In recent years,there has been a significant acceleration in the thinning,calving and retreat of the Pine Island Ice Shelf(PIIS).The basal channels,results of enhanced basal melting,have the potential to significantly...In recent years,there has been a significant acceleration in the thinning,calving and retreat of the Pine Island Ice Shelf(PIIS).The basal channels,results of enhanced basal melting,have the potential to significantly impact the stability of the PIIS.In this study,we used a variety of remote sensing data,including Landsat,REMA DEM,ICESat-1 and ICESat-2 satellite altimetry observations,and Ice Bridge airborne measurements,to study the spatiotemporal changes in the basal channels from 2003 to 2020 and basal melt rate from 2010 to 2017 of the PIIS under the Eulerian framework.We found that the basal channels are highly developed in the PIIS,with a total length exceeding 450 km.Most of the basal channels are ocean-sourced or groundingline-sourced basal channels,caused by the rapid melting under the ice shelf or near the groundingline.A raised seabed prevented warm water intrusion into the eastern branch of the PIIS,resulting in a lower basal melt rate in that area.In contrast,a deepsea trough facilitates warm seawater into the mainstream and the western branch of the PIIS,resulting in a higher basal melt rate in the main-stream,and the surface elevation changes above the basal channels of the mainstream and western branch are more significant.The El Ni?o event in 2015–2016 possibly slowed down the basal melting of the PIIS by modulating wind field,surface sea temperature and depth seawater temperature.Ocean and atmospheric changes were driven by El Ni?o,which can further explain and confirm the changes in the basal melting of the PIIS.展开更多
The rapid development of the digital economy has provided a new impetus for rural residents to extend their working hours.Based on the data collected by the China Labor-force Dynamics Survey(CLDS)in 2014,2016,and 2018...The rapid development of the digital economy has provided a new impetus for rural residents to extend their working hours.Based on the data collected by the China Labor-force Dynamics Survey(CLDS)in 2014,2016,and 2018,this paper measured the development level of the digital economy in China from the perspectives of internet development and digital financial inclusion,and tested the mechanisms of how the digital economy affected rural residents’working hours.The results showed that the digital economy extended rural residents’working hours by expanding information channels and enhancing human capital,and this mechanism was affected by heterogeneity in rural residents’educational background,age,and social capital.Building on these findings,this paper holds that to increase rural residents’income by extending their working hours and achieving common prosperity for all,it is necessary to expand the opportunities for rural residents to participate in skills training and promote their accumulation of human capital.展开更多
An emerging railway technology called smart railway promises to deliver higher transportation efficiency,enhanced comfort in services,and greater eco-friendliness.The smart railway is expected to integrate fifth-gener...An emerging railway technology called smart railway promises to deliver higher transportation efficiency,enhanced comfort in services,and greater eco-friendliness.The smart railway is expected to integrate fifth-generation mobile communication(5G),Artificial Intelligence(AI),and other technologies,which poses new problems in the construction,operation and maintenance of railway wireless networks.Wireless Digital Twins(DTs),which have recently emerged as a new paradigm for the design of wireless networks,can address these problems and enable the whole lifecycle management of railway wireless networks.However,there are still many scientific issues and challenges for railway-oriented wireless DT.Relevant key technologies to solve these problems are introduced and described,including characterization of materials'physical-EM properties,autonomous reconstruction of Three-dimensional(3D)environment model,AI-empowered environmental cognition,Ray-Tracing(RT),model-based and AIbased RT acceleration,and generation of multi-spectra sensing data.Moreover,this paper presents our research results for each key technology and describes the wireless network planning and optimization system based on highperformance RT developed by our laboratory.This paper outlines the framework for realizing the wireless DT of smart railways,providing the direction for future research.展开更多
Integration of digital twin(DT)and wireless channel provides new solution of channel modeling and simulation,and can assist to design,optimize and evaluate intelligent wireless communication system and networks.With D...Integration of digital twin(DT)and wireless channel provides new solution of channel modeling and simulation,and can assist to design,optimize and evaluate intelligent wireless communication system and networks.With DT channel modeling,the generated channel data can be closer to realistic channel measurements without requiring a prior channel model,and amount of channel data can be significantly increased.Artificial intelligence(AI)based modeling approach shows outstanding performance to solve such problems.In this work,a channel modeling method based on generative adversarial networks is proposed for DT channel,which can generate identical statistical distribution with measured channel.Model validation is conducted by comparing DT channel characteristics with measurements,and results show that DT channel leads to fairly good agreement with measured channel.Finally,a link-layer simulation is implemented based on DT channel.It is found that the proposed DT channel model can be well used to conduct link-layer simulation and its performance is comparable to using measurement data.The observations and results can facilitate the development of DT channel modeling and provide new thoughts for DT channel applications,as well as improving the performance and reliability of intelligent communication networking.展开更多
