Transfer Formula Research Articles

Luminescence, energy transfer properties of Dy3+/Eu3+ coactivated neutral and warm white emissions GSBG glasses

Dy3+/Eu3+ co-doped GeO2-SiO2-BaO-Ga2O3(GSBG) glass was prepared by the traditional high temperature melting method. The structure and the optical performance of the sample were characterized through X-Ray Diffraction, absorption spectra, photoluminescence spectra, the fluorescence decay time and CIE chromaticity coordinates. The density of the samples was measured. The band gap and the distance between the rare earth ions were calculated theoretically. The energy transfer between Dy3+-Eu3+ was analyzed by Dexter energy transfer formula and I–H model. The results showed that the gap width of Dy3+/Eu3+ doped GSBG glass decreased from 4.6617 eV to 4.1472 eV and the decay time of fluorescence also decreases continuously with the increase of Eu3+ concentrations. The characteristic emission bands of Dy3+ at 483 nm and 574 nm are weakened, while those of Eu3+ at 590 nm and 614 nm are significantly enhanced, indicating that there is energy transfer between Dy3+-Eu3+ and the energy transfer is electric dipole-electric dipole transfer. It is worth noting that the prepared glass emits bright white light under ultraviolet excitation. In particular, sample DE0.5 emits neutral or warm white light under 365 nm excitation. The correlated color temperature is 4763 K; the color coordinate is x = 0.3487, y = 0.3271 and the color purity is low to10.88%, close to the standard white light.

Temperature-dependent light upconversion and thermometric properties of Er3+/Yb3+-codoped SrMoO4 sintered ceramics

A series of Sr1−x−yErxYbyMoO4 phosphor compositions codoped with Er3+ (x = 1 mol%) and varying Yb3+ (y = 0–9 mol%) dopants have been evaluated for luminescence-based thermometry. Sintered ceramics exhibit enhanced grain growth at an optimum Yb3+ content (y = 0.03) and exhibit improved upconversion luminescence and a relatively better thermometric performance over the phosphors in the powder form. Strong upconversion (UC) luminescence at ~ 529, ~ 552, and ~ 662 nm assisted by a 2-photon process, cooperative luminescence from Yb3+ ion pair at 495 nm, and weak UC emissions at ~ 380 and ~ 410 nm due to 3-photon process are identified. Luminescence quenching is observed in all the UC emission bands for Yb3+ content y > 3 mol%. Sensitization from Yb3+ to Er3+ and Yb3+–(MoO4)2− dimer to Er3+ ions results in selective enhancement of the green emission. Variation of UC emission intensity with increasing dopant concentration is analyzed using Dexter’s energy transfer formula, which supports the dipole–dipole interaction between Yb3+ and Er3+ ions. Changes in fluorescence intensity ratio (I529/I552) with temperature reveal the potential usefulness of the optimized Sr0.96Er0.01Yb0.03MoO4 phosphor composition in the ceramic form for non-contact optical thermometry and exhibits good repeatability for temperature sensing applications.

Effects of non-isothermal oxidation on transient conjugate heat transfer of the cryo-supersonic air-quenching

In this paper, the effects of non-isothermal oxidation on transient conjugate heat transfer of the cryo-supersonic air-quenching are investigated based on a double-layered oxidation kinetics model, while a unified conjugate heat transfer formula is developed to synthetically consider the near-wall turbulence, non-isothermal oxidation, and surface radiation. The comparison between numerical and experimental results are also presented to check the validity of the developed model. The results indicate that the film growth has some degree of inhibition to the conjugate heat transfer, in particular, the stagnation temperature increases linearly by about 5 K per 100 ?m increase in film thickness, and the effective conjugate heat transfer coefficient in the stagnation region decreases linearly by about 55 Wm?2K?1 per 100 ?m increase in film thickness. Moreover, the oxide film would have little impact on transient conjugate heat transfer when the near-wall velocity is higher due to the effect of viscous dissipation.

