young adult patients after a Ross procedure versus that after mechanical aortic valve replacement with optimal self-management anticoagulation therapy. We selected 918 Ross patients and 406 mechanical valve patients 18 to 60 years of age without dissection, aneurysm, or mitral valve replacement who survived an elective procedure (1994 to 2008). With the use of propensity score matching, late survival was compared between the 2 groups. Two hundred fifty-three patients with a mechanical valve (mean follow-up, 6.3 years) could be propensity matched to a Ross patient (mean follow-up, 5.1 years). Mean age of the matched cohort was 47.3 years in the Ross procedure group and 48.0 years in the mechanical valve group (P=0.17); the ratio of male to female patients was 3.2 in the Ross procedure group and 2.7 in the mechanical valve group (P=0.46). Linearized all-cause mortality rate was 0.53% per patient-year in the Ross procedure group compared with 0.30% per patient-year in the mechanical valve group (matched hazard ratio, 1.86; 95% confidence interval, 0.58 to 5.91; P=0.32). Late survival was comparable to that of the general German population. In comparable patients, there is no late survival difference in the first postoperative decade between the Ross procedure and mechanical aortic valve implantation with optimal anticoagulation self-management. Survival in these selected young adult patients closely resembles that of the general population, possibly as a result of highly specialized anticoagulation self-management, better timing of surgery, and improved patient selection in recent years.

Developing Optimal Procedure of Emergency Outside Cooling Water Injection for APR1400 Extended SBO Scenario Using MARS Code

Energy Technology Data Exchange (ETDEWEB)

Hwang, Jong Rok; Oh, Seung Jong [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

2013-10-15

In this study, we examined optimum operator actions to mitigate extended SBO using MARS code. Particularly, this paper focuses on analyzing outside core cooling water injection scenario, and aimed to develop optimal extended SBO procedure. Supplying outside emergency cooling water is the key feature of flexible strategy in extended SBO situation. An optimum strategy to maintain core cooling is developed for typical extended SBO. MARS APR1400 best estimate model was used to find optimal procedure. Also RCP seal leakage effect was considered importantly. Recent Fukushima accident shows the importance of mitigation capability against extended SBO scenarios. In Korea, all nuclear power plants incorporated various measures against Fukushima-like events. For APR1400 NPP, outside connectors are installed to inject cooling water using fire trucks or portable pumps. Using these connectors, outside cooling water can be provided to reactor, steam generators (SG), containment spray system, and spent fuel pool. In U. S., similar approach is chosen to provide a diverse and flexible means to prevent fuel damage (core and SFP) in external event conditions resulting in extended loss of AC power and loss of ultimate heat sink. Hence, hardware necessary to cope with extended SBO is already available for APR1400. However, considering the complex and stressful condition encountered by operators during extended SBO, it is important to develop guidelines/procedures to best cope with the event.

Optimization in the utility maximization framework for conservation planning: a comparison of solution procedures in a study of multifunctional agriculture

Science.gov (United States)

Kreitler, Jason R.; Stoms, David M.; Davis, Frank W.

2014-01-01

Quantitative methods of spatial conservation prioritization have traditionally been applied to issues in conservation biology and reserve design, though their use in other types of natural resource management is growing. The utility maximization problem is one form of a covering problem where multiple criteria can represent the expected social benefits of conservation action. This approach allows flexibility with a problem formulation that is more general than typical reserve design problems, though the solution methods are very similar. However, few studies have addressed optimization in utility maximization problems for conservation planning, and the effect of solution procedure is largely unquantified. Therefore, this study mapped five criteria describing elements of multifunctional agriculture to determine a hypothetical conservation resource allocation plan for agricultural land conservation in the Central Valley of CA, USA. We compared solution procedures within the utility maximization framework to determine the difference between an open source integer programming approach and a greedy heuristic, and find gains from optimization of up to 12%. We also model land availability for conservation action as a stochastic process and determine the decline in total utility compared to the globally optimal set using both solution algorithms. Our results are comparable to other studies illustrating the benefits of optimization for different conservation planning problems, and highlight the importance of maximizing the effectiveness of limited funding for conservation and natural resource management.

A pilot study of short-duration sputum pretreatment procedures for optimizing smear microscopy for tuberculosis.

Directory of Open Access Journals (Sweden)

Peter Daley

2009-05-01

Full Text Available Direct sputum smear microscopy for tuberculosis (TB lacks sensitivity for the detection of acid fast bacilli. Sputum pretreatment procedures may enhance sensitivity. We did a pilot study to compare the diagnostic accuracy and incremental yield of two short-duration (<1 hour sputum pretreatment procedures to optimize direct smears among patients with suspected TB at a referral hospital in India.Blinded laboratory comparison of bleach and universal sediment processing (USP pretreated centrifuged auramine smears to direct Ziehl-Neelsen (ZN and direct auramine smears and to solid (Loweinstein-Jensen (LJ and liquid (BACTEC 460 culture. 178 pulmonary and extrapulmonary TB suspects were prospectively recruited during a one year period. Thirty six (20.2% were positive by either solid or liquid culture. Direct ZN smear detected 22 of 36 cases and direct auramine smears detected 26 of 36 cases. Bleach and USP centrifugation detected 24 cases each, providing no incremental yield beyond direct smears. When compared to combined culture, pretreated smears were not more sensitive than direct smears (66.6% vs 61.1 (ZN or 72.2 (auramine, and were not more specific (92.3% vs 93.0 (ZN or 97.2 (auramine.Short duration sputum pretreatment with bleach and USP centrifugation did not increase yield as compared to direct sputum smears. Further work is needed to confirm this in a larger study and also determine if longer duration pre-treatment might be effective in optimizing smear microscopy for TB.

Patient Dose Optimization in Fluoroscopically Guided Interventional Procedures. Final Report of a Coordinated Research Project

International Nuclear Information System (INIS)

2010-01-01

In recent years, many surgical procedures have increasingly been replaced by interventional procedures that guide catheters into the arteries under X ray fluoroscopic guidance to perform a variety of operations such as ballooning, embolization, implantation of stents etc. The radiation exposure to patients and staff in such procedures is much higher than in simple radiographic examinations like X ray of chest or abdomen such that radiation induced skin injuries to patients and eye lens opacities among workers have been reported in the 1990's and after. Interventional procedures have grown both in frequency and importance during the last decade. This Coordinated Research Project (CRP) and TECDOC were developed within the International Atomic Energy Agency's (IAEA) framework of statutory responsibility to provide for the worldwide application of the standards for the protection of people against exposure to ionizing radiation. The CRP took place between 2003 and 2005 in six countries, with a view of optimizing the radiation protection of patients undergoing interventional procedures. The Fundamental Safety Principles and the International Basic Safety Standards for Protection against Ionizing Radiation (BSS) issued by the IAEA and co-sponsored by the Food and Agriculture Organization of the United Nations (FAO), the International Labour Organization (ILO), the World Health Organization (WHO), the Pan American Health Organization (PAHO) and the Nuclear Energy Agency (NEA), among others, require the radiation protection of patients undergoing medical exposures through justification of the procedures involved and through optimization. In keeping with its responsibility on the application of standards, the IAEA programme on Radiological Protection of Patients encourages the reduction of patient doses. To facilitate this, it has issued specific advice on the application of the BSS in the field of radiology in Safety Reports Series No. 39 and the three volumes on Radiation

Application of an optimized AM procedure following a SBO in a VVER1000

International Nuclear Information System (INIS)

Cherubini, Marco; D'Auria, Francesco; Petrangeli, Gianni; Muellner, Nikolaus

2006-01-01

The University of Pisa was involved in investigations of an Accident Management procedure based on passive feed water injection. Some experiments were performed to validate this possibility (e.g. in LOBI and Bethsy facilities) and fully analyzed by thermal hydraulic system codes. Recent activities in which the University of Pisa is engaged (also as leader) are focused on VVER-1000 safety analyses. The idea is now to use the acquired knowledge to explore if a procedure based on passive feed water injection is applicable and can provide any benefits to the Russian design pressurized plant. The postulated accident is a station blackout, in such a way only passive systems are available. The proposed AM is based on secondary and primary side depressurisation in sequence. The secondary side depressurisation performed by the BRU-A valves has the scope to feed passively the SGs with the water left in the feed water lines and in the deaerators. The primary side depressurisation, via the PORV, is foreseen to keep the plant at the lowest pressure (to reduce the energy of the system) and to maximize the 'grace time' of the plant. Three cases are here considered: no operator action, application of the optimized AM sequence, application of the AM procedure at the last time when it is effective. The intention of this paper is to show that in case of an unlikely event such a SBO the implementation of a strategy based on systems not designed for specific safety application can have a large impact on the 'grace time' of the plant. (author)

[Safety of repeat median sternotomy in the palliative treatment of patients with a univentricular heart].

Science.gov (United States)

Díliz-Nava, Héctor; Meléndez-Sagaón, Isis; Tamaríz-Cruz, Orlando; García-Benítez, Luis; Araujo-Martínez, Aric; Palacios-Macedo, Alexis

To establish the morbidity and mortality of patients with univentricular hearts who underwent a repeat median sternotomy at the Instituto Nacional de Pediatría. A retrospective review was performed on the clinical charts of all patients who underwent a repeat median sternotomy from 2001 to 2016. Sixty-five patients underwent 76 surgeries by repeat median sternotomy. Fifty-nine patients had a first repeat median sternotomy, with a mean age of 36 months (range: 4-176 months) and a mean weight of 12.2 kg (range: 3.2-21.5 kg). Forty patients had a Glenn procedure, and 19 patients had a Fontan procedure. There were 17 patients with a second repeat median sternotomy, with a mean age of 89 months (range 48-156 months), and a mean weight of 22.7 kg (14.4-41 kg). A Fontan procedure was performed on all these 17 patients. A section of the right coronary artery with electrocardiographic changes and a right atrium tear that caused hypotension occurred during first repeat sternotomy. An aortic tear occurred during a second repeat sternotomy with massive bleeding and subsequent death. This represents 3.9% of re-entry injuries. It is concluded that repeat median sternotomy is a safe procedure. Copyright © 2016 Instituto Nacional de Cardiología Ignacio Chávez. Publicado por Masson Doyma México S.A. All rights reserved.

Evaluation and optimization of DNA extraction and purification procedures for soil and sediment samples.

Science.gov (United States)

Miller, D N; Bryant, J E; Madsen, E L; Ghiorse, W C

1999-11-01

We compared and statistically evaluated the effectiveness of nine DNA extraction procedures by using frozen and dried samples of two silt loam soils and a silt loam wetland sediment with different organic matter contents. The effects of different chemical extractants (sodium dodecyl sulfate [SDS], chloroform, phenol, Chelex 100, and guanadinium isothiocyanate), different physical disruption methods (bead mill homogenization and freeze-thaw lysis), and lysozyme digestion were evaluated based on the yield and molecular size of the recovered DNA. Pairwise comparisons of the nine extraction procedures revealed that bead mill homogenization with SDS combined with either chloroform or phenol optimized both the amount of DNA extracted and the molecular size of the DNA (maximum size, 16 to 20 kb). Neither lysozyme digestion before SDS treatment nor guanidine isothiocyanate treatment nor addition of Chelex 100 resin improved the DNA yields. Bead mill homogenization in a lysis mixture containing chloroform, SDS, NaCl, and phosphate-Tris buffer (pH 8) was found to be the best physical lysis technique when DNA yield and cell lysis efficiency were used as criteria. The bead mill homogenization conditions were also optimized for speed and duration with two different homogenizers. Recovery of high-molecular-weight DNA was greatest when we used lower speeds and shorter times (30 to 120 s). We evaluated four different DNA purification methods (silica-based DNA binding, agarose gel electrophoresis, ammonium acetate precipitation, and Sephadex G-200 gel filtration) for DNA recovery and removal of PCR inhibitors from crude extracts. Sephadex G-200 spin column purification was found to be the best method for removing PCR-inhibiting substances while minimizing DNA loss during purification. Our results indicate that for these types of samples, optimum DNA recovery requires brief, low-speed bead mill homogenization in the presence of a phosphate-buffered SDS-chloroform mixture, followed

Procedures for Dealing with Optimism Bias in Transport Planning

DEFF Research Database (Denmark)

Flyvbjerg, Bent; Glenting, Carsten; Rønnest, Arne Kvist

of the document are to provide empirically based optimism bias up-lifts for selected reference classes of transport infrastructure projects and provide guidance on using the established uplifts to produce more realistic forecasts for the individual project's capital expenditures. Furthermore, the underlying...... causes and institutional context for optimism bias in British transport projects are discussed and some possibilities for reducing optimism bias in project preparation and decision-making are identified....

Virtual reality simulation for the optimization of endovascular procedures: current perspectives.

Science.gov (United States)

Rudarakanchana, Nung; Van Herzeele, Isabelle; Desender, Liesbeth; Cheshire, Nicholas J W

2015-01-01

Endovascular technologies are rapidly evolving, often requiring coordination and cooperation between clinicians and technicians from diverse specialties. These multidisciplinary interactions lead to challenges that are reflected in the high rate of errors occurring during endovascular procedures. Endovascular virtual reality (VR) simulation has evolved from simple benchtop devices to full physic simulators with advanced haptics and dynamic imaging and physiological controls. The latest developments in this field include the use of fully immersive simulated hybrid angiosuites to train whole endovascular teams in crisis resource management and novel technologies that enable practitioners to build VR simulations based on patient-specific anatomy. As our understanding of the skills, both technical and nontechnical, required for optimal endovascular performance improves, the requisite tools for objective assessment of these skills are being developed and will further enable the use of VR simulation in the training and assessment of endovascular interventionalists and their entire teams. Simulation training that allows deliberate practice without danger to patients may be key to bridging the gap between new endovascular technology and improved patient outcomes.

Optimal admission to higher education

DEFF Research Database (Denmark)

Albæk, Karsten

2016-01-01

that documents the relevance of theory and illustrates how to apply optimal admission procedures. Indirect gains from optimal admission procedures include the potential for increasing entire cohorts of students' probability of graduating with a higher education degree, thereby increasing the skill level...

Helicopter Flight Procedures for Community Noise Reduction

Science.gov (United States)

Greenwood, Eric

2017-01-01

A computationally efficient, semiempirical noise model suitable for maneuvering flight noise prediction is used to evaluate the community noise impact of practical variations on several helicopter flight procedures typical of normal operations. Turns, "quick-stops," approaches, climbs, and combinations of these maneuvers are assessed. Relatively small variations in flight procedures are shown to cause significant changes to Sound Exposure Levels over a wide area. Guidelines are developed for helicopter pilots intended to provide effective strategies for reducing the negative effects of helicopter noise on the community. Finally, direct optimization of flight trajectories is conducted to identify low noise optimal flight procedures and quantify the magnitude of community noise reductions that can be obtained through tailored helicopter flight procedures. Physically realizable optimal turns and approaches are identified that achieve global noise reductions of as much as 10 dBA Sound Exposure Level.

Correction: General optimization procedure towards the design of a new family of minimal parameter spin-component-scaled double-hybrid density functional theory.

Science.gov (United States)

Roch, Loïc M; Baldridge, Kim K

2018-02-07

Correction for 'General optimization procedure towards the design of a new family of minimal parameter spin-component-scaled double-hybrid density functional theory' by Loïc M. Roch and Kim K. Baldridge, Phys. Chem. Chem. Phys., 2017, 19, 26191-26200.

The Miracle Baby Grows Up: Hypoplastic Left Heart Syndrome in the Adult.

Science.gov (United States)

Lewis, Matthew; Rosenbaum, Marlon

2017-08-01

Hypoplastic left heart syndrome (HLHS) is characterized by underdevelopment of the mitral valve, left ventricle, and aorta and is ultimately palliated with a single-ventricle repair. Universally fatal in infancy prior to the advent of modern surgical techniques, the majority of HLHS patients will now reach adulthood. However, despite improvements in early survival, the HLHS population continues to face significant morbidity and early mortality. This review delineates common sources of patient morbidity and highlights areas in need of additional research for this growing segment of the adult congenital heart disease population. It has become increasingly clear that palliated adult single ventricle patients, like those with HLHS, face significant life-long morbidity from elevated systemic venous pressures as a consequence of the Fontan procedure. Downstream organ dysfunction secondary to elevated Fontan pressures has the potential to significantly impact long-term management decisions, including strategies of organ allocation. Because of the presence of a morphologic systemic right ventricle, HLHS patients may be at even higher risk than other adult patients with a Fontan. Because the adult HLHS population continues to grow, recognition of common sources of patient morbidity and mortality is becoming increasingly important. A coordinated effort between patients and providers is necessary to address the many remaining areas of clinical uncertainty to help ensure continued improvement in patient prognosis and quality of life.

Design optimization of axial flow hydraulic turbine runner: Part II - multi-objective constrained optimization method

Science.gov (United States)

Peng, Guoyi; Cao, Shuliang; Ishizuka, Masaru; Hayama, Shinji

2002-06-01

This paper is concerned with the design optimization of axial flow hydraulic turbine runner blade geometry. In order to obtain a better design plan with good performance, a new comprehensive performance optimization procedure has been presented by combining a multi-variable multi-objective constrained optimization model with a Q3D inverse computation and a performance prediction procedure. With careful analysis of the inverse design of axial hydraulic turbine runner, the total hydraulic loss and the cavitation coefficient are taken as optimization objectives and a comprehensive objective function is defined using the weight factors. Parameters of a newly proposed blade bound circulation distribution function and parameters describing positions of blade leading and training edges in the meridional flow passage are taken as optimization variables.The optimization procedure has been applied to the design optimization of a Kaplan runner with specific speed of 440 kW. Numerical results show that the performance of designed runner is successfully improved through optimization computation. The optimization model is found to be validated and it has the feature of good convergence. With the multi-objective optimization model, it is possible to control the performance of designed runner by adjusting the value of weight factors defining the comprehensive objective function. Copyright

Optimized manufacturable porous materials

DEFF Research Database (Denmark)

Andreassen, Erik; Andreasen, Casper Schousboe; Jensen, Jakob Søndergaard

Topology optimization has been used to design two-dimensional material structures with specific elastic properties, but optimized designs of three-dimensional material structures are more scarsely seen. Partly because it requires more computational power, and partly because it is a major challenge...... to include manufacturing constraints in the optimization. This work focuses on incorporating the manufacturability into the optimization procedure, allowing the resulting material structure to be manufactured directly using rapid manufacturing techniques, such as selective laser melting/sintering (SLM....../S). The available manufacturing methods are best suited for porous materials (one constituent and void), but the optimization procedure can easily include more constituents. The elasticity tensor is found from one unit cell using the homogenization method together with a standard finite element (FE) discretization...

Computational procedure of optimal inventory model involving controllable backorder rate and variable lead time with defective units

Science.gov (United States)

Lee, Wen-Chuan; Wu, Jong-Wuu; Tsou, Hsin-Hui; Lei, Chia-Ling

2012-10-01

This article considers that the number of defective units in an arrival order is a binominal random variable. We derive a modified mixture inventory model with backorders and lost sales, in which the order quantity and lead time are decision variables. In our studies, we also assume that the backorder rate is dependent on the length of lead time through the amount of shortages and let the backorder rate be a control variable. In addition, we assume that the lead time demand follows a mixture of normal distributions, and then relax the assumption about the form of the mixture of distribution functions of the lead time demand and apply the minimax distribution free procedure to solve the problem. Furthermore, we develop an algorithm procedure to obtain the optimal ordering strategy for each case. Finally, three numerical examples are also given to illustrate the results.

Structural optimization procedure of a composite wind turbine blade for reducing both material cost and blade weight

Science.gov (United States)

Hu, Weifei; Park, Dohyun; Choi, DongHoon

2013-12-01

A composite blade structure for a 2 MW horizontal axis wind turbine is optimally designed. Design requirements are simultaneously minimizing material cost and blade weight while satisfying the constraints on stress ratio, tip deflection, fatigue life and laminate layup requirements. The stress ratio and tip deflection under extreme gust loads and the fatigue life under a stochastic normal wind load are evaluated. A blade element wind load model is proposed to explain the wind pressure difference due to blade height change during rotor rotation. For fatigue life evaluation, the stress result of an implicit nonlinear dynamic analysis under a time-varying fluctuating wind is converted to the histograms of mean and amplitude of maximum stress ratio using the rainflow counting algorithm Miner's rule is employed to predict the fatigue life. After integrating and automating the whole analysis procedure an evolutionary algorithm is used to solve the discrete optimization problem.

Fuel shuffling optimization for the Delft research reactor

Energy Technology Data Exchange (ETDEWEB)

Geemert, R. van; Hoogenboom, J.E.; Gibcus, H.P.M. [Delft Univ. of Technology, Interfaculty Reactor Inst., Delft (Netherlands); Quist, A.J. [Delft Univ., Fac. of Applied Mathematics and Informatics, Delft (Netherlands)

1997-07-01

A fuel shuffling optimization procedure is proposed for the Hoger Onderwijs Reactor (HOR) in Delft, the Netherlands, a 2 MWth swimming-pool type research reactor. In order to cope with the fluctuatory behaviour of objective functions in loading pattern optimization, the proposed cyclic permutation optimization procedure features a gradual transition from global to local search behaviour via the introduction of stochastic tests for the number of fuel assemblies involved in a cyclic permutation. The possible objectives and the safety and operation constraints, as well as the optimization procedure, are discussed, followed by some optimization results for the HOR. (author) 5 figs., 4 refs.

Fuel shuffling optimization for the Delft research reactor

International Nuclear Information System (INIS)

Geemert, R. van; Hoogenboom, J.E.; Gibcus, H.P.M.; Quist, A.J.

1997-01-01

A fuel shuffling optimization procedure is proposed for the Hoger Onderwijs Reactor (HOR) in Delft, the Netherlands, a 2 MWth swimming-pool type research reactor. In order to cope with the fluctuatory behaviour of objective functions in loading pattern optimization, the proposed cyclic permutation optimization procedure features a gradual transition from global to local search behaviour via the introduction of stochastic tests for the number of fuel assemblies involved in a cyclic permutation. The possible objectives and the safety and operation constraints, as well as the optimization procedure, are discussed, followed by some optimization results for the HOR. (author)

Fuel shuffling optimization for the Delft research reactor

Energy Technology Data Exchange (ETDEWEB)

Geemert, R. van; Hoogenboom, J.E.; Gibcus, H.P.M. [Delft Univ. of Technology, Interfaculty Reactor Inst., Delft (Netherlands); Quist, A.J. [Delft Univ., Fac. of Applied Mathematics and Informatics, Delft (Netherlands)

1997-07-01

A fuel shuffling optimization procedure is proposed for the Hoger Onderwijs Reactor (HOR) in Delft, the Netherlands, a 2 MWth swimming-pool type research reactor. In order to cope with the fluctuatory behaviour of objective functions in loading pattern optimization, the proposed cyclic permutation optimization procedure features a gradual transition from global to local search behaviour via the introduction of stochastic tests for the number of fuel assemblies involved in a cyclic permutation. The possible objectives and the safety and operation constraints, as well as the optimization procedure, are discussed, followed by some optimization results for the HOR. (author)

Robust electromagnetically guided endoscopic procedure using enhanced particle swarm optimization for multimodal information fusion

International Nuclear Information System (INIS)

Luo, Xiongbiao; Wan, Ying; He, Xiangjian

2015-01-01

Purpose: Electromagnetically guided endoscopic procedure, which aims at accurately and robustly localizing the endoscope, involves multimodal sensory information during interventions. However, it still remains challenging in how to integrate these information for precise and stable endoscopic guidance. To tackle such a challenge, this paper proposes a new framework on the basis of an enhanced particle swarm optimization method to effectively fuse these information for accurate and continuous endoscope localization. Methods: The authors use the particle swarm optimization method, which is one of stochastic evolutionary computation algorithms, to effectively fuse the multimodal information including preoperative information (i.e., computed tomography images) as a frame of reference, endoscopic camera videos, and positional sensor measurements (i.e., electromagnetic sensor outputs). Since the evolutionary computation method usually limits its possible premature convergence and evolutionary factors, the authors introduce the current (endoscopic camera and electromagnetic sensor’s) observation to boost the particle swarm optimization and also adaptively update evolutionary parameters in accordance with spatial constraints and the current observation, resulting in advantageous performance in the enhanced algorithm. Results: The experimental results demonstrate that the authors’ proposed method provides a more accurate and robust endoscopic guidance framework than state-of-the-art methods. The average guidance accuracy of the authors’ framework was about 3.0 mm and 5.6° while the previous methods show at least 3.9 mm and 7.0°. The average position and orientation smoothness of their method was 1.0 mm and 1.6°, which is significantly better than the other methods at least with (2.0 mm and 2.6°). Additionally, the average visual quality of the endoscopic guidance was improved to 0.29. Conclusions: A robust electromagnetically guided endoscopy framework was

Robust electromagnetically guided endoscopic procedure using enhanced particle swarm optimization for multimodal information fusion.

Science.gov (United States)

Luo, Xiongbiao; Wan, Ying; He, Xiangjian

2015-04-01

Electromagnetically guided endoscopic procedure, which aims at accurately and robustly localizing the endoscope, involves multimodal sensory information during interventions. However, it still remains challenging in how to integrate these information for precise and stable endoscopic guidance. To tackle such a challenge, this paper proposes a new framework on the basis of an enhanced particle swarm optimization method to effectively fuse these information for accurate and continuous endoscope localization. The authors use the particle swarm optimization method, which is one of stochastic evolutionary computation algorithms, to effectively fuse the multimodal information including preoperative information (i.e., computed tomography images) as a frame of reference, endoscopic camera videos, and positional sensor measurements (i.e., electromagnetic sensor outputs). Since the evolutionary computation method usually limits its possible premature convergence and evolutionary factors, the authors introduce the current (endoscopic camera and electromagnetic sensor's) observation to boost the particle swarm optimization and also adaptively update evolutionary parameters in accordance with spatial constraints and the current observation, resulting in advantageous performance in the enhanced algorithm. The experimental results demonstrate that the authors' proposed method provides a more accurate and robust endoscopic guidance framework than state-of-the-art methods. The average guidance accuracy of the authors' framework was about 3.0 mm and 5.6° while the previous methods show at least 3.9 mm and 7.0°. The average position and orientation smoothness of their method was 1.0 mm and 1.6°, which is significantly better than the other methods at least with (2.0 mm and 2.6°). Additionally, the average visual quality of the endoscopic guidance was improved to 0.29. A robust electromagnetically guided endoscopy framework was proposed on the basis of an enhanced particle swarm

Robust electromagnetically guided endoscopic procedure using enhanced particle swarm optimization for multimodal information fusion

Energy Technology Data Exchange (ETDEWEB)

Luo, Xiongbiao, E-mail: xluo@robarts.ca, E-mail: Ying.Wan@student.uts.edu.au [Robarts Research Institute, Western University, London, Ontario N6A 5K8 (Canada); Wan, Ying, E-mail: xluo@robarts.ca, E-mail: Ying.Wan@student.uts.edu.au; He, Xiangjian [School of Computing and Communications, University of Technology, Sydney, New South Wales 2007 (Australia)

2015-04-15

Purpose: Electromagnetically guided endoscopic procedure, which aims at accurately and robustly localizing the endoscope, involves multimodal sensory information during interventions. However, it still remains challenging in how to integrate these information for precise and stable endoscopic guidance. To tackle such a challenge, this paper proposes a new framework on the basis of an enhanced particle swarm optimization method to effectively fuse these information for accurate and continuous endoscope localization. Methods: The authors use the particle swarm optimization method, which is one of stochastic evolutionary computation algorithms, to effectively fuse the multimodal information including preoperative information (i.e., computed tomography images) as a frame of reference, endoscopic camera videos, and positional sensor measurements (i.e., electromagnetic sensor outputs). Since the evolutionary computation method usually limits its possible premature convergence and evolutionary factors, the authors introduce the current (endoscopic camera and electromagnetic sensor’s) observation to boost the particle swarm optimization and also adaptively update evolutionary parameters in accordance with spatial constraints and the current observation, resulting in advantageous performance in the enhanced algorithm. Results: The experimental results demonstrate that the authors’ proposed method provides a more accurate and robust endoscopic guidance framework than state-of-the-art methods. The average guidance accuracy of the authors’ framework was about 3.0 mm and 5.6° while the previous methods show at least 3.9 mm and 7.0°. The average position and orientation smoothness of their method was 1.0 mm and 1.6°, which is significantly better than the other methods at least with (2.0 mm and 2.6°). Additionally, the average visual quality of the endoscopic guidance was improved to 0.29. Conclusions: A robust electromagnetically guided endoscopy framework was

Optimization of somatic embryogenesis procedure for commercial ...

African Journals Online (AJOL)

The first objective of this study was to assess and optimize somatic embryo production in a genetically diverse range of cacao genotypes. The primary and secondary somatic embryogenesis response of eight promising cacao clones and a positive control was evaluated using modified versions of standard protocols.

Optimal Brain Surgeon on Artificial Neural Networks in

DEFF Research Database (Denmark)

Christiansen, Niels Hørbye; Job, Jonas Hultmann; Klyver, Katrine

2012-01-01

It is shown how the procedure know as optimal brain surgeon can be used to trim and optimize artificial neural networks in nonlinear structural dynamics. Beside optimizing the neural network, and thereby minimizing computational cost in simulation, the surgery procedure can also serve as a quick...

Multiparameter optimization of mammography: an update

Science.gov (United States)

Jafroudi, Hamid; Muntz, E. P.; Jennings, Robert J.

1994-05-01

Previously in this forum we have reported the application of multiparameter optimization techniques to the design of a minimum dose mammography system. The approach used a reference system to define the physical imaging performance required and the dose to which the dose for the optimized system should be compared. During the course of implementing the resulting design in hardware suitable for laboratory testing, the state of the art in mammographic imaging changed, so that the original reference system, which did not have a grid, was no longer appropriate. A reference system with a grid was selected in response to this change, and at the same time the optimization procedure was modified, to make it more general and to facilitate study of the optimized design under a variety of conditions. We report the changes in the procedure, and the results obtained using the revised procedure and the up- to-date reference system. Our results, which are supported by laboratory measurements, indicate that the optimized design can image small objects as well as the reference system using only about 30% of the dose required by the reference system. Hardware meeting the specification produced by the optimization procedure and suitable for clinical use is currently under evaluation in the Diagnostic Radiology Department at the Clinical Center, NH.

Topology optimization of microwave waveguide filters

DEFF Research Database (Denmark)

Aage, Niels; Johansen, Villads Egede

2017-01-01

We present a density based topology optimization approach for the design of metallic microwave insert filters. A two-phase optimization procedure is proposed in which we, starting from a uniform design, first optimize to obtain a set of spectral varying resonators followed by a band gap optimizat......We present a density based topology optimization approach for the design of metallic microwave insert filters. A two-phase optimization procedure is proposed in which we, starting from a uniform design, first optimize to obtain a set of spectral varying resonators followed by a band gap...... little resemblance to standard filter layouts and hence the proposed design method offers a new design tool in microwave engineering....

Optimization of simulated moving bed (SMB) chromatography: a multi-level optimization procedure

DEFF Research Database (Denmark)

Jørgensen, Sten Bay; Lim, Young-il

2004-01-01

objective functions (productivity and desorbent consumption), employing the standing wave analysis, the true moving bed (TMB) model and the simulated moving bed (SMB) model. The procedure is constructed on a non-worse solution property advancing level by level and its solution does not mean a global optimum...

Optimal learning with Bernstein online aggregation

DEFF Research Database (Denmark)

Wintenberger, Olivier

2017-01-01

batch version achieves the fast rate of convergence log (M) / n in deviation. The BOA procedure is the first online algorithm that satisfies this optimal fast rate. The second order refinement is required to achieve the optimality in deviation as the classical exponential weights cannot be optimal, see...... is shown to be sufficiently small to assert the fast rate in the iid setting when the loss is Lipschitz and strongly convex. We also introduce a multiple learning rates version of BOA. This fully adaptive BOA procedure is also optimal, up to a log log (n) factor....

Optimal truss and frame design from projected homogenization-based topology optimization

DEFF Research Database (Denmark)

Larsen, S. D.; Sigmund, O.; Groen, J. P.

2018-01-01

In this article, we propose a novel method to obtain a near-optimal frame structure, based on the solution of a homogenization-based topology optimization model. The presented approach exploits the equivalence between Michell’s problem of least-weight trusses and a compliance minimization problem...... using optimal rank-2 laminates in the low volume fraction limit. In a fully automated procedure, a discrete structure is extracted from the homogenization-based continuum model. This near-optimal structure is post-optimized as a frame, where the bending stiffness is continuously decreased, to allow...

Abdominoplasty for Ladd's procedure: optimizing access and esthetics

African Journals Online (AJOL)

often-displeasing incision and visible scar. ... inception and is traditionally performed by making a ... procedure, these highly visible surgical approaches can .... reportedthat she remained symptom free and was pleased with her nearly invisible.

Determination of optimal ultrasound planes for the initialisation of image registration during endoscopic ultrasound-guided procedures.

Science.gov (United States)

Bonmati, Ester; Hu, Yipeng; Gibson, Eli; Uribarri, Laura; Keane, Geri; Gurusami, Kurinchi; Davidson, Brian; Pereira, Stephen P; Clarkson, Matthew J; Barratt, Dean C

2018-06-01

Navigation of endoscopic ultrasound (EUS)-guided procedures of the upper gastrointestinal (GI) system can be technically challenging due to the small fields-of-view of ultrasound and optical devices, as well as the anatomical variability and limited number of orienting landmarks during navigation. Co-registration of an EUS device and a pre-procedure 3D image can enhance the ability to navigate. However, the fidelity of this contextual information depends on the accuracy of registration. The purpose of this study was to develop and test the feasibility of a simulation-based planning method for pre-selecting patient-specific EUS-visible anatomical landmark locations to maximise the accuracy and robustness of a feature-based multimodality registration method. A registration approach was adopted in which landmarks are registered to anatomical structures segmented from the pre-procedure volume. The predicted target registration errors (TREs) of EUS-CT registration were estimated using simulated visible anatomical landmarks and a Monte Carlo simulation of landmark localisation error. The optimal planes were selected based on the 90th percentile of TREs, which provide a robust and more accurate EUS-CT registration initialisation. The method was evaluated by comparing the accuracy and robustness of registrations initialised using optimised planes versus non-optimised planes using manually segmented CT images and simulated ([Formula: see text]) or retrospective clinical ([Formula: see text]) EUS landmarks. The results show a lower 90th percentile TRE when registration is initialised using the optimised planes compared with a non-optimised initialisation approach (p value [Formula: see text]). The proposed simulation-based method to find optimised EUS planes and landmarks for EUS-guided procedures may have the potential to improve registration accuracy. Further work will investigate applying the technique in a clinical setting.

Reliability Based Optimization of Structural Systems

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

1987-01-01

The optimization problem to design structural systems such that the reliability is satisfactory during the whole lifetime of the structure is considered in this paper. Some of the quantities modelling the loads and the strength of the structure are modelled as random variables. The reliability...... is estimated using first. order reliability methods ( FORM ). The design problem is formulated as the optimization problem to minimize a given cost function such that the reliability of the single elements satisfies given requirements or such that the systems reliability satisfies a given requirement....... For these optimization problems it is described how a sensitivity analysis can be performed. Next, new optimization procedures to solve the optimization problems are presented. Two of these procedures solve the system reliability based optimization problem sequentially using quasi-analytical derivatives. Finally...

Optimization of Radiological Protection in Pediatric Patients Undergoing Common Conventional Radiological Procedures: Effectiveness of Increasing the Film to Focus Distance (FFD

Directory of Open Access Journals (Sweden)

Vahid Karami

2017-04-01

Full Text Available Background Increasing the x-ray film to focus distance (FFD, has been recommended as a practical dose optimization tool for patients undergoing conventional radiological procedures. In the previous study, we demonstrated a 32% reduction in absorbed dose is achievable due to increasing the FFD from 100 to 130 cm during pediatric chest radiography. The aim of this study was to examine whether increasing the FFD from 100 to 130 cm is equally effective for other common radiological procedures and performing a literature review of published studies to address the feasibility and probable limitations against implementing this optimization tool in clinical practice. Materials and Methods Radiographic examination of the pelvis (AP view, abdomen (AP view, skull (AP and lateral view, and spine (AP and lateral view, were taken of pediatric patients. The radiation dose and image quality of a radiological procedure is measured in FFD of 100 cm (reference FFD and 130 cm (increased FFD. The thermo-luminescent dosimeters (TLD were used for radiation dose measurements and visual grading analysis (VGA for image quality assessments. Results: Statistically significant reduction in the ESD ranged from 21.91% for the lateral skull projection to 35.24% for the lateral spine projection was obtained, when the FFD was increased from 100 to 130 cm (P0.05. Conclusion Increasing the FFD from 100 to 130 cm has significantly reduced radiation exposure without affecting on image quality. Our findings are commensurate with the literatures and emphasized that radiographers should learn to use of an updated reference FFD of 130 cm in clinical practice.

Virtual reality simulation for the optimization of endovascular procedures: current perspectives

Directory of Open Access Journals (Sweden)

Rudarakanchana N

2015-03-01

Full Text Available Nung Rudarakanchana,1 Isabelle Van Herzeele,2 Liesbeth Desender,2 Nicholas JW Cheshire1 1Department of Surgery, Imperial College London, London, UK; 2Department of Thoracic and Vascular Surgery, Ghent University Hospital, Ghent, BelgiumOn behalf of EVEREST (European Virtual reality Endovascular RESearch TeamAbstract: Endovascular technologies are rapidly evolving, often requiring coordination and cooperation between clinicians and technicians from diverse specialties. These multidisciplinary interactions lead to challenges that are reflected in the high rate of errors occurring during endovascular procedures. Endovascular virtual reality (VR simulation has evolved from simple benchtop devices to full physic simulators with advanced haptics and dynamic imaging and physiological controls. The latest developments in this field include the use of fully immersive simulated hybrid angiosuites to train whole endovascular teams in crisis resource management and novel technologies that enable practitioners to build VR simulations based on patient-specific anatomy. As our understanding of the skills, both technical and nontechnical, required for optimal endovascular performance improves, the requisite tools for objective assessment of these skills are being developed and will further enable the use of VR simulation in the training and assessment of endovascular interventionalists and their entire teams. Simulation training that allows deliberate practice without danger to patients may be key to bridging the gap between new endovascular technology and improved patient outcomes.Keywords: virtual reality, simulation, endovascular, aneurysm

Numerical modeling and optimization of the Iguassu gas centrifuge

Science.gov (United States)

Bogovalov, S. V.; Borman, V. D.; Borisevich, V. D.; Tronin, V. N.; Tronin, I. V.

