Maximum Transfer Efficiency Research Articles

Modeling ozonation pretreatment parameters of distillery wastewater for improved biodegradability

In this study, ozonation pretreatment of real distillery wastewater (DWW) for biodegradability enhancement was undertaken. Response surface methodology was used to model the value of effective parameters, including ozonation duration and initial chemical oxygen demand (COD) concentration, and to estimate linear interactions and quadratic effects. The analysis of variance confirmed the adequate description of all the responses by the quadratic model employed. During ozonation, the pH of the DWW increased in acidity from 4.53 to 4.05, indicating the formation of acidic intermediates. A 60% reduction in color was observed signifying the oxidation of the color causing biorecalcitrant aromatic compounds and confirmed by the reduction in ultraviolet absorbance at λmax of 254 nm. Moreover, an increase in change in oxidation state from −0.1 to 0.4 was attributed to the declined aromaticity and the formation of aliphatic structures. From the measurement of the ratio of biochemical: chemical oxygen demand (BOD5:COD), an increase from 0.48 to 0.72 confirmed improved biodegradability. Optimization studies aimed at achieving maximum improved biodegradability at maximum ozone transfer efficiency yielded optimum ozonation pretreatment parameters of initial COD of 4.1 g L−1 and duration of 64 min.

All-utensil domestic induction heating system

This paper proposes and implements an all-utensil domestic induction heating system, which can effectively heat utensils made by ferromagnetic conductive (FC), non-ferromagnetic conductive (NFC) and non-ferromagnetic non-conductive (NFNC) materials. The proposed system consists of a controller, a full-bridge inverter and a new sandwiched-coil structure with the primary coil located at the lower part, ferrite bars in the middle part and resonant coil in the upper part of the heater, respectively. Besides, a fixed capacitor is connected with the primary coil and a switched-capacitor array is connected with the resonant coil to ensure that the magnetic resonant coupling (MRC) can be achieved when adopting different utensils. The proposed system not only releases the current stress of the inverter but also significantly strengthens the magnetic coupling effect to boost the heating performance under a resonant frequency of 30 kHz. In the meantime, the burst firing control (BFC) is utilized to flexibly regulate the output power while retaining the maximum transfer efficiency. For exemplification, a 500 W prototype has been built for heating FC (iron), NFC (aluminum) and NFNC (ceramic) utensils with the average temperatures of 83.8, 73.1 and 76.5 °C, output powers of 484.4, 411.4 and 426.16 W, and transfer efficiencies of 96.9, 82.3 and 85.2% respectively. Both finite element analysis and experimentation are given to verify the validity of the proposed system.

Luminescence properties and energy transfers of NaLa(WO4)2:Sm3+:Ce3+ phosphor

A series of NaLa(WO4)2:Sm3+:Ce3+ phosphors are prepared by the hydrothermal method. The structure, morphology, luminescent properties of sample are characterized with X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, and fluorescence spectrophotometer. The results show that all the obtained products have the scheelite structure with ellipsoidal shapes. Ce3+ has quenching effects on luminescence properties of NaLa(WO4)2:Sm3+ phosphors at high Ce3+ doping concentration. When the Ce3+ molar content is 1%, the intensity of the excitation and emission spectra is the maximum. It indicates that when the sensitizer Ce3+ has the molar content of 1%, the sensitizing ability of luminescent properties of NaLa(WO4)2:Sm3+:Ce3+ phosphors is the strongest. That is, Ce3+ can transfer energy to Sm3+. The critical distance of Ce3+ → Sm3+ energy transfer is 2.196 nm. The type of energy transfer of Ce3+ → Sm3+ is electric multi-pole interaction. The maximum energy transfer efficiency of Ce3+ → Sm3+ in NaLa(WO4)2:Sm3+:Ce3+ phosphors can reach 15.17%. The temperature-dependent emission spectra demonstrates that the NaLa(WO4)2: 0.02Sm3+:0.01Ce3+ phosphor has a good thermal stability with a thermal activation energy ΔE of 0.2789 eV. The CIE coordinates show that the phosphor is red, and is the potential red phosphor for LEDs.

