波浪仪器海上比测试验方法研究

波浪测量仪器由于观测对象的随机性和本身工作原理的多样性,很难通过室内实验进行计量检定,而海上试验的进行通常采用仪器比测的方式开展,文中就波浪测量仪器进行实海况仪器比测试验的方法进行了研究和探讨。首先通过严格选取试验环境、选择合适的试验参照仪器并规定统一的试验方法和试验流程,确保比测试验获得的数据具有真实的可比性。然后进一步通过对试验数据的处理和分析,对波浪仪器的准确性、可靠性和稳定性等仪器性能进行了分析,以期对波浪仪器比测试验标准规范的建立提供理论参考。     

A brief history of the development of wind-profiling or MST radars

The history of the development of the wind-profiling or MST radar technique is reviewed from its inception in the late 1960s to the present. Extensions of the technique by the development of boundary-layer radars and the radio-acoustic sounding system (RASS) technique to measure temperature are documented. Applications are described briefly, particularly practical applications to weather forecasting, with data from networks of radars, and scientific applications to the study of rapidly varying atmospheric phenomena such as gravity waves and turbulence.     

单测试质量无拖曳卫星无拖曳及姿态系统仿真及其控制研究

以ASTROD I (Astrodynamical Space Test of Relativity using Optical Devices I,单航天器天文激光动力学)为例介绍无拖曳卫星的结构及其工作原理.推导了其动力学方程,并在此基础上建立了卫星的动力学数值仿真器.将H2最优控制理论运用于以噪声压制为主要目的的无拖曳卫星控制系统的设计,通过传递函数法及数值法双重分析表明所设计的控制器能符合卫星的控制要求,同时表明在控制器设计过程中采用的线性化假设是适当的.     

A wide-field corrector at the prime focus of a Ritchey-Chrétien telescope

We propose a form of a lens corrector at the prime focus of a hyperboloidal mirror that provides a flat field of view up to 3° in diameter at image quality D₈₀<0.8 arcsec in integrated (0.32–1.1 µm) light. The corrector consists of five lenses made of fused silica. All lens surfaces are spherical in shape, so the system is capable of achieving better images, if necessary, by aspherizing the surfaces. The optical system of the corrector is stable in the sense that its principal features are retained when optimized after significant perturbations of its parameters. As an example, we calculated three versions of the corrector for the Blanco 4-m telescope at Cerro Tololo Inter-American Observatory with \(2\mathop .\limits^ \circ 12\), \(2\mathop .\limits^ \circ 4\) and \(3\mathop .\limits^ \circ 0\) fields of view.     

提高地矿单位大型精密仪器设备利用率的探讨

大型精密仪器设备是地矿科研分析单位的重要组成部分,是科技工作者的生产工具,其在一定程度上影响和决定科学研究的质量和深度。本文运用科学学、管理学、经济学和信息学的手段、方法,探讨了对大型精密仪器设备进行科学管理,充分提高大型精密仪器设备的利用率。     

Observations of thermospheric neutral winds within the polar cusp and the auroral oval using a Doppler imaging system (DIS)

Two Doppler imaging systems (DIS) or wide-field imaging Fabry-Perot interferometers (FPI), have recently been commissioned, one at the Auroral Station, Adventdalen, Longyearbyen, Svalbard, and the second at the IRF, Kiruna, Sweden. These instruments can provide wide-field (600 * 800 km) images of neutral wind flows in the upper thermosphere, by measuring the Doppler shift of the atomic oxygen forbidden near 630 nm, which is emitted from an altitude of approximately 240 km. From the instrument in Svalbard, at mid-winter, it is possible to observe the dayside polar cusp and the polar cap throughout the entire day, whereas from Kiruna, the night-time auroral oval is observable during the hours of darkness. Measurements of thermospheric dynamics from the DIS can be used in conjunction with observations of ionospheric plasma flows and thermal plasma densities by the EISCAT-Svalbard radar (ESR) and by EISCAT, along with other complementary observations by co-located instruments such as the auroral large-scale imaging system (ALIS). Such combined data sets will allow a wide range of scientific studies to be performed concerning the dynamical response of the thermosphere and ionosphere, and the important energetic and momentum exchange processes resulting from their complex interactions. These processes are particularly important in the immediate vicinity of the polar cusp and within the auroral oval. Early results from Svalbard in late 1995 will be discussed. The DIS in Kiruna observed two interesting geomagnetic disturbances in early 1997, the minor geomagnetic storm of 10, 11 January, and the disturbed period from 7–10 February. During these events, the thermospheric wind response showed some interesting departures from the average behaviour, which we attribute to the result of strong and variable Lorenz forcing (ion drag) and Joule and particle heating during these geomagnetic disturbances.     

Fishing vessel profitability and local economic link obligations—the case of Norwegian trawlers

This paper investigates to what extent limited entry licence local-link obligations hamper economic performance of Norwegian wet fish trawlers. For 1999 average landing prices, gross revenue, net profit and some other economic indicators are compared for three groups of trawlers: (A) vessels that had local-link licence obligations and complied with them; (B) vessels that had such obligations but did not comply; and (C) vessels without local-link obligations. Average operating profit was highest for Group C. Group B vessels’ operating profit was just above that of Group A, despite significantly higher revenues. For all fish species, except redfish, Group C trawlers received higher prices than the other vessels.