bluuebunny/crossref_metadata_2025 huggingface dataset:
Applying joint traveltime and waveform inversion to image the Sichuan Basin, China
Authors: Li Ziang , Zhang Jie
Published: September 2019

We apply a joint first‐arrival traveltime and early‐arrival waveform inversion method to image complex near‐surface structures in the Sichuan Basin, China. The area includes rugged topography and large near‐surface velocity variations. Due to the near‐surface effects, it is difficult to produce high‐quality reflection images of the deep subsurface. First‐arrival traveltime tomography is often applied for near‐surface imaging, but the results may not be sufficiently accurate because of ray assumptions and the limited traveltime information. Waveform inversion should allow complex structures to be resolved; however, it may fall into local minima because of cycle skipping issues and may also produce artefacts in very shallow areas that are associated with rugged topography. Therefore, we combine the advantages of the two methods and mitigate their problems by performing joint inversion of the two types of data. We demonstrate the effectiveness of the joint inversion method using synthetic and real data from Sichuan, China. In the real data example, we compare the velocity models resolved from waveform inversion alone with those resolved from the joint inversion. We calculate long‐wavelength static corrections and apply them to the data processing. The common midpoint stacking results show that the joint inversion method produces a more effective statics solution.
Focusing on soil‐foundation heterogeneity through high‐resolution electrical and seismic tomography
Authors: Cercato Michele , De Donno Giorgio
Published: September 2019

The reconstruction of the current status of a historic building is essential for seismic safety assessment and for designing the retrofitting interventions since different safety and confidence factors have to be assumed, depending on the level of information about the subsoil structure. In this work, we present an investigation of the shallow subsurface below and around a historic building affected by differential settlements in order to define its geometry and to characterise its stiffness at low strain. To this end, we employed high‐resolution electrical resistivity and seismic (both P‐wave and S‐wave) tomographies. A three‐dimensional electrical resistivity tomography survey was performed to obtain more information about the type and the maximum depth of the building foundation. Electrical resistivity and seismic tomographies were carried out alongside the building, aimed at imaging the top soils and the near‐surface geometry. The corresponding inverted models pointed out a remarkable heterogeneity of the shallow subsoil below the building, which is partly founded on a weathered layer and partly on a more rigid lithotype. This heterogeneity is probably a concurrent cause of the building’s instability under both static and seismic loading. Our results demonstrate that the man‐made fillings and the top soils have to be thoroughly investigated to fully understand the soil‐structure behaviour. In this light, the integration of non‐invasive high‐resolution geophysical techniques, especially tomographic methods, has been proved to properly address the problem of imaging the shallow subsoil.
Modelling of high‐resolution aeromagnetic data to decipher structural deformation in parts of Kaladgi basin, Peninsular India
Authors: Muthyala Sridhar , Yalla Harsha , Maurya Ashwini K. , Chaturvedi Anand K.
Published: September 2019

We show the effectiveness of forward and inversion modelling of high‐resolution magnetic data in deciphering the geological framework in a polydeformed Proterozoic Kaladgi basin. The Meso to Neo Proterozoic Kaladgi basin exposes platformal sediments in the northern margin of Dharwar Craton, Peninsular India. The study of high‐resolution magnetic data over Deshnur locality suggests two prominent trends NW–SE and NE–SW, followed by two minor trends of E–W and N–S. Analysis of the magnetic anomalies aided in understanding the succession of deformation events and their impact over sedimentation. The NW–SE trending Nalur shear zone marks the western contact between the Chitradurga Schist belt and Peninsular gneisses that are traced beneath the Badami sediments. The forward model suggests that the NE–SW trending block faulting resulted in generating a series of Horst and Graben structures. Three‐dimensional compact inversion of circular features bearing remanent magnetisation indicates elliptical‐shaped pipe‐like bodies. The three‐dimensional inversion of magnetic data implied thicker sediments within these Graben structures. The basement configuration depicted as elevation of magnetic basement corroborates these three‐dimensional inversion results. The derived results are validated by drill holes, and the intercepts substantiate the inferred structural setup over the study area. Available drill hole and magnetic data interpretation are combined with field information to reconstruct the tectonostratigraphy and the architecture of the Kaladgi basin around Deshnur locality.
The competing effects of stress and water saturation on in situ Q for shallow (< 1 m), unconsolidated sand, evaluated with a modified spectral ratio method
Authors: Crane James M. , Lorenzo Juan M. , Shen Jie , White Chris D.
Published: September 2019

A publicly available seismic dataset from a lab experiment shows the dependence of quality factor simultaneously on water saturation and stress in unconsolidated sand. Large gradients (e.g., > 10 m−1) necessitate a spectral ratio method modified to assume that Q changes with each ray path, thereby eliminating false values (e.g., < 0). Interval values increase the most with depth and stress in dry sand and the least in partially saturated sand ( and ) where attenuation created by local fluid flow reaches a maximum. Expected values can be extrapolated from and are bounded by of the dry and partially saturated media (e.g., ). deviations outside this range may be explained by changes in effective stress, attenuation mechanism, or sediment composition. Field estimation of seismic attenuation in natural settings may be helped by these constraints, although attenuation remains subject to careful consideration of other factors, e.g., grain size, sorting, and shape.
Specific polarizability of sand–clay mixtures with varying ethanol concentration
Authors: Sharma Sundeep , Slater Lee , Ntarlagiannis Dimitrios , Werkema Dale , Szabo Zoltan
Published: September 2019