2017-07-01

The full procedure of the numerical calculation of the optimized parameters of the Iguassu gas centrifuge (GC) is under discussion. The procedure consists of a few steps. On the first step the problem of a hydrodynamical flow of the gas in the rotating rotor of the GC is solved numerically. On the second step the problem of diffusion of the binary mixture of isotopes is solved. The separation power of the gas centrifuge is calculated after that. On the last step the time consuming procedure of optimization of the GC is performed providing us the maximum of the separation power. The optimization is based on the BOBYQA method exploring the results of numerical simulations of the hydrodynamics and diffusion of the mixture of isotopes. Fast convergence of calculations is achieved due to exploring of a direct solver at the solution of the hydrodynamical and diffusion parts of the problem. Optimized separative power and optimal internal parameters of the Iguassu GC with 1 m rotor were calculated using the developed approach. Optimization procedure converges in 45 iterations taking 811 minutes.

Robot-assisted procedures in pediatric neurosurgery.

Science.gov (United States)

De Benedictis, Alessandro; Trezza, Andrea; Carai, Andrea; Genovese, Elisabetta; Procaccini, Emidio; Messina, Raffaella; Randi, Franco; Cossu, Silvia; Esposito, Giacomo; Palma, Paolo; Amante, Paolina; Rizzi, Michele; Marras, Carlo Efisio

2017-05-01

OBJECTIVE During the last 3 decades, robotic technology has rapidly spread across several surgical fields due to the continuous evolution of its versatility, stability, dexterity, and haptic properties. Neurosurgery pioneered the development of robotics, with the aim of improving the quality of several procedures requiring a high degree of accuracy and safety. Moreover, robot-guided approaches are of special interest in pediatric patients, who often have altered anatomy and challenging relationships between the diseased and eloquent structures. Nevertheless, the use of robots has been rarely reported in children. In this work, the authors describe their experience using the ROSA device (Robotized Stereotactic Assistant) in the neurosurgical management of a pediatric population. METHODS Between 2011 and 2016, 116 children underwent ROSA-assisted procedures for a variety of diseases (epilepsy, brain tumors, intra- or extraventricular and tumor cysts, obstructive hydrocephalus, and movement and behavioral disorders). Each patient received accurate preoperative planning of optimal trajectories, intraoperative frameless registration, surgical treatment using specific instruments held by the robotic arm, and postoperative CT or MR imaging. RESULTS The authors performed 128 consecutive surgeries, including implantation of 386 electrodes for stereo-electroencephalography (36 procedures), neuroendoscopy (42 procedures), stereotactic biopsy (26 procedures), pallidotomy (12 procedures), shunt placement (6 procedures), deep brain stimulation procedures (3 procedures), and stereotactic cyst aspiration (3 procedures). For each procedure, the authors analyzed and discussed accuracy, timing, and complications. CONCLUSIONS To the best their knowledge, the authors present the largest reported series of pediatric neurosurgical cases assisted by robotic support. The ROSA system provided improved safety and feasibility of minimally invasive approaches, thus optimizing the surgical

Topology optimized electrothermal polysilicon microgrippers

DEFF Research Database (Denmark)

Sardan Sukas, Özlem; Petersen, Dirch Hjorth; Mølhave, Kristian

2008-01-01

This paper presents the topology optimized design procedure and fabrication of electrothermal polysilicon microgrippers for nanomanipulation purposes. Performance of the optimized microactuators is compared with a conventional three-beam microactuator design through finite element analysis...

Optimized molecular reconstruction procedure combining hybrid reverse Monte Carlo and molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Bousige, Colin; Boţan, Alexandru; Coasne, Benoît, E-mail: coasne@mit.edu [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); UMI 3466 CNRS-MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Ulm, Franz-Josef [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Pellenq, Roland J.-M. [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); UMI 3466 CNRS-MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); CINaM, CNRS/Aix Marseille Université, Campus de Luminy, 13288 Marseille Cedex 09 (France)

2015-03-21

We report an efficient atom-scale reconstruction method that consists of combining the Hybrid Reverse Monte Carlo algorithm (HRMC) with Molecular Dynamics (MD) in the framework of a simulated annealing technique. In the spirit of the experimentally constrained molecular relaxation technique [Biswas et al., Phys. Rev. B 69, 195207 (2004)], this modified procedure offers a refined strategy in the field of reconstruction techniques, with special interest for heterogeneous and disordered solids such as amorphous porous materials. While the HRMC method generates physical structures, thanks to the use of energy penalties, the combination with MD makes the method at least one order of magnitude faster than HRMC simulations to obtain structures of similar quality. Furthermore, in order to ensure the transferability of this technique, we provide rational arguments to select the various input parameters such as the relative weight ω of the energy penalty with respect to the structure optimization. By applying the method to disordered porous carbons, we show that adsorption properties provide data to test the global texture of the reconstructed sample but are only weakly sensitive to the presence of defects. In contrast, the vibrational properties such as the phonon density of states are found to be very sensitive to the local structure of the sample.

Evaluation of relevant information for optimal reflector modeling through data assimilation procedures

International Nuclear Information System (INIS)

Argaud, J.P.; Bouriquet, B.; Clerc, T.; Lucet-Sanchez, F.; Poncot, A.

2015-01-01

The goal of this study is to look after the amount of information that is mandatory to get a relevant parameters optimisation by data assimilation for physical models in neutronic diffusion calculations, and to determine what is the best information to reach the optimum of accuracy at the cheapest cost. To evaluate the quality of the optimisation, we study the covariance matrix that represents the accuracy of the optimised parameter. This matrix is a classical output of the data assimilation procedure, and it is the main information about accuracy and sensitivity of the parameter optimal determination. We present some results collected in the field of neutronic simulation for PWR type reactor. We seek to optimise the reflector parameters that characterise the neutronic reflector surrounding the whole reactive core. On the basis of the configuration studies, it has been shown that with data assimilation we can determine a global strategy to optimise the quality of the result with respect to the amount of information provided. The consequence of this is a cost reduction in terms of measurement and/or computing time with respect to the basic approach. Another result is that using multi-campaign data rather data from a unique campaign significantly improves the efficiency of parameters optimisation

Aerodynamic shape optimization using preconditioned conjugate gradient methods

Science.gov (United States)

Burgreen, Greg W.; Baysal, Oktay

1993-01-01

In an effort to further improve upon the latest advancements made in aerodynamic shape optimization procedures, a systematic study is performed to examine several current solution methodologies as applied to various aspects of the optimization procedure. It is demonstrated that preconditioned conjugate gradient-like methodologies dramatically decrease the computational efforts required for such procedures. The design problem investigated is the shape optimization of the upper and lower surfaces of an initially symmetric (NACA-012) airfoil in inviscid transonic flow and at zero degree angle-of-attack. The complete surface shape is represented using a Bezier-Bernstein polynomial. The present optimization method then automatically obtains supercritical airfoil shapes over a variety of freestream Mach numbers. Furthermore, the best optimization strategy examined resulted in a factor of 8 decrease in computational time as well as a factor of 4 decrease in memory over the most efficient strategies in current use.

Improving the efficiency of aerodynamic shape optimization

Science.gov (United States)

Burgreen, Greg W.; Baysal, Oktay; Eleshaky, Mohamed E.

1994-01-01

The computational efficiency of an aerodynamic shape optimization procedure that is based on discrete sensitivity analysis is increased through the implementation of two improvements. The first improvement involves replacing a grid-point-based approach for surface representation with a Bezier-Bernstein polynomial parameterization of the surface. Explicit analytical expressions for the grid sensitivity terms are developed for both approaches. The second improvement proposes the use of Newton's method in lieu of an alternating direction implicit methodology to calculate the highly converged flow solutions that are required to compute the sensitivity coefficients. The modified design procedure is demonstrated by optimizing the shape of an internal-external nozzle configuration. Practically identical optimization results are obtained that are independent of the method used to represent the surface. A substantial factor of 8 decrease in computational time for the optimization process is achieved by implementing both of the design procedure improvements.

Status of systemic to pulmonary arterial collateral flow after the fontan procedure.

Science.gov (United States)

Whitehead, Kevin K; Harris, Matthew A; Glatz, Andrew C; Gillespie, Matthew J; DiMaria, Michael V; Harrison, Neil E; Dori, Yoav; Keller, Marc S; Rome, Jonathan J; Fogel, Mark A

2015-06-15

The investigators recently validated a method of quantifying systemic-to-pulmonary arterial collateral flow using phase-contrast magnetic resonance imaging velocity mapping. Cross-sectional data suggest decreased collateral flow in patients with total cavopulmonary connections (TCPCs) compared with those with superior cavopulmonary connections (SCPCs). However, no studies have examined serial changes in collateral flow from SCPCs to TCPCs in the same patients. The aim of this study was to examine differences in collateral flow between patients with SCPCs and those with TCPCs. Collateral flow was quantified by 2 independent measures from 250 single-ventricle studies in 219 different patients (115 SCPC and 135 TCPC studies, 31 patients with both) and 18 controls, during routine studies using through-plane phase-contrast magnetic resonance imaging. Collateral flow was indexed to body surface area, aortic flow, and pulmonary venous flow. Regardless of indexing method, SCPC patients had significantly higher collateral flow than TCPC patients (1.64 ± 0.8 vs 1.03 ± 0.8 L/min/m(2), p <0.001). In 31 patients who underwent serial examinations, collateral flow as a fraction of aortic flow increased early after TCPC completion. In TCPC patients, indexed collateral flow demonstrated a significant negative correlation with time from TCPC. In conclusion, SCPC and TCPC patients demonstrate substantial collateral flow, with SCPC patients having higher collateral flow than TCPC patients overall. On the basis of the paired subset analysis, collateral flow does not decrease in the short term after TCPC completion and trends toward an increase. In the long term, however, collateral flow decreases over time after TCPC completion. Copyright © 2015 Elsevier Inc. All rights reserved.

Research on Operating Procedure Development in View of RCM Theory

International Nuclear Information System (INIS)

Shi, J.

2015-01-01

The operation of NPPs (nuclear power plants) is closely related to SSCs (Structure, System and Component) function implementations and failure recoveries, and strictly follows operating procedure. The philosophy of RCM (Reliability Centered Maintenance) which is a widely-used systematic engineering approach in industry focusing on likewise facility functions and effectiveness of maintenance is accepted in relative analysis of NPPs operation in this paper. Based on the theory of RCM, the paper will discuss general logic of operating procedure development and framework optimization as well combining NPPs engineering design. Since the quality of operating procedures has a significant impact on the safe and reliable operation of NPPs, the paper provides a proposed operating procedure development logic diagramme for reference for the procedure optimization task ahead. (author)

Low emittance lattice optimization using a multi-objective evolutionary algorithm

International Nuclear Information System (INIS)

Gao Weiwei; Wang Lin; Li Weimin; He Duohui

2011-01-01

A low emittance lattice design and optimization procedure are systematically studied with a non-dominated sorting-based multi-objective evolutionary algorithm which not only globally searches the low emittance lattice, but also optimizes some beam quantities such as betatron tunes, momentum compaction factor and dispersion function simultaneously. In this paper the detailed algorithm and lattice design procedure are presented. The Hefei light source upgrade project storage ring lattice, with fixed magnet layout, is designed to illustrate this optimization procedure. (authors)

Biaxial testing for fabrics and foils optimizing devices and procedures

CERN Document Server

Beccarelli, Paolo

2015-01-01

This book offers a well-structured, critical review of current design practice for tensioned membrane structures, including a detailed analysis of the experimental data required and critical issues relating to the lack of a set of design codes and testing procedures. The technical requirements for biaxial testing equipment are analyzed in detail, and aspects that need to be considered when developing biaxial testing procedures are emphasized. The analysis is supported by the results of a round-robin exercise comparing biaxial testing machines that involved four of the main research laboratories in the field. The biaxial testing devices and procedures presently used in Europe are extensively discussed, and information is provided on the design and implementation of a biaxial testing rig for architectural fabrics at Politecnico di Milano, which represents a benchmark in the field. The significance of the most recent developments in biaxial testing is also explored.

Topology optimization of radio frequency and microwave structures

DEFF Research Database (Denmark)

Aage, Niels

in this thesis, concerns the optimization of devices for wireless energy transfer via strongly coupled magnetic resonators. A single design problem is considered to demonstrate proof of concept. The resulting design illustrates the possibilities of the optimization method, but also reveals its numerical...... of efficient antennas and power supplies. A topology optimization methodology is proposed based on a design parameterization which incorporates the skin effect. The numerical optimization procedure is implemented in Matlab, for 2D problems, and in a parallel C++ optimization framework, for 3D design problems...... formalism, a two step optimization procedure is presented. This scheme is applied to the design and optimization of a hemispherical sub-wavelength antenna. The optimized antenna configuration displayed a ratio of radiated power to input power in excess of 99 %. The third, and last, design problem considered...

A CFD-based aerodynamic design procedure for hypersonic wind-tunnel nozzles

Science.gov (United States)

Korte, John J.

1993-01-01

A new procedure which unifies the best of current classical design practices, computational fluid dynamics (CFD), and optimization procedures is demonstrated for designing the aerodynamic lines of hypersonic wind-tunnel nozzles. The new procedure can be used to design hypersonic wind tunnel nozzles with thick boundary layers where the classical design procedure has been shown to break down. An efficient CFD code, which solves the parabolized Navier-Stokes (PNS) equations using an explicit upwind algorithm, is coupled to a least-squares (LS) optimization procedure. A LS problem is formulated to minimize the difference between the computed flow field and the objective function, consisting of the centerline Mach number distribution and the exit Mach number and flow angle profiles. The aerodynamic lines of the nozzle are defined using a cubic spline, the slopes of which are optimized with the design procedure. The advantages of the new procedure are that it allows full use of powerful CFD codes in the design process, solves an optimization problem to determine the new contour, can be used to design new nozzles or improve sections of existing nozzles, and automatically compensates the nozzle contour for viscous effects as part of the unified design procedure. The new procedure is demonstrated by designing two Mach 15, a Mach 12, and a Mach 18 helium nozzles. The flexibility of the procedure is demonstrated by designing the two Mach 15 nozzles using different constraints, the first nozzle for a fixed length and exit diameter and the second nozzle for a fixed length and throat diameter. The computed flow field for the Mach 15 least squares parabolized Navier-Stokes (LS/PNS) designed nozzle is compared with the classically designed nozzle and demonstrates a significant improvement in the flow expansion process and uniform core region.

Robust buckling optimization of laminated composite structures using discrete material optimization considering “worst” shape imperfections

DEFF Research Database (Denmark)

Henrichsen, Søren Randrup; Lindgaard, Esben; Lund, Erik

2015-01-01

Robust buckling optimal design of laminated composite structures is conducted in this work. Optimal designs are obtained by considering geometric imperfections in the optimization procedure. Discrete Material Optimization is applied to obtain optimal laminate designs. The optimal geometric...... imperfection is represented by the “worst” shape imperfection. The two optimization problems are combined through the recurrence optimization. Hereby the imperfection sensitivity of the considered structures can be studied. The recurrence optimization is demonstrated through a U-profile and a cylindrical panel...... example. The imperfection sensitivity of the optimized structure decreases during the recurrence optimization for both examples, hence robust buckling optimal structures are designed....

Approximate Reanalysis in Topology Optimization

DEFF Research Database (Denmark)

Amir, Oded; Bendsøe, Martin P.; Sigmund, Ole

2009-01-01

In the nested approach to structural optimization, most of the computational effort is invested in the solution of the finite element analysis equations. In this study, the integration of an approximate reanalysis procedure into the framework of topology optimization of continuum structures...

Analytical Tools to Improve Optimization Procedures for Lateral Flow Assays

Directory of Open Access Journals (Sweden)

Helen V. Hsieh

2017-05-01

Full Text Available Immunochromatographic or lateral flow assays (LFAs are inexpensive, easy to use, point-of-care medical diagnostic tests that are found in arenas ranging from a doctor’s office in Manhattan to a rural medical clinic in low resource settings. The simplicity in the LFA itself belies the complex task of optimization required to make the test sensitive, rapid and easy to use. Currently, the manufacturers develop LFAs by empirical optimization of material components (e.g., analytical membranes, conjugate pads and sample pads, biological reagents (e.g., antibodies, blocking reagents and buffers and the design of delivery geometry. In this paper, we will review conventional optimization and then focus on the latter and outline analytical tools, such as dynamic light scattering and optical biosensors, as well as methods, such as microfluidic flow design and mechanistic models. We are applying these tools to find non-obvious optima of lateral flow assays for improved sensitivity, specificity and manufacturing robustness.

Optimization of labelling procedure of 188rE-DMSA(v)

International Nuclear Information System (INIS)

Dantas, Danielle M.; Brambilla, Tania P.; Reis, Nicoli F.; Osso Junior, Joao A.

2011-01-01

Radionuclide therapy (RNT) is emerging as an important tool of nuclear medicine. Apart from the well established 131 I, several other promising radionuclides have been identified, among them 188 Re, 90 Y and 177 Lu. 188 Re has received a lot of attention in the past decade, due to its favourable nuclear characteristics [t 1/2 16.9 h, E b eta m ax 2.12 MeV and E g amma 155 keV (15%) suitable for imaging, including the fact that it is carrier-free and can be obtained cost-effectively through the generator 188 W- 188 Re. Biodistribution studies of 188 Re-DMSA(V) have shown that its general pharmacokinetic properties are similar to that of 99m Tc-DMSA(V), so this agent could be used for targeted radiotherapy of medullary thyroid carcinoma, bone metastases, soft tissue and others tumors. The aim of this work is to evaluate two labeling procedures for the preparation of 188 Re-DMSA(V). The first method was prepared using a commercial kit of DMSA(III) for labeling with 99m Tc at high temperature (100 deg C). The second method was prepared in a vial containing 2.5 mg of DMSA, 1.00 mg of SnCl 2 .2H 2 O and 10 mg of sodium oxalate, 10 mg of cyclodextrin, in a total volume of 2.0 mL. The pH was adjusted to 3 with 37% HCl. After labeling the solution was stirred and incubated for 30 min at room temperature. The radiochemical purity was determined using TLC-SG developed with two different solvent systems: Acetone and glycine. Preliminary results for both methods of labeling 188 Re-DMSA(V) showed that the labeling yield was >95%. Further experiments are also necessary to optimize the labeling methodology of 188 Re-DMSA(V).author)

Optimal Computing Budget Allocation for Particle Swarm Optimization in Stochastic Optimization.

Science.gov (United States)

Zhang, Si; Xu, Jie; Lee, Loo Hay; Chew, Ek Peng; Wong, Wai Peng; Chen, Chun-Hung

2017-04-01

Particle Swarm Optimization (PSO) is a popular metaheuristic for deterministic optimization. Originated in the interpretations of the movement of individuals in a bird flock or fish school, PSO introduces the concept of personal best and global best to simulate the pattern of searching for food by flocking and successfully translate the natural phenomena to the optimization of complex functions. Many real-life applications of PSO cope with stochastic problems. To solve a stochastic problem using PSO, a straightforward approach is to equally allocate computational effort among all particles and obtain the same number of samples of fitness values. This is not an efficient use of computational budget and leaves considerable room for improvement. This paper proposes a seamless integration of the concept of optimal computing budget allocation (OCBA) into PSO to improve the computational efficiency of PSO for stochastic optimization problems. We derive an asymptotically optimal allocation rule to intelligently determine the number of samples for all particles such that the PSO algorithm can efficiently select the personal best and global best when there is stochastic estimation noise in fitness values. We also propose an easy-to-implement sequential procedure. Numerical tests show that our new approach can obtain much better results using the same amount of computational effort.

Neurologic Injury and Cerebral Blood Flow In Single Ventricles Throughout Staged Surgical Reconstruction

Science.gov (United States)

Fogel, Mark A.; Li, Christine; Elci, Okan U.; Pawlowski, Tom; Schwab, Peter J.; Wilson, Felice; Nicolson, Susan C.; Montenegro, Lisa M.; Diaz, Laura; Spray, Thomas L.; Gaynor, J William; Fuller, Stephanie; Mascio, Christopher; Keller, Marc S.; Harris, Matthew A.; Whitehead, Kevin K.; Bethel, Jim; Vossough, Arastoo; Licht, Daniel J.

2017-01-01

Background Single ventricle patients experience a high rate of brain injury and adverse neurodevelopmental outcome, however, the incidence of brain abnormalities throughout surgical reconstruction and its relationship with cerebral blood flow, oxygen delivery and carbon dioxide reactivity remains unknown. Methods Single ventricle patients were studied with MRI scans immediately prior to bidirectional Glenn (pre-BDG), prior to Fontan and then 3–9 months after Fontan reconstruction. Results One hundred and sixty eight consecutive subjects recruited into the project underwent 235 scans: 63 pre-BDG (mean age 4.8+1.7 months), 118 BDG (2.9+1.4 years) and 54 after Fontan (2.4+1.0 years). Non-acute ischemic white matter changes on T2 weighted imaging, focal tissue loss, and ventriculomegaly were all more commonly detected in BDG and Fontans compared to pre-BDG (P<0.05). BDG patients has significantly higher CBF than Fontan patients. The odds of discovering brain injury adjusting for surgical stage as well as 2 or more co-existing lesions within a patient all decreased (63–75% and 44% respectively) with increasing amount of cerebral blood flow (P<0.05). In general, there was no association of oxygen delivery (with the exception of ventriculomegaly in the BDG group) or carbon dioxide reactivity with neurological injury. Conclusion Significant brain abnormalities are commonly present in single ventricle patients and detection of these lesions increase as children progress through staged surgical reconstruction with multiple co-existing lesions more common earlier than later. In addition, this study demonstrated that BDG patients had greater CBF than Fontan patients and that there exists an inverse association of various indices of CBF with these brain lesions, however, CO2 reactivity, oxygen delivery (with one exception) were not associated with brain lesion development. PMID:28031423

Mathematical calibration procedure of a capacitive sensor-based indexed metrology platform

International Nuclear Information System (INIS)

Brau-Avila, A; Valenzuela-Galvan, M; Herrera-Jimenez, V M; Santolaria, J; Aguilar, J J; Acero, R

2017-01-01

The demand for faster and more reliable measuring tasks for the control and quality assurance of modern production systems has created new challenges for the field of coordinate metrology. Thus, the search for new solutions in coordinate metrology systems and the need for the development of existing ones still persists. One example of such a system is the portable coordinate measuring machine (PCMM), the use of which in industry has considerably increased in recent years, mostly due to its flexibility for accomplishing in-line measuring tasks as well as its reduced cost and operational advantages compared to traditional coordinate measuring machines. Nevertheless, PCMMs have a significant drawback derived from the techniques applied in the verification and optimization procedures of their kinematic parameters. These techniques are based on the capture of data with the measuring instrument from a calibrated gauge object, fixed successively in various positions so that most of the instrument measuring volume is covered, which results in time-consuming, tedious and expensive verification and optimization procedures. In this work the mathematical calibration procedure of a capacitive sensor-based indexed metrology platform (IMP) is presented. This calibration procedure is based on the readings and geometric features of six capacitive sensors and their targets with nanometer resolution. The final goal of the IMP calibration procedure is to optimize the geometric features of the capacitive sensors and their targets in order to use the optimized data in the verification procedures of PCMMs. (paper)

Mathematical calibration procedure of a capacitive sensor-based indexed metrology platform

Science.gov (United States)

Brau-Avila, A.; Santolaria, J.; Acero, R.; Valenzuela-Galvan, M.; Herrera-Jimenez, V. M.; Aguilar, J. J.

2017-03-01

The demand for faster and more reliable measuring tasks for the control and quality assurance of modern production systems has created new challenges for the field of coordinate metrology. Thus, the search for new solutions in coordinate metrology systems and the need for the development of existing ones still persists. One example of such a system is the portable coordinate measuring machine (PCMM), the use of which in industry has considerably increased in recent years, mostly due to its flexibility for accomplishing in-line measuring tasks as well as its reduced cost and operational advantages compared to traditional coordinate measuring machines. Nevertheless, PCMMs have a significant drawback derived from the techniques applied in the verification and optimization procedures of their kinematic parameters. These techniques are based on the capture of data with the measuring instrument from a calibrated gauge object, fixed successively in various positions so that most of the instrument measuring volume is covered, which results in time-consuming, tedious and expensive verification and optimization procedures. In this work the mathematical calibration procedure of a capacitive sensor-based indexed metrology platform (IMP) is presented. This calibration procedure is based on the readings and geometric features of six capacitive sensors and their targets with nanometer resolution. The final goal of the IMP calibration procedure is to optimize the geometric features of the capacitive sensors and their targets in order to use the optimized data in the verification procedures of PCMMs.

Radiation safety in nuclear medicine procedures

International Nuclear Information System (INIS)

Cho, Sang Geon; Kim, Ja Hae; Song, Ho Chun

2017-01-01

Since the nuclear disaster at the Fukushima Daiichi Nuclear Power Plant in 2011, radiation safety has become an important issue in nuclear medicine. Many structured guidelines or recommendations of various academic societies or international campaigns demonstrate important issues of radiation safety in nuclear medicine procedures. There are ongoing efforts to fulfill the basic principles of radiation protection in daily nuclear medicine practice. This article reviews important principles of radiation protection in nuclear medicine procedures. Useful references, important issues, future perspectives of the optimization of nuclear medicine procedures, and diagnostic reference level are also discussed

Radiation safety in nuclear medicine procedures

Energy Technology Data Exchange (ETDEWEB)

Cho, Sang Geon; Kim, Ja Hae; Song, Ho Chun [Dept. of Nuclear Medicine, Medical Radiation Safety Research Center, Chonnam National University Hospital, Gwangju (Korea, Republic of)

2017-03-15

Since the nuclear disaster at the Fukushima Daiichi Nuclear Power Plant in 2011, radiation safety has become an important issue in nuclear medicine. Many structured guidelines or recommendations of various academic societies or international campaigns demonstrate important issues of radiation safety in nuclear medicine procedures. There are ongoing efforts to fulfill the basic principles of radiation protection in daily nuclear medicine practice. This article reviews important principles of radiation protection in nuclear medicine procedures. Useful references, important issues, future perspectives of the optimization of nuclear medicine procedures, and diagnostic reference level are also discussed.

Efficiency of performing pulmonary procedures in a shared endoscopy unit: procedure time, turnaround time, delays, and procedure waiting time.

Science.gov (United States)

Verma, Akash; Lee, Mui Yok; Wang, Chunhong; Hussein, Nurmalah B M; Selvi, Kalai; Tee, Augustine

2014-04-01

The purpose of this study was to assess the efficiency of performing pulmonary procedures in the endoscopy unit in a large teaching hospital. A prospective study from May 20 to July 19, 2013, was designed. The main outcome measures were procedure delays and their reasons, duration of procedural steps starting from patient's arrival to endoscopy unit, turnaround time, total case durations, and procedure wait time. A total of 65 procedures were observed. The most common procedure was BAL (61%) followed by TBLB (31%). Overall procedures for 35 (53.8%) of 65 patients were delayed by ≥ 30 minutes, 21/35 (60%) because of "spillover" of the gastrointestinal and surgical cases into the time block of pulmonary procedure. Time elapsed between end of pulmonary procedure and start of the next procedure was ≥ 30 minutes in 8/51 (16%) of cases. In 18/51 (35%) patients there was no next case in the room after completion of the pulmonary procedure. The average idle time of the room after the end of pulmonary procedure and start of next case or end of shift at 5:00 PM if no next case was 58 ± 53 minutes. In 17/51 (33%) patients the room's idle time was >60 minutes. A total of 52.3% of patients had the wait time >2 days and 11% had it ≥ 6 days, reason in 15/21 (71%) being unavailability of the slot. Most pulmonary procedures were delayed due to spillover of the gastrointestinal and surgical cases into the block time allocated to pulmonary procedures. The most common reason for difficulty encountered in scheduling the pulmonary procedure was slot unavailability. This caused increased procedure waiting time. The strategies to reduce procedure delays and turnaround times, along with improved scheduling methods, may have a favorable impact on the volume of procedures performed in the unit thereby optimizing the existing resources.

Optimal configuration of microstructure in ferroelectric materials by stochastic optimization

Science.gov (United States)

Jayachandran, K. P.; Guedes, J. M.; Rodrigues, H. C.

2010-07-01

An optimization procedure determining the ideal configuration at the microstructural level of ferroelectric (FE) materials is applied to maximize piezoelectricity. Piezoelectricity in ceramic FEs differs significantly from that of single crystals because of the presence of crystallites (grains) possessing crystallographic axes aligned imperfectly. The piezoelectric properties of a polycrystalline (ceramic) FE is inextricably related to the grain orientation distribution (texture). The set of combination of variables, known as solution space, which dictates the texture of a ceramic is unlimited and hence the choice of the optimal solution which maximizes the piezoelectricity is complicated. Thus, a stochastic global optimization combined with homogenization is employed for the identification of the optimal granular configuration of the FE ceramic microstructure with optimum piezoelectric properties. The macroscopic equilibrium piezoelectric properties of polycrystalline FE is calculated using mathematical homogenization at each iteration step. The configuration of grains characterized by its orientations at each iteration is generated using a randomly selected set of orientation distribution parameters. The optimization procedure applied to the single crystalline phase compares well with the experimental data. Apparent enhancement of piezoelectric coefficient d33 is observed in an optimally oriented BaTiO3 single crystal. Based on the good agreement of results with the published data in single crystals, we proceed to apply the methodology in polycrystals. A configuration of crystallites, simultaneously constraining the orientation distribution of the c-axis (polar axis) while incorporating ab-plane randomness, which would multiply the overall piezoelectricity in ceramic BaTiO3 is also identified. The orientation distribution of the c-axes is found to be a narrow Gaussian distribution centered around 45°. The piezoelectric coefficient in such a ceramic is found to

Genetic algorithm based separation cascade optimization

International Nuclear Information System (INIS)

Mahendra, A.K.; Sanyal, A.; Gouthaman, G.; Bera, T.K.

2008-01-01

The conventional separation cascade design procedure does not give an optimum design because of squaring-off, variation of flow rates and separation factor of the element with respect to stage location. Multi-component isotope separation further complicates the design procedure. Cascade design can be stated as a constrained multi-objective optimization. Cascade's expectation from the separating element is multi-objective i.e. overall separation factor, cut, optimum feed and separative power. Decision maker may aspire for more comprehensive multi-objective goals where optimization of cascade is coupled with the exploration of separating element optimization vector space. In real life there are many issues which make it important to understand the decision maker's perception of cost-quality-speed trade-off and consistency of preferences. Genetic algorithm (GA) is one such evolutionary technique that can be used for cascade design optimization. This paper addresses various issues involved in the GA based multi-objective optimization of the separation cascade. Reference point based optimization methodology with GA based Pareto optimality concept for separation cascade was found pragmatic and promising. This method should be explored, tested, examined and further developed for binary as well as multi-component separations. (author)

Geometrical Optimization Approach to Isomerization: Models and Limitations.

Science.gov (United States)

Chang, Bo Y; Shin, Seokmin; Engel, Volker; Sola, Ignacio R

2017-11-02

We study laser-driven isomerization reactions through an excited electronic state using the recently developed Geometrical Optimization procedure. Our goal is to analyze whether an initial wave packet in the ground state, with optimized amplitudes and phases, can be used to enhance the yield of the reaction at faster rates, driven by a single picosecond pulse or a pair of femtosecond pulses resonant with the electronic transition. We show that the symmetry of the system imposes limitations in the optimization procedure, such that the method rediscovers the pump-dump mechanism.

Optimal Design of Gravity Pipeline Systems Using Genetic Algorithm and Mathematical Optimization

Directory of Open Access Journals (Sweden)

maryam rohani

2015-03-01

Full Text Available In recent years, the optimal design of pipeline systems has become increasingly important in the water industry. In this study, the two methods of genetic algorithm and mathematical optimization were employed for the optimal design of pipeline systems with the objective of avoiding the water hammer effect caused by valve closure. The problem of optimal design of a pipeline system is a constrained one which should be converted to an unconstrained optimization problem using an external penalty function approach in the mathematical programming method. The quality of the optimal solution greatly depends on the value of the penalty factor that is calculated by the iterative method during the optimization procedure such that the computational effort is simultaneously minimized. The results obtained were used to compare the GA and mathematical optimization methods employed to determine their efficiency and capabilities for the problem under consideration. It was found that the mathematical optimization method exhibited a slightly better performance compared to the GA method.

k-Means: Random Sampling Procedure

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. k-Means: Random Sampling Procedure. Optimal 1-Mean is. Approximation of Centroid (Inaba et al). S = random sample of size O(1/ ); Centroid of S is a (1+ )-approx centroid of P with constant probability.

COGNITIVE FATIGUE FACILITATES PROCEDURAL SEQUENCE LEARNING

Directory of Open Access Journals (Sweden)

Guillermo eBorragán

2016-03-01

Full Text Available Enhanced procedural learning has been evidenced in conditions where cognitive control is diminished, including hypnosis, disruption of prefrontal activity and non-optimal time of the day. Another condition depleting the availability of controlled resources is cognitive fatigue. We tested the hypothesis that cognitive fatigue, eventually leading to diminished cognitive control, facilitates procedural sequence learning. In a two-day experiment, twenty-three young healthy adults were administered a serial reaction time task (SRTT following the induction of high or low levels of cognitive fatigue, in a counterbalanced order. Cognitive fatigue was induced using the Time load Dual-back (TloadDback paradigm, a dual working memory task that allows tailoring cognitive load levels to the individual's optimal performance capacity. In line with our hypothesis, reaction times in the SRTT were faster in the high- than in the low-level fatigue condition, and performance improvement showed more of a benefit from the sequential components than from motor. Altogether, our results suggest a paradoxical, facilitating impact of cognitive fatigue on procedural motor sequence learning. We propose that facilitated learning in the high-level fatigue condition stems from a reduction in the cognitive resources devoted to cognitive control processes that normally oppose automatic procedural acquisition mechanisms.

Chemometrics Optimized Extraction Procedures, Phytosynergistic Blending and in vitro Screening of Natural Enzyme Inhibitors Amongst Leaves of Tulsi, Banyan and Jamun.

Science.gov (United States)

De, Baishakhi; Bhandari, Koushik; Singla, Rajeev K; Katakam, Prakash; Samanta, Tanmoy; Kushwaha, Dilip Kumar; Gundamaraju, Rohit; Mitra, Analava

2015-10-01

Tulsi, Banyan, and Jamun are popular Indian medicinal plants with notable hypoglycemic potentials. Now the work reports chemo-profiling of the three species with in-vitro screening approach for natural enzyme inhibitors (NEIs) against enzymes pathogenic for type 2 diabetes. Further along with the chemometrics optimized extraction process technology, phyto-synergistic studies of the composite polyherbal blends have also been reported. Chemometrically optimized extraction procedures, ratios of polyherbal composites to achieve phyto-synergistic actions, and in-vitro screening of NEIs amongst leaves of Tulsi, Banyan, and Jamun. The extraction process parameters of the leaves of three plant species (Ficus benghalensis, Syzigium cumini and Ocimum sanctum) were optimized by rotatable central composite design of chemometrics so as to get maximal yield of bio-actives. Phyto-blends of three species were prepared so as to achieve synergistic antidiabetic and antioxidant potentials and the ratios were optimized by chemometrics. Next, for in vitro screening of natural enzyme inhibitors the individual leaf extracts as well as composite blends were subjected to assay procedures to see their inhibitory potentials against the enzymes pathogenic in type 2 diabetes. The antioxidant potentials were also estimated by DPPH radical scavenging, ABTS, FRAP and Dot Blot assay. Considering response surface methodology studies and from the solutions obtained using desirability function, it was found that hydro-ethanolic or methanolic solvent ratio of 52.46 ± 1.6 and at a temperature of 20.17 ± 0.6 gave an optimum yield of polyphenols with minimal chlorophyll leaching. The species also showed the presence of glycosides, alkaloids, and saponins. Composites in the ratios of 1:1:1 and 1:1:2 gave synergistic effects in terms of polyphenol yield and anti-oxidant potentials. All composites (1:1:1, 1:2:1, 2:1:1, 1:1:2) showed synergistic anti-oxidant actions. Inhibitory activities against the

Distributed Cooperative Optimal Control for Multiagent Systems on Directed Graphs: An Inverse Optimal Approach.

Science.gov (United States)

Zhang, Huaguang; Feng, Tao; Yang, Guang-Hong; Liang, Hongjing

2015-07-01

In this paper, the inverse optimal approach is employed to design distributed consensus protocols that guarantee consensus and global optimality with respect to some quadratic performance indexes for identical linear systems on a directed graph. The inverse optimal theory is developed by introducing the notion of partial stability. As a result, the necessary and sufficient conditions for inverse optimality are proposed. By means of the developed inverse optimal theory, the necessary and sufficient conditions are established for globally optimal cooperative control problems on directed graphs. Basic optimal cooperative design procedures are given based on asymptotic properties of the resulting optimal distributed consensus protocols, and the multiagent systems can reach desired consensus performance (convergence rate and damping rate) asymptotically. Finally, two examples are given to illustrate the effectiveness of the proposed methods.

Using Chemicals to Optimize Conformance Control in Fractured Reservoirs; TOPICAL

International Nuclear Information System (INIS)

Seright, Randall S.; Liang, Jenn-Tai; Schrader, Richard; Hagstrom II, John; Wang, Ying; Kumar, Ananad; Wavrik, Kathryn

2001-01-01

This report describes work performed during the third and final year of the project, Using Chemicals to Optimize Conformance Control in Fractured Reservoirs. This research project had three objectives. The first objective was to develop a capability to predict and optimize the ability of gels to reduce permeability to water more than that to oil or gas. The second objective was to develop procedures for optimizing blocking agent placement in wells where hydraulic fractures cause channeling problems. The third objective was to develop procedures to optimize blocking agent placement in naturally fractured reservoirs

Stochastic optimization methods

CERN Document Server

Marti, Kurt

2005-01-01

Optimization problems arising in practice involve random parameters. For the computation of robust optimal solutions, i.e., optimal solutions being insensitive with respect to random parameter variations, deterministic substitute problems are needed. Based on the distribution of the random data, and using decision theoretical concepts, optimization problems under stochastic uncertainty are converted into deterministic substitute problems. Due to the occurring probabilities and expectations, approximative solution techniques must be applied. Deterministic and stochastic approximation methods and their analytical properties are provided: Taylor expansion, regression and response surface methods, probability inequalities, First Order Reliability Methods, convex approximation/deterministic descent directions/efficient points, stochastic approximation methods, differentiation of probability and mean value functions. Convergence results of the resulting iterative solution procedures are given.

Portfolio Optimization in a Semi-Markov Modulated Market

International Nuclear Information System (INIS)

Ghosh, Mrinal K.; Goswami, Anindya; Kumar, Suresh K.

