On inland waterways the ship resistance and propulsive characteristics are strictly related to the depth of the waterway, thus it is important to have an understanding of the influence of water depth on ship hydrodynamic characteristics. Therefore, accurate predictions of hydrodynamic forces in restricted waterways are required and important. The aim of this paper is investigating the capability of the commercial unsteady Reynolds–Averaged Navier–Stokes (RANS) solver to predict the influence of water depth on ship resistance. The volume of fluid method (VOF) is applied to simulate the free surface flow around the ship. The hull resistance in shallow and deep water is compared. The obtained numerical results are validated against related experimental studies available in the literature.

Shrimp products play a vital role in the international trade of fisheries products. The main suppliers for shrimp products are developing nations such as Vietnam, Thailand, Bangladesh and other countries in Southeast Asia. Among them, Vietnam is one of the largest exporters of shrimp products, and developed countries, especially the United States, Europe and Japan, are key importers of shrimp in the global market. An increase in the demand for shrimp products has led to the development of traceability regulations in developed countries. In this study, Pressure-State-Response (PSR) concepts are applied to evaluate the implementation responses of traceability regulations by exporting countries to meet the mandatory requirements of global markets. The evaluation was based on the prepared questions that were developed to allow comparison of specified indicators in the traceability regulations of importing countries and those of Vietnam. The examination showed that importing countries have introduced stringent traceability regulations via legislation and quality assurance practices. Regarding measures taken by exporting countries, Vietnam has introduced traceability regulations for both shrimp and other seafood products. Thus, Vietnamese regulations were found to satisfy the regulations of importing countries. However, the implementation of these regulations has faced a number of challenges, largely because of complicated of distribution channels, small-scale production, price discrimination and a lack capital to apply for international certificates.

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This study investigated the effects of applications of international quality assurance certification at farm level on implementation of traceability along the shrimp supply chain with the evidences from Vietnam. Descriptive statistics was explored to compare in terms of products, information flows, financial efficiency, and willingness to implement traceability between certified and non-certified quality assurance shrimp farms. Binary logistics model was applied to examine the effects of applications of international quality assurance certification and other factors to the willingness to implement traceability of shrimp farmers. Found results showed that the applications of international quality assurance certification of shrimp farmers supported traceability of shrimp products among stakeholders in the supply chain. The certified farmers indicated a higher willingness to implement traceability. However, the profitability of those applications for shrimp farmers was not statistically found. The economics incentives, including farm-gate price differentiation and minimization of production costs should be carefully considered.

The paper discusses the length to beam (L/B) ratio effects on ship resistance at three different Froude numbers using unsteady RANSE simulation. First, the JBC ship model was used as an initial hull form for verification and validation of predicted ship resistance results with measured data, and then the influence of the L/B ratio on ship resistance was carried out. Ship hull forms with different L/B ratios were produced from the initial one by using the Lackenby method. The numerical results obtained show the L/B ratio’s effect on ship resistance. Increases of the L/B ratio led to gradual reduction of the total ship resistance and vice versa. Analysis of the changing of the resistance components indicates that the pressure resistance changes are considerably larger than the frictional one. Finally, the paper analyses the difference in the flow field around the hull of the ship with variation of the L/B ratio to fully understand the physical phenomenon in the change of ship resistance at different L/B parameters.