Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “collision operators”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

The applications of satellites to communications, navigation and surveillance for aircraft operating over the contiguous United States

The objective was to determine on a priority basis the satellite applications to communications, navigation, and surveillance requirements for aircraft operating beyond 1975 over the contiguous United States and adjacent oceanic transition regions, and to determine if and how satellite technology can meet these requirements in a reliable, efficient, and economical manner. Major results and conclusions are as follows: (1) The satellite applications of greatest importance are surveillance and rapid collision warning communications; and (2) The necessary technology is available as demonstrated by an attractive system concept.

Craigie, J. H.↗
NASA NTRS1980

AMTV headway sensor and safety design

A headway sensing system for an automated mixed traffic vehicle (AMTV) employing an array of optical proximity sensor elements is described, and its performance is presented in terms of object detection profiles. The problem of sensing in turns is explored experimentally and requirements for future turn sensors are discussed. A recommended headway sensor configuration, employing multiple source elements in the focal plane of one lens operating together with a similar detector unit, is described. Alternative concepts including laser radar, ultrasonic sensing, imaging techniques, and radar are compared to the present proximity sensor approach. Design concepts for an AMTV body which will minimize the probability of injury to pedestrians or passengers in the event of a collision are presented.

Johnston, A. R.↗
NASA NTRS1990

Modelling and performance analysis of four and eight element TCAS

This semi-annual report describes the work performed during the period September 1989 through March 1990. The first section presents a description of the effect of the engines of the Boeing 737-200 on the performance of a bottom mounted eight-element traffic alert and collision avoidance system (TCAS). The second section deals exclusively with a four element TCAS antenna. The model obtained to simulate the four element TCAS and new algorithms developed for studying its performance are described. The effect of location on its performance when mounted on top of a Boeing 737-200 operating at 1060 MHz is discussed. It was found that the four element TCAS generally does not perform as well as the eight element TCAS III.

Sampath, K. S.↗
NASA NTRS1998

Sensitivity Analysis of Data Link Alternatives for LVLASO

As part of this research, we have modeled the Mode-S system when used to enhance communications among several ground vehicles to facilitate low-visibility landing and surface operations. The model has then been simulated using Bones Designer software. The effectiveness of the model has been evaluated under several conditions: (i) different number of vehicles (100, 200, and 300), (ii) different distributions of interarrival times for squitters: uniform, exponential, and constrained exponential, and (iii) Different safe distances (for collision purpose): squitter length, 1.5*squitter length, and 2* squitter length. The model has been developed in a modular fashion to facilitate any future modifications. The results from the simulations suggest that the Mode S system is indeed capable of functioning satisfactorily even when covering up to 300 vehicles. Certainly, about 10 percent of the squitters undergo collisions and hence the interarrival times for these is much larger than the expected time of 500 msec. In fact, the delay could be as much as 2 seconds. The model could be further enhanced to incorporate more realistic scenarios.

Mukkamala, Ravi↗
NASA NTRS2001

A Decade of Growth

This paper examines the Space Surveillance Network catalog's growth in low Earth orbit (LEO) and the geosynchronous Earth orbit (GEO) over the decade 1990-2000. During this time, innovative space utilization concepts, e.g. the Iridium and Globalstar commercial communication satellite constellations, have increased the public's consciousness of space. At the same time, however, these constellations have increased spatial density per 10 km altitude bin by factors of two and three respectively. While not displaying as spectacular a growth in spatial density, other regions of space have grown steadily in terms of number, mass, size, and operational lifetime. In this work we categorize launch traffic by type (e.g. payload, rocket body, operational debris, fragmentation debris, or anomalous debris), mass, and size so as to present the observed growth numerically, in terms of mass, and in terms of cross-sectional area. GEO traffic is further categorized by operational longitude. Because growth itself defines only the instantaneous environment, we also examine the higher-order derivatives of growth. In addition, we compare the last decade's growth with modeling results to illustrate the subtle effects of inclination, eccentricity, and size, in addition to spatial densities, on estimating the collision probability. We identify those regions of space most subject to accidental collision.

