scholarly journals JAMMING TRANSITION OF POINT-TO-POINT TRAFFIC THROUGH CO-OPERATIVE MECHANISMS

2012 ◽  
Vol 23 (11) ◽  
pp. 1250077 ◽  
Author(s):  
JUN FANG ◽  
ZHENG QIN ◽  
XIQUN CHEN ◽  
ZHAOHUI XU
Keyword(s):  
Average Velocity ◽  
Critical Density ◽  
Two Dimensional ◽  
Average Flow ◽  
Traffic Models ◽  
Face To Face ◽  
Jamming Transition ◽  
Ping Pong ◽  
Point To Point ◽  
Alternative Routes

We study the jamming transition of two-dimensional point-to-point traffic through co-operative mechanisms (DCM) using computer simulation. We propose two decentralized co-operative mechanisms CM which are incorporated into the point-to-point traffic models: stepping aside (CM-SA) and choosing alternative routes (CM-CAR). Incorporating CM-SA is to prevent a type of ping-pong jumps from happening when two objects standing face-to-face want to move in opposite directions. Incorporating CM-CAR is to handle the conflict when more than one object competes for the same point in parallel update. We investigate and compare four models mainly from fundamental diagrams, jam patterns and the distribution of co-operation probability. It is found that although it decreases the average velocity a little, the CM-SA increases the critical density and the average flow. Despite increasing the average velocity, the CM-CAR decreases the average flow by creating substantially vacant areas inside jam clusters. We investigate the jam patterns of four models carefully and explain this result qualitatively. In addition, we discuss the advantage and applicability of decentralized co-operation modeling.

An Evaluation of the Average Flow Model [1] for Surface Roughness Effects in Lubrication

1980 ◽  
Vol 102 (3) ◽  
pp. 360-366 ◽  
Author(s):  
J. L. Teale ◽  
A. O. Lebeck
Keyword(s):  
Surface Roughness ◽  
Flow Model ◽  
Two Dimensional ◽  
Roughness Effects ◽  
Important Conclusion ◽  
Average Flow ◽  
One Dimensional ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Average Flow Model

The average flow model presented by Patir and Cheng [1] is evaluated. First, it is shown that the choice of grid used in the average flow model influences the results. The results presented are different from those given by Patir and Cheng. Second, it is shown that the introduction of two-dimensional flow greatly reduces the effect of roughness on flow. Results based on one-dimensional flow cannot be relied upon for two-dimensional problems. Finally, some average flow factors are given for truncated rough surfaces. These can be applied to partially worn surfaces. The most important conclusion reached is that an even closer examination of the average flow concept is needed before the results can be applied with confidence to lubrication problems.

scholarly journals Research on Antennas Alignment of Dynamic Point-to-Point Communication

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Qilin Zeng ◽  
Jiaxin Liu ◽  
Weiming Xiong
Keyword(s):  
Elevation Angle ◽  
Least Square Method ◽  
Optimal Level ◽  
Least Square ◽  
Two Dimensional ◽  
Scanning Strategy ◽  
One Dimensional ◽  
Communication Signal ◽  
Signal Value ◽  
Point To Point

In the dynamic point-to-point communication, to track and aim at antenna fast and accurately is the guarantee of high quality communication signal. In order to solve the problem of antenna alignment, we used the least square method (LSM) to fit the optimal level signal value (LSV) point which is based on coordinate coarse tracking alignment and matrix scanning strategy to find the LSV in this paper. Antenna is driven by two-dimensional turntable (azimuth and elevation angle (AE)): the two-dimensional turntable is decomposed into two independent one-dimensional turntables, and the LSV in AE direction are obtained by scanning, respectively. The optimal LSV point of two-dimensional turntable can be find by combing optimal LSV point of two independent one-dimensional turntables. The method has the advantages of high precision and easy implementation and can meet the requirement of fast and accurately alignment in dynamic point-to-point communication antenna engineering.

scholarly journals EVALUATION OF THE FASHION DRAWING (ILLUSTRATION) LESSON TEACHING PROGRAM UNDER THE LIGHT OF LECTURERS’ AND STUDENTS’ OPINIONS

