bluuebunny/crossref_metadata_2025 huggingface dataset:
The fractional linear probability generating function in the random environment branching process
Authors: Grey D. R. , Zhunwei Lu
Published: July 2016

In a branching process with random environments, the probability of ultimate extinction is a function of the environment sequence, and is therefore a random variable. Explicit results about the distribution of this random variable are difficult to obtain in general. Here we assume independent and identically distributed environments and use the special properties of fractional linear generating functions to derive some explicit distributions, which may be singular or absolutely continuous, depending on the values of certain parameters. We also consider briefly tail behaviour close to 1, and provide an extension to cases where probability generating functions are not fractional linear.
Weak convergence of conditioned birth and death processes
Authors: Roberts G. O. , Jacka S. D.
Published: July 2016

We consider the problem of conditioning a non-explosive birth and death process to remain positive until time T, and consider weak convergence of this conditional process as T → ∞. By a suitable almost sure construction we prove weak convergence. The almost sure construction used is of independent interest but relies heavily on the strong monotonic properties of birth and death processes.
Some limit theorems for the general semi-Markov storage model
Authors: Balagopal K.
Published: July 2016

In this paper we treat the general version of the semi-Markov storage model, introduced first by Senturia and Puri: transitions in the state of the system occur at a discrete sequence of time points, described by a two-state semi-Markov process. An input occurs at an instant of transition to state 1 and a demand for release occurs at an instant of transition to state 2.

Assuming general distributions for all the variables involved, we show that the dam contents just after the nth input converges properly in distribution as n →∞ under conditions of stability; likewise that after the nth demand. We also show that the demand lost due to shortage of stock, accumulated over instants of demand as well as over time, obeys a strong law and a central limit theorem.
Optimal insurance premium rates when the distribution of claims is unknown
Authors: Venezia Itzhak
Published: July 2016

We analyze here the optimal premium rates for an insurance company for the case where the claims process is a stochastic process with unknown parameters. The beliefs of the insurance company about these parameters are represented by some prior distribution function, and the premium rates are determined on the basis of this distribution. The insurer learns about the unknown parameters from the past behavior of the claims process, and revises the prior distribution whenever new information is obtained (i.e., a claims stream is observed).

The learning process introduces multi-period dynamic considerations to the problem of the rate determination, since the rates determined at any period affect the claims process, and thus the information available for future decisions. We show how the optimal rates can be obtained by using some dynamic programming techniques. We also prove that the optimal rates obtained in our case are lower than those determined by an insurance company that does not revise its distribution.
Calculation of the equilibrium distribution for a solar energy storage model
Authors: Hooghiemstra G. , Keane M.
Published: July 2016

The study of simple solar energy storage models leads to the question of analyzing the equilibrium distribution of Markov chains (Harris chains), for which the state at epoch (n + 1) (i.e. the temperature of the storage tank) depends on the state at epoch n and on a controlled input, acceptance of which entails a further decrease of the temperature level. Here we study the model where the input is exponentially distributed. For all values of the parameters involved an explicit expression for the equilibrium distribution of the Markov chain is derived, and from this we calculate, as one of the possible applications, the exact values of the mean of this equilibrium distribution.
A note on the probability of extinction in a class of population-size-dependent Galton-Watson processes
Authors: Höpfner R.
Published: July 2016

In a class of population-size-dependent Galton-Watson processes where extinction does not occur with probability 1 we describe the rate of decay of qi (the probability that the process starting from i ancestors will become extinct) as the number i of ancestors increases.

The results are related to the asymptotic behavior of the Green's function of the critical Galton-Watson process with immigration.
A queue with Markov-dependent service times
Authors: Pestalozzi Gerold
Published: July 2016

A queueing system is considered where each item has a property associated with it, and where the service time interposed between two items depends on the properties of both of these items. The steady state of a single-channel queue of this type, with Poisson input, is investigated. It is shown how the probability generating function of the number of items waiting can be found. Easily applied approximations are given for the mean number of items waiting and for the average waiting time.
On the autocorrelation and spectral functions of queues
Authors: Reynolds John F.
Published: July 2016

This paper considers the autocorrelation function of queue length and the corresponding spectral density (i.e., its Fourier transform). Some general expressions are obtained using generating functions and matrices, and applied to M/M/1 and M
[x]/M/∞ queues.
An Extension of the Hájek-Rényi inequality for the case without moment conditions
Authors: Heyde C. C.
Published: July 2016

In the paper [1], Hájek and Rényi established an inequality which they formulated in the following way: X
1,X
2,··· are independent random variables and . For each k, EXk
= 0 and , while is a non-increasing sequence of positive numbers. Then, for any ε > 0 and any positive integers n and m (n < m),

The well-known Kolmogorov inequality is the particular case ck
= 1, all k, and n = 1 of (1). It is the object of the present note to produce an extended version of (1) where no moment conditions need be satisfied. This provides a useful general bound and illuminates the role of certain standard techniques in the study of the almost sure behaviour of sums of independent random variables.
Low density inhomogeneous traffic flow
Authors: Mine Hisashi , Ohno Katsuhisa
Published: July 2016