2009-01-01

We address a portfolio optimization problem in a semi-Markov modulated market. We study both the terminal expected utility optimization on finite time horizon and the risk-sensitive portfolio optimization on finite and infinite time horizon. We obtain optimal portfolios in relevant cases. A numerical procedure is also developed to compute the optimal expected terminal utility for finite horizon problem

A New Hybrid Whale Optimizer Algorithm with Mean Strategy of Grey Wolf Optimizer for Global Optimization

Directory of Open Access Journals (Sweden)

Narinder Singh

2018-03-01

Full Text Available The quest for an efficient nature-inspired optimization technique has continued over the last few decades. In this paper, a hybrid nature-inspired optimization technique has been proposed. The hybrid algorithm has been constructed using Mean Grey Wolf Optimizer (MGWO and Whale Optimizer Algorithm (WOA. We have utilized the spiral equation of Whale Optimizer Algorithm for two procedures in the Hybrid Approach GWO (HAGWO algorithm: (i firstly, we used the spiral equation in Grey Wolf Optimizer algorithm for balance between the exploitation and the exploration process in the new hybrid approach; and (ii secondly, we also applied this equation in the whole population in order to refrain from the premature convergence and trapping in local minima. The feasibility and effectiveness of the hybrid algorithm have been tested by solving some standard benchmarks, XOR, Baloon, Iris, Breast Cancer, Welded Beam Design, Pressure Vessel Design problems and comparing the results with those obtained through other metaheuristics. The solutions prove that the newly existing hybrid variant has higher stronger stability, faster convergence rate and computational accuracy than other nature-inspired metaheuristics on the maximum number of problems and can successfully resolve the function of constrained nonlinear optimization in reality.

Evaluation of medical radiation exposure in pediatric interventional radiology procedures

Energy Technology Data Exchange (ETDEWEB)

Navarro, Valeria Coelho Costa; Navarro, Marcus Vinicius Teixeira; Oliveira, Aline da Silva Pacheco, E-mail: vccnavarro@gmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia da Bahia (IFBA), Salvador, BA (Brazil); Maia, Ana Figueiredo [Universidade Federal de Sergipe (UFS), Aracaju, SE (Brazil); Oliveira, Adriano Dias Dourado [Sociedade Brasileira de Hemodinamica e Cardiologia Intervencionista, Salvador, BA (Brazil)

2012-07-15

Objective: To evaluate pediatric radiation exposure in procedures of interventional radiology in two hospitals in the Bahia state, aiming at contributing to delineate the scenario at the state and national levels. The knowledge of exposure levels will allow an evaluation of the necessity of doses optimization, considering that peculiarities of radiology and pediatrics become even more significant in interventional radiology procedures which involve exposure to higher radiation doses. Materials and Methods: A total of 32 procedures were evaluated in four rooms of the two main hospitals performing pediatric interventional radiology procedures in the Bahia state. Air kerma rate and kerma-area product were evaluated in 27 interventional cardiac and 5 interventional brain procedures. Results: Maximum values for air kerma rate and kerma-area product and air kerma obtained in cardiac procedures were, respectively, 129.9 Gy.cm{sup 2} and 947.0 mGy; and, for brain procedures were 83.3 Gy.cm{sup 2} and 961.0 mGy. Conclusion: The present study results showed exposure values up to 14 times higher than those found in other foreign studies, and approximating those found for procedures in adults. Such results demonstrate excessive exposure to radiation, indicating the need for constant procedures optimization and evaluation of exposure rates. (author)

Monitoring of the radioactive liquid effluents discharged from IPEN-CNEN/SP. Optimization of the procedures adopted

International Nuclear Information System (INIS)

Seki, C.R.

1990-01-01

The main purpose of a radioactive liquid effluents monitoring of a nuclear installation is to determine the amount of radioactivity discharged to the environment, as well as, to verify if this activity is below the authorized discharge limits established by the competent authority. Although this control has been established on a routine basis since the beginning of operation of the nuclear installations available at IPEN, the growing of such facilities in the last years has implied in an increase in the number of samples to be analyzed. The aim of this work is, therefore, to optimize the procedures adopted in the Environmental Monitoring Division of IPEN-CNEN/SP for the activity measurement of the liquid effluents discharged to the environment. Since these effluents are discharged to Pinheiros river, which presents a high dilution factor, a study is also carried out in order to verify if the activity present can be measured by the equipment available. (author)

Fabrication of compact and stable perovskite films with optimized precursor composition in the fast-growing procedure

Energy Technology Data Exchange (ETDEWEB)

Liu, Tanghao; Zhou, Yuanyuan; Hu, Qin; Chen, Ke; Zhang, Yifei; Yang, Wenqiang; Wu, Jiang; Ye, Fengjun; Luo, Deying; Zhu, Kai; Padture, Nitin P.; Liu, Feng; Russell, Thomas; Zhu, Rui; Gong, Qihuang

2017-06-02

The fast-growing procedure (FGP) provides a simple, high-yield and lead (Pb)-release free method to prepare perovskite films. In the FGP, the ultra-dilute perovskite precursor solution is drop-cast onto a hot (~240 degrees C) substrate, where a perovskite film grows immediately accompanied by the rapid evaporation of the host solvent. In this process, all the raw materials in the precursor solution are deposited into the final perovskite film. The potential pollution caused by Pb can be significantly reduced. Properties of the FGP-processed perovskite films can be modulated by the precursor composition. While CH3NH3Cl (MACl) affects the crystallization process and leads to full surface coverage, CH(NH2)2I (FAI) enhances the thermal stability of the film. Based on the optimized precursor composition of PbI2(1-x)FAI xMACl, x=0.75, FGP-processed planar heterojunction perovskite solar cells exhibit power conversion efficiencies (PCEs) exceeding 15% with suppressed hysteresis and excellent reproducibility.

Use of fractional factorial design for optimization of digestion procedures followed by multi-element determination of essential and non-essential elements in nuts using ICP-OES technique.

Science.gov (United States)

Momen, Awad A; Zachariadis, George A; Anthemidis, Aristidis N; Stratis, John A

2007-01-15

Two digestion procedures have been tested on nut samples for application in the determination of essential (Cr, Cu, Fe, Mg, Mn, Zn) and non-essential (Al, Ba, Cd, Pb) elements by inductively coupled plasma-optical emission spectrometry (ICP-OES). These included wet digestions with HNO(3)/H(2)SO(4) and HNO(3)/H(2)SO(4)/H(2)O(2). The later one is recommended for better analytes recoveries (relative errortime, pre-digestion time, temperature of the hot plate and sample weight) were used for optimization of sample digestion procedures. For this purpose Plackett-Burman fractional factorial design, which involve eight experiments was adopted. The factors HNO(3) and H(2)O(2) volume, and the digestion time were found to be the most important parameters. The instrumental conditions were also optimized (using peanut matrix rather than aqueous standard solutions) considering radio-frequency (rf) incident power, nebulizer argon gas flow rate and sample uptake flow rate. The analytical performance, such as limits of detection (LOD<0.74mugg(-1)), precision of the overall procedures (relative standard deviation between 2.0 and 8.2%) and accuracy (relative errors between 0.4 and 11%) were assessed statistically to evaluate the developed analytical procedures. The good agreement between measured and certified values for all analytes (relative error <11%) with respect to IAEA-331 (spinach leaves) and IAEA-359 (cabbage) indicates that the developed analytical method is well suited for further studies on the fate of major elements in nuts and possibly similar matrices.

Multidisciplinary Design Optimization of a Swash-Plate Axial Piston Pump

Directory of Open Access Journals (Sweden)

Guangjun Liu

2016-12-01

Full Text Available This work proposes an MDO (multidisciplinary design optimization procedure for a swash-plate axial piston pump based on co-simulation and integrated optimization. The integrated hydraulic-mechanical model of the pump is built to reflect its actual performance, and a hydraulic-mechanical co-simulation is conducted through data exchange between different domains. The flow ripple of the pump is optimized by using a MDO procedure. A CFD (Computational Fluid Dynamics simulation of the pump’s flow field is done, which shows that the hydrodynamic shock of the pump is improved after optimization. To verify the MDO effect, an experimental system is established to test the optimized piston pump. Experimental results show that the simulated and experimental curves are similar. The flow ripple is improved by the MDO procedure. The peak of the pressure curve is lower than before optimization, and the pressure pulsation is reduced by 0.21 MPa, which shows that the pressure pulsation is improved with the decreasing of the flow ripple. Comparing the experimental and simulation results shows that MDO method is effective and feasible in the optimization design of the pump.

Optimization procedures in mammography: First results; Procesos de Optimizacion en Mamografia. Primeros Resultados

Energy Technology Data Exchange (ETDEWEB)

Espana Lopez, M. L.; Marcos de Paz, L.; Martin Rincon, C.; Jerez Sainz, I.; Lopez Franco, M. P. [Hospital Universitario de La Princesa. Madrid (Spain)

2001-07-01

Optimization procedures in mammography using equipment with a unique target/filter combination can be carried out through such diverse factors as target optical density, technique factors for exposure, screen film combination or processing cycle, in order to obtain an image adequate for the diagnosis with an acceptable risk benefit balance. Diverse studies show an increase in the Standardised Detection Rate of invasive carcinomas with an increase in the optical density among others factors. In our hospital an optimisation process has been established, and as previous step, the target optical density has been increased up to 1,4 DO. The aim of this paper is to value the impact of optical density variation as much in the quality of image as in the entrance surface dose and the average dose to the glandular tissue, comparing them with the results obtained in a previous study. The study has been carried out in a sample of 106 patients, with an average age of 53,4 years, considering 212 clinical images corresponding to the two projections of a same breast with an average compressed thickness of 4,86 cm. An increase of 16,6% on the entrance surface dose and 18% on the average dose to the glandular tissue has been recorded. All the clinical images has been evaluated for the physician as adequate for diagnosis. (Author) 16 refs.

Neurological Injury and Cerebral Blood Flow in Single Ventricles Throughout Staged Surgical Reconstruction.

Science.gov (United States)

Fogel, Mark A; Li, Christine; Elci, Okan U; Pawlowski, Tom; Schwab, Peter J; Wilson, Felice; Nicolson, Susan C; Montenegro, Lisa M; Diaz, Laura; Spray, Thomas L; Gaynor, J William; Fuller, Stephanie; Mascio, Christopher; Keller, Marc S; Harris, Matthew A; Whitehead, Kevin K; Bethel, Jim; Vossough, Arastoo; Licht, Daniel J

2017-02-14

Patients with a single ventricle experience a high rate of brain injury and adverse neurodevelopmental outcome; however, the incidence of brain abnormalities throughout surgical reconstruction and their relationship with cerebral blood flow, oxygen delivery, and carbon dioxide reactivity remain unknown. Patients with a single ventricle were studied with magnetic resonance imaging scans immediately prior to bidirectional Glenn (pre-BDG), before Fontan (BDG), and then 3 to 9 months after Fontan reconstruction. One hundred sixty-eight consecutive subjects recruited into the project underwent 235 scans: 63 pre-BDG (mean age, 4.8±1.7 months), 118 BDG (2.9±1.4 years), and 54 after Fontan (2.4±1.0 years). Nonacute ischemic white matter changes on T2-weighted imaging, focal tissue loss, and ventriculomegaly were all more commonly detected in BDG and Fontan compared with pre-BDG patients ( P <0.05). BDG patients had significantly higher cerebral blood flow than did Fontan patients. The odds of discovering brain injury with adjustment for surgical stage as well as ≥2 coexisting lesions within a patient decreased (63%-75% and 44%, respectively) with increasing amount of cerebral blood flow ( P <0.05). In general, there was no association of oxygen delivery (except for ventriculomegaly in the BDG group) or carbon dioxide reactivity with neurological injury. Significant brain abnormalities are commonly present in patients with a single ventricle, and detection of these lesions increases as children progress through staged surgical reconstruction, with multiple coexisting lesions more common earlier than later. In addition, this study demonstrated that BDG patients had greater cerebral blood flow than did Fontan patients and that an inverse association exists of various indexes of cerebral blood flow with these brain lesions. However, CO 2 reactivity and oxygen delivery (with 1 exception) were not associated with brain lesion development. URL: http

Comparison of optimization of loading patterns on the basis of SA and PMA algorithms

International Nuclear Information System (INIS)

Beliczai, Botond

2007-01-01

Optimization of loading patterns is a very important task from economical point of view in a nuclear power plant. The optimization algorithms used for this purpose can be categorized basically into two categories: deterministic ones and stochastic ones. In the Paks nuclear power plant a deterministic optimization procedure is used to optimize the loading pattern at BOC, so that the core would have maximal reactivity reserve. To the group of stochastic optimization procedures belong mainly simulated annealing (SA) procedures and genetic algorithms (GA). There are new procedures as well, which try to combine the advantages of SAs and GAs. One of them is called population mutation annealing algorithm (PMA). In the Paks NPP we would like to introduce fuel assemblies including burnable poison (Gd) in the near future. In order to be able to find the optimal loading pattern (or near-optimal loading patterns) in that case, we have to optimize our core not only for objective functions defined at BOC, but at EOC as well. For this purpose I used stochastic algorithms (SA and PMA) to investigate loading pattern optimization results for different objective functions at BOC. (author)

Optimizing towing processes at airports

OpenAIRE

Du, Jia Yan

2015-01-01

This work addresses the optimization of push-back and towing processes at airports, as an important part of the turnaround process. A vehicle routing based scheduling model is introduced to find a cost optimal assignment of jobs to towing tractors in daily operations. A second model derives an investment strategy to optimize tractor fleet size and mix in the long-run. Column generation heuristics are proposed as solution procedures. The thesis concludes with a case study of a major European ...

Process optimization and particle engineering of micronized drug powders via milling.

Science.gov (United States)

Brunaugh, A; Smyth, H D C

2017-11-13

Process control and optimization is a critical aspect of process analytical technology (PAT), quality by design (QbD), and the implementation of continuous manufacturing procedures. While process control and optimization techniques have been utilized in other manufacturing industries for decades, the pharmaceutical industry has only recently begun to adopt these procedures. Micronization, particularly milling, is a generally low-yield, high-energy consumption process that is well suited for a process optimization mindset. This review discusses optimization of the pharmaceutical milling process through design space development, theoretical and empirical modeling, and monitoring of critical quality attributes.

Strategies for Optimal Design of Structural Systems

DEFF Research Database (Denmark)

Enevoldsen, I.; Sørensen, John Dalsgaard

1992-01-01

Reliability-based design of structural systems is considered. Especially systems where the reliability model is a series system of parallel systems are analysed. A sensitivity analysis for this class of problems is presented. Direct and sequential optimization procedures to solve the optimization...

Optimization of microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry

International Nuclear Information System (INIS)

Soylak, Mustafa; Tuzen, Mustafa; Souza, Anderson Santos; Korn, Maria das Gracas Andrade; Ferreira, Sergio Luis Costa

2007-01-01

The present paper describes the development of a microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry (FAAS). The optimization step was performed using a full factorial design (2 3 ) involving the factors: composition of the acid mixture (CMA), microwave power (MP) and radiation time (RT). The experiments of this factorial were carried out using a certified reference material of tea GBW 07605 furnished by National Research Centre for Certified Reference Materials, China, being the metal recoveries considered as response. The relative standard deviations of the method were found below 8% for the three elements. The procedure proposed was used for the determination of copper, zinc and nickel in several samples of tea from Turkey. For 10 tea samples analyzed, the concentration achieved for copper, zinc and nickel varied at 6.4-13.1, 7.0-16.5 and 3.1-5.7 (μg g -1 ), respectively

Procedural Personas for Player Decision Modeling and Procedural Content Generation

DEFF Research Database (Denmark)

Holmgård, Christoffer

2016-01-01

." These methods for constructing procedural personas are then integrated with existing procedural content generation systems, acting as critics that shape the output of these systems, optimizing generated content for different personas and by extension, different kinds of players and their decision making styles......How can player models and artificially intelligent (AI) agents be useful in early-stage iterative game and simulation design? One answer may be as ways of generating synthetic play-test data, before a game or level has ever seen a player, or when the sampled amount of play test data is very low....... This thesis explores methods for creating low-complexity, easily interpretable, generative AI agents for use in game and simulation design. Based on insights from decision theory and behavioral economics, the thesis investigates how player decision making styles may be defined, operationalised, and measured...

Numerical optimization of circulation control airfoil at high subsonic speed

Science.gov (United States)

Tai, T. C.; Kidwell, G. H., Jr.

1984-01-01

A numerical procedure for optimizing the design of the circulation control airfoil for use at high subsonic speeds is presented. The procedure consists of an optimization scheme coupled with a viscous potential flow analysis for the blowing jet. The desired airfoil is defined by a combination of three baseline shapes (cambered ellipse and cambered ellipse with drooped and spiraled trailing edges). The coefficients of these shapes are used as design variables in the optimization process. Under the constraints of lift augmentation and lift-to-drag ratios, the airfoil, optimized at free-stream Mach 0.54 and alpha = -2 degrees can be characterized as a cambered ellipse with a drooped trailing edge. Experimental tests support the performance improvement predicted by numerical optimization.

Optimized pre-thinning procedures of ion-beam thinning for TEM sample preparation by magnetorheological polishing.

Science.gov (United States)

Luo, Hu; Yin, Shaohui; Zhang, Guanhua; Liu, Chunhui; Tang, Qingchun; Guo, Meijian

2017-10-01

Ion-beam-thinning is a well-established sample preparation technique for transmission electron microscopy (TEM), but tedious procedures and labor consuming pre-thinning could seriously reduce its efficiency. In this work, we present a simple pre-thinning technique by using magnetorheological (MR) polishing to replace manual lapping and dimpling, and demonstrate the successful preparation of electron-transparent single crystal silicon samples after MR polishing and single-sided ion milling. Dimples pre-thinned to less than 30 microns and with little mechanical surface damage were repeatedly produced under optimized MR polishing conditions. Samples pre-thinned by both MR polishing and traditional technique were ion-beam thinned from the rear side until perforation, and then observed by optical microscopy and TEM. The results show that the specimen pre-thinned by MR technique was free from dimpling related defects, which were still residual in sample pre-thinned by conventional technique. Nice high-resolution TEM images could be acquired after MR polishing and one side ion-thinning. MR polishing promises to be an adaptable and efficient method for pre-thinning in preparation of TEM specimens, especially for brittle ceramics. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of Optimization Procedure for Design of Package Cushioning

Science.gov (United States)

1975-01-01

that we seek. Vibration Optimization from Random Excitation Excitation power spect : cl density S(U)j) must be specified in 1-octave frequency...CUO INCHES 3.010 INCHES t.11* INCHES •i»i. C ’Sl/llfs Bl.’Ji •COS-Is-jT •" ~» TBI «."»tf<I»l. vf»TIC»L,*xIS MGHIZONT»L J.’" l

Structural Optimization with Reliability Constraints

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Thoft-Christensen, Palle

1986-01-01

During the last 25 years considerable progress has been made in the fields of structural optimization and structural reliability theory. In classical deterministic structural optimization all variables are assumed to be deterministic. Due to the unpredictability of loads and strengths of actual......]. In this paper we consider only structures which can be modelled as systems of elasto-plastic elements, e.g. frame and truss structures. In section 2 a method to evaluate the reliability of such structural systems is presented. Based on a probabilistic point of view a modern structural optimization problem...... is formulated in section 3. The formulation is a natural extension of the commonly used formulations in determinstic structural optimization. The mathematical form of the optimization problem is briefly discussed. In section 4 two new optimization procedures especially designed for the reliability...

A model for the value of a business, some optimization problems in its operating procedures and the valuation of its debt

Science.gov (United States)

1997-12-01

In this paper we present a model for the value of a firm based on observable variables and parameters: the annual turnover, the expenses, interest rates. This value is the solution of a parabolic partial differential equation. We show how the value of the company depends on its legal status such as its liability (that is, whether it is a Limited Company or a sole trader/partnership). We give examples of how the operating procedures can be optimized (for example, whether the firm should close down, relocate etc.). Finally, we show how the model can be used to value the debt issued by the firm.

Topology Optimization and Robotic Fabrication of Advanced Timber Space-frame Structures

DEFF Research Database (Denmark)

Søndergaard, Asbjørn; Amir, Oded; Eversmann, Phillip

2016-01-01

This paper presents a novel method for integrated topology optimization and fabrication of advanced timber space-frame structures. The method, developed in research collaboration between ETH Zürich, Aarhus School of Architecture and Israel Institute of Technology, entails the coupling of truss...... processes solving timber joint intersections, robotically controlling member prefabrication, and spatial robotic assembly of the optimized timber structures. The implication of this concept is studied through pilot fabrication and load-testing of a full scale prototype structure.......-based topology optimization with digital procedures for rationalization and robotic assembly of bespoke timber members, through a procedural, cross-application workflow. Through this, a direct chaining of optimization and robotic fabrication is established, in which optimization data is driving subsequent...

Optimalization of selected RFID systems Parameters

Directory of Open Access Journals (Sweden)

Peter Vestenicky

2004-01-01

Full Text Available This paper describes procedure for maximization of RFID transponder read range. This is done by optimalization of magnetics field intensity at transponder place and by optimalization of antenna and transponder coils coupling factor. Results of this paper can be used for RFID with inductive loop, i.e. system working in near electromagnetic field.

Topology optimization of microwave waveguide filters

DEFF Research Database (Denmark)

Aage, Niels; Johansen, Villads Egede

2017-01-01

We present a density based topology optimization approach for the design of metallic microwave insert filters. A two-phase optimization procedure is proposed in which we, starting from a uniform design, first optimize to obtain a set of spectral varying resonators followed by a band gap...... optimization for the desired filter characteristics. This is illustrated through numerical experiments and comparison to a standard band pass filter design. It is seen that the carefully optimized topologies can sharpen the filter characteristics and improve performance. Furthermore, the obtained designs share...... little resemblance to standard filter layouts and hence the proposed design method offers a new design tool in microwave engineering....

Gaussian process regression for geometry optimization

Science.gov (United States)

Denzel, Alexander; Kästner, Johannes

2018-03-01

We implemented a geometry optimizer based on Gaussian process regression (GPR) to find minimum structures on potential energy surfaces. We tested both a two times differentiable form of the Matérn kernel and the squared exponential kernel. The Matérn kernel performs much better. We give a detailed description of the optimization procedures. These include overshooting the step resulting from GPR in order to obtain a higher degree of interpolation vs. extrapolation. In a benchmark against the Limited-memory Broyden-Fletcher-Goldfarb-Shanno optimizer of the DL-FIND library on 26 test systems, we found the new optimizer to generally reduce the number of required optimization steps.

Economic optimization of photovoltaic water pumping systems for irrigation

International Nuclear Information System (INIS)

Campana, P.E.; Li, H.; Zhang, J.; Zhang, R.; Liu, J.; Yan, J.

2015-01-01

Highlights: • A novel optimization procedure for photovoltaic water pumping systems for irrigation is proposed. • An hourly simulation model is the basis of the optimization procedure. • The effectiveness of the new optimization approach has been tested to an existing photovoltaic water pumping system. - Abstract: Photovoltaic water pumping technology is considered as a sustainable and economical solution to provide water for irrigation, which can halt grassland degradation and promote farmland conservation in China. The appropriate design and operation significantly depend on the available solar irradiation, crop water demand, water resources and the corresponding benefit from the crop sale. In this work, a novel optimization procedure is proposed, which takes into consideration not only the availability of groundwater resources and the effect of water supply on crop yield, but also the investment cost of photovoltaic water pumping system and the revenue from crop sale. A simulation model, which combines the dynamics of photovoltaic water pumping system, groundwater level, water supply, crop water demand and crop yield, is employed during the optimization. To prove the effectiveness of the new optimization approach, it has been applied to an existing photovoltaic water pumping system. Results show that the optimal configuration can guarantee continuous operations and lead to a substantial reduction of photovoltaic array size and consequently of the investment capital cost and the payback period. Sensitivity studies have been conducted to investigate the impacts of the prices of photovoltaic modules and forage on the optimization. Results show that the water resource is a determinant factor

Dynamic stochastic optimization

CERN Document Server

Ermoliev, Yuri; Pflug, Georg

2004-01-01

Uncertainties and changes are pervasive characteristics of modern systems involving interactions between humans, economics, nature and technology. These systems are often too complex to allow for precise evaluations and, as a result, the lack of proper management (control) may create significant risks. In order to develop robust strategies we need approaches which explic­ itly deal with uncertainties, risks and changing conditions. One rather general approach is to characterize (explicitly or implicitly) uncertainties by objec­ tive or subjective probabilities (measures of confidence or belief). This leads us to stochastic optimization problems which can rarely be solved by using the standard deterministic optimization and optimal control methods. In the stochastic optimization the accent is on problems with a large number of deci­ sion and random variables, and consequently the focus ofattention is directed to efficient solution procedures rather than to (analytical) closed-form solu­ tions. Objective an...

Topology Optimization for Conceptual Design of Reinforced Concrete Structures

DEFF Research Database (Denmark)

Amir, Oded; Bogomolny, Michael

2011-01-01

Design of reinforced concrete structures is governed by the nonlinear behavior of concrete and by its dierent strengths in tension and compression. The purpose of this article is to present a computational procedure for optimal conceptual design of reinforced concrete structures, based on topology...... must be consid- ered. Optimized distribution of material is achieved by introducing interpolation rules for both elastic and plastic material properties. Several numerical examples illustrate the capability and potential of the proposed procedure....

Procedure for Selection of Suitable Resources in Interactions in Complex Dynamic Systems Using Artificial Immunity

Directory of Open Access Journals (Sweden)

Naors Y. anadalsaleem

2017-03-01

Full Text Available The dynamic optimization procedure for -dimensional vector function of a system, the state of which is interpreted as adaptable immune cell, is considered Using the results of the theory of artificial immune systems. The procedures for estimate of monitoring results are discussed. The procedure for assessing the entropy is recommended as a general recursive estimation algorithm. The results are focused on solving the optimization problems of cognitive selection of suitable physical resources, what expands the scope of Electromagnetic compatibility.

Well-posed optimization problems

CERN Document Server

Dontchev, Asen L

1993-01-01

This book presents in a unified way the mathematical theory of well-posedness in optimization. The basic concepts of well-posedness and the links among them are studied, in particular Hadamard and Tykhonov well-posedness. Abstract optimization problems as well as applications to optimal control, calculus of variations and mathematical programming are considered. Both the pure and applied side of these topics are presented. The main subject is often introduced by heuristics, particular cases and examples. Complete proofs are provided. The expected knowledge of the reader does not extend beyond textbook (real and functional) analysis, some topology and differential equations and basic optimization. References are provided for more advanced topics. The book is addressed to mathematicians interested in optimization and related topics, and also to engineers, control theorists, economists and applied scientists who can find here a mathematical justification of practical procedures they encounter.

Communication and Procedural Models of the E-Commerce Systems

Directory of Open Access Journals (Sweden)

Petr SUCHÁNEK

2009-06-01

Full Text Available E-commerce systems became a standard interface between sellers (or suppliers and customers. One of basic condition of an e-commerce system to be efficient is correct definitions and describes of the all internal and external processes. All is targeted the customers´ needs and requirements. The optimal and most exact way how to obtain and find optimal solution of e-commerce system and its processes structure in companies is the modeling and simulation. In this article author shows basic model of communication between customers and sellers in connection with the customer feedback and procedural models of e-commerce systems in terms of e-shops. Procedural model was made with the aid of definition of SOA.

Optimization of labelling procedure of {sup 188}rE-DMSA(v)

Energy Technology Data Exchange (ETDEWEB)

Dantas, Danielle M.; Brambilla, Tania P.; Reis, Nicoli F.; Osso Junior, Joao A., E-mail: jaosso@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

Radionuclide therapy (RNT) is emerging as an important tool of nuclear medicine. Apart from the well established {sup 131}I, several other promising radionuclides have been identified, among them {sup 188}Re, {sup 90}Y and {sup 177}Lu. {sup 188}Re has received a lot of attention in the past decade, due to its favourable nuclear characteristics [t{sub 1/2} 16.9 h, E{sub b}eta{sub m}ax 2.12 MeV and E{sub g}amma 155 keV (15%) suitable for imaging, including the fact that it is carrier-free and can be obtained cost-effectively through the generator {sup 188}W-{sup 188}Re. Biodistribution studies of {sup 188}Re-DMSA(V) have shown that its general pharmacokinetic properties are similar to that of {sup 99m}Tc-DMSA(V), so this agent could be used for targeted radiotherapy of medullary thyroid carcinoma, bone metastases, soft tissue and others tumors. The aim of this work is to evaluate two labeling procedures for the preparation of {sup 188}Re-DMSA(V). The first method was prepared using a commercial kit of DMSA(III) for labeling with {sup 99m}Tc at high temperature (100 deg C). The second method was prepared in a vial containing 2.5 mg of DMSA, 1.00 mg of SnCl{sub 2}.2H{sub 2}O and 10 mg of sodium oxalate, 10 mg of cyclodextrin, in a total volume of 2.0 mL. The pH was adjusted to 3 with 37% HCl. After labeling the solution was stirred and incubated for 30 min at room temperature. The radiochemical purity was determined using TLC-SG developed with two different solvent systems: Acetone and glycine. Preliminary results for both methods of labeling {sup 188}Re-DMSA(V) showed that the labeling yield was >95%. Further experiments are also necessary to optimize the labeling methodology of {sup 188}Re-DMSA(V).author)

Topology optimization for nano-photonics

DEFF Research Database (Denmark)

Jensen, Jakob Søndergaard; Sigmund, Ole

2011-01-01

Topology optimization is a computational tool that can be used for the systematic design of photonic crystals, waveguides, resonators, filters and plasmonics. The method was originally developed for mechanical design problems but has within the last six years been applied to a range of photonics...... applications. Topology optimization may be based on finite element and finite difference type modeling methods in both frequency and time domain. The basic idea is that the material density of each element or grid point is a design variable, hence the geometry is parameterized in a pixel-like fashion....... The optimization problem is efficiently solved using mathematical programming-based optimization methods and analytical gradient calculations. The paper reviews the basic procedures behind topology optimization, a large number of applications ranging from photonic crystal design to surface plasmonic devices...

Geometrical optimization of the dense plasma focus

International Nuclear Information System (INIS)

Lee, S.; Chen, Y.H.

1982-01-01

A 12 kJ DPF device with a periodic time of 12μsec, UMDPF1 has been optimized geometrically to produce a higher neutron yield of 1.5x10 9 at 10 torr filling pressure than from the same device before optimization. With the same optimization procedure a faster DPF device with a periodic time of 3.7μsec, UMDPF2, of the same energy has also been optimized to give a peak neutron yield of 6.3x10 9 at 16 torr filling pressure. Experimental evidence shows that over and above the increase in neutron production due to an increase in current according to the Isup(3.3) scaling law, a faster current rise time may have an additional effect of enhancement in neutron production. The outcome of this project is that a new high pressure regime of 16 torr with an enhanced neutron yield of 6.3x10 9 and improved yield reproducibility for an input energy of 12 kJ has thus been established. There is every reason to believe that this optimization procedure can be extended to other DPF devices. (author)

Procedure for the use of the code SAGAPO-A and auxiliary programs

International Nuclear Information System (INIS)

Cevolani, S.

1981-06-01

This paper describes the procedure developed in order to optimize the use of the computer code SAGAPO-A for the thermo-fluid-dynamic analysis of gas cooled fuel element bundles. The first item of this procedure concerns the dynamic dimensioning of the code, having as target the optimization of the computer storage requirement. The second item concerns the graphical output: the results of the calculation are plotted together with the experimental results, in order to allow an immediate evaluation of the calculation. (orig.) [de

Optimal and efficient decoding of concatenated quantum block codes

International Nuclear Information System (INIS)

Poulin, David

2006-01-01

We consider the problem of optimally decoding a quantum error correction code--that is, to find the optimal recovery procedure given the outcomes of partial ''check'' measurements on the system. In general, this problem is NP hard. However, we demonstrate that for concatenated block codes, the optimal decoding can be efficiently computed using a message-passing algorithm. We compare the performance of the message-passing algorithm to that of the widespread blockwise hard decoding technique. Our Monte Carlo results using the five-qubit and Steane's code on a depolarizing channel demonstrate significant advantages of the message-passing algorithms in two respects: (i) Optimal decoding increases by as much as 94% the error threshold below which the error correction procedure can be used to reliably send information over a noisy channel; and (ii) for noise levels below these thresholds, the probability of error after optimal decoding is suppressed at a significantly higher rate, leading to a substantial reduction of the error correction overhead

Optimization and audit of radiation dose during percutaneous transluminal coronary angioplasty

International Nuclear Information System (INIS)

Livingstone, Roshan S.; Timothy Peace, B.S.; Chandy, Sunil; Gorge, Paul V.; Pati, Purendra

2007-01-01

The percutaneous transluminal coronary angioplasty (PTCA) is one of the interventional procedures which impart high radiation doses to patients compared to the other cardiologic procedures. This study intends to audit and optimize radiation dose imparted to patients undergoing PTCA. Forty-four patients who underwent PTCA involving single or multiple stent placement guided under cardiovascular X-ray machine were included in the study. Radiation doses were measured using dose area product (DAP) meter for patients undergoing single and multiple stent placements during PTCA. A dose reduction of 27-47% was achieved using copper filters and optimal exposure parameters. The mean DAP values before optimization were 66.16 and 122.68 Gy cm 2 for single and multiple stent placement respectively. These values were 48.67 and 65.44 Gy cm 2 respectively after optimization. In the present scenario, due to the increase in the number of PTCAs performed and the associated risk from radiation, periodical audit of radiation doses for interventional procedures are recommended. (author)

Robust and optimal control a two-port framework approach

CERN Document Server

Tsai, Mi-Ching

2014-01-01

A Two-port Framework for Robust and Optimal Control introduces an alternative approach to robust and optimal controller synthesis procedures for linear, time-invariant systems, based on the two-port system widespread in electrical engineering. The novel use of the two-port system in this context allows straightforward engineering-oriented solution-finding procedures to be developed, requiring no mathematics beyond linear algebra. A chain-scattering description provides a unified framework for constructing the stabilizing controller set and for synthesizing H2 optimal and H∞ sub-optimal controllers. Simple yet illustrative examples explain each step. A Two-port Framework for Robust and Optimal Control  features: ·         a hands-on, tutorial-style presentation giving the reader the opportunity to repeat the designs presented and easily to modify them for their own programs; ·         an abundance of examples illustrating the most important steps in robust and optimal design; and ·   �...

Two-speed phacoemulsification for soft cataracts using optimized parameters and procedure step toolbar with the CENTURION Vision System and Balanced Tip.

Science.gov (United States)

Davison, James A

2015-01-01

To present a cause of posterior capsule aspiration and a technique using optimized parameters to prevent it from happening when operating soft cataracts. A prospective list of posterior capsule aspiration cases was kept over 4,062 consecutive cases operated with the Alcon CENTURION machine and Balanced Tip. Video analysis of one case of posterior capsule aspiration was accomplished. A surgical technique was developed using empirically derived machine parameters and customized setting-selection procedure step toolbar to reduce the pace of aspiration of soft nuclear quadrants in order to prevent capsule aspiration. Two cases out of 3,238 experienced posterior capsule aspiration before use of the soft quadrant technique. Video analysis showed an attractive vortex effect with capsule aspiration occurring in 1/5 of a second. A soft quadrant removal setting was empirically derived which had a slower pace and seemed more controlled with no capsule aspiration occurring in the subsequent 824 cases. The setting featured simultaneous linear control from zero to preset maximums for: aspiration flow, 20 mL/min; and vacuum, 400 mmHg, with the addition of torsional tip amplitude up to 20% after the fluidic maximums were achieved. A new setting selection procedure step toolbar was created to increase intraoperative flexibility by providing instantaneous shifting between the soft and normal settings. A technique incorporating a reduced pace for soft quadrant acquisition and aspiration can be accomplished through the use of a dedicated setting of integrated machine parameters. Toolbar placement of the procedure button next to the normal setting procedure button provides the opportunity to instantaneously alternate between the two settings. Simultaneous surgeon control over vacuum, aspiration flow, and torsional tip motion may make removal of soft nuclear quadrants more efficient and safer.

A Method for Correcting IMRT Optimizer Heterogeneity Dose Calculations

International Nuclear Information System (INIS)

Zacarias, Albert S.; Brown, Mellonie F.; Mills, Michael D.

2010-01-01

Radiation therapy treatment planning for volumes close to the patient's surface, in lung tissue and in the head and neck region, can be challenging for the planning system optimizer because of the complexity of the treatment and protected volumes, as well as striking heterogeneity corrections. Because it is often the goal of the planner to produce an isodose plan with uniform dose throughout the planning target volume (PTV), there is a need for improved planning optimization procedures for PTVs located in these anatomical regions. To illustrate such an improved procedure, we present a treatment planning case of a patient with a lung lesion located in the posterior right lung. The intensity-modulated radiation therapy (IMRT) plan generated using standard optimization procedures produced substantial dose nonuniformity across the tumor caused by the effect of lung tissue surrounding the tumor. We demonstrate a novel iterative method of dose correction performed on the initial IMRT plan to produce a more uniform dose distribution within the PTV. This optimization method corrected for the dose missing on the periphery of the PTV and reduced the maximum dose on the PTV to 106% from 120% on the representative IMRT plan.

Parameter Optimization for Feature and Hit Generation in a General Unknown Screening Method-Proof of Concept Study Using a Design of Experiment Approach for a High Resolution Mass Spectrometry Procedure after Data Independent Acquisition.

Science.gov (United States)

Elmiger, Marco P; Poetzsch, Michael; Steuer, Andrea E; Kraemer, Thomas

2018-03-06

High resolution mass spectrometry and modern data independent acquisition (DIA) methods enable the creation of general unknown screening (GUS) procedures. However, even when DIA is used, its potential is far from being exploited, because often, the untargeted acquisition is followed by a targeted search. Applying an actual GUS (including untargeted screening) produces an immense amount of data that must be dealt with. An optimization of the parameters regulating the feature detection and hit generation algorithms of the data processing software could significantly reduce the amount of unnecessary data and thereby the workload. Design of experiment (DoE) approaches allow a simultaneous optimization of multiple parameters. In a first step, parameters are evaluated (crucial or noncrucial). Second, crucial parameters are optimized. The aim in this study was to reduce the number of hits, without missing analytes. The obtained parameter settings from the optimization were compared to the standard settings by analyzing a test set of blood samples spiked with 22 relevant analytes as well as 62 authentic forensic cases. The optimization lead to a marked reduction of workload (12.3 to 1.1% and 3.8 to 1.1% hits for the test set and the authentic cases, respectively) while simultaneously increasing the identification rate (68.2 to 86.4% and 68.8 to 88.1%, respectively). This proof of concept study emphasizes the great potential of DoE approaches to master the data overload resulting from modern data independent acquisition methods used for general unknown screening procedures by optimizing software parameters.

