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Do protostellar fountains shape the regional core mass function?
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作者 Jin-Zeng Li Claudio Carlos Mallamaci +3 位作者 Ricardo César Podest Eloy Actis Vicente Ya-Fang Huang Ana Maria Pacheco 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2013年第6期719-728,共10页
The emerging massive binary system associated with AFGL 961 signifies the latest generation of massive star and cluster formation in the Rosette Molecular Complex. We present the detection of a compact cluster of dust... The emerging massive binary system associated with AFGL 961 signifies the latest generation of massive star and cluster formation in the Rosette Molecular Complex. We present the detection of a compact cluster of dusty cores toward the AFGL 961 region based on continuum imaging at 1.3 mm by the Submillimeter Array. The binary components of AFGL 961 are associated with the most intensive millime- ter emission cores or envelopes, confirming that they are indeed in an early stage of evolution. The other massive cores, however, are found to congregate in the close vicinity of the central high-mass protostellar binary. They have no apparent infrared counterparts and are, in particular, well aligned transverse to the bipolar molecular outflows originating from AFGL 961. This provides evidence for a likely triggered origin of the massive cores. All 40 individual cores with masses ranging between 0.6 and 15 Mo were detected above a 3 σ level of 3.6 mJy beam-1 (or 0.4 M⊙), based on which we derive a total core mass of 107 M⊙ in the AFGL 961 region. As compared to the stellar initial mass function, a shallow slope of 1.8 is, however, derived from the best fit to the mass spectrum of the millimeter cores with a prestellar and/or protostel- lar origin. The flatter core mass distribution in the AFGL 961 region is attributed here to dynamic perturbations from the massive molecular outflows that originated from the massive protostellar binary, which may have altered the otherwise more quiescent conditions of core or star formation, enhanced the formation of more massive cores and, as a result, influenced the core mass distribution in its close vicinity. 展开更多
关键词 stars: formation -- stars: individual (AFGL 961) -- stars: circumstellarmatter -- stars: mass function
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Measurement of hepatic functional mass by means of ^(13)C-methacetin and ^(13)C-phenylalanine breath tests in chronic liver disease: Comparison with Child-Pugh score and serum bile acid levels 被引量:35
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作者 D.Festi S.Capodicasa +9 位作者 L.Sandri L.Colaiocco-Ferrante T.Staniscia E.Vitacolonna A.Vestito R.Simoni G.Mazzella P.Portincasa E.Roda A.Colecchia 《World Journal of Gastroenterology》 SCIE CAS CSCD 2005年第1期142-148,共7页
AIM: To evaluate and compare the clinical usefulness of 13C-phenylalanine and 13C-methacetin breath tests in quantitating functional hepatic mass in patients with chronic liver disease and to further compare these res... AIM: To evaluate and compare the clinical usefulness of 13C-phenylalanine and 13C-methacetin breath tests in quantitating functional hepatic mass in patients with chronic liver disease and to further compare these results with those of conventional tests, Child-Pugh score and serum bile acid levels.METHODS: One hundred and forty patients (50 HCV-related chronic hepatitis, 90 liver cirrhosis patients) and 40 matched healthy controls were studied. Both breath test and routine liver test, serum levels of cholic and chenodeoxycholic acid conjugates were evaluated.RESULTS: Methacetin breath test, expressed as 60 min cumulative percent of oxidation, discriminated the hepatic functional capacity not only between controls and liver disease patients, but also between different categories of chronic liver disease patients. Methacetin breath test was correlated with liver function tests and serum bile acids.Furthermore, methacetin breath test, as well as serum bile acids, were highly predictive of Child-Pugh scores. The diagnostic power of phenylalanine breath test was always less than that of methacetin breath test.CONCLUSION: Methacetin breath test represents a safe and accurate diagnostic tool in the evaluation of hepatic functional mass in chronic liver disease patients. 展开更多
关键词 Chronic hepatitis c Liver cirrhosis Breath Tests Hepatic functional mass
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Disabling hip osteoarthritis: gender, body mass, health and functional status correlates
