The reduction of TE-scattering by a conducting cylinder with multiple surface impedance loads is investigated. Synthesis procedures are developed to find the optimal loading which result in zero scattering in the desi...The reduction of TE-scattering by a conducting cylinder with multiple surface impedance loads is investigated. Synthesis procedures are developed to find the optimal loading which result in zero scattering in the desired directions or at several frequencies. Numerical results of these procedures are presented. The theoretical predictions are confirmed with an experiment. The proposed synthesis procedure is completely general and can be applied to arbitrarily shaped conducting bodies.展开更多
Transmission expansion planning(TEP)addresses the intricate task of optimizing new transmission infrastructure within an existing grid to meet system objectives.As a critical strategy in power system development,TEP s...Transmission expansion planning(TEP)addresses the intricate task of optimizing new transmission infrastructure within an existing grid to meet system objectives.As a critical strategy in power system development,TEP significantly influences the long-term efficiency,reliability,and scalability of the network,with enduring effects on overall system performance.This paper explores the application of unconventional high surge impedance loading(HSIL)lines as a cost-effective alternative to conventional extra high-voltage(EHV)transmission lines.By optimizing the geometry of subconductors,HSIL designs could achieve higher power delivery capacities while operating at reduced voltage levels,addressing the increased demand for sustainable energy infrastructure.Two 500 kV HSIL line configurations are analyzed for their feasibility in replacing the conventional 765 kV transmission lines for the TEP to integrate the large-scale wind energy sources located in far remote areas.The analysis is carried out within the 23-bus EHV test system.This study reveals that both HSIL line configurations successfully meet the technical constraints of the TEP problem,ensuring reliable system operation even under contingency conditions.Therefore,the HSIL lines offer significant cost savings due to infrastructure and accessories at reduced voltage levels with much smaller right of way(ROW)than conventional counterparts.This underscores the potential of unconventional HSIL lines to contribute to more sustainable and cost-effective grid planning strategies for integrating large-scale renewable energy sources.展开更多
Power line is an efficient media for home area networking communication scenarios. However, it is not designed to transmit data. This causes several perturbations phenomenon for communications technologies over the po...Power line is an efficient media for home area networking communication scenarios. However, it is not designed to transmit data. This causes several perturbations phenomenon for communications technologies over the power cables. This work presents an investigation of the indoor narrowband power lines channel behavior. The load, the transmission line length and the network topology impact are studied using a simple network. A channel response measure campaign has been realized in 13 sites. The channel capacity has been used for channel classification. The measures were classified into 5 classes. It is shown that channel response is mainly impacted by the load impedance. The class distributions are more impacted by the nature of appliances connected into the indoor network.展开更多
The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic sources.However,the existing calculation methods suffer from outliers caused by the zero-crossing of the denominat...The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic sources.However,the existing calculation methods suffer from outliers caused by the zero-crossing of the denominator.These outliers can result in inaccuracy and unreliability of harmonic source location.To address this issue,this paper proposes an innovative method of equivalent impedance parameter calculation of three-phase symmetrical loads that avoid outliers.The correctness and effectiveness of the proposed method are verified by simulations on Simulink using actual monitoring data.The results show that the proposed method is not only simple and easy to implement but also highly accurate.展开更多
A general 2-D problem of electromagnetic scattering from a multiple cavity-backed longitudinally loaded slotted perfectly conducting cylinder with arbitrary cross section is formulated. The formulation is used to acco...A general 2-D problem of electromagnetic scattering from a multiple cavity-backed longitudinally loaded slotted perfectly conducting cylinder with arbitrary cross section is formulated. The formulation is used to account for the scattered field from the scale models, for which, a series of experiments has been conducted in an anechoic chamber. Quite good agreement between theory and experiment is obtained. The analysis of the experimental results near resonant frequency shows that the reduction of backscattering radar cross section over wide aspect angles, and the dominant enhancement of target angular glint (linear deviation) can be achieved by impedance loading such as multiple cavity-backed slots, which realizes a new stealth technique for vehicles.展开更多
