bluuebunny/crossref_metadata_2025_split huggingface dataset:
On a distributed clustering process of Coffman, Courtois, Gilbert and Piret
Authors: van den Berg J. , Ermakov A. 
Published: July 2016

Coffman, Courtois, Gilbert and Piret (1991) have introduced a flow process in graphs, where each vertex gets an initial random resource, and where at each time vertices with large resources tend to attract resources from neighbours. The initial resources are assumed to be i.i.d., with a continuous distribution.
We are mainly interested in the following question: does, with probability 1, the resource of each vertex change only finitely many times?
Coffman et al. concentrate mainly on the case where the graph corresponds with the integer points on the line, in which case it is easily seen that the answer to the above question is positive. For higher-dimensional lattices they make general remarks which suggest that the answer to the above question is still positive. However, no proof seems to be known.
We restrict to the case of the square lattice, and, by a percolation approach, we reduce the question above to the question whether a certain quantity, which can be obtained from a finite computation, is sufficiently small. This computation is, however, still too long to be executed in an acceptable time. We therefore apply Monte Carlo simulation for this finite problem, which gives overwhelming evidence that, for the square lattice, the answer to the main question is positive.
Random secants of a convex body
Authors: Kingman J. F. C. 
Published: July 2016

Summary
Let two points be taken at random in an n-dimensional convex body K, and let σ be the line joining them. The distribution of σ is found and compared with other distributions for random secants of K. More generally, if r + 1 ≦ npoints are taken in K, the distribution of the r-dimensional affine subspace containing them is computed. The results find application to the n-dimensional case of a problem of Sylvester.
Inequalities with applications to percolation and reliability
Authors: Van Den Berg J. , Kesten H. 
Published: July 2016

A probability measure μ on ℝn
+ is defined to be strongly new better than used (SNBU) if for all increasing subsets . For n = 1 this is equivalent to being new better than used (NBU distributions play an important role in reliability theory). We derive an inequality concerning products of NBU probability measures, which has as a consequence that if μ
1, μ
2, ···, μn
are NBU probability measures on ℝ+, then the product-measure μ = μ × μ
2 × ··· × μn
on ℝn
+ is SNBU. A discrete analog (i.e., with N instead of ℝ+) also holds.
Applications are given to reliability and percolation. The latter are based on a new inequality for Bernoulli sequences, going in the opposite direction to the FKG–Harris inequality. The main application (3.15) gives a lower bound for the tail of the cluster size distribution for bond-percolation at the critical probability. Further applications are simplified proofs of some known results in percolation. A more general inequality (which contains the above as well as the FKG-Harris inequality) is conjectured, and connections with an inequality of Hammersley [12] and others ([17], [19] and [7]) are indicated.
On the maximum of random fields represented by stochastic integrals over circles
Authors: Orsingher Enzo 
Published: July 2016

In this paper we obtain an upper bound for the maximum of random fields of the form , where CP
denotes circles of fixed radius and dW(P′) is a plane white noise field.
The results presented are obtained by means of successive steps involving Slepian's lemma for random fields, inequalities on Brownian fields and planar stochastic integrals.
On the maximum of gaussian fourier series emerging in the analysis of random vibrations
Authors: Orsingher Enzo 
Published: July 2016

In this paper we study the maximum of Gaussian Fourier series emerging in the analysis of random vibrations of a finite string. Evaluating the distribution of the maximal displacement corresponds to the analysis of the maximum for the related Gaussian Fourier series with independent coefficients.
When vibrations are triggered by an initial white noise disturbance (where the instantaneous form of the vibrating string is composed of three processes pieced together) we give upper bounds for the maximal displacement.
In the last section we consider forced vibrations at special instants where the instantaneous form of the vibrating string has the structure of a Brownian bridge. This enables us to give the exact distribution of the maximum for the related sine series.
Extremal properties of the FIFO discipline in queueing networks
Authors: Righter Rhonda , Shanthikumar J. George 
Published: July 2016