2021 ◽  
Vol 9 (60) ◽  
Keyword(s):  
Art Education ◽  
Design Education ◽  
Formal Education ◽  
Fashion Design ◽  
Two Dimensional ◽  
Examination System ◽  
Art And Design ◽  
Face To Face ◽  
Dimensional Plane ◽  
Figure Drawing

While clothing is produced and consumed rapidly, it strives to create appropriate forms and to create appropriate identities by giving correct messages; therefore, it is one of the most important fields requiring art and design education. The fashion design student, who forms the infrastructure with basic art education and figure drawing, not only transfers the imagination to the two-dimensional plane with the fashion drawing lesson but also transfers it to the two-dimensional plane; at the same time, he takes art and design education, which is aesthetic education, and feeds his visual vision and mind. In this research, the Fashion Drawing Lesson has been examined in detail in terms of determining the place, position, importance, processing and content of the Fashion Drawing Lesson in the official fashion design curriculum and a comprehensive literature search has been conducted; then the matter has been tried to be examined thanks to a link has been established between education, fashion, art and design disciplines. The course syllabus in Turkey and some of fashion design course programs in the world were examined; the experts providing fashion formal education and the students who received fashion formal education were interviewed face-to-face to obtain information first-hand. First of all, the study started by determining the fashion design undergraduate programs in the OSYM (Assessment Selection and Placement Center) placement guide and examining the course hours, course times and course contents of the fashion formal courses in these programs. The researcher visited the designated universities for the purpose of on-site observation and interview, and conducted semi-structured interview questions and face-to-face interviews with experts and students and recorded them. The transcribed interviews were analyzed using content analysis method and the findings were interpreted within the framework of the research questions. The findings were interpreted and discussed, and after the results were written, suggestions about the study were included. As a result, it has been determined that the admission of students to the fashion design program should be made with the combination of central examination system and talent exam suitable for fashion design education. It was seen that the time granted for the program was not sufficient in mean of implementation of the fashion drawing lessons properly in the fashion design education programs. Keywords: Fashion drawing, fashion illustration, design education, fashion design education, art education

scholarly journals Crystal structures of 4-chloropyridine-2-carbonitrile and 6-chloropyridine-2-carbonitrile exhibit different intermolecular π-stacking, C—H...Nnitrileand C—H...Npyridineinteractions

2015 ◽  
Vol 71 (7) ◽  
pp. 852-856 ◽  
Author(s):  
Matthew J. Montgomery ◽  
Thomas J. O'Connor ◽  
Joseph M. Tanski
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Pyridine Ring ◽  
Nitrile Group ◽  
Two Dimensional ◽  
One Dimensional ◽  
Face To Face ◽  
Π Stacking

The two title compounds are isomers of C6H3ClN2containing a pyridine ring, a nitrile group, and a chloro substituent. The molecules of each compound pack together in the solid state with offset face-to-face π-stacking, and intermolecular C—H...Nnitrileand C—H...Npyridineinteractions. 4-Chloropyridine-2-carbonitrile, (I), exhibits pairwise centrosymmetric head-to-head C—H...Nnitrileand C—H...Npyridineinteractions, forming one-dimensional chains, which are π-stacked in an offset face-to-face fashion. The intermolecular packing of the isomeric 6-chloropyridine-2-carbonitrile, (II), which differs only in the position of the chloro substituent on the pyridine ring, exhibits head-to-tail C—H...Nnitrileand C—H...Npyridineinteractions, forming two-dimensional sheets which are π-stacked in an offset face-to-face fashion. In contrast to (I), the offset face-to-face π-stacking in (II) is formed between molecules with alternating orientations of the chloro and nitrile substituents.

Three-dimensional dynamics and transition to turbulence in the wake of bluff objects

1992 ◽  
Vol 238 ◽  
pp. 1-30 ◽  
Author(s):  
George Em Karniadakis ◽  
George S. Triantafyllou
Keyword(s):  
Reynolds Number ◽  
Three Dimensional ◽  
Period Doubling ◽  
Reynolds Numbers ◽  
Transition To Turbulence ◽  
Two Dimensional ◽  
Near Wake ◽  
Vortex Filaments ◽  
Average Flow ◽  
Time Average

