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THE necessary manoeuvres of fighting aeroplanes in the present war may occasionally be expected to stress them beyond their strength. In addition to this, the increase in…
THE necessary manoeuvres of fighting aeroplanes in the present war may occasionally be expected to stress them beyond their strength. In addition to this, the increase in speed may be expected to produce unpleasant vibration. It is interesting, therefore, to consider how recent flutter investigations have influenced aeroplane design, and it is proposed in this article to review the more practical aspect of flutter research and to give a general guide to designers as to the importance of the many parameters influencing flutter speed.
IN the 1940 Wilbur Wright memorial lecture on the future of British Civil Aviation Dr. Roxbec Cox has stated that the study of passenger convenience leads to consideration…
IN the 1940 Wilbur Wright memorial lecture on the future of British Civil Aviation Dr. Roxbec Cox has stated that the study of passenger convenience leads to consideration of over weather flying and that the study of improvements in safety leads to consideration of flutter prevention. He has stated also that all aviation authorities recognize the danger of flutter and warns that the chief danger to be guarded against in the future is a sense of security. It has, therefore, been thought worth while to examine the effect on wing flutter speed of flying at great heights. The effects have already been briefly considered by Williams, Pugsley and Duncan in this country and by Kassner and Fingado in Germany.
THE stiffness of an aeroplane wing is usually considered in terms of its torsional and llexural stiffnesses as measured at the “mid‐aileron” and “equivalent tip”…
THE stiffness of an aeroplane wing is usually considered in terms of its torsional and llexural stiffnesses as measured at the “mid‐aileron” and “equivalent tip” sections(1), (2). It appears at present that the stiffness in torsion is more significant than that in flexure, partly because high torsional stiffness is necessary to prevent not only flutter but also reversal of aileron control and divergence(1), (2), both of which are independent of llexural stiff‐ness ; and partly because it is found in practice that when a wing is designed to meet minimum existing strength requirements alone, its torsional stiffness may be inadequate whereas its llexural stiffness is commonly sufficient. The more important of the two torsional stiff‐nesses (“mid‐aileron” and “equivalent‐tip”) is that at the “mid‐aileron” section. The present paper examines the effect of the various parameters on the torsional stiffness of a tapered rectangular tube of proportions representative of an aeroplane wing under a con‐centrated torque applied at a section equivalent to the average “mid‐aileron” section. The analysis of the problem is based on the stress distribution in an axially constrained tapered tube given by Williams in R. & M. 1761(3), and the stiffness obtained is compared with that for a tube with the simple shear stress distribution of the Bredt‐Batho type for a tube with free ends. The similar problem for a uniform tube has already been solved from the equations of reference (3) in R. & M. 1790(4).
At the annual general meeting of British Messier Ltd., held on July 24, 1953, it was announced that the Rt. Hon. The Lord Hives, C.H., M.B.E., D.Sc., had tendered his resignation from the Board to take effect from that date. Mr W. T. Gill has consented to fill the vacancy caused by the resignation of Lord Hives. The British Messier Board now consists of the following: Sir W. Reginald Vcrdon Smith, Mr W. T. Gill, Lt.‐Gen. Sir John Evctts, Mr L. S. Armandias, Mr H. G. Conway.
IN the past, the required amount of directional stability was dictated mainly by asymmetric power considerations and by the maximum angles of sideslip in manoeuvres…
IN the past, the required amount of directional stability was dictated mainly by asymmetric power considerations and by the maximum angles of sideslip in manoeuvres permissible from the structural strength viewpoint. The requirement for satisfactory recovery from steady spin would in certain cases influence both the directional stability and control power in such a fashion as ultimately to be the determining factor. Present indications are that the choice of the required degree of directional stability will be based on supersonic lateral dynamic stability considerations, in particular the stability of the so‐called Dutch roll oscillation, or on considerations of avoiding inertia coupling between the lateral and longitudinal degrees of freedom during rolling. Both of these problems will be discussed in some detail later. It should be emphasized, however, that large values of subsonic directional stability will be required for supersonic aircraft in order to provide satisfactory dynamic characteristics at supersonic speeds at high altitudes.
Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics and publications of other similar research bodies as issued
We develop a conceptual model, based on person-environment fit theory, which explains how employee age affects occupational strain and well-being. We begin by explaining…
We develop a conceptual model, based on person-environment fit theory, which explains how employee age affects occupational strain and well-being. We begin by explaining how age directly affects different dimensions of objective and subjective P-E fit. Next, we illustrate how age can moderate the relationship between objective P-E fit and subjective P-E fit. Third, we discuss how age can moderate the relationships between P-E fit, on one hand, and occupational strain and well-being on the other. Fourth, we explain how age can impact occupational strain and well-being directly independent of P-E fit. The chapter concludes with implications for future research and practice.