The novel closed-form expressions for the average channel capacity of dual selection diversity is presented, as well as, the bit-error rate (BER) of several coherent and noncoherent digital modulation schemes in the...The novel closed-form expressions for the average channel capacity of dual selection diversity is presented, as well as, the bit-error rate (BER) of several coherent and noncoherent digital modulation schemes in the correlated Weibull fading channels with nonidentical statisticS. The results are expressed in terms of Meijer's Gfunction, which can be easily evaluated numerically. The simulation results are presented to validate the proposed theoretical analysis and to examine the effects of the fading severity on the concerned quantities.展开更多
Objective To investigate the changing regularity of thoracic pedicle screw channel (PSC) in different transverse screw angle(TSA).Methods CT scan images of thoracic vertebrae of a healthy adult ware digitally analyzed...Objective To investigate the changing regularity of thoracic pedicle screw channel (PSC) in different transverse screw angle(TSA).Methods CT scan images of thoracic vertebrae of a healthy adult ware digitally analyzed by Mimics 10.01展开更多
An approach is proposed to realize a digital channelized receiver in the fractional Fourier domain (FRFD) for signal intercept applications. The presented architecture can be considered as a generalization of that i...An approach is proposed to realize a digital channelized receiver in the fractional Fourier domain (FRFD) for signal intercept applications. The presented architecture can be considered as a generalization of that in the traditional Fourier domain. Since the linear frequency modulation (LFM) signal has a good energy concentration in the FRFD, by choosing an appropriate fractional Fourier transform (FRFT) order, the presented architecture can concentrate the broadband LFM signal into only one sub-channel and that will prevent it from crossing several sub-channels. Thus the performance of the signal detection and parameter estimation after the sub-channel output will be improved significantly. The computational complexity is reduced enormously due to the implementation of the polyphase filter bank decomposition, thus the proposed architecture can be realized as efficiently as in the Fourier domain. The related simulation results are presented to verify the validity of the theories and methods involved in this paper.展开更多
The basal channel is a detailed morphological feature of the ice shelf caused by uneven basal melting.This kind of specifically morphology is widely distributed in polar ice shelves.It is an important research object ...The basal channel is a detailed morphological feature of the ice shelf caused by uneven basal melting.This kind of specifically morphology is widely distributed in polar ice shelves.It is an important research object of sea-ice interaction and plays a vital role in studying the relationship between the ice sheet/ice shelf and global warming.In this paper,high-resolution remote sensing image and ice penetration data were combined to extract the basal channel of the Pine Island Ice Shelf.The depth variation of Pine Island Ice Shelf in the recent 20 years was analyzed and discussed by using ICESat-1,ICESat-2,and IceBridge data.Combined with relevant marine meteorological elements(sea surface temperature,surface melting days,circumpolar deep water and wind)to analyze the basal channel changes,the redistribution of ocean heat is considered to be the most important factor affecting the evolution and development of the basal channel.展开更多
A novel efficient partial sharing channelization structure with odd and even stacking is designed and implemented. There are two special designs in the proposed structure. Firstly, by the intensive channel overlap des...A novel efficient partial sharing channelization structure with odd and even stacking is designed and implemented. There are two special designs in the proposed structure. Firstly, by the intensive channel overlap design, for non-cooperative wideband signals, the proposed structure can achieve good parameter estimation accuracy and high probability of complete interception.Secondly, based on the partial sharing design developed in this paper, the computation burden of the proposed structure can be greatly reduced compared with the traditional directly implemented structures. Experiments and numerical simulations are conducted to evaluate the proposed structure, which shows its improvements over traditional methods in terms of field programmable gate arrays(FPGA) resource consumption and parameter estimation accuracy.展开更多
