bluuebunny/crossref_metadata_2025 huggingface dataset:
Register allocation and spilling using the expected distance heuristic
Authors: Burroughs Neil
Published: February 2016

The primary goal of the register allocation phase in a compiler is to minimize register spills to memory. Spill decisions by the allocator are often made based on the costs of spilling a virtual register and, therefore, on an assumed placement of spill instructions. However, because most allocators make these decisions incrementally, placement opportunities can change as allocation proceeds, calling into question the basis for the original spill decision. An alternative heuristic to placement costs for spill decisions focuses on where program execution will lead. Spilling the virtual register with the Furthest Next Use is known to lead to the minimum number of loads under certain conditions in straight‐line code. While it has been implemented in register allocation in different forms, none of these implementations fully exploits profiling information. We present a register allocator that can adapt to improved profiling information, using branch probabilities to compute an Expected Distance to Next Use for making spill decisions and block frequency information to optimize post‐allocation spill instruction placement. Spill placement is optimized after allocation using a novel method for minimizing spill instruction costs on the control flow graph. Our evaluation of the allocator compared with LLVM recognizes more than 36% and 50% reductions, on average, in the number of dynamically executed store and load instructions, respectively, when using statically derived profiling information. When using dynamically gathered profiling, these improvements increase to 50% and 60% reductions, on average, for stores and loads, respectively. Copyright © 2016 John Wiley & Sons, Ltd.
Segmentbrücke Greißelbach als Stahlverbundbrücke ohne Abdichtung und Asphalt
Authors: Seidl Günter , Hierl Martin , Breu Michael , Mensinger Martin , Stambuk Mislav
Published: February 2016

Ein neues Konzept im Brückenbau wird im Pilotprojekt Greißelbach umgesetzt. Das Hauptmerkmal des Bauprinzips bildet die Trennung der Tragstruktur in ein Längs‐ und ein Quertragsystem und die trocken gestoßenen, voll vorgespannten Segmente ohne Abdichtung und Asphalt. Das Haupttragsystem bildet ein VFT‐Rahmen als integrales Bauwerk. Durch eine Gleitebene zwischen Segment und Hauptträger bewegt sich die Fahrbahnplatte unabhängig vom Haupttragsystem. Die Bauweise weist eine hohe Qualität und sehr kurze Bauzeiten durch die Vorfertigung sowie große Flexibilität in der Nutzung aus.

Segment bridge Greißelbach as composite bridge without sealing and asphalt. The Greißelbach bridge project implements a new construction principle. The main feature of the construction is the separation of the bridge bearing system in a main structural system in longitudinal and transversal direction in interaction with dry jointed segments without sealing and asphalt. A VFT‐frame is the integral main structural system. The deck slab is independently moving of the structural system realised by a sliding surface between the segments and the main girders. The construction is characterized by its high quality level and the short construction time based on the high level of prefabrication. Furthermore the bridge implements a high degree of flexibility in service.
Randnahe Kopfbolzen – Ermüdungsverhalten unter Querschub
Authors: Raichle Jochen , Kuhlman Ulrike
Published: February 2016

Kopfbolzen, die in neuen interessanten Konstruktionsformen nahe zum freien Bauteilrand des Betons angeordnet werden, zeigen ein anderes, durch frühe Spaltrissbildung bestimmtes Tragverhalten als die üblichen randfernen Kopfbolzen. Der effektive Randabstand hat einen bedeutenden Einfluss auf die Tragfähigkeit. Für die bisher schon in DIN EN 1994‐2, Anhang C gegebenen Bemessungsregeln bei einer randnahen Anordnung mit Beanspruchungsrichtung längs oder quer zum freien Bauteilrand werden Ergänzungen und Verbesserungen erläutert. Insbesondere werden Forschungsergebnisse zum Ermüdungsverhalten unter Querschub vorgestellt, die auch zu einer Bemessungsgleichung für die Ermüdungsfestigkeit von randnahen Kopfbolzen unter Querschub führen. Darüber hinaus wird für diesen Fall der Einfluss einer Ermüdungsbeanspruchung auf die statische Resttragfähigkeit näher betrachtet.

Headed studs that cause splitting forces in direction of the slab thickness – Fatigue behaviour under transverse shear – enhancement of existing rules. Headed studs, arranged in interesting innovative composite cross sections near to the slab surface, show a different load carrying behaviour due to splitting forces than studs in standard situations without any edge influence. The effective edge distance has a significant influence on the carrying capacity. For the rules given in EN 1994‐2, Annex C for the case of headed studs close to the concrete surface with load direction either in longitudinal or transverse direction, enhancements and improvements are explained in detail. Especially research results on the fatigue behaviour of headed studs close to the concrete surface under transverse shear are introduced und a design equation for the fatigue resistance is provided. Furthermore the influence of a fatigue loading on the residual static resistance of headed stud arranged close to the concrete surface is discussed.
Schicksal der Freybrücke – ein Baudenkmal wurde entsorgt
Authors: Dicleli Cengiz
Published: February 2016

Karl Bernhard gilt als einer der bedeutendsten Bauingenieure in Deutschland Anfang des 20. Jahrhunderts. Seine beiden Brücken entlang der Heerstraße in Berlin, die Stößenseebrücke und die Freybrücke über die Havel, sind seit 1909 verkehrstechnisch von höchster Bedeutung für die Ost‐West‐Verbindung der Stadt. Die Freybrücke wurde jedoch im März 2015 abgerissen, um einem Ersatzneubau Platz zu machen. Wie kam es dazu, dass eine historisch und verkehrstechnisch derart wichtige, seit 1971 unter Denkmalschutz stehende Konstruktion so lange vernachlässigt wurde, bis sie abbruchreif war? Dieser Artikel ist eine Hommage an Bernhards Havelbrücke und geht ihrer wechselvollen Geschichte nach.

