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迭代制导及其在火箭飞行中的应用

导弹与航天运载技术(中英文) 1983年第12期 35-45页

作者： DORIS C.CHANDLeR ISAAC e.smith 鸣远

本文讨论了迭代制导模型及其在火箭上面级的三维真空飞行中的应用。迭代制导模型是一种惯性的闭合系统模型,在这种模型中,火箭起飞后只需要火箭导航系统的输入信号。也就是说,迭代制导按照火箭状态(速度,位置,纵向加速度和重力加速度)... 详细信息

本文讨论了迭代制导模型及其在火箭上面级的三维真空飞行中的应用。迭代制导模型是一种惯性的闭合系统模型,在这种模型中,火箭起飞后只需要火箭导航系统的输入信号。也就是说,迭代制导按照火箭状态(速度,位置,纵向加速度和重力加速度)和要求的发动机关机状态来计算操纵指令。制导指令每个制导循环修正一次,以便用来修正火箭状态。迭代制导方案是一种轨道适应制导方案,该方案是火箭在各种预计扰动量的扰动下,轨道均将保持其最佳特性而不使发动机关机点精度受到任何损失。它的最佳特性和精度已由土星1B和土星V的飞行所证实。

关键词：方程火箭飞行迭代制导多级火箭

Research on water ice content in Cabeus crater using the data from the microwave radiometer onboard Chang’e-1 satellite

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Science China(Physics,Mechanics & Astronomy) 2010年第12期53卷 2172-2178页

作者： MeNG ZhiGuo CHeN ShengBo edward matthew OSeI Jnr WANG ZiJun CUI TengFei College of Geoexploration Science and Technology Jilin UniversityChangchun 130026China Department of Geomatic engineering Kwame Nkrumah University of Science and TechnologyKumasiGhana

The existence, formation and content of water ice in the lunar permanently shaded region is one of the important questions for the current Moon study. On October 9, 2009, the LCROSS mission spacecraft impacted the Moon, and the initial result verified the existence of water on the Moon. But the study on formation and content of water ice is still under debate. The existence of water ice can change the dielectric constants of the lunar regolith, and a microwave radiometer is most sensitive to the dielectric parameters. Based on this, in this paper, the radiation transfer model is improved according to the simulation results in high frequency. Then the mixture dielectric constant models, including Odelevsky model, Wagner and landau-Lifshitz model, Clau-sius model, Gruggeman-Hanai model, etc., are analyzed and compared. The analyzing results indicate that the biggest difference occurs between Lichtenecker model and the improved Dobson model. The values estimated by refractive model are the second biggest in all the models. And the results from Odelevsky model, strong fluctuation model, Wagner and Landau –Lifshitz model, Clausius model and Bruggeman-Hanai model are very near to each other. Thereafter, the relation between volume water ice content and microwave brightness temperature is constructed with Odelevsky mixing dielectric model and the improved radiative transfer simulation, and the volume water ice content in Cabeus crater is retrieved with the data from microwave radiometer onboard Chang’e-1 satellite. The results present that the improved radiative transfer model is proper for the brightness temperature simulation of the one infinite regolith layer in high frequency. The brightness temperature in Cabeus crater is 69.93 K (37 GHz), and the corresponding volume water ice content is about 2.8%.

关键词： Cabeus crater CeLMS radiation transfer simulation mixture dielectric constant model water ice content

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重载货车径向转向架的经济效益及其性能

国外铁道车辆 2007年第1期44卷 34-38页

作者： Roy e.smith[加拿大] 李莉（译）刘宏友（校）

介绍了Resco engineering公司研发的货车用构架式径向转向架。经AAR试验表明,与常规转向架及性能良好的转向架相比,Resco径向转向架的曲线通过能力非常优越,动力学稳定性极好。从经济效益角度,概述了采用Resco径向转向架所能产生的一系... 详细信息

介绍了Resco engineering公司研发的货车用构架式径向转向架。经AAR试验表明,与常规转向架及性能良好的转向架相比,Resco径向转向架的曲线通过能力非常优越,动力学稳定性极好。从经济效益角度,概述了采用Resco径向转向架所能产生的一系列节约效果。

关键词：重载货车转向架加拿大

Combined influence of Ce(Ⅲ)and iodide ions for corrosion protection of AA 2024-T3 in acidic to neutral chloride-rich environments:electrochemical and surface characterization studies

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Journal of Rare earths 2023年第2期41卷 309-320页

作者： Mohammed A.el-Hashemy Anthony e.Hughes Thomas Gengenbach A.matthew Glenn Ivan S.Cole Chemistry Department College of ScienceJouf UniversityP.O.Box 2014SakakaAljoufSaudi Arabia Air Pollution Research Department Environmental and Climate Change Research InstituteNational Research CentreDokkiGiza12622Egypt CSIRO Mineral Resources ClaytonVic3168Australia CSIRO Manufacturing ClaytonVic3168Australia School of engineering RMIT UniversityCarltonVic3053Australia

