High latitude helical surge of May 22, 1989     

Adnan Ökten  Hikmet Çakmak 《Solar physics》1990,128(2):365-369

A helical surge (S 72, W 90) was recorded by a monochromatic filter at the University Observatory of Istanbul. It is a significient one at a very high latitude and without any center of activity. A sequence of the filtergrams showed some condensed points from which the motions of the plasma are traced. Different velocities were determined on each of the branches of the helical surge during its evolution. The surge reached its maximum height of 298 000 km and the maximum velocity of this upper region was 250 km s^–1.  相似文献   

Temporal Offsets Between Maximum CME Speed Index and Solar,Geomagnetic, and Interplanetary Indicators During Solar Cycle 23 and the Ascending Phase of Cycle 24     

A. Özgüç  A. Kilcik  K. Georgieva  B. Kirov 《Solar physics》2016,291(5):1533-1546

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Bounce Rock—A shergottite‐like basalt encountered at Meridiani Planum,Mars     

Jutta ZIPFEL  Bradley L. JOLLIFF  Ralf GELLERT  Kenneth E. HERKENHOFF  Rudolf RIEDER  Robert ANDERSON  James F. BELL III  Johannes BRÜCKNER  Joy A. CRISP  Philip R. CHRISTENSEN  Benton C. CLARK  Paulo A. De SOUZA Jr.  Gerlind DREIBUS  Claude D’USTON  Thanasis ECONOMOU  Steven P. GOREVAN  Brian C. HAHN  Göstar KLINGELHÖFER  Timothy J. McCOY  Harry Y. McSWEEN Jr.  Douglas W. MING  Richard V. MORRIS  Daniel S. RODIONOV  Steven W. SQUYRES  Heinrich WÄNKE  Shawn P. WRIGHT  Michael B. WYATT  Albert S. YEN 《Meteoritics & planetary science》2011,46(1):1-20

Abstract– The Opportunity rover of the Mars Exploration Rover mission encountered an isolated rock fragment with textural, mineralogical, and chemical properties similar to basaltic shergottites. This finding was confirmed by all rover instruments, and a comprehensive study of these results is reported here. Spectra from the miniature thermal emission spectrometer and the Panoramic Camera reveal a pyroxene‐rich mineralogy, which is also evident in Mössbauer spectra and in normative mineralogy derived from bulk chemistry measured by the alpha particle X‐ray spectrometer. The correspondence of Bounce Rock’s chemical composition with the composition of certain basaltic shergottites, especially Elephant Moraine (EET) 79001 lithology B and Queen Alexandra Range (QUE) 94201, is very close, with only Cl, Fe, and Ti exhibiting deviations. Chemical analyses further demonstrate characteristics typical of Mars such as the Fe/Mn ratio and P concentrations. Possible shock features support the idea that Bounce Rock was ejected from an impact crater, most likely in the Meridiani Planum region. Bopolu crater, 19.3 km in diameter, located 75 km to the southwest could be the source crater. To date, no other rocks of this composition have been encountered by any of the rovers on Mars. The finding of Bounce Rock by the Opportunity rover provides further direct evidence for an origin of basaltic shergottite meteorites from Mars.  相似文献   

Absolute parameters of the newly-identified contact binary star IS Canis Major     

B. Özkardeş  A. Erdem 《New Astronomy》2010,15(2):247-253

This paper presents the results of the first high-resolution spectroscopic observations of the Southern W UMa type system IS CMa. Spectroscopic observations of the system were made at Mt. John University Observatory using a HERCULES fibre-fed échelle spectrograph in September 2007. The first radial velocities of the component stars of the system were determined by using the spectral disentangling technique. The resulting orbital elements of IS CMa are: $a_1\sin i=0.0041\pm 0.0001$ AU, $a_2\sin i=0.0135\pm 0.0001$ AU, $M_1{\sin }^{3}i=1.48\pm 0.01{\mathrm{M}}_{\odot }$, and $M_2{\sin }^{3}i=0.44\pm 0.01{\mathrm{M}}_{\odot }$. The components were found to be in synchronous rotation taking into account the disentangled ${\mathrm{H}}_{\delta }$ line profiles of both components of the system. The Hipparcos light curve was solved by means of the Wilson–Devinney method supplemented with a Monte Carlo type algorithm. The radial velocity curve solutions including the proximity effects give the mass ratio of the system as 0.297 ± 0.001. The combination of the Hipparcos light and radial velocity curve solutions give the following absolute parameters of the components: $M_1=1.68\pm 0.04{\mathrm{M}}_{\odot }\text{,}{\mathrm{M}}_2=0.50\pm 0.02{\mathrm{M}}_{\odot }\text{,}{R}_1=2.00\pm 0.02{\mathrm{R}}_{\odot }\text{,}{R}_2=1.18\pm 0.03R_{\odot }\text{,}{L}_1=7.65\pm 0.60$ ${\mathrm{L}}_{\odot }$ and $L_2=1.99\pm 0.80{\mathrm{L}}_{\odot }$. The distance to IS CMa was calculated as $87\pm 5$ pc using the distance modulus with corrections for interstellar extinction. The position of the components of IS CMa in the HR diagram are also discussed: the system seems to have an age of 1.6 Gyr.  相似文献   

