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Cepheid Distance to M100 in Virgo Cluster  [PDF]
D. Narasimha,Anwesh Mazumdar
Physics , 1998,
Abstract: A measurement of the distance to Virgo Cluster by a direct method along with a realistic error analysis is important for a reliable determination of the value of Hubble Constant. Cepheid variables in the face-on spiral M100 in the Virgo Cluster were observed with the Hubble Space Telescope in 1994 under the HST Key Project on the Extragalactic Distance Scale. This work is a reanalysis of the HST data following our study of the Galactic Cepheids (in an accompanying communication). The periods of the Cepheids are determined using two independent methods and the reasons for varying estimates are analyzed. The log(period) vs V-magnitude relation is re-calibrated using LMC data as well as available HST observations for three galaxies and the slope is found to be -3.45 +/- 0.15. A prescription to compute correction for the flux-limited incompleteness of the sample is given and a correction of 0 to 0.28 magnitude in V-magnitude for Cepheids in the period range of 35 to 45 days is applied. The extinction correction is carried out using period vs mean (V-I) color and V-amplitude vs (V-I) color at the brightest phase relations. The distance to M100 is estimated to be 20.4 +/- 1.7 (random) +/- 2.4 (systematic) Mpc.
NIR imaging and modeling of the core of M100  [PDF]
J. H. Knapen,R. F. Peletier,I. Shlosman,J. E. Beckman,C. H. Heller,R. S. de Jong
Physics , 1995,
Abstract: High-resolution NIR and optical images are used to constrain a dynamical model of the circumnuclear star forming (SF) region in the barred galaxy M100 (=NGC 4321). Subarcsecond resolution allowed us to distinguish important morphological details which are easily misinterpreted when using images at lower resolution. Small leading arms observed in our K-band image of the nuclear region are reproduced in the gas flow in our model, and lead us to believe that part of the K light comes from young stars, which trace the gas flow.
美国社区创客教育的载体  [PDF]
开放教育研究 , 2015,
Abstract: 美国推进全民创客行动的进程中,非常重视社区创客空间的建设,并积极动员全美各地区、各社区重视将创客行动纳入区域与社区的发展计划,众多社区创客空间明确提出自身所担负的教育责任。基于对美国若干社区创客空间建设目标与运行方式的分析,本文探析了作为社区创客教育主要载体的创客空间的发展动力、功用与应用。研究发现,技术与社会的发展是美国社区创客空间发展的根本动力,全美创客行动的深化实践则是美国社区创客空间发展的基本依托。在功用维度,美国社区创客空间具有培养社区成员创造创新能力、提升社区成员创业就业技能的教育功用,同时又具有创生就业创业机会、促进社区经济发展的经济功用;在应用维度,美国社区创客空间主要通过精心规划功能区支持多样化创客活动、采用适当的运行形式、多途径开展创客教育、多方位促进创客空间高效利用等实现并优化空间的应用。
Oleg Y. Gnedin,Jeremy Goodman,Zsolt Frei
Physics , 1995, DOI: 10.1086/117590
Abstract: Spiral arms, if they are massive, exert gravitational torques that transport angular momentum radially within galactic disks. These torques depend not on the pattern speed or permanence of the arms but only on the nonaxisymmetric mass distribution. Hence the torques can be measured from photometry. We demonstrate this using $gri$ CCD data for M100 (NGC 4321). Since we find consistency among the three bands, we believe that dust and young stars in the arms do not seriously bias our results. If the present epoch is representative, the timescale for redistribution of angular momentum in M100 is $5-10$ Gyr, the main uncertainty being the mass-to-light ratio of the disk.
综合集成研讨厅模型分析  [PDF]
重庆大学学报 , 2009, DOI: 10.11835/j.issn.1000-582X.2009.06.015
Abstract: 以基于网络服务的思想,构建了综合集成研讨厅模型,将专家体系、机器体系、知识体系都以服务的形式加以封装,是对传统研讨模型厅的一种扩展。研究了该研讨厅模型各要素之间的协调运作机制,采用语义网络建立了各要素相互沟通的桥梁,并引入了逻辑推理能力,使得各个参与研讨的角色能够使用语义网络来印证自己观点,最终形成研讨共识。以格拉管线泄漏诊断问题为背景,给出了该研讨厅模型的实现实例。
The Central Region in M100: Observations and Modeling  [PDF]
J. H. Knapen,J. E. Beckman,C. H. Heller,I. Shlosman,R. S. de Jong
Physics , 1995, DOI: 10.1086/176516
Abstract: We present new high-resolution observations of the center of the late-type spiral M100 (NGC 4321) supplemented by 3D numerical modeling of stellar and gas dynamics, including star formation (SF). NIR imaging has revealed a stellar bar, previously inferred from optical and 21 cm observations, and an ovally-shaped ring-like structure in the plane of the disk. The K isophotes become progressively elongated and skewed to the position angle of the bar (outside and inside the `ring') forming an inner bar-like region. The galaxy exhibits a circumnuclear starburst in the inner part of the K `ring'. Two maxima of the K emission have been observed to lie symmetrically with respect to the nucleus and equidistant from it slightly leading the stellar bar. We interpret the twists in the K isophotes as being indicative of the presence of a double inner Lindblad resonance (ILR) and test this hypothesis by modeling the gas flow in a self-consistent gas + stars disk embedded in a halo, with an overall NGC4321-like mass distribution. We have reproduced the basic morphology of the region (the bar, the large scale trailing shocks, two symmetric K peaks corresponding to gas compression maxima which lie at the caustic formed by the interaction of a pair of trailing and leading shocks in the vicinity of the inner ILR, both peaks being sites of SF, and two additional zones of SF corresponding to the gas compression maxima, referred usually as `twin peaks').
