bluuebunny/crossref_metadata_2025 huggingface dataset:
Associations Between Penetration Cognitions, Genital Pain, and Sexual Well-Being in Women with Provoked Vestibulodynia
Authors: Anderson Alexandra B. , Rosen Natalie O. , Price Lisa , Bergeron Sophie
Published: February 2016

Introduction

Provoked vestibulodynia (PVD) is a common vulvovaginal pain condition that negatively impacts women's psychological and sexual well-being. Controlled studies have found that women with PVD report greater negative and less positive cognitions about penetration; however, associations between these types of cognitions and women's pain and sexual well-being remain unknown. Further, researchers have yet to examine how interpersonal variables such as sexual communication may impact the association between women's penetration cognitions and PVD outcomes.

Aim

We examined associations between vaginal penetration cognitions and sexual satisfaction, sexual function, and pain in women with PVD, as well as the moderating role of sexual communication.

Methods

Seventy-seven women (M age = 28.32, SD = 6.19) diagnosed with PVD completed the catastrophic and pain cognitions and positive cognitions subscales of the Vaginal Penetration Cognition Questionnaire, as well as the Dyadic Sexual Communication Scale. Participants also completed measures of sexual satisfaction, sexual function, and pain.

Main Outcome Measures

Dependent measures were the (i) Global Measure of Sexual Satisfaction Scale; (ii) Female Sexual Function Index; and (iii) Present Pain Intensity scale of the McGill Pain Questionnaire, with reference to pain during vaginal intercourse.

Results

Women's lower catastrophic and pain cognitions, higher positive cognitions, and higher sexual communication were each uniquely associated with higher sexual satisfaction and sexual function. Lower catastrophic and pain cognitions also were associated with women's lower pain. For women who reported higher sexual communication, as positive cognitions increased, there was a significantly greater decrease in pain intensity during intercourse compared to women who reported lower levels of sexual communication.

Conclusion

Findings may inform cognitive-behavioral interventions aimed at improving the pain and sexual well-being of women with PVD. Targeting the couple's sexual communication and women's penetration cognitions may improve women's sexual adjustment and reduce pain.
Nonalcoholic Fatty Liver Disease is Associated with Erectile Dysfunction: A Prospective Pilot Study
Authors: Duman Deniz Güney , Biçakci Ercan , Çelikel Çiğdem Ataizi , Akbal Cem
Published: February 2016

Introduction

Nonalcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome (MetS). Although the link between MetS and erectile dysfunction (ED) is well known, clinical studies investigating the association between NAFLD and ED are scant.

Aim

To evaluate the relationship between NAFLD and ED.

Methods

Male patients with biopsy-proven NAFLD were prospectively asked to fill the five-item International Index of Erectile Function (IIEF-5) questionnaire. Their clinical and histologic variables were compared with the IEFF scores.

Main Outcome Measures

IIEF scores; proportions of NAFLD patients who demonstrated ED and/or MetS; association between the severity of histological hepatic damage and ED.

Results

Forty male patients having an age range of 33 (24–57) and a mean age of 40.13 ± 10.22 years with biopsy-proven NAFLD had a median IIEF-5 score of 16 (9–25) and MetS was present in 23 (57.5%). ED severity distributions as moderate, mild, and no ED were 11 (27.5%), 16 (40%), and 13 (32.5 %), respectively. Histological NAFLD score was significantly higher in patients having ED compared with patients with no ED (5.63 ± 1.39 vs 4.15 ± 1.46; P = .006). MetS diagnosis was significantly more common in patients having ED, compared with those without ED [19 (70.4%) vs 4 (30.8%), respectively, P = .018)]. When patients with and without ED were compared, gamma glutamyl transferase was significantly lower in ED, whereas components of MetS did not correlate with ED. After multivariate analysis, NAFLD score has remained the only significant outcome associated with ED [P = .03; OR (95% CI): 2.38 (1.079–5.238)].

Conclusion

The current clinical study demonstrates a significant association between nonalcoholic steatohepatitis and ED for the first time. Our findings suggest liver damage may play role in the pathogenesis of ED in patients with NAFLD. Future studies are needed to expand the underlying common mechanisms responsible for this novel hypothesis.
Decreased Endogenous Hydrogen Sulfide Generation in Penile Tissues of Diabetic Rats with Erectile Dysfunction
Authors: Zhang Yan , Yang Jun , Wang Tao , Wang Shao-Gang , Liu Ji-Hong , Yin Chun-Ping , Ye Zhang-Qun
Published: February 2016

Introduction

Hydrogen sulfide (H2S) is an endogenous gasotransmitter. The levels of H2S-generating enzyme expression and endogenous H2S production in diabetic rats with erectile dysfunction (ED) remain unknown. The aim of this study was to investigate the expression of the H2S-generating enzymes and endogenous production of H2S in penile tissues of diabetic ED rats.

Methods

Experimental rats were randomly divided into normal control group, apomorphine (APO)-positive group and APO-negative group. Primary rat corpus cavernosum smooth muscle cells (CCSMCs) and aortic endothelial cells (AECs) were isolated and cultured in vitro under 3 different conditions: normal glucose (NG) condition, high glucose (HG) condition, and osmotic control (OC) condition.