Multiple classifier systems have been used widely in computing, communications, and informatics. Combining multiple classifier systems (MCS) has been shown to outperform a…
Multiple classifier systems have been used widely in computing, communications, and informatics. Combining multiple classifier systems (MCS) has been shown to outperform a single classifier system. It has been demonstrated that improvement in ensemble performance depends on either the diversity among or the performance of individual systems. A variety of diversity measures and ensemble methods have been proposed and studied. However, it remains a challenging problem to estimate the ensemble performance in terms of the performance of and the diversity among individual systems. The purpose of this paper is to study the general problem of estimating ensemble performance for various combination methods using the concept of a performance distribution pattern (PDP).
In particular, the paper establishes upper and lower bounds for majority voting ensemble performance with disagreement diversity measure Dis, weighted majority voting performance in terms of weighted average performance and weighted disagreement diversity, and plurality voting ensemble performance with entropy diversity measure D.
Bounds for these three cases are shown to be tight using the PDP for the input set.
As a consequence of the authors' previous results on diversity equivalence, the results of majority voting ensemble performance can be extended to several other diversity measures. Moreover, the paper showed in the case of majority voting ensemble performance that when the average of individual systems performance P is big enough, the ensemble performance Pm resulting from a maximum (information‐theoretic) entropy PDP is an increasing function with respect to the disagreement diversity Dis. Eight experiments using data sets from various application domains are conducted to demonstrate the complexity, richness, and diverseness of the problem in estimating the ensemble performance.
Purpose – In this chapter, we outline early sociological thinking on time rooted in various philosophies of time and review the relatively current research in the area of…
Purpose – In this chapter, we outline early sociological thinking on time rooted in various philosophies of time and review the relatively current research in the area of temporal perspective. Next, we define the scope of the social psychology of time and illustrate how and why social psychology has failed to properly and effectively include time as a central component of study. Finally, we link current thinking about time to group processes research, most directly to identity and social identity processes (though not exclusively), making clear the ways current and future approaches could benefit from including temporal perspectives.
Methodology – We review relevant research engaged with concepts related to time in psychology, sociology, and social psychology. On the foundation of our review and the identification of gaps in the literature, we provide insights and recommendations regarding how temporal perspectives may be adopted by existing knowledge bases in sociological social psychology.
Findings – As a conceptual chapter, this work presents no empirical findings. A review of the literature reveals a scarcity of research effectively embedding temporal perspectives in major areas of social psychological research.
Practical Implications – The recommendations we make for connecting temporal perspectives to existing research areas provide a practical foundation from which to develop new ideas.
Social Implications – This work contributes to the social psychology of time by detailing how time is an important, yet mostly overlooked, component to our understandings of many social psychological processes. In the effort to extend identity and social identity theory in specific, we add to the general knowledge of the self and self-processes via the incorporation of temporal perspectives.
Originality – This work is the first to explore how temporal perspectives in sociological social psychology are employed, but mostly, how they are underutilized. We make recommendations for how novel theoretical predictions may emerge by including perspectives about time in existing research programs.
Although a significant body of work has amassed that explores the antecedents, correlates, and consequences of employee turnover in organizations, little is known about…
Although a significant body of work has amassed that explores the antecedents, correlates, and consequences of employee turnover in organizations, little is known about how employees go about quitting once they have made the decision to leave. That is, after the decision to voluntarily quit their job is made, employees must then navigate through the process of planning for their exit, announcing their resignation, and potentially working at their company for weeks after their plans to resign have been made public. Our lack of understanding of the resignation process is important as how employees quit their jobs has the potential to impact the performance and turnover intentions of other organizational members, as well as to harm or benefit the reputation of the organization, overall. Moreover, voluntary turnover is likely to increase in the coming decades. In this chapter, we unpack the resignation process. Specifically, drawing from the communication literature and prior work on employee socialization, we develop a three-stage model of the resignation process that captures the activities and decisions employees face as they quit their jobs, and how individual differences may influence how they behave in each of these three stages. In doing so, we develop a foundation upon which researchers can begin to build a better understanding of what employees go through after they have decided to quit but before they have exited their organization for the final time.