bluuebunny/crossref_metadata_2025 huggingface dataset:
Fractionated Er:YAG laser versus fully ablative Er:YAG laser for scar revision: Results of a split scar, double blinded, prospective trial
Authors: Tidwell W. James , Owen Cindy E. , Kulp‐Shorten Carol , Maity Abhishek , McCall Michael , Brown Timothy S.
Published: July 2016

Background and Objective

Ablative laser resurfacing is a common treatment for post‐surgical scars. Fractional ablative laser resurfacing has been an emerging treatment option that is replacing fully ablative lasers in many applications. Data comparing fractionated and fully ablative lasers in treating post‐operative scars are lacking.

Study Design

Twenty patients were enrolled in a split scar study following excisions from dermatologic surgery. Wounds had to be older than 8 weeks but less than 1 year. The scars were randomly divided into two halves. One half of the scar was treated with fully ablative erbium‐doped yttrium aluminum garnet (Er:YAG) and the other was treated with fractionated Er:YAG. The scars were treated at monthly intervals for 3 months, then followed up at months 1 and 2 after the last treatment. POSAS was used to evaluate the scars by a panel of dermatologists blinded to the lasers in conjunction with the patients, who were also blinded.

Results

Physicians and patients both observed a superior outcome of 32.5% (P = 0.019) and 58.1% (P = 0.001), respectively, using the POSAS. There was no trend in difference in pain reported by the patient between the two lasers. Patients overwhelmingly preferred the fractionated Er:YAG laser (94%) to the fully ablative laser when asked at the end of the study.

Conclusions

Although this study is limited by a short follow‐up period, it shows a statistically significant superior outcome in fractionated Er:YAG over fully ablative Er:YAG for scar revision. It also adds quantitative values to the assessment of scar appearance when treated with fractionated lasers compared to fully ablative lasers. It was also found that the fractionated Er:YAG had increased patient satisfaction, but there was no difference in reported pain scores. These data are useful when counseling patients undergoing laser surgery. Lasers Surg. Med. 48:837–843, 2016. © 2016 Wiley Periodicals, Inc.
The eye opener: Preparing for and performing facility siting to best communicate with upper management
Authors: James Michael
Published: July 2016

Upon completion of a facility siting study, a major step in the critical path for implementation is acceptance from upper management on the remediation plan. Communicating with upper management occurs at the end of several steps which can be strategically mapped in order to maximize upper management's understanding of the needs of a site's remediation requirements.

Using an example chemical plant, this paper will detail the process of initiating a facility siting study, provide a novel approach to prioritizing building remediation requirements, and discuss how the resulting information can best be framed and communicated to upper management. In addition to discussing strategies for effective communication with upper management on proposed facility siting strategies, the paper also details an online system that could be used for keeping facility siting data evergreen after the study is completed. © 2016 American Institute of Chemical Engineers Process Saf Prog 36: 158–164, 2017
Optical properties of silica aerogels with embedded multiwalled carbon nanotubes
Authors: Chernov Alexander I. , Predein Alexander Y. , Danilyuk Alexander F. , Kuznetsov Vladimir L. , Larina Tatyana V. , Obraztsova Elena D.
Published: July 2016

Multiwalled carbon nanotubes (MWCNTs) were successfully incorporated inside silica aerogel matrix. Solid composite materials were investigated by high‐resolution transmission microscopy, scanning electron microscopy, optical spectroscopy. MWCNTs in the form of small bundles and individual tubes get locked inside the aerogel between its pores resulting in the local solution‐free environment for nanotubes. Optical transmission of the composite material can be modified by the amount of the added MWCNTs. Nonlinear optical properties were studied by a Z‐scan technique. Composite materials demonstrate saturable absorption for femtosecond laser pulses at 515 nm wavelength that are attributed to the properties of embedded nanotubes. Silica aerogels possess significantly better thermal stability compared to polymer matrices, hosts that are frequently used for saturable absorption applications of carbon nanotubes. Solid and lightweight silica aerogels with embedded nanotubes can be used as optical elements for various photonic devices.

Photo of silica aerogel with embedded MWCNTs. Normalized Z‐scan transmittance of silica aerogel with nanotubes for two different on‐focus intensities.
Practical analysis of Li distribution by EELS
Authors: Akita Tomoki , Taguchi Noboru
Published: July 2016

Practical measurement of the Li distribution in Li‐ion battery electrode materials is demonstrated using a scanning transmission electron microscopy‐electron energy loss spectroscopy (EELS) spectrum imaging method. Lithium distribution images were obtained for LiCoO2 positive electrode material using conventional software, Digital Micrograph (Gatan), for STEM‐EELS spectrum imaging data. Some data processing methods using Li K‐edge EELS spectra were examined to obtain a Li distribution image for LiCoO2. A quantitative method was successfully applied to Li2TiO3, while it was not suitable for LiCoO2. Issues regarding the measurement of Li distributions in electrode materials are discussed. Copyright © 2016 John Wiley & Sons, Ltd.
Optimally combining propensity score subclasses
Authors: Rudolph Kara E. , Colson K. Ellicott , Stuart Elizabeth A. , Ahern Jennifer
Published: July 2016

