oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
National Report for the International Association of Geodesy of the International Union of Geodesy and Geophysics 2011-2014  [PDF]
V. P. Savinykh,V. I. Kaftan,Z. Malkin,G. Pobedinsky,I. A. Stoliarov,R. Sermiagin,L. Zotov,V. Gorshkov,N. Shestakov,G. Steblov,P. Dokukin,A. Ustinov
Physics , 2015, DOI: 10.2205/2015IUGG-RU-IAG
Abstract: In this National Report are given major results of researches conducted by Russian geodesists in 2011-2014 on the topics of the International Association of Geodesy (IAG) of the International Union of Geodesy and Geophysics (IUGG). This report is prepared by the Section of Geodesy of the National Geophysical Committee of Russia. In the report prepared for the XXVI General Assembly of IUGG (Czhech Republic, Prague, 22 June - 2 July 2015), the results of principal researches in geodesy, geodynamics, gravimetry, in the studies of geodetic reference frame creation and development, Earth's shape and gravity field, Earth's rotation, geodetic theory, its application and some other directions are briefly described. For some objective reasons not all results obtained by Russian scientists on the problems of geodesy are included in the report.
National Report for the International Association of Geodesy of the International Union of Geodesy and Geophysics 2007-2010  [PDF]
E. A. Boyarsky,L. F. Vitushkin,M. D. Gerasimenko,G. V. Demianov,M. B. Kaufman,V. I. Kaftan,E. M. Mazurova,Z. M. Malkin,S. M. Molodenskii,Yu. M. Neyman,A. K. Pevnev,V. P. Savinykh,G. M. Steblov,S. K. Tatevian,S. A. Tolchel'nikova,N. V Shestakov
Physics , 2015,
Abstract: This report submitted to the International Association of Geodesy (IAG) of the International Union of Geodesy and Geophysics (IUGG) contains results obtained by Russian geodesists in 2007-2010. In the report prepared for the XXV General Assembly of IUGG (Australia, Melbourne, 28 June - 7 July 2011), the results of principal researches in geodesy, geodynamics, gravimetry, in the studies of geodetic reference frame creation and development, Earth's shape and gravity field, Earth's rotation, geodetic theory, its application and some other directions are briefly described. The period from 2007 to 2010 was still difficult for Russian geodesy mainly due to the permanent reformation of state geodetic administration as well as state education structure and organization. The report is organized as a sequence of abstracts of principal publications and presentations for symposia, conferences, workshops, etc. Each of the report paragraphs includes a list of scientific papers published in 2007-2010 including those prepared in cooperation of Russian scientists and their colleagues from other countries. Some interesting international and national scientific events are reflected in the text too. For some objective reasons not all results obtained by Russian scientists on the problems of geodesy are included in the report.
Grain Segregation Mechanism in Aeolian Sand Ripples  [PDF]
Hernan A. Makse
Physics , 1998,
Abstract: Many sedimentary rocks are formed by migration of sand ripples. Thin layers of coarse and fine sand are present in these rocks, and understanding how layers in sandstone are created has been a longstanding question. Here, we propose a mechanism for the origin of the most common layered sedimentary structures such as inverse graded climbing ripple lamination and cross-stratification patterns. The mechanism involves a competition between three segregation processes: (i) size-segregation and (ii) shape-segregation during transport and rolling, and (iii) size segregation due to different hopping lengths of the small and large grains. We develop a discrete model of grain dynamics which incorporates the coupling between moving grains and the static sand surface, as well as the different properties of grains, such as size and roughness, in order to test the plausibility of this physical mechanism.
To see a world in a grain of sand  [PDF]
Shou-Cheng Zhang
Physics , 2002,
Abstract: Throughout John Wheeler's career, he wrestled with big issues like the fundamental length, the black hole and the unification of quantum mechanics and relativity. In this essay, I argue that solid state physics -- historically the study of silicon, semiconductors and sand grains -- can give surprisingly deep insights into the big questions of the world.
ANN modelling for the determination of moulding sand matrix grain size  [PDF]
J. Jakubski,St. M. Dobosz,K. Major-Gabry?
Archives of Foundry Engineering , 2011,
Abstract: One of the modern methods of the production optimisation are artificial neural networks. Neural networks are gaining broader and broader application in the foundry industry, among others for controlling melting processes in cupolas and in arc furnaces, for designing castings and supply systems, for controlling moulding sand processing, for predicting properties of cast alloys or selecting parameters of pressure castings. An attempt to apply neural networks for controlling the quality of bentonite moulding sands is presented in this paper. This is the assessment method of sands suitability by means of detecting correlations between their individual parameters. The presented investigations were obtained by using the Statistica 9.0 program. The aim of the investigations was to select the neural network suitable for prediction the moulding sand matrix grain size on the basis of the determined sand properties such as: permeability, compactibility, and compressive strength.
