Off-stoichiometry effect on the CuInSe2 dielectric function

The dielectric function of CuInSe₂ has been studied for various composition ratios of Cu/In. The crystals were cut from ingots of 10 mm diameter and 40 mm length, grown by the classical Bridgman method. Spectroscopic ellipsometry measurements have been performed at room temperature in the range of 1.5–5.5 eV. From the measured spectra of the imaginary part of the dielectric function ₂, the broadening effect of the Cu/In ratio has been examined in connection with photoluminescence measurements. All transition edges were found to broaden as the In content increases. The effect of copper d levels has been observed to dominate in the 2.5–3.5 eV range.     

Investigating the performance of ice slurry system and the growth of ice crystals using seawater

Journal of Mechanical Science and Technology - This study investigates ice slurry systems, their transport characteristics, and seawater ice crystal formation through microscopy. Here, the salinity...     

Enhanced electrochemical performance of graphitic carbon-wrapped spherical FeOF nanoparticles using maleopimaric acid as a cathode material for sodium-ion batteries

Sodium-ion batteries(SIBs)are considered one of the most promising energy storage systems for replac-ing lithium-ion batteries because of the high abundance and low cost of sodium.Iron oxyfluoride(FeOF)is a promising conversion-based cathode material for SIBs because of its high theoretical capacity of about 855 mA h g-1,low-cost chemical compositions,and its lower sensitivity to the size of charged carrier ions.However,the poor electrical conductivity and ionic diffusion of FeOF result in a low rate capability and cyclability.In this work,FeOF nanoparticles wrapped by graphitic carbon layers were synthesized using abietic or maleopimaric acid as both the carbon source and organic ligand.In addition,the mor-phology of the FeOF particles was gradually controlled from rod to spherical shapes,simply depending on the rosin acids.The FeOF nanoparticles prepared with maleopimaric acid showed a large reversible discharge capacity of 356.7 mA h g-1 with a fading rate of 0.21％per cycle after 100 cycles at a current density of 100 mA g-1 and an excellent rate capability.     

Hydraulics conveyances of mud slurry by a spiral pipe

Indonesia particularly East Java has been suffering from eruption of gas and mud slurry, caused by oil and gas exploration. Everyone calls this disaster as Sidoarjo mud or Lapindo mud. Mud slurry is essentially a mixture of a carrying fluid and solid particles held in suspension. When the mud slurry flow speed is not sufficiently high the particles will not be maintained in suspension. In spiral pipe twisted with a constant pitch in relation to the axis a swirling flow occurs when fluids flow in the pipe. The aim of this study is to examine characteristics of the hydraulic transport of mud slurry flowing in the spiral pipe with three-shape groove pipe walls. The shear stress and the shear strain are calculated by measuring the pressure drop and the volumetric flow rate in circular pipe, respectively. The power law exponent were about 0.93–1.0 for mud slurry solution of 45%, 30% and 20% of weight concentrations. The diameter of particles was 0.95 mm and the density was 2.19 × 10³ (kg/m³). The apparent viscosity of mud slurry solution is not constant to the shear strain but the relationship is approximated by model of power law. The friction factor of mud slurries in a spiral pipe with ratio pitch per diameter 6.7 is lower than circular pipe and spiral pipe with P/Di= 3.9 and 4.3. It was shown that the spiral pipe caused drag reduction in flowing of mud slurries. The drag reduction ratio of spiral pipe was about 28% for Cw=30% at Re’=32 × 10³. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Yanuar received his B.S. degree in Mechanical Engineering from Indonesia University, Indonesia, in 1986. He then received his Master of Eng. and Doctor of Eng. in Mechanical Engineering from University of Tokyo Metropolitan, Japan, in 1995 and 1998, respectively. Professor at Mechanical Engineering at University of Indonesia in Jakarta, Indonesia.     

Sensitivity analysis of steam power plant-binary cycle

This paper analyses a steam power – two-stage binary cycle plant (SPP–2BCP), in which low temperature waste heat from a conventional steam power plant can be efficiently utilized to generate electricity by installing a bottoming binary cycle. The result from a previous calculation on the installation of binary cycle technology on a Steam Power Plant (SPP) with n-Pentane working fluid indicates an increase in plant efficiency of about 9%. The purpose of this study is to analyze the sensitivity of performance of the binary cycle system against variations in the SPP operational load and the condenser’s cooling water temperature. The calculation is conducted on SPP load variations of 25%, 50%, 75% and 100%, inlet turbine pressure variations of 5 bar–30 bar, and inlet turbine temperature variations of 125 °C up to 235 °C. Each of these is also analyzed with ambient cooling water temperatures of 30 °C–37 °C. The results of the analysis indicate that the performance of this binary cycle SPP degrades slightly with SPP load, turbine inlet temperature, and turbine inlet pressure variations and with cooling water variations.     

Finite element modeling of capacitive coupling voltage contrast

Capacitive coupling voltage contrast (CCVC) is proven to be able to detect broken track in high density organic substrate with solder mask on top of the tracks. In this work, we develop a finite element model to solve the electromagnetic equations and determine the surface voltage of the solder mask under the interaction of the electron beam and the electrostatic induction due to the biasing of the underlying track. As the brightness of an image under SEM depends on the surface voltage of the object under observation, our model is able to explain the experimental observations of CCVC accurately. This model also examines the limitation of the CCVC.     

Lead sulphide/phthalocyanine nanocomposite spun films

Composite lead sulphide/phthalocyanine thin films were produced for the first time by exposure of thin spun films of a lipophilic lead phthalocyanine derivative to H/sub 2/S gas. The formation of lead sulphide was confirmed by Raman and X-ray photoelectron spectroscopy measurements. UV-visible absorption and photoluminescence spectral measurements as well as a film morphology study using atomic force microscopy indicate the formation of lead sulphide clusters. From the blue spectral shift of the fundamental adsorption band, the size of the PbS clusters was estimated to be 2.24 nm.