It has been reported that trivalent cerium salts are effective inhibitors for corrosion of AA2024-T3 in neutral to alkaline co rrosive enviro nments,but poor in acidic *** this study,work was done for extending corrosion resistance provided by Ce(NO_(3))_(3)to acidic pHs as low as 2.5 through the addition of iodide *** this end,potentiodynamic polarization was used to ascertain the optimum Ce(Ⅲ)concentration for the inhibition of AA2024-T3 corrosion in 3.5%NaCl *** optimum concentration is found to be in a range between 0.1 and 0.3 mmol/L Ce(Ⅲ).This optimum concentration also gives a maximum width of the passive region under the pitting potential(epit).Based on this optimization,further work was performed as a function of pH without and in the presence of 0.01 mol/L KI at five pH values(2.5,4,5,7,and 8).Without iodide the best inhibition provided by the Ce(Ⅲ)cation is at pH=7 but active corrosion is observed at pH=2.5 with an estimated inhibitor efficiency(-37.6%).The addition of iodide ions(I^(-))reverses the poor corrosion resistance whereby the inhibitor efficiency becomes 47.7%.Moreover,at pH=4 the efficiency is also increased from 54.0%to 81.0%with iodide addition providing a significant improvement over Ce(Ⅲ)cations alone under acidic *** is a synergistic effect between I-anion and Ce(Ⅲ)cation,which is determined to be 2.4 and 2.1 at pH=2.5and 4.0,*** pH=5 and 7 there is virtually no change in inhibition but at pH=8 the inhibition falls away due to a considerable amount of cerium precipitating out of solution as cerium *** protective film formed on sites in the aluminium alloy surface at different pH values was examined by both scanning electron microscopy with energy dispersive X-ray analysis and X-ray photoelectron spectroscopy to determine the role of these ions as a function of pH in surface *** is proposed that at pH=2.5 protection is provided by a bilayer adsorption of iodide with"cap

关键词： Aluminium alloy Cerium(Ⅲ)salt Potassium iodide Corrosion inhibitor XPS Rare earths

Trait associations in common bean genotypes grown under drought stress and field infestation by BSM bean fly

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The Crop Journal 2015年第4期3卷 305-316页

作者： Daniel Ambachew Firew Mekbib Asrat Asfaw Stephen e.Beebe matthew W.Blair South Agricultural Research Institute(SARI) Haramaya University International Potato Center (CIP) International Center for Tropical Agriculture (CIAT) Tennessee State University (TSU)

Understanding functional relations among plant traits and their modulation by growing conditions is imperative in designing selection strategies for breeding programs. This study assessed trait relationships among 196 common bean genotypes exposed to stresses for drought and field infestation of bean fly or bean stem maggot(BSM). The study was carried out at two locations and data was analyzed with linear correlation, path coefficient and genotype × trait biplot analyses. Multiple trait data related to mechanisms of drought and bean fly tolerance were collected on 196 genotypes grown under i) water deficit at mid-pod fill, or ii) unprotected against bean fly; iii) irrigated, well watered conditions, or iv) bean fly protection with chemicals. Seed yield exhibited positive and significant correlations with leaf chlorophyll content, vertical root pulling resistance, pod harvest index, pods per plant and seeds per pod at both phenotypic and genotypic levels under stress and non-stress conditions. Genotypic correlations of traits with seed yield were greater than their respective phenotypic correlations across environments indicating the greater contribution of genotypic factors to the trait correlation. Pods per plant and seeds per pod had high positive direct effects on seed yield both under stress and non-stress whereas pods per plant had the highest indirect effect on seed yield through pod harvest index under *** general, our results suggest that vertical root pulling resistance and pod harvest index are important selection objectives for improving seed yield in common beans under non-stress and stress conditions, and particularly useful for drought and BSM tolerance evaluation.

关键词： Bean stem maggot(BSM) Path coefficient Selection objective Trait linkage Pleiotropism

emerging artificial intelligence applications in liver magnetic resonance imaging

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World Journal of Gastroenterology 2021年第40期27卷 6825-6843页

作者： Charles e Hill Luca Biasiolli matthew D Robson Vicente Grau Michael Pavlides Department of engineering Science University of OxfordOxford OX37DQUnited Kingdom Radcliffe Department of Medicine University of OxfordOxford OX39DUUnited Kingdom MR Physics Perspectum LtdOxford OX42LLUnited Kingdom Department of engineering University of OxfordOxford OX37DQUnited Kingdom Oxford Centre for Clinical Magnetic Resonance Research Division of Cardiovascular MedicineRadcliffe Department of MedicineUniversity of OxfordOxford OX39DUUnited Kingdom Translational Gastroenterology Unit University of OxfordOxford OX39DUUnited Kingdom Oxford NIHR Biomedical Research Centre University of OxfordOxford OX39DUUnited Kingdom

Chronic liver diseases(CLDs)are becoming increasingly more prevalent in modern *** use of imaging techniques for early detection,such as magnetic resonance imaging(MRI),is crucial in reducing the impact of these diseases on healthcare *** intelligence(AI)algorithms have been shown over the past decade to excel at image-based analysis tasks such as detection and *** applied to liver MRI,they have the potential to improve clinical decision making,and increase throughput by automating *** Liver diseases becoming more prevalent in society,the need to implement these techniques to utilize liver MRI to its full potential,is *** this review,we report on the current methods and applications of AI methods in liver MRI,with a focus on machine learning and deep learning *** assess four main themes of segmentation,classification,image synthesis and artefact detection,and their respective potential in liver MRI and the wider *** provide a brief explanation of some of the algorithms used and explore the current challenges affecting the *** there are many hurdles to overcome in implementing AI methods in the clinic,we conclude that AI methods have the potential to positively aid healthcare professionals for years to come.