Tunable blue-green color emitting Al5O6N: Eu2+, Tb3+ phosphors with energy transfer for near-UV white LEDs

A series of tunable blue-green emitting phosphors Al5O6N: Eu2+, Tb3+ were prepared via gas-pressure sintering reaction process. The morphology, UV–Vis reflectance spectra, photoluminescence properties, decay behavior, Eu2+ occupy site, energy transfer mechanism and thermal stability were investigated systematically. The Al5O6N: 0.003Eu2+, 0.01Tb3+ phosphor exhibits strong green emission under near-UV excitation due to briskly efficient energy transfer from Eu2+ to Tb3+. The maximum energy transfer efficiency calculated by decay lifetime can reach 80%. The mechanism of energy transfer from the Eu2+ to Tb3+ is considered to be a dipole−dipole type. The critical distance of the energy transfer is calculated via the concentration quenching method. Moreover, the color emission from blue to green can be obtained through controlling the concentration of Eu2+ and Tb3+. These results reveal the potential value of Al5O6N: Eu2+, Tb3+ phosphors as green light emitting material for near-UV pumped white light-emitting diodes.

An Inverter Topology for Wireless Power Transfer System with Multiple Transmitter Coils

This paper presents an inverter topology for a wireless power transfer (WPT) system that is intended to reduce the component counts and complexity of the conventional excitation circuit for multiple transmitter coils. The proposed inverter topology requires only (n+2) power switches, where “n” is the number of transmitter coils. An excitation of a proper transmitter coil pattern with regard to the receiver coil position is determined. The output voltage can be regulated through the primary-side control by adjusting the duty cycles of the inverter switches. A detection method of the receiver coil position is presented using the detection switches on the secondary side. The detection algorithm is based on the reflected impedance knowledge and requires only a current sensor on the primary side. A proper transmitter coil pattern is energized to ensure maximum transfer efficiency throughout the operation. The proposed system is experimentally validated on the created 500-watt WPT multi-coil system. After the receiver coil is placed in a designated area, the proper transmitter coil pattern can be automatically selected and energized. The output voltage can be regulated to a desired value under the typical operation conditions, including load change.

Enhanced luminescence at 2.88 and 2.04 μm from Ho3+/Yb3+ codoped low phonon energy TeO2–TiO2–La2O3 glass

The high phonon energy and short infrared cut-off wavelength of conventional oxide glass (or crystal) hosts are the limitations to achieve mid-infrared (MIR, λ≥2.5μm) luminescence. In present study, the luminescence performance of low phonon and non-conventional TeO2-TiO2-La2O3-based glass (TTL) host doped with Ho3+ and Ho3+/Yb3+ has been investigated, for visible to MIR range. The MIR emission band with peak at 2.88μm (Ho3+:5I6→5I7) and NIR band at 2.04μm (Ho3+:5I7→5I8) has been realized from Ho3+ singly doped TTL glass due to low phonon energy and extended transmission window of the host. Intensity of MIR and NIR emission bands have enhanced significantly in Ho3+/Yb3+: TTL glass under Yb3+ excitation, signifying an efficient Yb3+→Ho3+ energy transfer. The Judd-Ofelt analysis, on Ho3+ absorption characteristics reveals relatively better radiative transition probability (34.4s−1) and branching ratio (10.5%), which is associated to Ho3+:5I6→5I7 transition. The effective bandwidth of 2.88μm emission band is 180nm, with stimulated emission cross-section is 4.26×10-21cm2 and its gain bandwidth has been evaluated as 7.67×10-26cm3. For 2.04μm (Ho3+:5I7→5I8) emission band, the effective bandwidth of 160.5nm and gain bandwidth of 7.26×10-26cm3 have been accomplished. The non-resonant Förster-Dexter method has been applied to Ho3+/Yb3+: TTL glass on emission (donor, Yb3+) and absorption (acceptor, Ho3+) cross sections. The evaluated donor-donor (CDD) and donor-acceptor (CDA) energy transfer micro-parameters are 1.02×10-38 and 5.88×10-41cm6/s respectively while, maximum energy transfer efficiency has been 80%. In concise, Ho3+/Yb3+ codoped TeO2–TiO2–La2O3 glass host has revealed its potential for MIR to NIR photonic applications.