研讨厅系统实现方法及技术的研究  [PDF]
系统工程理论与实践 , 2002,
Abstract: ?在研讨厅研究及系统实现的基础上,论述了研讨厅的作用、特点及解决的问题,并提出了研讨厅系统实现的关键问题,包括如何实现从定性到定量,适于研讨厅的研讨过程、研讨模板、面向问题重构的概念和内涵.利用新的计算机技术,构建了一种研讨厅的系统结构及其综合集成系统.
The Effect of Temperature on Mechanical Properties of M100 Concrete  [PDF]
A. Sreenivasulu
American Journal of Engineering Research , 2013,
Abstract: Concrete is generally an excellent fire proofing material. As concrete is exposed to elevated temperature in accidental building fire, an operating furnace, coke oven batteries or a nuclear reactor, its mechanical properties such as Compressive strength, Split tensile strength, Modulus of rupture and Modulus of elasticity for M100 concrete may be decreased reasonably. Since M100 concrete is a relatively a new type of concrete, knowledge about the performance of M100 subjected to fire is limited in comparison with conventional concrete. The behavior of M100 concrete differs from that of Conventional concrete under the same temperature exposure. An attempt has been made in this work to study the effect of elevated temperatures on Compressive strength, Split tensile strength and Flexural strength (modulus of rupture). The cubes of 150 mm side, the beams of 500 mm x 100mm x 100mm and the cylinders of 150mm dia and 300 mm height are used for this study. They were exposed to different temperatures of 50 to 2500 C in intervals of 500C for different durations of 1h, 2h, 3h, 4h and 5hours. After these specimens were heated, they were tested for the above mechanical properties in hot state. The effect of elevated temperature on those properties was observed.
图书馆创客空间建设研究  [PDF]
图书情报工作 , 2013,
Abstract: ?从创客空间的概念、兴起背景、成功案例出发,分析创客空间与图书馆的关系,探讨构建创客空间的要素和步骤。图书馆为创客空间提供孕育发展的平台,创客空间赋予图书馆服务“支持学习”的新内容,为未来图书馆转型提供了切入点。
Kinematics of ionized and molecular hydrogen in the core of M100  [PDF]
J. H. Knapen,I. Shlosman,C. H. Heller,R. J. Rand,J. E. Beckman,M. Rozas
Physics , 1999, DOI: 10.1086/308162
Abstract: We present high angular and velocity resolution two-dimensional kinematic observations in the spectral lines of H alpha and CO J=1-0 of the circumnuclear starburst region in the barred spiral galaxy M100, and compare them with kinematics derived from our previously published numerical modeling. The H alpha data, fully sampled and at sub-arcsecond resolution, show a rotation curve that is rapidly rising in the central ~140 pc, and stays roughly constant, at the main disk value, further out. Non-circular motions are studied from the H alpha and CO data by detailed consideration of the velocity fields, residual velocity fields after subtraction of the rotation curve, and sets of position-velocity diagrams. These motions are interpreted as the kinematic signatures of gas streaming along the inner part of the bar, and of density wave streaming motions across a two-armed mini-spiral. Comparison with a two-dimensional velocity field and rotation curve derived from our 1995 dynamical model shows good qualitative and quantitative agreement for the circular and non-circular kinematic components. Both morphology and kinematics of this region require the presence of a double inner Lindblad Resonance in order to explain the observed twisting of the near-infrared isophotes and the gas velocity field. These are compatible with the presence of a global density wave driven by the moderately strong stellar bar in this galaxy. We review recent observational and modeling results on the circumnuclear region in M100, and discuss the implications for bar structure and gas dynamics in the core of M100 and other disk galaxies.
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