فصلنامه علوم و فناوری دریا
سال بیست و هشتم شماره 110 (تابستان 1403)

The three-dimensional reconstruction of the underwater environment for the exploration and exploitation of the oceans and seas in terms of transportation, trade, food and medicine resources, mineral resources and the security of coastal countries is very important in today's world. For this reason, various researches have been carried out in this area and it is still one of the important research areas for research groups in research centers and universities. Obviously, to conduct new research in this field, it is necessary to be familiar with the methods that have been presented up to now. Therefore, in this research, the various methods that researchers have presented for the reconstruction of the three-dimensional surface of seas and oceans and underwater objects have been reviewed. For this purpose, the content is presented in three categories. In the first category, the optical methods, the second category, the reconstruction of the underwater 3D surface using acoustic methods, and the third category, the 3D underwater reconstruction based on the combination of optical-acoustic images have been investigated and evaluated. Finally, potential future developments in this field are considered.

A kind of large scale breakwater is constructed for the first time in Iran in Tombak port. Some important points of launch and installation of these caissons are including: planning and using necessary equipment for locating this structure in breakwater accurate place. In launching time when water is filling for merging, caissons stabilization and fixation in the correct place are important, therefore using some moorings is necessary. In this research we use ANSYS AQWA software for investigation of mooring forces in caissons installing time. This analysis done in four conditions including: caisson without mooring, with one, two and four cable moorings. Then, wind and wave forces in installing time and force analysis of moorings are obtained using numerical modelling. In optimum condition (caisson with four cable mooring) the maximum force on caissons is 190 tons.

Reducing the resistance force in order to access more power, higher speed, and less fuel consumption is one of the various goals in scientific research. Considering that the main important problem for a vessel moving in a fluid is the drag force, the tools for reducing drag has attracted the researchers.In this study, the researchers sought to find the mathematical relationship for predict sawtoothed riblets percentage of drag reduction. For this purpose, first, by investigating the result of scientific researches, they are determined the effective variables on drag reduction. Then, by anlyzing the relationship between drag reduction and these variable, fit the curve of the three-dimensional shape of the obtained function, and matching the spatial shape of the relationship with the equations of quadratic procedures, the closest shape that has the ability to match the relationship according to the limits was calculated. it determined elliptic paraboloid relationship. which had a good agreement with the experimental results.

One of the important factors in these damages is the incorrect prediction of liquid fluctua-tions in tanks. In this research, the dynamic analysis of concrete water storage tanks under near-field earthquakes has been done. The finite Element model of the studied tank is de-veloped in ABAQUS software considering the interaction of structure and fluid. Concrete tanks with cylindrical, square, and rectangular sections with the same storage volume are considered. These models are considered with two filling levels of 40 and 90%. To investi-gate the performance of the considered concrete tanks under near-field earthquakes with different characteristics, two groups of near-field earthquakes are selected for time history analysis. In the first group, 3 records of no-pulse near-field earthquakes and in the second group, 3 records of near-field earthquakes with forward-directivity effects were selected. The results of the time history analysis show that cylindrical tanks have performed better than square and rectangular tanks from the point of view of vertical and horizontal vibra-tion of the liquid surface inside the tank. Also, the results indicate that near-field earthquakes with the characteristic of forward-directivity compared to the no-pulse near-field earthquakes, lead to more horizontal and vertical vibration of the liquid surface inside the tank and also bring more acceleration to the walls of the tanks. In the same storage volume and in all forms of tanks, the amount of vibration of the liquid inside the tank is higher at lower filling levels. By reducing the aspect ratio, the response of both types of cylindrical and square tanks has shown a decrease. For square tanks with 40% filling, by reducing the aspect ratio from 0.583 to 0.357, the amount of vertical displacement of the liquid surface has decreased by about 20%. Also, for cylindrical tanks with a filling level of 40%, the amount of vertical displacement of the liquid surface has decreased by 29% corresponding to aspect ratio reduction from 0.517 to 0.3125.

