Effects of pooling,specialization,and discretionary task completion on queueing performance

Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and disadvantages in different operational environments.This paper uses the M/M/1 and M/M/2 queues to study the impact of pooling,specialization,and discretionary task completion on the average queue length.Closed-form solutions for the average M/M/2 queue length are derived.Computational examples illustrate how the average queue length changes with the strength of pooling,specialization,and discretionary task completion.Finally,several conjectures are made in the paper.

A Maintenance Service Improvement Approach Based on Queue Networks: Application

The quest to increase the performance of production systems that have become complex leads to the transfer to the maintenance function of the responsibility of guaranteeing the availability of such systems. Also, we will never stop saying that maintenance must integrate into all of the company’s initiatives, to affirm its role, which is to ensure greater availability and sustainability of the means of production. The objective of this paper is to evaluate the reliability and availability of a system without knowing the distribution law of the operating times. Among the methods for evaluating dependability criteria (Fault Trees, Petri Nets, etc.), we are interested in queues that have the advantage of taking into account functional dependencies, thus allowing a quantified optimization of maintenance. Indeed, queues make it possible to model parallel or sequential processes, implementing operations taking place at the same time or one after the other, meeting the needs of modeling production systems. The main result of this paper is the study of the influence of availability on the reliability of a multi-state production system.

V-uniform ergodicity for fluid queues

In this paper, we show that a positive recurrent ?uid queue is automatically V-uniformly ergodic for some function V ≥ 1 but never uniformly ergodic. This reveals a similarity of ergodicity between a ?uid queue and a quasi-birth-and-death process. As a byproduct of V-uniform ergodicity, we derive computable bounds on the exponential moments of the busy period.

A Non-Preemptive Priority Queueing System with a Single Server Serving Two Queues M/G/1 and M/D/1 with Optional Server Vacations Based on Exhaustive Service of the Priority Units

We study a vacation queueing system with a single server simultaneously dealing with an M/G/1 and an M/D/1 queue. Two classes of units, priority and non-priority, arrive at the system in two independent Poisson streams. Under a non-preemptive priority rule, the server provides a general service to the priority units and a deterministic service to the non-priority units. We further assume that the server may take a vacation of random length just after serving the last priority unit present in the system. We obtain steady state queue size distribution at a random epoch. Corresponding results for some special cases, including the known results of the M/G/1 and the M/D/1 queues, have been derived.

VIRTUAL WAITING TIMES IN PRIORITY-M/G/1 QUEUES WITH VACARIONS

In this paper exhaustive-service priority-M/G/1 queueing systems with multiple vacations, single vacation and setup times are studied under the nonpreemptive and preemptive resume priority disciplines. For each of the six models analysed, the Laplace-Stieltjes transform of the virtual waiting time Wk(t) at time t of class k is derived by the method of collective marks. A sufficient condition for , where U has the standard normal distribution, is also given.

Computational analysis of(MAP_1,MAP_2)/(PH_1,PH_2)/N queues with finite buffer in wireless cellular networks

This paper studies a queueing model with the finite buffer of capacity K in wireless cellular networks, which has two types of arriving calls--handoff and originating calls, both of which follow the Markov arriving process with different rates. The channel holding times of the two types of calls follow different phase-type distributions. Firstly, the joint distribution of two queue lengths is derived, and then the dropping and blocking probabilities, the mean queue length and the mean waiting time from the joint distribution are gotten. Finally, numerical examples show the impact of different call arrival rates on the performance measures.

Basic Limit Theorems for Light Traffic Queues &Their Applications

In this paper, we study some basic limit theorems characterizing the stationary behavior of light traffic queuing systems. Beginning with limit theorems for the simple M/M/1 queuing system, we demonstrate the methodology for applying these theorems for the benefit of service systems. The limit theorems studied here are dominant in the literature. Our contribution is primarily on the analysis leading to the application of these theorems in various problem situations for better operations. Relevant Examples are included to aid the application of the results studied in this work.

