CPLat: first operational experimental processing center for SIRGAS in Argentina

The SIRGAS permanent GPS network which is in fact the IGS network densification for the American continent, consists today of more than 200 stations covering the continent and islands. It is currently processed by the IGS RNAAC SIR centre at Deutsches Geodätisches Forschungsinstitut producing weekly free solutions relying on IGS final orbits and EOP that contribute to the ITRF through IGS. By August 2006, the SIRGAS Working Group I had accepted five proposals for experimental processing centers within the region that would collaborate with IGS RNAAC SIR. One of them, Centro de Procesamiento La Plata (CPLat) in Argentina, began processing 60 stations on October 2006. By January 2007 CPLat reached operational capability, delivering weekly free solution SINEX files, with an internal consistency of 1.5 mm average for the horizontal components, and 3 mm in the vertical. Comparisons with IGS global and IGS RNAAC SIR weekly solutions were taken as external consistency indications, showing average RMS residuals of 1.8, 2.4 and 5 mm for the north, east, and vertical component, respectively. Analysis and comparison of adjusted solution time series from CPLat and other processing centers has proved to be highly valuable for solution QC, namely detection and identification of station anomalous behavior or modelling problems. These procedures will ensure the maintenance of the performance specifications for CPLat solutions. Action is being taken in order to guarantee the continuity of this effort beyond the experimental phase.     

Late quaternary seismic stratigraphy and active faults of the Gulf of İzmit (NE Marmara Sea)

The Upper Quaternary seismic stratigraphy and active faults of the Gulf of İzmit were investigated by means of high-resolution shallow seismic profiling data in the source region of 1999 İzmit earthquake. High-resolution seismic reflection data correlated with borehole data indicate that the stratigraphy of İzmit Bay consists of three distinct depositional sequences formed in response to middle Pleistocene-Holocene sea-level changes. Reflector R, separating the pre-Holocene sequences (1 and 2) from the Holocene sequence (3), represents an erosional unconformity produced by the subaerial fluvial erosion of the continental shelves at the time of the last glacial maximum. Occasional, anomalous reflections (acoustic turbidity) observed within the Holocene sequence are interpreted as gas accumulations. The maximum thickness of the Holocene sediments is found to be about 25 m. The isopach map of Holocene sediment implies that the thickness of the Holocene decreases from the east towards the central and western basins of İzmit Bay. Two distinct fault systems are interpreted in İzmit Bay. The main fault system extending roughly in an E-W direction along the Gulf of İzmit is an active right lateral strike slip fault with a normal component. The secondary faults are normal faults striking in different directions and these are identified as being both active and inactive. In addition, prominent compressive features are identified in the seismic cross-sections of some profiles acquired to the east of Hersek Peninsula where the focal mechanisms of the aftershocks of the 1999 İzmit earthquake also reveal predominantly reverse faulting mechanisms, as identified by a local dense seismic network.     

Organized bacterial assemblies in manganese nodules: evidence for a role of S-layers in metal deposition

Polymetallic/ferro-manganese nodules (Mn-nodules) reach sizes of up to 10 cm in diameter and are abundantly found on the seabed. To date, the origin of Mn-nodules remains unclear, and both abiogenic and biogenic origins have been proposed. In search of evidence for a contribution of microbial processes to the formation of Mn-nodules, we analyzed those spherical nodules which contain a concentrically banded texture in their interior. The Mn-nodules were collected at a depth of 5,152 m from the Clarion-Clipperton Zone. Our high-resolution scanning electron microscopy analyses reveal first published evidence that endolithic microorganisms exist and are arranged in a highly organized manner on plane mineral surfaces within the nodules. These microorganisms are adorned on their surfaces with S-layers, which are indicative for bacteria. Moreover, the data suggest that these S-layers are the crystallization seeds for the mineralization process. We conclude that the mineral material of the Mn-nodule has a biogenic origin, and hope that these data will contribute to the development of biotechnological approaches to concentrate metals from seawater using bacteria in bioreactors.     

Determining the weights of two types of artificial reefs required to resist wave action in different water depths and bottom slopes

The interaction between waves and artificial reefs (ARs; a hollow cube weighing 8.24 kN (0.84 t) and a water pipe weighing 1.27 kN (0.13 t)) in shallow waters was investigated with respect to variations in design weight, orientation (for cube; 45° and 90° angles, for pipe; 0°, 90°, and 180° angles to flow), depth (1–20 m), and bottom slope (10^?1, 30^?1, and 50^?1). Physics equations and FLUENT software were used to estimate resisting and mobilising forces, and drag coefficients. Drag coefficients for the hollow cube were 0.76 and 0.85 at 45° and 90° angles to the current, respectively, and 0.97, 0.38, and 1.42 for the water pipe at 0°, 90°, and 180° angles to the current, respectively. Deepwater offshore wave conditions at six stations were transformed into shallow nearshore waters representative of the artificial reef site. Waters deeper than 12 and 16 m are safe to deploy blocks with angles of 45° and 90°, respectively. However, water pipes constructed at angles of 90° and 180° to the current were estimated as being unstable for 365 out of 720 cases at all stations (only one station was stable for all cases). Water pipes angled at 0° were found to be stable in all 360 cases. Slope had a significant effect on weight and depth. Results from this study provide an important reference for engineers performing projects aiming to increase the performance and service life of ARs.     

