Nowadays, there has been a rapid increase in the variety and popularity of messaging systems and social networks. It is imperative to consider the effect and impact of the number of words feature on the verification p...Nowadays, there has been a rapid increase in the variety and popularity of messaging systems and social networks. It is imperative to consider the effect and impact of the number of words feature on the verification process for modern messaging systems such as Twitter, Facebook, SMS and Email. Given the volume of text is often a restricted factor (due to the nature of messaging systems), key to this investigation is a better understanding of what length of message is required to improve performance. A large historical dataset containing 50 participants, the four datasets containing a large number of messaging system samples (4539 samples for Facebook, 13,616 for Twitter, 6538 for Email and 106,359 for Text message), the best performance was for Text messages, with an EER of 7.6% if the number of words was more than nine;followed by Email with an EER of 14.9% if the number of words was between 25 to 60;then, Twitter tweets, with an EER of 22.5% if the number of words was less than ten. Finally, the Facebook platform with an EER of 31.9% if the number of words was over 11.展开更多
In this paper,an index modulation(IM)aided uplink orthogonal time frequency space modulation(OTFS)structure for sparse code multiple access(SCMA)is proposed.To be more specific,the information bits are firstly partiti...In this paper,an index modulation(IM)aided uplink orthogonal time frequency space modulation(OTFS)structure for sparse code multiple access(SCMA)is proposed.To be more specific,the information bits are firstly partitioned for transmit antenna(TA)selection and sparse codeword mapping,respectively.Subsequently,the codewords deployed on the 2-dimensional(2D)delay-Doppler(DD)plane are transmitted by the selected TA,and the superimposed signals are jointly detected at the receiver.Furthermore,a low-complexity zero-embedded expectation propagation(ZE-EP)detector is conceived,where the codebooks are extended with zero vectors to reflect the silent indices.The simulation results demonstrate that the proposed IM-OTFS-SCMA system is capable of providing significant performance gain over the OTFS-SCMA counterpart.展开更多
Recursively embedded atom neural network(REANN)is a general-purpose atomistic machine learning software package for representing potential energy and other physical properties.The original REANN 1.0 architecture is a ...Recursively embedded atom neural network(REANN)is a general-purpose atomistic machine learning software package for representing potential energy and other physical properties.The original REANN 1.0 architecture is a physically inspired invariant message passing neural network,which was designed for systems with a limited number of elements.It is efficient but hardly transferable to more complex multi-element systems.In this work,we release REANN 2.0 aimed at multi-element systems and universal potentials,which integrates element embedding and equivariant representation.Compared to the first version,REANN 2.0 demonstrates enhanced ele-ment transferability and higher accuracy across various periodic systems with higher efficiency.Built upon this framework,a pre-trained REANN-MPtrj model without fine-tuning accurately predicts the lithium-ion diffusion dynamics in a benchmark solid-state electrolyte Li_(3)YCl_(6).We hope this open-source software package will facilitate the development of computationally efficient universal potentials in the future.展开更多
In order to meet the needs of Agricultural Meteorology business and research,an edition system of agricultural meteorology short message was established based on the Microsoft Access 2000 database and visualization de...In order to meet the needs of Agricultural Meteorology business and research,an edition system of agricultural meteorology short message was established based on the Microsoft Access 2000 database and visualization developing software Visual Basic 6.0 in Liaoning Province.The basic principles of agro-meteorological text editing and system optimization ideas were pointed out.The meteorological conditions of the main crops growth needed in material library were introduced.展开更多
Objective: To compare the efficacy of a short messaging service (SMS) text messaging and phone reminder to im-prove attendance rates at a health promotion center. Methods: A total of 1 859 participants who had schedul...Objective: To compare the efficacy of a short messaging service (SMS) text messaging and phone reminder to im-prove attendance rates at a health promotion center. Methods: A total of 1 859 participants who had scheduled appointments in the health promotion center of our hospital from April 2007 to May 2007 were enrolled in the study and randomly assigned into 3 groups: control (no reminder) group,SMS text messaging reminder group and telephone reminder group. Attendance rates and costs of interventions were collected. Results: A total of 1848 participants were eligible for analysis. Attendance rates of control,SMS and telephone groups were 80.5%,87.5% and 88.3%,respectively. The attendance rates were significantly higher in SMS and telephone groups than that in the control group,with odds ratio 1.698,95% confidence interval 1.224 to 2.316,P=0.001 in the SMS group,and odds ratio 1.829,95% confidence interval 1.333 to 2.509,P<0.001 in the telephone group. However,there was no difference between the SMS group and the telephone group (P=0.670). The cost effectiveness analysis showed that the cost per attendance for the SMS group (0.31 Yuan) was significantly lower than that for the telephone group (0.48 Yuan). Conclusion: SMS and telephone are effective reminders for improving attendance rate at a health promotion center. SMS reminder may be more cost-effective compared with the telephone reminder.展开更多
