BACKGROUND This case report examines the challenges associated with removing a totally implantable venous access port(TIVAP)used for long-term chemotherapy in a patient with breast cancer.Prolonged use of TIVAPs can r...BACKGROUND This case report examines the challenges associated with removing a totally implantable venous access port(TIVAP)used for long-term chemotherapy in a patient with breast cancer.Prolonged use of TIVAPs can result in complications such as catheter kinking,thrombosis,and adhesions between the catheter and surrounding tissues,potentially complicating their removal.CASE SUMMARY A breast cancer patient with bone metastasis presented with difficulty aspirating blood from a TIVAP that had been placed in the right internal jugular vein for 3 years.Initial removal attempts at the Department of Venous Access Center were unsuccessful,likely due to adhesions,necessitating a subsequent successful catheter extraction in a hybrid operating room.Imaging revealed no abnor-malities,and the catheter was removed using a mosquito clamp to detach it from surrounding tissues.CONCLUSION This case highlights the challenges of removing TIVAPs inserted via the internal jugular vein,particularly when the catheter traverses the sternocleidomastoid muscle.Repeated neck movements might lead to significant adhesions around the catheter,complicating its removal.Careful consideration should be given during catheter placement to avoid muscle-related adhesions and facilitate smoother extraction in long-term use.展开更多
With the deployment of ultra-dense low earth orbit(LEO)satellite constellations,LEO satellite access network(LEO-SAN)is envisioned to achieve global Internet coverage.Meanwhile,the civil aviation communications have i...With the deployment of ultra-dense low earth orbit(LEO)satellite constellations,LEO satellite access network(LEO-SAN)is envisioned to achieve global Internet coverage.Meanwhile,the civil aviation communications have increased dramatically,especially for providing airborne Internet services.However,due to dynamic service demands and onboard LEO resources over time and space,it poses huge challenges in satellite-aircraft access and service management in ultra-dense LEO satellite networks(UDLSN).In this paper,we propose a deep reinforcement learning-based approach for ultra-dense LEO satellite-aircraft access and service management.Firstly,we develop an airborne Internet architecture based on UDLSN and design a management mechanism including medium earth orbit satellites to guarantee lightweight management.Secondly,considering latency-sensitive and latency-tolerant services,we formulate the problem of satellite-aircraft access and service management for civil aviation to ensure service continuity.Finally,we propose a proximal policy optimization-based access and service management algorithm to solve the formulated problem.Simulation results demonstrate the convergence and effectiveness of the proposed algorithm with satisfying the service continuity when applying to the UDLSN.展开更多
BACKGROUND Cancer patients with an implanted venous access port(IVAP)often manage their care at home during chemotherapy intervals,including maintaining the device,monitoring complications,and following medication ins...BACKGROUND Cancer patients with an implanted venous access port(IVAP)often manage their care at home during chemotherapy intervals,including maintaining the device,monitoring complications,and following medication instructions.Home care ensures continued support after discharge.However,due to factors such as age,gender,culture,psychological status,and family support,the quality of home care varies significantly.Understanding these factors can help provide targeted guidance to improve the care of cancer patients.AIM To explore IVAP chemotherapy on home care quality and its association with mental health and family support for cancer patients.METHODS This investigative study was based on a medical records system.It investigated the relationship between psychological status,family support,and home care quality in 180 patients with cancer undergoing IVAP chemotherapy.Psychological status was assessed using the State Anxiety Inventory(S-AI);family support was assessed using the Perceived Social Support Scale(PSSS),and home care quality was evaluated using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire(EORTC QLQ-C30).Pearson’s correlation and Structural Equation Modeling were used to analyze the interplay between these factors.RESULTS The average S-AI score was 47.52±14.47,PSSS was 52.48±12.64,and EORTC QLQ-C30 was 70.09±17.32.A substantial inverse relationship was observed between the EORTC QLQ-C30 and S-AI scores(r=-0.712).A significant positive correlation was found between the EORTC QLQ-C30 and the PSSS,with a correlation coefficient of(r=0.744).The multiple linear regression analysis indicated that family social support,psychological status,and average monthly family income were the main factors influencing the variation in the quality of home care,explaining 71.9%of the variation.The Structural Equation Modeling results indicated that psychological status acted as a partial mediator in the association between family social support and home care quality of life,explaining 32.78%of the mediation effect.CONCLUSION Psychological status and family social support positively impacted cancer patients’home care quality,with psychology partially mediating this effect.展开更多
Searchable encryption technology makes it convenient to search encrypted data with keywords for people.A data owner shared his data with other users on the cloud server.For security,it is necessary for him to build a ...Searchable encryption technology makes it convenient to search encrypted data with keywords for people.A data owner shared his data with other users on the cloud server.For security,it is necessary for him to build a fine-grained and flexible access control mechanism.The main idea of this paper is to let the owner classify his data and then authorizes others according to categories.The cloud server maintains a permission matrix,which will be used to verify whether a trapdoor is valid or not.In this way we can achieve access control and narrow the search range at the same time.We prove that our scheme can achieve index and trapdoor indistinguishability under chosen keywords attack security in the random oracles.展开更多
