مجله علوم و فنون دریایی
سال بیست و دوم شماره 4 (زمستان 1402)

Estimating the required propulsive power of a vessel at early stage of design is important from two aspects, which are estimating the weight of the machinery as a function of required power and estimating the amount of fuel needed to determine the initial capacity of the vessel. This approximation can be based on empirical formulas, data of similar ships or diagrams deduced from statistical data for various types and sizes of ships. Current empirical formulas for estimating ship power are only limited to very few general equations and are inaccurate for specific type of vessels. In this study, by using 90 container ship data and multiple linear regression method, several statistical models were prepared and statistically analyzed considering the influence of the main parameters of the vessels on the required amount of power, and finally a suitable formula extracted. Evaluation of the extracted formula indicates acceptable accuracy for the container ships which can be used to estimate the required power of container ships within the range of this formula.

One of the most important concerns in fisheries management is finding suitable areas and zones to invest in aquaculture with a sustainable development approach. The use of GIS is one of the most important factors for success in aquaculture development.  Site selection of sturgeon breeding and farming locations was carried out using the facilities of GIS and data analysis was performed using fuzzy model, hierarchical analysis process and the fuzzy criteria AHP. The main criteria used in this study were ecological, climatic, natural and environmental, economic and social factors, barriers and limitations and sensitive habitats. Then, using the weighting method, a competency map was prepared and with considering the merit and applying the average of the merit value of each place, the priority of each place was determined. Combining this method with fuzzy logic and application in GIS environment and also taking into consideration the weight and relative importance of each feature and option, has increased the efficiency of this method. According to the results, the highest weight was awarded to ecological factors (0.321), the next ranks were awarded to climate (0.205), economic and social (0.179), natural (0.167) factors and barriers and restrictions (0.129), respectively. The most suitable areas for the development of sturgeon breeding and culture centers are located in the northern, northeastern and eastern regions of the Khuzestan province. The most unsuitable sites are located in the southern regions of the province.

Ports play a key intermediate role between maritime and other systemes of transport. Due to the many activities that are carried out in ports nowadays, there are various dangers at any point in port and working in the port is considered a high risk job. In this research, the factors affecting occurrence of work accidents in Shahid Rajaee Port were identified and prioritized. At first, the factors were identified using numerous interviews and meetings with operational managers, experts and HSE professionals and also review previous research and literature and then using Delphi technique they were selected. Prioritize the factors was done using AHP method and distributing 105 questionnaires which out of them 86 valid ones collected. The statistical population of this study are the managers and experts of HSE and operation Shahid Rajaee Port. Since research findings can be used to reduce number of work accidents in Shahid Rajaee Port, it is considered as an applied research in terms of purpose and is descriptive, in terms of the type and nature of the research. The importance and prioritization of each of the factors affecting the occurrence of workplace accidents were identified using the (AHP) hierarchical analysis process. The results showed that high risk-taking of the employees, excessive fatigue, inadequate supervision of contractors and staff / workers, respectively, were the first to third priority in influencing factors of work accidents in Shahid Rajaee Port.

Polychaetes are important in determining the environmental status of seabed and their role in the food chain. Sampling of sediments in three areas of Beris, Ramin and Pasabandar was performed at 10 stations in the north of the Makoran Sea by Garb van-veen during three periods of pre-monsoon, monsoon, and post-monsoon winter with recordings of chemical physical parameters from November to March 2016. In the study identified 18 families of polychaetes communities it was found that the highest density in Monson period and in Post-Monsoon with 4364.67 ± 570 ind/m2 and the lowest density in Post-Manson period in Roman region with 225.33 ± 89 ind/m2.  In the pasaBandar area, the highest percentages belonged to the families Spionidae, Maldanidae and Cirratulidae, and to the families of Nephtydae, Phyllodocidae and Cirratulidae and to the Ramin family's Orbiniidae, Maldanidae and Cirratulidae. One-way ANOVA showed significant differences between stations and time periods (P <0.05). The highest densities of the polychaetes were estimated in terms of the period of Monsoon> Pre-Monsoon> Post-Monsoon period, respectively. Results of correlation between polychaete density and environmental factors of grain size sediment and TOM in pre-monsoon period showed a positive and significant correlation. There was no positive and significant correlation with environmental factors in monsoon period (P <0.05), but there was a significant positive correlation with grain size in post-monsoon period (p<0.05). The results showed that winter monsoon causes significant changes in the populations of the studied areas and the increase in density in monsoon can be due to the change of the currents direction and consequent increase of nutrient load in the area.

