Phenomenon Of Splitting Research Articles

A novel approach for modeling bubbling gas-solid fluidized beds

A phenomenological discrete bubble model is proposed to help in the design and dynamic diagnosis of bubbling fluidized beds. An activation region mechanism is presented for bubble formation, making it possible to model large beds in a timely manner. The bubbles are modeled as spherical-cap discrete elements that rise through the emulsion phase that is considered as a continuum. The model accounts for the simultaneous interaction of neighboring bubbles by including the trailing effects due to the wake acceleration force. The coalescence process is not irreversible and therefore, the coalescing bubble pair is free to interact with other rising bubbles originating the splitting phenomena. To validate the model, the simulated dynamics are compared with both experimental and literature data. Time, frequency, and state space analysis are complementarily used with a multiresolution approach based on the empirical method of decomposition to explore the different dynamic scales appearing in both the simulated time series and those obtained from experimental runs. It is concluded that the bubble dynamics interactions play the main role as the driver of the resulting bed dynamics, matching the main features of measured bubble dynamics. Exploding bubble phenomena have been identified by establishing a direct relation between the bubble generation, interaction and eruption, and the measured signals. © 2010 American Institute of Chemical Engineers AIChE J, 2011

Shock-induced phase transition in systems of hard spheres with internal degrees of freedom

Shock waves and shock-induced phase transitions are theoretically and numerically studied on the basis of the system of Euler equations with caloric and thermal equations of state for a system of hard spheres with internal degrees of freedom. First, by choosing the unperturbed state (the state before the shock wave) in the liquid phase, the Rankine-Hugoniot conditions are studied and their solutions are classified on the basis of the phase of the perturbed state (the state after the shock wave), being a shock-induced phase transition possible under certain conditions. With this regard, the important role of the internal degrees of freedom is shown explicitly. Second, the admissibility (stability) of shock waves is studied by means of the results obtained by Liu in the theory of hyperbolic systems. It is shown that another type of instability of a shock wave can exist even though the perturbed state is thermodynamically stable. Numerical calculations have been performed in order to confirm the theoretical results in the case of admissible shocks and to obtain the actual evolution of the wave profiles in the case of inadmissible shocks (shock splitting phenomena).

Experimental analysis of bubble size distributions in 2D gas fluidized beds

The present work focuses on the development of a novel statistical approach for the analysis of the behavior of a 2D fluidized bed operating under bubbling and slugging conditions. Experimental data were collected by means of a purposely built lab-scale 2D fluidized bed and an original digital image analysis technique (DIAT), allowing the acquisition of a number of data sufficient to perform a statistical analysis of bubble dynamics. In particular, measurements of bubble size distributions (BSD) along the bed were performed. The analysis allowed to characterize the shape of BSD for different particle systems and fluidization gas velocities; interestingly a bimodal shape of BSD is observed, likely due to the simultaneous presence of coalescence and splitting phenomena. Linear combination of two Gamma distributions was used to describe the data. Also bubble size distributions weighed on bubble area were computed, and for all cases a characteristic negatively skewed distribution shape was found. Preliminary assessment of available data allowed to point out the effectiveness of the new approach proposed for a more in-depth description of bubble dynamics in 2D gas fluidized beds.

Spatiotemporal electromagnetic soliton and spatial ring formation in nonlinear metamaterials

We present a systematic investigation of ultrashort electromagnetic pulse propagation in metamaterials (MMs) with simultaneous cubic electric and magnetic nonlinearity. We predict that spatiotemporal electromagnetic solitons may exist in the positive-index region of a MM with focusing nonlinearity and anomalous group velocity dispersion (GVD), as well as in the negative-index region of the MM with defocusing nonlinearity and normal GVD. The experimental circumstances for generating and manipulating spatiotemporal electromagnetic solitons can be created by elaborating appropriate MMs. In addition, we find that, in the negative-index region of a MM, a spatial ring may be formed as the electromagnetic pulse propagates for focusing nonlinearity and anomalous GVD; while the phenomenon of temporal splitting of the electromagnetic pulse may appear for the same case except for the defocusing nonlinearity. Finally, we demonstrate that the nonlinear magnetization makes the sign of effective electric nonlinear effect switchable due to the combined action of electric and magnetic nonlinearity, exerting a significant influence on the propagation of electromagnetic pulses.