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作者 Ray Marks 《Health》 2010年第7期696-704,共9页
Objective: To examine gender differences in self-reported pain and function before and after hip replacement surgery and the extent to which overweight, comorbidities and muscular status impact pain and function in ad... Objective: To examine gender differences in self-reported pain and function before and after hip replacement surgery and the extent to which overweight, comorbidities and muscular status impact pain and function in adults with disabling end-stage hip joint osteoarthritis. Setting: Orthopedic Hospital Setting on the East Coast of the United States. Study Design: Cross-sectional retrospective chart review. Methods: The desired demographic, physical and psychological attributes of 1040 adults with end-stage hip osteoarthritis hospitalized for hip surgery were recorded and subjected to comparison and correlational analyses. These data included gender, self-reported weight, height, numbers and nature of physical and psychological comorbidities, pain intensity, ambulatory capacity and discharge destination. Sub-group analyses of 808 candidates hospitalized for primary unilateral surgery were also conducted using SPSS 16. Results: There were significant (p 【0.05) associations between gender, pain scores, comorbidity numbers and ambulatory capacity. Specifically, women who exhibited higher comorbid disease rates than men, exhibited higher pre-surgery pain levels and greater functional limitations in walking ability before and after surgery than men with the same condition. In sub-group analyses of men and women with the same mean age, comorbid prevalence rates, and body mass indices, women were found to have significantly higher ideal weights on average than men, and those with higher ideal weights recovered more slowly after surgery (p 【0.05). Conclusion: The presentation of hip joint osteoarthritis is not uniform, and may be impacted differentially by gender. Women with high ideal body weights, may be specifically impacted. Whether genetic or other factors account for gender differences in pain and function among adults with disabling hip osteoarthritis observation needs to be examined. 展开更多
关键词 BODY mass COMORBIDITY function GENDER HIP Joint OSTEOARTHRITIS
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Analytically determining frequency and amplitude of spontaneous alpha oscillation in Jansen's neural mass model using the describing function method 被引量:1
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作者 Yao Xu Chun-Hui Zhang +1 位作者 Ernst Niebur Jun-Song Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第4期551-558,共8页
Spontaneous alpha oscillations are a ubiquitous phenomenon in the brain and play a key role in neural information processing and various cognitive functions.Jansen's neural mass model(NMM) was initially proposed to... Spontaneous alpha oscillations are a ubiquitous phenomenon in the brain and play a key role in neural information processing and various cognitive functions.Jansen's neural mass model(NMM) was initially proposed to study the origin of alpha oscillations.Most of previous studies of the spontaneous alpha oscillations in the NMM were conducted using numerical methods.In this study,we aim to propose an analytical approach using the describing function method to elucidate the spontaneous alpha oscillation mechanism in the NMM.First,the sigmoid nonlinear function in the NMM is approximated by its describing function,allowing us to reformulate the NMM and derive its standard form composed of one nonlinear part and one linear part.Second,by conducting a theoretical analysis,we can assess whether or not the spontaneous alpha oscillation would occur in the NMM and,furthermore,accurately determine its amplitude and frequency.The results reveal analytically that the interaction between linearity and nonlinearity of the NMM plays a key role in generating the spontaneous alpha oscillations.Furthermore,strong nonlinearity and large linear strength are required to generate the spontaneous alpha oscillations. 展开更多
关键词 neural mass model spontaneous alpha oscillation describing function
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Representation of three-dimensional mass distribution of the Earth's interior by biorthogonal series and its use for studying internal structure of the planet
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作者 Mykhailo Fys Mariana Yurkiv +1 位作者 Andrii Brydun Andrii Sohor 《Geodesy and Geodynamics》 EI CSCD 2024年第3期264-275,共12页