豫西嵩县前范岭石英脉型钼矿床地质特征及辉钼矿Re-Os同位素年龄   总被引：14，自引：2，他引：12  

高阳  李永峰  郭保健  程国祥  刘彦伟 《岩石学报》2010,26(3):757-767

位于熊耳山-外方山地区的前范岭钼矿是东秦岭地区新近发现的石英脉型钼矿床之一。赋矿围岩为古元古界熊耳群安山质火山岩类。矿体主要以含辉钼矿石英脉产出,矿石类型以石英脉型为主。金属矿物以辉钼矿和黄铁矿为主,脉石矿物以石英为主,其次为方解石、萤石等。围岩蚀变类型有硅化、钾长石化、青磐岩化等。对6件辉钼矿样品进行Re-Os同位素测年所获得的模式年龄为233.3±3.3～248.2±3.5Ma,等时线年龄为239±13Ma,表明矿床形成于中三叠世。矿床的成矿作用发生于华北与扬子两个板块碰撞对接的晚期阶段。区域上整体的挤压造成了局部的剪切和伸展环境,这种环境为控矿断裂的形成和成矿流体的运移提供了有利条件。嵩县境内现已发现的多处脉型钼矿床很可能形成于同一时期(三叠纪),它们构成了熊耳山与外方山之间的嵩县脉型钼矿田。  相似文献   

Impact of Hydropower Regulation on River Water Composition in Northern Sweden     

Dmytro Siergieiev  Anders Widerlund  Angela Lundberg  Lisbeth Almqvist  Magali Collomp  Johan Ingri  Björn Öhlander 《Aquatic Geochemistry》2014,20(1):59-80

Using hydrogeochemical analysis of two large boreal rivers (pristine Kalix and hydropower regulated Lule) discharging into the Gulf of Bothnia, the major impacts of regulation on water discharge, element transport and their seasonal redistribution have been assessed. The pre-regulation hydrogeochemical features were assumed to be similar for the two rivers. For the Lule River, the average maximum runoff was almost halved, while the average minimum was tripled as a result of the regulation. The fraction of winter transport of total organic carbon (TOC), Fe, Si, suspended Mn and P in the Lule River was, according to a conservative estimate, two to three times higher than in the pristine river. Longer residence time in the Lule River delayed arrival of the suspended Mn peak and dissolved Si decline to the river mouth. During summer, the suspended C/N ratio in the regulated river was 10–20 compared to <10 for the pristine, suggesting presence of predominantly old organic material. This was supported by a virtually constant suspended P/Fe ratio throughout the year in the Lule River, indicating low abundance of phytoplankton. TOC varied irregularly in the Lule River suggesting temporal disconnection between the river and the upper riparian zone. The disappearance of the spring flow maximum, a shift of element transport from spring to winter and supply of mainly old organic material during the vegetation growth season may have a pronounced impact on the ecosystem of the Gulf of Bothnia and the river itself.  相似文献   

Investigation of surface and subsurface displacements due to multiple tunnels excavation in urban area     

Alireza Talebinejad  Hamid Chakeri  Mahdi Moosavi  Yılmaz Özçelik  Bahtiyar Ünver  Mehmet Ali Hindistan 《Arabian Journal of Geosciences》2014,7(9):3913-3923

Underground structures are currently widely used and are built as urbanism develops. The interactions between perpendicularly crossing and parallel tunnels in the Tehran region are investigated by using a full three-dimensional (3D) finite difference analysis with elastic-plastic material models. Special attention is paid to the effect of subsequent tunneling on the support system, i.e., the shotcrete lining and rock bolts of the existing tunnel. Eventually, as the tunnels are excavated at certain levels, the interaction between the tunnels will certainly have a significant influence on both stress distribution and consequently deformations. Since multilayer tunneling is a three-dimensional phenomenon in nature, 3D numerical solutions must be utilized for analyzing effect of perpendicularly crossing tunnels at various levels. As Tohid twin tunnels and Line 7 pass beneath the Line 4 metro tunnel, changes in stress distribution, deformations, and surface settlements are studied for various conditions and the results are presented in this paper. Consequently, it is shown that there is a significant interaction between tunnels that necessitate certain preventive measures to maintain a stable tunneling operation.  相似文献   

A New Rock Mass Quality Rating System: Rock Mass Quality Rating (RMQR) and Its Application to the Estimation of Geomechanical Characteristics of Rock Masses   总被引：1，自引：0，他引：1  

Ömer Aydan  Reşat Ulusay  Naohiko Tokashiki 《Rock Mechanics and Rock Engineering》2014,47(4):1255-1276

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Pushover and nonlinear time history analysis evaluation of a RC building collapsed during the Van (Turkey) earthquake on October 23, 2011     

Özlem Çavdar  Alemdar Bayraktar 《Natural Hazards》2014,70(1):657-673

The nonlinear seismic behavior of a collapsed reinforced concrete (RC) residential building in the city of Van in Turkey is investigated by the static pushover and nonlinear time history analyses. The selected RC structure was designed according to the 1975 version of Turkish Earthquake Code (TEC-1975). The building had experienced heavy damage, and it was demolished in the Van earthquake on October 23, 2011. The 2007 version of Turkish Earthquake Code (TEC-2007) is considered for the assessing seismic performance evaluation of the selected RC building. The RC structure presents collapse performance level under the earthquake loads. Besides, the analytical solutions show that different performance levels for the sections are obtained from the pushover and nonlinear time history methods.  相似文献   

Stable (H,O, C) and noble-gas (He and Ar) isotopic compositions from calcite and fluorite in the Speewah Dome,Kimberley Region,Western Australia: implications for the conditions of crystallization and evidence for the influence of crustal-mantle fluid mixing     

Gy Czuppon  R. R. Ramsay  I. Özgenc  A. Demény  L. G. Gwalani  K. Rogers  A. Eves  L. Papp  L. Palcsu  M. Berkesi  P. J. Downes 《Mineralogy and Petrology》2014,108(6):759-775

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