Propensity score methods, such as subclassification, are a common approach to control for confounding when estimating causal effects in non‐randomized studies. Propensity score subclassification groups individuals into subclasses based on their propensity score values. Effect estimates are obtained within each subclass and then combined by weighting by the proportion of observations in each subclass. Combining subclass‐specific estimates by weighting by the inverse variance is a promising alternative approach; a similar strategy is used in meta‐analysis for its efficiency. We use simulation to compare performance of each of the two methods while varying (i) the number of subclasses, (ii) extent of propensity score overlap between the treatment and control groups (i.e., positivity), (iii) incorporation of survey weighting, and (iv) presence of heterogeneous treatment effects across subclasses. Both methods perform well in the absence of positivity violations and with a constant treatment effect with weighting by the inverse variance performing slightly better. Weighting by the proportion in subclass performs better in the presence of heterogeneous treatment effects across subclasses. We apply these methods to an illustrative example estimating the effect of living in a disadvantaged neighborhood on risk of past‐year anxiety and depressive disorders among U.S. urban adolescents. This example entails practical positivity violations but no evidence of treatment effect heterogeneity. In this case, weighting by the inverse variance when combining across propensity score subclasses results in more efficient estimates that ultimately change inference. Copyright © 2016 John Wiley & Sons, Ltd.
The role of early inter-professional and inter-agency encounters in increasing students’ awareness of the clinical and community context of medicine
Authors: Thandi Charankumal Singh , Forrest Simon , Williamson Catherine
Published: July 2016

Coordinated input from a variety of health and social care professionals into medical education helps students to become strong, effective, successful and competent future practitioners able to function within the multi-disciplinary environment which characterizes modern medicine. This paper presents a new model of teaching developed within the context of the Phase 1 Medicine Programme at Durham, which has been used to help prepare students for this by intertwining a selection of lectures and activities run by external organizations with additional clinical exposure and experience. This one-week learning journey was called the Additional Clinical Experience (ACE) week, and now forms an integral part of the curriculum at Durham University.
Description of a Hospital Outbreak of Middle East Respiratory Syndrome in a Large Tertiary Care Hospital in Saudi Arabia
Authors: Balkhy Hanan H. , Alenazi Thamer H. , Alshamrani Majid M. , Baffoe-Bonnie Henry , Arabi Yaseen , Hijazi Raed , Al-Abdely Hail M. , El-Saed Aiman , Al Johani Sameera , Assiri Abdullah M. , bin Saeed Abdulaziz
Published: July 2016

BACKGROUND

Since the first isolation of Middle East respiratory syndrome coronavirus (MERS-CoV) in Saudi Arabia in 2012, sporadic cases, clusters, and sometimes large outbreaks have been reported.

OBJECTIVE

To describe the recent (2015) MERS-CoV outbreak at a large tertiary care hospital in Riyadh, Saudi Arabia.

METHODS

We conducted an epidemiologic outbreak investigation, including case finding and contact tracing and screening. MERS-CoV cases were categorized as suspected, probable, and confirmed. A confirmed case was defined as positive reverse transcription polymerase chain reaction test for MERS-CoV.

RESULTS

Of the 130 suspected cases, 81 (62%) were confirmed and 49 (38%) were probable. These included 87 patients (67%) and 43 healthcare workers (33%). Older age (mean [SD], 64.4 [18.3] vs 40.1 [11.3] years, P<.001), symptoms (97% vs 58%, P<.001), and comorbidity (99% vs 42%, P<.001) were more common in patients than healthcare workers. Almost all patients (97%) were hospitalized whereas most healthcare workers (72%) were home isolated. Among 96 hospitalized cases, 63 (66%) required intensive care unit management and 60 (63%) required mechanical ventilation. Among all 130 cases, 51 (39%) died; all were patients (51 [59%]) with no deaths among healthcare workers. More than half (54%) of infections were believed to be caught at the emergency department. Strict infection control measures, including isolation and closure of the emergency department, were implemented to interrupt the chain of transmission and end the outbreak.

CONCLUSION

MERS-CoV remains a major healthcare threat. Early recognition of cases and rapid implementation of infection control measures are necessary.

Infect Control Hosp Epidemiol 2016;1–9
LGBT OLDER ADULTS, CHOSEN FAMILY, AND CAREGIVING
Authors: Knauer Nancy J.
Published: July 2016

