bluuebunny/crossref_metadata_2025 huggingface dataset:
The general N server finite queue
Authors: Kapadia Asha Seth
Published: July 2016

Kingman (1962) studied the effect of queue discipline on the mean and variance of the waiting time. He made no assumptions regarding the stochastic nature of the input and the service distributions, except that the input and service processes are independent of each other. When the following two conditions hold:

(a)

no server sits idle while there are customers waiting to be served;

(b)

the busy period is finite with probability one (i.e., the queue empties infinitely often with probability one);

he has shown that the mean waiting time is independent of the queue discipline and the variance of the waiting time is a minimum when the customers are served in order of their arrival. Conditions (a) and (b) will henceforward be called Kingman conditions and a queueing system satisfying Kingman conditions will be referred to in the text as a Kingman queue.
On the single server queue with preemptive service interruptions
Authors: Şahin İzzet
Published: July 2016

In [4], the limiting behaviour of a stochastic system with two types of input was investigated by reducing the problem to the solution of an integral equation. In this note we use the same approach to study the equilibrium waiting time problem for the general single server queue with preemptive service interruptions. (For a comprehensive account of the existing literature on queues with service interruptions we refer to [2] and [3].)
Some asymptotic properties of a two-dimensional periodogram
Authors: Pagano M.
Published: July 2016

The two-dimensional periodogram has been proposed as an estimator of the spectral density of a real, homogeneous, random field defined over a regular lattice on the plane. In the present paper, results pertaining to the asymptotic distributional properties of such a periodogram are obtained. These results generalize some of the work of Hannan (1960), Walker (1965) and more directly Olshen (1967a,b) concerning asymptotic theory for the periodogram of a stationary time series. Although extension of asymptotic theory for one-dimensional periodograms to a parallel theory for two-dimensional periodograms is not completely straightforward (one runs into problems akin to the problems encountered in extending the theory of one-dimensional trigonometric series to two dimensions), further extensions to asymptotic theory for p-dimensional periodograms (p > 2) is easily accomplished by an obvious mimicry of the definitions, theorems and proofs for the two-dimensional case. Since the notation required for the p-dimensional case is rather cumbersome, we have chosen to give results only for two-dimensional periodograms.
The spitzer identity for some bivariate processes in queueing theory: an algebraic approach
Authors: Schmidt Gerd
Published: July 2016

This note deals with a purely algebraic development of the Spitzer identity for a bivariate Markov process, which is important for random walks, dams and queues. This identity, comprising the results of Kingman on the process, has been known for a long time in an analytic form as a solution of a certain integral equation. The algebraic approach leads to explicit results of interesting structure. In particular, the bivariate distribution of (Yn, Zn) can be expressed in terms of the marginal distributions of the stochastically dependent variablesYnandZn.
Size-biased filtering of Poisson–Dirichlet samples with an application to partition structures in genetics
Authors: Hoppe Fred M.
Published: July 2016

A characteristic property of the Ewen sampling formula is shown to follow from the invariance under size-biased sampling of the Poisson–Dirichlet distribution.
Discrimination between monotonic trends and long-range dependence
Authors: Künsch H.
Published: July 2016

We show that the periodogram behaves differently for a weakly dependent process with a small monotonic trend and a stationary strongly dependent process. In the former case it has a non-central-distribution with noncentrality parameter tending to 0 uniformly outside intervals. In the latter case it has λα−1times a central-distribution, 0 <α< 1.
Avalanches of electrons in a gas
Authors: Steutel F. W.
Published: July 2016

The motion of electrons through a gas of particles is modelled as a two-state process: an electron is alternatingly moving and being held captive by a non-moving particle, during exponentially distributed periods.

The model contains a parameterp, the probability that collision of an electron with a gas particle does not lead to its capture but produces an extra electron.

The quantity of interest is the currentC(t) produced by the moving electrons, as a function of time.
Asymptotic behavior of Hill's estimate and applications
Authors: Lo Gane Samb
Published: July 2016

The problem of estimating the exponent of a stable law is receiving an increasing amount of attention because Pareto's law (or Zipf's law) describes many biological phenomena very well (see e.g. Hill (1974)). This problem was first solved by Hill (1975), who proposed an estimate, and the convergence of that estimate to some positive and finite number was shown to be a characteristic of distribution functions belonging to the Fréchet domain of attraction (Mason (1982)). As a contribution to a complete theory of inference for the upper tail of a general distribution function, we give the asymptotic behavior (weak and strong) of Hill's estimate when the associated distribution function belongs to the Gumbel domain of attraction. Examples, applications and simulations are given.
Embedding sequences of successive maxima in extremal processes, with applications
Authors: Ballerini Rocco , Resnick Sidney I.
Published: July 2016

