The sensitivity and selectivity of gas sensors are related with not only sensing material,but also their operating temperatures.Applying this property,temperature modulation technique has been proposed to improve the ...The sensitivity and selectivity of gas sensors are related with not only sensing material,but also their operating temperatures.Applying this property,temperature modulation technique has been proposed to improve the selectivity of gas sensors.With a newly developed alumina based micro gas sensor,the sensitivity to CO and CH_4 at different operating temperatures was investigated.By modulating the temperature of the sensor at pulse and sine wave modes with different frequencies and amplitudes,the dynamic responses of the sensor were measured and processed.Results show that the modulating waveshape plays an important role in the improvement of selectivity,while the influence of frequency is small at the suitable sampling frequency in the range of 25 mHz～200 mHz.展开更多
The efficient transmission of images,which plays a large role inwireless communication systems,poses a significant challenge in the growth of multimedia technology.High-quality images require well-tuned communication ...The efficient transmission of images,which plays a large role inwireless communication systems,poses a significant challenge in the growth of multimedia technology.High-quality images require well-tuned communication standards.The Single Carrier Frequency Division Multiple Access(SC-FDMA)is adopted for broadband wireless communications,because of its low sensitivity to carrier frequency offsets and low Peak-to-Average Power Ratio(PAPR).Data transmission through open-channel networks requires much concentration on security,reliability,and integrity.The data need a space away fromunauthorized access,modification,or deletion.These requirements are to be fulfilled by digital image watermarking and encryption.This paper ismainly concerned with secure image communication over the wireless SC-FDMA systemas an adopted communication standard.It introduces a robust image communication framework over SC-FDMA that comprises digital image watermarking and encryption to improve image security,while maintaining a high-quality reconstruction of images at the receiver side.The proposed framework allows image watermarking based on the Discrete Cosine Transform(DCT)merged with the Singular Value Decomposition(SVD)in the so-called DCT-SVD watermarking.In addition,image encryption is implemented based on chaos and DNA encoding.The encrypted watermarked images are then transmitted through the wireless SC-FDMA system.The linearMinimumMean Square Error(MMSE)equalizer is investigated in this paper to mitigate the effect of channel fading and noise on the transmitted images.Two subcarrier mapping schemes,namely localized and interleaved schemes,are compared in this paper.The study depends on different channelmodels,namely PedestrianAandVehicularA,with a modulation technique namedQuadratureAmplitude Modulation(QAM).Extensive simulation experiments are conducted and introduced in this paper for efficient transmission of encrypted watermarked images.In addition,different variants of SC-FDMA based on the Discrete Wavelet Transform(DWT),Discrete Cosine Transform(DCT),and Fast Fourier Transform(FFT)are considered and compared for the image communication task.The simulation results and comparison demonstrate clearly that DWT-SC-FDMAis better suited to the transmission of the digital images in the case of PedestrianAchannels,while the DCT-SC-FDMA is better suited to the transmission of the digital images in the case of Vehicular A channels.展开更多
Digital Communications, in relation to wireless networks, have taken off in recent years due to the expanding need to communicate faster and more efficiently. A popular way to achieve this is by using wireless Multipl...Digital Communications, in relation to wireless networks, have taken off in recent years due to the expanding need to communicate faster and more efficiently. A popular way to achieve this is by using wireless Multiple Input Multiple Output (MIMO) communication systems. MIMO systems utilize Space Time Block Codes (STBC) as one of the leading ways to obtain higher data rates with limited bandwidth and power. With several STBC methods currently available, this paper analyzes simulations using Orthogonal Space Time Block Codes (OSTBC) in Rayleigh fading channels to evaluate the performance of MIMO systems. The selection to use a Rayleigh fading channel as a model for a non-line-of-sight (nLOS) environment is selected to mimic installations where a large number of signal paths and reflections are expected. All simulations are coded, generated and plotted using MATLAB resulting in graphical data representing the bit-error rate (BER) to signal-to-noise ratio (Eb/N<sub>0</sub>) or SNR. Each simulation captures how different configurations of key variables including code rate, diversity and antenna count can impact system performance. Four modulation schemes (BPSK, QPSK, 16-QAM and 64-QAM) are included in each simulation. Conclusive evidence based upon these simulations suggests higher diversity gains were achieved with a greater number of antennas. The most significant factor for increasing system performance was using a lower count of transmit antennas with a higher count of receive antennas.展开更多
To improve the precision of inertial navigation system（INS） during long time operation,the rotation modulated technique（RMT） was employed to modulate the errorr of the inertial sensors into periodically varied sig...To improve the precision of inertial navigation system（INS） during long time operation,the rotation modulated technique（RMT） was employed to modulate the errorr of the inertial sensors into periodically varied signals,and,as a result,to suppress the divergence of INS errors.The principle of the RMT was introduced and the error propagating functions were derived from the rotary navigation equation.Effects of the measurement error for the rotation angle of the platform on the system precision were analyzed.The simulation and experimental results show that the precision of INS was ① dramatically improved with the use of the RMT,and ② hardly reduced when the measurement error for the rotation angle was in arc-second level.The study results offer a theoretical basis for engineering design of rotary INS.展开更多
