bluuebunny/crossref_metadata_2025 huggingface dataset:
Conducting sparse feature selection on arbitrarily long phrases in text corpora with a focus on interpretability
Authors: Miratrix Luke , Ackerman Robin
Published: July 2016

We propose a general framework for topic‐specific summarization of large text corpora, and illustrate how it can be used for analysis in two quite different contexts: an Occupational Safety and Health Administration (OSHA) database of fatality and catastrophe reports (to facilitate surveillance for patterns in circumstances leading to injury or death), and legal decisions on workers' compensation claims (to explore relevant case law). Our summarization framework, built on sparse classification methods, is a compromise between simple word frequency‐based methods currently in wide use, and more heavyweight, model‐intensive methods such as latent Dirichlet allocation (LDA). For a particular topic of interest (e.g., mental health disability, or carbon monoxide exposure), we regress a labeling of documents onto the high‐dimensional counts of all the other words and phrases in the documents. The resulting small set of phrases found as predictive are then harvested as the summary. Using a branch‐and‐bound approach, this method can incorporate phrases of arbitrary length, which allows for potentially rich summarization. We discuss how focus on the purpose of the summaries can inform choices of tuning parameters and model constraints. We evaluate this tool by comparing the computational time and summary statistics of the resulting word lists to three other methods in the literature. We also present a new R package,textreg. Overall, we argue that sparse methods have much to offer in text analysis and is a branch of research that should be considered further in this context. © 2016 Wiley Periodicals, Inc. Statistical Analysis and Data Mining: The ASA Data Science Journal, 2016
Wide‐Range Strain Sensors Based on Highly Transparent and Supremely Stretchable Graphene/Ag‐Nanowires Hybrid Structures
Authors: Li Qi , Ullah Zaka , Li Weiwei , Guo Yufen , Xu Jianbao , Wang Rubing , Zeng Qi , Chen Mingliang , Liu Chaojun , Liu Liwei
Published: July 2016

The increasing demand of electronic devices for physical motion detection has encouraged the development of highly elastic strain sensors. Especially, to capture wide‐range physical movements, supremely stretchable and wide‐range strain sensors are required. Here, a novel transparent, bendable, stretchable, and wide‐range strain sensor based on a sandwich‐like stacked graphene and Ag‐nanowires hybrid structures is reported. The hybrid structures on 200% pre‐stretched polyacrylate (PAC) are patterned which possess good bendability up to 2 mm radius, impressive stretchability up to 200% and comparatively low sheet resistance ≈200 Ω sq–1 with transparency 85%. Pre‐stretched PAC technique enables the sensor to work well at extremely high strains and to sense the multidirectional strains efficiently. The Ag‐nanowires pattern on PAC is fabricated via the bubble‐template method, by which a uniform distribution of Ag‐nanowires is achieved with significant connectivity throughout the surface. This not only decreases the power consumption but also enhances the sensitivity of the strain sensor. The demonstrated strain sensor is capable to sense strains between 5% and 200%, and the response time for this sensation is <1 ms.
Odyssey in Polyphasic Catalysis by Metal Nanoparticles
Authors: Denicourt‐Nowicki Audrey , Roucoux Alain
Published: July 2016

Nanometer‐sized metal particles constitute an unavoidable family of catalysts, combining the advantages of molecular complexes in regards to their catalytic performances and the ones of heterogeneous systems in terms of easy recycling. As part of this research, our group aims at designing well‐defined metal nanoparticles based‐catalysts, in non‐conventional media (ionic liquids or water), for various catalytic applications (hydrogenation, dehalogenation, carbon‐carbon coupling, asymmetric catalysis) in mild reaction conditions. In the drive towards a more eco‐responsible chemistry, the main focuses rely on the search of highly active and selective nanocatalysts, in association with an efficient recycling mainly under pure biphasic liquid‐liquid conditions. In this Personal Account, we proposed our almost fifteen‐years odyssey in the world of metal nanoparticles for a sustainable catalysis.

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Visual sign phonology: insights into human reading and language from a natural soundless phonology
Authors: Petitto L. A. , Langdon C. , Stone A. , Andriola D. , Kartheiser G. , Cochran C.
Published: July 2016

Among the most prevailing assumptions in science and society about the human reading process is that sound and sound‐based phonology are critical to young readers. The child's sound‐to‐letter decoding is viewed as universal and vital to deriving meaning from print. We offer a different view. The crucial link for early reading success is not between segmental sounds and print. Instead the human brain's capacity to segment, categorize, and discern linguistic patterning makes possible the capacity to segment all languages. This biological process includes the segmentation of languages on the hands in signed languages. Exposure to natural sign language in early life equally affords the child's discovery of silent segmental units in visual sign phonology (VSP) that can also facilitate segmental decoding of print. We consider powerful biological evidence about the brain, how it builds sound and sign phonology, and why sound and sign phonology are equally important in language learning and reading. We offer a testable theoretical account, reading model, and predictions about how VSP can facilitate segmentation and mapping between print and meaning. We explain how VSP can be a powerful facilitator of all children's reading success (deaf and hearing)—an account with profound transformative impact on learning to read in deaf children with different language backgrounds. The existence of VSP has important implications for understanding core properties of all human language and reading, challenges assumptions about language and reading as being tied to sound, and provides novel insight into a remarkable biological equivalence in signed and spoken languages. WIREs Cogn Sci 2016, 7:366‐381. doi: 10.1002/wcs.1404

