Application of geodetic receivers to timing and time transfer

Two methods for smoothing pseudorange observable by Carrier and Doppler are discussed. Then the procedure based on the RINEX observation files is tested using the Ashtech Z-XII3T geodetic receivers driven by a stable external frequency at UNSO. This paper proposes to adapt this procedure for the links between geodetic receivers, in order to take advantage of the P codes available on L1 and L2, This new procedure uses the 30-second RINEX observations files, the standard of the International GPS Service (IGS), and processes the ionosphere-free combination of the codes P1 and P2 ; the satellite positions are deduced from the IGS rapid orbits, available after two days.     

Geochemical investigation and characterisation of Neogene sediments from Valjevo-Mionica Basin (Serbia)

Sediments from the Valjevo-Mionica Basin of Neogene age were investigated in this study using different geochemical methods. The results of the inorganic part analyses suggest that during genesis of the sediments, the contents of Na₂O, B and As changed the most, which indicates that genesis of the investigated sediments was followed by climate changes and volcanic activity. The quantity of other macro- and microelements did not vary significantly. Investigations of the organic substance showed that it is native organic matter, which has been preserved to a significant extent, formed predominantly of algal precursor organisms, which provided good quality, deposited under reducing conditions and that it is at a low maturity level. As it has been established that genesis of the investigated sediments was mostly affected by an arid climate with more intensive salinity, the aim of this study, was also to identify the processes which were the most affected by the change in salinity, as well as biomarkers which are the most sensitive to this change. The results led to the conclusion that the salinity increase in the depositional environment had a primary effect on the preservation of the organic substance and the formation of the mineral searlesite. In addition, it was noticed that besides the Sq/nC₂₆ ratio, the parameters nC₁₇/nC₂₇, CPI and Ph/nC₁₈, are also significantly sensitive to salinity change in a depositional environment in case of immature organic substance deposited under reducing conditions.     

Trace metals (Cd,Pb, Cu,Zn and Ni) in sediment of the submarine pit Dragon ear (Soline Bay,Rogoznica, Croatia)

Vertical profiles of trace metal (Cd, Pb, Zn, Cu, Ni) concentrations, organic matter content, carbonate content and granulometric composition were determined in two sediment cores from the submarine pit Dragon Ear (Middle Adriatic). Concentrations of the analyzed metals (Cd: 0.06–0.12 mg kg⁻¹, Pb: 28.5–67.3 mg kg⁻¹, Zn: 17.0-65.4 mg kg⁻¹, Cu: 21.1–51.9 mg kg⁻¹, Ni: 27.8–40.2 mg kg⁻¹) were in usual range for Adriatic carbonate marine sediments. Nevertheless, concentrations of Cu, Zn, and especially Pb in the upper layer of sediments (top 12 cm) were higher than in bottom layer, while Cd and Ni concentration profiles were uniform. Regression analysis and principal component analysis were used to interpret distribution of trace metals, organic matter and carbonate content in sediment cores. Results of both analysis showed that concentrations of all trace metals in the core below the entrance to the pit were significantly positively correlated with organic matter and negatively correlated with carbonate, while in the core more distant from the entrance only Pb showed significant positive correlation with organic matter. Obtained results indicated that, except for lead which was enriched in surface sediment, in the time of sampling (before the building of the nautical marina) investigated area belonged to unpolluted areas.     

The conspicuous red “impact” layer of the Fish Clay at Højerup (Stevns Klint,Denmark)

The marine Cretaceous-Paleogene boundary (KPB) section at Højerup-Fish Clay consists of a very thin red smectite-rich carbonate-poor (“impact”) layer overlain by a thick black marl. Similar red layers are found in the KPB sections at Agost in Spain and El Kef in Tunisia.Smectite of the red layer of the KPB section at Højerup is probably detrital and redeposited from adjacent coastal or marine areas. This clay mineral is likely mixed with a small amount of smectite derived from impact glasses. Most of the microspherules and nano-size glasses of the red layer at Højerup are probably detrital and simultaneously redeposited with smectite. The deposition of the red layer occurred for several decades to a century at most.     

