Reinforced concrete (RC) structures are widely used in urban buildings and infrastructures, and these are always subjected to explosions caused by intentional or unintentional accidents. Among the structural members, columns are key load carrier elements. In this paper, behavior of RC columns with circular and square sections strengthened by steel jackets is investigated and compared under blast loading. Accordingly, six circular columns and six square columns, which are equivalent in geometry and material properties, were modeled using ABAQUS software package. The effect of varying the concrete strength, longitudinal reinforcement and geometrical properties of steel jacket on FE models of the columns has been studied. In addition, a sub-program has been written to evaluate the changes in axial and lateral capacity of the column. Based on the most important results, the circular columns perform better under blast loading. Using steel jackets, in addition to increasing the explosive capacity of the column, improves the effects of other remediation strategies such as the use of high strength concrete and the higher percentage of reinforcement. This effect was observed to be higher in circular columns in compare to square columns.

Occurrence of water scouring phenomenon around hydraulic structures is one of the most essential factors that destroys and consequently losses of the financial each year. Existence of pier structure in front of the entrance of harbor, causes to generate three dimensional (3-D) flows around the piles of piers (due to entrance of wave into the harbor and the result of ships movements) and causes erosion, sedimentation of basin and localized water scouring. In numerical modelings that have been done so far, rate of water scouring is a function of flow parameters such as flow velocity, depth and geometrical parameters like diameter of the piles and granulation. In this paper, in addition to the study of previous parameters, we can estimate amount of affect of rotation in water scouring process around the piles of piers. In this article, according to the existence of 3-D flows around hydraulic structures such as downwards flows in front of piles and in order to consider the role of flows in water scouring a complete 3-D model is used for hydraulic flow simulation around the structures. To consider the actual boundaries of the piles of piers, the structural mesh and curvelinear border method (along the horizontal and vertical) is used. Due to changes in depth and sea bottom, the Sigma coordinate system is used to mesh.

Deep Drawing with rubber components is one of the conventional methods to reduce the cost of manufacturing, also this method is core cause for increase of LDR and has positive effect on improving the thinning defect. Moreover, the punch or matrix is made of rubber. Deep drawing of two-layer sheets is one of the new ways to achieve the desired properties in the produced parts in which two layer metal sheets are connected to each other by glue and are transformed together to the desired shape. Thinning control is different in the single layer when there are different materials or thicknesses. In this paper used the technique of initial gap distance between blank holder and fixed ring. In this study square sample using die along with rubber matrix by experimental and three-dimensional simulation has been formed. In this paper, using the finite element method and hyper-elastic model and the numerical model simulation for this process is three-dimensional.Then, to validate the obtained result from simulations, die with rubber components is made for square cups by considering permutation of layers for aluminum and steel and then, experimental and numerical results were compared. Finally, for evaluation effect of process parameters on thinning defect, force of punch and blank holder force used from Taguchi methodology.

1. Introduction The jacket-type platform is the most common offshore structure employed for the oil and gas production from the reservoirs below the seabed. It consists of three main parts: superstructure or topside, substructure or jacket, and the foundation or piles. Construction of floating breakwaters and wave barriers is one of the commonly used methods for the protection of harbors and coastal structures. However, their application for the protection of offshore structures has not been extensively studied. The present paper investigates the effects of a floating wave barrier installed in front of an offshore jacket structure on the wave height, waveinduced forces, and consequently jacket’, s base shear and overturning moment. Abul-Azm and Gesraha (2000) studied the hydrodynamics of floating pontoons under oblique waves. Gesraha (2006) analyzed the shaped floating breakwater in oblique waves. Rahman et al. (2006) presented a numerical modeling for the estimation of dynamic responses and mooring forces of submerged floating breakwaters. Christensen et al. (2018) conducted a set of experimental and numerical studies on floating breakwaters. Dong et al. (2008) carried out a number of experiments on the wave transmission coefficients of floating breakwaters. In the present research, a jacket model with the height of 4. 55m was fabricated and tested in wave flume of NIMALA marine laboratory. The wave flume was 402m long. The jacket was tested at the water depth of 4m subjected to JONSWAP waves with the height of 20cm, 23cm, and 28cm. The mechanism of wave energy dissipation due to hitting a wave barrier is mainly a combination of the wave diffraction and the wave reflection. A square cross section was selected for the wave barrier. Results showed that a floating wave barrier can effectively reduce the base shear and overturning moment in an offshore jacket structure...

In tube drawing process, there is a bunch of parameters playing key roles in the process performance. Thus finding the optimized parameters is a controversial issue. The current study aimed to produce a squared section of round tube by tube sinking process. Finite element method (FEM) was used to simulate the process. Then, to find a meaningful kinship between process input and output parameters the developed FE model was associated with the design of an experiment based on response surface methodology (RSM). The sufficiency of each model was checked by analyzing the variances. Further, the SA (simulated annealing) was associated with RSM models to find the optimal solution regarding maximum thickness distributions and minimum force and dimensional error. Hereafter, for performing accurate optimization, principal component analysis was used to find the appropriate weight factor of each response. The obtained results were in right congruence with those derived from the simulation and confirmatory experiment.

