INTERNATIONAL JOURNAL OF MARINE SCIENCE AND ENGINEERING
Year:2013 | Volume:3 | Issue:3|Papers Count:8

Analyzing the vortex-induced vibration of a slender marine structure with length to diameter ratio up to 200 is the objective of this study. This slender is free to move in both in-line and cross flow directions and immersed completely in water. Three different types of shear currents pass on it and cause to vibrate slender in different forms. Nowadays, these vibrations are very important for designers. In this study, 3D Finite difference method has been used to solve cable governing equations in a long slender with two hanged ends. The hydrodynamic forces, in the direction of in-line and cross-flow created by vortex shedding are simultaneously considered based on Morison equation. In a specified range of Reynolds number, the flow is in-line direction, but the results show riser oscillation in both in-line and cross flow directions. The results showed a good agreement with other researches in VIV with constant flow on it. Then non-uniform flows with profiles in real ocean currents were selected as inputs of this study. The results showed that small variations in velocity profiles and quantities can create significant differences in riser behavior.

Seasonal variations of the seawater properties (e.g. temperature, salinity, density and chlorophyll-a) in western part of the southern coastal waters of the Caspian Sea near the Iranian coast were studied. A portable CTD probe was applied for profiling from sea surface to bottom at 23 stations. Maximum depth of the profiling stations was more than 470 m in the study area. Vertical structure of temperature in the southern Caspian Sea waters is characterized by a significant seasonal thermocline between 20-50 m depths in summer with a vertical gradient of 16 oC. Seasonal average of the salinity was in a range of 12.27-12.37 PSU in period of measurements. The data showed that the most chlorophyll-a was found below the sea surface. In general, variations of the chlorophyll-a concentration in the study area can be attributed to the effect of changes of seawater characteristics in various seasons, stratification and heating the sea surface layer in the warm seasons and discharge of lagoon and rivers in the study area. The range of the concentrations at the sea surface in August and November were higher than the measured values in April in the study area. Concentrations of chlorophyll-a were recorded in midsummer in a range of 0.2-3.4 mg m-3.

Ports are the most important economic, political and military bottlenecks. This puts shoreline structures (port) in the class of important structures and they have a crucial role in the countries’ life. Pile and deck wharf and their access bridges and offshore deck (jetties), are one of the parts which are supplier of coupling between the land and the waterfront. Correct and exact estimation of loads acting on individual structures leads to more accurate and more economical design. To design waterfront deck, it is necessary to estimate the amount of reaction generated in the deck by live loads due to the crossing of the machines over it. To more accurate assessment the effect of moving vehicle passing on the deck, the dynamic analysis is used to calculate the response generated in the deck. The modeling of the vehicle moving on an access bridge of pier piles and deck with the beam element-capturing method, and the D'Alembert and balance principle are used to write the governing differential equation. The deck is also modeled in the form of Euler-Bernoulli beam, with a uniform cross-section. Dynamic load modeling for dynamic analysis of the deck is done by MATLAB program. The main output of this research is to answer the question, that the moving vehicle passing with heavy cargo, with unconventional weight can cause what reactions in the deck? Depending on the type of deck structures and military vehicles, unique results can be obtained including a new deck design, deck strengthen for existing services and changes in specific cargo trailers for safe passing on the deck.

In the present study, a total of 595 specimens collected monthly in the northern part of Persian Gulf between November 2006 and October 2007 were examined by routine macroscopic and histological techniques. Monthly changes in the gonadosomatic index showed the spawning season extended within 2 peaks, from April- May and September. The maturity stages are morphologically separated according to the changes in size, color and shape of the ovaries. Histologically, the oocytes development described the following stages; immature period (oogonia, early perinucleolus stage and late perinucleolus stage) maturation period (vacuolization stage, yolk granule stage, vitellogenic stage, germinal vesicle migration stage and mature yolk stage). The simultaneous presence of oocytes within ovaries indicated that this species is a batch spawner.

In this study marine sponges of inter tidal zone from Hengam Island Persian Gulf were collected by wading at low tides in Eskeleh station at  locations 55o 53' 40" E & 26o 40' 53" N. For identifying identification of sponge samples, acid digestion method as a method of early detection and microtome section to identify the skeletal structure were used. All the identified sponges were from class Demospongia, two orders (Hadromerida, Haplosclerida) and four families (Clionidae, Callyspongidae, Chalinidae, Niphatidae) and seven species Amphimedon viridis, Haliclona rosea, Haliclona cinerea, Siphonochalina sp., Callyspongia fallax, Callyspongia sp.2, Cliona dioryssa. This Research is the exact study to the identification sponges in basis of microtome sectioning to observe skeletal structures in Iranian Island.

The effects of five different foods including: blood worm, artemia cyst, Artemia mass powder, gammarus mass powder and ordinary commercial food were studied on Siamese fighting fish (Betta splendens) propagation efficiency during thirty days in a Randomize Totally Design with 4 repeats. Experimental plots had been consisted of twenty 30*30*40 (cm) aquarium which a pair of male and female brood stocks was introduced to each one. Male and female were separated in each plot by a glass plate for 15 days in order to prepare for spawning. The results of the experiment showed no significant differences on spawned ova, ova diameter, and hatched ova among various ration treatments (p>0.05), but the averages comparison of referring factors showed that spawned ova, hatched ova, and ova diameter, were better in those brood stocks that had been fed by blood worm food treatment. However, ordinary commercial food treatment resulted weakest averages through all ration treatments.

The purpose of this project is the investigation of LHRHa2 integrated effect with carp pituitary extract (CPE) in three stages injection on sexual indexes (fecundity, fertilization, hatch and larval survival) in artificial propagation of Barbus xanthopterus. 20 fish were divided in to 4 treatment and injected interpritoneal as follows 4mgkg-1 b.w.of CPE as positive control, 4 mg/kg+4 mgkg-1 b.w. of LHRH-A2+CPE, 7 mg/kg-1 b.w.+4mgkg-1 b.w. of LHRH-A2+CPE, 10 mg/kg-1 b.w.+4mg kg-1 b.w. of LHRH-A2+CPE. Results showed that the broodstocks of control treatment were answered no positive to injecting 4 mg/lit pituitary extract and second treatment (7 mg LHRHa2+4 mg CPE) showed highest weight of extracted egg, spawning success, fertilization success, hatching rate and larvae survival, in comparison with other groups. None of fish were ovulated in the group of positive control. Therefore, this dose and injection method can be introduced as the most successful and practical method for artificial propagation of Barbus xanthopterus.

In this paper effect of pile-soil consideration in obtaining seismic response offshore structure is assessed due to earthquake loading. InducedSeismic force is one of the most important excitations for the dynamic response of an offshore structure. According to API, Seismic forces should be accounted in platform design for seismically active regions in order to determine the allowable seismic risk for the type of operation intended. Two model were developed, in the first one, pile-soil interaction was neglected whereas in the second one, pile-soil interaction was considered by using un-grouted pile stubs. The models that were used in this research were consist of two dimensional finite element models with linear behavior. After obtaining dynamic specification of structural system, a linear time history analysis was performed on both models and eventually the response of structure in the form of overall drift and maximum top displacement was compered. Finally it was shown that neglecting consideration of pile soil interaction will not always result in ensuring structural responses.