Amplitude death in a ring of nonidentical nonlinear oscillators with unidirectional coupling

We study the collective behaviors in a ring of coupled nonidentical nonlinear oscillators with unidirectional coupling, of which natural frequencies are distributed in a random way. We find the amplitude death phenomena in the case of unidirectional couplings and discuss the differences between the cases of bidirectional and unidirectional couplings. There are three main differences; there exists neither partial amplitude death nor local clustering behavior but oblique line structure which represents directional signal flow on the spatio-temporal patterns in the unidirectional coupling case. The unidirectional coupling has the advantage of easily obtaining global amplitude death in a ring of coupled oscillators with randomly distributed natural frequency. Finally, we explain the results using the eigenvalue analysis of Jacobian matrix at the origin and also discuss the transition of dynamical behavior coming from connection structure as coupling strength increases.Comment: 14 pages, 11 figure

REACTION CHARACTERISTICS OF TWO WATER GAS SHIFT CATALYSTS IN A BUBBLING FLUIDIZED BED REACTOR FOR SEWGS PROCESS

Reaction characteristics of two WGS catalysts for SEWGS process were investigated in a bubbling fluidized bed reactor. The commercial low temperature WGS catalyst produced by Süd-chemie and new catalyst produced by spray-drying method were used as bed materials. Reaction temperature, steam/CO ratio, and gas velocity were considered as experimental variables. Moreover, long-term operation results of two WGS catalysts were compared as well

NOVEL TWO-INTERCONNECTED FLUIDIZED BED SYSTEM FOR SELECTIVE SOLID CIRCULATION

A novel two-interconnected fluidized bed system was developed to separate fine and coarse particles by means of particle size difference. Coarse (212~300 μm) and fine (63~106 μm) particles were separated perfectly using the solid separator. The effects of the fluidizing velocity, solid injection velocity, diameter of solid injection nozzle, and solid height on the solid separation rate were investigated. Moreover, continuous solid separation and circulation test up to 20 hours was performed to check feasibility of stable operation

Modeling of an Interconnected Fluidized Bed Reactor for Chemical Looping Combustion

Chemical Looping Combustion (CLC) is comprised of two reactors, in which direct contact between air and fuel is avoided. A metal oxide, as oxygen carrier, transports oxygen from the air reactor to the fuel reactor while circulating between them. Based on the hydrodynamics coupled with reaction kinetics of oxygen carrier from the literature, a model for an interconnected fluidized bed reactor has been developed to optimize the design and operation of the reactor system. The model considers the chemical reaction of a single particle and a particle population balance for the calculation of bed particle conversion. The core-annulus and two-phase hydrodynamic models are assumed for the air and fuel reactors, respectively. Predictions of the oxygen emission, particle conversion and fuel conversion efficiency under different operating conditions are presented for a pilot scale CLC reactor system

Symmetry-protected flatband condition for Hamiltonians with local symmetry

We derive symmetry-based conditions for tight-binding Hamiltonians with flatbands to have compact localized eigenstates occupying a single unit cell. The conditions are based on unitary operators commuting with the Hamiltonian and associated with local symmetries that guarantee compact localized states and a flatband. We illustrate the conditions for compact localized states and flatbands with simple Hamiltonians with given symmetries. We also apply these results to general cases such as the Hamiltonian with long-range hoppings and higher-dimensional Hamiltonian.Comment: 7 pages, 2 figure

A 9-year-old Korean girl with Fontaine progeroid syndrome: a case report with further phenotypical delineation and description of clinical course during long-term follow-up

Background Gorlin–Chaudhry–Moss syndrome (GCMS) and Fontaine–Farriaux syndrome (FFS) are extremely rare genetic disorders that share similar clinical manifestations. Because a de novo missense mutation of the solute carrier family 25 member 24 (SLC25A24) gene was suggested to be the common genetic basis of both syndromes, it has been proposed recently that they be integrated into a single disorder under the name of Fontaine progeroid syndrome (FPS). Case presentation A 9-year-old Korean girl presented with typical clinical features of FPS. She had generalized loose skin with decreased subcutaneous fat, skin wrinkling on the forehead and limbs, skull deformities and a peculiar facial appearance with microphthalmia and midface hypoplasia, anomalies of the digits and nails, a large umbilical hernia and a nearly normal developmental outcome. She exhibited prenatal and postnatal growth retardation together with short stature, and records showed that her height and weight were invariably under − 2.0 SD from birth to the age of 10 years. SLC25A24 analysis revealed a heterozygous mutation reported previously, NM_013386:c.650G > A, p.[Arg217His]. After screening her family for the identified mutation, she was confirmed as being a de novo case of FPS caused by an SLC25A24 mutation. Conclusion We describe a Korean girl with typical clinical findings of FPS and a de novo mutation in SLC25A24, as well as 10 years of clinical follow-up, including growth and developmental achievements.This study was supported by grant no. 05–2018-0010 from the SNUH Research Fund. The funder had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript

GAS AND SOLID MIXING IN A THREE PARTITIONED FLUIDIZED BED

There are many gas-solid reaction systems which take place simultaneously in a single reactor, such as coal gasification. By splitting the reactions, high concentrated gases can be obtained without separation processes. Dual fluidized bed was proposed for this purpose. Similarly, simultaneous adsorption/desorption systems with dry sorbent for CO2 capture and the gasification reaction system with a char combustor and a gasifier separately were developed. For improving gas and solid mixing efficiencies of the dual fluidized beds, a hitherto unknown partitioned fluidized bed (PFB) is proposed. A basic concept of PFB is that lower parts between two separated fluidized beds are linked (opened), whereas upper parts are blocked by walls. Solid mixing occurs in lower parts with preventing gas mixing. The solid residence time becomes longer than that of dual fluidized bed and the high conversion of solid can be obtained. In this study, the gas and the solid mixing behaviors were investigated in three partitioned fluidized beds (left, center and right). The size of each fluidized bed is 7 cm (w) X 7 cm (d) X 30 cm (h) and partitioned above the 7 cm of distributor. Air and CO2-air mixture were used as fluidizing gas in each partitioned fluidized bed. For the gas mixing experiments, glass bead particles with 150 micron and density of 2.5g/cm3 were introduced. Outlet gas concentrations of each fluidized bed were analyzed by IR and then the gas exchanges between the reactors were calculated. For the solid mixing experiments, the polypropylene particles with 1000 micron and the density of 0.883 g/cm3 were continuously fed into the reactor. The gas mixing percentages were 0.4 ~ 16.0% of input gas amounts with varying gas velocities. The solid discharge rates in center and right side can be controlled by operating conditions

Li-Fi based on security cloud framework for future IT environment

This study was supported by the Research Program funded by the SeoulTech (Seoul National University of Science and Technology).Peer reviewedPublisher PD

A Study of Solids and Gas Mixing in a Partitioned Fluidized Bed

A partitioned fluidized bed gasifier has been developed for improving coal gasification performance. The basic concept is to divide a fluidized bed into two parts, a gasifier and a combustor, by a partition. Char is burnt in the combustor and generated heat is supplied to the gasifier by solid mixing. Therefore, solid mixing should be maximized whereas gas mixing between syngas and the combusted gas should be minimized. In this study, gas and solid mixing behaviors were verified in cold model acrylic beds. For monitoring solid mixing behavior, transient temperature trends in the beds were analyzed. A heat source and a heat sink were installed in each bed. Dozens of thermocouples were used to monitor temperature distribution