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Development of diabetic complications and influencing factors among 32653 type 2 diabetes patients:retrospective cohort study using a multi-state Markov
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作者 Shu-Yuan Shi Hou-Yu Zhao +5 位作者 Zhi-Ke Liu Ruo-Gu Meng Peng Shen Si-Yan Zhan Hong-Bo Lin Feng Sun 《Medical Data Mining》 2024年第2期1-8,共8页
Background:Patients with type 2 diabetes are at high risk for developing multiple chronic complications.However,there is a lack of studies of the cumulative number of diabetic complications in China.Methods:A retrospe... Background:Patients with type 2 diabetes are at high risk for developing multiple chronic complications.However,there is a lack of studies of the cumulative number of diabetic complications in China.Methods:A retrospective cohort study was performed from 2009 to 2021.Type 2 diabetes patients who were first diagnosed after the age of 35 years between January 1,2009,and December 31,2017,were included.Five states were defined according to the number of chronic complications:no(S0),one(S1),two(S2),three(S3),and four or more complications(S4).A multi-state Markov model was constructed to estimate transition probability,transition intensity,mean sojourn time,and the possible factors for each state.Results:The study included 32653 type 2 diabetes patients(mean age,59.59 years;15929(48.8%)male),and mean follow-up time of 7.75 years.In all,4375 transitions were observed.The 12-year transition probability of from state S0 to S1 was the lowest at 16.4%,while that from S2 to S3 was the highest,at 45.6%.Higher fasting blood glucose,lower high-density lipoprotein cholesterol,higher total cholesterol,and an unhealthy diet were associated with higher risk of progression from S0 to S1.Being female,less than 60 years old,weekly physical activity,and vegetarian diet decreased this risk.Being female and less than 60 years old reduced the likelihood of transition from S1 to S2,whereas lower high-density lipoprotein cholesterol increased this likelihood.Conclusions:Following the occurrence of two complications in type 2 diabetes patients,the risk for accumulating a third complication within a short time is significantly increased.It is important to take advantage of the stable window period when patients have fewer than two complications,strengthen the monitoring of blood glucose and blood lipids,and encourage patients to maintain good living habits to prevent further deterioration. 展开更多
关键词 multi-state Markov model transition probability type 2 diabetes diabetic chronic complications
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CORBA异步Polling模型的研究与实现
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作者 张志伟 杨玉清 +1 位作者 杨大强 吴泉源 《计算机工程》 CAS CSCD 北大核心 2004年第7期6-7,110,共3页
基于CORBA异步消息中的抽象Polling模型提出了一种Polling模型实现方案,讨论了其中的核心算法,该算法能分解耦合请求和应答并确保at-most-once语义。在分布对象中间件平台StarBus上实现了该模型和算法,实现结果表明该模型和算法为在C... 基于CORBA异步消息中的抽象Polling模型提出了一种Polling模型实现方案,讨论了其中的核心算法,该算法能分解耦合请求和应答并确保at-most-once语义。在分布对象中间件平台StarBus上实现了该模型和算法,实现结果表明该模型和算法为在CORBA中实现异步Polling机制提供了一种有效的参考方案。 展开更多
关键词 分布对象中间件 异步机制 polling模型
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优化的EPON前摄Polling机制 被引量:1
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作者 张晋豫 黄成富 +1 位作者 王众 梁满贵 《北京邮电大学学报》 EI CAS CSCD 北大核心 2008年第5期61-64,共4页
利用由多个关键报告生成的插值多项式预测方程来预测未来几个周期的业务量,通过1个消息(grant)对多个周期的授权,节省了带宽和减少了数据包的时延,建立了知识支撑系统(KSS)系统,通过偏导(DC)寻优法来优化关键周期和预测周期的个数,通过... 利用由多个关键报告生成的插值多项式预测方程来预测未来几个周期的业务量,通过1个消息(grant)对多个周期的授权,节省了带宽和减少了数据包的时延,建立了知识支撑系统(KSS)系统,通过偏导(DC)寻优法来优化关键周期和预测周期的个数,通过神经网络来优化非线形预测方程的调节因子.仿真结果很好地验证了它的效果. 展开更多
关键词 以太无源光网络 神经网络 轮巡 优化
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Polling规约的远动实时数据的接收
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作者 梁京章 苏东伟 《软件》 北大核心 1996年第10期38-41,45,共5页
在电力系统MIS开发建设中,远动实时信息经加工后进入管理信息网是一项基本功能要求。实时信息进入管理信息网,首先要解决如何从远动系统接收数据的问题。本文结合“广西西津电厂远动实时信息网络监视系统”的开发,介绍如何实现Polling... 在电力系统MIS开发建设中,远动实时信息经加工后进入管理信息网是一项基本功能要求。实时信息进入管理信息网,首先要解决如何从远动系统接收数据的问题。本文结合“广西西津电厂远动实时信息网络监视系统”的开发,介绍如何实现Polling规约远动实时信息的接收问题。 展开更多
关键词 电力系统 polling规约 数据接收 实时数据
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基于POLLING方式的分布式监控系统
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作者 贾智平 《计算机工程与应用》 CSCD 北大核心 1997年第3期61-63,69,共4页
本文介绍了一个用于自来水生产行业的分布式微机监控系统,给出了由8098单片机组成的有线及无线混合通信网络方案。并结合8098的特点,推出了一个抗干扰能力强、码效率高。
关键词 自来水 监控系统 polling 分布式
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PERFORMANCE ANALYSIS OF POLLING SYSTEMS WITH LIMITED SERVICE 被引量:12
