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A Generalized Predictive Kinetic Energy Controller (GPKEC), which has been previously developed, is implemented to control the machine tool vibration in a lathe turning process. The control variable, tool feed, is computed using acceleration feedback through the GPKEC algorithm. The feed is controlled by attaching a high torque/low inertia permanent magnet DC servomotor to the main feed rod through a high performance timing belt. Experiments are carried out for a number of cases. The system identification of the overall machining process is done on-line and precedes the control action. Accelerometers have been used to sense the vibration signal in the feed direction. The experimental results show that GPKEC can effectively suppress the chatter vibration in a single point turning process, even in presence of an appreciable change in the dynamics of the process. GPKEC has also been observed to be robust against step disturbances.

Electron beam (EB) welding process is characterized by an extremely high power density that is capable of producing weld seams which are considerably deeper than width. Unlike other welding process, heat of EB welding is provided by the kinetic energy of electrons. This paper presents a computational model for the numerical prediction of microstructure and residual stress resulting from EB welding process. Energy input is modeled as a step function within the fusion zone. The predicted values from finite element simulation of the EB welding process agree well with the experimentally measured values. The present model is used to study an axial weld failure problem.

Over the past decade there has been a resurgence of interest in applying “artificial” intelligence techniques to control and decision-making systems. This paper surveys the applications of two artificial intelligence techniques, viz., neural networks and fuzzy logic, to earthmoving machine systems control. Neural networks can be thought of as a class of computational models that represent nonlinear input-output mappings, while fuzzy logic aims to capture the knowledge of experts in the form of rules expressed in linguistic terms. The papers reviewed cover their application to machine control, engine control, transmission control, diagnostics and prognostics, operator modeling, and other related applications.

Proper hydraulic pump inlet pressure conditions are critical for proper operation of hydraulic systems. This is especially true when water-containing hydraulic fluids are used as direct replacements for mineral oil or synthetic esters. In this paper, the importance of proper inlet conditions on hydraulic system performance will be reviewed. Also provided are various reservoir design recommendations that should be followed when using water-containing hydraulic fluids such as water-glycol (HFC) hydraulic fluids.

The development of automated guidance for agricultural tractors has addressed several basic and applied issues of agricultural equipment automation. Basic analyses have included the dynamics of steering systems and posture sensors for guidance. Applied issues have evaluated the potential of several commercial sensing systems and a commercial mechanical guidance system. A research platform has been developed based on a Case 7220 Magnum1 2-wheel drive agricultural tractor. An electrohydraulic steering system was used and characterized in support of automated guidance control. Posture sensing methods were developed using GPS, geomagnetic direction sensors (GDS), inertial, and machine vision sensing systems. Sensor fusion of GPS-inertial-machine vision and GPS-GDS-machine vision provided the most flexible and accurate guidance and capable for operation under dynamically changing field conditions.

This paper describes a strategy that allows a vehicle builder to quickly design and build an electrical communication and control system infrastructure. The power, ground, and communication infrastructure connects readily available operator interfaces and other electromechanical devices together with high level controllers to provide a complete vehicle electrical system.

This paper introduces a new generation high-performance hydraulic fluid: polyether polyol. The fluid's patented chemistry, along with its biodegradable, fire-resistant and high-pressure performance characteristics will be described. Seven years of field experience, in various pieces of mobile equipment, will also be discussed.

New trends in aircraft design suggest that there may be a mission advantage to placing the aircraft engine in backwards for applications in Unmanned Combat Air Vehicles (UCAV’s). These aircraft use stealth as their primary defense. Stealth is, therefore, of utmost importance leaving aerodynamics to take a lower priority in the design process. The combination of a flying wing, planform shape, airfoil and stability and control of these aircraft limit the maximum lift coefficient of the vehicle to a relatively low value. Increasing the maximum lift coefficient can be achieved by use of thrust vectoring forward of the center of gravity. This suggests an internal layout that places the engine flow opposite to that of the free stream. This design is currently being developed in an Embry-Riddle Aeronautical University undergraduate design course.

