It is shown that such phenomena as quantum correlations (interaction of space-separated quantum entities), the action of magnetic vector potential on quantum entities in the absence of magnetic field, and near-field a...It is shown that such phenomena as quantum correlations (interaction of space-separated quantum entities), the action of magnetic vector potential on quantum entities in the absence of magnetic field, and near-field antenna effect (the existence of superluminally propagating electromagnetic fields) may be explained by action of spin supercurrents. In case of quantum correlations between quantum entities, spin supercurrent emerges between virtual particles pairs (virtual photons) created by those quantum entities. The explanation of magnetic vector potential and near-field antenna effect is based on contemporary principle of quantum mechanics: the physical vacuum is not an empty space but the ground state of the field consisting of quantum harmonic oscillators (QHOs) characterized by zero-point energy. Using the properties of the oscillators and spin supercurrent, it is proved that magnetic vector potential is proportional to the moment causing the orientation of spin of QHO along the direction of magnetic field. The near-field antenna effect is supposed to take place as a result of action of spin supercurrent causing secondary electromagnetic oscillations. In this way, the electromagnetic field may spread at the speed of spin supercurrent. As spin supercurrent is an inertia free process, its speed may be greater than that of light, which does not contradict postulates of special relativity that sets limits to the speed of inertial systems only.展开更多
The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler bec...The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler because of its high spectral efficiency. The higher the frequencies of the RF signal, the lower the distance it travels in free space caused by path loss, and it is more easily absorbed by obstacles, which are needed for high-gain transmitters. The advantage of the physical properties of higher New Radio (NR) frequencies is that 5G can utilize more spectrum, more antennas, and higher-order modulation schemes. The massive antennas and radio frequency chains improve the implementation of the cost of 5G wireless communication systems and result in an intense mutual coupling effect among antennas because of the limited space for deploying antennas. The upper bound of the effective capacity is derived for 5G multimedia massive MIMO communication systems. Two antennas that receive diversity gain models, the mutual coupling matrix, and the spacing antenna distance are built and analyzed. The impacts and affections of the antenna spacing the number of antennas, the quality-of-service (QoS) statistical exponent, and the number of independent incident directions on the upper effective capacity of 5G multimedia massive MIMO communication systems are analyzed. It is shown that for MIMO systems with compact transmit antenna arrays, the mutual coupling seriously degrades system capacity to mitigate the capacity degradation. In case of improvement in the mutual coupling by 99%, the system performance is kept stationary and enhances system capacity. However, the improvement of the mutual coupling is still about 87.5% today, which means the mutual coupling should be considered in 5G massive MIMO networks.展开更多
A novel host-vip luminous system with enhanced near-UV light absorption thereby enhanced luminescence are designed based on the synergism of quantum confinement,spatial confinement,and antenna effect,where ultrasmal...A novel host-vip luminous system with enhanced near-UV light absorption thereby enhanced luminescence are designed based on the synergism of quantum confinement,spatial confinement,and antenna effect,where ultrasmall Y_(2)O_(3):Eu^(3+)nanocrystals are fixed inside MOF(Eu/Y-BTC)as supporting structure.The Eu/Y-BTC not only limits the size and leads to lattice distortion of Y_(2)O_(3):Eu^(3+)nanocrystals and controls the distance between nanocrystals,but also promotes the light absorption and emission.The significantly red-shifted and broadened charge transfer band of Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)leads to the excellent applications of Y_(2)O_(3):Eu^(3+)in white light-emitting diodes(LEDs).Our results show that white light with superior color quality(CRI>90)and extremely high luminous efficacy(an LER of 335 lm/W)could be achieved using Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)as red phosphor.The Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)also improves the photoelectric performance of dye-sensitized solar cells(DSSCs),not only because Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)has a large specific surface area and the adsorption amount of the dye is increased,but also because the valence band position of Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)is 2.41 eV,which can provide an additional energy level between the TiO2 and dye,promoting electron transfer.For these advantageous features,the multifunctional Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)composite product will open new avenues in white LEDs and DSSCs.展开更多