This article is categorized under:

Psychology > Language
Clinicopathological Features of Ganglioneuroma Originating From the Adrenal Glands
Authors: Lee Joon‐Hyop , Chai Young Jun , Kim Tae‐Hyung , Choi June Young , Lee Kyu Eun , Kim Hyun‐Young , Yoon Yoo‐Seok , Kim Hyeon Hoe
Published: July 2016

Background

Ganglioneuromas are benign tumors that rarely develop from adrenal glands. In this study, we present our clinical experience of patients with adrenal ganglioneuroma (AGN).

Methods

Demographic, diagnostic, surgical, and pathologic findings of patients who were adrenalectomized as a result of AGN were retrospectively reviewed from the database of a tertiary referral hospital.

Results

Among 1784 patients who underwent an adrenalectomy between 2002 and 2015, 35 (1.9 %; 14 males, 21 females) were diagnosed with AGN. Mean age was 33.4 ± 18.7 years (0–84). Twenty‐nine (82.9 %) were asymptomatic, four (11.4 %) complained of abdominal discomfort, and two (5.7 %) had abdominal distension. Preoperative computed tomography (CT) reported AGN in 22 (62.9 %) cases. Precontrast Hounsfield units, increased postcontrast phase attenuation, and well‐defined borders were characteristic CT features of AGN. Mean tumor size was 6.3 ± 3.3 cm (range, 1.5–16.0). No recurrence occurred during a median follow‐up period of 19 months (range, 1–120).

Conclusion

AGN was asymptomatic in most cases and diagnosis may be challenging. Adrenalectomy is a safe treatment modality for AGN and ensures favorable outcomes when diagnosed.
Compliance of Clinical Pathways in Elective Laparoscopic Cholecystectomy: Evaluation of Different Implementation Methods
Authors: Holderried Martin , Hummel Rebecca , Falch Claudius , Kirschniak Andreas , Koenigsrainer Alfred , Ernst Christian , Muller Sven
Published: July 2016

Background

Clinical pathways aim to standardize perioperative and postoperative care of surgical procedures and are shown to result in a significant optimization associated with cost reduction. The aim of this study was to establish the impact of two different implementations forms of clinical pathways on the pathway compliance and resulting costs.

Methods

Data of patients undergoing elective cholecystectomy for symptomatic cholecystolithiasis were collected over two different periods: using a clinical pathway in the form of a paper‐based checklist, or a clinical pathway integrated into the paper‐based medical treatment and nursing documentation. Outcome measures were compliance of the clinical pathway and total costs per case.

Results

The compliance was significantly higher using integrated pathways compared to paper‐based checklists (n = 117 of 123, 95 % vs 54 of 118, 46 %; p < 0.001). Mean total costs (€2206 vs €2458, p = 0.027) and length of hospital stay (2.13 vs 2.77 days, p < 0.001) were significantly reduced by the integrated clinical pathway compared to checklists. Further, the variation of costs per case and variation of length of hospital stay were significantly smaller with integrated clinical pathway (±€440 vs ±€538, p = 0.039 and ±0.53 vs ±0.68 days, p < 0.001, respectively). No difference regarding postoperative complication was observed (n = 3 vs. 4 events; p = 0.67).

Conclusion

Integrated clinical pathways display a significant higher compliance compared to checklists resulting in reduced total costs, shorter hospital stay and a smaller variation of cost, making it a useful tool in process controlling and planning.
Teamwork of clinical teachers in postgraduate medical training
Authors: Slootweg Irene Arida
Published: July 2016

Teamwork among clinical teachers is essential for continuous improvement of postgraduate medical training. This thesis deconstructs teamwork in four studies, mostly based on qualitative research approaches and one study utilizes mixed methods. We found that clinical teachers do train residents, but individually rather than as a team. The programme directors as leaders focus more on teaching activities than on the collective ambition and mutual engagement of clinical teachers. During the teaching meetings, mistakes and conflicts are mainly discussed in a general sense and are often neither directed at the individual, nor result-oriented. A valid evaluation instrument is constructed to improve teamwork.
Levels of tau protein in plasma are associated with neurodegeneration and cognitive function in a population‐based elderly cohort
Authors: Dage Jeffrey L. , Wennberg Alexandra M.V. , Airey David C. , Hagen Clinton E. , Knopman David S. , Machulda Mary M. , Roberts Rosebud O. , Jack Clifford R. , Petersen Ronald C. , Mielke Michelle M.
Published: July 2016

Introduction

Tau protein levels in plasma may be a marker of neuronal damage. We examined associations between plasma tau levels and Alzheimer's disease (AD)–related magnetic resonance imaging (MRI) and positron emission tomography (PET) neuroimaging measures among nondemented individuals.

