scholarly journals Assessing the stochastic error of acoustic scattering matrices using linear methods

2018 ◽  
Vol 10 (4) ◽  
pp. 380-392 ◽  
Author(s):  
Luck Peerlings ◽  
Friedrich Bake ◽  
Susann Boij ◽  
Hans Bodén
Keyword(s):  
Uncertainty Analysis ◽  
Linear Method ◽  
Plane Waves ◽  
Acoustic Scattering ◽  
Higher Order ◽  
Condition Numbers ◽  
Matrix Perturbation ◽  
Stochastic Error ◽  
Scattering Matrices

To be able to compare the measured scattering matrices with model predictions, the quality of the measurements has to be known. Uncertainty analyses are invaluable to assess and improve the quality of measurement results in terms of accuracy and precision. Linear analyses are widespread, computationally fast and give information of the contribution of each error source to the overall measurement uncertainty; however, they cannot be applied in every situation. The purpose of this study is to determine if linear methods can be used to assess the quality of acoustic scattering matrices. The uncertainty in measured scattering matrices is assessed using a linear uncertainty analysis and the results are compared against Monte-Carlo simulations. It is shown that for plane waves, a linear uncertainty analysis, applied to the wave decomposition method, gives correct results when three conditions are satisfied. For higher order mode measurements, the number of conditions that have to be satisfied increases rapidly and the linear analysis becomes an unsuitable choice to determine the uncertainty on the scattering matrix coefficients. As the linear uncertainty analysis is most suitable for the plane wave range, an alternative linear method to assess the quality of the measurements is investigated. This method, based on matrix perturbation theory, gives qualitative information in the form of partial condition numbers and the implementation is straightforward. Using the alternative method, the measurements of higher order modes are analyzed and the observed difference in the measured reflection coefficients for different excitation conditions is explained by the disparity in modal amplitudes.

scholarly journals Effect of the turning characteristics of underfloor wheel lathes on the evolution of wheel polygonisation

2018 ◽  
Vol 233 (5) ◽  
pp. 479-488 ◽  
Author(s):  
Dabin Cui ◽  
Boyang An ◽  
Paul Allen ◽  
Ruichen Wang ◽  
Ping Wang ◽  
...  
Keyword(s):  
Fourth Order ◽  
High Speed ◽  
Higher Order ◽  
Ride Quality ◽  
Sustained Use ◽  
High Speed Trains ◽  
Cut Quality ◽  
Multiple Unit ◽  
Component Failures

During both running and wheel cut operations, wheels of railway vehicles and the friction rollers that support and drive the wheelset on a typical wheel cut lathe are subject to wear and hence are likely to develop out-of-round characteristics after sustained use. The resulting out-of-round wheels can significantly affect the ride quality and can potentially increase the incidence of fatigue-related component failures due to the resulting higher intensity loading cycles. Furthermore, the corresponding out-of-round characteristics of the lathe's friction rollers will continue to degrade the subsequent cut quality of wheels. For the analysis of the out-of-round characteristics caused by an underfloor wheel lathe used for the high-speed trains in China, a mathematical model based on a typical electric multiple unit (EMU) vehicle's wheelsets and their interactions with the wheel lathe friction rollers was established. Factors influencing the cut quality of the wheels, including the number of cuts, eccentricity forms of the friction rollers and the longitudinal spacing of the two rollers, have been analysed. The results show that two cuts can effectively remove the higher order polygon on the wheel surface. The eccentricity and phase angle of the friction rollers have no influence on the cut quality of higher order polygons, whereas they are the primary cause for the fourth-order polygons. The severity of the fourth-order polygon depends on the level and the phase of the eccentricity of the friction rollers. The space of the two rollers can also significantly affect the cut quality. Obtaining the theoretical and practical value for the maintenance of polygonised wheels using the underfloor lathe is the main outcome of this study.

scholarly journals INSTRUMEN TES HIGHER ORDER THINKING SKILL PADA MATERI KIMIA SMA

2020 ◽  
Vol 4 (2) ◽  
pp. 135-149
Author(s):  
Etrie Jayanti
Keyword(s):  
Field Test ◽  
Higher Order Thinking ◽  
Higher Order ◽  
Difficulty Level ◽  
Development Research ◽  
Thinking Skill ◽  
Self Evaluation ◽  
Skill Test ◽  
Test Instrument