Impact is one of the most important subjects which always have been considered in mechanical science. Nature of impact is such that which makes its control a hard task. Therefore it is required to adopt a safe and secure mechanism for transferring the impact to other vulnerable parts of a structure, when it is necessary. One of the best methods of absorbing impact energy is using Thin-walled tubes, where the tubes collapse under impact by absorbing energy, while this prevents the damage to other parts. Purpose of the present study is to survey the deformation and energy absorption of tubes with different type of cross section (rectangular or square) and with similar volumes, height, mean cross section, and material under different speed loading. Lateral loading of tubes are quasi-static type and in addition to the numerical analysis, also experimental experiment has been performed to evaluate the accuracy of the results. Results from the survey indicates that at the same conditions which mentioned above, samples with square cross sections, absorb more energy compared to rectangular cross sections; also by increasing the loading speed and thickness, the energy absorption would be more.

The deep drawing process is one of the most widely used metal forming methods, which is widely used in the mass production of parts. The phenomenon of earring has always been one of the defects in deep drawing processes, which causes an increase in material waste and a decrease in the production speed of parts. This phenomenon is caused by plane anisotropy resulting from the cold rolling operation. One of the methods to reduce the earring defect is to optimize the initial blank. In this article, a method to optimize the initial blank and to reduce the earring defect in the process of deep drawing of square sections is presented. For this purpose, the initial blank made of SAE 1015 steel was simulated in Abaqus software. In the following, by using the particular objective function, the initial blank was radially optimized in specific paths. By re-simulating the optimal blank and checking parameters such as; Thickness changes, stress distribution, and strain changes, it was found that if the optimal blank is used, the earring defect is significantly reduced

Piles with a gradually decreasing cross-section area from pile top to the tip is called tapered piles. Making this change in pile geometry could improve pile behavior in terms of axial compression load bearing, compared to conventional uniform cross-section piles. The beneficial effect of shaft taper pile on the capacity and performance of axially loaded single piles is well documented in the literature. However, the behavior of tapered pile groups has been rarely investigated experimentally and numerically. In this study, a numerical investigation of single tapered pile and pile group behavior based on an experimental investigation in geotechnical centrifuge is conducted. This investigation included both circular and square cross-sections for tapered pile and 2x2 pile group. The results of experimental and numerical modeling highlight the considerable advantage of circular and square tapered piles over the uniform cross-section ones in terms of axial compressive load-bearing capacity. Although the surface area of the circular tapered piles is smaller than square ones, the results surprisingly imply upon an increase in the axial bearing capacity. In numerical simulation, pile group efficiency of tapered pile and shear stress distribution in the soil medium around the pile are investigated. Moreover, the effect of shaft surface geometry of tapered pile with circular and square cross-sections on axial compression load-bearing capacity is also investigated. The findings of numerical simulations indicate that the concave corners of the pile cross-section impose negative effect on shear stress mobilized on the pile surface. In addition, the pile group efficiency of tapered piles is generally lower than corresponding values for uniform cross-section piles. Also, the group efficiency of all tapered pile groups was almost equal to unity, meaning that the load carried by the group is equal to the sum of the load carried by individual similar piles.

Background and Objective: Intraoperative consultation by frozen section is a high – risk procedure with important consequences. Therefore, it is critical to determine efficiency of frozen section performance periodically. This study was performed to determine the accuracy of frozen section in Urmia University of Medical Sciences.Materials & Methods: In this cross sectional study, we compared the results of 200 consecutive cases of frozen sections with theirfinal permanent section diagnoses in teaching hospitals of Urmia University of Medical Sciences during March 2001 to March 2008.Results: A total of 155 neoplastic and 45 nonneoplastic specimens were studied. The overall accuracy of frozen sections was 96.5%. In diagnosis of neoplastic lesions, sensitivity, specificity, positive and negative predictive values and accuracy were 93.1%, 97.7%, 96%, 95% and 95.9%, respectively.Conclusion: In this university interpretation of frozen sections is done with high accuracy and is valuable to help surgeons to plan the best management of the operation.

In order to predict the behavior of soil-related phenomena, it is necessary to have knowledge about unsaturated flow and using models that provide optimal estimates of the retention curve and hydraulic conductivity of soils. Despite the widespread use of the classic van Genuchten-Mualem model (VGM), this model usually performs poorly in predicting hydraulic conductivity and modification of some of its parameters seems necessary. In this research, 283 soils from different textures of the UNSODA bank were selected and divided into two sections of calibration and validation and their soil parameters were exported and categorized. Then, by defining the modified unsaturated hydraulic conductivity (Ksc) instead of the saturated hydraulic conductivity (Ks) and determining the limits for l and n parameters, the hydraulic conductivity-moisture function of VGM were solved using 24600 pairs of points li and nj for each soil of the three main soil texture classes. In the following, the optimal l value (l̂) of each texture class was selected based on the minimum value of the hydraulic conductivity estimation error using the root mean square error (RMSE) index and the n values that had created the minimum errors, were selected as the optimal pore size distribution coefficients of the hydraulic conductivity-moisture function (n̂opt). In order to create pedotransfer functions for estimating n̂opt, we ran stepwise regression in MATLAB software considering the condition of statistical significance (P-value=0.05) for independent variables and functions for each soil texture class. After creating pedotransfer functions, the results of the proposed method of this research (MVGM) were compared with the VGM results using RMSE and Nash-Sutcliffe (NSE) indices. The results showed that in both sections of creation and validation functions, the MVGM performed better in estimating hydraulic conductivity and had a higher efficiency index in all textural classes of soil.