The purpose of this paper is to show some statistical properties of a one-dimensional inhomogeneous flow of particles with their own constant velocities. The most interesting example of such flows is a low-density inhomogeneous road traffic flow; each vehicle drives at his own constant velocity (desired velocity), since passing is freely allowed. Therefore, to give a definite picture to the one-dimensional inhomogeneous flow of particles, the authors deal with a low-density inhomogeneous traffic flow.
Some applications of renewal theory on the whole line
Authors: Crump Kenny S. , Hoel David G.
Published: July 2016

Suppose F is a one-dimensional distribution function, that is, a function from the real line to the real line that is right-continuous and non-decreasing. For any such function F we shall write F{I} = F(b)– F(a) where I is the half-open interval (a, b]. Denote the k-fold convolution of F with itself by Fk*
and let

Now if z is a non-negative function we may form the convolution

although Z may be infinite for some (and possibly all) points.
The limiting distribution of the maximum term in a sequence of random variables defined on a markov chain
Authors: Fabens Augustus J. , Neuts Marcel F.
Published: July 2016

Gnedenko's classical work [1] on the limit of the distribution of the maximum of a sequence of independent random variables is extended to the distribution of the maximum of a sequence of random variables defined on a finite Markov chain.
Superimposed non-stationary renewal processes
Authors: Blumenthal S. , Greenwood J. A. , Herbach L.
Published: July 2016

For superposition of independent, stationary renewal processes, it is well known that the distribution of waiting time between events for the superimposed process is approximately exponential if the number of processes involved is sufficiently large, (see Khintchine (1960), Ososkov (1956)). We assume that all component processes have the same age t, and we generalize the classical result to show that even for t finite (non-stationary case), the limiting waiting time distribution (as the number of processes increases) is exponential with a scale parameter which depends on t through the average of the individual process renewal densities.
A note on random walks
Authors: Phatarfod R. M. , Speed T. P. , Walker A. M.
Published: July 2016

Let {Xn
} be a random walk between reflecting barriers at 0 and a > 0 with jumps {Zn
}. By we mean the random walk between absorbing barriers at — a and 0+ with the same jumps {Zn
}. It has been known for some time that when {Zn
} is a sequence of mutually independent and identically distributed random variables, and 0 ≦x <a, we have for all n:
A first-passage problem for a two-dimensional controlled random walk
Authors: Lalley S.
Published: July 2016

The process of interest is a controlled random walk in two dimensions: whenever the walker is above the main diagonal, the next increment to his position is chosen from a distribution FA
; whenever the walker is below the diagonal, the next increment comes from another distribution FB. The two distributions have mean vectors which tend to push the walker back toward the diagonal. We analyze the problem of first passage to the first quadrant, obtaining explicit representations for the limiting first-entry distribution and expected first-passage time.
On the almost sure convergence of controlled branching processes
Authors: Bagley J. H.
Published: July 2016

An almost sure convergence result for the normed population size of a supercritical controlled branching process is proved.
A note on the total size distribution of epidemic models
Authors: Ball Frank
Published: July 2016

A simple coupling argument is used to obtain a new proof of a result of Daniels (1967) concerning the total size distribution of the general stochastic epidemic. The proof admits a straightforward generalisation to multipopulation epidemics and indicates that similar results are unlikely to be available for epidemics with non-exponential infectious periods.
Moments of coverage and coverage spaces
Authors: Ailam Gedalia
Published: July 2016

Moments of the measure of the intersection of a given set with the union of random sets may be called moments of coverage. These moments specified for the case of independent random sets in the Euclidean space, were treated by several authors. Kolmogorov (1933) and Robbins (1944), (1945), (1947) derived transformation formulas for the moments of coverage under some specified conditions. Robbins' formula was applied by Robbins (1945), Santaló (1947) and Garwood (1947) to computations of expectations and variances of coverage in the cases of spheres and intervals in 2-dimensional and in n-dimensional Euclidean space. The computations were carried out under the assumption of a simple distribution function for the centers of the covering figures (a homogeneous distribution in most of the cases and a normal one in some of them). Neyman and Bronowski (1945) computed by a different method the variance of coverage for some specific cases in the Euclidean plane.
Diffusion approximations and models for certain congestion problems
Authors: Gaver D. P.
Published: July 2016