Consequences of embedding sequences {Mn
} in an extremal-F process are discussed where Mn
represents the maximum of n independent (but not necessarily identically distributed) random variables. Various limit theorems are proved for the sample record rate, record times, inter-record times, and record values. These results are illustrated with applications to three particular record models: the Yang (1975) record model where population size increases geometrically, a record model where linear improvement is present, and a record model incorporating features of the previous two.
Quantile spectral analysis and long-memory time series
Authors: Parzen Emanuel
Published: July 2016

An approach to time series model identification is described which involves the simultaneous use of frequency, time and quantile domain algorithms; the approach is called quantile spectral analysis. It proposes a framework to integrate the analysis of long-memory (non-stationary) time series with the analysis of short-memory (stationary) time series.
Identifiability of time series models with errors in variables
Authors: Solo Victor
Published: July 2016

Straightforward derivations are provided for some identifiability results for time series models with errors in variables.
Consistency of model selection and parameter estimation
Authors: Shibata Ritei
Published: July 2016

The relationship between consistency of model selection and that of parameter estimation is investigated. It is shown that the consistency of model selection is achieved at the cost of a lower order of consistency of the resulting estimate of parameters in some domain. The situation is different when selecting autoregressive moving average models, since the information matrix becomes singular when overfitted. Some detailed analyses of the consistency are given in this case.
The Box-Jenkins approach to random coefficient autoregressive modelling
Authors: Nicholls D. F.
Published: July 2016

Recent time series research has been directed towards the relaxation of the assumption that time series models have constant coefficients. One class of models to emerge as a result of this has been that of random coefficient autoregressive models. This paper demonstrates how the Box-Jenkins three-step approach of model specification, estimation and diagnostic checking may be applied to this class of models.
Parameter estimation for finite-parameter stationary random fields
Authors: Rosenblatt M.
Published: July 2016

The concept of strong mixing is used to obtain a generalization of results on the asymptotic distribution of finite-parameter estimates of linear processes and extend them for stationary sequences and random fields.
A note on the two-sex population process
Authors: Gani J. , Tin Pyke
Published: July 2016

This paper considers the two-sex birth-death model {X(t), Y(t); t ≧ 0}; an explicit solution is obtained for its probability generating function. It is shown that moments of the process can be found directly from the Kolmogorov forward equations for the probabilities. An integral equation approach is also used to throw light on the structure of the process.
On the use of time series representations of population models
Authors: Heyde C. C.
Published: July 2016

Many population models which are far from stationarity can nevertheless be written in autoregressive format, perhaps with random coefficient. It is the thesis of this paper that procedures developed for stationary time series models are a useful guide to inferential results for population processes and may indeed be directly applicable. The illustrations concentrate on estimation of the matrix of mean vital rates in an age-structured population.
Correlation and variability in birth processes
Authors: Donnelly Peter , Kurtz Thomas , Marjoram Paul
Published: July 2016

Faddy (1990) has conjectured that the variability of a pure birth process is increased, relative to the linear case, if the birth rates are convex and decreased if they are concave. We prove the conjecture by relating variability to the correlation structure of certain more informative versions of the process. A correlation inequality due to Harris (1977) is used to derive the necessary positive and negative correlation results.
Tail behaviour of the stationary density of general non-linear autoregressive processes of order 1
Authors: Diebolt Jean , Guégan Dominique
Published: July 2016

We examine the main properties of the Markov chain Xt
= T(Xt

– 1) + σ(Xt

– 1)ε t
. Under general and tractable assumptions, we derive bounds for the tails of the stationary density of the process {Xt
} in terms of the common density of the ε t
's.
Behavior of the supercritical phase of a continuum percolation model on ℝd
Authors: Tanemura Hideki
Published: July 2016

A continuum percolation model on is considered. Using a renormalization technique developed by Grimmett and Marstrand, we show a continuum analogue of their results. We prove the critical value of the percolation equals the limit of the critical value of a slice as the thickness of the slice tends to infinity. We also prove that the effective conductivity in the model is bounded from below by a positive constant in the supercritical case.
Dynamic conditional marginal distributions in reliability theory
Authors: Shaked Moshe , Shanthikumar J. George
Published: July 2016

Motivated by the need of studying a subset of components, ‘separate' from the other components, we introduce a new definition of ‘marginal distribution'. This is done by fixing the lives of the other components, but without the ‘knowledge' of the components of interest. Formally this is done by minimally repairing the components of no interest up to a predetermined time. Preservation properties of these ‘conditional marginal distributions', with respect to several stochastic orderings, are obtained. Also, inheritance of positive dependence properties, by the conditional marginal distributions, is shown. In addition, the preservations of dynamic multivariate aging properties, by the dynamic conditional marginal distributions, are obtained. The definitions and results are illustrated by a set of examples. Some applications for modelling ‘combinations' of sets of random lifetimes, and for bounding complex sets of random lifetimes, are described.
Servers in tandem with communication and manufacturing blocking
Authors: Avi-Itzhak Benjamin , Halfin Shlomo
Published: July 2016

