激光垂准仪一测回垂准测量标准偏差校准的精度分析

根据JJF1081-2002《垂准仪校准规范》的规定,采用测量不确定度A类或B类评定方法,在观测条件正好处于合格条件的临界状态的情况下,对垂准仪一测回垂准测量标准偏差校准的测量不确定度进行评定,并给出垂准仪在实际使用中一测回垂准测量标准偏差的预警值。     

FAH方法与气体敏化方法的对比

我们使用上海天文台的敏化实验室,用同一批号的同盒底片,对比研究了气体敏化方法和BAH方法对几种常用柯达天文底片的效果。结果表明,BAH方法虽然不象原提出者所说的那样理想,但它不失为一种简便易行的好方法。 我们还研究了把气体敏化方法和FAH方法结合的问题。看来,对于某些品种底片,结合是有希望的。     

对NJS-Ⅱ型计算机组成实验仪的改进

介绍了改进后的NJS－Ⅱ型计算机组成实验仪，从而使用户掌握微程序控制计算机的基本设计方法和调试方法，增强动手能力。     

Evaluation of saltation flux impact responders (Safires) for measuring instantaneous aeolian sand transport intensity

The measurement of aeolian sand transport rates on small scales is of interest to the development and testing of detailed models of sand movement by wind. This paper reports on laboratory evaluations and preliminary field tests of a new design of a piëzo-electric impact responder, called a ‘Safire’, capable of measuring saltation impacts at a frequency of 20 Hz. The advantages of the Safire are: (1) that it provides high-frequency measurements, (2) that it presents a minimal obstruction to the wind flow (no scour observed in the field), and (3) that it is of a (relatively) low-cost.Laboratory calibrations were performed with a vertical gravity flume generating known sand grain fluxes using both mixed sand and specific size fractions. Initial tests investigated three fundamental characteristics: correspondence between digital and analogue signals generated by the instrument, directional response of the probe, and linearity of instrument response to mass flux.Instrument calibration included determination of the momentum threshold required for the sensor to register a grain impact. Based on this lower limit and the known distribution of grain size and speed at different fall heights, a prediction is made as to the sand grain flux the Safire ought to measure, which is then compared with the signal response. The result of this comparison is an assessment of the instrument's efficiency in counting saltating grains. These Safires were also deployed in the field as part of a larger investigation of spatio-temporal transport variability. This experiment provided the opportunity to compare the instrument's performance with traditional sand traps, and this paper develops methods and assumptions required to convert measurements from impact responders to traditional mass transport rates.The evaluations indicate that improvements to the instrument production process are required to ensure a standard momentum threshold among individual instruments. Furthermore, the sensor design needs to be reconsidered in order to eliminate the variation in response depending on azimuth direction, so that the sensor is uniformly omni-directional.     

Determination of gas bubble fractionation rates in the deep ocean by laser Raman spectroscopy

A new deep-sea laser Raman spectrometer (DORISS—Deep Ocean Raman In Situ Spectrometer) is used to observe the preferential dissolution of CO₂ into seawater from a 50%–50% CO₂–N₂ gas mixture in a set of experiments that test a proposed method of CO₂ sequestration in the deep ocean. In a first set of experiments performed at 300 m depth, an open-bottomed 1000 cm³ cube was used to contain the gas mixture; and in a second set of experiments a 2.5 cm³ funnel was used to hold a bubble of the gas mixture in front of the sampling optic. By observing the changing ratios of the CO₂ and N₂ Raman bands we were able to determine the gas flux and the mass transfer coefficient at 300 m depth and compare them to theoretical calculations for air–sea gas exchange. Although each experiment had a different configuration, comparable results were obtained. As expected, the ratio of CO₂ to N₂ drops off at an exponential rate as CO₂ is preferentially dissolved in seawater. In fitting the data with theoretical gas flux calculations, the boundary layer thickness was determined to be  42 μm for the gas cube, and  165 μm for the gas funnel reflecting different boundary layer turbulence. The mass transfer coefficients for CO₂ are k_L = 2.82 × 10^− 5 m/s for the gas cube experiment, and k_L = 7.98 × 10^− 6 m/s for the gas funnel experiment.     