In a variety of the congestion or queueing problems that arise in practice, for example, in studies of the crossing and entry problems of road traffic, (see Evans, Herman, and Weiss [2]), and recently of the service afforded by large centralized and shared computer facilities, (see Scherr [12]), the understanding of system performance furnished by the present mathematical theory is inadequate. The reason is that while the consideration of simple problems typically yields elegant mathematical results, the form of these results—often expressed in terms of integral transforms—is not immediately comprehensible nor useful for simple comparisons. This fact has been remarked upon by Newell, who in [9] has suggested certain more comprehensible but approximate approaches based on diffusion theory; further promising developments and elaborations will be found in [10]. The latter approach is related to the “heavy traffic theory” of J. F. C. Kingman [8], and to some recent work of Iglehart [6]. Of course, the idea of approximating complex discrete-state processes by diffusion processes with continuous paths is not new. It has long been used in genetics, see Feller [3], and the review paper by Kimura [7]. Nonetheless, applications to congestion theory are apparently still rather rare.
On a model for a fair distribution of gifts
Authors: Galambos János
Published: July 2016

A number of items are to be distributed among n individuals, arranged in a line and labelled by the integers 1, 2, ···, n, in such a way that the distance between any two members presented should be at least d, a given number, but otherwise any subset of the population should have the same probability of each of its members being presented. The number of items thus distributed is a random variable X(d, n) and it turns out that X(d, n) is asymptotically a fixed percentage of the population size n. This fact makes it possible to apply the model in a number of situations. For example, if in a foreign aid program a number of tools are offered and to be distributed in a fair way but, for lack of sufficient quantity, one tool is expected to be used by a number of neighbours, the model is applicable if the amount of aid is not fixed in advance but may vary within certain limits. A similar situation arises in cases of disaster (floods, earthquakes, etc.) when the victims are sent gifts, again in an insufficient quantity, hence for the sake of justice, a family of a smaller size is supposed to receive only one gift. In many other similar cases, the model can be used.
The construction of limiting distributions of response probabilities
Authors: Marliss G. S. , McGregor J. R.
Published: July 2016

As stated elsewhere [9], the two experimenter-controlled events learning model of Bush and Mosteller [1] may be described by a Markov process X
0,X
1, ···satisfying the following conditions.

(i)

Xo has an arbitrary distribution on (0, 1).

(ii)

If Xn is given, then with probability π1 and with probability π2

(ii)
Some renewal process models for single neuron discharge
Authors: Hochman Howard G. , Fienberg Stephen E.
Published: July 2016

Leslie (1969) obtained the Laplace transform for the recurrence time of clusters of Poisson processes, which can be thought of as yielding the interspike interval distribution for a neuron that receives Poisson excitatory inputs subject to decay. Here, several extensions of this model are derived, each including Poisson inhibitory inputs. Expressions for the mean and variance are derived for each model, and the results for the different models are compared.
Point processes arising in vehicular traffic flow
Authors: Brill Edward A.
Published: July 2016

In this paper we investigate the properties of stationary point processes motivated by the following traffic model. Suppose there is a dichotomy of slow and fast points (cars) on a road with limited overtaking. It is assumed that fast points are delayed behind (or are clustered at) a slow point in accordance with the principles of aGI/G/squeue, the order of service being irrelevant. Thus each slow point represents a service station, with the input into each station consisting of a fixed (but random) displacement of the output of the previous queueing station. It is found that tractable results for stationary point processes occur for the casesM/M/s(s= 1, 2, ···, ∞) andM/G/∞. In particular, it is found that for these cases the steady state point processes are compound Poisson and that for theM/M/1 case the successive headways form a two state Markov renewal process. In addition it is shown that the input, output, and queue size processes in a steady stateM/G/∞queue are independent at any fixed time; this is a result I have been unable to find in the literature.
Stereological versions of integral geometric formulae for n-dimensional ellipsoids
Authors: Jensen E. B. , Møller J.
Published: July 2016

Recently, unbiased stereological estimators of moments of particle volume, based on measurements on lower-dimensional sections through the particles, have been developed by Jensen and Gundersen (1985). In this note, we derive an explicit form of these unbiased estimators valid for particles in Rnof ellipsoidal shape, and we establish a close relationship between the estimators and a known integral geometric formula for ellipsoids, due to Furstenberg and Tzkoni (1971). Furthermore, a stereological version of another integral geometric formula forn-dimensional ellipsoids, due to Guggenheimer (1973), is derived.
Non-linear filtering of rare events with large signal-to-noise ratio
Authors: Heunis A. J.
Published: July 2016

The theory of robust non-linear filtering in Clark (1978) and Davis (1980), (1982) is used to evaluate the limiting conditional distribution of a diffusion, given an observation of a ‘rare-event' sample-path of the diffusion, as the signal-to-noise ratio and the diffusion noise-intensity converge to infinity and zero respectively. Under mild conditions it is shown that the limiting conditional distribution is a Dirac measure concentrated at a trajectory which solves a variational problem parametrised by the sample-path of the observed signal.
More predictable, less predictable and stable counting processes
Authors: Ebrahimi Nader
Published: July 2016

In a counting process considered at time t the focus is often on the length of the current interarrival time, whereas points in the past may be said to constitute information about the process. The paper introduces new concepts on how to quantify predictability of the future behavior of counting processes based on the past information and considers then situations in which the future points become more (or less) predictable. Various properties of our proposed concepts are studied and applications relevant to the reliability of repairable systems are given.
Random walks with negative drift conditioned to stay positive
Authors: Iglehart Donald L.
Published: July 2016

