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This study presents the results of a numerical investigation on static resistance of welded planar steel tubular joints under in-plane and out-of-plane bending moments at elevated temperatures. The numerical simulations were carried out using the commercial finite Element software ABAQUS v6.14-1 and the simulation model was validated by comparing against test results for CHS joints under brace in-plane bending at elevated temperatures. Extensive numerical parametric simulations were performed for CHS/SHS/EHS joints under in-plane and outof- plane bending at elevated temperatures, to establish a database of results covering a wide range of geometrical parameters, including brace to chord diameter ratio, the angle between brace to chord members, and chord diameter to twice chord thickness ratio. The ratios of joint elevated temperature resistance to ambient temperature resistance were compared to the steel yield strength reduction factor, the steel Young’s modulus reduction factor, and the average of the above these reduction factors at different elevated temperatures. Based on the comparisons, it has been found that using the reduction factor for the yield strength of steel to modify the ambient temperature equations will overestimate the resistance of joints at elevated temperatures. As a simplified and safe recommendation, the ambient temperature joint resistance equations can be modified by the average reduction factors for the Young’s modulus and yield strength at elevated temperatures. This modification factor can be increased to the yield strength reduction factor when the brace and chord widths/diameters are the same. This research is supported by the Scientific and Technological Research Council of Turkey (TUBITAK-BIDEB, 2219 International Post-Doctoral Research Fellowship Programme). The authors would also like to acknowledge partial funding by CIDECT through its project 15U-7/18 Joints at high temperatures.

This study presents the results of a numerical study to develop a method to calculate the static strength of welded Elliptical Hollow Section (EHS) joints at elevated temperatures. Extensive numerical simulations using the nonlinear finite element package, ABAQUS v6.14–1 on EHS T- and X-joints under brace axial compression or tension and pre-stress in chord member with different type of joint orientations at elevated temperatures over a wide range of diameter ratio have been conducted. The adjustments required to be made to the equations of joint resistance under ambient temperature conditions for estimating joint resistance at elevated temperature conditions are investigated in this study. The FE simulation results have been compared with the calculation results of a number of existing methods at ambient temperature. It has been found that the method proposed by Packer et al. gives the best agreement with the authors' simulation results at ambient temperature. At elevated temperatures, for T- and X- joints with braces in compression welded to the wide sides of chords, replacing the ambient temperature yield strength of steel by the elevated temperature value in the current design method overestimates the ultimate load carrying capacity of axially loaded EHS T- and X-joints due to inability of the ambient temperature calculation equations to take into consideration EHS flattening at high temperatures. For these cases, it is recommended to calculate the joint strength reduction factor at elevated temperatures according to the Young's modulus of steel. The authors would like to thank CIDECT for partial funding of the research of this paper through a CIDECT project 15U-7/18 – Welded Joint Strength at Elevated Temperatures.

Silver colloidal nanospheres have been synthesized via electrochemical method. The absorption spectrum features show two peaks at 410 and 470 nm, which result from transverse and longitudinal surface plasmon resonance, respectively. Two kinds of fluorescence emission peaks are observed. The shorter wavelength peaks fixed at about 315 nm are due to the local field enhancement and the longer wavelength peaks red shift with the increasing excitation wavelength, which results from the electron interband transitions.

The charge distribution on the surface of gold nanoellipsoid is different from direction. This anisotropic charge density can further influence the collective behavior of surface electrons. Therefore, ellipsoidal gold nanoparticles exhibit two surface plasmon bands corresponding to transverse and longitudinal resonance, respectively. Theoretical calculation shows a nonlinear relationship between the absorption maximum of the longitudinal plasmon resonance and the mean aspect ratio, which is in agreement with the experimental results.

Gold colloidal nanochains with different morphology have been synthesized via electrochemical method. The absorption spectrum features show two peaks at 530 and 780 nm, which result from transverse and longitudinal surface plasmon resonance, respectively. Fluorescence spectrum properties have also been studied, three emission peaks are observed at 370, 660 and 735 nm. These fluorescence emission peaks are due to the local field enhancement via coupling to the transverse and longitudinal surface plasmon resonance.

Aqueous solutions containing a high yield of suspended pure silver, pure gold and silver-coated gold nanoshells have been synthesized via an electrochemical method. UV-vis absorption spectra and fluorescence emission spectra have been measured at room temperature. The absorption spectra show two peaks at 445 and 485 nm, which due to the plasmon resonance of silver-coated gold nanoparticles. Fluorescence emission peaks have been observed in the wavelength region of 550–700 nm. The emission peak corresponding to solid silver particles is more intensive than the peaks corresponding to silver-coated gold nanoshells and solid gold particles. The relationship between relative thickness of silver shell and fluorescence intensity has been illuminated from the quasi-static and local field theory. With decreasing the thickness of silver shell, the maximum of local field enhancement factor decrease and red shifts nonlinearly.

Suspended gold nanorods have been synthesized via an electrochemical method. The absorption spectrum features show two peaks at 520nm and 650nm, which result from the transverse and longitudinal surface plasmon resonance. The spectra at different growth stages indicate that the absorption peaks split and shift after electrolysis, which correspond to the anisotropy growth of nanorods. The quasi-static calculation results indicate that with increasing the mean aspect ratio of the nanorods, the longer wavelength absorption peak decreases and red shifts obviously, whereas the shorter wavelength absorption peak blue shifts slightly.

Aqueous solutions containing a high yield of suspended gold nanorods with mean aspect ratio 2.5 have been synthesized via an electrochemical method. The fluorescence emission peaks fixed at 370 nm and 670 nm are due to the local field enhancement via coupling to the transverse and longitudinal surface plasmon resonance. The quasi-static calculation results indicate that with the increasing aspect ratio of the nanorods, the longer wavelength emission peak decreases and red shifts, whereas the shorter wavelength emission peak blue shifts slightly.

Highly ordered metal Sn nanodot arrays were prepared by vacuum electron beam evaporation using porous anodic alumina (PAA) membrane as the substrate. They were characterized by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM images indicated that the Sn nanodot arrays are highly ordered and coincid with the contours of porous anodic alumina. The shape of Sn nanodot is spherical and the diameter approximates the pore diameter of the PAA membrane. XRD showed that crystallographic structures of Sn nanodot arrays are the same as the bulk Sn. The forming process and mechanism of the Sn nanodot array was discussed.

The master equation of the single-electron triple-barrier tunnel-junction(TBTJ) model is developed based on the orthodox theory. The steady distribution of electrons on the Coulomb islands is obtained with the linear system of equations method and the I-V curves through the simulation method are presented in this paper. Discontinuities of the slope of the curve at the flat-form of Coulomb staircase compared to double barrier tunnel-junction system, which is caused by the change of the electron numbers on the second Coulomb island, are found. The system temperature requirement can be reduced in the TBTJ system, and the maximum temperature at which Coulomb staircase can be resolved is estimated using the energy spacing at the Fermi energy.