Showing papers by "Mitre Corporation published in 1975"

Cursor positioning on an electronic display using lightpen, lightgun, or keyboard for three basic tasks.

Abstract: Three basic tasks were designed to measure how fast a user could position a cursor at various locations on an electronic display. The tasks were arbitrary cursor positioning, sequential cursor positioning, and check-reading for errors. Three cursor positioning devices were tested. Both lightpen and lightgun permitted faster cursor positioning than a poorly designed keyboard. These pointing devices were four to five times faster than the keyboard for the arbitrary positioning task, and about twice as fast for the other tasks.

Electricity from photosensitisation of titanium

Abstract: FUJISHIMA and Honda1 have described a novel photochemical cell with an open circuit emf of up to 05 V which they indicated had a capability for water photolysis The anode consisted of a TiO2 n-type single crystal which was illuminated by light of wavelength shorter than 415 nm This corresponds to the 30 eV band gap of TiO2 (refs 2–4)

Report to the American Physical Society by the study group on light-water reactor safety

Abstract: The issue of light-water reactor (LWR) safety has been the subject of a part-time, year-long study sponsored by the American Physical Society. The goal of the study was the assessment of some of the technical aspects of the safety of large light-water nuclear power reactors typical of present commercial practice in the Unted States. The report examines issues related to safe operation of LWRs; the research and development program responsible for establishing and enhancing safety; and the consequences of accidents for public health and welfare. The report in no way deals with the need for nuclear power or its benefits, and should not be considered as a net assessment of the risks versus the benefits of nuclear reactors. Since the risks of ecological impacts of other energy technologies are not addressed, no recommendations are made concerning the specific reactor program which should be followed in the immediate future. Among the areas covered in the report are primary pressure-vessel integrity; quality assurance; accident initiation from operator error, transients, and sabotage; the adequacy of present emergency core-cooling system designs; the calculation of long-term consequences to health of one particular low-probability accidental release of radioactivity; and the experimental and calculational (computer-code-development) aspects of the present reactor safety research program. A number of recommendations are contained with the report, mainly addressed to ways in which the safety of the present LWRs can be improved or better understood.

An Algorithm for the Binomial Distribution with Dependent Trials

Abstract: A computational algorithm is developed for generating the cumulative distribution of successes in a sequence of dependent trials, characterized by a Markov model, for which tables of the distribution may be compiled. Such tables may be used to assess the impact of such dependence on the calculation of confidence intervals and the testing of hypotheses. Examples are presented to show how such confidence intervals and hypothesis tests deteriorate with increasing dependence.

Bayesian Confidence Limits For The Availability of Systems

Abstract: This paper presents a numerical procedure for computing Bayes confidence intervals for the availability of a series or parallel system consisting of several statistically independent 2-state subsystems each having exponential distributions of life and repair time. The present results 1) provide a useful generalization of a previous result in which test data were limited to ``snap-shot'' observations on the subsystems operating states; 2) allow conventional life-test data for estimating the exponential parameters. The methods are suited to numerical evaluation using electronic computers as shown by particular examples.

The effect of elevated guideway construction tolerances on vehicle ride quality

Abstract: In this paper the ride quality of a vehicle traversing an elevated guideway is related directly to guideway construction tolerances and design parameters. Moreover, the construction tolerances are modeled in terms familiar to a guideway contractor. The tolerance modeled for an elevated, two-span semicontinuous, concrete guideway are: surface finish, camber deviations, pier survey errors, and pier settlement. The major design parameters relating to live-load deflection, stiffness (material and cross- section), and pier spacing are included. A general technique is presented for relating these tolerances to vehicle ride quality by means of a digital computer simulation. Various ride quality criteria are considered, including rms acceleration, acceleration spectral density, acceleration frequency decomposition, and a deterministic state boundary. Numerical results are presented for a particular vehicle-guideway configuration and as such are valid only for the system considered. It is shown that for this system, equivalent ride quality can be maintained while adjusting the various construction tolerances. This trade-off capability allows the contractor to choose the least costly combination of tolerance parameters.

Electronic Disks in the 1980's

Abstract: In forecasting future types and uses of electronic disks one must consider processing unit architecture and software systems, as well as trends in computer memory technologies. This paper will concentrate on projections of memory technology, including computer architecture and software trends where relevant to these projections. Technologies which have the potential to result in standard commercial products are addressed rather than those which will result only in laboratory prototypes or militarized equipments designed for unique application environments. For example, a technology which may be uniquely suited for space applications may be much too expensive to compete as a commercial product. Bit densities, costs, access times, and other characteristics have been projected as representative of products which are in production, are available in quantity from several vendors, and are therefore competitively priced.

Data Compression in Recursive Estimation with Applications to Navigation Systems

Abstract: The goal of data compression or preprocessing is to reduce computational requirements in a Kalman filter while retaining adequate estimation accuracy. A technique which averages batches of data is considered here. Guidelines are given for averaging, such as, how often to sample the data, when to average, and how many data points to average. The averaging technique is applied to aircraft navigation using two DMEs and either air data or inertial data. The results demonstrate that significant computation time reductions are possible with some covariance degradation. VOR/DME flight data of aircraft landing approaches were used to verify the analysis and show agreement with the analytical predictions.

The Effects of Defruiting on the ATCRBS

Abstract: The defruiter that is employed in the Air Traffic Control Radar Beacon System (ATCRBS) to prefilter asynchronous replies has a complex impact on the detection, estimation and validation properties of the detection subsystem. Its positive and negative effects are quantitatively enumerated via a simulation of the beacon processing subsystem of the Automated Radar Terminal System (ARTS III). It is concluded that the disadvantages of using the present-day defruiter in the ARTS III digital processing channel outweigh the advantages when fruit rates are below several thousand per scan. As an alternative to the total elimination of the defruiter a more general class of preprocessors is defined and their input-output relationships are derived using a Markov Chain formulation. These are found to represent an improvement over the current defruiter in that the positive effects of defruiting are retained while some of the negative effects are reduced.