The fate of the Frey Bridge in Berlin – A memorial structure was disposed. Karl Bernhard is one of the significant German civil engineers of the beginning of the 20th century. His two bridges along the Heerstrasse in Berlin, the Stössensee Bridge and the Frey Bridge which are crossing the Havel River, have been since 1909 of paramount importance for the East‐West traffic connection of the city. The Frey Bridge was demolished in March 2015 in order to make room for a new substitution bridge. How was it possible at all that from a historical and traffic‐technical point of view such an important construction has been neglected so long that it became ripe for demolition? And although it was under preservation since 1971? This article is a homage to Bernhard’s Havel Bridge and follows up its rich history.
Die neue Bleichinselbrücke in Heilbronn
Authors: Keil Andreas , Schächner Frank
Published: February 2016

Die neue Bleichinselbrücke überspannt mit 88 m Länge und 24 m Breite den Alt‐Neckar in Heilbronn und verbindet die Innenstadt mit dem neu entstehenden Stadtgebiet auf der nördlichen Hälfte der Bleichinsel. Die 5‐feldrige Straßenbrücke ist als Verbundtragwerk mit oben liegender Betonfahrbahnplatte aus Halbfertigteilen und Ortbetonergänzung ausgeführt. Das darunter liegende Tragwerk besteht aus zwei geschweißten Stahlhohlkästen als Längsträger und schrägen, V‐förmig angeordneten Stützstreben, welche sich an den Ufern jeweils in einem Punkt treffen. Die Stützstreben wie auch die Widerlagerwände sind monolithisch mit den Längsträgern verbunden, es konnte ein integrales Bauwerk konzipiert werden, für das weder Lager noch Übergangskonstruktionen erforderlich wurden. Im Folgenden wird auf Entwurf, Konstruktion und Berechnung sowie auf Fertigung und Montage eingegangen.

The new road bridge ‘Bleichinselbrücke’ in Heilbronn – Design of an integral composite road bridge. With 88 m length and 24 m width the new road bridge “Bleichinselbrücke” spans across the river “Alt‐Neckar” in Heilbronn connecting the city centre with the new residential area on the northern side of the island “Bleichinsel”. The 5‐span bridge is designed as a composite structure with a concrete deck made of precast concrete slabs and in situ concrete. The supporting structure of the deck consists of two welded steel hollow boxes as longitudinal girders and inclined V‐shaped struts at each side, which merge at one point at the river banks. The supporting struts as well as the abutment walls are monolithically connected to the longitudinal girders. An integral bridge structure has been conceived, without bearings and construction joints. The following report points out the architectural and structural design as well the construction and erection.
Peptide nanostructures in biomedical technology
Authors: Feyzizarnagh Hamid , Yoon Do‐Young , Goltz Mark , Kim Dong‐Shik
Published: February 2016

Nanostructures of peptides have been investigated for biomedical applications due to their unique mechanical and electrical properties in addition to their excellent biocompatibility. Peptides may form fibrils, spheres and tubes in nanoscale depending on the formation conditions. These peptide nanostructures can be used in electrical, medical, dental, and environmental applications. Applications of these nanostructures include, but are not limited to, electronic devices, biosensing, medical imaging and diagnosis, drug delivery, tissue engineering and stem cell research. This review offers a discussion of basic synthesis methods, properties and application of these nanomaterials. The review concludes with recommendations and future directions for peptide nanostructures. WIREs Nanomed Nanobiotechnol 2016, 8:730–743. doi: 10.1002/wnan.1393

This article is categorized under:

Diagnostic Tools > Biosensing

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Biology-Inspired Nanomaterials > Peptide-Based Structures
Enhancing post anaerobic digestion of full-scale anaerobically digested sludge using free nitrous acid treatment
Authors: Zhang Tingting , Wang Qilin , Ye Liu , Yuan Zhiguo
Published: February 2016

In some wastewater treatment plants (WWTPs), the ever increasing production of sludge with the expanding population overloaded the anaerobic digestion which compromises the sludge reduction efficiency. Post anaerobic digestion of anaerobically digested sludge (ADS) has been applied to enhance sludge reduction, however, to a very limited extent. This study verified the effectiveness of free nitrous acid (FNA i.e. HNO2) pre-treatment on enhancing full-scale ADS degradation in post anaerobic digestion. The ADS collected from a full-scale WWTP was subject to FNA treatment at concentrations of 0.77, 1.54, 2.31, 3.08, and 3.85 mg N/L for 24 h followed by biochemical methane potential tests. The FNA treatment at all concentrations resulted in an increase (from 1.5–3.1 % compared to the control) in sludge reduction with the highest improvement achieved at 0.77 mg HNO2-N/L. The FNA treatment at this concentration also resulted in the highest increase in methane production (40 %) compared to the control. The economic analysis indicates that FNA treatment is economically attractive for enhancing post anaerobic digestion of full-scale ADS.
A Unified Approach to Functional Principal Component Analysis and Functional Multiple-Set Canonical Correlation
Authors: Choi Ji Yeh , Hwang Heungsun , Yamamoto Michio , Jung Kwanghee , Woodward Todd S.
Published: February 2016