Optimized Layout of Tea Plantation Sensors Based on Improved Ant Colony Optimization

HighlightsIn this article, an improved ant colony algorithm is proposed for optimizing the sensor placement path.The experimental data derived from field measurements.The method in this article reduces the number of sensors and the investment cost.The test results show that data redundancy, data transmission distance, and network energy consumption are reduced.Abstract. In the optimized layout of tea plantation sensors, the number and location of sensors, energy consumption of sensors, and data redundancy are all important factors that affect the layout. To reduce data redundancy, network energy loss, and the cost of sensors, an improved ant colony is proposed. The algorithm optimizes the sensor layout of the tea plantation. Introduce data redundancy and network energy consumption models into the heuristic function to guide the ants to choose the path with less data redundancy and less energy loss; add the path trend guide G to the probability transfer formula to guide the ants from the source node to the sink node Search the path, reduce the path length and the number of sensors. A tea plantation in the National High-tech Agricultural Park of Anhui Agricultural University was selected as the test area, and 25 sensor nodes were randomly arranged to collect soil moisture data for the experiment. The improved ant colony algorithm optimized the path data with less redundancy, less network energy consumption and short distance. Only 6 sensors are needed, reducing the sensor from the initial 25 to 6, which reduces the cost. In order to eliminate the accidental problem of the research results, the soil moisture data collected on 29 August 2019 was selected for the verification test, and the test results were good. Keywords: Data redundancy, Energy consumption, Improved ant colony algorithm, Soil moisture, Tea plantation.

Rwanda: Lessons from Applied Intergovernmental Fiscal Equalization Formula

It is a well-known fact that budgetary allocations need to be based on a just formula for balanced service delivery in the modern world. This paper describes the intergovernmental formula designed for Rwanda in 2003 to allocate grants from the central to local governments (LGs). First, the previous criterion, the Local Authority Budget Support Fund, was reviewed. This was followed by a literature review and field visits. Finally, the specifications of the mathematical model are described, followed by the proxy selection, data analysis, econometric evaluation, and estimations used in the study. In 2003, data analysis revealed that LGs had low fiscal capacities and ubiquitous fiscal needs. These were proxied by mean own source revenues and expenditure needs, respectively, in the proposed formula. The difference between the two was taken as the mean fiscal gap. This formula corrected the inherent weaknesses in the previous transfer system. It proposed weighting parameters to determine subnational transfer entitlements. Additionally, it constructed and applied welfare poverty and fiscal gap indices that captured the behavior of LGs in terms of wellbeing, fiscal needs, and revenue capacity for the first time in Rwanda. The study recommendations were entirely adopted by the government. The formula was used to allocate unconditional grants from the central government to LGs to improve service delivery and reduce poverty. The study also highlights that any successful transfer formula design depends on how the following are determined—the transfer pool, weights, proposed variables, and proxy indices—and how they enter the model.

Study on Heat Transfer Performance of Antifreeze-R134a Heat Exchanger (ARHEx)

In this paper, the liquid cooling and vapor compression refrigeration system based on an Antifreeze-R134a Heat Exchanger (ARHEx) was applied to the thermal management system for high-power avionics in helicopters. The heat transfer performance of the ARHEx was studied. An experimental prototype of ARHEx was designed and established. A series of experiments was carried out with a ground experimental condition. A heat transfer formula for the antifreeze side in the ARHEx was obtained by means of the coefficient of Nusselt number with experimental analysis. The performance of heat transfer and pressure drop for the refrigerant side of the ARHEx was deduced for the given condition.

MPS eutectic reaction model development for severe accident phenomenon simulation

During the postulated severe accident of nuclear reactor, eutectic reaction leads to low-temperature melting of fuel cladding and early failure of core structure. In order to model eutectic melting with the moving particle semi-implicit (MPS) method, the eutectic reaction model is developed to simulate the eutectic reaction phenomenon. The coupling of mass diffusion and phase diagram is applied to calculate the eutectic reaction with the uniform temperature. A heat transfer formula is proposed based on the phase diagram to handle the heat release or absorption during the process of eutectic reaction, and it can combine with mass diffusion and phase diagram to describe the eutectic reaction with temperature variation. The heat transfer formula is verified by the one-dimensional melting simulations and the predicted interface position agrees well with the theoretical solution. In order to verify the eutectic reaction models, the eutectic reaction of uranium and iron in two semi-infinite domains is simulated, and the profile of solid thickness decrease over time follows the parabolic law. The modified MPS method is applied to calculate Transient Reactor Test Facility (TREAT) experiment, the penetration rate in the simulations are agreeable with the experiment results. In addition, a hypothetical case based on the TREAT experiment is also conducted to validate the eutectic reaction with temperature variation, the results present continuity with the simulations of TREAT experiment. Thus the improved method is proved to be capable of simulating the eutectic reaction in the severe accident.

