scholarly journals FEM-Analysis of 2D Micromachined Flow Transduers based on aGe-Thermistor Arrays and a Double Bridge Readout

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3561
Author(s):  
Almir Talic ◽  
Samir Cerimovic ◽  
Roman Beigelbeck ◽  
Franz Kohl ◽  
Thilo Sauter ◽  
...  
Keyword(s):  
Leading Edge ◽  
Fem Analysis ◽  
High Accuracy ◽  
Thermal Flow ◽  
Excess Temperature ◽  
Temperature Variations ◽  
Air Gaps ◽  
Flow Velocity Field ◽  
Planar Surfaces ◽  
Thin Film Devices

This paper reports on a design and simulation study aiming at high-accuracy 2D micromachined thermal flow transducers. The scope is restricted to micromachined devices featuring a square-shaped membrane incorporating central symmetric thin-film devices. A microthermistor array probed spatial excess temperature variations while the main heat supply was alternatively established by optional heating resistors or by pronounced self-heating of the thermistor devices. Proper device designs enable leading edge transducer performance without sophisticated signal conditioning schemes. We found that a high azimuthal uniformity of flow magnitude transduction is tantamount to a precise azimuthal accuracy. The most advanced result gave a maximum azimuthal aberration of 0.17 and 1.7 degrees for 1 m/s and 10 m/s, respectively, while the corresponding magnitude uniformity amounted to 0.07% and 0.5%. Such excellent specifications exceed the need of ordinary meteorological applications by far. However, they are essential for, e.g., precise non-contact measurements of 2D relative movements of two quasi-planar surfaces via the related Couette flow in intermediate air gaps. The simulations predicted significantly better device characteristics than achieved by us in first experiments. However, this gap could be attributed to imperfect control of the flow velocity field by the measurement setup.

Numerical and experimental modeling of the thermal flow in a modern rotary transfer machine

2021 ◽  
pp. 1-23
Author(s):  
Francesco Robusto ◽  
Dario Croccolo ◽  
Massimiliano De Agostinis ◽  
Stefano Fini ◽  
Giorgio Olmi ◽  
...  
Keyword(s):  
Relative Displacement ◽  
Numerical Control ◽  
Heat Sources ◽  
Thermal Flow ◽  
Complete Model ◽  
Rolling Bearings ◽  
Temperature Variations ◽  
Friction Heat ◽  
Working Day ◽  
Thermal Sources

Abstract The aim of this study is to estimate the relative displacement between the spindle nose and the clamping vice in a rotary transfer machine due to temperature variations. The study was focused on the relative displacements caused by temperature variations produced by two heat sources: the environment around the machine and the 3-axis computer numerical control station during the duty cycle. Regarding the last point, an analytical model was developed, in order to account for different thermal sources inside the 3-axis module (e.g. ball screws, rolling bearings and guideways friction heat, as well as heat generation in the motor). The complete numerical model was calibrated and successfully validated. Comparison was run between numerical results and experimental data in the framework of trials involving a newly developed transfer machine. Finally, the complete model, considering the combination of both the heat sources, has made it possible to estimate spindle nose-clamp relative displacement during a typical working day, highlighting that the radial displacement risks affecting seriously the accuracy of a workpiece.

FEM Analysis of a 0.50 Caliber Rifle Barrel

2010 ◽  
Author(s):  
Gary A. Anderson ◽  
Corey M. Lanoue ◽  
Fereidoon Delfanian
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Leading Edge ◽  
Fem Analysis ◽  
High Strength ◽  
Element Model ◽  
Pressure Profile ◽  
Strength Analysis ◽  
Analysis Tool ◽  
Element Analysis

In order to ensure rifle barrels have the features of high strength, durability, and light weight, the strength analysis of the barrels under hot temperatures and pressures is very important in the design. A finite element model incorporating the plastic deformation of a typical 0.50 caliber rifle barrel is constructed to determine the stresses caused by the mechanical loads and plastic deformation. According to the simulation results, the finite element analysis is proved to be a power analysis tool for future failure analysis of firearm barrels. The method provides a power tool for analysis of firearm barrels. The projectile was accelerated to 941.7 m/s in 1.430 ms with a pressure profile that reached a maximum of 469.3 MPa. Stresses as large as 1,410 MPa along the interior of the barrel were found where the leading edge of the projectile slides along the bore, but the largest stresses at the exterior of the barrel were found where the barrel wall is thinnest near the chamber.

