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An efficient technique for controlling power flow in a single stage grid-connected photovoltaic system

SCIENTIA IRANICA 2014年第3期21卷 885-897页

作者： Datta, A. Bhattacharya, G. Mukherjee, D. Saha, H. Natl Inst Technol Meghalaya Dept Elect & Elect Engn Shillong 793003 Meghalaya India Ramakrishna Mission Vidyamandira Dept Phys Belur Math 711202 Howrah India Bengal Engn & Sci Univ Dept Elect & Telecommun Engn Sibpur 711103 Howrah India Bengal Engn & Sci Univ Ctr Excellence Green Energy & Sensor Syst Sibpur 711103 Howrah India

Compared to multistage grid-connected photovoltaic systems (GCPVSs), complexity in monitoring and controlling scheme in a single-stage GCPVS is much increased, as maximum power point tracking and power sharing with the grid need to be considered simultaneously in the same stage. An efficient technique for performing the aforementioned functions, simultaneously, in a single stage system, by adjustment of the voltage phasor of a voltage source inverter, is presented. Active and reactive powers flow from the inverter is regulated by the adjustment of amplitude and phase angle of the inverter output voltage with respect to the grid voltage. An algorithm is also developed for automatic active and reactive powers sharing for the intended applications in the single stage GCPVSs. A typical 2.8 kWp, 368 V (DC) nominal photovoltaic array based GCPVS is modeled and simulated to analyze proper load matching for different ambient and grid voltage conditions. Performances, like the efficiency of the inverter and the total harmonic distortion of the inverter output voltage and current, are studied, with variations in ambient conditions and the modulation index of a sinusoidal pulse width modulation of the IGBT based inverter. Simulation results have been included to show the feasibility of the proposed technique. (C) 2014 Sharif University of Technology. All rights reserved.

关键词： Single stage Grid-connected PV system Efficient technique Power sharing automatic algorithm

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Accurate Recognition of Vascular Lumen Region from 2D Ultrasound Cine Loops for Bubble Detection

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CURRENT MEDICAL IMAGING 2024年 20卷 e15734056298529页

作者： Wang, Ziyi Yang, Zhuochang Chen, Ziye Huang, Xiaoyu Xu, Lifan Zhou, Chang Zhou, Yingjie Zhu, Baoliang Zhang, Kun Gong, Deren Xu, Weigang Chen, Jiangang East China Normal Univ Shanghai Key Lab Multidimens Informat Proc Shanghai Peoples R China Xian Jiaotong Liverpool Univ Dept Biol Sci Suzhou 215123 Jiangsu Peoples R China Univ Liverpool Univ Liverpool Xian Jiaotong Dept Elect Engn & Elect Suzhou 215123 Jiangsu Peoples R China Xian Jiaotong Liverpool Univ Sch Adv Technol Dept Comp Suzhou 215123 Jiangsu Peoples R China Second Mil Med Univ Naval Special Med Ctr Dept Diving & Hyperbar Med Shanghai 200433 Peoples R China Shanghai Jiao Tong Univ Sch Aeronaut & Astronaut Shanghai 200240 Peoples R China

Background Accurate identification of vascular lumen region founded the base of bubble detection and bubble grading, which played a significant role in the detection of vascular gas emboli for the diagnosis of decompression *** To assist in the detection of vascular bubbles, it is crucial to develop an automatic algorithm that could identify vascular lumen areas in ultrasound videos with the interference of bubble *** This article proposed an automated vascular lumen region recognition (VLRR) algorithm that could sketch the accurate boundary between vessel lumen and tissues from dynamic 2D ultrasound videos. It adopts 2D ultrasound videos of the lumen area as input and outputs the frames with circled vascular lumen boundary of the videos. Normalized cross-correlation method, distance transform technique, and region growing technique were adopted in this *** A double-blind test was carried out to test the recognition accuracy of the algorithm on 180 samples in the images of 6 different grades of bubble videos, during which, intersection over union and pixel accuracy were adopted as evaluation metrics. The average IOU on the images of different bubble grades reached 0.76. The mean PA on 6 of the images of bubble grades reached *** It is concluded that the proposed method could identify the vascular lumen with high accuracy, potentially applicable to assist clinicians in the measurement of the severity of vascular gas emboli in clinics.