Johnson, Nicholas L.↗
NASA NTRS2018

Warning Alert HITL Experiment Results

Minimum Operational Performance Standards (MOPS) are being developed to support the integration of Unmanned Aircraft Systems (UAS) in the National Airspace (NAS). Input from subject matter experts and multiple research studies have informed display requirements for Detect-and-Avoid (DAA) systems aimed at supporting timely and appropriate pilot responses to collision hazards. Phase 1 DAA MOPS alerting is designed to inform pilots if an avoidance maneuver is necessary; the two highest alert levels - caution and warning - indicate how soon pilot action is required and whether there is adequate time to coordinate with the air traffic controller (ATC). Additional empirical support is needed to clarify the extent to which warning-level alerting impacts DAA task performance. The present study explores the differential effects of the auditory and visual cues provided by the DAA Warning alert, and performance implications compared to caution-only alerting are discussed.

alerting↗
DOE OSTI2026

Movement Models to Predict Low‐Altitude Flight of Soaring Birds Using Look‐Ahead Environmental Factors

Advances in fine-scale movement modeling of soaring birds can aid efforts to understand and resolve the impacts of anthropogenic activities on such birds. Soaring birds often rely on underlying terrain and low-altitude updrafts to govern their flights at rotor-swept altitudes (≤ 200 m above ground level), which puts them at risk of collision with wind turbines. We developed a data-driven Markov model at 1-s resolution that predicts the fine-scale flight behavior of golden eagles (Aquila chrysaetos) as a function of ecological covariates at the current location as well as those within an eagle's line of sight. We only considered ecological covariates that are readily available in real-time (ground elevation and wind conditions). Latent factors (age, sex, species, behavioral intent, migratory status) were intentionally left out of the model. We calibrated the model using golden eagle telemetry data collected in two different ecoregions of the United States. Given a starting location, the calibrated model simulates multiple stochastic 3D paths to produce a time-explicit and spatially explicit risk map of turbine collisions. We discovered an empirical relation between the rate of change of heading and the orographic updraft conditions within an eagle's line of sight. Our model performed most effectively when predicting predominantly-soaring flights at rotor-swept altitudes during wind conditions in which turbines are likely to be operational. The calibrated model could be used in concert with automated eagle detection and turbine curtailment technologies. Specifically, once an eagle is detected by those systems, our model could then provide accurate predictions of turbines the eagle is likely to interact with in the near term.

17 WIND ENERGY↗
DOE OSTI2022

New proposed ITER divertor design using carbon insert on tungsten to mitigate ELMs and secondary radiation effects on nearby components

Abstract Building a successful device for the magnetic fusion energy production is a great challenge. ITER is an international project of the tokamak based magnetic fusion design being developed for the demonstration of the feasibility of thermonuclear technologies for future realization of successful commercial fusion energy. A key obstacle to a successful magnetic fusion energy production is however, the performance during abnormal events including plasma disruptions and edge-localized modes (ELMs). A credible reactor design must tolerate at least a few of these transient events without serious consequences such as melting of the structure. This paper investigates and compares the performance of the current ITER tokamak design during two types of transient events, i.e., ELMs occurring at normal operation and disruptions during abnormal operation. We simulated the divertor components response using our integrated 3D HEIGHTS package. The simulations include self-consistent modeling of the interaction of the released core plasma particles with the initial solid divertor material, energy deposition processes, vaporization of divertor material, secondary plasma formation and MHD evolution, incident core particles collisions and scattering from this dense secondary plasma, photon radiation of secondary plasma, and the resulting heat loads on nearby components. Our simulations showed that using a small carbon insert around the strike point can significantly reduce the overall expected damage on the tungsten dome structure, reflector plates, and prevent tungsten vaporization and its potential core plasma contamination.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Experimental testing of particle attrition in CSP systems at high temperature

An alternate and sustainable form of energy is CSP systems, which capture and store the sun’s energy in the form of heat. Increasing the operational temperature of CSP systems will increase the efficiency of electricity production while operating at temperatures exceeding 700 degrees Celsius also creates novel operational problems. One approach for high-temperature CSP systems is to utilize solid particles as the primary heat transfer medium. As particles flow through this system, the movement of particles creates erosion in the forms of impact, abrasion, and attrition erosion. In the real world, while all three forms of erosion will occur simultaneously, it is imperative to understand the individual effect of each erosion over the lifetime of the powerplant. Besides material erosion and long-term durability concerns, thermal cycling of the particles could also introduce changes in particle thermal performance due to alterations in particle morphology. Current research on the issue of erosion has been limited to industrial applications and does not necessarily coincide with the operating conditions in CSP systems. We focus on attrition erosion resulting from particle-to-wall and particle-to-particle interactions. Research has shown that besides material hardness affecting how fast particles break down, attrition erosion increased as the size of the particles increased due to a higher chance of collision between the particles. Particle attrition is relevant to the CSP community as it may result in material loss, change the system's thermal performance, and generation of fines which could pose an environmental hazard. In this work, we focus on developing a test set up that can isolate and measure particle attrition when subjected to conditions relevant to Gen3 CSP systems.

