bluuebunny/crossref_metadata_2025 huggingface dataset:
Using electrical anisotropy for structural characterization of sediments: an experimental validation study
Authors: Al‐Hazaimay Sadam , Huisman Johan A. , Zimmermann Egon , Vereecken Harry
Published: September 2019

Improved characterization of subsurface heterogeneity is important to better understand a range of key processes in the hydrologic cycle, such as overland flow, infiltration into the soil, evaporation to the atmosphere, and transpiration by plants. Recently, synthetic modelling studies have shown that information on subsurface heterogeneity can be obtained from the anisotropy in electrical resistivity. The objective of this paper is to experimentally validate the findings of this synthetic modelling study. In order to do so, we developed a new measurement procedure to determine the effective complex electrical resistivity from a set of current injections and voltage measurements on a heterogeneous sample. A synthetic modelling study showed that this new measurement procedure was able to reproduce the results of the previous study that showed how the electrical properties and the correlation length ratio of bimodal distributions of two materials can be obtained from the effective complex electrical resistivity measured in two perpendicular directions. After validation of the new measurement approach, we constructed two bimodal distributions in a 2D measurement cell and applied the newly developed measurement strategy. We were able to estimate the electrical properties, the volume fraction, and the correlation length ratio with good accuracy from the complex resistivity measurements in two directions. The remaining differences were attributed to variations in sediment thickness that occurred during sample preparation. We conclude that anisotropy should not be ignored but embraced when dealing with subsurface heterogeneity and that proper interpretation of anisotropy may actually be used to characterize subsurface heterogeneity.
Seasonal saline intrusion monitoring of a shallow coastal aquifer using time‐lapse DC resistivity traversing
Authors: Sutter Eva , Ingham Malcolm
Published: September 2019

Long‐term time‐lapse DC resistivity measurements along six 145‐ to 275‐m‐long transects have been carried out to image seasonal changes in the resistivity distribution within a shallow coastal aquifer on the Kapiti Coast, New Zealand. Two‐monthly repetition of the measurements shows a continuous decrease in the bulk resistivity at depth over an extended horizontal portion of the profile lines when coming into the drier summer season. This is most distinct in more rural locations and less pronounced along urban profiles, and is interpreted to be the result of a decrease in the fluid resistivity resulting from lower freshwater pressure that allows saltwater to intrude. Coming into the wetter winter season, the bulk resistivity at depth increases again, as freshwater pressure in the aquifer increases. A 24‐hour tidal cycle monitoring along one of the northern profiles, observations of seawater level stages, and tidal ranges show that the observed resistivity changes are seasonally driven rather than tidal overprints. Time‐lapse monitoring using electrical resistivity tomography has thus proven itself as a suitable tool for imaging both the saline interface shape and extent, and the changes in the subsurface resistivity distribution in an unconfined coastal, shallow, sand aquifer over a seasonal time frame. This significantly adds to the knowledge about the dynamic behaviour near the saline interface in coastal aquifers and can be used for groundwater assessment in this and other similar geological and hydrological environments around the world.
Spectral time‐domain induced polarisation and magnetic surveying – an efficient tool for characterisation of solid waste deposits in developing countries
Authors: Dotse Wemegah David , Fiandaca Gianluca , Auken Esben , Menyeh Aboagye , Kojo Danuor Sylvester
Published: September 2019

Time‐domain induced polarisation and magnetic data were acquired to map and characterise the decommissioned and un‐engineered municipal solid waste disposal site of the Kwame Nkrumah University of Science and Technology, located in the Kumasi Metropolis of Ghana. In this survey, 13 induced polarisation profiles 500–800 m long and 26 magnetic profiles 400–800 m long were acquired. In addition, two boreholes were drilled to help in the interpretation of the geophysical data. The study was carried out with the aim of determining the risk posed by the waste deposit to the quality of the soil and the ground water system, which is the main potable water supply for the Secondary School, the University Teaching Hospital and the Veterinary School, situated within the catchment area of the site. Full‐decay 2‐D time‐domain induced polarisation inversions in terms of Cole–Cole parameters were used for interpreting the induced polarisation data. The chargeability, resistivity and normalised charge‐ability distributions, together with the magnetic results, aided in a full characterisation of the site geology, the waste and the associated pollution plume. In particular, clear contrasts in resistivity and the polarisation parameters were found between the saprolite layer and the granitic bedrock, which are the main lithological units of the area. Furthermore, it was found that the Kwame Nkrumah University of Science and Technology waste deposit is characterised by a low‐chargeability and low‐resistivity signature and that the low‐resistivity area spreads out from the waste deposit into the permeable saprolite layer, indicating the presence of a leachate plume. A fracture zone in the granitic bedrock beneath the waste deposit, which is a potential conduit for leachate contamination of the ground water system, was also identified. The study thus provides the information needed for assessing the future impact of the waste on the water quality in the area and for designing risk‐mitigation actions.
A controlled monitoring study of simulated clandestine graves using 3D ground penetrating radar
Authors: van Schoor Michael , Coenraad Nienaber Willem , Marais‐Werner Anatulie
Published: September 2019

