112,489 research outputs found
Assessment of present day geomorphological dynamics to decipher landscape evolution around the Paleolithic sites of Melka Kunture, Ethiopia.
No full textAssessment of present day geomorphological dynamics to decipher
landscape evolution around the Paleolithic sites of Melka Kunture,
Ethiopia
Michael Maerker (1,2), Calogero Schillaci (1), Rita Melis (3), and Margherita Mussi (4)
(1) Heidelberg Academy of Sciences and Humanities, Germany ([email protected]), (2)
Department of Earth Sciences, Università degli studi di Firenze, Italy, (3) Department of Earth Sciences, Università degli studi
di Cagliari. Italy, (4) Dipartimento Scienze dell’Antichità. Università di Roma la Sapienza, Italy
The area of Melka Kunture (central Ethiopia) is one of the most important clusters of Paleolithic sites in Eastern
Africa. The archaeological record spans from c. 1.7 Ma onwards, with a number of stratified occurrences of
Oldowan, Acheulean, Middle Stone Age and Late Stone Age industries, together with faunal remains and human
fossils. However, the archaeological sites are endangered by flooding and soil erosion. The main excavation area
lies close to the convergence of the Awash river with the Atabella river, one of the main tributaries of the upper
Awash catchment. In the semi-arid Ethiopian highlands, gully networks develop especially in the vicinity of the
active and inactive river meanders. Various erosion processes are linked to specific driving factors such as the
rainfall regime, the land use/cover changes and vertic soils with a specific hydrological behaviour. It was documented
in the field and by previous research that the origin of most of the man made erosion channels is due to
animal pathways and car tracks. However, paleolandscape features increase the general erosion risk. Former wetland
areas and deposition zones are particularly affected by soil erosion processes. Hence, the spatial distribution
and characteristics of present day geomorphic processes also reveal information on the paleolandscape. In order to
assess landscape evolution and present day geomorphologic dynamics, we mapped the geomorphology describing
in detail the present-day slope processes at a 10.000 scale. We performed a detailed terrain analysis based on high
resolution DEMs such as SRTM-X with 25m resolution and ALOS/PRISM with 10m resolution to characterize
the main erosion processes and surface runoff dynamics. The latter ones are simulated using a Soil Conservation
Service Curve Number method. Landuse was delineated for a larger area using ASTER 25m multispectral data.
Finally, using calibrated topographic indices and a simple hydrological model we were able to detect and quantify
the major present day soil erosion and surface runoff processes. Based on the analysis of the processes and the
respective terrain features derived from the digital elevation models we also identified the major paelolandscape
features. This will be the basis for assessing conservation risks related to modern land use and climate
Desenvolvimento de um plano de marketing: CR Vigilância e Segurança Ltda.
Get PDFTCC (graduação) - Universidade Federal de Santa Catarina, Centro Sócio Econômico, Curso de Administração.O objetivo deste estudo é propor um Plano de Marketing a ser utilizado pela CR Vigilância e Segurança Ltda., traçando linhas de ação que permitirão viabilizar a expansão dos serviços de vigilância patrimonial. Para isto são revistos conceitos sobre marketing, serviços e plano de marketing, buscando na literatura um plano de marketing ideal para elaborar um plano para a organização. O plano de marketing utilizado possui as seguintes fases: a análise do macro e microambiente e definições estratégicas que englobam a definição da missão, visão, valores, objetivos, metas, estratégias, plano de ação e plano de custos, assim como implantação e controle. Verificou-se que a organização estudada não possui plano de marketing e atua de maneira desintegrada nas suas estratégias de marketing e comunicação e, através deste trabalho a organização poderá utilizar este plano para obter eficácia na sua atuação, bem como demonstrar que é de fundamental importância que as organizações tenham um plano de marketing definido para nortear a sua atuação e atender seu mercado alvo
Colorimetric characterization of ochres in a Palaeolithic flint pebble from Maschio dell’Artemisio, Latium, Italy
No full textThe flint pebble from Maschio dell’Artemisio, a peak of the Artemisio mountain range (South-East of Rome), represents one of the first complex artefacts from the Upper Palaeolithic of the Alban Hills possibly displaying a symbolic/artistic value (Altamura & Mussi, 2014). It has been used as a hammer stone and retoucher, to create or modify lithic implements. It shows a diffuse and intense ochraceous colour on almost half of its surface. In the present work we discuss the results of an innovative colorimetric approach to define the use of pigments in the Palaeolithic community of the area and eventually compare the raw materials with local supplies. Second-derivative diffuse reflectance spectroscopy (DRS) is a data treatment on colorimetric data used from the ‘80s in the characterization of soil (Scheinost et al., 1998). More recently, it has been applied on iron oxide and hydroxide minerals, to investigate their colour and crystal properties (Torrent & Barrón, 2003). Here it was used directly on an archaeological artefact, to determine the presence of yellow and red ochres, but also to quantify the amount of each pigment present in mixture on the surface. Data were acquired using either a colorimeter and fibre optic reflectance spectroscopy (FORS) and then compared to test the efficiency of both techniques.