Source potential and palynofacies of Late Jurassic “Lemeš facies”, Croatia

Laminated limestone and calcareous shale outcrop samples from the Late Jurassic “Leme?” facies (Croatia) were investigated to characterize their organic facies and palynofacies and their hydrocarbon generative potential. The results indicate that the organic rich sediments of “Leme?” facies were deposited within a relatively shallow marine environment at low redox potential, characterized as an oxygen depleted depositional setting with stratified bottom waters of the carbonate platform (Adriatic Carbonate Platform). The organic rich samples contain a high portion of lipid rich amorphous kerogen of algal/phytoplankton origin, enriched by bacterial biomass. Most of the analyzed samples have total organic carbon contents (TOC) greater than 3%, Rock-Eval S2 >20 mg HC/g rock, yielding Hydrogen Index (HI) values ranging from 509–602 mg HC/g TOC. According to these results, the analyzed samples have very good to excellent oil generative potential. Relatively high sulfur content suggests that the kerogen is best described as Type II-S. Biomarker maturity parameters, as well as the fluorescence of the isolated kerogen, show that the organic matter is at early to peak oil thermal maturity. The observed level of thermal maturity indicates that these samples were once buried to depths of ～5.5–5.8 km before being uplifted in the late Tertiary. The surface outcrops of the “Leme?” facies suggest that these strata have significant source potential and are the likely source of oil in the Croatian External Dinarides.     

2-Gyr Simulation of the Oort-cloud Formation II. A Close View of the Inner Oort cloud after the First Two Giga-years

We simulate the formation of the Oort cloud (OC) till the age of 2 Gyr starting from an initial disc of planetesimals made by 10 038 test particles. The results on the outer part of the distant comet reservoir are reported by Neslu?an et al. (this issue). Here we deal with the evolution of the population and structure at 2 Gyr of the complementary inner part of the Oort cloud. The dynamical evolution of the massless test particles was followed via the numerical integration of their orbits. We considered the perturbations produced by four giant planets assuming they have their current orbits and masses, as well as the perturbations caused by the Galactic tide and passing stars. The efficiency of the formation of inner OC is found to be very low: only about 1.1% of all considered particles ended in this part of the OC. At 2 Gyr, the dynamics of the inner cloud is mainly governed by the dominant z-term of the Galactic tide. The number density of the bodies is proportional to the heliocentric distance, r, as r ^?3.53. The directional distribution of orbits is still strongly inhomogeneous. There are large empty regions in the space angles around the Galactic Equator points with the galactic longitude 90 and 270° (non-rotating frame), or there are only few bodies having the ecliptical latitude higher than +60° or lower than 60°. A strong concentration of objects at the Ecliptic is apparent up to ≈1,000 AU, with a possible—but still not proved—extension to ≈1,500 AU. Beyond r ≈ 6,000 AU, bodies directly above and below the Sun, with respect to the Ecliptic, are absent.     

地震诱发的堰塞湖初步研究

由于地震引发山体滑坡并堵塞河道形成的湖泊称为地震堰塞湖。据统计,我国自1856年以来,共计产生141个地震堰塞湖,按照其形成和造成的灾害来看,堰塞湖可以分为3类:高危型堰塞湖、稳态型堰塞湖和即生即消型堰塞湖。高危型堰塞湖由于蓄水量大、落差大,往往在形成后几天至几年后会被冲垮,形成严重的地震滞后次生水灾。稳态型堰塞湖(亦称“死湖”),可以存在很长时间且湖积水量很大。即生即消型堰塞湖为震时形成的短时堰塞湖,很快会被后来累积的水体冲毁,一般危害不大。如果简单的用时间来区分堰塞湖的类型,那么在一天或者几天内溃决的是即生即消型堰塞湖;几天至100年溃决的是高危型堰塞湖;溃决时间超过100年者,是稳态型堰塞湖。     

白音华一号露天南帮工程地质特征分析

在分析矿区地层岩性、构造和水文地质条件的基础上,依据岩石的物理力学性质,确定了矿区边坡的软弱层面,同时对矿区南帮（非工作帮）的工程地质特征进行了研究。认为：第四系松散层具饱水性质,新近系地层以膨胀性的粘土（岩）为主,可塑性较强,易崩解,抗压、抗剪强度低,煤系地层以软岩为主,力学强度亦低,矿区工程地质特征为二类一型。据此预测了该区可能产生的工程地质问题,并提出了相应预防措施。     

混凝土灌芯纤维增强石膏板T形节点构件抗震性能试验研究

本试验对4组混凝土灌芯纤维增强石膏板T形纵横墙节点构件进行了低周反复试验研究,分析了混凝土灌芯纤维增强石膏板T形节点构件在水平低周反复荷载和常竖向荷载共同作用下的抗震性能(包括承载能力、变形能力、刚度退化、滞回环和耗能能力)以及结构的破坏特征,并对不同配筋形式的构件作了相应对比分析,得出了混凝土灌芯纤维增强石膏板T形节点构件配置水平拉接筋形式可以取代配置箍筋形式和抗剪性能优于普通砌体纵横墙节点构件的结论,为混凝土灌芯纤维增强石膏板结构的纵横墙节点抗震设计提供一定的试验依据和理论指导。