Functional principal component analysis (FPCA) and functional multiple-set canonical correlation analysis (FMCCA) are data reduction techniques for functional data that are collected in the form of smooth curves or functions over a continuum such as time or space. In FPCA, low-dimensional components are extracted from a single functional dataset such that they explain the most variance of the dataset, whereas in FMCCA, low-dimensional components are obtained from each of multiple functional datasets in such a way that the associations among the components are maximized across the different sets. In this paper, we propose a unified approach to FPCA and FMCCA. The proposed approach subsumes both techniques as special cases. Furthermore, it permits a compromise between the techniques, such that components are obtained from each set of functional data to maximize their associations across different datasets, while accounting for the variance of the data well. We propose a single optimization criterion for the proposed approach, and develop an alternating regularized least squares algorithm to minimize the criterion in combination with basis function approximations to functions. We conduct a simulation study to investigate the performance of the proposed approach based on synthetic data. We also apply the approach for the analysis of multiple-subject functional magnetic resonance imaging data to obtain low-dimensional components of blood-oxygen level-dependent signal changes of the brain over time, which are highly correlated across the subjects as well as representative of the data. The extracted components are used to identify networks of neural activity that are commonly activated across the subjects while carrying out a working memory task.
Clinical and electrocardiographic predictors of T wave oversensing in patients with subcutaneous ICD
Authors: El‐Chami Mikhael F. , Harbieh Bernard , Levy Mathew , Leon Angel R. , Merchant Faisal M.
Published: February 2016

Background

T wave oversensing (TWOS) is a major drawback of the subcutaneous implantable cardioverter defibrillator (S‐ICD). Data on predictors of TWOS in S‐ICD recipients are limited.

We sought to investigate predictors of TWOS in a cohort of patients receiving an S‐ICD at our institution.

Methods

S‐ICD recipients at our center were identified retrospectively and stratified based on the presence or absence of TWOS. Clinical and electrocardiographic parameters were collected and compared between the 2 groups.

Results

Ninety‐two patients underwent an S‐ICD implantation at our institution between April 2010 and January 2015. Six (6.5%) patients had TWOS. These patients were younger (38.1±13.7 vs. 52.3±16.1 years, p=0.04) and had higher left ventricle ejection fractions (48.5±14.9% vs. 28.4±12.2%, p<0.01) than patients without a history of TWOS. Baseline 12‐lead electrocardiogram (ECG) parameters were not different between the 2 groups. Leads I, II, and avF (which mimic the sensing vectors of the S‐ICD) were further inspected to identify ECG characteristics that could predict TWOS. The QRS amplitude in ECG lead I was significantly smaller in the TWOS group than in the non‐TWOS group (3.7 vs. 7.4 mV, p=0.02).

Conclusion

In this study, younger age, higher ejection fraction, and lower QRS amplitude were associated with TWOS. These findings could help identify patients referred for S‐ICD at high‐risk of TWOS.
The evolution of the subduction zone magmatism on the Neoproterozoic and Early Paleozoic active margins of the Paleoasian Ocean
Authors: Gordienko I.V. , Metelkin D.V.
Published: February 2016

The geodynamic reconstruction using new data on the composition, age, and paleomagnetism of Neoproterozoic and Vendian–Early Paleozoic island arc complexes has provided new insights into the evolution of the subduction zone magmatism over extensive areas of the Central Asian Orogenic Belt, including eastern Altai–Sayan, Transbaikalia, and Northern Mongolia. Comparison of the igneous complexes of modern and ancient ensimatic and ensialic island arcs in the subduction zone forms a basis for possible geodynamic scenarios of the subduction zone magmatism in Neoproterozoic and Vendian–Early Paleozoic island arcs in the zone of interaction between the Siberian paleocontinent and the Paleoasian Ocean, which take into account the composition of crustal and mantle (including mantle plume) components.
Evolution of tectonic events and topography in southeastern Gorny Altai in the Late Mesozoic–Cenozoic (data from apatite fission track thermochronology)
Authors: Vetrov E.V. , Buslov M.M. , De Grave J.
Published: February 2016

Results of apatite fission track dating have been summarized and correlated with stratigraphic, geoelectrical, tectonic, and geomorphological data. The average regional rate of rock denudation in southeastern Gorny Altai is reflected in three thermotectonic events: (1) Late Cretaceous–Early Paleogene tectonic activity with a denudation rate of ~200 m/Myr, related to the distant impact of the Mongol–Okhotsk orogeny; (2) Middle Paleogene–Early Neogene stabilization with peneplanation; and (3) Neogene–Quaternary “stepwise” tectonic activity with a denudation rate of ≤270 m/Myr, related to the distant impact of the Indo-Eurasian collision. We present results of study of the evolution of regional tectonic processes and topography over the last 100 Myr by analysis of digital and shaded elevation models and apatite fission track dating.
Boninites and ophiolites: Problems of their relations and petrogenesis of boninites
Authors: Sklyarov E.V. , Kovach V.P. , Kotov A.B. , Kuzmichev A.B. , Lavrenchuk A.V. , Perelyaev V.I. , Shchipansky A.A.
Published: February 2016