Design and Optimization of Internal Longitudinal Fins of a Tube Using Constructal Theory

This research is devoted to geometrical optimization of internal longitudinal fins based on constructal theory. These fins are extended inward from the pipe perimeter to a prescribed radius and would have an optimal length, determined analytically by means of constructal theory. The effective parameters of the current study are the ratio of high conductivity to low conductivity, volume fraction of the fins, and the number of the fins. For a round tube with two thermal boundary conditions, i.e., constant heat flux and constant temperature, the optimization length and also the corresponding thickness of fins for a known material ratio are determined parametrically ensuring maximum heat transfer and thermal efficiency In addition, dominancy of conduction heat transfer between fins and convection in the core of pipe are the main assumptions of this research. Finally, our analytical results are verified with their corresponding numerical counterparts.

MIMO WPT 시스템의 최대 효율을 위한 최적화 방법

In this paper, we proposed a method to control input powers and receiver loads for maximum efficiency in multiple-input multiple-output(MIMO) wireless power transfer(WPT) systems. The input voltage ratio between transmitters and receiver loads for maximum transfer efficiency is derived in terms of figure of merits. The theoretically derived input voltages for the transmitters and optimum loads for the receivers were found to be similar to those obtained by a genetic algorithm. We demonstrate the effectiveness of the theory using a few design examples. Using the results obtained from this study, effective and simplified designs of MIMO WPT systems will be possible.

Implementing series of dual-chamber units for sequential loading of the liquids in centrifugal microfluidic platforms

Liquids flow control plays a critical role in the designing of microfluidic networks for utilizing in the lab-on-a-chip devices as a modern platform for miniaturizing and automating medical diagnostic tests. In some applications such as immunoassay, it is essential to use different samples and reagent liquids in a series of sequential steps based on the test procedures. Thus far, a number of studies have reported associated methods mostly employing a different kind of the micro-valves. We introduce the concept of a dual-chamber, a passive method for the sequential entrance of any kind of liquids into a chamber in centrifugal microfluidics. The mechanism relies on the ability of the liquid pumping by employing its rotational potential energy through an abrupt angular deceleration of the containing disk. The model is analyzed theoretically, numerically and experimentally for optimizing the geometrical design to reach to the maximum liquid transfer efficiency. Furthermore, a model comprising of several dual-chamber units is presented and experimented based on the optimized designs. The results show that the presented method has a high ability of precise and efficient liquid transfer in the centrifugal microfluidic platforms through a simple and highly integrated approach.

A Novel Approach to Reach Impedance Matching in Wireless Power Transfer Systems

Wireless power transfer (WPT) using magnetic resonant coupling technology, came into focus promptly by virtue of its long transfer distance, and its non-radiative and high-efficiency power transfer. The impedance matching has been studied in the literature in recent years. However, there is no suitable way to reach the optimum load in reality. In this paper, a new method is proposed to maximize the power transfer ability of a given pair of coupled coils. An analytical calculation of the mutual inductance is presented accurately with respect to the angled concentric multiple-turn printed spiral coils (PSC). In addition, the experimental results were in good agreement with the circuit simulation. Finally, a WPT experiment setup working at 3MHz resonance was established. The experiment results verified that the maximum transfer efficiency at fixed distances can be easily achieved by adjusting the angle to reach impedance matching. Compared to prior to optimization, the maximum improved efficiency was improved by 11%.

