scholarly journals The FMM-BEM Method for the 3D Particulate Stokes Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Hassib Selmi ◽  
Mohamed Abdelwahed ◽  
Hatem Hamda ◽  
Lassaad El Asmi
Keyword(s):  
Spherical Harmonics ◽  
Stokes Flow ◽  
Transfer Functions ◽  
Stokes Problem ◽  
High Accuracy ◽  
Multipole Moments ◽  
Accuracy Level ◽  
Reasonable Cost

This work introduces new functions based on the spherical harmonics and the solid harmonics which have been used to construct a multipole development for the 3D Stokes problem in order to reduce the operations costs in the BEM method. We show that the major properties of those functions are inherited from the solid harmonics. The contribution of this paper is the introduction of new formulas that serve to calculate the multipole moments and the transfer functions that are necessary for the schemes of orderO(NlogN). Moreover, new translation formulas are introduced to obtain anO(N)scheme. The error truncation of the resulting scheme is discussed. In comparison to the BEM that attains a limit storage atO(104), we present here a method based on FMM-BEM that attains a storage at a limit ofO(106). The implementation of the method achieves a high accuracy level at a reasonable cost.

A new version of the Fast Multipole Method for the Laplace equation in three dimensions

Acta Numerica ◽  
1997 ◽  
Vol 6 ◽  
pp. 229-269 ◽  
Author(s):  
Leslie Greengard ◽  
Vladimir Rokhlin
Keyword(s):  
Laplace Equation ◽  
Fast Multipole Method ◽  
High Accuracy ◽  
Three Dimensions ◽  
Potential Fields ◽  
Diagonal Form ◽  
Fast Multipole ◽  
Reasonable Cost ◽  
Multipole Method ◽  
Translation Operators

We introduce a new version of the Fast Multipole Method for the evaluation of potential fields in three dimensions. It is based on a new diagonal form for translation operators and yields high accuracy at a reasonable cost.

scholarly journals Design and Development of a 5-Channel Arduino-Based Data Acquisition System (ABDAS) for Experimental Aerodynamics Research

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2382 ◽  
Author(s):  
Antonio Vidal-Pardo ◽  
Santiago Pindado
Keyword(s):  
Data Acquisition ◽  
Low Cost ◽  
Data Acquisition System ◽  
High Accuracy ◽  
Acquisition System ◽  
Calibration System ◽  
Experimental Aerodynamics ◽  
Accuracy Level ◽  
The Fourier Transform ◽  
Cup Anemometer

In this work, a new and low-cost Arduino-Based Data Acquisition System (ABDAS) for use in an aerodynamics lab is developed. Its design is simple and reliable. The accuracy of the system has been checked by being directly compared with a commercial and high accuracy level hardware from National Instruments. Furthermore, ABDAS has been compared to the accredited calibration system in the IDR/UPM Institute, its measurements during this testing campaign being used to analyzed two different cup anemometer frequency determination procedures: counting pulses and the Fourier transform. The results indicate a more accurate transfer function of the cup anemometers when counting pulses procedure is used.

scholarly journals MULTI-CHANNEL FRY COUNTER DESIGN USING OPTOCOUPLER SENSOR

2019 ◽  
Vol 4 (2) ◽  
pp. 97-104
Author(s):  
Lazuardi Umar ◽  
Yanuar Hamzah ◽  
Rahmondia N. Setiadi
Keyword(s):  
Counting Process ◽  
Production Capacity ◽  
High Accuracy ◽  
Limited Capacity ◽  
High Concentration ◽  
Counting System ◽  
Channel Detection ◽  
Accuracy Level ◽  
High Level ◽  
Almost All

This paper describes a design of a fry counter intended to be used by consuming fish farmer. Along this time, almost all the fry counting process is counted by manual, which is done by a human. It is requiring much energy and needs high concentration; thus, can cause a high level of exhaustion for the fry counting worker. Besides that, the human capability and capacity of counting are limited to a low level. A fry counter design in this study utilizes a multi-channel optocoupler sensor to increase the counting capacity. The multi-channel fry counter counting system is developed as a solution to a limited capacity of available fry counter. This design uses an input signal extender system on controller including the interrupt system. From the experiment, high accuracy level is obtained on the counting and channel detection, therefore, this design can be implemented and could help farmers to increase the production capacity of consuming fish.

