Dynamic priority rules for cyclic-type queues

1989 ◽  
Vol 21 (2) ◽  
pp. 432-450 ◽  
Author(s):  
Sid Browne ◽  
Uri Yechiali
Keyword(s):  
Control Strategies ◽  
Current System ◽  
Waiting Times ◽  
Physical Principle ◽  
Priority Rules ◽  
Dynamic Priority ◽  
Cyclic Service ◽  
Cyclic Type ◽  
General Physical ◽  
Adaptive Nature

A cyclic service system is composed of K channels (queues) and a single cyclically roving server who typically takes a positive amount of time to switch between channels. Research has previously focused on evaluating and computing performance measures (notably, waiting times) of fixed template routing schemes under three main service disciplines, the exhaustive, gated and limited service regimes.In this paper, probabilistic results are derived that allow control strategies and optimal policies to be considered for the first time. By concentrating on a new objective function, we are able to derive rules of index form amenable for direct implementation to dynamically control the system at suitably defined decision epochs. These rules utilize current system information, are of an adaptive nature, and are shown to emanate from a general physical principle.

Dynamic priority rules for cyclic-type queues

1989 ◽  
Vol 21 (02) ◽  
pp. 432-450 ◽  
Author(s):  
Sid Browne ◽  
Uri Yechiali
Keyword(s):  
Control Strategies ◽  
Current System ◽  
Waiting Times ◽  
Physical Principle ◽  
Priority Rules ◽  
Dynamic Priority ◽  
Cyclic Service ◽  
Cyclic Type ◽  
General Physical ◽  
Adaptive Nature

A cyclic service system is composed of K channels (queues) and a single cyclically roving server who typically takes a positive amount of time to switch between channels. Research has previously focused on evaluating and computing performance measures (notably, waiting times) of fixed template routing schemes under three main service disciplines, the exhaustive, gated and limited service regimes. In this paper, probabilistic results are derived that allow control strategies and optimal policies to be considered for the first time. By concentrating on a new objective function, we are able to derive rules of index form amenable for direct implementation to dynamically control the system at suitably defined decision epochs. These rules utilize current system information, are of an adaptive nature, and are shown to emanate from a general physical principle.

scholarly journals Analysis of the Installed Productive Capacity in a Medical Angiography Room through Discrete Event Simulation

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 660
Author(s):  
Félix Badilla-Murillo ◽  
Bernal Vargas-Vargas ◽  
Oscar Víquez-Acuña ◽  
Justo García-Sanz-Calcedo
Keyword(s):  
Resource Utilization ◽  
Discrete Event Simulation ◽  
Current System ◽  
Waiting Times ◽  
Continuous Process ◽  
Discrete Event ◽  
Computer Software ◽  
Productive Capacity ◽  
Continuous Process Improvement ◽  
Event Simulation

The installed productive capacity of a healthcare center’s equipment limits the efficient use of its resources. This paper, therefore, analyzes the installed productive capacity of a hospital angiography room and how to optimize patient demand. For this purpose, a Discrete Event Simulation (DES) model based on historical variables from the current system was created using computer software. The authors analyzed 2044 procedures performed between 2014 and 2015 in a hospital in San José, Costa Rica. The model was statistically validated to determine that it does not significantly differ from the current system, considering the DMAIC stages for continuous process improvement. In the current scenario, resource utilization is 0.99, and the waiting list increases every month. The results showed that the current capacity of the service could be doubled, and that resource utilization could be reduced to 0.64 and waiting times by 94%. An increase in service efficiency could be achieved by shortening maximum waiting times from 6.75 days to 3.70 h. DES simulation, therefore, allows optimizing of the use of healthcare systems’ resources and hospital management.

scholarly journals Improving the waiting times within a hospice breathlessness service

2019 ◽  
Vol 8 (2) ◽  
pp. e000582
Author(s):  
Caroline Sime ◽  
Stuart Milligan ◽  
Kevin Donal Rooney
Keyword(s):  
Palliative Care ◽  
Quality Improvement ◽  
Waiting Time ◽  
Current System ◽  
Waiting Times ◽  
Well Being ◽  
Common Symptom ◽  
Specialist Palliative Care ◽  
Published Evidence

