一种提高热电阻测温准确性方法研究

分析了工业铂、铜热电阻电阻-温度特性,以工业铂电阻温度传感器为例,给出了一种提高热电阻测温准确度的方法。通过对工业铂电阻进行多点测试,利用最小二乘法对测得数据进行拟合,得出新的电阻-温度转换公式和分度表。通过试验数据的比较表明,使用该方法可以提高传感器的测温准确性。     

At－1型全自动测温电桥

Ａｔ－１型全自动测温电桥金俊成，王吉新，魏以嘉１引言１９９０年国际温标规定温度在１３Ｋ～９６１℃范围内的标准内插仪器为铂电阻温度计。铂电阻温度计的测量原理是基于铂电阻丝的阻值随着温度的变化而变化。为此，准确测量铂电阻温度计的阻值是贯彻９０国际温标传递...     

表面测温传感器简介

表面测温传感器简介郑晓文，郑红长期以来，表面温度的测量由于受到被测物体和环境条件复杂多变及测温元件本身缺陷的制约．一直是温度测量技术领域的一个难题。近年来，许多新型的表面测温传感器的涌现，为表面测温技术带来了巨大的进步，特别是铂电阻技术应用于表面测温...     

At－1型全自动测温电桥

Ａｔ－１型全自动测温电桥金俊成，王吉新，魏以嘉１引言１９９０年国际温标规定温度在１３Ｋ～９６１℃范围内的标准内插仪器为铂电阻温度计。铂电阻温度计的测量原理是基于铂电阻丝的阻值随着温度的变化而变化。为此，准确测量铂电阻温度计的阻值是贯彻９０国际温标传递...     

厚膜铂电阻温度计的研制、生产和应用

研制七十年代初期,英国经济在经历了一段稳定时期后,物价和工资都开始上涨。在此之前,罗斯蒙特公司生产的铂电阻温度计是以细铂丝为原料,通过密集型劳动制成的。出于经济上的考虑,探索制作电阻温度计的新方法以降低原材料和劳动力的成本,在当     

微差法检定工业用镍铬——镍硅热电偶的自动化

在石油、化工、冶金、机械和电力工业的测温系统巾。大量和广泛地使用着镍铬-镍硅热电偶。为保证测温的正确性,对使用中的热电偶需要进行定期检定。为此以往一般在工厂中采用双极比较法,用稳压器、调压器、管式炉作恒温设备,用0.05级直流电位差计和三等标准铂铑-铂热电偶作标准仪     

一种新型高温检定炉

叙述了用新型材料─—螺旋管状二硅化钼代替价格昂贵的铂铑丝作为发热体，制成了一台新型高温检定炉。介绍了高温炉的结构特点、配套仪表及试验过程。该高温炉满足了检定规程对高温热电偶和钨铼热电偶检定用炉的要求，并具有可观的经济效益和推广价值。     

AT-1型全自动测温电桥

ＡＴ - 1型全自动测温电桥是为标准铂电阻温度计的自动测量设计的 ,可以自动平衡完成测量并直接显示欧姆值和温度值。测量过程中不需要联接外部标准电阻 ,操作过程用中文提示 ,使用非常简便、快捷 ,抗干扰性能强 ,适用于一、二等铂电阻温度计的计量检定 ,以及需要用铂电阻温度计测量温度的一切测量领域。ＡＴ - 1提供的软件可完成定点法、比较法的检定测量 ,并按检定规程的要求打印出证书 ,也可对被测温度长期连续监测 ,给出温度变化曲线与测量值 ,也可与其他设备构成全自动温度监控或测量系统。ＡＴ - 1型性能指标完全可替代价格昂贵的各种…     

AT-1型全自动测温电桥

ＡＴ -1型全自动测温电桥是为标准铂电阻温度计的自动测量设计的 ,可以自动平衡完成测量并直接显示欧姆值和温度值。测量过程中不需要联接外部标准电阻 ,操作过程用中文提示 ,使用非常简便、快捷 ,抗干扰性能强 ,适用于一、二等铂电阻温度计的计量检定 ,以及需要用铂电阻温度计测量温度的一切测量领域。ＡＴ -1提供的软件可完成定点法、比较法的检定测量 ,并按检定规程的要求打印出证书 ,也可对被测温度长期连续监测 ,给出温度变化曲线与测量值 ,也可与其他设备构成全自动温度监控或测量系统。ＡＴ -1型性能指标完全可替代价格昂贵的各种进…     

铠装标准铂电阻温度计的研制

铠装标准铂电阻温度计是将敏感元件、中间引线、绝缘粉料、不锈钢外保护管组装后,再经模具拉制成的坚实整体。它除具有石英外管标准铂电阻精度高和稳定性好的优点外,还具有抗振、可挠、耐用、使用方便等优点。该温度计的测温范围为-200～-450℃。根据抽样试验分析,可作一般或精密测试之用。     

Growth of hydrodynamic perturbations in accretion disks: Possible route to non-magnetic turbulence

We study the possible origin of hydrodynamic turbulence in cold accretion disks such as those in star-forming systems and quiescent cataclysmic variables. As these systems are expected to have neutral gas, the turbulent viscosity is likely to be hydrodynamic in origin, not magnetohydrodynamic. Therefore, MRI will be sluggish or even absent in such disks. Although there are no exponentially growing eigenmodes in a hydrodynamic disk because of the non-normal nature of the eigenmodes, a large transient growth in the energy is still possible, which may enable the system to switch to a turbulent state. For a Keplerian disk, we estimate that the energy will grow by a factor of 1000 for a Reynolds number close to a million.     