关键词： Ultrasound videos KCF Tissue segmentation Bubble detection automatic algorithm DCS

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An algorithm for fatigue crack growth applied to mixed and biaxial mode loadings

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Procedia Structural Integrity 2019年 17卷 547-554页

作者： R. Baptista V. Infante M. Freitas CDP2T and Department of Mechanical Engineering Setúbal School of Technology Instituto Politécnico de Setúbal 2910-761 Setúbal Portugal IDMEC Escola Superior de Tecnologia de Setúbal Instituto Politécnico de Setúbal 2910-761 Setúbal Portugal IDMEC Instituto Superior Técnico Universidade de Lisboa Lisboa Portugal

Fatigue is still one of the main concerns when dealing with mechanical components failure. While it is fundamental to experimentally determine the fatigue material behavior using standard specimens, testing large and complex component geometries can be complicated. In these cases, the Finite Element Method can be a cost-effective solution but developing fatigue crack growth models is still a complicated task. In order to solve this problem, an algorithm for automatic crack propagation was developed. Using three different modules, the algorithm can generate a complex Finite Element Method model including a fatigue crack; solve this model considering complex loading conditions, by applying the superposition method; and calculate the fatigue crack propagation rate, using it to update the original model. In order to benchmark this solution two different problems were analyzed, a modified compact tension specimen and a cruciform specimen. By modifying the compact tension specimen hole location and simulating an initial crack, it was possible to understand how mixed mode conditions influence the fatigue crack path. Different load ratios and initial crack directions on the cruciform specimen were analyzed. Increasing the load ratio will increase the crack deflecting angle. The obtain solutions were compared with experimental results, showing good agreement. Therefore the developed algorithm can be used to predict the fatigue crack growth behavior on complex geometries and when different types of loads are applied to the component.

关键词： Fatigue Crack propagation Mixed mode automatic algorithm

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A novel methodology for the modeling of catheter aspiration in high-fidelity thrombectomy simulations

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Procedia Structural Integrity 2023年 49卷 67-73页

作者： Sara Bridio Giulia Luraghi Anushree Dwivedi Ray McCarthy Jose Felix Rodriguez Matas Francesco Migliavacca Department of Chemistry Materials and Chemical Engineering “Giulio Natta” Politecnico di Milano Piazza Leonardo Da Vinci 32 20133 Milan Italy Cerenovus Neuro Technology Center Ballybrit Business Park H91 K5YD Galway Ireland

The development of high-fidelity in silico simulations of the endovascular thrombectomy (EVT) procedure, the treatment for acute ischemic stroke, is gaining importance for the possibility of investigating the causes of failure of the clinical procedure and optimizing the treatment. This work proposed a novel methodology for a realistic modeling of the thrombus aspiration in a combined EVT procedure, with stent-retriever and proximal aspiration catheter. In the combined EVT procedure, the thrombus is entrapped in the stent struts and is retrieved towards the aspiration catheter. During the retrieval, the thrombus may rotate, and therefore different portions of its surface are subjected to aspiration forces. An automatic algorithm is implemented allowing to redefine the portion of the thrombus surface subjected to the aspiration pressure in different time points of a high-fidelity finite-element EVT simulation. The algorithm updates at each iteration the loaded portion of thrombus surface, by selecting elements aligned with the vascular centerline. The algorithm is applied in a high-fidelity EVT simulation in a patient-like vascular model, demonstrating the ability of obtaining a realistic simulation of thrombus aspiration.

