MEMS Integrated Electro-Fluid-Elastic Modeling for Aerospace Applications

2006 ◽  
Author(s):  
Alessandro Fumagalli ◽  
Giuseppe Quaranta ◽  
Paolo Mantegazza
Keyword(s):  
Jacobian Matrix ◽  
Dynamical Analysis ◽  
Published Data ◽  
Field Equations ◽  
Fully Integrated ◽  
Aerospace Applications ◽  
Integrated Methodology ◽  
Proposed Model ◽  
Elastic Systems ◽  
Good Agreement

MEMS physics is characterized by multi-fields interactions. In this paper, a fully integrated methodology is proposed for dynamical analysis of electro-fluid-elastic systems, typical of MEMS-based microresonators and microswitches. Finite Elements/Volumes Method is used to solve field equations. These are coupled by an opportune procedure of interface between domains, resulting in a nonlinear algebraic differential system of equations describing the system. This is directly integrated in time, becoming fully algebraic, and solved by a Newton technique. Full Jacobian matrix computation results in a very hard task. Analytical block approximation for Jacobian matrix is proposed. Model is validated comparing results with commercial codes and with published data, showing good agreement, high convergence properties and reduced computational efforts.

scholarly journals Compact Modelling of Electrical, Optical and Thermal Properties of Multi-Colour Power LEDs Operating on a Common PCB

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1286
Author(s):  
Krzysztof Górecki ◽  
Przemysław Ptak
Keyword(s):  
Integrated Circuits ◽  
Optical Model ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Junction Temperature ◽  
Optical Parameters ◽  
Spice Simulation ◽  
Light Emitting ◽  
Proposed Model ◽  
Good Agreement

This paper concerns the problem of modelling electrical, thermal and optical properties of multi-colour power light-emitting diodes (LEDs) situated on a common PCB (Printed Circuit Board). A new form of electro-thermo-optical model of such power LEDs is proposed in the form of a subcircuit for SPICE (Simulation Program with Integrated Circuits Emphasis). With the use of this model, the currents and voltages of the considered devices, their junction temperature and selected radiometric parameters can be calculated, taking into account self-heating phenomena in each LED and mutual thermal couplings between each pair of the considered devices. The form of the formulated model is described, and a manner of parameter estimation is also proposed. The correctness and usefulness of the proposed model are verified experimentally for six power LEDs emitting light of different colours and mounted on an experimental PCB prepared by the producer of the investigated devices. Verification was performed for the investigated diodes operating alone and together. Good agreement between the results of measurements and computations was obtained. It was also proved that the main thermal and optical parameters of the investigated LEDs depend on a dominant wavelength of the emitted light.

Static and Dynamic Structure of Molecular Monomers and Dimers of the Rare-earth Fluorides

2001 ◽  
Vol 56 (5) ◽  
pp. 381-385
Author(s):  
Z. Akdeniz ◽  
M . Gaune-Escard ◽  
M. P. Tosi
Keyword(s):  
Rare Earth ◽  
Bond Length ◽  
Geometrical Structure ◽  
Vibrational Mode ◽  
Dynamic Structure ◽  
Molecular Shape ◽  
Proposed Model ◽  
Infrared Studies ◽  
Charged Clusters ◽  
Good Agreement

Abstract We determine a model of the ionic interactions in RF3 compounds, where R is a rare-earth element in the series from La to Lu, by an analysis of data on the bond length and the vibrational mode frequencies of the PrF3, GdF3 and HoF3 molecular monomers. All RF3 monomers are predicted to have a pyramidal shape, displaying a progressive flattening of the molecular shape in parallel with the lanthanide contraction of the bond length. The vibrational frequencies of all monomers are calculated, the results being in good agreement with the data from infrared studies of matrix-isolated molecules. We also evaluate the geometrical structure and the vibrational spectrum of the La2F6 and Ce2F6 dimers, as a further test of the proposed model. -PACS 36.40.Wa (Charged clusters)