Altamura F., Mussi M., Arte mobiliare paleolitica dalla Catena del Tuscolano-Artemisio, Lazio e Sabina 10 (2014), Atti del Convegno Decimo Incontro di Studi sul Lazio e la Sabina, Roma, 4-6 Giugno 2013, pp. 119-125
Scheinost A. C., Chavernas A., Barrón V., Torrent J., Use and limitations of second-derivative diffuse reflectance spectroscopy in the visible to near-infrared range to identify and quantify Fe oxide minerals in soils, Clays and Clay Minerals, 46(1998), 528-536
Torrent J., Barrón V., The visible diffuse reflectance spectrum in relation to the color and crystal properties of hematite,Clays and Clay Minerals, 51(2003), 309-31
Performance variability of aluminium hybrid lap-joints obtained by means of adhesives and ultrasonic welding
No full textThis paper presents the first results of the running project HY-LAP (HYbrid LAP-joints) carried out at the Dipartimento di Meccanica of the Politecnico di Milano in collaboration with MUSP and the University of Parma. Thin plates of aluminium 6022T4 have been joined by means of ultrasonic welding, structural adhesives and a combination of them; the applied experimental procedures (i.e. specimens preparation) have been described and the obtained joints have been characterized in terms of morphology and tensile-shear strength. Results are particularly effective in order to evaluate the relevance of the various phenomena influencing the hybrid joining technique, allowing a deep understanding of the process and the possibility to keep it under control. © 2010 Springer-Verlag France
Development of generalized tool life model for constant and variable speed turning
Get PDFIn this research, a generalized tool life modelling for considering non-stationary cutting conditions was developed. In particular, for the first time in literature, the model was conceived for predicting the life of the tool when spindle speed variation SSV, one of the most effective techniques for suppressing regenerative chatter vibrations, is used. The proposed formulation takes into account the main cutting parameters and the parameters associated to the SSV. A dedicated experimental campaign of turning tests was executed and the data were used for modelling purposes. The model validation was carried out performing additional tool life tests. According to the analyzed technological scenario, it was found that the generalized formulation can be used for predicting the tool life both at constant spindle machining CSM and adopting SSV with the maximum estimating error of 6%
A novel application of cryogenics in dieless sheet metal piercing
Get PDFIn tube punching, if the internal die is necessary to properly pierce the tube avoiding its collapse, it also represents a bottleneck to a rapid change of the punching set. In this research an innovative dieless tube punching approach has been conceived and studied. The use of a cryogenic fluid to force the material ductile-brittle transition is a way to limit the sheet deformation during the piercing process. The analysis of the innovative cryogenic punching was carried out both adopting numerical and experimental methodologies. A finite element FE model of the cryogenic punching was developed and updated in two stages. First, experimental tensile tests, performed at cryogenic temperatures, were used to characterize some material properties. Secondly, some piercing tests in cryogenic conditions were performed at different velocities and temperatures to fine update the model. A validation session was carried out to assess the model and the process feasibility. It was found that the FE model reproduced the experimental results within a maximum estimation error of 10% on both the punching force and tube deflection. Results showed that both the increment of the punching velocity and especially the decrement of the punching temperature could be the only viable solution for making the tube dieless punching industrially feasible
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
From ignorance to uncertainty: a conceptual analysis
Get PDFsummary:This paper aims to develop an analysis of how ignorance affects the reasoning activity and is related to the concept of uncertainty. With reference to a simple inferential reasoning step, involving a single piece of relational knowledge, we identify four types of ignorance and show how they give rise to different types of uncertainty. We then introduce the concept of reasoning attitude, as a basic choice about how reasoning should be carried out in presence of ignorance. We identify two general attitudes, analyze how they are related to different types of ignorance, and propose some general requirements about how they should affect the reasoning activity. A formalism for uncertain reasoning explicitly including the different types of uncertainty identified and satisfying the stated requirements is finally introduced and its performance is analyzed in simple examples
Zn nanoparticle formation in FIB irradiated single crystal ZnO
No full textWe report on the formation of Zn nanoparticles induced by Ga+focused ion beam on single crystal ZnO. The irradiated materials have been studied as a function of the ion dose by means of atomic force microscopy, scanning electron microscopy, Raman spectroscopy and transmission electron microscopy, evidencing the presence of Zn nanoparticles with size of the order of 5â30 nm. The nanoparticles are found to be embedded in a shallow amorphous ZnO matrix few tens of nanometers thick. Results reveal that ion beam induced Zn clustering occurs producing crystalline particles with the same hexagonal lattice and orientation of the substrate, and could explain the alteration of optical and electrical properties found for FIB fabricated and processed ZnO based devices
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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