Aim To design the home -made embedded real time operating system COSIX V2.O/RT developing platform,the Mach operating system interprocess communication mech- anism based on object-oriented technique was analyzed. Met...Aim To design the home -made embedded real time operating system COSIX V2.O/RT developing platform,the Mach operating system interprocess communication mech- anism based on object-oriented technique was analyzed. Methods Not only being the trans-mission channel,but also being the abstract of all the entity in the Mach operating system.ports play the most important role in Mach IPC(interprocess communication).Ports were de-vided into 4 types: system ports, privileged ports user ports and kernel ports.All these ports'creation,run and kill processes and the message transmission in IPC were analyzed.ResultsMach IPC has been widely used in Client/Server run environment.Packing and unpacking inmessage transmission must restrict the run efficiency of IPC Conclusion To enhance IPC runefficiency and at the same time enhance the operating system's run efficiency,some of thesystem calls should be rewritten and implemented with trapped mode in kernel.In the end the aim of designing real time operating system is achieved.展开更多
Research on human behavior has attracted increasing attention recently because of its scientific significance and potential applications.Some empirical results have indicated that the timing of many human activities f...Research on human behavior has attracted increasing attention recently because of its scientific significance and potential applications.Some empirical results have indicated that the timing of many human activities follows non-Poisson statistics.We analyze a real-life huge dataset of short message communication with 6326713 users and 37577781 records during the 2006 Chinese New Year.The results show that the number of short message sendings,the interevent time between two consecutive short message sendings and the response time all follow heavy-tailed distribution.We further observe a strongly positive correlation between the activity and the power-law exponent of the interevent time distribution.In addition,the short message communication system displays a bursty property yet no memory effects,which is in particular different from some well-studied human-activited systems such as email-sending,library-loaning and file printing.展开更多
In this paper,we propose a joint channel estimation and symbol detection(JCESD)algorithm relying on message-passing algorithms(MPA)for orthogonal frequency division multiple access(OFDMA)systems.The channel estimation...In this paper,we propose a joint channel estimation and symbol detection(JCESD)algorithm relying on message-passing algorithms(MPA)for orthogonal frequency division multiple access(OFDMA)systems.The channel estimation and symbol detection leverage the framework of expectation propagation(EP)and belief propagation(BP)with the aid of Gaussian approximation,respectively.Furthermore,to reduce the computation complexity involved in channel estimation,the matrix inversion is transformed into a series of diagonal matrix inversions through the Sherman-Morrison formula.Simulation experiments show that the proposed algorithm can reduce the pilot overhead by about 50%,compared with the traditional linear minimum mean square error(LMMSE)algorithm,and can approach to the bit error rate(BER)performance bound of perfectly known channel state information within 0.1 dB.展开更多
In the era of Big Data, typical architecture of distributed real-time stream processing systems is the combination of Flume, Kafka, and Storm. As a kind of distributed message system, Kafka has the characteristics of ...In the era of Big Data, typical architecture of distributed real-time stream processing systems is the combination of Flume, Kafka, and Storm. As a kind of distributed message system, Kafka has the characteristics of horizontal scalability and high throughput, which is manly deployed in many areas in order to address the problem of speed mismatch between message producers and consumers. When using Kafka, we need to quickly receive data sent by producers. In addition, we need to send data to consumers quickly. Therefore, the performance of Kafka is of critical importance to the performance of the whole stream processing system. In this paper, we propose the improved design of real-time stream processing systems, and focus on improving the Kafka's data loading process.We use Kafka cat to transfer data from the source to Kafka topic directly, which can reduce the network transmission. We also utilize the memory file system to accelerate the process of data loading, which can address the bottleneck and performance problems caused by disk I/O. Extensive experiments are conducted to evaluate the performance, which show the superiority of our improved design.展开更多
Recently,the importance of vehicle safety supporting system has been highlighted as autonomous driving and platooning has attracted the researchers.To ensure driving safety,each vehicle must broadcast a basic safety m...Recently,the importance of vehicle safety supporting system has been highlighted as autonomous driving and platooning has attracted the researchers.To ensure driving safety,each vehicle must broadcast a basic safety message(BSM)every 100 ms.However,stable BSM exchange is difficult because of the changing environment and limited bandwidth of vehicular wireless communication.The increasing number of vehicles on the road increases the competition to access wireless networks for BSM exchange;this increases the packet collision rate.An increased packet collision rate impairs the transmission and reception of BSM information,which can easily cause a traffic accident.We propose a solution,the vehicular safety support system(V3S),which exchanges BSMs reliably even when many vehicles are on the road.The V3S uses a clustering scheme to decrease network traffic by reducing the amount of data exchanged between a vehicle and the roadside unit(RSU).In addition,the V3S reduces the collision rate of wireless network packets by broadcasting the vehicle’s BSM in an allocated timeslot using the time division multiple access(TDMA)MAC protocol.The V3S also deals with insufficient bandwidth for dedicated short-range communications(DSRC)by changing DSRC channels according to traffic flow.In evaluating the packet error rate for stable BSM packet delivery,the V3S demonstrates an excellent packet error rate of less than 1%,compared to the 802.11p with its packet error rate of 82%.展开更多