Abstract: According to demands of curriculum 2013, assessment carried out on school should have led to increasing of higher order thinking skill. The lack of availability of questions are specifically designed to develop student’s higher order thinking skill causes students are not really proficient in solving higher order thinking skill questions. This study was research and development research purposing to determine development steps and quality of higher order thinking skill test instrument in one of high schools chemistry topic, i.e. colloid. The process of developing a higher order thinking skill test instrument used a formative research designed by Tessmer through 4 stages, namely: preliminary, self-evaluation, prototyping (expert reviews, one-to-one and small group) and field test. The data were obtained from the results of filling out validation sheets by expert reviews, questionnaires filled out by students, and test/trial of higher order thinking skill test instrument on students. The results of the development were categorically valid logically and empirically. The reliability of the test instrument was 0,65 with the high category. The item’s difficulty level was in the medium category. Six questions had good distinguishing power and one question had enough distinguishing power. The higher order thinking skill of students were in excellent, good, adequate, lacking and very poor categories respectively: 15,14%;  12,12%;  42,42%;  24,24%;  6,06%.

scholarly journals PENERAPAN MODEL PROBLEM SOLVING DALAM MENINGKATKAN KEMAMPUAN HOT (HIGHER ORDER THINKING) SISWA SDN BANYU LANDAS

Vidya Karya ◽  
2017 ◽  
Vol 31 (1) ◽  
Author(s):  
Silvia Uyani
Keyword(s):  
Problem Solving ◽  
Model Problem ◽  
Higher Order Thinking ◽  
Thinking Skills ◽  
Achievement Test ◽  
Higher Order ◽  
Research Subject ◽  
Higher Order Thinking Skills ◽  
Student Activity

Abstract: This research relates to the implementation of Problem Solving model in Banyu Landas Elementary School. The research objective is to increase students’ Higher Order Thingking Skills (HOTS). The research was conducted by using classroom action research (CAR) method through 2 cycles. Ten six class students of SDN Banyu Landas were used as research subject. The data collection used obeservation sheets and HOT oriented achievement test. The data were qualitatively analyzed with percentage technique. The result of research stated that (1) students’ Higher Order Thingking Skills (HOTS) increased from analysis skills 77,85% in the first cycle up to  synthesys skills 86,58% in the end of second cycle (2) the quality of teacher’s activity increased  from 58,41% in the first cycle  up to 71,14% in the end of second cycle; (2) students’ activity incresed  from 68,39% in the first cycle  up to 70,10% in the end of second cycle.              Keywords: Higher Order Thinking Skills, teacher activity, student activity , Problem Solving. Abstrak: Penelitian ini berkenaan dengan penerapan model Problem Solving di SDN Banyu Landas. Tujuan penelitian adalah untuk meningkatkan kemampuan berpikir tingkt tinggi (Higher Order Thingking Skill/HOT) siswa. Penelitian ini dilakukan dengan menggunakan rancangan penelitian tindakan kelas dalam 2 siklus. Subyek penelitian adalah 10 orang siswa kelas VI SDN Banyu Landas. Pengumpulan data menggunakan lembar observasi dan tes hasil belajar berorientasi HOT. Data dianalisis secara kualitatif dengan teknik persentase. Hasil penelitian menunjukkan bahwa: (1) kemampuan berpikir tingkat tinggi (Higher Order Thingking Skill/HOT) peserta didik meningkat dari kemampuan analisis 77,85% pada awal siklus I menjadi kemampuan sintesis 86,58% pada akhir siklus II kualitas, (2) aktivitas guru meningkat dari 58,41% pada siklus 1 menjadi menjadi 71,14%  pada siklus 2; (2) aktivitas siswa meningkat dari 68,39% pada siklus 1 menjadi 70,10% pada siklus II. Kata kunci: HOT (Higher Order Thinking) skills, aktivitas guru, aktivitas siswa, Problem Solving

Fundamentals of Higher Order Neural Networks for Modeling and Simulation

2013 ◽  
pp. 103-133 ◽  
Author(s):  
Madan M. Gupta ◽  
Ivo Bukovsky ◽  
Noriyasu Homma ◽  
Ashu M. G. Solo ◽  
Zeng-Guang Hou
Keyword(s):  
Neural Networks ◽  
Modeling And Simulation ◽  
Learning Algorithm ◽  
Nonlinear Approximation ◽  
Higher Order ◽  
Higher Order Neural Networks ◽  
High Dynamic ◽  
Input Variables ◽  
Continuous Dynamic

