bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating Bahasa Inggris Maritim dan Perikanan Paket Keahlian Teknika Kapal Penangkapan Ikan Kelas X
Authors: Mella Stellar Nube
Published: September 2019

This study would like to find out the extent to which the ESP textbooks Bahasa Inggris Maritim dan Perikanan Paket Keahlian: Teknika Kapal Penangkapan Ikan Kelas X Semester I (BIMP I) and Bahasa Inggris Maritim dan Perikanan Paket Keahlian: Teknika Kapal Penangkapan Ikan Kelas X Semester II (BIMP II) met the criterions of ESP textbooks evaluation proposed by Cunningsworth (1995). Content analysis was used to analyze the textbooks. It was found that one of the textbooksâ€™ objectives was to enable students to use English as a communication tool. Both ESP textbooks presented vocabulary and discourse structures, covered relevant skills, encouraged learning activities relevant to studentâ€™s real life, and acknowledged studentâ€™s subject specific knowledge. The presentation of language items and language skills, however, were not fully in balance, and both ESP textbooks did cover speaking activities which replicated genuine English communication.
"Hot Issue" Critical Review: The Aboriginalization of Inquiry: Tourism Research by and for Aboriginal and Torres Strait Islander People
Authors: Jacobsen Damien
Published: September 2019

In this "hot issue" article, Jacobsen argues that even after decades of inquiry the level of Tourism Studies disconnect from Aboriginal and Torres Strait Islander people is troubling. He maintains that (relieved of Aboriginal or Torres Strait Islander voices for so long) the received
literature on tourism is still dominated by non-indigenous academics who continue to forge a discourse based on "Othering." The purpose of his critical review article is to substantively engage with the disconnect that seemingly plagues inquiry about tourism for Aboriginal and Torres Strait
Islander people in Australia. This Jacobsen piece thereby exposes subtle, overarching misgivings observable in the literature underscored by the presupposed "Othering" of Aboriginal and Torres Strait Islander people as "inferior people." This hot issue article therefore moves away from discourses
of deficit, inertia, imposed Western-centric theorization, and superficial inquiry towards the Aboriginalization of research-intotourism as inquiry that is emancipative and situated within and emanating from Aboriginal and Torres Strait Islander worldviews. In providing a number of outcomes
from a 6-year national research program in remote Australia, Jacobson reflects on their value as the basis for "leadership" and for "future broad directions." To Jacobsen, the Aboriginalization of tourism inquiry must be based on cultural integrity in order to drive the discourse of enabling,
cultural ways of business, and appropriate leadership. This hot issue article thus draws attention to the urgent need for Tourism Studies practice to be genuinely committed to the well-being of Aboriginal and Torres Strait Islander people, cultures, country, and knowledge. [Abstract by the
Reviews Editor]
Harnessing enzyme plasticity for the synthesis of oxygenated sesquiterpenoids
Authors: Demiray Melodi , Miller David J , Allemann Rudolf K
Published: September 2019

8-Methoxy-γ-humulene, (E)-8-methoxy-β-farnesene, 12-methoxy-β-sesquiphellandrene and 12-methoxyzingiberene can be synthesised in amorphadiene synthase-catalysed reactions from 8- and 12-methoxyfarnesyl diphosphates due to the highly plastic yet tightly controlled carbocationic chemistry of this sesquiterpene cyclase.
Emission Measures and Emission-measure-weighted Temperatures of Shocked Interstellar Medium and Ejecta in Supernova Remnants
Authors: Leahy Denis , Wang Yuyang , Lawton Bryson , Ranasinghe Sujith , Filipović Miroslav
Published: September 2019

A goal of supernova remnant (SNR) evolution models is to relate fundamental parameters of a supernova (SN) explosion and progenitor star to the current state of its SNR. The SNR hot plasma is characterized by its observed X-ray spectrum, which yields electron temperature, emission measure (EM), and abundances. Depending on their brightness, the properties of the plasmas heated by the SNR forward shock, reverse shock, or both can be measured. The current work uses models that are spherically symmetric. One-dimensional hydrodynamic simulations are carried out for SNR evolution prior to onset of radiative losses. From these, we derive dimensionless EMs and EM-weighted temperatures, and we present fitting formulae for these quantities as functions of scaled SNR time. These models allow one to infer SNR explosion energy, circumstellar medium density, age, ejecta mass, and ejecta density profile from SNR observations. The new results are incorporated into the SNR modeling code SNRPy. The code is demonstrated with application to three historical SNRs: Kepler, Tycho, and SN1006.
Entrapment of CO in CO2 Ice
Authors: Simon Alexia , Öberg Karin I. , Rajappan Mahesh , Maksiutenko Pavlo
Published: September 2019

