John Ferris - Academia.edu (original) (raw)
Papers by John Ferris
SPIE Proceedings, 2007
Chassis loads and vehicle handling are primarily impacted by the road surface over which a vehicl... more Chassis loads and vehicle handling are primarily impacted by the road surface over which a vehicle is traversing. By accurately measuring the geometries of road surfaces, one can generate computer models of these surfaces that will allow more accurate predictions of the loads introduced to various vehicle components. However, the logistics and computational power necessary to handle such large data files makes this problem a difficult one to resolve, especially when vehicle design deadlines are impending. This work aims to improve this process by developing Markov Chain models by which all relevant characteristics of road surface geometries will be represented in the model. This will reduce the logistical difficulties that are presented when attempting to collect data and run a simulation using large data sets of individual roads. Models will be generated primarily from measured road profiles of highways in the United States. Any synthetic road realized from a particular model is representative of all profiles in the set from which the model was derived. Realizations of any length can then be generated allowing efficient simulation and timely information about chassis loads that can be used to make better informed design decisions, more quickly.
SAE International Journal of Passenger Cars - Mechanical Systems, 2014
SAE Technical Paper Series, 2003
The U.S. Army uses the root mean squared of elevation, or the RMSE standard for characterizing ro... more The U.S. Army uses the root mean squared of elevation, or the RMSE standard for characterizing road/off-road roughness descriptions. This standard has often appeared in contracts as a performance requirement for the vehicle system. One important application of the standard is describing the testing environment for the vehicle. A physical test, which uses the standard, is the 30,000 mile endurance test. More recently, another metric has been used, the power spectral density (PSD) of road roughness. The international standard for road roughness is known as the International Roughness Index (IRI), and all road construction projects in the U.S. are based on this, as well as Department of Transportation analyses. This paper will analyze the different standards by comparing and contrasting the various aspects of each. Depending on the standard and metrics chosen, the simulation results will have different correlations with actual test. The goal is to better understand each standards limitations and how it affects the correlations.
ETS Research Bulletin Series, 1971
Journal of Paramedic Practice, 2014
A tension pneumothorax is an important reversible cause of deterioration in the multiply-injured ... more A tension pneumothorax is an important reversible cause of deterioration in the multiply-injured patient, but it is not always easy to make the diagnosis. Features that indicate the development of a tension pneumothorax can be subtle in the spontaneously breathing patient. The ‘classical’ features may not all be present and in addition, the clinical signs of tension may develop over time with increasing patient compromise. This is a life-threatening situation, which requires relief in order to save the patient's life. A tension pneumothorax can be managed in one of three ways: needle decompression, insertion of an intercostal chest drain or by open thoracostomy. Needle decompression can be performed quickly and safely by paramedic crews using well-established techniques in both the conscious and unconscious patient. We describe a case of a 55-year-old male who was ejected from his motorcycle at high speed. He was conscious with a Glasgow Coma Score (GCS) of 15 and complaining of difficulty breathing. In c...
Social Policy & Administration, 2001
Magnetic Resonance Imaging, 1994
OAH Magazine of History, 2001
Journal of Strategic Studies, 1987
Journal of Social Policy, 2002
Journal of Policy Analysis and Management, 1986
The Journal of Military History, 2008
The Journal of Military History, 1999
The Journal of Military History, 1998
Journal of Dynamic Systems, Measurement, and Control, 2013
Terrain topology is the principal source of vertical excitation to the vehicle system and must be... more Terrain topology is the principal source of vertical excitation to the vehicle system and must be accurately represented in order to correctly predict the vehicle response. It is desirable to evaluate vehicle and tire models over a wide range of terrain types, but it is computationally impractical to simulate long distances of every terrain variation. This work seeks to study the terrain surface, rather than the terrain profile, to maximize the information available to the tire model (i.e., wheel path data), yet represent it in a compact form. A method to decompose the terrain surface as a combination of deterministic and stochastic components is presented. If some, or all, of the components of the terrain surface are considered to be stochastic, then the sequence can be modeled as a stochastic process. These stochastic representations of terrain surfaces can then be implemented in tire and vehicle models to predict chassis loads.