A controlled three‐dimesional ground penetrating radar monitoring study over simulated clandestine graves was conducted near Pretoria, South Africa, in which the detectability of graves as a function of post‐burial interval was assessed, as this is of particular interest to local forensic investigators. It was demonstrated that the site‐specific environmental parameter (a clay‐rich loamy soil with poor drainage) and heavy seasonal rainfall (as confirmed by ground‐penetrating‐radar‐derived soil moisture estimates) drastically compromised the long‐term grave detectability, especially when adopting a three‐dimensional depth slice analysis approach. It is also seen that the disturbed burial zone is the major contributor to the total grave anomaly rather than the buried body due to the combination of environmental parameters and the absence of buried artefacts. This paper also advocates the combined use of different data representations (two‐dimensional and three‐dimensional) to increase the likelihood of detecting subtle grave anomalies.
Characterization of the sedimentary fabrics in ornamental rocks by using GPR
Authors: Rey Javier , Martínez Julián , Montiel Violeta , Cañadas Francisco , Ruiz Nicolás
Published: September 2019

In this study, the use of ground‐penetrating radar for characterising ornamental sedimentary rocks was tested. Specifically, the ability of this non‐invasive geophysical prospecting method to identify fabrics and textures in rocks was investigated. Blocks mined from quarries were analysed, and ornamental rocks with the same lithologies as other widely utilised ornamental rocks with a variety of sedimentary fabrics and textures were selected. Rocks with clastic brechoid, cross‐laminated sparitic, massive or layered micritic, and laminar bindstone textures were analysed. Antennas that provided the maximum detail and a sufficient depth of penetration were used. The low electrical conductivity of carbonates permitted the use of high‐frequency antennas (800 MHz and 1.6 GHz), which were useful in studying the entire thickness of a boulder (up to 2 m).

The cross‐laminations in the oolitic limestones, the laminar bindstones of travertines, the differentiation between massive and brecciated fabrics, and the massive and slaty fabrics of the mic‐ritic limestones were examined using these two frequencies. In micritic textures without discontinuities (neither sedimentary nor diagenetic), the radargrams could detect facies with few reflections (Crema Marfil). In addition to analysing fabrics and textures, the ground‐penetrating radar measurements could identify anisotropy in these rocks, which makes ground‐penetrating radar an effective tool for evaluating the mechanical state of a boulder prior to its cutting.
Grey wolf optimisation for inversion of layered earth geophysical datasets
Authors: Chandra Akash , Agarwal Aayush , Shalivahan  , Singh Roshan K.
Published: September 2019

Geophysical observables using optimisation algorithms are interpreted in terms of physical properties defining the Earth. The field of optimisation is a dynamic field as no single algorithm can solve all optimisation problems. We implement the grey wolf algorithm, an apex predator‐based method, in optimizing geophysical datasets over a layered earth. The grey wolf optimiser is a swarm‐based meta‐heuristic algorithm and has two extremely interesting social practices, viz., social leadership hierarchy and hunting behaviour. The leadership hierarchy is simulated by employing different types of grey wolves where hunting strategies are implemented as optimisation methods. Global minimum from the grey wolf optimiser has been obtained with a pack of 7 wolves and 1500 iterations. To evaluate the efficacy of the grey wolf optimiser, we performed inversion of noise‐contaminated vertical electrical sounding (apparent resistivity), induced polarisation sounding (apparent chargeability), and magneto‐telluric apparent resistivity data. Subsequently, we implemented grey wolf optimisation on field apparent resistivity, apparent chargeability, and magnetotelluric apparent resistivity data adapted from published literature. Both noise‐contaminated synthetic and field data have been compared with popular population‐based algorithms, i.e., particle swarm optimisation and ant colony optimisation and with a local optimisation algorithm—ridge regression. The sensitivity analysis was performed by inverting the noise‐contaminated datasets using the grey wolf optimiser, particle swarm optimisation and ant colony optimisation with six different search space. It is observed that the grey wolf optimiser is least sensitive to the varied search space. The results obtained from the grey wolf optimiser as compared with other techniques are relatively more stable and the obtained normalised RMS deviation is either less or equal with ridge regression, particle swarm optimisation, or ant colony optimisation. This is due to the fact that the grey wolf optimiser does not converge prematurely and avoids getting trapped in a local minimum, as a balance between exploration and exploitation is maintained. We also compared the grey wolf optimiser using L1‐norm and L2‐norm as misfit functions for field data examples. The grey wolf optimiser using L1‐norm resulted in a more stable solution. The execution time of the grey wolf optimiser is least as compared with other population optimisation techniques. Grey wolf optimisation could be applied for routine interpretation of geophysical datasets.
Airborne mapping of sensitive clay—stretching the limits of AEM resolution and accuracy
Authors: Anschütz Helgard , Bazin Sara , Kåsin Kristoffer , Pfaffhuber Andreas A. , Smaavik Tone F.
Published: September 2019

