The high reliability of the communication system is critical in metro and mining applications for personal safety,channel optimization,and improving operational performance.This paper surveys the progress of wireless ...The high reliability of the communication system is critical in metro and mining applications for personal safety,channel optimization,and improving operational performance.This paper surveys the progress of wireless communication systems in underground environments such as tunnels and mines from 1920 to 2022,including the evolution of primitive technology,advancements in channel modelling,and realization of various wireless propagation channels.In addition,the existing and advanced channel modeling strategies,which include the evolution of different technologies and their applications;mathematical,analytical,and experimental techniques for radio propagation;and significance of the radiation characteristics,antenna placement,and physical environment of multiple-input multiple-output(MIMO)communication systems,are analyzed.The given study introduces leaky coaxial cable(LCX)and distributed antenna system(DAS)designs for improving narrowband and wideband channel capacity.The paper concludes by figuring out open research areas for the future technologies.展开更多
Coronary cameral fistula (CCF) is a very rare coronary anomaly in which a communication exists between one of the coronaries and a cardiac chamber. Most of the times it is an incidental finding detected at the time of...Coronary cameral fistula (CCF) is a very rare coronary anomaly in which a communication exists between one of the coronaries and a cardiac chamber. Most of the times it is an incidental finding detected at the time of a coronary angiography. However, sometimes it can have serious presentation like unstable angina, coronary steal or ventricular arrhythmia. We present a rare case of coronary cameral fistula arising from left circumflex artery (LCx) draining in to left ventricular (LV) apex and presenting as unstable angina.展开更多
文摘The high reliability of the communication system is critical in metro and mining applications for personal safety,channel optimization,and improving operational performance.This paper surveys the progress of wireless communication systems in underground environments such as tunnels and mines from 1920 to 2022,including the evolution of primitive technology,advancements in channel modelling,and realization of various wireless propagation channels.In addition,the existing and advanced channel modeling strategies,which include the evolution of different technologies and their applications;mathematical,analytical,and experimental techniques for radio propagation;and significance of the radiation characteristics,antenna placement,and physical environment of multiple-input multiple-output(MIMO)communication systems,are analyzed.The given study introduces leaky coaxial cable(LCX)and distributed antenna system(DAS)designs for improving narrowband and wideband channel capacity.The paper concludes by figuring out open research areas for the future technologies.
文摘Coronary cameral fistula (CCF) is a very rare coronary anomaly in which a communication exists between one of the coronaries and a cardiac chamber. Most of the times it is an incidental finding detected at the time of a coronary angiography. However, sometimes it can have serious presentation like unstable angina, coronary steal or ventricular arrhythmia. We present a rare case of coronary cameral fistula arising from left circumflex artery (LCx) draining in to left ventricular (LV) apex and presenting as unstable angina.
