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  • Open Access


    Analysis of the Lost Circulation Problem

    Xingquan Zhang1, Renjun Xie1, Kuan Liu2,*, Yating Li2, Yuqiang Xu2,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.6, pp. 1721-1733, 2023, DOI:10.32604/fdmp.2023.025578

    Abstract The well-known “lost circulation” problem refers to the uncontrolled flow of whole mud into a formation. In order to address the problem related to the paucity of available data, in the present study, a model is introduced for the lost-circulation risk sample profile of a drilled well. The model is built taking into account effective data (the Block L). Then, using a three-dimensional geological modeling software, relying on the variation function and sequential Gaussian simulation method, a three-dimensional block lost-circulation risk model is introduced able to provide relevant information for regional analyses. More >

  • Open Access


    Research on Mixed Logic Dynamic Modeling and Finite Control Set Model Predictive Control of Multi-Inverter Parallel System

    Xiaojuan Lu, Mengqiao Chen, Qingbo Zhang*

    Energy Engineering, Vol.120, No.3, pp. 649-664, 2023, DOI:10.32604/ee.2023.025065

    Abstract Parallel connection of multiple inverters is an important means to solve the expansion, reserve and protection of distributed power generation, such as photovoltaics. In view of the shortcomings of traditional droop control methods such as weak anti-interference ability, low tracking accuracy of inverter output voltage and serious circulation phenomenon, a finite control set model predictive control (FCS-MPC) strategy of microgrid multi-inverter parallel system based on Mixed Logical Dynamical (MLD) modeling is proposed. Firstly, the MLD modeling method is introduced logical variables, combining discrete events and continuous events to form an overall differential equation, which makes the modeling more accurate. Then… More > Graphic Abstract

    Research on Mixed Logic Dynamic Modeling and Finite Control Set Model Predictive Control of Multi-Inverter Parallel System

  • Open Access


    Characteristics of Diesel/N-Butanol Blend on a Common Rail Diesel Engine with Exhaust Gas Recirculation

    Yanfei Chen1, Jingjing He2,*, Hao Chen2,*, Xin Su2, Bin Xie2

    Energy Engineering, Vol.119, No.3, pp. 1239-1259, 2022, DOI:10.32604/ee.2022.017847

    Abstract 20% n-butanol is blended in diesel by volume (noted as D80B20) and experiment has been carried out to study the effect on the combustion and emission characteristics based on a common rail diesel engine with exhaust gas recirculation (EGR) system. The results reveal that D80B20 has longer ignition delay, shorter combustion duration and higher maximum in-cylinder temperature than pure diesel (noted as D100). Further, the number concentration and volume concentration of ultrafine particles decrease significantly while NOX emissions increase a little with the addition of n-butanol. When the exhaust gas is induced into cylinder, NOX emissions significantly decrease and ultrafine… More >

  • Open Access


    Arrhythmic Risk in Paediatric Patients Undergoing Surgical Repair for Pulmonary Atresia with Intact Ventricular Septum

    Pietro Paolo Tamborrino1,2, Corrado Di Mambro1,2,*, Cecilia Marcolin1,2, Walter Vignaroli3, Giulia Cafiero4, Gianluca Brancaccio3, Sonia Albanese3, Massimo Stefano Silvetti1,2, Adriano Carotti3, Fabrizio Drago1,2

    Congenital Heart Disease, Vol.16, No.1, pp. 85-94, 2021, DOI:10.32604/CHD.2021.013038

    Abstract Introduction: While previous studies only focused on the arrhythmic risk associated with specific correction strategies, this study evaluates this risk in a large cohort of paediatric patients with all phenotypes of PA-IVS after surgical repair. Methods: In this single centre observational cohort study, we retrospectively evaluated 165 patients with a diagnosis of PA-IVS and we excluded those with an exclusively percutaneous treatment, patients lost or with insufficient follow-up and those affected by other arrhythmic syndromes. Surgical history and clinical outcomes were reviewed. Results: 86 patients were included in the study (54 male [62.8%], mean age 16.4 ± 6.1 years), with… More >

  • Open Access


    Determination of the Circulation for a Large-Scale Wind Turbine Blade Using Computational Fluid Dynamics

    Hao Cheng, Guangsheng Du*, Meng Zhang, Kun Wang, Wenbin Bai

    FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.4, pp. 685-698, 2020, DOI:10.32604/fdmp.2020.09673

    Abstract The determination of the circulation for wind turbine blades is an important problem in engineering. In the present study, we develop a specific approach to evaluate the integral that represents mathematically the circulation. First the potentialities of the method are assessed using a two-dimensional NACA64_A17 airfoil as a testbed and evaluating the influence of different integration paths and angles of attack on the circulation value. Then the method is applied to blades with different relative heights in order to provide useful reference data to be used for the optimization and reverse design of wind turbine blades. As shown by the… More >

  • Open Access


    Pacemaker treatment after Fontan surgery—A Swedish national study

    Jenny Alenius Dahlqvist1, Jan Sunnegårdh2, Katarina Hanséus3, Eva Strömvall Larsson2, Anders Nygren2, Magnus Dalén4,5, Håkan Berggren6, Jens Johansson Ramgren7, Urban Wiklund8, Annika Rydberg1

