bluuebunny/crossref_metadata_2025_split huggingface dataset:
A stochastic process whose successive intervals between events form a first order Markov chain — I
Authors: Lampard D. G. 
Published: July 2016

In this paper we discuss a counter system whose output is a stochastic point process such that the time intervals between pairs of successive events form a first order Markov chain. Such processes may be regarded as next, in order of complexity, in a hierarchy of stochastic point processes, to “renewal” processes, which latter have been studied extensively. The main virtue of the particular system which is studied here is that virtually all its important statistical properties can be obtained in closed form and that it is physically realizable as an electronic device. As such it forms the basis for a laboratory generator whose output may be used for experimental work involving processes of this kind.
Such statistical properties as the one and two-dimensional probability densities for the time intervals are considered in both the stationary and nonstationary state and also discussed are corresponding properties of the successive numbers arising in the stores of the counter system. In particular it is shown that the degree of coupling between successive time intervals may be adjusted in practice without altering the one dimensional probability density for the interval lengths. It is pointed out that operation of the counter system may also be regarded as a problem in queueing theory involving one server alternately serving two queues. A generalization of the counter system, whose inputs are normally a pair of statistically independent Poisson processes, to the case where one of the inputs is a renewal process is considered and leads to some interesting functional equations.
On extreme stable laws and some applications
Authors: Eaton Morris L. , Morris Carl , Rubin Herman 
Published: July 2016

Summary
It is shown that the extreme stable laws have one-sided moment generating functions with interesting mathematical forms. The fact that one of these forms, zcz
, is a moment generating function is used to establish two interesting statistical results; first, that rr
is a moment sequence for a density with decreasing failure rate, and secondly, that the likelihood ratio test for testing a simple null hypothesis in a multinomial distribution is admissible and Bayes.
Band-limited spectral estimation of autoregressive-moving-average processes
Authors: Thomson P. J. 
Published: July 2016

Consider an autoregressive-moving-average process of given order where it is known that a number of moving-average roots are of unit modulus. Such a situation might arise, for example, when a time series has been differenced to induce stationarity by removing a non-stationary polynomial or seasonal trend. A band-limited spectral estimation procedure is proposed for estimating the coefficients of such a process and the asymptotic properties of the estimators investigated. The asymptotic theory is illustrated with reference to simulated and real data. A preliminary investigation of the use of Akaike's AIC criterion and this procedure to determine the number of roots of unit modulus (in the case where this is unknown) is also carried out by means of simulation.
The proposed band-limited spectral estimation procedure can also be used to take account of other possible effects met in practice. These include, for example, the band-limited response of a recording device or trend-contaminated low-frequency components.
Record values and inter-record times
Authors: Shorrock R. W. 
Published: July 2016

First, asymptotic results for inter-record times when the CDF of the underlying IID process is not necessarily continuous are obtained, by a stochastic order argument, from known results for the continuous case. Then the asymptotic behaviour of the bivariate process of upper-record values and inter-record times is studied. Finally, assuming continuity of the underlying CDF, we derive the law of the process of total times spent in sets of states, viewing upper record values as states and inter-record times as times spent in a state, the process so viewed being a discrete time continuous state Markov jump process.
The possible relevance of this result to single lane road traffic flow is indicated.
On the expected range and expected adjusted range of partial sums of exchangeable random variables
Authors: Boes D. C. , Cruz J.D. Salas-La 
Published: July 2016

Studies of storage capacity of reservoirs, under the assumption of infinite storage, lead to the problem of finding the distribution of the range or adjusted range of partial sums of random variables.
In this paper, formulas for the expected values of the range and adjusted range of partial sums of exchangeable random variables are presented. Such formulas are based on an elegant result given in Spitzer (1956). Some consequences of the aforementioned formulas are discussed.
Cortical salience network activation precedes the development of delusion severity
Authors: Raij T. T. , Mäntylä T. , Mantere O. , Kieseppä T. , Suvisaari J. 
Published: July 2016