Hierarchical models and iterative optimization of hybrid systems

Energy Technology Data Exchange (ETDEWEB)

Rasina, Irina V. [Ailamazyan Program Systems Institute, Russian Academy of Sciences, Peter One str. 4a, Pereslavl-Zalessky, 152021 (Russian Federation); Baturina, Olga V. [Trapeznikov Control Sciences Institute, Russian Academy of Sciences, Profsoyuznaya str. 65, 117997, Moscow (Russian Federation); Nasatueva, Soelma N. [Buryat State University, Smolina str.24a, Ulan-Ude, 670000 (Russian Federation)

2016-06-08

A class of hybrid control systems on the base of two-level discrete-continuous model is considered. The concept of this model was proposed and developed in preceding works as a concretization of the general multi-step system with related optimality conditions. A new iterative optimization procedure for such systems is developed on the base of localization of the global optimality conditions via contraction the control set.

Optimal procedures for home visits — A case study

Science.gov (United States)

Alves, Filipe; Fernandes, Florbela P.; Pereira, Ana I.; Fernandes, Adília

2017-07-01

In Portugal the population is ageing. Therefore, the provision of health care at patients' home is becoming an important social and health area; this health service is provided by professional teams (usually composed by nurses) of the Health Centers. Nowadays, the scheduling of the visits is made manually. The proposal of this work is to do the scheduling automatically in order to minimize the overall time spent by the professional teams in the visiting activity. In this work the genetic algorithm was used to solve the optimization problem. Some numerical results are presented.

Performance audit procedures for opacity monitors

International Nuclear Information System (INIS)

Plaisance, S.J.; Peeler, J.W.

1987-04-01

This manual contains monitor-specific performance audit procedures and data forms for use in conducting audits of installed opacity continuous emission monitoring systems (CEMS). General auditing procedures and acceptance limits for various audit criteria are discussed. Practical considerations and common problems encountered in conducting audits are delineated, and recommendations are included to optimize the successful completion of performance audits. Performance audit procedures and field-data forms were developed for six common opacity CEMS: (1) Lear Siegler, Inc. Model RM-41; (2) Lear Siegler, Inc. Model RM-4; (3) Dynatron Model 1100; (4) Thermo Electron, Inc. Model 400; (5) Thermo Electron, Inc. Model 1000A; and (6) Enviroplan Model D-R280 AV. Generic audit procedures are included for use in evaluating opacity CEMS with multiple transmissometers and combiner devices. In addition, several approaches for evaluating the zero-alignment or clear-path zero response are described. The zero-alignment procedures are included since the factor is fundamental to the accuracy of opacity monitoring data, even though the zero-alignment checks cannot usually be conducted during a performance audit

Ferroelectric materials for piezoelectric actuators by optimal design

International Nuclear Information System (INIS)

Jayachandran, K.P.; Guedes, J.M.; Rodrigues, H.C.

2011-01-01

Research highlights: → Microstructure optimization of ferroelectric materials by stochastic optimization. → Polycrystalline ferroelectrics possess better piezo actuation than single crystals. → Randomness of the grain orientations would enhance the overall piezoelectricity. - Abstract: Optimization methods provide a systematic means of designing heterogeneous materials with tailored properties and microstructures focussing on a specific objective. An optimization procedure incorporating a continuum modeling is used in this work to identify the ideal orientation distribution of ferroelectrics (FEs) for application in piezoelectric actuators. Piezoelectric actuation is dictated primarily by the piezoelectric strain coefficients d iμ . Crystallographic orientation is inextricably related to the piezoelectric properties of FEs. This suggests that piezoelectric properties can be tailored by a proper choice of the parameters which control the orientation distribution. Nevertheless, this choice is complicated and it is impossible to analyze all possible combinations of the distribution parameters or the angles themselves. Stochastic optimization combined with a generalized Monte Carlo scheme is used to optimize the objective functions, the effective piezoelectric coefficients d 31 and d 15 . The procedure is applied to heterogeneous, polycrystalline, FE ceramics which are essentially an aggregate of variously oriented grains (crystallites). Global piezoelectric properties are calculated using the homogenization method at each grain configuration chosen by the optimization algorithm. Optimal design variables and microstructure that would generate polycrystalline configurations that multiply the macroscopic piezoelectricity are identified.

Aerodynamic optimization of the blades of diffuser-augmented wind turbines

International Nuclear Information System (INIS)

Vaz, Jerson R.P.; Wood, David H.

2016-01-01

Highlights: • An optimization procedure to design shrouded wind turbine blades is proposed. • The procedure relies on the diffuser speed-up ratio. • The diffuser speed-up ratio increases the velocity at the rotor plane. • Chord and twist angle are optimized for typical speed-up ratios. • The procedure is applicable for any tip-speed ratio greater than 1. - Abstract: Adding an exit diffuser is known to allow wind turbines to exceed the classical Betz–Joukowsky limit for a bare turbine. It is not clear, however, if there is a limit for diffuser-augmented turbines or whether the structural and other costs of the diffuser outweigh any gain in power. This work presents a new approach to the aerodynamic optimization of a wind turbine with a diffuser. It is based on an extension of the well-known Blade Element Theory and a simple model for diffuser efficiency. It is assumed that the same conditions for the axial velocity in the wake of an ordinary wind turbine can be applied on the flow far downwind of the diffuser outlet. An algorithm to optimize the blade chord and twist angle distributions in the presence of a diffuser was developed and implemented. As a result, an aerodynamic improvement of the turbine rotor geometry was achieved with the blade shape sensitive to the diffuser speed-up ratio. In order to evaluate the proposed approach, a comparison with the classical Glauert optimization was performed for a flanged diffuser, which increased the efficiency. In addition, a comparative assessment was made with experimental results available in the literature, suggesting better performance for the rotor designed with the proposed optimization procedure.

Optimization of reconstruction algorithms using Monte Carlo simulation

International Nuclear Information System (INIS)

Hanson, K.M.

1989-01-01

A method for optimizing reconstruction algorithms is presented that is based on how well a specified task can be performed using the reconstructed images. Task performance is numerically assessed by a Monte Carlo simulation of the complete imaging process including the generation of scenes appropriate to the desired application, subsequent data taking, reconstruction, and performance of the stated task based on the final image. The use of this method is demonstrated through the optimization of the Algebraic Reconstruction Technique (ART), which reconstructs images from their projections by a iterative procedure. The optimization is accomplished by varying the relaxation factor employed in the updating procedure. In some of the imaging situations studied, it is found that the optimization of constrained ART, in which a nonnegativity constraint is invoked, can vastly increase the detectability of objects. There is little improvement attained for unconstrained ART. The general method presented may be applied to the problem of designing neutron-diffraction spectrometers. 11 refs., 6 figs., 2 tabs

Optimization of reconstruction algorithms using Monte Carlo simulation

International Nuclear Information System (INIS)

Hanson, K.M.

1989-01-01

A method for optimizing reconstruction algorithms is presented that is based on how well a specified task can be performed using the reconstructed images. Task performance is numerically assessed by a Monte Carlo simulation of the complete imaging process including the generation of scenes appropriate to the desired application, subsequent data taking, reconstruction, and performance of the stated task based on the final image. The use of this method is demonstrated through the optimization of the Algebraic Reconstruction Technique (ART), which reconstructs images from their projections by an iterative procedure. The optimization is accomplished by varying the relaxation factor employed in the updating procedure. In some of the imaging situations studied, it is found that the optimization of constrained ART, in which a non-negativity constraint is invoked, can vastly increase the detectability of objects. There is little improvement attained for unconstrained ART. The general method presented may be applied to the problem of designing neutron-diffraction spectrometers. (author)

Learning optimal embedded cascades.

Science.gov (United States)

Saberian, Mohammad Javad; Vasconcelos, Nuno

2012-10-01

The problem of automatic and optimal design of embedded object detector cascades is considered. Two main challenges are identified: optimization of the cascade configuration and optimization of individual cascade stages, so as to achieve the best tradeoff between classification accuracy and speed, under a detection rate constraint. Two novel boosting algorithms are proposed to address these problems. The first, RCBoost, formulates boosting as a constrained optimization problem which is solved with a barrier penalty method. The constraint is the target detection rate, which is met at all iterations of the boosting process. This enables the design of embedded cascades of known configuration without extensive cross validation or heuristics. The second, ECBoost, searches over cascade configurations to achieve the optimal tradeoff between classification risk and speed. The two algorithms are combined into an overall boosting procedure, RCECBoost, which optimizes both the cascade configuration and its stages under a detection rate constraint, in a fully automated manner. Extensive experiments in face, car, pedestrian, and panda detection show that the resulting detectors achieve an accuracy versus speed tradeoff superior to those of previous methods.

Numerical optimization of circulation control airfoils

Science.gov (United States)

Tai, T. C.; Kidwell, G. H., Jr.; Vanderplaats, G. N.

1981-01-01

A numerical procedure for optimizing circulation control airfoils, which consists of the coupling of an optimization scheme with a viscous potential flow analysis for blowing jet, is presented. The desired airfoil is defined by a combination of three baseline shapes (cambered ellipse, and cambered ellipse with drooped and spiralled trailing edges). The coefficients of these shapes are used as design variables in the optimization process. Under the constraints of lift augmentation and lift-to-drag ratios, the optimal airfoils are found to lie between those of cambered ellipse and the drooped trailing edge, towards the latter as the angle of attack increases. Results agree qualitatively with available experimental data.

Optimization of synthesis and quality control procedures for the preparation of 18F-labelled peptides

International Nuclear Information System (INIS)

Amartey, J.K.

2002-01-01

human cancer cell line in a dose dependent manner as expected. The biodistribution showed that the [ 18 F]-RC-160 bound to tumour xenograft in nude mice. The main objective of the project was to optimize reaction conditions and quality control procedures for prosthetic labelling of peptides. Hence the aims of the project were to: improve fluorination of prosthetic group such as fluorobenzoate, synthesis and isolation of the succinimidyl activated ester of the prosthetic group and reaction conditions to couple the activated ester to a model chemotactic peptide, and to develop an isolation method for the peptide conjugate; perform in vitro and in vivo experiments to ascertain the biological activity of the conjugate; apply the methods and techniques developed to label another biologically active peptide and evaluate its potential application as a cancer detection agent. (author)

Conjugate gradient optimization programs for shuttle reentry

Science.gov (United States)

Powers, W. F.; Jacobson, R. A.; Leonard, D. A.

1972-01-01

Two computer programs for shuttle reentry trajectory optimization are listed and described. Both programs use the conjugate gradient method as the optimization procedure. The Phase 1 Program is developed in cartesian coordinates for a rotating spherical earth, and crossrange, downrange, maximum deceleration, total heating, and terminal speed, altitude, and flight path angle are included in the performance index. The programs make extensive use of subroutines so that they may be easily adapted to other atmospheric trajectory optimization problems.

Optimization theory for large systems

CERN Document Server

Lasdon, Leon S

2002-01-01

Important text examines most significant algorithms for optimizing large systems and clarifying relations between optimization procedures. Much data appear as charts and graphs and will be highly valuable to readers in selecting a method and estimating computer time and cost in problem-solving. Initial chapter on linear and nonlinear programming presents all necessary background for subjects covered in rest of book. Second chapter illustrates how large-scale mathematical programs arise from real-world problems. Appendixes. List of Symbols.

Aerodynamic Optimization of Airfoil Profiles for Small Horizontal Axis Wind Turbines

Directory of Open Access Journals (Sweden)

Ali Cemal Benim

2018-04-01

Full Text Available The purpose of this study is the development of an automated two-dimensional airfoil shape optimization procedure for small horizontal axis wind turbines (HAWT, with an emphasis on high thrust and aerodynamically stable performance. The procedure combines the Computational Fluid Dynamics (CFD analysis with the Response Surface Methodology (RSM, the Biobjective Mesh Adaptive Direct Search (BiMADS optimization algorithm and an automatic geometry and mesh generation tool. In CFD analysis, a Reynolds Averaged Numerical Simulation (RANS is applied in combination with a two-equation turbulence model. For describing the system behaviour under alternating wind conditions, a number of CFD 2D-RANS-Simulations with varying Reynolds numbers and wind angles are performed. The number of cases is reduced by the use of RSM. In the analysis, an emphasis is placed upon the role of the blade-to-blade interaction. The average and the standard deviation of the thrust are optimized by a derivative-free optimization algorithm to define a Pareto optimal set, using the BiMADS algorithm. The results show that improvements in the performance can be achieved by modifications of the blade shape and the present procedure can be used as an effective tool for blade shape optimization.

DETERMINATION OF BRAKING OPTIMAL MODE OF CONTROLLED CUT OF DESIGN GROUP

Directory of Open Access Journals (Sweden)

A. S. Dorosh

2015-06-01

Full Text Available Purpose. The application of automation systems of breaking up process on the gravity hump is the efficiency improvement of their operation, absolute provision of trains breaking up safety demands, as well as improvement of hump staff working conditions. One of the main tasks of the indicated systems is the assurance of cuts reliable separation at all elements of their rolling route to the classification track. This task is a sophisticated optimization problem and has not received a final decision. Therefore, the task of determining the cuts braking mode is quite relevant. The purpose of this research is to find the optimal braking mode of control cut of design group. Methodology. In order to achieve the purpose is offered to use the direct search methods in the work, namely the Box complex method. This method does not require smoothness of the objective function, takes into account its limitations and does not require calculation of the function derivatives, and uses only its value. Findings. Using the Box method was developed iterative procedure for determining the control cut optimal braking mode of design group. The procedure maximizes the smallest controlled time interval in the group. To evaluate the effectiveness of designed procedure the series of simulation experiments of determining the control cut braking mode of design group was performed. The results confirmed the efficiency of the developed optimization procedure. Originality. The author formalized the task of optimizing control cut braking mode of design group, taking into account the cuts separation of design group at all elements (switches, retarders during cuts rolling to the classification track. The problem of determining the optimal control cut braking mode of design group was solved. The developed braking mode ensures cuts reliable separation of the group not only at the switches but at the retarders of brake position. Practical value. The developed procedure can be

Simplified proceeding as a civil procedure model

Directory of Open Access Journals (Sweden)

Олексій Юрійович Зуб

2016-01-01

Full Text Available Currently the directions for the development of modern civil procedural law such as optimization, facilitation, forwarding proceedings promoting the increase of the civil procedure efficiency factor are of peculiar importance. Their results are occurrence and functionality of simplified proceedings system designed to facilitate significantly hearing some categories of cases, promotion of their consideration within reasonable time and reduce legal expenses so far as it is possible. The category “simplified proceedings” in the native science of the procedural law is underexamined. A good deal of scientists-processualists were limited to studying summary (in the context of optimization as a way to improve the civil procedural form, summary proceedings and procedures functioning in terms of the mentioned proceedings, consideration of case in absentia as well as their modification. Among the Ukrainian scientist who studied some aspects of the simplified proceedings are: E. A. Belyanevych, V. I. Bobrik, S. V. Vasilyev, M. V. Verbitska, S. I. Zapara, A. A. Zgama, V. V. Komarov, D. D. Luspenuk, U. V. Navrotska, V. V. Protsenko, T. V. Stepanova, E. A. Talukin, S. Y. Fursa, M. Y. Shtefan others. The problems of the simplified proceedings were studied by the foreign scientists as well, such as: N. Andrews, Y. Y. Grubanon, N. A. Gromoshina, E. P. Kochanenko, J. Kohler, D. I. Krumskiy, E. M. Muradjan, I. V. Reshetnikova, U. Seidel, N. V. Sivak, M. Z. Shvarts, V. V. Yarkov and others. The paper objective is to develop theoretically supported, practically reasonable notion of simplified proceedings in the civil process, and also basing on the notion of simplified proceedings, international experience of the legislative regulation of simplified proceedings, native and foreign doctrine, to distinguish essential features of simplified proceedings in the civil process and to describe them. In the paper we generated the notion of simplified proceedings that

Optimization of patient protection using rare earth screen in conventional imaging procedure

International Nuclear Information System (INIS)

Inkoom, S.; Schandorf, C.; Fletcher, J.J.

2008-01-01

The purpose of this study was to optimize patient protection using rare earth screen of speed 400 in place of conventional screen-film of speed 200. The entrance surface dose (ESD) for the two screen-film systems was determined for patients undergoing simple radiographic examinations (chest, lumbar spine and pelvis series). The determination of the ESD included backscatter factors. The ESD was the optimizing parameter and its trade off with the image quality assessment, which was surveyed based on the information obtained through standardized questionnaire. The estimated ESDs were compared with reference levels set by the Community of European Commission (CEC) for a standard adult patient. For chest PA, ESD estimates were lower than the CEC reference levels whilst that of lumbar spine AP and LAT and pelvis AP were high. Upon the adoption of rare earth screen of speed 400, a dose reduction of 33% for chest, 17% for lumbar spine and 28% for pelvis examinations was achieved. From the observations made from this study, some corrective actions such as equipment quality control of parameters that affect patient dose and image quality like kVp accuracy and consistency, mAs accuracy and consistency, optimal film processing conditions, regular film reject analysis to detect and minimize the root causes and contributory factors to poor image quality and periodic training of staff on dose reduction techniques must be undertaken. Regular assessment of patient dose and image quality, equipment quality control, adoption of faster rare earth screens and optimum radiographic technique are therefore recommended in order to achieve optimization goals. (author)

Decision theoretical justification of optimization criteria for near-real-time accountancy procedures

International Nuclear Information System (INIS)

Avenhaus, R.

1992-01-01

In the beginning of nuclear material safeguards, emphasis was placed on safe detection of diversion of nuclear material. Later, the aspect of timely detection became equally important. Since there is a trade-off between these two objectives, the question of an appropriate compromise was raised. In this paper, a decision theoretical framework is presented in which the objectives of the two players, inspector and inspectee, are expressed in terms of general utility functions. Within this framework, optimal safeguards strategies are defined, and furthermore, conditions are formulated under which the optimization criteria corresponding to the objectives mentioned above can be justified

Guide for External Beam Radiotherapy. Procedures 2007

International Nuclear Information System (INIS)

Ardiet, Jean-Michel; Bourhis, Jean; Eschwege, Francois; Gerard, Jean-Pierre; Martin, Philippe; Mazeron, Jean-Jacques; Barillot, Isabelle; Bey, Pierre; Cosset, Jean-Marc; Thomas, Olivier; Bolla, Michel; Bourguignon, Michel; Godet, Jean-Luc; Krembel, David; Valero, Marc; Bara, Christine; Beauvais-March, Helene; Derreumaux, Sylvie; Vidal, Jean-Pierre; Drouard, Jean; Sarrazin, Thierry; Lindecker-Cournil, Valerie; Robin, Sun Hee Lee; Thevenet, Nicolas; Depenweiller, Christian; Le Tallec, Philippe; Ortholan, Cecile; Aimone, Nicole; Baldeschi, Carine; Cantelli, Andree; Estivalet, Stephane; Le Prince, Cyrille; QUERO, Laurent; Costa, Andre; Gerard, Jean-Pierre; Ardiet, Jean-Michel; Bensadoun, Rene-Jean; Bourhis, Jean; Calais, Gilles; Lartigau, Eric; Ginot, Aurelie; Girard, Nicolas; Mornex, Francoise; Bolla, Michel; Chauvet, Bruno; Maingon, Philippe; Martin, Etienne; Azria, David; Gerard, Jean-Pierre; Grehange, Gilles; Hennequin, Christophe; Peiffert, Didier; Toledano, Alain; Belkacemi, Yazid; Courdi, Adel; Belliere, Aurelie; Peignaux, Karine; Mahe, Marc; Bondiau, Pierre-Yves; Kantor, Guy; Lepechoux, Cecile; Carrie, Christian; Claude, Line

2007-01-01

In order to optimize quality and security in the delivery of radiation treatment, the French SFRO (Societe francaise de radiotherapie oncologique) is publishing a Guide for Radiotherapy. This guide is realized according to the HAS (Haute Autorite de sante) methodology of 'structured experts consensus'. This document is made of two parts: a general description of external beam radiation therapy and chapters describing the technical procedures of the main tumors to be irradiated (24). For each procedure, a special attention is given to dose constraints in the organs at risk. This guide will be regularly updated

Reliability-Based Optimization of Series Systems of Parallel Systems

DEFF Research Database (Denmark)

Enevoldsen, I.; Sørensen, John Dalsgaard

Reliability-based design of structural systems is considered. Especially systems where the reliability model is a series system of parallel systems are analysed. A sensitivity analysis for this class of problems is presented. Direct and sequential optimization procedures to solve the optimization...

Optimal depth-based regional frequency analysis

Science.gov (United States)

Wazneh, H.; Chebana, F.; Ouarda, T. B. M. J.

2013-06-01

Classical methods of regional frequency analysis (RFA) of hydrological variables face two drawbacks: (1) the restriction to a particular region which can lead to a loss of some information and (2) the definition of a region that generates a border effect. To reduce the impact of these drawbacks on regional modeling performance, an iterative method was proposed recently, based on the statistical notion of the depth function and a weight function φ. This depth-based RFA (DBRFA) approach was shown to be superior to traditional approaches in terms of flexibility, generality and performance. The main difficulty of the DBRFA approach is the optimal choice of the weight function ϕ (e.g., φ minimizing estimation errors). In order to avoid a subjective choice and naïve selection procedures of φ, the aim of the present paper is to propose an algorithm-based procedure to optimize the DBRFA and automate the choice of ϕ according to objective performance criteria. This procedure is applied to estimate flood quantiles in three different regions in North America. One of the findings from the application is that the optimal weight function depends on the considered region and can also quantify the region's homogeneity. By comparing the DBRFA to the canonical correlation analysis (CCA) method, results show that the DBRFA approach leads to better performances both in terms of relative bias and mean square error.

3D printing for construction: a procedural and material-based approach

Directory of Open Access Journals (Sweden)

A. Nadal

2017-06-01

Full Text Available 3D printing for construction is stagnated at an early stage of development, especially regarding material optimization and procedural issues. These limitations are due to the specific knowledge that these technologies imply, the total cost of the machinery involved, and the lack of clear procedural guidelines. This paper presents a methodology that aims at overcoming these limitations through a workflow that allows for the ease of use of 6-axis robotic arms. A technique for the optimization of material usage is presented. A test case that shows the integration the design-to-fabrication process combining Integrated Robotic Systems (IRS and Additive Layer Manufacturing (ALM techniques is discussed. A structure-based approach to material optimization and smart infill patterning is introduced. A 0.4 x 0.4 x 1.5 m test part is shown as technological demonstrator.

Optimization of Laminated Composite Structures

DEFF Research Database (Denmark)

Henrichsen, Søren Randrup

of the contributions of the PhD project are included in the second part of the thesis. Paper A presents a framework for free material optimization where commercially available finite element analysis software is used as analysis tool. Robust buckling optimization of laminated composite structures by including...... allows for a higher degree of tailoring of the resulting material. To enable better utilization of the composite materials, optimum design procedures can be used to assist the engineer. This PhD thesis is focused on developing numerical methods for optimization of laminated composite structures...... nonlinear analysis of structures, buckling and post-buckling analysis of structures, and formulations for optimization of structures considering stiffness, buckling, and post-buckling criteria. Lastly, descriptions, main findings, and conclusions of the papers are presented. The papers forming the basis...

Application of Six Sigma Robust Optimization in Sheet Metal Forming

International Nuclear Information System (INIS)

Li, Y.Q.; Cui, Z.S.; Ruan, X.Y.; Zhang, D.J.

2005-01-01

Numerical simulation technology and optimization method have been applied in sheet metal forming process to improve design quality and shorten design cycle. While the existence of fluctuation in design variables or operation condition has great influence on the quality. In addition to that, iterative solution in numerical simulation and optimization usually take huge computational time or endure expensive experiment cost In order to eliminate effect of perturbations in design and improve design efficiency, a CAE-based six sigma robust design method is developed in this paper. In the six sigma procedure for sheet metal forming, statistical technology and dual response surface approximate model as well as algorithm of 'Design for Six Sigma (DFSS)' are integrated together to perform reliability optimization and robust improvement. A deep drawing process of a rectangular cup is taken as an example to illustrate the method. The optimization solutions show that the proposed optimization procedure not only improves significantly the reliability and robustness of the forming quality, but also increases optimization efficiency with approximate model

Optimal design of a magneto-rheological brake absorber for torsional vibration control

International Nuclear Information System (INIS)

Nguyen, Q H; Choi, S B

2012-01-01

This research presents an optimal design of a magneto-rheological (MR) brake absorber for torsional vibration control of a rotating shaft. Firstly, the configuration of an MR brake absorber for torsional vibration control of a rotating shaft system is proposed. Then, the braking torque of the MR brake is derived based on the Bingham plastic model of the MR fluid. By assuming that the behaviour of the MR brake absorber is similar to that of a dry friction torsional damper, the optimal braking torque to control the torsional vibration is determined and validated by simulation. The optimal design problem of the MR brake absorber is then developed and a procedure to solve the optimal problem is proposed. Based on the proposed optimal design procedure, the optimal design of a specific rotating shaft system is performed. Vibration control performance of the shaft system employing the optimized MR brake absorber is then investigated through simulation and discussion on the results is given. (paper)

Optimal design of a magneto-rheological brake absorber for torsional vibration control

Science.gov (United States)

Nguyen, Q. H.; Choi, S. B.

2012-02-01

This research presents an optimal design of a magneto-rheological (MR) brake absorber for torsional vibration control of a rotating shaft. Firstly, the configuration of an MR brake absorber for torsional vibration control of a rotating shaft system is proposed. Then, the braking torque of the MR brake is derived based on the Bingham plastic model of the MR fluid. By assuming that the behaviour of the MR brake absorber is similar to that of a dry friction torsional damper, the optimal braking torque to control the torsional vibration is determined and validated by simulation. The optimal design problem of the MR brake absorber is then developed and a procedure to solve the optimal problem is proposed. Based on the proposed optimal design procedure, the optimal design of a specific rotating shaft system is performed. Vibration control performance of the shaft system employing the optimized MR brake absorber is then investigated through simulation and discussion on the results is given.

Method of optimization onboard communication network

Science.gov (United States)

Platoshin, G. A.; Selvesuk, N. I.; Semenov, M. E.; Novikov, V. M.

2018-02-01

In this article the optimization levels of onboard communication network (OCN) are proposed. We defined the basic parameters, which are necessary for the evaluation and comparison of modern OCN, we identified also a set of initial data for possible modeling of the OCN. We also proposed a mathematical technique for implementing the OCN optimization procedure. This technique is based on the principles and ideas of binary programming. It is shown that the binary programming technique allows to obtain an inherently optimal solution for the avionics tasks. An example of the proposed approach implementation to the problem of devices assignment in OCN is considered.

Gas chromatographic-mass spectrometric analysis of urinary volatile organic metabolites: Optimization of the HS-SPME procedure and sample storage conditions.

Science.gov (United States)

Živković Semren, Tanja; Brčić Karačonji, Irena; Safner, Toni; Brajenović, Nataša; Tariba Lovaković, Blanka; Pizent, Alica

2018-01-01

Non-targeted metabolomics research of human volatile urinary metabolome can be used to identify potential biomarkers associated with the changes in metabolism related to various health disorders. To ensure reliable analysis of urinary volatile organic metabolites (VOMs) by gas chromatography-mass spectrometry (GC-MS), parameters affecting the headspace-solid phase microextraction (HS-SPME) procedure have been evaluated and optimized. The influence of incubation and extraction temperatures and times, coating fibre material and salt addition on SPME efficiency was investigated by multivariate optimization methods using reduced factorial and Doehlert matrix designs. The results showed optimum values for temperature to be 60°C, extraction time 50min, and incubation time 35min. The proposed conditions were applied to investigate urine samples' stability regarding different storage conditions and freeze-thaw processes. The sum of peak areas of urine samples stored at 4°C, -20°C, and -80°C up to six months showed a time dependent decrease over time although storage at -80°C resulted in a slight non-significant reduction comparing to the fresh sample. However, due to the volatile nature of the analysed compounds, more than two cycles of freezing/thawing of the sample stored for six months at -80°C should be avoided whenever possible. Copyright © 2017 Elsevier B.V. All rights reserved.

Sizing optimization of skeletal structures using teaching-learning based optimization

Directory of Open Access Journals (Sweden)

Vedat Toğan

2017-03-01

Full Text Available Teaching Learning Based Optimization (TLBO is one of the non-traditional techniques to simulate natural phenomena into a numerical algorithm. TLBO mimics teaching learning process occurring between a teacher and students in a classroom. A parameter named as teaching factor, TF, seems to be the only tuning parameter in TLBO. Although the value of the teaching factor, TF, is determined by an equation, the value of 1 or 2 has been used by the researchers for TF. This study intends to explore the effect of the variation of teaching factor TF on the performances of TLBO. This effect is demonstrated in solving structural optimization problems including truss and frame structures under the stress and displacement constraints. The results indicate that the variation of TF in the TLBO process does not change the results obtained at the end of the optimization procedure when the computational cost of TLBO is ignored.

Optimization of Organic Rankine Cycles for Off-Shore Applications

DEFF Research Database (Denmark)

Pierobon, Leonardo; Larsen, Ulrik; Nguyen, Tuong-Van

2013-01-01

and the thermal efficiency of the cycle can be maximized. This paper is aimed at finding the most optimal ORC tailored for off-shore applications using an optimization procedure based on the genetic algorithm. Numerous working fluids are screened through, considering mainly thermal efficiency, but also other...

Optimization of synthesis and quality control procedures for the preparation of 18F and 123I labelled peptides for nuclear medicine

International Nuclear Information System (INIS)

2002-09-01

The general scope of this CRP focused on the optimization of syntheses, quality control, in vitro and in vivo evaluation of 18 F and 123 I radiopharmaceuticals based on peptides with known or anticipated clinical potential. Selective labelling procedures using prosthetic groups were applied to both fluorine and iodine. Studies included investigation on the fate of the label, stability in vivo, biodistribution and pharmacokinetic studies in rodents and in cell culture. With respect to 123 I, the work aimed at developing a simplified labelling kit using solid state systems. The first Research Co-ordination Meeting (RCM) that was held in August 1997 took up and decided on the criteria for selecting the peptides and agreed upon a set of recommended laboratory protocols for the CRP participants to follow and further optimize. Eight scientists from reputed laboratories from Argentina, Brazil, China, Germany, Greece, the Islamic Republic of Iran, Saudi Arabia and the United States of America participated in the CRP. Three RCMs were held where the participants presented their scientific results: August 1997 in Sao Paulo, Brazil, April 1999 in Athens, Greece, and November 2000 in Shanghai, People's Republic of China. Reports describing the research work of all participants are included herein. Each of the report has been indexed separately

Investigations into the Optimization of Multi-Source Strength Brachytherapy Treatment Procedures

CERN Document Server

Henderson, D L; Yoo, S

2002-01-01

The goal of this project is to investigate the use of multi-strength and multi-specie radioactive sources in permanent prostate implant brachytherapy. In order to fulfill the requirement for an optimal dose distribution, the prescribed dose should be delivered to the target in a nearly uniform dose distribution while simultaneously sparing sensitive structures. The treatment plan should use a small number of needles and sources while satisfying the treatment requirements. The hypothesis for the use of multi-strength and/or multi-specie sources is that a better treatment plan using fewer sources and needles could be obtained than by treatment plans using single-strength sources could reduce the overall number of sources used for treatment. We employ a recently developed greedy algorithm based on the adjoint concept as the optimization search engine. The algorithm utilizes and ''adjoint ratio'', which provides a means of ranking source positions, as the pseudo-objective function. It ha s been shown that the gre...

Investigation on a procedure for optimal axial depth of cut accuracy in micromilling

DEFF Research Database (Denmark)

Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

2005-01-01

On the basis of a previously developed procedure for control of axial depth of cut in high accuracy micromilling operations, this paper presents an investigation on the estimation of the uncertainty of the set axial depth of cut.......On the basis of a previously developed procedure for control of axial depth of cut in high accuracy micromilling operations, this paper presents an investigation on the estimation of the uncertainty of the set axial depth of cut....

Autogenous bone grafts in the esthetic zone: optimizing the procedure using piezosurgery.

Science.gov (United States)

Majewski, Piotr

2012-12-01

Soft and hard tissue defects pose a therapeutic challenge in modern implant dentistry. There are a multitude of surgical techniques available, and it is necessary to match the problem with the solution. This report describes the reconstruction of the alveolar ridge in the esthetic zone with the help of autogenous bone blocks harvested from the chin that were shaped to fit and stabilized at the recipient site. The procedures were performed using Piezosurgery, which made it possible to introduce surgical modifications and had a significant impact on the accuracy of the procedure. An observation period of 2 to 7 years showed positive stable results for treatment in terms of function and esthetics.

Design optimization of jacket structures for mass production

DEFF Research Database (Denmark)

Sandal, Kasper

This thesis presents models and applications for structural optimization of jacket structures for offshore wind turbines. The motivation is that automatic design procedures can be used to obtain more cost efficient designs, and thus reduce the levelized cost of energy from offshore wind. A struct......This thesis presents models and applications for structural optimization of jacket structures for offshore wind turbines. The motivation is that automatic design procedures can be used to obtain more cost efficient designs, and thus reduce the levelized cost of energy from offshore wind....... A structural finite element model is developed specifically for the analysis and optimization of jacket structures. The model uses Timoshenko beam elements, and assumes thin walled tubular beams and a linear elastic structural response. The finite element model is implemented in a Matlab package called JADOP...... (Jacket Design Optimization), and the static and dynamic structural response is verified with the commercial finite element software Abaqus. A parametric mesh of the offshore wind turbine structure makes it relatively easy to represent various structures from the literature, as well as exploring...

Determination of optimal geometry for cylindrical sources for gamma radiation measurements; Odredjivanje optimalne geometrije za mjerenje gama zracenja cilindrichnih izvora

Energy Technology Data Exchange (ETDEWEB)

Sinjeri, Lj; Kulisic, P [Elektra - Zagreb, Zagreb (Yugoslavia)

1990-07-01

Low radioactive sources were used for experimental determination of optimal dimensions for cylindrical source using coaxial Ge(Li) detector. Then, calculational procedure is used to find optimal dimensions of cylindrical source. The results from calculational procedure confirm with experimental results. In such way the verification of calculational procedure is done and it can be used for determination of optimal geometry for low radioactive cylindrical sources. (author)

On optimal quadrature formulae

Directory of Open Access Journals (Sweden)

Lanzara Flavia

2000-01-01

Full Text Available A procedure to construct quadrature formulae which are exact for solutions of linear differential equations and are optimal in the sense of Sard is discussed. We give necessary and sufficient conditions under which such formulae do exist. Several formulae obtained by applying this method are considered and compared with well known formulae.

Optimizing Chromatographic Separation: An Experiment Using an HPLC Simulator

Science.gov (United States)

Shalliker, R. A.; Kayillo, S.; Dennis, G. R.

2008-01-01

Optimization of a chromatographic separation within the time constraints of a laboratory session is practically impossible. However, by employing a HPLC simulator, experiments can be designed that allow students to develop an appreciation of the complexities involved in optimization procedures. In the present exercise, a HPLC simulator from "JCE…

Sensor Calibration Design Based on D-Optimality Criterion

Directory of Open Access Journals (Sweden)

Hajiyev Chingiz

2016-09-01

Full Text Available In this study, a procedure for optimal selection of measurement points using the D-optimality criterion to find the best calibration curves of measurement sensors is proposed. The coefficients of calibration curve are evaluated by applying the classical Least Squares Method (LSM. As an example, the problem of optimal selection for standard pressure setters when calibrating a differential pressure sensor is solved. The values obtained from the D-optimum measurement points for calibration of the differential pressure sensor are compared with those from actual experiments. Comparison of the calibration errors corresponding to the D-optimal, A-optimal and Equidistant calibration curves is done.

Two-speed phacoemulsification for soft cataracts using optimized parameters and procedure step toolbar with the CENTURION Vision System and Balanced Tip

Directory of Open Access Journals (Sweden)

Davison JA

2015-08-01

Full Text Available James A DavisonWolfe Eye Clinic, Marshalltown, IA, USA Purpose: To present a cause of posterior capsule aspiration and a technique using optimized parameters to prevent it from happening when operating soft cataracts.Patients and methods: A prospective list of posterior capsule aspiration cases was kept over 4,062 consecutive cases operated with the Alcon CENTURION machine and Balanced Tip. Video analysis of one case of posterior capsule aspiration was accomplished. A surgical technique was developed using empirically derived machine parameters and customized setting-selection procedure step toolbar to reduce the pace of aspiration of soft nuclear quadrants in order to prevent capsule aspiration.Results: Two cases out of 3,238 experienced posterior capsule aspiration before use of the soft quadrant technique. Video analysis showed an attractive vortex effect with capsule aspiration occurring in 1/5 of a second. A soft quadrant removal setting was empirically derived which had a slower pace and seemed more controlled with no capsule aspiration occurring in the subsequent 824 cases. The setting featured simultaneous linear control from zero to preset maximums for: aspiration flow, 20 mL/min; and vacuum, 400 mmHg, with the addition of torsional tip amplitude up to 20% after the fluidic maximums were achieved. A new setting selection procedure step toolbar was created to increase intraoperative flexibility by providing instantaneous shifting between the soft and normal settings.Conclusion: A technique incorporating a reduced pace for soft quadrant acquisition and aspiration can be accomplished through the use of a dedicated setting of integrated machine parameters. Toolbar placement of the procedure button next to the normal setting procedure button provides the opportunity to instantaneously alternate between the two settings. Simultaneous surgeon control over vacuum, aspiration flow, and torsional tip motion may make removal of soft nuclear

Generalized massive optimal data compression

Science.gov (United States)

Alsing, Justin; Wandelt, Benjamin

2018-05-01

In this paper, we provide a general procedure for optimally compressing N data down to n summary statistics, where n is equal to the number of parameters of interest. We show that compression to the score function - the gradient of the log-likelihood with respect to the parameters - yields n compressed statistics that are optimal in the sense that they preserve the Fisher information content of the data. Our method generalizes earlier work on linear Karhunen-Loéve compression for Gaussian data whilst recovering both lossless linear compression and quadratic estimation as special cases when they are optimal. We give a unified treatment that also includes the general non-Gaussian case as long as mild regularity conditions are satisfied, producing optimal non-linear summary statistics when appropriate. As a worked example, we derive explicitly the n optimal compressed statistics for Gaussian data in the general case where both the mean and covariance depend on the parameters.