Topology optimization via sequential integer programming and Canonical relaxation algorithm

The mathematical essence of structural topology optimization is large-scale nonlinear integer programming. To overcome its huge computational burden, a popular way is to relax the 0–1 variable constraints and transform the integer programming problem into a continuous variable programming problem which can be solved by using gradient based mathematical programming methods. To cope with the variable transformation, the well-known SIMP (Solid Isotropic Material with Penalty) method introduces interpolation schemes for the material properties versus design variables with penalty and achieves great success and popularity. However, there is no doubt that directly tackling the large-scale nonlinear integer programming is very important. This paper solves the structural topology optimization problems with single or multiple constraints by applying the Canonical Dual Theory (CDT) by Gao and Ruan (2010) together with Sequential Approximate Programming approach under the classic structural topology optimization formulations.Following the Sequential Approximate Programming (SAP) frame from the structural optimization, the present paper firstly utilizes sensitivity information to construct the explicit and separable approximate Sequential Quadratic Integer Programming (SQIP) or Sequential Linear Integer Programming (SLIP) subproblems for the topology optimization. And then, the subproblems are solved by applying the Canonical relaxation algorithm based on CDT theory. Their special mathematical structures are exploited to develop analytic solution of Kuhn–Tucker condition of the dual programming. Numerical experiments of two linear and quadratic integer programming problems with random coefficients assert that the Canonical relaxation algorithm can obtain approximate solutions with good properties very efficiently and the dual gap is negligible when the number of design variables increases.Because move limit strategies play a key role in many search algorithms of structural optimization, this paper combines one of two different move limit strategies within the new method. The new method first solves a set of classic topology optimization problems with only material usage constraint, including minimum structural compliance design under constant load, maximum heat transfer efficiency for the heat conduction problem. And then we apply the method to the topology optimization problems with multiple constraints, including minimum structural compliance design under an additional local displacement constraint and minimum structural compliance design under infill constraints. The results of these problems demonstrate that the new method can efficiently solve the discrete variable structural topology optimization problems with multiple nonlinear constraints or many local linear constraints in a unified and systematic way. Beyond that, the new method can achieve integer solutions when combined with the move limit strategy of controlling volume fraction parameter. It can deal with much more design variables than the general branch-and-bound method and makes no use of any sensitivity threshold or heuristic stabilization scheme during the iterative process in comparison with BESO method. Finally, the new method in this paper can be further developed as a general solver for these large-scale discrete variable structural topology optimization problems.

Polarization dependence of two-photon excitation of cold 7Li Rydberg atoms

The two-photon excitation of cold 7Li atoms at the 2S–120S transition is studied with variable polarization of one of the two counter-propagating optical beams. The maximum efficiency of the two-photon transfer of atoms from the ground state 2S to the Rydberg state 120S can be reached when the circular polarizations of the beams are orthogonal. In this case the selection rules ΔL = 0 are satisfied. By using a rotating quarter-wave plate it is possible to vary the polarization of the selected optical beam and change the amplitude of the two-photon resonance. The recorded dependence of the two-photon resonance on the beam polarization is discussed. The obtained results can be used to compensate the unwanted variations of the beam polarization after reflections from mirrors.

Measurements of inertial wave packets propagating within steady rotating turbulence

We measure and quantify the spatial transport of energy within steady rotating hydrodynamic turbulence. A steady turbulent field in a rotating tank is perturbed by a short and abrupt increase of energy injection at a well-defined plane. Initially, a wave packet of inertial modes is generated within the background turbulent field, propagating according to the dispersion relation of inertial waves, much like wave propagation within a static fluid. At this stage, the background turbulence is only weakly affected by the pulse passage. Only at longer times, which are determined by the pulse initial amplitude and spectrum, energy is efficiently transferred from the wave packet to the background flow. The energy, which is physically injected at the bottom of the tank, is, therefore, effectively injected at a higher plane. The height of maximum energy transfer efficiency is estimated and varied via manipulations of experimental parameters.