Equal access to social infrastructures is a fundamental prerequisite for sustainable development,but has long been a great challenge worldwide.Previous studies have primarily focused on the accessibility to social inf...Equal access to social infrastructures is a fundamental prerequisite for sustainable development,but has long been a great challenge worldwide.Previous studies have primarily focused on the accessibility to social infras-tructures in urban areas across various scales,with less attention to rural areas,where inequality can be more severe.Particularly,few have investigated the disparities of accessibility to social infrastructures between urban and rural areas.Here,using the Changsha-Zhuzhou-Xiangtan urban agglomeration,China,as an example,we investigated the inequality of accessibility in both urban and rural areas,and further compared the urban-rural difference.Accessibility was measured by travel time of residents to infrastructures.We selected four types of social infrastructures including supermarkets,bus stops,primary schools,and health care,which were funda-mentally important to both urban and rural residents.We found large disparities in accessibility between urban and rural areas,ranging from 20 min to 2 h.Rural residents had to spend one to two more hours to bus stops than urban residents,and 20 min more to the other three types of infrastructures.Furthermore,accessibility to multiple infrastructures showed greater urban-rural differences.Rural residents in more than half of the towns had no access to any infrastructure within 15 min,while more than 60%of the urban residents could access to all infrastructures within 15 min.Our results revealed quantitative accessibility gap between urban and rural areas and underscored the necessity of social infrastructures planning to address such disparities.展开更多
Beamforming in stand-alone Millimeter-Wave(mmWave)communications results in prolonged access times and latencies due to the increased number of measurements required to determine the optimal beam directions at the Mob...Beamforming in stand-alone Millimeter-Wave(mmWave)communications results in prolonged access times and latencies due to the increased number of measurements required to determine the optimal beam directions at the Mobile Station(MS)and Base Station(BS),returning the highest received signal level.Therefore,dynamic and fast access schemes that meet the Third-Generation Partnership Project(3GPP)specifications are required here.Therefore,in this paper,a novel initial access scheme is proposed for multiple MS users by leveraging for the first time a digital compass in the access procedure.Namely,when a new MS joins the footprint of a BS,it probes the channel for beacon signaling about the BS direction,i.e.,broadcasted by a neighboring MS that completed beam association at previous time steps.Then,a digital compass is utilized to adjust the coordinates of the BS according to the location of the new MS.The proposed scheme is applied for a single and multi-user settings at various broadcasting approaches.This includes a single associated MS user that broadcasts information to a single incoming MS user,a single user that broadcasts signals to multiple incoming users,or all multiple associated users broadcast to multiple incoming users.Overall,the proposed schemes yield in notable efficiency in terms of the computational complexity,access times,power and energy consumption as compared to existing access schemes.Further,high success rates are achieved at the detriment of relatively higher cost.展开更多
The Internet of Things(IoT)access controlmechanism may encounter security issues such as single point of failure and data tampering.To address these issues,a blockchain-based IoT reputation value attribute access cont...The Internet of Things(IoT)access controlmechanism may encounter security issues such as single point of failure and data tampering.To address these issues,a blockchain-based IoT reputation value attribute access control scheme is proposed.Firstly,writing the reputation value as an attribute into the access control policy,and then deploying the access control policy in the smart contract of the blockchain system can enable the system to provide more fine-grained access control;Secondly,storing a large amount of resources fromthe Internet of Things in Inter Planetary File System(IPFS)to improve system throughput;Finally,map resource access operations to qualification tokens to improve the performance of the access control system.Complete simulation experiments based on the Hyperledger Fabric platform.Fromthe simulation experimental results,it can be seen that the access control system can achieve more fine-grained and dynamic access control while maintaining high throughput and low time delay,providing sufficient reliability and security for access control of IoT devices.展开更多