断层垂直形变对强远震的响应

利用新型断层形变三维观测系统的垂直向观测结果, 研究了两年以来7.0级以上强远震在非发震断层上的同震响应特征. 结果表明,非发震断层体垂直向同震形变的延迟时间、 同震位移最大振幅、 振动持续时间等特征与地震震级、震中距等之间存在密切联系. 断层体垂直向同震形变延迟时间与震中距线性正相关,发生地震同震形变的响应速度约为5.5km/s,反映了在上层花岗岩地层中面波的传播速度;同震位移最大振幅和震中距的对数、 震级之间具有明显线性关系,震级越大,同震位移的最大振幅越大;地震震级是断层体垂直同震形变振动持续时间的主要影响因素,震级越大,同震形变振动持续时间越长. 根据断层仪观测数据推算得到的断层体垂直向同震形变延迟时间、同震位移最大振幅、振动持续时间的经验计算公式,对于地震同震形变研究具有一定意义.      

An on Orbit Determination of Point Spread Functions for the <Emphasis Type="Italic">Interface Region Imaging Spectrograph</Emphasis>

Using the 2016 Mercury transit of the Sun, we characterize on orbit spatial point spread functions (PSFs) for the Near- (NUV) and Far- (FUV) Ultra-Violet spectrograph channels of NASA’s Interface Region Imaging Spectrograph (IRIS). A semi-blind Richardson–Lucy deconvolution method is used to estimate PSFs for each channel. Corresponding estimates of Modulation Transfer Functions (MTFs) indicate resolution of 2.47 cycles/arcsec in the NUV channel near 2796 Å and 2.55 cycles/arcsec near 2814 Å. In the short (\({\approx}\,1336~\mathring{\mathrm{A}}\)) and long (\({\approx}\,1394~\mathring{\mathrm{A}}\)) wavelength FUV channels, our MTFs show pixel-limited resolution (3.0 cycles/arcsec). The PSF estimates perform well under deconvolution, removing or significantly reducing instrument artifacts in the Mercury transit spectra. The usefulness of the PSFs is demonstrated in a case study of an isolated explosive event. PSF estimates and deconvolution routines are provided through a SolarSoft module.     

Dynamical system analysis of a five-dimensional cosmological model

A five-dimensional cosmological model including a single perfect fluid is studied in the framework of dynamical system analysis. All the critical points of the system are listed with their stability properties and some representative phase diagrams are explicitly shown. It is found that the stabilization of extra dimension is possible and the observed flatness of the three-dimensional space is provided for certain ranges of the equation of state parameter of the fluid. The model suggested here can be considered as a simplified model for examining the possible effects of the extra dimensions in the early universe.     

Precipitable water vapor (PWV) estimations from the site of the Eastern Anatolia Observatory<Superscript>∗</Superscript> (DAG), a new astronomical observatory in Turkey

We present preliminary statistics on the precipitable water vapor (PWV) content over the Karakaya Hills in Erzurum city, where the largest optical and near-infrared astronomical telescope in Turkey will be operated. Since the observatory will observe in the near-infrared (NIR), it is intended to perform PWV measurements of the atmosphere above the site by using signal delays in Global Positioning System (GPS) communication. The analysis of the GPS data recorded on the summit for almost one year shows that the atmosphere over the site of the observatory, which has an altitude of 3170 m, has favorable conditions for NIR observations. From GPS measurements, we report that the site had an average PWV of 3.2 mm and a median PWV of 2.7 mm between October 6, 2016, and June 15, 2017. We also present the time dependency of the PWV content and the correlations between the amount of PWV and the other meteorological records gathered from radiosonde flights and ground-based measurements.     

Experimental impact cratering: A summary of the major results of the MEMIN research unit

This paper reviews major findings of the Multidisciplinary Experimental and Modeling Impact Crater Research Network (MEMIN). MEMIN is a consortium, funded from 2009 till 2017 by the German Research Foundation, and is aimed at investigating impact cratering processes by experimental and modeling approaches. The vision of this network has been to comprehensively quantify impact processes by conducting a strictly controlled experimental campaign at the laboratory scale, together with a multidisciplinary analytical approach. Central to MEMIN has been the use of powerful two-stage light-gas accelerators capable of producing impact craters in the decimeter size range in solid rocks that allowed detailed spatial analyses of petrophysical, structural, and geochemical changes in target rocks and ejecta. In addition, explosive setups, membrane-driven diamond anvil cells, as well as laser irradiation and split Hopkinson pressure bar technologies have been used to study the response of minerals and rocks to shock and dynamic loading as well as high-temperature conditions. We used Seeberger sandstone, Taunus quartzite, Carrara marble, and Weibern tuff as major target rock types. In concert with the experiments we conducted mesoscale numerical simulations of shock wave propagation in heterogeneous rocks resolving the complex response of grains and pores to compressive, shear, and tensile loading and macroscale modeling of crater formation and fracturing. Major results comprise (1) projectile–target interaction, (2) various aspects of shock metamorphism with special focus on low shock pressures and effects of target porosity and water saturation, (3) crater morphologies and cratering efficiencies in various nonporous and porous lithologies, (4) in situ target damage, (5) ejecta dynamics, and (6) geophysical survey of experimental craters.     

灰色稳健总体最小二乘估计及高铁路基变形预测

最小二乘估计和部分变量误差模型的总体最小二乘估计不具备抵御粗差的能力。鉴于粗差可能同时出现在灰色白化微分方程的观测值和系数矩阵中,本文提出基于IGGⅢ抗差方案的部分变量总体最小二乘稳健估计。结合仿真数据和高铁路基观测数据,系统地比较稳健最小二乘、部分变量总体最小二乘、本文算法参数估计结果和算法稳定性。结果表明,本文算法预测精度高,可以应用到高铁路基沉降预测中。