bluuebunny/crossref_metadata_2025 huggingface dataset:
An interesting random walk on the non-negative integers
Authors: Neuts Marcel F.
Published: July 2016

A particular random walk on the integers leads to a new, tractable Markov chain. Of the stationary probabilities, we discuss the existence, some analytic properties and a factorization which leads to an algorithmic procedure for their numerical computation. We also consider the positive recurrence of some variants which each call for different mathematical arguments. Analogous results are derived for a continuous version on the positive reals.
Time-dependent rate conservation laws for a process defined with a stationary marked point process and their applications
Authors: Miyazawa Masakiyo
Published: July 2016

We derive two kinds of rate conservation laws for describing the time-dependent behavior of a process defined with a stationary marked point process and starting at time 0. These formulas are called TRCLs (time-dependent rate conservation laws). It is shown that TRCLs are useful to study the transient behaviors of risk and storage processes with stationary claim and supply processes and with a general premium and release rates, respectively. Detailed discussions are given for the severity for the risk process, and for the workload process of a single-server queue.
Characterizations of life distributions by moments of extremes and sample mean
Authors: Jun Cai
Published: July 2016

We consider two weaker partial orderings among non-negative random variables. We derive some characterizations of the equivalence of two life distributions under the weaker orderings. These results lead to the characterizations of the equality of two non-negative random vectors in distributions by moments of extremes and sample mean. As the application of these results, we get various characterizations of the exponential distribution among HNBUE and HNWUE life distribution classes. The main results of Bhattacharjee and Sethuraman (1990), and Basu and Kirmani (1986) are special cases of these more general results.
Simpler proofs of some properties of the fundamental period of the MAP/G/1 queue
Authors: Lucantoni David M. , Neuts Marcel F.
Published: July 2016

By an argument which involves matching sample paths, some useful equations for the probability distribution of the fundamental period in theMAP/G/1 queue are derived with less calculational effort than in earlier proofs. It is further shown that analogous equations hold for theMAP/SM/1 queueing model. These results are then used to derive explicit formulas for the mean vectors of the number served during and the duration of the fundamental period.
An unreliable server characterization of the exponential distribution
Authors: Galambos Janos , Hagwood Charles
Published: July 2016

Consider a workstation with one server, performing jobs with a service time, Y, having distribution function, G(t). Assume that the station is unreliable, in that it occasionally breaks down. The station is instantaneously repaired, and the server restarts the uncompleted job from the beginning. Let T denote the time it takes to complete each job. If G(t) is exponential with parameter A, then because of the lack-of-memory property of the exponential,
P
(T > t) = Ḡ(t) =exp(−γt), irrespective of when and how the failures occur. This property also characterizes the exponential distribution.
Convex majorization with an application to the length of critical paths
Authors: Meilijson Isaac , Nádas Arthur
Published: July 2016

1.

(Y) for all non-negative, non-decreasing convex functions φ (X is convexly smaller than Y) if and only if, for all .

2.

Let H be the Hardy–Littlewood maximal function HY
(x) = E(Y – X | Y > x). Then HY
(Y) is the smallest random variable exceeding stochastically all random variables convexly smaller than Y.

3.

Let X
1
X
2 · ·· Xn
be random variables with given marginal distributions, let I
1,
I
2, ···, Ik
be arbitrary non-empty subsets of {1,2, ···, n} and let M = max (M is the completion time of a PERT network with paths Ij
, and delay times Xi
.) The paper introduces a computation of the convex supremum of M in the class of all joint distributions of the Xi
's with specified marginals, and of the ‘bottleneck probability' of each path.
The non-renewal nature of the quasi-input process in the M/G/1/∞ queue
Authors: Hunter Jeffrey J.
Published: July 2016

Falin (1984) examined the quasi-input process (the flow of service starting times) in the M/G/1/∞ queue and raised the question as to whether this process is a renewal process. We show that, except in the trivial case of instantaneous service, the quasi-input process is never renewal.
Non-Gaussian bifurcating models and quasi-likelihood estimation
Authors: Basawa I. V. , Zhou J.
Published: July 2016

A general class of Markovian non-Gaussian bifurcating models for cell lineage data is presented. Examples include bifurcating autoregression, random coefficient autoregression, bivariate exponential, bivariate gamma, and bivariate Poisson models. Quasi-likelihood estimation for the model parameters and large-sample properties of the estimates are discussed.
Pricing risk when distributions are fat tailed
Authors: Gay Roger
Published: July 2016