Over the past few decades,the Internet has rapidly diffused across China.The spread of the Internet has had a profound economic and social impact on Chinese rural areas.Existing research shows that Internet access sig...Over the past few decades,the Internet has rapidly diffused across China.The spread of the Internet has had a profound economic and social impact on Chinese rural areas.Existing research shows that Internet access significantly impacts agricultural production and improves smallholder farmers’income.Beyond these,the Internet can affect other dimensions of social welfare.However,research about the impact of Internet access on dietary quality in rural China remains scarce.This study utilizes multi-period panel data from Fixed Observation Point in rural China from 2009 to 2015 to estimate the impact of Internet access on dietary quality and food consumption of rural households and conducts a causal analysis.Regression models with time and household fixed effects allow robust estimation while reducing potential issues of unobserved heterogeneity.The estimates show that Internet access has significantly increased rural household dietary quality(measured by the Chinese Diet Balance Index).Further research finds that Internet access has increased the consumption of animal products,such as aquatic and dairy products.We also examine the underlying mechanisms.Internet access improves dietary quality and food consumption mainly through increasing household income and food expenditure.These results encourage the promotion of Internet access as a valuable tool for nutritional improvements,especially in rural areas.展开更多
According to the feature of city’s apartment building in China,a kind of Multi-users Watt-hour Meter based on ATT7022B has been developed in this paper.The master-slave MCU control model and the principles of Time Sh...According to the feature of city’s apartment building in China,a kind of Multi-users Watt-hour Meter based on ATT7022B has been developed in this paper.The master-slave MCU control model and the principles of Time Sharing Multiplex are adopted in this Watt-hour Meter,its function includes the measurement of current, voltage,power,power factor and the overload protection.It supports remote reading,pre-payment,multi-rate and etc. The practice shows that this meter has high accuracy,runs stable.It has wide prospect in the future market.展开更多
As the risks associated with air turbulence are intensified by climate change and the growth of the aviation industry,it has become imperative to monitor and mitigate these threats to ensure civil aviation safety.The ...As the risks associated with air turbulence are intensified by climate change and the growth of the aviation industry,it has become imperative to monitor and mitigate these threats to ensure civil aviation safety.The eddy dissipation rate(EDR)has been established as the standard metric for quantifying turbulence in civil aviation.This study aims to explore a universally applicable symbolic classification approach based on genetic programming to detect turbulence anomalies using quick access recorder(QAR)data.The detection of atmospheric turbulence is approached as an anomaly detection problem.Comparative evaluations demonstrate that this approach performs on par with direct EDR calculation methods in identifying turbulence events.Moreover,comparisons with alternative machine learning techniques indicate that the proposed technique is the optimal methodology currently available.In summary,the use of symbolic classification via genetic programming enables accurate turbulence detection from QAR data,comparable to that with established EDR approaches and surpassing that achieved with machine learning algorithms.This finding highlights the potential of integrating symbolic classifiers into turbulence monitoring systems to enhance civil aviation safety amidst rising environmental and operational hazards.展开更多
Multi-user detection techniques are currently being studied as highly promising technologies for improving the performance of unsourced multiple access systems. In this paper, we propose joint multi-user detection sch...Multi-user detection techniques are currently being studied as highly promising technologies for improving the performance of unsourced multiple access systems. In this paper, we propose joint multi-user detection schemes with weighting factors for unsourced multiple access. First, we introduce bidirectional weighting factors in the extrinsic information passing process between the multi-user detector based on belief propagation (BP) and the LDPC decoder. Second, we incorporate bidirectional weighting factors in the message passing process between the MAC nodes and the user variable nodes in BP- based multi-user detector. The proposed schemes select the optimal weighting factors through simulations. The simulation results demonstrate that the proposed schemes exhibit significant performance improvements in terms of block error rate (BLER) compared to traditional schemes. .展开更多
Normally,in the downlink Network-Coded Multiple Access(NCMA)system,the same power is allocated to different users.However,equal power allocation is unsuitable for some scenarios,such as when user devices have differen...Normally,in the downlink Network-Coded Multiple Access(NCMA)system,the same power is allocated to different users.However,equal power allocation is unsuitable for some scenarios,such as when user devices have different Quality of Service(QoS)requirements.Hence,we study the power allocation in the downlink NCMA system in this paper,and propose a downlink Network-Coded Multiple Access with Diverse Power(NCMA-DP),wherein different amounts of power are allocated to different users.In terms of the Bit Error Rate(BER)of the multi-user decoder,and the number of packets required to correctly decode the message,the performance of the user with more allocated power is greatly improved compared to the Conventional NCMA(NCMA-C).Meanwhile,the performance of the user with less allocated power is still much better than NCMA-C.Furthermore,the overall throughput of NCMA-DP is greatly improved compared to that of NCMA-C.The simulation results demonstrate the remarkable performance of the proposed NCMA-DP.展开更多