In this chapter, the authors provide fundamental principles of Higher Order Neural Units (HONUs) and Higher Order Neural Networks (HONNs) for modeling and simulation. An essential core of HONNs can be found in higher order weighted combinations or correlations between the input variables and HONU. Except for the high quality of nonlinear approximation of static HONUs, the capability of dynamic HONUs for the modeling of dynamic systems is shown and compared to conventional recurrent neural networks when a practical learning algorithm is used. In addition, the potential of continuous dynamic HONUs to approximate high dynamic order systems is discussed, as adaptable time delays can be implemented. By using some typical examples, this chapter describes how and why higher order combinations or correlations can be effective for modeling of systems.

scholarly journals Higher Order Thinking in Education

2013 ◽  
Vol 2 ◽  
pp. 5-10 ◽  
Author(s):  
Bhawani Prasad Mainali
Keyword(s):  
Quality Of Life ◽  
Higher Order Thinking ◽  
Thinking Skills ◽  
Higher Order ◽  
Educational Context ◽  
Higher Order Thinking Skills

The purpose of this article is to focus on pedagogical process that can be utilized to develop in students higher order thinking skills considered necessary for quality of life. Moreover, it also describes the rationale of developing higher order thinking skills and its implications in educational context. Academic Voices, Vol. 2, No. 1, 2012, Pages 5-10 DOI: http://dx.doi.org/10.3126/av.v2i1.8277

Acoustic Scattering Cross Sections of Smart Obstacles: A Case Study

2011 ◽  
Vol 10 (3) ◽  
pp. 672-694
Author(s):  
Lorella Fatone ◽  
Maria Cristina Recchioni ◽  
Francesco Zirilli
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Space Shuttle ◽  
Scattering Problem ◽  
Plane Waves ◽  
Acoustic Scattering ◽  
Scattering Cross Section ◽  
Scattering Cross ◽  
Scattering Cross Sections

AbstractAcoustic scattering cross sections of smart furtive obstacles are studied and discussed. A smart furtive obstacle is an obstacle that, when hit by an incoming field, avoids detection through the use of a pressure current acting on its boundary. A highly parallelizable algorithm for computing the acoustic scattering cross section of smart obstacles is developed. As a case study, this algorithm is applied to the (acoustic) scattering cross section of a “smart” (furtive) simplified version of the NASA space shuttle when hit by incoming time-harmonic plane waves, the wavelengths of which are small compared to the characteristic dimensions of the shuttle. The solution to this numerically challenging scattering problem requires the solution of systems of linear equations with many unknowns and equations. Due to the sparsity of these systems of equations, they can be stored and solved using affordable computing resources. A cross section analysis of the simplified NASA space shuttle highlights three findings: i) the smart furtive obstacle reduces the magnitude of its cross section compared to the cross section of a corresponding “passive” obstacle; ii) several wave propagation directions fail to satisfactorily respond to the smart strategy of the obstacle; iii) satisfactory furtive effects along all directions may only be obtained by using a pressure current of considerable magnitude. Numerical experiments and virtual reality applications can be found at the website: http://www.ceri.uniromal.it/ceri/zirilli/w7.

Higher‐order moveout spectra

Geophysics ◽  
1979 ◽  
Vol 44 (7) ◽  
pp. 1193-1207 ◽  
Author(s):  
Bruce T. May ◽  
Donald K. Straley
Keyword(s):  
Fourth Order ◽  
Seismic Reflection ◽  
Order Term ◽  
Higher Order ◽  
Second Order ◽  
Equation Modeling ◽  
Fourth Order Term ◽  
Higher Order Terms ◽  
Velocity Spectra

Higher‐order terms in the generalized seismic reflection moveout equation are usually neglected, resulting in the familiar second‐order, or hyperbolic, moveout equation. Modeling studies show that the higher‐order terms are often significant, and their neglect produces sizable traveltime residuals after correction for moveout in such cases as kinked‐ray models. Taner and Koehler (1969) introduced velocity spectra for estimating stacking velocity defined on the basis of second‐order moveout. Through the use of orthogonal polynomials, an iterative procedure is defined that permits computation of fourth‐order moveout spectra while simultaneously upgrading the previously computed, second‐order spectra. Emphasis is placed on the fourth‐order term, but the procedure is general and can be expanded to higher orders. When used with synthetic and field recorded common‐midpoint (CMP) trace data, this technique produces significant improvements in moveout determination affecting three areas: (1) resolution and interpretability of moveout spectra, (2) quality of CMP stacked sections, and (3) computation of velocity and depth for inverse modeling.

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