Due to postglacial uplift, lowlands in Canada, Norway, Sweden and Russia are prone to formation of highly unstable, sensitive, and leached marine clay (quick clay). Quick‐clay failures are dramatic due to its high water content, resulting in liquefaction. It thus poses a major hazard for society and construction projects in particular, and knowledge of its extent is of vital importance. Quick‐clay assessment is usually undertaken in geotechnical boreholes having the disadvantage of giving only information at the borehole location. To overcome this limitation, geophysical ground‐based methods like electrical resistivity tomography have been used successfully. However, when a larger area has to be investigated, electrical resistivity tomography surveys become costly and time consuming. We show results from an airborne electromagnetic survey aiming at detection of different clay units for a road project in southeastern Norway. Airborne electromagnetic data clearly show structures within the sediment layer that correspond well with results from geotechnical boreholes. While a clear distinction between clay and quick clay cannot be derived from airborne electromagnetic alone, our study shows that this method has high‐enough resolution and accuracy to map differences in clay units, which can subsequently be probed at specified locations. Thus, by using airborne electromagnetics to target borehole locations, the costs for the geotechnical drilling program can be reduced significantly.
An ultra‐high‐resolution 3D marine seismic system for detailed site investigation
Authors: Monrigal Olivier , de Jong Ivan , Duarte Henrique
Published: September 2019

Currently, marine ultra‐high‐resolution 3D surveys tend to be characterized by signal frequency ranges of 0–600 Hz and bin sizes of the order of 3 to 6 metres. This may be acceptable in industry geohazard studies for top‐hole well drilling, but it does not have sufficient resolution for the very detailed information required by geotechnical engineers for the design and positioning of the turbine foundations in offshore wind farms.

We present a newly developed ultra‐high‐resolution 3D system, which takes the 3D‐resolution and 3D‐imaging one step further: to frequency ranges up to 2.5 kHz and 1‐m bin sizes. This system is based on an ultra‐high‐resolution sparker source utilising negative discharge technology, thus guaranteeing a stable and repeatable source signature. The high‐fidelity multi‐channel recording system is composed of four 24‐trace streamers with GPS positioning on both sources and receivers. Sophisticated navigation processing guarantees decimetre precision and the resultant 1‐m bin sizes. In addition, slant streamer technology is applied to ensure a broadband seismic response. Processing techniques, including critical corrections for wave motion and tides, have been developed.

Trial surveys were conducted in Thailand to validate the method and later in Croatia to study the shallow geology for the foundations of a 2.5‐km bridge across a sea inlet. The resultant 3D cubes gave very detailed views of the subsurface allowing the imaging of stratigraphic structures and small‐scale features, such as individual boulders in a boulder bed, that had hitherto not been identified.
Sparsity constraints using a Laplacian kernel to get geological structures from potential field data
Authors: Meng Zhaohai , Li Fengting , Xu XueChun , Zhou Wenyue , Hang Danian
Published: September 2019

We propose a new method for including sparsity constraints into potential field data inversion using a Laplacian kernel. The method obtains three‐dimensional density distributions, which are at best a proxy for geological structures. Compressive sensing has been used in many domains to recover the original data from the acquisition data. Compressive sensing is an inversion philosophy where sparsity constraints are applied, and thus, we use this principle into geophysical inversion. Here, we extend this algorithm to potential field data inversion. We introduced the Laplacian smoothed L0 norm into the stabiliser function as a sparse constraint, and the density constraint function has been introduced into our inversion method to guarantee the inverted density to be in the geological and physical meaning range. Compared to the traditional smooth inverse algorithm, our proposed method can obtain accurate geological structures with sharp boundary and sub‐surface “block” structures. This method permits reconstruction of (non‐smooth) density functions that represent a blocky geological structure. Our results using synthetic gravity data show that the Laplacian smoothed L0 norm inversion method with sparsity constraints predicts more focused and accurate depth and density anomalies than smooth inversion method. Application of this Laplacian smoothed L0 norm sparsity constraints method to the inversion of gravity data collected over the Humble salt dome, Harris County, near Houston, United States, leads to improved interpretation of geological structures. These results confirm the validity of the proposed method and its potential application for other potential field data inversions to explore geological structures.
Spectral induced polarization in a sandy medium containing semiconductor materials: experimental results and numerical modelling of the polarization mechanism
Authors: Abdulsamad Feras , Florsch Nicolas , Camerlynck Christian
Published: September 2019

Induced polarization is widely used for mineral exploration. In the presence of sulfides (more generally speaking, semiconductors), the charge carriers inside the particles are electrons and electron gaps. The mechanism of induced polarization is not fully understood in those cases. In order to improve our knowledge about the mechanisms controlling induced polarization in such media, we carried out spectral induced polarization measurements on unconsolidated mineralised medium and performed a numerical modelling based on the solution of the Poisson–Nernst–Planck equations set. Different types of semiconductors (graphite, pyrite, chalcopyrite, and galena) have been included in the experiments. The polarization effects of grain radius, semiconductor content, and electrolyte salinity and type have been investigated at the lab scale. The experimental results showed that the chargeability or frequency effect of the medium is a function of the mineral volume and is independent of electrolyte salinity and type. Furthermore, the time constant is highly dependent on grain radius and electrolyte salinity, whereas it is slightly dependent on mineral type. The observed dependence of the chargeability and time constant on salinity could be explained by considering the semiconductor grain as an electric dipole impacting the potential and consequently the charge distribution in its vicinity. This dipole is generated inside the particle to compensate the primary electrical field. Since the Poisson–Nernst–Planck equations are coupled, the potential depends in return on the resulting ions distribution. Therefore, it could be used to explain the induced polarization phenomena. Using the finite element method, we computed the solution of the Poisson–Nernst–Planck equations for a grain of pyrite surrounded by an ionic solution, where the charge diffusions in both grain and electrolyte were considered. Regarding the electrolyte salinity, the dependence of the relaxation time observed from the experimental study is qualitatively consistent with that extracted from the numerical simulation.
Geometrical constraints for membrane polarization
Authors: Hördt Andreas , Bairlein Katharina , Bücker Matthias , Stebner Hermann
Published: September 2019

