Post-fire behavior of CFRP retrofitted thin-walled steel tanks

Thin-walled shell structures are characterized by a lightweight structural form with high strength. This structure has many applications in various engineering fields and is considered to be a basic tool in the modern industry. This study investigates the effect of CFRP on tanks after post-fire in order to examine the buckling and post-buckling of the cylindrical tanks. Herein, post-fire was introduced at different temperatures (150°C-600°C). Ten laboratory specimens in two groups with verified temperatures, under external pressure, are examined. The models were designed to demonstrate how repairing steel tanks, which are damaged by fire, by using carbon-fiber-reinforced polymer can recover lost capacity. The results of testing under different theories and codes were compared. This study shows that the initial buckling load of the temperature group increased by 30.82% to 57.09% compared to the temperature without-CFRP group. The overall buckling load of the temperature group increased by 37.01% to 67.74% compared to the temperature without-CFRP group. The collapse load of the temperature group increased by 27.04% to 52.64% compared to the temperature without-CFRP group. And using carbon-fiber-reinforced polymer on models, which are damaged by fire, can be an improvement behavior for the buckling and post-buckling specimen tests.     

An integration of enhanced social force and crowd control models for high-density crowd simulation

Neural Computing and Applications - Social force model is one of the well-known approaches that can successfully simulate pedestrians’ movements realistically. However, it is not suitable to...     

A Novel Approach for Bolted T-Stub Connections

This paper reports an investigation into new connection types and their behaviors determined using full-scale experiments. T-shaped connections were created using the IPE standard profile. The aim of this study was to analyze the influence of T connections based on the IPE standard profile, height of beam to height of T-stub joint (H) of T-stub joints, and lengths (X) of T-stub joints on the behavior of steel connections, in order to provide the necessary data for improving Eurocode 3 and enable efficient use of residue IPE standard profiles and back to the consumption cycle. While the moment resistance values increased with an increase in H from H_min to H_max in model groups with X of 126 mm, and the energy dissipation increased with an increase in H from H_min to H_max and also with an increase in the lengths (X) of T-stub joints from 54 to 126 mm.     

Direct Measurement of Transformation Zone Strains in Toughened Zirconia

Residual strains responsible for crack tip shielding have been measured within transformation zones surrounding cracks in Mg-PSZ. Two techniques were used for strain measurement: moiré interferometry and high-resolution image matching. Both methods provide maps of differential in-plane displacements within the specimen surface intersected by the crack, the latter method with the higher resolution. The results are compared with finite-element analysis to assess surface relaxation effects, and the measured strains are used to evaluate the crack tip shielding stress intensity factor. Calculations based on the assumption that the unconstrained transformation strain is hydrostatic dilatation yielded results that were significantly smaller than the measured toughness increases.     

Covering photo-realistic properties of outdoor components with the effects of sky color in mixed reality

Outdoor rendering is an attractive topic in computer graphics. In this paper our main concern is to reveal the interaction between sky color and virtual objects in Mixed Reality environments. Although registration and tracking are two of the main issues in building effective Augmented Reality (AR) systems the creation of more realistic virtual objects indistinguishable from their real-world counterparts is our target which is currently the ultimate goal in AR. Two classes of sky color generation are employed to reveal the outdoor-element interaction. Virtual Sky Modelling (VSM) based on the Perez Model is capable of generating the sky color in a specific location, date and time. The second technique is to generate a virtual model based on the real image of the sky which is called in this paper Real Sky Modelling (RSM). Subsequently, preprocessing of the sky color bleeding is based on the radiosity technique to give the sky color effect to the virtual objects as well as the real ones. Through designing a test AR set-up and applying software and hardware the goal of a robust generation of realistic virtual objects with effect of sky color is achieved.     

A quadratic spline approximation using detail multi-layer for soft shadow generation in augmented reality

Implementation of shadows is crucial to enhancement of images in AR environments. Without shadows, virtual objects would look floating over the scene resulting in unrealistic rendering of AR environments. Casting hard shadows would provide only spatial information while soft shadows help improve realism of AR environments. Several algorithms have been proposed to render realistic shadows which often incurred high computational costs. Little attention has been directed towards the balanced trade-off between shadow quality and computational costs. In this study, two approaches are proposed: Quadratic Spline Interpolation (QSI) to soften the outline of the shadow and Detail Multi-Layer (DML) technique to optimize the volume of computations for the generation of soft shadows based on real light sources. QSI estimates boarder hard shadow samples while DML involves three main phases: real light sources estimation, soft shadow production and reduction of the complexity of 3-Dimensional objects’ shadows. To be more precise, a reflective hemisphere is used to capture real light and to create an environment map. The Median Cut algorithm is implemented to locate the direction of real light sources on the environment map. Subsequently, the original hard shadows are retrieved and a sample of multilayer hard shadows is produced where each layer has its unique size and colour. These layers overlap to produce soft shadows based on the real light sources’ directions. Finally, the Level of Details (LOD) algorithm is implemented to increase the efficiency of soft shadows by decreasing the complexity of vertex transformations. The proposed technique is tested using three samples of multilayer hard shadows with varying numbers of light sources generated from the Median Cut algorithm. The experimental results show that the proposed technique successfully produces realistic soft shadows at low computational costs.     

Toughening Mechanisms in Cemented Carbides

Plastic zones much larger than previously expected have been observed around cracks in several cemented carbide materials. A preliminary estimate of the crack tip shielding due to the plastic zone in one material suggests that a substantial fraction of the fracture toughness may be due to the zone. Moreover, reduced zone sizes were observed in regions of rapid crack growth, implying that the dynamic fracture toughness may be smaller than the quasi-static value.     

Design of all-optical simultaneous AND,NAND, OR,and NOR logic gates using phase-based control of three coupled waveguides

In this paper, we present a novel phase-based structure for implementing the all-optical multi-function logic gates. The proposed structure which is composed of three coupled waveguides allows us to simultaneously access OR/NOR and AND/NAND logic functions from different output ports. The phase of middle waveguide plays the role of control tool which defines the logical values of outputs. The output ports can be switched from OR/NOR to AND/NAND logic functions by changing the control phase from 24\(^{\circ }\) to 237\(^{\circ }\), respectively. Beam propagation method has been employed in order to accomplish the simulations of light propagation.