Aim(s): Complex Arteriovenous fistula (AVF) poses challenges to cannulation. Ultrasound (US)-guided cannulation may promote successful cannulation and prevent AVF-related complications. Renal nurses performing US-guid...Aim(s): Complex Arteriovenous fistula (AVF) poses challenges to cannulation. Ultrasound (US)-guided cannulation may promote successful cannulation and prevent AVF-related complications. Renal nurses performing US-guided cannulation may improve successful cannulation and reduce complications associated with unnecessary punctures. The study aims to conduct the meta-analyze to examine the effectiveness of renal nurse-performed US-guided cannulation to improve successful cannulation and reduce AVF-related complications in difficult AVF access. Design: A meta-analysis of randomised controlled trials. Methods: A systemic search was performed on electronic databases including CINAHL Plus, Web of Science, and PubMed from inception to October 2023. Risk ratios (RR) and standardized mean differences (SMD) were estimated using random-effect models for considerable homogeneity, and the Scottish Intercollegiate Guidelines Network (SIGN) methodology was adopted for critical appraisal. Results: Four RCTs were included. The results showed US-guided AVF cannulation had a significant effect in improving successful cannulation (RR: 0.19, 95% CI: 0.06 to 0.63, p = 0.007), and was favorable in reducing cannulation-associated complications (RR: 0.44, 95% CI: 0.10 to 1.93, p = 0.28), compared with blind needle cannulation. Conclusion: US-guided cannulation performed by renal nurses has the potential to improve successful cannulation, and fewer complications in hemodialysis patients with difficult arteriovenous access. Relevance to Clinical Practice: The results suggest the value of further training for renal nurses in US-guided cannulation, and broader implementation of US-guided cannulation to improve patient outcomes. Future studies could explore the optimal nursing training and longer-term benefits of US-guided cannulation by renal nurses in difficult AVF access. Patient or Public Contribution: No Patient or Public Contribution as this is a meta-analysis using the secondary data published in the RCTs.展开更多
To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlin...To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlink cellular scenario with the aim of maximizing system spectral efficiency while guaranteeing user fairness.We first model the MSMURA problem as a dual-sequence decision-making process,and then solve it by a novel Transformerbased deep reinforcement learning(TDRL)approach.Specifically,the proposed TDRL approach can be achieved based on two aspects:1)To adapt to the dynamic wireless environment,the proximal policy optimization(PPO)algorithm is used to optimize the multi-slot RA strategy.2)To avoid co-channel interference,the Transformer-based PPO algorithm is presented to obtain the optimal multi-user RA scheme by exploring the mapping between user sequence and resource sequence.Experimental results show that:i)the proposed approach outperforms both the traditional and DRL methods in spectral efficiency and user fairness,ii)the proposed algorithm is superior to DRL approaches in terms of convergence speed and generalization performance.展开更多
There are numerous terminals in the satellite Internet of Things(IoT).To save cost and reduce power consumption,the system needs terminals to catch the characteristics of low power consumption and light control.The re...There are numerous terminals in the satellite Internet of Things(IoT).To save cost and reduce power consumption,the system needs terminals to catch the characteristics of low power consumption and light control.The regular random access(RA)protocols may generate large amounts of collisions,which degrade the system throughout severally.The near-far effect and power control technologies are not applicable in capture effect to obtain power difference,resulting in the collisions that cannot be separated.In fact,the optimal design at the receiving end can also realize the condition of packet power domain separation,but there are few relevant researches.In this paper,an auxiliary beamforming scheme is proposed for power domain signal separation.It adds an auxiliary reception beam based on the conventional beam,utilizing the correlation of packets in time-frequency domain between the main and auxiliary beam to complete signal separation.The roll-off belt of auxiliary beam is used to create the carrier-to-noise ratio(CNR)difference.This paper uses the genetic algorithm to optimize the auxiliary beam direction.Simulation results show that the proposed scheme outperforms slotted ALOHA(SA)in terms of system throughput per-formance and without bringing terminals additional control burden.展开更多
The hybrid carrier(HC)system rooted in the carrier fusion concept is gradually garnering attention.In this paper,we study the extended hybrid carrier(EHC)multiple access scheme to ensure reliable wireless communicatio...The hybrid carrier(HC)system rooted in the carrier fusion concept is gradually garnering attention.In this paper,we study the extended hybrid carrier(EHC)multiple access scheme to ensure reliable wireless communication.By employing the EHC modulation,a power layered multiplexing framework is realized,which exhibits enhanced interference suppression capability owing to the more uniform energy distribution design.The implementation method and advantage mechanism are explicated respectively for the uplink and downlink,and the performance analysis under varying channel conditions is provided.In addition,considering the connectivity demand,we explore the non-orthogonal multiple access(NOMA)method of the EHC system and develop the EHC sparse code multiple access scheme.The proposed scheme melds the energy spread superiority of EHC with the access capacity of NOMA,facilitating superior support for massive connectivity in high mobility environments.Simulation results have verified the feasibility and advantages of the proposed scheme.Compared with existing HC multiple access schemes,the proposed scheme exhibits robust bit error rate performance and can better guarantee multiple access performance in complex scenarios of nextgeneration communications.展开更多
基金Supported by the Science and Technology Research Project of Jiangxi Provincial Education Department,No.GJJ2208202Science and Technology Program Project of Health Commission of Jiangxi Province,No.202510069+1 种基金Jiangxi Cancer Hospital Doctoral Start-up Fund,No.BSQDJ202309Jiangxi Province Gan Po Talent Support Program,No.20232BCJ23035.