Let {Xk
: k ≧ 1} be a sequence of independent, identically distributed random variables with EX
1 = μ < 0. Form the random walk {Sn
: n ≧ 0} by setting S
0 = 0, Sn
= X
1 + … + Xn, n ≧ 1. Let T denote the hitting time of the set (–∞, 0] by the random walk. The principal result in this paper is to show (under appropriate conditions on the distribution of X
1) that Sn
, conditioned on T > n converges weakly to a limit random variable, S∗, and to find the Laplace transform of the distribution of S∗. We also investigate a collection of random walks with mean μ < 0 and conditional limits S∗ (μ), and show that S∗ (μ), properly normalized, converges to a gamma distribution of second order as μ ↗ 0. These results have applications to the GI/G/1 queue, collective risk theory, and the gambler's ruin problem.
Transience and recurrence of an interesting Markov chain
Authors: Letac Gérard
Published: July 2016

This note studies the natural extension to the countable case of a chain considered by Hendricks (1972) and gives necessary and sufficient conditions for transience, null recurrence and positive recurrence.
Carrier-borne epidemics in a community consisting of different groups
Authors: Becker Niels
Published: July 2016

A model for the spread of a carrier-borne disease is considered which allows for individual variability. The solutions are used to study the effect of relaxing the assumption of ‘homogeneous mixing’. It is shown that the mean size of an epidemic outbreak is a minimum when the individuals are homogeneous.
A quantum-mechanical central limit theorem for anti-commuting observables
Authors: Hudson R. L.
Published: July 2016

A quantum-mechanical central limit theorem for sums of pairwise anti-commuting representations of the canonical anti-commutation relations over a finite-dimensional space is formulated and proved.
Almost sure limit points of record values
Authors: De Haan Laurens , Resnick Sidney I.
Published: July 2016

{Xn, n ≧ 1} are i.i.d. unbounded random variables with continuous d.f. F(x) =1 —e –R

(x). Xj
is a record value of this sequence if Xj
>max {X
1, …, Xj-

1} The almost sure behavior of the sequence of record values {XL
n
} is studied. Sufficient conditions are given for lim sup
n→∞
X
Ln
/R
–l(n)=e
c, lim inf
n → ∞
X

Ln
/R
−1 (n) = e
−c, a.s., 0 ≦ c ≦ ∞, and also for lim sup
n→∞
(XLn—R–

1(n))/an
=1, lim inf
n→∞
(XLn—R–

1(n))/an
= − 1, a.s., for suitably chosen constants an
. The a.s. behavior of {XL
n
} is compared to that of the sequence {Mn
}, where Mn
= max {X
1, …, Xn
}. The method is to translate results for the case where the Xn's are exponential to the general case by means of an extended theory of regular variation.
Stochastic comparisons of random processes, with applications in reliability
Authors: Pledger Gordon , Proschan Frank
Published: July 2016

The usual definition of stochastic comparison of random vectors is extended to stochastic comparison of random processes. Conditions are stated under which {X (t), t ≧ 0} stochastically larger than {Y (t), t ≧ 0} implies that for increasing functionals f.

Applications are made to reliability problems, yielding stochastic comparisons for systems of independently operating machines assuming exponential failure and exponential repair. From these stochastic comparisons we may then deduce similar stochastic comparisons for functionals of practical importance in reliability applications, such as the total machine up-time, the first time that the number of functioning machines drops below a specified number, the total time during which at least a specified number of machines are functioning, etc.
HEALTH EDUCATION AND THE CONTROL OF UROGENITAL SCHISTOSOMIASIS: ASSESSING THE IMPACT OF THEJUMA NA KICHOCHOCOMIC-STRIP MEDICAL BOOKLET IN ZANZIBAR
Authors: Stothard J. R. , Khamis A. N. , Khamis I. S. , Neo C. H. E. , Wei I. , Rollinson D.
Published: July 2016

Endeavours to control urogenital schistosomiasis on Unguja Island (Zanzibar) have focused on school-aged children. To assess the impact of an associated health education campaign, the supervised use of the comic-strip medical bookletJuma na Kichochoby Class V pupils attending eighteen primary schools was investigated. A validated knowledge and attitudes questionnaire was completed at baseline and repeated one year later following the regular use of the booklet during the calendar year. A scoring system (ranging from 0.0 to 5.0) measured children’s understandings of schistosomiasis and malaria, with the latter being a neutral comparator against specific changes for schistosomiasis. In 2006, the average score from 751 children (328 boys and 423 girls) was 2.39 for schistosomiasis and 3.03 for malaria. One year later, the score was 2.43 for schistosomiasis and 2.70 for malaria from 779 children (351 boys and 428 girls). As might be expected, knowledge and attitudes scores for schistosomiasis increased (+0.05), but not as much as originally hoped, while the score for malaria decreased (−0.33). According to a Kolmogorov–Smirnov test, neither change was statistically significant. Analysis also revealed that 75% of school children misunderstood the importance of reinfection after treatment with praziquantel. These results are disappointing. They demonstrate that it is mistaken to assume that knowledge conveyed in child-friendly booklets will necessarily be interpreted, and acted upon, in the way intended. If long-term sustained behavioural change is to be achieved, health education materials need to engage more closely with local understandings and responses to urogenital schistosomiasis. This, in turn, needs to be part of the development of a more holistic, biosocial approach to the control of schistosomiasis.
Bi-musicality and dialogical musicality: Influences of Javanese gamelan participation on Western instrumental learning
Authors: Haddon Elizabeth
Published: July 2016