In this paper, insurance claims X on [0, ∞) with tail distributions which are O(x
−δ) for some δ > 1 are considered. Markets are assumed arbitrageable, the insurer setting a premium P > E[X]. Setting a premium as a fixed quantile of the loss distribution presents difficulties; for Pareto distributions with F(x) = 1 – (x + l)–δ ‘ultimately' (as δ ↓ 1) E[X] is larger than any quantile. When δ is near 1, premiums determined by weighting outcomes and a rule analogous to the expected utility principle are highly sensitive to change in δ, which is generally unknown or known only approximately. Under these circumstances, to protect insurers' interests, strategies are needed which provide some ‘premium stability' across a range of δ-values. We introduce a class of pricing functions which are functionally dependent on the governing loss distribution, and which are themselves distribution functions. We demonstrate that they provide a coherent framework for pricing insurance premiums when the loss distribution is fat tailed, and enable some degree of premium stability to be established.
Summability methods and negatively associated random variables
Authors: Bingham N. H. , Nili Sani H. R.
Published: July 2016

The paper studies convergence of sequences of negatively associated random variables under various summability methods. The results extend previously known results for independence and complement known results forϕ-mixing.
Optimal couplings are totally positive and more
Authors: Glasserman Paul , Yao David D.
Published: July 2016

An optimal coupling is a bivariate distribution with specified marginals achieving maximal correlation. We show that optimal couplings are totally positive and, in fact, satisfy a strictly stronger condition we call the nonintersection property. For discrete distributions we illustrate the equivalence between optimal coupling and a certain transportation problem. Specifically, the optimal solutions of greedily-solvable transportation problems are totally positive, and even nonintersecting, through a rearrangement of matrix entries that results in a Monge sequence. In coupling continuous random variables or random vectors, we exploit a characterization of optimal couplings in terms of subgradients of a closed convex function to establish a generalization of the nonintersection property. We argue that nonintersection is not only stronger than total positivity, it is the more natural concept for the singular distributions that arise in coupling continuous random variables.
Bounds for moment generating functions and for extinction probabilities
Authors: Brook D.
Published: July 2016

Suppose that we have a non-negative, real valued random variable x, whose distribution is governed by some unknown moment generating function M(t). Suppose further that we are given certain moments of x, then the question to be discussed in this paper is : can we find a sharp upper bounding function for the m.g.f.? It will be shown that this is usually possible both in the single variate case and in its natural extension to the multivariate case.
Applications of the age distribution in age dependent branching processes
Authors: Weiner Howard J.
Published: July 2016

This paper considers asymptotic properties of increasing population age dependent branching processes which have a limiting age distribution. In Section I, the Bellman-Harris model [2] is altered in accord with a suggestion by Kendall [3]. The effect of this modification on the applicable results of [3] is indicated. An extension to the case where each cell passes through a sequence of states to mitosis or proceeds from state to state in accord with a semi-Markov process to mitosis is considered. Section 1.1 considers asymptotic moments for the total number of cells. Section 1.2 treats moments in a sequence-of-states model [4]. Section 1.3 extends the results of 1.2 to a semi-Markov model. Section 1.4 treats various asymptotic lifetime distributions and fraction of cells in a given state for both the sequence-of-states and semi-Markov models.
The single server queue with Poisson input and semi-Markov service times
Authors: Neuts Marcel F.
Published: July 2016

We assume that the successive service times in a single server queue with Poisson arrivals form an m-state semi-Markov process.

The results for the M/G/1 queue are extended to this case. Both the time-dependence and the stationary solutions are discussed.
Equilibrium probability distributions for low density highway traffic
Authors: Newell G. F.
Published: July 2016

If on a long homogeneous highway there is no interaction between cars, then, under a wide range of conditions, an initial distribution of cars will in the course of time tend toward that of a Poisson process with statistically independent velocities for the cars in any finite interval of highway. Here we will generalize this known property to obtain the following. Suppose cars do interact in such a way as to delay a car when it passes another, but the density of cars is so low that we can neglect simultaneous interactions between three or more cars. There will again be equilibrium distributions of cars to which general classes of initial distributions will converge. These equilibrium distributions are superpositions of two statistically independent processes, one a Poisson process of single free cars with statistically independent velocities, and the other a Poisson process of interacting pairs of cars with various velocities. In the limit of zero interaction, the density of pairs vanishes leaving only the Poisson process of single cars as a special case. To the same order of approximation, including the first order effects of interactions, the headway distribution between consecutive cars will still have exponential tail outside the range of interaction.
A stochastic calculus and its application to some fundamental theorems of natural selection
Authors: Mode Charles J.
Published: July 2016

In this paper a stochastic calculus, based on limits in quadratic mean and in probability, is introduced and applied to some fundamental theorems of natural selection. The paper is divided into five principal sections. In Section 2 some elements of stochastic calculus are given, and in Section 3 the stochastic calculus is applied to the haploid case. Section 4 is devoted to the development of an analysis of variance structure applicable to a haploid population, and in Section 5 the results of Sections 3 and 4 are generalized to cover the diploid case. Finally, Section 6 is devoted to two specific examples in which the results of previous sections apply.
Some results involving HNBUE distributions
Authors: Basu A. P. , Kirmani S. N. U. A.
Published: July 2016

