Managing loading and discharging operations at cross-docking terminals

Abstract A cross-docking terminal is a relevant node within a distribution chain. Actually, at this intermediate logistic platform between suppliers and retailers, incoming flows of possible different commodities are consolidated into single shipments, with respect to the retailers\x92 orders, and directly delivered, skipping thus the storage phase. In such a context the synchronization of the inbound and outbound trucks is a necessary condition to guarantee fast and congestion-free transshipment operations. In this paper we propose a Mixed Integer Linear Program and a heuristic algorithm for managing the loading and discharging operations, with the aim of minimizing the completion time of the whole transshipment process

Combined quay crane assignment and quay crane scheduling with crane inter-vessel movement and non-interference constraints

Integrated models of the quay crane assignment problem (QCAP) and the quay crane scheduling problem (QCSP) exist. However, they have shortcomings in that some do not allow movement of quay cranes between vessels, others do not take into account precedence relationships between tasks, and yet others do not avoid interference between quay cranes. Here, an integrated and comprehensive optimization model that combines the two distinct QCAP and QCSP problems which deals with the issues raised is put forward. The model is of the mixed-integer programming type with the objective being to minimize the difference between tardiness cost and earliness income based on finishing time and requested departure time for a vessel. Because of the extent of the model and the potential for even small problems to lead to large instances, exact methods can be prohibitive in computational time. For this reason an adapted genetic algorithm (GA) is implemented to cope with this computational burden. Experimental results obtained with branch-and-cut as implemented in CPLEX and GA for small to large-scale problem instances are presented. The paper also includes a review of the relevant literature

An evolutionary approach to a combined mixed integer programming model of seaside operations as arise in container ports

This paper puts forward an integrated optimisation model that combines three distinct problems, namely berth allocation, quay crane assignment, and quay crane scheduling that arise in container ports. Each one of these problems is difficult to solve in its own right. However, solving them individually leads almost surely to sub-optimal solutions. Hence, it is desirable to solve them in a combined form. The model is of the mixed-integer programming type with the objective being to minimize the tardiness of vessels and reduce the cost of berthing. Experimental results show that relatively small instances of the proposed model can be solved exactly using CPLEX. Large scale instances, however, can only be solved in reasonable times using heuristics. Here, an implementation of the genetic algorithm is considered. The effectiveness of this implementation is tested against CPLEX on small to medium size instances of the combined model. Larger size instances were also solved with the genetic algorithm, showing that this approach is capable of finding the optimal or near optimal solutions in realistic times

Inter-organizational knowledge transfer:current issues and future prospects

Many papers have been published recently in the fields of strategy and international business research incorporating the role of organizational knowledge as a basis of firm competitive advantage. While such knowledge is normally developed within the firm, it is important that firms possess the ability to learn from others in order to meet the increasing pace of competition. Knowledge transfer, defined here as an event through which one organization learns from the experience of another, has thus become an important research area within the broader domain of organizational learning and knowledge management. This paper presents a theoretical framework, identifies key themes covered by the six articles included in the Special Issue on Inter-Organizational Knowledge Transfer, and then discusses priorities for future research

Bone metastases in breast cancer: higher prevalence of osteosclerotic lesions

Purpose. It is well known that bone metastases from breast cancer usually show osteolytic changes. We retrospectively analysed the computed tomography (CT) appearance of bone metastases to quantify the distribution of lytic, mixed and sclerotic changes in a series of patients presenting with neoplastic bone involvement from breast cancer. Materials and methods. Between 1996 and 2005, 468 women with a diagnosis of breast cancer were referred to our department for staging or follow-up CT examinations. Staging CT examinations detected systemic metastases in 142/468 patients, 60 of which had bone involvement. Patients with a second primary turnout or bone metabolic disorders were excluded from this retrospective analysis. Results. In patients with bone metastases, CT identified 18 with osteolytic lesions (30%), 32 with osteosclerotic lesions (53.3%) and ten with mixed lesions (16.7%). Analysis of the cases observed for the first time during the 1996-2000 period showed osteolytic lesions in 53.6% (15/28), osteosclerotic lesions in 32.1% (9/28) and mixed lesions in 14.3% (4/28). Results were 9.4% (3/32), 71.9% (23/32) and 18.7% (6/32), respectively, for the same groups in the 2001-2005 period. Histological analysis of all cases included 81.9% of infiltrative ductal carcinoma, 11.2% of infiltrative lobular carcinoma, 3.7% of ductal lobular mixed carcinoma and 3% of medullar carcinoma. We found no statistically significant correlation between histological type of breast cancer and radiological appearance of bone metastasis. A significant difference between patients treated with or without zoledronic acid was observed, with a higher prevalence of osteosclerotic lesions in the former group of patients (p < 0.05). Conclusions. We observed an increasing prevalence of osteosclerotic bone metastasis when comparing the 1996-2000 period with the 2001-2005 period. The significance of these distribution changes is not clear. However, we found a significant correlation of osteosclerotic lesions with zoledronic acid treatment. The advent of third generation bisphosphonates may have changed the CT appearance of bone metastasis from breast cancer