The Mechanisms of Determining Shock Locations in One and Two Dimensional Transonic Flows

1986 ◽  
Vol 53 (1) ◽  
pp. 203-205 ◽  
Author(s):  
D. Nixon ◽  
Y. Liu
Keyword(s):  
Shock Wave ◽  
Transonic Flow ◽  
Two Dimensions ◽  
One Dimension ◽  
Two Dimensional ◽  
Entropy Condition ◽  
Transonic Flows ◽  
Sonic Line

The mechanism that locates a shock wave in a transonic flow in one and two dimensions is examined. It is found that in one dimension the shock is located by specifying the downstream pressure whereas in two dimensions the shock is located by the application of an entropy condition at the sonic line.

scholarly journals Averaging over Narain moduli space

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Alexander Maloney ◽  
Edward Witten
Keyword(s):  
Einstein Gravity ◽  
Two Dimensions ◽  
Three Dimensions ◽  
One Dimension ◽  
Simons Theory ◽  
Two Dimensional ◽  
Dual Theory ◽  
Recent Developments ◽  
Chern Simons ◽  
Chern Simons Theory

Abstract Recent developments involving JT gravity in two dimensions indicate that under some conditions, a gravitational path integral is dual to an average over an ensemble of boundary theories, rather than to a specific boundary theory. For an example in one dimension more, one would like to compare a random ensemble of two-dimensional CFT’s to Einstein gravity in three dimensions. But this is difficult. For a simpler problem, here we average over Narain’s family of two-dimensional CFT’s obtained by toroidal compactification. These theories are believed to be the most general ones with their central charges and abelian current algebra symmetries, so averaging over them means picking a random CFT with those properties. The average can be computed using the Siegel-Weil formula of number theory and has some properties suggestive of a bulk dual theory that would be an exotic theory of gravity in three dimensions. The bulk dual theory would be more like U(1)2D Chern-Simons theory than like Einstein gravity.

ADSORPTION OF POLYATOMICS: THEORETICAL APPROACHES IN MODEL SYSTEMS AND APPLICATIONS

2006 ◽  
Vol 20 (28) ◽  
pp. 4709-4778 ◽  
Author(s):  
JOSÉ L. RICCARDO ◽  
FEDERICO J. ROMÁ ◽  
ANTONIO J. RAMIREZ-PASTOR
Keyword(s):  
Heterogeneous Systems ◽  
Statistical Thermodynamics ◽  
Two Dimensions ◽  
Model Systems ◽  
One Dimension ◽  
Two Dimensional ◽  
Multilayer Adsorption ◽  
Theoretical Approaches ◽  
Semi Empirical ◽  
Adsorption Phenomena

The adsorption of polyatomics on one- and two-dimensional lattices is studied by combining theoretical modeling, Monte-Carlo (MC), simulations and their correspondence with experimental results. In one dimension, the rigorous statistical thermodynamics of interacting chains has been presented. With respect to two-dimensional adsorption, six different models to study non-interacting adsorbates have been discussed: (i) an extension to two dimensions of the exact thermodynamic functions obtained in one dimension; (ii) the Flory–Huggins's approximation and its modification to address linear adsorbates; (iii) the well-known Guggenheim–DiMarzio approximation; (iv) the fourth one is a new description of adsorption phenomena, based on Haldane's fractional statistics; (v) the so-called Occupation Balance, based on the expansion of the reciprocal of the fugacity; and (vi) a simple semi-empirical model obtained by combining exact one-dimensional calculations and Guggenheim–DiMarzio approach. In addition, the statistical thermodynamics of interacting polyatomics has been developed on a generalization in the spirit of the Bragg–Williams and the quasi-chemical approximations. Comparison with MC simulations and experimental adsorption isotherms are used to test the accuracy and reliability of the proposed models. Finally, applications to heterogeneous systems and multilayer adsorption are discussed.

