Trends in aircraft design

The improved performance of aircraft during the past decade has resulted in the need for new design and production techniques. Particular examples are integral construction and the use of sandwich panels. Although these processes are costly, especially when applied to titanium and steel construction, their use is likely to be necessary, at least to some extent. on many supersonic aircraft. The supersonic airliner is no exception to this and the paper discusses the design aspects of this type of aircraft which have a bearing on production problems. It is concluded that more research aimed at reducing the cost of sophisticated forms of construction is required

The teaching of aircraft design

Aircraft Design has been taught at the College of Aeronautics since 1946. The course is at postgraduate level and is of two years duration. In the first year the students are given three exercises in component design which aim to teach a logical approach and the fundamentals of the subject. During the second year each student works as a member of a team engaged in the design of a complete aircraft, which is chosen to be of a type currently being investigated by industry. The project aircraft invariably incorporates experimental features and the design work is therefore of the nature of research

Human transfer characteristics in flight and ground simulation for a roll tracking task

Human transfer characteristics in flight and ground simulation for roll tracking tas

A pattern-recognition theory of search in expert problem solving

Understanding how look-ahead search and pattern recognition interact is one of the important research questions in the study of expert problem-solving. This paper examines the implications of the template theory (Gobet & Simon, 1996a), a recent theory of expert memory, on the theory of problem solving in chess. Templates are "chunks" (Chase & Simon, 1973) that have evolved into more complex data structures and that possess slots allowing values to be encoded rapidly. Templates may facilitate search in three ways: (a) by allowing information to be stored into LTM rapidly; (b) by allowing a search in the template space in addition to a search in the move space; and (c) by compensating loss in the "mind's eye" due to interference and decay. A computer model implementing the main ideas of the theory is presented, and simulations of its search behaviour are discussed. The template theory accounts for the slight skill difference in average depth of search found in chess players, as well as for other empirical data

The Tropos Software Development Methodology: Processes, Models and Diagrams

Tropos is a novel agent-oriented software development methodology founded on two key features: (i) the notions of agent, goal, plan and various other knowledge level concepts are fundamental primitives used uniformly throughout the software development process; and (ii) a crucial role is assigned to requirements analysis and specification when the system-to-be is analyzed with respect to its intended environment. This paper provides a (first) detailed account of the Tropos methodology. In particular, we describe the basic concepts on which Tropos is founded and the types of models one builds out of them. We also specify the analysis process through which design flows from external to system actors through a goal analysis and delegation. In addition, we provide an abstract syntax for Tropos diagrams and other linguistic constructs

Effects of Mowing Frequency on the Yield and Protein Content of Several Grasses Grown in Pure Stands

This paper presents results of a five-year experiment conducted at the Agricultural Experiment Station, Lincoln, Nebraska, on the adaptation, yield, and quality of several grasses subjected to different frequencies of harvest as a means of determining their forage value

Introduced Forage Grasses for Nebraska

This circular presents illustrations, descriptions and recommended usage of fourteen introduced cultivated grasses that are worthy of practical consideration in Nebraska. Most of them can easily be identified by comparing plant specimens with the illustrations and descriptions. This circular has been prepared for use by farmers, county agricultural agents, teachers and others who are interested in our most important grasses. Station Circular 59 contains information and illustrations of the more common native perennial grasses of Nebraska

Generalized survival in equilibrium step fluctuations

We investigate the dynamics of a generalized survival probability $S(t,R)$ defined with respect to an arbitrary reference level $R$ (rather than the average) in equilibrium step fluctuations. The exponential decay at large time scales of the generalized survival probability is numerically analyzed. $S(t,R)$ is shown to exhibit simple scaling behavior as a function of system-size $L$, sampling time $\delta t$, and the reference level $R$. The generalized survival time scale, $\tau_s(R)$, associated with $S(t,R)$ is shown to decay exponentially as a function of $R$.Comment: 4 pages, 2 figure

First measurements of the flux integral with the NIST-4 watt balance

In early 2014, construction of a new watt balance, named NIST-4, has started at the National Institute of Standards and Technology (NIST). In a watt balance, the gravitational force of an unknown mass is compensated by an electromagnetic force produced by a coil in a magnet system. The electromagnetic force depends on the current in the coil and the magnetic flux integral. Most watt balances feature an additional calibration mode, referred to as velocity mode, which allows one to measure the magnetic flux integral to high precision. In this article we describe first measurements of the flux integral in the new watt balance. We introduce measurement and data analysis techniques to assess the quality of the measurements and the adverse effects of vibrations on the instrument.Comment: 7 pages, 8 figures, accepted for publication in IEEE Trans. Instrum. Meas. This Journal can be found online at http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=1