scholarly journals Supplier Replacement Model in a One-Level Assembly System under Lead-Time Uncertainty

2020 ◽  
Vol 10 (10) ◽  
pp. 3366
Author(s):  
Hasan Murat Afsar ◽  
Oussama Ben-Ammar ◽  
Alexandre Dolgui ◽  
Faicel Hnaien
Keyword(s):  
Lead Time ◽  
Probability Distributions ◽  
Assembly System ◽  
Lead Times ◽  
Real Component ◽  
Price Negotiation ◽  
Purchase Cost ◽  
Replacement Model ◽  
Replenishment Policy ◽  
Lead Time Uncertainty

Supplier selection/replacement strategies, purchasing price negotiation and optimized replenishment policies play a key role in efficient supply chain management in today’s dynamic market. Their importance increases even more in Industry 4.0. In this paper, we propose a joint model of replenishment planning and purchasing price negotiation in the context of supplier replacement in a one-level assembly system (OLAS) producing one type of finished product. The real component lead times are stochastic. There is consequently a non-negligible risk that the assembly process may be stopped if all components for assembly are not delivered on the due date. This incurs inventory-related costs, holding and backlogging, which should be minimized. We consider a set of suppliers characterized by their prices and the probability distributions of their lead-times, and we present a model and an approach that optimize not only replenishment policy, but also purchasing prices. For a given unit, it is possible to model several alternative suppliers with alternative pricing and lead-time uncertainties, and evaluate their impacts on the total cost: composed of holding, backlogging and purchasing costs for the assembly system. The findings of this study indicate that it can be beneficial to pay suppliers an additional purchase cost in order to reduce the holding and backlogging costs related to uncertainty. In consequence, decision makers can use the proposed approach to negotiate prices and delivery delays or to select suppliers.

scholarly journals Integration of additional purchase cost to reduce the lead time uncertainty for one level assembly system

2013 ◽  
Vol 46 (9) ◽  
pp. 383-388
Author(s):  
F. Hnaien ◽  
H.M. Afsar ◽  
A. Dolgui
Keyword(s):  
Lead Time ◽  
Assembly System ◽  
Time Uncertainty ◽  
Purchase Cost ◽  
Lead Time Uncertainty

scholarly journals Supplier Replacement Model in a One-Level Assembly System under Lead-Time Uncertainty

2020 ◽  
Author(s):  
Hasan Murat Afsar ◽  
Oussama Ben-Ammar ◽  
Alexandre Dolgui ◽  
Faicel Hnaien
Keyword(s):  
Lead Time ◽  
Supplier Selection ◽  
Assembly System ◽  
Assembly Process ◽  
Optimal Assignment ◽  
Sources Of Uncertainty ◽  
Replacement Model ◽  
Lead Time Uncertainty ◽  
The Impact ◽  
Component Order

Supplier selection/replacement strategies and optimized purchasing policies play a key role in efficient supply chain management in today’s dynamic market. Here we study supplier replacement in a one-level assembly system (OLAS) producing one type of finished product. To assemble the product, we need to provide multi-type components, but assembly will be interrupted if any single component is missing, and incoming units will get hoarded until the missing component arrives. The assembly process can be interrupted by various sources of uncertainty, including delays in component deliveries. There is consequently a non-negligible risk that the assembly process may get stopped any moment. This brings inventory-related costs, which should be minimized. Here we consider discrete lead-time distributions to mimic industry-world reality. We present a model that takes into account not only optimal assignment of component order release dates but also replacement of a critical supplier. For a given unit, we model several alternative suppliers with alternative pricing and lead-time uncertainties, and we evaluate the impact on the total assembly system. For a more general case where several suppliers may be replaced, we propose a genetic algorithm.

scholarly journals The Impact of Lead Time Uncertainty on Supply Chain Performance Considering Carbon Cost

2019 ◽  
Vol 11 (22) ◽  
pp. 6457
Author(s):  
Li ◽  
Fei ◽  
Zhou ◽  
Gajpal ◽  
Chen
Keyword(s):  
Supply Chain ◽  
Lead Time ◽  
Lead Times ◽  
Supply Chain Performance ◽  
Chain Model ◽  
Carbon Cost ◽  
Inventory Costs ◽  
Time Uncertainty ◽  
Supply Chain Model ◽  
Lead Time Uncertainty

In supply chain operation practices, lead time uncertainty is a common management issue. Uncertain lead time can lead to increased inventory costs and unstable service levels, which will directly affect the overall operation performance of the supply chain. While considering environmental performance in supply chain, it is important to understand how an uncertain lead time will affect sustainable performance. In this paper, we constructed a supply chain model with stochastic lead time and explored the relationship between uncertain lead time and supply chain performance. We considered carbon cost, inventory cost, and service level as a supply chain performance. System dynamics methodology was employed to observe and explore the dynamic change trend of the overall performance in the complicated supply chain model. This was done under both different levels of lead time standard deviation and different order policies. The results demonstrate how stochastic lead times can significantly increase inventory costs and carbon costs. Therefore, we propose appropriate ordering policies which mitigate the negative impacts of stochastic lead times.