Subsidence rate monitoring of Aghajari oil field based on Differential SAR Interferometry

Land subsidence, due to natural or anthropogenic processes, causes significant costs in both economic and structural aspects. That part of subsidence observed most is the result of human activities, which relates to underground exploitation. Since the gradual surface deformation is a consequence of hydrocarbon reservoirs extraction, the process of displacement monitoring is amongst the petroleum industry priorities. Nowadays, Differential SAR Interferometry, in which satellite images are utilized for elevation change detection and analysis – in a millimetre scale, has proved to be a more real-time and cost-effective technology in contrast to the traditional surveying method. In this study, surface displacements in Aghajari oil field, i.e. one of the most industrious Iranian hydrocarbon sites, are being examined using radar observations. As in a number of interferograms, the production wells inspection reveals that surface deformation signals develop likely due to extraction in a period of several months. In other words, different subsidence or uplift rates and deformation styles occur locally depending on the geological conditions and excavation rates in place.     

The Lunar Terrestrial Observatory: Observing the Earth using photometers on the Moon’s surface

The Earth’s albedo is one of the least studied fundamental climate parameters. The albedo is a bi-directional variable, and there is a high degree of anisotropy in the light reflected from a given terrestrial surface. However, simultaneously observing from all points on Earth at all reflecting angles is a practical impossibility. Therefore, all measurements from which albedo can be inferred require assumptions and/or modeling to derive a good estimate. Nowadays, albedo measurements are taken regularly either from low Earth orbit satellite platforms or from ground-based measurements of the earthshine from the dark side of the Moon. But the results from these different measurements are not in satisfactory agreement. Clearly, the availability of different albedo databases and their inter-comparisons can help to constrain the assumptions necessary to reduce the uncertainty of the albedo estimates. In recent years, there has been a renewed interest in the development of robotic and manned exploration missions to the Moon. Returning to the Moon will enable diverse exploration and scientific opportunities. Here we discuss the possibility of a lunar-based Earth radiation budget monitoring experiment, the Lunar Terrestrial Observatory, and evaluate its scientific and practical advantages compared to the other, more standard, observing platforms. We conclude that a lunar-based terrestrial observatory can enable advances in Earth sciences, complementary to the present efforts, and to our understanding of the Earth’s climate.     

Concept of wireless sensor network for future in-situ exploration of lunar ice using wireless impedance sensor

It is known that a wireless sensor network uses some sort of sensors to detect a physical quantity of interest, in general. The wireless sensor network is a potential tool for exploring the difficult-to-access area on the earth and the concept may be extended to space applications in future. Recently, lunar water has been detected by a few lunar missions using remote sensing techniques. The lunar water is expected to be in the form of ice at very low temperatures of permanently dark regions on the moon. To support the remote observations and also to find out potential ice bearing sites on the moon, in-situ measurement of the lunar ice is essential. However, a rover may not be able to reach the permanently shadowed regions due to terrain irregularity. One possibility to access such areas is to use a wireless sensor network on the lunar surface.     

使用Gao-Yong湍流方程计算翼体角偶流动

Gao-Yong湍流方程基于侧偏统计平均方法保留了湍流脉动量的一阶统计信息,并引入加权漂移速度对称性及正交各向异性,导出漂移流连续方程、动量方程和机械能方程,最后依据湍流物理的唯象论,使用动量传输链概念模化封闭了整个方程组.大量算例验证了此方程对广泛范围的复杂湍流问题的适定性.为了进一步的工程应用,将其加入开源计算流体力学软件OpenFOAM(Open Field Operation and Manipulation)中,并就翼体角偶流动进行了数值模拟.翼体角偶流动具有三维分离、马蹄涡等十分复杂的流动特征,通过与实验测量结果的对比研究表明,Gao-Yong湍流方程不论在定性还是定量上,都成功捕捉到这类复杂流动现象的主要特征,得到了令人满意的结果.     