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作者 Zhao Dongfeng Li Bihai Zheng Sumin(Department of Information and Electronic Science, Yunnan University, Kunming 650091) 《Journal of Electronics(China)》 1998年第1期43-49,共7页
This paper analyzes a queue mode] of the polling system with limited service (K=1) in discrete time. By the imbedded Markov chain theory and the probability generating function method, the mean values of queue length ... This paper analyzes a queue mode] of the polling system with limited service (K=1) in discrete time. By the imbedded Markov chain theory and the probability generating function method, the mean values of queue length and message waiting time are explicitly obtained. Also, we give the simulation results. The results obtained by H. Tagai (1985) are revised. 展开更多
关键词 polling system LIMITED SERVICE DISCRETE TIME
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A DISCRETE TIME TWO-LEVEL MIXED SERVICE PARALLEL POLLING MODEL 被引量:6
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作者 GuanZheng ZhaoDongfeng ZhaoYifan 《Journal of Electronics(China)》 2012年第1期103-110,共8页
We present a discrete time single-server two-level mixed service polling systems with two queue types, one center queue and N normal queues. Two-level means the center queue will be successive served after each normal... We present a discrete time single-server two-level mixed service polling systems with two queue types, one center queue and N normal queues. Two-level means the center queue will be successive served after each normal queue. In the first level, server visits between the center queue and the normal queue. In the second level, normal queues are polled by a cyclic order. Mixed service means the service discipline are exhaustive for center queue, and parallel 1-limited for normal queues. We propose an imbedded Markov chain framework to drive the closed-form expressions for the mean cycle time, mean queue length, and mean waiting time. Numerical examples demonstrate that theoretical and simulation results are identical the new system efficiently differentiates priorities. 展开更多
关键词 polling model PRIORITY TWO-LEVEL Mixed-service Waiting time
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Dynamic Polling MAC Scheme Considering Emergency Access in WSNs Based on Priorities 被引量:3
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作者 Pei Qingqi Chen Chen Xie Weiguang 《China Communications》 SCIE CSCD 2012年第4期45-54,共10页
In Wireless Sensor Networks(WSNs),polling can obviously improve the throughput and decrease average access delay by allocating bandwidth efficiently and reasonably.In this paper,a Dynamic Polling Media Access Control ... In Wireless Sensor Networks(WSNs),polling can obviously improve the throughput and decrease average access delay by allocating bandwidth efficiently and reasonably.In this paper,a Dynamic Polling Media Access Control (DPMAC) scheme designed according to WSNs' features is proposed.DPMAC is a priority based access control protocol with the characteristics that its polling table is dynamically refreshed depending on whether the sensor node is active and that the bandwidth is dynamically allocated according to the traffic types.The access priorities are determined by the emergency levels of events and the scheduler proposed in our MAC is preemptive based on the deadline of the events.Simulation results show that DPMAC can efficiently utilize bandwidth and decrease average access delay and response time for emergency events with different access priorities in WSNs. 展开更多
关键词 无线传感器网络 优先级 MAC 轮询 媒体访问控制 接入控制协议 突发事件 访问延迟
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Achieving Energy Efficiency in Wireless Sensor Networks Using Dynamic Channel Polling and Packet Concatenation 被引量:1
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作者 Shama Siddiqui Anwar Ahmed Khan Sayeed Ghani 《China Communications》 SCIE CSCD 2021年第8期249-270,共22页
