The 1989 May outburst of the soft X-ray transient GS 2023+338 (V404 Cyg)

We reanalyse archival Ginga data of the soft X-ray transient source GS 2023+338 covering the beginning of its 1989 May outburst. The source showed a number of rather unusual features: very high and apparently saturated luminosity, dramatic flux and spectral variability (often on ∼1 s time-scale), and generally very hard spectrum, with no obvious soft thermal component characteristic for soft/high state.
We describe the spectrum obtained at the maximum of flux and we demonstrate that it is very different from spectra of other soft X-ray transients at similar luminosity. We confirm previous suggestions that the dramatic variability was the result of heavy and strongly variable photoelectric absorption. We also demonstrate that for a short time the spectrum of the source did look like a typical soft/high state spectrum but that this coincided with very heavy absorption.     

Mapping the porosity of international border to pedestrian traffic: a comparative data classification approach to a study of the border region in Austria,Italy, and Slovenia

National borders play an important role in everyday life. Interest in border studies has increased with recent changes in geographical locations of the border or the fluctuation of the permeability of the border between some countries, such as in the European Union. Whether the nations are trying to increase traffic flow of the border or to implement stricter border control, having appropriate information of the border is crucial for effective policymaking.

The objective of this research was to identify areas of high porosity, or high permeability, for pedestrians along the southern national border region in Carinthia, Austria using terrain, land use, and road data along with geocomputational methods. Two unsupervised classification methods, the fuzzy K-means clustering and the Self-Organizing Map, were applied to segment the border into homogeneous zones according to topographic and infrastructural attributes. The fuzzy K-means clustering method was chosen for its ability to allow for a continuous approach to classification. With this method, an object can belong, with different degrees of membership, to multiple classes, which is a more realistic reflection of the natural world than discrete clustering, where each object can only belong to one class. However, the fuzzy K-means clustering method does have disadvantages, i.e. the user must determine the number of classes and the input parameters are required to be in continuous format. The second classification method, the Self-Organizing Map, is a type of artificial neural network and was chosen for its ability to automatically determine the number of classes and handle categorical data. The Self-Organizing Map is unique because it can transform high dimensional data into low dimensional display while preserving the topology and spatial distribution of the input parameters. The results of the two classification methods suggest that the fuzzy K-means classification is more effective than the Self-Organizing Map for this situation. However, more research is needed to determine the fit of these algorithms for particular spatial data classification tasks.

The results obtained from this research provide an insight into the permeability of the border region of Carinthia, Slovenia, and Italy to pedestrian traffic and can be potentially useful for decision making processes for tourism development and road transportation management in that region. Furthermore, the approach presented in this article can be applied to other national borders to identify zones permeable to pedestrian traffic.     

Numerical simulation of catastrophic flood: the case study of hypothetical failure of the Bielkowo hydro-power plant reservoir

The numerical modeling of flood wave propagation following the hypothetical breaks of the embankments of the Bielkowo hydro-power plant storage reservoir (Kolbudy II Reservoir) on the Radunia River in Poland has been presented. The results of computations were used to estimate the parameters of the flood waves, which are indispensable for the flood zone determination and mapping and then for the flood risk analysis. When estimating the reach and area of the inundation, related to the embankments failures, digital terrain model, and mathematical model of flood wave propagation are necessary. For the numerical simulations of flood, the mathematical model of free surface, two-dimensional unsteady water flow was applied. Four locations of potential breaks of the reservoir embankments were considered. The computed flood zones were presented on the flood hazard maps. The maps have been used by the local authorities and the dam owner to manage the flood risk related to hydro-power plants operations on the Radunia River. This type of research has been done for the first time for the water plant managed by the ENERGA Elektrownie Straszyn.     

Landforms and landscape evolution in the Mylliem Granite Area,Meghalaya Plateau,Northeast India

The Mylliem granite is one of many igneous bodies within the basement complex of the Meghalaya Plateau, northeast India. Although relatively small in size at c. 90 km², it is very diverse geomorphologically and shows a range of distinctive landscapes within its limits. Relict flat watershed ridges and topographic basins characterize the northern and eastern part of the pluton, whereas to the southwest the relief becomes higher, with steeper hillslopes and deeply incised valleys. Deep weathering and thick saprolites are abundant, as are residual landforms resulting from stripping of the saprolite: domes, tors and boulders. The major reason behind the diversity of granite landscape of the Mylliem pluton is the progress of headward erosion, initiated at the Dauki fault in the south of the Meghalaya. Headward erosion enhances local relief and hence, weathering systems. Multi‐concave morphology is gradually transformed into multi‐convex one, which is hypothesized to be the specific mode of plateau evolution and scarp retreat in granite bedrock.     