Neutrinos and flavour in a brane model

I describe how a domain-wall brane model based on S U ( 5 ) can explain fermion mass hierarchies using the intrinsically extra-dimensional phenomenon of fermion splitting.

Frequency splitting phenomenon of dual transverse modes in a Nd:YAG laser

We observed frequency splitting phenomenon of dual transverse modes (TEM 00q and TEM 01q) in a Nd:YAG microchip standing wave laser utilizing intracavity stress birefringence effects. Four resonance frequencies ( ν 00qe, ν 00qo, ν 01qe, and ν 01qo, respectively) were produced and tuned by changing the diametral compression force applied on the laser crystal. The transverse mode frequency spacing for the same longitudinal mode number (Δ ν trans) was 1.16 GHz, and the magnitude of frequency splitting (Δ ν) ranged from 0 MHz to 1.16 GHz. Based on this phenomenon, a four-mode differential standing wave laser, whose signal characteristics were a little like those of a four-mode differential travelling wave laser gyro however with a much larger frequency splitting range, was produced. The theoretical analysis is in good agreement with the experimental results. This phenomenon not only can be used to make lasers with two or more frequency differences, but also can be used to make high-resolution self-sensing laser sensors (e.g. laser force sensors and laser accelerometers).

Terapia della Gestalt, psicoanalisi moderna e infant research: considerazioni sul tema

- The author, a German psychotherapist, takes into account similarities between gestalt therapy, object relational theories and infant research. He explores in particular similarities between object relational theories and the therapeutical work of Fritz Perls. In this context the autor discusses concepts like "internal theatre", the therapist as an "additional" other and the contribution of gestalt therapy to the work with the phenomenon of splitting. Bocian then explores the possibles overlaps between the evolutionary models of gestaltpsychology and gestalt therapy with that one of theorists of the infant resarch - in particolar of Daniel Stern - that are realised in the acknowledgment of the social nature of the child and his interaction with the mother.Key words: contemporary psychoanalysis, object relational theories, "additional" other, "internal theatre", splitting, development, infant research.Parole chiave: psicoanalisi contemporanea, teorie delle relazioni oggettuali, altro supplementare, "teatro interno", scissione, sviluppo, /infant research/.

Dynamic behavior of splitting flames in a heated channel

Flame-propagation dynamics with dual peaks in a heated microchannel is predicted by employing a thermal-diffusive model taking into account two reactants. After auto-ignition, the flame immediately splits into two reaction fronts with different luminosities. One front propagates upstream, whereas the other moves downstream, and finally they both extinguish. After some delay, the process is repeated, and reignition of the fuel-air mixture is induced by hot walls. It is also shown that the commonly used infinitely thin reaction zone model, which has no reactant concentration dependence, is not capable of capturing this phenomenon. The splitting flame dynamics with dual fronts is confirmed by photographs taken with a high-speed digital video camera in experimental investigations with a propane-air mixture. The experiments reveal interesting details, namely, coexistence of triple reaction peaks during the process of propagation of splitting flames is observed, and the flame splitting phenomenon occurs twice in one extinction-ignition period.

Microfluidic Picoliter-Scale Translational Spontaneous Sample Introduction for High-Speed Capillary Electrophoresis