Main Outcome Measures

Erectile function; H2S concentrations in plasma or penile tissues; expression of H2S-generating enzymes and endogenous H2S production in penile tissues, CCSMCs, and AECs.

Results

Erectile function was significantly decreasedin the APO-negative group. In addition to significantly decreased expression of cysteine aminotransferase (CAT), d-amino acid oxidase (DAO), and 3-mercaptopyruvate sulfurtransferase (3-MST), the H2S concentrations in plasma and penile tissues and endogenous H2S production were significantly decreased in the APO-negative group. Endogenous H2S production by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) decreased to the same levels in the APO-negative and APO-positive groups as that in the normal control group. However, CBS and CSE expression remained unchanged in the 3 groups. Under HG conditions, H2S-generating enzyme expression in AECs did not change, while CAT, DAO, and 3-MST expression in CCSMCs was significantly decreased. In both cell types, H2S production by these enzymes was decreased in the HG group.

Conclusion

Endogenous H2S production was significantly decreased in the diabetic ED rats' penile tissues due to downregulated expression of the CAT/3-MST and DAO/3-MST pathways and low activities of CBS and CSE.
Methylisoindigo preferentially kills cancer stem cells by interfering cell metabolism via inhibition of LKB1 and activation of AMPK in PDACs
Authors: Cheng Xinlai , Kim Jee Young , Ghafoory Shahrouz , Duvaci Tijen , Rafiee Roya , Theobald Jannick , Alborzinia Hamed , Holenya Pavlo , Fredebohm Johannes , Merz Karl-Heinz , Mehrabi Arianeb , Hafezi Mohammadreza , Saffari Arash , Eisenbrand Gerhard , Hoheisel Jörg D. , Wölfl Stefan
Published: February 2016

Pancreatic ductal adenocarcinoma (PDAC) clinically has a very poor prognosis. No small molecule is available to reliably achieve cures. Meisoindigo is chemically related to the natural product indirubin and showed substantial efficiency in clinical chemotherapy for CML in China. However, its effect on PDAC is still unknown. Our results showed strong anti‐proliferation effect of meisoindigo on gemcitabine‐resistant PDACs. Using a recently established primary PDAC cell line, called Jopaca‐1 with a larger CSCs population as model, we observed a reduction of CD133+ and ESA+/CD44+/CD24+ populations upon treatment and concomitantly a decreased expression of CSC‐associated genes, and reduced cellular mobility and sphere formation. Investigating basic cellular metabolic responses, we detected lower oxygen consumption and glucose uptake, while intracellular ROS levels increased. This was effectively neutralized by the addition of antioxidants, indicating an essential role of the cellular redox balance. Further analysis on energy metabolism related signaling revealed that meisoindigo inhibited LKB1, but activated AMPK. Both of them were involved in cellular apoptosis. Additional in situ hybridization in tissue sections of PDAC patients reproducibly demonstrated co‐expression and ‐localization of LKB1 and CD133 in malignant areas. Finally, we detected that CD133+/CD44+ were more vulnerable to meisoindigo, which could be mimicked by LKB1 siRNAs. Our results provide the first evidence, to our knowledge, that LKB1 sustains the CSC population in PDACs and demonstrate a clear benefit of meisoindigo in treatment of gemcitabine‐resistant cells. This novel mechanism may provide a promising new treatment option for PDAC.
Recent advances in high-pressure science and technology
Authors: Mao Ho-Kwang , Chen Bin , Chen Jiuhua , Li Kuo , Lin Jung-Fu , Yang Wenge , Zheng Haiyan
Published: February 2016

Recently we are witnessing the boom of high-pressure science and technology from a small niche field to becoming a major dimension in physical sciences. One of the most important technological advances is the integration of synchrotron nanotechnology with the minute samples at ultrahigh pressures. Applications of high pressure have greatly enhanced our understanding of the electronic, phonon, and doping effects on the newly emerged graphene and related 2D layered materials. High pressure has created exotic stoichiometry even in common Group 17, 15, and 14 compounds and drastically altered the basic σ and π bonding of organic compounds. Differential pressure measurements enable us to study the rheology and flow of mantle minerals in solid state, thus quantitatively constraining the geodynamics. They also introduce a new approach to understand defect and plastic deformations of nano particles. These examples open new frontiers of high-pressure research.
Special Issue of The Aeronautical Journal, marking the 150th Anniversary of the Founding of the Royal Aeronautical Society
Authors: Bearman Peter
Published: February 2016