In the upgrade project of Hefei Light Source（HLSⅡ）,a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively.We design a...In the upgrade project of Hefei Light Source（HLSⅡ）,a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively.We design a new waveguide overloaded cavity longitudinal feedback kicker as the feedback actuator.The beam pipe of the kicker is a racetrack shape so as to avoid a transition part to the octagonal vacuum chamber.The central frequency and the bandwidth of the kicker have been simulated and optimized to achieve design goals by the HFSS code.A higher shunt impedance can be obtained by using a nose cone to reduce the feedback power requirement.Before the kicker cavity was installed in the storage ring,a variety of measurements were carried out to check its performance.All these results of simulation and measurement are presented.展开更多
This paper reports a wideband passive mixer for direct conversion multi-standard receivers.A brief comparison between current-commutating passive mixers and active mixers is presented.The effect of source and load imp...This paper reports a wideband passive mixer for direct conversion multi-standard receivers.A brief comparison between current-commutating passive mixers and active mixers is presented.The effect of source and load impedance on the linearity of a mixer is analyzed.Specially,the impact of the input impedance of the transimpedance amplifier（TIA）,which acts as the load impedance of a mixer,is investigated in detail.The analysis is verified by a passive mixer implemented with 0.18 μm CMOS technology.The circuit is inductorless and can operate over a broad frequency range.On wafer measurements show that,with radio frequency（RF） ranges from 700 MHz to 2.3 GHz,the mixer achieves 21 dB of conversion voltage gain with a-1 dB intermediate frequency（IF） bandwidth of 10 MHz.The measured IIP3 is 9 dBm and the measured double-sideband noise figure（NF） is 10.6 dB at 10 MHz output.The chip occupies an area of 0.19 mm2 and drains a current of 5.5 mA from a 1.8 V supply.展开更多
An integrated low-phase-noise voltage-controlled oscillator （VCO） has been designed and fabricated in SMIC 0.18 μm RF CMOS technology. The circuit employs an optimally designed LC resonator and a differential cross...An integrated low-phase-noise voltage-controlled oscillator （VCO） has been designed and fabricated in SMIC 0.18 μm RF CMOS technology. The circuit employs an optimally designed LC resonator and a differential cross-coupling amplifier acts as a negative resistor to compensate the energy loss of the resonator. To extend the frequency tuning range, a three-bit binary-weighted switched capacitor array is used in the circuit. The testing result indicates that the VCO achieves a tuning range of 60% from 1.92 to 3.35 GHz. The phase noise of the VCO is -117.8 dBc/Hz at 1 MHz offset from the carrier frequency of 2.4 GHz. It draws 5.6 mA current from a 1.8 V supply. The VCO integrated circuit occupies a die area of 600 × 900 μm^2. It can be used in the IEEE802.1 lb based wireless local network receiver.展开更多
DC I-V output,small signal and an extensive large signal characterization（load-pull measurements） of a GaN HEMT on a SiC substrate with different gate widths of 100μm and 1 mm have been carried out.From the small s...DC I-V output,small signal and an extensive large signal characterization（load-pull measurements） of a GaN HEMT on a SiC substrate with different gate widths of 100μm and 1 mm have been carried out.From the small signal data,it has been found that the cutoff frequencies increase with gate width varying from 100μm to 1 mm,owing to the reduced contribution of the parasitic effect.The devices investigated with different gate widths are enough to work in the C band and X band.The large signal measurements include the load-pull measurements and power sweep measurements at the C band（5.5 GHz） and X band（8 GHz）.When biasing the gate voltage in class AB and selecting the source impedance,the optimum load impedances seen from the device for output power and PAE were localized in the load-pull map.The results of a power sweep at an 8 GHz biased various drain voltage demonstrate that a GaN HEMT on a SiC substrate has good thermal conductivity and a high breakdown voltage,and the CW power density of 10.16 W/mm was obtained.From the results of the power sweep measurement at 5.5 GHz with different gate widths, the actual scaling rules and heat effect on the large periphery device were analyzed,although the effects are not serious. The measurement results and analyses prove that a GaN HEMT on a SiC substrate is an ideal candidate for high-power amplifier design.展开更多
文摘The reduction of TE-scattering by a conducting cylinder with multiple surface impedance loads is investigated. Synthesis procedures are developed to find the optimal loading which result in zero scattering in the desired directions or at several frequencies. Numerical results of these procedures are presented. The theoretical predictions are confirmed with an experiment. The proposed synthesis procedure is completely general and can be applied to arbitrarily shaped conducting bodies.