scholarly journals Review and Selection Strategy for High-Accuracy Modeling of PWM Converters in DCM

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Yu-Jun Mao ◽  
Chi-Seng Lam ◽  
Sai-Weng Sin ◽  
Man-Chung Wong ◽  
Rui Paulo Martins
Keyword(s):  
Closed Loop ◽  
Transfer Functions ◽  
High Accuracy ◽  
Operating Conditions ◽  
Selection Strategy ◽  
Small Signal ◽  
Pwm Converters ◽  
Modeling Methods ◽  
The Past ◽  
Conduction Mode

Among various modeling methods for DC-DC converters introduced in the past two decades, the state-space averaging (SSA) and the circuit averaging (CA) are the most general and popular exhibiting high accuracy. However, their deduction approaches are not entirely equivalent since they incorporate different averaging processes, thus yielding different small signal transfer functions even under identical operating conditions. Some research studies claimed that the improved SSA can obtain the highest accuracy among all the modeling methods, but this paper discovers and clearly verifies that this is not the case. In this paper, we first review and study these two modeling methods for various DC-DC converters operating in the discontinuous conduction mode (DCM). We also streamline the general model-deriving processes for DC-DC converters, and test and compare the accuracy of these two methods under various conditions. Finally, we provide a selection strategy for a high-accuracy modeling method for different DC-DC converters operating in DCM and verified by simulations, which revealed necessary and beneficial for designing a more accurate DCM closed-loop controller for DC-DC converters, thus achieving better stability and transient response.

scholarly journals Quantifying the redshift space distortion of the bispectrum I: primordial non-Gaussianity

2020 ◽  
Vol 493 (1) ◽  
pp. 594-602 ◽  
Author(s):  
Somnath Bharadwaj ◽  
Arindam Mazumdar ◽  
Debanjan Sarkar
Keyword(s):  
Spherical Harmonics ◽  
Real Space ◽  
Line Of Sight ◽  
Multipole Moments ◽  
Distortion Parameter ◽  
Redshift Surveys ◽  
Space Distortion ◽  
Zero Values ◽  
Parallel Approximation ◽  
Analytical Expressions

ABSTRACT The anisotropy of the redshift space bispectrum contains a wealth of cosmological information. This anisotropy depends on the orientation of three vectors $\boldsymbol {k_1},\boldsymbol {k_2},\boldsymbol {k_3}$ with respect to the line of sight. Here, we have decomposed the redshift space bispectrum in spherical harmonics which completely quantify this anisotropy. To illustrate this, we consider linear redshift space distortion of the bispectrum arising from primordial non-Gaussianity. In the plane-parallel approximation, only the first four even ℓ multipoles have non-zero values, and we present explicit analytical expressions for all the non-zero multipoles, that is, upto ℓ = 6 and m = 4. The ratio of the different multipole moments to the real-space bispectrum depends only on β1 the linear redshift distortion parameter and the shape of the triangle. Considering triangles of all possible shapes, we have studied how this ratio depends on the shape of the triangle for β1 = 1. We have also studied the β1 dependence for some of the extreme triangle shapes. If measured in future, these multipole moments hold the potential of constraining β1. The results presented here are also important if one wishes to constrain fNL using redshift surveys.

Ear biometric verification approach based on morphological and geometric invariants

2020 ◽  
Vol 20 (3) ◽  
pp. 1479
Author(s):  
Wurood A. Jbara
Keyword(s):  
Feature Extraction ◽  
Edge Detection ◽  
Main Idea ◽  
High Accuracy ◽  
Geometric Invariants ◽  
Biometric Verification ◽  
Accuracy Level ◽  
Image Capturing ◽  
Verification Process ◽  
Biometric Model

<p>Biometric verification based on ear features is modern filed for scientific research. As known, there are many biometric identifiers that can identify people such as fingerprints, iris and speech. In this paper, the focus is placed on the ear biometric model in order to verifying the identity of persons. The main idea is based on used the moments as ear feature extractors. The proposed approach included some operations as follow: image capturing, edge detection, erosion, feature extraction, and matching. The proposed approach has been tested using many images of the ears with different states. Experimental results using several trails verified that the proposed approach is achieved high accuracy level over a wide variety of ear images. Also, the verification process will be completed by matching query ear image with ear images that kept in database during real time.</p>

scholarly journals ON COUPLED PROBLEMS FOR VISCOUS FLOW IN EXTERIOR DOMAINS

1998 ◽  
Vol 08 (04) ◽  
pp. 657-684 ◽  
Author(s):  
M. FEISTAUER ◽  
C. SCHWAB
Keyword(s):  
Stokes Flow ◽  
Stokes System ◽  
Stokes Problem ◽  
Large Data ◽  
Transmission Conditions ◽  
Navier Stokes ◽  
Coupled Problems ◽  
Exterior Domains ◽  
Existence Of A Solution ◽  
Coupled Problem

