نتایج جستجو برای: rock material

تعداد نتایج: 400441  

M. G. Mahjani M. Jafarian, Y. Zeraatkish

Electrochemical properties of various rock-shaped-CuO/graphite (G) composites and monoclinic structure CuO nanoparticles as the cathode versus a zinc plate as the anode in a 4M NaOH electrolyte were elucidated by electrochemical impedance spectroscopy (EIS) and chronopotentiometry (CP) in a two electrode configuration cell. Various values of G 9, 16 and 28 wt% were prepared and studied as catho...

2008
Rakesh Kumar K. G. Sharma A. Varadarajan

ABSTRACT: A number of civil engineering projects which include river valley projects, transportation projects and metro rail projects are under construction in India. Various structures, such as underground openings, powerhouse caverns, metro tunnels, dam foundations and slopes are increasingly located in/on rock formations. The rock in its natural state is a very complex material especially wh...

2014
Sian Sullivan

The snake is a potent entity in many cultures across the world, and is a noticeable global theme in rock art and inscribed landscapes. We mobilise our long-term ethnographic research with southern African KhoeSan peoples to situate and interpret the presence of snake motifs in the region’s rock art. We contextualise the snake as a transformative ontological mediator between everyday and “entran...

2005
DAVID A. MCKEOWN JEFFREY E. POST

Rock varnish is a dark-colored Mnand Fe-rich coating that forms on exposed rock surfaces in almost every terrestrial weathering environment, particularly in arid and semiarid regions. Varnishes average about 100 μm in thickness but can reach thicknesses of several hundred micrometers, with accumulation rates of 1–15 μm/1000 years (Liu and Dorn 1996). Rock varnishes have attracted considerable r...

2001
Joshua Alexander Marshall

Towards Autonomous Excavation of Fragmented Rock: Experiments, Modelling, Identification and Control Joshua Alexander Marshall Master of Science (Engineering) Department of Mechanical Engineering Queen’s University August, 2001 Increased competition and recent globalization in the minerals industry has resulted in further demands for advanced mining equipment technology. The autonomous excavati...

2011
Ruyu Zheng

Analysis on the current research status, this article studies on the dynamic subsidence principles of overburden rock strata during coal mining based on similar material simulation test. Close ranged industrial photogram metric system was introduced to collect data. After coordinate transformation, matching and model amendment, dynamic subsidence curves which can be used to analyze the continui...

Journal: :Science 2000
B P Weiss J L Kirschvink F J Baudenbacher H Vali N T Peters F A Macdonald J P Wikswo

The ejection of material from Mars is thought to be caused by large impacts that would heat much of the ejecta to high temperatures. Images of the magnetic field of martian meteorite ALH84001 reveal a spatially heterogeneous pattern of magnetization associated with fractures and rock fragments. Heating the meteorite to 40 degrees C reduces the intensity of some magnetic features, indicating tha...

Ali Reza Yarahmadi Bafghi Hamid Reza Bakhshi Mehdi Mousavi

In the past, rock slope stability analysis were performed either graphically or using a hand-held calculator, but nowadays there are variety of slope stability analysis which can be used according to the field condition and potential failure mode. In 2-D analysis, effect of convex and concave walls are neglected, however concave slopes are believed to be more stable than straight walls due to t...

2008
Weixing Wang Peng-Yeng Yin

As known, most important, and the hard part of pattern recognition for rock particles, is image segmentation. Segmentation can be divided into two steps, one is segmentation based on gray levels (called image binarization, sometimes) in which a gray level image is processed and converted into a binary image. Another is segmentation based on rock particle shapes in a binary image, in which overl...

2006
M. R. Balme V. Rocchi C. Jones P. R. Sammonds P. G. Meredith S. Boon

A sound knowledge of mechanical properties of rocks at high temperatures and pressures is essential for modelling volcanological problems such as fracture of lava flows and dike emplacement. In particular, fracture toughness is a scale invariant material property of a rock that describes its resistance to tensile failure. A new fracture mechanics apparatus has been constructed enabling fracture...

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