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۱INVESTIGATION OF DURABILITY OF REINFORCEMENT CONCRETE IN SEVERE CORROSIVE MARINE ENVIRONMENT
نویسنده(ها): ، ، ،
اطلاعات انتشار: سومین کنفرانس بین المللی بتن و توسعه، سال
تعداد صفحات: ۸
The intensity of damage in concrete structures has a vital relationship to the position of concrete versus the sea water level. With regard to this concept, the environment of located structures near the coast (i.e. coastal structures) can be divided into four zones: marine atmospheric, splashing, tidal and submerged [1, 2]. A hydraulic model consists of a channel with 10 meters in length, 0.7 meters width,
1 meter depth and a wave maker machine capable of making regular waves with various heights and periods, has been designed and constructed in hydraulic laboratory of Sahand University of Technology to simulate the marine environment and conditions in this research study. The Oroomiyeh lake water was used to reproduce severe corrosive marine environment. Two water\ cement ratios (0.45
and 0.55) and two cement contents (350 and 400 kg\m3) were selected for reinforcement and plain concrete specimens. Furthermore, silica fume was used as supplementary cementing material. After standard curing, these specimens were kept in different conditions:
submerged, tidal, splash, atmospheric and outdoors. A series of tests such as corrosion potential measurement, electrical resistivity and
reinforcement corrosion intensity, chloride ion concentration and compressive strength were carried out at different ages of concrete. In this paper, the function of specimens, durability in different zones have been investigated and compared with one to the others.<\div>

۲Comparison of Multimode Interference Couplers: Gaussian–mode and Sinusoidal–mode Cases
نویسنده(ها): ،
اطلاعات انتشار: پنجمین کنفرانس بین المللی پیشرفتهای علوم و تکنولوژی، سال
تعداد صفحات: ۹
Analysis of the multimode–interference couplers can be done by using the sinusoidal eigen–modes and also the Gaussian eigen–modes for the multimode region. Study of the multimode interference couplers using the sinusoidal eigen–modes is based on the self–imaging concept of the multimode waveguides. These modes can be determined by using the planar waveguide theory. In Gaussian model, eigen–modes of the multimode region are obtained by using the Gaussian mode theory. In this paper, direct comparison of the multimode interference couplers with Gaussian eigen–modes and couplers with sinusoidal eigen–modes is done. The coupling coefficients of the field for these models are compared. In addition, a comparison is made between wave propagation analysis of Gaussian model and wave propagation simulation by FEMLAB software and FDTD method for MMI couplers with ultrashort lengths. It is shown that the Gaussian model results, unlike the sinusoidal model, are in good agreement with the simulation results. In other words, the Gaussian model is necessary for analysis of the ultrashort MMI couplers and also the sinusoidal model is not suitable for small lengths. In fact, building–up of the sinusoidal modes is the result of multiple interference of the reflected waves that appears in larger lengths. In addition, for long MMI couplers, the Gaussian modes are gradually transformed into the sinusoidal modes and the results of the sinusoidal model with self–imaging principle is true to handle these types of devices<\div>

۳Comparison of Linear and Nonlinear Regimes in MMI couplers
نویسنده(ها): ،
اطلاعات انتشار: پنجمین کنفرانس بین المللی پیشرفتهای علوم و تکنولوژی، سال
تعداد صفحات: ۷
In this paper, linear and nonlinear characteristics of the multimode interference couplers are investigated. When the intense input field is launched from the access waveguide, the linear modes of multimode waveguide, which are determined by using the planar waveguide theory, can be influenced and therefore Kerr nonlinear effect will be appeared. In fact, by varying the intensity of the input field, the refractive index of the region and therefore the intensity distribution of the light in MMI region will be changed. To determine the guided modes in nonlinear medium, the set of coupled wave equations in this region is analyzed and then is solved by numerical method. In addition, the guided modes in linear model are obtained by EIM method. Coupling and transmission coefficients of MMI coupler for these regimes are obtained and their results are compared. In addition, comparison of wave propagation along the waveguide for these regimes is done and it is shown that there are some differences in their intensity distribution of the field.<\div>

۴numerical modeling wave transmission over trapezoid submerged breakwaters with SPH method
نویسنده(ها): ، ،
اطلاعات انتشار: نهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۸
the paper employs a reynolds averaged nanier stokes RANS approach to investigate the wave transmission over trapezoid submerged breakwaters the numerical model is based on smoothed particle hydrodynamic SPH method it is a mesh free particle approach which is capable of tracking the free surfaces of large deformation in an easy and accurate way study aimed to determine the effect of depth of submergence crest width and initial wave conditions on the transmission characteristics of the submerged breakwater.<\div>
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