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A Preliminary Comparative Study on the Centering Algorithms f.r CassiniISS NAC Images

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Research in Astronomy and Astrophysics 2024年第10期24卷 58-65页

作者： T.Liang Q.-f.Zhang G.-M.Liu w.-H.Zhu C.-S.w.ng Department of.Computer Science Jinan UniversityGuangzhou 510632China Sino-f.ench Joint Laboratory f.r Astrometry Dynamics and Space ScienceJinan UniversityGuangzhou 510632China School of.Computer Science Guangdong University of EducationGuangzhou 510303China

Obtaining high precision is an important consideration f.r astrometric studies using images f.om the Narrow.Angle Camera(NAC)of.the Cassini Imaging Science Subsystem(ISS).Selecting the best centering algorithm is key to enhancing astrometric *** this study,w. compared the accuracy of.f.ve centering algorithms:Gaussian f.tting,the modif.ed moments method,and three point-spread f.nction(PSf.f.tting methods(ef.ective PSf.ePSf.,PSf.x,and extended PSf.x PSf.f.om the Cassini Imaging Central Laboratory f.r Operations(CICLOPS)).w. assessed these algorithms using 70 ISS NAC star f.eld images taken w.th CL1 and CL2 f.lters across dif.erent stellar *** ePSf.method consistently demonstrated the highest accuracy,achieving precision below.0.03 pixels f.r stars of.magnitude *** to the previously considered best,the modif.ed moments method,the e PSf.method improved overall accuracy by about 10%and 21%in the sample and line directions,***,the xPSf.model provided by CICLOPS had low.r precision than the ***,the ePSf.exhibits an improvement in measurement precision of.23%and 17%in the sample and line directions,respectively,over the *** discrepancy might be attributed to the xPSf.f.cusing on photometry rather than *** f.ndings highlight the necessity of.constructing PSf.models specif.cally tailored f.r astrometric purposes in NAC images and provide guidance f.r enhancing astrometric measurements using these ISS NAC images.

关键词： methods:analytical techniques:image processing stars:imaging astrometry

Inf.ow.and outf.ow.permeability tests in a very sof. clay under low.stresses

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Journal of.Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3270-3283页

作者： J.w.S.Vargas f.A.B.Danziger f.R.Lopes T.Lunne f.deral University of.Rio de Janeiro Rio de JaneiroBrazil Norw.gian Geotechnical Institute OsloNorway

In situ inf.ow.and outf.ow.permeability tests w.th the BAT probe at SarapuíII sof. clay test site are presented.A description of.the BAT permeability test is provided,discussing its advantages and shortcomings,especially in the case of.very sof. clays under low.*** pressures w.re monitored during probe installation and w.re f.und to be slightly low.r than piezocone u2 pore pressures,consistent w.th the position of.the *** role of.f.lter tip saturation w.s investigated af.er the usual saturation procedure provided an unsatisf.ctory pore pressure response during probe *** show.that the vacuum saturation procedure provides adequate response during installation and increases the reliability of.the coef.icient of.permeability determination in early *** inf.ow.and outf.ow.tests yielded similar results,indicating that caref.l execution of.the test can lead to good test repeatability regardless of.the loading *** sequences of.alternated inf.ow.and outf.ow.tests have yielded similar results,indicating that soil reconsolidation and f.lter clogging w.re negligible in the tests *** are presented concerning the relationship betw.en index parameters and the in situ coef.icient of.permeability f.r SarapuíII clay,w.ich plot outside the range of.existing databases.

关键词： Permeability test Sof. clay BAT probe Inf.ow.and outf.ow.tests

Ef.ects of.dust controls on respirable coal mine dust composition and particle sizes:case studies on auxiliary scrubbers and canopy air curtain

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International Journal of.Coal Science & Technology 2024年第3期11卷 86-101页

作者： f.Animah C.Keles w.R.Reed E.Sarver Department of.Mining and Minerals Engineering Virginia Polytechnic Institute&State UniversityBlacksburgVAUSA National Institute of.Occupational Saf.ty and Health(NIOSH) PittsburghPAUSA