Tandem queueing systems with blocking are frequently used in modelling of data communications and production transfer lines. We study such a system with no intermediate queues under the communication and the manufacturing blocking schemes and the assumption of just-in-time input. Explicit expressions for residence times, departure times, equilibrium throughput and some other measures of performance are obtained for the case of equal service requirements at all servers. This case is shown to be the ‘worst’ under the manufacturing blocking scheme, but not under the communication blocking scheme. An approximation formula is proposed for the equilibrium throughput in the case of exponential i.i.d. service times under the manufacturing blocking scheme.
First-order autoregressive logistic processes
Authors: Sim C. H.
Published: July 2016

We propose an AR(1) model that can be used to generate logistic processes. The proposed model has simple probability and correlation structure that can accommodate the full range of attainable correlation. The correlation structure and the joint distribution of the proposed model are given, as well as their conditional mean and variance.
Component allocation for a distributed system: reliability maximization
Authors: Revyakov Mikhail
Published: July 2016

An optimal allocation of subsystems depending on the system structure and reliability ordering of inherent subsystem components is determined, in the presence of various external influences on the reliability of components in different locations. It is carried out with the help of L-superadditive functions and Schur-convex functions.
Tail Asymptotics for Monotone-Separable Networks
Authors: Lelarge Marc
Published: July 2016

A network belongs to the monotone separable class if its state variables are homogeneous and monotone functions of the epochs of the arrival process. This framework contains several classical queueing network models, including generalized Jackson networks, max-plus networks, polling systems, multiserver queues, and various classes of stochastic Petri nets. We use comparison relationships between networks of this class with independent and identically distributed driving sequences and the GI/GI/1/1 queue to obtain the tail asymptotics of the stationary maximal dater under light-tailed assumptions for service times. The exponential rate of decay is given as a function of a logarithmic moment generating function. We exemplify an explicit computation of this rate for the case of queues in tandem under various stochastic assumptions.
A Paradox for Admission Control of Multiclass Queueing Network with Differentiated Service
Authors: Ye Heng-Qing
Published: July 2016

In this paper we present counter-intuitive examples for the multiclass queueing network, where each station may serve more than one job class with differentiated service priority and each job may require service sequentially by more than one service station. In our examples, the network performance is improved even when more jobs are admitted for service.
Supercritical age-dependent branching processes with immigration
Authors: Athreya K. B. , Parthasarathy P. R. , Sankaranarayanan G.
Published: July 2016

A branching process with immigration of the following type is considered. For everyi, a random numberNiof particles join the system at time. These particles evolve according to a one-dimensional age-dependent branching process with offspring p.g.f.and life time distributionG(t). Assume. Then it is shown thatZ(t)e–αtconverges in distribution to an extended real-valued random variableYwhereais the Malthusian parameter. We do not require the sequences {τi} or {Ni} to be independent or identically distributed or even mutually independent.
Physical nearest-neighbour models and non-linear time-series: III Non-zero means and sub-critical temperatures
Authors: Bartlett M. S.
Published: July 2016

The product moment equations previously derived are first discussed for the infinite one- and two-dimensional Ising (or autologistic) model in the case of non-zero mean, as a prelude to an examination of the probability structure in the higher-dimensional (and nominally zero mean) case below the ‘critical temperature’. Of two simple possible models, A and B, both consistent with the division of the product moment p into ergodic, and long-range non-ergodic, components, such that ρ = r (1 – m
2) + m
2, where r is the intrinsic correlation coefficient, it is shown that the second model B appears appropriate to the three-dimensional ‘spherical model’, but the first model A to the Ising model. Model A is defined by xi = yi
+ M, where M = +m or –m, and E{yi
} = 0; and Model B by
Stochastic bounds for heterogeneous-server queues with Erlang service times
Authors: Yu Oliver S.
Published: July 2016

This paper establishes stochastic bounds for the phasal departure times of a heterogeneous-server queue with a recurrent input and Erlang service times. The multi-server queue is bounded by a simple GI/E/1 queue. When the shape parameters of the Erlang service-time distributions of different servers are the same, these relations yield two-sided bounds for customer waiting times and the queue length, which can in turn be used with known results for single-server queues to obtain characterizations of steady-state distributions and heavy-traffic approximations.
On supercritical Galton-Watson processes allowing immigration
Authors: Pakes A. G.
Published: July 2016

We establish the absolute continuity of the limit random variables of two supercritical Galton-Watson branching processes, one allowing unrestricted immigration and the other having a state dependent immigration component.
Weak limits of sample range
Authors: Haan Laurens De
Published: July 2016

