Distortion Theory Research Articles

RDT study of non-isentropic compressible homogeneous sheared turbulence

The objective of this work is to formulate governing equations for non-isentropic compressible homogeneous sheared turbulence using rapid distortion theory (RDT). Furthermore, we develop a code able to solve these linearized equations. It is possible for this code to address both kinematic and thermal properties i.e. mass density, temperature variances, mass and heat fluxes which are the specific properties of compressible turbulence. RDT code resolves directly evolution equations of two-point spectral correlation. The results of our RDT code are compared with the direct numerical simulation data of Simone et al (1997) and have demonstrated good agreement. The comparisons concern different contributions such as the kinetic turbulent energy, the temporal energy growth rate, the non-dimensional production term, the solenoidal and dilatational contributions of non-dimensional production and the sum of pressure-dilatation terms and rate of kinetic energy dissipation, scaled by the production term. Some results concerning the polytropic coefficient and the energy partition parameter are presented and discussed.

Automated map projection selection for GIS

ABSTRACTThe selection of an appropriate map projection has a fundamental impact on the visualization and analysis of geographic information. Distortion is inevitable and the decision requires simultaneous consideration of several different factors; a process which can be confusing for many cartographers and GIS users. The last few decades have seen numerous attempts to create automated map projection selection solutions based on traditional classification and selection guidelines, but there are no existing tools directly accessible to users of GIS software when making projection selection decisions. This paper outlines key elements of projection selection and distortion theory, critically reviews the previous solutions, and introduces a new tool developed for ESRI’s ArcGIS, employing an original selection method tailored to the specific purpose and geographical footprint characteristics of a GIS project. The tool incorporates novel quantitative projection distortion measures which are currently unavailable within existing GIS packages. Parameters are optimized for certain projections to further reduce distortions. A set of candidate projected coordinate systems are generated that can be applied to the GIS project; enabling a qualitative visual assessment to facilitate the final user selection. The proposed tool provides a straightforward application which improves understanding of the projection selection process and assists users in making more effective use of GIS.

Extending information maximization from a rate-distortion perspective

In this paper, we propose a new interpretation of the information maximization method (InfoMax) from a perspective of the rate distortion theory. We show that under specific conditions, InfoMax is equivalent to the minimization of a compression rate under the constraint of zero distortion. Zero distortion, or equivalently, zero reconstruction error between the input and its reconstruction, does not provide meaningful solutions in many cases. Based on the new interpretation, we extend InfoMax to be able to deal with non-zero distortion and also to learn under/over-complete representations. Experimental results on synthetic as well as real data show the effectiveness of our method.

An analytic solution for gust–cascade interaction noise including effects of realistic aerofoil geometry

This paper presents an analytic solution for the sound generated by rotor–stator interaction for aerofoils with small camber and thickness subject to a background flow with small angle of attack. The interaction is modelled as a convected, unsteady vortical or entropic gust incident on an infinite rectilinear cascade of staggered aerofoils in a background flow that is uniform far away from the cascade. Applying rapid distortion theory (RDT) and transforming to an orthogonal coordinate system reduces the cascade of aerofoils to a cascade of flat plates. By seeking a perturbation expansion in terms of the disturbance of the background flow from uniform flow, leading- and first-order governing equations and boundary conditions are obtained for the acoustic potential. The system is then solved analytically using the Wiener–Hopf method. The resulting expression is inverted to give the acoustic potential function in the entire domain, i.e. a solution to the inhomogeneous convected Helmholtz equation with inhomogeneous boundary conditions in a cascade geometry. The solution significantly extends previous analytical work that is restricted to flat plates or only calculates the far-upstream radiation, and as such can give insight into the role played by blade geometry on the acoustic field upstream, downstream and in the important inter-blade region of the cascade. This new solution is validated against solutions that only account for flat plates at zero angle of attack. Various aeroacoustic results, including the scattered pressure, unsteady lift and sound power output, are discussed for a range of geometries and angles of attack.

