A compact antenna formed by three concentric split rings for ultra-high frequency(UHF)radio frequency identification(RFID)tag is proposed in this paper.The antenna is composed of two parts,an outer short-circuited rin...A compact antenna formed by three concentric split rings for ultra-high frequency(UHF)radio frequency identification(RFID)tag is proposed in this paper.The antenna is composed of two parts,an outer short-circuited ring modified from a traditional split-ring resonator(SRR)antenna and an inner SRR load,so the antenna can be regarded as a short-circuited ring loaded with SRR.According to the transmission line theory,to conjugate match with the capacitive input-impedance of a tag chip,the length of the short-circuited ring isλg/4 shorter than that of an open-circuited dipole of a traditional SRR antenna,whereλg is the wavelengh of the operating frequency.Hence,the size of the proposed antenna is more compact than that of the traditional SRR antenna.Thereafter,the proposed antenna is simulated and optimized by ANSYS high-frequency structure simulator(HFSS).The impedance,efficiency,and mutual coupling of the fabricated antenna are tested in a reverberation chamber(RC).The results show that the size of the presented antenna is 83%smaller than that of the traditional SRR antenna and the proposed antenna can cover the whole UHF RFID operating frequency band worldwide(840—960 MHz).The measured read range of the tag exhibits maximum values of 45 cm in free space and 37 cm under dense tag environment.展开更多
Age-specific fertility rate and total fertility rate of females are the most important parame- ters in population dynamics. This paper proposes an algorithm to get these parameters from the initial age distribution an...Age-specific fertility rate and total fertility rate of females are the most important parame- ters in population dynamics. This paper proposes an algorithm to get these parameters from the initial age distribution and the total population the years followed. The idea is natural in the sense that the total population is easily to be obtained in a closed society. The authors use a discrete population model to formulate this problem into an inverse problem, which is ill-posed generally. A necessary and sufficient condition for the identifiability is established. An algorithm for reconstruction of age-specific fertility rate is developed.展开更多
文摘A compact antenna formed by three concentric split rings for ultra-high frequency(UHF)radio frequency identification(RFID)tag is proposed in this paper.The antenna is composed of two parts,an outer short-circuited ring modified from a traditional split-ring resonator(SRR)antenna and an inner SRR load,so the antenna can be regarded as a short-circuited ring loaded with SRR.According to the transmission line theory,to conjugate match with the capacitive input-impedance of a tag chip,the length of the short-circuited ring isλg/4 shorter than that of an open-circuited dipole of a traditional SRR antenna,whereλg is the wavelengh of the operating frequency.Hence,the size of the proposed antenna is more compact than that of the traditional SRR antenna.Thereafter,the proposed antenna is simulated and optimized by ANSYS high-frequency structure simulator(HFSS).The impedance,efficiency,and mutual coupling of the fabricated antenna are tested in a reverberation chamber(RC).The results show that the size of the presented antenna is 83%smaller than that of the traditional SRR antenna and the proposed antenna can cover the whole UHF RFID operating frequency band worldwide(840—960 MHz).The measured read range of the tag exhibits maximum values of 45 cm in free space and 37 cm under dense tag environment.
基金supported by the National Natural Science Foundation of Chinathe National Research Foundation of South Africa
文摘Age-specific fertility rate and total fertility rate of females are the most important parame- ters in population dynamics. This paper proposes an algorithm to get these parameters from the initial age distribution and the total population the years followed. The idea is natural in the sense that the total population is easily to be obtained in a closed society. The authors use a discrete population model to formulate this problem into an inverse problem, which is ill-posed generally. A necessary and sufficient condition for the identifiability is established. An algorithm for reconstruction of age-specific fertility rate is developed.