Конфигурационный резонанс и скорость генерации поверхностных плазмон-поляритонов возбужденными полупроводниковыми квантовыми точками вблизи металлической поверхности-=SUP=-*-=/SUP=-

AbstractWe discuss particular features of generation of surface plasmon polaritons in a metal–dielectric planar interface that is coupled to semiconductor quantum dots by near-field interactions. As a model of working medium for performing numerical experiment, we use a gold metal surface onto which a polyethylene terephthalate film containing CdSe semiconductor spherical quantum dot is deposited. The problem of optimizing the radius of a quantum dot and its distance to a metal surface is solved for achieving the maximum transfer efficiency of the quantum dot energy for the generation of surface plasmon polaritons. Dispersion effects of the surface wave generation rate associated with deviations of the radius of quantum dots and their distance to the metal surface from the corresponding average values are taken into account.

Configuration Resonance and Generation Rate of Surface Plasmon Polaritons Excited by Semiconductor Quantum Dots near a Metal Surface

We discuss particular features of generation of surface plasmon polaritons in a metal–dielectric planar interface that is coupled to semiconductor quantum dots by near-field interactions. As a model of working medium for performing numerical experiment, we use a gold metal surface onto which a polyethylene terephthalate film containing CdSe semiconductor spherical quantum dot is deposited. The problem of optimizing the radius of a quantum dot and its distance to a metal surface is solved for achieving the maximum transfer efficiency of the quantum dot energy for the generation of surface plasmon polaritons. Dispersion effects of the surface wave generation rate associated with deviations of the radius of quantum dots and their distance to the metal surface from the corresponding average values are taken into account.

Immobilization of gold nanoparticles with rhodamine to enhance the fluorescence resonance energy transfer between quantum dots and rhodamine; new method for downstream sensing of infectious bursal disease virus.

Infectious bursal disease virus is a causative agent of one of the most important disease which causes frequent tragic disaster in the poultry industry all over the world. Therefore, in the present study a new fluorescence resonance energy transfer-based technique was developed to detect VP2 gene of infectious bursal disease virus using two oligonucleotide probes labeled with quantum dots and rhodamine- immobilized gold nanoparticles (AuNPs-Rh). Quantum dots labeled with an amino-modified first oligonucleotide, and AuNPs-Rh labeled with thiol-modified second oligonucleotides were added to the DNA targets upon which hybridization occurred. In the presence of target the AuNPs-Rh will be located in the vicinity of the quantum dots and leads to the fluorescence resonance energy transfer to be occurred and subsequently the fluorescence intensity of quantum dots was stimulated. The immobilization of rhodamine to the surface of AuNPs increased the fluorescence intensity of rhodamine. The maximum fluorescence resonance energy transfer efficiency for the developed sensor is monitored at a quantum dots-PA/AuNPs-Rh-PT molar ratio of 1:10. Moreover, the feasibility of the developed nanobiosensor was demonstrated by the detection of a synthetic 49-mer nucleotide derived from infectious bursal disease virus and the limit of detection was estimated as 3 × 10-8 M. The developed DNA detection scheme is a simple, rapid and efficient technique which does not need excessive washing and separation steps.

Luminescent properties, energy transfer, and thermal stability of double perovskites La2MgTiO6:Sm3+, Eu3+

La2MgTiO6 red phosphors doped with both Sm3+ and Eu3+ were prepared by high temperature solid state method. Their phase compositions, morphologies, fluorescence spectra, fluorescence lifetimes and thermal stability were analyzed by X-ray diffraction, scanning electron microscopy, and fluorescence spectroscopy. The optimal synthetic temperature of La2MgTiO6:Sm3+, Eu3+ phosphors was 1400 °C. La2MgTiO6:Eu3+ showed red emission at 615 nm under 396 nm excitation, while La2MgTiO6:Sm3+ showed red orange emission at 601 nm under 406 nm excitation. La2MgTiO6: Sm3+, Eu3+ phosphor showed strong red emission at 615 nm under the excitation of 406 nm. The energy transfer from Sm3+ to Eu3+ in La2MgTiO6: Sm3+, Eu3+ was very effective. The maximum energy transfer efficiency was about 73.5% when Eu3+ concentration was 0.2. The temperature dependent emission spectra showed that the phosphors had good thermal stability. The La1.94MgTiO6:0.06Sm3+, La1.85MgTiO6:0.15Eu3+ and La1.79MgTiO6:0.06Sm3+, 0.15Eu3+ phosphors exhibited color purities close to 100%: 96.26%, 98.05% and 98.95%.