Necessary and sufficient conditions are obtained for the weak convergence of the sample range of i.i.d. random variables as the number of observations tends to infinity.
Busy period of queues with state dependent arrival and service rates
Authors: Hadidi Nasser
Published: July 2016

A technique is derived providing for the analysis of busy period processes in the queueing models M/Mn
/1 and Mn
/M/1; queueing models with state dependent service and arrival rates respectively. A single treatment covers both models and no separate analysis is required.
On two stationary distributions for the stable GI/G/1 queue
Authors: Lemoine Austin J.
Published: July 2016

This paper provides simple proofs of two standard results for the stable GI/G/1 queue on the structure of the distribution functions of the stationary virtual waiting time and the stationary queue-length Our argument is applicable to more general single server systems than the queue GI/G/1.
On the busy period of discrete-time queues
Authors: Gergely T. , Török T. L.
Published: July 2016

This paper obtains the probability and the expectation of the length of the busy and idle periods in a discrete-time service system by means of two-component Markov chains and their first passage times. The M/G/1 model is discussed as a special case.
On the distribution of records in a finite sequence of observations, with an application to a road traffic problem
Authors: Haghighi-Talab Dariush , Wright Christopher
Published: July 2016

Probability distributions relating to the number and positions of lower records in a finite sequence of observations are obtained by methods involving the permutation of ranks. Some new results, and results of earlier authors, are expressed in a form thought to be useful for direct practical applications.

Expressions are also given for the distribution of the length of a ‘record run’, which consists of the observations following and including a given record either up to the next record, or, if a further record does not occur, up to the end of the sequence of observations. This quantity, whose distribution is closely related to that of the inter-record time, has a direct and simple application to road traffic leaving a signal which has been confirmed by experimental observation.
Order preserving measures of information
Authors: Shiva S. G. S. , Ahmed N. U. , Georganas N. D.
Published: July 2016

If the information content of a complete finite probability scheme is greater than that of another such scheme in one measure of information, it seems reasonable to expect that this relation remains true in any other valid measure. In this paper Shannon and Rényi measures are discussed, regarding this aspect.
Shot noise generated by a semi-Markov process
Authors: Smith Woollcott
Published: July 2016

In this note a model for shot noise generated by a semi-Markov process is developed. The moments of the shot noise process are found, and some applications of this model are briefly indicated.
Brain connectome modularity in weight-restored anorexia nervosa and body dysmorphic disorder
Authors: Zhang A. , Leow A. , Zhan L. , GadElkarim J. , Moody T. , Khalsa S. , Strober M. , Feusner J. D.
Published: July 2016

Background

Anorexia nervosa (AN) and body dysmorphic disorder (BDD) frequently co-occur, and have several overlapping phenomenological features. Little is known about their shared neurobiology. The aim of the study was to compare modular organization of brain structural connectivity.

Method

We acquired diffusion-weighted magnetic resonance imaging data on unmedicated individuals with BDD (n= 29), weight-restored AN (n= 24) and healthy controls (HC) (n= 31). We constructed connectivity matrices using whole-brain white matter tractography, and compared modular structures across groups.

Results

AN showed abnormal modularity involving frontal, basal ganglia and posterior cingulate nodes. There was a trend in BDD for similar abnormalities, but no significant differences compared with AN. In AN, poor insight correlated with longer path length in right caudal anterior cingulate and right posterior cingulate.

Conclusions

Abnormal network organization patterns in AN, partially shared with BDD, may have implications for understanding integration between reward and habit/ritual formation, as well as conflict monitoring/error detection.
Aerodynamics I
Authors: Wilde M. G.
Published: July 2016

In a paper delivered before the Society in March 1960, Morgan concluded that a Mach number of about 2.0 may prove a natural “fit” for the first generation of long-range supersonic transports. Sub-sequently, at the second Congress of I.C.A.S., Kuchemann developed the theme of fitting an aircraft to a particular duty and concluded that the slender wing provides a natural basis for the layout of the supersonic transport. It is convenient to accept these two papers as a starting point for a more detailed examination of the aircraft, since, taken together, they can be taken as fixing some of the major variables—range, speed and general layout.
Materials—Metallic and Non-Metallic
Authors: Megson N. J. L.
Published: July 2016

With increasing speeds of aircraft, problems arise over materials of construction, partly through kinetic heating effects which cause temperature rises and partly through rain erosion effects. Additionally, account has to be taken of a required life of 30,000 hours which is much longer than that over which most materials are normally evaluated.