We utilise a concept of specific polarizability , represented as the ratio of mineral‐fluid interface polarization per pore‐normalised surface area , to demonstrate the influence of clay‐organic interaction on complex conductivity measurements. Complex conductivity measurements were performed on kaolinite‐ and illite‐sand mixtures as a function of varying ethanol (EtOH) concentration (10% and 20% v/v). The specific surface area of each clay type and Ottawa sand was determined by nitrogen‐gas‐adsorption Brunauer‐Emmett‐Teller method. We also calculated the porosity and saturation of each mixture based on weight loss of dried samples. Debye decomposition, a phenom‐enological model, was applied to the complex conductivity data to determine normalised chargea‐bility . Specific polarizability estimates from previous complex conductivity measurements for bentonite‐sand mixtures were compared with our dataset. The for all sand–clay mixtures decreased as the EtOH concentration increased from 0% to 10% to 20% v/v. We observe similar responses to EtOH concentration for all sand–clay mixtures. Analysis of variance with a level of significance suggests that the suppression in responses with increasing EtOH concentration was statistically significant for all sand–clay mixtures. On the other hand, real conductivity showed only 10% to 20% v/v changes with increasing EtOH concentration. The estimates reflect the sensitivity of complex conductivity measurements to alteration in surface chemistry at available surface adsorption sites for different clay types, likely resulting from ion exchange at the clay surface and associated with kinetic reactions in the electrical double layer of the clay‐water‐EtOH media. Our results indicate a much larger influence of specific surface area and ethanol concentration on clay‐driven polarization relative to changes in clay mineralogy.
The effect of compaction on complex electrical resistivity of shaly sands
Authors: Börner Frank , MüllerHuber Edith , Branka Daniel , Rücker Carsten
Published: September 2019

Pore space properties of sedimentary rocks are of fundamental importance with regard to reservoir evaluation and fluid flow modelling or special geotechnical applications such as stability considerations for reservoirs, dams, or embankments. Processes such as compaction due to pressure drawdown in weakly consolidated reservoirs, effects caused by stimulation of reservoirs with decreasing productivity, or the compaction of building ground can be effectively studied by verifying and monitoring changes in porosity. The close connections between electrical resistivity or conductivity and pore space geometry as well as a high sensitivity to even slight changes in pore space characterising parameters are well‐established.

Therefore, the results of complex electrical conductivity measurements in the frequency range from 0.05 Hz to 1 kHz on a set of heterogeneous shaly sand samples during increasing compaction are presented in this study. The major objective of these investigations was to quantify the porosity reduction in shaly sands during the step‐wise compaction of the samples in a specially designed measurement cell. Overall, ten unconsolidated shaly sand samples with varying grain size distribution were analysed. In addition, selected shaly sandstone data are presented to enhance the observations made for the sand samples with regard to the potential influence of cementation as expressed by the cementation exponent.

With increasing compaction, the measured complex conductivity data of the fully water‐saturated samples show two co‐occurring effects. On the one hand, the real part decreases due to the dominating effect of Archie’s law. On the other hand, the imaginary part increases due to the increasing contribution of interface conductivity. This effect is due to an increase in the internal surface‐area‐to‐porosity ratio. Cementation exponent and the considered porosity range seem to be controlling the magnitude of this effect. These observations may be explained by using a simple complex conductivity model that relates conductivity components to porosity, specific surface area, and cementation exponent. An interpretation algorithm is proposed that allows determining relative porosity variations based on a baseline and a single repeat measurement without prior knowledge of further rock characteristics.

To demonstrate the applicability of the algorithm on field measurements, data from spectral induced polarization soundings obtained at a test site for compaction techniques were interpreted. It could be shown that these observations bear further potential for enhancing the prediction of porosity, changes of compaction, and, hence, changes in hydraulic permeability.
Integration of upward GPR and water content reflectometry to monitor snow properties
Authors: Godio Alberto , Frigo Barbara , Chiaia Bernardino , Maggioni Paola , Freppaz Michele , Ceaglio Elisabetta , Dellavedova Paola
Published: September 2019