Instant messaging （IM） has become one of the most popular online communication tools among consumer and enterprise IM users. It provides instant message delivery, as well as convenient file transfer services. The in...Instant messaging （IM） has become one of the most popular online communication tools among consumer and enterprise IM users. It provides instant message delivery, as well as convenient file transfer services. The increasing popularity and functionalities of IM programs have made it increasingly attractive for attackers, especially for worm writers. IM contact list offers worm an easy way of finding potential victims so that the worm could achieve a surprising spreading speed. This paper first presents our experimental results of simulating IM worm propagation in the logical network defined by IM contact lists, which is reported to be a scale-free network. Then, the existing proposals for detecting and containing IM worm epidemics are discussed. At last, a new algorithm for this purpose is presented, which is based on the observation of the bi-directional nature of IM worm traffic, and its advantages and possible improvements in implementation are analyzed. The simulation results show the proposed algorithm is of significant effect on restricting IM worm propagation.展开更多
Orthogonal time frequency space(OTFS)technique,which modulates data symbols in the delay-Doppler(DD)domain,presents a potential solution for supporting reliable information transmission in highmobility vehicular netwo...Orthogonal time frequency space(OTFS)technique,which modulates data symbols in the delay-Doppler(DD)domain,presents a potential solution for supporting reliable information transmission in highmobility vehicular networks.In this paper,we study the issues of DD channel estimation for OTFS in the presence of fractional Doppler.We first propose a channel estimation algorithm with both low complexity and high accuracy based on the unitary approximate message passing(UAMP),which exploits the structured sparsity of the effective DD domain channel using hidden Markov model(HMM).The empirical state evolution(SE)analysis is then leveraged to predict the performance of our proposed algorithm.To refine the hyperparameters in the proposed algorithm,we derive the update criterion for the hyperparameters through the expectation-maximization(EM)algorithm.Finally,Our simulation results demonstrate that our proposed algorithm can achieve a significant gain over various baseline schemes.展开更多
Aiming at the problems of unreliable data transmission,poor steadiness,nonsupport of complex data types,direct couple between data transmission and exchange,a high-level method based on advanced message queuing protoc...Aiming at the problems of unreliable data transmission,poor steadiness,nonsupport of complex data types,direct couple between data transmission and exchange,a high-level method based on advanced message queuing protocol( AMQP) is proposed to integrate naval distributed tactical training simulation system after serious consideration with current information exchange features of military combat system. Transferring layer in traditional user datagram protocol is implemented by publishing and subscribing scheme of message middleware. By creating message model to standardize message structure,integration architecture is formulated to resolve potential information security risks from inconsistent data type and express data transmission. Meanwhile,a communication model is put forward based on AMQP,which is in the center position of the whole transmission framework and responsible for reliably transferring battlefield data among subsystems. Experiments show that the method can accurately post amounts of data to the subscriber without error and loss,and can get excellent real-time performance of data exchange.展开更多
The newly emerging orthogonal time frequency space(OTFS)modulation can ob⁃tain delay-Doppler diversity gain to significantly improve the system performance in high mobility wireless communication scenarios such as veh...The newly emerging orthogonal time frequency space(OTFS)modulation can ob⁃tain delay-Doppler diversity gain to significantly improve the system performance in high mobility wireless communication scenarios such as vehicle-to-everything(V2X),high-speed railway and unmanned aerial vehicles(UAV),by employing inverse symplectic finite Fouri⁃er transform(ISFFT)and symplectic finite Fourier transform(SFFT).However,OTFS modu⁃lation will dramatically increase system complexity,especially at the receiver side.Thus,de⁃signing low complexity OTFS receiver is a key issue for OTFS modulation to be adopted by new-generation wireless communication systems.In this paper,we review low complexity OTFS detectors and provide some insights on future researches.We firstly present the OTFS system model and basic principles,followed by an overview of OTFS detector structures,classifications and comparative discussion.We also survey the principles of OTFS detection algorithms.Furthermore,we discuss the design of hybrid OTFS and orthogonal frequency di⁃vision multiplexing(OFDM)detectors in single user and multi-user multi-waveform commu⁃nication systems.Finally,we address the main challenges in designing low complexity OT⁃FS detectors and identify some future research directions.展开更多