Optimizing cost-efficiency in mean exposure assessment--cost functions reconsidered.

Science.gov (United States)

Mathiassen, Svend Erik; Bolin, Kristian

2011-05-21

Reliable exposure data is a vital concern in medical epidemiology and intervention studies. The present study addresses the needs of the medical researcher to spend monetary resources devoted to exposure assessment with an optimal cost-efficiency, i.e. obtain the best possible statistical performance at a specified budget. A few previous studies have suggested mathematical optimization procedures based on very simple cost models; this study extends the methodology to cover even non-linear cost scenarios. Statistical performance, i.e. efficiency, was assessed in terms of the precision of an exposure mean value, as determined in a hierarchical, nested measurement model with three stages. Total costs were assessed using a corresponding three-stage cost model, allowing costs at each stage to vary non-linearly with the number of measurements according to a power function. Using these models, procedures for identifying the optimally cost-efficient allocation of measurements under a constrained budget were developed, and applied on 225 scenarios combining different sizes of unit costs, cost function exponents, and exposure variance components. Explicit mathematical rules for identifying optimal allocation could be developed when cost functions were linear, while non-linear cost functions implied that parts of or the entire optimization procedure had to be carried out using numerical methods.For many of the 225 scenarios, the optimal strategy consisted in measuring on only one occasion from each of as many subjects as allowed by the budget. Significant deviations from this principle occurred if costs for recruiting subjects were large compared to costs for setting up measurement occasions, and, at the same time, the between-subjects to within-subject variance ratio was small. In these cases, non-linearities had a profound influence on the optimal allocation and on the eventual size of the exposure data set. The analysis procedures developed in the present study can be used

Optimal depth-based regional frequency analysis

Directory of Open Access Journals (Sweden)

H. Wazneh

2013-06-01

Full Text Available Classical methods of regional frequency analysis (RFA of hydrological variables face two drawbacks: (1 the restriction to a particular region which can lead to a loss of some information and (2 the definition of a region that generates a border effect. To reduce the impact of these drawbacks on regional modeling performance, an iterative method was proposed recently, based on the statistical notion of the depth function and a weight function φ. This depth-based RFA (DBRFA approach was shown to be superior to traditional approaches in terms of flexibility, generality and performance. The main difficulty of the DBRFA approach is the optimal choice of the weight function ϕ (e.g., φ minimizing estimation errors. In order to avoid a subjective choice and naïve selection procedures of φ, the aim of the present paper is to propose an algorithm-based procedure to optimize the DBRFA and automate the choice of ϕ according to objective performance criteria. This procedure is applied to estimate flood quantiles in three different regions in North America. One of the findings from the application is that the optimal weight function depends on the considered region and can also quantify the region's homogeneity. By comparing the DBRFA to the canonical correlation analysis (CCA method, results show that the DBRFA approach leads to better performances both in terms of relative bias and mean square error.

Sequential optimization of a polygeneration plant

International Nuclear Information System (INIS)

Rubio-Maya, Carlos; Uche, Javier; Martinez, Amaya

2011-01-01

Highlights: → A two-steps optimization procedure of a polygeneration unit was tested. → First step was the synthesis and design; the superstructure definition was used. → Second step optimized the operation with hourly data and energy storage systems. → Remarkable benefits for the analyzed case study (Spanish hotel) were found. - Abstract: This paper presents a two-steps optimization procedure of a polygeneration unit. The unit simultaneously provides power, heat, cooling and fresh water to a Spanish tourist resort (450 rooms). The first step consist on the synthesis and design of the polygeneration scheme: a 'superstructure' was constructed to allow the selection of the appropriate choice and size of the plant components, from both economic and environmental considerations. At that first step, only monthly averaged requirements are considered. The second step includes hourly data and analysis as well as energy storage systems. A detailed modelling of pre-selected devices is then required to also fulfil economic and environmental constraints. As a result, a better performance is obtained compared to the first step. Thus, the two-steps procedure explained here permits the complete design and operation of a decentralized plant producing simultaneously energy (power, heat and cooling) but also desalted water (that is, trigeneration + desalination). Remarkable benefits for the analyzed case study are found: a Net Present Value of almost 300,000 Euro , a primary energy saving ratio of about 18% and more than 850 ton per year of avoided CO 2 emissions.

Concrete Plant Operations Optimization Using Combined Simulation and Genetic Algorithms

NARCIS (Netherlands)

Cao, Ming; Lu, Ming; Zhang, Jian-Ping

2004-01-01

This work presents a new approach for concrete plant operations optimization by combining a ready mixed concrete (RMC) production simulation tool (called HKCONSIM) with a genetic algorithm (GA) based optimization procedure. A revamped HKCONSIM computer system can be used to automate the simulation

Daily dose and shielding optimization in work performance at 'Ukrytie' object

International Nuclear Information System (INIS)

Batij, V.G.; Derengovskij, V.V.; Egorov, V.V.; Kuz'menko, V.A.; Rud'ko, V.M.; Sizov, A.A.; Stoyanov, A.I.

2000-01-01

The procedure of daily dose and shielding optimization in work performance at 'Ukryttia' object is offered. The recommendations allowing reducing collective effective doze according to the optimization principle are submitted. The technique of shielding optimization is given at stabilization works realization. The optimum shielding calculation example for the strengthening support is given

Optimal sensor configuration for complex systems

DEFF Research Database (Denmark)

Sadegh, Payman; Spall, J. C.

1998-01-01

configuration is based on maximizing the overall sensor response while minimizing the correlation among the sensor outputs. The procedure for sensor configuration is based on simultaneous perturbation stochastic approximation (SPSA). SPSA avoids the need for detailed modeling of the sensor response by simply......Considers the problem of sensor configuration for complex systems. Our approach involves definition of an appropriate optimality criterion or performance measure, and description of an efficient and practical algorithm for achieving the optimality objective. The criterion for optimal sensor...... relying on observed responses as obtained by limited experimentation with test sensor configurations. We illustrate the approach with the optimal placement of acoustic sensors for signal detection in structures. This includes both a computer simulation study for an aluminum plate, and real...

Green Wave Traffic Optimization - A Survey

DEFF Research Database (Denmark)

Warberg, Andreas; Larsen, Jesper; Jørgensen, Rene Munk

The objective of this survey is to cover the research in the area of adaptive traffic control with emphasis on the applied optimization methods. The problem of optimizing traffic signals can be viewed in various ways, depending on political, economic and ecological goals. The survey highlights some...... important conflicts, which support the notion that traffic signal optimization is a multi-objective problem, and relates this to the most common measures of effectiveness. A distinction can be made between classical systems, which operate with a common cycle time, and the more flexible, phase......-based, approach, which is shown to be more suitable for adaptive traffic control. To support this claim three adaptive systems, which use alternatives to the classical optimization procedures, are described in detail....

Optimization of reagent concentration for radioiodination of rat C-peptide II in development of radioimmunoassay procedure for rats

Directory of Open Access Journals (Sweden)

B R Manupriya

2018-01-01

Full Text Available Rat C-peptide is a polypeptide molecule made up of 31 amino acids and secreted from pancreas into circulation in two isoforms I and II. Quantification of rat C-peptide II in rat serum is important as it is directly related to the diagnosis of carbohydrate metabolism abnormalities, pancreatic performance analysis, monitoring of hypoglycemia, and diabetes-related illness in rat model. The aim of the present work is to develop a tracer by chloramine-T method for radioimmunoassay (RIA procedure and to determine the optimum amount of chloramine-T required for the preparation of stable radioiodinated product with a specific activity of around 24.97 MBq/μg, corresponding to 1 125I atom per molecule of the peptide. Tyrosylated rat C-peptide II was selected for the radioiodination procedure as rat C-peptide II does not contain either tyrosine or histidine which is mandatory for the incorporation of 125I atom to the rat C-peptide II. Tyrosylated rat C-peptide II was subjected to radioiodination by chloramine-T method with different concentrations of chloramine-T and sodium metabisulfite (MBS to obtain a stable radiolabeled compound. Optimized reaction conditions relating to the concentration of chloramine-T (10 μg and MBS (20 μg yielded a stable 125I-rat C-peptide II with specific activity of 21.01 MBq/μg corresponding to 0.84 125I atoms per molecule of the peptide. Preparation of high integrity tracer of rat C-peptide II was achieved by combining one molecule of oxidant (chloramine-T and two molecule of reductant (MBS.

Optimal transport of particle beams

International Nuclear Information System (INIS)

Allen, C.K.; Reiser, M.

1997-01-01

The transport and matching problem for a low energy transport system is approached from a control theoretical viewpoint. We develop a model for a beam transport and matching section based on a multistage control network. To this model we apply the principles of optimal control to formulate techniques aiding in the design of the transport and matching section. Both nonlinear programming and dynamic programming techniques are used in the optimization. These techniques are implemented in a computer-aided design program called SPOT. Examples are presented to demonstrate the procedure and outline the results. (orig.)

Automation and Optimization of Multipulse Laser Zona Drilling of Mouse Embryos During Embryo Biopsy.

Science.gov (United States)

Wong, Christopher Yee; Mills, James K

2017-03-01

Laser zona drilling (LZD) is a required step in many embryonic surgical procedures, for example, assisted hatching and preimplantation genetic diagnosis. LZD involves the ablation of the zona pellucida (ZP) using a laser while minimizing potentially harmful thermal effects on critical internal cell structures. Develop a method for the automation and optimization of multipulse LZD, applied to cleavage-stage embryos. A two-stage optimization is used. The first stage uses computer vision algorithms to identify embryonic structures and determines the optimal ablation zone farthest away from critical structures such as blastomeres. The second stage combines a genetic algorithm with a previously reported thermal analysis of LZD to optimize the combination of laser pulse locations and pulse durations. The goal is to minimize the peak temperature experienced by the blastomeres while creating the desired opening in the ZP. A proof of concept of the proposed LZD automation and optimization method is demonstrated through experiments on mouse embryos with positive results, as adequately sized openings are created. Automation of LZD is feasible and is a viable step toward the automation of embryo biopsy procedures. LZD is a common but delicate procedure performed by human operators using subjective methods to gauge proper LZD procedure. Automation of LZD removes human error to increase the success rate of LZD. Although the proposed methods are developed for cleavage-stage embryos, the same methods may be applied to most types LZD procedures, embryos at different developmental stages, or nonembryonic cells.

Optimized tomography of observables

International Nuclear Information System (INIS)

D'Ariano, G.M.; Paris, G. A.

1998-01-01

Tomographic measurement of observables is revisited and an adaptive optimization of the kernel functions suggested. The method is based on the existence of a class of null functions, which have zero tomographic average for any state of radiation. The general procedure is illustrated, and application to relevant observables analyzed in details for coherent, squeezed and 'cat' states.(author)

Space and time optimization of nuclear reactors by means of the Pontryagin principle

International Nuclear Information System (INIS)

Anton, V.

1979-01-01

A numerical method is being presented for solving space dependent optimization problems concerning a functional for one dimensional geometries in the few group diffusion approximation. General dimensional analysis was applied to derive relations for the maximum of a functional and the limiting values of the constraints. Two procedures were given for calculating the anisotropic diffusion coefficients in order to improve the results of the diffusion approximation. In this work two procedures were presented for collapsing the microscopic multigroup cross sections, one general and another specific to the space dependent optimization problems solved by means of the Pontryagin maximum principle. Neutron spectrum optimization is performed to ensure the burnup of Pu 239 isotope produced in a thermal nuclear reactor. A procedure is also given for the minimization of finite functional set by means of the Pontryagin maximum principle. A method for determining the characteristics of fission Pseudo products is formulated in one group and multigroup cases. This method is applied in the optimization of the burnup in nuclear reactors with fuel electric cells. A procedure to mjnimze the number of the fuel burnup equations is described. The optimization problems presented and solved in this work point to the efficiency of the maximum principle. Each problem on method presented in the various chapters is accompanied by considerations concerning dual problems and possibilities of further research development. (author)

Extremely Efficient Design of Organic Thin Film Solar Cells via Learning-Based Optimization

Directory of Open Access Journals (Sweden)

Mine Kaya

2017-11-01

Full Text Available Design of efficient thin film photovoltaic (PV cells require optical power absorption to be computed inside a nano-scale structure of photovoltaics, dielectric and plasmonic materials. Calculating power absorption requires Maxwell’s electromagnetic equations which are solved using numerical methods, such as finite difference time domain (FDTD. The computational cost of thin film PV cell design and optimization is therefore cumbersome, due to successive FDTD simulations. This cost can be reduced using a surrogate-based optimization procedure. In this study, we deploy neural networks (NNs to model optical absorption in organic PV structures. We use the corresponding surrogate-based optimization procedure to maximize light trapping inside thin film organic cells infused with metallic particles. Metallic particles are known to induce plasmonic effects at the metal–semiconductor interface, thus increasing absorption. However, a rigorous design procedure is required to achieve the best performance within known design guidelines. As a result of using NNs to model thin film solar absorption, the required time to complete optimization is decreased by more than five times. The obtained NN model is found to be very reliable. The optimization procedure results in absorption enhancement greater than 200%. Furthermore, we demonstrate that once a reliable surrogate model such as the developed NN is available, it can be used for alternative analyses on the proposed design, such as uncertainty analysis (e.g., fabrication error.

Optimizing production and imperfect preventive maintenance planning's integration in failure-prone manufacturing systems

International Nuclear Information System (INIS)

Aghezzaf, El-Houssaine; Khatab, Abdelhakim; Tam, Phuoc Le

2016-01-01

This paper investigates the issue of integrating production and maintenance planning in a failure-prone manufacturing system. It is assumed that the system's operating state is stochastically predictable, in terms of its operating age, and that it can accordingly be preventively maintained during preplanned periods. Preventive maintenance is assumed to be imperfect, that is when performed, it brings the manufacturing system to an operating state that lies between ‘as bad as old’ and ‘as good as new’. Only an overhauling of the system brings it to a ‘as good as new’ operating state again. A practical integrated production and preventive maintenance planning model, that takes into account the system's manufacturing capacity and its operational reliability state, is developed. The model is naturally formulated as a mixed-integer non-linear optimization problem, for which an extended mixed-integer linear reformulation is proposed. This reformulation, while it solves the proposed integrated planning problem to optimality, remains quite demanding in terms of computational time. A fix-and-optimize procedure, that takes advantage of some properties of the original model, is then proposed. The reformulation and the fix-and-optimize procedure are tested on some test instances adapted from those available in the literature. The results show that the proposed fix-and-optimize procedure performs quite well and opens new research direction for future improvements. - Highlights: • Integration of production planning and imperfect preventive maintenance is explored. • Imperfect maintenance is modeled using a fitting age reduction hybrid hazard rate. • A practical approximate optimization model for this integration is proposed. • The resulting naturally MINL optimization model is reformulated and solved as a MILP. • An effective fix-and-optimize procedure is proposed for large instances of this MILP.

58. Actitud frente al flujo sanguíneo pulmonar adicional en la operación de glenn

Directory of Open Access Journals (Sweden)

F. Serrano Martínez

2010-01-01

Conclusiones: El mantenimiento de FPAC no incrementa la morbimortalidad post-Glenn ni altera la conservación funcional del ventrículo único, permitiendo llegar a la fase pre-Fontan con mayor SaO2 y mejor tamaño de ramas pulmonares. La existencia o ausencia de FPAC no influyó en los resultados del Fontan posterior, aunque consideramos interesante mantenerlo, especialmente en casos con ramas pulmonares pequeñas. La paliación pre-Glenn tipo banding pulmonar se asoció a mayor imposibilidad de conservar un FPAC.

Optimization of Grillages Using Genetic Algorithms for Integrating Matlab and Fortran Environments

Directory of Open Access Journals (Sweden)

Darius Mačiūnas

2013-02-01

Full Text Available The purpose of the paper is to present technology applied for the global optimization of grillage-type pile foundations (further grillages. The goal of optimization is to obtain the optimal layout of pile placement in the grillages. The problem can be categorized as a topology optimization problem. The objective function is comprised of maximum reactive force emerging in a pile. The reactive force is minimized during the procedure of optimization during which variables enclose the positions of piles beneath connecting beams. Reactive forces in all piles are computed utilizing an original algorithm implemented in the Fortran programming language. The algorithm is integrated into the MatLab environment where the optimization procedure is executed utilizing a genetic algorithm. The article also describes technology enabling the integration of MatLab and Fortran environments. The authors seek to evaluate the quality of a solution to the problem analyzing experimental results obtained applying the proposed technology.

Optimization of Grillages Using Genetic Algorithms for Integrating Matlab and Fortran Environments

Directory of Open Access Journals (Sweden)

Darius Mačiūnas

2012-12-01

Full Text Available The purpose of the paper is to present technology applied for the global optimization of grillage-type pile foundations (further grillages. The goal of optimization is to obtain the optimal layout of pile placement in the grillages. The problem can be categorized as a topology optimization problem. The objective function is comprised of maximum reactive force emerging in a pile. The reactive force is minimized during the procedure of optimization during which variables enclose the positions of piles beneath connecting beams. Reactive forces in all piles are computed utilizing an original algorithm implemented in the Fortran programming language. The algorithm is integrated into the MatLab environment where the optimization procedure is executed utilizing a genetic algorithm. The article also describes technology enabling the integration of MatLab and Fortran environments. The authors seek to evaluate the quality of a solution to the problem analyzing experimental results obtained applying the proposed technology.

LASL lens design procedure: simple, fast, precise, versatile

International Nuclear Information System (INIS)

Brixner, B.

1978-11-01

The Los Alamos Scientific Laboratory general-purpose lens design procedure optimizes specific lens prescriptions to obtain the smallest possible image spots and therefore near-spherical wave fronts of light converging on all images in the field of view. Optical image errors are analyzed in much the same way that they are measured on the optical bench. This lens design method is made possible by using the full capabilities of large electronic computers. First, the performance of the whole lens is sampled with many precisely traced skew rays. Next, lens performance is analyzed with spot diagrams generated by the many rays. Third, lens performance is optimized with a least squares system aimed at reducing all image errors to zero. This statistical approach to lens design uses skew rays and precisely measured ray deviations from ideal image points to achieve greater accuracy than was possible with the classical procedure, which is based on approximate expressions derived from simplified ray traces developed for pencil-and-paper calculations

Optimal control of helicopters following power failure. Helicopter no engine koshoji no saiteki hiko seigyo

Energy Technology Data Exchange (ETDEWEB)

Okuno, Y.

1993-01-01

In order to study the optimal control of helicopters, the control procedures following power failure were theoretically investigated by applying nonlinear optimal control theory to the following four optimization problems. The first was minimization of the touchdown speed following power failure. Comparisons between the calculated optimal solutions and the empirical flight test results showed that pilots used nonoptimal controls, especially in the timing and amplitude of the collective flare before touchdowns. The second was prediction of the height-velocity (H-V) boundaries. The calculated H-V boundaries showed good correlation with the flight test results. The third was optimization of the takeoff procedures for category A STOL operation following power failure. The results showed that the required takeoff distance using the normal takeoff procedure can be significantly reduced. The fourth was evaluation of the takeoff performance for category A VTOL operation. The calculating method of the maximum takeoff weight was confirmed, and possibility of allowing the payload to be increased was shown. 38 refs., 53 figs.

VISUALIZATION SOFTWARE DEVELOPMENT FOR PROCEDURE OF MULTI-DIMENSIONAL OPTIMIZATION OF TECHNOLOGICAL PROCESS FUNCTIONAL PARAMETERS

Directory of Open Access Journals (Sweden)

E. N. Ishakova

2016-05-01

Full Text Available A method for multi-criteria optimization of the design parameters for technological object is described. The existing optimization methods are overviewed, and works in the field of basic research and applied problems are analyzed. The problem is formulated, based on the process requirements, making it possible to choose the geometrical dimensions of machine tips and the flow rate of the process, so that the resulting technical and economical parameters were optimal. In the problem formulation application of the performance method adapted to a particular domain is described. Task implementation is shown; the method of characteristics creation for the studied object in view of some restrictions for parameters in both analytical and graphical representation. On the basis of theoretical research the software system is developed that gives the possibility to automate the discovery of optimal solutions for specific problems. Using available information sources, that characterize the object of study, it is possible to establish identifiers, add restrictions from the one side, and in the interval as well. Obtained result is a visual depiction of dependence of the main study parameters on the others, which may have an impact on both the flow of the process, and the quality of products. The resulting optimal area shows the use of different design options for technological object in an acceptable kinematic range that makes it possible for the researcher to choose the best design solution.

Optimal reduction of flexible dynamic system

International Nuclear Information System (INIS)

Jankovic, J.

1994-01-01

Dynamic system reduction is basic procedure in various problems of active control synthesis of flexible structures. In this paper is presented direct method for system reduction by explicit extraction of modes included in reduced model form. Criterion for optimal system discrete approximation in synthesis reduced dynamic model is also presented. Subjected method of system decomposition is discussed in relation to the Schur method of solving matrix algebraic Riccati equation as condition for system reduction. By using exposed method procedure of flexible system reduction in addition with corresponding example is presented. Shown procedure is powerful in problems of active control synthesis of flexible system vibrations

Optimization of a wearable power system

Energy Technology Data Exchange (ETDEWEB)

Kovacevic, I.; Round, S. D.; Kolar, J. W.; Boulouchos, K.

2008-07-01

In this paper the optimization of wearable power system comprising of an internal combustion engine, motor/generator, inverter/rectifier, Li-battery pack, DC/DC converters, and controller is performed. The Wearable Power System must have the capability to supply an average 20 W for 4 days with peak power of 200 W and have a system weight less then 4 kg. The main objectives are to select the engine, fuel and battery type, to match the weight of fuel and the number of battery cells, to find the optimal working point of engine and minimizing the system weight. The minimization problem is defined in Matlab as a nonlinear constrained optimization task. The optimization procedure returns the optimal system design parameters: the Li-polymer battery with eight cells connected in series for a 28 V DC output voltage, the selection of gasoline/oil fuel mixture and the optimal engine working point of 12 krpm for a 4.5 cm{sup 3} 4-stroke engine. (author)

Wave drag as the objective function in transonic fighter wing optimization

Science.gov (United States)

Phillips, P. S.

1984-01-01

The original computational method for determining wave drag in a three dimensional transonic analysis method was replaced by a wave drag formula based on the loss in momentum across an isentropic shock. This formula was used as the objective function in a numerical optimization procedure to reduce the wave drag of a fighter wing at transonic maneuver conditions. The optimization procedure minimized wave drag through modifications to the wing section contours defined by a wing profile shape function. A significant reduction in wave drag was achieved while maintaining a high lift coefficient. Comparisons of the pressure distributions for the initial and optimized wing geometries showed significant reductions in the leading-edge peaks and shock strength across the span.

Teleportation of squeezing: Optimization using non-Gaussian resources

International Nuclear Information System (INIS)

Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio; Adesso, Gerardo

2010-01-01

We study the continuous-variable quantum teleportation of states, statistical moments of observables, and scale parameters such as squeezing. We investigate the problem both in ideal and imperfect Vaidman-Braunstein-Kimble protocol setups. We show how the teleportation fidelity is maximized and the difference between output and input variances is minimized by using suitably optimized entangled resources. Specifically, we consider the teleportation of coherent squeezed states, exploiting squeezed Bell states as entangled resources. This class of non-Gaussian states, introduced by Illuminati and co-workers [F. Dell'Anno, S. De Siena, L. Albano, and F. Illuminati, Phys. Rev. A 76, 022301 (2007); F. Dell'Anno, S. De Siena, and F. Illuminati, ibid. 81, 012333 (2010)], includes photon-added and photon-subtracted squeezed states as special cases. At variance with the case of entangled Gaussian resources, the use of entangled non-Gaussian squeezed Bell resources allows one to choose different optimization procedures that lead to inequivalent results. Performing two independent optimization procedures, one can either maximize the state teleportation fidelity, or minimize the difference between input and output quadrature variances. The two different procedures are compared depending on the degrees of displacement and squeezing of the input states and on the working conditions in ideal and nonideal setups.

Heart transplantation for adults with congenital heart disease: current status and future prospects.

Science.gov (United States)

Matsuda, Hikaru; Ichikawa, Hajime; Ueno, Takayoshi; Sawa, Yoshiki

2017-06-01

Increased survival rates after corrective or palliative surgery for complex congenital heart disease (CHD) in infancy and childhood are now being coupled with increased numbers of patients who survive to adulthood with various residual lesions or sequelae. These patients are likely to deteriorate in cardiac function or end-organ function, eventually requiring lifesaving treatment including heart transplantation. Although early and late outcomes of heart transplantation have been improving for adult survivors of CHD, outcomes and pretransplant management could still be improved. Survivors of Fontan procedures are a vulnerable cohort, particularly when single ventricle physiology fails, mostly with protein-losing enteropathy and hepatic dysfunction. Therefore, we reviewed single-institution and larger database analyses of adults who underwent heart transplantation for CHD, to enable risk stratification by identifying the indications and outcomes. As the results, despite relatively high early mortality, long-term results were encouraging after heart transplantation. However, further investigations are needed to improve the indication criteria for complex CHD, especially for failed Fontan. In addition, the current system of status criteria and donor heart allocation system in heart transplantation should be arranged as suitable for adults with complex CHD. Furthermore, there is a strong need to develop ventricular assist devices as a bridge to transplantation or destination therapy, especially where right-sided circulatory support is needed.

Efficiency Optimization in Class-D Audio Amplifiers

DEFF Research Database (Denmark)

Yamauchi, Akira; Knott, Arnold; Jørgensen, Ivan Harald Holger

2015-01-01

This paper presents a new power efficiency optimization routine for designing Class-D audio amplifiers. The proposed optimization procedure finds design parameters for the power stage and the output filter, and the optimum switching frequency such that the weighted power losses are minimized under...... the given constraints. The optimization routine is applied to minimize the power losses in a 130 W class-D audio amplifier based on consumer behavior investigations, where the amplifier operates at idle and low power levels most of the time. Experimental results demonstrate that the optimization method can...... lead to around 30 % of efficiency improvement at 1.3 W output power without significant effects on both audio performance and the efficiency at high power levels....

Current perspectives on the optimal age to spay/castrate dogs and cats

Directory of Open Access Journals (Sweden)

Howe LM

2015-05-01

Full Text Available Lisa M HoweDepartment of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USAAbstract: Spaying and castrating of dogs and cats has been considered for decades to be a routine standard of practice in veterinary medicine in the US for the prevention of numerous undesirable behaviors, medical conditions, and diseases. Additionally, the procedures have been promoted as a method of curbing the severe pet-overpopulation problem in the US. Recently, however, this routine practice has come under scrutiny and become a very controversial topic. The general wisdom and safety of the procedures have been questioned by those who are concerned that the procedures may have some unintended consequences that are only recently being recognized. The purpose of this paper is to critically examine the scientific literature regarding elective spay/castration procedures and present both risks and benefits of elective gonadectomy. After the literature is examined, it becomes clear that there may not be a single absolute optimal age to spay or castrate all dogs and cats, but that the optimal age may be dependent upon several factors, including species, breed, body size, and breed-specific diseases, among others. Determining the optimal age to perform elective gonadectomy is much clearer in cats, and the literature demonstrates that the procedures can typically be safely performed at any age after 6–8 weeks of age. The optimal age to spay or castrate dogs of certain breeds (rottweiler, golden retriever, Labrador retriever, and vizsla is becoming less clear as studies are being conducted as to the health benefits and risks in those breeds. This review will examine these controversies and make recommendations as to the optimal age to spay/castrate dogs based upon the scientific literature.Keywords: gonadectomy (neuter, ovariohysterectomy (spay, castration, neoplasia, longevity, orthopedic

Optimization of automation: III. Development of optimization method for determining automation rate in nuclear power plants

International Nuclear Information System (INIS)

Lee, Seung Min; Kim, Jong Hyun; Kim, Man Cheol; Seong, Poong Hyun

2016-01-01

Highlights: • We propose an appropriate automation rate that enables the best human performance. • We analyze the shortest working time considering Situation Awareness Recovery (SAR). • The optimized automation rate is estimated by integrating the automation and ostracism rate estimation methods. • The process to derive the optimized automation rate is demonstrated through case studies. - Abstract: Automation has been introduced in various industries, including the nuclear field, because it is commonly believed that automation promises greater efficiency, lower workloads, and fewer operator errors through reducing operator errors and enhancing operator and system performance. However, the excessive introduction of automation has deteriorated operator performance due to the side effects of automation, which are referred to as Out-of-the-Loop (OOTL), and this is critical issue that must be resolved. Thus, in order to determine the optimal level of automation introduction that assures the best human operator performance, a quantitative method of optimizing the automation is proposed in this paper. In order to propose the optimization method for determining appropriate automation levels that enable the best human performance, the automation rate and ostracism rate, which are estimation methods that quantitatively analyze the positive and negative effects of automation, respectively, are integrated. The integration was conducted in order to derive the shortest working time through considering the concept of situation awareness recovery (SAR), which states that the automation rate with the shortest working time assures the best human performance. The process to derive the optimized automation rate is demonstrated through an emergency operation scenario-based case study. In this case study, four types of procedures are assumed through redesigning the original emergency operating procedure according to the introduced automation and ostracism levels. Using the

Optimization of Perfect Absorbers with Multilayer Structures

Science.gov (United States)

Li Voti, Roberto

2018-02-01

We study wide-angle and broadband perfect absorbers with compact multilayer structures made of a sequence of ITO and TiN layers deposited onto a silver thick layer. An optimization procedure is introduced for searching the optimal thicknesses of the layers so as to design a perfect broadband absorber from 400 nm to 750 nm, for a wide range of angles of incidence from 0{°} to 50{°}, for both polarizations and with a low emissivity in the mid-infrared. We eventually compare the performances of several optimal structures that can be very promising for solar thermal energy harvesting and collectors.

Experimental design technique applied to the validation of an instrumental Neutron Activation Analysis procedure

International Nuclear Information System (INIS)

Santos, Uanda Paula de M. dos; Moreira, Edson Gonçalves

2017-01-01

In this study optimization of procedures and standardization of Instrumental Neutron Activation Analysis (INAA) method were carried out for the determination of the elements bromine, chlorine, magnesium, manganese, potassium, sodium and vanadium in biological matrix materials using short irradiations at a pneumatic system. 2 k experimental designs were applied for evaluation of the individual contribution of selected variables of the analytical procedure in the final mass fraction result. The chosen experimental designs were the 2 3 and the 2 4 , depending on the radionuclide half life. Different certified reference materials and multi-element comparators were analyzed considering the following variables: sample decay time, irradiation time, counting time and sample distance to detector. Comparator concentration, sample mass and irradiation time were maintained constant in this procedure. By means of the statistical analysis and theoretical and experimental considerations, it was determined the optimized experimental conditions for the analytical methods that will be adopted for the validation procedure of INAA methods in the Neutron Activation Analysis Laboratory (LAN) of the Research Reactor Center (CRPq) at the Nuclear and Energy Research Institute (IPEN /CNEN-SP). Optimized conditions were estimated based on the results of z-score tests, main effect, interaction effects and better irradiation conditions. (author)

Experimental design technique applied to the validation of an instrumental Neutron Activation Analysis procedure

Energy Technology Data Exchange (ETDEWEB)

Santos, Uanda Paula de M. dos; Moreira, Edson Gonçalves, E-mail: uandapaula@gmail.com, E-mail: emoreira@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

2017-07-01

In this study optimization of procedures and standardization of Instrumental Neutron Activation Analysis (INAA) method were carried out for the determination of the elements bromine, chlorine, magnesium, manganese, potassium, sodium and vanadium in biological matrix materials using short irradiations at a pneumatic system. 2{sup k} experimental designs were applied for evaluation of the individual contribution of selected variables of the analytical procedure in the final mass fraction result. The chosen experimental designs were the 2{sup 3} and the 2{sup 4}, depending on the radionuclide half life. Different certified reference materials and multi-element comparators were analyzed considering the following variables: sample decay time, irradiation time, counting time and sample distance to detector. Comparator concentration, sample mass and irradiation time were maintained constant in this procedure. By means of the statistical analysis and theoretical and experimental considerations, it was determined the optimized experimental conditions for the analytical methods that will be adopted for the validation procedure of INAA methods in the Neutron Activation Analysis Laboratory (LAN) of the Research Reactor Center (CRPq) at the Nuclear and Energy Research Institute (IPEN /CNEN-SP). Optimized conditions were estimated based on the results of z-score tests, main effect, interaction effects and better irradiation conditions. (author)

Methods for optimizing over the efficient and weakly efficient sets of an affine fractional vector optimization program

DEFF Research Database (Denmark)

Le, T.H.A.; Pham, D. T.; Canh, Nam Nguyen

2010-01-01

Both the efficient and weakly efficient sets of an affine fractional vector optimization problem, in general, are neither convex nor given explicitly. Optimization problems over one of these sets are thus nonconvex. We propose two methods for optimizing a real-valued function over the efficient...... and weakly efficient sets of an affine fractional vector optimization problem. The first method is a local one. By using a regularization function, we reformulate the problem into a standard smooth mathematical programming problem that allows applying available methods for smooth programming. In case...... the objective function is linear, we have investigated a global algorithm based upon a branch-and-bound procedure. The algorithm uses Lagrangian bound coupling with a simplicial bisection in the criteria space. Preliminary computational results show that the global algorithm is promising....

Patients exposure from fluoroscopic guided pacemaker implantation procedures

International Nuclear Information System (INIS)

Alkhorayef, M.; Babikir, E.; Sulieman, A.; Daar, E.; Alnaaimi, M.; Alduaij, M.; Bradley, D.

2016-10-01

A pacemaker, which is used for heart re synchronization with electrical impulses, is used to manage many clinical conditions. Recently, the frequency of the pacemaker implantation procedures increased 50% worldwide. During this procedure, patients and staff can be exposed to excessive radiation exposure. Wide range of doses was reported in previous studies, suggesting that optimization of this procedure is not fulfilled yet. This study aims to evaluate the patient and staff radiation doses during cardiac pacemaker procedure and quantify the patient effective dose. A total of 145 procedures were performed for five pacemakers procedures (VVI, VVIR, VVD, VVDR and DDDR) two hospitals were evaluated. Patients doses were measured using the kerma-area product meter. Effective doses were estimated using software based on Monte Carlo simulation from National Radiological Protection Board. The effective dose values were used to estimate the cancer risk from pacemaker procedure. Patients demographic data, exposure parameters for both fluoroscopy and radiography were quantified. The mean patients doses (Gy. cm 2 ) for VVI, VVIR, VVD, VVDR and DDDR was 1.52±0.13 (1.43-1.61), 3.28±2.34 (0.29-8.73), 3.04±1.67 (1.57-4.86), 6.04±2.326 and 19.2±3.6 (5.43-30.2), respectively, per procedure. The overall patients effective dose is 1.1 mSv per procedure. (Author)

Patients exposure from fluoroscopic guided pacemaker implantation procedures

Energy Technology Data Exchange (ETDEWEB)

Alkhorayef, M.; Babikir, E. [King Saud University, College of Applied Sciences, Radiological Sciences Department, P. O. Box 10219, Riyadh 11433 (Saudi Arabia); Sulieman, A. [Prince Sattam bin Abdulaziz University, College of Applied Medical Sciences, Radiology and Medical Imaging Department, P. O. Box 422, Alkharj 11942 (Saudi Arabia); Daar, E. [University of Jordan, Faculty of Science, Department of Physics, Amman 11942 (Jordan); Alnaaimi, M.; Alduaij, M. [Kuwait Cancer Control Centre, Department of Nuclear Medicine, Shwiekh (Kuwait); Bradley, D., E-mail: malkhorayef@ksu.edu.sa [University of Surrey, Centre for Nuclear and Radiation Physics, Guildford, Surrey, GU2 7XH (United Kingdom)

2016-10-15

A pacemaker, which is used for heart re synchronization with electrical impulses, is used to manage many clinical conditions. Recently, the frequency of the pacemaker implantation procedures increased 50% worldwide. During this procedure, patients and staff can be exposed to excessive radiation exposure. Wide range of doses was reported in previous studies, suggesting that optimization of this procedure is not fulfilled yet. This study aims to evaluate the patient and staff radiation doses during cardiac pacemaker procedure and quantify the patient effective dose. A total of 145 procedures were performed for five pacemakers procedures (VVI, VVIR, VVD, VVDR and DDDR) two hospitals were evaluated. Patients doses were measured using the kerma-area product meter. Effective doses were estimated using software based on Monte Carlo simulation from National Radiological Protection Board. The effective dose values were used to estimate the cancer risk from pacemaker procedure. Patients demographic data, exposure parameters for both fluoroscopy and radiography were quantified. The mean patients doses (Gy. cm{sup 2}) for VVI, VVIR, VVD, VVDR and DDDR was 1.52±0.13 (1.43-1.61), 3.28±2.34 (0.29-8.73), 3.04±1.67 (1.57-4.86), 6.04±2.326 and 19.2±3.6 (5.43-30.2), respectively, per procedure. The overall patients effective dose is 1.1 mSv per procedure. (Author)

Design optimization for fuel reloading in Laguna Verde nuclear power plant

International Nuclear Information System (INIS)

Cortes Campos, C.C.; Montes Tadeo, J.L.

1991-01-01

Procedure followed to perform the design optimation in fuel reloading is described in general words and also is shown an example in which such procedure was uses for analysis of BWR type reactor in unit 1 of Laguna Verde nuclear power plant (Author)

Optimal tree-stem bucking of northeastern species of China

Science.gov (United States)

Jingxin Wang; Chris B. LeDoux; Joseph McNeel

2004-01-01

An application of optimal tree-stem bucking to the northeastern tree species of China is reported. The bucking procedures used in this region are summarized, which are the basic guidelines for the optimal bucking design. The directed graph approach was adopted to generate the bucking patterns by using the network analysis labeling algorithm. A computer-based bucking...

A neurocomputational theory of how explicit learning bootstraps early procedural learning.

Science.gov (United States)

Paul, Erick J; Ashby, F Gregory

2013-01-01

It is widely accepted that human learning and memory is mediated by multiple memory systems that are each best suited to different requirements and demands. Within the domain of categorization, at least two systems are thought to facilitate learning: an explicit (declarative) system depending largely on the prefrontal cortex, and a procedural (non-declarative) system depending on the basal ganglia. Substantial evidence suggests that each system is optimally suited to learn particular categorization tasks. However, it remains unknown precisely how these systems interact to produce optimal learning and behavior. In order to investigate this issue, the present research evaluated the progression of learning through simulation of categorization tasks using COVIS, a well-known model of human category learning that includes both explicit and procedural learning systems. Specifically, the model's parameter space was thoroughly explored in procedurally learned categorization tasks across a variety of conditions and architectures to identify plausible interaction architectures. The simulation results support the hypothesis that one-way interaction between the systems occurs such that the explicit system "bootstraps" learning early on in the procedural system. Thus, the procedural system initially learns a suboptimal strategy employed by the explicit system and later refines its strategy. This bootstrapping could be from cortical-striatal projections that originate in premotor or motor regions of cortex, or possibly by the explicit system's control of motor responses through basal ganglia-mediated loops.

