scholarly journals Integrating Queueing Theory and Scheduling for Dynamic Scheduling Problems

2014 ◽  
Vol 50 ◽  
pp. 535-572 ◽  
Author(s):  
D. Terekhov ◽  
T. T. Tran ◽  
D. G. Down ◽  
J.C. Beck
Keyword(s):  
Queueing Theory ◽  
Dynamic Scheduling ◽  
Queueing Network ◽  
Scheduling Problems ◽  
Short Term ◽  
Arrival Times ◽  
Processing Times ◽  
Long Run ◽  
Resource Requirements ◽  
First Time

Dynamic scheduling problems consist of both challenging combinatorics, as found in classical scheduling problems, and stochastics due to uncertainty about the arrival times, resource requirements, and processing times of jobs. To address these two challenges, we investigate the integration of queueing theory and scheduling. The former reasons about long-run stochastic system characteristics, whereas the latter typically deals with short-term combinatorics. We investigate two simple problems to isolate the core differences and potential synergies between the two approaches: a two-machine dynamic flowshop and a flexible queueing network. We show for the first time that stability, a fundamental characteristic in queueing theory, can be applied to approaches that periodically solve combinatorial scheduling problems. We empirically demonstrate that for a dynamic flowshop, the use of combinatorial reasoning has little impact on schedule quality beyond queueing approaches. In contrast, for the more complicated flexible queueing network, a novel algorithm that combines long-term guidance from queueing theory with short-term combinatorial decision making outperforms all other tested approaches. To our knowledge, this is the first time that such a hybrid of queueing theory and scheduling techniques has been proposed and evaluated.

Parallel autonomous guided vehicle assembly line for a semi-continuous manufacturing system

2016 ◽  
Vol 36 (3) ◽  
pp. 262-273 ◽  
Author(s):  
Hamed Fazlollahtabar
Keyword(s):  
Manufacturing System ◽  
Assembly Line ◽  
Dynamic Scheduling ◽  
Continuous Manufacturing ◽  
Scheduling Problems ◽  
Assembly Lines ◽  
Short Term ◽  
Line System ◽  
Content Type ◽  
Multiple Products

Purpose This paper aims to propose a parallel automated assembly line system to produce multiple products in a semi-continuous system. Design/methodology/approach The control system developed in this research consists of a manufacturing system for two-level hierarchical dynamic decisions of autonomous/automated/automatic-guided vehicles (AGVs) dispatching/next station selection and machining schedules and a station control scheme for operational control of machines and components. In this proposed problem, the assignment of multiple AGVs to different assembly lines and the semi-continuous stations is a critical objective. AGVs and station scheduling decisions are made at the assembly line level. On the other hand, component and machining resource scheduling are made at the station level. Findings The proposed scheduler first decomposes the dynamic scheduling problems into a static AGV and machine assignment during each short-term rolling window. It optimizes weighted completion time of tasks for each short-term window by formulating the task and resource assignment problem as a minimum cost flow problem during each short-term scheduling window. A comprehensive decision making process and heuristics are developed for efficient implementation. A simulation study is worked out for validation. Originality/value Several assembly lines are configured to produce multiple products in which the technologies of machines are shared among the assembly lines when required. The sequence of stations is pre-specified in each assembly line and the components of a product are kept in machine magazine. The transportation between the stations in an assembly line (intra assembly line) and among stations in different assembly lines (inter assembly line) are performed using AGVs.

scholarly journals Berth Allocation Problem with Quay Crane Assignment for Container Terminals Based on Rolling-Horizon Strategy

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Ling Xiao ◽  
Zhi-Hua Hu
Keyword(s):  
Large Scale ◽  
Dynamic Scheduling ◽  
Time Window ◽  
Optimal Solution ◽  
Container Terminals ◽  
Rolling Horizon ◽  
Scheduling Problems ◽  
Berth Allocation Problem ◽  
Arrival Times ◽  
Rolling Window

In order to solve the large-scale integral dynamic scheduling of continuous berths and quay cranes problem, a method based on rolling-horizon strategy is proposed. A multiobjective optimization model that is established minimizes the total penalty costs considering vessels’ deviations to their preferred berthing positions, delayed times for berthing comparing to their estimated arrival times, and delayed times for departure comparing to their estimated departure times. Then, the scheduling process was divided into a set of continual scheduling interval according to the dynamic arrival sequences. Meanwhile, rolling-horizon strategies for setting rolling and frozen windows and the parameter updating strategy are designed. The input parameters of the model in the next rolling window are updated according to the optimal results of each time window which have been obtained. The model is solved by choosing appropriate rolling and freezing window lengths that represents the numbers of adjacent vessels in the sequence of calling vessels. The holistic optimal solution is obtained by gradually rolling and combining the results of each window. Finally, a case study indicated that the rolling schedule can solve large-scale scheduling problems, and the efficiency of the proposed approach relates to the size of rolling window, freeze ship quantity, and rolling frequency.

The Sustainable Debts of Philip II

2017 ◽  
Author(s):  
Mauricio Drelichman ◽  
Hans-Joachim Voth
Keyword(s):  
Sixteenth Century ◽  
Strong Evidence ◽  
Military Expenditure ◽  
Debt Service ◽  
Fiscal Sustainability ◽  
Short Term ◽  
Systematic Analysis ◽  
Philip Ii ◽  
Long Run

This chapter addresses the sustainability of debt. A systematic analysis based on the International Monetary Fund's (IMF) methodology to evaluate fiscal sustainability shows that Castile was able to service its debts in the long run. While liquidity was scarce during periods of intense warfare, years of relative peace brought large surpluses. The data collected from Castile's annual fiscal accounts produced new yearly series of revenue, military expenditure, short-term debt issues, and short-term debt service. The resulting database spans a full 31-year period—enough to employ modern quantitative techniques. This analysis provides strong evidence that Castile's fiscal position in the second half of the sixteenth century was on a solid footing. The chapter then assesses whether the events that led to major downturns in Castile's financial fortunes could have been anticipated.