基金supported by the National Science Foundation(NSF)(No.2306098)。
文摘Transmission expansion planning(TEP)addresses the intricate task of optimizing new transmission infrastructure within an existing grid to meet system objectives.As a critical strategy in power system development,TEP significantly influences the long-term efficiency,reliability,and scalability of the network,with enduring effects on overall system performance.This paper explores the application of unconventional high surge impedance loading(HSIL)lines as a cost-effective alternative to conventional extra high-voltage(EHV)transmission lines.By optimizing the geometry of subconductors,HSIL designs could achieve higher power delivery capacities while operating at reduced voltage levels,addressing the increased demand for sustainable energy infrastructure.Two 500 kV HSIL line configurations are analyzed for their feasibility in replacing the conventional 765 kV transmission lines for the TEP to integrate the large-scale wind energy sources located in far remote areas.The analysis is carried out within the 23-bus EHV test system.This study reveals that both HSIL line configurations successfully meet the technical constraints of the TEP problem,ensuring reliable system operation even under contingency conditions.Therefore,the HSIL lines offer significant cost savings due to infrastructure and accessories at reduced voltage levels with much smaller right of way(ROW)than conventional counterparts.This underscores the potential of unconventional HSIL lines to contribute to more sustainable and cost-effective grid planning strategies for integrating large-scale renewable energy sources.
文摘Power line is an efficient media for home area networking communication scenarios. However, it is not designed to transmit data. This causes several perturbations phenomenon for communications technologies over the power cables. This work presents an investigation of the indoor narrowband power lines channel behavior. The load, the transmission line length and the network topology impact are studied using a simple network. A channel response measure campaign has been realized in 13 sites. The channel capacity has been used for channel classification. The measures were classified into 5 classes. It is shown that channel response is mainly impacted by the load impedance. The class distributions are more impacted by the nature of appliances connected into the indoor network.
基金supported by the National Natural Science Foundation of China(No.51777035).
文摘The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic sources.However,the existing calculation methods suffer from outliers caused by the zero-crossing of the denominator.These outliers can result in inaccuracy and unreliability of harmonic source location.To address this issue,this paper proposes an innovative method of equivalent impedance parameter calculation of three-phase symmetrical loads that avoid outliers.The correctness and effectiveness of the proposed method are verified by simulations on Simulink using actual monitoring data.The results show that the proposed method is not only simple and easy to implement but also highly accurate.
文摘A general 2-D problem of electromagnetic scattering from a multiple cavity-backed longitudinally loaded slotted perfectly conducting cylinder with arbitrary cross section is formulated. The formulation is used to account for the scattered field from the scale models, for which, a series of experiments has been conducted in an anechoic chamber. Quite good agreement between theory and experiment is obtained. The analysis of the experimental results near resonant frequency shows that the reduction of backscattering radar cross section over wide aspect angles, and the dominant enhancement of target angular glint (linear deviation) can be achieved by impedance loading such as multiple cavity-backed slots, which realizes a new stealth technique for vehicles.
