The use of visual cues for vehicle control and navigation

At least three levels of control are required to operate most vehicles: (1) inner-loop control to counteract the momentary effects of disturbances on vehicle position; (2) intermittent maneuvers to avoid obstacles, and (3) outer-loop control to maintain a planned route. Operators monitor dynamic optical relationships in their immediate surroundings to estimate momentary changes in forward, lateral, and vertical position, rates of change in speed and direction of motion, and distance from obstacles. The process of searching the external scene to find landmarks (for navigation) is intermittent and deliberate, while monitoring and responding to subtle changes in the visual scene (for vehicle control) is relatively continuous and 'automatic'. However, since operators may perform both tasks simultaneously, the dynamic optical cues available for a vehicle control task may be determined by the operator's direction of gaze for wayfinding. An attempt to relate the visual processes involved in vehicle control and wayfinding is presented. The frames of reference and information used by different operators (e.g., automobile drivers, airline pilots, and helicopter pilots) are reviewed with particular emphasis on the special problems encountered by helicopter pilots flying nap of the earth (NOE). The goal of this overview is to describe the context within which different vehicle control tasks are performed and to suggest ways in which the use of visual cues for geographical orientation might influence visually guided control activities

Determination of surfaces of constant inelastic strain rate at elevated temperature

An experimental effort to perform special exploratory multiaxial deformation tests on tubular specimens of type 316 stainless steel at 650 C (1200 F) is described. One test specimen was subjected to a time-independent torsional shear strain test history, and surfaces of constant inelastic strain rate (SCISRs) in an axial/torsional stress space were measured at various predetermined points during the test. A second specimen was subjected to a 14-week time-dependent (creep-recovery-creep periods) torsional shear stress histogram SCISRs determinations made at 17 points during the test. The tests were conducted in a high temperature, computer controlled axial/torsional test facility using high-temperature multiaxial extensometer. The effort was successful, and for the first time the existence of surfaces of constant inelastic strain rate was experimentally demonstrated

Thermal rearrangements in the tetra-arylcyclopropene series

The literature provides many examples of thermal rearrangements of small-ring compounds to yield systems involving less bond-angle strain. In the arylcyclopropene series these involve, in many cases, fairly complex pathways, and only formalized mechanisms have been suggested

POPCORN: a Supervisory Control Simulation for Workload and Performance Research

A multi-task simulation of a semi-automatic supervisory control system was developed to provide an environment in which training, operator strategy development, failure detection and resolution, levels of automation, and operator workload can be investigated. The goal was to develop a well-defined, but realistically complex, task that would lend itself to model-based analysis. The name of the task (POPCORN) reflects the visual display that depicts different task elements milling around waiting to be released and pop out to be performed. The operator's task was to complete each of 100 task elements that ere represented by different symbols, by selecting a target task and entering the desired a command. The simulated automatic system then completed the selected function automatically. Highly significant differences in performance, strategy, and rated workload were found as a function of all experimental manipulations (except reward/penalty)

The role of actuality in Aristotle's first philosophy

textI show how Aristotle’s theory of the priority of actuality and his theory of non-correlative actuality help prepare the way for his own positive account of the separate, non-sensible substances. Aristotle argues that actuality is prior to potentiality in Metaphysics [Theta]8, and in particular that actuality is prior in substance and in a more authoritative kind of way. I show how both of these arguments are to be understood, and how the more authoritative kind of priority (which is not substantial priority, as usually thought) is again appealed to in Metaphysics [Lamda]6 in order to draw important inferences about the primary principles. I also show how the theory of non-correlative actuality used in [Theta]8 is, just like the more authoritative kind of priority, again applied in [Lamda]6 in parallel kinds of ways. It turns out that the traditional interpretation which ascribes the notion of “pure actuality” to Aristotle is mistaken, and this comes to light once Aristotle’s theory of non-correlative actuality is properly understood and the texts are properly interpreted.Philosoph

Using Green Building to Mitigate Climate Change in the Twenty-First Century

The need for green buildings are rapidly becoming more important as the nation faces impending energy crises and the world heats up from the overabundance of greenhouse gases. Buildings in America are one of the largest consumers of energy and one of the greatest contributors to CO2 emissions; more than the total emissions from all the transportation vehicles used every day. By making the construction and use of buildings more resource efficient, this can help alleviate the environmental strain of climate change. Neutralizing or eliminating carbon emissions from building use will significantly reduce the amount of greenhouse gases in the atmosphere and is a single most effective way to begin the reversal of climate change. Making this shift in the building industry will not be easy but is certainly possible at this moment in time. Cooperation from the government, the public, and the market is critical to help make sustainable building mainstream. Voluntary measures already in place can be revamped to appeal to more people and the introduction of green building codes and standards can work together to achieve this goal of the significant reduction of the emission of greenhouse gases

Gravel Language

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The Case for Intervention in the Humanitarian Crisis in the Sudan

The humanitarian crisis in Darfur presents one of the greatest challenges to the international community since the coordinated massacre of over 800,000 people in Rwanda in 1994. The mass murder of national, ethnic and tribal groups at the hands of both the Sudanese Government and the pro-Arab, government-backed militias, known as the janjaweed, is deemed responsible for the deaths of tens of thousands of black Sudanese in the region. Despite the unmistakable tragedy that has occurred and continues to occur, the international community has utterly failed to respond. Debate over whether the term genocide should be used to describe the ethnic cleansing and displacement of nearly a quarter of a million people in Sudan has essentially deterred any type of humanitarian intervention from other nations that have signed or ratified the Genocide Convention. Although the U.S. Government has called the crisis a genocide, the United Nations and the rest of the world has yet to do so, and has failed to respond in a timely manner that could have prevented countless deaths and ended the violence

Fracture Toughness: Evaluation of Analysis Procedures to Simplify JIC Calculations

The purpose of this study is to determine if there is an alternative analysis method that can provide an estimate of fracture toughness for specimens that failed to meet all of ASTM E 1820 requirements. This study will look at three alternative analysis methods and evaluate each method’s ability to accurately and easily estimate the elastic-plastic fracture toughness. The standard method of analysis is long and complicated which leads to a number of validity requirements that many tests fail to meet. The objective is to find an easier and reasonably accurate estimate of elastic-plastic fracture toughness. This study has shown that there are two useful means of directly measuring the toughness from the load versus displacement record. It has also shown that there is a method of substituting a linear regression for the power law regression which yields good estimates of fracture toughness. All three methods have been estimating JQ which is a provisional measure of elastic-plastic fracture toughness. The first direct method uses an integral of the area up to the maximum load point to acquire the JQ. The second direct method uses a conversion of the linear elastic fracture toughness which only uses the crack growth and the maximum load from the load versus displacement record. The final method substitutes a linear regression of the two J-R points on either side of the JQ line to determine the JQ point. Each alternative analysis was able to acquire J values with varying degrees of accuracy. The linear substitution was the most accurate. The first direct method using an area integral tended to over predict the true J value. The second direct method using a conversion formula had a tendency to under predict the true J value. None of these methods could substitute for the ASTM standard; however, each provided a usable estimate of elastic-plastic fracture toughness