Sensitivity analysis of steel buildings subjected to column loss

In this study, the sensitivity of design parameters of steel buildings subjected to progressive collapse is studied. To this end, design parameters such as yield strengths of beams, columns, and braces, live load, elastic modulus, and damping ratio were considered as random variables. The Monte Carlo simulation, the Tornado Diagram analysis, and the First-Order Second Moment method were applied to deal with the uncertainties involved in the design parameters. The analysis results showed that among the design variables beam yield strength was ultimately the most important design parameter in the moment-resisting frame buildings while the column yield strength was the most important design parameter in the dual system building. Sensitivity of the vertical displacement to uncertain member strength showed that progressive collapse mechanisms of the moment-resisting frame buildings and the dual system building completely differed due to different patterns of the vertical load redistribution.     

A distributed energy-efficient clustering scheme for deploying IDS in MANETs

Cluster-based intrusion detection systems, where cluster heads (CHs) detect misbehavior of their member nodes, have been proposed in mobile ad-hoc networks (MANETs) in order to protect the network and save the energy. However, long-term survival of all nodes is more important so as not to partition the network. The extension of the network lifetime in the cluster-based IDS depends on which nodes are selected as CHs, which consume much more energy than cluster members due to monitoring them and detecting intrusions. In this paper, we propose a Distributed Energy Efficient Cluster Formation (DEECF) scheme, which exploits the expected residual energy of mobile nodes to select CHs and starts the cluster formation from leaf nodes to reduce the number of clusters. The scheme consists of the cluster construction algorithm and the cluster maintenance algorithm, both of which can be performed at each node in a distributed way without any global knowledge. We prove the correctness of the algorithms, and show that the DEECF scheme is more energy efficient than other clustering schemes by extensive simulation.     

Torsional stiffness requirements for diaphragm bracing of discretely braced I-girders

I-section girders are laterally interconnected by Torsional bracings that are discretely installed to increase resistance to lateral-torsional buckling. However, there are confusing discrepancies in the current design specifications for the stiffness of diaphragm-type bracings. The mathematical formula for determining the required torsional stiffness is still unclear. In this study, rigorous examinations were carried out to clarify the effects of the web distortional stiffness and the number of diaphragm bracings. To achieve the purpose of this study, the theoretical derivation of the stiffness equations was thoroughly examined. Three-dimensional finite-element analysis was used for the parametric numerical analyses of a series of feasible two-girder system models, and enhanced equations are proposed for achieving sufficient stiffness in the torsional bracings. The practical validity of the proposed equations are verified by statistical correlation analyses, which clearly prove their superiority compared to current design guidelines.     

Magnetic Polishing of Titanium-Nickel Alloy Stents: Surface Characterization and Catheter Deployment Test

We report here for the first time the use of magnetic polishing to improve the surface finish of titanium-nickel (TiNi) stents for better performance. We investigated the effects of polishing time and rotational speed on the average surface roughness, surface chemical contents, and push-out load of stents. The magnetically polished stents show a decrease of 2.3 to 17.9?pct in surface roughness and a lower push-out load for stent deployment from the catheter.     

Curing Behaviors of UV-Curable Temporary Adhesives for a 3D Multichip Package Process

Temporary bonding adhesives for a three-dimensional (3D) multichip package process have been synthesized. To enhance the thermal stability, the adhesives used a fluorinated silicon urethane acrylic binder and ultraviolet (UV) curing for crosslinked network structures. Focusing on different photoinitiator contents and UV doses, the UV-curing behaviors and thermal stability were studied using Fourier-transform infrared spectroscopy attenuated total reflectance, gel fraction, swelling ratio, shrinkage, and thermogravimetric analyses.     

Effect of pore size on the nucleate pool boiling of structured enhanced tubes

In this study, pool boiling test results are provided for the structured enhanced tubes having pores with connecting gaps. The surface geometry of the present tube is similar to that of Turbo-B. Three tubes with different pore size (0.20 mm, 0.23 mm and 0.27 mm) were manufactured and tested using R-11, R-123 and R-134a. The pore size which yields the maximum heat transfer coefficient varied depending on the refrigerant. For R-134a, the maximum heat transfer coefficient was obtained for the tube having 0.27 mm pore size. For R-11 and R-123, the optimum pore size was 0.23 mm. One novel feature of the present tubes is that their boiling curves do not show a ‘cross-over’ characteristic, which existing pored tubes do. The connecting gaps of the present tube are believed to serve an additional route for the liquid supply and delay the dry-out of the tunnel. The present tubes yield the heat transfer coefficients approximately equal to those of the existing pored enhanced tubes. At the heat flux 40 kW/m² and saturation temperature 4.4° C, the heat transfer coefficients of the present tubes are 6.5 times larger for R-11, 6.0 times larger for R-123 and 5.0 times larger for R-134a than that of the smooth tube     