This special issue is one of a number of activities taking place this year to celebrate the founding of the Royal Aeronautical Society in 1866. The decision to form the Society was taken on 12 January 1866 at a meeting of distinguished people held in London and chaired by the Duke of Argyll. One of those present, James Glaisher, addressed the gathering and it is interesting to revisit an extract from his statement: “The first application of the balloon as a means of ascending into the upper regions of the atmosphere has been almost within the recollection of men now living but with the exception of some of the early experimenters it has scarcely occupied the attention of scientific men, nor has the subject of aeronautics been properly recognised as a distinct branch of science. . .”. The meeting resolved “that it is desirable to form a Society for the purpose of increasing by experiments our knowledge of Aeronautics and for other purposes incidental thereto and that a Society be now formed under the title of the ‘Aeronautical Society of Great Britain’ to be supported by annual subscriptions and donations.”
On the role and challenges of CFD in the aerospace industry
Authors: Spalart P. R. , Venkatakrishnan V.
Published: February 2016

This article examines the increasingly crucial role played by Computational Fluid Dynamics (CFD) in the analysis, design, certification, and support of aerospace products. The status of CFD is described, and we identify opportunities for CFD to have a more substantial impact. The challenges facing CFD are also discussed, primarily in terms of numerical solution, computing power, and physical modelling. We believe the community must find a balance between enthusiasm and rigor. Besides becoming faster and more affordable by exploiting higher computing power, CFD needs to become more reliable, more reproducible across users, and better understood and integrated with other disciplines and engineering processes. Uncertainty quantification is universally considered as a major goal, but will be slow to take hold. The prospects are good for steady problems with Reynolds-Averaged Navier-Stokes (RANS) turbulence modelling to be solved accurately and without user intervention within a decade – even for very complex geometries, provided technologies, such as solution adaptation are matured for large three-dimensional problems. On the other hand, current projections for supercomputers show a future rate of growth only half of the rate enjoyed from the 1990s to 2013; true exaflop performance is not close. This will delay pure Large-Eddy Simulation (LES) for aerospace applications with their high Reynolds numbers, but hybrid RANS-LES approaches have great potential. Our expectations for a breakthrough in turbulence, whether within traditional modelling or LES, are low and as a result off-design flow physics including separation will continue to pose a substantial challenge, as will laminar-turbulent transition. We also advocate for much improved user interfaces, providing instant access to rich numerical and physical information as well as warnings over solution quality, and thus naturally training the user.
Computational aerodynamics: Advances and challenges
Authors: Drikakis Dimitris , Kwak Dochan , Kiris Cetin C.
Published: February 2016

Computational aerodynamics, which complement more expensive empirical approaches, are critical for developing aerospace vehicles. During the past three decades, computational aerodynamics capability has improved remarkably, following advances in computer hardware and algorithm development. However, most of the fundamental computational capability realised in recent applications is derived from earlier advances, where specific gaps in solution procedures have been addressed only incrementally. The present article presents our view of the state of the art in computational aerodynamics and assessment of the issues that drive future aerodynamics and aerospace vehicle development. Requisite capabilities for perceived future needs are discussed, and associated grand challenge problems are presented.
Airbus Group: A Story of Continuous Innovation
Authors: Botti Jean
Published: February 2016

The 150th anniversary of the Royal Aeronautical Society offers an ideal opportunity to reflect on the spirit of innovation and collaboration fostered by the Society and its members over the past century and a half. Dr Jean Botti, an engineer with 31 patents to his name and Chief Technical Officer at Airbus Group, reflects on key innovation milestones for both Airbus Group and the industry as a whole. He also discusses the benefits of collaboration between the RAeS members and industry, and looks forward to an exciting new era of discovery – from electric flight (e-flight) to ‘smarter skies’ and the future development of new modes of flight which can only be imagined today.
The design of future passenger aircraft – the environmental and fuel price challenges
Authors: Jupp J. A.
Published: February 2016

This paper is intended as a general introduction to the requirements for future passenger aircraft design. The needs of the 21stcentury are addressed to meet the important requirements of the customer airlines as well as those of the general public. In particular, the impact on two traditional major requirements are reviewed, the Design Mission and the operating costs. The effect of aircraft on the environment and the increases in the cost of fuel will have a substantial effect on the way future aircraft are optimised. These demands are summarised before moving on to the basic equations affecting how the aircraft design must respond. Very similar targets driving research work have been set in both Europe and the United States, and some of the new technologies that we can expect to be incorporated are outlined. Finally, a glimpse is given of the possible future aircraft configurations we may see in the skies in response to the new demands.
Revitalising advanced rotorcraft research – and the compound helicopter
Authors: Ormiston R. A.
Published: February 2016

PREFACE

I was honoured to have been selected to deliver the 35thNikolsky Honorary Lecture. My graduate education at Princeton University owed much to the influence of Alexander A. Nikolsky, the second faculty member appointed to the Princeton Aeronautical Engineering Department in 1943(1). I arrived in 1963, only months after he passed away, but the memory of his presence was still vivid in the minds of his students and colleagues, as well as the professors who introduced me to rotorcraft(2,3). Bob Lynn, Senior Vice President at Bell Helicopter Textron, one of Nikolsky's most illustrious students, recalled the impact of his teaching in the 12thNikolsky Lecture in 1992(4).
Parliamentary Opposition on the Wane? The Case of Sweden, 1970–2014
Authors: Loxbo Karl , Sjölin Mats
Published: February 2016