A novel microfluidic picoliter-scale sample introduction approach was developed by combining the spontaneous injection approach with a capillary electrophoresis (CE) system based on a short capillary and slotted-vial array. A droplet splitting phenomenon at the capillary inlet end during the spontaneous sample introduction process was observed for the first time. On the basis of this phenomenon, a translational spontaneous injection approach was established to reduce sample injection volumes to the sub-100 pL range. A versatile high-speed capillary electrophoresis (HSCE) system was built on the basis of this sample injection approach with separation performance comparable to or even better than those reported in microfluidic chip-based CE systems. The HSCE system was composed of a short fused-silica capillary and an automated sample introduction system with slotted sample and buffer reservoirs and a computer-programmed translational stage. The translational spontaneous sample injection was performed by linearly moving the stage, allowing the capillary inlet first to enter the sample solution and then removing it. A droplet was left at the tip end and spontaneously drawn into the capillary by surface tension effect to achieve sample injection. The stage was continuously moved to allow the capillary inlet to be immersed into the buffer solution, and CE separation was performed by applying a high voltage between the buffer and waste reservoirs. With the use of the novel system, high-speed and efficient capillary zone electrophoresis (CZE) separation of a mixture of five fluorescein isothiocyanate (FITC) labeled amino acids was achieved within 5.4 s in a short capillary with a separation length of 15 mm, reaching separation efficiencies up to 0.40 microm plate height. Outstanding peak height precisions ranging from 1.2% to 3.7% RSD were achieved in 51 consecutive separations. By extension of the separation length to 50 mm, both high-speed and high-resolution CZE separation of eight FITC-labeled amino acids could be obtained in less than 21 s with theoretical plates ranging from 163,000 to 251,000 (corresponding to 0.31-0.20 microm plate heights). The present HSCE system also allowed fast chiral separations of FITC-labeled amino acids under micellar electrokinetic chromatography (MEKC) mode within 6.5 s.

Compact dual-wavelength Nd:GdVO_4 laser working at 1063 and 1065 nm

We report a compact diode-laser pumped Nd:GdVO(4) laser with stable dual-wavelength output at 1063 nm and 1065 nm simultaneously. Two types of resonant cavity configurations were presented to support the stable dual-wavelength operation of the laser. Using a polarization beam splitter(PBS) included T-shaped cavity, we obtained a total power output over 5 W in two orthogonal polarized beam directions with 4 W in sigma polarization (1065.5 nm) and 1 W in pi polarization (1063.1 nm). By combining a half-wave-plate with the PBS in the laser cavity, a new configuration favoring one beam direction dual-wavelength output with same polarization direction was realized. A phenomenon of further line splitting was observed in both 1065 nm and 1063 nm.

Filtration Combustion of Methane in High-Porosity Micro-Fibrous Media

Filtration combustion of lean methane-air mixtures in inert, high-porosity micro-fibrous media was studied experimentally in quartz tubes with different diameters. First, an overall stability diagram was obtained. Between the upstream and downstream propagating regimes, a specific rigid standing wave regime was observed, whereas only one standing wave point existed in other ordinary porous media. A specific instability phenomenon of a combustion wave splitting into two or more parts during wave propagation downstream was also observed in smaller diameter tubes at high filtration velocities. In principle, the results of a conventional two-temperature 1D analytical model captured the main feature of the process obtained in the experiment, but failed to explain the process of flame anchoring to the porous carcass that was observed under variation of the mass flow rate. The possible causes of the failure of the conventional modeling approach were presented.

QUANTUM SIZE EFFECTS OF HYDROGEN IMPURITY AT OFF-CENTER DONOR ATOM IN SPHERICAL QUANTUM DOTS

We obtain the numerical solutions for a single electron energy level of a hydrogen impurity confined inside an off-center donor in a spherical quantum dot. The energy spectrum of single electron impurity for off-center donor atom subject to screened Coulomb's attractive potential barrier well is presented. Using B-spline finite element method, we generate a complete set of wavefunctions within the central unit cell, and through the perturbation theory, the whole energy spectrum of an impurity at low temperature can be explored. We find that the energy splitting and different related magnetic quantum number ml, i.e., (n, l, ml) varies with quantum dot size. This is due to the fact that quantum confinement effect lifts the degeneracy which comes from the Coulomb interaction. On the other hand, the phenomena of energy spectrum splitting under this model is an analogous case, considering that degeneracy of hydrogen energy levels in free space has been lifted by an external magnetic field (Zeeman effect).