Large reflector antennas are widely used in radars, satellite communication, radio astronomy, and so on. The rapid developments in these fields have created demands for development of better performance and higher sur...Large reflector antennas are widely used in radars, satellite communication, radio astronomy, and so on. The rapid developments in these fields have created demands for development of better performance and higher surface accuracy. However, low accuracy and low effi- ciency are the common disadvantages for traditional panel alignment and adjustment. In order to improve the surface accuracy of large reflector antenna, a new method is pre- sented to determinate panel adjustment values from far field pattern. Based on the method of Physical Optics （PO）, the effect of panel facet displacement on radiation field value is derived. Then the linear system is constructed between panel adjustment vector and far field pattern. Using the method of Singular Value Decomposition （SVD）, the adjustment value for all panel adjustors are obtained by solving the linear equations. An experiment is conducted on a 3.7 m reflector antenna with 12 segmented panels. The results of simulation and test are similar, which shows that the presented method is feasible. Moreover, thediscussion about validation shows that the method can be used for many cases of reflector shape. The proposed research provides the instruction to adjust surface panels efficiently and accurately.展开更多
Omnidirectional antennas are often used for radio frequency (RF) communication in wireless sensor networks (WSNs). Outside noise, electromagnetic interference (EMI), overloaded network traffic, large obstacles (vegeta...Omnidirectional antennas are often used for radio frequency (RF) communication in wireless sensor networks (WSNs). Outside noise, electromagnetic interference (EMI), overloaded network traffic, large obstacles (vegetation and buildings), terrain and atmospheric composition, along with climate patterns can degrade signal quality in the form of data packet loss or reduced RF communication range. This paper explores the RF range reduction properties of a particular WSN designed to operate in agricultural crop fields to collect aggregate data composed of subsurface soil moisture and soil temperature. Our study, using simulation, anechoic and field measurements shows that the effect of antenna placement close to the ground (within 10 cm) signi?cantly changes the omnidirectional transmission pattern. We then develop and propose a prediction method that is more precise than current practices of using the Friis and Fresnel equations. Our prediction method takes into account environmental properties for RF communication range based on the height of nodes and gateways.展开更多
Lanthanide coordination compounds of the formula Na[Ln(L)4](1 Ln),where Ln=La^3+,Eu^3+,Gd^3+,Tb^3+,L=[L]-and HL=dimethyl(4-methylphenylsulfo nyl)amidophosphate,were synthesized.Their structural and spectro scopic prop...Lanthanide coordination compounds of the formula Na[Ln(L)4](1 Ln),where Ln=La^3+,Eu^3+,Gd^3+,Tb^3+,L=[L]-and HL=dimethyl(4-methylphenylsulfo nyl)amidophosphate,were synthesized.Their structural and spectro scopic properties were discussed in detail based on X-ray diffraction measurements,IR spectroscopy,absorption and emission spectroscopy at 293 and 77 K and theoretical calculations of the intramolecular energy transfer(IET)rates.DFT calculations were used to investigate the 1 Ln electronic properties re quired to calculate the transition rates.30 and 22 pathways of intramolecular nonradiative energy transfer were examined in the case of 1 Eu and 1 Tb,respectively.It is shown that the main pathway for sensitization of the lanthanide emission is either the triplet(1 Eu)or singlet(1 Tb)transfer,occurring mainly through the exchange mechanism.The energy rates for energy transfer from S1 and T1 equal WS=1.53×10^5 s^-1(1 Eu),WT=5.14×10^6 s^-1(1 Eu)and WS=4.09×10^7 s^-1(1 Tb),WT=6.88×10^5 s^-1(1 Tb).The crucial role of the 7 F5 level in the energy transfer process of 1 Tb and the participation of the LMCT state in the depopulation of the ligand singlet state of 1 Eu were demonstrated.The influence of the resonance effect on the splitting of the7 F1 level in 1 Eu was analyzed.By comparing the properties of 1 Ln with the properties of 2 Ln coordination compounds,sharing the same ligand and crystallizing in the same crystallographic system(monoclinic),but with a different space group,it is demonstrated how slight structural changes can affect the photophysical properties of Ln compounds.展开更多
为研究当无线基站通信塔上避雷针遭受雷击时位于闪电通道附近天线的耦合效应,基于CST Studio Suite电磁仿真软件建立闪电通道-通信塔和工作在中国移动通信GSM1800/1900频段下的微带阵列天线的仿真模型。基于闪电回击电磁模型的继后回击...为研究当无线基站通信塔上避雷针遭受雷击时位于闪电通道附近天线的耦合效应,基于CST Studio Suite电磁仿真软件建立闪电通道-通信塔和工作在中国移动通信GSM1800/1900频段下的微带阵列天线的仿真模型。基于闪电回击电磁模型的继后回击过程,研究从天线极化方向讨论天线的雷击耦合特性以及天线单元连接由不同功分器构成的馈电网络进行组阵时阵列天线的雷击耦合特性。发现天线的耦合电压峰值与极化旋转角呈现线性关系,天线在垂直极化下的耦合电压比在水平极化下的耦合电压大得多;同时,对于通信塔上GSM频段的微带阵列天线,阵列天线的耦合电压受到馈电网络的影响,采用由威尔金森功分器构成的馈电网络进行组阵比采用由T型功分器构成的馈电网络进行组阵阵列天线的耦合电压更小。展开更多