With the advancement of technology in the field of manufacturing power electronic equipment, following the presentation and introduction of FACTS equipment in the transmission system, equipment called Custom Power equipment was introduced in distribution networks. These tools include; DSTATCOM, DVR and UPQC are the most significant compensators of power quality problems in the distribution network. Among these equipments, DVR dynamic voltage recovery is known as the most effective equipment (in terms of performance and economic considerations) to compensate for the lack of voltage. In this way, the main axis of this article is devoted to compensating the lack of voltage by this equipment. Compensating the lack of voltage by DVR will require the use of a tracking pattern or voltage estimation. The selection of the voltage estimation model in the design of the DVR control system determines the speed of response, the mode of operation and the type of voltage deficiency compensation.

n this research, in order to evaluate the ecological assessment of Safarod River sediments and environmental effects, 8 sediment samples were collected from river bed and the concentration of heavy metals (iron, arsenic, cobalt, chromium, nickel, lead, copper and zinc) was determined by ICP-OES method. Based on the degree of contamination (Cd), sediments of the Safarod River are classified in the range of moderate pollution. Also, based on the modified pollution degree index (mCd), it was determined that all the samples except for 3 stations are polluted and they are in the range of low to medium pollution degree. The pollution load coefficient (PLI) was obtained in most stations, especially in the end sections, in the range of more than 1 (slightly polluted to polluted), but in terms of the ecological risk (RI) of the river, it is in the low risk range. Based on these results, the key solutions to prevent further pollution of this river are continuous management, control of erosion of upstream sediments, reduction and treatment of industrial and domestic effluents and preventing them from entering the river.

A hotel barge is a barge that has been converted into a hotel or other types of accommodation to provide services. In Europe, hotel barges are commonly found on rivers and canals and may be used for domestic travel or permanently docked in an area. There are not many resources available regarding the interior architecture of the Hotel barge, and this article intends to cover a part of it in this field. The hotel barge has many advantages, such as the northern and southern cities in Iran, due to the location of the land, they are very affordable. They don't stay in one place forever and they can be moved by tug boat, they are environmentally friendly and they are quick and easy to build. In this article, first, some rules of the rules of the international convention on the safety of life at sea, and then the cross-sections of three famous floating hotels in the world have been examined, and some points related to the stability of the hotel have been presented. In the second step, the internal architecture of these hotels were examined and finally it was concluded that attention to the floating center of gravity is very important in the placement of different parts of a floating hotel. In the investigated floating hotels, the area of the rooms starts from 14 square meters and reaches 65 square meters. The minimum service area is 3 square meters and the maximum area is 8.8 square meters. The ratio of room area to room area with service is 0.73-0.91 and the ratio of room area to service area is from 2.64-9.7. The space allocated to each person in a room is also 5.5-28.25 square meters.

In today's knowledge-based economy, knowledge and virtual assets of the company, which are considered as intangible financial assets, are considered as the main factor of wealth production in comparison with other tangible assets of the company. In today's competitive markets, where the goal of companies, whether knowledge-based companies or other companies that have significant virtual assets, is to gain more market share by creating competitive advantages, the success of companies depends on the organization's virtual asset management because it is parallel to the growth of technology. Gradually, companies' assets are moving towards virtual assets. Today, with the advancement of technology, virtual assets have found a special place in various forms in the process of economic, managerial, technological and social development. Therefore, it is important in applied research to value the virtual assets of knowledge-based companies using information technologies, and the results are available to the stakeholders and managers of knowledge-based companies. For this reason, in this research, 92 knowledge-based companies cooperate with defense organizations. was evaluated by using structural equations and mediating role of information technology to examine the level of access, confidentiality and integrity of virtual assets of knowledge-based companies, and the results revealed that availability is 0.193, confidentiality is 0.363, and integrity is 0.061 variables of information technology. As a mediating variable, it influences and also the information technology variable predicts the intention by 0.717 of virtual assets.

In the current situation, the UN regulations regarding the law of the seas are related to the protection of the environment. Considering the undeniable value of marine and oceanic resources in world trade, the dependence of food security on the status of fishery and the subsequent destructive effects on marine ecosystems, the United Nations follows a special system for the protection of the marine environment and has raised a common responsibility according to common principles and values for the continuation of human life. The principles of international environmental law are directly employed to support sustainable development and the protection of the global environment. These principles include the precautionary principle, the duty to cooperate, the ecosystem approach, and the principle of common but differentiated responsibilities. So, Current paper studies how general principles of international environmental law and the United Nations Convention on the Law of the Sea (UNCLOS) and its related agreements, have interacted with each other over time. In following, it study the importance of protecting the marine environment, the interaction of the general principles of international environmental law and the law of the sea, and the impact of the adoption of new instruments as well as interpretation by international courts on the development and evolution of the 12th part of the United Nations Convention on the Law of the Sea in the field of sea law to meet the contemporary environmental challenges.