Coupled Thermoelasticity of Bars

1967 ◽  
Vol 34 (1) ◽  
pp. 137-145 ◽  
Author(s):  
O. W. Dillon
Keyword(s):  
Constant Velocity ◽  
Specific Problem ◽  
Error Function ◽  
Time History ◽  
Temperature Gradients ◽  
Constant Acceleration ◽  
Coupled Thermoelasticity ◽  
The Face ◽  
Bar Velocity ◽  
Thermal Precursors

Several boundary-value problems for semi-infinite bars made of a coupled thermoelastic material are solved by means of new functions. These arise in the solutions as “corrections” to classical tabulated functions such as the error function. However, they are not always small compared to their uncoupled equivalents. It turns out that the numerical differences in the solutions of a specific problem are usually small. But interesting phenomena are still found. The stresses produced in the coupled material are larger than those in the uncoupled one. The temperature generated on the face during impact of identical specimens is less than one might expect on simple intuitive grounds. Its time history is also quite interesting. Stress, strain, and thermal precursors exist but they do not propagate at a unique speed, while discontinuities propagate at the isothermal bar velocity. It is found that there is not much difference between the surface temperatures generated in a constant-velocity problem and one in which a constant acceleration is imposed. The temperature gradients are, however, different in these two problems.

IMM-UKF-TFS Model-based Approach for Intelligent Navigation

2013 ◽  
Vol 66 (6) ◽  
pp. 859-877 ◽  
Author(s):  
M. Malleswaran ◽  
V. Vaidehi ◽  
S. Irwin ◽  
B. Robin
Keyword(s):  
Kalman Filter ◽  
Constant Velocity ◽  
Unscented Kalman Filter ◽  
Interacting Multiple Model ◽  
Multiple Model ◽  
State Variables ◽  
Constant Acceleration ◽  
Positional Accuracy ◽  
Model Based ◽  
Novel Approach

This paper aims to introduce a novel approach named IMM-UKF-TFS (Interacting Multiple Model-Unscented Kalman Filter-Two Filter Smoother) to attain positional accuracy in the intelligent navigation of a manoeuvring vehicle. Here, the navigation filter is designed with an Unscented Kalman Filter (UKF), together with an Interacting Multiple Model algorithm (IMM), which estimates the state variables and handles the noise uncertainty of the manoeuvring vehicle. A model-based estimator named Two Filter Smoothing (TFS) is implemented along with the UKF-based IMM to improve positional accuracy. The performance of the proposed IMM-UKF-TFS method is verified by modelling the vehicle motion into Constant Velocity-Coordinated Turn (CV-CT), Constant Velocity – Constant Acceleration (CV-CA) and Constant Acceleration-Coordinated Turn (CA-CT) models. The simulation results proved that the proposed IMM-UKF-TFS gives better positional accuracy than the existing conventional estimators such as UKF and IMM-UKF.

scholarly journals The Onset Threshold of Cybersickness in Constant and Accelerating Optical Flow

2020 ◽  
Vol 10 (21) ◽  
pp. 7808
Author(s):  
Jiwon Kim ◽  
Taezoon Park
Keyword(s):  
Optical Flow ◽  
Constant Velocity ◽  
Human Subject ◽  
Rotational Axis ◽  
Constant Acceleration ◽  
Severe Nausea ◽  
Particle Field ◽  
Human Subject Experiment ◽  
Experimental Findings ◽  
Subject Experiment

This study investigated the principal translational or rotational axis that evokes the most severe cybersickness by detecting constant velocity and acceleration thresholds on the onset of cybersickness. This human subject experiment with 16 participants used a 3D particle field with movement directions (lateral, vertical, yaw, or pitch) and motion profiles (constant velocity or constant acceleration). The results showed that the threshold of pitch optical flow was suggestively lower than that of the yaw, and the vertical threshold was significantly lower than the lateral. Still, there was no effect of scene movement on the level of cybersickness. In four trials, the threshold increased from the first to the second trial, but the rest remained the same as the second one. However, the level of cybersickness increased significantly between the trials on the same day. The disorientation-related symptoms occurred on the first trial day diminished before the second trial day, but the oculomotor-related symptoms accumulated over the days. Although there were no correlations between the threshold and total cybersickness severity, participants with a lower threshold experienced severe nausea. The experimental findings can be applied in designing motion profiles to reduce cybersickness by controlling the optical flow in virtual reality.

