Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these...Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.展开更多
Passive intermodulation（PIM） has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh...Passive intermodulation（PIM） has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal（MM） contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.展开更多
In this review,the advanced microwave devices based on the integrated passive device(IPD)technology are expounded and discussed in detail,involving the performance breakthroughs and circuit innovations.Then,the develo...In this review,the advanced microwave devices based on the integrated passive device(IPD)technology are expounded and discussed in detail,involving the performance breakthroughs and circuit innovations.Then,the development trend of IPD-based multifunctional microwave circuits is predicted further by analyzing the current research hot spots.This paper discusses a distinctive research area for microwave circuits and mobile-terminal radio-frequency integrated chips.展开更多
Organic-inorganic hybrid metal halide perovskite solar cells(PSCs)have attracted much attention due to their high photoelectric conversion efficiency(PCE)and low cost.The certificated PCE of small active area(below 0....Organic-inorganic hybrid metal halide perovskite solar cells(PSCs)have attracted much attention due to their high photoelectric conversion efficiency(PCE)and low cost.The certificated PCE of small active area(below 0.1 cm^(2))device has reached 26.7%[1].However,when considering the scaled-up commercialization of PSCs,an obvious efficiency drop exists for the translation to large-area perovskite submodules(PSMs)with areas more than 200 cm^(2),thus limiting the practical commercialization[2].The major PCE gap between small area cells and large area modules arises the drop of open-circuit voltage(VOC)and fill factor(FF).Formamidinium lead iodide(FAPbI_(3))is now the mostly widely used and highly efficient perovskite composition.However,the photo-active black α-FAPbI_(3) phase will spontaneously transform into photo-inactive yellowδ-FAPbI_(3) phase at room temperature[3].展开更多
This paper presents a novel impedance matching approach for passive UHF RFID transponder ICs,which are compatible with the ISO/IEC 18000-6B standard and operate in the 915MHz ISM band. The passive UHF RFID transponder...This paper presents a novel impedance matching approach for passive UHF RFID transponder ICs,which are compatible with the ISO/IEC 18000-6B standard and operate in the 915MHz ISM band. The passive UHF RFID transponder with complex impedances is powered by received RF energy. The approach uses the parasitic inductance of the antenna to implement ASK modulation by adjusting the capacitive reactance of the matching network, which changes with the backscatter circuit. The impedance matching achieves maximum power transfer between the reader, antenna, and transponder. The transponder IC,whose operating distance is more than 4m with the impedance matching approach,is fabricated using a Chartered 0.35μm two-poly four-metal CMOS process that supports Schottky diodes and EEPROM.展开更多
A behavior model for the receiver of the Ethernet passive optical network（EPON） is presented. The model consists of a fiber, a photodetector, a transimpedance amplifier （TIA） followed by a limiting amplifier and a...A behavior model for the receiver of the Ethernet passive optical network（EPON） is presented. The model consists of a fiber, a photodetector, a transimpedance amplifier （TIA） followed by a limiting amplifier and a clock and data recovery＇ circuit （CDR）. Each sub-model is constructed based on the architecture of a circuit. The noise and jitter in each block such as shot noise, thermal noise, deterministic and random jitter are also considered. The performance of the whole receiver can be evaluated by the simulation of the behavior model, which is faster than the ordinary circuit model and more accurate than the analytical model. The whole model is implemented with C ＋＋ and simulated in Microsoft Visual C ＋＋ 6. 0. Using the Monte Carlo method, the EPON receiver is simulated. The simulation results show a good agreement with experimental ones.展开更多
In this article,a new type current transformer was developed using an active-passive circuit to improve low frequency response of the system without impairing high frequency response.The active-passive current transfo...In this article,a new type current transformer was developed using an active-passive circuit to improve low frequency response of the system without impairing high frequency response.The active-passive current transformer with In-flange was fabricated.Theoretical analysis,numerical simulations and experimental results are given.展开更多
It is well known that [6,6]-phenyl-C<sub><span style="font-size:12px;font-family:Verdana;">61</span></sub><span style="font-size:12px;font-family:Verdana;">-butyric ac...It is well known that [6,6]-phenyl-C<sub><span style="font-size:12px;font-family:Verdana;">61</span></sub><span style="font-size:12px;font-family:Verdana;">-butyric acid methyl ester (PCBM) is a common n-type passivation material in PSCs, usually used as an interface modification layer. However, PCBM is extremely expensive and is not suitable for future industrialization. Herein, the various concentrations of PCBM as an additive are adopted for PSCs. It not only avoids the routine process of spin coating the multi-layer films, but also reduces the PCBM material and cost. Meanwhile, PCBM can passivate the grain surface and modulate morphology of perovskite films. Furthermore, the most important optical parameters of solar cells, the current density (</span><i><span style="font-size:12px;font-family:Verdana;">J</span><sub><span style="font-size:12px;font-family:Verdana;">sc</span></sub></i><span style="font-size:12px;font-family:Verdana;">), fill factor (FF), open-circuit voltage (</span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;">) and