Integrating geographical information systems and multiple criteria decision-making methods

Abstract

Many spatial decision-making problems, such as site selection or land use allocation require the decision-maker to consider the impacts of choice-alternatives along multiple dimensions in order to choose the best alternative. The decision-making process, involving policy priorities, trade-offs, and uncertainties, can be aided by Multiple Criteria Decision making (MCDM) methods. This paper presents a framework for integrating geographical information systems (GIS) and MCDM methods. In this framework the MCDM methods are classified and matched with choice heuristics used by the decision-makers in the presence of competing alternatives and multiple evaluation criteria. Two strategies for integrating GIS with MCDM are proposed. The first strategy suggests linking GIS and MCDM techniques using a file exchange mechanism. The second strategy suggests integrating GIS and MCDM functions using a common database. The paper presents the implementation of the first strategy using PC-ARC/INFO, a file exchange module, and four different MCDM computer programs.     

Lidar and the mobile Scene Modeler (mSM) as scientific tools for planetary exploration

With the continued success of the Mars Exploration Rovers and the return of humans to the Moon within the next decade, a considerable amount of research is being done on the technologies required to provide surface mobility and the tools required to provide scientific capability. Here, we explore the utility of lidar and the mobile Scene Modeler (mSM) - which is based on a stereo camera system - as scientific tools. Both of these technologies have been, or are being considered for, technological applications such as autonomous satellite rendezvous and rover navigation. We carried out a series of field tests at the 23 km diameter, 39 Ma, Haughton impact structure located on Devon Island in the Canadian Arctic. Several sites of geological interest were investigated, including polygonal terrain, gullies and channels, slump/collapse features, impact melt breccia hills, and a site of impact-associated hydrothermal mineralization. These field tests show that lidar and mSM provide a superior visual record of the terrain, from the regional (km) to outcrop (m to cm) scale and in 3-D, as compared to standard digital photography. Thus, a key strength of these technologies is in situ reconnaissance and documentation. Lidar scans also provide a wealth of geometric and structural information about a site, accomplishing the equivalent of weeks to months of manual surveying and with much greater accuracy than traditional tools, making this extremely useful for planetary exploration missions. An unexpected result of these field tests is the potential for lidar and mSM to provide qualitative, and potentially quantitative, composition information about a site. Given the high probability of lidar and mSM being used on future lunar missions, we suggest that it would be beneficial to further investigate the potential for these technologies to be used as science tools.     

Geology,stratigraphy and palaeoenvironmental evolution of the Stephanorhinus kirchbergensis-bearing Quaternary palaeolake(s) of Gorzów Wielkopolski (NW Poland,Central Europe)

The sedimentary succession exposed in the Gorzów Wielkopolski area includes Eemian Interglacial (MIS 5e) or Early Weichselian (MIS 5d–e) deposits. The sedimentary sequence has been the object of intense interdisciplinary study, which has resulted in the identification of at least two palaeolake horizons. Both yielded fossil remains of large mammals, alongside pollen and plant macrofossils. All these proxies have been used to reconstruct the environmental conditions prevailing at the time of deposition, as well as to define the geological context and the biochronological position of the fauna. Optically stimulated luminescence dating of the glaciofluvial layers of the GS3 succession to 123.6 ± 10.1 (below the lower palaeolake) and 72.0 ± 5.2 ka (above the upper palaeolake) indicate that the site formed during the Middle–Late Pleistocene (MIS 6 – MIS 5). Radiocarbon-dating of the lacustrine organic matter revealed a tight cluster of Middle Pleniglacial Period (MIS 3) ages in the range of ~41–32 ka cal bp (Hengelo – Denekamp Interstadials). Holocene organic layers have also been found, with ¹⁴C ages within a range of 4330–4280 cal bp (Neolithic). Pollen and plant macrofossil records, together with sedimentological and geochemical data, confirm the dating to the Eemian Interglacial.     

Reconstruction of subglacial depositional conditions based on the anisotropy of magnetic susceptibility: an example from Dębe (central Poland)

The analysis of low-field anisotropy of magnetic susceptibility (AMS) was used to reconstruct the subglacial deposition conditions during the Main Stadial of the Odranian Glaciation (MIS 6) in till deposits from a site in Dębe (central Poland). Based on the AMS parameters, six till beds were identified (intervals 1–6). The declination of the maximum magnetic susceptibility axis (k₁) indicates that the ice sheet was moving in from the northwest. The obtained results confirm the thesis about the preferred direction of ice-sheet transgression during the Odranian Glaciation (MIS 6) in this part of Poland. This interpretation is also confirmed by data obtained from measurements of the long axis of clasts, which agree with the orientation of k₁. Based on the AMS results, a significant part of the profile was deformed through simple shear and direct interaction of the ice sheet with the underlying sediment (beds 2–5). The lowest part of the till (bed 6) may have been deposited on a southeast-trending slope or post-depositional deformed by uneven loading of the ice cover. The upper part of the profile (especially in interval 1) could be deposited with an impact of pore water.