    Congenital Heart Disease, Vol.14, No.4, pp. 582-589, 2019, DOI:10.1111/chd.12766

    Abstract Objective: Fontan surgery is performed in children with univentricular heart defects. Previous data regarding permanent pacemaker implantation frequency and indica‐ tions in Fontan patients are limited and conflicting. We examined the prevalence of and risk factors for pacemaker treatment in a consecutive national cohort of patients after Fontan surgery in Sweden.
    Methods: We retrospectively reviewed all Swedish patients who underwent Fontan surgery from 1982 to 2017 (n = 599).
    Results: After a mean follow‐up of 12.2 years, 13% (78/599) of the patients with Fontan circulation had received pacemakers. Patients operated with the extracardiac conduit (EC) type of total cavopulmonary connection… More >

  • Open Access


    Cardiovascular adaptation to the Fontan circulation

    Gruschen R. Veldtman1, Alexander R. Opotowsky2, Samuel G. Wittekind1, Jack Rychik3, Daniel J. Penny4, Mark Fogel3, Bradley S. Marino5, Marc Gewillig6

    Congenital Heart Disease, Vol.12, No.6, pp. 699-710, 2017, DOI:10.1111/chd.12526

    Abstract Although medium-term survival following Fontan operations in the modern era has improved dramatically, late cardiovascular and extracardiac morbidity are common and are associated with impaired quality of life and premature late mortality. This serves as a reminder of the extraordinary adaptations required of the cardiovascular system when the systemic arterial, systemic venous and pulmonary circulations are placed in series coupled to a single ventricular pump. This article reviews the key features and principles that govern interactions between the ventricle, systemic arterial circulation, the systemic venous and pulmonary circulatory compartments, the microcirculation, and lymphatic circulations. The overarching aim is to provide… More >

  • Open Access


    Echocardiographic parameters associated with biventricular circulation and right ventricular growth following right ventricular decompression in patients with pulmonary atresia and intact ventricular septum: Results from a multicenter study

    Shiraz A. Maskatia1, Christopher J. Petit2,3, Curtis D. Travers2, David J. Goldberg4, Lindsay S. Rogers4, Andrew C. Glatz4, Athar M. Qureshi6, Bryan H. Goldstein5, Jingning Ao2,3, Ritu Sachdeva2,3

    Congenital Heart Disease, Vol.13, No.6, pp. 892-902, 2018, DOI:10.1111/chd.12671

    Abstract Background: In patients with pulmonary atresia, intact ventricular septum (PA/IVS) following right ventricular (RV) decompression, RV size and morphology drive clinical outcome. Our objectives were to (1) identify baseline and postdecompression echo‐ cardiographic parameters associated with 2V circulation, (2) identify echocardio‐ graphic parameters associated with RV growth and (3) describe changes in measures of RV size and changes in RV loading conditions.
    Methods: We performed a retrospective analysis of patients who underwent RV de‐ compression for PA/IVS at four centers. We analyzed echocardiograms at baseline, postdecompression, and at follow up (closest to 1‐year or prior to Glenn circulation).
    Results: Eighty‐one… More >

  • Open Access


    Evaluation of systemic microvascular reactivity in adults with congenital heart disease

    Pablo Marino1,2, Gabriella de Oliveira Lopes1,3, Juliana Pereira Borges3, Maria Carolina Terra Cola1, Daniel Arkader Kopiler1, Eduardo Tibirica1

    Congenital Heart Disease, Vol.13, No.6, pp. 978-987, 2018, DOI:10.1111/chd.12660

    Abstract Objective: Adults with congenital heart disease share some features with those with chronic heart failure. Although microvascular endothelial dysfunction has been de‐ scribed in chronic heart failure, evaluation of the microcirculation in adults with con‐ genital heart disease is lacking. The present study aimed to investigate systemic microvascular reactivity in adults with congenital heart disease.
    Interventions: The patients initially underwent cardiopulmonary exercise testing. Then, the cutaneous microvascular reactivity was evaluated in these patients using a laser speckle contrast imaging system coupled with skin iontophoresis of endothelial‐de‐ pendent (acetylcholine) or ‐independent (sodium nitroprusside) vasodilators and pos‐ tocclusive reactive hyperemia (PORH) and… More >

  • Open Access


    Achieving biventricular circulation in patients with moderate hypoplastic right ventricle in pulmonary atresia intact ventricular septum after transcatheter pulmonary valve perforation

    Robin H.S. Chen1, Adolphus K.T. Chau1, Pak Cheong Chow1, Tak Cheung Yung1, Yiu Fai Cheung1,2, Kin Shing Lun1

    Congenital Heart Disease, Vol.13, No.6, pp. 884-891, 2018, DOI:10.1111/chd.12658

    Abstract Objective: Transcatheter valve perforation for pulmonary atresia intact ventricular septum is the standard of care for patients with mild right ventricular hypoplasia. However, its role in moderate right ventricular hypoplasia has been less well defined. We sought to report the long‐term outcome of patients with moderate hypoplastic right ventricle who had undergone the procedure.
    Design, Settings, and Patients: We performed a retrospective analysis on patients who had undergone transcatheter pulmonary valve perforation from January 1996 to January 2015 at our institution. The procedures would be carried out irrespective of the right ventricular size, as long as there were no absolute… More >

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