Uniform Energy Distribution Research Articles

Mathematical Modeling of Fluid Flow in Bath during Combined Side and Top Blowing AOD Refining Process of Stainless Steel: Application of the Model and Results

AbstractThe mathematical model developed for the molten steel flow in the combined side and top blowing AOD refining process of stainless steel has been used to compute and analyze the flow fields of the liquid phases in the baths of the 120 t AOD converter and its water model unit with a 1/4 linear scale. The influence of the side tuyere number and the angle between each tuyere on the flows has been examined. The results demonstrate that the mathematical model can quite reliably and well model and predict the fluid flow in an AOD bath with the combined blowing. The liquid flow in an AOD converter bath with the combined blowing is resulted from the gas side blowing streams under the influence of a gas top blowing jet. The streams play a governing role on it; and the liquid in the whole bath is in active agitation and circulatory motion during the gas blowing process. The gas jet from the top lance does not change the essential features of the gas stirring and liquid flow in the bath, but can make the local flow pattern of the bath liquid obviously vary and its turbulent kinetic energy enhance. The changes in the tuyere position and number have similarly not altered the basic characteristics and patterns of the gas agitation and liquid flow and turbulent kinetic energy distribution in the bath. At a given tuyere number and gas side blowing rate or a given angular separation between each tuyere and gas side blowing rate, however, the variation of the angle between each tuyere or the tuyere number can locally change them. Using 6 tuyeres with 27° can reach the more uniform flow field and turbulent energy distribution of the liquid in the bath than taking 7 tuyeres with 18° or 22.5° and 6 tuyeres with 22.5°.

On a wave-particle in closed and open isotropic universes

The Klein–Gordon equation satisfied by the wave function in general relativity is solved for the metric of the closed and open universe corresponding to Einstein–De Sitter–Friedmann isotropic cosmological model. The angular dependences are specified by spherical harmonics for the longitude and latitude, and for the hyperlatitude by modified spherical harmonics having as variable circular functions for the closed universe and hyperbolic functions for the open universes. The time dependence of the probabilistic wave function is similar for the closed and open universes and is obtained in the following three cases: (I) constant Hubble parameter, (II) constant decceleration parameter, and (III) uniform matter and energy distribution, which corresponds to the Hubble parameter a linear function of time. Thus six solutions are obtained, namely, the three cases I–III each for closed and open isotropic universes. For each of these six solutions is considered: (i) the existence of singularities in space–time including asymptotic time in the future or past, (ii) the square integrability of the wave function over the full extent of the four-dimensional space–time, and (iii) the existence or otherwise of a positive probability density associated with the wave function.

Practical issues for two-light-sources model of phosphor-based white light-emitting diode

We report an intuitive approach to simulating the performance of the phosphor-based light emitting diode (LED) by using the two-light-sources model for an optimized LED lens. The optimized secondary lens shape is achieved by approaching a uniform energy distribution on the detecting plane. Both the spectrum and spatial apodization of the LED structure are discussed, and the results indicate that the two-light-sources model can solve the misleading design on the phosphor-based LED due to imperfect color mixing of light source, that one can satisfy the highly uniformity requirement for specific applications, such as display backlight or optogenetic.

An Improvement of GAF for Lifetime Elongation in Wireless Sensor Networks

The introduction of Geographical Adaptive Fidelity (GAF) into field of Wireless sensor network (WSN) has help save sensor's energy to a large extent in some cases. Nevertheless, the traditional GAF still cannot reach the optimum energy usage since it select cluster heads completely randomly, not considering the best position of cluster head and energy distribution. In this paper, a novel topology control algorithm based on GAF is proposed: its main idea is to find the optimum position of the cluster head with a grid for energy saving, and divide the virtual grid dynamically and periodically, as well as take residual energy of each node into account, for uniform energy distribution. Compared to GAF, the proposed algorithm improves the networks' performance on the nodes' life time and average load for the network.

Gap discrete breathers in two-component three-dimensional and two-dimensional crystals with Morse interatomic potentials

The properties of gap discrete breathers in three-dimensional and two-dimensional crystals of the composition A3B with interatomic bonds described by the Morse potential have been investigated by the molecular dynamics method for different ratios between the masses of components mA/mB. The transition to a thermal equilibrium from a state far from equilibrium has been studied for the two-dimensional crystal. In this case, a short-wavelength phonon vibrational mode is excited in the crystal. This mode appears to be modulationally unstable for not too small amplitudes. During the transition to the state characterized by a uniform energy distribution between all vibrational modes of the crystal, the energy is localized in the form of gap discrete breathers, which exist in time intervals that exceed their oscillation period by several orders of magnitude.