This paper considers a novel polling system with two classes of message which can experience an up-per bounded time before being served. The station serves these two classes with mixed service discipline, one class wi...This paper considers a novel polling system with two classes of message which can experience an up-per bounded time before being served. The station serves these two classes with mixed service discipline, one class with exhaustive service discipline, and the other with gated service discipline. Using iterative method, we have developed an approximation method to obtain the mean waiting time for each message class. The performance of approximation has been compared with the simulation results. The expression for the upper bound of waiting time is given too.展开更多
Timely investigating post-disaster situations to locate survivors and secure hazardous sources is critical,but also very challenging and risky.Despite first responders putting their lives at risk in saving others,huma...Timely investigating post-disaster situations to locate survivors and secure hazardous sources is critical,but also very challenging and risky.Despite first responders putting their lives at risk in saving others,human-physical limits cause delays in response time,resulting in fatality and property damage.In this paper,we proposed and implemented a framework intended for creating collaboration between heterogeneous unmanned vehicles and first responders to make search and rescue operations safer and faster.The framework consists of unmanned aerial vehicles(UAVs),unmanned ground vehicles(UGVs),a cloud-based remote control station(RCS).A light-weight message queuing telemetry transport(MQTT)based communication is adopted for facilitating collaboration between autonomous systems.To effectively work under unfavorable disaster conditions,antenna tracker is developed as a tool to extend network coverage to distant areas,and mobile charging points for the UAVs are also implemented.The proposed framework’s performance is evaluated in terms of end-to-end delay and analyzed using architectural analysis and design language(AADL).Experimental measurements and simulation results show that the adopted communication protocol performs more efficiently than other conventional communication protocols,and the implemented UAV control mechanisms are functioning properly.Several scenarios are implemented to validate the overall effectiveness of the proposed framework and demonstrate possible use cases.展开更多
This paper investigates the fundamental data detection problem with burst interference in massive multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) systems. In particular, burst inte...This paper investigates the fundamental data detection problem with burst interference in massive multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) systems. In particular, burst interference may occur only on data symbols but not on pilot symbols, which means that interference information cannot be premeasured. To cancel the burst interference, we first revisit the uplink multi-user system and develop a matrixform system model, where the covariance pattern and the low-rank property of the interference matrix is discussed. Then, we propose a turbo message passing based burst interference cancellation(TMP-BIC) algorithm to solve the data detection problem, where the constellation information of target data is fully exploited to refine its estimate. Furthermore, in the TMP-BIC algorithm, we design one module to cope with the interference matrix by exploiting its lowrank property. Numerical results demonstrate that the proposed algorithm can effectively mitigate the adverse effects of burst interference and approach the interference-free bound.展开更多
Introduction: Intimate Partner Violence (IPV) is defined as controlling, abusive, and aggressive behavior in a romantic relationship. Women between the ages 16 and 24 experience the highest rate of IPV. IPV costs US s...Introduction: Intimate Partner Violence (IPV) is defined as controlling, abusive, and aggressive behavior in a romantic relationship. Women between the ages 16 and 24 experience the highest rate of IPV. IPV costs US society at least $13.6 billion annually and is expected to rise to $15.6 billion by 2021. The purpose of this study is to explore the feasibility of Text Messaging Intervention (TMI) in recognizing, responding and preventing IPV among college students. The research questions are: Will TMI 1) improve participant knowledge of warning signs of IPV? (Knowledge) and 2) improve participant confidence to intervene in IPV? (Confidence). Methods: A mixed methods design in data collection and data analysis was used. One-way ANOVA and Chi-square test were used to analyze quantitative data from the pre and post TMI survey. Results of the qualitative data analysis are included verbatim. Results: Results showed that knowledge level pre to post test increased from 2.00 ± 1.00 to 2.7 ± 0.48 (p < 0.001) and confidence level pre to post test increased from 2.89 ± 0.60 to 3.30 ± 0.68 (p < 0.001). Conclusions: Further research is needed in evaluating the feasibility and effectiveness of IPV prevention programs that uses mobile devices to create the best optimal health outcomes.展开更多
文摘Nowadays, there has been a rapid increase in the variety and popularity of messaging systems and social networks. It is imperative to consider the effect and impact of the number of words feature on the verification process for modern messaging systems such as Twitter, Facebook, SMS and Email. Given the volume of text is often a restricted factor (due to the nature of messaging systems), key to this investigation is a better understanding of what length of message is required to improve performance. A large historical dataset containing 50 participants, the four datasets containing a large number of messaging system samples (4539 samples for Facebook, 13,616 for Twitter, 6538 for Email and 106,359 for Text message), the best performance was for Text messages, with an EER of 7.6% if the number of words was more than nine;followed by Email with an EER of 14.9% if the number of words was between 25 to 60;then, Twitter tweets, with an EER of 22.5% if the number of words was less than ten. Finally, the Facebook platform with an EER of 31.9% if the number of words was over 11.