Membrane polarization is one process that might describe the causes of induced polarization in sediments at the pore scale. Here, we investigate the practical relevance of one particular model, which consists of two cylindrical pores with different radii r and lengths L, for which the impedance can be calculated analytically. We derive approximate equations that relate polarizabilities and relaxation times directly to r and L. Based on these relations and on a systematic exploration of the parameter space, we investigate under which conditions membrane polarization is relevant in the sense that it produces measurable phase shifts in the frequency range typically observed in the laboratory or at the field scale.

In principle, a wide range of spectra can be obtained. Maximum phase shifts up to hundreds of milliradian can be simulated, and the characteristic time scales cover the entire range typically measured in the laboratory. We discuss some specific constraints in the context of results from mercury injection porosimetry and recently published laboratory data and show that the required geometries are not unrealistic, even if a moderate ratio between pore length and width is included as an additional condition. We conclude that membrane polarization as a possible mechanism is not limited to a particular frequency range. We also provide evidence that the pore length of the wide pore is likely to control the measured relaxation times in practical situations. The results encourage further attempts to combine impedances of two‐pore systems to approach the simulation of real sediments, with the aim to extract pore space parameters from measured data.
Simulation of membrane polarization of porous media with impedance networks
Authors: Stebner Hermann , Halisch Matthias , Hördt Andreas
Published: September 2019

The spectral induced polarization method is supposed to have some potential to provide useful information on hydraulic properties of the subsurface. One difficulty for the practical implementation is the simulation of underlying physical processes at the pore scale and their upscaling to hydraulically relevant scales. We extend an existing semi‐analytical membrane polarization model to two‐ and three‐dimensional impedance networks, which are numerically solved to obtain a spectral induced polarization response that can be compared to measured data.

The original model consists of two cylinders with different sizes. The model has been shown to be able to reproduce some basic features of spectral induced polarization spectra measured in the laboratory, but it is unable to meet the complexity of macroscopic porous media structures, which can be found within unconsolidated sediments or rocks. To approach realistic pore space geometry, we connect different combinations of cylinders to networks. We treat the smaller of the two cylinders as a pore throat. The pore throat distribution in the network is chosen by matching measured pore throat radii distributions obtained from the mercury injection method. The large cylinder is treated as the (large) pore body, and its radii are associated to the pore throats using existing relationships.

We compare the behaviour of the networks with real porous media by using sandstone samples for which both the electrical and petrophysical properties have been measured. We adjust the geometrical parameters of the network, i.e., pore lengths, pore radii, and their relative occurrences, such that they match the measured parameters (specific internal surface area, pore throat distribution, and porosity) of the sandstone samples. The measured spectral induced polarization parameters, like the maximum phase shift and the characteristic relaxation time, are qualitatively consistent with our simulation results.
Pore‐scale modelling of complex conductivity of saturated granular materials
Authors: Niu Qifei , Zhang Chi
Published: September 2019

The complex conductivity method has been frequently used in solving hydrogeological, engineering, and environmental problems in practice. Macroscopic geophysical responses are governed by pore‐scale rock properties; therefore, a clear petrophysical understanding of how the pore‐scale structure controls electric conduction and polarization in geomaterials is necessary to fully interpret laboratory‐/field‐scale geophysical observations. In this study, we have developed a pore‐scale numerical approach to calculate the complex conductivity of water‐saturated granular materials. This physics‐based model has advantage over phenomenological or empirical models such that the intrinsic relations between pore structure and geoelectrical signals could be revealed. In the modelling, the influence of electrical double layer, which is quantified by complex surface conductance, can be converted to an apparent volumetric complex conductivity of either solid particles or pore fluid. The effective complex conductivity of the sample is determined by directly solving the finite‐difference representation of the Laplace equation in the domain of a representative elementary volume. The numerical approach is tested on one synthetic sample and one glass beads sample. For the synthetic sample, the consistency between the numerical and the analytical solution confirms the accuracy of the approach. Comparison with experimental measurements of the glass beads sample reported previously indicates that the developed numerical approach can well reproduce the key characteristics of the complex conductivity of water‐saturated granular materials in the frequency range between 10‐1 and 104 Hz. Furthermore, the numerical examples also show that the proposed approach can capture the salinity‐dependent electric conduction and polarization in saturated granular materials.
La longue marche pour la formation pédagogique des enseignants du supérieur au Liban
Authors: Moghaizel-Nasr Nada
Published: September 2019

L’auteure commence par expliciter l’enjeu de la formation pédagogique des enseignants universitaires, à la lumière des compétences à développer auprès des étudiants pour le XXIe siècle. Elle présente ensuite le cadre national impactant les pratiques pédagogiques dans les universités libanaises, l’état des lieux de la formation pédagogique des enseignants dans ces universités ainsi que les projets institutionnels ayant une portée nationale. Elle conclut par une réflexion sur les conditions favorisant l’amélioration des pratiques enseignantes et sur l’enjeu sociétal de la pédagogie universitaire, qui favorise une qualité inclusive de l’enseignement.
PROSTATE CANCER DETECTION USING HISTOPATHOLOGY IMAGES AND CLASSIFICATION USING IMPROVED RideNN
Authors: Gurav Shashidhar B. , Kulhalli Kshama V. , Desai Veena V.
Published: September 2019

