ترجمه مقاله نقش ضروری ارتباطات 6G با چشم انداز صنعت 4.0
- مبلغ: ۸۶,۰۰۰ تومان
ترجمه مقاله پایداری توسعه شهری، تعدیل ساختار صنعتی و کارایی کاربری زمین
- مبلغ: ۹۱,۰۰۰ تومان
Analytic queueing network models often assume infinite capacity queues due to the difficulty of grasping the between-queue correlation. This correlation can help to explain the propagation of congestion. We present an analytic queueing network model which preserves the finite capacity of the queues and uses structural parameters to grasp the between-queue correlation. Unlike pre-existing models it maintains the network topology and the queue capacities exogenous. Additionally, congestion is directly modeled via a novel formulation of the state space of the queues which explicitly captures the blocking phase. The model can therefore describe the sources and effects of congestion.
The model is formulated for networks with an arbitrary topology, multiple server queues and blocking-after-service. It is validated by comparison with both pre-existing methods and simulation results. It is then applied to study patient flow in a network of units of the Geneva University Hospital. The model has allowed us to identify three main sources of bed blocking and to quantify their impact upon the different hospital units.
1. Introduction
Detecting the sources and effects of congestion within a network allows us to better understand its behavior and to improve its performance. The study of congestion is relevant in a variety of sectors ranging from the analysis of spillbacks (i.e. the backwards propagation of congestion) in urban traffic or pedestrian traffic (Cheah and Smith, 1994) to that of hospital bed blocking (Koizumi et al., 2005) or prison cell blocking (Korporaal et al., 2000).
The most common approach to analyze network congestion is the development of simulation models that capture the details of the underlying system. They are cumbersome to use within an optimization framework. On the other hand, analytic models naturally fit within such a framework but are rarely developed due to the complexity of modeling the propagation of congestion while preserving a flexible model. We focus on analytic models and more specifically on analytic queueing network models.
7. Conclusions and future work
We have presented an analytic queueing network model that preserves the finite capacity property of the real system. The model is formulated for multiple server finite capacity queueing networks with an arbitrary topology and blocking-after-service. The model is based on a decomposition of the network into single queues. The structural parameters of the queues are approximated so that they can account for the between-queue correlation. Unlike pre-existing methods the network topology and its configuration (number of queues and their capacity) are preserved throughout the analysis thus no constraints need to be checked a posteriori.