Plasmons: Chemical Bonding Coupling Induced Surface Plasmon Resonance Splitting in Self-Assembled Gold Nanoparticles

Recently, the effect of π-bonding electrons conjugating to a gold surface has been predicated by first principles. In this paper, we observe surface plasmon resonance splitting due to the covalence and π-bonding electrons conjugated effect. When surfactantless Au NPs are linked on the glass substrate by sulfur, the SPR peak is split from one mode (638 nm) into two modes at 615 and 643 nm. The binding energy of 3s electrons for sulfur atoms has a huge red-shift in XPS peaks to confirm the π-bonding electrons conjugated effect. Furthermore, a proposed classical coupling dielectric function model, adding the gold−sulfur covalence bonding effect and conjugated π-bond electrons from sulfur to gold into the Drude model, is achieved to explain the mechanism of the SPR split phenomenon. In the extreme case, when the Au surface atoms are all covered by thiol sulfur atoms, or not covered at all by thiols, the SPR peak will not split. We found 3.28% of the Au atoms are bound by sulfur atoms and 92% of the conjugated electrons of the sulfur atoms transfer to Au electronic gas. The coverage rate of the sulfur atoms bonded to the surface of the Au atoms is about 25%, and this can cause the SPR splitting.

Critical sensitivity in hetero-modal interferometric sensor using spectral interrogation

This paper reports on the finding of a critical working point in the sensitivity of hetero-modal interferometric optical sensors using spectral interrogation. At this point the theoretical sensitivity approaches infinity and the practical sensitivity will depend only on the measurement accuracy and noise sources present. If the critical condition is attained at a point of minimal power transfer, a phenomenon of splitting or bifurcation of the minimum dip is expected as sensing occurs. The conditions for attainment of these critical effects are discussed.

Dense wavelength conversion and multicasting in a resonance-split silicon microring

We experimentally demonstrate all-optical wavelength conversions in a 10 μm radius resonance-split silicon microring resonator based on free carrier dispersion effect. The split resonance is caused by the mutual coupling between the two countertraveling modes inside the ring resonator. Dense wavelength conversions are performed at data rates from 500 Mbytes/s to 5 Gbytes/s and a dual-channel wavelength multicasting is realized at a data rate of 1.25 Gbytes/s. The resonance splitting phenomenon opens up opportunities to convert more closely spaced wavelengths, thus effectively increasing the system capacity.

In-plane free vibration of a single-crystal silicon ring

In this paper the natural frequencies and the associated mode shapes of in-plane free vibration of a single-crystal silicon ring are analyzed. It is found that the Si(1 1 1) ring is two-dimensionally isotropic in the (1 1 1) plane for elastic constants but three-dimensionally anisotropic, while the Si(1 0 0) ring is fully anisotropic. Hamilton’s principle is used to derive the equations of vibration, which is a set of partial differential equations with coefficients being periodic in polar variable. Expressing the radial and tangential displacements in sinusoidal form with non-predetermined amplitudes, and through the integration with respect to the circumferential variable, the original governing equations in partial differential form can be converted into the amplitude equations in ordinary differential form. The exact expressions for frequencies and mode shapes are obtained. It is found that for Si(1 0 0) rings the frequencies of a pair of modes, which are equal for an isotropic ring, split due to the anisotropic effect only for the second in-plane vibration mode. The phenomena of frequency splitting and degenerate modes can be proved either based on the conservation of averaged mechanical energy or by the concept of crystallographic symmetry groups. When the single-crystal silicon is replaced by the polycrystalline silicon, which is isotropic in elastic constants, the derived equations for frequencies correctly predict the vanishing of the phenomenon of frequency splitting.