We adopt upward ground‐penetrating radar (up‐GPR) and water content reflectometry sensors to monitor the seasonal behaviour of snow density. Upward ground‐penetrating radar permitted observation at a single fixed station the time‐lapse response of the electromagnetic signal at the main frequency of 1500 MHz, with the antenna radiating upward from the soil toward the snow surface. Measurements have been performed at a test site on the Italian Alps (at an elevation of about 2100 m above sea level) during the 2014–2015 winter season at an interval of 30 minutes. The data processing of radar data involved the travel‐time picking and the conversion into snow depth and density. Water content reflectometry measurements have been useful in order to calibrate the radar response and retrieve information on the presence of liquid water content. The integration of upward ground‐penetrating radar and water content reflectometry technology allows us to infer snow high and layering, snow density changes during the winter season, and a preliminary estimate of the liquid water content. For snow in dry condition, we are able to estimate density values through mixing rules or polynomial formula. Snow density varies during the season in a range between 250 kg/m3 and 450 kg/m3; the results are in good agreement with the results of the ground truth. For snow in wet condition, the residuals of the electrical permittivity, after a trend removal on the original water content reflectometry data, permitted to estimate liquid water content in the range between 3% and 5%, during some periods of the winter season, according to warmer climate condition.

Snow layering and densification processes are monitored by the response of upward ground‐penetrating radar: fast phenomena such as wetting front infiltration can be also pointed out even if they appear challenging if other observations are not available (e.g., monitoring with water content reflectometry).
Geophysical and geochemical characterisation of a site impacted by hydrocarbon contamination undergoing biodegradation
Authors: Abbas Mohamad , Jardani Abderrahim , Machour Nadine , Dupont Jean‐Paul
Published: September 2019

Hydrocarbon contamination, which can alter the physiochemical and biological properties of the subsurface, can be monitored by using geochemical analyses and integrated geophysical techniques. Electrical resistivity tomography, induced polarization, ground‐penetrating radar, and self‐potential methods were used in this work to characterise the hydrocarbon contamination and investigate the geoelectrical properties of a site impacted by an aged hydrocarbon plume. Throughout the investigation, geoelectrical measurements supported the conductive plume model and consistently recorded low‐resistivity anomalies and high‐chargeability values in the contaminated aquifer. Furthermore, the low‐resistivity anomalies were found to be coincident with regions of ground‐penetrating radar attenuated reflections and significant negative self‐potential anomalies associated with oxidation–reduction processes. These findings were supported by the geochemical measurements, which revealed depleted concentrations of terminal electron acceptors (TEAs) and elevated amounts of ions and total dissolved solids, which could be attributed to bacterial biodegradation of hydrocarbons. The study showed that biological alterations of hydrocarbon‐induced subtle changes in the pore water biogeochemistry, which consequently modified the geophysical properties of the contaminated sediments. Based on these observations, the extent of groundwater contamination was delineated according to the geophysical contrast between the contaminated and clean zones. The combination of different geophysical methods constrained by geochemical point measurements provided insight on the different processes that might have modified the soil and groundwater biogeochemical properties.
De l’expérimentation des innovations pédagogiques numériques à leur généralisation en France
Authors: Dulbecco Philippe
Published: September 2019

Les universités françaises sont nombreuses à avoir ouvert le chantier de la transformation pédagogique et numérique avec des équipes d’abord pionnières, aujourd’hui rejointes par un plus grand nombre d’enseignants-chercheurs. Le risque est fort toutefois que cette nouvelle étape de développement des innovations pédagogiques numériques au sein des universités ne permette pas d’atteindre l’objectif poursuivi, celui du passage de l’expérimentation à la généralisation. L’article souligne les fondamentaux de la transformation (la temporalité, le portage politique, l’appropriation par les acteurs et les usagers) et décrit les mesures d’accompagnement nécessaires en termes d’organisation, de pilotage et d’administration des établissements concernés.
Des centres pour le développement de l’enseignement et de l’apprentissage dans les universités chinoises de recherche
Authors: Wu Fan
Published: September 2019

La mise en place de centres pour le développement pédagogique ayant pour but de promouvoir l’excellence des professeurs en matière d’enseignement dans les universités de recherche est considérée comme étant l’une des approches les plus importantes de la construction de l’identité de l’enseignement supérieur en Chine. L’étude du cas du Centre pour le développement de l’enseignement et de l’apprentissage (Center for Teaching and Learning Development : CTLD) au sein de l’Université de Xiamen permet d’illustrer les problèmes à résoudre et les défis à relever, les programmes et les services efficaces ainsi que les principes et les pratiques pertinents que l’on peut retirer de l’expérience du CTLD. Cette étude de cas montre également comment, lorsque la mission, la gestion et la programmation de ces centres sont bien adaptées aux différentes facettes d’une université de recherche, un tel centre pour le développement pédagogique est au service de la création d’une culture de l’excellence en matière d’enseignement.
Modelisation and Simulation of Cgs.op and Cgd.op Capacities of GaAs MESFETs OPFET
Authors: Hamma Issam , Farh Hichem , Ziar Toufik , Said Yasmina , Cherifa Azizi
Published: September 2019