Medical industry reports prostate cancer as common and high among men and alarms the necessity for detecting prostate cancer for which the required morphology is extracted from the histopathology images. Commonly, the Gleason grading system remains a perfect factor for grading prostate cancer in men, but pathologists suffer from minute inter- and intra-observer variations. Thus, an automatic method for segmenting and classifying prostate cancer is modeled in this paper. The significance of the developed method is that the segmentation and classification are gland-oriented using the Color Space (CS) transformation and Salp Swarm Optimization Algorithm-based Rider Neural Network (SSA-RideNN). The gland region is considered as the morphology for cancer detection from which the maximal significant regions are extracted as features using multiple-kernel scale-invariant feature transform (MK-SIFT). Here, the RideNN classifier is trained optimally using the proposed Salp–Rider Algorithm (SRA), which is the integration of Salp Swarm Optimization Algorithm (SSA) and Rider Optimization Algorithm (ROA). The experimentation is performed using the histopathology images and the analysis based on sensitivity, accuracy, and specificity reveals that the proposed prostate cancer detection method acquired the maximal accuracy, sensitivity, and specificity of 0.8966, 0.8919, and 0.8596, respectively.
Applying of Heat Treatments to Improve the Properties of Welded Pipeline Steel
Authors: Digheche Kaltoum , Boumerzoug Zakaria , Khamouli Farida , Saoudi Adel , Saadi Khawla
Published: September 2019

This work, presents some heat treatments were used to improve the microstructure in different zones of the API X70 welded pipeline steel. In this study a shielded metal arc welding (SMAW) process has been realized.. Scanning electron microscopy and X-ray diffraction have been used as characterization techniques to observe the WM microstructures, in addition hardness are also measured. The results revealed that the isothermal heat treatment caused progressive recristallization reactions in the weld zone, and the hardness of weld joints decreased, were the main transformations after increasing the temperature of the heat treatment.
Optimization of TIG Welding Process Parameters for X70-304L Dissimilar Joint Using Taguchi Method
Authors: Benlamnouar Mohamed Farid , Hadji Mohamed , Badji Riad , Bensaid Nabil , Saadi Taher , dit Laksir Yazid Laib , Senouci Sabah
Published: September 2019

The optimization of mechanical properties of the welded joints requires a statistical approach such as Taguchi experimental designs associated with experimental techniques and laboratory characterizations. The aim of this work is to propose a method of optimization of the mechanical performances of a TIG dissimilar welding of two grades of steels: a high strength low alloy steel X70 and an austenitic stainless steel 304L. The experimental designs were chosen according to the Taguchi method L9. The metallurgical characterization includes optical microscopy, SEM microscopy, EDX analyses and mechanical tests to establish a relationship between welding parameters, microstructures and mechanical behavior in different zones of a dissimilar weld joint. The results showed that the hardness is more strongly related to microstructural evolution than tensile strength of dissimilar joint. It was found that gas flow is the main significant TIG welding parameter affecting dissimilar weld characteristics.
Poincaré inequality 3/2 on the Hamming cube
Authors: Ivanisvili Paata , Volberg Alexander
Published: September 2019

For any

n \geq 1

, and any

f \colon \{-1,1\}^{n} \to \mathbb{R}

, we have

\mathcal R \mathbb{E} (f + i |\nabla f|)^{3/2} \leq \mathcal R (\mathbb{E}f)^{3/2},

where

z^{3/2}

for

z=x+iy

is taken with principal branch, and

\mathcal R

denotes the real part. We show an application of this inequality: it sharpens a well-known inequality of Beckner.
Numerical Investigation of Electrostatic Spray Painting Transfer Processes for Vehicle Coating
Authors: Pendar Mohammad Reza , Pascoa Jose
Published: September 2019

In this study we examined numerically the electrostatic spray transfer processes in the rotary bell spray applicator, which is this case implemented in a full 3D representation. Instead of an experimental approach [Stevenin et al., 2015, Fluids Eng., 137 (11)], here an algorithm implemented and developed for this simulation includes airflow, spray dynamics, tracking of paint droplets and an electrostatic modularized solver to present atomization and in-flight spray phenomena for the spray forming procedure. The algorithm is implemented using the OpenFOAM package. The shaping airflow is simulated via an unsteady 3D compressible Navier-Stokes method. Solver for particle trajectory was developed to illustrate the process of spray transport and also the interaction of airflow and particle that is solved by momentum coupling. As the numerical results in this paper indicates dominant operating parameter voltage setting, further the charge to mass ratio and air-paint flow rate deeply effect the spray shape and the transfer efficiency (TE). The spin of the bell forced the paint to fall off from the bell edge into the high-velocity airflow. By increasing the shaping airflow more uniform distribution of mass of paint is produced but the TE decreases. The size distribution is highly sensitive to the bell rotational speed. Our results demonstrate the validity of the numerical procedure and also the applicability of it in reducing the production costs for painting. Unsteady and dynamic treatment of the flow is described using Large eddy simulation (LES) turbulence models, whereas the movement of the paint particles is modeled by the approach of tracking droplet size distribution, also the electrical potential effect on its size and form can be predicted. Using this advanced numerical simulation the efficiency and quality of the program can be evaluated precisely for industrial robots of paint over Off-Line Programming (OLP). Further, the paint spraym structure obtained from the numerical simulations is compared with the experimental data at the same working condition with appropriate quantitative accuracy.
Local Weakening of Honeycomb Core for Improved Surface Quality and Bonding in Co-Cured Sandwich Panels
Authors: Eschen Henrik , Schüppstuhl Thorsten
Published: September 2019