基金supported in part by the National Key Research and Development Program of China with Grant number 2021YFB2900502。
文摘In this paper,an index modulation(IM)aided uplink orthogonal time frequency space modulation(OTFS)structure for sparse code multiple access(SCMA)is proposed.To be more specific,the information bits are firstly partitioned for transmit antenna(TA)selection and sparse codeword mapping,respectively.Subsequently,the codewords deployed on the 2-dimensional(2D)delay-Doppler(DD)plane are transmitted by the selected TA,and the superimposed signals are jointly detected at the receiver.Furthermore,a low-complexity zero-embedded expectation propagation(ZE-EP)detector is conceived,where the codebooks are extended with zero vectors to reflect the silent indices.The simulation results demonstrate that the proposed IM-OTFS-SCMA system is capable of providing significant performance gain over the OTFS-SCMA counterpart.
基金the support by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0450101)the National Natural Science Foundation of China(Nos.22325304,22221003 and 22033007)。
文摘Recursively embedded atom neural network(REANN)is a general-purpose atomistic machine learning software package for representing potential energy and other physical properties.The original REANN 1.0 architecture is a physically inspired invariant message passing neural network,which was designed for systems with a limited number of elements.It is efficient but hardly transferable to more complex multi-element systems.In this work,we release REANN 2.0 aimed at multi-element systems and universal potentials,which integrates element embedding and equivariant representation.Compared to the first version,REANN 2.0 demonstrates enhanced ele-ment transferability and higher accuracy across various periodic systems with higher efficiency.Built upon this framework,a pre-trained REANN-MPtrj model without fine-tuning accurately predicts the lithium-ion diffusion dynamics in a benchmark solid-state electrolyte Li_(3)YCl_(6).We hope this open-source software package will facilitate the development of computationally efficient universal potentials in the future.
基金Supported by The Innovation Team in Liaoning Meteorological Technology Service Center
文摘In order to meet the needs of Agricultural Meteorology business and research,an edition system of agricultural meteorology short message was established based on the Microsoft Access 2000 database and visualization developing software Visual Basic 6.0 in Liaoning Province.The basic principles of agro-meteorological text editing and system optimization ideas were pointed out.The meteorological conditions of the main crops growth needed in material library were introduced.
基金Project supported by the Health Promotion Center of Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, China
文摘Objective: To compare the efficacy of a short messaging service (SMS) text messaging and phone reminder to im-prove attendance rates at a health promotion center. Methods: A total of 1 859 participants who had scheduled appointments in the health promotion center of our hospital from April 2007 to May 2007 were enrolled in the study and randomly assigned into 3 groups: control (no reminder) group,SMS text messaging reminder group and telephone reminder group. Attendance rates and costs of interventions were collected. Results: A total of 1848 participants were eligible for analysis. Attendance rates of control,SMS and telephone groups were 80.5%,87.5% and 88.3%,respectively. The attendance rates were significantly higher in SMS and telephone groups than that in the control group,with odds ratio 1.698,95% confidence interval 1.224 to 2.316,P=0.001 in the SMS group,and odds ratio 1.829,95% confidence interval 1.333 to 2.509,P<0.001 in the telephone group. However,there was no difference between the SMS group and the telephone group (P=0.670). The cost effectiveness analysis showed that the cost per attendance for the SMS group (0.31 Yuan) was significantly lower than that for the telephone group (0.48 Yuan). Conclusion: SMS and telephone are effective reminders for improving attendance rate at a health promotion center. SMS reminder may be more cost-effective compared with the telephone reminder.