תיאוריית העיוות והחיסול בספרות העברית הציונית החדשה The theory of distortion and eradication in modern Zionist Hebrew literature

כותרת זו יכולה להיות משהו מוזר או פרדוקסלי, כי זה לא נדיר או טבעי לחפש אלימות בספרות! . או תהיה הספרות כלי רצח! , באמצעות היצירה של סופרים ומשוררים ליצור אלימות ותזונה וסנגור לה. הספרות העברית הציונית שייכת למאה ה -20. זוהי הספרות היחידה בין הספרותיות של עולם, אשר מפרסמת את הגזענות שלה ומתגאה בבגידה בתפקידה האנושי. ספרות זו רוצה להיות מדיום של טרור ושליטה. ואמצעי טרור בידי רוצחים והרפתקנים. ספרות זו מאמינה שאין פתרון לבעיה היהודית, רק הישות הציונית תחליף ,על חורבות פלסטין והפלסטינים. יצירה ספרותית רחבת היקף שרויה באלימות ובגזענות . מדובר בספרות שנוצרה על ידי סופרים ,משוררים, הוגים, פוליטיקאים ואנשי דת ציוניים. כמו אורל אופק, יצחק שדה, קולדה מאיר, משה סימלנסקי, עמוס עוז, לאון אוריס, אורי צבי גרינברג,ג.כהן, , מרדכי טביב, ויוסף אריכא. This title may have something strange or paradoxical; it is unusual or natural to look for violence in literature, or that literature is a tool for killing through the contribution of writers and poets in generating, feeding or advocating violence. The Zionist literature belongs to the 20th century, is almost the only literature among the etiquette of peoples, which professes racism and boasts of betraying its human role, and wants to be a vehicle for terrorism domination. It also tends to be a means in the hands of killers and adventurers. Writers of this Literature show that no solution to the Jewish problem is only by Zionist presence to replace the Palestinian presence and to build the state of Israel on the ruins of Palestine and Palestinians. Many of such statements and allegations that are full of violence, racism, and contempt of facts carried and echoed by writers, poets, intellectuals, politicians and clergy Zionists, such as Orel Ofek, Yitzhak Chade, Kolda Meir, Moshe Simlansky, Amos Oz, Leon Oris, Uri Zvi Greenberg, Cohen, Mordecai the doctor, and Joseph Reza.

Variations on anchoring: Sequential anchoring revisited

AbstractThe anchoring effect, the assimilation of judgment toward a previously considered value, has been shown using various experimental paradigms. We used several variations of the sequential anchoring paradigm, in which a numeric estimate influences a subsequent numeric estimate on the same scale, to investigate how anchoring is influenced by multiple anchors, a comparison question, and by a newly introduced debiasing procedure. We replicated the anchoring effect using the sequential anchoring paradigm and showed that, when two anchors of opposite directions are presented, the second seems to influence a subsequent judgment somewhat more. A comparison of a target with another object before the numerical estimate was not sufficient to elicit anchoring, but it might have increased the sequential anchoring effect. The debiasing procedure, based on providing reference points on the numerical scale, prevented the sequential anchoring effect. The results are in accord with the scale distortion theory of anchoring, but other theories may also account for the observed findings with additional adjustments.

Rapid distortion theory on transversely sheared mean flows of arbitrary cross-section

This paper is concerned with rapid distortion theory on transversely sheared mean flows that (among other things) can be used to analyse the unsteady motion resulting from the interaction of a turbulent shear flow with a solid surface. It expands on a previous analysis of Goldsteinet al. (J. Fluid Mech., vol. 824, 2017, pp. 477–512) that uses a pair of conservation laws to derive upstream boundary conditions for planar mean flows and extends these findings to transversely sheared flows of arbitrary cross-section. The results, which turn out to be quite general, are applied to the specific case of a round jet interacting with the trailing edge of a flat plate and are used to calculate the radiated sound field, which is then compared with experimental data taken at the NASA Glenn Research Center.

