为了减少用户接通客服热线电话的等待时间,同时控制企业在客服热线方面的投入成本,结合用户行为,基于企业数据,采用连续时间马尔可夫链(continuous time Markov chain,CTMC)的数学模型对企业热线话务进行信道预测分析,寻求影响信道需求...为了减少用户接通客服热线电话的等待时间,同时控制企业在客服热线方面的投入成本,结合用户行为,基于企业数据,采用连续时间马尔可夫链(continuous time Markov chain,CTMC)的数学模型对企业热线话务进行信道预测分析,寻求影响信道需求的相关参数。对不同规模企业的话务进行仿真,比对在不同客户量、不同通话保持时间需求、不同通话频率条件下的成功通话率、阻塞通话率及系统占线率,实现一种企业客服热线信道最佳资源配置的预测模型。展开更多
针对并行密度聚类算法在处理大数据集时存在伸缩困难、参数寻优能力不佳、并行化效率较低等问题,提出一种基于分组和重力搜索优化算法(improve gravitational search algorithm,IGSA)的并行密度聚类算法(density-based clustering algor...针对并行密度聚类算法在处理大数据集时存在伸缩困难、参数寻优能力不佳、并行化效率较低等问题,提出一种基于分组和重力搜索优化算法(improve gravitational search algorithm,IGSA)的并行密度聚类算法(density-based clustering algorithm based on groups and improve gravitational search,MR-GDBIGS)。首先,该算法设计了基于图形的分组策略(grouping strategy based on pattern,GSP)来有效划分数据,加速邻域搜索,解决了处理大数据集时伸缩困难的问题;其次,在局部聚类中提出基于位置更新函数(position update function,PUF)的重力搜索优化算法,动态寻找局部聚类中的最优参数,提升了局部聚类的效果;最后,提出基于覆盖树的并行局部簇合并策略(cluster merging strategy by using MapReduce,MR-CTMC),在实现局部簇并行化合并的同时加快了合并局部簇的收敛速度,提升了算法整体的并行化效率。实验结果表明,MR-GDBIGS算法在处理大数据时的聚类效果更佳,且并行化性能更好。展开更多
为了将故障预测与健康管理(prognostics and health management,PHM)技术应用到工程实践中,提出了基于可用度模型的PHM方法。首先通过广义随机Petri网(generalized stochastic Petri nets,GSPN)和连续马尔科夫链(continuous time Markov...为了将故障预测与健康管理(prognostics and health management,PHM)技术应用到工程实践中,提出了基于可用度模型的PHM方法。首先通过广义随机Petri网(generalized stochastic Petri nets,GSPN)和连续马尔科夫链(continuous time Markov chain,CTMC)建立基本单元的软硬件可用度模型和健康状态转换图,通过求解微分方程得到基本单元软硬件的可用度数值。然后综合软硬件之间的故障相关性建立基本单元的完整可用度模型,并利用事件调度仿真机制得到其可用度的解。最后将基本单元故障模型同通用的可修系统稳态可用度模型对比,得到"可用度-故障率-维修率"形式的PHM计算模型,并以此作为工程应用中PHM分析的有效手段。展开更多
AIM: To study the developmental regularities and heterogeneity of mast cells (MC) in human fetus duodenum and the distribution and developmental regularities of substance P(SP), calcitonin gene-related peptide (CGRP)-...AIM: To study the developmental regularities and heterogeneity of mast cells (MC) in human fetus duodenum and the distribution and developmental regularities of substance P(SP), calcitonin gene-related peptide (CGRP)-immunoreactive (IR) peptidergic nerves in fetus duodenum, as well as the relationship between MC, SP and CGRP-IR peptidergic nerves. METHODS: Duodena from 21 cases of human fetus and one term infant were stained by hematoxylin-eosin (HE), toluidine blue (TB) and immunohistochemical avidin-biotinylated peroxidase complex (ABC) method. RESULTS: Lobe-shape intestinal villi in duodenum were already developed at the twelfth week. At the 21st wk, muscular mucosa appeared gradually, and four layers were observed in the wall of duodenum. TB staining showed that the granules in the immature MC were pale violet, while the mature MC were strong violet in color by TB staining. Connective tissue MC (CTMC) appeared occasionally in submucosa and muscular layer of duodenum at the 16th wk. While the mucosa MC (MMC) appeared at the 18th wk. At the 22nd wk, both CTMC and MMC were activated, and distributed in the surrounding blood vessels and ganglions. The verge of some MC were unclear, and showed degranular phenomena. At the 14th wk, SP and CGRP-IR nerve fibers and cells appeared in the myenteric and submucous plexuses in small intestine, and the responses were turn strongly. Neurons were light to deep brown, and nerve fibers were present as varicose and liner profiles. On the corresponding site of serial sections, SP and CGRP immunohistochemical reactions were coexisted in one nerve fiber or cell. Some of MC showed SP and CGRP-IR positive staining. CONCLUSION: There are two heterogeneous kinds of MC in duodenum, MMC and CTMC. MC might play an important role in regulating blood circulation and sensation.展开更多