A MODEL FOR AN ASSEMBLY SYSTEM UNDER LEAD TIME UNCERTAINTY

2006 ◽  
Vol 39 (3) ◽  
pp. 241-246
Author(s):  
S.S. Chauhan ◽  
A. Dolgui ◽  
M.-A. Louly ◽  
J.-M. Proth
Keyword(s):  
Lead Time ◽  
Assembly System ◽  
Time Uncertainty ◽  
Lead Time Uncertainty

scholarly journals A Spatiotemporal Convolutional Gated Recurrent Unit Network for Mean Wave Period Field Forecasting

2021 ◽  
Vol 9 (4) ◽  
pp. 383
Author(s):  
Ting Yu ◽  
Jichao Wang
Keyword(s):  
Lead Time ◽  
Wave Period ◽  
Data Driven ◽  
Lead Times ◽  
Proposed Model ◽  
Data Driven Approach ◽  
Mean Wave Period ◽  
Scattering Index ◽  
Gated Recurrent Unit ◽  
Methods Numerical

Mean wave period (MWP) is one of the key parameters affecting the design of marine facilities. Currently, there are two main methods, numerical and data-driven methods, for forecasting wave parameters, of which the latter are widely used. However, few studies have focused on MWP forecasting, and even fewer have investigated it with spatial and temporal information. In this study, correlations between ocean dynamic parameters are explored to obtain appropriate input features, significant wave height (SWH) and MWP. Subsequently, a data-driven approach, the convolution gated recurrent unit (Conv-GRU) model with spatiotemporal characteristics, is utilized to field forecast MWP with 1, 3, 6, 12, and 24-h lead times in the South China Sea. Six points at different locations and six consecutive moments at every 12-h intervals are selected to study the forecasting ability of the proposed model. The Conv-GRU model has a better performance than the single gated recurrent unit (GRU) model in terms of root mean square error (RMSE), the scattering index (SI), Bias, and the Pearson’s correlation coefficient (R). With the lead time increasing, the forecast effect shows a decreasing trend, specifically, the experiment displays a relatively smooth forecast curve and presents a great advantage in the short-term forecast of the MWP field in the Conv-GRU model, where the RMSE is 0.121 m for 1-h lead time.

scholarly journals A Preliminary Look at the Social Perspective of Warn-on-Forecast: Preferred Tornado Warning Lead Time and the General Public’s Perceptions of Weather Risks

2011 ◽  
Vol 3 (2) ◽  
pp. 128-140 ◽  
Author(s):  
S. Hoekstra ◽  
K. Klockow ◽  
R. Riley ◽  
J. Brotzge ◽  
H. Brooks ◽  
...  
Keyword(s):  
Lead Time ◽  
Stated Preference ◽  
The United States ◽  
Public Understanding ◽  
Lead Times ◽  
Present System ◽  
The Public ◽  
Tornado Warnings ◽  
Tornado Warning ◽  
Weather Risks

Abstract Tornado warnings are currently issued an average of 13 min in advance of a tornado and are based on a warn-on-detection paradigm. However, computer model improvements may allow for a new warning paradigm, warn-on-forecast, to be established in the future. This would mean that tornado warnings could be issued one to two hours in advance, prior to storm initiation. In anticipation of the technological innovation, this study inquires whether the warn-on-forecast paradigm for tornado warnings may be preferred by the public (i.e., individuals and households). The authors sample is drawn from visitors to the National Weather Center in Norman, Oklahoma. During the summer and fall of 2009, surveys were distributed to 320 participants to assess their understanding and perception of weather risks and preferred tornado warning lead time. Responses were analyzed according to several different parameters including age, region of residency, educational level, number of children, and prior tornado experience. A majority of the respondents answered many of the weather risk questions correctly. They seemed to be familiar with tornado seasons; however, they were unaware of the relative number of fatalities caused by tornadoes and several additional weather phenomena each year in the United States. The preferred lead time was 34.3 min according to average survey responses. This suggests that while the general public may currently prefer a longer average lead time than the present system offers, the preference does not extend to the 1–2-h time frame theoretically offered by the warn-on-forecast system. When asked what they would do if given a 1-h lead time, respondents reported that taking shelter was a lesser priority than when given a 15-min lead time, and fleeing the area became a slightly more popular alternative. A majority of respondents also reported the situation would feel less life threatening if given a 1-h lead time. These results suggest that how the public responds to longer lead times may be complex and situationally dependent, and further study must be conducted to ascertain the users for whom the longer lead times would carry the most value. These results form the basis of an informative stated-preference approach to predicting public response to long (>1 h) warning lead times, using public understanding of the risks posed by severe weather events to contextualize lead-time demand.

scholarly journals Tornado Warnings, Lead Times, and Tornado Casualties: An Empirical Investigation

2008 ◽  
Vol 23 (2) ◽  
pp. 246-258 ◽  
Author(s):  
Kevin M. Simmons ◽  
Daniel Sutter
Keyword(s):  
United States ◽  
Lead Time ◽  
Empirical Investigation ◽  
Conventional Wisdom ◽  
Lead Times ◽  
Time Intervals ◽  
Consistent Effect ◽  
Tornado Warnings ◽  
The Relationship

Abstract Conventional wisdom holds that improved tornado warnings will reduce tornado casualties, because longer lead times on warnings provide extra opportunities to alert residents who can then take precautions. The relationship between warnings and casualties is examined using a dataset of tornadoes in the contiguous United States between 1986 and 2002. Two questions are examined: Does a warning issued on a tornado reduce the resulting number of fatalities and injuries? Do longer lead times reduce casualties? It is found that warnings have had a significant and consistent effect on tornado injuries, with a reduction of over 40% at some lead time intervals. The results for fatalities are mixed. An increase in lead time up to about 15 min reduces fatalities, while lead times longer than 15 min increase fatalities compared with no warning. The fatality results beyond 15 min, however, depend on five killer tornadoes and consequently are not robust.

The MPS parameterization under lead time uncertainty

2004 ◽  
Vol 90 (3) ◽  
pp. 369-376 ◽  
Author(s):  
Mohamed-Aly Ould-Louly ◽  
Alexandre Dolgui
Keyword(s):  
Lead Time ◽  
Time Uncertainty ◽  
Lead Time Uncertainty
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