ST radar observations of atmospheric waves over mountainous areas: a review

Lee and mountain waves are dominant dynamic processes in the atmosphere above mountain areas. ST VHF radars had been intensively used to investigate these wave processes. These studies are summarized in this work. After discussing features of long-period quasi-stationary lee waves, attention is drawn to the frequent occurrence of freely propagating waves of shorter periods, which seem to be more common and characteristic for wave processes generated over mountainous areas. Characteristics of these waves such as their relation to the topography and background winds, the possibility of trapping by and breaking in the tropopause region and their propagation into the stratosphere is investigated. These orographically produced waves transport energy and momentum into the troposphere and stratosphere, which is considered an important contribution to the kinetic energy of the lower atmosphere. The occurrence of inertia-gravity waves in the stratosphere had been confused with lee waves, which is discussed in conclusion. Finally further questions on mountain and lee waves are drawn up, which remain to be solved and where investigations with ST radars could play a fundamental role.     

高频大地电磁仪一致性试验研究

用新老两台高频大地电磁仪,在同一测点上进行一致性试验研究.结果表明：新款仪器在50Hz频率的陷波能力较强,老款仪器陷波能力相对较弱.在200～63100Hz频段上两台仪器一致性较好.两台仪器在同一测点同时观测时相互之间存在干扰.     

Scaling,analysis and new instrumentation for dynamic bed tests: The SANDS-Hydralab III papers

This special issue presents the main research results from the SANDS project in Hydralab-III, a research project of the European Union. The papers review the scaling and design of mobile bed tests, the role and limits of conventional and new instrumentation and the extrapolation to full scale. The project has focused on innovative systems of opto-acoustic instrumentation, able to recover water and sediments fluxes at an unprecedented level of accuracy and resolution. The research also included large scale experiments at different scales and a critical comparison of experimental and numerical results to improve the state of the art in Coastal Engineering.     

全数字化自相关射电频谱仪观测分子谱线成功

鉴于分子天文学对研究银河系结构、恒星诞生和演化、宇宙化学及宇宙生命等方面有极其重要的意义,近年来国内不仅在这个领域的理论研究有迅速发展,而且积极进行着实测手段的建设.其中,用于谱线观测的射电频谱仪先后确定采用的数种技术方案,均已进行研制并已在实验室调测.然而因种种技术上的考虑,原来并没有打算采用国外已广泛使用的全数字化自相关射电频谱仪.     

Mars environment and magnetic orbiter model payload

Mars Environment and Magnetic Orbiter was proposed as an answer to the Cosmic Vision Call of Opportunity as a M-class mission. The MEMO mission is designed to study the strong interconnections between the planetary interior, atmosphere and solar conditions essential to understand planetary evolution, the appearance of life and its sustainability. MEMO provides a high-resolution, complete, mapping of the magnetic field (below an altitude of about 250 km), with an yet unachieved full global coverage. This is combined with an in situ characterization of the high atmosphere and remote sensing of the middle and lower atmospheres, with an unmatched accuracy. These measurements are completed by an improved detection of the gravity field signatures associated with carbon dioxide cycle and to the tidal deformation. In addition the solar wind, solar EUV/UV and energetic particle fluxes are simultaneously and continuously monitored. The challenging scientific objectives of the MEMO mission proposal are fulfilled with the appropriate scientific instruments and orbit strategy. MEMO is composed of a main platform, placed on a elliptical (130 × 1,000 km), non polar (77° inclination) orbit, and of an independent, higher apoapsis (10,000 km) and low periapsis (300 km) micro-satellite. These orbital parameters are designed so that the scientific return of MEMO is maximized, in terms of measurement altitude, local time, season and geographical coverage. MEMO carry several suites of instruments, made of an ‘exospheric-upper atmosphere’ package, a ‘magnetic field’ package, and a ‘low-middle atmosphere’ package. Nominal mission duration is one Martian year.