VAX计算机及图象系统硬磁盘扩充     

关忠仁  吴士达  杨立新  游思琼 《成都信息工程学院学报》1992,(3)

本文介绍了为VAX计算机系统扩充硬磁盘以及为ARIES-Ⅱ图象处理系统建立图象伪磁盘的方法及步骤。  相似文献   

Kinematics and parameters of the gas in the vicinity of TW Hya     

S. A. Lamzin  A. S. Kravtsova  M. M. Romanova  C. Batalha 《Astronomy Letters》2004,30(6):413-427

The following conclusions about the kinematics and parameters of the gas in the vicinity of TW Hya have been drawn from an analysis of optical and ultraviolet line profiles and intensities. The accreting matter rises in the magnetosphere to a distance z>R_* above the disk plane and falls to the star near its equator almost perpendicular to its plane. The matter outflows from a disk region with an outer radius of ≤0.5 AU. The [OI], [SII], and H2 lines originate in the disk atmosphere outside the outflow region, where the turbulent gas velocity is close to the local speed of sound. In the formation region of the forbidden lines, T?8500 K and N_e?5×10⁶ cm^?3, and the hydrogen is almost neutral: x_e<0.03. The absorption features observed in the blue wings of some of the ultraviolet lines originate in the part of the wind that moves almost perpendicular to the disk plane, i.e., in the jet of TW Hya. The V _z gas velocity component in the jet decreases with increasing distance from the jet axis from 200 to 30 km s^?1. The matter outflowing from the inner disk boundary, moves perpendicular to the disk plane in the formation region of blue absorption line components, at a distance of ～0.5 AU from the axis of symmetry of the disk. This region of the wind is collimated into the jet at a distance of <3 AU from the disk plane. The gas temperature in the formation region of absorption components is ?2×10⁴ K, and the gas density is <3×10⁶ cm^?3. This region of the jet is on the order of several AU away from the disk plane, while free recombination in the jet begins even farther from the disk. The mass-loss rate for TW Hya is \(\dot M_w < 7 \times 10^{ - 10} M_ \odot yr^{ - 1}\), which is a factor of 3lower than the mean accretion rate. The relative abundance of silicon and aluminum in the jet gas is at least an order of magnitude lower than its standard value.  相似文献   

Possible variability of the magnetic field of T Tau     

D. A. Smirnov  S. A. Lamzin  S. N. Fabrika  G. A. Chuntonov 《Astronomy Letters》2004,30(7):456-460

Using the Main Stellar Spectrograph of the 6-m Special Astrophysical Observatory telescope equipped with a polametric analyzer, we measured the longitudinal magnetic field component B_∥ for the T Tauri stars T Tau and AS 507 on January 16 and 18 and February 15, 2003. For both stars, we determined only the upper limits on B_∥ from photospheric lines: +15±30 G for T Tau and ?70±90 G for AS 507. The magnetic field of AS 507 was not measured previously, while B_∥ for T Tau is lower than its values that we obtained in 1996 and 2002 (B_∥?150±50G), suggesting that the longitudinal magnetic field component in the photosphere of T Tau is variable. We also measured the longitudinal magnetic field component for T Tau in the formation region of the He I 5876 Å emission line. We found B_∥ in this region to be ?+650, ?+350, and ?+1100 G on January 16, 18, and February 15, 2003, respectively. Our observations on January 18 and February 15 correspond to virtually the same phase of the star's rotation period, but the profiles of the He I 5876 Å line differ markedly on these two nights. Therefore, we believe that the threefold difference between the B_∥ values on these nights does not result from observational errors. We discuss the possible causes of the B_∥ variability in the photosphere and the magnetosphere of T Tau.  相似文献   

Energy release during disk accretion onto a rapidly rotating neutron star     

N. R. Sibgatullin  R. A. Sunyaev 《Astronomy Letters》2000,26(11):699-724

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含粘滞和磁场的薄吸积盘不稳定性     

杨兰田  丁世学  吴学兵  谢光中 《中国天文和天体物理学报》1994,(4)

本文采用微扰方法导出色散方程，并在四种情况下详细讨论了薄吸积盘的不稳定性。结果表明：在纯粘滞和纯磁场盘中都存在脉动不稳定性。而且在吸积盘内同时考虑粘滞和磁场时，存在两种不稳定性，一种是脉动不稳定性，另一种是单调不稳定性。同时数值计算还表明，脉动不稳定性更可能存在于盘的内区，而单调不稳定性则只在盘的外区，对短波扰动才有意义。这些结果为解释ＢＬＬａｃ天体、Ｓｅｙｆｅｒｔ星系及类星体等活动星系核的光变现象进一步提供了理论依据。  相似文献   

含粘滞的弱磁化吸积盘的非轴对称脉动不稳定性   总被引：1，自引：0，他引：1  

汪定雄  杨兰田 《天文学报》1997,38(3):250-256

本文讨论了一种含扩散型粘滞的弱磁化等温吸积盘模型．在作者原有工作的基础上研究了吸积盘对非轴对称扰动（含径向、环向和垂向三个方向的扰动）所表现的脉动不稳定性．结果表明，径向扰动是最重要、最根本的扰动：在无径向扰动时，吸积盘中不存在环向扰动与垂向扰动所产生的脉动不稳定性．在径向扰动存在时，吸积盘除了可能存在纯径向脉动不稳定性外，还可能存在由于径向扰动与垂向扰动的耦合所引起的轴对称脉动不稳定性，以及由于径向扰动与环向扰动的耦合所引起的非轴对称脉动不稳定性．当上述三个方向的扰动并存时，对应的非轴对称脉动不稳定性也可能存在．  相似文献   

一个实现大规模存储的方案     

高华  陈敏  余东昌 《气象科技》2013,41(6):1026-1030

基于廉价磁盘冗余阵列（RAID）方法和逻辑卷管理（LVM）工具,将一台机架式服务器和五台磁盘阵列进行连接管理,实现了一种单一逻辑磁盘容量达90 TB的大规模存储空间。该方案注重了系统的稳定性和数据的安全性。磁盘阵列采用串联方式,增强了可扩展性,理论上可以无限扩展。实际应用表明,该方案方便了数值预报业务数据的安全、快速存取,并具有容量的可扩展性。满足了省级气象部门对科研数据存储的需求,尤其是数值预报结果检验工作对大规模存储的需求。  相似文献   

吸积盘随机振荡光度功率谱密度中低频准周期振荡现象的研究     

陈培杰  汪志云 《天文研究与技术》2022,(1)

采用含有频率涨落噪声和指数形式关联随机力作用的广义朗之万(Langevin)方程模型描述黑洞吸积盘的垂向振荡,推导出吸积盘随机振荡光度功率谱密度的解析表达式,并讨论了系统参数对功率谱密度中低频准周期振荡(Low Frequency Quasi-Periodic Oscillations,LFQPOs)现象的影响。研究结果发现选取合适的系统参数时,功率谱密度曲线上出现了一个基频和一个二次谐频的共振双峰低频准周期振荡,基频峰对应的中心频率为吸积盘振荡的特征频率;随机力关联时间决定了基频峰的高度和宽度,频率噪声强度和粘滞阻尼只对二次谐频峰产生影响。结果说明吸积盘的随机振荡模型可以作为低频准周期振荡起源的一种解释。  相似文献   

A new insight into changes in protoplanetary disk structure caused by change in stellar mass     

《New Astronomy》2022

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