This paper utilizes the mathematical concept of approximation within an ellipsoid from a single viewpoint to present the spatial mass distribution function of the Earth's interior and its internal potential.The pr... This paper utilizes the mathematical concept of approximation within an ellipsoid from a single viewpoint to present the spatial mass distribution function of the Earth's interior and its internal potential.The primary focus lies in constructing the volume distribution of masses in the planet's interior, with the expansion coefficients being linear combinations of the Stokes constants. Several possible approaches are suggested for determining accurately these coefficients employing three-dimensional(biorthogonal)polynomials. By expressing the mass distribution function of the Earth's interior and its internal potential as a series, an algorithm is introduced for the calculation of gravitational energy. It allows us to estimate fluctuations in gravitational energy. The implementation of this algorithm offers the means of establishing the extent to which the Earth deviates from a state of hydrostatic equilibrium as a celestial body.Due to the aforementioned method, calculations have been conducted to validate its effectiveness and reliability. This example is given as an illustration of a given method for studying the internal structure of planets. 展开更多
关键词 mass distribution function Potential Stokes constants Biorthogonal polynomials
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INVESTIGATION ON MAKING MEMBERSHIP FUNCTION OF WATER MASS FROM MIXING MODIFIED PROCESS
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作者 李凤岐 苏育嵩 +1 位作者 喻祖祥 王凤钦 《中国海洋大学学报(自然科学版)》 CAS CSCD 1989年第S1期445-461,共17页
A water mass in the sea area under investigation is defined as a fuzzy subset in the discourse universe. Possible forms of membership function of water masses in the mixing modified process are discussed with the mixi... A water mass in the sea area under investigation is defined as a fuzzy subset in the discourse universe. Possible forms of membership function of water masses in the mixing modified process are discussed with the mixing theory for conservative concentration of sea water. It may provide bases for making membership functions. Results in this paper may be extended and applied to shallow water. Examples and discussion are given in this paper. 展开更多
关键词 water mass fuzzy SETS MEMBERSHIP function the measure-value space
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Effect of body mass index on functional outcomes following arthroplasty procedures
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作者 Gokhan Polat Hasan Huseyin Ceylan +3 位作者 Safak Sayar Fatih Kucukdurmaz Mehmet Erdil Ibrahim Tuncay 《World Journal of Orthopedics》 2015年第11期991-995,共5页
AIM: To evaluate the body mass index(BMI) change in arthroplasty patients and its impact on the patients' functional results. METHODS: Between October 2010 and May 2013, 606 patients who were operated due to gonar... AIM: To evaluate the body mass index(BMI) change in arthroplasty patients and its impact on the patients' functional results. METHODS: Between October 2010 and May 2013, 606 patients who were operated due to gonarthrosis, coxarthrosis, aseptic loosening of the total knee and hip prosthesis were evaluated prospectively. Patients were operated by three surgeons in three medical centers. Patients who were between 30-90 years of age and who were underwent total knee arthroplasty, total hip arthroplasty, revision knee arthroplasty, or revision hip arthroplasty were included in the study. We excluded the patients who cannot tolerate our standard postoperative rehabilitation program. Additionally, patients who had systemic inflammatory diseases, diabetes mellitus, or endochrinopathies were excluded from the study. The remaining 513 patients comprised our study group. Preoperative functional joint scores, height, weightand BMI of all patients were recorded. We used the Knee Society Score(KSS) for knee and Harris Hip Score(HHS) for hip patients. Postoperative functional scores were measured at 1^(st), 6^(th) and 12^(th) months and recorded separately at outpatient visits. RESULTS: The mean age of the patients was 64.7(range: 30-90) years(207 males/306 females) and the mean follow-up duration was 14.3(range: 12-26) mo. We found that arthroplasty patients had weight gain and had an increase in BMI at the postoperative 1^(st), 6^(th) and 12^(th) months. The mean BMI of the patients was 27.7 preoperatively, 27.8 at the postoperative 