BackgroundDelusion is the most characteristic symptom of psychosis. While researchers suggested an association between changes of the cortical salience network (CSN) and delusion, whether these CSN findings are a cause or a consequence of delusion remains unknown.MethodTo assess the effect of CSN functioning to forthcoming changes in delusion scores, we measured brain activation with 3-T functional magnetic resonance imaging in two independent samples of first-episode psychosis patients (total of 27 patients and 23 healthy controls). During scanning, the patients evaluated statements about whether an individual's psychosis-related experiences should be described as a mental illness, and control statements that were also evaluated by healthy controls. Symptoms were assessed at the baseline and at 2 months follow-up with Brief Psychiatric Rating Scale.ResultsBoth tasks activated the CSN in comparison with rest. Activation of CSN (‘illness evaluation v. control task’ contrast) in patients positively correlated with worsening of or less improvement in delusions at the 2-month follow-up assessment. This finding was independent of delusion and clinical insight scores at the baseline evaluation.ConclusionsOur findings link symptom-evaluation-related CSN functioning to severity of delusion and, importantly, add a new layer of evidence for the contribution of CSN functioning to the longitudinal course of delusions.
An Iteration Process for the Solution of the Prandtl-Meyer Expansion
Authors: Collar A. R. 
Published: July 2016

In the Journal of the Royal Aeronautical Society, November 1959, the writer described an iteration process for the solution of the equations for plane oblique shock waves. Iteration methods avoid the difficulty of reading a solution from a chart; or, given a chart, provide a means of checking such a reading and, usually, of improving the accuracy to any desired degree.As with plane oblique shocks, it is usual to use a chart to obtain the solution of a problem involving a Prandtl-Meyer expansion fan. The present note proposes an iteration process to avoid the use of a Prandtl-Meyer chart; or, given such a chart, offers the possibility of improvement in the accuracy of the solution obtained by reading from it, the limit being set by the accuracy of the trigonometric tables used.
The Era of the Autogiro
Authors: Bennett J. A. J. 
Published: July 2016

The First Cierva Memorial Lecture was given in the Lecture Theatre of the Society on 16th February 1961 with Dr. E. S. Moult, C.B.E., B.Sc., F.R.Ae.S., M.I.Mech.E., President of the Society, in the Chair. Introducing the lecturer, Dr. Moult said that, beginning in 1948, through the generosity of Wing Commander Graham Douglas, the Helicopter Association of Great Britain awarded a prize annually in commemoration of the great pioneer work of Juan de la Cierva in the field of rotary wing flight. When the Helicopter Association merged with the Royal Aeronautical Society in 1960 it was decided to institute a Cierva Memorial Lecture as a main event in the yearly calendar of the newly-formed Rotorcraft Section of the Society.This was the first lecture of what he was sure would be an outstanding series and they were honoured by having with them for the occasion Dr. Carlos de la Cierva, son of the great pioneer. Professor Bennett had spent much of his working life associated with rotary wing aircraft and had been closely associated with Senor de la Cierva. He had been with the Cierva Autogiro Company for about 10 years, and for some seven years was head of the Helicopter Branch of Fairey Aviation; in America he was for a period a member of the British Air Commission and later, was Chief of Research of Hiller Aircraft. He was now Deputy Principal and Head of the Department of Aerodynamics at the College of Aeronautics.
Electronic Displays for Rotary Wing Aircraft
Authors: Bell J. C. G. 
Published: July 2016

