BRBF response modification factor

In this paper, overstrength, ductility and response modification factor of Buckling Restrained Braced frames were evaluated. To do so, buildings with various stories and different bracing configuration including diagonal, split X, chevron (V and Inverted V) bracings were considered. Static pushover analysis, nonlinear incremental dynamic analysis and linear dynamic analysis have been performed using Opensees software. The effects of some parameters influencing response modification factor, including the height of the building and the type of bracing system, were investigated. In this article seismic response modification factor for each of bracing systems has been determined separately and tentative values of 8.35 and 12 has been suggested for ultimate limit state and allowable stress design methods.     

Predictive Mitigation of Timing Channels - Threat Defense for Machine Codes

The security of software systems can be threatened by many internal and external threats, including data leakages due to timing channels. Even if developers manage to avoid security threats in the source code or bytecode during development and testing, new threats can arise as the compiler generates machine codes from representations at the binary code level during execution on the processor or due to operating system specifics. Current approaches either do not allow the neutralization of timing channels to be achieved comprehensively with a sufficient degree of security or require an unjustifiable amount of time and/or resources. Herein, a method is demonstrated for the protected execution of software based on a secure virtual execution environment (VEE) that combines the results from dynamic and static analyses to find timing channels through the application of code transformations. This solution complements other available techniques to prevent timing channels from being exploited. This approach helps control the appearance and neutralization of timing channels via just-in-time code modifications during all stages of program development and usage. This work demonstrates the identification of threats using timing channels as an example. The approach presented herein can be expanded to the neutralization of other types of threats.     

R2T-DSDN: reliable real-time distributed controller-based SDN

The Journal of Supercomputing - Software-defined network (SDN) is an emerging network architecture in which the network control task is separated from packet forwarding. This architecture can be...     

Characterization of the evolution of the volume fraction of precipitates in aged AlMgSiCu alloys using DSC technique

Differential scanning calorimetry is used to quantify the evolution of the volume fraction of precipitates during age hardening in AlMgSiCu alloys. The calorimetry tests are run on alloy samples after aging for various times at 180 °C and the change in the collective heat effects from the major precipitation and dissolution processes in each run are used to determine the precipitation state of the samples. The method is implemented on alloys with various thermal histories prior to artificial aging, including commercial pre-aging histories. The estimated values for the relative volume fraction of precipitates are compared with the results from a newly developed analytical method using isothermal calorimetry and a related quantitative transmission electron microscopy work. Excellent agreement is obtained between the results from various methods.     

A study on magnetic field of electospinning jet bending instability and magnetic field-assisted alignment mechanism

Bending instability in electrospinning jet motion is the main cause of irregular collection of nanofibers on the collector. This instability forces the jet to go on a conical solenoid like motion, and produce a magnetic field which stabilizes the jet. In this paper, ViziMag software was used to calculate the produced magnetic field through simulating jet motion and investigate some influential parameters including voltage and tip to target distance on field strength. Then, the mechanism of applying external magnetic field in magnetic field-assisted electrospinning (MFAES) was investigated based on the summation of simulated jet magnetic field lines and external magnets drawn by ViziMag software. The magnetic field produced due to electrospinning jet was too small to have any effect on jet alignment but the main cause of alignment in MFAES was collecting the charged jet exactly on the field lines of external magnets which act similar to iron fillings.     

In-situ laser-fabrication and characterization of TiC-containing Ti–Co composite on pure Ti substrate

This work presents the in-situ fabrication of a layered metal-matrix composite coating on a pure Ti substrate. The coating consists of a matrix of cobalt-titanium intermetallics and the reinforcement phase of titanium carbide. The fabrication process is laser cladding, conducted using a pre-placed powder mixture of elemental titanium, cobalt, and graphite. Several materials characterization methods including microscopy, microhardness and nano-indentation are used to study the coating and coating–substrate interface. The intermetallic phases in the matrix vary from Co-rich phases at the coating surface to Ti-rich compounds near the substrate. The interface is revealed to have a smooth profile, free of any porosity or cracks, with good metallurgical bonding to the substrate. A relatively uniform hardness in the range of 1200–1300 HVN is achieved through a depth of 200 μm into the coating. The hardness then gradually decreases to 480 HVN at the substrate interface, approximately 300 μm from the surface. The hardness evolution, which is predictable using the Rule of Mixtures, is explained by the fraction of the carbide particles and the type of intermetallic compounds in the matrix.     

