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991.
CT-1地震计传递函数测试仪的设计 总被引:6,自引:4,他引:2
将计算机控制技术应用到甚宽频带地震计的传递函数测试中。讨论了基本的测试方法和原理,阐述了传递函数测试系统的软、硬件设计,给出了测试系统的应用实例。该测试系统具有正弦波自动扫频、阶跃信号法和脉冲信号法等标定方法,满足了甚宽频带地震计的传递函数测试在观测频带、动态范围和测试精度等方面的要求。 相似文献
992.
FIVE RED TIDE SPECIES IN GENUS PROROCENTRUM INCLUDING THE DESCRIPTION OF PROROCENTRUM DONGHAIENSE LU SP. NOV. FROM THE EAST CHINA SEA 总被引:22,自引:0,他引:22
A new planktonic dinoflagellate, Prorocentrum donghaiense I_a sp. nov., is described in the present paper. The water sample was collected from the Changjiang Estuary, the East China Sea. The species identification is based on shape, size, surface micro-morphology, ornamentation of thecal plates and the architecture of the pel‘iflagellar area and the intercalary bands as seen by fight and scanning electron microscope. Prorocentrum donghaiense Lu sp. nov. is compared with other prorocentrum species with respect to morphological characteristics and bloom behavior. It is not known whether Prorocentrum donghaiense Lu sp. nov produces phycotoxins like some other Prorocentrum species. Four other red tide species in the family Prorocentraceae (Dinophyceae), namely P. balticum, P. minimum, P.micans, P. triestinum, were examined and identified by light and scanning electron microscope. They have been recorded as bloom-forming species. Some aggregates of Prorocentrum are observed at the end of blooms. An event of strong discoloration caused by P. donghaiense could be detected by satellite sensor in the East China Sea in the late spring, of 1995. 相似文献
993.
皖南低丘茶园土壤动物群落结构研究 总被引:13,自引:0,他引:13
本文是1986年10月—1988年10月对皖南低丘茶园土壤动物群落结构调查和研究的结果。调查期间共获大、中、小型土壤动物9468个,分别隶属于6门13纲37类。其中线虫类、螨类和蚁类为优势类群;线蚓类、弹尾类、鞘翅类幼虫、双翅类幼虫、蜘蛛类为常见类群,两者共占全捕量的94.03%。中小型土壤动物平均密度为1—2万个/m~2,大型土壤动物密度为200—500个/m~2。30年树龄茶园土壤动物群落的组成和数量最丰富,多样性、均匀性和密度-类群指数最高,其变化规律一般是30年茶园>20年茶园>15年茶园;7年树龄茶园群落土壤动物个体数虽少,但组成并不贫乏,且分布均匀,故多样性与密度-类群指数较高。土壤结构较好的黄红壤茶园各项指数大于土层薄、排水不良的黄棕壤茶园。群落各项指数秋季均大于春季。 相似文献
994.
Approximate spectral analysis by least-squares fit 总被引:4,自引:0,他引:4
Petr Vaníček 《Astrophysics and Space Science》1969,4(4):387-391
An approximate method of spectral analysis called successive spectral analysis based upon the mean-quadratic approximation of an empirical function by generalised trigonometric polynomial with both unknown frequencies and coefficients is developed. A few quotations describing some properties of the method as well as one of the possible methods for numerical solution are given. 相似文献
995.
Zdislav Šíma 《Astrophysics and Space Science》1973,24(2):421-448
In this paper, the model of the ring envelope round the primary component and the stream of the gaseous mass flowing from
the secondary component to the primary is constructed on the basis of theoretical computations concerning the exchange of
the mass between the components of the binary. The paper studies the influence of the gaseous mass on the profiles of spectral
lines before and after occultation; the influence of the stream on the profile in case the secondary is near elongation, is
also investigated. The line profiles obtained by numerical computations show that their changes caused by outflowing mass
should be well detectable from spectrograms taken at particular phase of the binary. Changes in the lines may influence the
measurement of radial velocities. The method for distinguishing the influence of the stream from the influence of the ring
is described. 相似文献
996.