Since the first decade of this century aircraft have been equipped with instrumentation to show attitude and direction and to assist navigation and to monitor the performance of the prime mover, if any. Their sophistication has grown with the aircraft but while aerodynamic shapes have apparently simplified over the years, instrument configuration has tended towards complex arrays of electro-mechanical analogues.Fundamentally, instruments are means of data communication between the systems of the aircraft and the human crew, the latter functioning either as part of a closed loop or, alternatively as the monitor of an automatic control. When functioning as a monitor it must always be considered that the human operator may have to revert with minimum delay and disturbance to the first role, namely that of an active part of the control system. In extreme cases of multiplex automatic systems, such as those intended for Auto-land, there may be a case for denying revertion on the grounds that channel redundancy will reduce the failure rate to an acceptable value, added to the fact that the pilot might in fact be incapable of improving the situation after a certain point in time and space had been reached.
Calibration of a Cruciform Wind Vane Configuration at Subsonic and Supersonic Speeds
Authors: Dee F. W. , Mabey D. G. 
Published: July 2016

Incidence and sideslip must be measured accurately in aircraft performance and stability tests. A convenient method is to install wind vanes on a nose boom. When only one sideslip and one incidence vane are fitted, mutual interference occurs, and the vanes do not indicate the true flow direction. This interference can be 0·5° at 0° incidence at subsonic and supersonic speeds. Thus a symmetric configuration of vanes is essential for accurate measurements of incidence and sideslip.A cruciform arrangement of four wind vanes was fitted around the nose boom Pitot head of the Fairey Delta 2 supersonic research aircraft. The effect of the Pitot boom on the vane sensitivity was determined by a calibration of the aircraft vanes on a duplicate Pitot-static head in the R.A.E. Bedford 3 ft wind tunnel.The effects of the fuselage and the wing upwash are only present at subsonic speeds and can be estimated.
Gas Turbine Development— Thirteen and a Half Years in Commercial Aircraft
Authors: Lovesey A. C. 
Published: July 2016

It is now 13½ years since turbine engines first began airline service with the Dart in the Viscount. It is 11½ years since the de Havilland Ghost jet engine went into airline operation with the Comet. Today there are some 2468 gas-turbined aircraft operating (or on order) on commercial service and it would be interesting to look back over those 13½ years and ask the question, “How do we apply this experience towards meeting the requirements of the future?”I can only speak with first hand knowledge of that part of the operation associated with engines produced by my Company. However, this is a sizeable sample covering over 50 per cent of the “Free-World’s” civil aircraft including propeller turbines, jet and by-pass engines.
The Physical Principles of Hovercraft
Authors: Mair W. A. 
Published: July 2016

Any vehicle that is required to travel at high speed over the surface of the earth (either land or water) should have(a) Low drag and(b) Some form of spring suspension.Anyone who doubts the need for the second of these, for travel over water, should consider the accelerations involved in following the surface of the sea at high speed and observe the behaviour of a high-speed motor boat on rough water.
The Determination of an Upper Bound of the Lowest Natural Frequency of a Star Shaped Membrane
Authors: Laura Patricio A. 
Published: July 2016

Let Г be a closed curve in the z-plane with p-axis of symmetry. The mapping functionmaps in general the interior of the unit circle |ξ| < 1 on to the interior of Г such that ξ=0 is transformed into z=0.
Thrust Throttling of Large Liquid Propellant Rocket Engines
Authors: Smith I. E. 
Published: July 2016

SummaryThe paper concerns rocket engines of the type currently employed in ballistic missiles and satellite booster vehicles, outlining some advantages to be gained from a reduction in thrust towards the end of the burning period. Several methods of throttling a rocket engine are then examined.Low frequency combustion instability which can arise when an engine is operated below its normal thrust level is considered in some detail, including the effect of such instability on engine performance. Means of ensuring stable operation both in the main thrust chamber and the turbine gas generator are described and compared.The mechanism of heat transfer to the main injector has been studied and the modifications to the injection pattern necessary to maintain this at a safe level are described. Also, changes in the overall heat transfer rate to the thrust chamber walls are discussed with special reference to the formation of an insulating layer which occurs with carbon-bearing propellants.The discrepancy between the inlet heads of the propellants at high vehicle accelerations is noted and the relative effect of this on engine operating conditions for the throttled and unthrottled cases described.Finally, the effect of pressure change on the thrust chamber performance is considered with reference to studies made on the Rolls-Royce RZ.2 engine.
Shear Buckling of Simply-Supported Rectangular Elastic Plate
Authors: Fang Bertrand T. 
Published: July 2016