A characterization of the exponential distribution in the class of all distributions which are HNBUE or HNWUE is proved. An upper (a lower) bound is obtained on the renewal function of a renewal process when the underlying distribution is HNBUE (HNWUE).
Concepts of dispersion in distributions: a comparative note
Authors: Hickey Raymond J.
Published: July 2016

The Lewis-Thompson (L-T) approach to ordering distributions in terms of dispersion is compared to the dispersion ordering obtained from majorisation. For given conditions, L-T ordering is shown to be stronger than majorisation ordering. Dilation is considered in relation to majorisation ordering.
Pseudo-conservation laws in cyclic-service systems
Authors: Boxma O. J. , Groenendijk W. P.
Published: July 2016

This paper considers single-server, multi-queue systems with cyclic service. Non-zero switch-over times of the server between consecutive queues are assumed. A stochastic decomposition for the amount of work in such systems is obtained. This decomposition allows a short derivation of a ‘pseudo-conservation law' for a weighted sum of the mean waiting times at the various queues. Thus several recently proved conservation laws are generalised and explained.
Probability of maintaining or attaining a structure in one step
Authors: Abdallaoui G.
Published: July 2016

Our concern is with a particular problem which arises in connection with a discrete-time Markov chain model for a graded manpower system. In this model, the members of an organisation are classified into distinct classes. As time passes, they move from one class to another, or to the outside world, in a random way governed by fixed transition probabilities. In this paper, the emphasis is placed on evaluating exact values of the probabilities of attaining and maintaining a structure.
A bivariate counting process
Authors: Watson Ray , Yip Paul
Published: July 2016

We consider a bivariate Markov counting process with transition probabilities having a particular structure, which includes a number of useful population processes. Using a suitable random time-scale transformation, we derive some probability statements about the process and some asymptotic results. These asymptotic results are also derived using martingale methods. Further, it is shown that these methods and results can be used for inference on the rate parameters for the process. The general epidemic model and the square law conflict model are used as illustrative examples.
Winning Rate in the Full-Information Best-Choice Problem
Authors: Gnedin Alexander V. , Miretskiy Denis I.
Published: July 2016

Following a long-standing suggestion by Gilbert and Mosteller, we derive an explicit formula for the asymptotic winning rate in the full-information best-choice problem.
Random collision processes with transition probabilities belonging to the same type of distribution
Authors: Nishimura Shōichi
Published: July 2016

By analogy with statistical mechanics we consider a random collision process with discrete time wand continuous states x ∈ [0, ∞). We assume three conditions (i), (ii) and (iii), which can be applied to Kac's model of a Maxwellian gas, and show that the sequence of probability distributions converges to a probability distribution using their moments.
Some Economic and Operational Questions
Authors: Jackson C. H.
Published: July 2016

The argument for the supersonic transport seems to run as follows: it offers a new and faster way to go places; it might not cost more to do so; it ought to create new wealth, and its influence on human affairs, although not clearly foreseeable, surely will be beneficial. There is a certain amount of evidence to warrant optimism; there are issues of national prestige and well-being; the technical challenge is exciting; so “ Let us somehow find finance and proceed.”

Operators agree that the design and operational problems of supersonic aircraft, one of the possible great advances in transport, are complex and interesting; they might also speculate on its likely social implications, though this is an unrewarding pastime. The operators accept that the aircraft probably will be developed, for it is as much a challenge of the times as have been all the great innovations of routes and vehicles from Columbus right through to our day; but as has always been the case, before any commitment, they must seek assurance of ultimate economic soundness.
A High Temperature Decompression Chamber for Developing Aircraft Environmental Control Systems
Authors: Furlong O. D.
Published: July 2016

The greatly increased performance of both civil and military aircraft since the Second World War has raised problems undreamt of at an earlier period and, from the simple measures originally introduced to improve pilot’s well-being, have sprung the complex installations which are now essential for human survival and comfort and to ensure the proper functioning of vital equipment carried in present day machines.

The term “Environmental Control System” is used for convenience to cover collectively the various cabin and equipment bay, pressure, temperature and humidity control systems that are fitted.
The Validity of the Initial Strain Concept
Authors: Argyris J. H. , Kelsey S.
Published: July 2016

We must thank Dr. Grzedzielski for the clarification of his argument and notation contained in his second note. Unfortunately, this note only shows more clearly the fundamental misconceptions and errors in his arguments. Our own argument as to the generality and validity of the initial strain concept remains unaffected.