Methods

Participants included 378 cognitively normal (CN) and 161 mild cognitive impairment (MCI) individuals enrolled in the Mayo Clinic Study of Aging with concurrent neuropsychological measures and amyloid PET, fluorodeoxyglucose PET, and MRI. Baseline plasma tau levels were measured using the Quanterix Simoa‐HD1 tau assay.

Results

Plasma tau levels were higher in MCI compared with CN (4.34 vs. 4.14 pg/mL, P = .078). In regression models adjusted for age, gender, education, and APOE, higher plasma tau was associated with worse memory performance (b = −0.30, P = .02) and abnormal cortical thickness in an AD signature region (odds ratio = 1.80, P = .018).

Discussion

Plasma tau is associated with cortical thickness and memory performance. Longitudinal studies will better elucidate the associations between plasma tau, neurodegeneration, and cognition.
Medical Management of Parkinson’s Disease after Initiation of Deep Brain Stimulation
Authors: Fasano Alfonso , Appel-Cresswell Silke , Jog Mandar , Zurowkski Mateusz , Duff-Canning Sarah , Cohn Melanie , Picillo Marina , Honey Christopher R. , Panisset Michel , Munhoz Renato Puppi
Published: July 2016

In this review, we have gathered all the available evidence to guide medication management after deep brain stimulation (DBS) in Parkinson’s disease (PD). Surprisingly, we found that almost no study addressed drug-based management in the postoperative period. Dopaminergic medications are usually reduced, but whether the levodopa or dopamine agonist is to be reduced is left to the personal preference of the treating physician. We have summarized the pros and cons of both approaches. No study on the management of cognitive problems after DBS has been done, and only a few studies have explored the pharmacological management of such DBS-resistant symptoms as voice (amantadine), balance (donepezil) or gait disorders (amantadine, methylphenidate). As for the psychiatric problems so frequently reported in PD patients, researchers have directed their attention to the complex interplay between stimulation and reduction of dopaminergic drugs only recently. In conclusion, studies addressing medical management following DBS are still needed and will certainly contribute to the ultimate success of DBS procedures.
Sustainable Development of Human Resources Inspired by Chinese Philosophies: A Repositioning Based on François Jullien's Works
Authors: Persson Sybille , Shrivastava Paul
Published: July 2016

This paper provides a philosophical repositioning of human resource management (HRM) to further sustainable human resources development (HRD). We use a conceptual process, based on the work of French philosopher and Sinologist François Jullien. Despite its growing and diversified academic production, HRM research has become increasingly isolated from practice, from alternative views of human life, and from nature. This is at least partly due to its failure to self-question its Western centric roots. This paper describes some key conceptual innovations that deal with efficacy and ‘vital nourishment’ which are of particular interest for sustainable HRD. The question of how to feed life (or nourish it) in the workplace is illustrated by a gardening metaphor for managing human potential. In contrast to cross-cultural studies, this metaphor emerges from a dialogue between Western and Eastern philosophies, and offers alternative approaches to HRD based on some core insights from the Chinese tradition.
Factors Influencing the Radiocarbon Dating of Human Skeletal Remains from the Dnieper River System: Archaeological and Stable Isotope Evidence of Diet from the Epipaleolithic to Eneolithic Periods
Authors: Lillie Malcolm , Henderson Rowena , Budd Chelsea , Potekhina Inna
Published: July 2016

Recent research has identified the existence of a freshwater reservoir effect influencing the radiocarbon dating of human skeletal remains from the Dnieper region of Ukraine (Lillie et al. 2009). The current study outlines the evidence for freshwater resource exploitation throughout the period ~10,200–3700 cal BC, and presents the available evidence for the existence of dietary offsets in the14C dates obtained. We have obtained human skeletal material from 54 Epipaleolithic to Mesolithic period individuals and 267 Neolithic to Eneolithic individuals, from 13 cemeteries, since our research in Ukraine began in 1992. Here, we present the initial results of stable isotope analysis of Eneolithic individuals from the Igren VIII cemetery alongside the Epipaleolithic to Eneolithic samples that have previously been analyzed. When contrasted against the evidence from the prehistoric fauna and fish remains studied, and modern fish species from the Dnieper region, we continue to see variability in diets at the population level, both internally and across cemeteries. We also observed temporal variability in human diets across these chronological periods. The fish samples (both archaeological and modern) show a wide range of isotope ratios for both δ13C and δ15N, which could prove significant when interpreting the dietary sources being exploited. This information directly informs the14C dating program as an inherent degree of complexity is introduced into the dating of individuals whose diets combine freshwater and terrestrial sources in differing quantities and at differing temporal and/or spatial scales (e.g. Bronk Ramsey et al. 2014).
Convolutions of heavy-tailed random variables and applications to portfolio diversification and MA(1) time series
Authors: Geluk Jaap L. , Peng Liang , de Vries Casper G.
Published: July 2016

