基于以太网的射电天文制冷接收机的监视系统

制冷接收机是射电望远镜的核心设备,它是否正常工作直接决定望远镜观测的效果。制冷接收机的制冷温度和杜瓦真空度是反映接收机是否正常工作的最重要、最直接的指标之一。因此实现制冷接收机制冷温度和杜瓦真空度的远程实时监控,及时了解接收机是否正常工作对保证射电望远镜正常运行、提高观测效率有重要意义。为乌鲁木齐天文站25m射电望远镜1.3cm制冷接收机研制的一套基于单片机和以太网的数据采集和数据传输的远程监视系统,实现了制冷接收机制冷温度和杜瓦真空度的远程实时监控。该系统采用了美国ATMEL公司生产的8位单片机AVR ATmega16、Microchip Technology公司生产的ENC28J60以及MAXIM公司生产的MAX7219,实现对射电天文制冷接收机制冷温度和杜瓦真空度的数据采集,并利用以太网传输数据实现了远程实时监控接收机的制冷状态。阐述了以太网数据采集及远程监控电路的设计原理及其实现方法。该系统首次在国内大型射电望远镜上实现了对制冷接收机工作状态的远程实时监控,对于保证乌鲁木齐天文站25m射电望远镜1.3cm波段的观测效果有重要作用。     

嵌入式TCP/IP协议在接收机杜瓦性能参数监测系统中的应用

介绍了射电天文望远镜接收机杜瓦温度与真空度监测系统的设计,具体讨论了监测系统的硬件结构与嵌入式TCP/IP协议在该系统中的实现.针对目前大量使用8位微控制器的嵌入式系统,硬件主控系统芯片采用ATMEL公司生产的8位单片机ATmega16,网络控制芯片采用美国MICROCHIP公司生产的带SPI接口的独立以太网微控制器ENC28J60,设计实现了低成本、高效率、高稳定性的性能参数监测系统.对该系统进行测试分析、数据比对,测试结果表明该系统能够高效与PC机进行通信,PC机所接收到的温度值与标准数据的误差在±0.3 K范围内,接收到的真空值绝对误差在±10 ubar范围内,能够达到系统设计要求.     

FAST促动器性能测试在线监测系统

根据FAST主动反射面需求评估了对促动器性能的要求,依促动器评估参数需求设计了针对电流、功率、温度、负载、位移、限位信号的监测系统,确定各监测信号传感器选型,完成监测系统的组装制作,并将其应用于实验,实现促动器的在线监测功能以及促动器无人值守实验,针对以往促动器实验时人工巡检故障的离线监测有很大改进,在精度以及历史信息记录上都有质的提高,进行了长期的促动器调试与监测.     

制冷HEMT低噪声放大器偏置电源的研制

高电子迁移率晶体管(HEMT)目前被广泛应用于高灵敏度(低噪声)射电天文接收机中. 在低温制冷环境下,其低噪声性能更佳,但对偏置供电系统要求很高,只有在特定的偏置条件下才能得到最佳的低噪声、高增益、高稳定性.本文提供了一套可调试、高稳定、高可靠性、带远程监控功能的可供多级低温制冷HEMT管的偏置电源的设计思路、方法和制作,使在低温制冷状态下的HEMT管能够稳定、安全、可靠地工作在最佳状态.     

一套小型化杜瓦的机械结构

随着天文实测的发展,对小型化杜瓦出现了一定需求.本文介绍了我们新设计的一套小型化半导体制冷杜瓦,给出了机械设计的要点,可供有兴趣的同行参考.     

明安图射电频谱日像仪高频阵模拟接收机研制

介绍了明安图射电频谱日像仪高频阵模拟接收机总体设计方案和研制情况,详细说明所采用的光传输、温控、滤波、LTCC等技术以及针对射电日像仪阵列特别采取的可靠性保证措施。经过全面的系统指标测试和幅、相稳定性温度环境测试,结果表明模拟接收机系统的性能、功能和稳定性等指标满足总系统的设计要求。     

天文用热电制冷杜瓦的一种实现

杜瓦是天文观测终端设备重要的部件。本文总结了我们研制二级热电制冷杜瓦中的一些重要经验 ,其恒温点依不同的系统可以改变 ,方法可供有兴趣的同行参考。试验表明 ,这套系统温控精度能达到± 0 .1℃     