The Economics of Reorganizing Otolaryngology Out-Patient Services for COVID-19 Pandemic in Low- and Middle-Income Countries

The Coronavirus 2019 (COVID-19) pandemic has widespread implications for clinical practice of otolaryngologists in clinics and hospitals. With various reports of otolaryngology practitioners catching infection, a profound structural reorganization of ENT services in the clinic is mandatory for protecting both patients and healthcare workers. The present study focused on quantifying the cost involved in reorganizing the otolaryngology out-patient services in a third world country during the ongoing Covid-19 pandemic. Though the pandemic has increased the cost of running of an otolaryngology practice world over, the impact is huge in India as penetration of health insurance/social security is minimal. As out of pocket expenditure forms a significant proportion of healthcare spending by majority in India, any transfer of additional cost incurred because of Covid-19 pandemic to the patient will burn a bigger hole in their pocket.

Stress and quality of life in dermatological patients: Are out-patients' needs different?

The debut, progression and maintenance of skin disease are related to stress(acne, alopecia areata, atopic dermatitis, lichen planus, psoriasis, urticaria, vitiligo, herpes, hyperhidrosis, pemphigus, rosacea or seborrheic dermatitis). Environmental, socio-professional, life events are representing external factors. Personality, previous experiences, traits of anxiety are individual factors influencing the state of stress. Perceived stress could be more harmful especially in "high reactors" to stress. Coping abilities to stress could be increased in social programs. There was a recent interest in measuring the quality of life in the last years. There are dermatology and disease specific questionnaires that could help. Out-patients have less time to wait for very sophisticated procedures. They expect faster results. For simple, acute diseases it is important to have a good communication and good understanding of the instructions to get results as soon as possible. For chronic diseases a strong long-term alliance is needed, so the patients should revisit for his benefit and not for giving up. Small questions regarding potential stressful events, impact on the quality of life, stigmatization, the level of symptoms(pruritus), psychiatric comorbidities(anxiety, depression), short questionnaires for quality of life give us a better picture, personalize the doctorpatient relationship and could influence the choice of treatment. Many skin disorders could be seen from a psychosomatic point of view and the final goal, especially for the chronic diseases, is to improve through our treatments the impact on the quality of patient's life.

A Fully Adaptive Active Queue Management Method for Congestion Prevention at the Router Buffer

Active queue management(AQM)methods manage the queued packets at the router buffer,prevent buffer congestion,and stabilize the network performance.The bursty nature of the traffic passing by the network routers and the slake behavior of the existing AQM methods leads to unnecessary packet dropping.This paper proposes a fully adaptive active queue management(AAQM)method to maintain stable network performance,avoid congestion and packet loss,and eliminate unnecessary packet dropping.The proposed AAQM method is based on load and queue length indicators and uses an adaptive mechanism to adjust the dropping probability based on the buffer status.The proposed AAQM method adapts to single and multiclass traffic models.Extensive simulation results over two types of traffic showed that the proposed method achieved the best results compared to the existing methods,including Random Early Detection(RED),BLUE,Effective RED(ERED),Fuzzy RED(FRED),Fuzzy Gentle RED(FGRED),and Fuzzy BLUE(FBLUE).The proposed and compared methods achieved similar results with low or moderate traffic load.However,under high traffic load,the proposed AAQM method achieved the best rate of zero loss,similar to BLUE,compared to 0.01 for RED,0.27 for ERED,0.04 for FRED,0.12 for FGRED,and 0.44 for FBLUE.For throughput,the proposed AAQM method achieved the highest rate of 0.54,surpassing the BLUE method’s throughput of 0.43.For delay,the proposed AAQM method achieved the second-best delay of 28.51,while the BLUE method achieved the best delay of 13.18;however,the BLUE results are insufficient because of the low throughput.Consequently,the proposed AAQM method outperformed the compared methods with its superior throughput and acceptable delay.

