A monolithic voltage controlled oscillator （VCO） based on negative resistance principle is presented uti-lizing commercially available InGaP/GaAs hetero-junction bipolar transistor （HBT） technology. This VCO is de...A monolithic voltage controlled oscillator （VCO） based on negative resistance principle is presented uti-lizing commercially available InGaP/GaAs hetero-junction bipolar transistor （HBT） technology. This VCO is de-signed for 5GHz-band wireless applications. Except for bypass and decoupled capacitors,no external component is needed for real application. Its measured output frequency range is from 4.17 to 4.56GHz,which is very close to the simulation one. And the phase noise at an offset frequency of 1MHz is -112dBc/Hz. The VCO core dissipates 15.5mW from a 3.3V supply,and the output power ranges from 0 to 2dBm. To compare with other oscillators,the figure of merit is calculated,which is about -173.2dBc/Hz. Meanwhile, the principle and design method of nega-tive resistance oscillator are also discussed.展开更多
An automated underground mine monitoring and communication system based on the integration of new technologies is introduced to promote safety and health,operational management and cost-effectiveness.The proposed syst...An automated underground mine monitoring and communication system based on the integration of new technologies is introduced to promote safety and health,operational management and cost-effectiveness.The proposed system integration considering Wireless Sensor Network(WSN) assisted Geographic Information System(GIS) enables to monitor and control underground mining applications from surface office.Based on the capabilities of WSNs,ZigBee network is adapted for near real-time monitoring,ventilation system control and emergency communication in underground mine.ZigBee nodes were developed to sense environmental attributes such as temperature,humidity and gases concentration;switching ON and OFF ventilation fans;and texting emergency messages.A trigger action plan for monitored attributes above normal and threshold value limits is programmed in the surface GIS management server.It is designed to turn the auxiliary fans on remotely or automatically in orange condition and sending evacuation messages for underground miners in unsafe(red) condition.Multi-users operation and 3D visualisations are other successful achievements of the proposed system for the underground monitoring and communication.展开更多
Let G = （V, E） be a connected graph. X belong to V（G） is a vertex set. X is a 3-restricted cut of G, if G- X is not connected and every component of G- X has at least three vertices. The 3-restricted connectivity ...Let G = （V, E） be a connected graph. X belong to V（G） is a vertex set. X is a 3-restricted cut of G, if G- X is not connected and every component of G- X has at least three vertices. The 3-restricted connectivity κ3（G） （in short κ3） of G is the cardinality of a minimum 3-restricted cut of G. X is called κ3-cut, if ｜X｜ = κ3. A graph G is κ3-connected, if a 3-restricted cut exists. Let G be a graph girth g ≥ 4, κ3（G） is min{d（x） ＋ d（y） ＋ d（z） - 4 ： xyz is a 2-path of G}. It will be shown that κ3（G） = ξ3（G） under the condition of girth.展开更多
文摘A monolithic voltage controlled oscillator （VCO） based on negative resistance principle is presented uti-lizing commercially available InGaP/GaAs hetero-junction bipolar transistor （HBT） technology. This VCO is de-signed for 5GHz-band wireless applications. Except for bypass and decoupled capacitors,no external component is needed for real application. Its measured output frequency range is from 4.17 to 4.56GHz,which is very close to the simulation one. And the phase noise at an offset frequency of 1MHz is -112dBc/Hz. The VCO core dissipates 15.5mW from a 3.3V supply,and the output power ranges from 0 to 2dBm. To compare with other oscillators,the figure of merit is calculated,which is about -173.2dBc/Hz. Meanwhile, the principle and design method of nega-tive resistance oscillator are also discussed.
文摘An automated underground mine monitoring and communication system based on the integration of new technologies is introduced to promote safety and health,operational management and cost-effectiveness.The proposed system integration considering Wireless Sensor Network(WSN) assisted Geographic Information System(GIS) enables to monitor and control underground mining applications from surface office.Based on the capabilities of WSNs,ZigBee network is adapted for near real-time monitoring,ventilation system control and emergency communication in underground mine.ZigBee nodes were developed to sense environmental attributes such as temperature,humidity and gases concentration;switching ON and OFF ventilation fans;and texting emergency messages.A trigger action plan for monitored attributes above normal and threshold value limits is programmed in the surface GIS management server.It is designed to turn the auxiliary fans on remotely or automatically in orange condition and sending evacuation messages for underground miners in unsafe(red) condition.Multi-users operation and 3D visualisations are other successful achievements of the proposed system for the underground monitoring and communication.
基金the National Natural Science Foundation of China (10671165)Specialized Research Fund for the Doctoral Program of Higher Education of China (20050755001)
文摘Let G = （V, E） be a connected graph. X belong to V（G） is a vertex set. X is a 3-restricted cut of G, if G- X is not connected and every component of G- X has at least three vertices. The 3-restricted connectivity κ3（G） （in short κ3） of G is the cardinality of a minimum 3-restricted cut of G. X is called κ3-cut, if ｜X｜ = κ3. A graph G is κ3-connected, if a 3-restricted cut exists. Let G be a graph girth g ≥ 4, κ3（G） is min{d（x） ＋ d（y） ＋ d（z） - 4 ： xyz is a 2-path of G}. It will be shown that κ3（G） = ξ3（G） under the condition of girth.