Planet atmosphere and hydrosphere compositions are fundamentally set by accretion of volatiles, and therefore by the division of volatiles between gas and solids in planet-forming disks. For hyper-volatiles such as CO, this division is regulated by volatile sublimation energies, and by the ability of other ice components to entrap. Water ice is known for its ability to trap CO and other volatile species. In this study we explore whether another common interstellar and cometary ice component, CO2, is able to trap CO as well. We measure entrapment of CO molecules in CO2 ice through temperature-programmed desorption experiments on CO2:CO ice mixtures. We find that CO2 ice traps CO with a typical efficiency of 40%–60% of the initially deposited CO molecules for a range of ice thicknesses between 7 and 50 monolayers, and ice mixture ratios between 1:1 and 9:1. The entrapment efficiency increases with ice thickness and CO dilution. We also run analogous H2O:CO experiments and find that under comparable experimental conditions, CO2 ice entraps CO more efficiently than H2O ice up to the onset of CO2 desorption at ∼70 K. We speculate that this may be due to different ice restructuring dynamics in H2O and CO2 ices around the CO desorption temperature. Importantly, in planet-forming disks, the ability of CO2 to entrap CO may change the expected division between gas and solids for CO and other hyper-volatiles exterior to the CO2 snowline.
Wave Heating in Simulated Multistranded Coronal Loops
Authors: Guo Mingzhe , Doorsselaere Tom Van , Karampelas Konstantinos , Li Bo
Published: September 2019

It has been found that the Kelvin–Helmholtz instability (KHI) induced by both transverse and torsional oscillations in coronal loops can reinforce the effects of wave heating. In this study, we model a coronal loop as a system of individual strands, and we study wave heating effects by considering a combined transverse and torsional driver at the loop footpoint. We deposit the same energy into the multistranded loop and an equivalent monolithic loop, and then observe a faster increase in the internal energy and temperature in the multistranded model. Therefore, the multistranded model is more efficient in starting the heating process. Moreover, higher temperature is observed near the footpoint in the multistranded loop and near the apex in the monolithic loop. The apparent heating location in the multistranded loop agrees with the previous predictions and observations. Given the differences in the results from our multistranded loop and monolithic loop simulations, and given that coronal loops are suggested to be multistranded on both theoretical and observational grounds, our results suggest that the multistrandedness of coronal loops needs to be incorporated in future wave-based heating mechanisms.
The Laboratory Millimeter and Submillimeter Rotational Spectrum of Lactaldehyde and an Astronomical Search in Sgr B2(N), Orion-KL, and NGC 6334I
Authors: Alonso Elena R. , McGuire Brett A. , Kolesniková Lucie , Carroll P. Brandon , León Iker , Brogan Crystal L. , Hunter Todd R. , Guillemin Jean-Claude , Alonso Jose L.
Published: September 2019

We present a laboratory rotational study of, and astronomical search for, lactaldehyde (CH3CH(OH)CH(O)), one of the simplest chiral molecules that could reasonably be seen in the interstellar medium (ISM), in the millimeter and submillimeter wave regions from 80 to 460 GHz. More than 5000 transitions were assigned to the most stable conformer, and a set of spectroscopic constants was accurately determined. Lactaldehyde is involved in numerous metabolic pathways used by life on Earth, and is a logical step up in complexity from glycolaldehyde (CH(O)CH2OH) which is being detected with increasing regularity in the ISM. We present an accompanying radio astronomical search for lactaldehyde in three high-mass star-forming regions (NGC 6334I, Sgr B2(N), and Orion-KL) as well as in the publicly available data from the ASAI Large Project. Neither molecule is detected in these sources, and we report corresponding upper limits to the column densities. We discuss the potential utility of lactaldehyde in combination with other members of the [C3,H6,O2] isomeric family in probing pathways of chemical evolution in the ISM.
Data-driven Reconstruction of Gravitationally Lensed Galaxies Using Recurrent Inference Machines
Authors: Morningstar Warren R. , Levasseur Laurence Perreault , Hezaveh Yashar D. , Blandford Roger , Marshall Phil , Putzky Patrick , Rueter Thomas D. , Wechsler Risa , Welling Max
Published: September 2019

