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Technical Paper

Considerations for Applying and Interpreting Monte Carlo Simulation Analyses in Accident Reconstruction

One popular method of examining and quantifying the uncertainty within an analysis is the use of Monte Carlo simulation techniques. The methods have been well established and published over the last several years by numerous authors. ...One of the key factors underlying the Monte Carlo analysis is the assumed probability distribution of the individual factors within the analysis. ...However, the literature to date has not examined how the assumption of a distribution affects the resulting probability distribution of the Monte Carlo analysis. This paper attempts to address this issue. Furthermore, with the large number of samples typically considered during a Monte Carlo analysis, the resulting probability distribution tends to be normal and lends itself well to statistical interpretation as to the “most likely” range of the desired parameter.
Technical Paper

Uncertainty in Accident Reconstruction Calculations

Three popular techniques are discussed in the context of accident reconstruction. The first establishes upper and lower bounds through calculation of the largest and smallest possible values of the quantity being estimated for all combinations of the input variables.
Technical Paper

Integrating Monte Carlo Simulation, Momentum-Based Impact Modeling, and Restitution Data to Analyze Crash Severity

Accurate evaluation of the crash severity will, therefore, include analysis of the effect that uncertainties in the values of the input parameters have on the calculated change in velocity. Monte Carlo simulation, a statistical technique, enables the reconstructionist to evaluate the effect of uncertainty on the analysis of crash severity. ...Use of the Monte Carlo simulation technique is beneficial since a reconstructionist can enter a range of values for each input parameter. ...Application of the Monte Carlo technique is intended to improve the legitimacy of crash severity analysis by helping the reconstructionist consider a wide range of possible solutions within the bounds of the imperfect data and report statistically meaningful ranges for the change in velocity.
Journal Article

A Bayesian Approach to Cross-Validation in Pedestrian Accident Reconstruction

In statistical modeling, cross-validation refers to the practice of fitting a model with part of the available data, and then using predictions of the unused data to test and improve the fitted model. In accident reconstruction, cross-validation is possible when two different measurements can be used to estimate the same accident feature, such as when measured skidmark length and pedestrian throw distance each provide an estimate of impact speed. ...In accident reconstruction, cross-validation is possible when two different measurements can be used to estimate the same accident feature, such as when measured skidmark length and pedestrian throw distance each provide an estimate of impact speed. ...An actual measurement falling in an extreme tail of the predictive distribution suggests a weakness in the assumptions governing the reconstruction. This paper describes an implementation of these ideas using the Bayesian freeware WinBUGS.

Vehicle Accident Analysis and Reconstruction Methods, Second Edition

Thoroughly revised, this new edition builds on the original exploration of accident analysis, reconstruction, and vehicle design. Enhanced with new material and improved chapters on key topics, an expanded glossary of automotive terms, and a bibliography at the end of the book providing further reading suggestions make this an essential resource reference for engineers involved in litigation, forensic investigation, automotive safety, and crash reconstruction. ...Designed for the experienced practitioner, this new book aims to help reconstruction specialists with problems they may encounter in everyday analysis. The authors demonstrate how to take the physics behind accidents out of the idealized world and into practical situations. ...The authors demonstrate how to take the physics behind accidents out of the idealized world and into practical situations. Real-world examples are used to illustrate the methods, clarify important concepts, and provide practical applications to those working in the field.
Technical Paper

Monte Carlo Based Predictive Models for Total Flux Output of Multi-LED Array Designs

Monte Carlo simulations are shown to be a useful tool when determining the flux output of LED arrays during the design phase. ...The results of Monte Carlo simulations are able to show the statistical distribution of output flux based on multi-LED arrays, thus allowing engineers to optimise their design, rather than using worst case scenario design principles.
Technical Paper

Predicting Weight Distribution from Occupant Load Using a Monte Carlo Method

Actual occupant weight distributions versus certified weight per occupant seat causes a potential conflict between a vehicle's in-use weight versus its certified GVWR. A Monte Carlo method using a midsized bus example was conducted to determine the statistical probability that adult passengers and rated cargo would result in weight distributions that exceeded tire load capability, Gross Axle Weight Rating (GAWR), or GVWR.
Technical Paper