BackgroundBreathlessness, a common symptom in advanced disease, is a distressing, complex symptom that can profoundly affect the quality of one’s life. Evidence suggests that specialist palliative care breathlessness intervention services can improve physical well-being, personal coping strategies and quality of life. In the UK, the use of quality improvement methods is well documented in the National Health Service. However, within the independent hospice sector there is a lack of published evidence of using such methods to improve service provision.AimThe aim of this project was to reduce the waiting time from referral to service commencement for a hospice breathlessness service by 40%—from a median of 19.5 to 11.5 working days.MethodsUsing a quality planning and systems thinking approach staff identified barriers and blockages in the current system and undertook plan-do-study-act cycles to test change ideas. The ideas tested included offering home visits to patients on long-term oxygen, using weekly team ‘huddles’, streamlining the internal referral process and reallocating staff resources.ResultsUsing quality improvement methods enabled staff to proactively engage in positive changes to improve the service provided to people living with chronic breathlessness. Offering alternatives to morning appointments; using staff time more efficiently and introducing accurate data collection enabled staff to monitor waiting times in real time. The reduction achieved in the median waiting time from referral to service commencement exceeded the project aim.ConclusionsThis project demonstrates that quality improvement methodologies can be successfully used in a hospice setting to improve waiting times and meet the specific needs of people receiving specialist palliative care.

scholarly journals Using Dynamic Priority Rules for Optimization of Complex Manufacturing Systems

2012 ◽  
Vol 45 (6) ◽  
pp. 1359-1365
Author(s):  
Tomasz Wisniewski ◽  
Przemysław Korytkowski ◽  
Oleg Zaikin ◽  
Eduard Pesikov
Keyword(s):  
Manufacturing Systems ◽  
Priority Rules ◽  
Dynamic Priority ◽  
Complex Manufacturing Systems

Heat Pump-Organic Rankine Cycle Hybrid Systems for Co/Tri-Generation Applications: A State-of-the-Art Overview

2020 ◽  
Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev ◽  
Pouyan Talebizadeh Sardari ◽  
Michela Longo
Keyword(s):  
Hybrid Systems ◽  
Control Strategies ◽  
Current System ◽  
Experimental Studies ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Economic Feasibility ◽  
Working Fluid ◽  
Future Research ◽  
Component Level

Abstract The following paper aims to explore a heat pump’s (HP) as well as an organic Rankine cycle’s (ORC) novel combination for the development of both an efficient and low-emissions heating and cooling systems. This latest review examines both benefits and possibilities of a combined HP-ORC system. Previously, studies have explored several different combinations, such as directly-coupled and reversible combination units as well as parallel configurations units in addition to indirectly-coupled ones. Following defining aforementioned configurations, a discussion on their performance is carried out in detail. Considerations for the optimisation of the architecture, overall of such hybrid systems via utilising the same sources while also discussing heat source, sink selection and operating temperatures as well as thermal energy storage, expander/compressor units, control strategies in addition to working fluids’ selection and managing seasonal temperatures that are increasingly variable, have been identified. Additionally, the experimental studies that have been performed reveal increasingly practical obstacles as well as other areas that require more research while serving to shed light on experimental techniques, which can be applicable to this research’s area. Based upon research, it has been revealed that regional conditions including temperatures and annual weather as well as the cost of energy produce a colossal effect on such systems’ economic feasibility framework as well as partially dictating the overall system configuration’s selection. Additionally, the review disclosed how important the following elements are: 1) a greater temperature differential amid the source of heat and heat sink; 2) proper source of heat and sink selection; 3) working fluid selection; and 4) thermal storage for the maintenance of the difference. Comparatively, from the research works from the past, additional optimisation based on individual component level as well as through control strategies of either an advanced or predictive method, these produce a smaller effect and are worth performing an evaluation on economically due to them not being feasible for the current system. Lastly, based on investigated research, there are certain areas for which recommendation have been provided with regard to future research and this includes a technology configurations’ comparison for understanding different regions’ optimal system, a sensitivity analysis for understanding key system elements for both optimisation as well as design, both an investigation as well as testing carried out for available units and applicable systems that are presently available, and identifying novel use cases.

scholarly journals The Attitude of Russian Population to the Revival of the Sports Complex «Ready for Labor and Defense» (GTO)

2021 ◽  
Vol 20 (2) ◽  
pp. 60-68
Author(s):  
Eugenia M. Bronnikova ◽  
◽  
Olga S. Kulyamina ◽  
Marina V. Vinogradova ◽  
◽  
...  
Keyword(s):  
Current System ◽  
Research Work ◽  
Age Groups ◽  
State Level ◽  
The Elderly ◽  
Physical Culture ◽  
Educational Organizations ◽  
Focus Group Research ◽  
Patriotic Education ◽  
General Physical