基金Supported by Natural Science Foundation of China(11175173,11005105)
文摘In the upgrade project of Hefei Light Source（HLSⅡ）,a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively.We design a new waveguide overloaded cavity longitudinal feedback kicker as the feedback actuator.The beam pipe of the kicker is a racetrack shape so as to avoid a transition part to the octagonal vacuum chamber.The central frequency and the bandwidth of the kicker have been simulated and optimized to achieve design goals by the HFSS code.A higher shunt impedance can be obtained by using a nose cone to reduce the feedback power requirement.Before the kicker cavity was installed in the storage ring,a variety of measurements were carried out to check its performance.All these results of simulation and measurement are presented.
基金Project supported by the National Science and Technology Major Project (No.2010ZX03007-002-01)the State Key Development Program for Basic Research of China (No.2010CB327404)
文摘This paper reports a wideband passive mixer for direct conversion multi-standard receivers.A brief comparison between current-commutating passive mixers and active mixers is presented.The effect of source and load impedance on the linearity of a mixer is analyzed.Specially,the impact of the input impedance of the transimpedance amplifier（TIA）,which acts as the load impedance of a mixer,is investigated in detail.The analysis is verified by a passive mixer implemented with 0.18 μm CMOS technology.The circuit is inductorless and can operate over a broad frequency range.On wafer measurements show that,with radio frequency（RF） ranges from 700 MHz to 2.3 GHz,the mixer achieves 21 dB of conversion voltage gain with a-1 dB intermediate frequency（IF） bandwidth of 10 MHz.The measured IIP3 is 9 dBm and the measured double-sideband noise figure（NF） is 10.6 dB at 10 MHz output.The chip occupies an area of 0.19 mm2 and drains a current of 5.5 mA from a 1.8 V supply.
基金supported by the Scientific and Technologic Cooperation Foundation of the Yangtxe River Delta Area of China(No.2008C16017)
文摘An integrated low-phase-noise voltage-controlled oscillator （VCO） has been designed and fabricated in SMIC 0.18 μm RF CMOS technology. The circuit employs an optimally designed LC resonator and a differential cross-coupling amplifier acts as a negative resistor to compensate the energy loss of the resonator. To extend the frequency tuning range, a three-bit binary-weighted switched capacitor array is used in the circuit. The testing result indicates that the VCO achieves a tuning range of 60% from 1.92 to 3.35 GHz. The phase noise of the VCO is -117.8 dBc/Hz at 1 MHz offset from the carrier frequency of 2.4 GHz. It draws 5.6 mA current from a 1.8 V supply. The VCO integrated circuit occupies a die area of 600 × 900 μm^2. It can be used in the IEEE802.1 lb based wireless local network receiver.
基金Project supported by the Major Program and State Key Program of the National Natural Science Foundation of China(No.60736033)
文摘DC I-V output,small signal and an extensive large signal characterization（load-pull measurements） of a GaN HEMT on a SiC substrate with different gate widths of 100μm and 1 mm have been carried out.From the small signal data,it has been found that the cutoff frequencies increase with gate width varying from 100μm to 1 mm,owing to the reduced contribution of the parasitic effect.The devices investigated with different gate widths are enough to work in the C band and X band.The large signal measurements include the load-pull measurements and power sweep measurements at the C band（5.5 GHz） and X band（8 GHz）.When biasing the gate voltage in class AB and selecting the source impedance,the optimum load impedances seen from the device for output power and PAE were localized in the load-pull map.The results of a power sweep at an 8 GHz biased various drain voltage demonstrate that a GaN HEMT on a SiC substrate has good thermal conductivity and a high breakdown voltage,and the CW power density of 10.16 W/mm was obtained.From the results of the power sweep measurement at 5.5 GHz with different gate widths, the actual scaling rules and heat effect on the large periphery device were analyzed,although the effects are not serious. The measurement results and analyses prove that a GaN HEMT on a SiC substrate is an ideal candidate for high-power amplifier design.