We present a machine-learning method for the reconstruction of the undistorted images of background sources in strongly lensed systems. This method treats the source as a pixelated image and utilizes the recurrent inference machine to iteratively reconstruct the background source given a lens model. Our architecture learns to maximize the likelihood of the model parameters (source pixels) given the data using the physical forward model (ray-tracing simulations) while implicitly learning the prior of the source structure from the training data. This results in better performance compared to linear inversion methods, where the prior information is limited to the two-point covariance of the source pixels approximated with a Gaussian form, and often specified in a relatively arbitrary manner. We combine our source reconstruction network with a convolutional neural network that predicts the parameters of the mass distribution in the lensing galaxies directly from telescope images, allowing a fully automated reconstruction of the background source images and the foreground mass distribution.
Accretion-induced Collapse of Dark Matter Admixed White Dwarfs. II. Rotation and Gravitational-wave Signals
Authors: Zha Shuai , Chu Ming-Chung , Leung Shing-Chi , Lin Lap-Ming
Published: September 2019

We present axisymmetric hydrodynamical simulations of accretion-induced collapse (AIC) of dark matter (DM) admixed rotating white dwarfs (WD) and their burst gravitational-wave (GW) signals. For initial WD models with the same central baryon density, the admixed DM is found to delay the plunge and bounce phases of AIC, and decrease the central density and mass of the protoneutron star (PNS) produced. The bounce time, central density, and PNS mass generally depend on two parameters, the admixed DM mass M
DM and the ratio between the rotational kinetic and gravitational energies of the inner core at bounce

. The emitted GWs have generic waveform shapes and the variation of their amplitudes h
+ show a degeneracy on

and M
DM. We found that the ratios between the GW amplitude peaks around bounce allow breaking of the degeneracy and extraction of both

and M
DM. Even within the uncertainties of the nuclear matter equation of state, a DM core can be inferred if its mass is greater than 0.03 M
⊙. We also discuss possible DM effects on the GW signals emitted by PNS g-mode oscillations. GWs may boost the possibility for the detection of AIC, as well as open a new window into the indirect detection of DM.
A Kinematically Cold Structure of Candidate Young OB Stars toward the Anticenter
Authors: Casetti-Dinescu Dana I. , Girard Terrence M.
Published: September 2019

We combine Galaxy Evolution Explorer and Gaia DR2 catalogs to track star formation in the outskirts of our Galaxy. Using photometry, proper motions, and parallaxes we identify a structure of ∼300 OB-type candidates located between 12 and 15 kpc from the Galactic center that are kinematically cold. The structure is located between l = 120° and 200°, above the plane up to ∼700 pc and below the plane to ∼1 kpc. The bulk motion is disklike; however, we measure a mean upward vertical motion of 5.7 ± 0.4 km s−1, and a mean outward radial motion of between 8 and 16 km s−1. The velocity dispersion along the least dispersed of its proper-motion axes (perpendicular to the Galactic disk) is 6.0 ± 0.3 km s−1, confirming the young age of this structure. While spatially encompassing the outer spiral arm of the Galaxy, this structure is not a spiral arm. Its explanation as the Milky Way warp is equally unsatisfactory. The structure’s vertical extent, mean kinematics, and asymmetry with respect to the plane indicate that its origin is more akin to a wobble generated by a massive satellite perturbing the Galaxy’s disk. The mean stellar ages in this outer structure indicate the event took place some 200 Myr ago.
An Episodic Wide-angle Outflow in HH 46/47
Authors: Zhang Yichen , Arce Héctor G. , Mardones Diego , Cabrit Sylvie , Dunham Michael M. , Garay Guido , Noriega-Crespo Alberto , Offner Stella S. R. , Raga Alejandro C. , Corder Stuartt A.
Published: September 2019

During star formation, the accretion disk drives fast MHD winds, which usually contain two components, a collimated jet and a radially distributed wide-angle wind. These winds entrain the surrounding ambient gas producing molecular outflows. We report a recent observation of 12CO (2–1) emission of the HH 46/47 molecular outflow by the Atacama Large Millimeter/submillimeter Array, in which we identify multiple wide-angle outflowing shell structures in both the blueshifted and redshifted outflow lobes. These shells are highly coherent in position–position–velocity space, extending to ≳40–50 km s−1 in velocity and 104 au in space, with well-defined morphology and kinematics. We suggest these outflowing shells are the result of the entrainment of ambient gas by a series of outbursts from an intermittent wide-angle wind. Episodic outbursts in collimated jets are commonly observed, yet detection of a similar behavior in wide-angle winds has been elusive. Here we show clear evidence that the wide-angle component of the HH 46/47 protostellar outflows experiences variability similar to that seen in the collimated component.
Bhutan’s Challenges in Biodiversity Informatics
Authors: Gyeltshen Choki , Dema Sangay
Published: September 2019