Pacing and Defibrillators in Complex Congenital Heart Disease

Science.gov (United States)

Chubb, Henry; O’Neill, Mark; Rosenthal, Eric

2016-01-01

Device therapy in the complex congenital heart disease (CHD) population is a challenging field. There is a myriad of devices available, but none designed specifically for the CHD patient group, and a scarcity of prospective studies to guide best practice. Baseline cardiac anatomy, prior surgical and interventional procedures, existing tachyarrhythmias and the requirement for future intervention all play a substantial role in decision making. For both pacing systems and implantable cardioverter defibrillators, numerous factors impact on the merits of system location (endovascular versus non-endovascular), lead positioning, device selection and device programming. For those with Fontan circulation and following the atrial switch procedure there are also very specific considerations regarding access and potential complications. This review discusses the published guidelines, device indications and the best available evidence for guidance of device implantation in the complex CHD population. PMID:27403295

Optimization of wearable microwave antenna with simplified electromagnetic model of the human body

Science.gov (United States)

Januszkiewicz, Łukasz; Barba, Paolo Di; Hausman, Sławomir

2017-12-01

In this paper the problem of optimization design of a microwave wearable antenna is investigated. Reference is made to a specific antenna design that is a wideband Vee antenna the geometry of which is characterized by 6 parameters. These parameters were automatically adjusted with an evolution strategy based algorithm EStra to obtain the impedance matching of the antenna located in the proximity of the human body. The antenna was designed to operate in the ISM (industrial, scientific, medical) band which covers the frequency range of 2.4 GHz up to 2.5 GHz. The optimization procedure used the finite-difference time-domain method based full-wave simulator with a simplified human body model. In the optimization procedure small movements of antenna towards or away of the human body that are likely to happen during real use were considered. The stability of the antenna parameters irrespective of the movements of the user's body is an important factor in wearable antenna design. The optimization procedure allowed obtaining good impedance matching for a given range of antenna distances with respect to the human body.

Social media methods for studying rare diseases.

Science.gov (United States)

Schumacher, Kurt R; Stringer, Kathleen A; Donohue, Janet E; Yu, Sunkyung; Shaver, Ashley; Caruthers, Regine L; Zikmund-Fisher, Brian J; Fifer, Carlen; Goldberg, Caren; Russell, Mark W

2014-05-01

For pediatric rare diseases, the number of patients available to support traditional research methods is often inadequate. However, patients who have similar diseases cluster "virtually" online via social media. This study aimed to (1) determine whether patients who have the rare diseases Fontan-associated protein losing enteropathy (PLE) and plastic bronchitis (PB) would participate in online research, and (2) explore response patterns to examine social media's role in participation compared with other referral modalities. A novel, internet-based survey querying details of potential pathogenesis, course, and treatment of PLE and PB was created. The study was available online via web and Facebook portals for 1 year. Apart from 2 study-initiated posts on patient-run Facebook pages at the study initiation, all recruitment was driven by study respondents only. Response patterns and referral sources were tracked. A total of 671 respondents with a Fontan palliation completed a valid survey, including 76 who had PLE and 46 who had PB. Responses over time demonstrated periodic, marked increases as new online populations of Fontan patients were reached. Of the responses, 574 (86%) were from the United States and 97 (14%) were international. The leading referral sources were Facebook, internet forums, and traditional websites. Overall, social media outlets referred 84% of all responses, making it the dominant modality for recruiting the largest reported contemporary cohort of Fontan patients and patients who have PLE and PB. The methodology and response patterns from this study can be used to design research applications for other rare diseases. Copyright © 2014 by the American Academy of Pediatrics.

On centralized power pool auction: a novel multipliers stabilization procedure

International Nuclear Information System (INIS)

Jimenez-Redondo, Noemi

2005-01-01

This paper addresses the Short-Term Hydro-Thermal Coordination (STHTC) problem. It is a large-scale, combinatorial and nonlinear optimization problem. It is usually solved using a Lagrangian Relaxation (LR) approach. LR procedure is based on the solution of the dual problem of the original one. The dual problem variables are the Lagrange multipliers. These multipliers have an economic meaning: electric energy hourly prices. This paper focuses on an efficient solution of the dual problem of the STHTC problem. A novel multiplier stabilization technique, which significantly improves the quality of the solution, is presented. The provided method could be the optimization tool used by the Independent System Operator of a centralized Power Pool. The solution procedure diminishes the conflict of interest in determining energy prices. A realistic large-scale case study illustrates the behavior of the presented approach. (Author)

A novel design procedure for tractor clutch fingers by using optimization and response surface methods

Energy Technology Data Exchange (ETDEWEB)

Dogan, Oguz; Karpat, Fatih; Yuce, Celalettin; Kaya, Necmettin; Yavuz, Nurettin [Uludag University, Gorukle (Turkmenistan); Sen, Hasan [Valeo A. S., Bursa (Turkmenistan)

2016-06-15

This paper presents a methodology for re-designing a failed tractor transmission component subjected to cyclic loading. Unlike other vehicles, tractors cope with tough working conditions. Thus, it is necessary to re-design components by using modern optimization techniques. To extend their service life, we present a design methodology for a failed tractor clutch power take-off finger. The finger was completely re-designed using topology and shape optimization approach. Stress-life based fatigue analyses were performed. Shape optimization and response surface methodology were conducted to obtain optimum dimensions of the finger. Two design parameters were selected for the design of experiment method and 15 cases were analyzed. By using design of the experiment method, three responses were obtained: Maximum stresses, mass, and displacement depending on the selected the design parameters. After solving the optimization problem, we achieved a maximum stress and mass reduction of 14% and 6%, respectively. The stiffness was improved up to 31.6% compared to the initial design.

Techniques for the optimal design of photovoltaic inverters interconnected with the electric grid

DEFF Research Database (Denmark)

Koutroulis, Eftichios; Blaabjerg, Frede

2011-01-01

the Genetic Algorithm-based optimization procedure is the PV inverter Levelized Cost Of the Electricity generated (LCOE). The proposed method has been applied for the optimal design of PV inverters installed at various sites in Europe. The simulation results indicate that the optimal values of the PV inverter...

Multiobjective Optimization Involving Quadratic Functions

Directory of Open Access Journals (Sweden)

Oscar Brito Augusto

2014-01-01

Full Text Available Multiobjective optimization is nowadays a word of order in engineering projects. Although the idea involved is simple, the implementation of any procedure to solve a general problem is not an easy task. Evolutionary algorithms are widespread as a satisfactory technique to find a candidate set for the solution. Usually they supply a discrete picture of the Pareto front even if this front is continuous. In this paper we propose three methods for solving unconstrained multiobjective optimization problems involving quadratic functions. In the first, for biobjective optimization defined in the bidimensional space, a continuous Pareto set is found analytically. In the second, applicable to multiobjective optimization, a condition test is proposed to check if a point in the decision space is Pareto optimum or not and, in the third, with functions defined in n-dimensional space, a direct noniterative algorithm is proposed to find the Pareto set. Simple problems highlight the suitability of the proposed methods.

Optimal power and distribution control for weakly-coupled-core reactor

International Nuclear Information System (INIS)

Oohori, Takahumi; Kaji, Ikuo

1977-01-01

A numerical procedure has been devised for obtaining the optimal power and distribution control for a weakly-coupled-core reactor. Several difficulties were encountered in solving this optimization problem: (1) nonlinearity of the reactor kinetics equations; (2) neutron-leakage interaction between the cores; (3) localized power changes occurring in addition to the total power changes; (4) constraints imposed on the states - e.g. reactivity, reactor period. To obviate these difficulties, use is made of the generalized Newton method to convert the problem into an iterative sequence of linear programming problems, after approximating the differential equations and the integral performance criterion by a set of discrete algebraic equations. In this procedure, a heuristic but effective method is used for deriving an initial approximation, which is then made to converge toward the optimal solution. Delayed-neutron one-group point reactor models embodying transient temperature feed-back to the reactivity are used in obtaining the kinetics equations for the weakly-coupled-core reactor. The criterion adopted for determining the optimality is a norm relevant to the deviations of neutron density from the desired trajectories or else to the time derivatives of the neutron density; uniform control intervals are prescribed. Examples are given of two coupled-core reactors with typical parameters to illustrate the results obtained with this procedure. A comparison is also made between the coupled-core reactor and the one-point reactor. (auth.)

Rethinking exchange market models as optimization algorithms

Science.gov (United States)

Luquini, Evandro; Omar, Nizam

2018-02-01

The exchange market model has mainly been used to study the inequality problem. Although the human society inequality problem is very important, the exchange market models dynamics until stationary state and its capability of ranking individuals is interesting in itself. This study considers the hypothesis that the exchange market model could be understood as an optimization procedure. We present herein the implications for algorithmic optimization and also the possibility of a new family of exchange market models

Multi-objective parametric optimization of powder mixed electro ...

Indian Academy of Sciences (India)

Multiple linear regression models have ... surface optimization scheme to select the parameters in powder mixed EDM process. Keskin ... Genetic algorithm (GA) is a subclass of population based stochastic search procedure which is.

STRUCTURAL OPTIMIZATION OF FUNCTIONALLY GRADED MATERIALS WITH SMALL CONCENTRATION OF INCLUSIONS

Directory of Open Access Journals (Sweden)

DISKOVSKY A. A.

2017-01-01

Full Text Available Raising of problem.With an optimal design of inner structure of functionally graded material (FGM based on the classical method of homogenization procedure, in cases of low concentration of inclusions, when the size of inclusions is essentially less than the distance between them, leads to computational difficulties. Purpose – the research to develop a homogenization procedure, allowing solving effectively the problem of optimizing the internal structure of FGM at low concentrations of inclusions and illustration with specific examples. Conclusion. The proposed method allows solving tasks of calculation and optimal design of the internal structure of FGM structures with variable inclusions and with a variable step between them using the same methodology. The optimization is performed using two mechanisms. The first allocation is fixed at the edges of the border areas in which inclusions are absent. The second optimization mechanism is the distribution of inclusions sizes under the law, coinciding with the distribution law of an external load. Alternate step for the step should be reduced in areas with greater intensity of the external load.

Texture mapping via optimal mass transport.

Science.gov (United States)

Dominitz, Ayelet; Tannenbaum, Allen

2010-01-01

In this paper, we present a novel method for texture mapping of closed surfaces. Our method is based on the technique of optimal mass transport (also known as the "earth-mover's metric"). This is a classical problem that concerns determining the optimal way, in the sense of minimal transportation cost, of moving a pile of soil from one site to another. In our context, the resulting mapping is area preserving and minimizes angle distortion in the optimal mass sense. Indeed, we first begin with an angle-preserving mapping (which may greatly distort area) and then correct it using the mass transport procedure derived via a certain gradient flow. In order to obtain fast convergence to the optimal mapping, we incorporate a multiresolution scheme into our flow. We also use ideas from discrete exterior calculus in our computations.

Simulation and Optimization of Control of Selected Phases of Gyroplane Flight

Directory of Open Access Journals (Sweden)

Wienczyslaw Stalewski

2018-02-01

Full Text Available Optimization methods are increasingly used to solve problems in aeronautical engineering. Typically, optimization methods are utilized in the design of an aircraft airframe or its structure. The presented study is focused on improvement of aircraft flight control procedures through numerical optimization. The optimization problems concern selected phases of flight of a light gyroplane—a rotorcraft using an unpowered rotor in autorotation to develop lift and an engine-powered propeller to provide thrust. An original methodology of computational simulation of rotorcraft flight was developed and implemented. In this approach the aircraft motion equations are solved step-by-step, simultaneously with the solution of the Unsteady Reynolds-Averaged Navier–Stokes equations, which is conducted to assess aerodynamic forces acting on the aircraft. As a numerical optimization method, the BFGS (Broyden–Fletcher–Goldfarb–Shanno algorithm was adapted. The developed methodology was applied to optimize the flight control procedures in selected stages of gyroplane flight in direct proximity to the ground, where proper control of the aircraft is critical to ensure flight safety and performance. The results of conducted computational optimizations proved the qualitative correctness of the developed methodology. The research results can be helpful in the design of easy-to-control gyroplanes and also in the training of pilots for this type of rotorcraft.

Teleportation of squeezing: Optimization using non-Gaussian resources

Science.gov (United States)

Dell'Anno, Fabio; de Siena, Silvio; Adesso, Gerardo; Illuminati, Fabrizio

2010-12-01

We study the continuous-variable quantum teleportation of states, statistical moments of observables, and scale parameters such as squeezing. We investigate the problem both in ideal and imperfect Vaidman-Braunstein-Kimble protocol setups. We show how the teleportation fidelity is maximized and the difference between output and input variances is minimized by using suitably optimized entangled resources. Specifically, we consider the teleportation of coherent squeezed states, exploiting squeezed Bell states as entangled resources. This class of non-Gaussian states, introduced by Illuminati and co-workers [F. Dell’Anno, S. De Siena, L. Albano, and F. Illuminati, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.76.022301 76, 022301 (2007); F. Dell’Anno, S. De Siena, and F. Illuminati, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.81.012333 81, 012333 (2010)], includes photon-added and photon-subtracted squeezed states as special cases. At variance with the case of entangled Gaussian resources, the use of entangled non-Gaussian squeezed Bell resources allows one to choose different optimization procedures that lead to inequivalent results. Performing two independent optimization procedures, one can either maximize the state teleportation fidelity, or minimize the difference between input and output quadrature variances. The two different procedures are compared depending on the degrees of displacement and squeezing of the input states and on the working conditions in ideal and nonideal setups.

Development and Optimization of a Flocculation Procedure for Improved Solid-Liquid Separation of Digested Biomass

Energy Technology Data Exchange (ETDEWEB)

Patton, Caroline; Lischeske, James J.; Sievers, David A.

2015-11-03

One viable treatment method for conversion of lignocellulosic biomass to biofuels begins with saccharification (thermochemical pretreatment and enzymatic hydrolysis), followed by fermentation or catalytic upgrading to fuels such as ethanol, butanol, or other hydrocarbons. The post-hydrolysis slurry is typically 4-8 percent insoluble solids, predominantly consisting of lignin. Suspended solids are known to inhibit fermentation as well as poison catalysts and obstruct flow in catalyst beds. Thus a solid-liquid separation following enzymatic hydrolysis would be highly favorable for process economics, however the material is not easily separated by filtration or gravimetric methods. Use of a polyacrylamide flocculant to bind the suspended particles in a corn stover hydrolyzate slurry into larger flocs (1-2mm diameter) has been found to be extremely helpful in improving separation. Recent and ongoing research on novel pretreatment methods yields hydrolyzate material with diverse characteristics. Therefore, we need a thorough understanding of rapid and successful flocculation design in order to quickly achieve process design goals. In this study potential indicators of flocculation performance were investigated in order to develop a rapid analysis method for flocculation procedure in the context of a novel hydrolyzate material. Flocculation conditions were optimized on flocculant type and loading, pH, and mixing time. Filtration flux of the hydrolyzate slurry was improved 170-fold using a cationic polyacrylamide flocculant with a dosing of approximately 22 mg flocculant/g insoluble solids at an approximate pH of 3. With cake washing, sugar recovery exceeded 90 percent with asymptotic yield at 15 L wash water/kg insoluble solids.

Review of dynamic optimization methods in renewable natural resource management

Science.gov (United States)

Williams, B.K.

1989-01-01

In recent years, the applications of dynamic optimization procedures in natural resource management have proliferated. A systematic review of these applications is given in terms of a number of optimization methodologies and natural resource systems. The applicability of the methods to renewable natural resource systems are compared in terms of system complexity, system size, and precision of the optimal solutions. Recommendations are made concerning the appropriate methods for certain kinds of biological resource problems.

Multi-Objective Patch Optimization with Integrated Kinematic Draping Simulation for Continuous–Discontinuous Fiber-Reinforced Composite Structures

Directory of Open Access Journals (Sweden)

Benedikt Fengler

2018-03-01

Full Text Available Discontinuous fiber-reinforced polymers (DiCoFRP in combination with local continuous fiber reinforced polymers (CoFRP provide both a high design freedom and high weight-specific mechanical properties. For the optimization of CoFRP patches on complexly shaped DiCoFRP structures, an optimization strategy is needed which considers manufacturing constraints during the optimization procedure. Therefore, a genetic algorithm is combined with a kinematic draping simulation. To determine the optimal patch position with regard to structural performance and overall material consumption, a multi-objective optimization strategy is used. The resulting Pareto front and a corresponding heat-map of the patch position are useful tools for the design engineer to choose the right amount of reinforcement. The proposed patch optimization procedure is applied to two example structures and the effect of different optimization setups is demonstrated.

Sulcal set optimization for cortical surface registration.

Science.gov (United States)

Joshi, Anand A; Pantazis, Dimitrios; Li, Quanzheng; Damasio, Hanna; Shattuck, David W; Toga, Arthur W; Leahy, Richard M

2010-04-15

Flat mapping based cortical surface registration constrained by manually traced sulcal curves has been widely used for inter subject comparisons of neuroanatomical data. Even for an experienced neuroanatomist, manual sulcal tracing can be quite time consuming, with the cost increasing with the number of sulcal curves used for registration. We present a method for estimation of an optimal subset of size N(C) from N possible candidate sulcal curves that minimizes a mean squared error metric over all combinations of N(C) curves. The resulting procedure allows us to estimate a subset with a reduced number of curves to be traced as part of the registration procedure leading to optimal use of manual labeling effort for registration. To minimize the error metric we analyze the correlation structure of the errors in the sulcal curves by modeling them as a multivariate Gaussian distribution. For a given subset of sulci used as constraints in surface registration, the proposed model estimates registration error based on the correlation structure of the sulcal errors. The optimal subset of constraint curves consists of the N(C) sulci that jointly minimize the estimated error variance for the subset of unconstrained curves conditioned on the N(C) constraint curves. The optimal subsets of sulci are presented and the estimated and actual registration errors for these subsets are computed. Copyright 2009 Elsevier Inc. All rights reserved.

Wind Generators Test Bench. Optimal Design of PI Controller

Directory of Open Access Journals (Sweden)

TUDORACHE, T.

2011-08-01

Full Text Available This paper proposes a novel and robust strategy for the optimal design of the drive system integrated in a wind generators test bench. The PI regulator coefficients used in control systems are usually computed based on simplified hypotheses and then tuned manually so as the system response meet certain specifications in terms of stability, accuracy and speed. The proposed methodology permits the automatic identification of PI regulator coefficients using intelligent optimization algorithms, the initial guess for the search procedure being determined based on particular simplified hypotheses. The proposed procedure can help the design engineers to drastically reduce the effort for finding the best PI regulator coefficients offering a range of feasible solutions depending on the imposed optimum criteria. The characteristics and performances of the optimization strategy are highlighted by using it for the design of a DC motor drive system used to simulate the wind prime mover integrated in a wind generators test bench.

Comparing effectiveness and efficiency in technical specifications and maintenance optimization

International Nuclear Information System (INIS)

Martorell, Sebastian; Sanchez, Ana; Carlos, Sofia; Serradell, Vicente

2002-01-01

Optimization of technical specification requirements and maintenance (TS and M) has been found interesting from the very beginning at Nuclear Power Plants (NPPs). However, the resolution of such a kind of optimization problem has been limited often to focus only on individual TS and M-related parameters (STI, AOT, PM frequency, etc.) and/or adopting an individual optimization criterion (availability, costs, plant risks, etc.). Nevertheless, a number of reasons exist (e.g. interaction, similar scope, etc.) that justify the interest to focus on the coordinated optimization of all of the relevant TS and M-related parameters based on multiple criteria. The purpose of this paper is on signifying benefits and improvement areas in performing the coordinated optimization of TS and M through reviewing the effectiveness and efficiency of common strategies for optimizing TS and M at system level. A case of application is provided for a stand-by safety-related system to demonstrate the basic procedure and to extract a number of conclusions and recommendations from the results achieved. Thus, it is concluded that the optimized values depend on the particular TS and M-related parameters being involved and the solutions with the largest benefit (minimum risk or minimum cost) are achieved when considering the simultaneous optimization of all of them, although increased computational resources are also required. Consequently, it is necessary to analyze not only the value reached but also the performance of the optimization procedure through effectiveness and efficiency measures which lead to recommendations on potential improvement areas

A study of optimization techniques in HDR brachytherapy for the prostate

Science.gov (United States)

Pokharel, Ghana Shyam

Several studies carried out thus far are in favor of dose escalation to the prostate gland to have better local control of the disease. But optimal way of delivery of higher doses of radiation therapy to the prostate without hurting neighboring critical structures is still debatable. In this study, we proposed that real time high dose rate (HDR) brachytherapy with highly efficient and effective optimization could be an alternative means of precise delivery of such higher doses. This approach of delivery eliminates the critical issues such as treatment setup uncertainties and target localization as in external beam radiation therapy. Likewise, dosimetry in HDR brachytherapy is not influenced by organ edema and potential source migration as in permanent interstitial implants. Moreover, the recent report of radiobiological parameters further strengthen the argument of using hypofractionated HDR brachytherapy for the management of prostate cancer. Firstly, we studied the essential features and requirements of real time HDR brachytherapy treatment planning system. Automating catheter reconstruction with fast editing tools, fast yet accurate dose engine, robust and fast optimization and evaluation engine are some of the essential requirements for such procedures. Moreover, in most of the cases we performed, treatment plan optimization took significant amount of time of overall procedure. So, making treatment plan optimization automatic or semi-automatic with sufficient speed and accuracy was the goal of the remaining part of the project. Secondly, we studied the role of optimization function and constraints in overall quality of optimized plan. We have studied the gradient based deterministic algorithm with dose volume histogram (DVH) and more conventional variance based objective functions for optimization. In this optimization strategy, the relative weight of particular objective in aggregate objective function signifies its importance with respect to other objectives

Development of assessment procedures at the CEGB's nuclear power training centre

International Nuclear Information System (INIS)

Chapman, C.R.; Harris, N.D.C.

1986-01-01

The work of a power station engineer can be considered under four aspects: technology, diagnosis action and communication. The development, validation and use of assessment procedures can successfully incorporate the same aspects. The purposes of assessment are reporting training achievement and giving feedback to course members and tutorial staff. The development of standardized procedures to produce, evaluate and mark assessments and to optimize feedback ensures objectivity and uniformity. This has been achieved at the Central Electricity Generating Board's Nuclear Power Training Centre by enlisting an educational consultant to provide guidance and assist in training the resident tutors in assessment procedures. (author)

Optimizing Teleportation Cost in Distributed Quantum Circuits

Science.gov (United States)

Zomorodi-Moghadam, Mariam; Houshmand, Mahboobeh; Houshmand, Monireh

2018-03-01

The presented work provides a procedure for optimizing the communication cost of a distributed quantum circuit (DQC) in terms of the number of qubit teleportations. Because of technology limitations which do not allow large quantum computers to work as a single processing element, distributed quantum computation is an appropriate solution to overcome this difficulty. Previous studies have applied ad-hoc solutions to distribute a quantum system for special cases and applications. In this study, a general approach is proposed to optimize the number of teleportations for a DQC consisting of two spatially separated and long-distance quantum subsystems. To this end, different configurations of locations for executing gates whose qubits are in distinct subsystems are considered and for each of these configurations, the proposed algorithm is run to find the minimum number of required teleportations. Finally, the configuration which leads to the minimum number of teleportations is reported. The proposed method can be used as an automated procedure to find the configuration with the optimal communication cost for the DQC. This cost can be used as a basic measure of the communication cost for future works in the distributed quantum circuits.

Shape Optimization for Additive Manufacturing of Removable Partial Dentures--A New Paradigm for Prosthetic CAD/CAM.

Directory of Open Access Journals (Sweden)

Junning Chen

Full Text Available With ever-growing aging population and demand for denture treatments, pressure-induced mucosa lesion and residual ridge resorption remain main sources of clinical complications. Conventional denture design and fabrication are challenged for its labor and experience intensity, urgently necessitating an automatic procedure. This study aims to develop a fully automatic procedure enabling shape optimization and additive manufacturing of removable partial dentures (RPD, to maximize the uniformity of contact pressure distribution on the mucosa, thereby reducing associated clinical complications. A 3D heterogeneous finite element (FE model was constructed from CT scan, and the critical tissue of mucosa was modeled as a hyperelastic material from in vivo clinical data. A contact shape optimization algorithm was developed based on the bi-directional evolutionary structural optimization (BESO technique. Both initial and optimized dentures were prototyped by 3D printing technology and evaluated with in vitro tests. Through the optimization, the peak contact pressure was reduced by 70%, and the uniformity was improved by 63%. In vitro tests verified the effectiveness of this procedure, and the hydrostatic pressure induced in the mucosa is well below clinical pressure-pain thresholds (PPT, potentially lessening risk of residual ridge resorption. This proposed computational optimization and additive fabrication procedure provides a novel method for fast denture design and adjustment at low cost, with quantitative guidelines and computer aided design and manufacturing (CAD/CAM for a specific patient. The integration of digitalized modeling, computational optimization, and free-form fabrication enables more efficient clinical adaptation. The customized optimal denture design is expected to minimize pain/discomfort and potentially reduce long-term residual ridge resorption.

Shape Optimization for Additive Manufacturing of Removable Partial Dentures - A New Paradigm for Prosthetic CAD/CAM

Science.gov (United States)

2015-01-01

With ever-growing aging population and demand for denture treatments, pressure-induced mucosa lesion and residual ridge resorption remain main sources of clinical complications. Conventional denture design and fabrication are challenged for its labor and experience intensity, urgently necessitating an automatic procedure. This study aims to develop a fully automatic procedure enabling shape optimization and additive manufacturing of removable partial dentures (RPD), to maximize the uniformity of contact pressure distribution on the mucosa, thereby reducing associated clinical complications. A 3D heterogeneous finite element (FE) model was constructed from CT scan, and the critical tissue of mucosa was modeled as a hyperelastic material from in vivo clinical data. A contact shape optimization algorithm was developed based on the bi-directional evolutionary structural optimization (BESO) technique. Both initial and optimized dentures were prototyped by 3D printing technology and evaluated with in vitro tests. Through the optimization, the peak contact pressure was reduced by 70%, and the uniformity was improved by 63%. In vitro tests verified the effectiveness of this procedure, and the hydrostatic pressure induced in the mucosa is well below clinical pressure-pain thresholds (PPT), potentially lessening risk of residual ridge resorption. This proposed computational optimization and additive fabrication procedure provides a novel method for fast denture design and adjustment at low cost, with quantitative guidelines and computer aided design and manufacturing (CAD/CAM) for a specific patient. The integration of digitalized modeling, computational optimization, and free-form fabrication enables more efficient clinical adaptation. The customized optimal denture design is expected to minimize pain/discomfort and potentially reduce long-term residual ridge resorption. PMID:26161878

Shape Optimization for Additive Manufacturing of Removable Partial Dentures--A New Paradigm for Prosthetic CAD/CAM.

Science.gov (United States)

Chen, Junning; Ahmad, Rohana; Suenaga, Hanako; Li, Wei; Sasaki, Keiichi; Swain, Michael; Li, Qing

2015-01-01

With ever-growing aging population and demand for denture treatments, pressure-induced mucosa lesion and residual ridge resorption remain main sources of clinical complications. Conventional denture design and fabrication are challenged for its labor and experience intensity, urgently necessitating an automatic procedure. This study aims to develop a fully automatic procedure enabling shape optimization and additive manufacturing of removable partial dentures (RPD), to maximize the uniformity of contact pressure distribution on the mucosa, thereby reducing associated clinical complications. A 3D heterogeneous finite element (FE) model was constructed from CT scan, and the critical tissue of mucosa was modeled as a hyperelastic material from in vivo clinical data. A contact shape optimization algorithm was developed based on the bi-directional evolutionary structural optimization (BESO) technique. Both initial and optimized dentures were prototyped by 3D printing technology and evaluated with in vitro tests. Through the optimization, the peak contact pressure was reduced by 70%, and the uniformity was improved by 63%. In vitro tests verified the effectiveness of this procedure, and the hydrostatic pressure induced in the mucosa is well below clinical pressure-pain thresholds (PPT), potentially lessening risk of residual ridge resorption. This proposed computational optimization and additive fabrication procedure provides a novel method for fast denture design and adjustment at low cost, with quantitative guidelines and computer aided design and manufacturing (CAD/CAM) for a specific patient. The integration of digitalized modeling, computational optimization, and free-form fabrication enables more efficient clinical adaptation. The customized optimal denture design is expected to minimize pain/discomfort and potentially reduce long-term residual ridge resorption.

Use of multilevel modeling for determining optimal parameters of heat supply systems

Science.gov (United States)

Stennikov, V. A.; Barakhtenko, E. A.; Sokolov, D. V.

2017-07-01

The problem of finding optimal parameters of a heat-supply system (HSS) is in ensuring the required throughput capacity of a heat network by determining pipeline diameters and characteristics and location of pumping stations. Effective methods for solving this problem, i.e., the method of stepwise optimization based on the concept of dynamic programming and the method of multicircuit optimization, were proposed in the context of the hydraulic circuit theory developed at Melentiev Energy Systems Institute (Siberian Branch, Russian Academy of Sciences). These methods enable us to determine optimal parameters of various types of piping systems due to flexible adaptability of the calculation procedure to intricate nonlinear mathematical models describing features of used equipment items and methods of their construction and operation. The new and most significant results achieved in developing methodological support and software for finding optimal parameters of complex heat supply systems are presented: a new procedure for solving the problem based on multilevel decomposition of a heat network model that makes it possible to proceed from the initial problem to a set of interrelated, less cumbersome subproblems with reduced dimensionality; a new algorithm implementing the method of multicircuit optimization and focused on the calculation of a hierarchical model of a heat supply system; the SOSNA software system for determining optimum parameters of intricate heat-supply systems and implementing the developed methodological foundation. The proposed procedure and algorithm enable us to solve engineering problems of finding the optimal parameters of multicircuit heat supply systems having large (real) dimensionality, and are applied in solving urgent problems related to the optimal development and reconstruction of these systems. The developed methodological foundation and software can be used for designing heat supply systems in the Central and the Admiralty regions in

Physiotherapy following elective orthopaedic procedures.

Science.gov (United States)

De Kleijn, P; Blamey, G; Zourikian, N; Dalzell, R; Lobet, S

2006-07-01

As haemophilic arthropathy and chronic synovitis are still the most important clinical features in people with haemophilia, different kinds of invasive and orthopaedic procedures have become more common during the last decades. The availability of clotting factor has made arthroplasty of one, or even multiple joints possible. This article highlights the role of physiotherapy before and after such procedures. Synovectomies are sometimes advocated in people with haemophilia to stop repetitive cycles of intra-articular bleeds and/or chronic synovitis. The synovectomy itself, however, does not solve the muscle atrophy, loss of range of motion (ROM), instability and poor propriocepsis, often developed during many years. The key is in taking advantage of the subsequent, relatively safe, bleed-free period to address these important issues. Although the preoperative ROM is the most important variable influencing the postoperative ROM after total knee arthroplasty, there are a few key points that should be considered to improve the outcome. Early mobilization, either manual or by means of a continuous passive mobilization machine, can be an optimal solution during the very first postoperative days. Muscle isometric contractions and light open kinetic chain exercises should also be started in order to restore the quadriceps control. Partial weight bearing can be started shortly after, because of quadriceps inhibition and to avoid excessive swelling. The use of continuous clotting factor replacement permits earlier and intensive rehabilitation during the postoperative period. During the rehabilitation of shoulder arthroplasty restoring the function of the rotator cuff is of utmost importance. Often the rotator cuff muscles are inhibited in the presence of pain and loss of ROM. Physiotherapy also assists in improving pain and maintaining ROM and strength. Functional weight-bearing tasks, such as using the upper limbs to sit and stand, are often discouraged during the first 6

Analysis of decision procedures for a sequence of inventory periods

International Nuclear Information System (INIS)

Avenhaus, R.

1982-07-01

Optimal test procedures for a sequence of inventory periods will be discussed. Starting with a game theoretical description of the conflict situation between the plant operator and the inspector, the objectives of the inspector as well as the general decision theoretical problem will be formulated. In the first part the objective of 'secure' detection will be emphasized which means that only at the end of the reference time a decision is taken by the inspector. In the second part the objective of 'timely' detection will be emphasized which will lead to sequential test procedures. At the end of the paper all procedures will be summarized, and in view of the multitude of procedures available at the moment some comments about future work will be given. (orig./HP) [de

Research reactor in-core fuel management optimization by application of multiple cyclic interchange algorithms

Energy Technology Data Exchange (ETDEWEB)

van Geemert, R.; Hoogenboom, J.E.; Gibcus, H.P.M. [Technische Univ. Delft (Netherlands). Interfacultair Reactor Inst.; Quist, A.J. [Delft University of Technology, Faculty of Applied Mathematics and Informatics Mekelweg 4, 2628 JB, Delft (Netherlands)

1998-12-01

Fuel shuffling optimization procedures are proposed for the Hoger Onderwijs Reactor (HOR) in Delft, The Netherlands, a 2MWth swimming-pool type research reactor. These procedures are based on the multiple cyclic interchange approach, according to which the search for the reload pattern associated with the highest objective function value can be thought of as divided in multiple stages. The transition from the initial to the final stage is characterized by an increase in the degree of locality of the search procedure. The general idea is that, during the first stages, the `elite` cluster containing the group of best patterns must be located, after which the solution space is sampled in a more and more local sense to find the local optimum in this cluster. The transition(s) from global search behaviour to local search behaviour can be either prompt, by defining strictly separate search regimes, or gradual by introducing stochastic acceptance tests. The possible objectives and the safety and operation constraints, as well as the optimization procedure, are discussed, followed by some optimization results for the HOR. (orig.) 4 refs.

Research reactor in-core fuel management optimization by application of multiple cyclic interchange algorithms

International Nuclear Information System (INIS)

Geemert, R. van; Hoogenboom, J.E.; Gibcus, H.P.M.

1998-01-01

Fuel shuffling optimization procedures are proposed for the Hoger Onderwijs Reactor (HOR) in Delft, The Netherlands, a 2MWth swimming-pool type research reactor. These procedures are based on the multiple cyclic interchange approach, according to which the search for the reload pattern associated with the highest objective function value can be thought of as divided in multiple stages. The transition from the initial to the final stage is characterized by an increase in the degree of locality of the search procedure. The general idea is that, during the first stages, the 'elite' cluster containing the group of best patterns must be located, after which the solution space is sampled in a more and more local sense to find the local optimum in this cluster. The transition(s) from global search behaviour to local search behaviour can be either prompt, by defining strictly separate search regimes, or gradual by introducing stochastic acceptance tests. The possible objectives and the safety and operation constraints, as well as the optimization procedure, are discussed, followed by some optimization results for the HOR. (orig.)

Application of multivariate techniques in the optimization of a procedure for the determination of bioavailable concentrations of Se and As in estuarine sediments by ICP OES using a concomitant metals analyzer as a hydride generator.

Science.gov (United States)

Lopes, Watson da Luz; Santelli, Ricardo Erthal; Oliveira, Eliane Padua; de Carvalho, Maria de Fátima Batista; Bezerra, Marcos Almeida

2009-10-15

A procedure has been developed for the determination of bioavailable concentrations of selenium and arsenic in estuarine sediments employing inductively coupled plasma optical emission spectrometry (ICP OES) using a concomitant metals analyzer device to perform hydride generation. The optimization of hydride generation was done in two steps: using a two-level factorial design for preliminary evaluation of studied factors and a Doehlert design to assess the optimal experimental conditions for analysis. Interferences of transition metallic ions (Cd(2+), Co(2+), Cu(2+), Fe(3+) and Ni(2+)) to selenium and arsenic signals were minimized by using higher hydrochloric acid concentrations. In this way, the procedure allowed the determination of selenium and arsenic in sediments with a detection limit of 25 and 30 microg kg(-1), respectively, assuming a 50-fold sample dilution (0.5 g sample extraction to 25 mL sample final volume). The precision, expressed as a relative standard deviation (% RSD, n=10), was 0.2% for both selenium and arsenic in 200 microg L(-1) solutions, which corresponds to 10 microg g(-1) in sediment samples after acid extraction. Applying the proposed procedure, a linear range of 0.08-10 and 0.10-10 microg g(-1) was obtained for selenium and arsenic, respectively. The developed procedure was validated by the analysis of two certified reference materials: industrial sludge (NIST 2782) and river sediment (NIST 8704). The results were in agreement with the certified values. The developed procedure was applied to evaluate the bioavailability of both elements in four sediment certified reference materials, in which there are not certified values for bioavailable fractions, and also in estuarine sediment samples collected in several sites of Guanabara Bay, an impacted environment in Rio de Janeiro, Brazil.

New Procedure to Develop Lumped Kinetic Models for Heavy Fuel Oil Combustion

KAUST Repository

Han, Yunqing

2016-09-20

A new procedure to develop accurate lumped kinetic models for complex fuels is proposed, and applied to the experimental data of the heavy fuel oil measured by thermogravimetry. The new procedure is based on the pseudocomponents representing different reaction stages, which are determined by a systematic optimization process to ensure that the separation of different reaction stages with highest accuracy. The procedure is implemented and the model prediction was compared against that from a conventional method, yielding a significantly improved agreement with the experimental data. © 2016 American Chemical Society.

A Neurocomputational Theory of how Explicit Learning Bootstraps Early Procedural Learning

Directory of Open Access Journals (Sweden)

Erick Joseph Paul

2013-12-01

Full Text Available It is widely accepted that human learning and memory is mediated by multiple memory systems that are each best suited to different requirements and demands. Within the domain of categorization, at least two systems are thought to facilitate learning: an explicit (declarative system depending largely on the prefrontal cortex, and a procedural (non-declarative system depending on the basal ganglia. Substantial evidence suggests that each system is optimally suited to learn particular categorization tasks. However, it remains unknown precisely how these systems interact to produce optimal learning and behavior. In order to investigate this issue, the present research evaluated the progression of learning through simulation of categorization tasks using COVIS, a well-known model of human category learning that includes both explicit and procedural learning systems. Specifically, the model's parameter space was thoroughly explored in procedurally learned categorization tasks across a variety of conditions and architectures to identify plausible interaction architectures. The simulation results support the hypothesis that one-way interaction between the systems occurs such that the explicit system "bootstraps" learning early on in the procedural system. Thus, the procedural system initially learns a suboptimal strategy employed by the explicit system and later refines its strategy. This bootstrapping could be from cortical-striatal projections that originate in premotor or motor regions of cortex, or possibly by the explicit system’s control of motor responses through basal ganglia-mediated loops.