There has been a significant interest of researchers to combine different schemes focused on optimizing energy performance while developing aMAC protocol for Wireless Sensor Networks(WSNs).In this paper,we propose to ... There has been a significant interest of researchers to combine different schemes focused on optimizing energy performance while developing aMAC protocol for Wireless Sensor Networks(WSNs).In this paper,we propose to integrate two cross-layer schemes:dynamic channel polling and packet concatenation using a recent asynchronous MAC protocol“Adaptive&Dynamic Polling MAC”(ADPMAC).ADP-MAC dynamically selects the polling interval distribution based on characterization of incoming traffic patterns using Coefficient of variation(CV).Packet Concatenation(PC)refers to combining the individually generated data packets into a single super packet and sending it at the polling instant.Also,the Block Acknowledgement(BA)scheme has been developed for ADP-MAC to work in conjunction with the packet concatenation.The proposed schemes have been implemented in Tiny-OS for Mica2 platform and Avrora emulator has been used for conducting experiments.Simulation results have revealed that the performance both in terms of energy&packet loss improves when ADP-MAC is used in conjunction with the additional features of PC&BA.Furthermore,the proposed scheme has been compared with a stateof-art packet concatenation primitive PiP(Packet-in-Packet).It has been observed that ADP-MAC supersedes the performance of PiP in terms of PDR(Packet Delivery Ratio)due to better management of synchronization between source and sink. 展开更多
关键词 energy efficiency CONCATENATION DYNAMIC polling
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A Priority-aware Frequency Domain Polling MAC Protocol for OFDMA-based Networks in Cyber-physical Systems 被引量:1
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作者 Meng Zheng Junru Lin +1 位作者 Wei Liang Haibin Yu 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI 2015年第4期412-421,共10页
Wireless networking in cyber-physical systems(CPSs) is characteristically different from traditional wireless systems due to the harsh radio frequency environment and applications that impose high real-time and reliab... Wireless networking in cyber-physical systems(CPSs) is characteristically different from traditional wireless systems due to the harsh radio frequency environment and applications that impose high real-time and reliability constraints.One of the fundamental considerations for enabling CPS networks is the medium access control protocol. To this end, this paper proposes a novel priority-aware frequency domain polling medium access control(MAC) protocol, which takes advantage of an orthogonal frequency-division multiple access(OFDMA)physical layer to achieve instantaneous priority-aware polling.Based on the polling result, the proposed work then optimizes the resource allocation of the OFDMA network to further improve the data reliability. Due to the non-polynomial-complete nature of the OFDMA resource allocation, we propose two heuristic rules,based on which an efficient solution algorithm to the OFDMA resource allocation problem is designed. Simulation results show that the reliability performance of CPS networks is significantly improved because of this work. 展开更多
关键词 Cyber-physical system(CPS) medium access control(MAC) protocol polling resource allocation
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A PRIORITY-BASED POLLING SCHEDULING ALGORITHM FOR ARBITRATION POLICY IN NETWORK ON CHIP 被引量:1
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作者 Bao Liyong Zhao Dongfeng Zhao Yifan 《Journal of Electronics(China)》 2012年第1期120-127,共8页
A solution is imperatively expected to meet the efficient contention resolution schemes for managing simultaneous access requests to the communication resources on the Network on Chip (NoC). Based on the ideas of conf... A solution is imperatively expected to meet the efficient contention resolution schemes for managing simultaneous access requests to the communication resources on the Network on Chip (NoC). Based on the ideas of conflict-free transmission, priority-based service, and dynamic self-adaptation to loading, this paper presents a novel scheduling algorithm for Medium Access Control (MAC) in NoC with the researches of the communication structure features of 2D mesh. The algorithm gives priority to guarantee the Quality of Service (QoS) for local input port as well as dynamic adjustment of the performance of the other ports along with input load change. The theoretical model of this algorithm is established with Markov chain and probability generating function. Mathematical analysis is made on the mean queue length and the mean inquiry cyclic time of the system. Simulated experiments are conducted to test the accuracy of the model. It turns out that the findings from theoretical analysis correspond well with those from simulated experiments. Further more, the analytical findings of the system performance demonstrate that the algorithm enables effectively strengthen the fairness and stability of data transmissions in NoC. 展开更多
关键词 Network on Chip(NoC) Arbitration policies Priority-based polling Dynamic load adaptation