power conversion efficiencies (PCE) were improved. Especially, when the PCBM doping ratio in CH</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">NH</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">PbI</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;"> (MAPbI</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">) precursor solution was 1</span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "=""><span style="font-size:12px;font-family:Verdana;">wt%, the device obtained the smallest </span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;"> decay (less than 1%) in the p-i-n type PSCs with poly</span></span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "=""><span style="font-size:12px;font-family:Verdana;">(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) as hole transport layer (HTL) and fullerene (C</span><sub><span style="font-size:12px;font-family:Verdana;">60</span></sub><span style="font-size:12px;font-family:Verdana;">) as electron transport layer (ETL). The PSCs </span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;"> stability improvement is attri</span><span style="font-size:12px;font-family:Verdana;">buted to enhanced crystallinity of photoactive layer and decreased non-radiative </span><span style="font-size:12px;font-family:Verdana;">recombination by PCBM doping in the perovskites.</span></span></span></span>展开更多
Stainless steel(SS)is one of the most widely used engineering materials in marine engineering.However,its corrosion in the marine atmospheric environment due to the high concentration of Cl-is a problem.The SS corrosi...Stainless steel(SS)is one of the most widely used engineering materials in marine engineering.However,its corrosion in the marine atmospheric environment due to the high concentration of Cl-is a problem.The SS corrosion is a threat to the development and security of marine industry;therefore,evaluating the corrosion resistance of SSs is necessary.In this work,atmospheric corrosion detection probes based on a symmetrical electrode system were used to study the corrosion behaviors of 304 SS and 2205 duplex stainless steel(DSS)in a simulated marine atmosphere.A theoretical model for electrochemical noise(EN)data analysis based on the Thevenin electrochemical equivalent circuit(EEC)model was established.The relationship between the EN characteristic parameters and the corrosion rate was obtained.The Thevenin EEC model analysis showed that the relationship between the noise resistance(Rn),the noise impedance[Rsn(f)],and the impedance modulus(|Z(f)|)was Rn≈Rsn=■.Thus,Rn and Rsn can be used as indicators for quantitative corrosion evaluation.The results of EN detection for the 304 SS and 2205 DSS showed that in a simulated marine atmospheric environment,the passive fi lms on the two SSs were relatively intact at the initial exposure stage,and their dissolution rates were slow.The corrosion resistance of the 2205 DSS was higher than that of the 304 SS.With the deposition of Cl-on the SS surface,pitting was initiated and the dissolution rate increased.The pitting initiation process on the SS surface was random,and part of the active pores could be repassivated.展开更多
In order to utilize integrated passive technology in printed circuit boards （PCBs）, manufacturing processing for integrated resistors by lamination method was investigated. Integrated resistors fabricated from Ohmeg...In order to utilize integrated passive technology in printed circuit boards （PCBs）, manufacturing processing for integrated resistors by lamination method was investigated. Integrated resistors fabricated from Ohmega technologies in the experiment were 1 408 pieces per panel with four different patterns A, B, C and D and four resistance values of 25, 50, 75 and 100 fL Six panel per batch and four batches were performed totally. The testing was done for 960 pieces of integrated resistors randomly selected with the same size. The value distribution ranges and the relative standard deviation （RSD） show that the scatter degree of the resistance decreases with the resistor size increasing and/or with the resistance increasing. Patterns D with resistance of 75 and 100% for four patterns have the resistance value variances less than 10%. Patterns C and D with resistance of 100 Ω have the manufacturing tolerance less than 10%. The process capabilities are from about 0.6 to 1.6 for the designed testing patterns, which shows that the integrated resistors fabricated have the potential to be used in multilayer PCBs in the future.展开更多
This paper presents an analysis and validation by advanced system simulation of compact and low-cost six-port transceivers for future wireless local area networks （WLANs） operating at millimeter-wave frequencies. To...This paper presents an analysis and validation by advanced system simulation of compact and low-cost six-port transceivers for future wireless local area networks （WLANs） operating at millimeter-wave frequencies. To obtain realistic simulation results, a six-port model based on the measurement results of a fabricated V-band hybrid coupler, the core component, is used. A frequency-division multiplexing scheme is used by introducing four quadrature phase-shift keying （QPSK） channels in the wireless communication link. The data rate achieved is about 4 Gbit/s. The operating frequency is in the 60-64 GHz unlicensed band. Bit error rate （BER） results are presented, and a comparison is made between single-carrier and multicarrier architectures. The proposed wireless system can be considered an efficient candidate for millimeter-wave communication systems operating at quasi-optical data rates.展开更多
基金supported by the Fundamental Research Funds for Central Public Welfare Research Institute,No.2020CZ-5(to WS and GS)the National Natural Science Foundation of China,No.31970970(to JSR)Fundamental Research Funds for the Central Universities,No.YWF-23-YG-QB-010(to JSR)。
文摘Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.