In our previous note, we were concerned to explain the initial strain concept, which Dr. Grzedzielski had criticised as “ an oversimplification not generally admissible “ both in the calculation of thermal stresses and as a device to simulate the effects of structural cut-outs and modifications. Here, we prove independently by a direct consideration of the compatibility conditions in the final structure, that the modified stress distribution given by our analysis is the correct one—regardless of the extent of the coupling in the flexibility matrix.
The Development of Short Range Air Transport Through The Use of V/STOL Aircraft
Authors: Ziegler Henri
Published: July 2016

The Fourteenth Louis Bleriot Lecture “ The Development of Short Range Air Transport through the use of V/STOL Aircraft,” by General Henri Ziegler, General Manager, S. A. Louis Breguet, was given before a distinguished audience which included a number of visitors from France, on 23rd March 1961 in the Society's Lecture Theatre.

The President, Dr. E. S. Moult, C.B.E., B.Sc.(Eng.), F.R.Ae.S., M.I.Mech.E., presided at the meeting. Before the formal proceedings the names of 17 members elected to Fellowship of the Society since December 1960 were read by the Secretary. (These names were published in the January, February and March JOURNALS—Ed.)

After congratulating the new Fellows, Dr. Moult said that this was one of those great occasions of the Society when they united with their friends from France to revere the memory of Louis BleYiot, the first aviator to cross the Channel. This was on the 25th July 1909; since then, they would agree, great things had happened in the field of aeronautics.
The Approximate Calculation of Eigenvalues for Certain Second-Order Linear Differential Equations
Authors: Goodey W. J.
Published: July 2016

In a recent technical note, Squire discussed the approximate solution of certain second-order linear differential equations by the method attributed variously to Riccati, Madelung, Wentzel, Kramers and Brillouin (the W.K.B. method), and others. The problem of eigenvalues, frequently met with in this type of equation, does not, however, appear to have received much attention by this method, and in this note a simple formula is developed which appears to give excellent numerical results in many cases.
An Experimental Investigation of Base Flows at Supersonic Speeds
Authors: Badrinarayanan M. A.
Published: July 2016

Detailed measurements in the wake flow behind blunt based two-dimensional and three-dimensional bodies have been made at M = 2. The results throw some light on the behaviour of separated flows and indicate the importance of flow reversal. The results for the two-dimensional body are in agreement with the Crocco and Lees’ theory on separated shear flows. A preliminary study of the effect of air injection at the base shows that the base pressures increase significantly.
The Royal Aeronautical Society The First Fifty Years
Authors: Laurence Pritchard J.
Published: July 2016

It has been recorded in the Annual Reports that String-fellow made a trip to California with Frederick Marriott, who had been the publicity agent for Henson's project of 1843 and the subsequent experiments of Henson and Stringfellow. Marriott, who had become editor of the San Francisco News Letter, began to interest the Californians in a project of a large aeroplane partly lifted by gas, a project which had been suggested in previous years without number.
A Note on the Choice of Co-ordinate Functions for the Rayleigh-Ritz Method
Authors: Singer Josef
Published: July 2016

The Rayleigh-Ritz method for approximate solution of equilibrium or stability problems in elasticity is based on the theorem of the minimum of the total potential. Hence the assumed displacements have to satisfy only the geometrical boundary conditions of the problem in order to be admissible. The displacements are expressed as a series of suitable chosen functions, called co-ordinate functions, multiplied by parameters which are determined by the minimisation procedure of the method. Except for the essential requirement that these co-ordinate functions have to satisfy the geometrical boundary conditions of the problem, no general rule for their choice can be given, and experience and physical considerations have to be relied upon.
Stress Concentrations in Tensile Strips with Central Notches
of Varying End Radii
Authors: Papirno Ralph
Published: July 2016

Using relations derived by Dixon and Inglis, the values of the elastic stress concentration factor for a fixed length notch in a finite width tensile strip with a varying notch end radius have been obtained in the form:

Photoelastic tests on internally notched tensile strip models showed excellent agreement with the analytical results.
Smoke for Flow Visualisation — A Warning
Authors: Maltby R. L. , Whitmore G.
Published: July 2016

In some recent tests we have successfully used the smoke from smouldering paper to indicate the flow of air in the vortices above slender wings at speeds in the region of 200 f.p.s. Smokes of this kind are particularly suitable for the production of the large volume flows required because in certain conditions they do not lose density by condensation in long supply tubes.
Economics of Ramjets as Satellite Launchers
Authors: Probert R. P. , Mallinson D. H
Published: July 2016

Although this talk, to conform to the general pattern of the Symposium has the word “Economics” in its title, the plain fact is that nobody at the present time is able to make a reliable assessment of the economics, in the usual financial sense, of ramjet launchers.