Automatic Braille translation in the United States of America

Abstract: There are several points I would like to cover in a brief survey .

A method for the sensitivity improvement of radio astronomy receivers

Abstract: The signal-to-noise ratio of radio astronomy receivers can be optimized and the sensitivity improved by reshaping the waveform of the signal received from the antenna by processing it through a transmission line in which the velocity of propagation can be made to vary as the signal enters or leaves the line. Presented here is the complete analysis of the determination of the minimum detectable temperature in the case of a total power radiometer incorporated with time-varying transmission lines. A comparison of the two sensitivity figures of the total power radiometers with and without such transmission lines is also given.

ATC Beacon Interference Characteristics in the New York Area

Abstract: An experimental program is described that had the objective of measuring the effects of the time-dependent structure of downlink (air craft to ground) interference generated by the Air Traffic Control Radar Beacon System (ATCRBS) in an active air traffic terminal area that are relevant to system and ground controller response time. The results of this program indicate a number of interesting details concerning the correlation of the level of the downlink interference with changes in the arrival and departure rates of aircraft at the local terminal sites.

Automata theory: what is it used for?

Abstract: At the graduate level, it seems like one should not have to be able t o explain theoretical relevance of material in a proof oriented fashion. I f everyone waited for such proof before pursing such material I am afrai d that we all would have rather limited educations. Both the student an d the school must work to bridge the theoretical relevance gap. The schoo l should continually be reviewing its course offerings to assure that th e theory they offer is not too far removed from the more relevant material a s to obscure its benefit. On the other hand, students should know beforehan d the broad scope of each course they take which has a theoretical bent t o assure themselves that they are getting material in which they are interested and which fits their educational plans. What quite often happens i s that a student will take a course and yet have no idea of its content, use , or place in his program. This subject is more than interesting, it is vitally important. It woul d like to know what others have to say. If you have any comments on what I have written, I would be glad to cover them further with you. Probably the question most often asked by graduate student s taking their first Automata Theory (A .T .) course is \"How i s this knowledge used?\". First let me address the question and the n evolve an answer. Such a question is probably the reflectio n of a student, such as an engineer, who is quite interested i n being able to directly apply all that he learns. This contrast s immediately in his first couple of lectures in A .T. becaus e A .T. is very much organized around abstract algebraic concepts. This is not to say that the concepts did not originate in th e real world or that there are not real applications ; quite th e contrary. But because of the representation of concepts in th e abstract, it is quite natural and reasonable for one to ask th e question. And as one progresses further into a first or secon d course in A .T ., this question grows in importance as the studen t finds himself putting in generous amounts of time and effort o n material which is increasingly more abstract. No wonder h …

Differential omega in the domestic air traffic control environment

Abstract: At the present time there is interest within the aviation community to determine how the Omega navigation system could possibly be applied to domestic IFR navigation. Assuming Omega provides a sufficient navigation information rate for a significant number of users, there are two Omega methods that are contenders for utilization in the air traffic control system; Composite Omega and Differential Omega. It appears that Differential Omega would be significantly more accurate than Composite Omega. Furthermore, Composite Omega accuracies may not be sufficient for future domestic ATC requirements, whereas Differential Omega would likely meet these accuracy requirements. However, a complete implementation of the differential technique involves several fundamental considerations before this method can be considered further. Some of these considerations are the configuration and the required number of ground monitoring stations, the differential correction message format and data rate, the practicality of various alternatives for the ground-to-air link, and resulting receiver complexity. In analyzing these considerations, a proposed configuration of the differential ground monitor stations is examined. Using a technique to locate these monitor stations, it is shown that approximately fifty will be required to obtain coverage for the forty-eight contiguous states. Based on the number of monitor stations necessary and the amount of correction information required, a differential message format is developed. The variability of the Omega propagation error sources is analyzed, so that a differential correction update rate can be specified. The alternatives for the differential communications link for complete coverage are assessed with consideration given to maximizing the benefits of the differential system. The implications of the differential system with respect to airborne complexity is also discussed.

Simulation and Analysis of a Demand Responsive, Automated Transit System

Abstract: This paper describes a computer simulation of a 12-station personal rapid transit system with offline stations and headways of 10 sec. The simulation has a vehicle assignment algorithm which permits one diversion of vehicles in service to pick up passengers at stations enroute who request the vehicle's programed destination. Results show the diversion strategy provides improved service over a nonstop PRT, for load factors below 30%. At higher demand levels, the additional delay involved in diverting the vehicle outweighs the savings in waiting time.

Ride quality criteria and the design process

Abstract: Conceptual designs for advanced ground transportation systems often hinge on obtaining acceptable vehicle ride quality while attempting to keep the total guideway cost (initial and subsequent maintenance) as low as possible. Two ride quality standards used extensively in work sponsored by the U.S. Department of Transportation (DOT) are the DOT-Urban Tracked Air Cushion Vehicle (UTACV) standard and the International Standards Organization (ISO) reduced ride comfort criteria. These standards are reviewed and some of the deficiencies, which become apparent when trying to apply them in practice, are noted. Through the use of a digital simulation, the impact of each of these standards on an example design process is examined. It is shown that meeting the ISO specification for the particular vehicle/guideway case investigated is easier than meeting the UTACV standard.