Sandwich panels made of Nomex honeycomb core and fiber reinforced face sheets are a major component of aircraft interior parts. A common way to locally increase the strength of such panels, e.g. for load introduction, is the local thickening of the face sheets with additional prepreg layers. Curing of strengthened panels without further processing of the core leads to higher flatness tolerances as well as residual stresses. Machining of the core in the strengthened areas is possible, but expensive due to high machine costs and additional cleaning processes. In this paper a new process for the reduction of the residual stresses in strengthened areas, as well as improved bonding between core and face sheets is presented. The process is based on local reduction of the compressive strength in the surface area of the honeycomb core, which allows for controlled, irreversible deformation at curing pressure. For the reduction of compressive strength, a concept based on a robot guided tool with multiple blades is presented. The process parameters impacting the compressive strength after weakening are derived based on a model based analysis. A testing tool was built, and a series of tests was performed, in order to quantify the impact and to select suitable parameters. It was found that the remaining compressive strength depends mainly on the cutting pattern, the blade distance and the cutting depth. A Further reduction of compressive strength was achieved by bending the remaining structures after the cutting process. In order to validate the process, surface flatness, as well as bonding strength between core and face sheets have been measured. In addition to the flat integration of a large amount of additional prepreg layers it has been found that the bonding strength increases up to 30% due to increased bonding surface of the honeycomb core.
High Speed Orbital Drilling Optimization and Fatigue Life Enhancement by Orbital Roller Burnishing for Aluminum Alloy
Authors: Kamgaing Souop Landry Arnaud , Landon Yann , Senatore Johanna , Daidie Alain , Ritou Mathieu
Published: September 2019

Orbital drilling has proved to be advantageous to achieve aeronautical-level quality drilling (surface roughness, geometry control…) fully adapted for complex assemblies in a single operation. However, compared to conventional drilling method, this process leads to a drastic change in structure’s fatigue life probably due to a non-optimised level of residual stress. The control of the mechanical behaviour of parts obtained by orbital drilling is the goal of the European-CleanSky collaborative R&D project RODEO (Robotized Orbital Drilling Equipment and Optimized Residual Stresses, GA no.738219). In this work, an orbital drilling unit (ORBIBOT) allowing high speed machining conditions was developed by PRECISE France, that can be integrated on a lightweight industrial robot. Cutting parameters were determined through an original Tool-Material Couple optimization strategy dedicated to orbital drilling, developed with MITIS Engineering and carried out on 2024-T351 Aluminum alloy. In order to enhance the mechanical behaviour of the system (fatigue, surface hardening…), an innovative mechanical surface treatment has been introduced for investigations: orbital roller burnishing, performed right after orbital drilling. The burnisher follows a helical path around the hole axis. Orbital burnishing and its associated tool have been patented by PRECISE (N°FR16 60693). A comparative study between axial drilling, orbital drilling and orbital drilling+burnishing was done in terms of hole diameter, surface roughness, burr height, fatigue life…. Performances and quality levels obtained by using orbital drilling (with or without burnishing) are significantly different compared to conventional drilling. On open-hole samples, a significative fatigue life improvement was exhibited using orbital drilling, even more important with burnishing. Tests were performed also on filled-hole configurations. The innovative coupling of orbital drilling and burnishing tools suggested by PRECISE offers new high-speed machining opportunities, especially in the controlled strain hardening and residual stresses domains.
Step & Repeat: Reduce Derivative Aircraft Development Risk with Design Reuse
Authors: Askar Muhammad
Published: September 2019

The complex and risky process of designing derivative aircraft, especially when it comes to electrical systems, can be a daunting task at best. There are a number of design strategies that can be employed to mitigate risk and increase the overall efficiency. Quite simply, the current methods of manual processes, design and integration approaches that were optimized from mechanical approaches, are no match for today’s complexities.

One method gaining significant traction is to employ a central database serving global interface definitions for the entire design process. Automation through generative design minimizes manual intervention and repetitive work. Furthermore, detecting changes through design rule checks allows system engineers to verify their designs, capturing both inadvertent and planned changes. The ability to instantly update the design content from the new definition streamlines the change management process.