Suppose X1,X2 are independent random variables satisfying a second-order regular variation condition on the tail-sum and a balance condition on the tails. In this paper we give a description of the asymptotic behaviour as t → ∞ for P(X1 + X2 > t). The result is applied to the problem of risk diversification in portfolio analysis and to the estimation of the parameter in a MA(1) model.
On the mean normal measures of a particle process
Authors: Schneider Rolf
Published: July 2016

The (unoriented or oriented) mean normal measure of a stationary process of convex particles carries information on the mean shape of the particles and may, in particular, be useful for describing and detecting anisotropy of the particle process. This paper investigates the mean normal measure under the aspect of its determination from intersections, especially with lines or hyperplanes.
Restarting search algorithms with applications to simulated annealing
Authors: Mendivil F. , Shonkwiler R. , Spruill M. C.
Published: July 2016

Some consequences of restarting stochastic search algorithms are studied. It is shown under reasonable conditions that restarting when certain patterns occur yields probabilities that the goal state has not been found by thenth epoch which converge to zero at least geometrically fast inn. These conditions are shown to hold for restarted simulated annealing employing a local generation matrix, a cooling scheduleTn∼c/nand restarting after a fixed numberr+ 1 of duplications of energy levels of states whenris sufficiently large. For simulated annealing with logarithmic cooling these probabilities cannot decrease to zero this fast. Numerical comparisons between restarted simulated annealing and several modern variations on simulated annealing are also presented and in all cases the former performs better.
Locating Fréchet means with application to shape spaces
Authors: Le Huiling
Published: July 2016

We use Jacobi field arguments and the contraction mapping theorem to locate Fréchet means of a class of probability measures on locally symmetric Riemannian manifolds with non-negative sectional curvatures. This leads, in particular, to a method for estimating Fréchet mean shapes, with respect to the distance functionρdetermined by the induced Riemannian metric, of a class of probability measures on Kendall's shape spaces. We then combine this with the technique of ‘horizontally lifting’ to the pre-shape spheres to obtain an algorithm for finding Fréchet mean shapes, with respect toρ, of a class of probability measures on Kendall's shape spaces in terms of the vertices of random shapes. This gives us, for example, an algorithm for finding Fréchet mean shapes of samples of configurations on the plane which is expressed directly in terms of the vertices.
Exact sampling from conditional Boolean models with applications to maximum likelihood inference
Authors: van Lieshout M. N. M. , van Zwet E. W.
Published: July 2016

We are interested in estimating the intensity parameter of a Boolean model of discs (the bombing model) from a single realization. To do so, we derive the conditional distribution of the points (germs) of the underlying Poisson process. We demonstrate how to apply coupling from the past to generate samples from this distribution, and use the samples thus obtained to approximate the maximum likelihood estimator of the intensity. We discuss and compare two methods: one based on a Monte Carlo approximation of the likelihood function, the other a stochastic version of the EM algorithm.
Upper bounds for the probability of a union by multitrees
Authors: Bukszár József
Published: July 2016

The problem of finding bounds for P(A1∪ ⋯ ∪An) based on P(Ak1∩ ⋯ ∩Aki) (1 ≤k1< ⋯ <ki≤n,i= 1,…,d) goes back to Boole (1854), (1868) and Bonferroni (1937). In this paper upper bounds are presented using methods in graph theory. The main theorem is a common generalization of the earlier results of Hunter, Worsley and recent results of Prékopa and the author. Algorithms are given to compute bounds. Examples for bounding values of multivariate normal distribution functions are presented.
A computational approach to first-passage-time problems for Gauss–Markov processes
Authors: Di Nardo E. , Nobile A. G. , Pirozzi E. , Ricciardi L. M.
Published: July 2016

A new computationally simple, speedy and accurate method is proposed to construct first-passage-time probability density functions for Gauss–Markov processes through time-dependent boundaries, both for fixed and for random initial states. Some applications to Brownian motion and to the Brownian bridge are then provided together with a comparison with some computational results by Durbin and by Daniels. Various closed-form results are also obtained for classes of boundaries that are intimately related to certain symmetries of the processes considered.
Optimal stopping rules for directionally reinforced processes
Authors: Allaart Pieter , Monticino Michael
Published: July 2016

This paper analyzes optimal single and multiple stopping rules for a class of correlated random walks that provides an elementary model for processes exhibiting momentum or directional reinforcement behavior. Explicit descriptions of optimal stopping rules are given in several interesting special cases with and without transaction costs. Numerical examples are presented comparing optimal strategies to simpler buy and hold strategies.
The stochastic equation Yn

+1=AnYn + Bn
with stationary coefficients
Authors: Brandt Andreas
Published: July 2016