文摘Aim To design the home -made embedded real time operating system COSIX V2.O/RT developing platform,the Mach operating system interprocess communication mech- anism based on object-oriented technique was analyzed. Methods Not only being the trans-mission channel,but also being the abstract of all the entity in the Mach operating system.ports play the most important role in Mach IPC(interprocess communication).Ports were de-vided into 4 types: system ports, privileged ports user ports and kernel ports.All these ports'creation,run and kill processes and the message transmission in IPC were analyzed.ResultsMach IPC has been widely used in Client/Server run environment.Packing and unpacking inmessage transmission must restrict the run efficiency of IPC Conclusion To enhance IPC runefficiency and at the same time enhance the operating system's run efficiency,some of thesystem calls should be rewritten and implemented with trapped mode in kernel.In the end the aim of designing real time operating system is achieved.
基金by the National Natural Science Foundation of China under Grant Nos 90924011,60973069,10975126,70971089 and 70871082the China Postdoctoral Science Foundation under Grant No 201003694the Sichuan Provincial Science and Technology Department under Grant No 2010HH0002.
文摘Research on human behavior has attracted increasing attention recently because of its scientific significance and potential applications.Some empirical results have indicated that the timing of many human activities follows non-Poisson statistics.We analyze a real-life huge dataset of short message communication with 6326713 users and 37577781 records during the 2006 Chinese New Year.The results show that the number of short message sendings,the interevent time between two consecutive short message sendings and the response time all follow heavy-tailed distribution.We further observe a strongly positive correlation between the activity and the power-law exponent of the interevent time distribution.In addition,the short message communication system displays a bursty property yet no memory effects,which is in particular different from some well-studied human-activited systems such as email-sending,library-loaning and file printing.
文摘In this paper,we propose a joint channel estimation and symbol detection(JCESD)algorithm relying on message-passing algorithms(MPA)for orthogonal frequency division multiple access(OFDMA)systems.The channel estimation and symbol detection leverage the framework of expectation propagation(EP)and belief propagation(BP)with the aid of Gaussian approximation,respectively.Furthermore,to reduce the computation complexity involved in channel estimation,the matrix inversion is transformed into a series of diagonal matrix inversions through the Sherman-Morrison formula.Simulation experiments show that the proposed algorithm can reduce the pilot overhead by about 50%,compared with the traditional linear minimum mean square error(LMMSE)algorithm,and can approach to the bit error rate(BER)performance bound of perfectly known channel state information within 0.1 dB.
基金supported by the Research Fund of National Key Laboratory of Computer Architecture under Grant No.CARCH201501the Open Project Program of the State Key Laboratory of Mathematical Engineering and Advanced Computing under Grant No.2016A09
文摘In the era of Big Data, typical architecture of distributed real-time stream processing systems is the combination of Flume, Kafka, and Storm. As a kind of distributed message system, Kafka has the characteristics of horizontal scalability and high throughput, which is manly deployed in many areas in order to address the problem of speed mismatch between message producers and consumers. When using Kafka, we need to quickly receive data sent by producers. In addition, we need to send data to consumers quickly. Therefore, the performance of Kafka is of critical importance to the performance of the whole stream processing system. In this paper, we propose the improved design of real-time stream processing systems, and focus on improving the Kafka's data loading process.We use Kafka cat to transfer data from the source to Kafka topic directly, which can reduce the network transmission. We also utilize the memory file system to accelerate the process of data loading, which can address the bottleneck and performance problems caused by disk I/O. Extensive experiments are conducted to evaluate the performance, which show the superiority of our improved design.
基金This work was supported in part by the Chung-Ang University Research Grants in 2019,and in part by R&D Program for Forest Science Technology(Project No.“2021338C10-2123-CD02)provided by Korea Forest Service(Korea Forestry Promotion Institute).
