Search results for "Rash"

Mathematical modeling of vehicle frontal crash by a double spring-mass-damper model

2013

This paper presents development of a mathematical model to represent the real vehicle frontal crash scenario. The vehicle is modeled by a double spring-mass-damper system. The front mass m1 represents the chassi of the vehicle and rear mass m2 represents the passenger compartment. The physical parameters of the model (Stiffness and dampers) are estimated using Nonlinear least square method (Levenberg-Marquart algorithm) by curve fitting the response of a double spring-mass-damper system to the experimental displacement data from the real vehicle crash. The model is validated by comparing the results from the model with the experimental results from real crash tests available.

Crash Response of a Repaired Vehicle - Influence of Welding UHSS Members

2020

The harp: a vehicle crash test apparatus for full-scale crash test experiments

2012

Published version of an article in the journal: The International Journal of Advanced Manufacturing Technology. Also available from the publisher at: http://dx.doi.org/10.1007/s00170-012-3960-3 The current paper describes an apparatus for full-scale vehicle crash test experimentation. This apparatus is referred to as the harp. In brief, the harp may either accelerate a trolley which is impacted into a test vehicle or the test vehicle itself may be accelerated and impacted into an object such as a barrier, a pole, or another vehicle. If a trolley is accelerated, it is equipped with load cells to record the axial crushing force. If a test vehicle is accelerated, it is equipped with a three-ax…

Crash modeling for urban roundabouts: a case study

2013

In many cities and towns, a large number of intersections are considered sites with promise for safety and operational improvements. Several studies have been carried out in many countries to establish relationships between crashes and flow and non-flow explanatory variables, using statistical tools to investigate factors critical to road safety. Starting from a brief review of existing information and analysis on the issue, this article summarizes the findings of an exploratory analysis aimed at modeling injury crashes for a sample of urban roundabouts. The methodological path followed in this research allowed to handle issues associated with the estimation of a safety performance function…

Mathematical modeling and parameters estimation of a car crash using data-based regressive model approach

2011

Author's version of an article in the journal: Applied Mathematical Modelling. Also available from the publisher at: http://dx.doi.org/10.1016/j.apm.2011.04.024 n this paper we present the application of regressive models to simulation of car-to-pole impacts. Three models were investigated: RARMAX, ARMAX and AR. Their suitability to estimate physical system parameters as well as to reproduce car kinematics was examined. It was found out that they not only estimate the one quantity which was used for their creation (car acceleration) but also describe the car's acceleration, velocity and crush. A virtual experiment was performed to obtain another set of data for use in further research. An A…

THE ROLE OF CYTOKININS AND ETHYLENE INHIBITORS ON LENTICEL HYPERTROPHY GENERATION AND ETHYLENE PRODUCTION IN IN VITRO CULTURES OF POPULUS EUPHRATICA …

1995

Populus euphratica Olivier is native to the Irano—Turanian areas (Middle East). Elche (Alicante province, SE Spain) is known to be its only European location. Nodal segments from root shoots were established in vitro in a Murashige and Skoog medium supplemented with several cytokinins. Ethylene inhibitors AgNO3 and CoCl2 were used in combination with kinetin. Hormone-free media supplemented with sucrose (20–60 mg 1−1) was also tested. Ethylene was measured by gas chromatography, and both the percentage of sprouting shoots and lenticel hypertrophy in cultures were recorded. Ethylene production was higher in cultures supplemented with cytokinins (especially with meta-topolin), with high sprou…

Flush-Crash Experiments in Drosophila

1989

In 1968, Hampton Carson (1968) proposed the founder-flush-crash model, a new model of speciation, which readily lends itself to experimental testing in the laboratory (Carson 1971).

Shape optimization of high-energy absorbers

2018

In this paper, a new approach to simulate and to optimize the performances of a crash-box, in terms of energy absorption or acceleration peak, is presented. As soon as the maximum size of the crash-box (longitudinal and transversal dimensions) has been fixed, the new approach allows optimizing the shape of the transversal section and the thickness of the structure. Thanks to the proposed procedure, engineers can easily identify the best crash-box depending on the particular working conditions. The new method has been tested with different cases study by considering different objective functions. The obtained results show the procedure works well and also demonstrate that the optimal number …

Visualizing coherent molecular rotation in a gaseous medium

2021

Inducing and controlling the ultrafast molecular rotational dynamics using shaped laser fields is essential in numerous applications. Several approaches exist that allow following the coherent molecular motion in real-time, including Coulomb explosion-based techniques and recovering molecular orientation from the angular distribution of high harmonics. We theoretically consider a non-intrusive optical scheme for visualizing the rotational dynamics in an anisotropic molecular gas. The proposed method allows determining the instantaneous orientation of the principal optical axes of the gas. The method is based on probing the sample using ultra-short circularly polarized laser pulses and recor…

Optical Imaging of Coherent Molecular Rotors

2020

International audience; Short laser pulses are widely used for controlling molecular rotational degrees of freedom and inducing molecular alignment, orientation, unidirectional rotation and other types of coherent rotational motion. To follow the ultra-fast rotational dynamics in real time, several techniques for producing molecular movies have been proposed based on the Coulomb explosion of rotating molecules, or recovering molecular orientation from the angular distribution of high-harmonics. The present work offers and demonstrates a novel non-destructive optical method for direct visualization and recording of movies of coherent rotational dynamics in a molecular gas. The technique is b…