While it is commonly assumed that parliamentary opposition is on the wane in Western democracies, we argue that evidence supporting this established proposition is lacking. Therefore, drawing on unique data from the Swedish parliament (the Riksdag), between 1970 and 2014, this article breaks new ground by systematically testing the ‘waning-of-opposition thesis’. First, we explore patterns of cross-partisan cooperation by gauging the extent to which governments seek to accommodate the position of the opposition. Second, we study the degree of partisan conflict over time by mapping the degree to which the opposition politicizes and rejects government policies. Our findings directly contradict the waning-of-opposition thesis. In contrast to theoretical expectations, including the influential ‘cartel-party thesis’, the article finds that partisan struggles in general have intensified significantly over time. Therefore, the article casts significant doubt over the influential idea that parliamentary opposition is waning.
Pseudomonas aeruginosa Colonization in the Intensive Care Unit: Prevalence, Risk Factors, and Clinical Outcomes
Authors: Harris Anthony D. , Jackson Sarah S. , Robinson Gwen , Pineles Lisa , Leekha Surbhi , Thom Kerri A. , Wang Yuan , Doll Michelle , Pettigrew Melinda M. , Johnson J. Kristie
Published: February 2016

OBJECTIVE

To determine the prevalence of Pseudomonas aeruginosa colonization on intensive care unit (ICU) admission, risk factors for P. aeruginosa colonization, and the incidence of subsequent clinical culture with P. aeruginosa among those colonized and not colonized.

METHODS

We conducted a cohort study of patients admitted to a medical or surgical intensive care unit of a tertiary care hospital. Patients had admission perirectal surveillance cultures performed. Risk factors analyzed included comorbidities at admission, age, sex, antibiotics received during current hospitalization before ICU admission, and type of ICU.

RESULTS

Of 1,840 patients, 213 (11.6%) were colonized with P. aeruginosa on ICU admission. Significant risk factors in the multivariable analysis for colonization were age (odds ratio, 1.02 [95% CI, 1.01–1.03]), anemia (1.90 [1.05–3.42]), and neurologic disorder (1.80 [1.27–2.54]). Of the 213 patients colonized with P. aeruginosa on admission, 41 (19.2%) had a subsequent clinical culture positive for P. aeruginosa on ICU admission and 60 (28.2%) had a subsequent clinical culture positive for P. aeruginosa in the current hospitalization (ICU period and post-ICU period). Of these 60 patients, 49 (81.7%) had clinical infections. Of the 1,627 patients not colonized on admission, only 68 (4.2%) had a subsequent clinical culture positive for P. aeruginosa in the current hospitalization. Patients colonized with P. aeruginosa were more likely to have a subsequent positive clinical culture than patients not colonized (incidence rate ratio, 6.74 [95% CI, 4.91–9.25]).

CONCLUSIONS

Prediction rules or rapid diagnostic testing will help clinicians more appropriately choose empirical antibiotic therapy for subsequent infections.

Infect Control Hosp Epidemiol 2016;37:544–548
Minority Languages in Dictatorships: A New Measure of Group Recognition
Authors: Liu Amy H. , Gandhi Jennifer , Bell Curtis
Published: February 2016

What explains minority language recognition in dictatorships? In this paper, we argue that minority language groups in authoritarian regimes are morelikelyto have their languages recognized when their interests are represented by a party in the legislature. Moreover, thelevelof recognition is greater. We test this argument using original group-level and time-variant measures of minority party in legislatureandminority language policies for all Asian dictatorships from 1980 to 2000. The results are robust even when we shift the analysis to the country level globally and account for possible spurious correlations.
Weight functions method for stability analysis applied as design tool for Hawker 800XP aircraft
Authors: Anton N. , Botez R. M.
Published: February 2016

A new method for system stability analysis, the weight functions method, is applied to estimate the longitudinal and lateral stability of a Hawker 800XP aircraft. This paper assesses the application of the weight functions method to a real aircraft and a method validation with an eigenvalues stability analysis of the linear small-perturbation equations. The method consists of finding the weight functions that are equal to the number of differential equations required for system modelling. The aircraft’s stability is determined from the sign of the total weight function – the sign should be negative for a stable model. Aerodynamic coefficients and stability derivatives of the mid-size twin-engine corporate aircraft Hawker 800XP are obtained using the in-house FDerivatives code, recently developed at our laboratory of applied research in active controls, avionics and aeroservoelasticity LARCASE. The results are validated with the flight test data supplied by CAE Inc. for all considered flight cases. This aircraft model was chosen because it was part of a research project for FDerivatives code and continued with weight function method for stability analysis in order to develop a design tool, based only on the aircraft geometrical parameters for subsonic regime. The following flight cases are considered: Mach numbers = 0·4 and 0·5, altitudes = 3,000m, 5,000m, 8,000m and 10,000m, and angles-of-attack α = –5° to 20°.
Experimental analysis of the automated process of sanding aircraft surfaces
Authors: Giublin B. , Vieira J. A. , Vieira T. G. , Trabasso L. G. , Martins C. A.
Published: February 2016