In the context of the digital economy, agricultural product marketing has also undergone new development, and the models of agricultural product marketing are constantly innovating. Based on the current sales situatio...In the context of the digital economy, agricultural product marketing has also undergone new development, and the models of agricultural product marketing are constantly innovating. Based on the current sales situation of Tashan Pomegranate, this paper analyzed the existing sales channels of Tashan Pomegranate. It found that Tashan Pomegranate currently has insufficient online marketing channels, incomplete logistics system, and a lack of comprehensive talents in online marketing. In response to the existing problems, constructive recommendations are proposed for the online marketing channels of agricultural products in Lieshan District, and a network marketing path suitable for Tashan Pomegranate in Lieshan District was explored.展开更多
For digital channelized frequency division multiple access based satellite communication(SATCOM) systems,it is a challenging but critical issue to improve the transponder power and spectrum efficiency simultaneously u...For digital channelized frequency division multiple access based satellite communication(SATCOM) systems,it is a challenging but critical issue to improve the transponder power and spectrum efficiency simultaneously under limited and non-linear high-power amplifier conditions.In this paper,different from the traditional link supportability designs aiming at minimizing the total transponder output power,a maximal sum Shannon capacity optimization objective is firstly raised subject to link supportability constraints.Furthermore,an efficient multilevel optimization(MO) algorithm is proposed to solve the considered optimization problem in the case of single link for each terminal.Moreover,in the case of multiple links for one terminal,an improved MO algorithm involving Golden section and discrete gradient searching procedures is proposed to optimize power allocation over all links.Finally,several numerical results are provided to demonstrate the effectiveness of our proposals.Comparison results show that,by the MO algorithm,not only all links' supportability can be guaranteed but also a larger sum capacity can be achieved with lower complexity.展开更多
The absolute delay caused by equipment of radio navigation satellite service (RNSS) signal channel must be calibrated in the application of positioning. The measurement accuracy of absolute delay will affect the posit...The absolute delay caused by equipment of radio navigation satellite service (RNSS) signal channel must be calibrated in the application of positioning. The measurement accuracy of absolute delay will affect the positioning precision of RNSS user. An absolute delay measurement technique using digital envelope detection was developed for RNSS signal transmission channel. The RNSS transmission signal of navigation satellite and the one pulse per second (1PPS)generated by satellite time keeping system were sampled synchronously. With sampling data of 1PPS,the reference point of the absolute delay can be decided at first,and then sampling data of RNSS transmission signal were truncated. The truncated data were processed using digital envelop detection algorithm to search the phase converting points of RNSS signal. Finally,the absolute delay of RNSS signal transmitting channel was calculated. Uncertainty of measurement with proposed technique is lower than 0. 2 ns as the sampling frequency is 10 GHz.展开更多
Formany years,researchers have explored power allocation(PA)algorithms driven bymodels in wireless networks where multiple-user communications with interference are present.Nowadays,data-driven machine learning method...Formany years,researchers have explored power allocation(PA)algorithms driven bymodels in wireless networks where multiple-user communications with interference are present.Nowadays,data-driven machine learning methods have become quite popular in analyzing wireless communication systems,which among them deep reinforcement learning(DRL)has a significant role in solving optimization issues under certain constraints.To this purpose,in this paper,we investigate the PA problem in a k-user multiple access channels(MAC),where k transmitters(e.g.,mobile users)aim to send an independent message to a common receiver(e.g.,base station)through wireless channels.To this end,we first train the deep Q network(DQN)with a deep Q learning(DQL)algorithm over the simulation environment,utilizing offline learning.Then,the DQN will be used with the real data in the online training method for the PA issue by maximizing the sumrate subjected to the source power.Finally,the simulation results indicate that our proposedDQNmethod provides better performance in terms of the sumrate compared with the available DQL training approaches such as fractional programming(FP)and weighted minimum mean squared error(WMMSE).Additionally,by considering different user densities,we show that our proposed DQN outperforms benchmark algorithms,thereby,a good generalization ability is verified over wireless multi-user communication systems.展开更多
This paper develops an efficient pseudo-random number generator for validation of digital communication channels and secure disc. Drives. Simulation results validates the effectiveness of the random number generator.
Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were...Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, ischemic preconditioning was induced by left anterior descending occlusion (three, 5 min episodes separated by 5 min of reperfusion), ischemia-reperfusion injury was induced by 30 min coronary artery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size and scores of ventricular arrhythmias were measured. The expression of Gαq/11 protein in the heart was measured by Western blot analysis in the second series. Results Ischemic preconditioning rats showed decreased infarct size and scores of ventricular arrhythmia vs non-IP control rats. The effect of IPC was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective KATP channel inhibitor. IPC caused a significant increase in the expression of Gαq/11 protein. Conclusions Activations of Gαq/11 signal pathway and KATP channel played significant roles in the classical cardioprotection of ischemic precon-ditioning rat heart and might be an important mechanism of signal transduction pathway during the ischemic preconditioning.展开更多
Zero Crossing Digital Phase Locked Loop with Arc Sine block (AS-ZCDPLL) is used to linearize the phase difference detection, and enhance the loop performance. The loop has faster acquisition, less steady state phase e...Zero Crossing Digital Phase Locked Loop with Arc Sine block (AS-ZCDPLL) is used to linearize the phase difference detection, and enhance the loop performance. The loop has faster acquisition, less steady state phase error, and wider locking range compared to the conventional ZCDPLL. This work presents a Zero Crossing Digital Phase Locked Loop with Arc Sine block (ZCDPLL-AS). The performance of the loop is analyzed under mobile faded channel conditions. The mobile channel is assumed to be two path fading channel corrupted by additive white Gaussian noise (AWGM). It is shown that for a constant filter gain, the frequency spread has no effect on the steady state phase error variance when the loop is subjected to a phase step. For a frequency step and under the same conditions, the effect on phase error is minimal.展开更多
基金The National Natural Science Foundation of China under contract Nos 41941010 and 42006184the Fundamental Research Funds for the Central Universities under contract No.2042022kf1068。
文摘In recent years,there has been a significant acceleration in the thinning,calving and retreat of the Pine Island Ice Shelf(PIIS).The basal channels,results of enhanced basal melting,have the potential to significantly impact the stability of the PIIS.In this study,we used a variety of remote sensing data,including Landsat,REMA DEM,ICESat-1 and ICESat-2 satellite altimetry observations,and Ice Bridge airborne measurements,to study the spatiotemporal changes in the basal channels from 2003 to 2020 and basal melt rate from 2010 to 2017 of the PIIS under the Eulerian framework.We found that the basal channels are highly developed in the PIIS,with a total length exceeding 450 km.Most of the basal channels are ocean-sourced or groundingline-sourced basal channels,caused by the rapid melting under the ice shelf or near the groundingline.A raised seabed prevented warm water intrusion into the eastern branch of the PIIS,resulting in a lower basal melt rate in that area.In contrast,a deepsea trough facilitates warm seawater into the mainstream and the western branch of the PIIS,resulting in a higher basal melt rate in the main-stream,and the surface elevation changes above the basal channels of the mainstream and western branch are more significant.The El Ni?o event in 2015–2016 possibly slowed down the basal melting of the PIIS by modulating wind field,surface sea temperature and depth seawater temperature.Ocean and atmospheric changes were driven by El Ni?o,which can further explain and confirm the changes in the basal melting of the PIIS.