文摘It is shown that such phenomena as quantum correlations (interaction of space-separated quantum entities), the action of magnetic vector potential on quantum entities in the absence of magnetic field, and near-field antenna effect (the existence of superluminally propagating electromagnetic fields) may be explained by action of spin supercurrents. In case of quantum correlations between quantum entities, spin supercurrent emerges between virtual particles pairs (virtual photons) created by those quantum entities. The explanation of magnetic vector potential and near-field antenna effect is based on contemporary principle of quantum mechanics: the physical vacuum is not an empty space but the ground state of the field consisting of quantum harmonic oscillators (QHOs) characterized by zero-point energy. Using the properties of the oscillators and spin supercurrent, it is proved that magnetic vector potential is proportional to the moment causing the orientation of spin of QHO along the direction of magnetic field. The near-field antenna effect is supposed to take place as a result of action of spin supercurrent causing secondary electromagnetic oscillations. In this way, the electromagnetic field may spread at the speed of spin supercurrent. As spin supercurrent is an inertia free process, its speed may be greater than that of light, which does not contradict postulates of special relativity that sets limits to the speed of inertial systems only.
文摘The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler because of its high spectral efficiency. The higher the frequencies of the RF signal, the lower the distance it travels in free space caused by path loss, and it is more easily absorbed by obstacles, which are needed for high-gain transmitters. The advantage of the physical properties of higher New Radio (NR) frequencies is that 5G can utilize more spectrum, more antennas, and higher-order modulation schemes. The massive antennas and radio frequency chains improve the implementation of the cost of 5G wireless communication systems and result in an intense mutual coupling effect among antennas because of the limited space for deploying antennas. The upper bound of the effective capacity is derived for 5G multimedia massive MIMO communication systems. Two antennas that receive diversity gain models, the mutual coupling matrix, and the spacing antenna distance are built and analyzed. The impacts and affections of the antenna spacing the number of antennas, the quality-of-service (QoS) statistical exponent, and the number of independent incident directions on the upper effective capacity of 5G multimedia massive MIMO communication systems are analyzed. It is shown that for MIMO systems with compact transmit antenna arrays, the mutual coupling seriously degrades system capacity to mitigate the capacity degradation. In case of improvement in the mutual coupling by 99%, the system performance is kept stationary and enhances system capacity. However, the improvement of the mutual coupling is still about 87.5% today, which means the mutual coupling should be considered in 5G massive MIMO networks.
基金This work was supported by the National Natural Science Foundation of China(No.21871079)the National Science Foundation(No.1945558).
文摘A novel host-vip luminous system with enhanced near-UV light absorption thereby enhanced luminescence are designed based on the synergism of quantum confinement,spatial confinement,and antenna effect,where ultrasmall Y_(2)O_(3):Eu^(3+)nanocrystals are fixed inside MOF(Eu/Y-BTC)as supporting structure.The Eu/Y-BTC not only limits the size and leads to lattice distortion of Y_(2)O_(3):Eu^(3+)nanocrystals and controls the distance between nanocrystals,but also promotes the light absorption and emission.The significantly red-shifted and broadened charge transfer band of Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)leads to the excellent applications of Y_(2)O_(3):Eu^(3+)in white light-emitting diodes(LEDs).Our results show that white light with superior color quality(CRI>90)and extremely high luminous efficacy(an LER of 335 lm/W)could be achieved using Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)as red phosphor.The Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)also improves the photoelectric performance of dye-sensitized solar cells(DSSCs),not only because Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)has a large specific surface area and the adsorption amount of the dye is increased,but also because the valence band position of Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)is 2.41 eV,which can provide an additional energy level between the TiO2 and dye,promoting electron transfer.For these advantageous features,the multifunctional Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)composite product will open new avenues in white LEDs and DSSCs.