Collagen-g-poly(Sodium Acrylate-co-Acrylamide)/sodium montmorillonite superabsorbent nanocomposites: synthesis and swelling behavior

Nanocomposite superabsorbents were synthesized by graft copolymerization of mixture of acrylamide (AAm) and acrylic acid (AA) onto collagen using potassium persulfate (KPS) as a free radical initiator and methylenebisacrylamide (MBA) as a crosslinker. Nanoclay sodium montmorillonite (MMt) was introduced as filler into superabsorbent. The chemical structure of the Collagen-g-poly(Sodium Acrylate-co-Acrylamide)/MMt nanocomposite was characterized by means of FTIR spectroscopy, XRD patterns, and TGA thermal methods. Morphology of the sample was examined by scanning electron microscopy (SEM). The effects of reaction variables were systematically optimized to achieve a superabsorbent with swelling capacity as high as possible. Under the optimized conditions concluded, the maximum swelling capacity in distilled water was 950 g/g. Dewatering of nanocomposite and clay-free superabsorbent revealed that inclusion of nanoclay into superabsorbents can improve water retention of superabsorbent under heating. The swelling ratio in various salt solution and kinetic of dewatering was also determined and additionally, the swelling of nanocomposite superabsorbent was measured in solution with pH ranged 1–13. The synthesized nanocomposite exhibited a pH-responsive characteristic.     

Fabrication of nano-structured electrospun collagen scaffold intended for nerve tissue engineering

Nerve tissue engineering is one of the most promising methods in nerve tissue regeneration. The development of blended collagen and glycosaminoglycan scaffolds can potentially be used in many soft tissue engineering applications. In this study an attempt was made to develop two types of random and aligned electrospun, nanofibrous scaffold using collagen and a common type of glycosaminoglycan. Ion chromatography test, MTT and attachment assays were conducted respectively to trace the release of glycosaminoglycan, and to investigate the biocompatibility of the scaffold. Cell cultural tests showed that the scaffold acted as a positive factor to support connective tissue cell outgrowth. The positive effect of fiber orientation on cell outgrowth organization was traced through SEM images. Porosity percentage calculation and tensile strength measurement of the webs specified analogous properties to the native neural matrix tissue. These results suggested that nanostructured porous collagen-glycosaminoglycan scaffold is a potential cell carrier in nerve tissue engineering.     

The effect of partially stabilized zirconia on the biological properties of HA/HDPE composites in vitro

The effect of partially stabilized zirconia (PSZ) on the biological properties of the hyroxyapatite - high density polyethylene (HA/HDPE) composites was studied by investigating the simultaneous effect of hydroxyapatite and PSZ volume fractions on the in vitro response of human osteoblast cells. The biocompatibility of composite samples with different volume fraction of HA and PSZ powders was assessed by proliferation, alkaline phosphatase (ALP) and cell attachment assays on the osteoblast cell line (G-292) in different time periods. The effect of composites on the behavior of G-292 cells was compared with those of HDPE and TPS (Tissue Culture Poly Styrene as negative control) samples. Results showed a higher proliferation rate of G-292 cells in the presence of composite samples as compared to the HDPE sample after 7 and 14 days of incubation period. ALP production rate in all composite samples was higher than HDPE and TPS samples. The number of adhered cells on the composite samples was higher than the number adhered on the HDPE and TPS samples after the above mentioned incubation periods. These findings indicates that the addition of PSZ does not have any adverse affect on the biocompatibility of HA/HDPE composites. In fact in some experiments PSZ added HA/HDPE composites performed better in proliferation, differentiation and attachment of osteoblastic cells.     

Glucosamine conjugated iron oxide and graphene oxide nanohybrid for smart drug delivery

Smart drug delivery systems have attracted a lot of attention as one of the new treatment methods for cancer. In this study, a smart drug delivery system carrying anticancer drugs was obtained by the intelligent synthesis of glucosamine (GA)-functionalized graphene oxide (GO)-based iron oxide nanoparticles (Fe₃O₄@GO-GA) using Hummers and chemical co-precipitation processes. Nanohybrids have a high surface area (280.26 m²/g) and superparamagnetic behaviour (Ms = 26.017 emu/g), indicating a significant loading capacity (373.78 mg/mg) and efficiency (96.3%) for pharmaceutical loading. An adsorption study of conventional daunorubicin (DNR) on this carrier showed that the drug release is more prone to occur under acidic conditions (pH = 5.5), at moderately high temperatures (T = 40°C), and in the absence of smart carriers. The toxicity of the smart nanohybrids was examined using the sulphorhodamine B (SRB) assay in Michigan Cancer Foundation-7 (MCF-7) cell lines. The rate of death of cells exposed to smart drug-containing systems in comparison to the systems without GA shows that GA reduces the toxicity of Fe₃O₄@GO.