Rockets have already demonstrated their ability to fill this role and assessments of the cost can be based upon real experience, as Mr. Rothrock's paper clearly shows. The use of ramjets for this duty, or more strictly for part of the duty, since we cannot hope to provide ramjet power all the way from take-off to orbit, remains problematical. The first step must be to prove the feasibility of using ramjets and only when some of the major problems on which feasibility hinges have been solved, can any really rational assessment of the probable cost be made.
Economics of Ground Stations
Authors: Milne K.
Published: July 2016

The Ground Stations to be discussed are the large Radio Stations required for a variety of Astronautical applications. The principle categories are:–

Radio Astronomy,

Telemetry and Control,

Communications,

Military applications,

and many examples can be found in each category. The Radio Astronomer is interested in the distribution, intensity and spectrum of all extra-terrestial radiations. He will also be interested in telemetry of signals from earth satellites used as observatories beyond the earth's atmosphere. At the other end of the scale, the military authorities are involved in the detection and tracking of hostile satellites as well as the telemetry of data from their own reconnaissance satellites.
The Electrostatic Problem in Aircraft Fuellin
Authors: Winter E. F.
Published: July 2016

The generation of electric charges in hydrocarbon fuels during transfer has been recognised for many years as an explosion hazard, and the oil companies have taken precautions against this danger as a matter of routine. Usually the hazard arises only in the early stages of handling, and is associated with the fast pumping of large quantities of product, particularly into large refinery tanks and tankers. The possibility of a hazard usually becomes less as the product approaches the consumer, owing to the successively smaller quantities pumped.
Elastic Instability of a Stringer on Thin Sheets
Authors: Caldwell J. B.
Published: July 2016

Figure 1 illustrates a load diffusion problem which occurs in ship structural design, and which may also be relevant to aircraft structures. A load applied to one end of a stringer is diffused into the attached sheet and eventually reacted by shearing forces at the longitudinal edges. The transverse edges of the sheet and the other end of the stringer are not loaded.

Various methods, which differ in their assumptions regarding stresses and displacements in the sheet, are available for tackling this problem. For calculating the distribution of load or stress in the stringer it makes little difference which method is used. The “finite stringer” method of reference (1) is the simplest and should be sufficiently accurate for most cases.
Radioactive Contamination of Commercial Aircraft
Authors: Doran D.
Published: July 2016

When atmospheric testing of nuclear devices was resumed in the latter part of 1961 it was found that certain commercial aircraft were being contaminated by airborne radioactive debris to such a degree that decontamination was required, with associated protection of personnel. Some airlines seemed reluctant to publish detailed information on the position. BOAC, however, recognised the phenomenon as a virtually permanent one and in recent months has been setting a lead in developing the process of measurement and control from a somewhat academic exercise to a properly understood engineering routine. When the nature of the hazard is understood—and particularly the all-important distinction between external radiation and internal radiation—it can be seen that, in fact, passengers and crews are not at risk at all, and that handling and maintenance personnel need not be concerned if the contaminated surfaces are washed by an essentially wet process and personal hygiene rules are observed where necessary.
Some Boundary Layer Measurements on a Slender Wing at Supersonic Speeds
Authors: Griffiths R. T.
Published: July 2016

Boundary layer measurements have been made at four positions on a slender gothic wing of aspect ratio 0·75. Test's were made over a range of incidence at M=1·42 and 1·82. With transition fixed by roughness near the leading edge the boundary layer thickness varied little with small positive or negative incidence but was reduced at larger incidences, this being most marked at positive incidence for positions nearest the leading edge due to the influence of the wing vortex. With the exception of positions in the vicinity of the vortex, a good estimate of the boundary layer thickness was given by the theory for incompressible flow over a flat plate and an excellent estimate of the variation of local static pressure and Mach number with incidence was given by not-so-slender wing theory.
Man and Military Space
Authors: Perkins C. D.
Published: July 2016

The Fifty-First Wilbur Wright Memorial Lecture, “Man in Military Space”, was given by Professor C. D. Perkins, Chairman of the Department of Aeronautical Engineering at Princeton University, on 23rd May 1963. Professor A. R. Collar, M.A., D.Sc, F.R.Ae.S., F.A.I.A.A., F.C.A.S.I., President of the Society, was in the Chair. Professor Collar presented the Lawrence Hargrave Memorial Lecture Medallion to Professor A. V. Stephens on behalf of the Melbourne Branch of the Australian Division. He explained that Professor Stephens had delivered the first Lawrence Hargrave Memorial Lecture in 1956 when he was the Lawrence Hargrave Professor of Aeronautical Engineering at Sydney University, but the Australian Division had not then had the Medallion struck. Professor Stephens was now Professor of Aeronautical Engineering at Queen's University, Belfast.
Some Aspects of Turboshaft Engine Installations in Multi-engined Helicopters
Authors: Sibley J. D.
Published: July 2016

In projecting future turboshaft engines for helicopter appUcations the engine designer is faced with the problem of selecting the size of engine to meet the likely size, configuration, performance and economic requirements of future helicopters. It is also desirable to meet as many different helicopter applications as possible with the same basic engine design. The helicopter designer is, likewise, faced with the problem of which engines could be available for the future and how they could best be tailored to his requirements. This is the perennial problem of the “chicken and the egg.”