Development of a Spray-Coated Tactile Sensor – Prototype and Modeling of 2D Sensor on Cylindrical Surface –

2019 ◽  
Vol 31 (6) ◽  
pp. 882-893
Author(s):  
Kouki Sato ◽  
Luis Canete ◽  
Takayuki Takahashi ◽  
◽  
Keyword(s):  
Equivalent Circuit ◽  
Cylindrical Surface ◽  
Delay Time ◽  
Tactile Sensor ◽  
Two Dimensions ◽  
One Dimension ◽  
Two Dimensional ◽  
One Dimensional ◽  
Contact Position ◽  
Spray Gun

The objective of this study is to extend the application of the spray-coated tactile sensor, ScoTacS, which is being developed by the authors and can be constructed simply by “coating” with a spray gun, from one dimension to two dimensions, and further to configure it into various shapes such as a ring. This sensor is constructed by coating three layers-conductive, piezoelectric, and resistive films-in sequence. It is based on a unique principle by which the contact position is detected from the delay time, i.e., the time difference between the arrivals of peaks in the output signals. As the delay time varies with the contact position, it can be used to estimate the contact position. In this paper, after analyzing the characteristics of one-dimensional sensors, such as linear and ring sensors, we present the equivalent circuit models and experimental results of a two-dimensional sensor fully coated on a cylinder.

scholarly journals A REJECTION MECHANISM IN 2D BOUNDED CONFIDENCE PROVIDES MORE CONFORMITY

2008 ◽  
Vol 11 (04) ◽  
pp. 529-549 ◽  
Author(s):  
S. HUET ◽  
G. DEFFUANT ◽  
W. JAGER
Keyword(s):  
Attitude Change ◽  
Large Range ◽  
Two Dimensions ◽  
The Other ◽  
One Dimension ◽  
Two Dimensional ◽  
Number Of Clusters ◽  
Bounded Confidence ◽  
Rejection Mechanism ◽  
Model Apply

This paper explores the dynamics of attitude change in two dimensions resulting from social interaction. We add a rejection mechanism into the 2D bounded confidence (BC) model proposed by Deffuant et al. (2001). Individuals are characterized by two-dimensional continuous attitudes, each associated with an uncertainty u, supposed constant in this first study. Individuals interact through random pairs. If their attitudes are closer than u on both dimensions, or further than u on both dimensions, or closer than u on one dimension and not further than u + δ u on the other dimension, then the rules of the BC model apply. But if their attitudes are closer than u on one dimension and further than u + δ u on the other dimension, then the individuals are in a dissonant state. They tend to solve this problem by shifting away their close attitudes. The model shows metastable clusters, which maintain themselves through opposite influences of competitor clusters. Our analysis and first experiments support the hypothesis that, for a large range of uncertainty values, the number of clusters grows linearly with the inverse of the uncertainty, whereas this growth is quadratic in the BC model.

scholarly journals Las dos dimensiones del rechazo hacia las personas homosexuales / The two dimensions of the rejection toward homosexual persons

2014 ◽  
Vol 14 (1) ◽  
pp. 103-116
Author(s):  
José Moral De La Rubia ◽  
Adrian Valle De La O
Keyword(s):  
Gay Men ◽  
Factor Model ◽  
Two Dimensions ◽  
One Dimension ◽  
Internalized Homonegativity ◽  
Two Dimensional ◽  
Probability Sample ◽  
Mexican Students ◽  
Close Fit ◽  
Better Than

Objetivo:Considerando los conceptos de actitud hacia las personas homosexua-les, homofobia y homonegatividad internalizada, este estudio tiene como objetivoscomprobar la hipotética distinción de dos dimensiones dentro del rechazo hacia laspersonas homosexuales, una de rechazo abierto y otra de rechazo sutil.Materialesy métodos:La escala de actitud hacia lesbianas y hombres homosexuales (ATLG),la escala homofobia (HF-8) y la escala de homonegatividad internalizada (HNI-16)fueron aplicadas a una muestra no probabilística de 231 estudiantes mexicanos demedicina y psicología (54% mujeres y 46% hombres). Los datos se analizaron poranálisis factorial confirmatorio.Resultados:Un modelo de dos factores tuvo buenajuste a los datos y su ajuste fue significativamente mejor que el de un modelo deun factor.Conclusiones:La distinción entre manifestaciones sutiles y abiertas en elrechazo hacia personas homosexuales puede ser sostenida empíricamente. Final-mente se hacen sugerencia para la evaluación e intervención en concordancia conesta conceptualización bidimensional. Objective: Taking into account the concepts of attitude toward homosexual persons,homophobia, and internalized homonegativity, the aims of this study were to verify thehypothetical distinction between two dimensions within the rejection toward homosexualpersons, one dimension of open rejection and another dimension of subtle rejection.Materials and methods: The Attitudes Toward Lesbians and Gay men (ATLG) scale,the 8-itemHomophobia (HF-8) scale and the 16-itemInternalized Homonegativity (HNI-16) scale were applied to a non-probability sample of 231 Mexican students of medicineand psychology (54% women and 46% men). Data were analyzed through confirmatoryfactor analysis. Results: A two-factor model had a close fit to the data, and its fitwas significantly better than the fit of a one-factor model. Conclusion: The distinctionbetween subtle and overt manifestations in the rejection toward homosexual personscan be empirically sustained. Finally, suggestions on evaluation and intervention areproposed in accordance with this two-dimensional conceptualization

scholarly journals Experimental Investigation of Dynamic Distortion Properties in Transonic Flow Diffuser