The use of the complete Navier–Stokes system in an unbounded domain is not always convenient in computations and, therefore, the Navier–Stokes problem is often truncated to a bounded domain. In this paper we simulate the interaction between the flow in this domain and the exterior flow with the aid of a coupled problem. We propose in particular a linear approximation of the exterior flow (here the Stokes flow or potential flow) coupled with the interior Navier–Stokes problem via suitable transmission conditions on the artificial interface between the interior and exterior domains. Our choice of the transmission conditions ensures the existence of a solution of the coupled problem, also for large data.

A Parallel Computational Model for Three-Dimensional, Thermo-Mechanical Stokes Flow Simulations of Glaciers and Ice Sheets

2014 ◽  
Vol 16 (4) ◽  
pp. 1056-1080 ◽  
Author(s):  
Wei Leng ◽  
Lili Ju ◽  
Max Gunzburger ◽  
Stephen Price
Keyword(s):  
Finite Element ◽  
Computational Model ◽  
Stokes Flow ◽  
Stokes Problem ◽  
Three Dimensional ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Iterative Solution ◽  
Element Model ◽  
High Order

AbstractThis paper focuses on the development of an efficient, three-dimensional, thermo-mechanical, nonlinear-Stokes flow computational model for ice sheet simulation. The model is based on the parallel finite element model developed in [14] which features high-order accurate finite element discretizations on variable resolution grids. Here, we add an improved iterative solution method for treating the nonlinearity of the Stokes problem, a new high-order accurate finite element solver for the temperature equation, and a new conservative finite volume solver for handling mass conservation. The result is an accurate and efficient numerical model for thermo-mechanical glacier and ice-sheet simulations. We demonstrate the improved efficiency of the Stokes solver using the ISMIP-HOM Benchmark experiments and a realistic test case for the Greenland ice-sheet. We also apply our model to the EISMINT-II benchmark experiments and demonstrate stable thermo-mechanical ice sheet evolution on both structured and unstructured meshes. Notably, we find no evidence for the “cold spoke” instabilities observed for these same experiments when using finite difference, shallow-ice approximation models on structured grids.

Calculation of Head-Related Transfer Functions for Arbitrary Field Points Using Spherical Harmonics Decomposition

2012 ◽  
Vol 98 (1) ◽  
pp. 72-82 ◽  
Author(s):  
Martin Pollow ◽  
Khoa-Van Nguyen ◽  
Olivier Warusfel ◽  
Thibaut Carpentier ◽  
Markus Müller-Trapet ◽  
...  
Keyword(s):  
Spherical Harmonics ◽  
Transfer Functions ◽  
Arbitrary Field

scholarly journals Subject-verb Word Order in Narratives in Swedish by Immersion and Non-immersion Students

2021 ◽  
Vol 12 (5) ◽  
pp. 641-653
Author(s):  
Eeva-Liisa Nyqvist
Keyword(s):  
Word Order ◽  
High Accuracy ◽  
Subordinate Clauses ◽  
Accuracy Level ◽  
L2 Learners

The Swedish V2 word order has been considered a notorious source of difficulty for L2 learners due to its strict rules. This study explores subject-verb word order in texts written in Swedish by 12-year-old and 15-year-old Finnish-speaking immersion students and by 16-year-old non-immersion students. Although the L1 of the informants lacks obligatory inversion, the analyses show that informants in all three groups have reached a high accuracy level in several aspects of word order in main clauses. However, the informants struggle with challenges that are similar to those detected in previous research: inversion is omitted in its obligatory occasions in main clauses but simultaneously overused in subordinate clauses where word order is canonical. In main clauses, the challenges focus on declarative main clauses with inversion. In subordinate clauses, on the contrary, the challenges focus on questions.

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