Dynamically reconfigurable Field Programmable Gate Array(dr-FPGA) based electronic systems on board mission-critical systems are highly susceptible to radiation induced hazards that may lead to faults in the logic or ...Dynamically reconfigurable Field Programmable Gate Array(dr-FPGA) based electronic systems on board mission-critical systems are highly susceptible to radiation induced hazards that may lead to faults in the logic or in the configuration memory. The aim of our research is to characterize self-test and repair processes in Fault Tolerant(FT) dr-FPGA systems in the presence of environmental faults and explore their interrelationships. We develop a Continuous Time Markov Chain(CTMC) model that captures the high level fail-repair processes on a dr-FPGA with periodic online Built-In Self-Test(BIST) and scrubbing to detect and repair faults with minimum latency. Simulation results reveal that given an average fault interval of 36 s, an optimum self-test interval of 48.3 s drives the system to spend 13% of its time in self-tests, remain in safe working states for 76% of its time and face risky fault-prone states for only 7% of its time. Further, we demonstrate that a well-tuned repair strategy boosts overall system availability, minimizes the occurrence of unsafe states, and accommodates a larger range of fault rates within which the system availability remains stable within 10% of its maximum level.展开更多
We consider a carrier sense multiple access (CSMA) in an unslotted cognitive radio network with random residence time. In this system, if an arriving secondary user (SU) does not find any idle channels, then the SU ei...We consider a carrier sense multiple access (CSMA) in an unslotted cognitive radio network with random residence time. In this system, if an arriving secondary user (SU) does not find any idle channels, then the SU either enters the back-off group or gives up its service and leaves the system. SUs in the back-off group have random mobility, so may re-access the channel after random time or go to the other network after random residence time. We model the system by 3-demensional Continuous Time Markov Chain (CTMC) and obtain the steady state probability of the system by matrix analytic method. In numerical results, we compare the performance of two systems with and without residence time of SUs. It is shown that the random mobility of SUs has an impact on the performance of SUs in cognitive radio networks.展开更多
As a payload support system deployed on satellites,the turntable system is often switched among different working modes during the on-orbit operation,which can experience great state changes.In each mode,the missions ...As a payload support system deployed on satellites,the turntable system is often switched among different working modes during the on-orbit operation,which can experience great state changes.In each mode,the missions to be completed are different,consecutive and non-over-lapping,from which the turntable system can be considered to be a phased-mission system(PMS).Reliability analysis for PMS has been widely studied.However,the system mode cycle characteristic has not been taken into account before.In this paper,reliability analysis method of the satellite turntable system is proposed considering its multiple operation modes and mode cycle characteristic.Firstly,the multi-valued decision diagrams(MDD)manipulation rules between two adjacent mission cycles are proposed.On this basis,MDD models for the turntable system in different states are established and the reliability is calculated using the continuous time Markov chains(CTMC)method.Finally,the comparative study is carried out to show the effectiveness of our proposed method.展开更多