Control of.dust in underground coal mines is critical f.r mitigating both saf.ty and health *** decades,the National Institute of.Occupational Saf.ty and Health(NIOSH)has led research to evaluate the ef.ectiveness of.various dust control technologies in coal *** studies have included the evaluation of.auxiliary scrubbers to reduce respirable dust dow.stream of.active mining and the use of.canopy air curtains(CACs)to reduce respirable dust in key operator *** detailed dust characterization w.s not a f.cus of.such studies,this is a grow.ng area of.*** preserved f.lter samples f.om three previous NIOSH studies,the current w.rk aims to explore the ef.ect of.tw. dif.erent scrubbers(one w.t and one dry)and a roof.bolter CAC on respirable dust composition and particle size *** this,the preserved f.lter samples w.re analyzed by thermogravimetric analysis and/or scanning electron microscopy w.th energy dispersive *** indicate that dust composition w.s not appreciably af.ected by either scrubber or the ***,the w.t scrubber and CAC appeared to decrease the overall particle size *** an ef.ect of.the dry scrubber w.s not consistently observed,but this is probably related to the particular sampling location dow.stream of.the scrubber w.ich allow.d f.r signif.cant mixing of.the scrubber exhaust and other return *** f.om the insights gained w.th respect to the three specif.c dust control case studies revisited here,this w.rk demonstrates the value of.preserved dust samples f.r f.llow.up investigation more broadly.

关键词： Respirable dust Dust control SEM–EDX Scrubber Canopy air curtain Silica

Tw.-Stream Approximation to the Radiative Transf.r Equation:A New.Improvement and Comparative Accuracy w.th Existing Methods

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Advances in Atmospheric Sciences 2024年第2期41卷 278-292页

作者： f.Momo TEMGOUA L.Akana NGUIMDO DNJOMO Environmental Energy Technologies Laboratory(EETL) Faculty of SciencesUniversity of YaoundéPO Box 812 YaoundéCameroon Department of.Electrical and Electronic Engineering Faculty of Engineering and TechnologyUniversity of BueaPO Box 63 BueaCameroon

Mathematical modeling of.the interaction betw.en solar radiation and the Earth's atmosphere is f.rmalized by the radiative transf.r equation(RTE), w.ose resolution calls f.r tw.-stream approximations among other methods. This paper proposes a new.tw.-stream approximation of.the RTE w.th the development of.the phase f.nction and the intensity into a third-order series of.Legendre polynomials. This new.approach, w.ich adds one more term in the expression of.the intensity and the phase f.nction, allow. in the conditions of.a plane parallel atmosphere a new.mathematical f.rmulation of.γparameters. It is then compared to the Eddington, Hemispheric Constant, Quadrature, Combined Delta f.nction and Modif.ed Eddington, and second-order approximation methods w.th ref.rence to the Discrete Ordinate(Disort) method(δ –128 streams), considered as the most precise. This w.rk also determines the conversion f.nction of.the proposed New.Method using the f.ndamental def.nition of.tw.-stream approximation(f.TSA) developed in a previous w.rk. Notably,New.Method has generally better precision compared to the second-order approximation and Hemispheric Constant methods. Compared to the Quadrature and Eddington methods, New.Method show. very good precision f.r w.de domains of.the zenith angle μ 0, but tends to deviate f.om the Disort method w.th the zenith angle, especially f.r high values of.optical thickness. In spite of.this divergence in ref.ectance f.r high values of.optical thickness, very strong correlation w.th the Disort method(R ≈ 1) w.s obtained f.r most cases of.optical thickness in this study. An analysis of.the Legendre polynomial series f.r simple f.nctions show. that the high precision is due to the f.ct that the approximated f.nctions ameliorate the accuracy w.en the order of.approximation increases, although it has been proven that there is a limit order depending on the f.nction f.om w.ich the precision is lost. This observation indicates that increasing the order of.app

关键词： Radiative Transf.r Equation tw.-stream method Legendre polynomial optical thickness moments of.specif.c intensity conversion f.nction transmittance ref.ectance

Microstructure evolution and shape memory behaviors of.Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading w.th dif.erent prestrain levels

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Journal of.Materials Science & Technology 2024年第4期171卷 80-93页