文摘Recently,the importance of vehicle safety supporting system has been highlighted as autonomous driving and platooning has attracted the researchers.To ensure driving safety,each vehicle must broadcast a basic safety message(BSM)every 100 ms.However,stable BSM exchange is difficult because of the changing environment and limited bandwidth of vehicular wireless communication.The increasing number of vehicles on the road increases the competition to access wireless networks for BSM exchange;this increases the packet collision rate.An increased packet collision rate impairs the transmission and reception of BSM information,which can easily cause a traffic accident.We propose a solution,the vehicular safety support system(V3S),which exchanges BSMs reliably even when many vehicles are on the road.The V3S uses a clustering scheme to decrease network traffic by reducing the amount of data exchanged between a vehicle and the roadside unit(RSU).In addition,the V3S reduces the collision rate of wireless network packets by broadcasting the vehicle’s BSM in an allocated timeslot using the time division multiple access(TDMA)MAC protocol.The V3S also deals with insufficient bandwidth for dedicated short-range communications(DSRC)by changing DSRC channels according to traffic flow.In evaluating the packet error rate for stable BSM packet delivery,the V3S demonstrates an excellent packet error rate of less than 1%,compared to the 802.11p with its packet error rate of 82%.
基金Supported by the National Natural Science Foundation of China (60573136)
文摘Instant messaging （IM） has become one of the most popular online communication tools among consumer and enterprise IM users. It provides instant message delivery, as well as convenient file transfer services. The increasing popularity and functionalities of IM programs have made it increasingly attractive for attackers, especially for worm writers. IM contact list offers worm an easy way of finding potential victims so that the worm could achieve a surprising spreading speed. This paper first presents our experimental results of simulating IM worm propagation in the logical network defined by IM contact lists, which is reported to be a scale-free network. Then, the existing proposals for detecting and containing IM worm epidemics are discussed. At last, a new algorithm for this purpose is presented, which is based on the observation of the bi-directional nature of IM worm traffic, and its advantages and possible improvements in implementation are analyzed. The simulation results show the proposed algorithm is of significant effect on restricting IM worm propagation.
基金supported by the Key Scientific Research Project in Colleges and Universities of Henan Province of China(Grant Nos.21A510003)Science and the Key Science and Technology Research Project of Henan Province of China(Grant Nos.222102210053).
文摘Orthogonal time frequency space(OTFS)technique,which modulates data symbols in the delay-Doppler(DD)domain,presents a potential solution for supporting reliable information transmission in highmobility vehicular networks.In this paper,we study the issues of DD channel estimation for OTFS in the presence of fractional Doppler.We first propose a channel estimation algorithm with both low complexity and high accuracy based on the unitary approximate message passing(UAMP),which exploits the structured sparsity of the effective DD domain channel using hidden Markov model(HMM).The empirical state evolution(SE)analysis is then leveraged to predict the performance of our proposed algorithm.To refine the hyperparameters in the proposed algorithm,we derive the update criterion for the hyperparameters through the expectation-maximization(EM)algorithm.Finally,Our simulation results demonstrate that our proposed algorithm can achieve a significant gain over various baseline schemes.
基金Supported by the National Natural Science Foundation of China(No.61401496)
文摘Aiming at the problems of unreliable data transmission,poor steadiness,nonsupport of complex data types,direct couple between data transmission and exchange,a high-level method based on advanced message queuing protocol( AMQP) is proposed to integrate naval distributed tactical training simulation system after serious consideration with current information exchange features of military combat system. Transferring layer in traditional user datagram protocol is implemented by publishing and subscribing scheme of message middleware. By creating message model to standardize message structure,integration architecture is formulated to resolve potential information security risks from inconsistent data type and express data transmission. Meanwhile,a communication model is put forward based on AMQP,which is in the center position of the whole transmission framework and responsible for reliably transferring battlefield data among subsystems. Experiments show that the method can accurately post amounts of data to the subscriber without error and loss,and can get excellent real-time performance of data exchange.
基金supported in part by the NSFC Project under Grant No.61871334part by the open research fund of the State Key Laboratory of Integrated Services Networks,Xidian University under Grant No.ISN21-15+1 种基金in part by the Fundamental Research Funds for the Central Universities,SWJTU under Grant No.2682020CX79supported by the NSFC project under Grant No.61731017 and the“111”project under Grant No.111-2-14.
文摘The newly emerging orthogonal time frequency space(OTFS)modulation can ob⁃tain delay-Doppler diversity gain to significantly improve the system performance in high mobility wireless communication scenarios such as vehicle-to-everything(V2X),high-speed railway and unmanned aerial vehicles(UAV),by employing inverse symplectic finite Fouri⁃er transform(ISFFT)and symplectic finite Fourier transform(SFFT).However,OTFS modu⁃lation will dramatically increase system complexity,especially at the receiver side.Thus,de⁃signing low complexity OTFS receiver is a key issue for OTFS modulation to be adopted by new-generation wireless communication systems.In this paper,we review low complexity OTFS detectors and provide some insights on future researches.We firstly present the OTFS system model and basic principles,followed by an overview of OTFS detector structures,classifications and comparative discussion.We also survey the principles of OTFS detection algorithms.Furthermore,we discuss the design of hybrid OTFS and orthogonal frequency di⁃vision multiplexing(OFDM)detectors in single user and multi-user multi-waveform commu⁃nication systems.Finally,we address the main challenges in designing low complexity OT⁃FS detectors and identify some future research directions.
