A Low-Sidelobe, High Frequency Corrugated Feed Horn for CMB Observations

We have produced a prototype broadband, low-sidelobe conical corrugated feed horn suitable for measurements of the Cosmic Microwave Blackground (CMB) radiation in the frequency band 120–150 GHz. The antenna is a first prototype for the Low Frequency Instrument array in ESA's PLANCK mission, a space project dedicated to CMB anisotropy mesurements in the 30–900 GHz range. We describe the fabrication method, based on silver electro-formation, and present the two-dimensional antenna beam pattern measured at 140 GHz with a milimeter-wave automated scalar test range. The beam has good symmetry in the E and H planes with a far sidelobe level approaching –60 dB at angles 80°. An upper limit to the return loss was measured to be –21 dB.     

TRIFFID Photometry of Globular Cluster Cores — I. Photometric Techniques and Variable Stars in M15

The Galway/DIAS Image Sharpening Camera, TRIFFID, has been used to make observations in two colours of the centre of the post-core-collapse globular cluster M15. We present here our analysis of the photometry in B over two seasons. We have combined the complementary qualities of the HST 's high astrometric precision and TRIFFID's extended coverage and photometric precision, to perform crowded-field photometry in the innermost region of M15. Our technique virtually eliminates the problem of extreme crowding which has hitherto hampered studies of the variable star populations in globular cluster cores, and thereby provides an extension of the HST 's capability. Candidate variables detected with the HST have been confirmed and monitored over longer periods. We show that most of these are RR Lyrae stars, and that one is a short-period Type II Cepheid (the third to be discovered in M15). Our photometric study also produced evidence of a similar number of new variables. These also appear to be RR Lyrae stars, except for a possible eclipsing system. Further data from an upgraded version of TRIFFID have recently been obtained to help to refine the light curves of all these objects.     

New equipment and processing for magnetotelluric remote reference observations

Robust estimates of magnetotelluric and geomagnetic response functions are determined using the coherency and expected uniformity of the magnetic source field as quality criteria. The method is applied on data sets of three simultaneously recording sites. For the data acquisition we used a new generation of geophysical equipment (S.P.A.M. MkIII), which comprises novel concepts of parallel computing and networked, digital data transmission. The data-processing results show that the amount of noise on the horizontal components of the magnetic field varies considerably in time, between sites and over the frequency range. The removal of such contaminated data beforehand is essential for most data-processing schemes, as the magnetic channels are usually assumed to be free of noise. The standard remote reference method is aimed at reducing bias in response function estimates. However, this does not necessarily improve their precision as our results clearly show. With our method, on the other hand, we can filter out source field irregularities, thereby providing suitable working conditions for the robust algorithm, and eventually obtain considerably improved results. Contrary to previous concepts, we suggest rejecting as much data as feasible in order to concentrate on the remaining parts of high-quality observations.     

Interferometer phase calibration sources — II. The region 0° ≤ δB1950≤ +20°

We present a catalogue of 781 compact radio sources in the declination range 0° ≤ δ_B1950≤ +20° whose positions have been measured to an rms accuracy of about 14 mas with the Very Large Array (VLA). These sources are primarily intended for use as phase calibration sources for the Jodrell Bank MERLIN. However, they will also be suitable as phase calibrators for the VLA and can be considered as candidate phase calibrators for very long-baseline interferometry (VLBI) networks.     

四湖排水系统运行规划优化模型

分析了四湖排水系统的运行特点,应用大系统理论对系统进行了递阶分析并确定了该系统运行规划的NLP/DP/LP优化模型结构。在确定系统运行规则的基础上,分层建立了系统运行规划优化模型。     

1991年夏季持续性异常环流的共轭敏感性分析

在共轭敏感性分析的基础上发展了最敏感扰动的概念。用共轭模式对江淮流域大水1991年东亚夏季环流的持续异常特征,包括乌拉尔阻塞高压、鄂霍次克海偶极子型阻塞以及副热带高压的变动过程进行了分析,分别得到了对这些过程影响最大的初始扰动。结果从新的角度揭示了这些系统最重要的影响因子,也显示了共轭敏感性分析方法在大气环流物理过程诊断中的有效性和应用前景。     

矿产资源的最适耗竭与可持续发展

为了能使矿产资源可持续利用与发展,解决矿产资源市场需求与资源节约利用需求的矛盾,从矿产资源可持续发展实质研究入手,利用利导因子和限制因子互为制约的关系以及矿产资源发展的阶段特性,确定矿产资源发展曲线,建立矿产资源可持续发展机制。通过对最佳开采速度静态模型和动态模型的研究,认为最佳开采速度是影响矿产资源最适耗竭能否实现的关键因素,以此确定系统函数关系和系统变量。运用最适耗竭理论中的最佳开采速度和福利函数,建立矿产资源最适耗竭模型,以实现矿产资源可持续利用与发展。     

NAOC 1m反射望远镜CCD相机的性能研究

研究了国家天文台兴隆观测基地1m反射望远镜新安装的VersArray1340×1300BCCD照相机的性能。它有几乎没有图案的良好本底（bias），极低的读出噪声和暗流。用平场序列露光来检测其线性时，能得到线性良好的转移曲线（transfercurve）。但是，不论在平场露光（面光源）还是在恒星（点光源）的观测中，当像元值约高于55000adu时（增益3．7e^-／adu），都会产生溢出。此时CCD并未满井。因此，使用它做点扩散函数分析研究时，要避免使用太亮的星像。不过，由于电荷守恒原理，对产生溢出的孤立亮星像，仍然可以做孔径测光。此外，该相机的快门函数也已测定。     

New INTEGRAL sources and TeV emission

INTEGRAL is operational since more than three years and producing high quality data that allows to detect fainter new hard X-ray sources. The new sources, identified until now, are mostly active galactic nuclei and absorbed or transient high mass X-ray binaries. TeV emission could be expected from the new high mass X-ray binaries accreting dense clumps of stellar wind. INTEGRAL sources with TeV counterparts are discussed. Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic and Poland, and with the participation of Russia and the USA.     

Streamflow estimation using optimal regional dependency function

The determination of spatial dependency of regionalized variable (ReV) is important in engineering studies. Regional dependency function that leads to calculation of weighting coefficients is required in order to make regional or point‐wise estimations. After obtaining this dependency function, it is possible to complete missing records in the time series and locate new measurement station. Also determination of regional dependency function is also useful to understand the regional variation of ReV. Point Cumulative Semi‐Variogram (PCSV) is another methodology to understand the regional dependency of ReV related to the magnitude and the location. However, this methodology is not useful to determine the weighting coefficient, which is required to make regional and point‐wise estimations. However, in Point Semi‐Variogram (PSV) proposed here, weighting coefficient depends on both magnitude and location. Although the regional dependency function has a fluctuating structure in PSV approach, this function gradually increases with distance in PCSV. The study area is selected in Mississippi river basin with 38 streamflow stations used for PCSV application before. It is aimed to compare two different geostatistical models for the same data set. PSV method has an ability to determine the value of variable along with optimum number of neighbour stations and influence radius. PSV and slope PSV approaches are compared with the PCSV. It was shown that slope slope point semi‐variogram (SPSV) approaches had relative error below 5%, and PSV and PCSV methods revealed relative errors below 10%. Copyright © 2009 John Wiley & Sons, Ltd.