Summary of a Numeric Method for Calculating Heat Transfer in the Rotary Air Preheater

Due to the introduction and implementation of new standards and new specifications, the structure of the heat transfer elements inside the air preheater has undergone relatively large changes. The thermal calculation method of the rotary air preheater is based on the Soviet 1973“Standard Method for Thermal Calculation of Boiler Units” It has been impossible to directly establish the heat transfer formula. According to the actual operating conditions of the rotary air preheater, the boundary conditions of the calculated heat transfer model can be obtained, including: the inlet temperature and inlet flow rate of the flue gas and air of the preheater; the heat transfer element of the regenerator is repeated Rotation, there are continuous conditions of the temperature of the heat storage element heat transfer element between the different air flow sub-bins. And a method for solving discrete equations is proposed.

Broadband near-infrared luminescence and energy transfer of Cr3+, Ce3+ co-doped Ca2LuHf2Al3O12 phosphors

Broadband near-infrared phosphors are highly desirable for food testing. Targeted Ca2LuHf2Al3O12:Cr3+ (CLHA:Cr3+) and Ca2LuHf2Al3O12:Ce3+,Cr3+ (CLHA:Ce3+,Cr3+) phosphors were synthesized by the conventional high-temperature solid state reaction. The CLHA:Cr3+ phosphor, with a good thermal stability, shows a red shift owing to radiation reabsorption and non-radiative transition with increasing Cr3+ content. For co-doped sample, the emission intensity of Cr3+ can be enhanced by three times due to the energy transfer from Ce3+ to Cr3+, which can be evidenced by a significant overlap between the PLE of Cr3+ single-doped phosphor and the PL of Ce3+ single-doped phosphor. In addition, the mechanism of energy transfer is identified as a quadrupole-quadrupole interaction according to decay lifetime and Dexter's energy transfer formula. The broadband NIR emission peaked at 775 nm of CLHA:Cr3+,Ce3+ phosphor shows a bright prospect in nondestructive quality-control analysis systems for food.

Research on Calculation Method of External Convective Heat Transfer Coefficient of Civil Aircraft

Based on the study of calculation method of external convective heat transfer coefficient of civil aircraft, this paper proposes a simulation calculation method, heat transfer formula method, which can be used to solve the external convective heat transfer coefficient of each part of aircraft under flight conditions. The STAR-CCM+ software is used as the calculation platform. Based on a civil aircraft, the theoretical reference temperature method is used to verify the heat transfer formula method. The results show that the difference between the simulation value of heat transfer formula method and the theoretical value of reference temperature method is about 8% of the theoretical value, so the value calculated by heat transfer formula method is basically accurate. Correct the theoretical value based on the simulated value, that can be used to solve the external convective heat transfer coefficient of each part of aircraft.

Strain transfer analysis of substrate fiber Bragg grating sensor in engineering structure health monitoring

Fiber Bragg grating sensors are usually buried in the matrix or pasted on the surface of the matrix in practical engineering applications. Due to the different physical and mechanical properties of the fiber, the protective layer, the adhesive layer and the matrix material, the measured strain of fiber Bragg grating sensors is not equal to the actual strain of the matrix structure, so it is necessary to correct the measured strain. Based on substrate optical fiber grating sensor as the research object, established the “matrix structure, colloid, substrate, colloid, and fiber Bragg grating sensor of strain transfer model, deduce the substrate optical fiber grating sensor measurement of strain and matrix structure actual strain between the strain transfer calculation formula, and through the finite element analysis and experiment validation of theoretical derivation. Finite element analysis and experiments verify the correctness of theoretical derivation, and the strain transfer formula obtained can be applied to practical engineering.

Efficient blue-white color luminescence with near-ultraviolet excitation in Dy3+/Tm3+:Na3Gd(PO4)2 nanophosphor for white LEDs

The Dy3+, Tm3+ ions activated, and Dy3+/Tm3+ ions co-activated Na3Gd(PO4)2 phosphors were synthesized by the citrate-gel based combustion technique. The structural properties of as-synthesized phosphors were studied through X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The influence of Tm3+ concentration on the fluorescence properties of Na3Gd(PO4)2:Dy3+/Tm3+ phosphors were systematically investigated under near-UV light irradiation of 359 and 352 nm. The energy transfer efficiency (ηET) of as-prepared phosphors increases gradually from 17 to 42%, and the critical distance (Rc) between Dy3+ and Tm3+ ions is calculated to be 4.76 Å. For better understanding the energy transfer mechanism (ET:Dy3+ →Tm3+), the decay curves were utilized on the basis of Dexter's energy transfer formula and Reisfeld's approximation. More importantly, the obtained CIE color coordinates of Na3Gd(PO4)2:Dy3+/Tm3+ phosphors located at blue-white region under near-UV light irradiation. The results demonstrate the promising application of Na3Gd(PO4)2:Dy3+/Tm3+ phosphor for near-UV white LEDs.