文摘Passive intermodulation（PIM） has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal（MM） contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.
基金Beijing Natural Science Foundation(No.JQ19018)National Natural Science Foundations of China(No.U20A20203 and No.61971052)National Special Support Program for High-Level Personnel Recruitment(No.2018RA2131)。
文摘In this review,the advanced microwave devices based on the integrated passive device(IPD)technology are expounded and discussed in detail,involving the performance breakthroughs and circuit innovations.Then,the development trend of IPD-based multifunctional microwave circuits is predicted further by analyzing the current research hot spots.This paper discusses a distinctive research area for microwave circuits and mobile-terminal radio-frequency integrated chips.
基金support from open fund of Fujian Provincial Key Laboratory of Functional Materials and Applications(Xiamen University of Technology,fma2024003)the National Key R&D Program of China(No.2021YFB3500400)the National Natural Science Foundation of China(Nos.52073286 and 22275185).
文摘Organic-inorganic hybrid metal halide perovskite solar cells(PSCs)have attracted much attention due to their high photoelectric conversion efficiency(PCE)and low cost.The certificated PCE of small active area(below 0.1 cm^(2))device has reached 26.7%[1].However,when considering the scaled-up commercialization of PSCs,an obvious efficiency drop exists for the translation to large-area perovskite submodules(PSMs)with areas more than 200 cm^(2),thus limiting the practical commercialization[2].The major PCE gap between small area cells and large area modules arises the drop of open-circuit voltage(VOC)and fill factor(FF).Formamidinium lead iodide(FAPbI_(3))is now the mostly widely used and highly efficient perovskite composition.However,the photo-active black α-FAPbI_(3) phase will spontaneously transform into photo-inactive yellowδ-FAPbI_(3) phase at room temperature[3].
文摘This paper presents a novel impedance matching approach for passive UHF RFID transponder ICs,which are compatible with the ISO/IEC 18000-6B standard and operate in the 915MHz ISM band. The passive UHF RFID transponder with complex impedances is powered by received RF energy. The approach uses the parasitic inductance of the antenna to implement ASK modulation by adjusting the capacitive reactance of the matching network, which changes with the backscatter circuit. The impedance matching achieves maximum power transfer between the reader, antenna, and transponder. The transponder IC,whose operating distance is more than 4m with the impedance matching approach,is fabricated using a Chartered 0.35μm two-poly four-metal CMOS process that supports Schottky diodes and EEPROM.
文摘A behavior model for the receiver of the Ethernet passive optical network（EPON） is presented. The model consists of a fiber, a photodetector, a transimpedance amplifier （TIA） followed by a limiting amplifier and a clock and data recovery＇ circuit （CDR）. Each sub-model is constructed based on the architecture of a circuit. The noise and jitter in each block such as shot noise, thermal noise, deterministic and random jitter are also considered. The performance of the whole receiver can be evaluated by the simulation of the behavior model, which is faster than the ordinary circuit model and more accurate than the analytical model. The whole model is implemented with C ＋＋ and simulated in Microsoft Visual C ＋＋ 6. 0. Using the Monte Carlo method, the EPON receiver is simulated. The simulation results show a good agreement with experimental ones.
文摘In this article,a new type current transformer was developed using an active-passive circuit to improve low frequency response of the system without impairing high frequency response.The active-passive current transformer with In-flange was fabricated.Theoretical analysis,numerical simulations and experimental results are given.
