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1
Content available Research on sand resistance performance of comprehensive protection facilities for desert hinterland highways under strong wind environment
Yin Wenhua, Wang Xu, Wu Yongxiang, Wang Fang
Archives of Civil Engineering
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2022
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Vol. 68, nr 4
683--698
EN
Based on the test and observation of the desert hinterland wind field, combined with the numerical simulation of Fluent wind-sand two-phase flow, the sand resistance performances of comprehensive protection in the desert hinterland under strong wind environment are researched. The transient wind speed and wind direction around the comprehensive protection facility are measured by two 3D ultrasonic anemometers on the highway in the desert hinterland, and the initial wind speed of the sand flow is provided for the numerical simulation boundary. The sedimentary sand particles around the comprehensive protection facility are collected for particle size analysis, and the particle size distributions of sedimentary sand particles at different locations are obtained. Numerical models of high vertical sand barriers, grass checkered sand barriers and roadbeds are established by Fluent, the wind-sand flow structures around the comprehensive protection facilities and desert hinterland highway under the strong wind environment are obtained, and the influence laws of the comprehensive protection facilities on the movement of wind-sand flow and sand deposition characteristics are obtained. The study found that the comprehensive protection facilities disturbed the wind and sand flow, and there are significant airflow partitions around the comprehensive protection facilities. The wind speed decreases rapidly after the wind-sand flows through the high vertical sand barrier; the wind-sand flow rises at the end of the high vertical sand barrier. When the wind-sand flow moves around the grass checkered sand barrier, the wind speed has dropped to the range of 0-3 m/s, and the wind speed near the ground by the grass checkered sand barrier is further reduced. Due to the existence of the concave surface of the grass grid, there are small vortices inside the grass grid sand barrier. Large sand particles are mainly deposited on the windward side and inside of high vertical sand barriers. The grass checkered sand barrier forms a stable concave surface to generate backflow, which can ensure that the sand surface does not sand itself in a strong wind environment, and can also make a small amount of sand carried in the airflow accumulate around the groove of the grass checkered sand barrier. The numerical simulation results are consistent with the measured results, and the comprehensive protection measures have achieved good sand control effects.
2
Content available remote Denoising of desert seismic signal based on synchrosqueezing transform and Adaboost algorithm
Sun Xiaofu, Li Yue
Acta Geophysica
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2020
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Vol. 68, no. 2
403--412
EN
Seismic data in desert area generally have low signal-to-noise ratio (SNR) due to special surface conditions. Desert noise is characterized as low-frequency, non-Gaussian and non-stationary noise, which makes the noise suppression in desert area more challenging by conventional methods. Conventional methods are efective for the signal with high SNR, but in desert seismic signal, the SNR is low and the signal can easily be obliterated in desert noise. In this paper, we propose an approach that operates in synchrosqueezing transform (SST) domain and use classifcation techniques obtained from supervised machine learning to identify the coefcients associated with signal and noise. First of all, we transform the real desert seismic data into time–frequency domain by SST. Secondly, we select features by calculating the SST coefcients of signal and noise. And then, we train them in the Adaboost classifer. Finally, when the training is completed, we can obtain the fnal classifer that can efectively separate the signal from noise. We perform tests on synthetic and feld records, and the results show great advantages in suppressing random noise as well as retaining efective signal amplitude.
3
Typowe ogrody australijskiej pustyni
Kożuszek R.
Zieleń Miejska
|
2017
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Nr 5
24--26
PL
Najważniejszym aspektem w kreowaniu ogrodów pustyni jest zminimalizowanie strat wody, które w suchym klimacie potrafią być ogromne. Idealnymi przykładami na typowe ogrody pustyni są te zlokalizowane w najgorętszym i najsuchszym mieście świata – w Alice Springs w Australii.
4
Content available Landscape values of Joshua Tree National Park
Świtalska A.