In the United States, informal elder care is principally the responsibility of younger relatives. Adult children perform the majority of elder care and non-relatives perform only 14 percent of care. Caregiving in the lesbian, gay, bisexual, and transgender, or LGBT, community follows a very different pattern that reflects the importance of “chosen family” in the lives of LGBT older adults. Instead of relying on relatives, LGBT older adults largely care for each other. Relatives provide only 11 percent of all elder care. This article explores the high level of caregiving by non-relatives in the LGBT community. It asks what motivates friends, neighbors, and community members to provide care for someone whom the law considers a legal stranger. It also asks what steps policy makers can take to facilitate and encourage this type of caregiving. Finally, it asks what lessons can be learned from LGBT older adults about the nature of both caregiving and community. As the aging population becomes more diverse, aging policies will have to become more inclusive to address the differing needs of various communities, including LGBT older adults. The potential lessons learned from the pattern of elder care in the LGBT community, however, extend far beyond a simple commitment to diversity.
Surface velocity fluctuations for Glaciar Universidad, central Chile, between 1967 and 2015
Authors: WILSON RYAN , MERNILD SEBASTIAN H. , MALMROS JEPPE K. , BRAVO CLAUDIO , CARRIÓN DANIELA
Published: July 2016

For the Andes Cordillera, where observed mass-balance records are sparse, long-term glacier velocity measurements potentially represent a useful tool for assessing glacier health. Utilising manual and automatic feature-tracking techniques applied to Corona, Landsat and ASTER satellite imagery, this paper presents surface velocity fluctuations for Glaciar Universidad between 1967 and 1969, and 1985 and 2015, the longest such time series available for the Andes Cordillera, outside Patagonia. This time series reveals an increase in the surface velocities of the main glacier trunk between 1967 and 1987 (~90%) followed by a deceleration between 1987 and 2015 (~80%), with ice velocities observed between 2014 and 2015 possibly representing a 48 a low. In response to the surface velocity fluctuations, the glacier front advanced between 1985 and 1992 (cumulative change of 137 ± 14 m), and again to a lesser magnitude during the 1996–98 and 2004–08 periods. Although having exhibited possible surge behaviour during the 1940s, the synchrony of the glacier changes presented for Glaciar Universidad with those reported for nearby glaciers, suggests that this glacier is responding to climatic trends. If the above scenario is true, the results indicate a general pattern of increasingly negative glacier mass-balance conditions since the late 1980s.
Weak homogenization of point processes by space deformations
Authors: Senoussi R. , Chadœuf J. , Allard D.
Published: July 2016

We study the transformation of a non-stationary point process ξ on ℝn into a weakly stationary point process ͂ξ, with ͂ξ(B) = ξ(Φ-1(B)), where B is a Borel set, via a deformation Φ of the space ℝn. When the second-order measure is regular, Φ is uniquely determined by the homogenization equations of the second-order measure. In contrast, the first-order homogenization transformation is not unique. Several examples of point processes and transformations are investigated with a particular interest to Poisson processes.
Long-range dependent point processes and their Palm-Khinchin distributions
Authors: Daley D. J. , Rolski T. , Vesilo Rein
Published: July 2016

For a stationary long-range dependent point process N(.) with Palm distribution P0, the Hurst index H ≡ sup{h : lim sup t→∞t-2h var N(0,t] = ∞} is related to the moment index κ ≡ sup{k : E0(Tk) < ∞} of a generic stationary interval T between points (E0 denotes expectation with respect to P0) by 2H + κ ≥ 3, it being known that equality holds for a stationary renewal process. Thus, a stationary point process for which κ < 2 is necessarily long-range dependent with Hurst index greater than ½. An extended example of a Wold process shows that a stationary point process can be both long-range count dependent and long-range interval dependent and have finite mean square interval length, i.e., E0(T2) < ∞.
Random walks crossing curved boundaries: a functional limit theorem, stability and asymptotic distributions for exit times and positions
Authors: Doney R. A. , Maller R. A.
Published: July 2016

We study the (two-sided) exit time and position of a random walk outside boundaries which are regularly varying functions of smaller order at infinity than the square root. A natural domain of interest is those random walks which are attracted without centring to a normal law, or are relatively stable. These are shown to have ‘stable’ exit positions, in that the overshoot of the curved boundary is of smaller order of magnitude (in probability) than the boundary, as the boundary expands. Surprisingly, this remains true regardless of the shape of the boundary. Furthermore, within the same natural domain of interest, norming of the exit position by, for example, the square root of the exit time (in the finite-variance case), produces limiting distributions which are computable from corresponding functionals of Brownian motion. We give a functional limit theorem for attraction of normed sums to general infinitely divisible random variables, as a means of making this, and more general, computations. These kinds of theorems have applications in sequential analysis, for example.
On Laslett's transform for the Boolean model
Authors: Barbour A. D. , Schmidt V.
Published: July 2016

Consider the Boolean model in ℝ2, where the germs form a homogeneous Poisson point process with intensity λ and the grains are convex compact random sets. It is known (see, e.g., Cressie (1993, Section 9.5.3)) that Laslett's rule transforms the exposed tangent points of the Boolean model into a homogeneous Poisson process with the same intensity. In the present paper, we give a simple proof of this result, which is based on a martingale argument. We also consider the cumulative process of uncovered area in a vertical strip and show that a (linear) Poisson process with intensity λ can be embedded in it.
The excursions of a stationary Gaussian process outside a large two-dimensional region
Authors: Illsley Robert
Published: July 2016