scholarly journals Chocs/contre choc pétroliers et investisssements étrangers au Nigéria

2005 ◽  
Vol 21 (3) ◽  
pp. 525-544
Author(s):  
Suzanne Quiers-Valette
Keyword(s):  
Foreign Investment ◽  
Specific Problem ◽  
Price Shocks ◽  
Foreign Investments ◽  
Oil Boom ◽  
The Face ◽  
The Subject ◽  
Sheer Size ◽  
Oil Wealth ◽  
The Impact

The problems linked to oil profits have been the subject of numerous studies. Few of these studies, however, have dealt with the specific problem of the impact of oil price shocks and return shocks on foreign investments in revenue-generating countries. This paper seeks to analyze the case of Nigeria which has been and still is a key country for the international oligopolies, thanks to the sheer size of its market and its oil wealth. In the face of Africa 's current decline Nigeria is, with South Africa, a potential keystone state that could in time bind together other states into a regional bloc with good prospects for growth. This possible unifying role, however, seems to depend on foreign investment picking up. It is therefore essential to understand better the extent to which foreign investment was spurred from 1973 onwards by the oil boom and what the consequences were of the crisis that began in 1982.

On the Discussion of the Damping Reduction Factors in the Constant Acceleration Region for ATC-40 and FEMA-273

2003 ◽  
Vol 19 (4) ◽  
pp. 1001-1006 ◽  
Author(s):  
Yu-Yuan Lin ◽  
Meng-Hao Tsai ◽  
Kuo-Chun Chang
Keyword(s):  
Constant Velocity ◽  
Response Spectra ◽  
Design Practice ◽  
Velocity Range ◽  
Acceleration Region ◽  
Constant Acceleration ◽  
Reduction Factors

According to the ATC-40 (1996) and FEMA-273 (1997) documents, the damping reduction factors for the constant acceleration range of the design response spectra are larger than those for the constant velocity range of those. This trend is contrary to the results obtained from several recent studies and may lead to underestimates of the high-damped design response spectra. This paper points out the issue and suggests further examinations of the factor in the constant acceleration region with potential revision to design practice.

Development of the Variable-Rate Transymmetric Motion With Discretely Vanishing Shock

1984 ◽  
Vol 106 (1) ◽  
pp. 109-113 ◽  
Author(s):  
S. N. Kramer
Keyword(s):  
Constant Velocity ◽  
Angular Displacement ◽  
Operating Cost ◽  
Dynamic Responses ◽  
Variable Rate ◽  
Constant Acceleration ◽  
Functional Relationships ◽  
Rest Position ◽  
New Type ◽  
Velocity Motion

In industry when a link, crank, or other mechanical component is to be rotated from one rest position to another, it is necessary to establish appropriate functional relationships for angular displacement, velocity, and acceleration versus time such that the output motion satisfies certain kinematic and dynamic requirements. In the work presented here, a new type of motion is developed which has distinct advantages over constant velocity motion, constant acceleration motion, simple harmonic motion, cycloidal motion, and polynomial motions. The “variable-rate transymmetric” motion allows a designer to assign specific portions of the motion to be described by a linearly varying acceleration and other portions by a constant acceleration. As a result, the designer can decrease the power required, decrease the operating cost, and decrease dynamic responses such as shock, vibration, and shaking force.

scholarly journals Communication disorder: contemporary art and psychoanalysis

2019 ◽  
pp. 91-97
Author(s):  
Ana Lúcia Mandelli de Marsillac
Keyword(s):  
Contemporary Art ◽  
Time History ◽  
Communication Disorders ◽  
Work Of Art ◽  
The Uncanny ◽  
The Face ◽  
History Of ◽  
Qualitative Methodologies ◽  
And Function ◽  
Psychoanalytic Method