We show that using the FIFO service discipline at single server stations with ILR (increasing likelihood ratio) service time distributions in networks of monotone queues results in stochastically earlier departures throughout the network. The converse is true at stations with DLR (decreasing likelihood ratio) service time distributions. We use these results to establish the validity of the following comparisons:
(i) The throughput of a closed network of FIFO single-server queues will be larger (smaller) when the service times are ILR (DLR) rather than exponential with the same means.
(ii) The total stationary number of customers in an open network of FIFO single-server queues with Poisson external arrivals will be stochastically smaller (larger) when the service times are ILR (DLR) rather than exponential with the same means.
We also give a surprising counterexample to show that although FIFO stochastically maximizes the number of departures by any time t from an isolated single-server queue with IHR (increasing hazard rate, which is weaker than ILR) service times, this is no longer true for networks of more than one queue. Thus the ILR assumption cannot be relaxed to IHR.
Finally, we consider multiclass networks of exponential single-server queues, where the class of a customer at a particular station determines its service rate at that station, and show that serving the customer with the highest service rate (which is SEPT — shortest expected processing time first) results in stochastically earlier departures throughout the network, among all preemptive work-conserving policies. We also show that a cµ rule stochastically maximizes the number of non-defective service completions by any time t when there are random, agreeable, yields.
L'intégrale du mouvement brownien
Authors: Lachal Aimé 
Published: July 2016

Let be the Brownian motion process starting at the origin, its primitive and Ut
= (Xt+x + ty, Bt
+ y), , the associated bidimensional process starting from a point . In this paper we present an elementary procedure for re-deriving the formula of Lefebvre (1989) giving the Laplace–Fourier transform of the distribution of the couple (σ α, Uσa
), as well as Lachal's (1991) formulae giving the explicit Laplace–Fourier transform of the law of the couple (σ ab, Uσab
), where σ α
and σ ab
denote respectively the first hitting time of from the right and the first hitting time of the double-sided barrier by the process . This method, which unifies and considerably simplifies the proofs of these results, is in fact a ‘vectorial' extension of the classical technique of Darling and Siegert (1953). It rests on an essential observation (Lachal (1992)) of the Markovian character of the bidimensional process .
Using the same procedure, we subsequently determine the Laplace–Fourier transform of the conjoint law of the quadruplet (σ α, Uσa, σb, Uσb
).
Asymptotic inference for an Ising lattice III. Non-zero field and ferromagnetic states
Authors: Pickard David K. 
Published: July 2016

In previous papers (1976), (1977) limit theorems were obtained for the classical Ising model in the absence of an external magnetic field, thereby providing a basis for asymptotic inference. The present paper extends these results to arbitrary external magnetic fields. Statistical inference for this model is important because its nearest-neighbour interactions provide a natural first approximation to spatial interaction among binary variables located on square lattices.
The most interesting behaviour occurs in zero field and at or beyond the critical point. In this case, the central limit result for nearest-neighbour interactions requires an unusual norming, the limiting variances may depend on the nature of the boundary conditions, and there cannot be any central limit result for external magnetic field. The implications of these phenomena for statistical inference are also discussed. In particular, the maximum likelihood estimator of magnetic field is not consistent. Rather it appears to have a non-trivial asymptotic distribution.
Basic analysis of a head-of-the-line priority queue with renewal type input
Authors: Schassberger R. 
Published: July 2016

A single server is fed by a renewal stream of individual customers. These are of type k with probability πk, k = 1, …, N, and are all served individually. Upon completion of a service the server proceeds immediately with a customer of the lowest type (= highest priority) present, if any. Service times for type k are drawn from a general distribution function Bk
(t) concentrated on (0, ∞).
We lay the foundations for a broad analysis of the model.
On the equivalence of certain Markov chains
Authors: Vit Pedro 
Published: July 2016

It is shown that an irreducible and aperiodic Markov chain can be altered preserving irreducibility without altering the nature of the chain in the sense that, the modified chain is transient (recurrent) if and only if the original chain is transient (recurrent). Furthermore, it is shown by means of a counterexample that ergodicity (null-recurrence) is not preserved.
An interesting application of this result is a simple proof of Pakes's generalization of Foster's criterion for a chain to be recurrent.
Braess's paradox in a queueing network with state-dependent routing
Authors: Calvert Bruce , Solomon Wiremu , Ziedins Ilze 
Published: July 2016