Let X(t) be a continuous two-dimensional stationary Gaussian process with mean zero, having a marginal density function p[x] and covariance matrix R(t). Let Δ = {∂L; L > 0} be a family of piecewise smooth boundaries of similar two-dimensional star-shaped regions ΓL. We show that, under two conditions on R(t), the asymptotic distribution of the duration of an excursion of X(t) outside ΓL, for large L, depends on the position of the maximum of p[x] on ∂L and on whether R′(0) is zero or not, should the maximum occur at a vertex. We obtain the asymptotic distributions of the duration of an excursion for each of the three cases that arise. We also generalise some results of Breitung (1994) on the asymptotic crossing rates of vector Gaussian processes.
Some control problems with random intervention times
Authors: Wang Hui
Published: July 2016

We consider the problem of optimally tracking a Brownian motion by a sequence of impulse controls, in such a way as to minimize the total expected cost that consists of a quadratic deviation cost and a proportional control cost. The main feature of our model is that the control can only be exerted at the arrival times of an exogenous uncontrolled Poisson process (signal). In other words, the set of possible intervention times are discrete, random and determined by the signal process (not by the decision maker). We discuss both the discounted problem and the ergodic problem, where explicit solutions can be found. We also derive the asymptotic behavior of the optimal control policies and the value functions as the intensity of the Poisson process goes to infinity, or roughly speaking, as the set of admissible controls goes from the discrete-time impulse control to the continuous-time bounded variation control.
Markovian bounds on functions of finite Markov chains
Authors: Ledoux James , Truffet Laurent
Published: July 2016

In this paper, we obtain Markovian bounds on a function of a homogeneous discrete time Markov chain. For deriving such bounds, we use well-known results on stochastic majorization of Markov chains and the Rogers–Pitman lumpability criterion. The proposed method of comparison between functions of Markov chains is not equivalent to generalized coupling method of Markov chains, although we obtain same kind of majorization. We derive necessary and sufficient conditions for existence of our Markovian bounds. We also discuss the choice of the geometric invariant related to the lumpability condition that we use.
The M/G/1 queue with two service speeds
Authors: Boxma O. J. , Kurkova I. A.
Published: July 2016

We consider an M/G/1 queue with the special feature that the speed of the server alternates between two constant values sL and sH > sL. The high-speed periods are exponentially distributed, and the low-speed periods have a general distribution. Our main results are: (i) for the case that the distribution of the low-speed periods has a rational Laplace–Stieltjes transform, we obtain the joint distribution of the buffer content and the state of the server speed; (ii) for the case that the distribution of the low-speed periods and/or the service request distribution is regularly varying at infinity, we obtain explicit asymptotics for the tail of the buffer content distribution. The two cases in which the offered traffic load is smaller or larger than the low service speed are shown to result in completely different asymptotics.
Coalescence times and F ST values in subdivided populations with symmetric structure
Authors: Wilkinson-Herbots Hilde M.
Published: July 2016

The structured coalescent is a continuous-time Markov chain which describes the genealogy of a sample of homologous genes from a subdivided population. Assuming this model, some results are proved relating to the genealogy of a pair of genes and the extent of subpopulation differentiation, which are valid under certain graph-theoretic symmetry and regularity conditions on the structure of the population. We first review and extend earlier results stating conditions under which the mean time since the most recent common ancestor of a pair of genes from any single subpopulation is independent of the migration rate and equal to that of two genes from an unstructured population of the same total size. Assuming the infinite alleles model of neutral mutation with a small mutation rate, we then prove a simple relationship between the migration rate and the value of Wright's coefficientFSTfor a pair of neighbouring subpopulations, which does not depend on the precise structure of the population provided that this is sufficiently symmetric.
Closed queueing networks with blocking-a model for flexible manufacturing systems
Authors: Yao David D. W. , Buzacott J.A.
Published: July 2016

We consider a family of single-server queueing systems with two priority classes. The system operates under a dynamic priority queue discipline in which the relative priorities of customers increase with their waiting times, and which can be characterized by the urgency number. We investigate the transient as well as the steady-state behavior of the virtual waiting times of the two classes of customer as functions of the urgency number. Stochastic orderings, the joint distribution, and surprising limit results for these processes are obtained for the first time.
Measurement of Wiener kernels
Authors: Ito Yoshifusa
Published: July 2016

Since the late 1960s Wiener's theory on the non-linear functionals of white noise has been widely applied to the construction of mathematical models of non-linear systems, especially in the field of biology. For such applications the main part is the measurement of Wiener's kernels, for which two methods have been proposed: one by Wiener himself and the other by Lee and Schetzen. The aim of this paper is to show that there is another method based on Hida's differential operator.
Optimal scheduling in queueing networks
Authors: Massey F. J. , Miller D. F.
Published: July 2016

This paper derives an algorithm for finding a scheduling discipline for scheduling N customers at M service stations in a closed queueing network so as to optimize a performance measure which depends on the configuration of customers at the service stations.
Space-time evaluation of reservoir regulation policies
Authors: Deutsch Stuart J. , Ramos José A.
Published: July 2016

Stochastic modeling of vector hydrologic time series exhibiting spatial as well as temporal correlations is examined with the general class of STARIMA, space-time autoregressive integrated moving-average models.
Pressure cabins of elliptic cross section
Authors: Hitch H. P. Y.
Published: July 2016

Some observers believe that there will be such growth in the travelling public and such constraint on airport and airspace usage that, by early in the 2000s. very large passenger carrying aircraft will be required. By ‘very large’ is meant anything from 1,000 to 2,000 seaters. Whilst the problems which come to mind when musing on this possibility are mostly those of ‘passenger flow’ in the widest sense and rather less related to the vehicle itself, there are some issues related to the vehicle which suggest themselves. One is the choice of fuselage cross section.

