Wyniki wyszukiwania - BazTech

1

Optimal decision making for empty container management at seaport yard

Vinh Ngo Quang, You Sam-Sang You, Long Le Ngoc Bao, Kim Hwan-Seong

LogForum

|

2023

|

Vol. 19, no. 1

75--89

EN

Background: In global trade, shipping companies are forced to manage empty containers due to imbalances in international trade activities. For decision-makers, the problems require considering restrictions and an uncertain environment and repositioning or leasing the containers to satisfy the rapidly changing global demands regardless of the epidemic outbreak's impact on the seaport. The proposed approach can help decision-makers manage the empty container in port yards more effectively under market uncertainty by employing the Bellman optimality principle for the stochastic dynamic system. Methods: A stochastic production planning model is employed to cope with uncertainty and unexpected events to ensure a robust management strategy. Ito's formula describes the dynamic model for solving a stochastic differential equation. This paper uses stochastic optimal control theory to deal with efficient empty container management at the port yard. The findings have revealed the effectiveness of the proposed framework, which will provide a decision-making support scheme for efficient port operations. Results: The presented algorithm is realized by a novel approach, employing the Hamilton-Jacobi-Bellman (HJB) equation for optimal stochastic control problems. When comparing the model with and without uncertainty events, the gap is just about 0.04 %, proving the robustness of the proposed model. The results provide a decision support system for port managers when managing the empty container in the seaport yard. Conclusions: The proposed model not only figures out the optimal ordering of empty containers for each cycle but also points out the optimal safety stock level. Using a stochastic optimization approach, decision-makers can implement a strategic management policy to optimize seaport operational costs under market disruptions.

2

A note on inventory model for ameliorating items with time dependent second order demand rate

Panda G. C., Sahoo S., Sukla P K

LogForum

|

2013

|

Vol. 9, no. 1

43--49

EN

Background: This paper is concerned with the development of ameliorating inventory models. The ameliorating inventory is the inventory of goods whose utility increases over the time by ameliorating activation. Material and Methods: This study is performed according to two areas: one is an economic order quantity (EOQ) model for the items whose utility is ameliorating in accordance with Weibull distribution, and the other is a partial selling quantity (PSQ) model developed for selling the surplus inventory accumulated by ameliorating activation with linear demand. The aim of this paper was to develop a mathematical model for inventory type concerned in the paper. Numerical examples were presented show the effect of ameliorating rate on inventory polices. Results and Conclusions: The inventory model for items with Weibull ameliorating is developed. For the case of small ameliorating rate (less than linear demand rate), EOQ model is developed, and for the case where ameliorating rate is greater than linear demand rate, PSQ model is developed.

PL

Wstęp: Praca porusza zagadnienie rozwoju modeli zarządzania zapasem dla produktów przetworzonych. Dotyczy ona produktów, których użyteczność wzrasta wraz z upływem czasu poprzez zastosowanie procesów ich obróbki ulepszania. Materiały i metody: W pracy oparto się na dwóch modelach: pierwszy z nich to model ekonomicznej wielkości zamówienia (EOQ) dla towarów, których użyteczność wzrasta zgodnie z dystrybucją Weibulla, natomiast drugi to model częściowej sprzedaży (PSQ) nadwyżek zapas nagromadzonych poprzez aktywności mające poprawę ich użyteczności i charakteryzujące się popytem liniowym. Celem tej pracy było wypracowanie matematycznego modelu dla zarządzania zapasem dla typu towarów omawianych tutaj. Praktyczne działanie modelu przedstawiono na zaprezentowanych przykładach. Wyniki i wnioski: Wypracowano model zarządzania zapasem towarów podlegających wzroście wartości Weibulla. Dla przypadku, gdy wskaźnik poprawy przybierał niską wartość (mniejszą niż wskaźnik popytu liniowego) opracowano model EOQ, natomiast dla przypadku, gdy ten wskaźnik był większy niż wskaźnik popytu liniowego, opracowano model PSQ.

3

Reverse logistics inventory model for reusable product parts

Jodejko-Pietruczuk A., Plewa M.

Logistics and Transport

|

2012

|

Vol. 14, No. 1

111-118

EN

Until recently logistics systems supported only processes carried out in classical material flow from producer to final user. Recently it has been a remarkable growth of interest in optimizing logistics processes that supports recapturing value from used goods. The process of planning, implementing, and controlling the efficient, cost effective flow of raw materials, in-process inventory, finished goods and related information from the point of consumption to the point of origin for the purpose of recapturing value or proper disposal is called reverse logistics. Reuse of product parts can bring direct advantages to the company because it reduces costs associated with acquiring new components. Main goal of this paper is to create the reverse logistics inventory model that uses the reliability theory to describe re-usability of product parts with assumption that recovered components are used in a production process but they aren't as good as new ones. The model allows to estimate the potential profits of the reusing policy in production and inven-tory management. It gives the base to optimize some of the process parameters: the threshold work time of returns, the warranty period for products containing reused elements or new components order size.

4

Effect of demand boosting policy on optimal inventory policy for imperfect lot size with backorder in fuzzy environment

Yadav D., Singh S. R., Kumari R.

Control and Cybernetics

|

2012

|

Vol. 41, no. 1

191-212

EN

This paper investigates an Economic Order Quantity (EOQ) model with backorder by taking imprecise demand rate with dependence upon the frequency of advertisement. The formulated model also incorporates learning effects on percentage of defective items present in each lot. Due to imprecision in demand, the obtained profit function is fuzzy. To determine the optimal values, we determine the equivalent crisp profit function by applying the signed distance method. Optimal order quantity and backorder level are obtained by using algebraic method in place of differential calculus. A numerical example is used to study the behavior of the model with respect to different inventory parameters. All calculations are performed with MATLAB 7.4.