Optimal Implementation of Two FIFO-Queues in Single-Level Memory

This paper presents mathematical models and optimal algorithms of two FIFO-queues control in single-level memory. These models are designed as two-dimensional random walks on the integer lattice in a rectangular area for consecutive implementation and a triangle area for linked list implementation.

基于异步整形机制的智能变电站通信队列调度策略

时间敏感网络(TSN)因能为智能变电站关键通信业务提供确定性低延时传输服务而得到广泛关注。针对现有变电站工业以太网交换机通信队列调度策略难以从理论上保证关键通信业务的实时性和可靠性的问题,该文提出了基于TSN异步整形机制(ATS)的智能变电站通信队列调度策略。首先,基于智能变电站业务流服务质量需求及传输特点,提出了智能变电站业务流的优先级划分及整形队列分配方案;其次,建立了以业务流端到端时延最小化为目标的整形器参数最优化模型,并通过内点优化算法求解;最后,整形器采用基于令牌桶的流量整形方法对划分后的业务流进行整形,整形后的流量基于严格优先级算法调度传输。基于OMNet++进行了仿真实验,实验结果表明,该文所提方法能够保障关键通信业务的确定性低时延传输。

基于虚拟网关的交通基础设施监测点位数据接入方法

针对交通基础设施点位监测数据来源多样、结构各异、协议不一的特点,分析具体接入需求,提出一种基于Netty架构的交通基础设施监测点位数据接入虚拟网关。阐述网关接入监测点位的配置方法及集群分配策略,定义超文本传输协议(HTTP)、传输控制协议(TCP)、用户数据报协议(UDP)下的数据传输格式,设计一种数据传输消息的编码和校验机制。在真实监测数据样本增强的基础上,利用分布式消息模拟工具对虚拟网关性能进行测试,结果表明,该虚拟网关实现了多点位多协议的交通基础设施监测数据统一接入,每亿条数据接入时间、存储时间分别达到8.14 s和9.75 s,平均数据溯源时间为2.96 s,具有亿级规模点位监测数据的接入能力,可为交通基础设施数字化监测的研究和应用提供理论支撑。

基于DQueue和CCF的消息队列设计要点分析

消息队列作为一种常见的数据结构,在应用程序和软件操作系统中得到了广泛应用,而随着处理器的不断迭代,传统的锁同步消息队列逐渐无法发挥多核处理器的性能。因此,研究人员尝试引入布谷鸟过滤器(Cuckoo Filter,CCF)和DQueue技术对消息队列进行优化升级,创建云开发消息队列(Cloud Development Message Queue,CDMQ)。基于上述两种技术同时生成多个队列写入数据,操作者利用CCF对数据进行过滤检验,并读取相关信息。通过对CDMQ的性能测试,研究人员证明该消息队列结构具有伸缩性强和吞吐量高等优势,对提高消息队列性能具有重要意义。

基于李雅普诺夫的RIS辅助无人机边缘计算网络中任务卸载与资源分配研究

针对无人机(UAV)面对复杂时变的衰落信道对无线传输造成不利影响这一问题,构建了可重构智能表面(RIS)辅助UAV边缘计算网络中UAV轨迹、RIS相移、卸载时隙分配、CPU频率分配和用户设备(UE)传输功率的联合优化问题。为了求解构建的问题,对UE和UAV的任务队列稳定性约束进行转化,将多时隙随机性优化问题转化为每个时隙的确定性优化问题,提出了基于李雅普诺夫优化和块坐标下降(BCD)法的任务卸载与资源分配(JORL)方法。首先基于三角不等式求解RIS相移并求得闭合表达式;然后使用非凸转凸问题的技术求解卸载时隙分配、CPU频率分配和UE传输功率;最后基于连续凸近似方法求解UAV轨迹。仿真结果表明,JORL在保证任务队列稳定性和降低能耗方面有较优越的性能。

离散时间的完全服务并行优化轮询排队系统特性分析

轮询是一种依次有序服务的系统资源动态调度机制.针对服务器在站点间查询、服务和转移过程中的流水线作业方式导致了系统整体服务效率较低的问题,本文提出了完全服务的并行优化轮询系统.首先,构建了系统的单服务器多队列排队模型和相应的系统状态方程,并精确解析出系统特性参数的完整数学解析表达式.此外,还提出了一种系统状态稳定性的判定方法,对不同负载状态下的系统稳定性进行了定量分析.计算机仿真的统计分析结果与理论计算值相一致.最后,系统性能分析表明,在保持周期性、无冲突服务的基础上,系统的队长、时延特性和稳定状态下负载能力均得到了较大的提高.