14 SOLAR ENERGY↗
NASA NTRS1985

Quantitative analysis in megageomorphology

Megageomorphology is the study of regional topographic features and their relations to independent geomorphic variables that operate at the regional scale. These independent variables can be classified as either tectonic or climatic in nature. Quantitative megageomorphology stresses the causal relations between plate tectonic factors and landscape features or correlations between climatic factors and geomorphic processes. In addition, the cumulative effects of tectonics and climate on landscape evolution that simultaneously operate in a complex system of energy transfer is of interst. Regional topographic differentiation, say between continents and ocean floors, is largely the result of the different densities and density contrasts within the oceanic and continental lithosphere and their isostatic consequences. Regional tectonic processes that alter these lithospheric characteristics include rifting, collision, subduction, transpression and transtension.

Mayer, L.↗
NASA NTRS1989

Explosive Joining

Laurence J. Bement of Langley Research Center invented a technique to permit metal joining operations under hazardous or inaccessible conditions. The process, which provides a joint with double the strength of the parent metal, involves the use of very small quantities of ribbon explosive to create hermetically sealed joints. When the metal plates are slammed together by the explosion's force, joining is accomplished. The collision causes a skin deep melt and ejection of oxide films on the surfaces, allowing a linkup of electrons that produce superstrong, uniform joints. The technique can be used to join metals that otherwise would not join and offers advantages over mechanical fasteners and adhesives. With Langley assistance, Demex International Ltd. refined and commercialized the technology. Applications include plugging leaking tubes in feedwater heaters. Demex produces the small plugs, associated sleeves and detonators. The technology allows faster plugging, reduces downtime, cuts plugging costs and increases reliability.

Source record↗
NASA NTRSDate not supplied

Integration of Automation Systems Flight Test Overview

This short presentation outlines an upcoming flight test to be performed as part of the Advanced Air Mobility (AAM) project. Referred to as the Integration of Automated Systems (IAS) flight test series, the objectives are to evaluate NASA research concepts and technologies for complex operations through integrated automation and candidate operational concepts and scenarios. The primary objective is to test mature AAM technologies in a relevant environment. The two primary systems under test are the Flight Path Management (FPM) and Hazard Perception and Avoidance (HPA) technology. This presentation focuses on the HPA technology developed by the FAA known as the Airborne Collision Avoidance System X for Rotorcraft (ACAS Xr) since the audience consists of committee members currently working on developing the minimum requirements for this system. The second half of the presentation explains the primary objectives and describes the scenarios expected to be tested in flight.

automation↗
DOE OSTI2020

The hidden geometry of particle collisions

We establish that many fundamental concepts and techniques in quantum field theory and collider physics can be naturally understood and unified through a simple new geometric language. The idea is to equip the space of collider events with a metric, from which other geometric objects can be rigorously defined. Our analysis is based on the energy mover’s distance, which quantifies the “work” required to rearrange one event into another. This metric, which operates purely at the level of observable energy flow information, allows for a clarified definition of infrared and collinear safety and related concepts. A number of well-known collider observables can be exactly cast as the minimum distance between an event and various manifolds in this space. Jet definitions, such as exclusive cone and sequential recombination algorithms, can be directly derived by finding the closest few-particle approximation to the event. Several area- and constituent-based pileup mitigation strategies are naturally expressed in this formalism as well. Finally, we lift our reasoning to develop a precise distance between theories, which are treated as collections of events weighted by cross sections. In all of these various cases, a better understanding of existing methods in our geometric language suggests interesting new ideas and generalizations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

High Multiplicity Trigger for long-lived particles in CMS detector

Searches for long-lived particles (LLPs) at the CMS experiment often involve unconventional event topologies that are difficult to efficiently select using standard trigger strategies. To improve sensitivity to such signatures during LHC Run 3 operation, a dedicated High Multiplicity Trigger (HMT) has been developed and deployed in the CMS trigger system. The trigger targets events containing unusually large numbers of hits in the CMS cathode strip chamber (CSC) muon detectors, a characteristic signature of several LLP scenarios involving displaced decays in the muon system. The HMT implementation, trigger logic, rate dependence with pileup, and operational stability are described. Optimized hit multiplicity thresholds are used to maintain acceptable trigger rates under high-luminosity and high-pileup conditions while preserving high efficiency across a broad range of LLP lifetimes and kinematic regimes. The trigger performance is evaluated using both simulated event samples and proton-proton collision data collected during Run 3 of the LHC. The HMT substantially extends the CMS sensitivity to non-standard signatures associated with LLP decays and provides a flexible platform for future searches for physics beyond the Standard Model.