An analytical of new theoretical model has been developed to study the Capacitance characteristics for an optically controlled Gallium Arsenic Metal Semiconductor Field Effect Transistor MESFET (OPFET) doped uniformly. The model takes the effects of photoconductive and photovoltaic into account that determine the device characteristics in the illuminated condition. It has been presented here for an analysis of extrinsic and intrinsic parameters such as, gate capacitances including both of the gate-source capacitances gate-drain capacitances under dark and illumination condition. The numerical results have also been compared with the reported data experience in the literature and a good agreement is observed.
Structural and Anisotropic Elastic Properties of Hexagonal YMnO3 in Low Symmetry Determined by First-Principles Calculations
Authors: Chadli Abdelhakim , Halit Mohamed , Lagoun Brahim , Mohamedi Ferhat , Maabed Said , Cheriet Abderrahmane , Hlil Elkebir , Farh Hichem
Published: September 2019

The structural, elastic and anisotropic properties for rare earth manganites compound YMnO3 in ferromagnetic state with hexagonal structure, have been investigated using the ab initio calculations based on the density functional theory, this calculations were based on the full potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA). The agreement of the DFT (FP-LAPW) calculations including internal atomic relaxations, with the experimental data is very good. Other relevant quantities such as elastic constants, shear modulus, Young’s modulus, Poisson’s ratio, anisotropy factors, sound velocity, and Debye temperature have been calculated and discussed.
First-Principles Study of Structural, Electronic, Optical and Elastic Properties of Cadmium Based Fluoro-Perovskite MCdF3 (M= Rb, Tl)
Authors: Cheriet Abderrahmane , Lagoun Brahim , Halit Mohamed , Zaabat Mourad , Abdelhakim Chadli , Hamza Lidjici
Published: September 2019

This paper presents a theoretical study using the full potential linearized augmented plane wave approach (FP-LAPW) based on the density functional theory (DFT) to predict the structural and electronic properties of RbCdF3 and TlCdF3 compounds. The exchange-correlation potential is treated by the local density approximation (LDA), generalized gradient approximation (GGA) and modified Beck-Johnson exchange potential (mBJ). The calculated structural properties such as the equilibrium lattice parameter, the bulk modulus and its pressure derivative are in good agreement with the available data. The obtained results for the band structure and the density of states (DOS) show that the RbCdF3 (TlCdF3) compound have an indirect band gap of 6.77 and 3.07 eV (5.70 and 3.66 eV) with TB-mBJ and WC method respectively. From the electronic transition from valence conduction bands to conduction bands the optical properties were calculated. The elastic constants were calculated using the energy deformation relationship, from these constants the other mechanical properties such as bulk modulus, shear modulus, Young modulus and Poisson ratio were calculate and comment. Lastly, the elastic anisotropy was discussed.
Possible Bose-Einstein Condensation of Polygonal Clusters in 2D-Materials
Authors: Boudiar Abid
Published: September 2019

This study investigates the possibility of Bose-Einstein condensation (BEC) in 2D-nanoclusters. A ground state equilibrium structure involves the single phonon exchange approximation. At critical temperature, the specific heat, entropy, and free energy of the system can be determined. The results support the existence of BEC in nanoclusters, and they lead to predictions of the behaviour of 2Dmaterials at low temperatures.
Electronic and Elastic Properties of TlX (X = N, P, As and Sb) in Zinc-Blende Structure
Authors: El Hassasna Amira , Bechiri Abderrachid
Published: September 2019

In this work we investigated the structural, electronic and elastic properties of TlN, TlP, TlAs and TlSb compounds in the zinc-blende phase, the lattice parameter, bulk modulus, band structure, and elastic constants have been calculated by employing the full potential linearized augmented plane wave method based on density functional theory of the exchange-correlation potentials including local density approximation, PBE generalized gradient, and Wu-Cohen generalized gradient are used. Furthermore, the modified Backe-Johnson (mBJ) potential has been utilized for the calculation of the energy gap. The present results are compared with other available theoretical values obtained.
Computational Analysis and Flow Physics of a Ducted Rotor in Edgewise Flight
Authors: Misiorowski Matthew P. , Gandhi Farhan S. , Oberai Assad A.
Published: September 2019

This study examines the performance of the ducted rotor in hover and edgewise flight conditions. The flow over a threedimensional model of a ducted rotor was simulated using the Spalart–Allmaras Reynolds-averaged Navier–Stokes model implemented in a stabilized finite element
method. A sliding mesh was used to conveniently account for the large-scale motion associated with rotor revolutions. The simulation results were analyzed to understand the flow physics and quantify the contributions of the rotor and various sections of the duct interior surfaces on the total
aerodynamic forces (thrust, drag, and side force) and moments (pitching and rolling). In edgewise flight, freestream flow separates off the front of the duct inlet, causing a region of recirculating flow and upwash in the rotor plane. The upwash region biases rotor thrust production to the
front of the disk. The swirl velocity further biases the region of flow separation over the inlet and upwash at the front of the rotor toward the retreating side of the disk. The shift of thrust production on the rotor and duct toward the front produces a strong nose-up pitching moment on
the ducted rotor. The rear of the diffuser is a significant contributor to the total drag; this force includes a nose-down pitch moment, which partially negates the moment from the duct inlet. The rotor is the primary source of vertical vibratory forces as well as vibratory pitching and rolling
moments. The small tip clearance of the rotor causes a local interaction between the blade tip and duct that is the dominant contributor to in-plane vibratory forces on the ducted rotor.
Coupled and Multimode Tailboom Vibration Control Using Fluidic Flexible Matrix Composite Tubes
Authors: Krott Matthew J. , Smith Edward C. , Rahn Christopher D.
Published: September 2019