We consider initially two parallel routes, each of two queues in tandem, with arriving customers choosing the route giving them the shortest expected time in the system, given the queue lengths at the customer's time of arrival. All interarrival and service times are exponential.
We then augment this network to obtain a Wheatstone bridge, in which customers may cross from one route to the other between queues, again choosing the route giving the shortest expected time in the system, given the queue lengths ahead of them.
We find that Braess's paradox can occur: namely in equilibrium the expected transit time in the augmented network, for some service rates, can be greater than in the initial network.
Fixation in bisexual models with variable population sizes
Authors: Möhle M. 
Published: July 2016

A general exchangeable bisexual model with variable population sizes is introduced. First the forward process, i.e. the number of certain descending pairs, is studied. For the bisexual Wright-Fisher model fixation of the descendants occurs, i.e. their proportion tends to 0 or 1 almost surely.The main part of this article deals with necessary and sufficient conditions for ultimate homozygosity, i.e. the proportion of an arbitrarily chosen allelic type tends to 0 or 1 almost surely. The results are applied to a bisexual Wright-Fisher model and to a bisexual Moran model.
Darwin's log: a toy model of speciation and extinction
Authors: Aldous David 
Published: July 2016

Stochastic models for the origin and extinction of species have been rather neglected in applied probability. As an alternative to modelling speciation and extinction as intrinsically random, I shall describe and show simulations of a rulebased model. This involves mathematical representations of notions such as genetic type of species, environmental niche, fitness of a species in a niche, and adaptation. There are underlying random mechanisms for changes of niche sizes and for disconnection and reconnection of geographical regions, and these ultimately drive the evolution of species.
Other approaches to mathematical modelling of evolution are briefly mentioned.
Two-stage output procedure of a finite dam
Authors: Zuckerman Dror 
Published: July 2016

The input of water into a finite dam is a Wiener process with positive drift. Water may be released at either of two possible rates 0 or M. At any time the output rate can be increased from 0 to M with cost KM, (K ≧ 0), or decreased from M to 0 with zero cost. There is a reward of A monetary units for each unit of output, (A &gt; 0). We will consider the problem of specifying an optimal control output policy under the following optimal criteria:

(a)
Minimum total long-run average cost per unit time.

(b)
Minimum expected total discounted cost.
On the age distribution of a Markov chain
Authors: Pakes Anthony G. 
Published: July 2016

This paper develops the notion of the limiting age of an absorbing Markov chain, conditional on the present state. Chains with a single absorbing state {0} are considered and with such a chain can be associated a return chain,obtained by restarting the original chain at a fixed state after each absorption. The limiting age,A(j), is the weak limit of the timegivenXn=j(n → ∞).A criterion for the existence of this limit is given and this is shown to be fulfilled in the case of the return chains constructed from the Galton–Watson process and the left-continuous random walk. Limit theorems forA(J) (J →∞) are given for these examples.
DEWORMING DELUSIONS? MASS DRUG ADMINISTRATION IN EAST AFRICAN SCHOOLS
Authors: Allen Tim , Parker Melissa 
Published: July 2016

SummaryRecent debates about deworming school-aged children in East Africa have been described as the ‘Worm Wars’. The stakes are high. Deworming has become one of the top priorities in the fight against infectious diseases. Staff at the World Health Organization, the Gates Foundation and the World Bank (among other institutions) have endorsed the approach, and school-based treatments are a key component of large-scale mass drug administration programmes. Drawing on field research in Uganda and Tanzania, and engaging with both biological and social evidence, this article shows that assertions about the effects of school-based deworming are over-optimistic. The results of a much-cited study on deworming Kenyan school children, which has been used to promote the intervention, are flawed, and a systematic review of randomized controlled trials demonstrates that deworming is unlikely to improve overall public health. Also, confusions arise by applying the term deworming to a variety of very different helminth infections and to different treatment regimes, while local-level research in schools reveals that drug coverage usually falls below target levels. In most places where data exist, infection levels remain disappointingly high. Without indefinite free deworming, any declines in endemicity are likely to be reversed. Moreover, there are social problems arising from mass drug administration that have generally been ignored. Notably, there are serious ethical and practical issues arising from the widespread practice of giving tablets to children without actively consulting parents. There is no doubt that curative therapy for children infected with debilitating parasitic infections is appropriate, but overly positive evaluations of indiscriminate deworming are counter-productive.
Bank Skin in the Game and Loan Contract Design: Evidence from Covenant-Lite Loans
Authors: Billett Matthew T. , Elkamhi Redouane , Popov Latchezar , Pungaliya Raunaq S. 
Published: July 2016

