New effective treatment of the light-front nonvalence contribution in timelike exclusive processes

We discuss a necessary nonvalence contribution in timelike exclusive processes. Following a Schwinger-Dyson type of approach, we relate the nonvalence contribution to an ordinary light-front wave function that has been extensively tested in the spacelike exclusive processes. A complicate four-body energy denominator is exactly cancelled in summing the light-front time-ordered amplitudes. Applying our method to $K_{\ell3}$ and $D^0\to K^- \ell^+ \nu_l$ where a rather substantial nonvalence contribution is expected, we find not only an improvement in comparing with the experimental data but also a covariance(i.e. frame-independence) of existing light-front constituent quark model.Comment: 10 pages including 5 figures; Changes: 1-added some sentences; 2-enlarged the figures; 3-added some reference

Automatic Volume Control Based on Background Noise Characteristics

In this study, we propose a novel technique for automatic volume control (AVC). Contemporary AVC systems operate according to background noise level. This paper presentsan AVC system that adaptively updates the audio volumeconsidering the frequency characteristics of the background noise. From the experiments, we conclude that the developed techniques can be successfully used for various acoustic environments

Synthesis of colloidal metal oxide nanocrystals and nanostructured surfaces using a continuous flow microreactor system and their applications in two-phase boiling heat transfer

Metal oxide nanocrystals have attracted significant interests due to their unique chemical, physical, and electrical properties which depend on their size and structure. In this study, a continuous flow microreactor system was employed to synthesize metal oxide nanocrystals in aqueous solution. Assembly of nanocrystals is considered one of the most promising approaches to design nano-, microstructures, and complex mesoscopic architectures. A variety of strategies to induce nanocrystal assembly have been reported, including directed assembly methods that apply external forces to fabricate assembled structures. In this study ZnO nanocrystals were synthesized in an aqueous solution using a continuous flow microreactor. The growth mechanism and stability of ZnO nanocrystals were studied by varying the pH and flow conditions of the aqueous solution. It was found that convective fluid flow from Dean vortices in a winding microcapillary tube could be used for the assembly of ZnO nanocrystals. The ZnO nanocrystal assemblies formed three-dimensional mesoporous structures of different shapes including a tactoid, a retangle and a sphere. The assembly results from a competing interaction between electrostatic forces caused by surface charge of nanocrystals and collision of nanocrystals associated with Dean vortices. The as synthesized colloidal ZnO nanocrystals or assembly were directly deposited onto a substrate to fabricate ZnO nanostructured surfaces. The rectangular assembly led to flower-like ZnO nanostructured films, while the spherical assembly resulted in amorphous ZnO thin film and vertical ZnO nanowire (NW) arrays. In contrast to the formation of flower structure or amorphous thin film, only colloidal ZnO nanocrystals were used as the building blocks for forming vertical ZnO NW arrays. This study demonstrates the versatility of the microreactor-assisted nanomaterial synthesis and deposition process for the production of nanostrucuturesres with various morphologies by tuning the physical parameters while using the same chemical precursors for the synthesis. ZnO flower structure was coated on a microwick structure to improve the capillary flow. The coated microwick structure showed an enhanced capillary rise, which was attributed to the hydrophilic property and geometrical modification of ZnO nanostructure. Two-phase boiling heat transfer was performed using ZnO nanostructured surfaces. ZnO nanocoating altered the important characteristics including surface roughness and wettability. Hydrophilic nature of the ZnO nanocoating generally enhanced the boiling heat transfer performance, resulting in higher heat transfer coefficient (HTC), higher critical heat flux (CHF), and lower surface superheat comparing to the bare surface. Octahedral SnO and porous NiO films, fabricated by a continuous flow microreactor system, were suggested as potential boiling surfaces for the high porosity and irregularity of their structures

A MODEL ON AN ENTRAINED BED-BUBBLING BED PROCESS FOR CO2 CAPTURE FROM FLUE GAS

A simplified model has been developed to investigate effects of important operating parameters on performance of an entrained-bed absorber and bubbling-bed regenerator system collecting CO2 from flue gas. The particle population balance was considered together with chemical reaction to determine the extent of conversion in both absorber and regenerator. Effects of several absorber parameters was tested in a laboratory scale process. The CO2 capture efficiency decreased as temperature or gas velocity increased. However, it increased with static bed height or moisture concentration. The CO2 capture efficiency was exponentially proportional to each parameter. Based on the absolute value of exponent of the parameter, the effect of gas velocity, static bed height, and moisture content was a half, one third, and one fourth as strong as that of temperature, respectively

Optimal design of quadratic electromagnetic exciter

The vibration acceleration of collecting plates, which is the core indicator of rapping performance in an electrostatic precipitator’s vibration rapping process, is determined by magnetic force of a quadratic electromagnetic exciter. The larger exciter provides the larger magnetic force, but the installation space for the exciter is limited. Accordingly, this paper presents the optimal design of quadratic electromagnetic exciter to maximize the magnetic force with constraint that the size of exciter is constant. A design optimization problem was formulated in order to find the quadratic electromagnetic exciter shape parameters that maximized the magnetic force. The magnetic force of the quadratic electromagnetic exciter was evaluated using the commercial electromagnetic analysis software “MAXWELL”. For efficient design, we employed metamodel-based design optimization using design of experiments (DOE), metamodels, and an optimization algorithm equipped in PIAnO (Process Integration, Automation and Optimization), a commercial PIDO (Process Integration and Design Optimization) tool. Using the proposed design approach, the optimal magnetic force was increased by 1.68 % compared to the initial one. This result demonstrates the effectiveness of the established analysis and design procedure for the quadratic electromagnetic exciter

