Critical Impact Points for Transitions and Terminals

2002 ◽  
Vol 1797 (1) ◽  
pp. 105-112
Author(s):  
Roger P. Bligh ◽  
King K. Mak
Keyword(s):  
Safety Performance ◽  
Worst Case ◽  
Roadside Safety ◽  
Simulation Techniques ◽  
Crash Testing ◽  
Families Of Curves ◽  
Impact Location ◽  
Safety Features ◽  
Computer Simulation Techniques ◽  
Selection Of

Guidelines for evaluating the safety performance of roadside safety features generally recommend that a worst case or critical impact point (CIP) be selected for crash testing. NCHRP Report 350 presents families of curves that can be used to determine the CIP for a transition section. However, these curves have been observed to overestimate the stiffness of a transition system and provide CIP values closer to the more rigid system of the transition (e.g., bridge rail end) than appropriate. New CIP selection curves for transitions are presented. A procedure is provided to aid in determining the CIP for transition sections with multiple rail elements or variations in post strength and post spacing. Various existing and theoretical transitions systems with wide-ranging combinations of beam and post strengths were used to validate the curves. The newly developed CIP relationships for transitions are recommended in lieu of the existing relationships contained in NCHRP Report 350. To facilitate the development of guidelines for the selection of a CIP for terminals, a new definition is proposed. The proposed definition for the CIP is the point along the terminal at which vehicle behavior transitions from gating to redirection. A methodology for determining the CIP using computer simulation techniques is investigated. The data clearly demonstrate that the selection of a single default impact location for all terminal configurations may not provide the CIP for many designs.

Simulation of a Crash Test of Minnesota’s Aluminum Type III Barricade

2004 ◽  
Author(s):  
Gale L. Paulsen ◽  
John D. Reid
Keyword(s):  
Contact Friction ◽  
Crash Test ◽  
Element Analysis ◽  
Roadside Safety ◽  
Vehicle Simulation ◽  
Type Iii ◽  
Crash Testing ◽  
Impact Location ◽  
The Impact ◽  
Being Moved

Full-scale crash testing was performed on Minnesota’s Aluminum Type III Barricade by the Midwest Roadside Safety Facility. Testing consisted of an 820 kg vehicle impacting the barricade at two positions, 0 and 90-degrees, at 100 km/h. This paper documents the modeling effort to simulate the physical crash events using LS-DYNA, a nonlinear finite element analysis program. As is typical for vehicle crash simulation, there were many modeling issues that needed careful attention. Four items of particular concern were (1) contact snagging - the barricade kept hooking on the hood with edge to edge snagging; (2) placement of barricade - small adjustments to the impact location could cause the tire to run over one of the barricade legs, which did not happen during the testing; (3) contact friction - the friction between the barricade and the front of the vehicle played an important role in how the barricade wrapped around and flipped off of the vehicle, and (4) sandbag weight - the weight of the sandbags, which are placed on the legs of the barricade and are used to prevent the barricades from being moved by the wind, makes a difference on how the sign legs flip up into the air when impacted by a vehicle. Simulation results are shown to be fairly accurate for both impact conditions. Future studies on various barricade configurations are now possible using the model developed during this research.

Computer simulations of ABC transporter componentsThis paper is one of a selection of papers published in this Special Issue, entitled CSBMCB — Membrane Proteins in Health and Disease.

2006 ◽  
Vol 84 (6) ◽  
pp. 900-911 ◽  
Author(s):  
Eliud O. Oloo ◽  
Christian Kandt ◽  
Megan L. O’Mara ◽  
D. Peter Tieleman
Keyword(s):  
Abc Transporters ◽  
Simulation Techniques ◽  
Multiple Components ◽  
Functional Dynamics ◽  
Future Challenges ◽  
Health And Disease ◽  
Dynamics Simulations ◽  
Functional Mechanisms ◽  
Computer Simulation Techniques ◽  
Selection Of

Current computer simulation techniques provide robust tools for studying the detailed structure and functional dynamics of proteins, as well as their interaction with each other and with other biomolecules. In this minireview, we provide an illustration of recent progress and future challenges in computer modeling by discussing computational studies of ATP-binding cassette (ABC) transporters. ABC transporters have multiple components that work in a well coordinated fashion to enable active transport across membranes. The mechanism by which members of this superfamily execute transport remains largely unknown. Molecular dynamics simulations initiated from high-resolution crystal structures of several ABC transporters have proven to be useful in the investigation of the nature of conformational coupling events that may drive transport. In addition, fruitful efforts have been made to predict unknown structures of medically relevant ABC transporters, such as P-glycoprotein, using homology-based computational methods. The various techniques described here are also applicable to gaining an atomically detailed understanding of the functional mechanisms of proteins in general.