Przestrzeń i Forma
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2017
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nr 30
279--294
EN
This article presents the landscape in Joshua Tree National Park in the United States and shows the different degrees of accessibility of individual locations. Selected places in the park are described. The analysis of the number of visitors indicated whether it is worthwhile to preserve nature and to protect it. It also respond to questions relating to the need for human interaction with nature.
PL
Artykuł przedstawia krajobraz w Parku Narodowym Drzewo Jozuego w Stanach Zjednoczonych oraz ukazuje różne stopnie dostępności poszczególnych lokalizacji. Opisane zostały wybrane miejsca w parku. Analiza liczby odwiedzających wskazała, czy warto zachowywać naturę oraz ją chronić i odpowiedziała na pytania odnoszące się do potrzeby obcowania człowieka z naturą.
5
Content available Formation conditions and diagenetic evolution of Sand Roses in clastic sabkhas along the Arabian Gulf Coastal Region, Eastern Saudi Arabia
Al-Hussaini A., Koeshidayatullah A., Al-Ramadan K.
Geological Quarterly
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2015
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Vol. 59, No. 1
71--78
EN
This field, petrographic and geochemical study aims at constraining the formation and diagenetic evolution of sand roses (desert roses) in interdune sabkhas in Eastern Saudi Arabia. These “roses”, which are mainly cemented by gypsum, carbonate, and clay minerals, occur as disc-shaped and spherical flower-like crystals. Sands, within the sand roses, are moderately-sorted, medium-grained, and sub-arkosic. Gypsum typically exceeds 20% of the volume of the roses, and locally gypsum is partly transformed to anhydrite. In addition to gypsum and anhydrite, early diagenetic modifications include precipitation of grain coating clay, dissolution of unstable grains (e.g., feldspar grains), and weak mechanical compaction. Iron oxide cement was formed when the sand roses exposed to the surface. The XRD and petrographic data indicate an increase in amounts of gypsum cement from the water table upward towards the sabkha surface. The sand roses also are larger and lighter in colour away from the water table. This study is expected to provide a better understanding of the mode of sand roses formation in the interdunes areas, as well as the diagenetic alterations in both phreatic and vadose zones.
6
Content available Research of flint patina from the Eastern Desert of Egypt
Pawlikowski M., Sęk M., Sitarz M.
Auxiliary Sciences in Archaeology, Preservation of Relics and Environmental Engineering
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2014
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nr 18
1--8
EN
The subject of patination of flint has been discussed in many scientific publications. The majority of research concentrates on the applicability of the criterion of patina thickness on determining the age of flint artefacts, as well as for studying the correlation of archaeological profiles. Detailed knowledge of the mechanisms of patination, both in terms of physical and chemical, as well as mineralogical processes, is necessary for the correct interpretation carried out for each archaeological site. The large number of factors affecting patination greatly complicates any analysis of these conditions. This publication presents the research results of desert patina developed on flint artefacts in the conditions of the Eastern Desert of Egypt. Studies indicate mineralogical and chemical variability of patina in different types of flint.
7
Content available Piaszczysto-skalista pustynia Wadi Rum w południowej Jordanii
Jarmołowicz-Szulc K.
Przegląd Geologiczny
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2009
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Vol. 57, nr 4
283-285
8
Content available remote Intensity of organic matter decomposition in various landscapes of Caucasus (Daghestan)
Fischer Zofia, Niewinna Magdalena, Yasulbutaeva Irina
Polish Journal of Ecology
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2006
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Vol. 54, nr 1
105-116
EN
Decomposition process in the soil of desert, steppe and mountain landscapes was studied in the region of Caucasus (Daghestan). The study sites differed mainly in average temperature and humidity being generally extremely dry with soil poor in organic matter. Two methods - bags with grass and cellulose filter paper discs were used. No dependence was found between the rate of decomposition of introduced organic matter and organic nitrogen content, and C:N ratio in soil, but strong dependence was found with temperature and humidity conditions. The measured rate of organic matter decomposition in soil of desert, steppe, and mountain sites indicated that the level of decomposition activity of these soils is high. In summer it is lowest in steppe (1.97 mg [x] g^-1 [x] 24 h^-1), whereas the highest in mountains (5.68 mg [x] g^-1 [x] 24 h^-1). The annual average rate of decomposition of cellulose discs and hay in mountain site was almost two times higher than in steppe site and nearly three times higher than in desert site. Mainly climatic conditions i.e. long-lasting drought (almost all the year) in desert as well as in steppe (January to August) are responsible for this difference.