Journal of Dynamic Systems, Measurement, and Control, 2012
Terrain is the principal source of vertical excitation to the vehicle and must be accurately repr... more Terrain is the principal source of vertical excitation to the vehicle and must be accurately represented in order to correctly predict the vehicle response. Ideally, an efficient terrain surface definition could be developed that maintains the high-fidelity information required to accurately excite vehicle models. It is also desirable to minimize the effect of the choice of measurement system used to sample the terrain surface. Nondeformable, anisotropic (path-specific) terrain surfaces are defined as a sequence of vectors, where each vector comprises terrain heights at locations oriented perpendicular to the direction of travel. A vector space is formed by the span of these vectors and a corresponding set of empirical basis vectors is developed. A set of analytic basis vectors is formed from Gegenbauer polynomials, parameterized to approximate the empirical basis vectors. A weighted inner product is defined to form a Hilbert space and the terrain surface vectors are projected onto ...
Journal of Dynamic Systems, Measurement, and Control, 2012
Terrain topology is the principal source of vertical excitation into the vehicle system and must ... more Terrain topology is the principal source of vertical excitation into the vehicle system and must be accurately represented in order to correctly predict the vehicle response. It is desirable to evaluate vehicle models over a wide range of terrain, but it is computationally impractical to simulate long distances of every terrain type. A method to parsimoniously characterize terrain topology is developed in this work so that terrain can be grouped into meaningful sets with similar topological characteristics. Specifically, measured terrain profiles are considered realizations of an underlying stochastic process; an autoregressive model and a residual process provide the mathematical framework to describe this process. A statistical test is developed to determine if the residual process is independent and identically distributed (IID) and, therefore, stationary. A reference joint probability distribution of the residuals is constructed based on the assumption that the data are realizat...
SPIE Proceedings, 2007
Chassis loads and vehicle handling are primarily impacted by the road surface over which a vehicl... more Chassis loads and vehicle handling are primarily impacted by the road surface over which a vehicle is traversing. By accurately measuring the geometries of road surfaces, one can generate computer models of these surfaces that will allow more accurate predictions of the loads introduced to various vehicle components. However, the logistics and computational power necessary to handle such large data files makes this problem a difficult one to resolve, especially when vehicle design deadlines are impending. This work aims to improve this process by developing Markov Chain models by which all relevant characteristics of road surface geometries will be represented in the model. This will reduce the logistical difficulties that are presented when attempting to collect data and run a simulation using large data sets of individual roads. Models will be generated primarily from measured road profiles of highways in the United States. Any synthetic road realized from a particular model is representative of all profiles in the set from which the model was derived. Realizations of any length can then be generated allowing efficient simulation and timely information about chassis loads that can be used to make better informed design decisions, more quickly.
SAE International Journal of Passenger Cars - Mechanical Systems, 2014
SAE Technical Paper Series, 2003
The U.S. Army uses the root mean squared of elevation, or the RMSE standard for characterizing ro... more The U.S. Army uses the root mean squared of elevation, or the RMSE standard for characterizing road/off-road roughness descriptions. This standard has often appeared in contracts as a performance requirement for the vehicle system. One important application of the standard is describing the testing environment for the vehicle. A physical test, which uses the standard, is the 30,000 mile endurance test. More recently, another metric has been used, the power spectral density (PSD) of road roughness. The international standard for road roughness is known as the International Roughness Index (IRI), and all road construction projects in the U.S. are based on this, as well as Department of Transportation analyses. This paper will analyze the different standards by comparing and contrasting the various aspects of each. Depending on the standard and metrics chosen, the simulation results will have different correlations with actual test. The goal is to better understand each standards limitations and how it affects the correlations.