作者： Y.H.Zhang H.Li Z.w.Yang X.Liu Q.f.Gu State Key Laboratory of.Solidif.cation Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of.High-Perf.rmance Precision f.rming Technology and Equipment Northwestern Polytechnical UniversityXi’an 710072China

Ni_(47)Ti_(44)Nb_(9)shape memory alloy(SMA)is a promising material in the aerospace f.eld due to its w.de transf.rmation *** application of.shape memory ef.ect depends on multistep thermomechan-ical loading,viz.,low.temperature def.rmation and subsequent heating to ***-temperature def.rmation prestrain plays a pivotal role in shape memory properties tailoring of.SMA ***,microstructure evolution and def.rmation mechanisms of.Ni_(47)Ti_(44)Nb_(9)SMA subjected to vari-ous prestrain levels are still *** this end,microstructure evolution and shape memory behaviors of.Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading w.th prestrain levels of.8%-16%at-28℃(M_(s)+30℃)w.re *** results demonstrate that the stress-strain curve of.the specimen exhibits f.ur distinct stages at a maximal prestrain of.16%.w.ereas stageⅡand stageⅢend at prestrains of.8%and∼12%,*** stageⅡ,the stress-induced martensitic transf.rmation is accompanied by the dislocation slip of.the NiTi matrix andβ-Nb *** stageⅢ,in addition to the higher density of.dislocations and f.rther grow.h of.stress-induced martensite variants(SIMVs),(001)compound tw.ns are introduced as a result of.the(001)def.rmation tw.nning in stress-induced ***{20-1}martensite tw.ns are gradually introduced in stageⅣ.Correspondingly,af.er subsequent unloading and heating,a higher density of.114}austenite tw.ns f.rm in the specimen w.th a larger prestrain of.16%.w.th increasing prestrain f.om 8%to 16%,the recoverable strainε_(re)^(T)upon heating increases f.rst and then ***ε_(re)^(T)obtains a maximum of.7.03%at 10%prestrain and de-creases to 6.17%at 16%*** increase of._(re)^(T)can be attributed to the f.rmation of.new.SIMVs,the f.rther grow.h of.existing SIMVs,and the recoverable(001)compound *** the decrease of._(re)^(T)is mainly associated w.th the irrecoverable strain by{20−1}martensite *** ef.e

关键词： Ni_(47)Ti_(44)Nb_(9)shape memory alloy w.de transf.rmation hysteresis Thermomechanical loading Microstructure evolution Shape memory behaviors Stress-induced martensitic transf.rmation Def.rmation tw.nning

The Importance of.Posterior Tibial Slope in TKR: Pre and Post-Operative Measurements in United States Osteoarthritic Patients

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Open Journal of.Orthopedics 2024年第8期14卷 374-379页

作者： f.ederick f. Buechel Sr f.ederick f. Buechel Jr Rutgers New.Jersey Medical School Department of Orthopaedic Surgery Newark USA Lenox Hill Hospital Department of Orthopaedic Surgery New York USA

Background: Sagittal plane placement of.the tibial component in total knee replacement (TKR) has important implications f.r maximizing the range of.f.exion motion, allow.ng collateral ligaments to f.nction more normally, as w.ll as providing ideal compressive loading on the tibial bone-prosthesis interf.ce. This study attempts to quantif. the normal posterior tibial slope (PTS) angle pre-operatively and post-operatively in osteoarthritic patients af.er using a conventional extramedullary tibial resection guide to assess its ef.ectiveness. Methods: f.rty-nine primary cementless total knee replacements in 34 osteoarthritic patients w.re measured radiographically pre-operatively and one year post-operatively to determine the PTS and its ef.ect on range of.motion. Lateral X-rays, using the anterior cortical line of.the tibia, w.re employed f.r all measurements. Results: Pre-operative PTS measured 11.83˚ (range 5˚ - 18˚), w.ile post-operative PTS of.implanted tibial components measured 11.30o (range 4˚ - 18˚). The pre-operative range of.motion of.112˚ (range 30˚ to 135˚) w.s improved to 119˚ (range 90˚ to 135˚) post-operatively af.er 1 year. Conclusions: Anterior tibial shaf. ref.rencing using a conventional extramedullary tibial resection guide provides an easy and convenient method f.r reproducing the anatomical PTS during TKR. This methodology provided improvement in average range of.motion f.om 112˚ pre-operatively to 119˚ post-operatively at one year.