This qualitative research examines the influence of learning Javanese gamelan on aspects of musicianship, attitudes and approaches relating to the learning and performance of Western instruments experienced by a sample of UK university music students. In addition to benefits to musicianship, students delineated positive developments in attitudes and approaches to learning and performance. While bi-musicality may be the prerogative of only those who can maintain expertise concurrently in more than one musical style, the concept of dialogical-musicality is proposed as a construct emphasising productive inter-relationships arising from practical engagement with different musical styles at any level.
Engines for a Mach 2·0 Transport
Authors: Reed A. V. N.
Published: July 2016

The problem of determining the type of engine which best suits a particular application is not new to the engine designer, but the supersonic transport is perhaps unique in that a number of design criteria have been introduced which cannot easily be taken account of in the usual terms of engine weight, fuel consumption or even aircraft direct operating cost.

However, an examination of the effect of these standard criteria on different types of engines is a starting point in determining what engine will best match the supersonic transport requirement. A survey of a series of thermodynamic cycles both at Mach numbers in the region of 2.0 and at subsonic speeds typical of standoff or diversion suggests that two types of engine merit further study.
The Initial Strain Concept
Authors: Grzedzielski Alex. L. M.
Published: July 2016

In a note published in the June 1960 JOURNAL, 1 pointed out certain deficiencies in the initial strain concept introduced by Messrs. J. H. Arygris and S. Kelsey. In the August JOURNAL, those authors have disputed my conclusions with an argument which, I feel, does not pay due regard to current literature and I believe may be based on a misinterpretation of certain algebraic manipulations contained in my note. For they concluded that my note contained misprints, which it, in fact, did not. Due to these unfortunate circumstances Messrs. Argyris and Kelsey failed to illuminate the basic disagreement between our two formulations. For this reason I should like to set out in simple detail the exact nature of our disagreement and to point out, as clearly as possible, where the initial strain concept as developed by Messrs. Argyris and Kelsey becomes, I believe, somewhat inadequate and how the concept of fictitious thermal loads achieves greater validity.
The Law versus Science in Aeronautics
Authors: Caplan H.
Published: July 2016

Law, Science and Aeronautics are defined in broad terms and some landmarks are outlined in the history of control of aeronautics by legal means.

The exercise of national sovereignty often means that relevant laws are a serious limiting operational parameter. This and other factors may hinder the development of international air transport (especially supersonic aircraft) and may thus threaten the livelihood of aeronautical scientists.

When aviation accidents occur, the operation of rules which determine “legal liability” may thrust an unfair financial burden on sections of the community which may be blameless from a scientific point of view. Suggestions for the future are made.

Scientific exploration into outer space provides a crucial opportunity for the nations of the world to co-ordinate the disciplines of science, law and politics in a way never before possible. Members of the Royal Aeronautical Society cannot afford to ignore this challenge and a practical suggestion is made as a first step in implementation.
An Appreciation of Missile Structures
Authors: Newell A. F.
Published: July 2016

The invitation for this lecture requested “a review of missile structures from the viewpoint of an aircraft designer.” This is inevitable because most of the author’s experience has been associated with aircraft design. There are however many people actively concerned with missiles who have had considerable experience designing aircraft and would be better qualified to make a more realistic approach to the subject. The difficulty for an outsider making a review of missiles is justifying the “need to know” and then, having found out, or deduced interesting facts, he may be made aware that to publish them would contravene some security ruling.
The Scientific Programme of Skylark to Mid-1960
Authors: Boyd R. L. F.
Published: July 2016

Today we are Interested in the scope of the research programme rather than the actual details of the physics. Further I shall discuss space research rather than just upper atmosphere research, because we include astronomy and this will be discussed by others as well.

Now I have, in fact, a formidable task, because I find I have something like twenty-three experiments to deal with in twenty minutes. What I am going to do therefore is to list the experiments that are going on, to tell you whether they have been carried out successfully, or are awaiting completion, and thus to try to give you some idea of the scope of the work which has been undertaken.
Some Current Problems Facing the Aircraft Designer
Authors: Floyd J. C.
Published: July 2016

While the subject of this paper is concerned with problems somewhat outside the scope of those which existed in the days of the late Roy Chadwick, nothing absorbed Chadwick's interest more than a seemingly intangible aircraft problem, and I am sure that had he been alive today he would have been deeply involved in the search for solutions to them.