This paper summarises the results of a preliminary study of the problem, based on some assumed airworthiness requirements and simple engine assumptions and, while it makes no claim to be a method in itself of assessing the problem, it does show the sort of trend which could be expected.
The Development of the P.531
Authors: Ciastula T. L.
Published: July 2016

The development of the P.531 family of helicopters covering the period of approximately 5 years is presented. Evolution from the first basic aircraft towards a land-based general purpose helicopter, the Scout, and towards a shipborne helicopter operating from small ships, the Wasp, is presented. The basic design features of the Scout are described briefly as broadly representative of the family. Development experiences are reviewed under the following main headings:—

(i) Ground resonance investigations.

(ii) Development of satisfactory flight handling characteristics including engine/rotor control system

(iii) Substantiation of structural integrity,

(iv) Development of systems and operational equipments.

(v) Environmental and climatic testing.

Development of miniaturised auto-stabilisation/autopilot system, for small helicopters, considered to be an important programme, is briefly reviewed. More detailed consideration is given to operations from small ships. The possible design solutions to ensure satisfactory operation from small ships are briefly reviewed, and the reasons for the solution chosen for the Wasp, i.e. four wheel undercarriage are given. Development experiences with the preferred solution are briefly described. It is shown that for operation from small ships in the Naval application a fair degree of complexity is unavoidable independent of the size of a helicopter.

Some statistical data on the development efforts expended are given and some tentative conclusions drawn, aiming at determination of the necessary conditions which would promote a relatively speedy development of a new helicopter.
Effect of Density on Air-Tunnel Measurements
Authors: Naudascher Eduard
Published: July 2016

In air-tunnel studies it is often necessary to measure the absolute magnitudes of pressure and velocity or to conduct tests at a given Reynolds number. For this purpose it is important to determine precisely the density of the air in the tunnel as a function of temperature, humidity, and barometric pressure. Because of the laborious evaluation involved, the influence of the latter two quantities is usually neglected, despite the fact that it is of the same order of magnitude as the influence of temperature. In the following a nomogram is developed which permits determination of the air-density without time-consuming calculation. The effect of density changes upon pressure and velocity measurements is illustrated by a factor C for the instrument most commonly employed in air-tunnel studies: a Pitot tube as the sensing element and a differential manometer as the recording device. An analogous factor could be derived for other measuring techniques.
Heliport Location and Design
Authors: Slocombe A. E.
Published: July 2016

A considerable amount of material has been produced over the past few years on the subject of heliports and therefore it is proposed to make only brief reference to general heliport requirements and the national and international activity in this field. The application of these requirements to the proposed heliport at Penzance will then be discussed.
A Review of Slotted-Wall Wind Tunnel Interference Effects on Oscillating Models in Subsonic and Transonic Flows
Authors: Wight K. C.
Published: July 2016

Measurements of oscillatory derivatives made in various tunnels at the NPL over the past few years have indicated that slotted walls, as used in high-speed tunnels, may give rise to large interference effects on damping derivatives. Other workers in this field, notably in America, have also observed interference effects both with solid and with slotted walls. This paper presents the available evidence, so that those making similar measurements may be aware of the effects.
Maximum Range of Hypersonic Ramjets
Authors: Horlock J. H.
Published: July 2016

Recent studies of the performance of high-speed aircraft have emphasised the importance of engine-airframe integration. For example, Probert and Mallinson, and Bragg have pointed out the advantages of jet deflection in producing extra lift with little penalty in decreased thrust. Townend has drawn attention to producing thrust or lift on high-speed aircraft by external heat addition, and has calculated the effects on the range of the aircraft.
Some Basic Studies of Liquid Propellant Injection Processes
Authors: Lewis J. D.
Published: July 2016

The recent analytical studies of rocket engine combustion based on propellant vaporisation as the rate controlling parameter, especially those by Spalding, and Priem and Heidmann, have contributed greatly to our appreciation of the mechanism of stable combustion. Critical combustion experiments on a small scale engine have shown fair agreement with vaporisation predictions, but have also revealed the need to understand and improve the mixing process.

In parallel with performance measurements in a combustion system, detailed measurements of the atomisation process including the break-up mechanism and drop-size distribution have been made. However, there are many gaps in our knowledge of the subject and further work remains to be done.

It is thought that the high-speed photographic and gas sampling techniques developed for these investigations provide useful research tools for more detailed studies of the problems.
The Thrust Augmentation of Rocket Motors at High Altitudes
Authors: Harper D. J.
Published: July 2016

Rocket motors designed for operation in ground launched vehicles generally have nozzle expansion ratios giving optimum thrust at low altitude (about 20 000ft). At higher altitudes the jets are under-expanded and the thrust is less than the maximum available with nozzles of higher expansion ratio. Some of this lost thrust may be regained by suitable design of the propulsion bay geometry, without the low altitude disadvantages of high expansion ratio nozzles. In addition, where the vehicle is propelled by clustered motors, interaction between the jet effluxes at high altitudes can be used to develop an extra thrust acting on the base of the vehicle. The flow changes, from low to high altitude, leading to these effects are described.