This paper discusses development of the scheduled maintenance development and testing methods for maintaining High Intensity Radiated Fields and Lightning (HIRF/L) protection on the Boeing 777 airplane. It describes HIRF/L, the effects of HIRF/L on the 777 airplane, and the engineering design that provides HIRF/L protection for 777 critical and essential systems. The main body of the paper discusses development of a scheduled maintenance program to maintain safety and continued airworthiness for the HIRF/L design on the 777. It includes the rationale and engineering judgment used in developing the maintenance program for this first completely fly-by-wire (FBW) Boeing airplane.

A new Aircraft Accident Awareness Program (AAAP) was developed, evaluated, and is available to emergency response service provider organizations (firefighters, emergency medical technicians, trauma center personnel, law enforcement, clergy, coroners, and media) who would be called to an aircraft accident scene. Aircraft accident responder training is a critical factor in accident victim crash survivability and successful life-safety outcomes. This program was designed to teach participants about the unique conditions and safety hazards associated with aircraft crashes. A blend of academic classroom investigation, exposure to airworthy/ unairworthy aircraft including operating systems and components, computer accident simulations, “hands-on” (destructive) extrication protocol training, and participation in simulated in-the-field accident scenarios was used as an instructional delivery model.

This paper presents a top-down methodology for causal analysis of fatal aviation accidents. The methodology incorporates a three tiered hierarchical approach to analyze accident causes and factors. These include looking at the big picture or “profile” of accident categories, followed by a detailed analysis that “fingerprints” each profile. Finally, an in-depth analysis is performed for each fingerprint which produces a “DNA” sequence breakdown for each accident category. The paper includes analysis results of National Transportation Safety Board (NTSB) accidents from 1990-1996. Key areas are identified which most significantly impact current accident rates. This includes a ranking by accident type as well as identifying focus areas for future research.

Airports and airlines can experience some of the most severe types of weather conditions during the winter season. Winter weather can also adversely affect flight operations as well as flight safety. Severe winter weather, such as freezing rain and snow, is one of the most difficult types of weather phenomenon to predict and prepare for from an airport and airline operations standpoint. Freezing rain and snow affects not only the airport runways, taxiways and aircraft, but the entire airport infrastructure as well, with the potential of incurring long and costly delays. The Weather Support to Deicing Decision Making (WSDDM) system provides help in managing airport ground operations during severe winter weather. WSDDM is a winter weather nowcasting tool that provides real-time meteorological and snow gauge data in a simple, concise, easy to understand nonmeteorological format.

Flight accidents with modern aircraft are often a result of complex dynamics of the “pilot (automaton1) - vehicle - operational environment” system. When a “critical mass” of the system’s complexity exceeds a certain level, a “chain reaction” of irreversible cause-and-effect links can be spontaneously triggered in the system behavior leading to a catastrophe. An affordable, practically tested technique is proposed to complement current methods of flight accident analysis. A generic situational model of the system behavior and a computer are employed as a virtual test article. This model includes a six-degree-of-freedom non-linear flight dynamics model, a generic situational pilot model (“silicon pilot”), models of anticipated operational factors (conditions), and a tool for flight scenario planning. Available flight recorder data are used to tune the model and reconstruct the accident.

The ultimate goal of knowledge-based aircraft design, pilot training and flight operations is to make flight safety an inherent, built-in feature of the flight vehicle, such as its aerodynamics, strength, economics and comfort are. Individual flight accidents and incidents may vary in terms of quantitative characteristics, circumstances, and other external details. However, their cause-and-effect patterns often reveal invariant structure or essential causal chains which may re-occur in the future for the same or other vehicle types. The identification of invariant logical patterns from flight accident reports, time-histories and other data sources is very important for enhancing flight safety at the level of the ‘pilot - vehicle -operational conditions’ system. The objective of this research project was to develop and assess a method for ‘mining’ knowledge of typical cause-and-effect patterns from flight accidents and incidents.