NCHRP Report 350 Compliance Tests of the ET-2000

1996 ◽  
Vol 1528 (1) ◽  
pp. 28-37 ◽  
Author(s):  
Hayes E. Ross ◽  
Wanda L. Menges ◽  
D. Lance Bullard
Keyword(s):  
Evaluation Criteria ◽  
Passenger Car ◽  
Roadside Safety ◽  
Impact Performance ◽  
Crash Testing ◽  
Level 3 ◽  
New Guidelines ◽  
Safety Features ◽  
The Impact ◽  
Crash Tests

The ET-2000 is one of the end treatments currently approved for use with W-beam guardrail systems. The ET-2000 has successfully met all evaluation criteria set forth in NCHRP Report 230. However, with the adoption of NCHRP Report 350 by FHWA as the official guidelines for crash testing of roadside safety features, it became necessary to reevaluate the ET-2000 to the new guidelines. It is noted that one of the design test vehicles specified in NCHRP Report 230, the 2044-kg passenger car, was replaced by a 2000-kg pickup truck (2000P) under NCHRP Report 350 guidelines. The purpose of the crash tests was to evaluate the ET-2000 according to NCHRP Report 350 guidelines. The ET-2000 met NCHRP Report 350 criteria for Performance Level 3 without any design modifications. All findings in this study demonstrate that the impact performance of the ET-2000 was satisfactory.

Development, Crash Testing, and Evaluation of Steel-Post Trailing-End Guardrail Anchorage System

2021 ◽  
pp. 036119812110319
Author(s):  
Mojdeh Asadollahi Pajouh ◽  
Karla Lechtenberg ◽  
Ronald Faller ◽  
Tewodros Yosef
Keyword(s):  
Safety Performance ◽  
Reverse Direction ◽  
Roadside Safety ◽  
Safety Requirements ◽  
Component Testing ◽  
Crash Testing ◽  
Anchorage System ◽  
Structural Capacity ◽  
Departments Of Transportation ◽  
Crash Tests

Trailing-end guardrail anchorage systems are widely used by most state departments of transportation (DOTs) and generally consist of simple adaptations of crashworthy end terminals. The safety performance and structural capacity of these trailing-end anchorage systems, when reverse-direction impacts occur near the end, is imperative in crashworthiness of guardrail systems. In 2013, a non-proprietary trailing-end anchorage system with a modified breakaway cable terminal (BCT) was developed by the Midwest Roadside Safety Facility (MwRSF) for the Midwest Guardrail System (MGS). Although this trailing-end guardrail anchorage system adequately met the Manual for Assessing Safety Hardware (MASH) TL-3 safety requirements, the use of two breakaway wood posts was deemed by some users to have several drawbacks. Thus, there was a critical need to develop a non-wood option to anchor the downstream end of the W-beam guardrail system, which led to the need to develop a steel-post trailing-end guardrail anchorage system for use with the MGS. Following the design and component testing of such a system, two full-scale crash tests were performed according to the MASH 2016 test designation nos. 3-37a and 3-37b. In the first test, a 2270P pickup truck struck the guardrail system and was adequately contained and redirected. In the second test, an 1100C small car struck the barrier and safely gated through the barrier. Both tests were deemed acceptable according to TL-3 safety criteria in MASH 2016. Recommendations are provided for the installation of a steel-post trailing-end guardrail anchorage system when used in combination with MGS.

Development of a Standardized Buttress for Approach Guardrail Transitions

2018 ◽  
Vol 2672 (39) ◽  
pp. 41-51
Author(s):  
Scott K. Rosenbaugh ◽  
Jennifer D. Schmidt ◽  
Ronald K. Faller
Keyword(s):  
Full Scale ◽  
Safety Performance ◽  
Span Length ◽  
Case Scenario ◽  
Worst Case ◽  
Worst Case Scenario ◽  
Crash Testing

Approach guardrail transitions (AGTs) incorporate increased post and rail sizes, reduced post spacings, and specialized buttress end geometries to smoothly transition from deformable W-beam guardrail to rigid barriers. This transition in barrier stiffness makes AGTs sensitive systems that require specific combinations of these components to function properly. Changing components, or even the removal of a curb below the rail, can negatively affect the safety performance of an otherwise crashworthy system. However, recent full-scale crash testing has indicated that a properly designed buttress at the downstream end of an AGT may be utilized with multiple AGT systems. Thus, the objective of this project was to develop a standardized buttress to reduce vehicle snag and be compatible with a wide variety of previously developed Thrie beam AGT systems, either with or without a curb. The standardized buttress was designed with a dual taper on its front upstream edge. A longer lower taper was designed to mitigate tire snag below the rail, while a shorter upper taper was designed to prevent vehicle snag and limit the unsupported span length of the rail. This buttress design was evaluated in combination with a critically weak AGT without a curb, which represented the worst-case scenario. The standardized buttress was successfully crash tested to MASH TL-3. Guidance was provided for both the attachment of the buttress to various Thrie beam AGTs as well as how to transition the shape of the buttress to adjacent bridge rails or rigid parapets downstream of the AGT.