1^(st) month, 28.1 at the 6^(th) month and 28.6 at the 12^(th) month(P < 0.01). At the last visit, the mean postoperative HHS of the hip arthroplasty patients was 82.2 ± 7.12(preoperatively, 52.3; 1st month, 78.2; 6^(th) month, 81.1; 12^(th) month, 82.2), and the mean KSS of the knee arthroplasty patients was 79.3 ± 4.31(preoperatively, 35.8; 1^(st) month, 75.2; 6^(th) month, 79.1; 12^(th) month, 79.3). Worse functional results were noted in the patients who had a BMI increase, however, this correlation was statistically significant only at the postoperative 6^(th) month(P = 0.03). CONCLUSION: To prevent the negative functional effects of this weight gain during the postoperative period, arthroplasty patients should be advised for weight control and risky patients should consult with a dietician. 展开更多
关键词 Body mass index ARTHROPLASTY OBESITY functional OUTCOMES WEIGHT GAIN
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Optical Functions, Band Structure and Effective Masses of Electrons and Holes in InGaTe<sub>2</sub>
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作者 Eldar Gojaev Ulker Abdurahmanova +1 位作者 Zakir Dzhakhangirli Shafiga Mehdieva 《Open Journal of Inorganic Non》 2014年第2期13-20,共8页
This paper has presented results of calculations of optical functions for e||c and e^c polarizations in 0 - 12 eV energy interval, band structure and effective masses of electrons and holes of ternary compound InGaTe2... This paper has presented results of calculations of optical functions for e||c and e^c polarizations in 0 - 12 eV energy interval, band structure and effective masses of electrons and holes of ternary compound InGaTe2. Genesis of valence band was investigated by using group-theoretical analyses. The main features of spectra of optical functions, the parameters of transition and their theoretical nature were found out. Identified interband transitions are responsible for the main peaks in the optical functions. Calculated results are in good agreement with the known experimental data. 展开更多
关键词 OPTICAL functions Effective mass Band Structure OPTICAL Conductivity Compound InGaTe2
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Heat and Mass Transfer on Non-Newtonian Peristaltic Flow in a Channel in Presence of Magnetic Field: Analytical and Numerical Analysis
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作者 Md. Maruf Hasan Md. Enamul Karim Md. Abdus Samad 《Applied Mathematics》 2024年第8期568-583,共16页
A study has been arranged to investigate the flow of non-Newtonian fluid in a vertical asymmetrical channel using peristalsis. The porous medium allows the electrically conductive fluid to flow in the channel, while a... A study has been arranged to investigate the flow of non-Newtonian fluid in a vertical asymmetrical channel using peristalsis. The porous medium allows the electrically conductive fluid to flow in the channel, while a uniform magnetic field is applied perpendicular to the flow direction. The analysis takes into account the combined influence of heat and mass transfer, including the effects of Soret and Dufour. The flow’s non-Newtonian behavior is characterized using a Casson rheological model. The fluid flow equations are examined within a wave frame of reference that has a wave velocity. The analytic solution is examined using long wavelengths and a small Reynolds number assumption. The stream function, temperature, concentration and heat transfer coefficient expressions are derived. The bvp4c function from MATLAB has been used to numerically solve the transformed equations. The flow characteristics have been analyzed using graphs to demonstrate the impacts of different parameters. 展开更多
关键词 Stream function mass Transfer Vertical Channel Casson Fluid
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New Kinetic Computerized Model for Multicomponent Mass Transfer in Bi-Functional Matrix of NanoComposites
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作者 Anatoliy Kalinitchev 《Advances in Nanoparticles》 2013年第2期191-203,共13页
