نشریه هیدروفیزیک
سال دوم شماره 2 (پیاپی 3، پاییز و زمستان 1395)

One of the important problems in ports is sedimentation in access channels and variations of coastline and sea bed, So that dredging for the optimal use of port has considerable price. One of the most important problems in coastal engineering is sediment transportation; because of some times the lack of residual materials show the existence of erosion in the region and in other points association of sediment indicates sedimentation. In this research at the first by comparing of Aerial imagery, coastline variations in Lengeh Port has been evaluated and then using LITPACK software related to DHI, using wave and current data and grading scales of sediments, coastline variation has been simulated and sedimentation in regional of study has been calculated. Results indicate that variation of coastline of Lengeh port in recent is very low and this condition is deposited in accordance with the sedimentary meager resources available in the region.

In areas such as the Strait of Hormuz analyzing the water flux is of great importance since in these areas subsurface currents can cause flux movement which in turn can cause lots of problems in marine transportation especially in submarine navy. In this study water current characteristic and flux parameters ( (are analyzed in the area of the Strait of Hormuz using HD module. For this purpose, current characteristic within the area was simulated using Mike21 numerical model. The results show that water flux component along the Strait of Hormuz (P component) changes within the range of -1.4 to 0.6 m^3/(s⁄m) and the water flux component along the width of the strait of Hormuz (Q component) changes within the range of -0.6 to 0.5 m^3/(s⁄m). In general, the results of this study show that since the P component is related to surface velocity, this component will decrease and the subsurface flux will increase if the surface velocity decreases. Designing such patterns (pattern of water flux) is crucial in navy, drawing naval maps, and drawing submarine subsurface maps.

The subject of this study is 3D modeling of density changes and double diffusion of salinity and temperature in a marine rectangular basin with closed boundaries and none-level bottom on longitude: 47º to 58º E and latitude: 24º to 30º N. In the area of the study every horizontal layer has regular mesh grid points. In this study the lattice that is applied is modified Arakawa C lattice and spatial grid distance in both east and north is equal to 0.5º and in vertical with respect to type of vertical coordinate, it is equal to 0.1 in sigma scale. Distance of grids is considered as long as 0.5-degree Longitude and Latitude. It is considered in 5 layers in spherical coordinate with sigma vertical component. In order to Numerical calculation of every parameter used in governing equations, equation should be discretize by special mathematical scheme, and wind blow is considered steady all over basin surface during the 4 days. Results show quality of changes in diffusion of temperature and salinity of each layer along longitude and latitude.

So far, various methods for extracting wave energy have been developed. However, most of these methods have low efficiency in shallow waters and for the small wave amplitude. The mud of the seabed is able to absorb a significant portion of wave energy in different wave lengths. In this paper inspired by this natural characteristic, the idea of a new wave energy converter with the ability to work with high efficiency in shallow water is proposed. If close to the coast, the sea floor is covered by the converter, a significant proportion of wave energy can be absorbed. The main component of this carpet of wave energy converter (CWEC) is a flexible and visco-elastic plate. In this paper, first, by using an analytical modeling, wave energy absorption capability in different sea states of Persian Gulf was considered and compared with other wave energy converters. Further investigations revealed that because of the high efficiency of this converter in shallow waters, it can be suitable for application in the Persian Gulf. Then, the new idea of using piezoelectric elements in the CWEC device was designed to increase its efficiency. The results show that the piezoelectric combined with CWEC could significantly increase the efficiency of this energy converter device.

The basic principles of calculations in the framework of density functional theory and density functional perturbation theory were used to investigate the elastic and piezoelectric properties of hypothetical SrHfO3 compound in tetragonal structure with P4mm space group. Polarization and Born effective charges tensor were calculated to investigate the nature of ferro-electricity of this system in an atomic scale. Our results show that Born effective charges of both Hf and O atoms are much larger than their anticipated nominal charges which show a strong bonding between Hf and O atoms. Formation energy calculation revealed that the compound will be stable, if it is synthesized and would not decompose to its ingredients. Non-vanishing and significant calculated piezoelectric constants imply system piezoelectricity. The effect of uniaxial stress along the c-axis on polarization, Born effective charges and piezoelectric stress and strain coefficients were also investigated. We found that the polarization increases as the uniaxial stress goes from negative to positive. These changes suggest that the uniaxial tensile stress could raise the ferro-electricity, while the uniaxial compressive stress would cancel it. We also found that the piezoelectricity of this system could be improved by applying stress. These results could be significant in the field of lead free piezoelectric materials.

The main purpose of this paper is to examine the monthly change of main constituents of tide in the northern coast of Persian Gulf and Oman Sea. So the coastal tide gauge data in the port of Bushehr, Jask and Chabahar is used. Duration of tide gauge data collection stations from the sea surface height is listed by about 24, 6 and 7 years. By analyzing the data monthly of tide, the tidal constituents of M2, S2, K1 and O1 were obtained separately for each month. Results obtained show that, the greatest tidal range is for lunar semi diurnal component (M2) about 72 cm in Jask. However, the main constituents of the monthly changes are for K1 with a range of about 30 centimeters. As well as for other constituents such as S2, O1 and M2 to the monthly change in values of 18, 11 and 9 cm are obtained.

They can be therefore the mouth of a route through the open oceans. Tiab Estuary, located 30 kms away from the Minab city, is a channel overflowed to the Persian Gulf and the Strait of Hormuz. In this field investigation 5 stations along the channel have been selected for measurements. Two cruises were carried out in the 23rd of Mehr and 28th of Aban of 1394 (October 15 to November 19, 2015). In the former cruise the measurements were carried out along the channel for a period of about 12 hours. The latter cruise however, took place at the middle of the channel during one tidal cycle. The instruments used, were a CTD, a Niskin sampler bottle, and a grub. The results derived from this investigation show that the increase in the suspended sediment concentration happen during the ebb condition, specifically at the mouth of the estuary. It was also found that the grain size distribution of the bed load is decreasing from the mouth of the channel toward the basin. At the basin the silt and clay percentage is about 40.71%, while at the mouth of the channel this amount reduces to about 3.48%.

The estimation of alongshore sediment transport rate (LSTR) is the most important factor in analyzing the amount of erosion or accretion along a coast. In the present research, an LSTR measurement was done at daily intervals using sediment traps in Noor coastal area, north of Iran, from March 21 to June 22, 2012. The existing empirical relations are linear or exponential regressions based on the observations and measurements data. Based on calculations, the yearly average of sediment transport rate is 928.73 (m3/day) for Noor coastal area. One of the most widely used methods for estimating LSTR, which has advantages compared with others, is setting up and application of an artificial neural network (ANNs) and the present study attempts to develop such a model. Different ANNs with different input configurations and transfer functions were examined. The results reveal that usage of the hyperbolic tangent is better than application of the sigmoid as the transfer functioning. Moreover, the ANN with wave breaking height (), surf zone width (W), and alongshore current velocity (V), as inputs and sediment transport rate (Q) as output configures the best model and predicts more reliably, with higher correlation coefficient, R2, of 0.96, the L.S.T.R among others. Using the ANNs model presented in this research, therefore, the sediment transport rate can be estimated with sufficient accuracy.