He was without doubt a man of great talent, with an intuitive flair for design, and I join the many members of his staff who deem it a great privilege to have been associated with him for many years; and am honoured to have been asked to present this Memorial Lecture.
Space-Correlations in the Fluctuating Pressure Field Near to a Jet Engine
Authors: Franklin R. E.
Published: July 2016

An aspect of structural design which is becoming increasingly more important is the behaviour of a structure when it is subjected to random pressure loading. Random pressure fields can be encountered in several different ways, two of the principal sources of such fields being the noise emitted by a jet, and the fluctuating pressures in a turbulent boundary layer. Many jet-propelled aircraft have suffered secondary structure fatigue failures in those parts of their structures near to the jet stream, and it is not unlikely that certain failures of panelling in engine intakes have arisen because of vibrations set up by the turbulent pressure fluctuations in the boundary layers at the walls.
The Agena Satellite and The Discoverer Programme
Authors: Smelt Ronald
Published: July 2016

The history of the Agena space vehicle starts in the years immediately following the Second World War, when the Rand Corporation under a contract with the U.S. Air Force examined the potential applications of satellites, recognising their technical feasibility as an additional bonus from an inter-continental ballistic missile development programme. The U.S. Air Force kept this concept alive throughout the development phase of the ICBM programme; the Lockheed Aircraft Corporation actually received its first contract, for detailed engineering studies, in 1955. The Agena space vehicle has grown from these beginnings and is now the vehicle selected for a large variety of U.S. space projects. Most of these are satellites, but they include a few space probes and moon explorers.
The Farmer's Viewpoint on Aerial Application of Fertilisers and Sprays
Authors: Farrant J. B.
Published: July 2016

What is the normal practice of a reasonably good farmer in the matter of fertiliser application to both arable and grass crops? First, there is such a wide disparity between the practice of a good farmer and the rest that it can only be hoped that all will soon be brought up to the good standard. A recent survey showed that about 50 per cent of temporary grass and 70 per cent of permanent grassland in England and Wales still receive no nitrogen fertiliser.

Normal application to both temporary and permanent grassland (for light and medium soils) is three to five cwt. of a compound (12: 12: 18) plus two applications of nitrogen, or expressed as straight fertilisers:
Part II: Approach Guidance
Authors: Lennox S. G.
Published: July 2016

The success of inter-city transport helicopter operation will depend on the ability to fly between small sites in city centres with good regularity. Any compromise, such as moving the site to the outskirts of the city or only being able to fly in fine weather, will destroy the advantage of the helicopter over other forms of transport. During the past decade there has been considerable progress in the improvement of helicopter flying qualities so that it is now possible to specify equipment which will enable a helicopter pilot to control his machine in all visibilities and most conditions of turbulence. Further developments in ice protection will enable the basic helicopter to be cleared as an airworthy vehicle for all-weather flight. However, there still remains the problem of navigation, which becomes particularly acute for the final instrument approach. Existing equipment, in particular the Decca Navigation System, can probably meet the case for aerial navigation at altitude, but to fly down an approach to low altitudes into a restricted site demands a higher standard of accuracy and reliability than is offered by any currently available equipment. This paper only deals with the blind approach down to a height of the order of 200 ft. above the landing pad. To extend this to blind landing would require an even higher degree of accuracy and reliability, which does not seem to be justified until some actual operational experience of a simpler blind approach system has been gained to establish whether or not there is a real need for blind landing. A blind approach system which will permit a cloud break height of 200 ft. to be followed by a visual approach and landing on ground lighting should offer at least as good a standard of weather regularity as is currently achieved by fixed-wing aircraft.
The Rôle of Jet Lift
Authors: Keith-Lucas David
Published: July 2016

In 1909 Monsieur Louis Blériot forged a link between our two countries, one might say an aeronautical link. He did so in an aeroplane which by today's standards took only a short take-off run and a short landing.

Today there are signs of new links being forged between the two countries and among them is co-operation in the development of vertical take-off and landing aircraft. There can, therefore, be no more suitable subject for a lecture in commemoration of Louis Blériot than one on “The Role of Jet Lift.”
Military Use of Ground-Effect Vehicles
Authors: Coulthard W. H.
Published: July 2016

The lecture illustrates, by typical examples, the standard of mobility which can be achieved by present military vehicles. An outline is then given of the mobility improvements which might be obtained by the use of military ground-effect vehicles but, in the concluding section, emphasis is given to a number of generalised problems in the military operation of such vehicles which require detailed consideration before an adequate specification of ground-effect vehicles for military use is possible. The lecture deals only with overland vehicles —although capable of water crossing—which are designed specifically to exploit the ground-effect principle and whose capabilities for sustained airborne movement are limited to the ground cushion.
Operations of Chicago Helicopter Airways, Inc.
Authors: Angstadt R. S.
Published: July 2016