This paper covers the modeling and testing of a helicopter tailboom integrated with a fluidic flexible matrix composite (F2MC) damped vibration absorber. In an advance over previous work, the F2MC absorber presented in this paper treats a combination of tailboom
lateral, torsional, and vertical vibrations. A finite element structural model of a laboratory-scale tailboom is combined with a model of attached F2MC tubes and a tuned fluidic circuit. Vibration reductions of over 75% in a coupled 26.8-Hz lateral bending/torsion tailboom mode
are predicted by the model and measured experimentally. These results demonstrate that F2MC vibration control is viable at higher frequencies and for more complex vibration modes than previous research had explored. A new absorber with a fluidic circuit that targets two tailboom
vibration modes is designed and experimentally tested. On the lab-scale tailboom testbed, the absorber with this circuit is shown to provide vibration reductions of over 60% in both a 12.2-Hz vertical mode and a 26.8-Hz lateral bending/torsion mode. Using this new absorber, vertical and lateral/torsion
mode damping are achieved with almost no added weight relative to a purely vertical absorber.
The Importance of Financial Recession for Mental Health among Students: Short- and Long-Term Analyses from An Ecosocial Perspective
Authors: Hammarström Ann , Virtanen Pekka
Published: September 2019

Background and aim

Referring to the ecosocial theory and utilising the ‘natural experiment’ setting provided by the global recession at the beginning of 1990s, the aim of our study was to analyse the short- and long-term associations between trade and mental health in young students followed until mid-adulthood.

Method

The study was based on two prospective cohort studies, the older and the younger Northern Swedish Cohort which both consisted of all pupils in a middle-sized industrial town in Northern Sweden. At age 21, the younger cohort entered the labour market during the deep recession of the early 1990s, while the older cohort entered the labour market during the boom of the 1980s. Both cohorts were followed up with a high response rate in mid adulthood. For this study, all students were selected at age 21.

Results

At age 21, those who studied during recession had more depressive and functional somatic symptoms than those who studied during boom. The cohort differences did not remain over age: by the follow-up in early middle age the differences between the cohorts were non-significant, most notably due to decreased depressive symptoms in the younger cohort and increase of functional somatic symptoms in the older cohort.

Conclusions

The short-term mental health consequences of the business cycle seem to be more extensive than limited only to those who are unemployed, even though the possible long-term consequences seem to be more complex. Thus, the macrolevel had a great short-term impact on the individual level in relation to the microlevel setting of university/school. The chronosystem was also of major importance. Future research would benefit from taking the context into account.
Factors hindering midwives’ utilisation of alternative birth positions during labour in a selected public hospital
Authors: Musie Maurine R. , Peu Mmapheko D. , Bhana-Pema Varshika
Published: September 2019

Background: An evidence-based practice suggests that the birth position adopted by women during labour has a significant impact on the maternal and neonatal birth outcomes. The birth positions are endorsed by guidelines of maternity care in South Africa, which documented that women in labour should be allowed to select the birth position of their choice, preferably alternative birth positions (including upright, kneeling, squatting and lateral positions) during labour. Thus, the lithotomy birth position should be avoided. However, despite available literature, midwives routinely position women in the lithotomy position during normal vertex births, which causes several adverse maternal outcomes (namely prolonged labour, postpartum haemorrhage) and adverse neonatal outcomes (such as foetal asphyxia and respiratory compromise).Aim: The aim was to explore and describe factors hindering midwives’ utilisation of alternative birth positions during labour in a selected public hospital.Setting: A public hospital in the Tshwane district, Pretoria were used in the study.Methods: This study used the qualitative, exploratory and descriptive research design. This design gathered quality information on factors hindering midwives’ utilisation of alternative birth positions during labour in a selected public hospital.Results: The study revealed the following themes: (1) midwives’ perceptions on alternative use of birth positions and (2) barriers to utilisation of alternative birth positions. The themes were discussed and validated through the use of a literature review.Conclusion: The lack of skills and training during the midwifery undergraduate and postgraduate programme contributes to the midwives being incompetent to utilise alternative birth positions during clinical practice.
Negative curvature in automorphism groups of one-ended hyperbolic groups
Authors: Genevois Anthony
Published: September 2019

In this article, we show that some negative curvature may survive when taking the automorphism group of a finitely generated group. More precisely, we prove that the automorphism group

\mathrm{Aut}(G)

of a one-ended hyperbolic group

G

turns out to be acylindrically hyperbolic. As a consequence, given a group

H

and a morphism

\varphi : H \to \mathrm{Aut}(G)