The implementation of the “Ready for Labor and Defense” (GTO) complex is intended to improve the health and life expectancy of citizens, to attract the population of all age groups to systematic physical activities and sports, and to improve the system of general physical training in educational organizations. This complex pursues the goal of sports and patriotic education of young people, is considered as a mechanism for organizing moral and spiritual education. The article presents the results of an Russian survey and focus group research carried out in the course of preparing a research work dedicated to identifying motives, incentives and satisfaction of the population with conditions for physical culture and sports in 2020 and 2021. It was revealed that the most involved in passing the standards of the complex is the group aged 18 to 24 years, which is due to the possibility of passing the standards in educational organizations, as well as in connection with the current system of adding points to the Unified State Exam when entering a university for applicants who have the GTO insignia. The set of programs is being carried out to attract the population of all age groups at the state level, including students, employees of organizations and the elderly population. Despite this, it was found that with increasing age, the motivation of the population to pass the standards of the complex decreases.

scholarly journals Fuzzy Logic based H-bridge STATCOM Controller to compensate Unbalanced Voltages

2020 ◽  
Vol 6 (7) ◽  
pp. 135-139
Author(s):  
G Mahesh P Ankineedu Prasad
Keyword(s):  
Fuzzy Logic ◽  
Reactive Power ◽  
Control Strategies ◽  
Current System ◽  
Voltage Regulation ◽  
Large Current ◽  
Railway Traction ◽  
And Performance ◽  
Shunt Compensation ◽  
Traction Power Supply

In this paper a new method four-leg topology is suggested for shunt compensation, the H-bridge multilevel converters based on the half-bridge converters, to achieve higher performance as a STATCOM in a distorted and unbalanced medium-voltage large-current system. Further, an extended Fuzzy based STATCOM is proposed in order to manage more accurate compensation for high-power applications. Both proposals can be controlled for various purposes such as reactive power and unbalance compensation, voltage regulation, and harmonic cancellation. One interesting application for the Fuzzy logic based STATCOM could be the improvement in power quality and performance of the electrified railway traction power supply system. Both the H-bridge based STATCOM along with their proposed control strategies were simulated.

scholarly journals A Dynamic Holding Approach to Stabilizing a Bus Line Based on the Q-Learning Algorithm with Multistage Look-Ahead

2021 ◽  
Author(s):  
Sheng-Xue He ◽  
Jian-Jia He ◽  
Shi-Dong Liang ◽  
June Qiong Dong ◽  
Peng-Cheng Yuan
Keyword(s):  
Learning Algorithm ◽  
Control Strategies ◽  
Waiting Times ◽  
Line System ◽  
Q Learning ◽  
Unstable Phase ◽  
Look Ahead ◽  
Bus Bunching ◽  
Detailed Simulation ◽  
Past Experiences

The unreliable service and the unstable operation of a high-frequency bus line are shown as bus bunching and the uneven distribution of headways along the bus line. Although many control strategies, such as the static and dynamic holding strategies, have been proposed to solve the above problems, many of them take on some oversimplified assumptions about the real bus line operation. So it is hard for them to continuously adapt to the evolving complex system. In view of this dynamic setting, we present an adaptive holding method that combines the classic approximate dynamic programming (ADP) with the multistage look-ahead mechanism. The holding time, the only control means used in this study, will be determined by estimating its impact on the operation stability of the bus line system in the remaining observation period. The multistage look-ahead mechanism introduced into the classic Q-learning algorithm of the ADP model makes it easy that the algorithm gets through its earlier unstable phase more quickly and easily. During the implementation of the new holding approach, the past experiences of holding operations can be cumulated effectively into an artificial neural network used to approximate the unavailable Q-factor. The use of a detailed simulation system in the new approach makes it possible to take into account most of the possible causes of instability. The numerical experiments show that the new holding approach can stabilize the system by producing evenly distributed headway and removing bus bunching thoroughly. Compared with the terminal station holding strategies, the new method brings a more reliable bus line with shorter waiting times for passengers.

Closed queueing networks with blocking-a model for flexible manufacturing systems

1984 ◽  
Vol 16 (1) ◽  
pp. 9-9
Author(s):  
David D. W. Yao ◽  
J.A. Buzacott
Keyword(s):  
Flexible Manufacturing ◽  
Queueing Networks ◽  
Manufacturing Systems ◽  
Waiting Times ◽  
Queueing Systems ◽  
Priority Queue ◽  
Single Server ◽  
Closed Queueing Networks ◽  
State Behavior ◽  
Dynamic Priority

We consider a family of single-server queueing systems with two priority classes. The system operates under a dynamic priority queue discipline in which the relative priorities of customers increase with their waiting times, and which can be characterized by the urgency number. We investigate the transient as well as the steady-state behavior of the virtual waiting times of the two classes of customer as functions of the urgency number. Stochastic orderings, the joint distribution, and surprising limit results for these processes are obtained for the first time.

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