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1.
Simultaneous wind, wave, and current data during 21 storms spanning four winters at Tromsøflaket (230 m depth) were analysed to determine joint probabilities of occurrence. Waves were measured with a Waverider Buoy, winds with a recording anemometer onboard a vessel and currents at up to five depths with Aandera RCM-4 current meters. Measured currents were filtered to separate tidal currents from residual currents. In most of the statistical analyses, the actual current profiles were replaced with a simplified “equivalent” profile (constant above 50 m depth) whose magnitude was chosen to give the same drag load on a single pile as the actual profile when both profiles were combined with wave orbital velocities. The data suggest that the equivalent current is weakly correlated with the wave height. Within the range of the data analysed, an in-line equivalent residual current of 30 cm sec−1 is adequate for design drag force calculations.The data presented here are used to illustrate a procedure for data analysis and are not suitable for use as design criteria. 相似文献
2.
Experimental determination of activities in FeTiO3-MnTiO3 ilmenite solid solution by redox reversals
Solid solutions of (Fe,Mn)TiO3 were synthesized, mostly at 0.10 XMn intervals, at 1 bar, 900°C and log f
O
2 = –17.50. Analysis by EMP indicate an ideal stoichiometry for the Fe-Mn ilmenites with (Fe+Mn) = Ti = 1.000 when normalized
to 3 oxygens. Their unit cell volume increases linearly with XMn. The composition of Fe-Mn ilmenite coexisting with metallic Fe and rutile was reversed at 1 bar, 700–900°C and fixed f
O
2 in a gas-mixing furnace. Oxygen fugacity was controlled by mixing CO2 and H2 gas and was continuously monitored with an yttrium-stabilized zirconia electrolyte. Solution properties of Fe-Mn ilmenite
were derived from the experimental data by mathematical programming (Engi and Feenstra, in preparation) including notably
the results of Fe-Mn exchange experiments between ilmenite and garnet (Feenstra and Engi, submitted) and anchoring the standard
state properties to the updated thermodynamic dataset of Berman and Aranovich (1996). The thermodynamic analysis resulted
in positive deviations from ideality for (Fe,Mn)TiO3 ilmenite, which is well described by an asymmetric Margules model with WH
FeFeMn = –9.703 and WH
FeMnMn = –23.234 kJ/mol, WS
FeFeMn = –19.65 and WS
FeMnMn = –22.06 J/(K·mol). The excess free energy for Fe-Mn ilmenite derived from the redox reversals is larger than in the symmetric
ilmenite model (WG
FeMn = +2.2 kJ/mol) determined by O'Neill et al. from emf measurements on the assemblage iron-rutile-(Fe,Mn)ilmenite.
Received: 10 January 1996 / Accepted: 11 July 1996 相似文献
3.
Previous stable isotope studies at Lizzies Basin revealed that metasedimentary rocks are 18O-depleted relative to protolith values, particularly in the lower parts of the section (Lower Zone) where the rocks are also
isotopically homogeneous on a scale of hundreds of meters (quartz δ18O=+9.0 to +9.6 per mil). In contrast, metasedimentary rocks at higher levels at Lizzies Basin (Upper Zone) are less 18O-depleted and more heterogeneous in δ18O. In order to understand more fully the isotopic evolution of this terrane, a series of detailed, meter-scale traverses across
various metamorphic and igneous lithologies were completed at Lizzies Basin, and at the structurally higher Angel Lake locality.
Traverses in the Lizzies Basin Lower Zone and in the lower parts of Angel Lake (Angel Lake Lower Sequence) across various
silicate lithologies, including abundant granitoids, reveal similar degrees of homogeneity, although the average δ18O values are higher at Angel Lake. In contrast, traverses which include substantial thicknesses of marble and calc-silicate
gneiss and very little granitoid have more heterogeneous quartz δ18O values (+11.9 to +13.4 per mil), and also have a higher average δ18O (+12.9 per mil), than observed elsewhere. The scale of 18O/16O homogeneity in quartz observed at Lizzies Basin and Angel Lake (meters to hundreds of meters) requires fluid-mediated isotope
exchange, which accompanied Tertiary metamorphism. There is a correlation between the degree of 18O-depletion in metasedimentary rocks, 18O/16O homogenization between lithologies, and the proportion of granitoids (leucogranites in particular) within any part of the
section, and a corresponding anticorrelation with the proportion of marble. This points to a causal relationship, whereby
the leucogranites (as well as the Tertiary hornblende diorite and biotite monzogranite) acted as both a relatively low-18O reservoir and a source of fluids to enhance exchange, while the marbles hindered isotope depletion and homogenization by
acting as relatively high-18O reservoirs and impermeable layers. Material balance calculations help delineate the plausible mechanisms of exchange between
granitoids and metasediments. Single-pass infiltration of magmatic fluids from the granitoids is not capable of reproducing
all of the observations. Fluid-mediated exchange by convective recirculation of magmatic fluids on a scale of meters is the
mechanism which explains all of the observations. The generalized model for the isotopic evolution of the East Humboldt Range
core complex provides an excellent opportunity to establish the main causes and controlling factors of 18O-depletion and 18O/16O homogenization during regional metamorphism.