Employing these technologies in a digital, connected thread, ensures that intelligent information is leveraged at every step along the way from aircraft conception, realization, and finally to utilization - thereby minimizing risk and maximizing efficiency.
Mao Zedong kot poslednji konfucijanski vladar? Moralno-didaktični vidik »konfucijanske« umetnosti
Authors: Vampelj Suhadolnik Nataša
Published: September 2019

Pričujoči članek obravnava problematiko moralno-didaktičnega vidika »konfucijanske umetnosti«, ki nastopa v obliki t. i. narativnega slikarstva. Z namenom legitimacije politične avtoritete so številni vladarji s pomočjo vizualnega medija promovirali konfucijanske družbene in politične vrednote, ki bi jih prikazali kot idealne konfucijanske vladarje. Na primeru dveh vladarjev – prvega cesarja dinastije Tang Taizonga (589–649) ter ustanovitelja dinastije Južni Song Gaozonga (1107–1187) – bomo poskušali prikazati koncept »konfucijanskega idealnega vladarja«, kot ga razkrivajo posamezni primeri narativnih ilustracij. Izhajajoč iz teh primerov bomo v zadnjem delu članka poskušali interpretirati slikovno propagando velikega vodje komunistične Kitajske Mao Zedonga (1893– 1976), ki je ravno tako s pomočjo didaktičnih ilustracij v obliki propagandnih plakatov širil moderne ideje komunistične ideologije. Pri tem je večkrat prikrito sledil modelu »konfucijanskega vladarja«, čeravno ga je ovil v simbolne ovoje modernih ideologij 20. stoletja. Ali bi torej lahko Mao Zedonga označili za poslednjega »konfucijanskega idealnega vladarja«, bo osrednje vprašanje zadnjega dela pričujočega članka.
Od Mehike do Brazilije, od starodavne Kitajske do novega konfucianizma: sinološke študije v Latinski Ameriki
Authors: Ciglič Barbara Pihler
Published: September 2019

V študiji začrtamo splošni okvir začetkov in razvoja sinoloških študij na geografsko, politično in kulturno zelo raznolikem področju Latinske Amerike ter izpostavimo osrednje sodobne vidike in tendence. V 21. stoletju se hitro rastoča povezanost med Kitajsko in Latinsko Ameriko odraža v pospešenem ustanavljanju raznolikih gospodarsko-političnih ter akademsko-izobraževalnih institucij in publikacij ter v organizaciji številnih mednarodnih konferenc in znanstvenih srečanj. Razvoj konfucijanskih študij najprej analiziramo s pregledom najpomembnejših prevodov in publikacij 20. stoletja v povezavi z »naukom izobražencev« na latinskoameriških tleh ter s preglednim komentarjem najodmevnejših znanstvenih člankov in monografij. Nato se študija osredotoči na Mehiko, državo z najdaljšo sinološko tradicijo v Latinski Ameriki, kjer Centro de Estudios de Asia y África na El Colegio de México še danes velja za eno najuglednejših latinskoameriških središč za azijske in afriške študije. Zatem se posveti Braziliji, za katero se zdi, da ima od vseh držav najmanj trdno tradicijo proučevanja sinoloških in konfucijanskih vsebin. Osrednje premise sinoloških in konfucijanskih raziskav v teh dveh deželah predstavimo skozi prizmo študij dveh pomembnih sodobnih sinologov, Chen Yonga (El Colegio de México) in Andréja Buena (Universidade do Estado Rio de Janeiro).
André Bueno, José Maria Neto (ur.): Antigas Leituras. Visões da China Antiga
Authors: Pihler Ciglič Barbara
Published: September 2019

Pričujoča publikacija z naslovom Antigas leituras. Visões da China Antiga (Stara branja. Pogledi na starodavno Kitajsko) prinaša trinajst študij o zgodovini, umetnosti, filozofiji in literaturi starodavne Kitajske, ki so jih prispevali avtorji iz Brazilije, Portugalske, Španije, Makaa, Kitajske, Singapurja, Izraela in Slovenije. Uredila sta jo André Bueno, brazilski zgodovinar in filozof, ki si že dvajset let prizadeva za uveljavitev sinologije v Braziliji, ter José Maria Gomes de Souza Neto, profesor antične zgodovine na univerzi v brazilski zvezni državi Pernambuco. Knjiga je zaključena celota in hkrati drugi del tematsko širše zastavljene zbirke Stara branja (Antigas Leituras), ki jo je zasnoval prav José Maria Neto in katere glavni namen je stare literarne vire osvetliti z nove perspektive ter spodbujati nova branja.
Vloga konfucijanske ideologije pri oblikovanju nacionalne države na Japonskem
Authors: Visočnik Nataša
Published: September 2019