For speeds of Mach 2.2, the maximum temperature attained will be of the order of 130°C, while for Mach 2.7 the corresponding temperature will be 200°C or higher. For the lower speed, it is probable that aluminium alloys will be satisfactory, although it must be emphasised that no information is yet available on the long-term behaviour of materials at the elevated temperatures likely to be experienced. Test programmes are in hand, but these will necessarily take considerable time for their completion. For speeds of Mach 2.7 or above, steel or titanium alloys will be required, but here again the necessary evaluation for long periods at high temperature has yet to be completed.
Cockpit Design and Management
Authors: Ormonroyd Captain F.
Published: July 2016

The rate of error in the performance of any task increases rapidly after a certain degree of complexity or rate of operation is exceeded. As aircraft speeds increase, therefore, the safety and efficiency of the operation will depend largely on the extent to which the job of the crew can be simplified and on the work-load being kept within tolerable limits. In recent years the problem has been tackled by the addition of specialist crew members and by the use of automatic and semi-automatic equipment. Distribution of the total load over an increased number of people is no longer a satisfactory solution, however, since it imposes an additional burden on the Captain in his capacity as overall monitor and the time available for this vital task is all too little. While the pilot by tradition tends to reserve judgment on automatic devices generally, where a high standard of reliability is proved the system will receive acceptance in due course and there is little doubt that it is in this field where the greatest contribution to operating efficiency will be found.
Thermal Bending of a Tri-Metal Strip
Authors: Vasudevan M. , Johnson W.
Published: July 2016

The General Elastic Analysis of the bending of a bi-metallic strip subjected to uniform heating has been made by Timoshenko. In this note we extend the theory to that of a tri-metal strip. General formulae for curvature and bending stresses have been developed. These formulae reduce to simple expressions if a particular choice of material constants and thicknesses is made. These latter formulae indicate that the curvature can be independent of the coefficient of linear expansion of the middle material and that it is possible to have the stresses at the inter-surfaces equal if a proper choice of the ratios of the coefficients of linear expansion of the three materials is made.
The Royal Aeronautical Society The First Fifty Years
Authors: Laurence Pritchard J.
Published: July 2016

Thomas Moy's declaration at the 1873 Meeting of the Society, that he and his partner Shill were constructing a large-scale model of a flying machine, roused considerable interest. Twelve months later, at the Meeting held on 15th May 1874, he said:

“We have not got on so fast as we had hoped. Various difficulties had arisen which had to be mastered one by one as they cropped up. As their machine was only a working model, the aeroplane required to be made of some light material. Some time ago I was trying to get thin steel rolled and corrugated but I was unable to get anything suitable. I next tried a fine kind of brown holland for our wing sails, but found this would not take the curves kindly, but got into wrinkles. I am now making use of thin pine lathes nicely planed and fitted so as to form a sectional screw surface, and I think they would answer very well, and would form the nearest approach to a perfect screw that can be obtained.”
The Production of Peaked Velocity Profiles
Authors: Morgan P. G. , Saunders A.
Published: July 2016

In many internal flow problems, the velocity profile of the flow in a duct of a given cross section is of major importance. In combustion chamber flow, for example, the entry velocity profile is a critical factor in determining the relative amounts of primary and secondary combustion air. Further, in the flow in an axial compressor, the peaked velocity profile between the root and the tip of the rotor blades has a marked effect upon the design of the blading. Recent work by Zanker has shown the effect of variation in velocity profile upon the accuracy of orifice-plate flowmeters.
Recent Developments in Photoelastic Coating Techniques
Authors: Holister G. S.
Published: July 2016

The original concept of measuring strains directly from the surface of a structure by coating it with a birefringent material is credited to Mesnager (France, 1930), who was unable to obtain practical results at that time because of the lack of suitably sensitive photo-elastic materials. Subsequent attempts were made by Mabboux (France) in 1932, Oppel (Germany) in 1936 and K. O. Scott (England) in 1949. In March 1953, Col. H. T. Jessop published in the JOURNAL of the Royal Aeronautical Society the results of some research into the feasibility of bonding modern plastics on to structures.
Liquid Atomisation
Authors: Fraser R. P.
Published: July 2016

The process of atomisation is of primary importance in several branches of engineering, such as in the combustion of liquid fuels, in the chemical industry, in operations involving drying, evaporation, absorption, and so on, in fire-fighting and the production and dissipation of fogs and in agriculture.

In agriculture, the spraying of small drops is employed in the dissemination of insecticides, herbicides, etc., for the purpose of crop protection, and the spraying of large drops is used for overhead irrigation.

