Inbound Operations Research Articles

Research on Inbound Jobs’ Scheduling in Four-Way-Shuttle-Based Storage System

The four-way-shuttle-based storage and retrieval system is a recent innovative intelligent vertical warehousing system that has been widely applied in manufacturing and e-commerce environments due to its high flexibility and density. As a complex multi-device cooperative operational system, this system features the parallel operation of multiple elevators and four-way shuttles. During large-scale-batch inbound operations, the quality of scheduling solutions for inbound-operation equipment significantly impacts the system’s efficiency and performance. In this paper, a detailed analysis of the inbound-operation process in the system is conducted, taking into consideration the motion characteristics of both the elevators and four-way shuttles. Furthermore, we establish operational time constraints that account for equipment acceleration and deceleration characteristics and introduce a flexible flow-shop-scheduling model to address the scheduling problem in the system. Additionally, we propose an improved genetic algorithm based on double-layer encoding to solve this problem. Comparative experiments with a traditional genetic algorithm and ant-colony algorithm demonstrate the superior efficiency and accuracy of our approach. Finally, the effectiveness of the proposed algorithm is validated through comparisons with large-scale practical experiments.

Scheduling wagons to unload in bulk cargo ports with uncertain processing times

Optimising operations in bulk cargo ports is of great relevance due to their major participation in international trade. In inbound operations, which are critical to meet due dates, the product typically arrives by train and must be transferred to the stockyard. This process requires several machines and is subject to frequent disruptions leading to uncertain processing times. This work focuses on the scheduling problem of unloading the wagons to the stockyard, approaching both the deterministic and the stochastic versions. For the deterministic problem, we compare three solution approaches: a Mixed Integer Programming model, a Constraint Programming model and a Greedy Randomised algorithm. The selection rule of the latter is evolved by Genetic Programming. The stochastic version is tackled by dispatching rules, also evolved via Genetic Programming. The proposed approaches are validated using real data from a leading company in the mining sector. Results show that the new heuristic presents similar results to the company’s algorithm in a considerably shorter computational time. Moreover, we perform extensive computational experiments to validate the methods on a wide spectrum of randomly generated instances. Finally, as managing uncertainty is fundamental for the effectiveness of these operations, distinct strategies are compared, ranging from purely predictive to completely reactive scheduling. We conclude that re-scheduling with high frequency is the best approach to avoid performance deterioration under schedule disruptions, and using the evolved dispatching rules incur fewer deviations from the original schedule.

Throughput optimisation in a coal export system with multiple terminals and shared resources

This work describes a genetic algorithm based approach for the optimization of the Hunter Valley coal export system in Newcastle, Australia. The Port of Newcastle features three coal export terminals, operating primarily in cargo assembly mode. They share a rail network on their inbound operations and a channel on their outbound operations. Maximizing throughput at a single coal terminal, taking into account its layout, equipment and operating policies, is already a challenging problem. However, maximizing throughput of the Hunter Valley coal export system as a whole requires that terminals and inbound/outbound shared resources be considered simultaneously. Existing approaches to solve this and similar problems either lack realism or are computationally too demanding to be useful as an everyday planning tool. We present a parallel genetic algorithm to optimize the integrated system. The algorithm models activities in continuous time and can handle practical planning horizons efficiently. The solutions are on average 17% better than those obtained with the current state-of-the-art method – a constraint programming-based approach – requiring less than 3% of the CPU time. Tests were conducted on 10 instances generated using real world data, with 200 vessels and approximately 270 stockpiles each.

Comparison of supplier quality assurance methods for compound feed manufacturing from efficiency, product consistency and economical point of view

Feed manufacturing and human food production are the main routes of use for agricultural products. The food industryparticularly has intensively implemented the recent quality management principles and developed systems that facilitate the continuous improvement and efficiency of the industrial production. Feed production has taken similar approaches however the intensity of deployment at the manufacturer and the rollout towards its supply chain has shown slower progress. The methods, that the feed manufacturer manages the supplier chain of mainly primer agricultural products according to, have a certain impact on the efficiency of the inbound operations, feed product quality and its consistency as well as on other resources. These methods have been built on sound quality management principles that are stated not only in quality standards but also in relevant regulations. Current study addresses the questions related to the link between supply chain quality management and feed product. The objective of the frontier research was to highlight the theoretical possibilities and benefits of the robust design methodimplemented into animal feed manufacturing dealing with highly variable ingredients.

An evaluation of unethical business practices in Australia's China inbound tourism market

This paper examines the prevalence of unethical practices within the business sector operating in the China to Australia tourism market. The range and nature of the practices are outlined in the context of the structure of outbound operations in China and inbound operations in Australia, taking account of the roles of the respective governments. The prospective impact of the practices on the growth of the market is evaluated. An estimation is provided of the potentially negative impacts of word-of-mouth recommendations on future China to Australia tourism flows. Copyright © 2006 John Wiley &Sons, Ltd.

Export Behavior Of Firms In Singapore's Travel-Agency Industry: Public Policy Implications

A survey of 374 firms in the travel-agency industry was conducted to determine how they can be encouraged to bring more tourists into Singapore. Export theories were used as a framework to differentiate the firms into four progressive stages and compare them with respect to management perception, problems encountered in inbound operations, export- supporting factors, and firm characteristics. The results indicated that different factors, particularly managerial ones, appeared to be important at each stage, thus enabling the development of profiles of firms in each corresponding stage. This finding has public policy implications.