Sound generation due to the interaction of turbulence with surfaces embedded in transversely sheared flow

This paper reviews the application of Rapid Distortion Theory (RDT) on transversely shear mean flows to the prediction of sound generated from solid surfaces imbedded in turbulent shear flows. This phenomenon is relevant to the so-called installation noise problem which has received considerable attention in recent years. A few representative results from applications that have appeared in the literature are also presented. This article is part of the theme issue 'Frontiers of aeroacoustics research: theory, computation and experiment'.

Markov Information Bottleneck to Improve Information Flow in Stochastic Neural Networks

While rate distortion theory compresses data under a distortion constraint, information bottleneck (IB) generalizes rate distortion theory to learning problems by replacing a distortion constraint with a constraint of relevant information. In this work, we further extend IB to multiple Markov bottlenecks (i.e., latent variables that form a Markov chain), namely Markov information bottleneck (MIB), which particularly fits better in the context of stochastic neural networks (SNNs) than the original IB. We show that Markov bottlenecks cannot simultaneously achieve their information optimality in a non-collapse MIB, and thus devise an optimality compromise. With MIB, we take the novel perspective that each layer of an SNN is a bottleneck whose learning goal is to encode relevant information in a compressed form from the data. The inference from a hidden layer to the output layer is then interpreted as a variational approximation to the layer’s decoding of relevant information in the MIB. As a consequence of this perspective, the maximum likelihood estimate (MLE) principle in the context of SNNs becomes a special case of the variational MIB. We show that, compared to MLE, the variational MIB can encourage better information flow in SNNs in both principle and practice, and empirically improve performance in classification, adversarial robustness, and multi-modal learning in MNIST.

The rapid distortion of two-way coupled particle-laden turbulence

In this study, we address the modification of sheared turbulence by dispersed inertial particles. The preferential sampling of the straining regions of the flow by inertial particles in turbulence leads to an inhomogeneous distribution of particles. The strong gravitational loading exerted by the highly concentrated regions results in anisotropic alteration of turbulence at small scales in the direction of gravity. These effects are investigated in a rapid distortion theory (RDT) extended for two-way coupled particle-laden flows. To make the analysis tractable, we assume that particles have small but non-zero inertia. In the classical results for single-phase flows, the RDT assumption of fast shearing compared to the turbulence time scales leads to the distortion and shear-induced production of turbulence. In particle-laden turbulence, the coupling between the two phases under rapid shearing induces number density fluctuations that convert gravitational potential energy to turbulent kinetic energy and modulate the turbulence spectrum in a manner that increases with mass loading. Turbulence statistics obtained from RDT are compared with Euler–Lagrange simulations of homogeneously sheared particle-laden turbulence.

ANALISA TEGANGAN POROS MOBIL LISTRIK TARSIUS X3 MENGGUNAKAN SOFTWARE

The development of the automotive industri in Indonesia that uses electrical energy sources is still a competition in the environment of college students. One of them is the Tarsius X3 electric car that has 2 kilowatts of power with a rear drive system that is used to transfer power from the electric motor to the wheels. Development, design and analysis of the drive shaft using software, aims to determine the surface tension and deformation that occurs on the shaft. Stress analysis uses the theory of energy distortion (von mises). Loading on the shaft is based on, electrical motor torsion, the weighing of car and stress of the shaft material permits by conducting tensile testing of the ASTM E-8 method as input for simulating CAD software (Inventor). The software simulation results show that the von mises maximum stress occurs at 162.463 MPa and the minimum stress occurs at 0.0011 MPa . The maximum deformation occurs at 4.74 x 10 -2 mm and a minimum of 0 mm. The stress and deformation that occur is still at the safety factor limit of 3.83 at under static conditions. Keywords: Shaft, Von Mises Stress, Safety Factor, Deformation