The FEM Analysis on the Damage of Wing Leading Edge under Hail Impact

2012 ◽  
Vol 460 ◽  
pp. 330-333
Author(s):  
Xiao Qing Zhang ◽  
Xuan Liu ◽  
Xiao Hu Yao
Keyword(s):  
Impact Damage ◽  
Leading Edge ◽  
Fem Analysis ◽  
Dynamic Responses ◽  
Composite Panel ◽  
Damage State ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Medium Speed ◽  
Hail Impact

The low and medium speed impact damage of composite structure of wing leading edge under hail impact is examined by numerical simulations, using nonlinear dynamic finite element analysis software LS-DYNA. For different impact velocities, the dynamic responses of wing leading edge are obtained and the damage in composite panel is clearly demonstrated. The relations of impact energy, maximum displacement and the damage state are analyzed. The simulation results can provide some references for the design of wing leading edge.

scholarly journals Workpiece Temperature Variations During Flat Peripheral Grinding

2018 ◽  
Vol 26 (2) ◽  
pp. 93-98 ◽  
Author(s):  
Vitalii A. Smirnov ◽  
Aleksandr V. Repko
Keyword(s):  
High Accuracy ◽  
Grinding Force ◽  
Nonlinear Heat Equation ◽  
Stability And Convergence ◽  
Grinding Temperature ◽  
Thermal Impact ◽  
Specific Nature ◽  
Temperature Variations ◽  
Thermophysical Model ◽  
Experimental Values

Abstract The paper presents the results of researches of temperature variations during flat peripheral grinding. It is shown that the temperature variations of the workpiece can reach 25...30% of the average values, which can lead to some thermal defects. A nonlinear two-dimensional thermophysical grinding model is suggested. It takes into account local changes in the cutting conditions: the fluctuation of the cut layer and the cutting force, the thermal impact of the cutting grains, and the presence of surface cavities in the intermittent wheel. For the numerical solution of the problem, the method of finite differences is adapted. Researches of the method stability and convergence are made, taking into account the specific nature of the problem. A high accuracy of the approximation of the boundary conditions and the nonlinear heat equation is provided. An experimental verification of the proposed thermophysical model was carried out with the use of installation for simultaneous measurement of the grinding force and temperature. It is shown that the discrepancy between the theoretical and experimental values of the grinding temperature does not exceed 5%. The proposed thermophysical model makes it possible to predict with high accuracy the temperature variations during grinding by the wheel periphery.

Application of Ultrasonic Anemometer Array to Field Measurements of the Downwash Flow of an Agricultural Unmanned Helicopter

2019 ◽  
Vol 62 (5) ◽  
pp. 1219-1230 ◽  
Author(s):  
Qing Tang ◽  
Ruirui Zhang ◽  
Chenchen Ding ◽  
Liping Chen ◽  
Min Xu ◽  
...  
Keyword(s):  
Velocity Field ◽  
Flow Velocity ◽  
Field Data ◽  
Radial Distance ◽  
High Accuracy ◽  
Unmanned Helicopter ◽  
Differential Gps ◽  
Forward Flight ◽  
Flow Velocity Field ◽  
Ultrasonic Anemometer

Abstract. Unmanned helicopters are widely used in agricultural spray applications; however, there is a lack of high-accuracy field data on the complex downwash flows caused by such helicopters to support efficient spraying. Therefore, we aimed to collect high-accuracy reference data by developing an ultrasonic anemometer array and related software to measure the downwash flow velocity field of a common agricultural unmanned helicopter (Copterworks AF-25B) during outdoor hovering and forward flight. Differential GPS and image scaling were used to determine the exact position and velocity of the helicopter to ensure repeatability of the tests. When the hovering height of the rotor above the ground plane was y/R = 2.5 (where y is the height above ground level and R is the radius of the rotor), the maximum downwash velocity reached 7 m s-1 at x/R = 0.5 (where x is the radial distance from the axis of the rotor). In addition, we obtained the spatial distribution of the turbulence kinetic energy. The attached flow velocity in the near-ground boundary layer increased radially and reached a maximum of 3 m s-1 at x = 3.6 m, after which it decreased. Comparatively, the maximum downwash velocity during forward flight occurred between x/R = 0.5 and 1.5 and was only about 3 m s-1, which was less than half the maximum downwash velocity while hovering. In addition, the circulation flow below the rotor tips had a velocity of 1.5 m s-1. The downwash flow lasted more than 1 s as the helicopter passed over a given point on the ground, the downwash velocity decreased from 3 m s-1 to 1.5 to 2.5 m s-1, and the symmetry of the flow field was not maintained. This study is the first application of an ultrasonic anemometer array to measure the airflow around an unmanned helicopter and provides high-accuracy field data that can be used as a reference for future indoor and simulation studies. Keywords: Agricultural unmanned helicopter, Downwash flow velocity field, Forward flight, Hovering, Ultrasonic anemometer.

scholarly journals Radiation-Conduction Interaction of Steady Streamwise Surface Temperature Variations on Vertical Free Convection

2011 ◽  
Vol 2011 ◽  
pp. 1-11
Author(s):  
Md. Kutub Uddin ◽  
Rabindra Nath Mondal
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Heated Surface ◽  
Leading Edge ◽  
Mean Value ◽  
Physical Parameters ◽  
Convective Boundary ◽  
Temperature Variations ◽  
Local Shear ◽  
Layer Flow