The results of the first firings of Black Knight drew attention in this country to these effects. Model tests in both the U.K. and America have confirmed them and indicated various means by which the thrust of clustered rockets may be augmented; these are described and consideration is also given to the side effects of thrust augmentation on vehicle control and propulsion bay heating. A full scale experiment, planned for the end of 1962 is outlined and possible future applications are considered.
A Technical History of the Mercury Programme
Authors: Williams Walter C.
Published: July 2016

In the light of what was now known, the only change that might have been made in the programme would have been the elimination of the animal flight; actually, systems for manned flight were ready to “go” at that time. The lecturer considered that the ballistic part of the programme would still have been needed to get the people ready for this sort of thing as well as for checking the systems control and for developing the recovery technique. The sea landing approach was chosen because it was a simpler system to develop within the brief time schedule available and would provide the lowest impact loads on the pilot and spacecraft alike.
Vibration of Stiffened Rectangular Plates
Authors: Sundara Raja Iyengar K. T. , Jagadish K. S.
Published: July 2016

The vibrations of stiffened plates have been considered by Kirk and Mahalingam. Kirk has treated plates with several stiffeners and also a plate with a single stiffener. For plates with several stiffeners he uses the Rayleigh Method as employed by Warburton. The calculated frequencies have been shown to compare favourably with the experimental frequencies when the stiffness has been taken as ef3/3 for a stiffener. While considering the plate with a single stiffener he has replaced the stiffener by a line of massless springs the spring constant of which is determined on the basis of certain approximations. The Rayleigh method has then been applied to solve the simplified problem. A plate with two opposite edges free and the other two simply supported with a central stiffener parallel to the free edges has also been considered by Kirk.
A Psychologist's Point of View
Authors: Corkindale K. C.
Published: July 2016

The main contribution of psychology to the design of displays up to the present time has been in advising on detailed points of design. It is suggested that there are three areas in which psychology can make a useful contribution; these are

(a) in stating the basic characteristics of the human operator, particularly the working of the perceptual mechanism,

(b) in stating the effect of environmental conditions on performance, and

(c) in assessing the information required and in advising on man's rôle in the system.
Difficulties and Advantages of Supersonic Civil Transport—A Discussion
Authors: Russell A. E.
Published: July 2016

We have heard that the SST project is the largest and most expensive project ever undertaken. It is fairly large and it is expensive. When making comparisons, however, it is important to remember that major developments in aviation have rarely been cheap. For some civil projects the subsidy has been indirect. For example, the present generation of successful American long range air liners, notably the Boeing 707, has succeeded to a large family of military progenitors and thereby enjoyed its massive inheritance. Even so, funds spent on the 707 development must have been substantial, for many hundreds of aircraft needed to be sold before the break-even point was reached. Those firms in the USA, lacking the advantage of a military ancestor, must have seen the prospect of profitability in the civil field, in straight competition with those better placed, as an illusive difference between two very large sums—launching expenditure and prospective income.

Now, and in the future, all civil projects everywhere must fight for existence without benefit of feed-back from a related defence project.

The question is whether to fight at all in this remorseless arena. Presumably nearly all at a meeting of the Royal Aeronautical Society would not agree that this country should reject the challenge.
Operational Research and Aviation Management
Authors: Longton P. A.
Published: July 2016

This paper is in effect an illustrative case study based in part on an actual study but including also a large amount of subsequent work.

In the previous paper the cost structure of an air transport system was considered and some models appropriate to capital investment and procurement programmes were discussed. The importance of obtaining optimal utilisation of this capital equipment was stressed, and delays, especially during turn-round of aircraft at airports, were mentioned as one group of factors which reduce utilisation both of aircraft and airports and which therefore merit attention by the OR scientist.

Instead of proceeding immediately with the broad survey of models referred to in the second article, the opportunity is taken at this point to consider intensively one particular set of investigations focused on this problem area. It is based on field work done some years ago on the apron of an airport by A. M. Lee and the author, and is concerned with the human controller of turn-round operations.

It is of special interest in that it demonstrates the increasing ability of science to tackle problems previously considered intractable to any rigorous scientific method.
Steps Towards Lower Operating Costs with Conventional Jet Transports
Authors: Thomas C. J. Hamshaw
Published: July 2016

The continued expansion of air transport is bound up with its possibility of producing ever lower fares. Thus the future of both sides of industry depends on the success in this field. This paper notes some of the difficulties seen from the manufacturer's side in this rather inexact science. It is essentially a personal view not associated with any one Company's views, but based on some years of experience in the industry. It answers no questions, but is aimed rather at provoking discussions on some of the important issues, particularly those which tend to be taken for granted.