47 OTHER INSTRUMENTATION↗
NASA NTRS1989

Adjustable impedance, force feedback and command language aids for telerobotics (parts 1-4 of an 8-part MIT progress report)

Projects recently completed or in progress at MIT Man-Machine Systems Laboratory are summarized. (1) A 2-part impedance network model of a single degree of freedom remote manipulation system is presented in which a human operator at the master port interacts with a task object at the slave port in a remote location is presented. (2) The extension of the predictor concept to include force feedback and dynamic modeling of the manipulator and the environment is addressed. (3) A system was constructed to infer intent from the operator's commands and the teleoperation context, and generalize this information to interpret future commands. (4) A command language system is being designed that is robust, easy to learn, and has more natural man-machine communication. A general telerobot problem selected as an important command language context is finding a collision-free path for a robot.

Sheridan, Thomas B.↗
NASA NTRS1992

Trajectory design and navigation analysis for Cargo Transfer Vehicle proximity operations

The paper documents an investigation of alternative (or off-nominal) final approach trajectories and terminal guidance algorithms for Cargo Transfer Vehicle (CTV) automated rendezvous and proximity operation in the vicinity of Space Station Freedom (SSF). Ten candidate trajectory designs, representing a survey of all approaches that reasonably satisfy the mission constraints, are compared qualitatively and quantitatively. It is shown that several fundamentally different types of approach strategies are feasible in the CTV application and enjoy more favorable passive collision avoidance and plume impingement properties than the nominal. They are, however, generally more costly in propellant. The extent to which an alternative approach is more costly is determined largely by the abort (or specifically the 'hold' or 'wave-off') requirements. These approach techniques are verified in a software simulation using a parametrically defined candidate navigation system, and proximity sensor accuracy requirements are derived.

Marsh, S. M.↗
NASA NTRS1993

Robust algebraic image enhancement for intelligent control systems

Robust vision capability for intelligent control systems has been an elusive goal in image processing. The computationally intensive techniques a necessary for conventional image processing make real-time applications, such as object tracking and collision avoidance difficult. In order to endow an intelligent control system with the needed vision robustness, an adequate image enhancement subsystem capable of compensating for the wide variety of real-world degradations, must exist between the image capturing and the object recognition subsystems. This enhancement stage must be adaptive and must operate with consistency in the presence of both statistical and shape-based noise. To deal with this problem, we have developed an innovative algebraic approach which provides a sound mathematical framework for image representation and manipulation. Our image model provides a natural platform from which to pursue dynamic scene analysis, and its incorporation into a vision system would serve as the front-end to an intelligent control system. We have developed a unique polynomial representation of gray level imagery and applied this representation to develop polynomial operators on complex gray level scenes. This approach is highly advantageous since polynomials can be manipulated very easily, and are readily understood, thus providing a very convenient environment for image processing. Our model presents a highly structured and compact algebraic representation of grey-level images which can be viewed as fuzzy sets.

Lerner, Bao-Ting↗
NASA NTRS2004

ADS-B within a Multi-Aircraft Simulation for Distributed Air-Ground Traffic Management

Automatic Dependent Surveillance Broadcast (ADS-B) is an enabling technology for NASA s Distributed Air-Ground Traffic Management (DAG-TM) concept. DAG-TM has the goal of significantly increasing capacity within the National Airspace System, while maintaining or improving safety. Under DAG-TM, aircraft exchange state and intent information over ADS-B with other aircraft and ground stations. This information supports various surveillance functions including conflict detection and resolution, scheduling, and conformance monitoring. To conduct more rigorous concept feasibility studies, NASA Langley Research Center s PC-based Air Traffic Operations Simulation models a 1090 MHz ADS-B communication structure, based on industry standards for message content, range, and reception probability. The current ADS-B model reflects a mature operating environment and message interference effects are limited to Mode S transponder replies and ADS-B squitters. This model was recently evaluated in a Joint DAG-TM Air/Ground Coordination Experiment with NASA Ames Research Center. Message probability of reception vs. range was lower at higher traffic levels. The highest message collision probability occurred near the meter fix serving as the confluence for two arrival streams. Even the highest traffic level encountered in the experiment was significantly less than the industry standard "LA Basin 2020" scenario. Future studies will account for Mode A and C message interference (a major effect in several industry studies) and will include Mode A and C aircraft in the simulation, thereby increasing the total traffic level. These changes will support ongoing enhancements to separation assurance functions that focus on accommodating longer ADS-B information update intervals.

Barhydt, Richard↗