374 research outputs found
Study of ISM tracers in galaxies
We collected data for two samples of normal and interacting galaxies for a
total of 2953 galaxies having fluxes in one or more of the following wavebands:
FIR, 21 cm line, CO(1-0) lines and soft X-ray. The large set of data obtained
allowed us to revisit some of the already known relations between the different
tracers of the interstellar medium (ISM), such as the link between the FIR flux
and the CO line emission, the relation between X-ray emission and the blue or
FIR luminosity. The relation lacking from observations for early-type galaxies
has been discussed and explained in detail in the frame of a suitable
theoretical model, obtained by coupling chemo-dynamical N-body simulations with
a dusty spectrophotometric code of population synthesis.Comment: 2 pages, o appear in the Proceedings of the Conf. "From Stars to
Galaxies: Building the Pieces to Build Up the Universe", Vallenari et al.
eds., ASP Conf. Serie
Modelling and Mapping Elusive Locations of Historic Water-Powered Grist Mills
Abstract. Grist mills are structures in which stone wheels are used to grind grain (e.g. corn, wheat) into a powder-like form for human consumption. Circular stone wheels provided the pressure to grind the grain and separate seed components. In most grist mills the energy for turning the heavy stones was derived from water power. The most visible part of some these mills was the externally mounted water wheel. However, other common configurations of the water 'turbine' internal to the structure were used (Figure 1). While grist mills existed in Europe at least as early as the 11th century such mills were not present in the United States until the last 1600s. No comprehensive census has been conducted for grist mills in the U.S. although an estimate of all water powered mills in eastern U.S. was 65,000 in 1840. Many of these water powered mills in the census estimate were for textile, sawmills, manufacturing, and other non-grain-grinding applications.Most often, the mill site included a small impoundment for creating a reliable source of water during low-flow stream conditions. These ponds were created in the late 1700s and especially in the 1800s as a reliable water source for turning grist or saw mills. By the middle of the 20th century the grist mills had all but vanished. Except for a few historic relics and conversion to touristic sites, the mill infrastructure has disappeared on the landscape while the mill ponds typically remain, serving other purposes, such as fishing or hunting lakes, or merely aesthetic environments.The local ecosystems around the mills sites have been artificially modified by the presence of these stream impoundments providing a new environment for fish, mammals, avian species, and of course, humans. While numerous positive ecosystem values may be observed from their continued presence, the risk of dam failure to both downstream systems and humans is substantial. In fact, such a catastrophic series of dam failures (51 in South Carolina) occurred in October of 2015 from a heavy rainfall event. In other instances the impoundments now store toxic sediment originating from sources farther upstream such as mining, military or industrial processes.Where are these historic mill sites and mill ponds? No inventory of mills or their ponds exist in South Carolina (and only for a few northeastern states). In this research we developed a systematic approach for identifying and mapping historic mill sites and ponds using a geohistorical framework and applied to South Carolina. The approach relied on 1) numerous geospatial sources, and 2) an analytical model of confidence mapping for predicting sites. The developed approach resulted in a new database of definitive and likely historic mill sites and mill pond locations throughout South Carolina. The sources of geospatial information was largely cartographic in nature including the following:USGS Historic Topographic Map SeriesRobert Mills 1820 atlas covering South CarolinaHistoric aerial photographyNational Hydrography Data (NHD)National Wetlands Inventory (NWI)National Inventory of DamsSC Department of Health and Environmental Control for Regulated DamsToponyms from the Geographic Names Information System (GNIS)U.S. Census TIGER street dataThe design for a predictive model (Figure 2) using diverse historic data with various scales and reliability is problematic. Most of the grist mills have disappeared from the landscape and do not exist in contemporary geospatial databases. Historic maps might include toponyms for the sites or ponds but their map projection, scale, and subsequent distortions in geometry are problematic. In addition, some of the sources for data are derived from a similar source and thus, are not statistically independent. The design of the analytical model for mapping confidence in mill site locations was calibrated and subsequently validated using several independent sources of information. Numerous field visits to known and suspected locations for mills sites were conducted throughout the physiographic regions of South Carolina.The model of likelihood included factors for the reliability of the source, the mapping scale and spatial accuracy of the source, correlation with other sources, and likelihood of correspondence with grist mills.</p
The application of GIS in railway heritage management: the case of Yunnan-Vietnam Railway
Abstract. Railways were a key mode of transporting goods and people for industrial and urban development in the late modern age. Their special part in economic growth comes with their role in the development of cultural heritage along their pathways. However, because of competing urban construction, many railway heritages are in danger, such as the Yunnan-Vietnam Railway (YVR) in China, an important international narrow-gauge railway built in 1901, acknowledged as a railway heritage in 2018. As a typical linear heritage, the railway integrates both the natural and cultural landscapes, related to the large spatial extent and complex composition of single heritage elements. Geographic Information Systems (GIS) offer a great support in the investigation, assessment, and management of railway heritage. In this research, the huge cultural heritage related to the YVR was studied using a combined geo-historical and GIS approach. This paper aims to 1) give a brief review of the current status of the application of GIS on linear railway heritages studies, including heritage resources surveys, spatial analysis, thematic mapping and public service, 2) introduce the case study of the Yunnan-Vietnam Railway, and 3) present a geodatabase design for the Yunnan-Vietnam Railway heritage management.</p
Forests as Protagonists on Battlefields: the case studies of Rivers Bridge and Honey Hill Through the Lens of a HGIS
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