نتایج جستجو برای: underground mines
تعداد نتایج: 20867 فیلتر نتایج به سال:
Severe natural conditions and complex terrain make it difficult to apply precise localization in underground mines. In this paper, an anchor-free localization method for mobile targets is proposed based on non-metric multi-dimensional scaling (Multi-dimensional Scaling: MDS) and rank sequence. Firstly, a coal mine wireless sensor network is constructed in underground mines based on the ZigBee t...
Due to the improvement of production technology and the adjustment of energy structure, as well as the town-ownership and private-ownership coal mines (TPCM) were closed or merged by national policy, the number of underground miner has changed comparing with 2004 in China, so collective dose and normalization collective dose in different type of coal mine should be changed at the same time. In ...
Acidity of water from abandoned underground mines decreases over time, and the rate of decrease can help formulate remediation approaches and treatment system designs. The objective of this study was to determine an overall acidity decay rate for above-drainage underground mines in northern West Virginia from a large data set of mines that were closed 50 to 70 yr ago. Water quality data were ob...
In December 2003, the assets of the Cassandra Mines (N.E. Halkidiki, Greece) of TVX HELLAS S.A., were transferred by law, ratified by the Greek Parliament, to the Greek State for 11 million euros. They were sold the same day to HELLAS GOLD S.A. for the same price without prior economic assessment of the assets and without an open competition [19]. The assets include mining and exploration conce...
The demand for increasing speed and low power dissipation triggers numerous research efforts with the increasing demand of wireless portable communication systems in underground mines driven by batteries. Presence of highly flammable gases in underground mines prohibits the use of higher power dissipating electronic systems. Low power wireless portable communication devices can safeguard the li...
OBJECTIVE To determine whether the prevalence of coal workers' pneumoconiosis (CWP) or progressive massive fibrosis (PMF) among United States underground miners is associated with mine size. METHODS We examined chest radiographs from 1970 to 2009 of working miners who participated in the National Coal Workers Health Surveillance Program for the presence of small and large opacities consistent...
Dust can be produced by almost all mining operations in underground coal mines and seen all around the mine. Different occupational groups get exposed to different dust levels and in order to minimize the probability of developing coal workers' pneumoconiosis (CWP), it is necessary to investigate the workers exposed to dust. This study aimed to evaluate the dust concentration conditions in unde...
This paper presents a low power, cost-effective, And Zigbee protocol based wireless sensor network that provides an intelligent surveillance and safety system for underground coal mines. The system consists of wireless connection of several nodes. Sensor node mainly consists of Zigbee protocol based low power CC2530 transceiver integrated with a high performance, low power microcontroller on si...
Shaft sinking is one of the main parts in underground mine planning. Shaft has various applications in underground mines e.g. minerals exiting flow, gases entrance or exit way, stope developments for exploitation etc. Considering that this section requires an abundance of expenses, management always following the election is the way that both terms have the technical considerations, economic co...
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...
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