Wireless underground sensor networks (WUSNs) can enable many important applications such as intelligent agriculture, pipeline fault diagnosis, mine disaster rescue, concealed border patrol, crude oil exploration, among others. The key challenge to realize WUSNs is the wireless communication in underground environments. Most existing wireless communication systems utilize the dipole antenna to t...

The cadastral system provides land ownership information by registering and representing land boundaries on a map. The current cadastral system in Korea, however, focuses mainly on the management of 2D land-surface boundaries. It is not yet possible to provide efficient or reliable land administration, as this 2D system cannot support or manage land information on 3D properties (including archi...

Underground railway stations are known to have elevated particulate matter (PM) loads compared to ambient air. As these particles are derived from metal-rich sources and transition metals may pose a risk to health by virtue of their ability to catalyze generation of reactive oxygen species (ROS), their potential enrichment in underground environments is a source of concern. Compared to coarse (...

A wireless underground sensor network (WUSN) is defined as a network of wireless sensor devices in which all sensor devices are deployed completely underground (network sinks or any devices specifically for relay between sensors and a sink may be aboveground). In hybrid wireless underground sensor network (HWUSN), communication between nodes is implemented from underground-to-air or air-to-unde...

This paper describes successful industrial research and development in the area of underground coal mining equipment automation. A brief background to underground coal mining is given, and the process of longwall mining is detailed. Some of the major limitations and issues impacting on the productivity and safety of the longwall mining process are highlighted, which serve to motivate the automa...

Coal is the dominant source of energy in China, but about 50% of the coal resource is left underground unmined. Because of this, the “long-tunnel, large section, two-stage” Underground Coal Gasification (UCG) technology has been put forward, and the UCG model platform has been built. Simulation tests are underway and some gasification parameters have been obtained. Five field trials have been c...

We answer the following question dating back to J. E. Littlewood (1885–1977): Can two lions catch a man in a bounded area with rectifiable lakes? The lions and the man are all assumed to be points moving with at most unit speed. That the lakes are rectifiable means that their boundaries are finitely long. This requirement is to avoid pathological examples where the man survives forever because ...

Avian song learning is an important model system for understanding vocal learning in humans and other animals. Laboratory studies indicate that social interactions are critical for song learning, but field observations show that territorial males are aggressive to intruders, raising the question of whether young birds are tolerated, much less tutored in the wild. We examined how adult song spar...