KAGRA引力波探测器中蓝宝石测试镜光学性质研究

低温制冷技术是下一代激光干涉仪引力波探测器的核心技术之一. 日本引力波探测器KAGRA (Kamioka Gravitational Wave Detector)作为该技术的前沿开拓者, 将运行在20K的超低温环境中, 并使用在低温下热噪声较低的单晶蓝宝石晶体作为测试镜. 然而, 高质量大尺寸低吸收率的蓝宝石晶体极难制备. 此外, 由于蓝宝石晶体存在晶格结构不均匀, 很容易导致不必要的双折射效应, 从而影响探测器的目标灵敏度. 基于上述问题, 开发了两套大尺寸光学测量系统, 首次系统研究了KAGRA低温蓝宝石测试镜的光学特性. 首先, 根据探测器对测试镜热噪声的要求, 开发了一套基于光热共光路干涉技术的光学测量系统, 该系统可对测试镜以及测试镜表面涂层的光学吸收进行有效的表征. 其次, 基于光学吸收测量系统, 开发了一套双折射效应测量系统, 该系统可以有效表征测试镜中双折射的均匀性. 目前两套测量系统的搭建与调试已完成, 对蓝宝石测试镜光学吸收的测量灵敏度达到了1.5ppm/cm, 双折射测量系统的空间分辨率小于0.3mm times 0.3mm. 该工作对降低大尺寸低温测试镜双折射效应及提高探测器灵敏度具有重要意义.     

一种天文用CCD相机的电路设计

简述了一种面向天文应用的CCD相机系统的设计要求,详细介绍了该相机系统电路的基本结构及设计原则,包括CCD及其周边电路、模拟前端、时钟驱动电路、电源电路以及用VHDL编写的植入FPGA的CCD时序发生器电路等一些技术细节.对系统中一些关键电路模块进行了仿真和实测,并对仿真和测试结果进行比较分析,最后给出该CCD相机的图像采集结果.     

2.4m望远镜摄谱仪狭缝监视系统

为了实现对云南天文台2.4m望远镜摄谱仪狭缝的远程监视,我们以CPLD为核心设计了CCD控制器,用PC-104嵌入式计算机采集图像,利用pcAnywhere软件实现远程数据传输,以较低的成本设计制作了一套狭缝监视系统。该系统目前已经通过测试,达到了狭缝监视的基本要求,并为下一步实现自动导星和Robotic观测打下了基础。本文详细介绍了该系统的软硬件设计和测试结果。     

Study of a Particular Model of Encounter Between a Comet and a Planet

The objective of this paper is to develop a simple model of an encounter between a comet and a planet, with a subsequent capture or an escape, and to study the potential consequences. The hypothetical scenario is as follows: a comet with a conic orbit meets close to one of its vertices (located near the ecliptic plane), a jovian planet, and transforms its orbit. There are two hypotheses which are made for the shock: this vertex becomes one of the final vertices and the orbital plane of the comet is unchanged during the encounter as it was the case for Brooks 2 in 1886. In this model, it was able to find an equation which was then used to obtain the pre‐ and post‐encounter orbits elements and the kind of orbit (ellipse, hyperbola, parabola) with respect to the initial inclination. The numerical experiments with the observed comets often provide pre‐encounter orbits with an aphelion point located near another jovian planet farther from the Sun, and so on with sometimes several planets, or with an aphelion point located beyond the Pluto orbit. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dynamics of a particle in a gravitational field of a homogeneous annulus disk

We formulate the problem of an infinitesimal particle moving in the space under the influence of the gravitational force induced by a homogeneous annulus disk fixed on a plane. We compute using different coordinates and in terms of an elliptic integral the potential associated to this problem. Also we study the symmetries of the associated potential. After that, we look at the dynamics in some particular cases, namely: in the line perpendicular to the plane that contains the annulus disk and passes through the center of the ring and on the plane that contains the massive annulus.      

Evolution of a binary system consisting of a helium star and a white dwarf

Results of evolutionary calculations for a close binary system with a central helium burning He-star filling its Roche lobe and an accreting white dwarf are presented. Values for the mass of the components and the degree of central helium exhaustion before the filling of the Roche lobe are varied. It is shown that in such a system the mass accretion rate will remain for a long time (2–4) Ö 10^–8 yr^–1 ifq<1 (q=M _He,2/M _CO,1). The obtained results are discussed in connection with pre-supernova I phenomenon.     