ITA and EMBRAER are currently executing the research project Automation of Aircraft Structural Assembly (AASA) whose goal is to implement a robotic cell for automating the riveting process of aeronautical structures. The proposal described herein complements the AASA project, adds other manufacturing processes, namely sanding and polishing of aircraft surfaces. To implement the additional processes AASA project resources and facilities were used (robots and metrology systems) and devices designed and /or acquired to allow sharing of these resources. Among these, an Automatic Tooling Support for AERonautics structures (ATS_AER) was designed and built; also, a robot tool changer with high load capacity was acquired. The outcome of this research project is the evaluation of the feasibility of automating the processes of sanding and polishing metal surfaces in the aircraft manufacture using robots. The operating method adopted for surface treatment employed the ‘U’ type trajectory optimised to be run by a KUKA robot KR 500. The sanding process has been applied to aluminum metal sheet specimen sized 2•18ft2 (0•20m2) and used commercial 600 and 800 sandpaper. The automated sanding process yielded an average value of RA 0•48 ± 0•08 which is 25% more efficient when compared to the traditional, manual process whose average value of RA is 0•75 ± 0•51.
A review of train aerodynamics Part 1 – Fundamentals
Authors: Baker C. J.
Published: February 2016

This paper is the first of a two-part review of train aerodynamics. After an initial introduction and broad survey of train aerodynamic issues, and a discussion of measurement, modelling and computational techniques, the nature of the flow around trains is considered – in the open air, with and without crosswinds, and in confined geometrical situations and tunnels. The flow in different regions around the train is described and the main flow features outlined. Part 2 of the paper will then consider a number of issues that are of concern in the design and operation of modern trains based on this description of the overall flow field.
Energy absorption structures design of civil aircraft to improve crashworthiness
Authors: Ren Y. , Xiang J.
Published: February 2016

To improve the crashworthiness of civil aircraft, the design concept of energy absorption structure for civil aircraft is investigated. Two typical different design principles could be identified. The first category includes Helicopter and Light fixed-wing Aircraft (HLA), and Transport, Mid-size and Commuter type Aircraft (TMCA) are classified into the second group. Frame, strut and bottom structure are the three kinds of energy absorption structure for TMCA. The strut layout of conventional civil aircraft is studied and some energy absorption devices are adopted. High efficiency energy absorption structures such as the foam and sine-wave beam are employed as the bottom structure for both of HLA and LMCA. The finite element method is used to analyse and design energy absorption structure in aircraft crashworthiness problem. Results show that the crashworthiness of civil aircraft could be largely improved by using proper strut layout and excellent energy absorption device. The stiffness combination of frame and strut should be considered to get better global aircraft deformation. Supporting platform and failure model are the two core problems of bottom energy absorption structure design. Foam and sine-wave beam under the lifted frame could improve the crashworthiness of civil aircraft.
A comparative study of parameter estimation techniques applied to jettisoned external stores
Authors: Guglieri G. , Marguerettaz P. , Simioni G.
Published: February 2016

The present work evaluates the performance of different optimisation techniques on a parameter identification problem of aeronautical interest. In particular, the focus is on the classical Least Square (LS) and Maximum Likelihood (ML) methods and on the CMAES (Covariance Matrix Adaptation Evolution Strategy), DE (Differential Evolution), GA (Genetic Algorithm) and PSO (Particle Swarm Optimisation) Meta-Heuristic methods. The test problem is the reconstruction from flight test data of the aerodynamic parameters of an external store jettisoned from a helicopter. Different initial conditions and the presence of measurement noise are considered. This case is representative of a class of problems of difficult solution because of nonlinearity, ill-conditioning, multidimensionality, non separability, and fitness function dispersion. Only reference algorithm implementations found in literature are used. The performance of each algorithm are defined in terms of fitness function value, sum of absolute errors of the estimated coefficients, computational time and number of function evaluations. The results show the efficiency of CMAES in finding the best estimates with the least computational cost. Moreover, tests reveal that traditional methods depend heavily on problem characteristics and loose accuracy at the increase of the number of unknowns.
Runway conflict alerting: advisory or directive?
Authors: Sammut A. , Mangion D. Zammit
Published: February 2016

Runway conflicts pose a significant threat to continued safety in commercial aviation. In recent years, stakeholders have initiated a number of programmes dealing with the issue of runway incursions, with the majority adopting traditional advisory alerting techniques. In contrast, this work proposes the use of directive cockpit alerting, which provides both an alert of the conflict as well as guidance on which manoeuvre to conduct to clear the conflict. This article reports the findings of simulator trials that have been conducted to assess the effectiveness and acceptability of a directive alerting strategy within the context of runway incursions. Statistical analysis performed on the quantitative measures taken from the evaluations have shown that the directive mode of alerting leads to a higher probability of the crew performing the correct action when faced with an alert. This, together with overall participant acceptance of the directive alerting concept, is a strong indicator that the technique has the potential of providing a complete solution to the problem of runway incursions.
On the application of light weight materials to improve aircraft fuel burn – reduce weight or improve aerodynamic efficiency?
Authors: Poll D. I. A.
Published: February 2016