In the present study, the antioxidant properties of protein hydrolysate produced from Caspian mullet by-products at different hydrolysis times were investigated. For this purpose, 20 pieces of Mullet fish with average weight of 300±50 g were prepared, and their by-products including head, fins and viscera were used for hydrolysis by alcalase enzyme 2.4 L (concentration 1.5%, temperature 55 ° C and pH 8) at different hydrolysis times including 30, 60, 120 and 180 minutes. Results showed that protein and ash content of protein hydrolysate powder were significantly increased and fat content significantly decreased compared to the raw samples (p <0.05). The soluble protein and the degree of hydrolysis of Mullet by-products increased with increasing the hydrolysis time up to 120 min (p>0.05). Free radical scavenging (DPPH) assay showed that increased with increasing the protein concentration up to 120 min. (p<0.05). The lowest IC50 value ​​of DPPH scavenging activity was obtained at 120 and 180 min (1.04±0.06 and 1.01±0.01 mg/ml, respectively) (p<0.05). With increasing protein concentration and time of hydrolysis, the reduction ferric ion power increased significantly at all times and protein concentrations (p <0.05). Moreover, ABTS increased with increasing hydrolysis time up to 120 min (p <0.05). In general, due to the proper performance of the Mullet by-products protein hydrolysate on DPPH and ABTS free radicals scavenging and the ferric ion reduction, it can be stated that, this product can be used as an antioxidant compound.

aturity of project management has a great impact on the rate of project success. However, the existing project management maturity models when in use  both organizationally and efficiently are costly, time consuming and difficult. The purpose of this paper is to design a project management maturity assessment model for large petrochemical industry projects  to assessment project management maturity by existing  project management tools and models at every level of project  life cycle. In this project by means of multi granded theory that combination of granded theory and transcendent, Project management functional areas are identified.Due to the combination of the two methods, fitslty About 20 studies out of more than 150 related studies were used for hybridization and the corresponding codes were identified then by  using 16 structured surveys in the form of a grounded theory, functional areas were extracted, the areas are : Project Management and Leadership Areas, Project Strategy Management, Integrated Project Management, Project Area Management, Project Time Management, Project Cost Management, Project Financing Management, Project Quality Management, Project Human Resource Management, Project Communication Management, Management Project contract logistics, project claims management, project safety and health management, project environment management, inventory management and project technologies, project business management.

In this paper, the quasi-static compressive strength of two different sandwich structure designs in which cores consist of trapezoidal corrugated panels is investigated. In one design, the core consists of a cross-corrugated multilayer structure, while in the other design the core is consists of two interlocking bidirectional cross-corrugated panels. For each design, three different trapezoidal wave profiles are studied and one of them is constructed and tested. The results of specimens' crushing tests under quasi-static compressive loads are compared with the numerical modeling results. Afterward, the mechanical behavior of the other four designs is evaluated numerically. The results showed that the ultimate strength of the sandwich structures with an interlocked corrugated core is higher than the ultimate strength of the other design. It was also found that, in a given design, the ultimate strength depends on the corrugation profile geometry. These results can be used in the design of high-strength light-weight structures. Measures that can be taken to improve the ultimate strength of sandwich panels include the use of polyurethane foam, which is light in weight but has high strength, or the geometry of the structure be changed.