Influence of ultrasonic frequency on the regeneration of silica gel by applying high-intensity ultrasound

Abstract Ultrasonic frequency is the key parameter considered in ultrasonic applications. In order to provide a basic knowledge about the influence of ultrasonic frequency on the regeneration of silica gel assisted by power ultrasound, the experiments about silica gel regeneration under the radiation of constant-power (60 W) ultrasound with different frequencies (i.e., 23, 27, and 38 kHz) and that without ultrasound were carried out at different regeneration temperatures (i.e., 35, 45, 55, and 65 °C). The experimental results showed that the lower frequency was beneficial for the application of power ultrasound in the regeneration of silica gel. The fact was theoretically explained by the ultrasonic power attenuation model which indicates that the ultrasound of lower frequency will lead to more uniform energy distribution and hence achieve higher efficiency of utilization. Meanwhile, the effect of ultrasonic frequency on silica gel regeneration would be influenced by the regeneration temperature and the moisture ratio in silica gel. As investigated in this study, the effect of ultrasonic frequency on the regeneration would be more significant at the lower regeneration temperature or at the higher moisture ratio in silica gel. In addition, the mean regeneration speed model of silica gel dependent of the regeneration temperature and the ultrasonic frequency was established according to the experimental data.

Optimum design of a multilayer beam partially treated with magnetorheologicalfluid

The modal damping characteristics of beams partially treated with magnetorheological(MR) fluid elements are studied using the modal strain energy approach and the finiteelement method. Different configurations of a sandwich beam partially treated with MRfluid are considered, including a beam with a cluster of MR fluid segments and abeam with arbitrarily located MR fluid segments. The significance of the locationof the MR fluid segments on the modal damping factor is investigated underdifferent end conditions. An optimization problem is formulated by combiningfinite element analysis with optimization algorithms based on sequential quadraticprogramming (SQP) and the genetic algorithm (GA) to identify optimal locationsfor MR fluid treatment to achieve maximum modal damping corresponding tothe first five modes of flexural vibration, individually and simultaneously. Thesolutions of the optimization problem revealed that the GA converges to theglobal solutions rapidly compared to the SQP method, which in some modalconfigurations usually entraps in the local optimum. The results suggest thatthe optimal location of the MR fluid treatment is strongly related to the endconditions and also the mode of vibration. Furthermore, partial treatments with MRfluid can significantly alter the deflection modes of the beam. It has also beendemonstrated that optimal locations of the MR fluid segments based on linearcombination of the modal damping factors of the first five modes are identicalto those obtained based on the first mode, irrespective of the end conditions.However, the optimal locations of the MR fluid segments, identified based on thelogarithmic summation of the modal damping factors of the first five modes, wouldyield a more uniform shear energy distribution compared to that attained byconsidering individual modes or a linear summation of the individual modes.

Uniform energy and density distribution: diblock copolymers’ functional

We study a nonlocal variational problem arising in diblock copolymers models, whose energy is given by the Cahn–Hilliard functional plus a long-range interaction term. We prove that minimizers develop uniform energy and density distributions, thus justifying partially the highly regular microphase separation observed in diblock copolymers’ melts. We also give a new proof of the scaling law for the minimum energy. This work extends the techniques introduced in [1] where analogous results are proved for the sharp interface limit of the functional considered.

Joint rate and cooperative MIMO scheme optimization for uniform energy distribution in Wireless Sensor Networks

An energy efficient adaptive rate cooperative MIMO selection scheme is proposed for uniform load distribution in the cluster based wireless sensor networks. The intrinsic data flow direction in multi-hop cluster based sensor networks causes uneven load distribution in the network. The transit clusters and the clusters near the base station carry more network traffic than the other clusters. Cooperative MIMO can artistically reduce the per bit energy consumption, Space–Time Block Codes are designed to achieve maximum diversity for a given number of transmit and receive antennas with very simple decoding algorithm. In radio fading channel, STBC require less transmission energy than SISO technique for the same Bit Error Rate and can be employed practically in Wireless Sensor Networks by using the cooperative MIMO scheme. Considering Alamouti and Tarokh Space–Time Block Codes, the number of antennas at both the transmission and the reception sides are selected with respect to the cluster load. The crude energy consumption per cluster then refined through adaptive rate transmission. It has been shown that the load based joint adaptive selection of rate and cooperative nodes in clusters renders uniform energy consumption in the network.