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Semi-polling based interrupt mitigation for high performance packet processing 被引量:1
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作者 Tian Zhihong(田志宏) Hu Mingzeng Li Bin 《High Technology Letters》 EI CAS 2005年第3期306-309,共4页
Interrupt-driven systems can be collapsed due to frequent NIC interrupts under heavy network traffic. To mitigate this problem, a high-performance communication mechanism SBIM based on real-time OS RTLinux is designed... Interrupt-driven systems can be collapsed due to frequent NIC interrupts under heavy network traffic. To mitigate this problem, a high-performance communication mechanism SBIM based on real-time OS RTLinux is designed and implemented. A new concept of semi-polling is presented. With state-based semi-polling mechanism and lightweight buffering algorithm, interrupt frequency is reduced and the performance for short packet is significantly ameliorated. The experimental results indicate that the throughputs of SBIM for 64byte and 1500byte packets are 394Mbps and 895Mbps in Gigabit Ethernet environments, which show that the performance of SBIM surpasses that of other mechanisms. 展开更多
关键词 中断驱动系统 网络交换 振动算法 潜伏性 交换容量
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Study of Asymmetric Polling System with Two Message Classes
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作者 曹春生 张卫东 《Journal of Beijing Institute of Technology》 EI CAS 2007年第2期182-186,共5页
A novel mixed polling system with multiple stations is considered. Each station produces two classes of messages served with different disciplines. The real time message served with exhaustive service discipline and t... A novel mixed polling system with multiple stations is considered. Each station produces two classes of messages served with different disciplines. The real time message served with exhaustive service discipline and the unreal time message served with gated service discipline. Using an iterative method, the exact mean waiting times for both message classes are derived. The influence of the gate location of the message class served by the gated service discipline on the mean waiting time is also analyzed. The analytical results are verified with simulation method and agree well with simulation results. 展开更多
关键词 mean waiting time message class gate location polling system
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Improved Radio Network Dimensioning for Real-Time Polling Service on IEEE 802.16 Wireless Networks with QoS Consideration
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作者 Thiaw Seng Ng Teong Chee Chuah Yi Fei Tan 《International Journal of Communications, Network and System Sciences》 2012年第3期192-205,共14页
Recently, applications of real-time polling service (rtPS) in IEEE 802.16 wireless networks have gained considerable popularity. These applications generate large amounts of real time traffic in the network and thus m... Recently, applications of real-time polling service (rtPS) in IEEE 802.16 wireless networks have gained considerable popularity. These applications generate large amounts of real time traffic in the network and thus maintaining the quality of service (QoS) such as packet delay requirement in rtPS dominant networks is critical. Existing dimensioning methodology does not consider QoS parameters of rtPS in network dimensioning. Moreover, exhaustive and time-consuming simulations are required to evaluate the performance and QoS of rtPS. To overcome this problem, we propose an improved radio network dimensioning framework which considers QoS parameters of rtPS in network dimensioning. In this framework, an analytical model is developed to evaluate the capacity and performance of rtPS in IEEE 802.16 wireless networks. The proposed framework provides a fast and accurate means of finding the trade-off between system load and packet delay, thus providing network operators with an analytical tool that jointly considers coverage, capacity and QoS requirements for obtaining the minimum number of sites required. The accuracy of the proposed model is validated through simulations. 展开更多
关键词 IEEE802.16 DIMENSIONING Analytical Model Real Time polling SERVICE QOS
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POLLING远动规约中CRC校验码的算法及程序实现
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作者 骆昌军 盛翊智 付海帆 《电脑与信息技术》 1994年第3期2-4,共3页
电力系统中广泛应用的POLLING运动规约,使用了国际标准化组织ISO制定的HDLC标准CRC校验码.本文具体介绍了CRC校验码的计算方法,并从软件工程的角度详细介绍了算法及其程序设计,此程序已成功地应用于N4F与本地功能计算机的数据通讯.