This paper is an explanation of some of the Flight Test Safety (FTS) methods used to reduce the risk associated with military rotorcraft development. Two flight test programs are addressed, the V-22 Osprey tiltrotor and the RAH-66 Comanche helicopter. A short history of the development of each program is provided as background information. Some of the challenges and strengths of joint ventures are also identified and discussed. Four critical elements of an FTS program are identified: 1) Organizational Risk Management (ORM), 2) issue/anomaly resolution, 3) incident recording and corrective action documentation and 4) interface between FTS and other organizations. Methods used in the two programs to address these elements are reviewed and can be applied to other flight test programs.

In situations of unanticipated maneuvers of an aircraft, information must be immediately received by the aircrew for correcting the aircraft flight path to a safe trajectory for continued flight and landing. These maneuvers may be due to failures in the control system, wind gust upsets, or other off-nominal conditions. Also critical are situations of control maneuvers that exceed the normal flight envelope of the aircraft, and providing information to the pilot and control system that will result in safe return to controllable flight. The Intelligent Damage Adaptive Control System (IDACS) operates during flight to detect dangerous conditions of the aircraft and to provide the crew with assistance to restore and to maintain safe control. This system is being developed by Boeing for NASA.

Safety is central to the maintenance program philosophy of today’s Air Carriers. Both MSG-2 and MSG-3 analysis procedures/logic have been used to develop a majority of the routine scheduled maintenance and inspection programs of Transport Category Air Carriers (those that operate under 14 CFR 121 [Title 14, Code of Federal Regulations, Part 121]; a.k.a., FAR 121). MSG-3 is a significant procedural shift from MSG-2; providing a more comprehensive decision logic flow, a “top down” consequence of failure approach, separating evident and hidden functional failures, clearly distinguishing safety related consequences from economic/operational consequences, and resulting in a more easily understood task-oriented program. This paper does not replace formal MSG-3 training, nor fully detail transitioning maintenance programs, but simply focuses on the safety benefits derived from the effort required to convert an existing MSG-2 derived program to MSG-3.

United Airlines has been operating long range, two-engined aircraft in ETOPS (Extended Range Operation with Two Engine Airplanes) for almost nine years. During that time, the shared industry experience and in-service operating results have created changes in the maintenance program and plan, and led to policies which have altered fleet operations. With an emphasis on safety-of-operations, this paper identifies lessons learned from experience and it also documents the adjustments to the maintenance program and policies.

The title “Advances in U.S. Air Force (USAF) Safety Equipment” is a slight misnomer in that most safety equipment advances have been accomplished through contractual partnerships with industry. However, there has been one development targeted to military operations that is transferable to civil aviation. This paper will show safety equipment priorities in the context of mishaps the USAF has experienced. It will then show current fleet status with respect to safety equipment installed and funded future upgrades. Lastly, the paper will discuss a system that will virtually eliminate Controlled Flight Into Terrain (CFIT).

The US Army Research Laboratory performed a failure investigation on a broken main landing gear mount from an AH-64 Apache attack helicopter. This “infinite-life” component had failed in flight, and initially prevented the helicopter from safely landing. In order to avoid a catastrophe, the pilot had to perform a low hover maneuver to the maintenance facility, where ground crews assembled concrete blocks at the appropriate height to allow the aircraft to safely touch down. The failed part was fabricated from maraging 300 grade steel (2,068 Mpa [300 ksi] ultimate tensile strength), and was subjected to visual inspection/light optical microscopy, metallography, electron microscopy, energy dispersive spectroscopy, chemical analysis, and mechanical testing. It was observed that the vacuum cadmium coating adjacent to the fracture plane had worn off and corroded in service, thus allowing pitting corrosion to occur.