Because cabins have to be pressurised (10 psi is a typical figure for cruise altitudes up to say 40,000 ft), it has been the norm to utilise circular cross sections (or double-bubble type) since the pressure forces are contained by hoop loads only, without frame bending, which affords a light and fatigue-insensitive structure (Fig. 1).
Fractal properties of inertial-range turbulence with implications for aircraft response
Authors: Jones J. G. , Foster G. W. , Haynes A.
Published: July 2016

Fractal geometry provides a method for modelling the scale dependence of fluctuations in atmospheric-turbulence velocity. In this paper the basic concepts are outlined and illustrated by a method of data analysis which, for a fractal process, displays measured probability distributions in scale-invariant form. To a first approximation the data exhibit statistical self-similarity, consistent with the classical theory of Kolmogorov. However, on more detailed analysis, the more intense fluctuations show systematic departures from self-similarity, consistent with recent theoretical estimates of the fractal dimension of the support of turbulence. Implications for aircraft gust response are discussed.
Some comments on the later stages of transition from laminar to turbulent flow in the flat plate boundary layer
Authors: Thomson K. D.
Published: July 2016

Pseudo-streamwise vortices develop during the transition of a boundary layer from the laminar to the turbulent state. It is suggested that the induced velocities associated with these vortices cause a gross change in the flow, and that the initial uniform flow is no longer tenable. The character of the flow in the boundary layer must change suddenly, and it is believed that this change provides the trigger for flow breakdown to turbulence.
Aerodynamic and hydrodynamic aspects of high-speed water surface craft
Authors: Nangia R. K.
Published: July 2016

High speeds on water are being attained in racing sport and in attempts on world speed records in various classes. Success, safety and stability of these craft depends upon the favourable interaction of their aerodynamic and hydrodynamic characteristics under the influence of two media, one about 800 times denser than the other. Speed on the straight course and in turns is important.

As its velocity increases, a craft experiences increasing dynamic pressure in water and to maintain the balance, the ‘wetted’ area of the craft reduces as it rises up (‘planing’). Modern fast craft have ‘tunnel-hulls’ and lifting areas to generate aerodynamic lift and to assist the craft to attain planing attitudes rapidly.

The ‘lifting’ areas may not necessarily be in the correct locations however. An example often seen is that of a power boat riding virtually on its propeller and ‘wallowing’ in an unstable manner. In this case the variation in riding height alters the relative positions of centres of aero- and hydro-lift such that the ‘stability-margins’ are near critical in both the longitudinal and the lateral sense.
On the speed of progressive waves in gust-tunnels of the QMC-type
Authors: Ishaq M. S. , Bernstein L.
Published: July 2016

In the Queen Mary College gust-tunnels, unsteady flows are generated by oscillating flaps attached to the downstream upper and lower surfaces of the contraction nozzle of a semi-open test section, open-return, low-speed wind-tunnel. The flow perturbations produced on the mainstream of velocity U∞, are of the travelling-wave type, with wave-velocity Q. Attention is drawn to the contradictory early measurements of Q/U∞. New data are presented which show Q/U∞ apparently diminishing along the tunnel axis from a high value near the nozzle exit to an asymptotic value of about 0·6 far downstream. Using a digital phase meter especially developed for the purpose it is shown that the explanation for this behaviour lies in the two-dimensional nature of the wave process in the region of the flaps.
Concepts of unreliability underlying the factor of safety for aircraft structures
Authors: Heath W. G.
Published: July 2016

In considering reliability, it is logical to look at sources of uncertainty, variability and inaccuracy. British Civil Airworthiness Requirements - Section D defines the factor of safety in terms of several sources of unreliability, as follows:

uncertainties in loads,

inaccuracies in structural analysis,

variability in the strength of materials.
Safety and availability of airborne weapons and their control in a 1553B based architecture
Authors: Clark G. D.
Published: July 2016

This paper is structured firstly to describe the operational requirements of a modern military aircraft with particular reference to its armament systems, secondly to derive and consider developing architectures for armament control and thirdly to present one of the architectures from an implementation point of view.