Ideja o iskanju identitete kot procesu, ki pojasnjuje, kdo so ljudje, je pri človeku vedno prisotna. V okviru tega kompleksnega procesa so bili tudi na Japonskem izumljeni številni novi koncepti, poleg tega pa je bila raziskava o etnogenezi na japonskih otokih pod velikim vplivom nacionalističnih diskurzov o japonski kulturi in je sprožila vrsto različnih predpostavk, ki so danes še vedno prisotne. Proces konstruiranja identitet, zlasti japonske nacionalne identitete, je bil še posebej intenziven v obdobju Meiji (1868–1912), tj. ko se je Japonska odprla svetu in je poskusila oblikovati nacionalno državo. V tem obdobju so politiki sprejeli zamisel o nacionalni pripadnosti, ki je delovala kot temeljni kamen za oblikovanje moderne nacionalne države. Oblikovali so idejo o družinski državi (kazoku kokka 家族国家). Ta vsebuje tradicionalno družinsko povezanost ali čut za družino (kazoku shugi 家族 主義), ki je del klasične konfucijanske etike, vendar se nekoliko razlikuje od japonske interpretacije skupine. Čut za družino, ki vključuje sistem širše družine, se je razširil na celoten narod, in sicer tako, da je vključeval cesarsko družino kot glavno družino vseh japonskih družin. Ta članek bo tako poskušal odgovoriti, kako se je konfucijanstvo vključevalo v japonski okvir posodobitve nacionalne države v poznem 19. stoletju in kako je prišlo do opredelitve ene glavnih, če ne celo prevladujoče plasti zgodnjih modernih in sodobnih svetovnih nazorov. Pri tem bo skozi analizo konceptov kritično prevetril uporabo konceptov v teh procesih ter pogledal, kako so ti koncepti nastajali in se spreminjali glede na potrebe družbenega dogajanja.
Evropski spomin in vizualizacija travme: vloga umetniške reprezentacije v medijskem projektu »Begunec_ka sem«
Authors: Vidmar Horvat Ksenija
Published: September 2019

Članek obravnava medijski projekt avtoric Widad Tamimi in Vesne Bukovec, ki ga je med januarjem in marcem 2016 predstavljal časopis Delo. Projekt je temeljil na srečanjih avtoric z begunci v begunskem centru v času t. i. begunske krize. Avtorici sta pričevanja predelali v pripovedi z ilustracijo. Analiza se osredotoča na pedagoško moč kolaža biografije, fikcije in vizualne reprezentacije in proučuje učinek na javni spomin. Primerjalno ozadje študiji je teorija fotografije in fotografskega spomina v 20. stoletju.
Li Shangyin and the Art of Poetic Ambiguity
Authors: Lavrač Maja
Published: September 2019

Li Shangyin (813–858), one of the most respected, mysterious, ambiguous and provocative of Chinese poets, lived during the late Tang period, when the glorious Tang dynasty was beginning to decline. It was a time of social riots, political division and painful general insecurity. Li Shangyin is famous as a highly original and committed poet who developed a unique style full of vague allusions and unusual images derived from the literary past (the traditional canon, myths and legends) as well as from nature and personal experience. The second important feature of his poetry is a mysteriousness which finally leads to ambiguity. Ambiguity plays an essential role in most of his renowned poems, and he uses it to superbly connect present and past, reality and fantasy, and history and mythology. Thus, ambiguity and obscurity, respectively, often engender different interpretations among Chinese critics. These interpretations reflect the poems’ imaginative qualities, hypotheses and contradictions. Since each interpretive direction emphasizes but a single aspect of the poet’s character, it is more fitting to understand his ambiguous poems in symbolic terms. Such understanding entails that the meaning of the poem is not limited to one interpretation; rather, the poem’s poetic landscape opens itself up to various interpretations.Li Shangyin is actually most popular for his melancholic love poetry that reveals his ambiguous attitude to love. In this poetry, love is shrouded in a secret message. On the one hand, we can sense his moral disapproval of a secret but hopeless love; on the other, we can sense his passion. This leads to a paradox: the pleasing temptations of an illicit romance also exact a high price. In these love poems Li investigates various aspects of the worlds of passion which stoke in him feelings of rapture, satisfaction, joy and hope as well as feelings of doubt, frustration, despair and even thoughts of death.
»Nočem biti odvisna«: Ali javne prevajalske in tolmaške storitve res negativno vplivajo na aktivno vključenost migrantov v državo gostiteljico?
Authors: Kocijančič Pokorn Nike , Jevtić Iva , Čibej Jaka
Published: September 2019

Prispevek se sprašuje o upravičenosti določenih političnih ukrepov, ki odrekajo zagotavljanje prevajanja in tolmačenja migrantom, ter zagovarja nove pristope k jezikovni in prevodni politiki, in sicer prek raziskave, ki je bila zasnovana kot odziv na trditve, da prevajalske in tolmaške storitve ovirajo integracijo nedavnih priseljencev. Raziskava je bila izvedena na skupini prosilcev za mednarodno zaščito v azilnem domu v Ljubljani. Najprej smo zbrali podatke o jezikovnem ozadju vseh stanovalcev azilnega doma v avgustu 2014 (56 stanovalcev iz 19 različnih držav), nato pa sestavili reprezentativno skupino 18 prosilcev za mednarodno zaščito na podlagi njihovega maternega jezika in jih razdelili na dve skupini glede na čas bivanja v Sloveniji v času intervjuja (krajše ali daljše obdobje). Kvantitativne podatke o jezikovnih profilih smo zbrali z vprašalnikom, kvalitativne pa s pomočjo polstrukturiranih intervjujev, izvedenih v letu 2014, in dveh ponovitvenih intervjujev v letu 2015. Nato smo kvalitativno analizirali transkripcije vseh posnetih intervjujev, pri čemer smo se osredotočali na jezikovne in komunikacijske rešitve na različnih stopnjah migrantovega življenja v državi gostiteljici. Rezultati kažejo, da je osnovne kompromise mogoče doseči, saj so prevajalske in tolmaške storitve komplementarni koraki do neodvisnosti in kot take ne ovirajo učenja dominantnega oz. nacionalnega jezika države gostiteljice, temveč ga podpirajo.