Chromatographic behavior of zwitterionic enalapril—Exploring the conditions for lipophilicity assessment

The chromatographic behavior of enalapril was investigated under different stationary and mobile phase conditions in an effort to unravel interferences in the underlying retention mechanism, which would affect its relation to octanol–water partitioning. Extrapolated retention factors, log k w, were used as relevant chromatographic indices. The retention/pH profile was established and the peak split phenomenon, associated with cis/ trans interconversion, was also monitored as a function of pH. The pH at maximum retention and minimum peak split occurrence was chosen for further investigation, so that the presence of zwitterionic structure was guaranteed and any effect of cis/ trans interconversion could be ignored. Retention of zwitterionic enalapril was found to be very sensitive to mobile phase conditions in regard to organic modifier as well to the aqueous component. The use of morpholine-propanesulfonic acid (MOPS) as buffer and the presence of n-octanol as mobile phase additive proved critical factors for maximum suppression of secondary interactions. Nevertheless, the corresponding extrapolated retention factor was considerably larger than octanol–water log D value at the isoelectric point. However, log k w could be successfully converted to log D by means of a calibration equation established for ionized acidic compounds.

Semi-active Damage Identification for a Composite Structural Missile Component using Minimal Passive Sensing with Data-driven Models

Cost, complexity, and weight restrictions often constrain industrial structural health monitoring (SHM) systems to the use of one sensor. Often, this one sensor is passive, i.e., it only measures the structural response. Therefore, new SHM techniques that utilize only one passive sensor along with advanced data interrogation methods are needed. A semi-active damage detection technique is described in this study that utilizes passively estimated forces and response measurements to update data-driven frequency-response-function (FRF) models of a filament-wound missile casing that is used as a test structure. During a damaging impact, the structural response is influenced by both the healthy and damaged structure properties. As a result, the magnitudes of the estimated FRFs can exhibit a splitting phenomenon at the natural frequencies of the healthy and damaged structure, and this phenomenon is evident in the experimental data. The updated FRFs are used with an active damage detection technique to quantify the damage. The normalized differences in the damaged and healthy FRFs and the shift of the natural frequencies of the structure quantify damage in this study. The shift of the natural frequencies more accurately quantifies the damage caused by four experimental impacts than the normalized differences in the FRFs.

Alterations in RFamide-Related Peptide Expression Are Coordinated with the Preovulatory Luteinizing Hormone Surge

The preovulatory LH surge is triggered when the circadian pacemaker, the bilateral suprachiasmatic nucleus (SCN), stimulates the GnRH system in the presence of high estrogen concentrations (positive feedback). Importantly, during the remainder of the estrous cycle, estradiol inhibits LH release via negative feedback. We have recently documented the presence of a novel mammalian RFamide-related peptide (RFRP), a putative gonadotropin-inhibitory hormone (GnIH), that presumably acts upstream of GnRH to modulate the negative feedback effects of estrogen. The present series of studies used female Syrian hamsters to examine the possibility that, in addition to driving the LH surge positively, the SCN concomitantly coordinates the removal of steroid-mediated RFRP inhibition of the gonadotropic axis to permit the surge. We found that the SCN forms close appositions with RFRP cells, suggesting the possibility for direct temporal control of RFRP activity. During the time of the LH surge, immediate-early gene expression is reduced in RFRP cells, and this temporal regulation is estrogen dependent. To determine whether projections from the SCN regulate the timed reduction in activation of the RFRP system, we exploited the phenomenon of splitting. In split animals in which the SCN are active in antiphase, activation of the RFRP system is asymmetrical. Importantly, this asymmetry is opposite to the state of the GnRH system. Together, these findings point to novel circadian control of the RFRP system and potential participation in the circuitry controlling ovulatory function.

Phase Behavior of the Mixtures of CO2+ Poly(methyl methacrylate) + Ethanol at High Pressure

Phase equilibria of carbon dioxide (CO2) + poly(methyl methacrylate) (PMMA-15 k, PMMA-120 k) + ethanol ternary systems were measured at temperatures ranging from (293.3 to 359.7) K and pressures up to 14.1 MPa. Furthermore, cloud point temperatures of PMMA + ethanol binary systems were determined at pressures up to 15 MPa. To determine the phase boundary, we observed the cloud points and bubble points by using a variable volume view cell. With the addition of CO2 into the binary PMMA + ethanol mixture, the upper critical solution temperature (UCST) line shifts toward higher pressure and temperature values. At high CO2 concentrations, the lower critical solution temperature (LCST) and UCST curves merge. Further, the liquid–liquid split phenomenon is observed over the entire temperature range.