It should be stated also at the outset that this paper is obviously affected by the current beleaguered state of the British airframe industry. There is nothing in it, however, which does not apply to any nation's airframe industry and it is not intended as criticism of the UK one. It is certainly not the intention to add to the volume of anti-British comment which is so valuable to our competition.
Design of Spacecraft for Experiments in the ESRO Scientific Programme
Authors: Lines A.W.
Published: July 2016

The principles of the design of spacecraft are well known and it is not the intention of this paper to review them. Rather it is the intention to review the possibilities of special purpose and multi-purpose designs in relation to the boundary conditions established for the creation of the European Space Research Organisation. These boundary conditions are contained in the Convention and the Protocols for the Organisation, which came into force in March 1964, after signature in June 1962.

The Convention states that: “The purpose of the Organisation shall be to provide for, and to promote, collaboration among European States in space research and technology, exclusively for peaceful purposes.” In addition, it states that: “In order to fulfil its purpose the Organisation shall carry out a programme of scientific research and related technological activities” and some of these are listed in the Convention.
An Improved Axial Flow Compressor Design
Authors: Doyle M. D. C.
Published: July 2016

In using the method of stage stacking to compute the off-design performance of multi-stage axial compressors, it has been observed that the limitation on performance at speeds above the design speed has been set by the stall and the choke points of the rear stages(1). Thus if the rear stages can absorb a wide range of mass flows between stalled conditions and choked conditions, a better performance could be obtained.

Compressor stages using low stagger blades will absorb a large range of mass flow between stalled and choked condition; but because of the high axial velocity involved in their use, they tend to be unsuitable for low pressure stages because of the high Mach number obtained. In the higher pressure stages the increased gas temperature will lower the Mach number for the same velocity and give more efficient operation.
The Mergers in the UK Aircraft Industry, 1957-60
Authors: Hartley K.
Published: July 2016

The Plowden Committee has been considering ”… the future place and organisation of the Aircraft Industry in relation to the general economy of the country taking into account the demands of national defence, export prospects, the comparable industries of other countries, and the relationship of the Industry with Government activities in the aviation field.” Against this background of inquiry into the future structure of the Industry, it seems opportune to consider in some detail the actual process of mergers and reorganisation which occurred in the Aircraft Industry during the period 1957-60. This paper will attempt to explain the reasons for the mergers, the development of Government policy towards the Industry during this period, and the actual process of events which produced the recent industrial structure.
Naval Aircraft
Authors: Petty G. E.
Published: July 2016

“Built like a—battleship”. I always remember this cryptic remark from one of the deck crew of the Courageous after the first deck landing on this Carrier of the Blackburn Skua well over twenty-five years ago. I still don't know whether this was a compliment or not, but it aptly fitted the rugged aircraft required for the very arduous Naval duties. The Skua was in fact the first monoplane specifically designed for the Navy, and it followed a long string of biplanes starting with the Dart, a torpedo carrying aircraft designed at Brough as a “private venture” immediately after the First World War.

None of these machines were particularly attractive in appearance, restricted as they were in span, length, height and so on, and handicapped with folding wing requirements, and the provision of an alternative float seaplane undercarriage that in most cases determined a large proportion of the main structure of the aircraft.
Transient Vibration by Vector Methods
Authors: Morley A. W.
Published: July 2016

In control theory, stability is investigated by established techniques such as the root-locus method. The same techniques may be applied to the control equivalent of a mechanical system and will show the transient state of the system. Vector methods such as are used to solve vibration problems may also be extended to give transients.

This note gives a vector representation of the transient vibration of a one degree of freedom system possessing inertia, elasticity and viscous damping. For the transient which is set up by a change in the steady vibration of the system, the initial amplitude and phase angle are readily found by vector methods. This information is sufficient to define the transient.
Arbitrary Quadrilateral Spar Webs for the Matrix Displacement Method
Authors: Argyris, J. H.
Published: July 2016

Ever since the realisation of the matrix Displacement Method, the introduction of a kinematically satisfactory spar element has remained a difficult and, as yet, not fully resolved problem. Two cardinal points have to be considered in establishing a suitable spar model: first, it must reproduce adequately both shearing and bending deformations, and second, it must satisfy everywhere the kinematic compatibility conditions, especially at the junction with the wing cover. Of course, if we were to restrict ourselves to a uniform rectangular element, the corresponding theory could be written down in a few lines. However, from the practical point of view, it is essential to take account, ab initio, of taper, and this necessitates some subtle considerations, especially if we have to allow for asymmetrical taper, as becomes indispensable with some modern flying vehicles.