This paper investigates the performability of hierarchical Wireless Networked Control Systems (WNCS). The WNCS studied can operate in two modes: passive supervisor and active supervisor. It is first shown that the Mar...This paper investigates the performability of hierarchical Wireless Networked Control Systems (WNCS). The WNCS studied can operate in two modes: passive supervisor and active supervisor. It is first shown that the Markov models for both modes are identical. Performability models are then developed and a case study shows how to use these models to help make design decisions. More specifically, it is observed that the performability of a passive supervisor system increases in time while that of an active supervisor system decreases in time.展开更多
文摘为了减少用户接通客服热线电话的等待时间,同时控制企业在客服热线方面的投入成本,结合用户行为,基于企业数据,采用连续时间马尔可夫链(continuous time Markov chain,CTMC)的数学模型对企业热线话务进行信道预测分析,寻求影响信道需求的相关参数。对不同规模企业的话务进行仿真,比对在不同客户量、不同通话保持时间需求、不同通话频率条件下的成功通话率、阻塞通话率及系统占线率,实现一种企业客服热线信道最佳资源配置的预测模型。
文摘针对并行密度聚类算法在处理大数据集时存在伸缩困难、参数寻优能力不佳、并行化效率较低等问题,提出一种基于分组和重力搜索优化算法(improve gravitational search algorithm,IGSA)的并行密度聚类算法(density-based clustering algorithm based on groups and improve gravitational search,MR-GDBIGS)。首先,该算法设计了基于图形的分组策略(grouping strategy based on pattern,GSP)来有效划分数据,加速邻域搜索,解决了处理大数据集时伸缩困难的问题;其次,在局部聚类中提出基于位置更新函数(position update function,PUF)的重力搜索优化算法,动态寻找局部聚类中的最优参数,提升了局部聚类的效果;最后,提出基于覆盖树的并行局部簇合并策略(cluster merging strategy by using MapReduce,MR-CTMC),在实现局部簇并行化合并的同时加快了合并局部簇的收敛速度,提升了算法整体的并行化效率。实验结果表明,MR-GDBIGS算法在处理大数据时的聚类效果更佳,且并行化性能更好。
文摘为了将故障预测与健康管理(prognostics and health management,PHM)技术应用到工程实践中,提出了基于可用度模型的PHM方法。首先通过广义随机Petri网(generalized stochastic Petri nets,GSPN)和连续马尔科夫链(continuous time Markov chain,CTMC)建立基本单元的软硬件可用度模型和健康状态转换图,通过求解微分方程得到基本单元软硬件的可用度数值。然后综合软硬件之间的故障相关性建立基本单元的完整可用度模型,并利用事件调度仿真机制得到其可用度的解。最后将基本单元故障模型同通用的可修系统稳态可用度模型对比,得到"可用度-故障率-维修率"形式的PHM计算模型,并以此作为工程应用中PHM分析的有效手段。
基金Supported by Youth Teacher Science and Technology Educational Foundation of Anhui Province,No.2003jq124National Natural Science Foundation of Anhui Province,No.2003kj 187
文摘AIM: To study the developmental regularities and heterogeneity of mast cells (MC) in human fetus duodenum and the distribution and developmental regularities of substance P(SP), calcitonin gene-related peptide (CGRP)-immunoreactive (IR) peptidergic nerves in fetus duodenum, as well as the relationship between MC, SP and CGRP-IR peptidergic nerves. METHODS: Duodena from 21 cases of human fetus and one term infant were stained by hematoxylin-eosin (HE), toluidine blue (TB) and immunohistochemical avidin-biotinylated peroxidase complex (ABC) method. RESULTS: Lobe-shape intestinal villi in duodenum were already developed at the twelfth week. At the 21st wk, muscular mucosa appeared gradually, and four layers were observed in the wall of duodenum. TB staining showed that the granules in the immature MC were pale violet, while the mature MC were strong violet in color by TB staining. Connective tissue MC (CTMC) appeared occasionally in submucosa and muscular layer of duodenum at the 16th wk. While the mucosa MC (MMC) appeared at the 18th wk. At the 22nd wk, both CTMC and MMC were activated, and distributed in the surrounding blood vessels and ganglions. The verge of some MC were unclear, and showed degranular phenomena. At the 14th wk, SP and CGRP-IR nerve fibers and cells appeared in the myenteric and submucous plexuses in small intestine, and the responses were turn strongly. Neurons were light to deep brown, and nerve fibers were present as varicose and liner profiles. On the corresponding site of serial sections, SP and CGRP immunohistochemical reactions were coexisted in one nerve fiber or cell. Some of MC showed SP and CGRP-IR positive staining. CONCLUSION: There are two heterogeneous kinds of MC in duodenum, MMC and CTMC. MC might play an important role in regulating blood circulation and sensation.