The operations of Chicago Helicopter Airways represent a portion of the total Federal effort within the United States on behalf of helicopter development. This effort has been an outgrowth of the interest of the Civil Aeronautics Board and the U.S. Post Office Department which has a long tradition of looking for new developments in transport and of experimenting in new ways to move mail. Post Office interest in the aeroplane was the chief stimulus to the early development of U.S. airlines and dates back to the first scheduled air mail route authorised between New York and Washington in August 1918. It was natural, then, that the Post Office Department should have interest in the helicopter as it emerged in usable form for civil use after the Second World War.
The Sikorsky Crane Helicopter
Authors: Michel P. L.
Published: July 2016

After many years of helicopter design, development, and operations, a practical flying crane helicopter is under construction whose particular features promise an unprecedented utility. The steps leading to this new helicopter configuration were evolutionary in nature dating back as far as 1922 when the deBothezat quadrotor machine hovered for one minute and forty-two seconds.

Early military interests in improved mobility of the armed forces and the experiences gained with helicopters in the Korean War gave impetus to the development of vertical lift capability. In addition to the basic helicopter developments specific crane flying test beds and parametric studies were sponsored by the military. These projects included the Hughes XH-17 flying crane, the McDonnell XHCH-1 rotor test programme and the Sikorsky HR2S-1 (H-37) helicopters. In addition design study contracts were sponsored which determined the feasibility of constructing crane-type helicopters of 8 to 16 ton payload capability.
The Westland Belvedere Mk. I
Authors: McClements A.
Published: July 2016

The Belvedere, previously known as the Bristol 192 helicopter, was designed and developed to an Air Staff Requirement for a General Purpose helicopter for the Royal Air Force.

While the design embodied certain principles which had been well proved in the Bristol Sycamore and, while useful information had been learned about the tandem configuration from the research 173 helicopter, the design of the Belvedere was new in all its engineering aspects. The machine was to be powered by turbine engines with more than twice the installed power of the 173; it was to be approaching twice the weight of the 173. The choice was the Napier Gazelle engine—the first turbine designed primarily for helicopter use. Hence, the helicopter was of new and larger design than that which had preceded it, and the engine was also of new design and type.
Aerodynamic Aspects of Boundary Layer Control for High Lift at Low Speeds
Authors: Williams John , Butler Sidney F. J.
Published: July 2016

The usefulness of boundary-layer control (B.L.C.) at the knee of a trailing-edge flap, over the wing nose close to the leading-edge or at the knee of a leading-edge flap is first noted. Various methods of providing B.L.C. are outlined, comprising slot blowing, slot suction, area suction, inclined air-jets, and specially-designed aerofoil shapes. The aerodynamic aspects of slot blowing over trailing-edge flaps and the wing nose are then examined in detail and both slot suction and area suction are also considered. The associated practical design features required for good performance are discussed and some flight-handling implications are mentioned.
The Manufacturer's Point of View
Authors: White C. B.
Published: July 2016

My Task is to express the manufacturer's point of view and his problems in this field. I can only speak of my own experiences in one Group, and that experience has been chiefly in the civil field. The observations which follow are therefore related mainly to civil aircraft.

In a previous life as a recently qualified solicitor I had the task of presenting to the head of a company, on behalf of my client, a cheque for more than £lm. This payment was made partly because my client's product had run into trouble and partly because there was uncertainty about the legal liability. My experiences in the Aircraft Industry have, therefore, been coloured by a considerable respect for any manufacturer's responsibilities for his product.
Comment on “Delta Wings of Shapes Amenable to Exact Shock-Wave Theory“
Authors: Southgate A. C. , Pedersen J. R.
Published: July 2016

Finite bodies supporting two-dimensional under surface flows behind “contained” plane shock waves of the type discussed by Professor Nonweiler in a recent paper are currently receiving attention from both theoretical and experimental workers. The experimental work already undertaken by the RAE has given hopeful indications that such bodies, characterised by a re-entrant lower surface in cross section, compete closely with more familiar convex bodies in terms of lift/drag ratio, and furthermore preserve the two-dimensional character of the flow away from the design incidence.

The purpose of this note is to point out that:

(a) Delta wings with inverted V or W cross sections are geometrically simple examples of a more general family of possible shapes supporting two-dimensional flow behind a plane shock.