文摘BACKGROUND This case report examines the challenges associated with removing a totally implantable venous access port(TIVAP)used for long-term chemotherapy in a patient with breast cancer.Prolonged use of TIVAPs can result in complications such as catheter kinking,thrombosis,and adhesions between the catheter and surrounding tissues,potentially complicating their removal.CASE SUMMARY A breast cancer patient with bone metastasis presented with difficulty aspirating blood from a TIVAP that had been placed in the right internal jugular vein for 3 years.Initial removal attempts at the Department of Venous Access Center were unsuccessful,likely due to adhesions,necessitating a subsequent successful catheter extraction in a hybrid operating room.Imaging revealed no abnor-malities,and the catheter was removed using a mosquito clamp to detach it from surrounding tissues.CONCLUSION This case highlights the challenges of removing TIVAPs inserted via the internal jugular vein,particularly when the catheter traverses the sternocleidomastoid muscle.Repeated neck movements might lead to significant adhesions around the catheter,complicating its removal.Careful consideration should be given during catheter placement to avoid muscle-related adhesions and facilitate smoother extraction in long-term use.
基金supported in part by the National Key R&D Program of China under Grant 2020YFB1806104in part by Innovation and Entrepreneurship of Jiangsu Province High-level Talent Programin part by Natural Sciences and Engineering Research Council of Canada(NSERC).
文摘With the deployment of ultra-dense low earth orbit(LEO)satellite constellations,LEO satellite access network(LEO-SAN)is envisioned to achieve global Internet coverage.Meanwhile,the civil aviation communications have increased dramatically,especially for providing airborne Internet services.However,due to dynamic service demands and onboard LEO resources over time and space,it poses huge challenges in satellite-aircraft access and service management in ultra-dense LEO satellite networks(UDLSN).In this paper,we propose a deep reinforcement learning-based approach for ultra-dense LEO satellite-aircraft access and service management.Firstly,we develop an airborne Internet architecture based on UDLSN and design a management mechanism including medium earth orbit satellites to guarantee lightweight management.Secondly,considering latency-sensitive and latency-tolerant services,we formulate the problem of satellite-aircraft access and service management for civil aviation to ensure service continuity.Finally,we propose a proximal policy optimization-based access and service management algorithm to solve the formulated problem.Simulation results demonstrate the convergence and effectiveness of the proposed algorithm with satisfying the service continuity when applying to the UDLSN.
文摘BACKGROUND Cancer patients with an implanted venous access port(IVAP)often manage their care at home during chemotherapy intervals,including maintaining the device,monitoring complications,and following medication instructions.Home care ensures continued support after discharge.However,due to factors such as age,gender,culture,psychological status,and family support,the quality of home care varies significantly.Understanding these factors can help provide targeted guidance to improve the care of cancer patients.AIM To explore IVAP chemotherapy on home care quality and its association with mental health and family support for cancer patients.METHODS This investigative study was based on a medical records system.It investigated the relationship between psychological status,family support,and home care quality in 180 patients with cancer undergoing IVAP chemotherapy.Psychological status was assessed using the State Anxiety Inventory(S-AI);family support was assessed using the Perceived Social Support Scale(PSSS),and home care quality was evaluated using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire(EORTC QLQ-C30).Pearson’s correlation and Structural Equation Modeling were used to analyze the interplay between these factors.RESULTS The average S-AI score was 47.52±14.47,PSSS was 52.48±12.64,and EORTC QLQ-C30 was 70.09±17.32.A substantial inverse relationship was observed between the EORTC QLQ-C30 and S-AI scores(r=-0.712).A significant positive correlation was found between the EORTC QLQ-C30 and the PSSS,with a correlation coefficient of(r=0.744).The multiple linear regression analysis indicated that family social support,psychological status,and average monthly family income were the main factors influencing the variation in the quality of home care,explaining 71.9%of the variation.The Structural Equation Modeling results indicated that psychological status acted as a partial mediator in the association between family social support and home care quality of life,explaining 32.78%of the mediation effect.CONCLUSION Psychological status and family social support positively impacted cancer patients’home care quality,with psychology partially mediating this effect.