关键词： Liver diseases Magnetic resonance imaging Machine learning Deep learning Artificial intelligence Computer vision

The ghosts of parasitism past:lingering frontline anti-brood parasite defenses in a former host

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Current Zoology 2021年第6期67卷 573-583页

作者： matthew.H.J.CHAUMONT Naomi e.LANGMORe Justin A.WeLBeRGeN Hawkesbury Institute for the environment Western Sydney University RichmondNSW2753Australia Research School of Biology Australian National UniversityCanberraACT 2600Australia

Coevolutionary arms races between brood parasites and hosts provide tractable systems for understanding antagonistic coevolution in nature;however,little is known about the fate of frontline antiparasite defenses when the host“wins”the coevolutionary arms *** recreating bygone species interactions,using artificial parasitism experiments,lingering defensive behaviors that evolved in the context of parasitism can be understood and may even be used to identify the unknown agent of parasitism *** we present the first study of this type by evaluating lingering“frontline”nest defenses that have evolved to prevent egg laying in a former brood parasite *** Australian reed warbler Acrocephalus australis is currently not parasitized but is known to exhibit fine-tuned egg discrimination—a defensive behavior indicative of a past brood parasite–host arms race and common in closely related parasitized ***,using 3D-printed models of adult brood parasites,we examined whether the Australian reed warbler also exhibits frontline defenses to adult brood parasites,and whether we could use these defenses to identify the warbler’s“ghost of parasitism past.”Our findings provide evidence that the Australian reed warbler readily engages in frontline defenses that are considered adaptive specifically in the context of brood ***,individuals were unable to discriminate between adults of different brood parasite species at their ***,our results demonstrate that despite a relaxation in selection,defenses against brood parasitism can be maintained across multiple stages of the host’s nesting cycle,and further suggest that,in accordance with previous findings,that learning may be important for fine-tuning frontline defense.

关键词： brood parasites coevolutionary arms-race ghosts of parasitism past hosts lingering traits

Paraspinous hemolymphangioma associated with adolescent scoliosis

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World Journal of Clinical Cases 2015年第6期3卷 514-518页

作者： Ishaan Swarup Benjamin T Bjerke-Kroll matthew e Cunningham Orthopaedic Surgery Hospital for Special Surgery

Lymphangiomas are a group of benign malformations of the lymphatic system, and hemolymphangioma(or hemangiolymphangioma) is a rare congenital malformation of the lymphatic system with vascular involvement. These benign malformations are most commonly diagnosed at an early age, and may be present as a part of an associated syndrome. In this case report, we describe the first case of adolescent scoliosis associated with a large, paraspinous hemolymphangioma. A 15-year-old girl with an incidental finding of a paraspinous hemolymphangioma is presented along with her history, physical exam, radiographic findings, and operative course. The possible pathogenesis, treatment approach, and clinical dilemmas are also discussed. Given the well-known relationship between tumors and scoliosis, a benign paraspinous vascular and lymphatic tumor may be responsible for the presence of scoliosis in a small number of patients.

关键词： Case report Scoliosis etiology Hemolymphangioma Tumor

Percutaneous cervical carotid artery access with stenting of the left internal carotid artery in an elderly patient

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Journal of Geriatric Cardiology 2007年第2期4卷 111-114页

作者： matthew O'Steen Kathy Dougherty Neil e. Strickman Division of Cardiology Baylor College of Medicine at St. Luke's Episcopal Hospital and the Texas Heart Institute Houston TX

To describe the successful endovascular treatment in a nonagenarian with symptomatic internal carotid artery stenosis using direct carotid artery access. An independent 98 year-old man was admitted to our hospital for symptoms of progressive weakness with disorientation and dysphasia. Carotid Duplex ultrasonography was performed which revealed a totally occluded right internal carotid artery and high grade stenosis of the left internal carotid artery by velocities of 608/240 cm/sec. The patient refused surgical endarterectomy and thus he was referred for carotid artery stenting. Using the femoral artery approach and multiple catheter techniques, access to the common carotid artery could not be accomplished safely. The procedure was aborted and he was therefore brought back to the catheterization laboratory the following day for direct carotid access. Carotid artery stenting was accomplished by using of a 6F sheath percutaneously in the left common carotid, cerebral protection device (CPD) and a Nitinol stent. The patient was discharged the following day without complications. At 14 months follow-up the patient is functional and independent without recurrence of symptoms. Carotid artery stenting via direct access can be accomplished in patients when the femoral artery approach is anatomically prohibitive. In this case of advanced age and the patient’s refusal for surgery, direct carotid access was his only option.

关键词： left Percutaneous cervical carotid artery access with stenting of the left internal carotid artery in an elderly patient