A two-step methodology was used to address and improve the power quality concerns for the PV-integrated microgrid system. First, partial shading was included to deal with the real-time issues. The Improved Jelly Fish ...A two-step methodology was used to address and improve the power quality concerns for the PV-integrated microgrid system. First, partial shading was included to deal with the real-time issues. The Improved Jelly Fish Algorithm integrated Perturb and Obserb (IJFA-PO) has been proposed to track the Global Maximum Power Point (GMPP). Second, the main unit-powered via DC–AC converter is synchronised with the grid. To cope with the wide voltage variation and harmonic mitigation, an auxiliary unit undergoes a novel series compensation technique. Out of various switching approaches, IJFA-based Selective Harmonic Elimination (SHE) in 120° conduction gives the optimal solution. Three switching angles were obtained using IJFA, whose performance was equivalent to that of nine switching angles. Thus, the system is efficient with minimised higher-order harmonics and lower switching losses. The proposed system outperformed in terms of efficiency, metaheuristics, and convergence. The Total Harmonic Distortion (THD) obtained was 1.32%, which is within the IEEE 1547 and IEC tolerable limits. The model was developed in MATLAB/Simulink 2016b and verified with an experimental prototype of grid-synchronised PV capacity of 260 W tested under various loading conditions. The present model is reliable and features a simple controller that provides more convenient and adequate performance.展开更多
This paper provides a comprehensive review of the principles of magnetic and optical control in thermal atomic spin ensembles,as well as recent advances and applications in quantum precision measurement.As a practical...This paper provides a comprehensive review of the principles of magnetic and optical control in thermal atomic spin ensembles,as well as recent advances and applications in quantum precision measurement.As a practical macroscopic quantum system,thermal atomic spin ensembles have emerged as a key platform for next-generation quantum sensors due to their exceptional sensitivity,accuracy,and scalability.The review emphasizes how magneto-optical modulation techniques can be employed to extract real-time information about spin dynamics and system states,thereby generating high-quality observables that serve as the foundation for advanced control strategies such as feedback regulation,quantum state estimation,and pulsed manipulation.These techniques are shown to play a crucial role in enhancing measurement sensitivity,dynamic response and long-term stability.In addition,the incorporation of modern control theories,including closed-loop feedback and Kalman filter,has facilitated real-time optimization of atomic spin dynamics,unlocking new levels of sensitivity across a range of applications such as atomic magnetometers,co-magnetometers,inertial sensors,and microwave masers.This paper systematically discusses the synergistic interplay of modulation,measurement,and control in thermal spin ensembles,exploring its potential across a wide range of scientific and engineering applications.These technological advances provide a solid foundation for ultra-sensitive magnetic field detection and show promising prospects in frontier fields such as dark matter detection and gravitational wave observation.Looking ahead,such innovations are expected to further drive the miniaturization and integration of quantum sensors,significantly expanding their utility across disciplines.展开更多
With the rapid development and widespread applications of power electronic converters,strong fault-tolerant capability of power electronic converters is required since they play important roles in power systems.In thi...With the rapid development and widespread applications of power electronic converters,strong fault-tolerant capability of power electronic converters is required since they play important roles in power systems.In this paper,a review of one of the most promising fault-tolerant topologies for semiconductor open-circuit fault,called four-switch three-phase(FSTP)topology,is presented in terms of modeling analysis,modulation techniques,and control strategies.The configuration of FSTP voltage source converter(VSC)is illustrated.To minimize the negative effects caused by the innate drawbacks of this fault-tolerant converter topology,considerable research has been carried out regarding modulation techniques and control strategies.The modulation principle for FSTP topology is explained in detail,since the performance of FSTP VSCs relies on it.This paper aims to illustrate current research progress on this fault-tolerant FSTP VSC topology.展开更多
文摘The sensitivity and selectivity of gas sensors are related with not only sensing material,but also their operating temperatures.Applying this property,temperature modulation technique has been proposed to improve the selectivity of gas sensors.With a newly developed alumina based micro gas sensor,the sensitivity to CO and CH_4 at different operating temperatures was investigated.By modulating the temperature of the sensor at pulse and sine wave modes with different frequencies and amplitudes,the dynamic responses of the sensor were measured and processed.Results show that the modulating waveshape plays an important role in the improvement of selectivity,while the influence of frequency is small at the suitable sampling frequency in the range of 25 mHz～200 mHz.