基金This work is partially supported by the Fundamental Research Funds for the Central Universities(No.30918012204)。
文摘Searchable encryption technology makes it convenient to search encrypted data with keywords for people.A data owner shared his data with other users on the cloud server.For security,it is necessary for him to build a fine-grained and flexible access control mechanism.The main idea of this paper is to let the owner classify his data and then authorizes others according to categories.The cloud server maintains a permission matrix,which will be used to verify whether a trapdoor is valid or not.In this way we can achieve access control and narrow the search range at the same time.We prove that our scheme can achieve index and trapdoor indistinguishability under chosen keywords attack security in the random oracles.
基金supported by funding from the National Natural Science Foundation of China(Grant No.U21A2010)the National Science Fund for Distinguished Young Scholars(Grant No.42225104)the National Key Research and Development Program(Grant No.2022YFF130110O).
文摘Equal access to social infrastructures is a fundamental prerequisite for sustainable development,but has long been a great challenge worldwide.Previous studies have primarily focused on the accessibility to social infras-tructures in urban areas across various scales,with less attention to rural areas,where inequality can be more severe.Particularly,few have investigated the disparities of accessibility to social infrastructures between urban and rural areas.Here,using the Changsha-Zhuzhou-Xiangtan urban agglomeration,China,as an example,we investigated the inequality of accessibility in both urban and rural areas,and further compared the urban-rural difference.Accessibility was measured by travel time of residents to infrastructures.We selected four types of social infrastructures including supermarkets,bus stops,primary schools,and health care,which were funda-mentally important to both urban and rural residents.We found large disparities in accessibility between urban and rural areas,ranging from 20 min to 2 h.Rural residents had to spend one to two more hours to bus stops than urban residents,and 20 min more to the other three types of infrastructures.Furthermore,accessibility to multiple infrastructures showed greater urban-rural differences.Rural residents in more than half of the towns had no access to any infrastructure within 15 min,while more than 60%of the urban residents could access to all infrastructures within 15 min.Our results revealed quantitative accessibility gap between urban and rural areas and underscored the necessity of social infrastructures planning to address such disparities.
基金funded by the Deanship of Scientific Research at King Faisal University,grant number 1811025.
文摘Beamforming in stand-alone Millimeter-Wave(mmWave)communications results in prolonged access times and latencies due to the increased number of measurements required to determine the optimal beam directions at the Mobile Station(MS)and Base Station(BS),returning the highest received signal level.Therefore,dynamic and fast access schemes that meet the Third-Generation Partnership Project(3GPP)specifications are required here.Therefore,in this paper,a novel initial access scheme is proposed for multiple MS users by leveraging for the first time a digital compass in the access procedure.Namely,when a new MS joins the footprint of a BS,it probes the channel for beacon signaling about the BS direction,i.e.,broadcasted by a neighboring MS that completed beam association at previous time steps.Then,a digital compass is utilized to adjust the coordinates of the BS according to the location of the new MS.The proposed scheme is applied for a single and multi-user settings at various broadcasting approaches.This includes a single associated MS user that broadcasts information to a single incoming MS user,a single user that broadcasts signals to multiple incoming users,or all multiple associated users broadcast to multiple incoming users.Overall,the proposed schemes yield in notable efficiency in terms of the computational complexity,access times,power and energy consumption as compared to existing access schemes.Further,high success rates are achieved at the detriment of relatively higher cost.
文摘The Internet of Things(IoT)access controlmechanism may encounter security issues such as single point of failure and data tampering.To address these issues,a blockchain-based IoT reputation value attribute access control scheme is proposed.Firstly,writing the reputation value as an attribute into the access control policy,and then deploying the access control policy in the smart contract of the blockchain system can enable the system to provide more fine-grained access control;Secondly,storing a large amount of resources fromthe Internet of Things in Inter Planetary File System(IPFS)to improve system throughput;Finally,map resource access operations to qualification tokens to improve the performance of the access control system.Complete simulation experiments based on the Hyperledger Fabric platform.Fromthe simulation experimental results,it can be seen that the access control system can achieve more fine-grained and dynamic access control while maintaining high throughput and low time delay,providing sufficient reliability and security for access control of IoT devices.
基金This study was supported in part by the National Natural Science Foundation of China(71973136 and 72061147002)the 2115 Talent Development Program of China Agricultural University.