An analysis, based upon exact relations and previously published approximate relations, is presented. It describes the connection between changes in aircraft weight and changes in the energy to revenue work ratio (ETRW), which, for a given aircraft on a given route, correspond to changes in trip fuel burn. This is used to establish the link between weight saving and fuel burn improvement at both the total aircraft and the component levels. The analysis is then extended to address the impact of trading weight savings anywhere on the aircraft for increased wing aspect ratio, whilst the aircraft total weight remains the same. It is shown that, for flights in excess of about 350 km, if saving fuel is the objective and provided that all the aerodynamic design and airworthiness requirements can be met, it is better to trade weight saving for increased aspect ratio. In general, the ratio of fuel burn reductions for traded to non-traded weight varies with aircraft size, design range, distance flown and payload carried, with the maximum values, for typical operational payloads, ranging from 2•8, for the smaller aircraft, to 2•2 for the largest aircraft, with medium haul operations deriving the largest benefit. It is estimated that, over the past 50 years, about 10% of the operational empty weight has been traded for increased aspect ratio, giving close to a 20% improvement in ETRW. Finally, estimates are produced for the impact of weight reduction and traded weight reduction on the fuel burn for the current global feet.
An expression for the dynamic stability of blunt slender elliptic bodies in hypersonic flow
Authors: Khalid M. , Juhany K. A.
Published: February 2016

Dynamic stability data on axially symmetric pointed and blunt cones, parabolic profiles and other ogive and blunt cylindrical shapes is readily available in literature; the dynamic stability on elliptic blunt paraboloids has not been studied at any great lengths in the past. Both numerical and experimental results are scarce. The present paper uses the shock expansion method to obtain the unsteady pressure distribution on blunt elliptic conical bodies at small angles-of-attack. The resulting unsteady pressure distribution is suitably integrated over the surface of the elliptic body to obtain appropriate analytic expressions for static and dynamic stability. Owing to scarcity of meaningful numerical or measured data for elliptic bodies, the results are compared in qualitative terms against published dynamic stability data on pointed elliptical cones or other axisymmetric blunt cones.
How to improve open rotor aerodynamics at cruise and take-off
Authors: Hall C. , Zachariadis A. , Brandvik T. , Sohoni N.
Published: February 2016

A key challenge in open rotor design is getting the optimum aerodynamics at both the cruise and take-off conditions. This is particularly difficult because the operation and the requirements of an open rotor are very different at cruise compared to takeoff. This paper uses CFD results to explore the impact of various design changes on the cruise and take-off flow-fields. The paper then considers how a given open rotor design is best operated at take-off to minimise noise whilst maintaining high thrust. The main findings are that various design modifications can be applied to control the flow features that lead to lost efficiency at cruise and increased noise emission at take-off. A breakdown of the lost power terms from CFD solutions demonstrates how developments in open rotor design have led to reduced aerodynamic losses. At take-off, the operating point of the open rotor should be set such that the non-dimensional lift is as high as possible, without causing significant flow separation. This can be achieved through suitable amounts of re-pitch and speed up applied to a design. Comparisons with fully three-dimensional CFD show that the amount of re-pitch required can be determined using simplified methods such as two-dimensional CFD and a Blade Element Method.
Analytical and experimental study of the integral aerodynamic characteristics of low-speed wind turbines
Authors: Valiev M. , Stepanov R. , Pakhov V. , Salakhov M. , Zherekhov V. , Barakos G. N.
Published: February 2016

This paper proposes a new wind turbine concept suitable for low-speed winds. The design is studied using a combination of wind-tunnel experimentation and aerodynamic theory. After processing the experimental results, and after comparison with theory, the optimal conditions for the operation of the turbine are identified. Experimental and theoretical results suggest that the design offers a realistic alternative to conventional horizontal axis wind turbines. In addition, the proposed turbine has good power efficiency at low wind speeds, and is suitable for deployment in areas not yet favoured by wind farm developers.
Supersonic wing-body wave drag co-ordinated optimisation based on FCE methodology
Authors: Guan X.
Published: February 2016

Wave drag reduction is important for the aerodynamic performance optimisation of supersonic cruise aircrafts, such as the supersonic civil transport and the supersonic cruise missile. In this paper a method of the supersonic wing-body wave drag optimisation, the wave drag co-optimisation based on far-field composite elements (CoFCE), is proposed based on class-shape-transformation (CST) parameterisation. Wave drag optimisation cases of a supersonic civil transport wing-body are presented, including the optimisation results and computation cost analyses. It is suggested that the supersonic wing-body wave drag can be significantly reduced by the proposed method with relatively small numbers of design parameter. In the optimisation case presented in this paper a 45% wave drag reduction is achieved. The wave drag optimised configuration also achieved significant lift to drag ratio improvements in small angles-of-attack supersonic cruise flight conditions.
Horizontal flight trajectories optimisation for commercial aircraft through a flight management system
Authors: Patrón R. S. Félix , Kessaci A. , Botez R. M.
Published: February 2016