The paper concludes that the optimum architecture for safety, availability and control of airborne weapons can be derived logically from the military aircraft operational requirement. It is not necessary to indulge in over duplication to achieve a cost effective, safe and available system.
Some laminated plate optimum design studies using an interactive computer programme
Authors: Webber J. P. H.
Published: July 2016

An interactive computer programme, based on linear-elastic laminated plate theory, is used to study the effect of lay-up geometry on first ply failure loads. A maximum allowable strain failure criterion is used and a number of design problems are considered where searches are made for optimum lay-up configurations for typical carbon fibre reinforced plastic properties. The relative weakness of this material in tension across the fibres, is found to have a significant effect on first ply failure loads. An optimisation technique based on principal load directions is introduced and compared with the familiar 0/90/±45 lay-up configuration.
Civil aviation, hijacking and international terrorism — an historical and legal review
Authors: Dawson Humphrey G.
Published: July 2016

Sadly, recent events continue to keep this subject to the fore — and memories of Dawsons Field, Entebbe, Mogadishu, Stansted, Beirut and Malta, to mention but a few of the most dramatic hijack incidents, are recalled, as are other events such as those of the early morning of 23rd June 1985 when one Boeing 747 of Air India was blown up in mid-air off the West Coast of Ireland, killing all 329 on board, with chance preventing the simultaneous destruction of another at Tokyo.

The seriousness of such incidents has, in recent months, grown from the mere appalling and tragic but occasional incident to one of major world importance having substantial effect on world peace and economic survival. The fact that this is no exaggeration is shown by the bombing raid carried out by the USA on Libya in April 1986, in retaliation for that country’s alleged involvement in or support of international terrorism. The subsequent reported mass cancellation of travel to Europe by Americans with consequential serious commercial implications not only for the airlines operating on the North Atlantic, where, for instance, British Airways reported a 25% drop in passenger traffic, is but one example of the effect of terrorism on the stability of world trade.
Aerospace Research and its Relationship to Universities, Industry and the Establishments
Authors: Tokaty G. A.
Published: July 2016

It would not, perhaps, be an exaggeration to say that aeronautics and space technology represent the most dynamic, progressive and exciting field of modern knowledge, where many bold dreams of yesterday are rapidly becoming the spectacular realities of today and tomorrow. Never before, and in no other field, has man learned so much and so profoundly in such a short space of time as he has here during the past ten years or so. This explosion of aerospace knowledge has brought forward and established new dimensions and criteria of national defence, international relations, military strategy, socio-political thought, economics, commerce, etc, and affects everyone’s life in one way or another.
The Momentum Equation for a Static Hovercraft at Zero Incidence
Authors: Fraser S. M.
Published: July 2016

The technical note by Dr. Alexander implies that hovercraft jet performance might be better than simple theory predicts for values of 1/x greater than 4. The experimental points used to compare with theory were obtained at the beginning of hovercraft development, but subsequently a number of British and American reports have been issued whose data can be interpreted to give points for comparison with theory. These results show that the simple theory overestimates the performance of the jet.
Plane Turbulent Free Jet and Wall Jet
Authors: Rajaratnam N. , Subramanya K.
Published: July 2016

The aim of this note is to compare the plane turbulent free jet diffusing in an infinite stagnant ambient environment with the corresponding plane turbulent wall jet on a smooth boundary regarding the three important characteristics, namely the velocity distribution and the variation of the velocity and length scales, in the region of developed flow.
Measurements of Entrainment on a Rotating Disc
Authors: Cham T. S. , Head M. R.
Published: July 2016

In an earlier note Case reported direct measurements of entrainment on a rotating disc. More comprehensive measurements, made subsequently to those of Case and using essentially the same technique, are reported here. Two different sizes of drum were used in the present investigation, the flow within the drum in each case being smoothed by the use of a honeycomb and screens as well as a baffle at entry (see Fig. 1).

The entrainment was also deduced from yawmeter and total pressure traverses through the boundary layer on the disc in free air, the integrated crossflow component of the velocity distribution through the layer evidently representing the entrainment up to the radius at which the traverses were performed. A typical measured crossflow profile is shown in Fig. 2.
Hole Size Effect on Hemisphere Pressure Distributions
Authors: Morrison D. F. , Sheppard L. M. , Williams M. J.
Published: July 2016

During 1961 preliminary consideration was given by the Weapons Research Establishment to the possibility of measuring the structure of the upper atmosphere by pressure probes on sounding rockets. A similar technique had been used with success in the USA. It was proposed that velocity be measured and that an incidence meter be used to measure pitot and static pressures, from which atmospheric pressure and density could be calculated. There was available at the time comprehensive calibration information on hemispherical-headed incidence meters at Mach numbers below 3. Since the sounding rocket would be flying within the Mach number range 3 to 6 there was a need to extend the existing calibrations to higher Mach numbers. At first it seemed that the results of Baer would do this, but a closer examination showed that his results did not agree with the incidence meter calibrations.
The Value of Non-Destructive Testing in the Aircraft Industry
Authors: Troughton A. J.
Published: July 2016

Before detailing the value of non-destructive testing in the aircraft industry, it seems best to explain aircraft structural design philosophies as they affect NDT.