Statistical Error Control for Radiative Software Based on Monte Carlo Methods

This paper presents a general error model for MCRT algorithms, which is later applied to the calculation of some basic radiative entities. Furthermore, some issues related to the implementation of such models in a software tool are discussed. Finally, the accuracy control methods are applied to the more complex case of the heat flux absorbed in a given radiative face. Although only the relative error is considered through the discussion, similar results can be derived for the absolute error.
Technical Paper

Sensitivity of Accident Reconstruction Calculations

A number of simplistic formulae, based on particle dynamics, energy, and momentum methods are routinely employed by accident reconstructionists to calculate vehicle speeds immediately prior to impact. It is almost always the case that scene evidence and other information regarding important variables involved in such equations must either be estimated or can be measured only in an approximate way. ...Example problems illustrate the difficulties faced by accident reconstructionists as they grapple with incomplete and/or estimated values for important variables, and with the inherent sensitivity of some of the calculations to seemingly small variations in variable magnitudes.
Journal Article

Estimation of One-Sided Lower Tolerance Limits for a Weibull Distribution Using the Monte Carlo Pivotal Simulation Technique

This paper introduces a methodology to calculate confidence bounds for a normal and Weibull distribution using Monte Carlo pivotal statistics. As an example, a ready-to-use lookup table to calculate one-sided lower confidence bounds is established and demonstrated for normal and Weibull distributions. ...Lieberman in 1958 (later modified by Link in 1985 and Wei in 2012), and has been widely used in the automotive industry because of the easy-to-use lookup tables. Monte Carlo simulation methods presented here are more accurate as they eliminate assumptions and approximations inherent in existing approaches by using random experiments.
Journal Article

Automatic Transmission Gear Ratio Optimization and Monte Carlo Simulation of Fuel Consumption with Parasitic Loss Uncertainty

An enterprise approach for vehicle fleet balancing of fuel consumption objectives based upon selection of automatic transmission gearing strategy is presented. Monte Carlo simulations for the influence of parasitic loss uncertainty for the automatic transmissions selected from the generalized DOE were conducted to determine the range of fuel consumption that might be realized in production. ...Automatic transmission gearing parameter selection was unaffected by the variation introduced by the Monte Carlo simulations, but did show fuel consumption performance to vary upwards of 9 g CO2/km depending on applications and to have a direct impact on powertrain operating parameters.
Technical Paper

Particulate Matter Formation Dynamics as Investigated by Ultra-Accelerated Quantum Chemical Molecular Dynamics Coupled with Canonical Monte Carlo Method

Suppression or reduction of soot emissions is an important goal in the development of automotive engines for environmental and human health purposes. A better understanding at the molecular level of the formation process of soot particles resulting from collision and aggregation of smaller particles made of Polycyclic Aromatic Hydrocarbon (PAH) is needed. In addition to experiments, computational methods are efficient and valuable tools for this purpose. As a first step in our detailed computational chemistry study, we applied Ultra-Accelerated Molecular Dynamics (UAQCMD) and Canonical Monte-Carlo (CMC) methods to investigate the nucleation process. The UA-QCMD can calculate chemical reaction dynamics 107 times faster than conventional first principle molecular dynamics methods, while CMC can calculate equilibrium properties at various temperatures, pressures, and chemical compositions.
Technical Paper

Spot Weld Failure Analysis for Accident Reconstruction

Adequacy of resistance spot welds in low carbon steels in relation to structural integrity can become an issue in the reconstruction of automotive accidents. Because formation of a plug (or button or slug) in a peel test is used as a quality control criterion for welds, it is sometimes assumed conversely that a weld which failed is defective if no plug is present.
Technical Paper

Comparison of Tire Friction Test Methodologies Used in Accident Reconstruction

Many accident reconstructions rely on the use of friction factors for the analysis of vehicle speeds. ...Measurement of the friction factor, or coefficient of friction, at the accident site is usually an important step in achieving a more accurate estimate of the friction factor at the time of the accident. Over the years several on site test methodologies have emerged within the accident reconstruction community. ...Measurement of the friction factor, or coefficient of friction, at the accident site is usually an important step in achieving a more accurate estimate of the friction factor at the time of the accident.
Technical Paper

Lane Change Maneuver Modeling for Accident Reconstruction Applications

Lane change maneuvers are often implemented in typical driving applications and more severe swerving maneuvers are occasionally performed in order to avoid motor vehicle collisions. For accident reconstruction purposes, it is necessary to accurately model the vehicle motion and driver response during a lane change maneuver.