Spark Parameter Monitoring Feedback System for Preparation of Nanosilver Colloid in EDM

This study developed a system monitoring the electric discharge machine's (EDM) discharge energy and success rate to replace conventional oscilloscope observation. By using logic circuit, the signals are transmitted to the PC monitoring platform in order to display the discharge success times, discharge success rate, and electrode's consumption energy. The advantage of the proposed system is the capability to observe real-time discharges and record the experimental conditions, as well as optimize the discharge parameter settings. The experimental results suggest that, in the preparation of nanosilver colloid, the cost-performance of T_on–T_off at 10–100 µs is the optimal setting. The monitoring system also can take advantage of the discharge success rate to control the energy consumption of the electrode to obtain the standardization of products. The results suggest that, while discharge success rate, electrode's weight loss and wavelength of the absorption peak are considerably accurate, but concentration accuracy is relatively poor. The discharge success rate monitoring system is an innovative method that can help to realize electric discharge processing, optimize product quality, and it may be a powerful processing tool in the future.     

Challenges and research directions for heterogeneous cyber–physical system based on IEC 61850: Vulnerabilities,security requirements,and security architecture

IEC 61850, an international standard for communication networks, is becoming prevalent in the cyber–physical system (CPS) environment, especially with regard to the electrical grid. Recently, since cyber threats in the CPS environment have increased, security matters for individual protocols used in this environment are being discussed at length. However, there have not been many studies on the types of new security vulnerabilities and the security requirements that are required in a heterogeneous protocol environment based on IEC 61850. In this paper, we examine the electrical grid in Korea, and discuss security vulnerabilities, security requirements, and security architectures in such an environment.     

Palladium(II) extraction from concentrated chloride media: Reactions involving thioamide derivatives

This work focuses on the detailed study of the palladium(II) extraction reactions by N-methyl-N-phenyl-octanthioamide (MPHTA) and N-methyl-N-cyclohexyl-octanthioamide (MCHTA) in toluene, since their ability to efficiently and selectively recover Pd(II) from a wide range of HCl concentrations is already known. Equilibrium data are presented and discussed, and further complemented by information depicted from UV–visible and NMR spectra. The determined apparent molar volumes show that MPHTA is monomeric, and MCHTA exhibits a slight tendency to aggregate. The Pd(II) extraction reactions by MPHTA and MCHTA are equivalent until 4.5 M HCl, passing through the formation of inner-sphere complexes with the metal ion.     

Effect of CuO as a dopant in TiO2 on ammonia and hydrogen sulphide sensing at room temperature

The heterogeneous nanocomposites of CuO doped TiO₂ nanoparticles were synthesized using sol gel method by varying the concentration of CuO as 0.1, 0.5 and 1 mol% for the sensing of ammonia and hydrogen sulphide. The substitutional doping of CuO in TiO₂ matrix was confirmed by the X-ray diffraction. Average crystallite size of the doped nanocomposites was found to reduce with increase in concentration of CuO. The 0.1 mol% CuO doped TiO₂ nanocomposites showed highest sensitivity to ammonia (97%) with response time of 2 s, while 1 mol% was selective to H₂S gas (77%) with response time of 45 s for 50 ppm of each gas at room temperature.     

The Cut and the Continuum: Sophie Ristelhueber’s Anatomical Atlas

From her early photographs of the ruinous aftermath of the Lebanon War in Beirut (1982) to her more recent images of bomb craters in Eleven Blowups (2006), the French artist Sophie Ristelhueber has been intent to maintain, in her own metaphor, ‘the analytical distance of an anatomy lesson’. Exhibiting the evidence of warfare but withholding their explanation, Ristelhueber’s provocative gesture of making art of war, removing human conflicts from their political contexts to render them as still-lifes, ready-mades, earthworks, or surrealist poems, is patently anti-journalistic. In keeping with the artist’s surgical analogy, this article explores Ristelhueber’s aesthetic mode of address as one that shares its fundamental operation with that of photography – namely, to make a cut. Retracing the morphology of recurring imprints and injuries that appear across the terrestrial and corporeal expanses traversed in her work, the article considers the ways in which these cuts pertain to the transformative power of violence and images alike.     