Analysis of Thermal Variation of Length and Refractive Index of Lead Fluoride to Study its Optical Properties

1989 ◽  
Vol 172 ◽  
Author(s):  
T. S. Aurora ◽  
D. O. Pederson ◽  
S. M. Day
Keyword(s):  
Refractive Index ◽  
Room Temperature ◽  
Linear Thermal Expansion ◽  
Small Variation ◽  
Published Data ◽  
Thermal Variation ◽  
Lead Fluoride ◽  
Superionic Phase Transition ◽  
Lorenz Relation ◽  
Good Agreement

AbstractLinear thermal expansion and refractive index variation have been measured in lead fluoride with a laser interferometer as a function of temperature. Data has been analyzed using the Lorentz-Lorenz relation. Molecular polarizability, band gap, variation of refractive index with density, and strain-polarizability parameter have been studied as a function of temperature. They exhibit a small variation with temperature except near the superionic phase transition where the variation appears to be more pronounced. The results are in good agreement with the published data near room temperature.

Reloading Stress Relaxation Behavior Analysis Based on a Creep Model for High Temperature Bolting Steel

2013 ◽  
Vol 328 ◽  
pp. 950-954
Author(s):  
Wei Wei Zhang ◽  
Hong Xu ◽  
Hong Yuan Li
Keyword(s):  
High Temperature ◽  
Stress Relaxation ◽  
Steady State Creep ◽  
Relaxation Behavior ◽  
Creep Model ◽  
National Research Institute ◽  
Time Intervals ◽  
Stress Relaxation Behavior ◽  
Proposed Model ◽  
Good Agreement

An analytical method based on a creep model is being developed to investigate the effect of retightening on stress relaxation behavior for high-temperature turbine and valve studs/bolts. In order to validate the approach, the calculated results are compared to the results of uniaxial reloading stress relaxation testing, which were performed by the National Research Institute for Metals of Japan (NRIM) for 12Cr-1Mo-1W-1/4V stainless steel bolting material at 550°C. It was shown that the proposed model based on Altenbach-Gorash-Naumenko creep model for the primary and steady state creep could be applied for the present data. The calculated residual stresses versus time curves were in good agreement with the measured for initial stress level of 273.6MPa at 550°C and for specific reloading time intervals of 24, 72, 240, and 720 hours.

scholarly journals Compact Model for Bipolar and Multilevel Resistive Switching in Metal-Oxide Memristors

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 98
Author(s):  
Eugeny Ryndin ◽  
Natalia Andreeva ◽  
Victor Luchinin
Keyword(s):  
Metal Oxide ◽  
Equation System ◽  
Software Implementation ◽  
Compact Model ◽  
Metal Oxide Films ◽  
Bipolar Switching ◽  
Proposed Model ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Good Agreement

The article presents the results of the development and study of a combined circuitry (compact) model of thin metal oxide films based memristive elements, which makes it possible to simulate both bipolar switching processes and multilevel tuning of the memristor conductivity taking into account the statistical variability of parameters for both device-to-device and cycle-to-cycle switching. The equivalent circuit of the memristive element and the equation system of the proposed model are considered. The software implementation of the model in the MATLAB has been made. The results of modeling static current-voltage characteristics and transient processes during bipolar switching and multilevel turning of the conductivity of memristive elements are obtained. A good agreement between the simulation results and the measured current-voltage characteristics of memristors based on TiOx films (30 nm) and bilayer TiO2/Al2O3 structures (60 nm/5 nm) is demonstrated.

scholarly journals The exponential cubic B-spline collocation method for the Kuramoto-Sivashinsky equation

Filomat ◽  
2016 ◽  
Vol 30 (3) ◽  
pp. 853-861 ◽  
Author(s):  
Ozlem Ersoy ◽  
Idiris Dag
Keyword(s):  
Collocation Method ◽  
Numerical Solutions ◽  
Spline Approximation ◽  
Algebraic Equations ◽  
Spline Collocation ◽  
Fully Integrated ◽  
B Spline ◽  
Spline Collocation Method ◽  
Sivashinsky Equation ◽  
Good Agreement

