Features of the ionosphere behavior before the Kythira 2006 earthquake

In this paper we present specific features of TEC (total electron content of the ionosphere) behavior as possible precursors of Kythira (Southern Greece) earthquake of January 8, 2006 (M6.8). For this purpose, we used both the TEC data of GPS-IGS stations nearest to the epicenter, and TEC maps over Europe. The favorable circumstance for this analysis was the quiet geomagnetic situation during the period prior to the earthquake. One day before the earthquake, a characteristic anomaly was found out as the day-time significant increase of TEC at the nearest stations, up to the value of 50% relative to the background condition. To estimate the spatial dimensions of seismo-ionospheric anomaly, the differential mapping method was used. The ionosphere modification as a cloud-like increase of electron concentration situated in the immediate vicinity of the forthcoming earthquake epicenter has been revealed. The amplitude of modification reached the value of 50% relative to the non-disturbed condition and was in existence from 10:00 till 22:00 UT. The area of significant TEC enhancement had a size of about 4000 km in longitude and 1500 km in latitude.     

Back-analysis for initial ground stress field at a diamond mine using machine learning approaches

Exact knowledge for ground stress field guarantees the construction of various underground engineering projects as well as prediction of some geological hazards such as the rock burst. Limited by costs, field measurement for initial ground stresses can be only conducted on several measure points, which necessitates back-analysis for initial stresses from limited field measurement data. This paper employed a multioutput decision tree regressor (DTR) to model the relationship between initial ground stress field and its impact factor. A full-scale finite element model was built and computed to gain 400 training samples for DTR using a submodeling strategy. The results showed that correlation coefficient r between field measurement values and back-analysis values reached 0.92, which proved the success of DTR. A neural network was employed to store the global initial ground stress field. More than 600,000 node data extracted from the full-scale finite element model were used to train this neural network. After training, the stresses on any location can be investigated by inputting corresponding coordinates into this neural network.

     

New design chart for geotechnical ground improvement: characterizing cement-stabilized sand

Cement stabilization of soil is a useful method to improve the mechanical behaviors and engineering performance of soils in geotechnical design and construction projects involving weak or liquefiable soils. Among the factors affecting the strength of cement-stabilized soils, water content and water–cement ratio are important but less well understood because of controversial views. This paper presents a systematic laboratory study to investigate the effects of water content and water–cement ratio on the unconfined compressive strength, with good control of the packing density and void ratio of the tested specimens. The effects of void ratio and cement content are also investigated. The strength of the cement-stabilized sand continuously decreased with increasing water–cement ratio within the range of 0.5 to about 3. A general equation is suggested to evaluate the unconfined compressive strength of cement-stabilized soil. Finally, a new conceptual characterization chart is proposed with consideration of the effects of cement content, water content, and water–cement ratio.

     

面向新经济的测绘工程专业改造升级路径探讨

针对传统测绘工程专业难以适应当前新经济环境,需要进行改造升级的现状,本文以闽江学院测绘工程专业为研究对象,依托现有测绘工程、地理信息科学和导航工程等3个专业,通过合理联动、适时修改测绘工程专业的教学大纲与教学内容,将地理信息科学和导航工程专业的相关教学资源融入测绘工程专业,建立以地理学、计算机科学与技术、测绘科学与技术为主线的现代测绘工程课程体系。以现有的"测绘地理信息专业群"为基础,构建了以地方特色产业发展和需要为导向、学科交叉互补的新型学科发展体系,提出了测绘工程专业多学科交叉复合改造的具体途径与方式。最后,建立了基于测绘工程专业改造升级的无人机遥感监测与应急测绘应用新方向并形成新的课程体系,以期为新经济环境下测绘工程专业人才的培养、学科发展、教学管理等提供参考。     

南海夏季风爆发的数值预报模拟实验

1998年5月21日00时（UTC）,对流层上部200hPa的南亚反气旋中心位于（16oN,94oE）附近,850hPa南海的中南部仍为副热带反气旋控制;到21日12时,200hPa的南亚反气旋中心迅速移到（21oN,94oE）附近,同时850hPa的南海副热带反气旋减弱东撤,南海的中南部由东南风转变为西南风,南海夏季风爆发。本文利用美国国家大气研究中心和宾西法尼亚州大学联合研制的中尺度模式（MM5V2）模拟预报这一过程,同时通过敏感性实验研究了区域边界条件和水平分辨率对季风预报模拟实验的影响。     

Radiochemical,scanning electron microscope (SEM) and X-ray dispersive energy (EDAX) studies of a FAMOUS hydrothermal deposit

During the French-American Mid-Oceanic Undersea Survey (FAMOUS) the French team participating in the mission explored the active A transform fault with the diving saucer CYANA, and discovered a characteristic hydrothermal deposit. The results presented here concern the structural and radiochemical study of three samples: two metalenriched samples and one sample of consolidated calcareous sediment recovered from the area.It is shown that there is a chemical segregation between silica and iron on one hand, and manganese in the other hand, and that on such deposits the layer-by-layer radio-chemical analysis of the uranium series is not applicable.Three different age estimations may be made:In the managanese encrustation, thorium 230 is depleted towards equilibrium with its parent uranium 234, suggesting a maximum age of 45,000 years to the deposit.On the contrary, the outermost layer, 0.1 cm thick, formed essentially with loose sediment stained with oxides, presents an excess of thorium 230. The Σ²³⁰Th_(excess)/cm² may be used to calculate a minimum age of 20 years.Such a sediment thickness, in this area, corresponds to a time span of 50 years.     

Urban landslide monitoring by combined use of multiple methodologies - a case study on Sv. Anton town,Slovakia

ABSTRACT

We employed integrated methods to assess the landslide movement in Sv. Anton town in the Western Carpathians Neogene Volcanic Field (Central Slovakia). The integrated diagnostics required study of the landslide kinematic activity by a combination of Global Navigation Satellite Systems (GNSS) and Electrical Resistivity Tomography (ERT) imaging from November 2013 to March 2015. A topographic model with 2-cm accuracy was constructed from Unmanned Aerial Vehicles (UAV) photogrammetry. Continuous spatial datasets of movement and displacement field vectors were interpolated from the measured movements over the entire study period. Although deformation studies in Slovakia have a long-term tradition, complex interdisciplinary studies in urbanized areas are still lacking. This inspired our main objectives: to identify landslide kinematics and to reconstruct and define the rates of annual landslide movement obtained from geodetic measurement at the monitoring points. Our results demonstrate how landslide integrated diagnostics contribute to the detection of slope instability, with a maximum velocity of 60.82 mm/yr during the summer period. The precipitation effects are consistent with the Sv. Anton landslide displacement acceleration, and the following increases in total monthly precipitations are staggering compared to long-term monthly averages: July precipitation increased by 175.3%, August by 203.3%, and September by 198.1%.     

Rapid apsidal motion in V381 Cassiopeiae

V381 Cas is a relatively bright and early-type eclipsing binary system. Several new times of its eclipses were measured as part of our long-term observational project of eccentric eclipsing binaries. Based on a current O–C diagram solution, we found for the first time that its orbit is slightly eccentric (e = 0.025) and shows a very rapid apsidal advance with short period of about 20 years only. The relativistic and third body effects are negligible, being about 3% of the total apsidal motion rate.