Airworthiness and weight-saving are two over-riding factors in aircraft design. The important parameter from an economic standpoint is the weight. Fig. 1 shows the value of weight saving for a civil aircraft operator in £ per lb with typical values going up to £100 per lb per aircraft per year. (This figure shows the actual financial saving associated with the reduction in operating economics due to the lower weight.) But the vulnerability of an aeroplane in any failure case makes safety a paramount consideration. To save weight, design factors on aircraft are very low.
The Effects on Wing Lift and Pitching Moment Due to the Fin of an Aircraft Flying at Supersonic Speeds
Authors: Jones L. B.
Published: July 2016

A simple expression is obtained for the lift induced upon a wing by the pressure field of the fin mounted upon the wing in supersonic flow. This expression holds for all fins with sharp edges provided that the wing trailing edge is normal to the free stream and that the Mach lines from the apex of the fin do not intersect the wing leading edge. If the fin has a blunt trailing edge the further restriction that the wing trailing edge is upstream of that of the fin is also required.

Results for the induced lift and pitching moment are presented for a delta fin with variations in size and position of the fin relative to the wing trailing edge.
Structural Trends in the Development of Man Powered Aircraft
Authors: Czerwinski W.
Published: July 2016

In the past few years, man powered flight has become a reality. The remarkable achievements in England by the Hatfield Man Powered Flight Group prove that man may take off and fly with his own muscle power without external aid.

Such a possibility seemed very remote to the early pioneers of man powered flight in the late thirties in Germany and Italy. Even after the Second World War, some of the designers of these pre-war aircraft still believed that the take-off of a man powered aircraft would never be possible without some outside assistance.
The Magnification of Roughness Drag by Pressure Gradients
Authors: Nash J. F. , Bradshaw P.
Published: July 2016

A simplified analysis indicates that the increase in profile drag of an aerofoil due to an isolated roughness element is, in general, different from the drag of the element measured on a flat plate with the same free-stream velocity. This “magnification” effect is caused chiefly by the effect of the pressure gradients on the boundary layer downstream of the roughness element.

The degree of magnification is not closely approximated by the ratio of local to free-stream dynamic pressure and, in many typical cases, the contribution to the drag due to roughness elements may be seriously under-estimated in this way.

Measurements of the effect of the initial boundary-layer thickness on the subsequent development of a turbulent boundary-layer in an adverse pressure gradient support the theoretical conclusions.
A Mixing Theory for the Hovering of Peripheral-Jet Air Cushion Vehicles
Authors: Bradbury L. J. S.
Published: July 2016

Recently Alexander suggested modifications to the inviscid theory of Stanton Jones for improving the agreement between theory and experiment on the cushion pressure of hovercraft. However, these simple inviscid theories can hardly be expected to represent even approximately the behaviour of peripheral jets in hovercraft and a more plausible theory taking mixing into account can easily be developed from some work of Bourque and Newman on the re-attachment of plane jets to adjacent surfaces. This theory, which is somewhat similar to a theory of Chaplin, can be used to predict the behaviour of peripheral jet models both in and out of ground effect but it is the intention here simply to compare the predictions of the mixing theory in ground effect with the simple inviscid theories which seem so commonly used in cushion craft work. Also, the advantages and potential of the mixing theory will be discussed briefly.
STOL—Some Possibilities and Limitations
Authors: Mair W. A.
Published: July 2016

The Ninth Lanchester Memorial Lecture was given by Professor W. A. Mair, MA, FRAeS, on “STOL—Some Possibilities and Limitations” in the Society's Lecture Theatre on 12th May 1966. The Chair was taken by the President, Mr. A. D. Baxter, MEng, CEng, FRAeS. Before the lecture he presented the Society's Gold Medal for 1965 to Professor M. J. Lighthill, DSc, FRS, FRAeS, for “his outstanding original work in many fields of Aeronautics”, explaining that Professor Lighthill had been unable to be present at the Wilbur and Orville Wright Memorial Lecture in December 1965 when the Society's main awards for the year were presented.

The President then said that this was the first meeting of the Society since his installation as President and it was a very pleasant way to start his year in office with first, the presentation of the Gold Medal to one distinguished scientist and second, the introduction of another as the Lanchester Memorial Lecturer.

There would be many members of the Society who would remember Dr. Lanchester, his attendance at lectures and his contributions to the discussions. It was true, however, that the real stature of such men was rarely recognised at close quarters and often only in the light of later developments was the importance of their work realised. It was 20 years since Dr. Lanchester's death and their Memorial Lecture was in its ninth year. Each year, each President had added a tribute to this great man. He was a man of many parts—a scientist, musician, poet and engineer and aeronautics owed much to him. It was fitting that the Lecture had established a tradition of surveying some field of research associated with aerodynamics, in which Lanchester was so eminent. He thought that Lanchester would approve of both the subjects discussed and the distinguished men who had honoured his memory by presenting them. Before introducing Professor Mair he wished to welcome Mrs. Lanchester and Mr. George Lanchester and his wife, and Mrs. Mair.

