An Optimization Model for Tramp Ship Scheduling considering Time Window and Seaport Operation Delay Factors

The quantity of electrical coal transported through the tramp shipping network is increasing due to the high demands. This trend has increased the scheduling difficulty combined with the underdevelopment of the private thermal power plant port. The high coal consumption and low port storage capacity requires the scheduling of the tramp ship to be on a strict time window to ensure the continuous operation of the thermal power plant. The low port unloading capacity often leads to the port congestion and delay of the unloading operation. This paper develops a mixed-integer-programming model for the optimization of the tramp ship scheduling to reduce the total operation cost, including the transportation cost and the unloading waiting cost, and the branch-and-price algorithm is adopted to solve this large-scale model. The model and algorithm are tested with historical operation data from the thermal power plant in the southern coastal areas of China. The optimized scheme significantly reduces the total operation cost by reducing the unloading waiting time and the number of active vessels in certain periods. The results also demonstrate the algorithm improvement in the aspects of the optimization quality and efficiency comparing with the heuristic solution.

TIME ACCELERATION ANALYSIS AND OPTIMAL COST OF HOSPITAL HOSPITAL DEVELOPMENT PROJECT ON SHIP BUILDING USING CRITICAL PATH METHOD (CASE STUDY: PT. PAL INDONESIA (PERSERO))

Hospital Auxiliary Ship is an Indonesian Navy ship produced by PT. PAL Indonesia (Persero). The construction of this BRS ship was very time consuming and one of the main parts of the ship building project was the construction of the hull structure. In relation to time and production costs, the shipyard must be as efficient as possible in the use of time in each activity or activity, so that costs can be minimized from the original plan. Acceleration of the total duration in a project is done by accelerating critical activities in the project. To find out which are the critical activities of a project, the Critical Path Method (CPM) technique is used; namely by drawing a Network Diagram of the project. By using the CPM method in scheduling a ship hull construction project, it can be seen which activities should take precedence so as not to experience delays and waste. After that, the crashing method is carried out by increasing work hours (overtime) which aims to speed up the time of the project. The results of research for activities that are in the initial critical path with the CPM method can be seen as activities A, C, H, M, R, W, AB, AC, AD, AI, AP, AT, BA, BJ, BN. After accelerating, the critical path activities include activities A, C, H, M, R, W, X, AC, AD, AI, AP, AT, BA, BH, BO. Calculation of the project during initial conditions with Early working days without using overtime hours PT PAL Indonesia (Persero) costs Rp. 5,299,631,000, - while the Crashing Method is through the addition of 1 hour / day overtime so that the project implementation can be accelerated from the initial implementation of 450 days to 412 days and PT. PAL Indonesia (Persero) issued a project cost of Rp. 5,323,752,480, -. Keywords: Hospital Support Ship, Scheduling, CPM, Crashing.

Determining inland logistics service attributes: a case study of Chinese landlocked regions

Purpose Recently, inland Chinese regions have become the major manufacturing base for most manufacturing firms. Accordingly, with this change, many shipping companies attempted to provide proper logistics service activities to maintain their business. Hence, this study aims to empirically examine the logistics service preference segments for Chinese landlocked regions from a manufacturer's perspective. By understanding these attributes, not only shipping companies but also logistics companies can provide proper service to their customers. Design/methodology/approach The preliminary logistics service attributes are determined using an interview and in-depth questionnaire with logistics experts from the local private and government sectors in southwest China and few international logistics coordinators. This study conducted importance-performance analysis (IPA) and used a customer dissatisfaction attitude index to evaluate the priorities for improving logistics service attributes. Cluster analysis is subsequently performed to group respondents on the basis of their factor scores. Findings Five crucial logistics service dimensions were identified by the factor analysis, namely, packing and storage, logistics supporting, logistics information, transportation planning and information inquiry. The results also revised the IPA model. The top five service attributes that needed to be improved were carrier selection, ship scheduling inquiry, route planning and inquiry, cargo receiving station and freight forwarding. By applying the factor analysis, this study reduced the 27 logistics attributes derived from the literature review to five underlying critical factors. Originality/value This study contributes to the inland logistics by investigating the preferences of manufacturers in Chinese landlocked regions. Moreover, in land logistics in China is lacking in the literature; hence, several important implications can be derived from this study's results.

Tramp Ship Routing and Scheduling with Speed Optimization Considering Carbon Emissions

The International Maritime Organization (IMO) proposed to reduce the total CO2 emissions of the maritime sector by 50% by 2050, and strive to gradually achieve the zero-carbon target. Therefore, shipping companies need to consider environmental impacts while pursuing benefits. In view of the tramp ship scheduling with speed optimization problem, considering carbon emissions, the configuration of owner ships and charter ships, and the impact of sailing speed on ship scheduling with the target of minimizing the total costs of shipping companies, multi-type tramp ship scheduling and speed optimization considering carbon emissions is established. A genetic simulated annealing algorithm based on a variable neighborhood search is proposed to solve the problem. Firstly, the ship type is matched with the cargo. Then the route is generated according to the time constraint, and finally, the neighborhood search strategy is adopted to improve the solution quality. The effectiveness of the proposed model and algorithm is verified by an example, which also confirms that ship scheduling and sailing speed joint optimization can reduce costs and carbon emissions. Research results can not only deepen the study of the theory of tramp scheduling but also to effectively solve the tramp shipping schedule considering carbon emissions problems faced by companies to provide theoretical guidance.