Image Analysis of Intramembrane Particles in Freeze-Fractured Biomembranes Using Computer Simulation Techniques

1975 ◽  
Vol 33 ◽  
pp. 214-215
Author(s):  
D.J. Benefiel ◽  
R.S. Weinstein
Keyword(s):  
Membrane Proteins ◽  
Freeze Fracture ◽  
Integral Membrane Proteins ◽  
Systematic Evaluation ◽  
Intramembrane Particles ◽  
Modeling Methods ◽  
Simulation Techniques ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron ◽  
Computer Simulation Techniques

Intramembrane particles (IMP or MAP) are components of most biomembranes. They are visualized by freeze-fracture electron microscopy, and they probably represent replicas of integral membrane proteins. The presence of MAP in biomembranes has been extensively investigated but their detailed ultrastructure has been largely ignored. In this study, we have attempted to lay groundwork for a systematic evaluation of MAP ultrastructure. Using mathematical modeling methods, we have simulated the electron optical appearances of idealized globular proteins as they might be expected to appear in replicas under defined conditions. By comparing these images with the apearances of MAPs in replicas, we have attempted to evaluate dimensional and shape distortions that may be introduced by the freeze-fracture technique and further to deduce the actual shapes of integral membrane proteins from their freezefracture images.

scholarly journals Selection of Optimal Magnets for Traction Motors to Prevent Demagnetization

Machines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 124
Author(s):  
Dantam Rao ◽  
Madhan Bagianathan
Keyword(s):  
Flux Density ◽  
Electric Vehicles ◽  
Parallel Line ◽  
Low Grade ◽  
Lower Grade ◽  
Worst Case ◽  
Traction Motors ◽  
Knee Point ◽  
Point Of Intersection ◽  
Selection Of

Currently, permanent-magnet-type traction motors drive most electric vehicles. However, the potential demagnetization of magnets in these motors limits the performance of an electric vehicle. It is well known that during severe duty, the magnets are demagnetized if they operate beyond a ‘knee point’ in the B(H) curve. We show herein that the classic knee point definition can degrade a magnet by up to 4 grades. To prevent consequent excessive loss in performance, this paper defines the knee point k as the point of intersection of the B(H) curve and a parallel line that limits the reduction in its residual flux density to 1%. We show that operating above such a knee point will not be demagnetizing the magnets. It will also prevent a magnet from degenerating to a lower grade. The flux density at such a knee point, termed demag flux density, characterizes the onset of demagnetization. It rightly reflects the value of a magnet, so can be used as a basis to price the magnets. Including such knee points in the purchase specifications also helps avoid the penalty of getting the performance of a low-grade magnet out of a high-grade magnet. It also facilitates an accurate demagnetization analysis of traction motors in the worst-case conditions.

Boiler Implosion Control in Fossil Fuel Power Plants

1985 ◽  
Vol 107 (4) ◽  
pp. 267-269 ◽  
Author(s):  
S. Z. Wu ◽  
D. N. Wormley ◽  
D. Rowell ◽  
P. Griffith
Keyword(s):  
Power Plants ◽  
Fossil Fuel ◽  
Companion Paper ◽  
Simulation Techniques ◽  
Power Plant Boiler ◽  
Induced Draft Fan ◽  
Fossil Fuel Power Plants ◽  
Computer Simulation Techniques ◽  
Plant Boiler ◽  
Furnace Pressure

An evaluation of systems for control of fossil fuel power plant boiler and stack implosions has been performed using computer simulation techniques described in a companion paper. The simulations have shown that forced and induced draft fan control systems and induced draft fan bypass systems reduce the furnace pressure excursions significantly following a main fuel trip. The limitations of these systems are associated with actuator range and response time and stack pressure excursions during control actions. Preliminary study suggests that an alternative control solution may be achieved by discharging steam into the furnace after a fuel trip.

Three-dimensional predator–prey interactions: a computer simulation of bird flocks and aircraft

1986 ◽  
Vol 64 (11) ◽  
pp. 2624-2633 ◽  
Author(s):  
Peter F. Major ◽  
Lawrence M. Dill ◽  
David M. Eaves
Keyword(s):  
Computer Simulation ◽  
Prey Species ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Aquatic Environments ◽  
Aircraft Engines ◽  
Predator Prey ◽  
Simulation Techniques ◽  
Computer Simulation Techniques ◽  
Individual Prey

Three-dimensional interactions between grouped aerial predators (frontal discs of aircraft engines), either linearly arrayed or clustered, and flocks of small birds were studied using interactive computer simulation techniques. Each predator modelled was orders of magnitude larger than an individual prey, but the prey flock was larger than each predator. Expected numbers of individual prey captured from flocks were determined for various predator speeds and trajectories, flock–predator initial distances and angles, and flock sizes, shapes, densities, trajectories, and speeds. Generally, larger predators and clustered predators caught more prey. The simulation techniques employed in this study may also prove useful in studies of predator–prey interactions between schools or swarms of small aquatic prey species and their much larger vertebrate predators, such as mysticete cetaceans.The study also provides a method to study problems associated with turbine aircraft engine damage caused by the ingestion of small flocking birds, as well as net sampling of organisms in open aquatic environments.

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