关键词 电力系统 polling规约 CRC校验码 算法 程序设计
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Synthesized Multi-station Tribo-test System for Bio-tribological Evaluation in Vitro
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作者 WU Tonghai DU Ying +2 位作者 LI Yang WANG Shuo ZHANG Zhinan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第4期853-861,共9页
Tribological tests play an important role on the evaluation of long-term bio-tribological performances of prosthetic materials for commercial fabrication.Those tests focus on the motion simulation of a real joint in v... Tribological tests play an important role on the evaluation of long-term bio-tribological performances of prosthetic materials for commercial fabrication.Those tests focus on the motion simulation of a real joint in vitro with only normal loads and constant velocities,which are far from the real friction behavior of human joints characterized with variable loads and multiple directions.In order to accurately obtain the bio-tribological performances of artificial joint materials,a tribological tester with a miniature four-station tribological system is proposed with four distinctive features.Firstly,comparability and repeatability of a test are ensured by four equal stations of the tester.Secondly,cross-linked scratch between tribo-pairs of human joints can be simulated by using a gear-rack meshing mechanism to produce composite motions.With this mechanism,the friction tracks can be designed by varying reciprocating and rotating speeds.Thirdly,variable loading system is realized by using a ball-screw mechanism driven by a stepper motor,by which loads under different gaits during walking are simulated.Fourthly,dynamic friction force and normal load can be measured simultaneously.The verifications of the performances of the developed tester show that the variable frictional tracks can produce different wear debris compared with one-directional tracks,and the accuracy of loading and friction force is within ?5%.Thus the high consistency among different stations can be obtained.Practically,the proposed tester system could provide more comprehensive and accurate bio-tribological evaluations for prosthetic materials. 展开更多
关键词 artificial joint multi-station tribological tester bio-tribology testing system
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Adaptive Polling Rate for SNMP for Detecting Elusive DDOS
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作者 Yichiet Aun Yen-Min Jasmina Khaw +1 位作者 Ming-Lee Gan Vasaki Ponnusamy 《Journal of Cyber Security》 2022年第1期17-28,共12页
Resilient network infrastructure is pivotal for business entities that are growing reliance on the Internet.Distributed Denial-of-Service(DDOS)is a common network threat that collectively overwhelms and exhausts netwo... Resilient network infrastructure is pivotal for business entities that are growing reliance on the Internet.Distributed Denial-of-Service(DDOS)is a common network threat that collectively overwhelms and exhausts network resources using coordinated botnets to interrupt access to network services,devices,and resources.IDS is typically deployed to detect DDOS based on Snort rules.Although being fairly accurate,IDS operates on a computeintensive packet inspection technique and lacks rapidDDOSdetection.Meanwhile,SNMP is a comparably lightweight countermeasure for fast detection.However,this SNMP trigger is often circumvented if the DDOS burst rate is coordinated to flood the network smaller than theSNMPpolling rate.Besides,SNMP does not scale well if the poll rate is set extremely fine for improved detection accuracy.In this paper,a lightweight 3D SNMP scaling method is proposed to optimize the SNMP poll rate forDDOSmitigation automatically.The 3D-SNMP uses horizontal scaling to dynamically adjust the optimal poll rate through random packet inspection that is selective.Suppose a sign of DDOS is detected,3D-SNMP scales down the poll rate for finer detection.As DDOS subsides,3D-SNMP scales the poll rate up for faster DDOS detection.The equilibrium between scalability and accuracy is determined on the fly depending on the types of DDOS variants.3D-SNMP also adds a vertical scaling to detect non-salient DDOS that falls below the detection threshold.The experimental results showed that 3D-SNMP achieved DDOS detection of 92%while remaining scalable to different DDOS variants and volumes. 展开更多
关键词 SNMP DDOS poll rate network security threat detection
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POLLING方式RTU装置接入SCADA系统的技术研究
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作者 董长玲 李杰 《吉林电力》 1994年第5期1-4,13,共5页
论述了POLLING方式RTU接入国内开发的SCADA系统的技术原理、方法及结构配置、功能。并通过省调SCADA系统接收μ4F、N4F型RTU的实例,较详细地介绍了POLLING方式RTU严格按部颁通讯规约接入SCADA系统的程序设计流程、主要程序模块及各程序... 论述了POLLING方式RTU接入国内开发的SCADA系统的技术原理、方法及结构配置、功能。并通过省调SCADA系统接收μ4F、N4F型RTU的实例,较详细地介绍了POLLING方式RTU严格按部颁通讯规约接入SCADA系统的程序设计流程、主要程序模块及各程序包的功能和使用说明。 展开更多
关键词 调度自动化 SCADA polling RTU 程序设计
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Controllers Design for the Multi-Shuttle and Multi-Station Transportation System
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作者 Tien Dong Ha Minh Tien Trinh +1 位作者 Tran Thanh Cong Vu Tuong Quan Vo 《Open Journal of Applied Sciences》 2021年第8期946-965,共20页