关键词： thrombectomy aspiration catheter finite-element automatic algorithm

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automatic phase space generation for Monte Carlo calculations of intensity modulated particle therapy

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BIOMEDICAL PHYSICS & ENGINEERING EXPRESS 2020年第2期6卷 025001页

作者： Wang, Qianxia Zhu, Cong Bai, Xuemin Deng, Yu Schlegel, Nicki Adair, Antony Chen, Zhi Li, Yongqiang Moyers, Michael Yepes, Pablo Rice Univ Dept Phys & Astron MS3156100 Main St Houston TX 77005 USA Univ Texas MD Anderson Canc Ctr Unit 1420 Dept Radiat Phys 1515 Holcombe Blvd Houston TX 77030 USA Univ Texas Hlth Sci Ctr Houston Sch Publ Hlth Houston TX 77030 USA Univ Houston Dept Ind Engn Houston TX 77204 USA Shanghai Proton & Heavy Ion Ctr Shanghai 201315 Peoples R China

Monte Carlo (MC) is generally considered as the most accurate dose calculation tool for particle therapy. However, a proper description of the beam particle kinematics is a necessary input for a realistic simulation. Such a description can be stored in phase space (PS) files for different beam energies. A PS file contains kinetic information such as energies, positions and travelling directions for particles traversing a plane perpendicular to the beam direction. The accuracy of PS files plays a critical role in the performance of the MC method for dose calculations. A PS file can be generated with a set of parameters describing analytically the beam kinematics. However, determining such parameters can be tedious and time consuming. Thus, we have developed an algorithm to obtain those parameters automatically and efficiently. In this paper, we presented such an algorithm and compared dose calculations using PS automatically generated for the Shanghai Proton and Heavy Ion Center (SPHIC) with measurements. The gamma-index for comparing calculated depth dose distributions (DDD) with measurements are above 96.0% with criterion 0.6%/0.6 mm. For each single energy, the mean difference percentage between calculated lateral spot sizes at 5 different locations along beam direction and measurements are below 3.5%.

关键词： automatic algorithm phase space Monte Carlo particle therapy measurement dose calculation

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Verification of new method for automatic thickness measurement of melanocytic skin tumours by high frequency ultrasound

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JOURNAL OF VIBROENGINEERING 2018年第1期20卷 651-661页

作者： Linkeviciute, Gintare Raisutis, Renaldas Sakalauskiene, Kristina Makstiene, Jurgita Guzaitis, Jonas Pilipaityte, Loreta Valiukeviciene, Skaidra Lithuanian Univ Hlth Sci Dept Skin & Venereal Dis Kaunas Lithuania Kaunas Univ Technol Ultrasound Inst Kaunas Lithuania Lithuanian Univ Hlth Sci Dept Pathol Anat Kaunas Lithuania Kaunas Univ Technol Kaunas Lithuania Lithuanian Univ Hlth Sci Dept Plast & Reconstruct Surg Kaunas Lithuania

Histological thickness of cutaneous melanoma (CM), known as the Breslow index (pT), represents the most important prognostic factor. The objective of this study is to evaluate the reliability of automatic algorithm based on B-scan image processing of 22 MHz ultrasound (US) for measuring the thickness of CM and melanocytic nevi (MN). The thickness of CM (n = 54) and MN (n = 91) has been measured manually (mT) and automatically (aT) using an algorithm based on B-scan image processing of 22 MHz US. All melanocytic skin tumours (MST) were surgically excised and their histological thicknesses (pT) according to Breslow were evaluated. The investigated parameters were expressed as medians with interquartile range (IQR) because of their asymmetric distribution, Spearman's correlation coefficient was determined as well. An agreement between values of mT/aT and mT/pT was evaluated by using the Bland-Altman plots. We found a good agreement of aT and mT with the moderate bias of 0.08 mm and relatively small range (95 % CI -0.01 to 0.18) in CM, accordingly 0.03 mm (95 % CI 0.00 to 0.07 mm) regarding MN. The medians of mT/pT in cases of CM and MN were 0.96 mm (IQR: 0.65-1.52)/0.97 (IQR: 0.66-1.62) and 0.51 mm (IQR: 0.37-0.67) /0.69 mm (IQR: 0.46-1.01) respectively. The parameters of the thickness correlated better in CM (r = 0.86) than in MN (r = 0.64) cases. The difference between manual (mT) and automatic (aT) measurements while evaluating the thickness of MST was non-significant. Therefore, automatic algorithm based on B-scan image processing of 22 MHz US is a reliable tool for measuring the thickness of MST by less experienced operators.