Grain Size Analysis of a Growing Sand Bar at Sonadia Island, Bangladesh  [PDF]
Md. Enamul Hoque, Sayedur Rahman Chowdhury, Mohammad Muslem Uddin, Mohammed Shahidul Alam, Md. Mostafa Monwar
Open Journal of Soil Science (OJSS) , 2013, DOI: 10.4236/ojss.2013.32008
Abstract:

Sonadia is one of the most important islands of Bangladesh. South-eastern shore of the island, which is a growing sand bar, has to encounter continuous and rapid morphological changes. So study of the sediment characteristics of this Sand Bar is very important. In the present study, grain size analysis of this Sand Bar has been done on the basis of laboratory analysis. Sediment samples were collected from 9 (Nine) stations and texture analysis of sediment was completed following a standard procedure of sieve analysis of sand samples. The average value of median (MD), mean (M), standard deviation (s), skewness (SK) and kurtosis (K) of sediment of the Sand Bar of Sonadia Island was 1.93, 1.87, 0.44, 0.11 and 1.88 respectively. Highest median, mean, standard deviation, skewness and kurtosis of Sand Bar of Sonadia Island was 2.98 (Station 2, Lower Shore), 2.68 (Station 1, Lower Shore), 0.83 (Station 1, Middle Shore and Station 2, Lower Shore), 0.65 (Station 2, Lower Shore) and 3.59 (Station 1, Lower Shore) respectively. Lowest median, mean, standard deviation, skewness and kurtosis of Sand Bar of Sonadia Island was 1.42 (Station 9, Middle Shore), 1.45 (Station 9, Middle Shore), 0.30 (Station 5, Lower Shore and Station 8, Lower Shore), 0.04 (Station 5, Upper Shore) and 0.94 (Station 6, Upper Shore) respectively.

Influence of Aggregate Grain Size on the Formulation of Sand Concrete in the Construction Industry in Congo  [PDF]
Charlène Bassolokidi Nkengue, Narcisse Malanda, Gilbert Ganga, Paul Louzolo-Kimbembe, Guy Richard Mouengue
Geomaterials (GM) , 2019, DOI: 10.4236/gm.2019.94007
Abstract: The main objective of this study is to contribute to the optimization of the formulation of sand concretes and its valorisation according to natural sands from different quarries or extraction sites. Physical characteristics of natural sands have been determined and improved by the addition of crushing sand, taking into account the too fine elements of the sand. Four types of sand were used (Congo River, Djiri, Mfilou, crushed sand). The concrete formulations proposed from improved sands (30% crushed sand and 70% natural sand) reveal an increase in mechanical strength. Thus, it appeared that this improvement of the natural fine sands by the crushing sand has brought a clear increase in the maneuverability of the concretes and the physico-mechanical characteristics of nearly 50%, although this crushing sand has a sand equivalent value of less than 70%. These results augur well for the durability of structures in the construction industry in Congo.
A world in a grain of sand: human history from genetic data
Vincenza Colonna, Luca Pagani, Yali Xue, Chris Tyler-Smith
Genome Biology , 2011, DOI: 10.1186/gb-2011-12-11-234
Abstract: To see a world in a grain of sand ...William Blake, Auguries of InnocenceThe genome of each individual is a temporary assemblage of DNA segments brought together for a single generation by a combination of chance, ancestry, recombination and natural selection. These segments have different histories because of recombination and can thus provide independent information about ancestry, the focus of this review. However, the ancestry of different segments is not entirely independent. Humans are not a single randomly mating population: we are subdivided, and these subdivisions into bands, tribes, clans, ethnic groups, nations and so on are of great interest to both scientists and non-scientists. Thus the thousands of different genomic segments in any individual do not trace back to ancestors randomly spread around the globe; segment ancestry is constrained by population history. Two non-recombining segments of the genome, mitochondrial DNA (mtDNA) and the Y chromosome, have been used for decades to study genetic histories [1,2]. Sometimes mtDNA and the Y chromosome share the same history, but often they do not, and such differences alert us to some of the complexities of the human past [3]. But mtDNA and the Y chromosome provide only two perspectives. Recent advances in technology provide access to most of the genome, and increasingly to the genomes of companion species. Here, we consider how this wider perspective is beginning to inform our view of human history. We will see that it is possible to probe much further back into the past, into a period in which the uniparental markers are uninformative yet key evolutionary events took place, and even to speculate about when humans might have begun to wear clothes or to start reconstructing the genomics of former populations before their contact with modern expansions.Genome-wide data can be obtained by either genotyping samples or re-sequencing them. Genotyping provides information about the allelic state of positions in
Comparisons of grain size characteristics of red earth from southern China with that of loess and dune sand from Bering region
Shangfa Xiong,Zhongli Ding,Dongsheng Liu
Chinese Science Bulletin , 1999, DOI: 10.1007/BF03183492
Abstract: The comparisons of grain size distributions among eolian deposits along the monsoon wind trajectory are a fundamental task for the reconstruction of the past wind regimes. Here the authors sampled the dune sands in Hunsandak desert, loess deposits in Beijing region and red earth in southern China. Grain size analyses show that the distribution models of the loess and dune sand samples are unimodal whereas the red earth and paleosol are polymodal. The red earth, paleosol, loess and dune samples are distinguished and closely related to one another in grain size parameter diagrams. Moreover, the grain size distributions and parameters of the red earth and paleosol are similar, implying that the red earth in southern China and the paleosol in northern China had the same origin.
On the Quantum Aspects of Geophysics  [PDF]
F. Darabi
Physics , 2004,
Abstract: We introduce a simple quantum mechanical justification for the formation of folded mountains. It is very appealing to develop this idea to a theory of {\it Quantum Geophysics}
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.