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Wireless underground sensor networks (WUSN) are a natural extension of the wireless sensor networks (WSN) phenomenon to the underground environment. In this work, experimental measurements are presented at the frequency of 433 MHz, which show a good agreement with the theoretical studies. Experiments are run to examine the received signal strength and the packet error rate for aboveground-to-un...

Evaluation of the Underground Economy in Quebec: A Microeconomic Approach The main purpose of this paper is to estimate the size and the growth of Quebec’s underground economy, and the corresponding loss of taxes for the government. Our approach is based on a method developed by Pissarides and Weber (1989) and extended by Lyssiotou et al. (2004). The basic hypothesis is that individuals can und...

A method for locating underground pipes from a pulse radar image is presented. The method employs the Laplacian of Gaussian filter to extract edges and employs the Hough transform to determine the depth of the pipes. A preliminary experiment showed its ability to detect deeply buried pipes with weak signal echoes. key words: radar image, Hough transform, LoG filter, underground locating

Knowledge of in situ stresses is fundamental to many studies in earth sciences, and coal mine ground control is no exception. During the past 20 years, it has become clear that horizontal stress is a critical factor affecting roof stability in underground coal mines. The theory of plate tectonics and the World Stress Map (WSM) project has been extremely helpful in explaining the sources and the...

A programmed software was developed in order to numerically simulate time variation of temperature field and snow depth around a pipe-in-pile snow-melting system, using meteorological data. The system utilized underground piles as heat exchanger between underground soil and water flowing inside the piles. The water was pumped into heat dissipation pipes embedded beneath pavement surface, on whi...

This paper is based on the open pit to underground mining practice of Daye Iron Mine. The influence mechanism between high-steep slope and non-pillar sublevel caving method is studied by using physical model test. Firstly, engineering geological properties of the choosing typical research section is analysed and generalized. Secondly, the system of open pit to underground mining is developing a...

At present, the cooling of all the hot underground operations at Impala is achieved by providing refrigerated air from surface. However, the depth of a number of planned projects will approach 2 000 m below surface and other future proposed operations will extend to even deeper levels. Obviously these depths will approach the horizon where acceptable underground conditions can no longer be achi...

This work studies the impact of estimating soil wave number in Underground Focused SAR imaging for tunnel detection applications. It is demonstrated that neglecting wave refraction at the ground surface results in poor underground imaging; however, by considering refraction with inexact, yet sufficiently high, estimates of soil dielectric constant, clear target images can be produced. In additi...