1985 ◽  
Author(s):  
Huang Xijun ◽  
Li Huaiti ◽  
Dong Jinzhong
Keyword(s):  
Shock Wave ◽  
Experimental Investigation ◽  
Probability Density Function ◽  
Transonic Flow ◽  
Dynamic Pressure ◽  
Experimental Studies ◽  
Two Dimensional ◽  
Dynamic Distortion ◽  
Wave Stability ◽  
Discharge Section

This paper provides a description of experimental studies of various dynamic distortion properties in a two-dimensional transonic diffuser. Based upon the measured dynamic pressure across the diffuser discharge section, the Δ PRMS, amplitude power density and probability density function have been analyzed. The results indicate that the dynamic distortion is closely related to the terminal shock wave stability of transonic diffuser, and the distribution of Δ PRMS and PSD are important Properties for dynamic distortion.

Numerical Simulation of Inviscid Transonic Flow Through Nozzles With Fluctuating Back Pressure

1989 ◽  
Vol 111 (2) ◽  
pp. 169-180 ◽  
Author(s):  
A. Bo¨lcs ◽  
T. H. Fransson ◽  
M. F. Platzer
Keyword(s):  
Steady State ◽  
Two Dimensions ◽  
Back Pressure ◽  
Nozzle Geometry ◽  
Pressure Jump ◽  
Two Dimensional ◽  
Transonic Flows ◽  
One Dimensional ◽  
Flux Vector Splitting ◽  
Shock Position

The study presents a numerical method, based on the flux vector splitting approach, to the problem of unsteady one-dimensional and two-dimensional inviscid transonic flows, with emphasis on the numerical determination of the shock position, through nozzles with time-varying back pressure. The model is first validated by comparison with exact (one dimension) and numerical (two dimensions) steady-state solutions. It is thereafter applied to the problem of time-fluctuating back pressure in quasi-one-dimensional and two-dimensional nozzles. The one-dimensional results are validated by comparison with a small perturbation analytical unsteady solution, whereafter a few sample cases are presented with the objective of understanding fundamental aspects of unsteady transonic flows. It is concluded that both the amplitude and frequency of the imposed fluctuating exit pressure are important parameters for the location of the unsteady shock. It is also shown that the average unsteady shock position is not necessarily identical with the steady-state position, and that the unsteady shock may, under certain circumstances, propagate upstream into the subsonic flow domain. The pressure jump over the shock, as well as the unsteady post-shock pressure, is different for identical shock positions during the cycle of fluctuation, which implies that an unsteady shock movement, imposed by oscillating back pressure, may introduce a significant unsteady lift and moment. This may be of importance for flutter predictions. It is also noted that, although the sonic velocity is obtained in the throat of steady-state, quasi-one-dimensional flow, this is not necessarily true for the unsteady solution. During part of the period with fluctuating back pressure, the flow velocity may be subsonic at the throat and still reach a supersonic value later in the nozzle. This phenomenon depends on the frequency and amplitude of the imposed fluctuation, as well as on the nozzle geometry.

GENERAL RESULTS FOR THE WITTEN INDEX USING THE WIGNER-KIRKWOOD EXPANSION

1989 ◽  
Vol 04 (27) ◽  
pp. 2701-2704 ◽  
Author(s):  
R.K. BHADURI ◽  
AVINASH KHARE ◽  
M.V.N. MURTHY
Keyword(s):  
Quantum Mechanics ◽  
Magnetic Flux ◽  
Order Term ◽  
Two Dimensions ◽  
One Dimension ◽  
Two Dimensional ◽  
Arbitrary Vector ◽  
Flux Lines ◽  
Magnetic Flux Lines ◽  
Witten Index

A systematic ħ-expansion of the regulated Witten index Δ(β) in one and two-dimensional SUSY quantum mechanics reveals that the lowest order ħ-term is nonzero, and all terms to at least the next four orders vanish. In one dimension, this lowest order term yields the well-known exact quantum result for an arbitrary superpotential. For the Pauli Hamiltonian with an arbitrary vector potential in two-dimensions, we find the new result that the semiclassical Δ(β) is β-independent and is equal to the number of magnetic flux lines.

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