, we deduce that the semidirect product

G \rtimes_\varphi H

is acylindrically hyperbolic if and only if

\mathrm{ker}(H \overset{\varphi}{\to} \mathrm{Aut}(G) \to \mathrm{Out}(G))

is finite.
Design Approach for Secure Networks to Introduce Data Analytics within the Aircraft Cabin
Authors: Hintze Hartmut , Giertzsch Fabian , God Ralf
Published: September 2019

In the past, aircraft network design did not demand for information security considerations. The aircraft systems were simple, obscure, proprietary and, most importantly for security, the systems have been either physically isolated or they have been connected by directed communication links. The union of the aircraft systems thus formed a federated network. These properties are in sharp contrast with today’s system designs, which rest upon platform-based solutions with shared resources being interconnected by a massively meshed and shared communication network. The resulting connectivity and the high number of interfaces require an in-depth security analysis as the systems also provide functions that are required for the safe operation of the aircraft. This network design evolution, however, resulted in an iterative and continuous adaption of existing network solutions as these have not been developed from scratch. Now, with the upcoming trend of data analytics and artificial intelligence applications, which demand for an extensive availability of data, holistic aircraft cabin networks are necessary to satisfy the associated requirements. For the development of such networks this paper proposes a novel design approach that includes security considerations as an integral part rather than as an isolated activity. The approach does not restrict itself to a specific class of network architectures, but takes the complete solution space into account. The resulting design decisions are based multiple classes of requirements, namely functional requirements such as the communication need and security requirements, e.g. the unwanted remote controlling of system functions by injecting incorrect information as well as the contract-based data exchange.
Design and Experimental Verification of a High Force Density Tubular Permanent Magnet Linear Motor for Aerospace Application
Authors: Kano Yoshiaki , Satou Kousuke
Published: September 2019

This paper presents the design and construction of a high force density tubular permanent-magnet (PM) linear motor. A strut structure of a tubular PM linear motor developed to improve resistance to impurities and structural rigidity is described.

In the design, computationally efficient two-dimensional finite-element analysis is used to estimate the motor force density. The motor’s design is optimized for the major pole number/slot number combinations of 8/24, 16/24, 20/24, 28/24, 32/24, and 40/24. The optimized motor design of a three-phase 16/24 combination with one-layer winding achieved the highest force-to-mass density. The force-to-mass density of the designed motor is higher than that of the first prototype motor by a factor of 5. The validity of the proposed design method and the expected drive characteristics are experimentally verified using the prototype.
A Study of the Disc Scoring Generation Principle and Reduction(III)
Authors: Jeong ByeongUk , Ryu Hyoung Tae , Jung Kwang Ki , Kim Chang Jin , Lee Hyunkyoung
Published: September 2019

In the latest works [12], we presented the guideline for reducing Metal pick up(MPU, the main component of disc scoring) by controlling the location of the roughness of disc, the brake pad friction coefficients and the disc slot's size. In this study, the previously studied iron transfer theory to 'Cu free' brake pad and the disc surface roughness controlling methods which are based on the mass production manufacturing process are applied. It is possible to suggest the ways to improve the scoring-free disc without reducing friction coefficient between the disc and pad, and any demerit such as increased wear and airplane noise like conventional slot discs [11].
Benefits and Application Bandwidth of Phenolic Piston Material in Opposed Piston Calipers
Authors: Antanaitis David B. , Ciechoski Chris , Riefe Mark
Published: September 2019

The use of reinforced phenolic composite material in application to hydraulic pistons for brake calipers has been well established in the industry - for sliding calipers (and certain fixed calipers with high piston length to diameter ratios). For decades, customers have enjoyed lower brake fluid temperatures, mass savings, improved corrosion resistance, and smoother brake operation (less judder). However, some persistent concerns remain about the use of phenolic materials for opposed piston calipers. The present work explores two key questions about phenolic piston application in opposed piston calipers. Firstly, do opposed piston calipers see similar benefits? Do high performance aluminum bodied calipers, where the piston may no longer be a dominant heat flow path into the fluid (due to a large amount of conduction and cooling enabled by the housing), still enjoy fluid temperature reductions? Are there still benefits for judder with the much shorter length to diameter ratio the pistons have in these applications? Secondly - it is clear that the much shorter length to diameter ratio of the piston in opposed piston calipers will result in significant increases in contact stress on the piston material at its contact points to the bore, when it is pressurized against pads with significant taper wear - will the phenolic material have adequate durability to withstand this? Can a simple “application guideline” for phenolic pistons be defined, potentially based on piston diameter (governing peak clamp load) and length to diameter ratio (which determines the correlation between clamp load and contact stress in the piston material at the bore contact points)? To address the first question, a battery of comparative tests was run on a high performance 6 piston aluminum-bodied brake calipers with high performance low-metallic brake pads and a large 18” wheel envelope two piece, cast iron plate and aluminum hub rotor. Fluid consumption, drag, brake torque variation, and fluid temperatures were measured through tests designed to exercise these behaviors, with both the production aluminum pistons and prototype phenolic piston calipers. The second question was explored through lab-based durability testing, abusive inertia dyno testing, and analysis of parts failed during testing. Pistons of the same phenolic material (Durez 29504B) were prototyped in opposed-piston caliper configurations in two sizes (51mm and 34mm) and tested to failure. The analysis of the data changed the authors’ initial thinking substantially about the failure mechanics of the piston in severe use, but still resulted in a simple, free body diagram based application guideline and a clear path for future work.
Lightweight Wheel Bearing with Dissimilar Materials for Vehicle
Authors: Lee Inha , Lee Seonho , Shim Heechan , Lee Jaehee , Hong Sung-Tae , Park Jungyang
Published: September 2019