The effect of an unsteady flow incident on an array of circular cylinders

In this paper we investigate the effect of an inhomogeneous and unsteady velocity field incident on an array of rigid circular cylinders arranged within a circular perimeter (diameter $D_{G}$) of varying solid fraction $\unicode[STIX]{x1D719}$, where the unsteady flow is generated by placing a cylinder (diameter $D_{G}$) upwind of the array. Unsteady two-dimensional viscous simulations at a moderate Reynolds number ($Re=2100$) and also, as a means of extrapolating to a flow with a very high Reynolds number, inviscid rapid distortion theory (RDT) calculations were carried out. These novel RDT calculations required the circulation around each cylinder to be zero which was enforced using an iterative method. The two main differences which were highlighted was that the RDT calculations indicated that the tangential velocity component is amplified, both, at the front and sides of the array. For the unsteady viscous simulations this result did not occur as the two-dimensional vortices (of similar size to the array) are deflected away from the boundary and do not penetrate into the boundary layer. Secondly, the amplification is greater for the RDT calculations as for the unsteady finite Reynolds number calculations. For the two highest solid fraction arrays, the mean flow field has two recirculation regions in the near wake of the array, with closed streamlines that penetrate into the array which will have important implications for scalar transport. The increased bleed through the array at the lower solid fraction results in this recirculation region being displaced further downstream. The effect of inviscid blocking and viscous drag on the upstream streamwise velocity and strain field is investigated as it directly influences the ability of the large coherent structures to penetrate into the array and the subsequent forces exerted on the cylinders in the array. The average total force on the array was found to increase monotonically with increasing solid fraction. For high solid fraction $\unicode[STIX]{x1D719}$, although the fluctuating forces on the individual cylinders is lower than for low $\unicode[STIX]{x1D719}$, these forces are more correlated due to the proximity of the cylinders. The result is that for mid to high solid fraction arrays the fluctuating force on the array is insensitive to $\unicode[STIX]{x1D719}$. For low $\unicode[STIX]{x1D719}$, where the interaction of the cylinders is weak, the force statistics on the individual cylinders can be accurately estimated from the local slip velocity that occurs if the cylinders were removed.

Double variational principle for mean dimension

We develop a variational principle between mean dimension theory and rate distortion theory. We consider a minimax problem about the rate distortion dimension with respect to two variables (metrics and measures). We prove that the minimax value is equal to the mean dimension for a dynamical system with the marker property. The proof exhibits a new combination of ergodic theory, rate distortion theory and geometric measure theory. Along the way of the proof, we also show that if a dynamical system has the marker property then it has a metric for which the upper metric mean dimension is equal to the mean dimension.

Mutual Information, the Linear Prediction Model, and CELP Voice Codecs

We write the mutual information between an input speech utterance and its reconstruction by a code-excited linear prediction (CELP) codec in terms of the mutual information between the input speech and the contributions due to the short-term predictor, the adaptive codebook, and the fixed codebook. We then show that a recently introduced quantity, the log ratio of entropy powers, can be used to estimate these mutual informations in terms of bits/sample. A key result is that for many common distributions and for Gaussian autoregressive processes, the entropy powers in the ratio can be replaced by the corresponding minimum mean squared errors. We provide examples of estimating CELP codec performance using the new results and compare these to the performance of the adaptive multirate (AMR) codec and other CELP codecs. Similar to rate distortion theory, this method only needs the input source model and the appropriate distortion measure.

Turbulence velocity spectra and intensities in the inflow of a turbine rotor

The changes in spectra and intensities of the streamwise component of turbulent velocity are calculated in the inflow of a turbine rotor. The flow is initially calculated in the limit when the turbulence is of small scale compared with the rotor diameter. Rapid distortion theory (RDT), Batchelor & Proudman (Q. J. Mech. Appl. Maths, vol. 7 (1), 1954, pp. 83–103) (BP), for small-scale turbulence is combined with the effect of the fluctuating potential flow field on the turbulence caused by the direct interaction of the incident turbulence with the rotor as a sheet of resistance. A second computation is then carried out for turbulence of larger length scale. The results of the calculations are compared with velocity measurements in the inflow of both a commercial wind turbine and a tidal turbine rotor.