关键词： melanoma thickness melanocytic skin tumors ultrasound automatic algorithm histology

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Semi-automatic segmentation of myocardium at risk from contrast enhanced SSFP images - validation against manual delineation and SPECT

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Journal of Cardiovascular Magnetic Resonance 2015年第SUPPL 1期17卷 Q127-Q127页

作者： Jane Tufvesson Marcus Carlsson Anthony H Aletras Henrik Engblom Jean-Francois Deux Sasha Koul Peder Sörensson John Pernow Dan Atar David Erlinge Håkan Arheden Einar Heiberg Cardiac MR group Lund Dept. of Clinical Physiology Lund University Lund Sweden Dept of Numerical Analysis Faculty of Engineering Lund University Lund Sweden Dept of Cardiology Henri Mondor Hospital Creteil France Dept of Cardiology Lund University Lund Sweden Dept of Medicine Karolinska Institutet Karolinska University Hospital Stockholm Sweden Dept of Cardiology B Oslo University Hospital Ullevål and Faculty of Medicine University of Oslo Oslo Norway

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Agreement between automatic and manual measurement of atrial and ventricular signal-averaged electrocardiograms in healthy subjects

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Annals of Noninvasive Electrocardiology 2000年第2期5卷 133-138页

作者： Savelieva, Irina Aytemir, Kudret Hnatkova, Katerina Camm, A. John Malik, Marek Department of Cardiological Sciences St. George's Hospital Medical School London United Kingdom St. George's Hospital Medical School London SW17 0RE Cranmer Terrace United Kingdom

Background: Although prolonged duration of the signal-averaged (SA) P wave has been proposed as a noninvasive marker of atrial arrhythmias, clinical value of atrial SAECG is limited largely due to the difficulty with detection of the onset and offset of the high gain P wave. The aim of this study was to assess the reliability of automatic measurement of the atrial SAECG. Methods: Fifty-one healthy volunteers (30 men;32 ± 8 years) underwent a session of 3 atrial and 3 ventricular SAECG recordings. automatically detected onset and offset of SA QRS complex (QRS(tot)) and SA P wave (P(tot)) were subsequently corrected by two independent observers. For ventricular SAECG, three conventional time-domain parameters were calculated. For atrial SAECG, the following five parameters were measured: P(tot), root mean square voltages of the entire P(tot) (RMS-P) and of the terminal 40, 30, and 20 ms of P(tot). Relative errors of the different pairs of measurements were used to assess the interobserver and observer-computer variability. The Bland-Altman method was applied to express the agreement between measurements. Results: Although the mean interobserver relative errors were low for QRS(tot) and P(tot) (1.1% vs 1.5%), the observer-computer error was significantly higher for P(tot) than for QRS(tot) (1.7% vs 7.1%;P < 0.0001). For the voltage parameters, the lowest interobserver and observer-computer relative errors were found for RMS-P (6.6% vs 7.3%, P = ns). For RMS voltages of the terminal 40-20 ms of P(tot), relative errors exceeded 10%, but the interobserver error was significantly lower than the observer-computer error (P < 0.0001). Conclusion: automatic detection of the SA P-wave onset and offset is unreliable and the atrial SAECG requires manual correction. Given a good interobserver agreement, such a correction is unlikely to introduce any significant observer-dependent bias.

关键词： Atrial fibrillation automatic algorithm Normal subjects Signal-averaged P wave

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