基金Supported by the High Technology Research and Development Program of China（2002AA412010-08） and the National Natural Science Foundation of China（60474031）.
文摘This paper considers a novel polling system with two classes of message which can experience an up-per bounded time before being served. The station serves these two classes with mixed service discipline, one class with exhaustive service discipline, and the other with gated service discipline. Using iterative method, we have developed an approximation method to obtain the mean waiting time for each message class. The performance of approximation has been compared with the simulation results. The expression for the upper bound of waiting time is given too.
基金supported partially by AirForce Research Laboratory,the Office of the Secretary of Defense(OSD)(FA8750-15-2-0116)the National Science Foundation(NSF)(1832110)the National Institute of Aerospace and Langley(C16-2B00-NCAT)。
文摘Timely investigating post-disaster situations to locate survivors and secure hazardous sources is critical,but also very challenging and risky.Despite first responders putting their lives at risk in saving others,human-physical limits cause delays in response time,resulting in fatality and property damage.In this paper,we proposed and implemented a framework intended for creating collaboration between heterogeneous unmanned vehicles and first responders to make search and rescue operations safer and faster.The framework consists of unmanned aerial vehicles(UAVs),unmanned ground vehicles(UGVs),a cloud-based remote control station(RCS).A light-weight message queuing telemetry transport(MQTT)based communication is adopted for facilitating collaboration between autonomous systems.To effectively work under unfavorable disaster conditions,antenna tracker is developed as a tool to extend network coverage to distant areas,and mobile charging points for the UAVs are also implemented.The proposed framework’s performance is evaluated in terms of end-to-end delay and analyzed using architectural analysis and design language(AADL).Experimental measurements and simulation results show that the adopted communication protocol performs more efficiently than other conventional communication protocols,and the implemented UAV control mechanisms are functioning properly.Several scenarios are implemented to validate the overall effectiveness of the proposed framework and demonstrate possible use cases.
基金supported by the National Key Laboratory of Wireless Communications Foundation,China (IFN20230204)。
文摘This paper investigates the fundamental data detection problem with burst interference in massive multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) systems. In particular, burst interference may occur only on data symbols but not on pilot symbols, which means that interference information cannot be premeasured. To cancel the burst interference, we first revisit the uplink multi-user system and develop a matrixform system model, where the covariance pattern and the low-rank property of the interference matrix is discussed. Then, we propose a turbo message passing based burst interference cancellation(TMP-BIC) algorithm to solve the data detection problem, where the constellation information of target data is fully exploited to refine its estimate. Furthermore, in the TMP-BIC algorithm, we design one module to cope with the interference matrix by exploiting its lowrank property. Numerical results demonstrate that the proposed algorithm can effectively mitigate the adverse effects of burst interference and approach the interference-free bound.
文摘Introduction: Intimate Partner Violence (IPV) is defined as controlling, abusive, and aggressive behavior in a romantic relationship. Women between the ages 16 and 24 experience the highest rate of IPV. IPV costs US society at least $13.6 billion annually and is expected to rise to $15.6 billion by 2021. The purpose of this study is to explore the feasibility of Text Messaging Intervention (TMI) in recognizing, responding and preventing IPV among college students. The research questions are: Will TMI 1) improve participant knowledge of warning signs of IPV? (Knowledge) and 2) improve participant confidence to intervene in IPV? (Confidence). Methods: A mixed methods design in data collection and data analysis was used. One-way ANOVA and Chi-square test were used to analyze quantitative data from the pre and post TMI survey. Results of the qualitative data analysis are included verbatim. Results: Results showed that knowledge level pre to post test increased from 2.00 ± 1.00 to 2.7 ± 0.48 (p < 0.001) and confidence level pre to post test increased from 2.89 ± 0.60 to 3.30 ± 0.68 (p < 0.001). Conclusions: Further research is needed in evaluating the feasibility and effectiveness of IPV prevention programs that uses mobile devices to create the best optimal health outcomes.