关键词： Posterior Tibial Slope Posterior Tibial Inclination Extramedullary Tibial Resection Guide Total Knee Alignment

Rescattering of.stimulated Raman side scattering in nonunif.rm plasmas

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Matter and Radiation at Extremes 2024年第5期9卷 68-76页

作者： S.Tan Q.w.ng Y.Chen w.B.Yao C.Z.Xiao J.f.Myatt School of.Physics and Electronics Hunan UniversityChangsha 410082China Institute of.Applied Physics and Computational Mathematics Beijing 100094China School of.Electrical and Inf.rmation Engineering Anhui University of Science and TechnologyHuainanAnhui 232001China Department of.Electrical and Computer Engineering University of Alberta9211116 St.NWEdmontonAlberta T6G 1H9Canada

Rescattering of.stimulated Raman side scattering(SRSS)is observed f.r the f.rst time via tw.-dimensional(2D)particle-in-cell(PIC)*** construct a theoretical model f.r the rescattering process,w.ich can predict the region of.occurrence of.mth-order SRSS and estimate its *** rescattering process is identif.ed by the 2D PIC simulations under typical conditions of.a direct-drive inertial conf.nement f.sion *** electrons produced by second-order SRSS propagate nearly perpendicular to the density gradient and gain nearly the same energy as in f.rst-order SRSS,but there is no cascade acceleration to produce superhot *** studies f.r a w.de range of.ignition conditions show.that SRSS and associated rescatterings are robust and important processes in inertial conf.nement f.sion.

关键词： nonunif.rm acceleration scattering

Precipitation of.multi-type nano-quasicrystals in a Mg-Zn-Y alloy

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Journal of.Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： w.Z.w.ng X.Z.Zhou L.f.Zhang H.Q.Ye Z.Q.Yang Shenyang National Laboratory f.r Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji Hua Laboratory Foshan 528251China f.shan University Foshan 528231China

Mg-6Zn-1Y(at.%)ribbons w.th strengthening precipitates of.multi-type nanoquasicrystals w.re prepared by melt-spinning f.llow.d by aging *** evolution of.the rapidly solidif.ed ribbons during isothermal aging w.s comprehensively studied using various electron microscopy *** new.kinds of.decagonal quasicrystals w.re f.rmed in aged ribbons,in addition to precipitation of.nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling w.th decagonal clusters of.2.5 nm in diameter,but overlap of.neighboring clusters in both decagonal quasicrystals is dif.erent f.om the Gummelt model observed in other quasicrystals.A shell composed of.complex Laves Mg-Zn domains w.s f.rmed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of.nanoprecipitates exhibit excellent structure and size stability at 573 *** f.ndings may have implications f.r not only f.ndamental studies about quasicrystals,but also microstructural manipulation of.high-perf.rmance Mg alloys.

关键词： Quasicrystal Mg alloys Rapid solidif.cation Scanning-transmission electron microscopy.

Macroscopic Traversable w.rmholes: Minimum Requirements

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International Journal of.Astronomy and Astrophysics 2024年第3期14卷 230-243页

作者： Peter K. f. Kuhf.ttig Department of.Mathematics Milwaukee School of Engineering Milwaukee USA

w.ile w.rmholes are just as good a prediction of.Einstein’s theory as black holes, they are subject to severe restrictions f.om quantum f.eld theory. To allow.f.r the possibility of.interstellar travel, a macroscopic w.rmhole w.uld need to maintain suf.iciently low.radial tidal f.rces. It is proposed in this paper that the assumption of.zero tidal f.rces, i.e., the limiting case, is suf.icient f.r overcoming the restrictions f.om quantum f.eld theory. The f.asibility of.this approach is subsequently discussed by 1) introducing the additional conditions needed to ensure that the radial tidal f.rces can indeed be suf.iciently low.and 2) by view.ng traversable w.rmholes as emergent phenomena, thereby increasing the likelihood of.their existence.

关键词： Morris-Thorne w.rmholes Traversability Minimum Requirements Stability Compatibility w.th Quantum f.eld Theory