The unified power quality conditioner: the integration of series and shunt-active filters

This paper deals with unified power quality conditioners (UPQCs), which aim at the integration of series-active and shunt-active power filters. The main purpose of a UPQC is to compensate for voltage flicker/imbalance, reactive power, negative-sequence current and harmonics. In other words, the UPQC has the capability of improving power quality at the point of installation on power distribution systems or industrial power systems. This paper discusses the control strategy of the UPQC, with a focus on the how of instantaneous active and reactive powers inside the UPQC. Experimental results obtained from a laboratory model of 20 kVA, along with a theoretical analysis, are shown to verify the viability and effectiveness of the UPQC     

Time-domain electronic-noise generation for a Monte Carlo study of signal processing

A general technique to generate electronic noise was developed in a time-domain approach with the aid of a deconvolution technique in a discrete-time sampling system. We found that the technique is applicable even for a system in which the electronic-noise charge is not well defined. The generated noise train was reconstructed in terms of a sample-correlated function and the frequency spectrum.     

Polymer film deposition with fine pitch openings by stencil printing

It is confirmed that stencil printing with a novel developed printable polyimide paste can be used for polymer film deposition on LSI wafers. A thick polyimide film with openings for solder ball bumping can be deposited on all of the LSIs on a wafer by stencil printing at one time. This stencil printing process does not need an expensive lithography process, providing cost-effective wafer-level chip scale packages (WLCSPs). In this study, a novel polyimide paste was tailored to have a higher thixotropy ratio than conventional printable polyimide materials. The novel printable polyimide paste shows that the viscosity ratio of more than 3.5 at the shear rate of 1 to 10 s⁻¹ and that the viscosity increases rapidly after the shear rate is lowered. Fine spaces of 40 μm between 250 μm openings were obtained for 10 μm thick polyimide films on Si wafers. It has been also confirmed that the new paste shows the variation range of 30 μm at the opening size of 385 μm within 100 continuously printed wafers. Even after the new paste was shear-thinned repeatedly, rheological behavior of the new paste was not changed. This robustness leads to higher efficiency of the materials for mass-producing. From the reliability viewpoint of the printed polyimide films, no peelings were observed on plasma-CVD SiN films after the pressure cooker test under the condition of 127 °C and 0.25 MPa with the humidity of 100% for 300 h. The optimal stencil printing process using the novel developed paste will lead to significant cost reduction of a patterned polymer deposition process. Finally, WLCSPs using the stencil printing of the new polyimide paste have been demonstrated for SRAM LSIs on 8-in. wafers.     

Uncertainty‐conscious methodology for process performance assessment in biopharmaceutical drug product manufacturing

This work presents an uncertainty‐conscious methodology for the assessment of process performance—for example, run time—in the manufacturing of biopharmaceutical drug products. The methodology is presented as an activity model using the type 0 integrated definition (IDEF0) functional modeling method, which systematically interconnects information, tools, and activities. In executing the methodology, a hybrid stochastic–deterministic model that can reflect operational uncertainty in the assessment result is developed using Monte Carlo simulation. This model is used in a stochastic global sensitivity analysis to identify tasks that had large impacts on process performance under the existing operational uncertainty. Other factors are considered, such as the feasibility of process modification based on Good Manufacturing Practice, and tasks to be improved is identified as the overall output. In a case study on cleaning and sterilization processes, suggestions were produced that could reduce the mean total run time of the processes by up to 40%. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1272–1284, 2018     

Enhancement of Thermoelectric Properties in Surface Nanostructures

The thermoelectric properties of TiN/MgO surface nanostructures have been determined using first-principles calculations based on the nonequilibrium Green’s function (NEGF) method. Through structural modification of the surfaces at the atomistic level, we find that the metallic TiN thin-film layer becomes semiconducting with a small bandgap, which enhances the Seebeck coefficient, while the electrical conductivity remains high at room temperature. Hence, a much larger thermoelectric figure of merit is obtained compared with bulk. These findings indicate the possibility of designing thermoelectric devices with surface nanostructures.     

Adsorption of benzoic acid and phenol from aqueous solution by activated carbons—effect of surface acidity

Effect of surface acidic groups of activated carbons on their adsorption characteristics for substrates from aqueous solutions were studied. Six kinds of carbons obtained commercially and their heat-treated products were used. Pore-size distribution, BET surface area and surface acidity were measured. Adsorption isotherms for benzoic acid and phenol from aqueous solutions (single or double components) were obtained. Substitution adsorption, i.e. substrate adsorbed preliminarily is substituted by another substrate, was also carried out. It was found that adsorption of benzoic acid is scarcely affected by surface acidity of carbons and the amount adsorbed is almost entirely controlled by the specific surface area of carbons. On the contrary, adsorption of phenol is retarded considerably by the acidity of carbons. In the case of solution of double components, benzoic acid is adsorbed predominatedly. The phenol adsorbed preliminarily is easily substituted by benzoic acid, but the substitution of benzoic acid by phenol scarcely proceeds.     

Analysis of particle trajectories of small particles in flotation when the particles and bubbles are both charged

The trajectory of a small particle moving to a bubble surface was analyzed by taking into account the effects of surface charges of the bubble and particle and the short range hydrodynamic interaction near the bubble surface, in a flotation process. The particle trajectories obtained theoretically were in good agreement with those obtained by direct observation. Even if the signs of the surface charges of the bubble and particle were the same, the particle adhered to the bubble surface when the net surface force, that is, the sum of the electrostatic force and the van der Waals force, was attractive. Particle capture efficiency, η_S, per bubble was estimated by trajectory analysis and the flotation efficiency, η_T, was calculated. The values of η_T calculated by the particle trajectory analysis were in reasonable agreement with those obtained experimentally. The dependence of particle diameter on η_T was also examined by the particle trajectory analysis.     

Relations between the molecular aggregation state and ionic conductivity in photopolymerized crosslinking polymers with oligo(oxyethylene) chains

A mixture of a vinyl monomer and a crosslinking agent was photopolymerized to form a crosslinked polymer film. Methacrylate with pendant oligo(oxyethylene) chain and poly(ethylene glycol) dimethacrylate were used as the vinyl monomer and crosslinking agent, respectively. The ionic conductivity of the film increased with an increasing concentration of LiClO₄ and then decreased. The size of the quasicrystalline aggregation phase composed of pendant and crosslinking chains in the film decreased with an increasing concentration of LiClO₄. The amorphous pendant and crosslinking oxyethylene chains gave rise to increased segmental motion and conductivity. The dissolution was depressed for a decrease in the ionic conductivity at a high LiClO₄ concentration at which the interactions among ions became stronger and the crystal phase of LiClO₄ was formed. The amount of the dissolution of the aggregation phase increased with an increasing crosslinking agent concentration. The quasicrystalline aggregation phase became larger with an increasing length of the pendant chains, and an increase in the size of the aggregation phase resulted in a decrease in the ionic conductivity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1272–1277, 2002