Since the advent of the atomiser, a hundred years ago, the engineer has been in advance of theory in his practice of atomisation. For lack of fundamental data he has had to rely upon laborious hit and miss experiments to obtain a design suitable to a particular requirement. Thus the atomiser has been a fruitful avenue for the inventor. Its small size and apparent simplicity has, however, deceived many into the belief that the problem is simple. Research over the last thirty years has proved this to be anything but true, and even now our knowledge is still extremely limited.
The Pressure Registered by a Very Small Static Hole
Authors: Jackson J. D.
Published: July 2016

Static pressure in a moving fluid is usually measured by means of a static hole either in a probe or on the wall of a duct. Such a hole creates a disturbance in the flow and thus has some error associated with it. The determination of the magnitude of this error has been attempted by several investigators and the procedure adopted in each case has been as follows :

The pressure in a region of sensibly constant static pressure was registered using holes of various diameter and a curve of pressure versus hole size plotted. The true static pressure was then obtained by extrapolating this curve to zero hole size, and the errors for the various holes were found. This procedure involves the assumption that, as the hole size tends to zero, the pressure registered tends to the true value. It is usually argued that this must be so because the disturbance caused by the static hole is progressively reduced as the hole size is reduced. Obviously, the validity, or otherwise, of the argument is of fundamental importance in the estimation of static hole error, and a somewhat more rigorous justification of the use of the extrapolation procedure is attempted in what follows.
The Production of Peak Velocity Profiles
Authors: Roberts D. C.
Published: July 2016

In the technical note in the August JOURNAL by Morgan and Saunders the values given in the last column of Table I on p. 572 are actually the square roots of the open area ratio.
Part I: Instrument Flight Developments
Authors: Mitchell Harry W.
Published: July 2016

Helicopters have reached a state of mechanical reliability today comparable to that of the aeroplane. Rotary wing aircraft have been severely limited performancewise, however, by the fixed wing type of instrumentation commonly used. It has been impossible to operate helicopters throughout their complete flight regime in their normal operational areas during instrument flight conditions. This paper defines the problem, the approach taken by Bell Helicopter Company, the flight test programmes and results, and the future for helicopter instrument flight operations in both populated and remote areas using information sensors and displays designed expressly for VTOL machines.
Notes on the Costs of the United States Space Programme
Authors: Rothrock Addison M.
Published: July 2016

The purpose of this paper is to discuss certain aspects of the costs of the United States Space Programme. Attention will be concentrated on the work of the National Aeronautics and Space Administration (NASA). The United States Aeronautics and Space Act of 1958 charges the NASA with the responsibility of “exercising control over aeronautical and space activities sponsored by the United States, except that activities peculiar to or primarily associated with …. defense of the United States …. shall be the responsibility of …. the Department of Defense.”
Recoverable Air-Breathing Boosters for Space Vehicles
Authors: Lane R. J.
Published: July 2016

In September 1957 the first small satellite was placed into orbit around the earth by the U.S.S.R. Since that time a very competitive situation has developed between the U.S.S.R. and the U.S.A. Each side has presumably used its military ballistic missiles, together with hurriedly-developed second and third stages. We are now reaching a situation in the West where more carefully prepared and optimised rocket stages are being used, with the basic I.C.B.M. and I.R.B.M. first stages. The result of this is to put larger payloads into orbit for a given launch weight. Recently, cost figures for the past^ present and future satellite launchers have been quoted.
Transient Analysis of Forced Vibrations of Complex Structural-Mechanical Systems
Authors: Chan S. P. , Cox H. L. , Benfield W. A.
Published: July 2016

This paper presents a numerical method, derived directly from the basic differential equations of motion and expressed in the form of recurrence-matrix of finite differences, that can be generally applied to all multi-degree-of-freedom structures subjected to dynamic forces or forced displacements on any masses at any instants of time. The movements of the system may be described by any form of generalised co-ordinates.
Twenty-Five Years More of Theoretical and Experimental Research in Fluid Mechanics
Authors: Riabouchinsky D.
Published: July 2016

In the spring of 1914, in view of the tenth anniversary of the Aerodynamic Institute at Koutchino, near Moscow, I published a booklet in which I gave a survey of the Institute's activities since its foundation and concluded it as follows: “The problem of aerodynamical flying is solved, but, after the conquest of air space, another conquest, more difficult and of higher import, is offered to the ambition of man— the conquest of interplanetary spaces. “The brilliant progress of science gives hope that, in a more or less distant future, this problem will be solved in its turn through the patient and co-ordinated efforts of searchers impassioned by the greatness of this idea.

“The brilliant progress of science gives hope that, in a more or less distant future, this problem will be solved in its turn through the patient and co-ordinated efforts of searchers impassioned by the greatness of this idea.
High Performance Turbine Engines
Authors: Weir R. H.
Published: July 2016

“Thunder driven, they clanged ……'thwart a heaven Pldshy with flying lightnings round the spurn o’ their feet”

Francis Thompson(1859–1907)

If it implied anything in the context of high performance turbine engines, the mutilated quotation from “The Hound of Heaven” might conjure up a vision of afterburning turbojets, or turbo-ramjets, propelling second or third generation supersonic transports at very great heights. This would be a misleading picture, and it will probably emerge that the quotation has little to do with what follows, as this is largely concerned with subsonic flight—on which I believe the economic future of aviation will depend for many years.
Bloodhound Missile Evaluation
Authors: Biggs A. G. , Cawthorne A. R.
Published: July 2016

The main objectives of Missile Evaluation Trials are a complete evaluation of the operational performance of the missile tested, a comprehensive assessment of the practical implications of regular operation of the weapon system from the user's point of view, and the feedback of scientific information to assist in future designs. This means that the trials must be planned to provide data on the following aspects: —

(a) Scientific evaluation, i.e. determination of performance in the various conditions which will arise in operational use.