Speech Enhancement Based on Noise Eigenspace Projection

How to reduce noise with less speech distortion is a challenging issue for speech enhancement. We propose a novel approach for reducing noise with the cost of less speech distortion. A noise signal can generally be considered to consist of two components, a “white-like” component with a uniform energy distribution and a “color” component with a concentrated energy distribution in some frequency bands. An approach based on noise eigenspace projections is proposed to pack the color component into a subspace, named “noise subspace”. This subspace is then removed from the eigenspace to reduce the color component. For the white-like component, a conventional enhancement algorithm is adopted as a complementary processor. We tested our algorithm on a speech enhancement task using speech data from the Texas Instruments and Massachusetts Institute of Technology (TIMIT) dataset and noise data from NOISEX-92. The experimental results show that the proposed algorithm efficiently reduces noise with little speech distortion. Objective and subjective evaluations confirmed that the proposed algorithm outperformed conventional enhancement algorithms.

Uniform energy distribution for an isoperimetric problem with long-range interactions

We study minimizers of a nonlocal variational problem. The problem is a mathematical paradigm for the ubiquitous phenomenon of energy-driven pattern formation induced by competing short- and long-range interactions. The short-range interaction is attractive and comes from an interfacial energy, and the long-range interaction is repulsive and comes from a nonlocal energy contribution. In particular, the problem is the sharp interface version of a problem used to model microphase separation of diblock copolymers. A natural conjecture is that in all space dimensions, minimizers are essentially periodic on an intrinsic scale. However, proving any periodicity result turns out to be a formidable task in dimensions larger than one. In this paper, we address a weaker statement concerning the distribution of energy for minimizers. We prove in any space dimension that each component of the energy (interfacial and nonlocal) of any minimizer is uniformly distributed on cubes which are sufficiently large with respect to the intrinsic length scale. Moreover, we also prove an L ∞ L^\infty bound on the optimal potential associated with the long-range interactions. This bound allows for an interesting interpretation: Note that the average volume fraction of the optimal pattern in a subsystem of size R R fluctuates around the system average m m . The bound on the potential yields a rate of decay of these fluctuations as R R tends to + ∞ +\infty . This rate of decay is stronger than the one for a random checkerboard pattern. In this sense, the optimal pattern has less large-scale variations of the average volume fraction than a pattern with a finite correlation length.

A Method for Improving the Estimation of Natal Chemical Signatures in Otoliths

AbstractLaser ablation‐inductively coupled plasma mass spectrometry has been widely used in studies aimed at identifying the natal sites of fish through analysis of the otolith core region. It is critical, then, that measurements of chemistry at the core accurately represent the natal chemical environment, rather than reflecting potential physiological and ontogenetic influences on elemental incorporation during the embryonic and early larval phases. We analyzed sagittal otoliths from 840 age‐0 and age‐1 Australian smelt Retropinna semoni using a 193‐nm Ar‐F excimer laser system with a fast response two‐volume sample cell to demonstrate a rapid depth‐profiling method that enables more accurate estimations of the natal chemistry by sampling a target region of the otolith that excludes the primordium. The method involves (1) examination of validated daily growth increments to identify the target region; (2) measurement of the amount of otolith material removed by each laser pulse; and (3) use of elevated 55Mn concentrations at the primordium to provide a marker to facilitate data selection. The target region in this study was material accreted onto the otolith 2‐10 d posthatch. We sampled this region by excluding data between the maximum value of the Mn peak and the otolith material representing the first 2 d of life. The laser pulses in the acquisition sequence that represented the target were then retained and all other data excluded. This method illustrates the advantages of the uniform energy distribution produced by 193‐nm excimer laser systems for depth profile analysis of otoliths and may provide the basis for a standardized approach to sampling at the otolith core that more accurately reflects the natal chemical environment.

Cylindrical concentrator with Quasiparabolic directrix

A cylindrical concentrator directrix that provides uniform energy distribution over the back (in the direction of solar ray travel) side of the receiving surface that is normal to the solar radiation has been investigated. The values of the focal parameters of the parabolas forming the directrix are determined. The parametric equations of the curve along which the parabolic foci move are obtained. The configurations of the directrix branches are considered and evaluated.

Multiple directional beaming effect of metallic subwavelength slit surrounded by periodically corrugated grooves

It is demonstrated that multiple directional beaming effect can be realized by a metallic subwavelength slit surrounded by finite number of grooves based on mode expansion method. Each of the directional beaming is formed by superimposing two diffraction orders of spoof surface plasmon excited on the two corrugated sides of the slit. This delivers high contrast and considerably uniform energy distribution for the beaming directions.