Optimization of Fuel Consumption and Emissions for Auxiliary Power Unit Based on Multi-Objective Optimization Model

Directory of Open Access Journals (Sweden)

Yongpeng Shen

2016-02-01

Full Text Available Auxiliary power units (APUs are widely used for electric power generation in various types of electric vehicles, improvements in fuel economy and emissions of these vehicles directly depend on the operating point of the APUs. In order to balance the conflicting goals of fuel consumption and emissions reduction in the process of operating point choice, the APU operating point optimization problem is formulated as a constrained multi-objective optimization problem (CMOP firstly. The four competing objectives of this CMOP are fuel-electricity conversion cost, hydrocarbon (HC emissions, carbon monoxide (CO emissions and nitric oxide (NO x emissions. Then, the multi-objective particle swarm optimization (MOPSO algorithm and weighted metric decision making method are employed to solve the APU operating point multi-objective optimization model. Finally, bench experiments under New European driving cycle (NEDC, Federal test procedure (FTP and high way fuel economy test (HWFET driving cycles show that, compared with the results of the traditional fuel consumption single-objective optimization approach, the proposed multi-objective optimization approach shows significant improvements in emissions performance, at the expense of a slight drop in fuel efficiency.

Reliability Of A Novel Intracardiac Electrogram Method For AV And VV Delay Optimization And Comparability To Echocardiography Procedure For Determining Optimal Conduction Delays In CRT Patients

Directory of Open Access Journals (Sweden)

N Reinsch

2009-03-01

Full Text Available Background: Echocardiography is widely used to optimize CRT programming. A novel intracardiac electrogram method (IEGM was recently developed as an automated programmer-based method, designed to calculate optimal atrioventricular (AV and interventricular (VV delays and provide optimized delay values as an alternative to standard echocardiographic assessment.Objective: This study was aimed at determining the reliability of this new method. Furthermore the comparability of IEGM to existing echocardiographic parameters for determining optimal conduction delays was verified.Methods: Eleven patients (age 62.9± 8.7; 81% male; 73% ischemic, previously implanted with a cardiac resynchronisation therapy defibrillator (CRT-D underwent both echocardiographic and IEGM-based delay optimization.Results: Applying the IEGM method, concordance of three consecutively performed measurements was found in 3 (27% patients for AV delay and in 5 (45% patients for VV delay. Intra-individual variation between three measurements as assessed by the IEGM technique was up to 20 ms (AV: n=6; VV: n=4. E-wave, diastolic filling time and septal-to-lateral wall motion delay emerged as significantly different between the echo and IEGM optimization techniques (p < 0.05. The final AV delay setting was significantly different between both methods (echo: 126.4 ± 29.4 ms, IEGM: 183.6 ± 16.3 ms; p < 0.001; correlation: R = 0.573, p = 0.066. VV delay showed significant differences for optimized delays (echo: 46.4 ± 23.8 ms, IEGM: 10.9 ± 7.0 ms; p <0.01; correlation: R = -0.278, p = 0.407.Conclusion: The automated programmer-based IEGM-based method provides a simple and safe method to perform CRT optimization. However, the reliability of this method appears to be limited. Thus, it remains difficult for the examiner to determine the optimal hemodynamic settings. Additionally, as there was no correlation between the optimal AV- and VV-delays calculated by the IEGM method and the echo

The Case for Laboratory Developed Procedures

Directory of Open Access Journals (Sweden)

Karen L. Kaul MD, PhD

2017-07-01

Full Text Available An explosion of knowledge and technology is revolutionizing medicine and patient care. Novel testing must be brought to the clinic with safety and accuracy, but also in a timely and cost-effective manner, so that patients can benefit and laboratories can offer testing consistent with current guidelines. Under the oversight provided by the Clinical Laboratory Improvement Amendments, laboratories have been able to develop and optimize laboratory procedures for use in-house. Quality improvement programs, interlaboratory comparisons, and the ability of laboratories to adjust assays as needed to improve results, utilize new sample types, or incorporate new mutations, information, or technologies are positive aspects of Clinical Laboratory Improvement Amendments oversight of laboratory-developed procedures. Laboratories have a long history of successful service to patients operating under Clinical Laboratory Improvement Amendments. A series of detailed clinical examples illustrating the quality and positive impact of laboratory-developed procedures on patient care is provided. These examples also demonstrate how Clinical Laboratory Improvement Amendments oversight ensures accurate, reliable, and reproducible testing in clinical laboratories.

On the optimal degree of imperfect repair

International Nuclear Information System (INIS)

Finkelstein, Maxim

2015-01-01

A simple cost-wise comparison between the minimal and perfect repair of a system is discussed first using a relevant example. The main focus of this note, however, is on imperfect (general) repair. The best repair for our system in this case is defined as the one that corresponds to the optimal level (extent) of repair actions that minimize the long-run expected cost per unit of time. This complex optimization problem is considered for a specific imperfect repair model (Kijima II), using the developed earlier asymptotic approach to the corresponding virtual age modelling. It is shown that the optimal solution exists when the failure rate of a system tends to infinity as t tends to infinity and the corresponding cost function decreases sufficiently fast. An example illustrating the optimization procedure is considered

Optimizing How We Teach Research Methods

Science.gov (United States)

Cvancara, Kristen E.

2017-01-01

Courses: Research Methods (undergraduate or graduate level). Objective: The aim of this exercise is to optimize the ability for students to integrate an understanding of various methodologies across research paradigms within a 15-week semester, including a review of procedural steps and experiential learning activities to practice each method, a…

The PDB_REDO server for macromolecular structure model optimization

Directory of Open Access Journals (Sweden)

Robbie P. Joosten

2014-07-01

Full Text Available The refinement and validation of a crystallographic structure model is the last step before the coordinates and the associated data are submitted to the Protein Data Bank (PDB. The success of the refinement procedure is typically assessed by validating the models against geometrical criteria and the diffraction data, and is an important step in ensuring the quality of the PDB public archive [Read et al. (2011, Structure, 19, 1395–1412]. The PDB_REDO procedure aims for `constructive validation', aspiring to consistent and optimal refinement parameterization and pro-active model rebuilding, not only correcting errors but striving for optimal interpretation of the electron density. A web server for PDB_REDO has been implemented, allowing thorough, consistent and fully automated optimization of the refinement procedure in REFMAC and partial model rebuilding. The goal of the web server is to help practicing crystallographers to improve their model prior to submission to the PDB. For this, additional steps were implemented in the PDB_REDO pipeline, both in the refinement procedure, e.g. testing of resolution limits and k-fold cross-validation for small test sets, and as new validation criteria, e.g. the density-fit metrics implemented in EDSTATS and ligand validation as implemented in YASARA. Innovative ways to present the refinement and validation results to the user are also described, which together with auto-generated Coot scripts can guide users to subsequent model inspection and improvement. It is demonstrated that using the server can lead to substantial improvement of structure models before they are submitted to the PDB.

Procedural Skills Education – Colonoscopy as a Model

Directory of Open Access Journals (Sweden)

Maitreyi Raman

2008-01-01

Full Text Available Traditionally, surgical and procedural apprenticeship has been an assumed activity of students, without a formal educational context. With increasing barriers to patient and operating room access such as shorter work week hours for residents, and operating room and endoscopy time at a premium, alternate strategies to maximizing procedural skill development are being considered. Recently, the traditional surgical apprenticeship model has been challenged, with greater emphasis on the need for surgical and procedural skills training to be more transparent and for alternatives to patient-based training to be considered. Colonoscopy performance is a complex psychomotor skill requiring practioners to integrate multiple sensory inputs, and involves higher cortical centres for optimal performance. Colonoscopy skills involve mastery in the cognitive, technical and process domains. In the present review, we propose a model for teaching colonoscopy to the novice trainee based on educational theory.

Temporo-spatial IMRT optimization: concepts, implementation and initial results

International Nuclear Information System (INIS)

Trofimov, Alexei; Rietzel, Eike; Lu Hsiaoming; Martin, Benjamin; Jiang, Steve; Chen, George T Y; Bortfeld, Thomas

2005-01-01

With the recent availability of 4D-CT, the accuracy of information on internal organ motion during respiration has improved significantly. We investigate the utility of organ motion information in IMRT treatment planning, using an in-house prototype optimization system. Four approaches are compared: (1) planning with optimized margins, based on motion information; (2) the 'motion kernel' approach, in which a more accurate description of the dose deposit from a pencil beam to a moving target is achieved either through time-weighted averaging of influence matrices, calculated for different instances of anatomy (subsets of 4D-CT data, corresponding to various phases of motion) or through convolution of the pencil beam kernel with the probability density function describing the target motion; (3) optimal gating, or tracking with beam intensity maps optimized independently for each instance of anatomy; and (4) optimal tracking with beam intensity maps optimized simultaneously for all instances of anatomy. The optimization is based on a gradient technique and can handle both physical (dose-volume) and equivalent uniform dose constraints. Optimization requires voxel mapping from phase to phase in order to score the dose in individual voxels as they move. The results show that, compared to the other approaches, margin expansion has a significant disadvantage by substantially increasing the integral dose to patient. While gating or tracking result in the best dose conformation to the target, the former elongates treatment time, and the latter significantly complicates the delivery procedure. The 'motion kernel' approach does not provide a dosimetric advantage, compared to optimal tracking or gating, but might lead to more efficient delivery. A combination of gating with the 'motion kernel' or margin expansion approach will increase the duty cycle and may provide one with the most efficient solution, in terms of complexity of the delivery procedure and dose conformality to

Standard Operating Procedures for Preparing and Handling Sterile Male Tsetse flies for Release

International Nuclear Information System (INIS)

Argiles-Herrero, Rafa; Leak, Stephen G.A.

2016-01-01

The purpose of this SOP is to describe the procedures involved in preparing tsetse flies reared in a breeding facility for release in the field for the sterile insect technique (SIT) as a component of Area-Wide Insect pest Management (AW-IPM). Following the procedures which are outlined will help to ensure that the released sterile male tsetse flies are of optimal quality.

Multi-Objective Aerodynamic and Structural Optimization of Horizontal-Axis Wind Turbine Blades

Directory of Open Access Journals (Sweden)

Jie Zhu

2017-01-01

Full Text Available A procedure based on MATLAB combined with ANSYS is presented and utilized for the multi-objective aerodynamic and structural optimization of horizontal-axis wind turbine (HAWT blades. In order to minimize the cost of energy (COE and improve the overall performance of the blades, materials of carbon fiber reinforced plastic (CFRP combined with glass fiber reinforced plastic (GFRP are applied. The maximum annual energy production (AEP, the minimum blade mass and the minimum blade cost are taken as three objectives. Main aerodynamic and structural characteristics of the blades are employed as design variables. Various design requirements including strain, deflection, vibration and buckling limits are taken into account as constraints. To evaluate the aerodynamic performances and the structural behaviors, the blade element momentum (BEM theory and the finite element method (FEM are applied in the procedure. Moreover, the non-dominated sorting genetic algorithm (NSGA II, which constitutes the core of the procedure, is adapted for the multi-objective optimization of the blades. To prove the efficiency and reliability of the procedure, a commercial 1.5 MW HAWT blade is used as a case study, and a set of trade-off solutions is obtained. Compared with the original scheme, the optimization results show great improvements for the overall performance of the blade.

Synthesis of Optimal Isolation Systems of Hand-Transmitted Vibration

Directory of Open Access Journals (Sweden)

Marek Książek

1997-01-01

Full Text Available In this article a procedure is presented for the analytical synthesis of optimal vibration isolation for a hand-arm system subjected to stochastic excitation. A general approach is discussed for a selected vibration isolation criterion. The general procedure is illustrated by analytical examples for different hand-arm systems described by their driving-point impedances. The influence of particular forms of excitation and the structure of the vibroisolated hand-arm systems on the resultant vibration isolation is then discussed. Some numerical examples illustrating the procedure have also been included.

Combined shape and topology optimization of 3D structures

DEFF Research Database (Denmark)

Christiansen, Asger Nyman; Bærentzen, Jakob Andreas; Nobel-Jørgensen, Morten

2015-01-01

We present a method for automatic generation of 3D models based on shape and topology optimization. The optimization procedure, or model generation process, is initialized by a set of boundary conditions, an objective function, constraints and an initial structure. Using this input, the method...... will automatically deform and change the topology of the initial structure such that the objective function is optimized subject to the specified constraints and boundary conditions. For example, this tool can be used to improve the stiffness of a structure before printing, reduce the amount of material needed...

Risk and safety requirements for diagnostic and therapeutic procedures in allergology

DEFF Research Database (Denmark)

Kowalski, Marek L; Ansotegui, Ignacio; Aberer, Werner

2016-01-01

One of the major concerns in the practice of allergy is related to the safety of procedures for the diagnosis and treatment of allergic disease. Management (diagnosis and treatment) of hypersensitivity disorders involves often intentional exposure to potentially allergenic substances (during skin...... attempted to present general requirements necessary to assure the safety of these procedures. Following review of available literature a group of allergy experts within the World Allergy Organization (WAO), representing various continents and areas of allergy expertise, presents this report on risk...... associated with diagnostic and therapeutic procedures in allergology and proposes a consensus on safety requirements for performing procedures in allergy offices. Optimal safety measures including appropriate location, type and required time of supervision, availability of safety equipment, access...

Advanced Topology Optimization Methods for Conceptual Architectural Design

DEFF Research Database (Denmark)

Aage, Niels; Amir, Oded; Clausen, Anders

2015-01-01

This paper presents a series of new, advanced topology optimization methods, developed specifically for conceptual architectural design of structures. The proposed computational procedures are implemented as components in the framework of a Grasshopper plugin, providing novel capacities...

Advanced Topology Optimization Methods for Conceptual Architectural Design

DEFF Research Database (Denmark)

Aage, Niels; Amir, Oded; Clausen, Anders

2014-01-01

This paper presents a series of new, advanced topology optimization methods, developed specifically for conceptual architectural design of structures. The proposed computational procedures are implemented as components in the framework of a Grasshopper plugin, providing novel capacities...

On the Equivalence of Quadratic Optimization Problems Commonly Used in Portfolio Theory

OpenAIRE

Taras Bodnar; Nestor Parolya; Wolfgang Schmid

2012-01-01

In the paper, we consider three quadratic optimization problems which are frequently applied in portfolio theory, i.e, the Markowitz mean-variance problem as well as the problems based on the mean-variance utility function and the quadratic utility.Conditions are derived under which the solutions of these three optimization procedures coincide and are lying on the efficient frontier, the set of mean-variance optimal portfolios. It is shown that the solutions of the Markowitz optimization prob...

Robust Structured Control Design via LMI Optimization

DEFF Research Database (Denmark)

Adegas, Fabiano Daher; Stoustrup, Jakob

2011-01-01

This paper presents a new procedure for discrete-time robust structured control design. Parameter-dependent nonconvex conditions for stabilizable and induced L2-norm performance controllers are solved by an iterative linear matrix inequalities (LMI) optimization. A wide class of controller...... structures including decentralized of any order, fixed-order dynamic output feedback, static output feedback can be designed robust to polytopic uncertainties. Stability is proven by a parameter-dependent Lyapunov function. Numerical examples on robust stability margins shows that the proposed procedure can...

Efficient reanalysis techniques for robust topology optimization

DEFF Research Database (Denmark)

Amir, Oded; Sigmund, Ole; Lazarov, Boyan Stefanov

2012-01-01

efficient robust topology optimization procedures based on reanalysis techniques. The approach is demonstrated on two compliant mechanism design problems where robust design is achieved by employing either a worst case formulation or a stochastic formulation. It is shown that the time spent on finite...

Optimization of Flame Atomic Absorption Spectrometry for ...

African Journals Online (AJOL)

Optimization of Flame Atomic Absorption Spectrometry for Measurement of High Concentrations of Arsenic and Selenium. ... This procedure allowed a rapid determination of As from minimum 4.462 mg/L to higher concentrations without sample pretreatment. Besides As, this method successfully measured Se concentrations ...

Conceptual design of reinforced concrete structures using topology optimization with elastoplastic material modeling

DEFF Research Database (Denmark)

Bogomolny, Michael; Amir, Oded

2012-01-01

Design of reinforced concrete structures is governed by the nonlinear behavior of concrete and by its different strengths in tension and compression. The purpose of this article is to present a computational procedure for optimal conceptual design of reinforced concrete structures on the basis...... response must be considered. Optimized distribution of materials is achieved by introducing interpolation rules for both elastic and plastic material properties. Several numerical examples illustrate the capability and potential of the proposed procedure. Copyright © 2012 John Wiley & Sons, Ltd....

Shape optimization of a perforated pressure vessel cover under linearized stress constraints

International Nuclear Information System (INIS)

Choi, Woo-Seok; Kim, Tae-Wan; Seo, Ki-Seog

2008-01-01

One of the general methods to evaluate a failure condition is to compare a maximum stress with an allowable stress. A failure condition for a stress is usually applied to a concerned point rather than a concerned section. In an optimization procedure, these stress conditions are applied as constraints. But the ASME code that prescribes its general rules upon the design of a NSSS (nuclear steam supply system) has quite a different view on a failure condition. According to the ASME code Sec. III, a stress linearization should be performed to evaluate a failure condition of a structure. Since a few programs provide a procedure for a stress linearization through a post-processing stage, an extra calculation of the linearized stresses and the derivatives of a linearized stress are conducted to adopt the stress linearization results to an optimization procedure as constraints. In this research, an optimization technique that utilizes the results of a stress linearization as a constraint is proposed. The proposed method was applied to the shape design of a perforated pressure vessel cover

Sequential Optimization of Paths in Directed Graphs Relative to Different Cost Functions

KAUST Repository

Abubeker, Jewahir Ali

2011-05-14

This paper is devoted to the consideration of an algorithm for sequential optimization of paths in directed graphs relative to di_erent cost functions. The considered algorithm is based on an extension of dynamic programming which allows to represent the initial set of paths and the set of optimal paths after each application of optimization procedure in the form of a directed acyclic graph.

Optimization of a Pre-MEKC Separation SPE Procedure for Steroid Molecules in Human Urine Samples

Directory of Open Access Journals (Sweden)

Ilona Olędzka

2013-11-01

Full Text Available Many steroid hormones can be considered as potential biomarkers and their determination in body fluids can create opportunities for the rapid diagnosis of many diseases and disorders of the human body. Most existing methods for the determination of steroids are usually time- and labor-consuming and quite costly. Therefore, the aim of analytical laboratories is to develop a new, relatively low-cost and rapid implementation methodology for their determination in biological samples. Due to the fact that there is little literature data on concentrations of steroid hormones in urine samples, we have made attempts at the electrophoretic determination of these compounds. For this purpose, an extraction procedure for the optimized separation and simultaneous determination of seven steroid hormones in urine samples has been investigated. The isolation of analytes from biological samples was performed by liquid-liquid extraction (LLE with dichloromethane and compared to solid phase extraction (SPE with C18 and hydrophilic-lipophilic balance (HLB columns. To separate all the analytes a micellar electrokinetic capillary chromatography (MECK technique was employed. For full separation of all the analytes a running buffer (pH 9.2, composed of 10 mM sodium tetraborate decahydrate (borax, 50 mM sodium dodecyl sulfate (SDS, and 10% methanol was selected. The methodology developed in this work for the determination of steroid hormones meets all the requirements of analytical methods. The applicability of the method has been confirmed for the analysis of urine samples collected from volunteers—both men and women (students, amateur bodybuilders, using and not applying steroid doping. The data obtained during this work can be successfully used for further research on the determination of steroid hormones in urine samples.

Reward optimization of a repairable system

International Nuclear Information System (INIS)

Castro, I.T.; Perez-Ocon, R.

2006-01-01

This paper analyzes a system subject to repairable and non-repairable failures. Non-repairable failures lead to replacement of the system. Repairable failures, first lead to repair but they lead to replacement after a fixed number of repairs. Operating and repair times follow phase type distributions (PH-distributions) and the pattern of the operating times is modelled by a geometric process. In this context, the problem is to find the optimal number of repairs, which maximizes the long-run average reward per unit time. To this end, the optimal number is determined and it is obtained by efficient numerical procedures

Reward optimization of a repairable system

Energy Technology Data Exchange (ETDEWEB)

Castro, I.T. [Departamento de Matematicas, Facultad de Veterinaria, Universidad de Extremadura, Avenida de la Universidad, s/n. 10071 Caceres (Spain)]. E-mail: inmatorres@unex.es; Perez-Ocon, R. [Departamento de Estadistica e Investigacion Operativa, Facultad de Ciencias, Universidad de Granada, Avenida de Severo Ochoa, s/n. 18071 Granada (Spain)]. E-mail: rperezo@ugr.es

2006-03-15

This paper analyzes a system subject to repairable and non-repairable failures. Non-repairable failures lead to replacement of the system. Repairable failures, first lead to repair but they lead to replacement after a fixed number of repairs. Operating and repair times follow phase type distributions (PH-distributions) and the pattern of the operating times is modelled by a geometric process. In this context, the problem is to find the optimal number of repairs, which maximizes the long-run average reward per unit time. To this end, the optimal number is determined and it is obtained by efficient numerical procedures.

Sequential optimization of matrix chain multiplication relative to different cost functions

KAUST Repository

Chikalov, Igor; Hussain, Shahid; Moshkov, Mikhail

2011-01-01

In this paper, we present a methodology to optimize matrix chain multiplication sequentially relative to different cost functions such as total number of scalar multiplications, communication overhead in a multiprocessor environment, etc. For n matrices our optimization procedure requires O(n 3) arithmetic operations per one cost function. This work is done in the framework of a dynamic programming extension that allows sequential optimization relative to different criteria. © 2011 Springer-Verlag Berlin Heidelberg.

Optimization of the Runner for Extremely Low Head Bidirectional Tidal Bulb Turbine

Directory of Open Access Journals (Sweden)

Yongyao Luo

2017-06-01

Full Text Available This paper presents a multi-objective optimization procedure for bidirectional bulb turbine runners which is completed using ANSYS Workbench. The optimization procedure is able to check many more geometries with less manual work. In the procedure, the initial blade shape is parameterized, the inlet and outlet angles (β1, β2, as well as the starting and ending wrap angles (θ1, θ2 for the five sections of the blade profile, are selected as design variables, and the optimization target is set to obtain the maximum of the overall efficiency for the ebb and flood turbine modes. For the flow analysis, the ANSYS CFX code, with a SST (Shear Stress Transport k-ω turbulence model, has been used to evaluate the efficiency of the turbine. An efficient response surface model relating the design parameters and the objective functions is obtained. The optimization strategy was used to optimize a model bulb turbine runner. Model tests were carried out to validate the final designs and the design procedure. For the four-bladed turbine, the efficiency improvement is 5.5% in the ebb operation direction, and 2.9% in the flood operation direction, as well as 4.3% and 4.5% for the three-bladed turbine. Numerical simulations were then performed to analyze the pressure pulsation in the pressure and suction sides of the blade for the prototype turbine with optimal four-bladed and three-bladed runners. The results show that the runner rotational frequency (fn is the dominant frequency of the pressure pulsations in the blades for ebb and flood turbine modes, and the gravitational effect, rather than rotor-stator interaction (RSI, plays an important role in a low head horizontal axial turbine. The amplitudes of the pressure pulsations on the blade side facing the guide vanes varies little with the water head. However, the amplitudes of the pressure pulsations on the blade side facing the diffusion tube linearly increase with the water head. These results could provide

Hybrid palliation for critical systemic outflow obstruction: neither rapid stage 1 Norwood nor comprehensive stage 2 mitigate consequences of early risk factors.

Science.gov (United States)

Davies, Ryan R; Radtke, Wolfgang; Bhat, Majeed A; Baffa, Jeanne M; Woodford, Edward; Pizarro, Christian

2015-01-01

Hybrid palliation with branch pulmonary artery banding (bPAB) has become increasingly common in the early management of patients with critical left ventricular outflow obstruction. Optimal subsequent surgical palliation remains undefined. We retrospectively reviewed patients undergoing initial bPAB for single ventricle physiology with systemic outflow obstruction (2001-2013, n = 37). Patients were stratified by subsequent surgical palliation: stage 1 Norwood (St1N, n = 14), comprehensive stage 2 (CompSt2, n = 11), and none (n = 12). bPAB was performed at a median of 4 days and 2.7-kg, post-bPAB mortality was increased in patients with aortic atresia (odds ratio [OR] = 3.8, 95% confidence interval [CI] = 0.9-15.8) or birth weight <2 kg (OR = 13.8, 95% CI = 1.4-136.4). Palliation strategy did not affect transplant-free survival through second-stage palliation (St1N: 71.4%, CompSt2: 72.7%, P = .9). Among CompSt2 patients, there was a trend toward poorer survival with aortic atresia (0% vs 80%, P = .09); birth weight <2.5 kg was associated with decreased survival (0% vs 89.0%, P = .01). A trend toward lower survival with low birth weight was evident among St1N patients (<2 kg, OR = 0.1, 95% CI = 0.01-1.9, P = .09). CompSt2 mortality occurred on postoperative days 0 and 1. Mortality following St1N occurred at a median of 38.5 days (range = 23.5-104.5). Among survivors of stage 2 palliation, Fontan completion was performed in the same number of patients in each group (St1N: 6/8, 75%, CompSt2: 6/8, 75%). Both St1N and CompSt2 are viable options for subsequent palliation following initial hybrid procedure. Transplant-free survival and eventual Fontan candidacy are similar between groups. Delaying surgical palliation with the CompSt2 did not mitigate the impact of early risk factors such as low birth weight and aortic atresia. Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Optimization based tuning approach for offset free MPC

DEFF Research Database (Denmark)

Olesen, Daniel Haugård; Huusom, Jakob Kjøbsted; Jørgensen, John Bagterp

2012-01-01

We present an optimization based tuning procedure with certain robustness properties for an offset free Model Predictive Controller (MPC). The MPC is designed for multivariate processes that can be represented by an ARX model. The advantage of ARX model representations is that standard system...... identifiation techniques using convex optimization can be used for identification of such models from input-output data. The stochastic model of the ARX model identified from input-output data is modified with an ARMA model designed as part of the MPC-design procedure to ensure offset-free control. The ARMAX...... model description resulting from the extension can be realized as a state space model in innovation form. The MPC is designed and implemented based on this state space model in innovation form. Expressions for the closed-loop dynamics of the unconstrained system is used to derive the sensitivity...

Improvement of the safety level of installations with the generalization of procedures

International Nuclear Information System (INIS)

Cornille, Y.; Dupraz, B.; Schektman, N.

1986-06-01

The generalization of control procedures to the largest possible spectra of accidental situations which is being developed on pressurized water reactor units will allow to increase the safety level of these installations. This improvement has been quantified for some situations pointing out an appreciable mitigation of meltdown risk which could result. A new improvement is aimed with the definition and the utilization of new procedures ''by states'' which will allow an optimized treatment of situations resulting from multiple failures, now treated in the procedures SPI - SPU - U1. The needs related to these procedures and their development led to joint research and development programs between Electricite de France and the Institute of Protection and Nuclear Safety [fr

Maze Procedures for Atrial Fibrillation, From History to Practice.

Science.gov (United States)

Kik, Charles; Bogers, Ad J J C

2011-10-01

Atrial fibrillation may result in significant symptoms, (systemic) thrombo-embolism, as well as tachycardia-induced cardiomyopathy with cardiac failure, and consequently be associated with significant morbidity and mortality. Nowadays symptomatic atrial fibrillation can be treated with catheter-based ablation, surgical ablation or hybrid approaches. In this setting a fairly large number of surgical approaches and procedures are described and being practised. It should be clear that the Cox-maze procedure resulted from building up evidence and experience in different steps, while some of the present surgical approaches and techniques are being based only on technical feasibility with limited experience, rather than on a process of consequent methodology. Some of the issues still under debate are whether or not the maze procedure can be limited to the left atrium or even to isolation of the pulmonary veins or that bi-atrial procedures are indicated, whether or not cardiopulmonary bypass is to be applied and which route of exposure facilitates an optimal result. In addition, maze procedures are not procedures guide by electrophysiological mapping. At least in theory not in all patients all lesions of the maze procedures are necessary. A history and aspects of current practise in surgical treatment of atrial fibrillation is presented.

Optimization analysis of propulsion motor control efficiency

Directory of Open Access Journals (Sweden)

CAI Qingnan

2017-12-01

Full Text Available [Objectives] This paper aims to strengthen the control effect of propulsion motors and decrease the energy used during actual control procedures.[Methods] Based on the traditional propulsion motor equivalence circuit, we increase the iron loss current component, introduce the definition of power matching ratio, calculate the highest efficiency of a motor at a given speed and discuss the flux corresponding to the power matching ratio with the highest efficiency. In the original motor vector efficiency optimization control module, an efficiency optimization control module is added so as to achieve motor efficiency optimization and energy conservation.[Results] MATLAB/Simulink simulation data shows that the efficiency optimization control method is suitable for most conditions. The operation efficiency of the improved motor model is significantly higher than that of the original motor model, and its dynamic performance is good.[Conclusions] Our motor efficiency optimization control method can be applied in engineering to achieve energy conservation.

Data Transfer Advisor with Transport Profiling Optimization

Energy Technology Data Exchange (ETDEWEB)

Rao, Nageswara S. [ORNL; Liu, Qiang [ORNL; Yun, Daqing [Harrisburg University; Wu, Chase Qishi [New Jersey Institute of Technology; Kettimuthu, R. [Argonne National Laboratory (ANL); Jung, Eun-sung [Argonne National Laboratory (ANL)

2017-11-01

The network infrastructures have been rapidly upgraded in many high-performance networks (HPNs). However, such infrastructure investment has not led to corresponding performance improvement in big data transfer, especially at the application layer, largely due to the complexity of optimizing transport control on end hosts. We design and implement ProbData, a PRofiling Optimization Based DAta Transfer Advisor, to help users determine the most effective data transfer method with the most appropriate control parameter values to achieve the best data transfer performance. ProbData employs a profiling optimization based approach to exploit the optimal operational zone of various data transfer methods in support of big data transfer in extreme scale scientific applications. We present a theoretical framework of the optimized profiling approach employed in ProbData as wellas its detailed design and implementation. The advising procedure and performance benefits of ProbData are illustrated and evaluated by proof-of-concept experiments in real-life networks.

Reduced medical and occupational exposures by optimizing working procedures in fluoroscopy equipment in the University Hospital of Santa Maria (RS)

International Nuclear Information System (INIS)

Weis, Guilherme L.; Claus, Thiago V.; Baumhardt, Tadeu; Shuch, Luiz A.

2013-01-01

This work seeks to reduce medical (patient) and occupational (workers) exposure by standardizing resources available in fluoroscopy equipment used in interventional procedures. Such procedures use transportable surgical arch type fluoroscopy equipment, with applications in orthopedics, angiography and pacemaker implantation. Improper use of these devices generates excessive radiation doses in both patients and the medical staff. It is observed that the equipment after being connected to the grid, is pre-selected to work in continuous fluoroscopy and no additional filtration, producing higher doses of radiation. For specific applications, changes in protocols should be undertaken according to medical indication. This work used a fluoroscopy equipment Shimadzu Active Opescope two radiation monitoring equipment, brand Radcal, models 9010 and 9015, two ionization chambers, of 60 cc and 180 cc and a low contrast phantom and a catheter, information that simulate the human body. Incidences were performed by changing the conditions of exposure as frame rates (fps - frames per second) and additional filtration. For each composition parameters was generated and filed an image, with the extent of their respective doses. These images were evaluated by radiologists. In more extreme cases we obtained a reduction of a factor 25 in occupational exposure (medical personnel) using the pulsed with the greatest 2 fps additional filter (0.3 mm Cu) compared to continuous system without any additional filtration. In medical exposure (of patients), decreased by a factor 39, the same conditions described above. With these arguments it is justified the optimization and standardization of the equipment used in fluoroscopy, which besides providing a dose reduction the patient and the medical personnel, increases the life of the X-ray tube while maintaining the quality of medical diagnosis. (author)

Theoretical analysis about early detection of hepatocellular carcinoma by medical imaging procedure

Energy Technology Data Exchange (ETDEWEB)

Odano, Ikuo; Hinata, Hiroshi; Hara, Keiji; Sakai, Kunio [Niigata Univ. (Japan). School of Medicine

1983-04-01

It is well-known that patients with chronic hepatitis and liver cirrhosis are frequently accompanied by hepatocellular carcinoma (hepatoma). They are called high risk group for hepatoma. In order to detect a small hepatoma, it is reasonable for us to perform screening examinations on these high risk group patients. Optimal screening interval, however, has not been established. In this report, a theoretical analysis was made to estimate optimal screening interval by imaging procedure such as ultrasonography, x-ray computed tomography and scintigraphy. By the analysis of eight cases, mean doubling time of hepatoma was estimated about four months (73 - 143 days). If we want to detect a hepatoma not greater than 3.0cm in diameter, medical screening procedure combining ultrasonography and scintigraphy should be performed once per about nine months.

Direct versus indirect revascularization procedures for moyamoya disease: a comparative effectiveness study.

Science.gov (United States)

Macyszyn, Luke; Attiah, Mark; Ma, Tracy S; Ali, Zarina; Faught, Ryan; Hossain, Alisha; Man, Karen; Patel, Hiren; Sobota, Rosanna; Zager, Eric L; Stein, Sherman C

2017-05-01

OBJECTIVE Moyamoya disease (MMD) is a chronic cerebrovascular disease that can lead to devastating neurological outcomes. Surgical intervention is the definitive treatment, with direct, indirect, and combined revascularization procedures currently employed by surgeons. The optimal surgical approach, however, remains unclear. In this decision analysis, the authors compared the effectiveness of revascularization procedures in both adult and pediatric patients with MMD. METHODS A comprehensive literature search was performed for studies of MMD. Using complication and success rates from the literature, the authors constructed a decision analysis model for treatment using a direct and indirect revascularization technique. Utility values for the various outcomes and complications were extracted from the literature examining preferences in similar clinical conditions. Sensitivity analysis was performed. RESULTS A structured literature search yielded 33 studies involving 4197 cases. Cases were divided into adult and pediatric populations. These were further subdivided into 3 different treatment groups: indirect, direct, and combined revascularization procedures. In the pediatric population at 5- and 10-year follow-up, there was no significant difference between indirect and combination procedures, but both were superior to direct revascularization. In adults at 4-year follow-up, indirect was superior to direct revascularization. CONCLUSIONS In the absence of factors that dictate a specific approach, the present decision analysis suggests that direct revascularization procedures are inferior in terms of quality-adjusted life years in both adults at 4 years and children at 5 and 10 years postoperatively, respectively. These findings were statistically significant (p indirect and combination procedures may offer optimal results at long-term follow-up.

Optimal sensor configuration for complex systems

DEFF Research Database (Denmark)

Sadegh, Payman; Spall, J. C.

1998-01-01

. The procedure for sensor configuration is based on the simultaneous perturbation stochastic approximation (SPSA) algorithm. SPSA avoids the need for detailed modeling of the sensor response by simply relying on the observed responses obtained by limited experimentation with test sensor configurations. We......The paper considers the problem of sensor configuration for complex systems with the aim of maximizing the useful information about certain quantities of interest. Our approach involves: 1) definition of an appropriate optimality criterion or performance measure; and 2) description of an efficient...... and practical algorithm for achieving the optimality objective. The criterion for optimal sensor configuration is based on maximizing the overall sensor response while minimizing the correlation among the sensor outputs, so as to minimize the redundant information being provided by the multiple sensors...

Optimization of chemical regeneration procedures of spent activated carbon

Directory of Open Access Journals (Sweden)

Naser Ghasemzadeh

2017-01-01

Full Text Available The chemical regeneration of granular activated carbon exhausted in a petrochemical wastewater unit was investigated. Gas chromatography and energy-dispersive X-ray spectroscopy demonstrated that spent activated carbon carries large types of organic and inorganic materials. Diverse chemical solvents were adopted in comparison with traditional chemical solvents and regeneration efficiency was investigated for each approach. The optimum procedure and optimum condition including temperature, concentration of solvent, and time were determined. The regenerated activated carbon was used in the adsorption of methylene blue (MB in order to find its regeneration efficiency. The regeneration efficiency can be identified by comparing of amount of MB absorbed by the fresh and regenerated activated carbon. The best acidic regenerator was hydrofluoric acid. The higher the temperature causes the faster desorption rate and consequently, the higher regeneration efficiency. The regeneration efficiency increased by means of an increase in the time of regeneration and solvent concentration, but there was an optimum time and solvent concentration for regeneration. The optimum temperature, solvent concentration and regeneration time obtained was 80 ⁰C, 3 molar and 3 hours, respectively.

Optimizing Perioperative Nutrition in Pediatric Populations.

Science.gov (United States)

Canada, Nicki L; Mullins, Lucille; Pearo, Brittany; Spoede, Elizabeth

2016-02-01

Nutrition status prior to surgery and nutrition rehabilitation after surgery can affect the morbidity and mortality of pediatric patients. A comprehensive approach to nutrition in pediatric surgical patients is important and includes preoperative assessment, perioperative nutrition considerations, and postoperative recovery. A thorough nutrition assessment to identify patients who are at nutrition risk prior to surgery is important so that the nutrition status can be optimized prior to the procedure to minimize suboptimal outcomes. Preoperative malnutrition is associated with increased complications and mean hospital days following surgery. Enteral and parenteral nutrition can be used in cases where food intake is inadequate to maintain and possibly improve nutrition status, especially in the 7-10 days prior to surgery. In the perioperative period, fasting should be limited to restricting solid foods and non-human milk 6 hours prior to the procedure and allowing clear liquids until 2 hours prior to the procedure. Postoperatively, early feeding has been shown to resolve postoperative ileus earlier, decrease infection rates, promote wound healing, and reduce length of hospital stay. If nutrition cannot be provided orally, then nutrition through either enteral or parenteral means should be initiated within 24-48 hours of surgery. Practitioners should identify those patients who are at the highest nutrition risk for postsurgical complications and provide guidance for optimal nutrition during the perioperative and postoperative period. © 2015 American Society for Parenteral and Enteral Nutrition.

The influence of different measurement structures on NRTA test procedures

International Nuclear Information System (INIS)

Beedgen, R.