Limited fossil fuel resources, air pollution, and global warming all drive strengthening of fuel economy and vehicle emission standards globally. Much R&D continues to be dedicated to improve fuel efficiency of automobiles and to reduce exhaust gasses. These include improvement of engine/driveline performance for higher efficiency, development of alternative energy, and minimization of air resistance through aerodynamic design optimization. OEM weight reduction-focused research has extended into chassis components (steering knuckle, brakes, control arms, etc.) in sequence from body-in-white(BIW). Wheel bearings, one of the core components of a driveline and part of a vehicle’s unsprung mass, are also being required to reduce weight. Conventionally, wheel bearings have achieved “lightweighting” primarily through design optimization methods. They have been highly optimized today using steel based materials. Opportunities for further mass optimization are increasingly limited and so the focus of this study is integration of lighter-materials into steel bearing components for weight savings. Both aluminum and CFRP were considered in the study for partial integration into the steel hub flange which interfaces directly with the wheel. The application of lightweight materials was targeted on the specific area of the hub which is relatively less affected by impact loads. Hot forging and compressive molding were applied to induce denser bonding of the dissimilar materials. The slope angle design having an inverse draft at the combined boundary was applied to reinforce physical bonding and to enhance joint integrity. In addition, a Zinc-based coating was partially applied on the surface of the combined boundary to protect against galvanic corrosion between dissimilar materials. Bearings containing the new composite hubs achieved a 20% weight reduction compared to conventional wheel bearings made of full steel.
Study on Application Methods to Mitigate Galvanic Corrosion between Wheel Bearing and Aluminum Knuckle
Authors: Kim Sewoong , Lee Seonho , Park Hyounsoo
Published: September 2019

The substitution of aluminum for steel is an effective weight reduction solution where the application permits it; aluminum knuckles have been widely used for this reason. However, when an aluminum knuckle is assembled with the steel outer-ring of a wheel bearing without any means for galvanic corrosion prevention, the aluminum knuckle may severely corrode. Galvanic corrosion products can make it difficult to remove a wheel bearing from the aluminum knuckle during vehicle maintenance. Prevention of this problem is the focus of this paper. In this study, several concepts were examined to prevent or mitigate galvanic corrosion between a wheel bearing and its mating aluminum knuckle. One set of concepts involves using surface treated metal sleeves (using ferritic nitro-carburizing or a special coating). The sleeves were then inserted onto the outer-ring diameters of the wheel bearings prior to assembly into the steering knuckle. Another set of concepts that were investigated involves the application of thin coatings having high anti-corrosion properties. The coatings were applied directly to the bearing outer-ring knuckle piloting surfaces and bearing knuckle mounting flange. Samples were subjected to rigorous cyclic and galvanic corrosion tests. Test results for some concepts showed mitigation of galvanic corrosion between the knuckle and bearing.
Association of Doximity Ranking and Residency Program Characteristics Across 16 Specialty Training Programs
Authors: Feinstein Max M. , Niforatos Joshua D. , Mosteller Lauretta , Chelnick David , Raza Syed , Otteson Todd
Published: September 2019

Background

Residency program prestige is an important variable medical students consider when creating their rank list. Doximity Residency Navigator is a ranking system that previous reports have shown significantly influences medical student application decisions. Doximity's use of peer nomination as a central component of its methodology for determining program rank has drawn criticism for its lack of objectivity. Doximity has not published information regarding how peer nomination and more objective measures are statistically weighted in reputation calculation.

Objective

This study assesses whether a strong negative correlation exists between residency program size and Doximity ranking.

Methods

A cross-sectional study of Doximity residency rankings from the 2018–2019 academic year was conducted. Data extracted from Doximity included program rank, size, and age. Data were additionally collected from the Blue Ridge Institute for Medical Research, National Institutes of Health, funding in 2018 and the US News & World Report Best Medical Schools 2019–2020. A multivariable linear regression model was used that included Doximity ranking as the outcome variable and residency program size as the predictor variable with adjustment for the aforementioned variables.

Results

Sixteen of the 28 specialties on Doximity were included in the analysis, representing 3388 unique residency programs. After adjustment for covariates, residency program size was a significant predictor of Doximity ranking (β = -1.84; 95% CI -2.01 to -1.66, P < .001).