Synthesis of barium strontium titanate quasi photonic crystals with nanopore arrays by sol–gel technique

We report on the synthesis, characterization and optical properties of barium strontium titanate (BST) quasi photonic crystals (PCs) through a sol–gel technique with the porous alumina template (PAT). The structure, morphology and pore-size distribution of the samples were characterized by SEM, XRD and EDS, The Ba_0.6Sr_0.4TiO₃ PCs of crystalline cubic phase with uniform pore size and ordered arrange were successfully synthesized. The obtained quasi BST PCs not only show that the nanostructure has spatially periodical orderly arrangement, but also exhibit good optical transmittance properties. The advantage of this sol–gel technique with PAT to fabricate ferroelectric (FE) nanopore arrays lies in its low cost and simplicity. This study opens a pathway for the effective fabrication and studies of FE nanopore arrays in uniquely large area.     

Local Gibbs–Markov–Young structures for non-invertible systems

We study non-uniformly expanding systems on a compact Riemannian manifold admitting critical sets. Under some general conditions, we construct a Gibbs–Markov–Young structure on a disk whose centre's preimages are dense in the manifold. The result has the following application: in a previous study, the authors showed that the decay of correlations implies the existence of tower structure whose return time decays at the same rate. However, for technical reasons, they have to assume that the density function for the absolutely continuous measure is bounded away from 0. Now we remove this constraint and provide the arguments for the more general results.     

Structure and magnetic properties of a multi-principal element Ni–Fe–Cr–Co–Zn–Mn alloy

A nanocrystalline alloy with a nominal composition of Ni₂₀Fe₂₀Cr₂₀Co₂₀Zn₁₅Mn₅ was produced by mechanical alloying and processed using annealing treatments between 450 and 600 °C for lengths from 0.5 to 4 h. Analysis was conducted using x-ray diffraction, transmission electron microscopy, magnetometry, and first-principles calculations. Despite designing the alloy using empirical high-entropy alloy guidelines, it was found to precipitate numerous phases after annealing. These precipitates included a magnetic phase, α-FeCo, which, after the optimal heat treatment conditions of 1 h at 500 °C, resulted in an alloy with reasonably good hard magnetic properties. The effect of annealing temperature and time on the microstructure and magnetic properties are discussed, as well as the likely mechanisms that cause the microstructure development.     

Noise reduction of ultrasonic Doppler velocimetry in liquid metal experiments with high magnetic fields

The last decades have seen a number of liquid metal experiments on the interaction of magnetic fields with the flow of electrically conducting fluids. The opaqueness of liquid metals requires non-optical methods for inferring the velocity structure of the flow. Quite often, such experiments are carried out in the presence of high electrical currents to generate the necessary magnetic fields. Depending on the specific purpose, these currents can reach several kiloamperes. The utilized switching mode power supply can then influence seriously the measurement system by electromagnetic interference. A recent experiment on the azimuthal magnetorotational instability (AMRI) has shown that a hydrodynamically stable Taylor–Couette flow becomes unstable under the influence of a high azimuthal magnetic field. An electrical current along the axis of the experiment with up to 20 kA generates the necessary field to destabilize the flow. We present experimental results of this AMRI experiment carried out at the PROMISE facility with an enhanced power supply. For this setup, we discuss the elaborate measures that were needed to obtain a reasonable signal-to-noise ratio of the ultrasonic Doppler velocimetry (UDV) system. In dependence on various parameter variations, some typical features of the observed instability, such as the energy content, the wavelength, and the frequency are analyzed and compared with theoretical predictions.     

Effect of sol–gel MgO spin-coating on the performance of TiO2-based dye-sensitized solar cells

This paper is concerned with the improvement of dye-sensitized solar cell (DSSC) efficiency upon MgO post-treatment of the TiO₂ electrode. A simple sol–gel technique, involving magnesium acetate as precursor, ethanol as solvent and nitric acid as stabilizer, is applied to prepare a solution of suspended MgO nanoparticles. A single drop of MgO sol at 0.1 M precursor concentration was spin-coated at 3000 rpm for 30 s onto the TiO₂ electrode and sintered at 500 K for 1 h. Dye-loading using N3-dye was applied for 6 h. An increase in the average efficiency of the DSSC from 2.5% to 3.9% (over 50% enhancement) was recorded. Measurements of the dark I–V characteristics, the open circuit voltage decays, the SEM images and the dye absorbance spectra, for both uncoated and MgO-coated electrodes were examined. The improvement of the DSSC efficiency was attributed to an upward shift of the TiO₂ flat band energy and a reduction of the rate of back-transport and recombination.