The aim of this theoretical investigation is the description of the multicomponent mass transfer process in the Nano- Composites (NC)—novel materials with the bi-functional matrix. The new theoretical NC Model is ass... The aim of this theoretical investigation is the description of the multicomponent mass transfer process in the Nano- Composites (NC)—novel materials with the bi-functional matrix. The new theoretical NC Model is assigned for the modern theoretical investigations of the multicomponent mass transfer kinetics in the bi-functional NC materials. This NC Model for the multicomponent mass transfer in the bi-functional NC matrix includes into the consideration the proposed key conception—two co-existing routes: I—chemical reactions onto the active NC centers-sites, and II—diffusion mass transfer inside the bi-functional NC matrix. All the results are presented in the terms of the additional key concept: propagating multicomponent concentration waves (W+) in the NC matrix. The used W+ concept for the description of the multicomponent NC mass transfer kinetics give the clear interpretation of the computerized results. The mass transfer process in the NC matrix has been described theoretically by computerized simulation. The results of the calculations are new and illustrated by author’s animations showing visually the propagation of the multicomponent concentration waves (W) inside the various NC matrixes: r-beads, cylindrical ro-fibers, or planar L-membranes. Two variants of modeling for mass transfer diffusion kinetics in the bi-functional NC matrixes with one (Variant 1), or two (Variant 2) dissociation-association reactions at the active nano-sites (R0) are considered theoretically. 展开更多
关键词 NANOCOMPOSITES mass Transfer Concentration Waves Diffusion MULTICOMPONENT Kinetics Bi-functional MATRIX Active Nano-Sites
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快速mass函数收敛算法 被引量:5
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作者 苗壮 程咏梅 +2 位作者 潘泉 刘准钆 梁彦 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2011年第1期89-92,共4页
DSmT可以很好地解决高冲突证据的组合问题,但是它存在计算量大和主焦元的mass函数难以收敛的问题.针对这些不足,提出快速mass函数收敛算法,在融合过程中只计算辨识框架中单元素形成焦元所占的基本置信指派,并对其做归一化处理,重构mass... DSmT可以很好地解决高冲突证据的组合问题,但是它存在计算量大和主焦元的mass函数难以收敛的问题.针对这些不足,提出快速mass函数收敛算法,在融合过程中只计算辨识框架中单元素形成焦元所占的基本置信指派,并对其做归一化处理,重构mass函数,大大降低了计算量的同时也使mass函数迅速收敛向规定的阈值,以利于快速准确地进行归类判决.计算量的比较和仿真算例证明了该算法的有效性. 展开更多
关键词 归类判决 DSMT mass函数
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基于统计证据的Mass函数和D-S证据理论的多传感器目标识别 被引量:28
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作者 王俊林 张剑云 《传感技术学报》 EI CAS CSCD 北大核心 2006年第3期862-864,共3页
mass函数表示对证据的精确信任程度,是信任函数的基本概率分配。文章在阐述Dempster-Shafer(D-S)证据理论和决策方法的基础上,较系统地论述了基于统计证据的mass函数和D-S证据理论的目标识别的数据融合方法,并给出了具体的识别实例。从... mass函数表示对证据的精确信任程度,是信任函数的基本概率分配。文章在阐述Dempster-Shafer(D-S)证据理论和决策方法的基础上,较系统地论述了基于统计证据的mass函数和D-S证据理论的目标识别的数据融合方法,并给出了具体的识别实例。从计算结果可以看出,该方法有利于目标识别的实现,具有较好的实用性。 展开更多
关键词 mass函数 证据理论 目标识别 多传感器信息融合
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基于目标多特征的mass函数确定方法 被引量:4
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作者 李军 黄力伟 《计算机应用研究》 CSCD 北大核心 2017年第8期2312-2314,共3页
针对D-S证据理论在目标识别中mass函数难以获取的问题,提出一种基于目标多特征的mass函数确定方法。该方法首先利用模糊理论中的隶属函数确定目标的特征隶属度矩阵,然后根据特征隶属度矩阵计算mass函数确定过程中各特征的可信度,最后把... 针对D-S证据理论在目标识别中mass函数难以获取的问题,提出一种基于目标多特征的mass函数确定方法。该方法首先利用模糊理论中的隶属函数确定目标的特征隶属度矩阵,然后根据特征隶属度矩阵计算mass函数确定过程中各特征的可信度,最后把各特征的隶属度值和可信度转换成mass函数。仿真结果表明,该方法获取的mass函数具有很好的可靠性和抗干扰性。 展开更多
关键词 目标多特征 mass函数 模糊理论 隶属函数
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基于熵的Mass函数算法及在液压泵故障诊断中的应用 被引量:4
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作者 江四厚 王汉功 阳能军 《机床与液压》 北大核心 2007年第12期185-187,共3页
如何确定Mass函数是D-S证据理论的棘手问题,本文从信息论的观点出发,提出一种新的计算Mass函数的算法。该算法依据证据体可信度因素和证据体与目标关联的相对熵来分配证据体的Mass函数,较全面反映证据体的不确定性。将方法应用于液压泵... 如何确定Mass函数是D-S证据理论的棘手问题,本文从信息论的观点出发,提出一种新的计算Mass函数的算法。该算法依据证据体可信度因素和证据体与目标关联的相对熵来分配证据体的Mass函数,较全面反映证据体的不确定性。将方法应用于液压泵诊断中,结果表明它获取的Mass函数是符合实际情况的,具有较好的实用性,而且其算法容易实现。 展开更多
关键词 液压泵 D—S证据理论 mass函数 信息熵 故障诊断
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Constraining Mass of M31 Combing Kinematics of Stars,Planetary Nebulae and Globular clusters
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作者 Sunshun Yuan Ling Zhu +2 位作者 Cheng Liu Han Qu Zhou Fan 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2022年第8期270-283,共14页
We construct a multiple-population discrete axisymmetric Jeans model for the Andromeda(M31)galaxy,considering three populations of kinematic tracers:48 supergiants and 721 planetary nebulae(PNe)in the bulge and disk r... We construct a multiple-population discrete axisymmetric Jeans model for the Andromeda(M31)galaxy,considering three populations of kinematic tracers:48 supergiants and 721 planetary nebulae(PNe)in the bulge and disk regions,554 globular clusters extending to~30 kpc,and halo stars extending to~150 kpc of the galaxy.The three populations of tracers are organized in the same gravitational potential,while each population is allowed to have its own spatial distribution,rotation,and internal velocity anisotropy.The gravitational potential is a combination of stellar mass and a generalized NFW dark matter halo.We created two sets of models,one with