The equation for the buckling of a homogeneous
elastic plate is well known
For a simply-supported rectangular plate without shear (Nxy=0), the critical loads are usually found by substituting
into equation (1) and determining the loads at which nontrivial solutions exist. In the presence of shear, however, the difficulty with the above approach is that the shear term would involve cosines instead of sines.
Investigation of the Possibilities of Rotating Cylinders as an Auxiliary Lift Device
Authors: Chacksfield J. E. 
Published: July 2016

The following is an attempt to show the gains and losses achieved when a rotating cylinder is used to create additional lift during the take-off and landing of an aircraft.A hundred-year old theory lies behind the results (the “Magnus” effect), which, up to the present day has not been put to practical use in flight for increasing CL. Many proposals and tentative designs have been studied at major Research Establishments, notably A.V.A. Gottingen and the RAE but experimental studies on aircraft converted for the purpose have yet to be made.Limited test results show that the CL on a rotating cylinder can be as great as 15 providing that sufficient care is taken to approach infinite aspect ratio by means of end-plates on a high aspect ratio cylinder. The one great disadvantage with the cylinder is the high drag coefficients produced. However, there seems no reason why a fairing should not be placed in the wake to reduce the drag to that corresponding to a blunt-nosed thick aerofoil section.
Jet Separation in Conical Nozzles
Authors: Sunley H. L. G. , Ferriman V. N. 
Published: July 2016

SummaryThe separation or breakaway of over-expanded gas from a nozzle wall plays an important role in the estimation of the thrust from a rocket engine when run at altitudes considerably less than the design. A number of reports have been written on the subject but the agreement of test results has not appeared to be good.In an effort to clarify the position, the Rocket Department of Bristol Siddeley Engines Ltd. has carried out tests on experimental combustion chambers having static pressure tappings in the nozzle divergent section. These tests have shown that, contrary to some previous suggestions, the pressure at which the gas separates is neither constant nor independent of the nozzle length. The paper, which includes results from other workers, divides the field into separation adjacent to the nozzle exit and also at positions where the area ratio is less than 80 per cent of the exit area ratio.For the most part, consideration is given to conical nozzles having divergence half angles of 15° to 17°, but comment is made on the effects of divergence and other variables. A tentative suggestion as to the mechanism of separation is also made.Finally, the effect of separation on the sea-level thrust of a nozzle designed for high altitude Is shown.
Natural Vibration with Damping Proportional to a Power of the Velocity
Authors: Richardson P. D. 
Published: July 2016

SummaryIn a recent note in the Journal, Morley and Bryce discuss the problem of natural vibration with a damping force proportional to a power of the velocity. They address themselves particularly to the problem of interpreting experimental measurements, and mention an application of the study of an elasticity in metals. They were apparently unaware of previous analytic studies of this problem, and their analysis is somewhat inaccurate in indicating that the full-cycle logarithmic decrement rather than the half-cycle logarithmic decrement characterises the damping.It is intended here to outline the previous analytic studies, to present the essential results, including those which can be directly employed in the interpretation of amplitude measurements, and to mention typical applications.
A Trial Flight on HMR33 1919
Authors: Potts R. W. 
Published: July 2016

Towards the end of the days of the Royal Naval Service, 1919, I was posted to Barlow, where HMR33 was under construction. Barlow was in Yorkshire, near Selby. I knew where Selby was, as a Sunderland man. Selby was “way down south, near York”.Barlow must have been the best RNAS station to be posted to, just a small group of officers and ratings, the potential crew of the wonderful new airship HMR33.When we arrived, the “ship” was about half to three-quarters built, and, among other things, our duties were to make ourselves useful and get to know the construction of the whole airship. We took a great interest in our official duties, but some, I believe, were also interested in the girls working on the ship, which, after all, added a bit of romance, especially to an RNAS station.
A Three-Component, Strain-Gauged Sting Balance for Use in Small Low-Speed Wind Tunnels
Authors: Marsden J. A. C. 
Published: July 2016