(b) Technical evaluation, i.e. assessment of the detail design, workmanship, engineering and reliability and its influence on operational performance.

(c) User evaluation, i.e. a practical critical examination of (and evolution of) handling and servicing procedures, personnel training requirements, installation requirements, logistics, and the numerous organisational steps necessary for the introduction of a new weapon into service.
Power for Supersonic Flight
Authors: Hooker S. G. , Garnier Michel
Published: July 2016

The engines for the Concorde supersonic transport are being developed jointly by SNECMA and Bristol Siddeley Engines Ltd. The basic engine is derived from the Olympus engine and the responsibility for this part of the development will rest with Bristol Siddeley Engines Ltd., but the jet pipe, propelling nozzle, thrust reverser and noise suppressor will be the responsibility of SNECMA.
The Transonic Flow Past Two-Dimensional Aerofoils
Authors: Holder D. W.
Published: July 2016

It is both an honour and a responsibility to deliver a lecture commemorating the names of two scientists who have made unique contributions to fluid dynamics, and whose names perhaps above all others will remain immortal in our subject. The range of topics that would be suitable for such a lecture is very wide, because there is scarcely a branch of fluid dynamics in which the work of Reynolds and Prandtl does not continue to play a significant part. In a lecture of current interest there is, therefore, no problem of relating the subject matter to the names to be commemorated; the influence of Reynolds and Prandtl remains as strong as when they were alive, and many of the problems that engaged their attention are even today only partially solved. The lecturer must, therefore, use other considerations for guidance in the selection of his subject from the limited range on which he is qualified to speak, for few could hope to work over the wide field covered by Reynolds and Prandtl. He must if possible select a, topic in which major contributions have originated from Germany and the United Kingdom, on which research is actively in progress in both countries, and for which progress has relied on the combination of theoretical and experimental work to provide acceptable simplifying assumptions that characterised many of the investigations of Reynolds and Prandtl.
The Biology of Tsetse Flies in Relation to Control Methods
Authors: Hadaway A. B.
Published: July 2016

Tsetse flies are generally classed as insects of medical and veterinary importance, but qualify for consideration by this group by virtue of their indirect influence on agricultural development in Africa and their possible control by the application of insecticides from aircraft.

Tsetse flies are confined to the African continent and a few small off-shore islands. They are widely distributed between 14°N and 29°S wherever the environment is suitable; and are absent from N. Africa, the Sahara, the Red Sea Zone and the Somalias, and the highlands of Ethiopia, and from the Union of South Africa, except Zululand.
Review of Problems in Application of Supersonic Combustion
Authors: Ferri Antonio
Published: July 2016

The problem of air-breathing engines capable of flying at very high Mach numbers is described briefly. Possible performance of supersonic combustion ramjets is outlined briefly and the supersonic combustion process is described. Two mechanisms of combustion are outlined: one is supersonic combustion controlled by convection process, and the second is controlled by diffusion. The parameters related to the combustion process are discussed in detail. Data and analyses of reaction rates and mixing phenomena are represented; the flame mechanism is discussed, and experimental results are presented.
Flight Simulation for Research
Authors: Perry D. H. , Naish J. M.
Published: July 2016

Some of the uses of ground based flight simulation as a research tool to aid the design of new aircraft and their equipment are described. The function of the simulator is to provide a method for investigating humon flying tasks in the laboratory, so that the relationship between the pilot's capabilities and the equipment's characteristics can be systematically studied. The paper is presented in two parts describing recent work on two research simulators at the RAE.

Part I deals with the use of simulation for studying aircraft stability and control characteristics. The equipment used at RAE for this work is described, with particular emphasis on methods of presenting to the pilot a simulated view of the outside world, and for reproducing some of the motion cues which he experiences in flight. Experimental evidence of the importance of these simulation cues when making aircraft control assessments is also presented. Several examples of simulation studies into the control of conventional and VTOL aircraft are given, to illustrate the type of research problems in this field which may be tackled and the techniques involved in solving them.
A Method of Calculating Maximum Permissible Take-off Weights using a Digital Computer
Authors: Wilson A. , Graham B. A.
Published: July 2016

The Vast amount of knowledge on the operation of long-haul jet aircraft will inevitably pass on to the short-haul jet; but it is felt that, in the take-off régime, further study must be done. A short-haul jet will probably average 8 to 12 take-offs a day—considerably more than a long-haul jet— and many of these take-offs will involve relatively minor airfields with short runways. In addition, on a world-wide basis, there is an increasing awareness of obstacles under the flight path. Roberts of North Central Airlines and Cooke of United Airlines have emphasised this aspect from the operator's point of view. As an example, calculation of a single point involving an obstacle limited take-off weight would take a pilot at least an hour. For efficient short-haul operation, this wastage of time is prohibitive.
Transient Response of Wire Resistance Thermometers
Authors: Quarmby Alan
Published: July 2016

In using resistance wire thermometers for measuring transient gas temperatures, such as internal combustion engine exhausts, errors occur due to the thermal inertia of the wire and conduction along it and the supports.