a cusped dark matter halo and one with a cored dark matter halo.Both the cusped and cored model fit kinematics of all the three populations well,but the cored model is not preferred due to a too high concentration compared to that predicted from cosmological simulations.With a cusped dark matter halo,we obtained total stellar mass of 1.0±0.1×10^(11)M_(☉),dark matter halo virial mass of M_(200)=7.0±0.9×10^(11)M_(☉),virial radius of r_(200)=184±4 kpc,and concentration of c=20±4.The mass of M31 we obtained is at the lower side of the allowed ranges in the literature and consistent with the previous results obtained from the HⅠrotation curve and PNe kinematics.Velocity dispersion profile of the outer stellar halo is important in constraining the total mass while it is still largely uncertain.Further proper motion of bright sources from Gaia or the Chinese Space Station Telescope might help on improving the data and lead to stronger constraints on the total mass of M31. 展开更多
关键词 Galaxy:kinematics and dynamics galaxies:luminosity function mass function Galaxy:evolution
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Long-period eclipsing binaries:towards the true mass-luminosity relation.I.the test sample,observations and data analysis
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作者 Alexei Yu.Kniazev Oleg Yu.Maikov +1 位作者 Ivan Yu.Katkov Leonid N.Berdnikov 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2020年第8期169-176,共8页
The mass-luminosity relation is a fundamental law of astrophysics.We have suggested that the currently used mass-luminosity relation is not correct for the M/M⊙>2.7 range of mass since it was created utilizing dou... The mass-luminosity relation is a fundamental law of astrophysics.We have suggested that the currently used mass-luminosity relation is not correct for the M/M⊙>2.7 range of mass since it was created utilizing double-lined eclipsing binaries,where the components are synchronized and consequently change each other's evolutionary path.To exclude this effect,we have started a project to study longperiod massive eclipsing binaries in order to construct radial velocity curves and determine masses for the components.We outline our project and present the selected test sample together with the first HRS/SALT spectral observations and the software package,FITTING BINARY STARS(FBS),that we developed for the analysis of our spectral data.As the first result,we present the radial velocity curves and best-fit orbital elements for the two components of the FP Car binary system from our test sample. 展开更多
关键词 stars:luminosity function mass function stars:binaries:spectroscopic
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New Probability Distributions in Astrophysics: X. Truncation and Mass-Luminosity Relationship for the Frèchet Distribution
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作者 Lorenzo Zaninetti 《International Journal of Astronomy and Astrophysics》 2022年第4期347-362,共16页
The Frèchet distribution has aided the modelling of scientific data in many contexts. We demonstrate how it can be adapted to model astrophysical data. We analyze the truncated version of the Frèchet distrib... The Frèchet distribution has aided the modelling of scientific data in many contexts. We demonstrate how it can be adapted to model astrophysical data. We analyze the truncated version of the Frèchet distribution deriving the probability density function (PDF), the distribution function, the average value, the rth moment about the origin, the median, the random generation of values and the maximum likelihood estimator, which allows us to derive the two unknown parameters. This first PDF in the regular and truncated version is then applied to model the mass of the stars. A canonical transformation from the mass to the luminosity allows us to derive a new PDF, which is derived in its regular and truncated version. Finally, we apply this new PDF model on the distribution in luminosity of NGC 2362. 展开更多
关键词 Stars: Normal Stars: Luminosity function mass function Stars: Statistics
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Numerical analysis of added mass and damping of floating production,storage and offloading system 被引量:9
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作者 Ke Wang Xi Zhang +1 位作者 Zhi-Qiang Zhang Wang Xu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第3期870-876,共7页