The wakes of bluff objects and in particular of circular cylinders are known to undergo a ‘fast’ transition, from a laminar two-dimensional state at Reynolds number 200 to a turbulent state at Reynolds number 400. The process has been documented in several experimental investigations, but the underlying physical mechanisms have remained largely unknown so far. In this paper, the transition process is investigated numerically, through direct simulation of the Navier—Stokes equations at representative Reynolds numbers, up to 500. A high-order time-accurate, mixed spectral/spectral element technique is used. It is shown that the wake first becomes three-dimensional, as a result of a secondary instability of the two-dimensional vortex street. This secondary instability appears at a Reynolds number close to 200. For slightly supercritical Reynolds numbers, a harmonic state develops, in which the flow oscillates at its fundamental frequency (Strouhal number) around a spanwise modulated time-average flow. In the near wake the modulation wavelength of the time-average flow is half of the spanwise wavelength of the perturbation flow, consistently with linear instability theory. The vortex filaments have a spanwise wavy shape in the near wake, and form rib-like structures further downstream. At higher Reynolds numbers the three-dimensional flow oscillation undergoes a period-doubling bifurcation, in which the flow alternates between two different states. Phase-space analysis of the flow shows that the basic limit cycle has branched into two connected limit cycles. In physical space the period doubling appears as the shedding of two distinct types of vortex filaments.Further increases of the Reynolds number result in a cascade of period-doubling bifurcations, which create a chaotic state in the flow at a Reynolds number of about 500. The flow is characterized by broadband power spectra, and the appearance of intermittent phenomena. It is concluded that the wake undergoes transition to turbulence following the period-doubling route.

scholarly journals Shock wave generation in thin foils using lasers and ion beams. II 2-D expansion effects and planarity considerations

1984 ◽  
Vol 2 (1) ◽  
pp. 13-26 ◽  
Author(s):  
P. C. Thompson ◽  
P. D. Roberts
Keyword(s):  
Equation Of State ◽  
Red Light ◽  
Critical Density ◽  
Green Light ◽  
Ion Beams ◽  
Two Dimensional ◽  
Composite Target ◽  
Thin Foils ◽  
State Measurement ◽  
Hydrodynamic Code

The shock pressures generated in the interaction of lasers and light ion beams with thin foils are calculated using a two-dimensional, axisymmetric hydrodynamic code. For lasers, finite spot sizes produce a significant decrease in the pressure generated, compared to previous 1-D estimates. The effect is closely related to the coupling of the critical density with the ablation surface and is less important at shorter wavelengths, the appropriate parameter being Iλ2. For 0·5 TW red light and a 100 μm radius spot pressures are limited to 30 Mb. Perturbations across the beam profile are discussed and it is demonstrated that beam uniformity of 30% (25% for green light) is required to achieve velocity modulation of less than 2%, such as would be necessary for an equation of state measurement.For the larger targets used with light ion beams, two-dimensional effects prove to be less of a problem, and for high-Z materials the initial 1-D estimates of peak pressure are adequate. In order to obtain the shock planarity requisite for equation of state measurements in a high-Z target an intensity uniformity of ±15% would be required. However, use of a composite target enables this to be relaxed to ±25% whilst obtaining slightly higher pressures.

A POSSIBLE PAIRING MECHANISM FOR HTSC: TWO-DIMENSIONAL CONFINEMENT AND COULOMB OVER-SCREENING

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3472-3477 ◽  
Author(s):  
D. ARIOSA ◽  
H. BECK
Keyword(s):  
Mean Field ◽  
Three Dimensional ◽  
Critical Density ◽  
Zero Point ◽  
Coulomb Repulsion ◽  
Two Dimensional ◽  
Pairing Mechanism ◽  
Density Region ◽  
Point Energy ◽  
Localization Energy

Among all the common properties of HTCS cuprates, we build our model on two of them: their high anisotropy, and their extremely low density of charge carriers. The intra-layer pairing mechanism is provided by the two-dimensional over-screening of Coulomb repulsion.1,2 The c-axis zero point energy restricts this pairing to a low carrier density region. Below a critical density, the system behaves as a two-dimensional confined jellium where the energy gain due to charge pairing is larger than the c-axis localization energy. In the high density region, where the pairing energy cannot compensate the localization energy, the system delocalizes and crosses over to a three-dimensional regime. This competition between binding and confinement energies implies a monotonic decrease of mass anisotropy with doping. Pre-formed pairs which exist below a Mean Field (MF) temperature defined by the binding energy, account for pseudo-gap observations.3,4 The superconducting critical temperature T c is given by the Beresinskii–Kosterlitz–Thouless (BKT) transition of the two-dimensional layer, renormalized by quantum phase fluctuations (QPF).5 QPF account for the metal-insulator transition at very low doping.

