Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 2
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

Mining the lower seams in a sequence of shallow, closely spaced coal seams causes serious air leakage in the upper goaf; this can easily aggravate spontaneous combustion in abandoned coal. Understanding the redevelopment of fractures and the changes in permeability is of great significance for controlling coal spontaneous combustion in the upper goaf. Based on actual conditions at the 22307 working face in the Bulianta coal mine, Particle Flow Code (PFC) and a corresponding physical experiment were used to study the redevelopment of fractures and changes in permeability during lower coal seam mining. The results show that after mining the lower coal seam, the upper and lower goafs become connected and form a new composite goaf. The permeability and the number of fractures in each area of the overlying strata show a pattern of „stability-rapid increase-stability“ as the lower coal seam is mined and the working face advances. Above the central area of goaf, the permeability has changed slightly, while in the open-cut and stop line areas are significant, which formed the main air leakage passage in the composite goaf.

Go to article

Authors and Affiliations

Zhenqi Liu
Xiaoxing Zhong
Botao Qin
Hongwei Ren
Ang Gao
Download PDF Download RIS Download Bibtex

Abstract

The aftermath of including new technologies in a modern electric system in conjunction with the incessant rise in power demand could pose a risk to the optimal operation of the system. Therefore, it becomes imperative to identify the most influential and critical nodes of such a system to avert future problems in network operation. In this paper, to identify most significant nodes of the system, the authors propose two measures of centrality in accordance with the network structural properties of a power system, namely, degree centrality (DC) and eigenvector centrality (EC). These are expressed considering the admittance matrix that exists among the interconnection of load to load nodes in an electrical power network. A critical node closeness centrality (CNCC) method is also proposed to identify critical nodes of the system. This is done by modifying the conventional closeness centrality (CC) to include the influence of interconnection that exists between network load to load nodes as captured by the admittance matrix between them. A comparative analysis of the proposed techniques with other conventional methods is also carried out. The result of the simulation shows that the proposed methods could serve as alternative tools in the identification of influential and weak nodes in a power system.
Go to article

Authors and Affiliations

Isaiah Adebayo
1
Yanxia Sun
2

  1. Ladoke Akintola University of Technology, PMB 4000, Ogbomoso, Oyo State, Nigeria
  2. University of Johannesburg, P.O. BOX 524, Auckland Park 2006, South Africa

This page uses 'cookies'. Learn more