Nowadays, the Multi-Shuttle and Multi-Station Transportation System (MMTS)<span><span><span style="font-family:;" "=""> is one of the most interesting research topics in many... Nowadays, the Multi-Shuttle and Multi-Station Transportation System (MMTS)<span><span><span style="font-family:;" "=""> is one of the most interesting research topics in many fields of industries. It is an effective solution to reduce unexpected accidents that occur during transportation as well as increase productivity in manufacturing. The aim of this paper is to introduce the controller design for the MMTS which is built in our BK-Recme BioMech Lab at Ho Chi Minh City University of Technology (VNU-HCM), Viet Nam. Based on the design of this system, the control algorithms will be conducted to check the operation of the whole system. To evaluate the feasibility and effectiveness of this model, we design a series of random instances for different quantities of nodes as well as the different quantities of shuttles. Our system includes 4 stations and 6 shuttles which are assembled in the serial chain system. However, the number of stations and number of shuttles can be expanded to any desired ones which are based on the requirement of the industries. In this paper, we mainly focus on the controller design of this system to make it operate in an effective way that the goods will be transported and delivered to the target station as fast as possible. In order to solve the large</span></span></span><span><span><span style="font-family:;" "="">-</span></span></span><span><span><span style="font-family:;" "="">scale instances and realistic transport prob<span>lems, we propose three algorithms for three progresses as shuttles calling</span>, path reading and shuttles communicating. The shuttles calling is to decide which <span>shuttle should be called to the star</span></span></span></span><span><span><span style="font-family:;" "="">t</span></span></span><span><span><span style="font-family:;" "="">-node. Path reading to determine the shortest</span></span></span><span><span><span style="font-family:;" "=""> <span>way to go from start-node to end-node. Finally, shuttles communicating,</span> which allow one shuttle to interact with the next shuttles so we have a loop of orders (shuttle 1 to shuttle 2;shuttle 2 to shuttle 3;etc</span></span></span><span><span><span style="font-family:;" "="">.</span></span></span><span><span><span style="font-family:;" "="">;shuttle n-1 to shuttle n). This proposes solution can help us to solve the huge numbers of shuttles <span>and stations in the system. The specific result of this study is applying</span> Dijkstra’s algorithm to propose an algorithm that allows handling a transportation system without caring about the number of shuttles as well as the number of stations for the closed-loop path. Several test problems are carried out in order to check the feasibility and the effectiveness of our purposed control algorithm.</span></span></span> 展开更多
关键词 multi-station Multi-Shuttle Transportation SHUTTLE CALLING RFID COMMUNICATING Start-Node End-Node
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A Two-Step Algorithm to Estimate Variable Importance for Multi-State Data:An Application to COVID-19
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作者 Behnaz Alafchi Leili Tapak +2 位作者 Hassan Doosti Christophe Chesneau Ghodratollah Roshanaei 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第6期2047-2064,共18页
Survival data with amulti-state structure are frequently observed in follow-up studies.An analytic approach based on a multi-state model(MSM)should be used in longitudinal health studies in which a patient experiences... Survival data with amulti-state structure are frequently observed in follow-up studies.An analytic approach based on a multi-state model(MSM)should be used in longitudinal health studies in which a patient experiences a sequence of clinical progression events.One main objective in the MSM framework is variable selection,where attempts are made to identify the risk factors associated with the transition hazard rates or probabilities of disease progression.The usual variable selection methods,including stepwise and penalized methods,do not provide information about the importance of variables.In this context,we present a two-step algorithm to evaluate the importance of variables formulti-state data.Three differentmachine learning approaches(randomforest,gradient boosting,and neural network)as themost widely usedmethods are considered to estimate the variable importance in order to identify the factors affecting disease progression and rank these factors according to their importance.The performance of our proposed methods is validated by simulation and applied to the COVID-19 data set.The results revealed that the proposed two-stage method has promising performance for estimating variable importance. 展开更多
关键词 multi-state data deviance residual martingale residual gradient boosting randomforest neural network variable importance variable selection
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