(b) The concept may be extended to bodies supporting two-dimensional flows with multiple shocks (leading to isentropic compression in the limit) or shock-expansion systems.
Vibration of Stiffened Rectangular Plates
Authors: Mahalingam S.
Published: July 2016

The free flexural vibrations of rectangular plates with various boundary conditions have been considered by Warburton. The natural frequencies were calculated by the Rayleigh method, the mode assumed being the product of the characteristic beam functions for the given boundary conditions. Comparison with experimental results shows that the method gives reasonably good approximations. The present note describes a method of obtaining the approximately equivalent characteristic beam functions to enable Warburton's method to be extended to plates having one or more stiffeners parallel to an edge. As a numerical example expressions for the frequencies are derived for a plate, simply supported along two opposite edges, and having a central stiffener parallel to the other two free edges. The results are compared with those given in a recent note by Kirk, who solved the same problem by the Rayleigh-Ritz method, using a mode with one arbitrary parameter. In the case of the fundamental frequency of the unstiffened plate, the characteristic beam function in a direction perpendicular to the free edges is simply a constant, and the solution is less accurate than that given by the Rayleigh-Ritz method. However, numerical analysis of a square plate shows that above a certain stiffener depth the characteristic beam function method is more accurate than the Rayleigh-Ritz method. The two methods are also compared for the 2/2 mode.
The Deflection of a Uniformly Loaded Circular Plate Supported by a Concentric Ring
Authors: Urry S. A.
Published: July 2016

For a given plate and loading the optimum supporting ring radius is shown to be approximately 0·677a, there being a slight variation with Poisson’s ratio.

The “edge square” condition, i.e. zero slope at the circumference of the plate, is also investigated. It is satisfied by a ring radius of , a result which is independent of Poisson’s ratio.

Macaulay’s brackets are used in the analysis as an example of their value in circular plate problems.
Noise From Turbojet Compressors
Authors: Bragg S. L. , Bridge R.
Published: July 2016

The noise radiated from the intakes of turbojet engines during landing is already causing a serious nuisance. This paper, which is largely based on the deliberations of an ad hoc working panel of academic experts formed by Rolls-Royce in 1961, describes the characteristics of the noise and discusses possible mechanisms of generation. The noise appears to be dipole in origin, and to come mainly from the first two compressor stages. It consists of a few discrete tone components, generated mainly by the interactions which occur when one row of aerofoils passes through the wakes of a preceding row; and broad band noise resulting from the turbulence in the wakes and the inherent instability of the boundary layer on the aerofoils.

Some discrete tones may be eliminated over part of the running range by suitable choice of blade numbers and disposition. The broad band noise is unlikely to be reduced without major design modifications involving either a reduction of the air speed relative to the front stage blades, or removal of the boundary layer at their trailing edges.
Fuel Systems Problems in High Speed Aircraft
Authors: Lydiard W. G.
Published: July 2016

The lecture discusses the extent to which the problems met in the fuel systems of subsonic aircraft are aggravated by flight at supersonic speeds and mentions some new problems of considerable severity. These arise from the relatively large fuel quantity required, its high rate of consumption and its heating by kinetic effects or by its use as a heat sink for the aircraft systems. The paper includes a discussion on fuel management and gauging and of the means used to transfer fuel to the engines—showing the relative merits of some of the available pumping techniques. A few comments only are made on the engine control system.

The problem of thermal degradation of the fuel in the tanks and in components leading to the engine is discussed, with particular attention being paid to the difficulty of establishing a valid test method for differing aircraft configurations.

Spontaneous ignition of flammable mixtures in contact with heated surfaces is a hazard that is likely to arise in a particularly acute form at a Mach number of about 3. The progress of research into this phenomenon is briefly outlined, and some of the measures which may be adopted to ensure safety are indicated. Associated with this is the necessity to develop instruments to detect hazardous conditions in various parts of an aircraft, on which some recommendations are made.
The Development of Military Aviation in Australia
Authors: Garing W. H.
Published: July 2016

Because two world wars have exerted such a profound influence on military aviation I have chosen to treat the subject under the following headings:

The Beginning

The First World War.

The Inter-War Years.

The Second World War.

From 1945 to the present.

The Future.

Under each heading I will endeavour to outline the developments and changes in technology and rôle which have taken place, and to indicate the effects these were to have upon each succeeding period.
The Control of Aircraft Noise Perceived at Ground Level
Authors: Richards E. J.
Published: July 2016

The world of hearing is made up of two types of sound— on the one hand, that which provides communication, be it in the form of speech, music or the noise of a car or dog; on the other hand, a noise which interferes with that message, or a sound consisting of an unwanted message, intruding upon a person's thought processes or sleep. It is always difficult to separate these two functions, since one man's noise is another man's message, and this is particularly so for quiet noises heard at night or occurring sharply to frighten and alarm. It is for this reason that the law regarding noise has been less specific than in other fields and it is for this reason that seldom have any clearly defined limits been specified.
The Control of Aircraft Noise Perceived at Ground Level
Authors: Caplan H.
Published: July 2016

This brief paper attempts to outline the present methods for the legal control of aircraft noise and, by emphasising potential weaknesses, draws attention to possible improvements for the future. The views expressed are personal opinions only and must not be interpreted as the views of Insurers generally or the British Aviation Insurance Co. Ltd., in particular.

Professor Richards has clearly described the technical problems involved in the control of aircraft noise. In its essentials, any system of legal control must involve the evolution and enforcement of standards in the design and operation of aircraft, airports and aircraft-affected communities.