In this note we deal with the stochastic difference equation of the form Y

n+1 = AnYn
+ Bn
, n∊ℤ, where the sequence is assumed to be strictly stationary and ergodic. By means of simple arguments a unique stationary solution of this equation is constructed. The stability of the stationary solution is the second subject of investigation. It is shown that under some additional assumptions
Stochastic hydrology-how much hydrology does it contain and how much does it matter?
Authors: Klemeš V.
Published: July 2016

Most of what is routinely labeled ‘stochastic hydrology’ does not contain any hydrology at all and could be more properly identified as the fitting of stochastic models to samples of data of hydrologic origin. T0 engage in this enterprise, no hydrologic knowledge is necessary, nor do the results contribute to hydrologic knowledge. Moreover, the bulk of the current stochastic hydrology does not appreciably enhance the quality of water management decisions-an aim which provided the original impetus for its development. It seems that the mainstream of stochastic hydrology follows in the steps of ‘dam theory’, the only difference being that while the latter has become a self-contained branch of pure probability theory, the former is on the way to becoming a branch of pure mathematical statistics.
Topics in stochastic point processes, by applications in hydrology
Authors: Todorovic P.
Published: July 2016

The strong impetus for the research in the theory of point processes comes from applications, real or potential, to a multitude of engineering, industrial and biological problems. Here we discuss some particular topics in this area and their applications in hydrology. Specifically, we consider stochastic models of a variety of geophysical phenomena, such as the rainfall, floods, sediment transport, dispersion in porous media and some others. The first part of this presentation is concerned with point processses on R+. Our discussion includes the stochastic intensity, some remarks on the martingale approach and a brief expose of the elements of renewal theory. In addition, we discuss in some detail the case when the counting random function represents a Markov process. In the second part we give an introduction to the theory of point processes on an abstract topological space. Elements of marked point processes, which are of particular interest in hydrological investigations, are also included. The rest of the paper is concerned with some hydrological applications.
A model for plant root-length measurement
Authors: Gallot S. F. L.
Published: July 2016

One of the more important parameters in the study of plant growth is the length of the root system.
Networks with random conductivities
Authors: Barndorff-Nielsen Ole E.
Published: July 2016

The study of networks with random conductivities or resistances is of considerable interest in physics, biology, geology and mathematics. The talk concentrated on a rather flexible class of parametric models for trees with random conductivities, based on properties of the inverse Gaussian distribution. For finite trees some exact distributional results were presented and extensions of the models to infinite trees were discussed. Joint work with Gerard Letac and Angelo E. Koudou (Toulouse), extending Barndorff-Nielsen (1994).
On the MLE for a spatial point pattern
Authors: Montes Francisco , Mateu Jorge
Published: July 2016

Parameter estimation for a two-dimensional point pattern is difficult because most of the available stochastic models have intractable likelihoods ([2]). An exception is the class of Gibbs or Markov point processes ([1], [5]), where the likelihood typically forms an exponential family and is given explicitly up to a normalising constant. However, the latter is not known analytically, so parameter estimates must be based on approximations ([3], [6], [7]). In this paper we present comparisons amongst the different techniques available in the literature to obtain an approximation of the maximum likelihood estimate (MLE). Two stochastic methods are specifically illustrated: a Newton-Raphson algorithm ([7]) and the Robbins-Monro procedure ([8]). We use a very simple point process model, the Strauss process ([4]), to test and compare those approximations.
Studies of the flow field near a IMACA 4412 aerofoil at nearly maximum lift
Authors: Hastings R. C. , Williams B. R.
Published: July 2016

Measurements made at a Mach number of 0.18 and a chord-based Reynolds number of 4·2 x 106 on a constant-chord model having a NACA 4412 aerofoil section are described and compared with the results of flow field calculations.

Both the experimental arrangement and the difficulties initially experienced in achieving an adequate approximation to two-dimensional flow above the wing are briefly outlined.

The measurements include static pressure distributions on the wing surface and on the wind-tunnel walls above and below the mid-span section of the wing. The main emphasis in the experiment was, however, on defining the development of the upper surface boundary layer through separation (at about 20% chord ahead of the trailing-edge) and on into the wake, making extensive use of laser anemometry to measure mean velocities. In addition, Reynolds stresses were measured in certain parts of the flow field by hot-wire anemometry.

The flow field calculations are of the semi-inverse kind in which an inverse momentum-integral treatment of the shear flow, used to avoid difficulties at separation, is coupled to a direct solution of the inviscid flow problem. The main features of the method are outlined.
Design features which influence flow separations on aircraft
Authors: Mabey D. G.
Published: July 2016

Features of aircraft which influence flow separations, and hence the onset of buffeting, should be always of interest to an aerodynamicist. The present compilation of such features is based on notes made during a visit to the USAF Aircraft Museum in Dayton, Ohio. Although two low-speed aircraft with high aspect ratio wings are considered, the emphasis is primarily on transonic and supersonic military aircraft, with wings of lower aspect ratio.