Conclusions

These findings support the critique that the Doximity reputation ranking system may favor larger residency programs. More transparency for Doximity reputation ranking algorithm is warranted.
Carlos Nelson Coutinho e o processo de desenvolvimento do capitalismo no Brasil
Authors: Massuia Rafael Da Rocha
Published: September 2019

O presente texto propõe a discussão da concepção formulada por Carlos Nelson Coutinho para compreender o processo de desenvolvimento do capitalismo no Brasil. Para tal intento, o pensador baiano recorre a dois conceitos, que conjuga em uma proposta interpretativa singular: da noção “via prussiana”, como formulada por Lenin (e retomada por G. Lukács), ao conceito de “revolução passiva”, como proposto por A. Gramsci. A partir desse aporte teórico, Coutinho investiga o caráter “conservador” do desenvolvimento do capitalismo no país, referendado pela aliança entre os principais setores das classes dominantes (do “velho” ao “novo”), que tem por consequência uma ampla ruptura entre nação e povo. Nesse sentido, realizaremos algumas considerações sobre a atualidade da proposta interpretativa coutianiana para a compreensão do Brasil contemporâneo.
Segurança Nacional e anticomunismo no Brasil pré-64: a ideologia de Golbery do Couto e Silva
Authors: Neves Júnior José Wilson Assis
Published: September 2019

O artigo analisou a configuração do pensamento anticomunista brasileiro no período que precedeu o golpe militar de 1964. Foi selecionada como fonte de pesquisa, a obra completa do general Golbery do Couto e Silva intitulada “Geopolítica e Poder”, em decorrência do seu protagonismo no intelectualismo militar nas décadas de 1950-80. Utilizando o método de análise lukácsiana da ideologia, inserida na perspectiva teórica do materialismo histórico-dialético, o artigo se encontra dividido em dois momentos. Primeiro são apresentados os nódulos temáticos da ideologia golberyana, classificados a partir da concepção do autor. Em seguida é realizada a definição da gênese pensamento e da função social do autor. Buscou-se explicitar a forma como a lógica de reprodução do capitalismo brasileiro, condicionou, e limitou, o desenvolvimento das formulações do ideólogo militar.
SEMANTIC ROAD SCENE KNOWLEDGE FOR ROBUST SELF-CALIBRATION OF ENVIRONMENT-OBSERVING VEHICLE CAMERAS
Authors: Hanel A. , Stilla U.
Published: September 2019

Abstract. Environment-observing vehicle camera self-calibration using a structure from motion (SfM) algorithm allows calibration over vehicle lifetime without the need of special calibration objects being present in the calibration images. Scene-specific problems with feature-based correspondence search and reconstruction during the SfM pipeline might be caused by critical objects like moving objects, poor-texture objects or reflecting objects and might have negative influence on camera calibration. In this contribution, a method to use semantic road scene knowledge by means of semantic masks for a semantic-guided SfM algorithm is proposed to make the calibration more robust. Semantic masks are used to exclude image parts showing critical objects from feature extraction, whereby semantic knowledge is obtained by semantic segmentation of the road scene images. The proposed method is tested with an image sequence recorded in a suburban road scene. It has been shown that semantic guidance leads to smaller deviations of the estimated interior orientation and distortion parameters from reference values obtained by test field calibration compared to a standard SfM algorithm.
STATISTICAL ANALYSIS OF AIRBORNE IMAGERY COMBINED WITH GIS INFORMATION FOR TRAINING DATA GENERATION
Authors: Häufel G. , Bulatov D. , Helmholz P.
Published: September 2019

Abstract. In recent years, the task of land cover classification from airborne image and elevation data advanced considerably due to enhanced applicability of CNNs (Convolutional Neural Networks). Nevertheless, CNNs require a huge amount of training data. Traditionally, few essential feature values, such as elevation or vegetation index, had been chosen to provide a coarse distinction of classes, but very often these values have to be adapted depending on the imagery. To improve this process, freely available GIS data are combined with spectral and spatial features (and their variations) following the K-Means and Mean-Shift algorithm. Based on cluster assignments to pixels, statistical analysis for extracting plausible values for distinguishing between land cover classes is applied. The resulting labeled databases are evaluated using ground truth data, and will form the basis for the training data required for CNNs.
EVENTS RECOGNITION FOR A SEMI-AUTOMATIC ANNOTATION OF SOCCER VIDEOS: A STUDY BASED DEEP LEARNING
Authors: Kazi Tani L. F. , Ghomari A. , Kazi Tani M. Y.
Published: September 2019

Abstract. In this work, we propose an efficient way of web video annotation in soccer domain. To achieve this, it is necessary to enjoy different architectures of deep learning. We aim at realising a system of annotation able to recognise several events from information of the object that is the ball in our case, in order to fuse them as a part of actions in video. We propose to use Deep Neural Network (DNN) to detect ball and actions. However, Mask R-CNN can play a very important role for features extracted as an output using a training network on ImageNet dataset. The Mask R-CNN is chosen as a method using different CNN as backbone (convolutional Neural Network) ResNet50, ResNet101 and ResNet152, VGG16, VGG 19. We experimentally verify the effectiveness of the proposed method in the test phase.