Fluctuations, correlations and transitions in granular materials: statistical mechanics for a non-conventional system

2007 ◽  
Vol 366 (1865) ◽  
pp. 493-504 ◽  
Author(s):  
R.P Behringer ◽  
Karen E Daniels ◽  
Trushant S Majmudar ◽  
Matthias Sperl
Keyword(s):  
Statistical Mechanics ◽  
Granular Materials ◽  
Granular Systems ◽  
Dimensional System ◽  
Two Dimensional ◽  
Conventional System ◽  
Dynamical Transition ◽  
Jamming Transition ◽  
System Experiment ◽  
Two Dimensional System

In this work, we first review some general properties of dense granular materials. We are particularly concerned with a statistical description of these materials, and it is in this light that we briefly describe results from four representative studies. These are: experiment 1: determining local force statistics, vector forces, force distributions and correlations for static granular systems; experiment 2: characterizing the jamming transition, for a static two-dimensional system; experiment 3: characterizing plastic failure in dense granular materials; and experiment 4: a dynamical transition where the material ‘freezes’ in the presence of apparent heating for a sheared and shaken system.

scholarly journals (2,2′-Bipyridine-6,6′-dicarboxylato-κ3N,N′,O6)(6′-carboxy-2,2′-bipyridine-6-carboxylato-κ3N,N′,O6)cobalt(III)

2012 ◽  
Vol 68 (4) ◽  
pp. m411-m412
Author(s):  
Huimin Wang ◽  
Xiaojun Gu ◽  
Bingbing Zhang ◽  
Haiquan Su
Keyword(s):  
Hydrogen Bonds ◽  
Title Compound ◽  
Octahedral Geometry ◽  
Distorted Octahedral Geometry ◽  
Stacking Interactions ◽  
Two Dimensional ◽  
Carboxylate Ligands ◽  
Face To Face ◽  
Centroid Distance ◽  
Distorted Octahedral

The CoIIIatom in the title compound, [Co(C12H6N2O4)(C12H7N2O4)], is six-coordinated in a distorted octahedral geometry by four N atoms and two O atoms of the chelating 2,2′-bipyridine-6,6′-dicarboxylate and 6′-carboxy-2,2′-bipyridine-6-carboxylate ligands. Intermolecular O—H...O hydrogen bonds and face-to-face π-stacking interactions [centroid–centroid distance = 3.6352 (16) Å] between inversion-related pyridine rings link adjacent mononuclear units into a two-dimensional supramolecular structure, and several intermolecular C—H...O interactions are also observed.

scholarly journals Can Drag Force Suppress Fermi Acceleration in a Bouncer Model?

2009 ◽  
Vol 2009 ◽  
pp. 1-13 ◽  
Author(s):  
Francys Andrews de Souza ◽  
Lucas Eduardo Azevedo Simões ◽  
Mário Roberto da Silva ◽  
Edson D. Leonel
Keyword(s):  
Drag Force ◽  
Average Velocity ◽  
Classical Particle ◽  
Nonlinear Mapping ◽  
Sufficient Condition ◽  
Two Dimensional ◽  
Control Parameters ◽  
Fermi Acceleration ◽  
Moving Wall ◽  
Dynamical Properties

Some dynamical properties for a bouncer model—a classical particle of massmfalling in the presence of a constant gravitational fieldgand hitting elastically a periodically moving wall—in the presence of drag force that is assumed to be proportional to the particle's velocity are studied. The dynamics of the model is described in terms of a two-dimensional nonlinear mapping obtained via solution of the second Newton's law of motion. We characterize the behavior of the average velocity of the particle as function of the control parameters as well as the time. Our results show that the average velocity starts growing at first and then bends towards a regime of constant value, thus confirming that the introduction of drag force is a sufficient condition to suppress Fermi acceleration in the model.

Sign in / Sign up

Export Citation Format

Share Document