Received: 27 July 1993 / Accepted: 1 July 1994 相似文献
4.
M. J. Bickle H. J. Chapman S. M. Wickham M. T. Peters 《Contributions to Mineralogy and Petrology》1995,121(4):400-413
Sr isotope profiles across marble-silicate rock contacts are used in conjunction with previously published oxygen isotope
profiles to constrain fluid movement, porosity and permeability contrasts in migmatitic rocks from Lizzies Basin in the East
Humboldt Range, Nevada. The 18O/16O systematics in the high-grade sequence have been interpreted to reflect infiltration of ∼2×102 m3/m2 of a relatively low 18O hydrous fluid through the sequence, but with preservation of δ18O anomalies in thin marble bands due to a 30-fold lower porosity in the marble compared with silicate rocks (Wickham and Peters
1992). The Sr isotope profiles confirm that tracer exchange between marble and silicate rock was primarily by diffusion, and
in one case, indicate that porosities differed by less than a factor of four in the ∼10 cm boundary layer which exhibits diffusive
modification of 87Sr/86Sr ratios. This contrasts with modelling of the oxygen isotope profiles which imply porosity contrasts >10 for one marble
band and >50 for a second marble band. Either strontium and oxygen isotope diffusion reflect different events (possible if
fluid Sr contents varied with time) or porosity varied substantially with the silicate rocks. Oxygen isotope profiles in the
deeper part of the metamorphic section in which δ18O values of silicate rocks have been homogenised and lowered, indicate similar diffusion distances (and thus porosity-time
evolution) to oxygen isotopic profiles higher in the section. Comparison of strontium and oxygen isotope diffusion distances
constrains fluid Sr contents to between ∼50 and ∼500 ppm deep in the section, but less than ∼10 ppm higher in the section.
The difference is related to release of relatively saline, Sr-rich fluids, by the abundant leucogranites and associated skarns
deep in the section (cf. Peters and Wickham 1995).
Received: 9 December 1994/Accepted: 13 April 1995 相似文献
5.
小型激光天文动力学空间计划概念 总被引:1,自引:0,他引:1
倪维斗 朱进 武向平 褚桂柏 杨彬 高健 关敏 汤健仁 周翊 张中豪 黄天衣 曲钦岳 易照华 李广宇 陶金河 吴岸明 罗俊 叶贤基 周泽兵 熊耀恒 毕少兰 须重明 吴雪君 唐孟希 包芸 李芳昱 黄珹 杨福民 叶叔华 张书练 张元仲 聂玉昕 陈光 Joergen Christensen-Dalsgaard Hansjoerg Dittus Yasunori Fujii Claus Laemmerzahl Jean Francois Mangin Achim Peters Albrecht Ruediger Etienne Samain Stephan Schiller 《天文研究与技术》2002,(3):123-136
小型激光天文动力学空间计划是 :使用在太阳轨道上无拖曳航天器和地面站以激光干涉和脉冲测距的方法 ,精确地探讨天文动力学 ,检测相对论与时空基本定律 ,改进探测引力波的灵敏度以及更准确地测定太阳、行星和小行星的参数。 1 969年开始的月球激光 (反射 )测距 ,对地球物理、参考坐标的选定、相对论的检验均有重要的贡献。 3 0年来 ,激光技术的长足进步 ,使现在正是适合于开始进行研究空间有源 (主动 )测距和光波空间通讯的时候。激光天文动力学的兴起是必然的趋势 ,其精确度将比现在提高 3到 6个数量级 ,将是天文动力学革命性的发展。小型激光天文动力学空间计划可以起到带头作用。它的关键技术有三 ,即 :弱光锁相、极精确无拖曳航天和高衰减日冕仪。弱光锁相已有长足的进步。对高衰减日冕仪的研究 ,也有了初步的方案。LISA空间计划将于 2 0 0 6年 8月发射SMART -2 ,研究测试极精确无拖曳航天。小型激光天文动力学空间计划的关键技术已日趋成熟。在第一届国际激光天文动力学研讨会 ( 2 0 0 1 ,9.1 3 -2 3 )中介绍了各相关学科背景及前沿研究 ,讨论了激光天文动力学空间计划科学目标及相关技术 ,并召开了两次小型激光天文动力学空间计划预研究筹备会 ,建立了和欧洲的合作关系。会后着手进行此项对基础 相似文献
6.