The combined effects of the steady free convective boundary-layer flow induced by a vertical heated surface in the presence of sinusoidal surface temperature variations about a constant mean value with the effect of radiation are examined. The problem is studied using fully numerical techniques. The surface rate of heat transfer eventually alternates in sign with distance from the leading edge, but no separation occurs unless the amplitude of the thermal modulation is sufficiently high. Numerical results are obtained for different values of the physical parameters, the radiation parameter Rd, the Prandtl number Pr, and the surface temperature wave amplitude a. It is found that both the local shear stress and the rate of heat transfer decrease when values of Rd increase.

scholarly journals Atropos: specific, sensitive, and speedy trimming of sequencing reads

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3720 ◽  
Author(s):  
John P. Didion ◽  
Marcel Martin ◽  
Francis S. Collins
Keyword(s):  
High Performance ◽  
State Of The Art ◽  
Leading Edge ◽  
High Sensitivity ◽  
High Accuracy ◽  
Free Software ◽  
Short Read Sequencing ◽  
Sequencing Errors ◽  
Quality And Reliability ◽  
Broad Feature

A key step in the transformation of raw sequencing reads into biological insights is the trimming of adapter sequences and low-quality bases. Read trimming has been shown to increase the quality and reliability while decreasing the computational requirements of downstream analyses. Many read trimming software tools are available; however, no tool simultaneously provides the accuracy, computational efficiency, and feature set required to handle the types and volumes of data generated in modern sequencing-based experiments. Here we introduce Atropos and show that it trims reads with high sensitivity and specificity while maintaining leading-edge speed. Compared to other state-of-the-art read trimming tools, Atropos achieves significant increases in trimming accuracy while remaining competitive in execution times. Furthermore, Atropos maintains high accuracy even when trimming data with elevated rates of sequencing errors. The accuracy, high performance, and broad feature set offered by Atropos makes it an appropriate choice for the pre-processing of Illumina, ABI SOLiD, and other current-generation short-read sequencing datasets. Atropos is open source and free software written in Python (3.3+) and available at https://github.com/jdidion/atropos.

scholarly journals Clandestine nanoelectromechanical tags for identification and authentication

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Sushant Rassay ◽  
Mehrdad Ramezani ◽  
Sumaiya Shomaji ◽  
Swarup Bhunia ◽  
Roozbeh Tabrizian
Keyword(s):  
Consumer Goods ◽  
Global Economy ◽  
Adaptive Algorithms ◽  
High Accuracy ◽  
Spectral Signature ◽  
Large Set ◽  
Temperature Variations ◽  
Wide Range ◽  
Key Factor ◽  
Binary Fingerprints

AbstractThe realization of truly unclonable identification and authentication tags is the key factor in protecting the global economy from an ever-increasing number of counterfeit attacks. Here, we report on the demonstration of nanoscale tags that exploit the electromechanical spectral signature as a fingerprint that is characterized by inherent randomness in fabrication processing. Benefiting from their ultraminiaturized size and transparent constituents, these clandestine nanoelectromechanical tags provide substantial immunity to physical tampering and cloning. Adaptive algorithms are developed for digital translation of the spectral signature into binary fingerprints. A large set of tags fabricated in the same batch is used to estimate the entropy of the corresponding fingerprints with high accuracy. The tags are also examined under repetitive measurements and temperature variations to verify the consistency of the fingerprints. These experiments highlight the potential of clandestine nanoelectromechanical tags for the realization of secure identification and authentication methodologies applicable to a wide range of products and consumer goods.

High Frequency and High Accuracy Laser Ranging System Based on Double Thresholds Leading-Edge Timing Discrimination

2013 ◽  
Vol 33 (9) ◽  
pp. 0912002 ◽  
Author(s):  
陈瑞强 Chen Ruiqiang ◽  
江月松 Jiang Yuesong ◽  
裴朝 Pei Zhao
Keyword(s):  
High Frequency ◽  
Leading Edge ◽  
High Accuracy ◽  
Laser Ranging

Acoustic receptivity simulations of flow past a flat plate with elliptic leading edge

2016 ◽  
Vol 800 ◽  
Author(s):  
Nima Shahriari ◽  
Daniel J. Bodony ◽  
Ardeshir Hanifi ◽  
Dan S. Henningson
Keyword(s):  
Numerical Methods ◽  
Numerical Simulations ◽  
Flat Plate ◽  
Incompressible Flow ◽  
Acoustic Waves ◽  
Asymptotic Theory ◽  
Finite Thickness ◽  
Leading Edge ◽  
High Accuracy ◽  
Order Of Magnitude

We present results of numerical simulations of leading-edge acoustic receptivity for acoustic waves impinging on the leading edge of a finite-thickness flat plate. We use both compressible and incompressible flow solvers fitted with high-order high-accuracy numerical methods and independent methods of estimating the receptivity coefficient. The results show that the level of acoustic receptivity in the existing literature appears to be one order of magnitude too high. Our review of previous numerical simulations and experiments clearly identifies some contradictory trends. In the limit of an infinitely thin flat plate, our results are consistent with asymptotic theory and numerical simulations.

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