This revision seeks to analyze the methodological intersections of contemporary art and psychoanalysis, by considering the value attributed to communication disorders by both fields. I will analyze elements of "In the Face of time: History of art and anachronism of Images" (2000), by Didi-Huberman. In addition, I will single out two texts that are crucial to the psychoanalytic method: "The Uncanny” (1919), by Freud and "Function and field of speech and Language" (1953), by Lacan. The concept of the uncanny is central to this approach, since it reveals the proximity between strangeness and familiarity. It is through the concept of the uncanny that psychoanalysis unfolds the perspective of a negative aesthetics, which is not at the service of the completeness of communication. Instead, it focuses on the cracks that paradoxically allow us to say more and to look at the latent contents of communication. Contemporary art and psychoanalysis both use non-linear communication. Research performed at their intersection is based on qualitative methodologies and seeks to analyze exemplary situations in culture, such as the discourses of an epoch and works of art. In this methodological encounter, there isn’t a single meaning to be sought. On the contrary, it is the researcher’s task to reflect on the paths that lead to the creation of a work of art, as well as on the ideals it conveys, its singularity and its relationship with culture. He can then render visible the complexity and the multiple meanings embedded in the work of art.

Thermoelasticity When the Material Coupling Parameter Equals Unity

1965 ◽  
Vol 32 (2) ◽  
pp. 378-382 ◽  
Author(s):  
O. W. Dillon
Keyword(s):  
Laplace Transform ◽  
Constant Velocity ◽  
Coupling Parameter ◽  
Step Function ◽  
Surface Strain ◽  
Coupled Thermoelasticity ◽  
Velocity Impact ◽  
One Dimensional ◽  
Laplace Transform Technique ◽  
The Laplace Transform

Analytical solutions of three problems in coupled thermoelasticity are presented for the case when the material coupling parameter equals unity. The problems considered are: (a) Danilovskaya’s problem of a step function in temperature at the surface; (b) a step function in surface strain; and (c) constant velocity impact. Solutions are presented for the case of thin bars (one-dimensional stress) and are obtained by the Laplace-transform technique. There is great simplification in the equations when the material coupling parameter equals unity which permits the straightforward inversion of the transformed solutions. The results demonstrate significant deviations from the corresponding uncoupled solutions.

scholarly journals Precise modeling of complex tooth surface microtopography and multi-degree-of-freedom nonlinear friction dynamics for high-performance face gear

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041988107 ◽  
Author(s):  
Shuai Mo ◽  
Jiabei Gong ◽  
Guoguang Jin ◽  
Shengping Zhu ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Gear Tooth ◽  
Time History ◽  
Surface Friction ◽  
Low Noise ◽  
Gear Transmission ◽  
Degree Of Freedom ◽  
Tooth Surface ◽  
Nonlinear Dynamic Model ◽  
Face Gear ◽  
The Face

Face gear transmission is a kind of space-meshing mechanism that is mainly used in the field of aviation. Compared with traditional transmission, it has the advantages of stability, reliability, low noise, and strong carrying capacity. However, owing to its complex tooth surface, there are no means to accurately model the face gear. Likewise, research based on the geometry is difficult. Therefore, the tooth surface equation of the face gear is derived in this article based on the meshing theory. Based on the equations, the point cloud of the face gear tooth surface is calculated, the complex tooth surface is generated, and the face gear is accurately modeled. Moreover, taking tooth surface friction excitation into consideration, a multi-degree-of-freedom nonlinear dynamic model of face gear transmission system is established, using the adaptive variable step length Runge–Kutta method. As shown in the results, the bifurcation diagram, phase diagram, time history diagram, and Poincaré section diagram are combined to analyze the influence of tooth surface friction and meshing frequency on the dynamic characteristics of the system.

ON THE PROLONG ATTACHMENT OF LEADING EDGE VORTEX ON A FLAPPING WING

2009 ◽  
Vol 23 (03) ◽  
pp. 357-360 ◽  
Author(s):  
T. T. LIM ◽  
C. J. TEO ◽  
K. B. LUA ◽  
K. S. YEO
Keyword(s):  
Constant Velocity ◽  
Leading Edge ◽  
Flapping Wing ◽  
Constant Acceleration ◽  
Leading Edge Vortex ◽  
Velocity Flow ◽  
Edge Vortex ◽  
Per Se ◽  
Spanwise Flow ◽  
Negligible Influence

In this paper, we take a fundamental approach to investigate the effect of spanwise flow on the prolonged attachment of leading edge vortex (LEV) on a flapping wing. By imposing a constant acceleration-constant velocity flow on elliptic wings of various sweep angles and angles of attack, our experimental and numerical results show that while spanwise flow per se has negligible influence on the prolong attachment of the LEV, vortex stretching can significantly delay detachment of the LEV, even for a small spanwise flow.

Sign in / Sign up

Export Citation Format

Share Document