基金the Deanship of Scientific Research,Princess Nourah bint Abdulrahman University,through the Program of Research Project Funding After Publication,Grant No.(44-PRFA-P-131).
文摘The efficient transmission of images,which plays a large role inwireless communication systems,poses a significant challenge in the growth of multimedia technology.High-quality images require well-tuned communication standards.The Single Carrier Frequency Division Multiple Access(SC-FDMA)is adopted for broadband wireless communications,because of its low sensitivity to carrier frequency offsets and low Peak-to-Average Power Ratio(PAPR).Data transmission through open-channel networks requires much concentration on security,reliability,and integrity.The data need a space away fromunauthorized access,modification,or deletion.These requirements are to be fulfilled by digital image watermarking and encryption.This paper ismainly concerned with secure image communication over the wireless SC-FDMA systemas an adopted communication standard.It introduces a robust image communication framework over SC-FDMA that comprises digital image watermarking and encryption to improve image security,while maintaining a high-quality reconstruction of images at the receiver side.The proposed framework allows image watermarking based on the Discrete Cosine Transform(DCT)merged with the Singular Value Decomposition(SVD)in the so-called DCT-SVD watermarking.In addition,image encryption is implemented based on chaos and DNA encoding.The encrypted watermarked images are then transmitted through the wireless SC-FDMA system.The linearMinimumMean Square Error(MMSE)equalizer is investigated in this paper to mitigate the effect of channel fading and noise on the transmitted images.Two subcarrier mapping schemes,namely localized and interleaved schemes,are compared in this paper.The study depends on different channelmodels,namely PedestrianAandVehicularA,with a modulation technique namedQuadratureAmplitude Modulation(QAM).Extensive simulation experiments are conducted and introduced in this paper for efficient transmission of encrypted watermarked images.In addition,different variants of SC-FDMA based on the Discrete Wavelet Transform(DWT),Discrete Cosine Transform(DCT),and Fast Fourier Transform(FFT)are considered and compared for the image communication task.The simulation results and comparison demonstrate clearly that DWT-SC-FDMAis better suited to the transmission of the digital images in the case of PedestrianAchannels,while the DCT-SC-FDMA is better suited to the transmission of the digital images in the case of Vehicular A channels.
文摘Digital Communications, in relation to wireless networks, have taken off in recent years due to the expanding need to communicate faster and more efficiently. A popular way to achieve this is by using wireless Multiple Input Multiple Output (MIMO) communication systems. MIMO systems utilize Space Time Block Codes (STBC) as one of the leading ways to obtain higher data rates with limited bandwidth and power. With several STBC methods currently available, this paper analyzes simulations using Orthogonal Space Time Block Codes (OSTBC) in Rayleigh fading channels to evaluate the performance of MIMO systems. The selection to use a Rayleigh fading channel as a model for a non-line-of-sight (nLOS) environment is selected to mimic installations where a large number of signal paths and reflections are expected. All simulations are coded, generated and plotted using MATLAB resulting in graphical data representing the bit-error rate (BER) to signal-to-noise ratio (Eb/N<sub>0</sub>) or SNR. Each simulation captures how different configurations of key variables including code rate, diversity and antenna count can impact system performance. Four modulation schemes (BPSK, QPSK, 16-QAM and 64-QAM) are included in each simulation. Conclusive evidence based upon these simulations suggests higher diversity gains were achieved with a greater number of antennas. The most significant factor for increasing system performance was using a lower count of transmit antennas with a higher count of receive antennas.