基金Supported by National Natural Science Foundation of China(Grant Nos.51490661,51490660,51205301)National Key Basic Research Program of China(973 Program,Grant No.2015CB857100)Special Funding for Key Laboratory of Xinjiang Uygur Autonomous Region,China(Grant No.2014KL012)
文摘Large reflector antennas are widely used in radars, satellite communication, radio astronomy, and so on. The rapid developments in these fields have created demands for development of better performance and higher surface accuracy. However, low accuracy and low effi- ciency are the common disadvantages for traditional panel alignment and adjustment. In order to improve the surface accuracy of large reflector antenna, a new method is pre- sented to determinate panel adjustment values from far field pattern. Based on the method of Physical Optics （PO）, the effect of panel facet displacement on radiation field value is derived. Then the linear system is constructed between panel adjustment vector and far field pattern. Using the method of Singular Value Decomposition （SVD）, the adjustment value for all panel adjustors are obtained by solving the linear equations. An experiment is conducted on a 3.7 m reflector antenna with 12 segmented panels. The results of simulation and test are similar, which shows that the presented method is feasible. Moreover, thediscussion about validation shows that the method can be used for many cases of reflector shape. The proposed research provides the instruction to adjust surface panels efficiently and accurately.
文摘Omnidirectional antennas are often used for radio frequency (RF) communication in wireless sensor networks (WSNs). Outside noise, electromagnetic interference (EMI), overloaded network traffic, large obstacles (vegetation and buildings), terrain and atmospheric composition, along with climate patterns can degrade signal quality in the form of data packet loss or reduced RF communication range. This paper explores the RF range reduction properties of a particular WSN designed to operate in agricultural crop fields to collect aggregate data composed of subsurface soil moisture and soil temperature. Our study, using simulation, anechoic and field measurements shows that the effect of antenna placement close to the ground (within 10 cm) signi?cantly changes the omnidirectional transmission pattern. We then develop and propose a prediction method that is more precise than current practices of using the Friis and Fresnel equations. Our prediction method takes into account environmental properties for RF communication range based on the height of nodes and gateways.
基金Project supported by the Minister of Science and Higher Education POIG.01.01.02-02-006/09the grant Minister of Science and Higher Education for young scientists 2432/M/WCH/14+1 种基金partially developed within the scope of the project CICECO-Aveiro Institute of Materials,FCT(Portuguese agency)Ref.UID/CTM/50011/2019financed by national funds through the FCT/MCTES。
文摘Lanthanide coordination compounds of the formula Na[Ln(L)4](1 Ln),where Ln=La^3+,Eu^3+,Gd^3+,Tb^3+,L=[L]-and HL=dimethyl(4-methylphenylsulfo nyl)amidophosphate,were synthesized.Their structural and spectro scopic properties were discussed in detail based on X-ray diffraction measurements,IR spectroscopy,absorption and emission spectroscopy at 293 and 77 K and theoretical calculations of the intramolecular energy transfer(IET)rates.DFT calculations were used to investigate the 1 Ln electronic properties re quired to calculate the transition rates.30 and 22 pathways of intramolecular nonradiative energy transfer were examined in the case of 1 Eu and 1 Tb,respectively.It is shown that the main pathway for sensitization of the lanthanide emission is either the triplet(1 Eu)or singlet(1 Tb)transfer,occurring mainly through the exchange mechanism.The energy rates for energy transfer from S1 and T1 equal WS=1.53×10^5 s^-1(1 Eu),WT=5.14×10^6 s^-1(1 Eu)and WS=4.09×10^7 s^-1(1 Tb),WT=6.88×10^5 s^-1(1 Tb).The crucial role of the 7 F5 level in the energy transfer process of 1 Tb and the participation of the LMCT state in the depopulation of the ligand singlet state of 1 Eu were demonstrated.The influence of the resonance effect on the splitting of the7 F1 level in 1 Eu was analyzed.By comparing the properties of 1 Ln with the properties of 2 Ln coordination compounds,sharing the same ligand and crystallizing in the same crystallographic system(monoclinic),but with a different space group,it is demonstrated how slight structural changes can affect the photophysical properties of Ln compounds.
文摘为研究当无线基站通信塔上避雷针遭受雷击时位于闪电通道附近天线的耦合效应,基于CST Studio Suite电磁仿真软件建立闪电通道-通信塔和工作在中国移动通信GSM1800/1900频段下的微带阵列天线的仿真模型。基于闪电回击电磁模型的继后回击过程,研究从天线极化方向讨论天线的雷击耦合特性以及天线单元连接由不同功分器构成的馈电网络进行组阵时阵列天线的雷击耦合特性。发现天线的耦合电压峰值与极化旋转角呈现线性关系,天线在垂直极化下的耦合电压比在水平极化下的耦合电压大得多;同时,对于通信塔上GSM频段的微带阵列天线,阵列天线的耦合电压受到馈电网络的影响,采用由威尔金森功分器构成的馈电网络进行组阵比采用由T型功分器构成的馈电网络进行组阵阵列天线的耦合电压更小。