Energy transfer investigation of Sm3+/Eu3+ CaBAl glasses

Sm3+/Eu3+ codoped CaBAl glasses were prepared by conventional melt-quenching method, and their structural and optical properties were studied. The values of volumetric density and electronic polarizability showed an increase with the addition of Sm2O3. The Fourier-transform infrared spectroscopy (FTIR) spectra indicated the existence of trigonal and tetrahedral borate groups. The N4 values revealed that Sm2O3/Eu2O3 codoping favored the conversion of structural units from BO4 to BO3. The observed absorption bands in UV/VIS spectra were attributed to Eu3+ and Sm3+ transitions, from the ground states 7F0 and 6H5/2 to the various excited states. Color coordinates at CIE diagram were studied for the codoped glasses upon exciting at 405 nm. The energy transfer from the level 4G5/2 of Sm3+ to the 5D0 level of Eu3+ was verified by means of the luminescence results. With the addition of Sm3+, emission intensity of Eu3+ has been enhanced due to migration of Sm3+ excitation energy. The mechanism for energy transfer from Sm3+ to Eu3+ was investigated by Dexter energy transfer formula and Reisfeld's theory application on photoluminescence decay curves. A decrease in the lifetime of 4G5/2 → 6H7/2 transition was observed when Sm3+ was increased, probably due to ion-ion interaction and excitation energy migration.

An Analysis of Equalizing Capacity of State Transfers for Local Government Activities in Bulgaria

The aim of this paper is to examine the fiscal disparities among local governments in Bulgaria and to show the capabilities of the existing intergovernmental transfer system to reduce them. Fiscal equalization policy in Bulgaria is performed through a general equalization transfer for local activities the distribution of which is based on local government tax revenue, as well as on service delivery costs. We measured the extent of equalization in three years – 2007, 2011 and 2017, during which the equalization transfer formula underwent considerable changes. For 365 municipalities we found out that, although the applied equalization mechanisms reduced the inequality in municipal own-source revenuе the remaining fiscal disparities among local governments were still considerable. Our research also suggests that disparity-reducing strength of the general equalization transfer remained almost unchanged during the period under review with its equalizing potential hampered to a great extent by the inclusion of additional compensatory elements in the distribution formula.

A simulation of bubble growth on heating surface in subcooled boiling water based on the heat flows derived by experiment

Two growth processes of individual bubble on heating surface in subcooled boiling water were numerically studied based on the heat flows derived by experiment. In the experiment, a high speed camera was used to photograph the growth and condensation process of a single bubble in low subcooling degree water under normal pressure. The bulk fluid temperature and the temperature of heating wall at the nucleation point were recorded. Based on the experimental data of the bubble condensation process, the convective heat transfer formula at the bubble cap was derived and the heat flow distributions during the whole process were obtained. Then a numerical simulation of the whole process was conducted according to the heat flows. The bubble size, bubble shape and temperature fields were obtained. The simulation results can confirm the rationality and correctness of the theoretical analysis, for the bubble size is highly close to the experiment data. The results also indicated that the evaporation at the bubble base accounts for more than 45% of the total evaporation, which is mainly contributed by microlayer.

Long-Term Implications of the Revenue Transfer Methodology in the Affordable Care Act

The Affordable Care Act introduced a revenue transfer formula that requires insurance plans with generally healthier enrollees to pay funds into a revenue transfer pool to reimburse plans with generally less healthy enrollees. For a given plan, the issue arises of whether the plan will be a payer into or a receiver from the pool in a chosen future year. To examine that issue, we analyze data from The Actuary Magazine on transfer payments for 2014–2015, and we infer strong evidence of a statistical relationship between year-to-year transfer payments. We also apply to the data a Markov transition model to study annual changes in the payer–receiver statuses of insurance plans. We estimate that the limiting conditional probability that an insurance plan will pay into the pool, given that the plan had paid into the pool in 2014, is 55.6%. Further, that limiting probability is attained quickly because the conditional probability that an insurance plan will pay into the pool in 2024, given that the plan had paid into the pool in 2014, is estimated to be 55.7%. We also find the revenue transfer system to have the disturbing feature that once a plan enters the “state” of paying into the pool, it will stay in that state for an average period of 4.87 years; also, once a plan has received funds from the pool, it will stay in that state for an average period of 3.89 years.

