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- Henesey, Lawrence, et al.
(författare)
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Smart Container Stacking in the Yard
- 2021
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Ingår i: International Conference on Harbour, Maritime and Multimodal Logistics Modelling and Simulation. - : CAL-TEK. - 9788885741591 ; , s. 37-44
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Konferensbidrag (refereegranskat)abstract
- The workloads at seaport container terminals are increasing; thus, to enhance performance, the focus on improving container stacking is argued to be an integral factor that should be studied. The main problem is the number of unproductive moves of handling containers. A well-planned stacking area is argued to be a key requirement in order to increase the performance of the terminal operations and assist in maximum utilization of existing resources. In this work, we investigated and then propose the best possible solution by evaluating GAs in order to minimize the unproductive moves often witnessed in terminal operations. A discrete-event simulation CSS model has been developed to study the inbound container stacking that considers in the model the following: the working of the yard crane, Automated Guided Vehicles, delivery trucks and obtain the simulation-based results of GA. We propose a mathematical model to minimize the container handling costs during stacking and retrieval operations in the container terminal yard. © 2021 The Authors.
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| 3. |
- Kittipittayakorn, Cholada
(författare)
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Prediction of Life Expectancy at Birth in Europe: A Comparison of Univariate and Multivariate Time Series Forecasting
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background The rising life expectancy at birth marks a significant victory for modern medicine and public health initiatives. Advances in medical technology, improved healthcare services, enhanced nutrition, and greater awareness of health and wellness have all contributed to prolonging the average human lifespan. In recent decades, many countries, particularly in Europe, have seen life expectancy at birth surpass previous historical limits. This increase significantly affects public health, economics, and social structures. As populations age, the demand for healthcare services, long-term care, and pensions increases, adding strain on both public and private sectors. These shifts necessitate modifications in social services, healthcare delivery, and pension plans to accommodate an older demographic. Therefore, accurate forecasts of life expectancy at birth are crucial for governments and organizations to make well-informed decisions and effectively plan for future demographic changes. Forecasting life expectancy at birth has become central to demographic research due to its pivotal role in planning and policy formulation.Methods Numerous studies have introduced various methods and techniques to predict future life expectancy, utilizing a broad array of statistical tools and models. These methods range from simple linear projections based on historical data to complex models that incorporate multiple variables and sophisticated statistical techniques. Despite the availability of numerous forecasting methods, there is a notable gap in the literature concerning systematic evaluations of these techniques, as most studies focus on creating new forecasting methods or refining existing models to increase predictive accuracy. This study addresses this gap by examining the performance of two principal econometric models, namely the Autoregressive Integrated Moving Average (ARIMA) and the Vector Error Correction (VEC) model, in predicting future life expectancy at birth in Europe. These models represent different approaches to time series forecasting, each with distinct assumptions and capabilities. This research used Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and the Diebold-Mariano (DM) tests to compare the forecast accuracy of the two models.Results The results from RMSE and MAE showed that the ARIMA model better predicted future life expectancy at birth for half of the European countries in this study, while the VEC model was more accurate for the other half. The DM test indicated statistically significant differences in forecast accuracy between the ARIMA and VEC models in some European countries.Conclusions This study aimed to determine which model delivers the most accurate and reliable predictions by comparing these models in predicting future life expectancy at birth across several European countries. Such insights are crucial for policymakers, planners, and researchers developing health systems and social policies tailored to an aging European population.
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| 4. |
- Shahmardani, Mahdieh, et al.
(författare)
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Numerical simulation of buckling and post-buckling behavior of a central notched thin aluminum foil with nonlinearity in consideration
- 2020
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- In thin notched sheets under tensile loading, wrinkling appears on the sheet surface, specifically around the cracked area. This is due to local buckling and compression stresses near the crack surfaces. This study aims to numerically study the buckling behavior of a thin sheet with a central crack under tension. A numerical model of a notched sheet under tensile loading is developed using the finite element method, which considers both material and geometrical nonlinearity. To overcome the convergence problem caused by the small thickness-to-length/width ratio and to stimulate the buckling, an imperfection is defined as a small perturbation in the numerical model. Both elastic and elasto-plastic behavior are applied, and the influence of them is studied on the critical buckling stress and the post-buckling behavior of the notched sheet. Numerical results for both elastic and elasto-plastic behavior reflect that very small perturbations need more energy for the activation of buckling mode, and a higher buckling mode is predominant. The influences of different parameters, including Poisson’s ratio, yield limit, crack length-to-sheet-width ratio, and the sheet aspect ratio are also evaluated with a focus on the critical buckling stress and the buckling mode shape. With increase in Poisson’s ratio. First, the critical buckling stress reduces and then remains constant. A higher yield limit results in increases in the critical buckling stress, and no change in the buckling mode shape while adopting various crack length-to-sheet-width ratios, and the sheet aspect ratio changes the buckling mode shape.
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