The solar eclipse on August 11, 1999, observed in the region covered by many geomagnetic observatories, has offered a unique opportunity to look for an effect of the eclipse on geomagnetic pulsations. The pulsation activity digital data have been taken from Budkov Observatory in the Czech Republic (in the X component only), from observatories in Germany (Niemegk, Fürstenfeldbruck, Bad Bergzabern), in Hungary (Nagycenk), and for comparison in South Africa (Hermanus, conjugate-point station), and in Finland (Sodankylä, far from the eclipse zone). At all these stations the field in all three component has been recorded. The pulsation amplitudes in the X component exhibit a long-term minimum near the time of the eclipse. Spectral analysis of selected short intervals confirmed this decrease and also revealed a decrease of the average pulsation period during the eclipse. Such a change in the amplitude or in the period was not observed outside of the eclipse interval or in other days. Investigation in some narrower frequency bands showed that the maximal decrease occurred in the 15–20 s band. All these changes can be found in records from all the stations near the eclipse totality belt, also in records at the conjugate-point station, where no eclipse occurred. No signature has been found in records at the station situated far from the eclipse zone. 相似文献
997.
Studia Geophysica et Geodaetica - 相似文献
998.
Observational estimation of heat budgets on drifting ice and open water over the Arctic Ocean 总被引:9,自引:0,他引:9
It is of major scientific interests to determine the parameters of momentum, heat and vapor exchange in the planetary boundary layer in order to study the effects of ocean-ice-atmosphere interactions and their feedback mechanisms on global climate[1]. Lin… 相似文献
999.
A technique to improve the empirical mode decomposition in the Hilbert-Huang transform 总被引:2,自引:0,他引:2
The Hilbert-based time-frequency analysis has promising capacity to reveal the time-variant behaviors of a system. To admit
well-behaved Hilbert transforms, component decomposition of signals must be performed beforehand. This was first systematically
implemented by the empirical mode decomposition (EMD) in the Hilbert-Huang transform, which can provide a time-frequency representation
of the signals. The EMD, however, has limitations in distinguishing different components in narrowband signals commonly found
in free-decay vibration signals. In this study, a technique for decomposing components in narrowband signals based on waves’
beating phenomena is proposed to improve the EMD, in which the time scale structure of the signal is unveiled by the Hilbert
transform as a result of wave beating, the order of component extraction is reversed from that in the EMD and the end effect
is confined. The proposed technique is verified by performing the component decomposition of a simulated signal and a free
decay signal actually measured in an instrumented bridge structure. In addition, the adaptability of the technique to time-variant
dynamic systems is demonstrated with a simulated time-variant MDOF system. 相似文献
1000.
Jan?Pa?avaEmail author Ivan?Vav?ín Ji?í?Fryda Vojtěch?Janou?ek Emil?Jelínek 《Mineralium Deposita》2003,38(3):298-311
The Ransko gabbro-peridotite massif in Eastern Bohemia is a strongly differentiated intrusive complex of Lower Cambrian age. The complex hosts low grade Ni-Cu ores mainly developed close to the contact of olivine-rich rocks with gabbros, in troctolites and, to a much lesser extent, in both pyroxene and olivine gabbros and plagioclase-rich peridotites. The ore zone is characterized by strong serpentinization and uralitization. The total Ni + Cu locally reaches up to 4 wt%. Anomalous concentrations of platinum-group elements (PGE's) (maximum 532 ppb Pd, 182 ppb Pt, 53 ppb Rh, 15 ppb Ru, 41 ppb Ir) were detected in samples of Cu-Ni and Ni-Cu ores (maximum 2.63 wt% Ni and 2.31 wt% Cu) from the Jezírka orebody. The main ore paragenesis includes pyrrhotite, pentlandite, chalcopyrite, cubanite, pyrite, magnetite, mackinawite, valleriite, ilmenite and sphalerite. During this work, michenerite, froodite, sperrylite, gold, native bismuth, altaite, tsumoite, hessite, an unnamed Bi-Ni telluride, cobaltite-gersdorffite and galena were newly identified. The host rocks originated through partial melting of a slightly depleted mantle source with noble metals scavenged from this primitive magma prior to the development of these rocks. 相似文献