Multicolour emission from thermally stable Tb3+/Eu3+ co-doped CaLa4Si3O13 phosphors for single-component w-LEDs application

Colour-tuneable Tb3+/Eu3+ co-doped CaLa4Si3O13 phosphors were prepared by a high-temperature solid-state reaction approach. The contraction of unit cell volume was concluded from the XRD Rietveld refinements data after introduction of dopants and suggests that the dopants have been effectively incorporated into the La3+ sites. Characteristic emission peaks at 545 and 617 nm originated from Tb3+ and Eu3+ emitting centres are observed under the excitation of 379 nm light. An adjustment of emission colour is achieved by varying the Eu3+ concentration. Energy transfer from Tb3+ to Eu3+ ions is experimentally confirmed from the photoluminescence and lifetime measurements. The dipole-dipole interaction is proposed as the main energy transfer route by Dexter's energy transfer formula and Inokuti-Hirayama model. The prepared phosphors exhibit good thermal stability at elevated temperatures. The results indicate that the synthesized materials have a great potential for single-component w-LED applications.

Nonlinear Model Establishment and Experimental Verification of a Pneumatic Rotary Actuator Position Servo System

In order to accurately reflect the characteristics and motion states of a pneumatic rotary actuator position servo system, an accurate non-linear model of the valve-controlled actuator system is proposed, and its parameter identification and experimental verification are carried out. Firstly, in the modeling of this system, the mass flow rate of the gas flowing through each port of the proportional directional control valve is derived by taking into account the clearance between the valve spool and the sleeve, the heat transfer formula is used to the derivation of the energy equation, and the Stribeck model is applied to the friction model of the pneumatic rotary actuator. Then, the flow coefficient, the heat transfer coefficient and the friction parameters are identified by the model and pneumatic test circuits. After the verification experiment of the mass flow rate equations, the charging and discharging experiment reveals that the model can clearly show the effect of clearances on gas pressure changes and describe the effect of heat transfer on gas temperature changes. Finally, the results of model verification indicate that the simulation curves of rotation angle and two-chamber pressures are consistent with their experimental values, and the non-linear model shows high accuracy.

Research on active steering control strategy based on sideslip angle estimation for a steering‐by‐wire forklift

Taking the TFC35 electric forklift as the research object, we analyze the movements and forces of the forklift in three directions: yaw, lateral movement, and roll. Combined with the load transfer formula of the forklift and the nonlinear and linear tire model, the formula for lateral force of the four tires of forklift is deduced, and the nonlinear and linear three‐degree‐of‐freedom (3DOF) forklift dynamics model is established. Because the sideslip angle of the forklift is not easy to measure directly, based on the linear 3DOF forklift model, we take the yaw rate and lateral angle as the observation variables and consider the influence of model error. An adaptive Kalman filter is designed to estimate the sideslip angle of the forklift. In order to improve the accuracy of estimation, an online optimization strategy of the adaptive Kalman filter based on genetic algorithm with an adaptive factor is proposed. Simulation results show the effectiveness of the proposed method. In combination with the forklift reference model, the rear wheel angle of the forklift is corrected by comprehensive proportional feedback of yaw rate and the sideslip angle, and the active steering system for a steering‐by‐wire forklift is designed. Simulation and test results show that the control strategy of forklift's active steering system can improve its driving stability and handling performance. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Evolution Mechanism of Photonically Sintered Nano-Silver Conductive Patterns.

Flash sintering is the most promising sintering method because of its high speed and large area of effect. However, current flash sintering processes exhibit poor stability and the conductive pattern surface is highly susceptible to damage during this process. Therefore, a sintering parameter prediction system must be established to optimize sintering parameters for manufacturing. In this study, a photon-sintered nano-silver particle model is proposed for studying the sintering characteristics of metal nanoparticles. The temperature field of the sintering area is obtained using the heat transfer formula and the sintered neck state, and the conductive pattern density of the nano-silver particles are obtained by employing the fluid dynamics finite element method. The conductive pattern’s structural density and conductivity are determined using the electronic state density and potential distribution of the crystal structure. The sintering state is then predicted based on the sintering parameters. The simulation results are consistent with conductive patterns corresponding to different sintering degrees observed using an electron microscope. The results of this study provide reference sintering parameters for flash sintering with effective cost reduction.