There are four main types of boninites in ophiolite suites, which either spatially coexist with ophiolites though belong to other tectonic units (1), or are present as later constituents of ophiolite sequences (crosscutting dikes or lavas on top) (2), or build ophiolite sequences together with island-arc tholeiites and basaltic andesites, followed by younger volcanics of MORB or BABB affinites (3), or occupy the whole mafic portion of ophiolite sequences, together with island-arc tholeiites and basaltic andesites (4). The latter type, considered in more detail for the case of ophiolites from the southeastern Sayan Mountains (Siberia, Russia), presents an example of inconsistency between the model of ophiolite formation in mid-ocean ridge settings and subduction-related island-arc fingerprints in ophiolitic mafic rocks. The patterns of boninites record several evolution models of oceanic systems, with melting and intrusion of boninites in forearc, arc, and back-arc settings. The existing models are controversial, possibly, because there is no single mechanism to account for all types of boninites.
Different-depth gabbro–ultrabasite associations in the Sikhote-Alin ophiolites (Russian Far East)
Authors: Khanchuk A.I. , Vysotskiy S.V.
Published: February 2016

Based on the new geological, mineralogical, and geochemical data on the crystalline rocks of the Paleozoic ophiolite associations in the Sikhote-Alin (Russian southern Far East), we have reconstructed the tectonic setting of their formation. Two ophiolite associations have been recognized: peridotite–troctolite and peridotite–gabbronorite, differing mainly in the structure of the cumulative part of their sections. In the peridotite–troctolite association, the base of the cumulative unit is formed mostly by olivine–plagioclase rocks (troctolites and olivine gabbro), and in the peridotite–gabbronorite association, by essentially pyroxene rocks (pyroxenites and wehrlites). We have established that the ophiolite rocks crystallized at different pressures: troctolites—<5 kbar (judging from the stability of the olivine–plagioclase paragenesis), hercynite gabbronorites—5–12 kbar, and garnet gabbro—>12 kbar. The crystalline rocks form a single geochemical series, with the accumulation of lithophile elements and LREE in more differentiated varieties. The REE patterns of rocks are in good correlation with their mineral composition. We assume that the Sikhote-Alin ophiolites formed at the basement of an oceanic plateau growing as a result of mantle plume intrusion.
The Early Cambrian bimodal magmatism in the northeastern Siberian Craton
Authors: Prokopiev A.V. , Khudoley A.K. , Koroleva O.V. , Kazakova G.G. , Lokhov D.K. , Malyshev S.V. , Zaitsev A.I. , Roev S.P. , Sergeev S.A. , Berezhnaya N.G. , Vasiliev D.A.
Published: February 2016

We present new data on geochemistry, isotopic geochemistry, and geochronology of the Early Cambrian igneous rocks of the northeastern Siberian Craton (Kharaulakh anticlinorium, contact between the Siberian Platform and the West Verkhoyansk sector of the Verkhoyansk fold-and-thrust belt united into an Early Cambrian bimodal complex. This complex comprises trachyrhyolites forming pebbles in conglomerates near the base of the Cambrian succession, overlying trachybasalts, and mafic sills and dikes cutting Neoproterozoic strata. According to chemical composition, the felsic rocks are high-alkali rhyolites and correspond to A-type granites. The high contents of Ta, Nb, Hf, Tb, and Zr in these rocks suggest the presence of enriched mantle material in their magmatic sources. The mafic volcanics are high-Ti trachybasalts and trachydolerites with similar geochemical characteristics corresponding to alkali basalts or OIB. The high (Tb/Yb)PM ratios in these volcanics evidence that their magmatic source was the garnet peridotite mantle located at depths more than 90 km and characterized by a low degree of melting. However, the rhyolites, trachybasalts, and trachydolerites show high positive εNd(T) values (4.2–4.7, 7.5–8.9, and 7.2–8.2, respectively) indicating a depleted mantle source and no crustal contamination. The high (Nb/Yb)PM ratio points to the mixing of magmas from enriched and depleted mantle sources. Mafic magmas might have been generated from a heterogeneous source or interacted with the depleted mantle before intrusion. Both the felsic and the mafic rocks formed in within-plate environments. U–Pb zircon dating yielded concordant ages of 525.6 ± 3.9 and 537.0 ± 4.2 Ma, corresponding to the Early Cambrian age of the rhyolites. The date of 546.0 ± 7.7 Ma obtained for one sample points (with regard to the error) to the Late Vendian–Early Cambrian age. Thus, at the Vendian–Early Cambrian boundary, the northeastern Siberian Platform was subjected to continental rifting accompanied by bimodal magmatism of antidrome evolution. According to paleotectonic reconstructions, this part of the Siberian Craton might have been connected with the eastern margin of Laurentia in the Late Neoproterozoic (Late Riphean–Late Vendian), and continental rifting that started at the Vendian–Cambrian boundary led to their separation. The obtained isotope-geochronological data suggest that the studied bimodal complex began to form at the Vendian–Cambrian boundary and this process terminated no earlier than the end of the Terreneuvian (Tommotian), i.e., the complex formed during rifting for about 20 Myr.
U–Pb dating of zircons from PZ3–MZ igneous complexes of Transbaikalia by sector-field mass spectrometry with laser sampling: technique and comparison with SHRIMP
Authors: Khubanov V.B. , Buyantuev M.D. , Tsygankov A.A.
Published: February 2016