文摘Dynamically reconfigurable Field Programmable Gate Array(dr-FPGA) based electronic systems on board mission-critical systems are highly susceptible to radiation induced hazards that may lead to faults in the logic or in the configuration memory. The aim of our research is to characterize self-test and repair processes in Fault Tolerant(FT) dr-FPGA systems in the presence of environmental faults and explore their interrelationships. We develop a Continuous Time Markov Chain(CTMC) model that captures the high level fail-repair processes on a dr-FPGA with periodic online Built-In Self-Test(BIST) and scrubbing to detect and repair faults with minimum latency. Simulation results reveal that given an average fault interval of 36 s, an optimum self-test interval of 48.3 s drives the system to spend 13% of its time in self-tests, remain in safe working states for 76% of its time and face risky fault-prone states for only 7% of its time. Further, we demonstrate that a well-tuned repair strategy boosts overall system availability, minimizes the occurrence of unsafe states, and accommodates a larger range of fault rates within which the system availability remains stable within 10% of its maximum level.
文摘We consider a carrier sense multiple access (CSMA) in an unslotted cognitive radio network with random residence time. In this system, if an arriving secondary user (SU) does not find any idle channels, then the SU either enters the back-off group or gives up its service and leaves the system. SUs in the back-off group have random mobility, so may re-access the channel after random time or go to the other network after random residence time. We model the system by 3-demensional Continuous Time Markov Chain (CTMC) and obtain the steady state probability of the system by matrix analytic method. In numerical results, we compare the performance of two systems with and without residence time of SUs. It is shown that the random mobility of SUs has an impact on the performance of SUs in cognitive radio networks.
基金co-supported by the Natural Science Foundation of China(No.61833016)the Shaanxi Out-standing Youth Science Foundation(No.2020JC-34)+1 种基金the Shaanxi Science and Technology Innovation Team(No.2022TD-24)the Natural Science Foundation of Heilongjiang Province of China(No.LH2021F038).
文摘As a payload support system deployed on satellites,the turntable system is often switched among different working modes during the on-orbit operation,which can experience great state changes.In each mode,the missions to be completed are different,consecutive and non-over-lapping,from which the turntable system can be considered to be a phased-mission system(PMS).Reliability analysis for PMS has been widely studied.However,the system mode cycle characteristic has not been taken into account before.In this paper,reliability analysis method of the satellite turntable system is proposed considering its multiple operation modes and mode cycle characteristic.Firstly,the multi-valued decision diagrams(MDD)manipulation rules between two adjacent mission cycles are proposed.On this basis,MDD models for the turntable system in different states are established and the reliability is calculated using the continuous time Markov chains(CTMC)method.Finally,the comparative study is carried out to show the effectiveness of our proposed method.
文摘This paper investigates the performability of hierarchical Wireless Networked Control Systems (WNCS). The WNCS studied can operate in two modes: passive supervisor and active supervisor. It is first shown that the Markov models for both modes are identical. Performability models are then developed and a case study shows how to use these models to help make design decisions. More specifically, it is observed that the performability of a passive supervisor system increases in time while that of an active supervisor system decreases in time.