Dampak Insentif Pajak Perumahan Terhadap Potensi Penerimaan Pajak Negara Dan Peningkatan Pendapatan Masyarakat : Kasus Provinsi Papua

2016 ◽  
Vol 1 (1) ◽  
pp. 13-22
Author(s):  
Towaf Totok Irawan
Keyword(s):  
Low Income ◽  
House Prices ◽  
Tax Incentives ◽  
High Price ◽  
Short Term ◽  
Primary Input ◽  
State Revenue ◽  
Long Run ◽  
The Government ◽  
The Impact

Until now the government and private sector have not been able to address the backlog of 13.5 million housing units for ownership status and 7.6 million units for residential status. The high price of land has led to the high price of the house so that low-income communities (MBR) is not able to reach out to make a home purchase. In addition to the high price of land, tax factors also contribute to the high price of the house. The government plans to issue a policy for the provision of tax incentives, ie abolish VAT on home-forming material transaction. This policy is expected to house prices become cheaper, so the demand for housing increases, and encourage the relevant sectors to intensify its role in the construction of houses. It is expected to replace the lost tax potential and increase incomes. Analysis of the impact of tax incentives housing to potential state revenue and an increase in people's income, especially in Papua province is using the table IO because in addition to looking at the role each sector can also see the impact on taxes (income tax 21 Pph 25 Pph, VAT), and incomes (wage). Although in the short-term impact is still small, but very rewarding in the long run. Keywords: Backlog, Gross Input, Primary Input, Intermediate Input

Literalism and Moral Status

2018 ◽  
Author(s):  
Carrie Figdor
Keyword(s):  
Moral Status ◽  
Moral Standing ◽  
Short Term ◽  
Long Run ◽  
Moral Boundaries ◽  
Psychological Capacities

Chapter 9 presents the idea that Literalism undermines current social and moral boundaries for moral status. Possession of psychological capacities, moral standing, and respectful treatment are a standard package deal. So either many more beings enjoy moral status than we now think, or the relative superiority of human moral status over other beings is diminished. It introduces the role of psychological ascriptions in drawing social and moral boundaries by examining dehumanization and anthropomorphism. It argues that in the short term Literalism does not motivate us to do more than make minor adjustments to current moral boundaries. We can distinguish the kinds of psychological capacities that matter for moral status from the kinds that best divide nature at its joints. In the long run, however, Literalism prompts us to reconsider the anthropocentric standards that govern current moral boundaries.

scholarly journals Shades between Black and Green Investment: Balance or Imbalance?

2021 ◽  
Vol 13 (9) ◽  
pp. 5024
Author(s):  
 Vítor Manuel de Sousa Gabriel ◽  
María Mar Miralles-Quirós ◽  
José Luis Miralles-Quirós
Keyword(s):  
Risk Factor ◽  
Oil Prices ◽  
Oil Price ◽  
Short Term ◽  
Environmental Indices ◽  
Long Run ◽  
Green Investment ◽  
Bounds Test

This paper analyses the links established between environmental indices and the oil price adopting a double perspective, long-term and short-term relationships. For that purpose, we employ the Bounds Test and bivariate conditional heteroscedasticity models. In the long run, the pattern of behaviour of environmental indices clearly differed from that of the oil prices, and it was not possible to identify cointegrating vectors. In the short-term, it was possible to conclude that, in contemporaneous terms, the variables studied tended to follow similar paths. When the lag of the oil price variable was considered, the impacts produced on the stock market sectors were partially of a negative nature, which allows us to suppose that this variable plays the role of a risk factor for environmental investment.

scholarly journals China’s plastic import ban increases prospects of environmental impact mitigation of plastic waste trade flow worldwide

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zongguo Wen ◽  
Yiling Xie ◽  
Muhan Chen ◽  
Christian Doh Dinga
Keyword(s):  
Environmental Impact ◽  
Environmental Sustainability ◽  
Trade Flow ◽  
Plastic Waste ◽  
Sharp Decline ◽  
Short Term ◽  
Long Run ◽  
Global Environmental ◽  
Waste Trade ◽  
Treatment Structure

AbstractSince the late 1990s, the trend of plastic waste shipment from developed to developing countries has been increasing. In 2017, China announced an unprecedented ban on its import of most plastic waste, resulting in a sharp decline in global plastic waste trade flow and changes in the treatment structure of countries, whose impacts on global environmental sustainability are enormous but yet unexamined. Here, through the life cycle assessment (LCA) method, we quantified the environmental impacts of changes in the flow patterns and treatment methods of 6 types of plastic waste in 18 countries subsequent to the ban. In the short term, the ban significantly improved four midpoint indicators of environmental impact, albeit contributed to global warming. An annual saving of about 2.35 billion euros of eco-cost was realized, which is equivalent to 56% of plastic waste global trade value in 2017. To achieve global environmental sustainability in the long run, countries should gradually realize the transition from export to domestic management, and from landfill to recycling, which would realize eco-costs savings of about 1.54–3.20 billion euros.

Sign in / Sign up

Export Citation Format

Share Document