U–Pb zircon dating by laser ablation and sector-field mass spectrometry with inductively coupled plasma (LA–SF-ICP-MS) is an accessible local method with easy sample preparation. At the Geological Institute, Ulan-Ude, this method was applied using a Thermo Scientific Element XR single-collector SF ICP mass spectrometer and a UP-213 (New Wave Research) laser ablation system. Measurements for standard zircons showed the error of dating less than 2%. The results of U–Pb LA–SF-ICP-MS dating of zircon from Late Paleozoic granitoids of western Transbaikalia confirm the overlapping of the time intervals of formation of the Barguzin (330–290 Ma), Chivyrkui (305–285 Ma), and Zaza (305–285 Ma) intrusive complexes.
Does Perceived Social Support Mediate or Moderate the Relationship Between Victimisation and Suicidal Ideation Among Chinese Adolescents?
Authors: Liu Xiaoqun , Chen Gui , Hu Peng , Guo Guipin , Xiao Shuiyuan
Published: February 2016

Bullying is a common problem in school. Engagement in bullying has been known to have many adverse effects, even including suicide. Examining which factor will moderate or mediate the pathway from victimisation to suicidal ideation is needed to develop effective intervention initiatives. This study aimed to examine the mediator and moderator roles of perceived social support in the relationship between victimisation and suicidal ideation. The participants in the study were 946 Chinese adolescents (402 girls, 544 boys) who ranged in age from 11 to 16 years old. The results showed that 48.1% of these adolescents reported being bullied in school. Victimisation was positively correlated with suicidal ideation. There was evidence that perceived social support buffered, as well as partially mediated, the relationship between victimisation and suicidal ideation. Results suggest that helping students to seek more support from their parents and peers may be an effective bullying intervention program.
Majoring in nutrition influences BMI of female college students
Authors: Hong Mee Young , Shepanski Tahirih L. , Gaylis Jaclyn B.
Published: February 2016

Maintaining healthy eating habits in college is challenging. Interventions focused on nutrition education can assist in reversing these trends of poor eating habits among college students. The purpose of the study was to identify factors affecting the dietary habits, food choices and BMI of college females majoring in nutrition (NMs) compared with non-nutrition majors (OMs). A questionnaire-based cross-sectional survey study of dietary behaviour and food frequency of 202 college females was conducted at San Diego State University. Data were analysed by using t tests, χ2 tests and regression analysis in SPSS. NMs exhibited a lower BMI than OMs (P < 0·01); however, BMI values for both groups were within a healthy range. Interestingly, 3 % of NMs had a BMI in the range of overweight or obese; however, prevalence was three times higher for OMs, being 9·2 %. A healthier meal option was the most influential factor in NMs’ meal choices whereas convenience and weight control were influential factors in OMs’ meal choices. Most NMs read nutrition labels and reported that this affects their food choices. NMs exercised longer than OMs in the <120 min/week category. Exercise affected healthy meal conception in NMs only (P < 0·001). Taking dietary supplements influenced healthy meal awareness in OMs only (P < 0·05). University-level nutrition education is strongly associated with healthier eating habits and superior food choices among young adult females. More regular meal patterns, healthier snack choice and adherence to dietary guidelines may contribute to the lower BMI values observed among NMs compared with OMs.
Some Recent Developments in the Landing Gear Field
Authors: Lucien Rene
Published: February 2016

What are the particular factors of the aeroplane of 1947, which have a special effect on landing gear technique?

(i)

Increase in the speed of take-off and landing.

1940: 65 to 90 m.p.h.

1947: up to 130 m.p.h.

(ii)

Increase in wing loading and the use of thin or laminar flow wing sections.

1940: 301b. sq.ft.

1947: more than 50 lb. sq. ft.

(iii)

Increase in physical dimensions and all-up-weight of the aircraft.

1940: 80,000 lb.

1947: 300,000 1b.

(iv)

Increase in operational altitude.

1940: 10,000 to 15,000 ft.

1947: 15,000 to 30,000 ft.
Heliplat®: high altitude very-long endurance solar powered UAV for telecommunication and Earth observation applications
Authors: Romeo G. , Frulla G.
Published: February 2016

Research is at present being carried out at the Turin Polytechnic University with the aim of designing an HAVE/UAV (high altitude very-long endurance/unmanned air vehicle). The vehicle should climb to 17-20km by mainly taking advantage of direct Sun radiation and thereafter maintain a level flight; during the night, a fuel cells energy storage system would be used. A computer program has been developed to carry out a parametric study for the platform design. The solar radiation change over one year, the altitude, masses and efficiencies of the solar and fuel cells, and the aerodynamic performances have all been taken into account. The parametric studies have shown how fuel cells and solar cells efficiency and mass have the most influence on the platform dimensions. A wide use of high modulus CFRP has been made in designing the structure in order to minimise the airframe weight. A first configuration of HELIPLAT® (HELIos PLATform) was worked out, following a preliminary parametric study. The platform is a monoplane with eight brushless electric motors, a twin-boom tail type with an oversized horizontal stabiliser and two rudders. The co-ordinates at the root and along the wing span as well as the wing planform were optimised to achieve the best efficiency. Several profiles and wing plans have been analysed using the CFD software Xfoil and Vsaero. Several wind-tunnel tests were carried out to compare the analytically predicted performances. A preliminary design of a scale-sized technological demonstrator was completed with the aim of manufacturing a proof-of-concept structure. A FEM analysis was carried by using the Msc/Patran/Nastran code to predict the static and dynamic behaviour of the UAV structure.
A novel method for the provision of flight experience and flight testing for undergraduate aeronautical engineers at the University of Strathclyde
Authors: Stickland M. T. , Scanlon T. J.
Published: February 2016