Diffusion characteristics of particles on energetically disordered lattices

The barrier model with random distribution of barrier energies is considered at nonzero particle concentrations. The statistical mechanics expressions for the jump diffusion coefficient that takes into account interparticle interactions are derived for dynamic and static disorder. For the former case the analytical expression for the barrier energy contribution is calculated, while for the latter case the limiting low and high temperature contributions are obtained. The derived expressions are tested by Monte Carlo simulations for uniform and exponential barrier energy distributions for one- and square, triangular and honeycomb two-dimensional lattices.

Microfluidic-based synthesis of non-spherical magnetic hydrogel microparticles

Spherical and non-spherical magnetic hydrogel particles were synthesized in a microfluidic device containing an embedded UV light reflector. Monodisperse magnetic emulsion droplets were generated in a T-junction and allowed to relax into spheres, disks, and plugs in confining microchannel geometries. Particle morphology was locked-in via UV-initiated photopolymerization. The role of the reflector in the microchannel is to provide a uniform distribution of UV energy to the magnetic emulsion droplets and to increase the UV flux, which significantly improves UV polymerization conditions for microfluidic-based particle synthesis. Magnetic nanoparticles were uniformly encapsulated in the hydrogel, giving the microparticles superparamagnetic behavior. Additionally, the non-spherical particles show anisotropic responses under an applied external magnetic field.

Phonon coupling of non-bridging oxygen hole center with the silica environment: Temperature dependence of the 1.9 eV emission spectra

We report an experimental study on the shape of the 1.9 eV emission associated with non-bridging oxygen hole centers in silica and its temperature dependence, from 4 up to 300 K, under visible and ultraviolet excitation. Our analysis points out that these defects are coupled with their environment by phonons whose contribution can be described by the single mode of mean frequency between 300–400 cm −1 and Huang–Rhys factor of ∼3. On increasing the temperature, the luminescence intensity undergoes a thermal quenching caused by non-radiative processes, its deviation from a pure Arrhenius law can be accounted for by an uniform distribution of activation energy, from 0.002 to 0.05 eV. Meanwhile the emission band gets narrower, this contrasts with the broadening with temperature observed in other silica defects and suggests that the vibrational levels associated with the excited state are not thermally populated according to Boltzmann's law.

Investigation of a compound concentrator with a quasi-parabolic guide

A compound concentrator guide has been investigated that provides uniform energy distribution over the receiver. The values of the focal parameters of the parabolas that form the quasi-parabolic guide curve have been determined. The parametric equations of the curve along which the parabolas foci travel have been set up. Arrangement variants of the guide curve branches have been considered, and the compound concentrators have been assessed.

Two-site realization of the Davydov model in a finite size lattice: A time-convolutionless master equation approach

A two-site realization of the Davydov model is introduced to study the energy flow between two amide-I modes embedded in a finite size lattice of hydrogen-bounded peptide units. The non-Markovian nature of the energy transfer is addressed by using a time convolutionless master equation for the population difference of quanta between the two sites of the dimer. It is shown that both the lattice size and the dimer position discriminate between two dynamical regimes. For specific values of these parameters, the population difference shows damped oscillations. It decreases exponentially and rapidly vanishes, which indicates that the equilibrium corresponds to a uniform energy distribution over the two sites of the dimer. By contrast, for other specific values of the lattice size and dimer position, a slowdown of the decoherence takes place. The population difference does not decay exponentially but evolves by steps during which the damping of the oscillations is very small. In addition, the occurrence of revivals characterizing an amplification of the coherence over a finite time scale is observed. Nevertheless, both the decoherence slowdown and the revivals are limited by pure dephasing so that the population difference finally vanishes, but after a rather large coherent time.

Study of the Drain Leakage Current in Bottom-Gated Nanocrystalline Silicon Thin-Film Transistors by Conduction and Low-Frequency Noise Measurements

The drain leakage current in n-channel bottom-gated nanocrystalline silicon (nc-Si) thin-film transistors is investigated systematically by conduction and low-frequency noise measurements. The presented results indicate that the leakage current, controlled by the reverse biased drain junction, is due to Poole-Frenkel emission at low electric fields and band-to-band tunneling at large electric fields. The leakage current is correlated with single-energy traps and deep grain boundary trap levels with a uniform energy distribution in the band gap of the nc-Si. Analysis of the leakage current noise spectra indicates that the grain boundary trap density of 8.5 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> in the upper part of the nc-Si film is reduced to 2.1 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> in the lower part of the film, which is attributed to a contamination of the nc-Si bulk by oxygen