To reduce aircraft emissions to the atmosphere, the fuel burn from aircraft has to be reduced. For long flights, the cruise is the phase where the most significant reduction can be obtained. A new horizontal profile optimisation methodology to achieve lower emissions is described in this article. The impact of wind during a flight can reduce the flight time, either by taking advantage of tailwinds or by avoiding headwinds. A set of alternative trajectories are evaluated to determine the quickest flight time, and therefore, the lowest fuel burn. To determine the expected amount of fuel reduction, the performance databases used on actual FMS devices, were used. These databases represent the flight performance of commercial aircraft.
A new wind tunnel for the study of pressure-induced separating and reattaching flows
Authors: Mohammed-Taifour A. , Schwaab Q. , Pioton J. , Weiss J.
Published: February 2016

The design, construction, and validation of a new academic wind tunnel is described in detail. The wind tunnel is of a classical, blow-down type and generates a pressure-induced, turbulent separation bubble on a flat test surface by a combination of adverse and favorable pressure gradients. The Reynolds number, based on momentum thickness just upstream of separation, is Reθ≃ 5,000 at a free-stream velocity ofUref= 25ms−1. The length of the separation bubble is estimated at 0°42 ± 0°02m by three different methods. Results of a numerical simulation demonstrate the absence of flow separation in the wind-tunnel contraction. This results in a turbulence level of about 0·05% in the test section. Oil-film visualisation experiments show that the flow near the wall is strongly three-dimensional in the recirculating region and that the topology of the limiting streamlines is consistent with experiments performed on configurations with fixed separation. Finally, spatial variations of the forward-flow fraction have been documented using a thermal-tuft probe and are shown to compare well with the results of the oil-film visualisation.
Trajectory prediction for future air traffic management – complex manoeuvres and taxiing
Authors: Schuster W.
Published: February 2016

The future air traffic management (ATM) concept envisaged by the Single European Sky ATM Research – SESAR – and the USA equivalent NextGen, mark a paradigm shift from the current reactive approach of ATM towards holistic strategic collaborative decision making. The core of the future ATM concept relies on common situational awareness over potentially large time-horizons, based upon the user operational intent. This is beyond human capabilities and requires the support of automation tools to predict aircraft state throughout the operation and provide support to optimal decision making long before any potential conflict may arise. This is achieved with trajectory predictors and conflict detectors and resolvers respectively. Numerous tools have been developed, typically geared towards addressing specific airborne applications. However, a comprehensive literature search suggests that none of the tools was designed to predict trajectories throughout the entire operation of an aircraft, i.e. gate-to-gate. Yet, such functionality is relevant in the holistic optimisation of aircraft operations. To address this gap, this paper builds on an existing en route trajectory prediction (TP) model and develops novel techniques to predict aircraft trajectories for the transitions between the ground- and enroute-phases of operation and for the ground-phase, thereby enabling gate-to-gate (or enroute -to-enroute) TP. The model is developed on the basis of Newtonian physics and operational procedures. Real recorded data obtained from a flight data record (FDR) were used to estimate some of the input parameters required by the model. The remaining parameters were taken from the BADA 3.7 model. Performance results using these flight data demonstrate that the proposed TP model has the potential to accurately predict gate-to-gate trajectories and to support future ATM applications such as gate-to-gate synchronisation.
Runway foreign object detection using RGB
Authors: Chen W.
Published: February 2016

This paper presents an improved algorithm for foreign object debris (FOD) detection on the runway with several innovative techniques. The detection scheme incorporates four steps of geometric adjustment, background subtraction, clutter suppression and camouflage elimination. After geometric adjustment, the background model is built for each pixel with a set of RGB colour values taken in the past at the same location or in the neighborhood in the step of background subtraction. The background model samples are substituted randomly with an unfixed update period. Furthermore, the steps of clutter suppression and camouflage elimination are added to modify the segmentation map after background subtraction in order to increase the detection probability and decrease the false alarm rate. The overall algorithm is applied to the test data and real data on the runway. The results show that the RGB-based algorithm performs better than the classical gray-based techniques.
Technology and operational sensitivity assessment for hypersonic endurance flight vehicles
Authors: Chudoba B. , Coleman G. , Oza A. , Gonzalez L. , Czysz P.A.
Published: February 2016

In an effort to increase the air-breathing endurance capability of current hypersonic research aircraft (i.e. X-43, 7 seconds; X-51, 5 minutes), the authors have explored the technical and operational solution space for a 30 minute cruise endurance demonstrator operating in the Mach 6 to Mach 8 speed regime. The focus of this activity has been on exploration of the available solution space through a unique screening process to assess the implication and interplay between the (a) mission, (b) baseline vehicle, and (c) operational scenarios. This study concludes that an air-launched, liquid hydrogen fuelled, 30 minute duration Mach 6 demonstrator (with 10 min Mach 8 capability) provides the largest feasible solution space of the trades examined (i.e. largest design margins, lowest technical risk) when compared to a kerosene-powered equivalent.
Pulse-frequency modulated guidance laws for a mortar missile with a pulse jet control mechanism
Authors: Pavic M. , Pavkovic B. , Mandic S. , Zivkovic S. , Cuk D.
Published: February 2016