Andreas Fries Rütger Rollenbeck Fabian Bayer Victor Gonzalez Fernando Oñate-Valivieso Thorsten Peters Jörg Bendix 《Meteorology and Atmospheric Physics》2014,126(1-2):13-29
The precise estimation of precipitation quantities in tropical mountain regions is in great demand by ecological and hydrological studies, due to the heterogeneity of the rainfall distribution and the lack of meteorological station data. This study uses radar images and ground station data to provide the required high-resolution precipitation maps. Also wind data are taken into account, due to its influence on the precipitation formation and to demonstrate the relation between synoptic wind, topography and the precipitation distribution inside small mountain valleys. The study analyses the rainfall distribution and amounts of 4 days inside the San Francisco Valley, a small catchment in the tropical Andes of southern Ecuador, representing different seasons and the typical atmospheric flows, which are correlated to the annual precipitation map. The results show that the rainfall distribution and amounts are generally defined by the wind direction and velocity, besides the topographic location in relation to the main barriers and pathways. The dominant wind direction causes a division of the catchment in a wetter eastern and a dryer western part. Moreover, the annual seasons are reversed; the main rainy season for the eastern part occurs between June and August, while the western part reaches the precipitation maximum between January and March. This may have influence on the species composition at the different slopes and the annual hydrological cycle inside the catchment. 相似文献
7.
D. Engelbart H. Steinhagen U. Görsdorf J. Neisser H. J. Kirtzel G. Peters 《Meteorology and Atmospheric Physics》1999,71(1-2):61-68
Summary At a special measuring site for boundary-layer studies as well as land-surface processes the Meteorological Observatory Lindenberg
of the German Weather Service (DWD) has recently put into operation a newly-desi gned phased-array SODAR/RASS, which has been
developed by METEK on behalf of the DWD. This system provides the vertical profiles of the three-di mensional wind vector
in the boundary layer on an operational basis and is furthermore suitable for getting information on the profile of virtual
temperature up to about 400 m in height based on the addition of RASS components. The following paper describes both the technique
of this SODAR/RASS and the various modes of operation as well as the different options in managing the system. First evaluations
on the data availability concerning the maximum height coverage will give an impression on the system’s capabilities. Finally,
the accuracy of the derived profiles of winds and temperature will be investigated by means of comparisons of the SODAR/RASS
data with measurements of a six-sonde tethered-balloon system as well as meteorological data of a 99 m tower in the vicinity
of the system.
Received November 27, 1998 Revised April 9, 1999 相似文献
8.
Summary The accuracy of the electrochemical ozone sonde, type OSR, has been estimated by analysing tandem ozone soundings of the balloon-borne electrochemical ozone sonde OSR at the Lindenberg Observatory from May to November 1982. A negative bias, though not significant, has been observed above about 28 km for soundings having high single correction factors. Random errors are at their minimum just above the level of the maximum of ozone partial pressure, and reach their maximum in the troposphere. Except at heights above about 28 km the random error of ozone sondes is a factor 2 to 3 times less than the error of the short Umkehr method. Provided that soundings with too high correction factors are neglected, the ozone sonde OSR has an accuracy comparable to that of other Brewer type sondes.The maximum amount of information on the vertical ozone distribution can be drawn from sonde measurements in the lower stratosphere. A study is underway to improve the sensitivity of the sonde OSR and thus to further enhance its reliability. 相似文献
9.
In this paper an explanation is given of Rijkswaterstaat's need for hydrological and meteorological information. The present means to gather this information are described together with their limitations. Future developments in the field of HF narrow-beam groundwave radar systems are indicated and some recommendations are given for the design of an operational HF radar system for Rijkswaterstaat (RWS). 相似文献
10.