Some recommendations are made to stimulate research into improved methods to control flow separation, particularly for future transonic and supersonic aircraft.
Large deflections of a spring-hinged tapered cantilever beam with a rotational distributed loading
Authors: Nageswara Rao B. , Venkateswara Rao G.
Published: July 2016

Large deflection problem of a spring loaded hinged nonuniform cantilever beam subjected to a rotational distributed loading is formulated by means of a second-order non-linear integro-differential equation. The problem is examined by considering the beam of rectangular cross-section with linear depth taper subjected to a uniform rotational distributed load. The elastic curves of a beam for this special case are presented.
The reliability of inspection techniques in relation to damage tolerant design
Authors: Stone D. E. W.
Published: July 2016

This paper is concerned especially with the reliability of inspection in the nondestructive testing of military aircraft structures. The first part considers design philosophies, examines how the requirements for inspection arise and highlights the difference between the approaches being adopted in the USA and in the UK.

The second part examines what data are already available on the reliability of inspection and discusses the UK programmes that are aimed at gathering more data.
The reliability concept as an aid to decision making in offshore engineering
Authors: Baker M. J.
Published: July 2016

Uncertainties exist at practically all stages of the design and construction process because of incomplete knowledge. Extreme environmental forces on offshore structures are uncertain because of the stochastic nature of the underlying physical phenomena. The actual strength and fatigue characteristics of structures can be predicted only approximately at the design stage and these predictions can be refined only partially by compliance tests during and after fabrication, and then only at high cost.
The use and potential use of reliability engineering for offshore structures
Authors: Mowatt G. A. , Loader D. J. , Arbuthnot C. H.
Published: July 2016

This paper presents a review of the current status and potential future use of reliability methods in the design, fabrication and operation of offshore oil production platforms.

An overview of the traditional design process is presented and key areas where reliability methods have contributed to the development of codes of practice are described. Future applications in the design stage include the optimisation of framing configurations and the treatment of uncertainties in basic design parameters.
Premature boundary layer transition caused by surface static pressure tappings
Authors: Roach P. E. , Turner J. T.
Published: July 2016

Experiments have been performed to study the influence of multiple surface static pressure tappings on transition of the boundary layer on a circular cylinder in cross-flow. A wide range of tapping and cylinder dimensions have been examined to demonstrate that the tappings can act in the same way as trip wires or other surface roughness to reduce the Reynolds number at which transition occurs. Hence, the pressure distribution around the cylinder may be influenced by the presence of the tappings, leading to incorrect measurements. Examination of the data has resulted in a correlation which should make it possible to avoid this tapping/boundary layer interaction in future experiments involving similar cylindrical bodies.
Project Cost Estimating
Authors: Petruschell R. L.
Published: July 2016

Cost estimating is all too frequently thought of as a necessary but dull and uninspiring task better performed by persons who are either incapable of, or uninterested in, wrestling with the important and exciting issues of the day. Even with the current concern for the economic implications of choice, cost estimating is only beginning to be accorded its rightful place in the decision making process. The reasons for this are many, but the most significant is probably a general lack of awareness of the potential benefits that are to be realised. One place where cost estimating has, in recent years, been allowed to play its proper role is in military long-range planning, and the rewards have been great. The general philosophy of the military planner and the concepts and methods of the cost estimator that have permitted this to happen are discussed. In the second part of the paper, an example of a cost analysis in support of a military planning problem is presented. The example points up the fact that cost estimating can be an intellectually stimulating activity worthy of the application of the best analytical skills available, and that it can provide useful answers to difficult and important questions even when uncertainty is great and quantification is difficult. Even though the discussion in ‘this paper is based on a military long-range planning application, the concepts, methods and techniques that have made success possible there, have much more general implications. Believing this, it is is hoped that this paper will serve to further the awareness of many, and stimulate some, to seek out the important benefits to be derived from a less traditional approach to cost estimating.
Precision Hovering by Light Helicopters at Moderate Altitudes
Authors: Clark B. A. , Gross K. A.
Published: July 2016

Using television as an instrumental aid, light helicopters can be hovered with considerable accuracy above a known ground point at altitudes of the order of a thousand metres above ground level. The image from a vertically-aimed ground-based television camera is transmitted to the helicopter and displayed on a receiver placed in front of the pilot, who uses the image of the helicopter for guidance to the hover point. With this system, the hover point has been maintained within ±1.2 m (4 feet) for periods of up to 2.5 minutes at 1200 m (4000 feet) above ground level.
On the Determination of the Dynamic Characteristics of a Vibrating System
Authors: Mahalingam S.
Published: July 2016

The natural frequencies and modes of vibration of a structure may be obtained more or less directly from experiments. The generalised masses and stiffnesses, however, are usually obtained indirectly from experimental investigations of the dynamic behaviour of the system. One of the techniques widely used for this purpose in the aircraft industry is known as the method of displaced frequenciesm.Stated briefly, the method consists of observing the changes in the natural frequencies caused by the addition of one or more small masses to the vibrating system.
Operational Problems of Antarctic Aviation
Authors: Grierson John
Published: July 2016