The impact point dispersion of mortar missiles can be drastically reduced with a control ring of lateral pulse jets located around the centre of gravity and a homing head to measure or to derive estimates of appropriate missile-target states, e.g. the line-of-sight rates. A simulation model including a missile as a six-degree-of-freedom vehicle, a jet pulse flight control system, and a relative missile-to-target motion was used for the comparison of four guidance laws i.e. proportional navigation guidance, augmented proportional navigation, augmented proportional navigation with rendezvous, and adaptive sliding-mode guidance. This paper focuses on the efficiency of pulse jet control on miss distance, and thus makes the assumption that sensor measurements and the guidance states required to apply each of the guidance laws are perfectly known. Proportional navigation and the adaptive sliding mode guidance exhibit a large miss distance due to limited control authority. Augmented proportional navigation is slightly better than augmented proportional navigation with rendezvous for the same design parameters and they both give small miss distances with limited control authority, but they both require a free gyro. A proper selection of the design parameters — the number of pulse jets and the magnitude of the individual pulse jet thrust for a particular dispersion of flight parameters and the instant of the guidance start — is required to achieve optimum dispersion reduction. The minimum intensity of the individual pulse jet impulse required for the ‘pin point’ accuracy (the circular error probable smaller than 1m) of the mortar missile was determined for all presented guidance laws considering dispersion from the nominal trajectory.
Modelling the aeroelastic response and flight dynamics of a hingeless rotor helicopter including the effects of rotor-fuselage aerodynamic interaction
Authors: Goulos I.
Published: February 2016

This paper presents a mathematical approach for the simulation of rotor-fuselage aerodynamic interaction in helicopter aeroelasticity and flight dynamics applications. A Lagrangian method is utilised for the numerical analysis of rotating blades with nonuniform structural properties. A matrix/vector-based formulation is developed for the treatment of elastic blade kinematics in the time-domain. The combined method is coupled with a finite-state induced flow model, an unsteady blade element aerodynamics model, and a dynamic wake distortion model. A three-dimensional, steady-state, potential flow, source-panel method is employed for the prediction of induced flow perturbations in the vicinity of the fuselage due to its presence in the free-stream and within the rotor wake. The combined rotor-fuselage model is implemented in a nonlinear flight dynamics simulation code. The integrated approach is deployed to investigate the effects of rotor-fuselage aerodynamic interaction on trim performance, stability and control derivatives, oscillatory structural blade loads, and nonlinear control response for a hingeless rotor helicopter modelled after the Eurocopter Bo105. Good agreement is shown between flow-field predictions and experimental measurements for a scaled-down isolated fuselage model. The proposed numerical approach is shown to be suitable for real-time flight dynamics applications with simultaneous prediction of structural blade loads, including the effects of rotor-fuselage aerodynamic interaction.
Control of the horizontal position of a stratospheric airship during ascent and descent
Authors: Chen L. , Zhou H. , Wen Y. B. , Duan D. P.
Published: February 2016

A stratospheric airship flies at a working altitude of 20km when it takes off from the ground. During ascent and descent, the wind field and thermal environment are highly complex. The thermal environment affects altitude, whereas wind influences the horizontal position of the airship. At a low altitude, this horizontal position cannot be controlled by thrusts given the low thrust-to-weight ratio, especially under a large wind field. However, it may be controlled indirectly by the pitch angle during ascent and descent with a certain vertical velocity. This study therefore proposes ascending and descending schemes for a stratospheric airship based on the thermal model. In this model, altitude is determined by the net lift/weight, whereas the horizontal position is controlled by the thrust and pitch. The pitch angle is determined by ballonets and an elevator. To allocate pitch control between the ballonets and the elevator under different airspeeds, pseudo-inverse dynamics of varied weight are introduced. In horizontal position control, the method of chain allocation is then applied between a pitch angle and vectored thrust to control the position of a stratospheric airship during ascent/descent.
Advanced noise abatement departure procedures: custom-optimised departure profiles
Authors: Hebly S. J. , Visser H. G.
Published: February 2016

This paper presents the concept of custom-optimised departure profiles, as an advanced form of noise abatement departure procedures. This concept relies on fixed routes in combination with individually optimised vertical departure profiles. Although the use of fixed ground tracks results in some loss in environmental performance, the high degree of complexity associated with free routing is eliminated as well, leading to a concept that does not appear to be incompatible with today’s Air Traffic Control (ATC) principles. By using a primitive form of trajectory negotiation between airline and ATC, selected flights can be allowed to perform an optimised departure without interfering with non-participating traffic. Apart from the concept itself, this paper also describes the departure profile optimisation tool, which is based on a previously developed trajectory optimisation framework called NOISHHH. Finally, in a numerical example, a current standard ICAO-A procedure is compared with two optimised profiles for a Boeing 737 departure from Amsterdam Airport. Fuel burn, noise impact and the required flight time to a specified point are compared for the three departure profiles. It is shown that the custom-optimised departure profiles have the potential to both reduce fuel burn as well as noise exposure, relative to the ICAO-A procedure.