9
Content available remote Jordania - geoturystyczny raj
Pająk J.
Geoturystyka
|
2004
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T. 1, nr 1
59-64
PL
Artykuł ten jest relacją z wyprawy studentów WGGiOŚ AGH do Jordanii, monarchii islamskiej na Półwyspie Arabskim. Graniczy ona z Syrią, Irakiem, Arabią Saudyjską, Palestyną oraz Izraelem. Kraj ten bogaty jest w różnorodne atrakcje turystyczne, związane z historią tychże obszarów, kulturą, a także szeroko pojętą geologią. Celem wyprawy było dotarcie do najciekawszych, pod względem geoturystycznym, obiektów geologicznych. Na trasie znalazły się: Morze Martwe, najniżej położone miejsce na Ziemi, Pustynia Wadi Rum oraz Petra, miasto będące dawniej stolicą Nabatejczyków wyrzeźbione w bajecznie kolorowych piaskowcach.
EN
The paper deals the expedition of students of the Faculty of Geology, Geophysics and Environmental Protection to Jordan, an Islamic Monarchy on the Arabian Peninsula. It borders upon Syria, Iraq, Saudi Arabia, Palestine and Israel. There are various touristic attractions connected with amazing history of the country, its culture and also geology. The main reason of this trip was to visit the most interesting geological sites considering geotourism. The route included the Dead Sea the lowest point on Earth, Wadi Rum Desert and Petra - the old Nabataean Arabs city carved in the marvelous sandstone.
10
Content available Środowiska sedymentacji i rozwój depozycji osadów górnego czerwonego spągowca w rejonie Poznania
Aksamitowska A.
Przegląd Geologiczny
|
2003
|
Vol. 51, nr 2
168-174
PL
W obrębie osadów górnego czerwonego spągowca wydzielono kilkanaście litofacji oraz określono środowiska ich depozycji. Na podstawie przestrzennej analizy powiązanych ze sobą genetycznie litofacji opisano następstwo środowisk sedymentacyjnych w czasie i przestrzeni oraz czynników warunkujących ich rozwój. Było to podstawą do scharakteryzowania systemów depozycyjnych oraz opisu rozwoju sedymentacji górnego czerwonego spągowca na badanym obszarze. Rozpoznano dwa systemy depozycyjne: eoliczny i fluwialny. Ich rozwój i rozprzestrzenienie były kontrolowane przez procesy o charakterze tektonicznym oraz zmiany klimatyczne. Przeprowadzone badania pozwalają na dokładniejsze przeanalizowanie paleogeografii permskiej w trakcie sedymentacji osadów górnego czerwonego spągowca.
EN
Several lithofacies and their sedimentary environments were recognised within Upper Rotliegend deposits. Spatial analysis of genetically related lithofacies, allowed to descrite the sequence of sedimentary environments and factors controlling their evolution. It was the basis to characterise the depositional systems of the Upper Rotliegendes in the eastern Wielkopolska area. Two depositional systems were recognised: aeolian and fluvial. Their evolution was controlled by tectonic and climatic factors. This study permits a refinement ofpaleogeographic interpretation of the Upper Rotliegendes deposits.
11
Content available remote Odkrywanie tajemnic pustyni
Linsenbarth A.
Geodeta : magazyn geoinformacyjny
|
2000
|
nr 12
82--86
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