Polar aviation is a branch of flying to which the domestic British (that is excluding the Canadians) have contributed modestly. Indeed, we do not have the Arctic on our doorstep like the Americans, Canadians, Russians, Finns, Swedes and Norwegians but, in exploration, we have a tradition second to none in Antarctica, a tradition fostered and developed in bygone years so dauntlessly by men of the Royal Navy. In fact it was Captain Robert Falcon Scott who was the first man ever to become airborne in Antarctica, early in January 1902, when he went aloft near Cape Adare in an observation balloon. Admittedly he let go all the ballast at once and shot up to 800 feet so rapidly that only the mooring rope prevented him from making a free-balloon voyage over the ice-bound wastes, and he did not enjoy the experience very much. But it was a pioneering flight. A few months later, the German Drygalski made a similar flight for the purpose of ice observation; but balloons never caught on in the Antarctic and there was no more flying there until Sir Hubert Wilkins’ expedition made the first aeroplane flight, from Deception Island, off Graham Land, with a Lockheed Vega wheeled aeroplane on 16th November 1928.
The Gemini Programme from an Engineering Point of View
Authors: Lindley Robert N.
Published: July 2016

I had the privilege and pleasure of working directly under Roy Chad wick from 1942 until the time of his death in 1947. I use the word “pleasure” advisedly, for he seemed at that time to be the most unreasonable of men. At one moment he would be full of charm and consideration, and at the next a martinet who drove us well beyond what we mistakenly thought to be the limits of human endurance. I well remember standing in Oldham Street on a cold Manchester war-time morning, having missed all reasonable buses to Chadderton, to be picked up by Chadwick in a shiny Armstrong-Siddeley. All the way out to the factory he talked about the good old days of aviation, and the challenge of my chosen profession. At the front door we were welcomed by the commissionaire, and I went to my desk confident that God was in his Heaven and all right with the world. Within ten minutes the telephone—Miss Jackson summoning me to Mr. Chadwick's presence. As I entered his office he scowled at me and started in—“Lindley —you were late this morning ….”.
Tizard and the Aeronautical Research Committee
Authors: Collar A. R.
Published: July 2016

The name of Sir Henry Tizard always induces in me feelings of humility: I have succeeded him in an office to which he lent distinction for ten years, but I can never hope to emulate his drive and efficiency, nor compete with his almost legendary chairmanship. I remember that in 1964, soon after I was appointed to the Chair of the Aeronautical Research Council, Dover Publications decided to reprint Goldstein's “Modern Developments in Fluid Dynamics“, and I was invited to contribute a Preface. I got out my set of the earlier edition, to be reminded that the first Preface bore the signature H. T. Tizard: somehow, it seemed almost indecent that I, or anyone, should have to write a new Preface. Such are my feelings about Tizard's name and fame: I daresay many of my generation feel as I do.
Gliding in New Zealand
Authors: Hookings G. A.
Published: July 2016

I am deeply conscious of the honour to the New Zealand gliding movement and to myself as its representative to be asked to deliver the First George Bolt Aviation Memorial Lecture. George Bolt was one of the first New Zealanders to construct and fly his own glider in the early years of this century, and for the remainder of his life he retained an intense interest in gliding, even when deeply involved in increasingly complex powered aircraft. He agreed to become the first Chairman of the Technical Committee of the New Zealand Gliding Association, and as such helped the movement in its struggles to get back into the air after the Second World War. It is thanks to him that the Association was established on a sound technical basis, as the first post-war Director of Civil Aviation made it clear that the New Zealand Gliding Association would not be recognised until a competent Technical Committee was formed.
Flow Separation in an Aerofoil Cascade
Authors: Clayton B. R. , Massey B. S.
Published: July 2016

The pattern of flow at low Reynolds Numbers about an aerofoil in a cascade has been illustrated by the hydrogen-bubble flow-visualisation technique. The method has also been adapted tor the accurate experimental determination of the position of boundary-layer separation. Results of the investigation are presented graphically together with photographs showing the general behaviour of the flow in the wake.
Pontryagin's Maximum Principle Applied to the Profile of a Beam
Authors: Dixon L. C. W.
Published: July 2016

Every structural member deforms under the forces acting upon it. In this paper the Maximum Principle, recently developed by Pontryagin is applied to the problem of determining that profile of a beam that deforms least under its own weight. The beam considered is a solid horizontal cantilever having constant density, modulus of elasticity and width. The height is taken as an independent variable subject to the restrictions that it lies between an upper and lower bound and is symmetrically distributed about the centre-line. The method is attractive in that it can readily be extended to take account of variable density, width and/or hollow members by extending the control vector u defined in the analysis.
The Influence of Added Narrow Band Noises and Tones on the Subjective Response to Shaped “White” Noise
Authors: Hargest T. J. , Pinker R. A.
Published: July 2016

Experiments on the influence of added narrow band sounds on the subjective assessment of noise were conducted at the NGTE 1966 Open Week and at the 1966 SBAC Show, with over two thousand people participating. The results clarify the apparently conflicting observations of earlier workers and show definitely that the presence of a narrow band content can significantly influence the degree of disturbance caused by noise of the type generated by aircraft near an airport.
A Two-Parameter Method for Calculating the Two-Dimensional Incompressible Laminar Boundary Layer
Authors: Curle N.
Published: July 2016