An integral equation approach is utilized to in- vestigate the added mass and damping of floating produc- tion, storage and offloading system (FPSO system). Finite water depth Green function and higher-order boundar... An integral equation approach is utilized to in- vestigate the added mass and damping of floating produc- tion, storage and offloading system (FPSO system). Finite water depth Green function and higher-order boundary ele- ment method are used to solve integral equation. Numeri- cal results about added mass and damping are presented for odd and even mode motions of FPSO. The results show ro- bust convergence in high frequency range and can be used in wave load analysis for FPSO designing and operation. 展开更多
关键词 FPSO. Added mass Damping. Green function Higher-order boundary element method
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Optimization of the Tuned Mass Damper for Chatter Suppression in Turning 被引量:5
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作者 YANG Yiqing LIU Qiang WANG Min 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第6期717-724,共8页
The tuned mass damper(TMD) has been successfully applied to the vibration control in machining, while the most widely adopted tuning is equal peaks, which splits the magnitude of the frequency response function(FRF... The tuned mass damper(TMD) has been successfully applied to the vibration control in machining, while the most widely adopted tuning is equal peaks, which splits the magnitude of the frequency response function(FRF) into equal peaks. However, chatter is a special self-excited problem and a chatter-flee machining is determined by FRF at the cutting zone. A TMD tuning aiming at achieving the maximum chatter stability is studied, and it is formulated as an optimization problem of maximizing the minimum negative real part of FRF. By employing the steepest descend method, the optimum frequency and damping ratio of TMD are obtained, and they are compared against the equal peaks tuning. The advantage of the proposed tuning is demonstrated numerically by comparing the minimum point of the negative real part, and is further verified by damping a flexible mode from the fixture of a turning machine. A TMD is designed and placed on the fixture along the vibration of the target mode after performing modal analysis and mode shape visualization. Both of the above two ttmings are applied to modify the tool point FRF by tuning TMD respectively. Chatter stability chart of the turning shows that the proposed tuning can increase the critical depth of cut 37% more than the equal peaks. Cutting tests with an increasing depth of cut are conducted on the turning machine in order to distinguish the stability limit. The tool vibrations during the machining are compared to validate the simulation results. The proposed damping design and optimization routine are able to further increase the chatter suppression effect. 展开更多
关键词 tuned mass damper frequency response function chatter suppression OPTIMIZATION ~rning
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Techniques of Discrete Function Transfers into Continuous Function in Practice 被引量:1
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作者 Ming-Jong Lin 《Engineering(科研)》 2018年第10期680-687,共8页
One confusing question over a long period of time is how transfer the discrete function transfers into continuous function. Recently the issue has been resolved but some details of the transformation process will be i... One confusing question over a long period of time is how transfer the discrete function transfers into continuous function. Recently the issue has been resolved but some details of the transformation process will be introduced in the paper. The correlation coefficients of 100,000 values are established from the two groups of data with the range between -1 and 1, creating a histogram from these correlation coefficient values known as “the probability mass function.” The coefficient values are brought into the discrete distribution function, so that transfers into the discrete cumulative function, next converted into a continuous cumulative function, next which is differentiated to get the density function, so that it is easy to being research analysis. A model will be established during the process of the conversion what the medium is “the least squares algorithm.” Finally, when the integral of the area within the range of the density function equals to 1, this implies that the transformation complete succeeds from the discrete function to the continuous function. 展开更多
关键词 PROBABILITY mass function DISCRETE CUMULATIVE function Continuous CUMULATIVE function PROBABILITY Density function The Least SQUARES Algorithm
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