文摘It is well known that [6,6]-phenyl-C<sub><span style="font-size:12px;font-family:Verdana;">61</span></sub><span style="font-size:12px;font-family:Verdana;">-butyric acid methyl ester (PCBM) is a common n-type passivation material in PSCs, usually used as an interface modification layer. However, PCBM is extremely expensive and is not suitable for future industrialization. Herein, the various concentrations of PCBM as an additive are adopted for PSCs. It not only avoids the routine process of spin coating the multi-layer films, but also reduces the PCBM material and cost. Meanwhile, PCBM can passivate the grain surface and modulate morphology of perovskite films. Furthermore, the most important optical parameters of solar cells, the current density (</span><i><span style="font-size:12px;font-family:Verdana;">J</span><sub><span style="font-size:12px;font-family:Verdana;">sc</span></sub></i><span style="font-size:12px;font-family:Verdana;">), fill factor (FF), open-circuit voltage (</span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;">) and power conversion efficiencies (PCE) were improved. Especially, when the PCBM doping ratio in CH</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">NH</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">PbI</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;"> (MAPbI</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">) precursor solution was 1</span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "=""><span style="font-size:12px;font-family:Verdana;">wt%, the device obtained the smallest </span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;"> decay (less than 1%) in the p-i-n type PSCs with poly</span></span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "=""><span style="font-size:12px;font-family:Verdana;">(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) as hole transport layer (HTL) and fullerene (C</span><sub><span style="font-size:12px;font-family:Verdana;">60</span></sub><span style="font-size:12px;font-family:Verdana;">) as electron transport layer (ETL). The PSCs </span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;"> stability improvement is attri</span><span style="font-size:12px;font-family:Verdana;">buted to enhanced crystallinity of photoactive layer and decreased non-radiative </span><span style="font-size:12px;font-family:Verdana;">recombination by PCBM doping in the perovskites.</span></span></span></span>
基金the National Natural Science Foundation of China(No.51701140)。
文摘Stainless steel(SS)is one of the most widely used engineering materials in marine engineering.However,its corrosion in the marine atmospheric environment due to the high concentration of Cl-is a problem.The SS corrosion is a threat to the development and security of marine industry;therefore,evaluating the corrosion resistance of SSs is necessary.In this work,atmospheric corrosion detection probes based on a symmetrical electrode system were used to study the corrosion behaviors of 304 SS and 2205 duplex stainless steel(DSS)in a simulated marine atmosphere.A theoretical model for electrochemical noise(EN)data analysis based on the Thevenin electrochemical equivalent circuit(EEC)model was established.The relationship between the EN characteristic parameters and the corrosion rate was obtained.The Thevenin EEC model analysis showed that the relationship between the noise resistance(Rn),the noise impedance[Rsn(f)],and the impedance modulus(|Z(f)|)was Rn≈Rsn=■.Thus,Rn and Rsn can be used as indicators for quantitative corrosion evaluation.The results of EN detection for the 304 SS and 2205 DSS showed that in a simulated marine atmospheric environment,the passive fi lms on the two SSs were relatively intact at the initial exposure stage,and their dissolution rates were slow.The corrosion resistance of the 2205 DSS was higher than that of the 304 SS.With the deposition of Cl-on the SS surface,pitting was initiated and the dissolution rate increased.The pitting initiation process on the SS surface was random,and part of the active pores could be repassivated.
基金Project(041010) supported by Start-Up Foundation of Northwest University,ChinaProject(UIT/39) supported by University-Industry Collaboration Program from the Innovation and Technology Fund of Hong Kong,China
文摘In order to utilize integrated passive technology in printed circuit boards （PCBs）, manufacturing processing for integrated resistors by lamination method was investigated. Integrated resistors fabricated from Ohmega technologies in the experiment were 1 408 pieces per panel with four different patterns A, B, C and D and four resistance values of 25, 50, 75 and 100 fL Six panel per batch and four batches were performed totally. The testing was done for 960 pieces of integrated resistors randomly selected with the same size. The value distribution ranges and the relative standard deviation （RSD） show that the scatter degree of the resistance decreases with the resistor size increasing and/or with the resistance increasing. Patterns D with resistance of 75 and 100% for four patterns have the resistance value variances less than 10%. Patterns C and D with resistance of 100 Ω have the manufacturing tolerance less than 10%. The process capabilities are from about 0.6 to 1.6 for the designed testing patterns, which shows that the integrated resistors fabricated have the potential to be used in multilayer PCBs in the future.
文摘This paper presents an analysis and validation by advanced system simulation of compact and low-cost six-port transceivers for future wireless local area networks （WLANs） operating at millimeter-wave frequencies. To obtain realistic simulation results, a six-port model based on the measurement results of a fabricated V-band hybrid coupler, the core component, is used. A frequency-division multiplexing scheme is used by introducing four quadrature phase-shift keying （QPSK） channels in the wireless communication link. The data rate achieved is about 4 Gbit/s. The operating frequency is in the 60-64 GHz unlicensed band. Bit error rate （BER） results are presented, and a comparison is made between single-carrier and multicarrier architectures. The proposed wireless system can be considered an efficient candidate for millimeter-wave communication systems operating at quasi-optical data rates.
