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Dynamic stability characterization of re-entry modules at hypersonic mach numbers

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International Journal of Modeling, Simulation, and Scientific Computing 2017年第1期8卷 153-164页

作者： J.Vinoth J.Bruce Ralphin Rose Department of Aeronautical Engineering regional Campus Anna UniversityTirunelveli Tamil Nadu 627007India

At the time of re-entry modules entering into the atmosphere from space,a small perturbation introduces dynamic oscillations on the vehicle because of their extreme traveling *** dynamic stability characteristics of re-entry modules at hypersonic Mach numbers is of considerable relevance to their initial *** the present paper,the dynamic stability of blunt cone model about 10◦is examined with wide range of design parameters such as nose bluntness,semi-vertex angle and center of rotation through theoretical and experimental *** approximations are made over a model based on the standard Newtonian *** are conducted at 0.25m hypersonic wind tunnel at M=8.3 and the following trends are observed from the experimental ***,the incremental higher nose bluntness,semi-vertex angle and center of rotation reduce the dynamic *** higher hypersonic Mach numbers(M>10),dynamic stability characteristics of the re-entry module are insensitive to the free stream Mach ***,it is observed that the dynamic stability is increased in proportion to the vibration amplitude at hypersonic speeds.

关键词： re-entry dynamic stability Newtonian theory flexure pivot center of rotation least square method

re-entry of Space Objects from Low Eccentricity Orbits

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International Journal of Astronomy and Astrophysics 2019年第3期9卷 200-216页

作者： Cynthia Sharon Lawrence Ram Krishan Sharma Department of Aerospace Engineering Karunya Institute of Technology and SciencesCoimbatoreIndia

This paper deals with the re-entry predictions of the space objects from the low eccentric orbit. Any re-entering object re-enters the Earth’s atmosphere with a high orbital velocity. Due to the aerodynamic heating the object tends to break into multiple fragments which later pose a great risk hazard to the population. Here a satellite is considered as the space object for which the re-entry prediction is made. This prediction is made with a package where the trajectory path, the time of re-entry and the survival rate of the fragments is done. The prediction is done using DRAMA 2.0—ESA’s Debris Risk Assessment and Mitigation Analysis Tool suite, MATLAB and Numerical Prediction of Orbital Events software. The predicted re-entry time of OSIRIS 3U was found to be on 7th March 2019, 7:25 (UTC), whereas the actual re-entry time was on 7th March 2019, 7:03 (UTC). The trajectory path found was 51.5699 deg. (Lat), −86.5738 deg. (Long.) with an altitude of 168.643 km. But the actual trajectory was 51.76 deg. (Lat), −89.01deg. (Long.) with an altitude of 143.5 km.

关键词： re-entry Space Objects Low Eccentricity Orbits DRAMA 2.0 Risk Event Statistics

Vasoactive-Ventilation-renal Score Predicts Cardiac Care Unit Length of Stay in Patients Undergoing re-entry Sternotomy: A Derivation Study

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World Journal of Cardiovascular Surgery 2018年第1期8卷 7-21页

作者： Vicki L. Mahan Monika Gupta Stephen Aronoff David Bruni Randy M. Stevens Achintya Moulick Division of Pediatric Cardiothoracic Surgery/Department of Surgery St. Christopher’s Hospital for Children/Drexel University College of Medicine Philadelphia USA Division of Critical Care/Department of Pediatrics St. Christopher’s Hospital for Children/Drexel University College of Medicine Philadelphia USA Division of Pediatric Infectious Disease/Department of Pediatrics Lewis Katz School of Medicine at Temple University Philadelphia USA Drexel University College of Medicine Philadelphia USA

Background: The vasoactive-ventilation-renal (VVR) score includes pulmonary and renal dysfunctions not previously addressed by the vasoactive inotrope score (VIS) and may be a better predictor of cardiac care unit (CCU) length of stay (LOS) in patients undergoing re-entry sternotomy (defined as no earlier than 30 days after previous sternotomy) for congenital heart disease (CHD). Methods: Patients undergoing re-entry sternotomy for CHD from August 1, 2009 to June 30, 2016 were studied retrospectively. A total of 96 patients undergoing 133 re-entry procedures were identified. VVR scores were calculated on CCU admission post-procedure (at 0 hour), 24-hour, and 48-hour after admission to the CCU. The response variable was CCU LOS.? recursive partition analysis identified variables predicting LOS. results: 133 re-entry sternotomies in 96 patients made up the samples of the database;11 samples were removed due to incomplete data or placement on ECMO. Of the initial 25 features, 5 were removed for near zero variance and 3 categorical features were removed for non-information. Covariance analysis did not demonstrate any significant correlation amongst the remaining features. Initial recursive tree regression using ANOVA, cross validation and conditional predictive p-value (cp) = 0.01 produced 3 trees. The tree with lowest cross validation error was selected. The resulting 2 split trees with ventilator days less than 20 days and VVR score at 48 hours greater than 23 identified three CCU LOS groups with mean CCU LOS of 77.6, 55.1, and 9.5 days. Conclusions: recursive partition analysis identified ventilator days greater than 20 days and the sub-population VVR at 48 hours as predictive of CCU LOS in patients undergoing re-entry sternotomy for CHD.