In this study the Kuramoto-Sivashinsky (KS) equation has been solved using the collocation method, based on the exponential cubic B-spline approximation together with the Crank Nicolson. KS equation is fully integrated into a linearized algebraic equations. The results of the proposed method are compared with both numerical and analytical results by studying two text problems. It is found that the simulating results are in good agreement with both exact and existing numerical solutions.

scholarly journals The Distribution of Larvae of Randomly Moving Insects

1961 ◽  
Vol 14 (4) ◽  
pp. 598 ◽  
Author(s):  
EJ Williams
Keyword(s):  
Normal Distribution ◽  
Bessel Function ◽  
Theoretical Distribution ◽  
Frequency Function ◽  
Published Data ◽  
Modified Bessel Function ◽  
Theoretical Conclusion ◽  
Constant Rate ◽  
Spatially Distributed ◽  
Good Agreement

Though randomly moving insects released from a central point in a uniform environment are often found to be distributed according to a circular normal distribution, their larvae will not conform to this distribution. When such insects lay at a constant rate and are subject to constant mortality, their larvae are found to be spatially distributed according to a highly peaked frequency function, depending on the modified Bessel function of the second kind. This theoretical conclusion is in good agreement with published data. Some of the properties of the theoretical distribution are discussed.

Randomness in modified general relativity theory: The stochastic f(R) gravity model

2018 ◽  
Vol 96 (11) ◽  
pp. 1173-1177
Author(s):  
Tomer Shushi
Keyword(s):  
Gravity Field ◽  
Gravity Model ◽  
Gravity Models ◽  
Relativity Theory ◽  
Field Equations ◽  
Important Special Case ◽  
Proposed Model ◽  
Stochastic Space ◽  
Wavefunction Collapse ◽  
New Interpretation

We consider a stochastic modification of the f(R) gravity models, and provide its important properties, including the gravity field equations for the model. We show a prediction in which particles are localized by a system of random gravitational potentials. As an important special case, we investigate a gravity model in the presence of a small stochastic space–time perturbation and provide its gravity field equations. Using the proposed model we examine the stochastic quantum mechanics interpretation, and obtain a novel Schrödinger equation with gravitational potential that is based on diffusion in a gravitational field. Furthermore, we provide a new interpretation to the wavefunction collapse. It seems that the stochastic f(R) gravity model causes decoherence of the spatial superposition state of particles.

Modeling Hydroplaning and Effects of Pavement Microtexture

2005 ◽  
Vol 1905 (1) ◽  
pp. 166-176 ◽  
Author(s):  
G. P. Ong ◽  
T. F. Fwa ◽  
J. Guo
Keyword(s):  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Results ◽  
Tire Pressure ◽  
Finite Volume Model ◽  
Proposed Model ◽  
Loss Of Contact ◽  
The One ◽  
Theoretical Considerations ◽  
Good Agreement

Hydroplaning on wet pavement occurs when a vehicle reaches a critical speed and causes a loss of contact between its tires and the pavement surface. This paper presents the development of a three-dimensional finite volume model that simulates the hydroplaning phenomenon. The theoretical considerations of the flow simulation model are described. The simulation results are in good agreement with the experimental results in the literature and with those obtained by the well-known hydroplaning equation of the National Aeronautics and Space Administration (NASA). The tire pressure–hydroplaning speed relationship predicted by the model is found to match well the one obtained with the NASA hydroplaning equation. Analyses of the results of the present study indicate that pavement microtexture in the 0.2- to 0.5-mm range can delay hydroplaning (i.e., raise the speed at which hydroplaning occurs). The paper also shows that the NASA hydroplaning equation provides a conservative estimate of the hydroplaning speed. The analyses in the present study indicate that when the microtexture of the pavement is considered, the hydroplaning speed predicted by the proposed model deviates from the speed predicted by the smooth surface relationship represented by the NASA hydroplaning equation. The discrepancies in hydroplaning speed are about 1% for a 0.1-mm microtexture depth and 22% for a 0.5-mm microtexture depth. The validity of the proposed model was verified by a check of the computed friction coefficient against the experimental results reported in the literature for pavement surfaces with known microtexture depths.