文摘Over the past few decades,the Internet has rapidly diffused across China.The spread of the Internet has had a profound economic and social impact on Chinese rural areas.Existing research shows that Internet access significantly impacts agricultural production and improves smallholder farmers’income.Beyond these,the Internet can affect other dimensions of social welfare.However,research about the impact of Internet access on dietary quality in rural China remains scarce.This study utilizes multi-period panel data from Fixed Observation Point in rural China from 2009 to 2015 to estimate the impact of Internet access on dietary quality and food consumption of rural households and conducts a causal analysis.Regression models with time and household fixed effects allow robust estimation while reducing potential issues of unobserved heterogeneity.The estimates show that Internet access has significantly increased rural household dietary quality(measured by the Chinese Diet Balance Index).Further research finds that Internet access has increased the consumption of animal products,such as aquatic and dairy products.We also examine the underlying mechanisms.Internet access improves dietary quality and food consumption mainly through increasing household income and food expenditure.These results encourage the promotion of Internet access as a valuable tool for nutritional improvements,especially in rural areas.
文摘According to the feature of city’s apartment building in China,a kind of Multi-users Watt-hour Meter based on ATT7022B has been developed in this paper.The master-slave MCU control model and the principles of Time Sharing Multiplex are adopted in this Watt-hour Meter,its function includes the measurement of current, voltage,power,power factor and the overload protection.It supports remote reading,pre-payment,multi-rate and etc. The practice shows that this meter has high accuracy,runs stable.It has wide prospect in the future market.
基金supported by the Meteorological Soft Science Project(Grant No.2023ZZXM29)the Natural Science Fund Project of Tianjin,China(Grant No.21JCYBJC00740)the Key Research and Development-Social Development Program of Jiangsu Province,China(Grant No.BE2021685).
文摘As the risks associated with air turbulence are intensified by climate change and the growth of the aviation industry,it has become imperative to monitor and mitigate these threats to ensure civil aviation safety.The eddy dissipation rate(EDR)has been established as the standard metric for quantifying turbulence in civil aviation.This study aims to explore a universally applicable symbolic classification approach based on genetic programming to detect turbulence anomalies using quick access recorder(QAR)data.The detection of atmospheric turbulence is approached as an anomaly detection problem.Comparative evaluations demonstrate that this approach performs on par with direct EDR calculation methods in identifying turbulence events.Moreover,comparisons with alternative machine learning techniques indicate that the proposed technique is the optimal methodology currently available.In summary,the use of symbolic classification via genetic programming enables accurate turbulence detection from QAR data,comparable to that with established EDR approaches and surpassing that achieved with machine learning algorithms.This finding highlights the potential of integrating symbolic classifiers into turbulence monitoring systems to enhance civil aviation safety amidst rising environmental and operational hazards.
文摘Multi-user detection techniques are currently being studied as highly promising technologies for improving the performance of unsourced multiple access systems. In this paper, we propose joint multi-user detection schemes with weighting factors for unsourced multiple access. First, we introduce bidirectional weighting factors in the extrinsic information passing process between the multi-user detector based on belief propagation (BP) and the LDPC decoder. Second, we incorporate bidirectional weighting factors in the message passing process between the MAC nodes and the user variable nodes in BP- based multi-user detector. The proposed schemes select the optimal weighting factors through simulations. The simulation results demonstrate that the proposed schemes exhibit significant performance improvements in terms of block error rate (BLER) compared to traditional schemes. .
文摘Normally,in the downlink Network-Coded Multiple Access(NCMA)system,the same power is allocated to different users.However,equal power allocation is unsuitable for some scenarios,such as when user devices have different Quality of Service(QoS)requirements.Hence,we study the power allocation in the downlink NCMA system in this paper,and propose a downlink Network-Coded Multiple Access with Diverse Power(NCMA-DP),wherein different amounts of power are allocated to different users.In terms of the Bit Error Rate(BER)of the multi-user decoder,and the number of packets required to correctly decode the message,the performance of the user with more allocated power is greatly improved compared to the Conventional NCMA(NCMA-C).Meanwhile,the performance of the user with less allocated power is still much better than NCMA-C.Furthermore,the overall throughput of NCMA-DP is greatly improved compared to that of NCMA-C.The simulation results demonstrate the remarkable performance of the proposed NCMA-DP.