基金Sponsored by the National Natural Science Foundation of China(60604011)
文摘To improve the precision of inertial navigation system（INS） during long time operation,the rotation modulated technique（RMT） was employed to modulate the errorr of the inertial sensors into periodically varied signals,and,as a result,to suppress the divergence of INS errors.The principle of the RMT was introduced and the error propagating functions were derived from the rotary navigation equation.Effects of the measurement error for the rotation angle of the platform on the system precision were analyzed.The simulation and experimental results show that the precision of INS was ① dramatically improved with the use of the RMT,and ② hardly reduced when the measurement error for the rotation angle was in arc-second level.The study results offer a theoretical basis for engineering design of rotary INS.
文摘A two-step methodology was used to address and improve the power quality concerns for the PV-integrated microgrid system. First, partial shading was included to deal with the real-time issues. The Improved Jelly Fish Algorithm integrated Perturb and Obserb (IJFA-PO) has been proposed to track the Global Maximum Power Point (GMPP). Second, the main unit-powered via DC–AC converter is synchronised with the grid. To cope with the wide voltage variation and harmonic mitigation, an auxiliary unit undergoes a novel series compensation technique. Out of various switching approaches, IJFA-based Selective Harmonic Elimination (SHE) in 120° conduction gives the optimal solution. Three switching angles were obtained using IJFA, whose performance was equivalent to that of nine switching angles. Thus, the system is efficient with minimised higher-order harmonics and lower switching losses. The proposed system outperformed in terms of efficiency, metaheuristics, and convergence. The Total Harmonic Distortion (THD) obtained was 1.32%, which is within the IEEE 1547 and IEC tolerable limits. The model was developed in MATLAB/Simulink 2016b and verified with an experimental prototype of grid-synchronised PV capacity of 260 W tested under various loading conditions. The present model is reliable and features a simple controller that provides more convenient and adequate performance.
基金supported by the National Natural Science Foundation of China(Grant No.62103026)the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0300400,and 2021ZD0300402)+1 种基金the China National Funds for Distinguished Young Scientists(Grant No.61925301)the Fundamental Research Funds for the Central Universities。
文摘This paper provides a comprehensive review of the principles of magnetic and optical control in thermal atomic spin ensembles,as well as recent advances and applications in quantum precision measurement.As a practical macroscopic quantum system,thermal atomic spin ensembles have emerged as a key platform for next-generation quantum sensors due to their exceptional sensitivity,accuracy,and scalability.The review emphasizes how magneto-optical modulation techniques can be employed to extract real-time information about spin dynamics and system states,thereby generating high-quality observables that serve as the foundation for advanced control strategies such as feedback regulation,quantum state estimation,and pulsed manipulation.These techniques are shown to play a crucial role in enhancing measurement sensitivity,dynamic response and long-term stability.In addition,the incorporation of modern control theories,including closed-loop feedback and Kalman filter,has facilitated real-time optimization of atomic spin dynamics,unlocking new levels of sensitivity across a range of applications such as atomic magnetometers,co-magnetometers,inertial sensors,and microwave masers.This paper systematically discusses the synergistic interplay of modulation,measurement,and control in thermal spin ensembles,exploring its potential across a wide range of scientific and engineering applications.These technological advances provide a solid foundation for ultra-sensitive magnetic field detection and show promising prospects in frontier fields such as dark matter detection and gravitational wave observation.Looking ahead,such innovations are expected to further drive the miniaturization and integration of quantum sensors,significantly expanding their utility across disciplines.
文摘With the rapid development and widespread applications of power electronic converters,strong fault-tolerant capability of power electronic converters is required since they play important roles in power systems.In this paper,a review of one of the most promising fault-tolerant topologies for semiconductor open-circuit fault,called four-switch three-phase(FSTP)topology,is presented in terms of modeling analysis,modulation techniques,and control strategies.The configuration of FSTP voltage source converter(VSC)is illustrated.To minimize the negative effects caused by the innate drawbacks of this fault-tolerant converter topology,considerable research has been carried out regarding modulation techniques and control strategies.The modulation principle for FSTP topology is explained in detail,since the performance of FSTP VSCs relies on it.This paper aims to illustrate current research progress on this fault-tolerant FSTP VSC topology.