The formation of a ring galaxy during a head-on collision between a disk and a spherical galaxy

The tidal force effects of a spherical galaxy passing head-on through a disk galaxy have been studied at various regions of the disk galaxy and for various orientations of the disk galaxy with respect to the direction of relative motion of the two galaxies. The density distribution of the disk galaxy is taken to be, (r)=_ce^–4r/R , where _c is the central density andR is the radius of the disk. The density distribution of the spherical galaxy is taken to be that of a oolytrope of indexn=4. It is found that as a result of the collision, through the central parts and the outer parts of the disk galaxy remain intact, the region in between these two regions disrupts. Thus a ring galaxy with a nucleus embedded in the ring-i.e., a ring galaxy of the RN-type, is formed.     

Structure of the clusters of galaxies a 999, a 1016, and a 1142

The hierarchical structure of the clusters of galaxies A 999, A 1016, and A 1142, which are part of one supercluster, is investigated. The HTree method is used to determine that A 999 and A 1016 are a single, dynamically bound system consisting of two “cores” and a common field of galaxies. The composition of the “cores” includes almost all the E and S0 galaxies, the luminosity function of which is very nearly Gaussian. It is also established that the cluster A 1142 has a nonuniform structure, both in density distribution and in radial velocity distribution. The location of the maxima in density and in the radial velocity distribution correlates with the galaxies that are sources of radio and x-ray emission. Translated from Astrofizika, Vol. 43, No. 1, pp. 45-54, January–March, 2000.     

Production of a short-lived filament by a surge

A large surge was observed on September 17, 1971, part of which, after travelling 200 000 km through the corona, returned to the surface to form a filament. The filament lasted about 30 min, then rose up and returned to the source of the surge. We interpret this as the filling of a semi-stable magnetic trap.The energetics of radio, X-ray, and surge expulsion are estimated. The radio spectrum and flux correspond to a thermal source of area 4 (arcmin)², T 190 000 K, N _e ² V 7 × 10⁴⁸, which is optically deep at 8800 MHz.The soft X-ray source has T 12 × 10⁶ K, N _e ² V 3 × 10⁴⁸; and if an equal mass is expelled in the surge, the kinetic energy of the surge is similar to the thermal energy of the X-ray source.     

Toward a model of a two-component solar cycle

In a two-component cycle, the generation of the dipole field by a separate mechanism as well as the strong link occurring, with a 5–6-yr delay, between the sunspot cycle and the preceding dipole cycle, sets in new terms the problem of the mechanisms at the origin of the solar cycle. In this paper, from various series of synoptic solar data, we identify some of the mechanisms to incorporate in a model of a two-component solar cycle. The first one concerns the dipole field which is not a surface phenomenon. We establish the cyclic behaviour and the various properties of the dipole-field sources which are deep-seated in the solar interior and have a rigid rotation of about 27 days. We identify two cyclic phenomena which, in each hemisphere, link with a 5–6-yr delay, the dipole field generation which occurs at high latitudes, to the bipolar field emergence occurring at sunspot latitudes. They are the signatures of a coupling mechanism taking place deep in the solar interior. Then we study the constraints imposed on the mechanisms of the sunspot field generation both by a two-component cycle and by new observational results. These last ones concern the links occurring between the birth of new sunspot groups and the occurrence of pre-existing features of the photospheric field and of pivot-points in rigid rotation at 27.3 days.Our final discussion is devoted to a first sketch of the distribution of the relevant mechanisms among separate regions of the convective zone. Unfortunately neither the helioseismology, nor our data analysis has yet supplied us with appropriate pieces of information for building a physical model of this two-component cycle.     

Dynamical properties of a centrifugally driven outflow from a disc near a black hole

The inclination of the field lines at the surface of the disc plays a crucial role on the nature of the magnetically driven flows. For the non-relativistic case, a centrifugally driven outflow of matter from the disc is possible, if the poloidal component of the magnetic field makes an angle of less than a critical 60° with the disc surface (Blandford and Payne 1982). We investigate the dynamical properties of the magnetically driven flows from the disc near a non-rotating black hole and find that the critical angle becomes larger than 60° when the flows start from the region near the black hole.