文摘Aim(s): Complex Arteriovenous fistula (AVF) poses challenges to cannulation. Ultrasound (US)-guided cannulation may promote successful cannulation and prevent AVF-related complications. Renal nurses performing US-guided cannulation may improve successful cannulation and reduce complications associated with unnecessary punctures. The study aims to conduct the meta-analyze to examine the effectiveness of renal nurse-performed US-guided cannulation to improve successful cannulation and reduce AVF-related complications in difficult AVF access. Design: A meta-analysis of randomised controlled trials. Methods: A systemic search was performed on electronic databases including CINAHL Plus, Web of Science, and PubMed from inception to October 2023. Risk ratios (RR) and standardized mean differences (SMD) were estimated using random-effect models for considerable homogeneity, and the Scottish Intercollegiate Guidelines Network (SIGN) methodology was adopted for critical appraisal. Results: Four RCTs were included. The results showed US-guided AVF cannulation had a significant effect in improving successful cannulation (RR: 0.19, 95% CI: 0.06 to 0.63, p = 0.007), and was favorable in reducing cannulation-associated complications (RR: 0.44, 95% CI: 0.10 to 1.93, p = 0.28), compared with blind needle cannulation. Conclusion: US-guided cannulation performed by renal nurses has the potential to improve successful cannulation, and fewer complications in hemodialysis patients with difficult arteriovenous access. Relevance to Clinical Practice: The results suggest the value of further training for renal nurses in US-guided cannulation, and broader implementation of US-guided cannulation to improve patient outcomes. Future studies could explore the optimal nursing training and longer-term benefits of US-guided cannulation by renal nurses in difficult AVF access. Patient or Public Contribution: No Patient or Public Contribution as this is a meta-analysis using the secondary data published in the RCTs.
基金supported by the National Natural Science Foundation of China(No.62071354)the Key Research and Development Program of Shaanxi(No.2022ZDLGY05-08)supported by the ISN State Key Laboratory。
文摘To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlink cellular scenario with the aim of maximizing system spectral efficiency while guaranteeing user fairness.We first model the MSMURA problem as a dual-sequence decision-making process,and then solve it by a novel Transformerbased deep reinforcement learning(TDRL)approach.Specifically,the proposed TDRL approach can be achieved based on two aspects:1)To adapt to the dynamic wireless environment,the proximal policy optimization(PPO)algorithm is used to optimize the multi-slot RA strategy.2)To avoid co-channel interference,the Transformer-based PPO algorithm is presented to obtain the optimal multi-user RA scheme by exploring the mapping between user sequence and resource sequence.Experimental results show that:i)the proposed approach outperforms both the traditional and DRL methods in spectral efficiency and user fairness,ii)the proposed algorithm is superior to DRL approaches in terms of convergence speed and generalization performance.
基金supported by the National Science Foundation of China(No.U21A20450)Natural Science Foundation of Jiangsu Province Major Project(No.BK20192002)+1 种基金National Natural Science Foundation of China(No.61971440)National Natural Science Foundation of China(No.62271266).
文摘There are numerous terminals in the satellite Internet of Things(IoT).To save cost and reduce power consumption,the system needs terminals to catch the characteristics of low power consumption and light control.The regular random access(RA)protocols may generate large amounts of collisions,which degrade the system throughout severally.The near-far effect and power control technologies are not applicable in capture effect to obtain power difference,resulting in the collisions that cannot be separated.In fact,the optimal design at the receiving end can also realize the condition of packet power domain separation,but there are few relevant researches.In this paper,an auxiliary beamforming scheme is proposed for power domain signal separation.It adds an auxiliary reception beam based on the conventional beam,utilizing the correlation of packets in time-frequency domain between the main and auxiliary beam to complete signal separation.The roll-off belt of auxiliary beam is used to create the carrier-to-noise ratio(CNR)difference.This paper uses the genetic algorithm to optimize the auxiliary beam direction.Simulation results show that the proposed scheme outperforms slotted ALOHA(SA)in terms of system throughput per-formance and without bringing terminals additional control burden.
基金supported in part by the National Natural Science Foundation of China under Grant U23A20278in part by the National Natural Science Foundation of China under Grant 62171151in part by the Fundamental Research Funds for the Central Universities under Grant HIT.OCEF.2021012。
文摘The hybrid carrier(HC)system rooted in the carrier fusion concept is gradually garnering attention.In this paper,we study the extended hybrid carrier(EHC)multiple access scheme to ensure reliable wireless communication.By employing the EHC modulation,a power layered multiplexing framework is realized,which exhibits enhanced interference suppression capability owing to the more uniform energy distribution design.The implementation method and advantage mechanism are explicated respectively for the uplink and downlink,and the performance analysis under varying channel conditions is provided.In addition,considering the connectivity demand,we explore the non-orthogonal multiple access(NOMA)method of the EHC system and develop the EHC sparse code multiple access scheme.The proposed scheme melds the energy spread superiority of EHC with the access capacity of NOMA,facilitating superior support for massive connectivity in high mobility environments.Simulation results have verified the feasibility and advantages of the proposed scheme.Compared with existing HC multiple access schemes,the proposed scheme exhibits robust bit error rate performance and can better guarantee multiple access performance in complex scenarios of nextgeneration communications.