مجله علوم و فنون دریایی
سال بیستم شماره 2 (تابستان 1400)

This study was conducted to identify and study the communities structure of adhesive organisms or the fouling of 13 years old artificial reefs on the coast of Bahrakan along the west of the Persian Gulf. fouling sample was collected seasonally from spring 2016 to winter 2016 from 4 sampling sites using quadrates 25 × 25 cm by diving operation. Based on the biomass (wet weight), Anthozoa corals with 88% of the total biomass, contain the most adhesive mass, followed by sponges (10%) and hydrozoa corals and Arthropod with 1% of the total biomass. The spring season showed the highest average rate, which was due to the biomass of the Antozoa group with 89% in this season. Based on the cluster test, the two winter and autumn seasons have a similar percentage of 80% and the summer and spring seasons show a similar percentage of 50%. Also, based on cluster analysis of two structures A, D, the similarity level of 45% and B, C indicate the similarity level of 80%

Over the past few decades, the structure and cover pattern of land in the Khuzestan coastal zone has also not been immune to such changes. Therefore, monitoring the spatial combination and arrangement of Land cover/Land use and its changes in order to identify the current threats and opportunities is considered essential. The aim of this research is to monitor or the trend of changes in landscape mosaic in the coastal regions of Khuzestan Plain in response to the growth and development of human activities. In this research, Landsat images were used across two time 2000 (Landsat 7 ETM+) and 2015 (Landsat OLI) for extracting Land cover/Land use map. In order to monitor the trend of changes, four metrics of land appearance MNND, MPS, PLAND, and NP have been used. The obtained results indicated that the spatial combination and arrangement of the landscape in the studied region have found greater heterogeneity and complexity with fragmentation, attrition, and patches. Further, with the addition of two types of use including sugar cane cultivation and industry as well as fish farming basins along with the development of industrial construction units have caused dramatic transformations in the land structure in terms of combination, continuity, and extension of valuable ecological patterns. Riparian forests with increase in the number of patches and 50% reduction in the PLAND metrics and wetlands with increase of 58% of NP metrics and 71% in MMND metrics in these regions with the maximum level of fragmentation are the most vulnerable environmental patterns.

In this research, the effect of weights that lose their lashing systems and can move freely in line with vessel breadths is investigated on ship roll motions. Therefore, the effect of friction and possible barriers that impeded on free movement of weights are neglected.To study the effects; weights with different masses are hung on pendulum which is installed on an ocean going trawler model and vessel roll motions is being experimentally tested.The results show that whoever hanging weights can increase the center of gravity of vessel and decrease the vessel stability; but caused increase the period of roll motions. The findings of research also can be used in design of damping systems of roll motions.In addition, the experimental results are compared with numerical results based on the Strip Theory. The results show that the damping coefficient has important role in the accuracy of numerical results.

We have developed a basic three-dimensional finite difference hydrodynamic oceanic model using baroclinic primitive equations based on the earth's spherical coordinate modified by vertical sigma coordinate with eleven levels equivalent to five layers to study the thermodynamics of wind-driven currents. In this basic model, we consider an enclosed rectangle area, with constant depth of 120 m. We have simulated the horizontal velocity fields, salinity and temperature distributions by forcing the model with the steady bellowing wind over the area for four days with the speed of 10 m/s and direction . According to the Rossby number of the order of one tenth thousands, the large scale processes are dominated in the middle of such basins.The salinity and temperature of the layers are changed due to the diffusion and convection terms in the salinity and temperature equations, respectively.

In the coastal areas and especially in the harbors, due to the presence of loose sandy sediments and structures under high lateral and vertical loads, the use of pile raft is a suitable choice for the foundation of these infrastructures. In this system, raft and piles are separated and a cushion is used in the distance between the raft and the piles. The existence of reinforcement layers in the cushion such as the geogrid changes the behavior of the pile raft system. In this paper, the behavior of reinforced nonconnected pile raft with geogrid under vertical loading in sandy soils has been investigated by a laboratory studies. An automatic hydraulic jack were used in the load application and LVDT is used to measuring the settlement. The strain gages are installed at the tip of the piles to calculate the force applied to the piles. Tests were carried out under reinforced and non-reinforced condition. In non-reinforced case, the optimum thickness and pile spacing of the cushion and in the reinforced case, the optimal location of the first and second layer of the geogrid and the effect of the geogrid layers length on the load-settlement behavior and the share of the piles from the total load were evaluated. The results shows that the thickness of the cushion and the pile spacing have a significant effect on the behavior of the pile raft. The presence of geogrid layers in the cushion increases the bearing pressure and the share of piles from loads.

Crab and shrimp wastes could be used as the cheapest raw materials for carotenoid pigments and also as an alternative to synthetic colors. The recovery of these valuable components from the aquatic waste could improve the aquatic processing industryand minimize the pollution potential of these wastes. In this research, Astaxanthin was used as thetarget extractionby using highperformance liquid chromatography to analyze the extended pigments under different ultrasound assisted extraction and microwave-assisted extractionconditions; namely, number of extraction times, theextraction duration, ultrasoundand microwave power andsolvent to waste ratio, inorderto understand the best condition of extraction. Theoptimal conditions forextracting crab wastes by UAE were at3times extraction with the solventtowaste ratio of15:1ml/g, and a power of 90W lasting for30second.Finally the astaxanthinyieldwas1407.12±0.58µg/gand for shrimp wastes were at 1 times extraction with thesolvent to waste ratio of 10:1 ml/g, and a power of150W lasting for150second that ultimately the astaxanthin yield was1257.43±0.02 µg/g. The optimal conditions for extracting crab wastes by MAE were at3times extraction withthe solvent towaste ratio of15:1ml/g, and a power of400W lasting for6second. Finally the astaxanthin yield was1082.07±0.25µg/g and for shrimp wastes were at 3 times extraction with the solvent to waste ratio of 15:1 ml/g, and a power of 600 W lasting for6second that ultimately the astaxanthin yield was1470.25±0.47µg/g. In comparison to the traditional method (soaking), the minimum amounts of carotenoid extraction from craband shrimp wastes were respectively95and11times, respectively.Therefore, the method of responsesurface methodology in optimizing the process condition is one ofthe effectivemethods for carotenoid extraction from crab and shrimp wastes.

Since innovation is one of the most important ways to improve organizational performance, knowledge management enables the innovation to grow dramatically, by providing a platform for knowledge development (KM) in the organization. Therefore, the purpose of this study is to investigate the impact of KM on operational performance directly and through innovation. In this study, for measurement of KM dimensions (transfer, storage, application, and creation) and innovation dimensions (marketing, process, organization and production) and, finally, the dimensions of operational performance (speed, cost, quality and flexibility) are considered. The population of this applied research consists of 420 employees of the Khorramshahr Port Authority and Maritime Administration. 291 people were selected using the Cochran formula for limited communities and a questionnaire was provided to them. The data gathering tool was questionnaire. The validity of the questionnaire’s content was confirmed by the experts and academic professors, and its structure was assessed through analysis. Confirmatory factor was reviewed. Data analysis and hypothesis testing were performed using SPSS 22 software and structural equation modeling (PLS). The results showed that KM improves innovation and operational performance. Also, KM indirectly through innovation improves operational performance. On the other hand, innovation increases operational performance