基金This paper is part of the Youth Program of Science and Technology Research of Chongqing Municipal Education Commission(KJQN202300545)Youth Program of National Social Science Fund of China(21CJY001)Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202300567).
文摘The rapid development of the digital economy has provided a new impetus for rural residents to extend their working hours.Based on the data collected by the China Labor-force Dynamics Survey(CLDS)in 2014,2016,and 2018,this paper measured the development level of the digital economy in China from the perspectives of internet development and digital financial inclusion,and tested the mechanisms of how the digital economy affected rural residents’working hours.The results showed that the digital economy extended rural residents’working hours by expanding information channels and enhancing human capital,and this mechanism was affected by heterogeneity in rural residents’educational background,age,and social capital.Building on these findings,this paper holds that to increase rural residents’income by extending their working hours and achieving common prosperity for all,it is necessary to expand the opportunities for rural residents to participate in skills training and promote their accumulation of human capital.
基金supported by Beijing Natural Science Foundation(L212029,L221009)the National Natural Science Foundation of China(62271043,62371033)the Ministry of Education of China(8091B032123).
文摘An emerging railway technology called smart railway promises to deliver higher transportation efficiency,enhanced comfort in services,and greater eco-friendliness.The smart railway is expected to integrate fifth-generation mobile communication(5G),Artificial Intelligence(AI),and other technologies,which poses new problems in the construction,operation and maintenance of railway wireless networks.Wireless Digital Twins(DTs),which have recently emerged as a new paradigm for the design of wireless networks,can address these problems and enable the whole lifecycle management of railway wireless networks.However,there are still many scientific issues and challenges for railway-oriented wireless DT.Relevant key technologies to solve these problems are introduced and described,including characterization of materials'physical-EM properties,autonomous reconstruction of Three-dimensional(3D)environment model,AI-empowered environmental cognition,Ray-Tracing(RT),model-based and AIbased RT acceleration,and generation of multi-spectra sensing data.Moreover,this paper presents our research results for each key technology and describes the wireless network planning and optimization system based on highperformance RT developed by our laboratory.This paper outlines the framework for realizing the wireless DT of smart railways,providing the direction for future research.
基金supported by National Key R&D Program of China under Grant 2021YFB3901302 and 2021YFB2900301the National Natural Science Foundation of China under Grant 62271037,62001519,62221001,and U21A20445+1 种基金the State Key Laboratory of Advanced Rail Autonomous Operation under Grant RCS2022ZZ004the Fundamental Research Funds for the Central Universities under Grant 2022JBQY004.
文摘Integration of digital twin(DT)and wireless channel provides new solution of channel modeling and simulation,and can assist to design,optimize and evaluate intelligent wireless communication system and networks.With DT channel modeling,the generated channel data can be closer to realistic channel measurements without requiring a prior channel model,and amount of channel data can be significantly increased.Artificial intelligence(AI)based modeling approach shows outstanding performance to solve such problems.In this work,a channel modeling method based on generative adversarial networks is proposed for DT channel,which can generate identical statistical distribution with measured channel.Model validation is conducted by comparing DT channel characteristics with measurements,and results show that DT channel leads to fairly good agreement with measured channel.Finally,a link-layer simulation is implemented based on DT channel.It is found that the proposed DT channel model can be well used to conduct link-layer simulation and its performance is comparable to using measurement data.The observations and results can facilitate the development of DT channel modeling and provide new thoughts for DT channel applications,as well as improving the performance and reliability of intelligent communication networking.
基金the National High-Tech Research and Development Program (2002AA123032)the Innovative Research Team Program of UESTC, China.
文摘The novel closed-form expressions for the average channel capacity of dual selection diversity is presented, as well as, the bit-error rate (BER) of several coherent and noncoherent digital modulation schemes in the correlated Weibull fading channels with nonidentical statisticS. The results are expressed in terms of Meijer's Gfunction, which can be easily evaluated numerically. The simulation results are presented to validate the proposed theoretical analysis and to examine the effects of the fading severity on the concerned quantities.