AbstractIn a model of dual-agency problems where borrower–lender and bank–nonbank incentives may conflict, we predict a hockey stick relation between bank skin in the game and covenant tightness. As bank participation declines, covenant tightness increases until reaching a low threshold, at which point the relation sharply reverses and covenant protection is removed with a commensurate increase in spread. We find support for the hockey stick relation with bank’s stake in covenant-lite loans averaging 8% (0% median). We also find that covenant-lite loans are more likely when borrower moral hazard is less severe and when bank relationship rents are high.
Airworthiness
Authors: Jameson D. M. 
Published: July 2016

I would like to preface my remarks by gratefully acknowledging the inspiration I have received from my colleagues and others with whom the problems I shall talk about have been discussed, and by making it clear that, although my views are naturally coloured by the work on which I am engaged, they must not necessarily be taken as the official views of the Air Registration Board.The supersonic aeroplane, due to its novelty, presents the three main types of airworthiness problem in a more pressing form. These are: knowledge of the environment; knowledge of what the aeroplane must be able to do in that environment (which includes a clear idea of acceptable risk); and obtaining, before passenger service, the necessary confidence that the intended safety level will be achieved. I can only touch on a few of the individual problems.
The First 25 Years of the Bristol Engine Department
Authors: Fedden Roy 
Published: July 2016

Few things have given me greater satisfaction than the invitation to give the Seventh Barnwell Memorial Lecture, and tell the story of the early history of the Bristol Engine Department.The Bristol Aeroplane Company which was founded by that great merchant venturer and pioneer of transport, Sir George White, has just passed its 50th Anniversary. I always look upon the 20 odd years spent with the Bristol Company as among some of the happiest and most stimulating in my engineering career.
The Royal Aeronautical Society The First Fifty Years
Authors: Laurence pritchard J. 
Published: July 2016

The year 1868 was destined to be memorable and significant in the history of the Society. It was the year in which the first Aeronautical Exhibition in the world was held.The Mechanics Magazine for 7th February 1868 said:“ The objects for exhibition,” quoting from a circular issued by the Society, “ and for which prizes will be offered out of the funds now raising, are light engines and machinery, complete working apparatus, models (working and stationary), plans and drawings, articles of interest commemorating previous experiments, kites or other similar apparatus proposed to be used in cases of shipwreck, traction, or in the attainment of other useful ends; paintings of landscapes and cloud scenery observed from a balloon.”
The Training of Guided Missiles Engineers
Authors: Nayler J. L. 
Published: July 2016

An All-Day Discussion on the Training of Guided Missiles Engineers was held by the Astronautics and Guided Flight Section of the Society in the Lecture Theatre on 16th March 1961. The Chair was taken by Mr. A. D. Baxter, M.Eng., F.R.Ae.S., M.I.Mech.E., F.Inst.P., Executive Director (Engineering), de Havilland Engine Co. Ltd.Introductory papers were given by L. H. Bedford, C.B.E., M.A., B.Sc, A.F.R.AcS., Director of Engineering, Guided Weapons Division, English Electric Aviation Ltd.; Ian Dean, M.A., Education Officer, de Havilland Aircraft Co. Ltd.; F. G. Tarrant, Assistant Director, Guided Weapons (Engineering), Ministry of Aviation; Professor G. A. Whitfield, B.Sc, F.R.Ae.S., Professor and Head of Department of Aircraft Electrical Engineering, College of Aeronautics; Commander E. G. lege, Greenwich; Professor C. Holt Smith, C.B.E., M.Sc., M.I.E.E., Head of Department of Electrical and Instrument Technology, Royal Military College of Science, Shrivenham; and Wing Cdr. G. C. Wainwright, B.Sc, A.F.R.Ae.S., A.F.I.A.S., Chief Instructor, Weapon Systems Engineering Wing, R.A.F. Technical College, Henlow. The Discussion was opened by M. Armstrong, Chief Training Engineer, Bristol Aircraft Ltd.; Professor E. J. Richards, O.B.E., M.A., D.Sc, F.R.Ae.S., Professor of Aeronautical Engineering, University of Southampton; Colonel J. P. G. Lewis, War Office (Directorate of Equipment Production), and Colonel W. J. Mellors, M.B.E., School of Electronic Engineering, R.E.M.E. Twenty-three other speakers took part in the General Discussion.
Effect of Wall Divergence on Sonic Flows in Solid Wall Tunnels
Authors: Tirumalesa D. , Satyanarayana B. 
Published: July 2016