ETS Research Bulletin Series, 1971
Journal of Paramedic Practice, 2014
A tension pneumothorax is an important reversible cause of deterioration in the multiply-injured ... more A tension pneumothorax is an important reversible cause of deterioration in the multiply-injured patient, but it is not always easy to make the diagnosis. Features that indicate the development of a tension pneumothorax can be subtle in the spontaneously breathing patient. The ‘classical’ features may not all be present and in addition, the clinical signs of tension may develop over time with increasing patient compromise. This is a life-threatening situation, which requires relief in order to save the patient's life. A tension pneumothorax can be managed in one of three ways: needle decompression, insertion of an intercostal chest drain or by open thoracostomy. Needle decompression can be performed quickly and safely by paramedic crews using well-established techniques in both the conscious and unconscious patient. We describe a case of a 55-year-old male who was ejected from his motorcycle at high speed. He was conscious with a Glasgow Coma Score (GCS) of 15 and complaining of difficulty breathing. In c...
Social Policy & Administration, 2001
Magnetic Resonance Imaging, 1994
OAH Magazine of History, 2001
Journal of Strategic Studies, 1987
Journal of Social Policy, 2002
Journal of Policy Analysis and Management, 1986
The Journal of Military History, 2008
The Journal of Military History, 1999
The Journal of Military History, 1998
Journal of Dynamic Systems, Measurement, and Control, 2013
Terrain topology is the principal source of vertical excitation to the vehicle system and must be... more Terrain topology is the principal source of vertical excitation to the vehicle system and must be accurately represented in order to correctly predict the vehicle response. It is desirable to evaluate vehicle and tire models over a wide range of terrain types, but it is computationally impractical to simulate long distances of every terrain variation. This work seeks to study the terrain surface, rather than the terrain profile, to maximize the information available to the tire model (i.e., wheel path data), yet represent it in a compact form. A method to decompose the terrain surface as a combination of deterministic and stochastic components is presented. If some, or all, of the components of the terrain surface are considered to be stochastic, then the sequence can be modeled as a stochastic process. These stochastic representations of terrain surfaces can then be implemented in tire and vehicle models to predict chassis loads.
Journal of Dynamic Systems, Measurement, and Control, 2012
Terrain is the principal source of vertical excitation to the vehicle and must be accurately repr... more Terrain is the principal source of vertical excitation to the vehicle and must be accurately represented in order to correctly predict the vehicle response. Ideally, an efficient terrain surface definition could be developed that maintains the high-fidelity information required to accurately excite vehicle models. It is also desirable to minimize the effect of the choice of measurement system used to sample the terrain surface. Nondeformable, anisotropic (path-specific) terrain surfaces are defined as a sequence of vectors, where each vector comprises terrain heights at locations oriented perpendicular to the direction of travel. A vector space is formed by the span of these vectors and a corresponding set of empirical basis vectors is developed. A set of analytic basis vectors is formed from Gegenbauer polynomials, parameterized to approximate the empirical basis vectors. A weighted inner product is defined to form a Hilbert space and the terrain surface vectors are projected onto ...
Journal of Dynamic Systems, Measurement, and Control, 2012
Terrain topology is the principal source of vertical excitation into the vehicle system and must ... more Terrain topology is the principal source of vertical excitation into the vehicle system and must be accurately represented in order to correctly predict the vehicle response. It is desirable to evaluate vehicle models over a wide range of terrain, but it is computationally impractical to simulate long distances of every terrain type. A method to parsimoniously characterize terrain topology is developed in this work so that terrain can be grouped into meaningful sets with similar topological characteristics. Specifically, measured terrain profiles are considered realizations of an underlying stochastic process; an autoregressive model and a residual process provide the mathematical framework to describe this process. A statistical test is developed to determine if the residual process is independent and identically distributed (IID) and, therefore, stationary. A reference joint probability distribution of the residuals is constructed based on the assumption that the data are realizat...