连续时间完全-限定(K=2)两级轮询系统性能分析

为了实现区分网络优先级、保证公平性、提高普通站点的性能和效率,在完全-限定(K=1)两级轮询控制系统模型的基础上,提出连续时间完全-限定(K=2)两级轮询控制系统模型。在该模型中,使用限定(K=2)服务和完全服务分别对普通站点和中心站点进行服务。中心站点转换到普通站点进行服务时,使用捎带查询方式。在此基础上,采用马尔可夫链和概率母函数的数学方法建立该轮询系统模型,并推导平均排队队长和时延。利用MATLAB进行仿真实验,结果表明:理论值与仿真值误差较小,验证了理论分析的正确性;与门限-完全服务模型相比,该模型中心站点的队长和时延均小于门限-完全服务中心站点的队长和时延,具有更高的优先级;与一级完全服务和一级限定(K=2)服务模型相比,区分了优先级,性能分别提升11.7%和14.5%,说明两级服务远好于一级服务;与完全-限定(K=1)两级服务模型相比,增加了发送的数据,减少了等待时间,性能提升13.04%左右,进一步优化了普通站点的性能。

基于排队论的动态最优保险区块链决策研究

保险业的经营原则与区块链的共识特征存在基因相似性。本文引入“批排队”理论构建了动态最优保险区块链模型,较好地刻画了按照“先到先服务”原则将包含众多保险交易的区块追加到整个区块链的过程,该模型可以通过最大化保险区块链系统主体效用得到最优的保险交易费率。以中国车险市场2020年的实际经营数据为例进行数值模拟表明,不同参数的变化对保险交易双方效用的影响取决于交易记录延迟时间与交易费率之间的权衡,而对保单区块存储员效用的影响取决于区块存储收益与区块存储成本之间的权衡。相关数据为区块链技术在保险市场中降低经营成本、提高经营效率、释放劳动力等提供了理论支持。

乐园游客排队最大接受时长影响因素研究——基于上海迪士尼乐园的实证研究

以ACSI模型为核心,结合ABC态度模型和归因理论等建立了概念模型,旨在探究游客排队最大接受时长的影响因素。将迪士尼乐园作为研究对象,对收集到的220份问卷进行统计分析结果发现,顾客期望维度的四个变量对排队最大接受时长均存在正向影响;游客排队时的感知质量中,游客对于园方排队管理的努力程度的感知以及游乐项目对于游客预期的个性化需求的满足程度对排队最大接受时长有正向影响,而排队的感知时长会对其产生负向影响;排队最大接受时长与顾客的抱怨/不满之间存在负向影响。研究结论为乐园优化游客排队体验,提升游客排队最大接受时长提供了一定的指导。

队列训练对新招录民警形象气质的塑造提升研究

队列训练是遵循队列训练条令规则进行的各种制式动作操练,是人民警察系统训练的基础,是加强人民警察队伍规范化和法治化建设的一种形式,是人民警察精神面貌的一种体现。通过队列训练塑造新招录人民警察良好的形象气质,强化扎实的纪律作风,培养坚定的意志品质,树立强烈的集体观念,强力推进警务化管理。队列训练体现着增强人民警察快速反应提高战斗力、推进人民警察正规化建设有序开展、强化人民警察纪律作风养成、锻造人民警察能拼善赢过硬本领、规范人民警察执法、提升执法效能的深刻内涵和价值意蕴。