The Department of Mechanical Engineering at the University of Strathclyde has developed a novel flight experience/test course for undergraduate Aeronautical Engineers. In common with similar courses at undergraduate level the course contains practical instruction in how an aircraft is flown, an analysis of its stall characteristics and an assessment of an aircraft’s performance and stability. However, uniquely, the Strathclyde course consists of dual instructional flights in two seat gliders. This paper contains a detailed description of the flight experience/test course developed at Strathclyde and its incorporation into the undergraduate curriculum. A critical analysis of its delivery is also presented.
Recent developments in delta wing aerodynamics
Authors: Gursul I.
Published: February 2016

Recent developments in delta wing aerodynamics are reviewed. For slender delta wings, recent investigations shed more light on the unsteady aspects of shear-layer structure, vortex core, breakdown and its instabilities. For nonslender delta wings, substantial differences in the structure of vortical flow and breakdown may exist. Vortex interactions are generic to both slender and nonslender wings. Various unsteady flow phenomena may cause buffeting of wings and fins, however, vortex breakdown, vortex shedding, and shear layer reattachment are the most dominant sources. Dynamic response of vortex breakdown over delta wings in unsteady flows can be characterised by large time lags and hysteresis, whose physical mechanisms need further studies. Unusual flow–structure interactions for nonslender wings in the form of self-excited roll oscillations have been observed. Recent experiments showed that substantial lift enhancement is possible on a flexible delta wing.
Design methodology and performance of an indraft wind tunnel
Authors: Johl G. , Passmore M. , Render P.
Published: February 2016

The design methodology and performance of Loughborough University’s new 1·9m × 1·3m, indraft wind tunnel is discussed in the following paper. To overcome severe spatial and financial constraints, a novel configuration was employed, with the inlet and exit placed adjacent to each other and opened to atmosphere. Using a fine filter mesh, honeycomb, two turbulence reduction screens and a contraction ratio of 7·3, flow uniformity in the working area of the jet at 40ms-1is shown to be within 0·3% deviation from the mean velocity, with turbulence intensity in the region of 0·15%. Working section boundary layer characteristics are shown to be consistent with that of a turbulent boundary layer growing along a flat plate, which originates at the point of inflection of the contraction. A maximum velocity of 46ms-1was achieved from a 140kW motor, compared to a prediction of 44ms-1, giving an energy ratio of 1·42. Comparison between theoretical and measured performance metrics indicate differences between the way modules perform when part of a wind tunnel system compared to data gathered from test rigs.
Optimising expansion deflection nozzles for vacuum thrust
Authors: Taylor N. V. , Hempsell C. M.
Published: February 2016

While expansion deflection (ED) nozzles have traditionally been considered primarily for use as altitude compensating devices to improve the performance of single stage to orbit vehicles, they also offer the potential for enhancing high altitude propulsion systems. If intended to only operate in near vacuum conditions, the complexity of analysis and inherent risks involved in the ED concept are greatly reduced. An integrated approach to the design and performance analysis of such nozzles is presented, comprising a mixture of computational fluid dynamics, the method of characteristics, and a semi-empirical model to allow full analysis of the closed wake flow-field of an ED nozzle. While it is demonstrated that the influence of the parameters used to define the throat region is critical to the successful application of the ED nozzle, it is also shown that with careful design the weight savings possible are significant. The analysis method itself is flexible and rapid, and lends itself well to incremental improvements in accuracy as the flow under consideration becomes better understood.
Life before and after implementation of an acoustic noise reduction enclosure
Authors: Timmins B.
Published: February 2016

This paper looks back on the designs and ambitions of ARA in resolving a long term acoustic noise problem which threatened ARA with closure. This paper today briefly looks back to the original issues but deals more fully with the later phases of a two phase project implementation and construction. ARA is now a truly ‘silent site’, where closure was once threatened, ARA has achieved the implementation of a bespoke noise reduction enclosure where 24-hour running has proved to be a reality. This paper looks at the design and construction phases, the ‘before and after’ noise footprints and at some of the financial benefits ARA has achieved.

The ARA transonic wind tunnel is sited on an industrial estate on the north west perimeter of Bedford. When it was first built it was on an original farm site with no appreciable residential houses in close proximity. Since the early 1950s there has been considerable residential development around the ARA site resulting in the local householders complaining about the wind tunnel acoustic noise. In early 1999 ARA was obliged to consider several options for noise reduction measures to reduce the noise to within UK government statutory requirements.

This paper deals briefly with the original noise nuisance characteristics and footprint, the noise reduction design and method that ARA selected and shows the construction phases, the further noise treatment ARA had to do on other major ancillary equipment to make ARA a truly quiet industrial site.