关键词： re-entry Sternotomy Vasoactive-Ventilation-renal Score VVR Score recursive Partitioning Analysis Congenital Heart Disease (CHD)

Trajectory shaping guidance law based on virtual angle with terminal constraints

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Journal of Systems Engineering and Electronics 2013年第6期24卷 992-1002页

作者： Xijing Hu Xuemei Huang Beijing Institute of Control and Electronic Technology Science and Technology on Information Systems Engineering Laboratory

A trajectory shaping guidance law based on virtua angle （TSGLBVA） is proposed for a re-entry vehicle with the constraints of terminal impact angles and their time derivatives. In the view of differential properties of the maneuvering trajectory, a virtual angle and a virtual radius are defined. Also, the shaping trajectory of the vehicle is established by the polynomials of the virtual angle. Then, four optimized parameters are selected according to the theorem of parameters transformation presented in this paper. Finally, a convergent variant of the Nelder-Mead algorithm is adopted to obtain the reference trajectory, and a trajectory feedback tracking guidance law is designed. The simulation results demonstrate that the TSGLBVA ensures the re-entry vehicle to impact a target precisely from a specified direction with smal terminal load factor command, as well as to obtain a maximum or constrained terminal velocity according to various requirements.

关键词： re-entry guidance law trajectory shaping virtual angle terminal constraint impact angle

Kinetic comparative study on aerodynamic characteristics of hypersonic reentry vehicle from near-continuous flow to free molecular flow

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Advances in Aerodynamics 2021年第1期3卷 217-226页

作者： Jin Li Dingwu Jiang Xiangren Geng Jianqiang Chen China Aerodynamics research and Development Center Mianyang 621000SichuanChina

A scaled model of the X38-like configuration was simulated under hypersonic conditions for the direct simulation Monte Carlo method and the unified gas kinetic *** inflow conditions considered several flow regimes,from the near-continuum through the slip-transitional to the free molecular *** fields and surface properties were compared in detail between these two *** only the density and temperature contours distribution but also the surface pressure,heat flux,friction distribution,both kinetic methods give fairly consistent *** of the model were also achieved and *** results provided by both methods agreed with each other very *** effects of the Knudsen number and angle of attack were *** is meaningful to carry out comparative studies and accelerate both methods to further progress.

关键词： DSMC UGKS Aerodynamic re-entry

Intimate partner violence against women. Does violence decrease after the entry of the alleged offender into the criminal justice system?

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Forensic Sciences research 2022年第1期7卷 53-60页

作者： Paulo Vieira-Pinto JoséIgnacio Muñoz-Barús Tiago Taveira-Gomes Maria João Vidal-Alves Teresa Magalhães Department of Forensic Sciences PathologyGynaecology and ObstetricsPaediatricsInstitute of Forensic SciencesUniversity of Santiago de CompostelaSantiago de CompostelaSpain IINFAC TS-Institute of research and Advanced Training in Health Sciences Department of SciencesCESPUUniversity Institute of Health Sciences(IUCS)GandraPortugal cFaculty of Medicine University of PortoPortoPortugal CINTESIS-Centre of Health Technology and Service research University of PortoPortoPortugal Fernando Pessoa University PortoPortugal

Intimate partner violence(IPV)is simultaneously assumed as a serious crime and a major public health issue,having recurrences as one of its main characteristics and,consequently,re-entries of some alleged offenders in the criminal justice system(CJS).The main goal of this study is to assess if in cases of female victims of IPV,violence decreases after the first entry of the alleged offender in the CJS.A retrospective study was performed based on the analysis of police reports of alleged cases of IPV during a 4-year *** final sample(n=1488)was divided into two groups according to the number of entries in the CJS(single or multiple)followed by a comparative *** suggest that violence decreases after the first entry of alleged offenders in the ***-entries were found in only 15.5%of the cases but they were accountable for 3.3 times more crimes on ***,victims of recidivism presented more injuries and required more medical ***,a small group of alleged offenders seems to be more violent and accountable for most of the IPV crimes registered in the CJS suggesting that regardless of legal sanctions aiming to deter violence,these measures may not be enough for a certain group of *** study sustains the need for a predictive model to quantify the risk of repeated IPV cases within the Portuguese population.

关键词： Forensic sciences intimate partner violence women re-entry recidivism criminal justice system

Aortic Sinus of Valsalva Aneurysm Isolation by Radiofrequency Ablation in Outflow Tract Ventricular Tachycardia

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World Journal of Cardiovascular Diseases 2014年第4期4卷 131-137页

作者： Nicholas Olson Scott W. Ferreira Peter C. Mikolajczak Ali Mehdirad Division of Electrophysiology Saint Louis University Saint Louis USA

Idiopathic monomorphic ventricular tachycardia and premature ventricular complexes (PVCs) commonly arise from the right and left ventricular outflow tracts (VOT). Their mechanism is most commonly triggered activity from delayed after-depolarizations and successful ablation is performed at the site of earliest endocardial activation. re-entrant mechanisms have been rarely described. We report a case of an otherwise healthy patient who ultimately underwent six electro-physiology studies (EPS) and suffered numerous implantable cardiac defibrillator (ICD) discharges prior to the successful radiofrequency ablation (RFA) of two idiopathic VOT tachycardias. During the sixth EPS, a proximal aortogram demonstrated a left aortic sinus of valsalva (LASV) aneurysm. Subsequntly, a novel and successful RFA strategy of aneurysm isolation was undertaken. The presence of multiple clinical or inducible VT morphologies and the characterization of a VT as re-entrant should raise concerns that a complex arrhythmogenic substrate is present and defining the anatomy with angiography or an alternative imaging modality is essential in achieving a successful ablation strategy.

关键词： Ventricular Tachycardia Outflow Tract Aortic Cusp Sinus of Valsalva Aneurysm Normal Heart Radiofrequency Ablation re-entry