文摘Objective To investigate the changing regularity of thoracic pedicle screw channel (PSC) in different transverse screw angle(TSA).Methods CT scan images of thoracic vertebrae of a healthy adult ware digitally analyzed by Mimics 10.01
基金supported by the Program for New Century Excellent Talents in University(NCET-06-0921)
文摘An approach is proposed to realize a digital channelized receiver in the fractional Fourier domain (FRFD) for signal intercept applications. The presented architecture can be considered as a generalization of that in the traditional Fourier domain. Since the linear frequency modulation (LFM) signal has a good energy concentration in the FRFD, by choosing an appropriate fractional Fourier transform (FRFT) order, the presented architecture can concentrate the broadband LFM signal into only one sub-channel and that will prevent it from crossing several sub-channels. Thus the performance of the signal detection and parameter estimation after the sub-channel output will be improved significantly. The computational complexity is reduced enormously due to the implementation of the polyphase filter bank decomposition, thus the proposed architecture can be realized as efficiently as in the Fourier domain. The related simulation results are presented to verify the validity of the theories and methods involved in this paper.
基金The National Natural Science Foundation of China under contract Nos 41941010 and 42006184the Fundamental Research Funds for the Central Universities under contract No.2042022kf1068the Independent Scientific Research Project of the State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing.
文摘The basal channel is a detailed morphological feature of the ice shelf caused by uneven basal melting.This kind of specifically morphology is widely distributed in polar ice shelves.It is an important research object of sea-ice interaction and plays a vital role in studying the relationship between the ice sheet/ice shelf and global warming.In this paper,high-resolution remote sensing image and ice penetration data were combined to extract the basal channel of the Pine Island Ice Shelf.The depth variation of Pine Island Ice Shelf in the recent 20 years was analyzed and discussed by using ICESat-1,ICESat-2,and IceBridge data.Combined with relevant marine meteorological elements(sea surface temperature,surface melting days,circumpolar deep water and wind)to analyze the basal channel changes,the redistribution of ocean heat is considered to be the most important factor affecting the evolution and development of the basal channel.
文摘A novel efficient partial sharing channelization structure with odd and even stacking is designed and implemented. There are two special designs in the proposed structure. Firstly, by the intensive channel overlap design, for non-cooperative wideband signals, the proposed structure can achieve good parameter estimation accuracy and high probability of complete interception.Secondly, based on the partial sharing design developed in this paper, the computation burden of the proposed structure can be greatly reduced compared with the traditional directly implemented structures. Experiments and numerical simulations are conducted to evaluate the proposed structure, which shows its improvements over traditional methods in terms of field programmable gate arrays(FPGA) resource consumption and parameter estimation accuracy.
文摘In the context of the digital economy, agricultural product marketing has also undergone new development, and the models of agricultural product marketing are constantly innovating. Based on the current sales situation of Tashan Pomegranate, this paper analyzed the existing sales channels of Tashan Pomegranate. It found that Tashan Pomegranate currently has insufficient online marketing channels, incomplete logistics system, and a lack of comprehensive talents in online marketing. In response to the existing problems, constructive recommendations are proposed for the online marketing channels of agricultural products in Lieshan District, and a network marketing path suitable for Tashan Pomegranate in Lieshan District was explored.
基金supportedin part by Natural Science Foundation under grant No.91338108,91438206Co-innovation Laboratory of Aerospace Broadband Network Technology
文摘For digital channelized frequency division multiple access based satellite communication(SATCOM) systems,it is a challenging but critical issue to improve the transponder power and spectrum efficiency simultaneously under limited and non-linear high-power amplifier conditions.In this paper,different from the traditional link supportability designs aiming at minimizing the total transponder output power,a maximal sum Shannon capacity optimization objective is firstly raised subject to link supportability constraints.Furthermore,an efficient multilevel optimization(MO) algorithm is proposed to solve the considered optimization problem in the case of single link for each terminal.Moreover,in the case of multiple links for one terminal,an improved MO algorithm involving Golden section and discrete gradient searching procedures is proposed to optimize power allocation over all links.Finally,several numerical results are provided to demonstrate the effectiveness of our proposals.Comparison results show that,by the MO algorithm,not only all links' supportability can be guaranteed but also a larger sum capacity can be achieved with lower complexity.