1986-01-01

The development of sequential statistical test procedures in the area of near real time material accountancy (NRTA) mostly assumed a fixed measurement model of a given model facility. In this paper different measurement models (dispersion matrices) for a sequence of balance periods are studied. They are used to compare the detection probabilities of three different sequential test procedures for losses of material. It is shown how different plant models have an influence on the sensitivity of specified tests. Great importance for that analysis have the optimal loss patterns in each measurement situation

Loading pattern optimization using ant colony algorithm

International Nuclear Information System (INIS)

Hoareau, Fabrice

2008-01-01

Electricite de France (EDF) operates 58 nuclear power plants (NPP), of the Pressurized Water Reactor type. The loading pattern optimization of these NPP is currently done by EDF expert engineers. Within this framework, EDF R and D has developed automatic optimization tools that assist the experts. LOOP is an industrial tool, developed by EDF R and D and based on a simulated annealing algorithm. In order to improve the results of such automatic tools, new optimization methods have to be tested. Ant Colony Optimization (ACO) algorithms are recent methods that have given very good results on combinatorial optimization problems. In order to evaluate the performance of such methods on loading pattern optimization, direct comparisons between LOOP and a mock-up based on the Max-Min Ant System algorithm (a particular variant of ACO algorithms) were made on realistic test-cases. It is shown that the results obtained by the ACO mock-up are very similar to those of LOOP. Future research will consist in improving these encouraging results by using parallelization and by hybridizing the ACO algorithm with local search procedures. (author)

Procedural virtual reality simulation in minimally invasive surgery.

Science.gov (United States)

Våpenstad, Cecilie; Buzink, Sonja N

2013-02-01

Simulation of procedural tasks has the potential to bridge the gap between basic skills training outside the operating room (OR) and performance of complex surgical tasks in the OR. This paper provides an overview of procedural virtual reality (VR) simulation currently available on the market and presented in scientific literature for laparoscopy (LS), flexible gastrointestinal endoscopy (FGE), and endovascular surgery (EVS). An online survey was sent to companies and research groups selling or developing procedural VR simulators, and a systematic search was done for scientific publications presenting or applying VR simulators to train or assess procedural skills in the PUBMED and SCOPUS databases. The results of five simulator companies were included in the survey. In the literature review, 116 articles were analyzed (45 on LS, 43 on FGE, 28 on EVS), presenting a total of 23 simulator systems. The companies stated to altogether offer 78 procedural tasks (33 for LS, 12 for FGE, 33 for EVS), of which 17 also were found in the literature review. Although study type and used outcomes vary between the three different fields, approximately 90 % of the studies presented in the retrieved publications for LS found convincing evidence to confirm the validity or added value of procedural VR simulation. This was the case in approximately 75 % for FGE and EVS. Procedural training using VR simulators has been found to improve clinical performance. There is nevertheless a large amount of simulated procedural tasks that have not been validated. Future research should focus on the optimal use of procedural simulators in the most effective training setups and further investigate the benefits of procedural VR simulation to improve clinical outcome.

A Framework for the Optimization of Discrete-Event Simulation Models

Science.gov (United States)

Joshi, B. D.; Unal, R.; White, N. H.; Morris, W. D.

1996-01-01

With the growing use of computer modeling and simulation, in all aspects of engineering, the scope of traditional optimization has to be extended to include simulation models. Some unique aspects have to be addressed while optimizing via stochastic simulation models. The optimization procedure has to explicitly account for the randomness inherent in the stochastic measures predicted by the model. This paper outlines a general purpose framework for optimization of terminating discrete-event simulation models. The methodology combines a chance constraint approach for problem formulation, together with standard statistical estimation and analyses techniques. The applicability of the optimization framework is illustrated by minimizing the operation and support resources of a launch vehicle, through a simulation model.

Reliability- and performance-based robust design optimization of MEMS structures considering technological uncertainties

Science.gov (United States)

Martowicz, Adam; Uhl, Tadeusz

2012-10-01

The paper discusses the applicability of a reliability- and performance-based multi-criteria robust design optimization technique for micro-electromechanical systems, considering their technological uncertainties. Nowadays, micro-devices are commonly applied systems, especially in the automotive industry, taking advantage of utilizing both the mechanical structure and electronic control circuit on one board. Their frequent use motivates the elaboration of virtual prototyping tools that can be applied in design optimization with the introduction of technological uncertainties and reliability. The authors present a procedure for the optimization of micro-devices, which is based on the theory of reliability-based robust design optimization. This takes into consideration the performance of a micro-device and its reliability assessed by means of uncertainty analysis. The procedure assumes that, for each checked design configuration, the assessment of uncertainty propagation is performed with the meta-modeling technique. The described procedure is illustrated with an example of the optimization carried out for a finite element model of a micro-mirror. The multi-physics approach allowed the introduction of several physical phenomena to correctly model the electrostatic actuation and the squeezing effect present between electrodes. The optimization was preceded by sensitivity analysis to establish the design and uncertain domains. The genetic algorithms fulfilled the defined optimization task effectively. The best discovered individuals are characterized by a minimized value of the multi-criteria objective function, simultaneously satisfying the constraint on material strength. The restriction of the maximum equivalent stresses was introduced with the conditionally formulated objective function with a penalty component. The yielded results were successfully verified with a global uniform search through the input design domain.

Optimization of wind farm micro-siting for complex terrain using greedy algorithm

International Nuclear Information System (INIS)

Song, M.X.; Chen, K.; He, Z.Y.; Zhang, X.

2014-01-01

An optimization approach based on greedy algorithm for optimization of wind farm micro-siting is presented. The key of optimizing wind farm micro-siting is the fast and accurate evaluation of the wake flow interactions of wind turbines. The virtual particle model is employed for wake flow simulation of wind turbines, which makes the present method applicable for non-uniform flow fields on complex terrains. In previous bionic optimization method, within each step of the optimization process, only the power output of the turbine that is being located or relocated is considered. To aim at the overall power output of the wind farm comprehensively, a dependent region technique is introduced to improve the estimation of power output during the optimization procedure. With the technique, the wake flow influences can be reduced more efficiently during the optimization procedure. During the optimization process, the turbine that is being added will avoid being affected other turbines, and avoid affecting other turbine in the meantime. The results from the numerical calculations demonstrate that the present method is effective for wind farm micro-siting on complex terrain, and it produces better solutions in less time than the previous bionic method. - Highlights: • Greedy algorithm is applied to wind farm micro-siting problem. • The present method is effective for optimization on complex terrains. • Dependent region is suggested to improve the evaluation of wake influences. • The present method has better performance than the bionic method

A convenient procedure for magnetic field homogeneity evaluation

International Nuclear Information System (INIS)

Teles, J; Garrido, C E; Tannus, A

2004-01-01

In many areas of research that utilize magnetic fields in their studies, it is important to obtain fields with a spatial distribution as homogeneous as possible. A procedure usually utilized to evaluate and to optimize field homogeneity is the expansion of the measured field in spherical harmonic components. In addition to the methods proposed in the literature, we present a more convenient procedure for evaluation of field homogeneity inside a spherical volume. The procedure uses the orthogonality property of the spherical harmonics to find the field variance. It is shown that the total field variance is equal to the sum of the individual variances of each field component in the spherical harmonic expansion. Besides the advantages of the linear behaviour of the individual variances, there is the fact that the field variance and standard deviation are the best parameters to achieve global homogeneity field information

Design and optimization for strength and integrity of tidal turbine rotor blades

International Nuclear Information System (INIS)

Liu, Pengfei; Veitch, Brian

2012-01-01

Tidal turbine rotor blade fractures and failures have resulted in substantial damage and hence cost of repair and recovery. The present work presents a rotor blade design and optimization method to address the blade structural strength design problem. The generic procedure is applicable to both turbine rotors and propellers. The optimization method seeks an optimum blade thickness distribution across the span with a prescribed constant safety factor for all the blade sections. This optimization procedure serves two purposes: while maintaining the required structural strength and integrity for an ultimate inflow speed, it aims to reduce the material to a minimum and to maintain power generation efficiency or improve the hydrodynamic efficiency. The value of the chosen minimum safety factor depends on the actual working conditions of the turbine in which the sectional peak loading and frequency are used: the harsher the environment, the larger the required safety factor. An engineering software tool with both hydrodynamic and structural capabilities was required to predict the instantaneous loading acting on all the blade sections, as well as the strength of a local blade section with a given blade geometry and chosen material. A time-domain, 3D unsteady panel method was then implemented based on a marine propeller software tool and used to perform the optimization. A 3-blade 20-m tidal turbine that was prototyped in parallel with the current work for the Bay of Fundy was used as an example for optimization. The optimum thickness distribution for a required safety factor at the ultimate possible inflow speed resulted in 37.6% saving in blade material. The blade thickness and distribution as a function of a maximum inflow speed of 6 m/s is also presented. The blade material used in the example was taken as nickel–aluminium–bronze (NAB) but the procedure was developed to be applicable to propeller or turbine blades of basically any material. -- Highlights: ► A

Power system optimization

International Nuclear Information System (INIS)

Bogdan, Zeljko; Cehil, Mislav

2007-01-01

Long-term gas purchase contracts usually determine delivery and payment for gas on the regular hourly basis, independently of demand side consumption. In order to use fuel gas in an economically viable way, optimization of gas distribution for covering consumption must be introduced. In this paper, a mathematical model of the electric utility system which is used for optimization of gas distribution over electric generators is presented. The utility system comprises installed capacity of 1500 MW of thermal power plants, 400 MW of combined heat and power plants, 330 MW of a nuclear power plant and 1600 MW of hydro power plants. Based on known demand curve the optimization model selects plants according to the prescribed criteria. Firstly it engages run-of-river hydro plants, then the public cogeneration plants, the nuclear plant and thermal power plants. Storage hydro plants are used for covering peak load consumption. In case of shortage of installed capacity, the cross-border purchase is allowed. Usage of dual fuel equipment (gas-oil), which is available in some thermal plants, is also controlled by the optimization procedure. It is shown that by using such a model it is possible to properly plan the amount of fuel gas which will be contracted. The contracted amount can easily be distributed over generators efficiently and without losses (no breaks in delivery). The model helps in optimizing of fuel gas-oil ratio for plants with combined burners and enables planning of power plants overhauls over a year in a viable and efficient way. (author)

3-D brain image registration using optimal morphological processing

International Nuclear Information System (INIS)

Loncaric, S.; Dhawan, A.P.

1994-01-01

The three-dimensional (3-D) registration of Magnetic Resonance (MR) and Positron Emission Tomographic (PET) images of the brain is important for analysis of the human brain and its diseases. A procedure for optimization of (3-D) morphological structuring elements, based on a genetic algorithm, is presented in the paper. The registration of the MR and PET images is done by means of a registration procedure in two major phases. In the first phase, the Iterative Principal Axis Transform (IPAR) is used for initial registration. In the second phase, the optimal shape description method based on the Morphological Signature Transform (MST) is used for final registration. The morphological processing is used to improve the accuracy of the basic IPAR method. The brain ventricle is used as a landmark for MST registration. A near-optimal structuring element obtained by means of a genetic algorithm is used in MST to describe the shape of the ventricle. The method has been tested on the set of brain images demonstrating the feasibility of approach. (author). 11 refs., 3 figs

Optimization for PET imaging based on phantom study and NECdensity

International Nuclear Information System (INIS)

Daisaki, Hiromitsu; Shimada, Naoki; Shinohara, Hiroyuki

2012-01-01

In consideration of the requirement for global standardization and quality control of PET imaging, the present studies gave an outline of phantom study to decide both scan and reconstruction parameters based on FDG-PET/CT procedure guideline in Japan, and optimization of scan duration based on NEC density was performed continuously. In the phantom study, scan and reconstruction parameters were decided by visual assessment and physical indexes (N 10mm , NEC phantom , Q H,10mm /N 10mm ) to visualize hot spot of 10 mm diameter with standardized uptake value (SUV)=4 explicitly. Simultaneously, Recovery Coefficient (RC) was evaluated to recognize that PET images had enough quantifiably. Scan durations were optimized by Body Mass Index (BMI) based on retrospective analysis of NEC density . Correlation between visual score in clinical FDG-PET images and NEC density fell after the optimization of scan duration. Both Inter-institution and inter-patient variability were decreased by performing the phantom study based on the procedure guideline and the optimization of scan duration based on NEC density which seem finally useful to practice highly precise examination and promote high-quality controlled study. (author)

Optimal allocation of International Atomic Energy Agency inspection resources

International Nuclear Information System (INIS)

Markin, J.T.

1987-12-01

The Safeguards Department of the International Atomic Energy Agency (IAEA) conducts inspections to assure the peaceful use of a state's nuclear materials and facilities. Because of limited resources for conducting inspections, the careful disposition of inspection effort among these facilities is essential if the IAEA is to attain its safeguards goals. This report describes an optimization procedure for assigning an inspection effort to maximize attainment of IAEA goals. The procedure does not require quantitative estimates of safeguards effectiveness, material value, or facility importance. Instead, the optimization is based on qualitative, relative prioritizations of inspection activities and materials to be safeguarded. This allocation framework is applicable to an arbitrary group of facilities such as a state's fuel cycle, the facilities inspected by an operations division, or all of the facilities inspected by the IAEA

Plug pattern optimization for gamma knife radiosurgery treatment planning

International Nuclear Information System (INIS)

Zhang Pengpeng; Wu, Jackie; Dean, David; Xing Lei; Xue Jinyue; Maciunas, Robert; Sibata, Claudio

2003-01-01

Purpose: To develop a novel dose optimization algorithm for improving the sparing of critical structures during gamma knife radiosurgery by shaping the plug pattern of each individual shot. Method and Materials: We first use a geometric information (medial axis) aided guided evolutionary simulated annealing (GESA) optimization algorithm to determine the number of shots and isocenter location, size, and weight of each shot. Then we create a plug quality score system that checks the dose contribution to the volume of interest by each plug in the treatment plan. A positive score implies that the corresponding source could be open to improve tumor coverage, whereas a negative score means the source could be blocked for the purpose of sparing normal and critical structures. The plug pattern is then optimized via the GESA algorithm that is integrated with this score system. Weight and position of each shot are also tuned in this procedure. Results: An acoustic tumor case is used to evaluate our algorithm. Compared to the treatment plan generated without plug patterns, adding an optimized plug pattern into the treatment planning process boosts tumor coverage index from 95.1% to 97.2%, reduces RTOG conformity index from 1.279 to 1.167, lowers Paddick's index from 1.34 to 1.20, and trims the critical structure receiving more than 30% maximum dose from 16 mm 3 to 6 mm 3 . Conclusions: Automated GESA-based plug pattern optimization of gamma knife radiosurgery frees the treatment planning team from the manual forward planning procedure and provides an optimal treatment plan

Surgical specialty procedures in rural surgery practices: implications for rural surgery training.

Science.gov (United States)

Sticca, Robert P; Mullin, Brady C; Harris, Joel D; Hosford, Clint C

2012-12-01

Specialty procedures constitute one eighth of rural surgery practice. Currently, general surgeons intending to practice in rural hospitals may not get adequate training for specialty procedures, which they will be expected to perform. Better definition of these procedures will help guide rural surgery training. Current Procedural Terminology codes for all surgical procedures for 81% of North Dakota and South Dakota rural surgeons were entered into the Dakota Database for Rural Surgery. Specialty procedures were analyzed and compared with the Surgical Council on Resident Education curriculum to determine whether general surgery training is adequate preparation for rural surgery practice. The Dakota Database for Rural Surgery included 46,052 procedures, of which 5,666 (12.3%) were specialty procedures. Highest volume specialty categories included vascular, obstetrics and gynecology, orthopedics, cardiothoracic, urology, and otolaryngology. Common procedures in cardiothoracic and vascular surgery are taught in general surgical residency, while common procedures in obstetrics and gynecology, orthopedics, urology, and otolaryngology are usually not taught in general surgery training. Optimal training for rural surgery practice should include experience in specialty procedures in obstetrics and gynecology, orthopedics, urology, and otolaryngology. Copyright © 2012 Elsevier Inc. All rights reserved.

Cost optimal levels for energy performance requirements

DEFF Research Database (Denmark)

Thomsen, Kirsten Engelund; Aggerholm, Søren; Kluttig-Erhorn, Heike

This report summarises the work done within the Concerted Action EPBD from December 2010 to April 2011 in order to feed into the European Commission's proposal for a common European procedure for a Cost-Optimal methodology under the Directive on the Energy Performance of Buildings (recast) 2010/3...

A method optimization study for atomic absorption ...

African Journals Online (AJOL)

A sensitive, reliable and relative fast method has been developed for the determination of total zinc in insulin by atomic absorption spectrophotometer. This designed study was used to optimize the procedures for the existing methods. Spectrograms of both standard and sample solutions of zinc were recorded by measuring ...

Optimized data evaluation for k0-based NAA

International Nuclear Information System (INIS)

Van Sluijs, R.; Bossus, D.A.W.

1999-01-01

k 0 -NAA allows the simultaneous analysis of up-to 67 elements. The k 0 method is based on calculations using a special library instead of measuring standards. For an efficient use of the method, the calculations and resulting raw data require optimized evaluation procedures. In this paper two efficient procedures for nuclide identification and gamma interference correction are outlined. For a fast computation of the source-detector efficiency and coincidence correction factors the matrix interpolation technique is introduced. (author)

Physically based modelling and optimal operation for product drying during post-harvest processing.

NARCIS (Netherlands)

Boxtel, van A.J.B.; Lukasse, L.; Farkas, I.; Rendik, Z.

1996-01-01

The development of new procedures for crop production and post-harvest processing requires models. Models based on physical backgrounds are most useful for this purpose because of their extrapolation potential. An optimal procedure is developed for alfalfa drying using a physical model. The model

Optimization of large-scale industrial systems : an emerging method

Energy Technology Data Exchange (ETDEWEB)

Hammache, A.; Aube, F.; Benali, M.; Cantave, R. [Natural Resources Canada, Varennes, PQ (Canada). CANMET Energy Technology Centre

2006-07-01

This paper reviewed optimization methods of large-scale industrial production systems and presented a novel systematic multi-objective and multi-scale optimization methodology. The methodology was based on a combined local optimality search with global optimality determination, and advanced system decomposition and constraint handling. The proposed method focused on the simultaneous optimization of the energy, economy and ecology aspects of industrial systems (E{sup 3}-ISO). The aim of the methodology was to provide guidelines for decision-making strategies. The approach was based on evolutionary algorithms (EA) with specifications including hybridization of global optimality determination with a local optimality search; a self-adaptive algorithm to account for the dynamic changes of operating parameters and design variables occurring during the optimization process; interactive optimization; advanced constraint handling and decomposition strategy; and object-oriented programming and parallelization techniques. Flowcharts of the working principles of the basic EA were presented. It was concluded that the EA uses a novel decomposition and constraint handling technique to enhance the Pareto solution search procedure for multi-objective problems. 6 refs., 9 figs.

Real-Time Optimization for Economic Model Predictive Control

DEFF Research Database (Denmark)

Sokoler, Leo Emil; Edlund, Kristian; Frison, Gianluca

2012-01-01

In this paper, we develop an efficient homogeneous and self-dual interior-point method for the linear programs arising in economic model predictive control. To exploit structure in the optimization problems, the algorithm employs a highly specialized Riccati iteration procedure. Simulations show...

Global Optimization for Bus Line Timetable Setting Problem

Directory of Open Access Journals (Sweden)

Qun Chen

2014-01-01

Full Text Available This paper defines bus timetables setting problem during each time period divided in terms of passenger flow intensity; it is supposed that passengers evenly arrive and bus runs are set evenly; the problem is to determine bus runs assignment in each time period to minimize the total waiting time of passengers on platforms if the number of the total runs is known. For such a multistage decision problem, this paper designed a dynamic programming algorithm to solve it. Global optimization procedures using dynamic programming are developed. A numerical example about bus runs assignment optimization of a single line is given to demonstrate the efficiency of the proposed methodology, showing that optimizing buses’ departure time using dynamic programming can save computational time and find the global optimal solution.

Optimization of Approximate Inhibitory Rules Relative to Number of Misclassifications

KAUST Repository

Alsolami, Fawaz

2013-10-04

In this work, we consider so-called nonredundant inhibitory rules, containing an expression “attribute:F value” on the right- hand side, for which the number of misclassifications is at most a threshold γ. We study a dynamic programming approach for description of the considered set of rules. This approach allows also the optimization of nonredundant inhibitory rules relative to the length and coverage. The aim of this paper is to investigate an additional possibility of optimization relative to the number of misclassifications. The results of experiments with decision tables from the UCI Machine Learning Repository show this additional optimization achieves a fewer misclassifications. Thus, the proposed optimization procedure is promising.

Optimal design of an automotive magnetorheological brake considering geometric dimensions and zero-field friction heat

International Nuclear Information System (INIS)

Nguyen, Q H; Choi, S B

2010-01-01

This paper presents an optimal design of a magnetorheological (MR) brake for a middle-sized passenger car which can replace a conventional hydraulic disc-type brake. In the optimization, the required braking torque, the temperature due to zero-field friction of MR fluid, the mass of the brake system and all significant geometric dimensions are considered. After describing the configuration, the braking torque of the proposed MR brake is derived on the basis of the field-dependent Bingham and Herschel–Bulkley rheological model of the MR fluid. The optimal design of the MR brake is then analyzed taking into account available space, mass, braking torque and steady heat generated by zero-field friction torque of the MR brake. The optimization procedure based on the finite element analysis integrated with an optimization tool is proposed to obtain optimal geometric dimensions of the MR brake. Based on the proposed procedure, optimal solutions of single and multiple disc-type MR brakes featuring different types of MR fluid are achieved. From the results, the most effective MR brake for the middle-sized passenger car is identified and some discussions on the performance improvement of the optimized MR brake are described

Investigations into the Optimization of Multi-Source Strength Brachytherapy Treatment Procedures

International Nuclear Information System (INIS)

Henderson, D. L.; Yoo, S.; Thomadsen, B.R.

2002-01-01

The goal of this project is to investigate the use of multi-strength and multi-specie radioactive sources in permanent prostate implant brachytherapy. In order to fulfill the requirement for an optimal dose distribution, the prescribed dose should be delivered to the target in a nearly uniform dose distribution while simultaneously sparing sensitive structures. The treatment plan should use a small number of needles and sources while satisfying the treatment requirements. The hypothesis for the use of multi-strength and/or multi-specie sources is that a better treatment plan using fewer sources and needles could be obtained than by treatment plans using single-strength sources could reduce the overall number of sources used for treatment. We employ a recently developed greedy algorithm based on the adjoint concept as the optimization search engine. The algorithm utilizes and ''adjoint ratio'', which provides a means of ranking source positions, as the pseudo-objective function. It ha s been shown that the greedy algorithm can solve the optimization problem efficiently and arrives at a clinically acceptable solution in less than 10 seconds. Our study was inclusive, that is there was no combination of sources that clearly stood out from the others and could therefore be considered the preferred set of sources for treatment planning. Source strengths of 0.2 mCi (low), 0.4 mCi (medium), and 0.6 mCi (high) of 125 I in four different combinations were used for the multi-strength source study. The combination of high- and medium-strength sources achieved a more uniform target dose distribution due to few source implants whereas the combination of low-and medium-strength sources achieved better sparing of sensitive tissues including that of the single-strength 0.4 mCi base case. 125 I at 0.4 mCi and 192 Ir at 0.12 mCi and 0.25 mCi source strengths were used for the multi-specie source study. This study also proved inconclusive , Treatment plans using a combination of two 0

Design of AC-DC Grid Connected Converter using Multi-Objective Optimization

Directory of Open Access Journals (Sweden)

Piasecki Szymon

2014-05-01

Full Text Available Power electronic circuits, in particular AC-DC converters are complex systems, many different parameters and objectives have to be taken into account during the design process. Implementation of Multi-Objective Optimization (MOO seems to be attractive idea, which used as designer supporting tool gives possibility for better analysis of the designed system. This paper presents a short introduction to the MOO applied in the field of power electronics. Short introduction to the subject is given in section I. Then, optimization process and its elements are briefly described in section II. Design procedure with proposed optimization parameters and performance indices for AC-DC Grid Connected Converter (GCC interfacing distributed systems is introduced in section III. Some preliminary optimization results, achieved on the basis of analytical and simulation study, are shown at each stage of designing process. Described optimization parameters and performance indices are part of developed global optimization method dedicated for ACDC GCC introduced in section IV. Described optimization method is under development and only short introduction and basic assumptions are presented. In section V laboratory prototype of high efficient and compact 14 kVA AC-DC converter is introduced. The converter is elaborated based on performed designing and optimization procedure with the use of silicon carbide (SiC power semiconductors. Finally, the paper is summarized and concluded in section VI. In presented work theoretical research are conducted in parallel with laboratory prototyping e.g. all theoretical ideas are verified in laboratory using modern DSP microcontrollers and prototypes of the ACDC GCC.

Topology optimization under stochastic stiffness

Science.gov (United States)

Asadpoure, Alireza

Topology optimization is a systematic computational tool for optimizing the layout of materials within a domain for engineering design problems. It allows variation of structural boundaries and connectivities. This freedom in the design space often enables discovery of new, high performance designs. However, solutions obtained by performing the optimization in a deterministic setting may be impractical or suboptimal when considering real-world engineering conditions with inherent variabilities including (for example) variabilities in fabrication processes and operating conditions. The aim of this work is to provide a computational methodology for topology optimization in the presence of uncertainties associated with structural stiffness, such as uncertain material properties and/or structural geometry. Existing methods for topology optimization under deterministic conditions are first reviewed. Modifications are then proposed to improve the numerical performance of the so-called Heaviside Projection Method (HPM) in continuum domains. Next, two approaches, perturbation and Polynomial Chaos Expansion (PCE), are proposed to account for uncertainties in the optimization procedure. These approaches are intrusive, allowing tight and efficient coupling of the uncertainty quantification with the optimization sensitivity analysis. The work herein develops a robust topology optimization framework aimed at reducing the sensitivity of optimized solutions to uncertainties. The perturbation-based approach combines deterministic topology optimization with a perturbation method for the quantification of uncertainties. The use of perturbation transforms the problem of topology optimization under uncertainty to an augmented deterministic topology optimization problem. The PCE approach combines the spectral stochastic approach for the representation and propagation of uncertainties with an existing deterministic topology optimization technique. The resulting compact representations

On the optimal design of glass grid shells with planar quadrilateral elements

DEFF Research Database (Denmark)

Sassone, Mario; Pugnale, Alberto

2010-01-01

specific geometric rules in the grid generation phase but, when the architectural shape is already defined at the conceptual stage, an optimization procedure can yield to suitable configurations. A Relaxation method based on nodal planarity errors and an evolutionary population based Genetic Algorithm have...... been applied to set of benchmarks, in order to tune parameters and to obtain general information about the solution. the problem and their efficiency compared. The Relaxation method in general shows better efficiency in reaching optimal solutions, as an effect of the regularity of the target function......This paper presents an optimization procedure for the solution of the planarity problem, a requirement of grid shells with four or more sides faces that need of having four adjacent nodes laying on a plane in order to use plane glass slabs as cladding elements. It can be satisfied by applying...

Robust Portfolio Optimization Using Pseudodistances

Science.gov (United States)

2015-01-01

The presence of outliers in financial asset returns is a frequently occurring phenomenon which may lead to unreliable mean-variance optimized portfolios. This fact is due to the unbounded influence that outliers can have on the mean returns and covariance estimators that are inputs in the optimization procedure. In this paper we present robust estimators of mean and covariance matrix obtained by minimizing an empirical version of a pseudodistance between the assumed model and the true model underlying the data. We prove and discuss theoretical properties of these estimators, such as affine equivariance, B-robustness, asymptotic normality and asymptotic relative efficiency. These estimators can be easily used in place of the classical estimators, thereby providing robust optimized portfolios. A Monte Carlo simulation study and applications to real data show the advantages of the proposed approach. We study both in-sample and out-of-sample performance of the proposed robust portfolios comparing them with some other portfolios known in literature. PMID:26468948

Robust Portfolio Optimization Using Pseudodistances.

Science.gov (United States)

Toma, Aida; Leoni-Aubin, Samuela

2015-01-01

The presence of outliers in financial asset returns is a frequently occurring phenomenon which may lead to unreliable mean-variance optimized portfolios. This fact is due to the unbounded influence that outliers can have on the mean returns and covariance estimators that are inputs in the optimization procedure. In this paper we present robust estimators of mean and covariance matrix obtained by minimizing an empirical version of a pseudodistance between the assumed model and the true model underlying the data. We prove and discuss theoretical properties of these estimators, such as affine equivariance, B-robustness, asymptotic normality and asymptotic relative efficiency. These estimators can be easily used in place of the classical estimators, thereby providing robust optimized portfolios. A Monte Carlo simulation study and applications to real data show the advantages of the proposed approach. We study both in-sample and out-of-sample performance of the proposed robust portfolios comparing them with some other portfolios known in literature.

Optimization of technological procedure for amygdalin isolation from plum seeds (Pruni domesticae semen)

Science.gov (United States)

Savic, Ivan M.; Nikolic, Vesna D.; Savic-Gajic, Ivana M.; Nikolic, Ljubisa B.; Ibric, Svetlana R.; Gajic, Dragoljub G.

2015-01-01

The process of amygdalin extraction from plum seeds was optimized using central composite design (CCD) and multilayer perceptron (MLP). The effect of time, ethanol concentration, solid-to-liquid ratio, and temperature on the amygdalin content in the extracts was estimated using both mathematical models. The MLP 4-3-1 with exponential function in hidden layer and linear function in output layer was used for describing the extraction process. MLP model was more superior compared with CCD model due to better prediction ability. According to MLP model, the suggested optimal conditions are: time of 120 min, 100% (v/v) ethanol, solid-to liquid ratio of 1:25 (m/v) and temperature of 34.4°C. The predicted value of amygdalin content in the dried extract (25.42 g per 100 g) at these conditions was experimentally confirmed (25.30 g per 100 g of dried extract). Amygdalin (>90%) was isolated from the complex extraction mixture and structurally characterized by FT-IR, UV, and MS methods. PMID:25972881

Heuristic query optimization for query multiple table and multiple clausa on mobile finance application

Science.gov (United States)

Indrayana, I. N. E.; P, N. M. Wirasyanti D.; Sudiartha, I. KG

2018-01-01

Mobile application allow many users to access data from the application without being limited to space, space and time. Over time the data population of this application will increase. Data access time will cause problems if the data record has reached tens of thousands to millions of records.The objective of this research is to maintain the performance of data execution for large data records. One effort to maintain data access time performance is to apply query optimization method. The optimization used in this research is query heuristic optimization method. The built application is a mobile-based financial application using MySQL database with stored procedure therein. This application is used by more than one business entity in one database, thus enabling rapid data growth. In this stored procedure there is an optimized query using heuristic method. Query optimization is performed on a “Select” query that involves more than one table with multiple clausa. Evaluation is done by calculating the average access time using optimized and unoptimized queries. Access time calculation is also performed on the increase of population data in the database. The evaluation results shown the time of data execution with query heuristic optimization relatively faster than data execution time without using query optimization.

Portal monitor evaluation and test procedure

International Nuclear Information System (INIS)

Johnson, L.O.; Gupta, V.P.; Stevenson, R.L.; Rich, B.L.

1983-10-01

The purpose was to develop techniques and procedures to allow users to measure performance and sensitivity of portal monitors. Additionally, a methodology was developed to assist users in optimizing monitor performance. The two monitors tested utilized thin-window gas-flow proportional counters sensitive to beta and gamma radiation. Various tests were performed: a) background count rate and the statistical variability, b) detector efficiency at different distances, c) moving source sensitivity for various size sources and speeds, and d) false alarm rates at different background levels. A model was developed for the moving source measurements to compare the experimental data with measured results, and to test whether it is possible to adequately model the behavior of a portal monitor's response to a moving source. The model results were compared with the actual test results. A procedure for testing portal monitors is also given. 1 reference, 9 figures, 8 tables

Contribution to the optimization of worker's radiological protection in a uranium mine

International Nuclear Information System (INIS)

Lombard, J.; Oudiz, A.; Zettwoog, P.

1984-04-01

This report presents the results of an optimization study dealing with radiological protection in a uranium mine. The modelization of alpha contamination associated with short-lived radon daughter in a mine branch allows the comparison of various protection strategies by a cost-effectiveness analysis in view of determining the ''optimal'' protection strategy. The study points out the interest of the optimization procedure as a decision-aiding tool within the framework of radiological protection [fr

A Novel Structure and Design Optimization of Compact Spline-Parameterized UWB Slot Antenna

Directory of Open Access Journals (Sweden)

Koziel Slawomir

2016-12-01

Full Text Available In this paper, a novel structure of a compact UWB slot antenna and its design optimization procedure has been presented. In order to achieve a sufficient number of degrees of freedom necessary to obtain a considerable size reduction rate, the slot is parameterized using spline curves. All antenna dimensions are simultaneously adjusted using numerical optimization procedures. The fundamental bottleneck here is a high cost of the electromagnetic (EM simulation model of the structure that includes (for reliability an SMA connector. Another problem is a large number of geometry parameters (nineteen. For the sake of computational efficiency, the optimization process is therefore performed using variable-fidelity EM simulations and surrogate-assisted algorithms. The optimization process is oriented towards explicit reduction of the antenna size and leads to a compact footprint of 199 mm2 as well as acceptable matching within the entire UWB band. The simulation results are validated using physical measurements of the fabricated antenna prototype.

Optimized Placement of Wind Turbines in Large-Scale Offshore Wind Farm using Particle Swarm Optimization Algorithm

DEFF Research Database (Denmark)

Hou, Peng; Hu, Weihao; Soltani, Mohsen

2015-01-01

With the increasing size of wind farm, the impact of the wake effect on wind farm energy yields become more and more evident. The arrangement of the wind turbines’ (WT) locations will influence the capital investment and contribute to the wake losses which incur the reduction of energy production....... As a consequence, the optimized placement of the wind turbines may be done by considering the wake effect as well as the components cost within the wind farm. In this paper, a mathematical model which includes the variation of both wind direction and wake deficit is proposed. The problem is formulated by using...... Levelized Production Cost (LPC) as the objective function. The optimization procedure is performed by Particle Swarm Optimization (PSO) algorithm with the purpose of maximizing the energy yields while minimizing the total investment. The simulation results indicate that the proposed method is effective...

Diabatic potential-optimized discrete variable representation: application to photodissociation process of the CO molecule

International Nuclear Information System (INIS)

Bitencourt, Ana Carla P; Prudente, Frederico V; Vianna, Jose David M

2007-01-01

We propose a new numerically optimized discrete variable representation using eigenstates of diabatic Hamiltonians. This procedure provides an efficient method to solve non-adiabatic coupling problems since the generated basis sets take into account information on the diabatic potentials. The method is applied to the B 1 Σ + - D' 1 Σ + Rydberg-valence predissociation interaction in the CO molecule. Here we give an account of the discrete variable representation and present the procedure for the calculation of its optimized version, which we apply to obtain the total photodissociation cross sections of the CO molecule

Can occupational exposure be optimized for medical workers?

International Nuclear Information System (INIS)

Aubert, B.; Lefaure, C.

1998-01-01

Implementation of the principle of optimization (ALARA), an essential radiation protection regulations, remains very limited in the medical field, even though 80 % of workers whose exposure exceeds 50 mSv are to be found in this domain. The doses measured by legal dosimetry sometimes underestimate the real exposure of workers. It is therefore necessary to optimize the protection of occupational exposure in the medical field. This paper reviews the steps of the optimization procedure with emphasis on specificity of its application in this domain. Operating dosimetry as well as information on the residual risk due to low exposures and a better estimation of the risk/benefit factor for the patient are needed for satisfactory implementation. (author)

Optimal Design and Operation of Permanent Irrigation Systems

Science.gov (United States)

Oron, Gideon; Walker, Wynn R.

1981-01-01

Solid-set pressurized irrigation system design and operation are studied with optimization techniques to determine the minimum cost distribution system. The principle of the analysis is to divide the irrigation system into subunits in such a manner that the trade-offs among energy, piping, and equipment costs are selected at the minimum cost point. The optimization procedure involves a nonlinear, mixed integer approach capable of achieving a variety of optimal solutions leading to significant conclusions with regard to the design and operation of the system. Factors investigated include field geometry, the effect of the pressure head, consumptive use rates, a smaller flow rate in the pipe system, and outlet (sprinkler or emitter) discharge.

On simultaneous shape and orientational design for eigenfrequency optimization

DEFF Research Database (Denmark)

Pedersen, Niels Leergaard

2007-01-01

Plates with an internal hole of fixed area are designed in order to maximize the performance with respect to eigenfrequencies. The optimization is performed by simultaneous shape, material, and orientational design. The shape of the hole is designed, and the material design is the design of an or......Plates with an internal hole of fixed area are designed in order to maximize the performance with respect to eigenfrequencies. The optimization is performed by simultaneous shape, material, and orientational design. The shape of the hole is designed, and the material design is the design...... of an orthotropic material that can be considered as a fiber-net within each finite element. This fiber-net is optimally oriented in the individual elements of the finite element discretization. The optimizations are performed using the finite element method for analysis, and the optimization approach is a two......-step method. In the first step, we find the best design on the basis of a recursive optimization procedure based on optimality criteria. In the second step, mathematical programming and sensitivity analysis are applied to find the final optimized design....

Assessment of Patients Radiation Dose During Interventional Radiological Procedure in PPUKM

International Nuclear Information System (INIS)

Mohd Khalid Matori; Husaini Salleh; Muhammad Jamal Muhammad Isa

2014-01-01

Interventional Radiology (IR) is a relatively new subspecialty of radiology. It is subspecialty where minimally invasive procedures are performed under radiological guidance using X-ray. This procedure can deliver high radiation doses compared with other radiological method due to long screening time. Because of these it is important to determine radiation doses received by patients undergoing IR procedures. It is to ensure that the dose is within the range deemed to be saved. A total of 128 patients undergoing IR procedures in PPUKM between 2012 and 2013 were study retrospectively. Dose area product (DAP) meter were used to measure the integral dose for the whole procedures. Mean kerma-area products for abdomen, head, pelvis, and thorax were 243.1, 107.3, 39.05 and 45.7 Gycm 2 , respectively. This study may provide the useful information which can be use to establish baseline patient dose data for dose optimizing study and carried out a recommendation on effective method of patient dose reduction during IR procedures. A more detail results of this study are presented in this paper. (author)

TLM modeling and system identification of optimized antenna structures

Directory of Open Access Journals (Sweden)

N. Fichtner

2008-05-01

Full Text Available The transmission line matrix (TLM method in conjunction with the genetic algorithm (GA is presented for the bandwidth optimization of a low profile patch antenna. The optimization routine is supplemented by a system identification (SI procedure. By the SI the model parameters of the structure are estimated which is used for a reduction of the total TLM simulation time. The SI utilizes a new stability criterion of the physical poles for the parameter extraction.

Optimizing Your K-5 Engineering Design Challenge

Science.gov (United States)