Benson and Brundrett analysed the situation by solving the heat transfer equation for a particular case where the gas temperature was assumed to vary sinusoidally with time. An estimate of the maximum error for particular sizes of wire could be obtained. Conduction in the supports was neglected.
Future Relationships Between Air and Ground Transport
Authors: Cooper J. R.
Published: July 2016

“I think everyone would agree that high flight speed, although it is the spectacular signature of aviation, is not a significant measure of progress. If any one of the eight purpose factors is to be regarded as the specific goal of aviation or the dominant yardstick of its progress, I think that it is to transport as many people as possible, i.e. to create a big volume of aviation, in passenger-miles.”

Bo K. O. Lundberg

We are living at a time of transition in civil aviation, between subsonic and supersonic flight. Subsonic flight has no connection with ground transport and supersonic flight, as now envisaged has no connection either. It is thus rather necessary to explain the title of this paper which would otherwise be irrelevant.
Technical notes
Authors: Arcyris J. H.
Published: July 2016

A decade has elapsed since triangular elements under constant strain and stress were independently introduced within the matrix Displacement Method by the Turner group at Boeing and the Aeronautical Structures Department at Imperial College. They proved a considerable success in the practical analysis of complex membrane shapes as occur in modern aircraft wings. However, the original formulation based on a local cartesian system of axes and the classical concept of stress and strain inevitably leads to an unsymmetrical and aesthetically (as well as computationally) unfavourable expression for the stiffness matrix k. Moreover, the method was restricted to isotropic media. The necessity of extending the theory to finite displacements ultimately showed the inadequacy of the past approach and guided the writer to the creation of new concepts, e.g. the natural stiffness of an element. This natural stiffness, which ignores the rigid body motions and is hence of dimensions (3 X 3) for a triangle with three nodal points, relates in a concise manner the nodal force components parallel to the sides and the elongations of the sides themselves. A powerful tool in its derivation and further development was a new definition of stress and strain vectors which excludes shearing contributions and only works with direct components parallel to the sides. The idea has also been extended to tetrahedra and many standard elements which are incorporated as a basic feature in the structural language ASKA (Automatic System for Kinematic Analysis) developed at ISD by the Applied Programming Group under Dr. H. Kamel. These fundamental ideas were emphasised in the author's recent lecture to the Society.
Numerical Solutions of the Viscous Flow Equations for a Class of Closed Flows
Authors: Mills Ronald D.
Published: July 2016

The Navier-Stokes equations are solved iteratively on a small digital computer for the class of flows generated within a rectangular “cavity” by a surface passing over its open end. Solutions are presented for depth/breadth ratios ƛ=0.5 (shallow), 10 (square), 20 (deep) and Reynolds number 100. Flow photographs ore obtained which largely confirm the predicted flows. The theoretical velocity profiles and pressure distributions through the centre of the vortex in the square cavity are calculated.

In an appendix an improved finite difference formula is given for the vorticity generated at a moving boundary.

Since Thorn began his pioneering work some thirty-five years ago the number of numerical solutions which have been obtained for the equations of incompressible viscous fluid motion remains small (see bibliographies of Thom and Apelt, Fromm). The known solutions are principally for steady streaming flows, although two methods have now been used with success for non-steady flows (Payne jets and Fromm flow past obstacles). By contrast this paper is concerned with the class of closed flows generated in a rectangular region of varying depth/breadth ratio by a surface passing over an open end. This problem has been considered for a number of reasons.
An Airline View
Authors: Whitby R. H.
Published: July 2016

Cheap and short range is a contradiction in terms if one is talking about cost per mile. Fig. 1 is from “American Aviation” for December 1964; it shows cost and revenue of US domestic operations in 1964. Over the average trip of 680 miles there was a margin of about 10 per cent of revenue over cost. At 200 miles, however, there was a deficit of 30 per cent. If the average 10 per cent margin were to be maintained at present fare levels, cost would have to be reduced by 35 per cent—no mean task.

The reasons for relatively high costs on short sectors are well known. Block speed is low; frequent stops consume much time on the ground and so utilisation of aircraft and crews is low; the outcome is that the output in seat miles per annum, and hence the revenue earning ability, is reduced. Landing fees and Station costs are spread over a smaller revenue.