In most one-parameter methods of calculating laminar boundary layers it is assumed that the non-dimensional parameters H=δ1/δ2, I=δ2τW/μu1 and L = 2{I−λ(H+2)}, depend only upon the pressure gradient parameter λ=u1δ22/v. In this paper it is shown theoretically that a more accurate, two-parameter representation is

L=F0(λ)−μG0(λ)

I2=F1(λ)−μG1(λ),

where μ=λ2U1U1/(U1)2. Careful examination of the available range of exact solutions of the boundary layer equations has enabled the four functions F0, G0, F1, G1, to be tabulated, and the above functional forms agree with the exact solutions to a remarkable accuracy.

In view of the fact that a reasonable first approximation to L is usually , we write

,

and it is then shown that the momentum integral equation becomes

This equation is easily solved by iteration, setting g=0 in the first approximation, and convergence is extremely rapid.

The method is, in effect, a refinement of that due to Thwaites, which is universally accepted as one of the better of the existing calculation methods. Detailed calculations made by the present method indicate that the errors are only 5% of those given by the Thwaites method.
Clamped Skew Plate under Uniform Normal Loading
Authors: Sundara Raja Iyengar K. T. , Srinivasan R. S.
Published: July 2016

In recent years a number of authors have analysed the bending of clamped skew plates under uniform pressure. Many of these solutions are very approximate. Favre and Dorman adopted the Ritz method and their expressions for displacement are restrictive. Based on the generalised method postulated by Lardy, Mirsky has presented a solution which involves considerable algebraic and arithmetic work. Komatsu's paper contains a solution using conformal mapping. Quinlan has given a powerful method to solve skew plate problems involving different boundary conditions and various types of loadings, but no numerical work has been done.
An Assessment of Maraging Steel for Aircraft Applications
Authors: Imrie W. M.
Published: July 2016

Mr. Haynes in his contribution to the Symposium, and also in previously published papers, has very adequately described the general development, advantages and characteristics of the maraging steels. However, as much of the information which he has given relates to the work done in the laboratories of International Nickel, and because we have only been able to find relatively little information available relating to production experience, we at Dowty Rotol set out to investigate the problems of steel making, forging, and resultant mechanical properties to be obtained under more normal production conditions. As landing gear manufacturers, our prime interest lies in the production of relatively large forgings of somewhat complex shape, and we were therefore particularly anxious to investigate first of all that our normal steel suppliers could produce material to the correct composition, that the material would forge as easily as conventional material, and that the subsequent forgings possessed adequate trans-verse properties, particularly insofar as ductility is concerned. In this latter connection, we had heard of certain difficulties encountered in the USA relating to inadequate ductility in large forgings, which they had concluded was related to the carbon and sulphur content of the steel: i.e. that it was essential to eliminate brittle intermetallic compounds such as titanium carbo-nitrides and titanium sulphides from the steel.
The Refractory Metals
Authors: Llewelyn G.
Published: July 2016

The refractory metals are usually referred to as metals which have melting points equal to, or higher than, chromium. A number of these metals, such as chromium, molybdenum, niobium, and tungsten are already being used quite extensively as alloying elements in both ferrous and non-ferrous alloys. Tungsten has been used in the lamp industry for many years, while molybdenum has been used for heating elements and niobium has been of interest in the atomic energy field.

The advancements in design and efficiency of aero engines has been associated with an increase in engine temperature. If this advancement is to continue, it will be necessary for a new family of alloys to be made available to the engineer. The current nickel-base high temperature alloys are now approaching their limit. It is difficult to be precise about these temperatures because the applications in terms of stress vary widely.
Britain's Future in Space
Authors: Caldecote Viscount
Published: July 2016

Captain Frank Barnwell is to be remembered as one of the pioneers of practical aviation. His love of flying inspired him and eventually killed him, for it was in an aircraft of his own design and construction that he eventually met his end; but his record of service to aeronautical design shows that he was much more than a brave and gifted amateur aviator. He was a professional engineer, a realist who foresaw the practical application of aeronautics to useful purpose. In an age when many considered aviation an interesting hobby of little practical importance, Barnwell set himself the task of designing aircraft for practical purposes.
Box Wing Theory
Authors: Lockwood Taylor J.
Published: July 2016

In 1931, several years before the RAE work on box wing theory which was mentioned (in the January Journal), I joined Armstrong Whitworth Aircraft. They were designing the Atalanta monoplane for Imperial Airways, and were in difficulties with the wing stressing, my chief H. A. Francis having, as he said, applied to RAE for advice and “got the bird”. The late J. K. Reid, their leading “methods man”, had already produced the simple exponential theory of uniform box torsion which RAE later re-discovered, but unfortunately, for our tapered thin-skin wing, we soon found out that this did not work.