Δπ=0 reverse osmosis enriches a high osmotic pressure solution from a low-titre fermentation broth to a saturated solution or salt form using RO and NF membranes

Diverse biotechnology products are produced by microbial or eukaryotic cell fermentations in aqueous solutions. Removal of water is inevitable to enrich the product into a concentrated solution or into solid forms (such as crystals). The theoretical minimum energy required to remove 1 m3 of water is 716 kWh for thermal methods and 1 kWh for reverse osmosis (RO). In practice, the thermal methods equipped with heat energy recycling needs about 25 kWh to remove 1 m3 of water, and the RO methods needs about 4 kWh since extra energy (3 kWh) is required to operate pumps and other facilities in a plant. In general, membrane processes need less energy than thermal processes since there is no phase change in the separation processes and do not damage heat-sensitive biotechnology products. While both RO and NF membranes are permeable to water, RO membrane retains NaCl molecules and NF membrane is permeable to NaCl molecules, which is useful to remove inorganic salts from the products. Unlike thermal processes, the application of the membrane processes is limited by high osmotic pressure as the product solution is enriched by removing water. Chang et al. (2013) proposed a concept of osmotic pressure-free reverse osmosis (Δπ=0 RO) that overcomes this limitation and allows concentration of any solution with high osmotic pressure to its saturation point and further to crystal form. Δπ=0 RO, a two-component system, is distinct from 3-component forward osmosis and does not require the third component (draw component or extraction solvent) that must be separated from the aqueous solution at the end. This presentation will compare (1) ways of Δπ=0 RO technologies in desalination, and, furthermore (2) dewatering and desalination of high osmotic solutions of NaCl (343 bar), volatile fatty acids (400 – 600 bar), and fuel ethanol (6000 bar) with thermal separation methods in terms of energy consumption and potential of Δπ=0 RO technology. Chang et al. (2017), US patent 14,764,975(2015, 07,30), registration in progres

Ultraviolet photodepletion spectroscopy of dibenzo-18-crown-6-ether complexes with alkali metal cations

Ultraviolet photodepletion spectra of dibenzo-18-crown-6-ether complexes with alkali metal cations (M+-DB18C6, M = Cs, Rb, K, Na, and Li) were obtained in the gas phase using electrospray ionization quadrupole ion-trap reflectron time-of-flight mass spectrometry. The spectra exhibited a few distinct absorption bands in the wavenumber region of 35450−37800 cm^(−1). The lowest-energy band was tentatively assigned to be the origin of the S_0-S_1 transition, and the second band to a vibronic transition arising from the “benzene breathing” mode in conjunction with symmetric or asymmetric stretching vibration of the bonds between the metal cation and the oxygen atoms in DB18C6. The red shifts of the origin bands were observed in the spectra as the size of the metal cation in M^+-DB18C6 increased from Li^+ to Cs^+. We suggested that these red shifts arose mainly from the decrease in the binding energies of larger-sized metal cations to DB18C6 at the electronic ground state. These size effects of the metal cations on the geometric and electronic structures, and the binding properties of the complexes at the S_0 and S_1 states were further elucidated by theoretical calculations using density functional and time-dependent density functional theories

ΛΛ\Lambda\Lambda Interaction in a Nuclear Density Functional Theory and Hyperon Puzzle of the Neutron Star

A Skyrme-type effective potential is determined to describe the interaction between $\Lambda$ hyperons in nuclear medium. Experimental data of the binding energies of the double-$\Lambda$ ($\Lambda\Lambda$) nuclei with mass numbers $A=10$--$13$ are used to fit the parameters of the $\Lambda\Lambda$ interaction. As a result of the fitting, we obtain eight different sets of the $\Lambda\Lambda$ interaction parameters, which reproduces the input data within 5\% deviation from the experimental data on average. The eight $\Lambda\Lambda$ interactions are plugged in the calculation of the heavier $\Lambda\Lambda$ nuclei and the neutron star equation of state to explore the issue of hyperon puzzle. We found that the $\Lambda\Lambda$ interaction, specifically, p-wave interaction makes the equation of state stiff enough that the maximum mass of the neutron star can be as large as, or above $2\;M_\odot$

Scaling laws for the photo-ionisation cross section of two-electron atoms

The cross sections for single-electron photo-ionisation in two-electron atoms show fluctuations which decrease in amplitude when approaching the double-ionisation threshold. Based on semiclassical closed orbit theory, we show that the algebraic decay of the fluctuations can be characterised in terms of a threshold law $\sigma \propto |E|^{\mu}$ as $E \to 0_-$ with exponent $\mu$ obtained as a combination of stability exponents of the triple-collision singularity. It differs from Wannier's exponent dominating double ionisation processes. The details of the fluctuations are linked to a set of infinitely unstable classical orbits starting and ending in the non-regularisable triple collision. The findings are compared with quantum calculations for a model system, namely collinear helium.Comment: 4 pages, 1 figur