The effect of wall divergence (in excess of the normal value given for compensating the Boundary Layer growth on the tunnel walls), on the simulation of Sonic flows in solid wall wind tunnels is presented in this note which is a condensed version of Ref. 1.Recently Spreiter showed that flows with free stream Mach number one can be simulated reasonably well in choked solid tunnels. Berndt and Petersohn showed that the thickening of the boundary layer on the walls of solid wall tunnels reduced the interference considerably. Wall divergence θg in excess of the normal one of about one degree (used for Boundary Layer compensation) may lead to favourable conditions for the thickening of the Boundary Layer and this appeared to be an interesting way of reducing the interference.
On The Correlation and Presentation of Information on Turbulent Variable Property Heat Transfer in Tubes
Authors: Ward Smith A. J. 
Published: July 2016

This note is concerned with the correlation and presentation of information on heat transfer under conditions of turbulent forced convection for the flow of gases in tubes. Discussion will be confined to the region where thermal entrance effects are absent and, furthermore, it will be assumed that the flow velocity is sufficiently low for compressibility effects to be neglected.The subject matter will be discussed in general terms only and it is not intended to produce quantitative conclusions, which may, however, be found in reference 11.
R.101 and Other Airships—The Process of Development
Authors: Cave-Browne-Cave T. R. 
Published: July 2016

In addressing the Historical Group it is desirable to let technical detail fall into the background so that the more general consideration of personal problems, policy and organisation can be clearly examined.Technical detail changes so much more with time than do the human and administrative considerations, that the greatest value for history comes perhaps from the study of the latter.
The Relative Roles of Man and Instruments in Space
Authors: Francis R. H. , Hilton W. F. 
Published: July 2016

This Discussion, held by the Astronautics and Guided Flight Section on 11th December 1962 in the Lecture Theatre, 4 Hamilton Place, London W.1, was introduced by R. H. Francis, B.Sc, M.Sc, F.R.Ae.S., F.B.I.S., and W. F. Hilton, D.Sc, Ph.D., A.R.C.S., D.I.C., F.R.Ae.S. The following report was prepared by J. L. Nayler, M.A., F.R.Ae.S., F.A.I.A.A.This interesting discussion ranged over the whole known field from that of near space with meteorological, communications, navigation and astronomical satellites, from prestige flights and satellites with military applications to interplanetary space with all the added difficulties arising from radiation and other engineering problems; landings and bases were mentioned as regards the planets. The desirability of this country having its own space problem, in addition to co-operation with other countries in Europe, was touched upon. The discussion was opened by Mr. R. H. Francis and Dr. W. F. Hilton, the former concentrating mainly on the instrumental rôles and the latter on the irreplaceability of man in certain aspects of space development.
Blue Streak Static Firings
Authors: Hume C. R. 
Published: July 2016

Blue Streak is to be the first stage booster of a three stage satellite and space probe launcher being developed in Europe. The main contractor for the Blue Streak rocket vehicle is Hawker Siddeley Dynamics Ltd. with the propulsion system the responsibility of Rolls-Royce Ltd. The work reported in this paper was carried out under Ministry of Aviation contract and forms part of the United Kingdom participation in the initial programme of the European Launcher Development Organisation (E.L.D.O.).The static or “tethered” firing of liquid-propelled rocket vehicles is an essential process in the establishment of operational reliability before attempting launchings.