Structure, luminescence properties and energy transfer of Dy3+ and Eu3+ codoped KBa(VO4) phosphor

Novel single-phased white-light-emitting and color tunable KBa(VO4):Dy3+, Eu3+ phosphors were synthesized by solid-state reaction method. The crystal structures, luminescence properties, lifetime, and energy transfer mechanism were investigated in detail. A series of characteristic emissions of Dy3+ and Eu3+ were observed in the emission spectra at around 486 nm, 578 nm, 663 nm and 617 nm when excited at 349 nm. With the increase of Eu3+ concentration, the emission intensity and the decay lifetime of Dy3+ decreased, which proved the existence of the energy transfer from Dy3+ to Eu3+ in the KBa(VO4) host. It was found that energy was transferred from 4F9/2 level of Dy3+ to the 5D0 level of Eu3+ by dipole-dipole interaction and the critical distance between Dy3+ and Eu3+ was 12.82 Å. In the case of Dy3+ and Eu3+ codoped phosphors, the color coordinates are very sensitive to the incorporation of Eu3+ ions and the correlated color temperature is improved with the introduction of Eu3+ ions. With 10 mol% Eu3+ phosphor can obtained maximum energy transfer efficiency of 83%. The experimental research shows that KBa(VO4): xDy3+, yEu3+ phosphors are promising materials for white UV LEDs.

Comparison between glass and glass-ceramic silica-hafnia matrices on the down-conversion efficiency of Tb3+/Yb3+ rare earth ions

In this paper, the investigation of energy transfer efficiency in Tb3+-Yb3+ co-doped SiO2-HfO2 glass and glass-ceramic waveguides is presented. Cooperative energy transfer between these two ions allows to cut one UV or 488 nm photon in two 980 nm photons and could have important applications in improving the performance of photovoltaic solar cells. Thin films with different molar concentrations of rare earths, up to a total concentration of 21%, were prepared by a sol-gel route, using dip-coating deposition technique on SiO2 substrates. The ratio between Yb3+ and Tb3+ ions in all the prepared thin films is constant and equal to 4. The energy transfer between Tb3+ and Yb3+ ions in glass and glass-ceramic waveguides shows the higher efficiency for glass-ceramic with a maximum quantum transfer efficiency of about 190% for the sample containing 19% of rare earths.

Study on oxygen transfer by solid jet aerator with multiple openings

In the current study, two different sets of solid jet aerators having area of openings equal to 594.96 mm2 and 246.30 mm2 with rectangular nozzles having rounded ends were studied. Each set consisted of aerators having one, two, four and eight openings. The oxygenation performance of every model was studied for five different discharges of 1.11 l/s, 2.10 l/s, 2.96 l/s, 3.83 l/s and 4.69 l/s. At low discharges, the aerator having lesser number of openings demonstrated more oxygen-transfer efficiency whereas at higher discharges, the aerator having more number of openings yielded more oxygenation-efficiency. Maximum value of oxygen-transfer efficiency of 21.53 kg-O2/kW-hr was obtained for the discharge of 1.11 l/s for single nozzle aerator; however the maximum oxygen-transfer factor of 2.0 × 10−2 s−1 was obtained at discharge of 4.69 l/s for aerator having eight numbers of openings having area of 594.96 mm2. On the other hand, maximum oxygen transfer efficiency of 10.93 kg-O2/kW-hr was demonstrated by aerator with single opening at a discharge of 1.11 l/s and maximum oxygen transfer factor of 7.83 × 10−3 s−1 was obtained from aerator with eight openings at a discharge of 4.69 l/s corresponding to set of aerators with area of openings equal to 246.30 mm2. Multiple non-linear regression modelling was applied to predict oxygen transfer of the aerators for different combinations of input parameters. At the end, the models were compared with conventional methods of aeration and were found to be competitive with traditional devices.