Calculation of 6-Hour Dip Creatinine Ratio from the 4-Hour Peritoneal Equilibration Test. The Effect of Dwell Duration on the Results

1997 ◽  
Vol 17 (3) ◽  
pp. 273-278 ◽  
Author(s):  
Rajnish Mehrotra ◽  
Ramesh Khanna ◽  
Thomas C.K. Yang ◽  
Pranay Kathuria ◽  
Harold L. Moore ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Peritoneal Dialysis ◽  
University Hospital ◽  
Published Data ◽  
Peritoneal Equilibration Test ◽  
Cardiovascular Research ◽  
Proposed Model ◽  
Margin Of Error ◽  
The University ◽  
Exponential Relation

Objectives Since the introduction of the peritoneal equilibration test (PET), the 4-hour dialysatelplasma creatinine (DIP Cr) has been used by several authors for determining continuous ambulatory peritoneal dialysis (CAPD) prescriptions. However, the results have been unsatisfactory because the 4-hr DIP Cr does not accurately reflect the DIP Cr in 24-hr collections. The PET and the 24-hr dialysate collections differ in the duration of dwell and the tonicity and volume of dialysate, all of which influence the equilibrated DIP Cr. It can be assumed that the DIP Cr in 24-hr collections in these patients is closer to a 6-hr DIP Cr. Because a 6hr PET is inconvenient, we developed a mathematical model to calculate the 5 and 6-hr DIP using the results of a standard PET. Design In a retrospective analysis, DIP Cr ratios in 24-hr collections and DIP Cr ratios calculated from a mathematical formula were correlated. Using a mathematical model, the data collected fit an exponential relation of the type DIP = a(1 -e-t/τ). The values of a and τ are unique for a given patient and were determined using a nonlinear regression technique. The formula performed well on our published data -the true and predicted 6-hr DIP Cr being 0.696 and 0.71, respectively. Setting The University Hospital and Clinics, Dalton Cardiovascular Research Center and Dialysis Clinic, Inc., Columbia, Missouri. Patients All CAPD patients on four 2-L exchangeslday at the time of the 24-hr collections were included. Interventions None. Main Outcome Measures Closeness of 4-hr and 6-hr DIP Cr values to those of 24-hr ratios. Results The study group comprised 74 patients (age, mean ± SEM: 56.4 ± 1.8 yr) with 80 PETs and 145 (24-hr) collections. The interval between the two tests was 8. 3 ± 0.9 months (0 48.7 months). The median 24-hr DIP Cr of 0.760 did not differ significantly from the predicted median 6-hr DIP Cr of 0.755. A subgroup analysis, based on transport type, showed that this relationship was most precise in the high-average transporters. The predicted 6hr DIP Cr was within 100;0 of the 24-hr DIP Cr in 48% of patients and within 20% in 77% of patients. The margin of error was greatest in the low transporters. Conclusions To conclude, the 4-hr DIP Cr from a PET cannot be used interchangeably with the DIP Cr in the 24-hr dialysate collections, hence, the clearances calculated thereof will be inaccurate. Using the proposed model, it is feasible to use the 4 -hr PET results to obtain 5 and 6 -hr DIP Cr values. In our study, using this model, the extrapolated 6-hr DIP Cr is similar to the DIP Cr in 24-hr dialysate collections only in the high-average transporters. Hence, the best way to determine clearances in peritoneal dialysis patients is still by collecting 24-hr dialysates.

Sign in / Sign up

Export Citation Format

Share Document