基金National Science and Technology Major Project of China(No.DHZX01A02004)
文摘The absolute delay caused by equipment of radio navigation satellite service (RNSS) signal channel must be calibrated in the application of positioning. The measurement accuracy of absolute delay will affect the positioning precision of RNSS user. An absolute delay measurement technique using digital envelope detection was developed for RNSS signal transmission channel. The RNSS transmission signal of navigation satellite and the one pulse per second (1PPS)generated by satellite time keeping system were sampled synchronously. With sampling data of 1PPS,the reference point of the absolute delay can be decided at first,and then sampling data of RNSS transmission signal were truncated. The truncated data were processed using digital envelop detection algorithm to search the phase converting points of RNSS signal. Finally,the absolute delay of RNSS signal transmitting channel was calculated. Uncertainty of measurement with proposed technique is lower than 0. 2 ns as the sampling frequency is 10 GHz.
文摘Formany years,researchers have explored power allocation(PA)algorithms driven bymodels in wireless networks where multiple-user communications with interference are present.Nowadays,data-driven machine learning methods have become quite popular in analyzing wireless communication systems,which among them deep reinforcement learning(DRL)has a significant role in solving optimization issues under certain constraints.To this purpose,in this paper,we investigate the PA problem in a k-user multiple access channels(MAC),where k transmitters(e.g.,mobile users)aim to send an independent message to a common receiver(e.g.,base station)through wireless channels.To this end,we first train the deep Q network(DQN)with a deep Q learning(DQL)algorithm over the simulation environment,utilizing offline learning.Then,the DQN will be used with the real data in the online training method for the PA issue by maximizing the sumrate subjected to the source power.Finally,the simulation results indicate that our proposedDQNmethod provides better performance in terms of the sumrate compared with the available DQL training approaches such as fractional programming(FP)and weighted minimum mean squared error(WMMSE).Additionally,by considering different user densities,we show that our proposed DQN outperforms benchmark algorithms,thereby,a good generalization ability is verified over wireless multi-user communication systems.
文摘This paper develops an efficient pseudo-random number generator for validation of digital communication channels and secure disc. Drives. Simulation results validates the effectiveness of the random number generator.
文摘Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, ischemic preconditioning was induced by left anterior descending occlusion (three, 5 min episodes separated by 5 min of reperfusion), ischemia-reperfusion injury was induced by 30 min coronary artery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size and scores of ventricular arrhythmias were measured. The expression of Gαq/11 protein in the heart was measured by Western blot analysis in the second series. Results Ischemic preconditioning rats showed decreased infarct size and scores of ventricular arrhythmia vs non-IP control rats. The effect of IPC was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective KATP channel inhibitor. IPC caused a significant increase in the expression of Gαq/11 protein. Conclusions Activations of Gαq/11 signal pathway and KATP channel played significant roles in the classical cardioprotection of ischemic precon-ditioning rat heart and might be an important mechanism of signal transduction pathway during the ischemic preconditioning.
文摘Zero Crossing Digital Phase Locked Loop with Arc Sine block (AS-ZCDPLL) is used to linearize the phase difference detection, and enhance the loop performance. The loop has faster acquisition, less steady state phase error, and wider locking range compared to the conventional ZCDPLL. This work presents a Zero Crossing Digital Phase Locked Loop with Arc Sine block (ZCDPLL-AS). The performance of the loop is analyzed under mobile faded channel conditions. The mobile channel is assumed to be two path fading channel corrupted by additive white Gaussian noise (AWGM). It is shown that for a constant filter gain, the frequency spread has no effect on the steady state phase error variance when the loop is subjected to a phase step. For a frequency step and under the same conditions, the effect on phase error is minimal.