The paper shows how ARA has utilised the resulting benefits of these investments to increase productivity and reduce costs, and the influence it has had on ARA’s financial health.
Infra-red signature reduction study on a small-scale jet engine
Authors: Dix J. , Saddington A.J. , Knowles K. , Richardson M.A.
Published: February 2016

This paper presents infra-red signature data for a small-scale, low pressure ratio turbojet engine typical of that used in unmanned air vehicle applications. The aim of the study was to test a number of different convergent nozzle designs concentrating on those with trailing edge modifications. The engine used in the tests has a single stage centrifugal compressor and radial inflow turbine and is designed to produce approximately 150N of thrust at 103,500rpm using liquid propane fuel. The test rig consisted of a calibrated thrust stand whilst the engine was controlled through an electronic engine control unit and laptop PC. The jet plume was visualised using an infra-red spectroradiometer which yielded qualitative data across the infra-red spectrum. Simultaneous measurements were also made of the engine thrust. A Pitot probe was used to take pressure readings across different sections of the exhaust flow. Analysis of the infrared signature of the engine exhaust plume and any thrust penalty yielded a performance comparison for each of the nozzles tested. Correlation of engine thrust with engine rpm showed that, within the accuracy of the measurements, there was no significant thrust penalty associated with the notched nozzles. Infra-red imagery of the plain and 60° notched nozzles indicated that the latter reduced the length of the hottest part of the exhaust plume by approximately 33%. The spectroradiometer data shows a significant reduction in spectral radiance for the CO2wavelength of approximately 4·3µm when the notched nozzles are used. The 60° notched nozzle appeared to perform best in reducing the spectral radiance at this wavelength. Centreline total pressure measurements in the exhaust plume correlated well with the infra-red imagery in that a potential core length reduction of up to 30% could be achieved using the 60° notched nozzle. Total pressure contours recorded 20mm (0·43D) downstream of the nozzle exit plane suggest that the notched nozzles are promoting increased mixing through radial spreading of the jet possibly associated with increased streamwise vorticity (although the latter could not be confirmed). There were also signs that the jet plumes being investigated were swirling.
The birth of the practical aeroplane: An appraisal of the Wright brothers’ achievements in 1905
Authors: Padfield G. D. , Lawrence B.
Published: February 2016

In this second Aeronautical Journal paper providing a technical appraisal of the Wright brothers’ achievements, the authors use modelling and simulation and associated flight dynamics analysis to present the development of the first practical aeroplane. The aircraft in question, the Wright Flyer III, was deemed fit for service by the Wrights in October 1905, and had evolved significantly from the first powered aircraft of 17 December 1903. The appraisal tries to shed light on many of the flight handling problems that the Wright brothers faced during this, their third phase of aeronautical endeavour, in 1904 and 1905. They retained their unstable configuration born in the 1901 and 1902 gliders, gradually refining the performance and handling until they considered the aircraft was ready for market. Their process of refinement has been reconstructed in simulation within the Liverpool Wright project, highlighting the many important developments during a period when Wilbur and Orville’s own documentation was limited. Apart from their engineering excellence, the Wright brothers are to be acknowledged for their perseverance and resolve in overcoming setbacks, for their ability to innovate and to recover and learn from their mistakes. In many ways the Wright brothers represent a model for the modern aeronautical engineer, and it is hoped that their legacy will be better preserved through the documentation of this project.
Prediction of acoustic resonance phenomena for weapon bays using detached eddy simulation
Authors: Ashworth R. M.
Published: February 2016

It is argued that acoustic resonance phenomena in open cavities such as weapons bays cannot be adequately predicted through numerical solution of Reynolds averaged Navier-Stokes (RANS) equations. The requirement to resolve the growth of the shear layer instability from the lip of the cavity inevitably implies that turbulence further downstream is resolved while also being modelled thus making RANS over dissipative. Large eddy simulation (LES) models only unresolved scales and a hybrid method combining RANS near walls with LES in the cavity appears a practical alternative to pure RANS. This paper compares computations of the M219 cavity configuration made with unsteady RANS and with the hybrid method known as detached eddy simulation (DES). It is shown that whilst unsteady RANS and DES give very similar predictions for the 1st and 3rd modes of the acoustic resonance the 2nd mode (which is dominant near the centre of the cavity) is absent in the RANS results but well predicted by DES. The 2nd mode is thought to arise from an interaction with vortical structures in the shear layer which are suppressed in the highly dissipative RANS method. The 4th mode, which is much weaker than the other three modes, is over-predicted by DES and under-predicted by a smaller amount in RANS.
Impact of privatisation on the financial and economic performance of European airports
Authors: Vogel H.-A.
Published: February 2016

This paper assesses the financial performance of 35 European airports for the decade 1990 to 2000, comparing those subject to partial or full privatisation with those still in public ownership. In contrast to earlier research, the outcomes of partial factor productivity (PFP), financial ratio (FRA) and data envelopment analysis (DEA) are evaluated, in order to investigate differences attributable to the degree of privatisation. Changes in performance after a change in ownership structure are reviewed. The analysis of sample data reveals economically meaningful and statistically significant differences between publicly owned and privatised airports. The major differences lie in operating efficiency, capital productivity and capital structure. Although partially and fully privatised airports operate more efficiently, this does not translate into significantly higher returns on shareholders’ funds. Due to their at least indirectly government-backed credit standing, publicly owned airport companies can assume more debt relative to their respective equity. This results in considerably higher gearing and financial leverage, which compensates for the comparatively low return rate on assets.
Aerofoil profile and sweep optimisation for a blended wing-body aircraft using a discrete adjoint method
Authors: Moigne A. Le , Qin N.
Published: February 2016