A priori zenith wet delays in the analysis of VLBI CONT sessions

Tropospheric delay is one of the major sources of error in VLBI (Very Long Baseline Interferometry) analysis. The principal component of this error can be accurately computed through reliable surface pressure data —hydrostatic delay— yet there is also a small but volatile component —wet delay— which is difficult to be modelled a priori. In VLBI analysis, troposphere delay is typically modelled in the theoretical delays using Zenith Hydrostatic Delays (ZHD) and a dry mapping function. Zenith Wet Delay (ZWD) is not modelled but estimated in the analysis process. This work studies inter alia the impact of including external GNSS estimates to model a priori ZWD in VLBI analysis, as well as other models of a priori ZWD.In a first stage, two different sources of GNSS troposphere products are compared to VLBI troposphere estimates in a period of 5 years. The solution with the best agreement to VLBI results is injected in the VLBI analysis as a priori ZWD value and is compared to other options to model a priori ZWD. The dataset used for this empirical analysis consists of the six CONT campaigns.It has been found that modelling a priori ZWD has no significant impact either on baseline length and coordinates repeatabilities. Nevertheless, modelling a priori ZWD can change the magnitude of the estimated coordinates a few millimeters in the up component with respect to the non-modelling approach. In addition, the influence of a priori ZWD on Earth Orientation Parameters (EOP) and troposphere estimates —Zenith Total Delays (ZTD) and gradients—has also been analysed, resulting in a small but significant impact on both geodetic products.     

Measuring the economic benefits of a national planetary protection policy to regulate future private space activities between Earth and Mars: Results of a contingent valuation survey in Greece

The emergence of private space actors may soon enable the growth of the novel market segments of space research and exploration, space resources utilization, and human access to space. The interdisciplinary field of Planetary Protection has to keep up with these advances. Planetary Protection is defined as a set of guidelines that aim to prevent the forward contamination of celestial bodies with biological material from Earth and the backward contamination of the terrestrial biosphere with extraterrestrial biological material. As space entrepreneurs acquire and develop the resources and competencies for commercial access to space, significant questions are expected to be raised in the future with respect to potential forward and backward contamination issues, particularly with respect to activities between Earth and Mars. Although such private activities do not seem to pose a serious Planetary Protection threat at the moment, certain preparatory steps need to be taken in order to prudently inform the relevant policy-making procedures. This work describes the application of the Contingent Valuation Method, a useful tool of the environmental economics discipline, with the aim of demonstrating a novel approach to estimate the economic valuation of the external benefits of preventing forward and backward contamination between Earth and Mars. Particularly, via a survey specifically developed for this purpose, a set of questions are used to elicit the perceived economic value that respondents place on the prevention of forward and backward contamination; the survey is administered to a national probability sample in Greece, and the generated data is processed through statistical analysis. The Contingent Valuation Method is a popular and well-established stated preference valuation technique; these techniques are often the more suitable choice for ex-ante valuations of future changes, and are currently the only known approach to capture all the aspects of the economic value of non-market goods. Through an initial proof-of-concept in Greece, the goal of this work is to provide useful insights on the expected external benefits of a national Planetary Protection policy to regulate future private space activities between Earth and Mars, and to encourage a larger-scale application of this tool in other countries around the world.     

A new approach to the telescope operation method for satellite tracking using a time synchronization technique

For the development of a telescope that is capable of precisely tracking satellites and high-speed operation such as satellite laser ranging, a special method of telescope operation is required. This study aims to propose a new telescope operation method and system configuration for the independent development of a mount and an operation system which includes the host computer. Considering that the tracking of a satellite is performed in real time, communication and synchronization between the two independent subsystems are important. Therefore, this study applied the concept of time synchronization, which is used in various fields of industry, to the communication between the command computer and the mount. In this case, communication delays do not need to be considered in general, and it is possible to cope with data loss. Above all, when the mount is replaced in the future, only the general communication interface needs to be modified, and thus, it is not limited by replacement in terms of the overall system management. The performance of the telescope operation method developed in this study was verified by applying the method to the first mobile SLR system in Korea. This study is significant in that it proposed a new operation method and system configuration, to which the concept of time synchronization was applied, for the observation system that requires an optical telescope.     

Global Environmental Alert Service (GEAS)

Early warning systems represent an innovative and effective approach to mitigate the risk associated with natural hazards. Early warning technologies are now available for almost all natural hazards and systems are already in operation in all parts of the world. Nevertheless, recent disasters such as the Indian Ocean tsunami in 2004 and Katrina hurricane in 2005, highlighted inadequacies in early warning technologies.

Efforts towards the development of a global warning system are necessary for turning the tide in early warning processes and technologies. There is a pressing need for a globally comprehensive early warning system based on existing systems. The global system should be a mechanism which can consolidate scientific information and evidences, package this knowledge in a form usable to international and national decision makers and actively disseminate this information to those users.

The proposed Global Environmental Alert Service (GEAS) will provide information emanating from monitoring, Earth observing and early warning systems to users in a near-real-time mode and bridge the gap between the scientific community and policy makers. Characteristics and operational aspects of such a service, GEAS, are discussed.