Practical control for improving power density and efficiency of the BLDC generator

This work presents an advanced control technique for maximizing power density and efficiency of the brushless dc generator by using a linear tracking method and also suggests a sub-optimal control method in practical applications. In a generator of given rating, the weight and size of the system affect the fuel consumption directly; therefore, power density is one of the most important issues in a standalone generator. Conventional rectification methods cannot achieve the maximum power possible because of a nonoptimal current waveform. The optimal control scheme to maximize power density and minimize machine size and weight in a nonsinusoidal power supply system has been derived, incorporated in a control system, and verified by simulation and experimental work. A new simple algebraic method has been proposed to accomplish the proposed control without a fast Fourier transform which is time consuming and complicated.     

Surface-enhanced Raman scattering of dopamine on self-assembled gold nanoparticles

Dopamine, a potent neurotransmitter in the brain, influences a variety of motivated behaviors and plays a major role in Parkinson's disease. In this study, the Raman signal of dopamine was detected on a fabricated nanoparticle-immobilized glass surface by surface-enhanced raman spectroscopy (SERS). Amine-modified glass was prepared by the self-assembly of amine-terminated silane on substrate, followed by the deposition of gold nanoparticles. The gold nanoparticles deposited on the glass surface were functionalized by anti-dopamine or dopamine. The antigen-dopamine was captured by antibody-assembled gold substrate and detected by SERS. The optical properties and morpology of the glass substrate with immobilized gold nanoparticles were analyzed by scanning electron microscopy and UV-VIS absorption spectroscopy. The Raman spectrum of dopamine displayed broad bands at 1267, 1331, 1158, 1478, 1578 and 1584 cm(-1). The strongest peaks in the spectra (at 1267 and 1478 cm(-1)) were identified as phenolic carbon-oxygen and phenyl C=C stretches, respectively. A working curve of the SERS signal constructed from cathecol ring vibration versus antigen-dopamine concentration was obtained at 1478 cm(-1), and the non-optimized detection limit for anti-dopamine surface antigen was as low as 1 ng/ml. These results suggest that SERS-based immunosensor can be a promising tool for the detection and screening of neurotransmitters.     

Detection of dopamine in dopaminergic cell using nanoparticles-based barcode DNA analysis

Nanotechnology-based bio-barcode-amplification analysis may be an innovative approach to dopamine detection. In this study, we evaluated the efficacy of this bio-barcode DNA method in detecting dopamine from dopaminergic cells. Herein, a combination DNA barcode and bead-based immunoassay for neurotransmitter detection with PCR-like sensitivity is described. This method relies on magnetic nanoparticles with antibodies and nanoparticles that are encoded with DNA, and antibodies that can sandwich the target protein captured by the nanoparticle-bound antibodies. The aggregate sandwich structures are magnetically separated from solution, and treated in order to remove the conjugated barcode DNA. The DNA barcodes were then identified via PCR analysis. The dopamine concentration in dopaminergic cells can be readily and rapidly detected via the bio-barcode assay method. The bio-barcode assay method is, therefore, a rapid and high-throughput screening tool for the detection of neurotransmitters such as dopamine.     

In-plane strength and design of parabolic arches

In the current AASHTO LRFD, the arch design formula is based on the bilinear interaction relationship between two extreme cases of the axial and the flexural strength. However, this method is not suitable for the design of the shallow arch which may buckle in a symmetric snap-through mode. Also, the use of the constant reduction factor for the design of arches leads to a conservative design. This paper investigates the in-plane buckling strength and design of parabolic arches. Firstly, the thresholds for the different buckling modes of shallow parabolic arches are summarized and boundaries for the deep and shallow arches are reported. The inelastic strengths of parabolic deep arches based on the finite element analyses are then compared with those presented in AASHTO LRFD. From the results, it is found that AASHTO LRFD provides good predictions of buckling strengths for the parabolic arches under only axial compression, while the bilinear interaction relationship provides conservative values for the in-plane strength of parabolic arches due to the use of constant reduction factors that can be applied regardless of loading and boundary conditions. The modified formulas for reduction factors are proposed for various loading and boundary conditions in this study. It is found that modified formulas for reduction factors show good match with the results obtained from finite element analyses.