Professor Mair must be well known to most of them. After graduating in Mechanical Sciences at Cambridge in 1939 he had joined the Royal Aircraft Establishment at Farnborough, where he scent some six years in the Aerodynamics Department doing research on high subsonic speed, both in the wind tunnels and in full-scale flight. In 1946 he had gone to the University of Manchester as Director of the Fluid Motion Laboratory and since 1952 he had held the Francis Mond Chair of Aeronautical Engineering at Cambridge. His chief interest there had been mainly in low speed aerodynamics and his authority in that field was widely recognised. In 1963 he had been appointed Chairman of the Powered Lift Committee of the Aeronautical Research Council.
The U.K. Polaris Project
Authors: Shepherd C. W. H.
Published: July 2016

I am very happy to have this opportunity to tell you about Polaris, which has had such a tremendous impact on the world situation. It will be appreciated that I cannot divulge anything of a classified nature, and that this places great restriction on what I can say. Nevertheless, I hope that what I can say will be of interest; it will be slanted towards the weapon aspects, as this is my prime responsibility.

I will start with some background information on how our programme started and the special measures we found necessary to stand a chance of getting our task completed in the timescale.
Propulsion Controls on the Concorde
Authors: Young Pierre
Published: July 2016

One of the novel problems presented by supersonic transports is the control of the complex powerplants needed to achieve optimum efficiency over a very wide range of forward speeds.

The subject is a large one and its proper understanding involves the disciplines of aerodynamics, thermodynamics, servo-theory and finally human engineering, because its end product is a set of knobs, levers, lights and dials which must be usable by the flight crew.

This paper is intended as an elementary introduction, using the special case of the Concorde as a basis. First, an attempt is made to give the aerodynamic and thermodynamic reasons for the large number of powerplant variables which the control systems must manipulate. On this basis, a functional specification of the control systems is established and, finally, the crew's job of propulsion management is described step-by-step in the course of a typical mission.
Development and Future Potential of Maraging Steels
Authors: Haynes A. G.
Published: July 2016

Conventional low-alloy steels at strengths above 100 ton/in2 have been successfully used in various aerospace applications, but laboratory test results, service-performance data and problems in production indicated a need for steels which possessed improved mechanical properties, and which were simpler to machine and fabricate. The 18% Ni-Co-Mo maraging steels were developed in 1961 with the aim of fulfilling this need, and since that date several thousand tons of the steels have been produced and used in all common shapes and forms. In comparison with low-alloy steels of equivalent strength, 18% nickel maraging steels have greater resistance to fracture at highly-stressed notches, defects or cracks, and their susceptibility to hydrogen embrittlement/stress-corrosion failure is generally far superior. The un-notched rotating bend fatigue properties of machined and mar aged specimens of 18% Ni-Co-Mo maraging steels tend to be superior in the low-cycle range and similar in the low-stress range to the properties of low-alloy steels of comparable strength. The fatigue properties of unnotched, in contrast to those of notched, specimens are affected by heat-treatment/machining procedure. Experience gained in production of components has proved that the 18% nickel maraging steels are extremely simple to heat treat, to machine, to cold form and to weld. Exploitation of these advantages can frequently offset the higher initial cost of maraging steel. For example, an analysis of production costs for a complex aircraft component has demonstrated that the use of maraging steel enabled the component to be made by forging and machining at 5-20% lower cost than with a conventional low-alloy steel, despite the fact that initial material costs were five times greater. 18% Ni-Co-Mo maraging steels retain high strength at temperatures up to 350-400°C, and have given good service in short-duration heating cycles at much higher temperatures. Maraging steels may be surface hardened by various methods, and gears and dies treated by simultaneous nitriding and maraging have given excellent performance.

The tremendous technological efforts which have been made in the past five years have yielded the majority of data and experience necessary to ensure successful use of the 18% Ni-Co-Mo maraging steels in the aerospace industry.
A New Approach to Airline Economics The Vehicle Millemile (VMM)
Authors: Willis R. W. E.
Published: July 2016

A Vehicle Millemile is a 1000-mile unit of flight production. A big jet may cost in total £1500 to fly 1000 statute miles or 1 VMM.

If 6 tons of passengers (or 60 passengers and their free baggage) earn £200/Paxton Ton-Millemile x 6=£1200, and the revenue from 3 tons of cargo is £100/Load Ton-Millemile x 3=£300, it is simple economics to see that this “mix” will provide breakeven with 9 tons load on board and a total revenue mix of £1200 + £300=£1500/VMM or per 1000 miles. A big jet flying 1600 VMMs per annum at £1500/VMM costs £2.4m and the above passenger and cargo ton factors would provide sufficient revenue to break even.

In a few seconds, therefore, we have ascertained the composite “mix” of load and revenue needed to meet the cost of flying the aircraft 1000 miles, and the answers are far more enlightening than saying that an average 60 passengers are carried at 4.8 d/PM and 2721 kg of cargo are carried at 24 d/LTM.

The fact that many medium size or small airlines have route stagelengths of less than one Vehicle Millemile at 500 miles or 200 miles makes no difference to the validity of ease of application of VMM Economics, but its great value Jies in the study of intercontinental big jet operations, SST analysis, sub-orbital flight and even interplanetary flight costing.