Aerodynamic optimisations of a blended wing-body (BWB) aircraft are presented. A discrete adjoint solver is used to calculate efficiently the gradients, which makes it possible to optimise for a large number of design variables. The optimisations employ either a variable-fidelity method that combines low- and high-fidelity models or a direct sequential quadratic programming (SQP) method. Four Euler optimisations of a BWB aircraft are then presented. The optimisation is allowed to change a series of master sections defining the aircraft geometry as well as the sweep angle on the outer wing for two of the optimisations. Substantial improvements are obtained, not only in the Euler mode but also when the optimised geometries are evaluated using Reynolds-averaged Navier-Stokes solutions. Some interesting features of the optimised wing profiles are discussed.
Considerations for flight testing of UAVs in South African airspace
Authors: Ingham L. A. , Jones T. , Maneschijn A.
Published: February 2016

South Africa has strategic requirements for tasks such as maritime patrol and border control. Research on UAVs should be done in order to design, certify and operate UAVs in civil airspace to satisfy these requirements. If principles such as ‘equivalence’, initially proposed by Eurocontrol are to be adopted in South Africa, it then follows that similar standards used by manned aircraft should be used by UAVs. Similarly, because the process of creating UAV regulations has not kept up with the pace of UAV development, and because dedicated UAV regulations do not yet exist in South Africa, UAVs must be tested and evaluated in order to prove compliance with comparable manned aircraft regulations in the foreseeable future until regulations are created or modified to accommodate UAVs. Given the airspace restrictions, and lack of applicable standards and regulations, proper flight testing of UAVs can become a very specialised task. Most test techniques applied to testing of manned aircraft are fortunately equally applicable to UAVs. This is a research-based paper that provides guidance to flight testers, UAV developers and research organisations wishing to execute tests in South Africa by suggesting a number of considerations for testing of UAVs.
Numerical exploration of starting process in supersonic nozzle
Authors: Saha S. , Chakraborty D.
Published: February 2016

The starting process in a supersonic nozzle is numerically simulated. The Navier Stokes equations, in axisymmetric form, are solved using a higher order spatial and temporal accurate scheme. Good comparisons between experimental and numerical values of various flow parameters form the basis of further analysis. The insight of the starting process in the nozzle, namely, the movement of primary and secondary shocks and contact discontinuity, has been obtained through analysis of various flow parameters. It has been observed that the inviscid phenomenon is more predominant in the flow development process. Parametric studies have been carried out to determine the effect of nozzle divergence angle on the starting process.
Measuring the effect of helicopter rotors on GPS reception
Authors: Brodin G. J. , Cooper J. A. , Stevens J. R. A.
Published: February 2016

This paper describes an experiment which was performed using an offshore transport helicopter to investigate the impact of the rotor blades upon Global Positioning System (GPS) reception.

The test aircraft was fitted with two separate GPS antennas which were positioned to isolate the effects caused by the main and tail rotors. Testing was undertaken with the aircraft on the ground and this allowed an assessment to be performed at different rotor speeds with accurate control over the relative geometry between the antenna, rotors and satellites.

Recorded data from a measurement system incorporating three dissimilar GPS receivers (including a technical standard order (TSO)-C129() compliant aviation unit and a custom research receiver) was analysed to identify the effect of the rotors at the correlator level and to determine the impacts upon ranging accuracy, the availability of ranging measurements, and the receivers’ signal level estimates.

Correlation data was used to demonstrate that the rotor blades were capable of generating both destructive and constructive interference effects, and the periodic nature of these oscillations was shown to correspond directly to the blade passing frequency. It was identified that signal degradation was not limited to satellite signal paths which intersected the rotor discs.

No evidence was found for any increase in code measurement error due to the rotor interference, but it was demonstrated that there could be a significant impact upon a receiver’s ability to maintain continuous tracking of the satellite signals. The overall effect of this availability problem for a given installation and type of operation will be dependent upon satellite geometry and other factors which are beyond the scope of this study.

The ability of a receiver to identify the presence of rotor interference was investigated by examining estimates of carrier-to-noise, and this revealed inconsistencies between the results from different receivers implying differences in the estimation algorithms employed. It was also identified that two alternative ‘textbook’ estimators do not give identical results in the presence of rotor interference and it is suggested that such data should therefore be interpreted with caution.
Three-dimensional tensile stress concentration in countersunk rivet holes
Authors: Bhargava A. , Shivakumar K. N.
Published: February 2016

A detailed and accurate three-dimensional finite element stress analysis was conducted on countersunk rivet holes in a plate subjected to tension loading. The analysis included a wide range of countersunk depths, plate thicknesses, countersunk angles and plate widths. The study confirmed some of the previous results, addressed their differences, provided many new results, and investigated countersunk angle and width effects. Using the detailed FE results and the limiting conditions, a design equation for stress concentration was developed and verified.