In preparation for the wind tunnel testing of a series of aerodynamic research models a strain-gauged balance was sought which could be successfully made without the use of sophisticated tools. The principal requirements which influenced the design of the balance were:(a)It must enable lift, drag and pitching moment to be measured.(b)Deformation of the balance under the aerodynamic loads to be small.(c)Use of only basic workshop tools.(d)Short manufacturing time.Further, the models were to be sting mounted at one end of the balance with their span vertical. The other end of the balance was to be rigidly fixed to a supporting stand which would be mounted on the wind tunnel turntable to permit incidence variation (Fig. 5).
Developments in Range Instrumentation
Authors: Harrison J. E. A. 
Published: July 2016

SummaryDevelopments in Range instrumentation for trajectory measurement over the past ten years are reviewed, and some possible future developments discussed. Instrumentation systems considered include kine-theodolites, tracking radars, multi-station Doppler systems and interferometers. Some common sources of error are discussed; it is shown that atmospheric retraction variations may be the limiting factor on the accuracy of modern trajectory measuring systems. The most important problems during the next five years will arise from requirements for very low level weapon systems, high precision tracking of small targets with fast response characteristics and long range high precision tracking of space vehicles. Developments to meet these requirements will lead to further requirements for completely automatic data processing for the high data rates needed. It seems probable that fewer completely new instrumentation systems will be developed during the next five years, more attention being given to reducing the size of airborne transponders and other equipment and increasing the reliability and accuracy of existing equipment. Systems using a common carrier lor telemetry signals and tracking may appear.Considerable work on isolating sources of error in existing systems and reducing them is going on and will continue. This will be combined with more advanced post-flight analysis techniques during the next five years.
The Acquisition and Processing of Data from the Ariel 1 and Ariel 2 Satellites
Authors: Dorling E. B. 
Published: July 2016

SummaryThe first two US/UK co-operative satellites, Ariel 1 and Ariel 2, were put into orbit in April 1962 and March 1964, and both functioned most successfully. The lecture describes the NASA Pulsed Frequency Modulated telemetry system, including the methods used to store and transmit the data to ground stations, the digitising techniques used to prepare these data for entry into a computer and, finally, the organisation of the central data handling operations to the point where the partially or wholly reduced results were handed over to the various experimenters for analysis.
Cotton Spraying in Rhodesia
Authors: Johnstone D. R. 
Published: July 2016

The past decade has seen considerable advance in the production of cotton from Rhodesia and the adjacent former Federation territories of Malawi and Zambia, brought about very largely by the introduction of effective pest control measures originating from the work of the Cotton Pest Research Scheme, located at Gatooma, Rhodesia.Complementary to a work programme investigating the type and formulation of insecticides capable of controlling an insect pest complex including bollworms, jassids, aphids and stainers, attention has been given to the design of spray equipment suited to both extensive European and intensive African forms of cultivation. The “tailboom” modification to the conventional knapsack sprayer has been developed and this versatile piece of equipment in several mechanised guises forms the basis of the recommended ground spray machinery.
The Low-Cost Autogyro
Authors: Wallis K. H. 
Published: July 2016

Autogyro principles and theory are well known and only the practical aspects of design and construction of the smallest of autogyro aircraft will be considered on this occasion. Also, at this stage, it would be inappropriate to be specific about prices of such aircraft owing to the difficulty of estimating production costs. Tare weights, however, may provide some clues as to costs.In the “thirties” the autogyro had been brought to quite a high standard of performance, mainly through the pioneering and development efforts of one man, Senor Juan de la Cierva.During those years many ideas, which would today be regarded as novel, had been tried. Jump-start, pusher engines and tricycle undercarriages are not new.