A note on rational inattention and rate distortion theory

In this teaching note, we discuss the relation between rational inattention and a major branch of information theory called “rate distortion theory.” Focusing on methods, we translate tools from rate distortion theory into the language of rational inattention. These tools provide an alternative, more primitive, approach to the study of optimal attention allocation.

Similarity, multiple estimations, and the anchoring effect

This paper compares the Selective Accessibility and Scale Distortion theories of anchoring as explanations for anchoring tasks involving (1) perceived dissimilarity between comparison and estimation objects and (2) successive estimation tasks. We begin by describing the two theories of anchoring and what each would predict for these conditions. Two studies are presented in which multiple estimates are made following a single comparison task and the effect sizes of these estimates are correlated to operationalizations of similarity. In the first study, the stimuli varied with respect to how well they fit within an existing category reasonably familiar to the participant population: aircraft. In the second study, the stimuli varied with respect to external features that did not define the category: the brand and location of hotels. In both studies, we find that the anchoring effect size has a positive correlation with the semantic similarity between the comparison and estimation objects, a finding consistent with Selective Accessibility.

Theory of Distortions and Welfare as the Backbone of the WTO: If We Lose the Form, Do We Lose the Essence?

The Project asks us to work on the presumption that the WTO is at the crossroads and may either survive after significant reforms or cease to exist. This concept paper does not examine the specific challenges that the WTO is currently facing or the various reform proposals. Instead, the paper revisits the underlying rationale for the need for the/a multilateral trading system and underscores the significance of the “Theory of Distortions and Welfare” to the proper functioning of the WTO or its successor. The paper submits that regardless of the fate of the WTO, anti-protectionism, collective rule-making and judicial interpretation and enforcement will remain at the core of international trade regulation. The fundamental function of the/a multilateral trading system will continue to be disciplining the choice of trade policies and policy instruments. As the backbone of the system, the “Theory of Distortions and Welfare” provides an effective mechanism for encouraging the use of economically efficient policy instruments without impairing governments’ capacity to pursue chosen non-protectionist policy objectives.

Design and Experimental Verification of a 1/20 Scale Model of Quayside Container Crane Using Distortion Theory

The scale model is an effective method to research the performance of quayside container crane (QCC) under the seismic condition, but the model distortion usually exists in the similar design process which leads to the incomplete similarity between the scale model and prototype. In this investigation, the distortion theory and the prediction coefficient correction method are used to upgrade the quality of 1/20 QCC scale model and, then, the seismic response of the QCC prototype is obtained from the shake table scale model test. In the first step, the similarity ratio of the 1/20 QCC scale model is calculated by the similitude law and the size of scale model is obtained from the similarity constants. In the second step, the bending stiffness is selected and determined as the distortion term and, then, the relationship between the distortion coefficient and the prediction coefficient is obtained by the finite element prediction coefficient method. Furthermore, the three different scale models are manufactured and tested in the shake table experiment under different seismic conditions. It is found that the experimental test results are consistent with the numerical simulation results of the QCC prototype. It can be concluded that the QCC scale model can be used to predict the performance of the prototype under the different seismic conditions after corrected by distortion theory, and the distortion theory is an effective method to solve the incomplete similarity between the scale model and prototype.

Theories of Poverty: A Critical Review

The study reviewed literature on the theories of poverty. The theories reviewed included theory of individual deficiencies, theory of cultural beliefs, theory of economic, political and social distortions, theory of geographical disparities, and theory of cumulative and cyclical dependencies. The theories were analysed, criticised and measures that will bring the poor out of poverty were recommended. Some of the recommended solutions included: encouraging the poor to embrace self-help strategies, replacing the culture with one that encourages hard work and investment, changing the system for the better, improving infrastructure and local industries competitiveness, and developing comprehensive programmes that will help the poor to be self-sufficient. Key words: Poverty, Cultural beliefs, Individual deficiencies, Geographical disparities, Economic, political, and structural f actors, psychological theories, sociological theories. DOI : 10.7176/JPID/48-08