Access to reliable and updated data and information on the status of biodiversity for effective conservation and sustainable use has been one of the major challenges in Bhutan. The current scenario of inaccessibility is due to the fact that biodiversity inventories and documentation are carried out within the context of individual projects and institutions, guided by their specific objectives and collection standards, often in isolation. More critical is the fact that these data hardly get shared nor are they easily accessible, resulting in either duplication of efforts or underutilization of the existing data. It has been duly noted that despite the global recognition of Bhutan’s protected areas system and its conservation achievements, information on the existing biodiversity of these protected areas is not easily accessible. There is also inadequate information on the critical biodiverse areas of the country, making it difficult to make informed decisions for either initiating developmental activities or prioritizing the area for conservation. These gaps are acknowledged and discussed in national documents (NBSAP 2014). In order to provide easy access to comprehensive biodiversity data and information of the country and to ensure the judicious use of our scarce resources, there is a compelling need to establish a coordination mechanism for sharing data on a common platform, not only to overcome the existing gaps but also to enable consolidation and analysis of the data in order to generate information for broader use such as conservation planning or education.

Thus in 1994, Bhutan, along with the South-South Cooperation (PSC 2009), which included Benin and Costa Rica, initiated a basic biodiversity information system in each country, funded by the Kingdom of Netherlands. In 2008, the National Biodiversity Centre (NBC) developed a web-based biodiversity portal, which was subsequently upgraded to the status of a national biodiversity information clearing house in 2010. However, because of the vastness and variety of biodiversity data, it was not feasible for a single agency to collect as well as curate these vast data. Thus, in early 2013, the Centre proposed the formation of a consortium to manage biodiversity data through a strengthened and an improved version of a web-based portal. In addition, this initiative to form a consortium amongst different biodiversity stakeholders, was also to address the issue of duplicative efforts in developing and managing isolated information systems and databases. The Bhutan Biodiversity Portal (www.biodiversity.bt) was launched on 17th December 2013. Currently, the observation data has crossed 63,000 of all taxa owing mostly to the efforts of a mass campaign across the country. However, one of the major challenges is the availability of active taxonmic curators especially for the understudied taxonomic groups such as invertebrates. In addition, some users prefer social media over the portal due to its user-friendliness.
Species richness and community composition of sphingid moths (Lepidoptera: Sphingidae) along an elevational gradient in southeast Peru
Authors: Sublett Clayton A. , Cook Jerry L. , Janovec John P.
Published: September 2019

A clear low-elevation skewed unimodal richness pattern is presented for hawkmoths in Southeast Peru. Several hypotheses offer plausible explanations for such a distribution. The effects of water-energy dynamics are partially supported by a strong correlation between temperature and species richness at higher elevations. Further, hypotheses of plant diversity influences on hawkmoth ranges are supported by species richness peaking in transitional habitats. Sphingid subfamilies do not appear to be influenced by habitat type or elevational factors, such as temperature. This may make subfamily analysis a poor means of characterizing sphingid community composition unless study sites vary in the level of disturbance. This study documents 134 species in 23 genera of Sphingidae from five Southeastern Peru sites from the 7,545 specimens collected for the study.
Classes sociales européennes à l’épreuve du logement comparaison Danemark, Espagne, France et Royaume-Uni
Authors: Bugeja-Bloch Fanny
Published: September 2019

À partir des données du panel EU-SILC, cet article vise à étudier le lien entre positions de classe sur le marché du travail (définie selon la nomenclature ESeG) et positions résidentielles (selon deux dimensions : statuts d’occupation et taux d’effort pour se loger) dans quatre pays d’Europe (Danemark, Espagne, France et Royaume-Uni), choisis pour leur appartenance à des modèles de logement différents. Après une présentation des modèles en question, l’analyse empirique s’appuie sur des indicateurs de liaisons statistiques et une régression. Si les inégalités face au coût du logement dépendent davantage du revenu des ménages que de leurs positions sociales, il y a néanmoins partout un lien hiérarchique entre statut d’occupation et position sociale. Les inégalités face au coût du logement touchent le plus souvent les peu qualifiés et les petits entrepreneurs, avec des distinctions entre pays en lien avec les contextes politiques et institutionnels.
Les mots pour (ne pas) le dire. L’expression des hiérarchies et des différences sociales
Authors: Hugrée Cédric , de Verdalle Laure
Published: September 2019

Nous analysons les univers lexicaux mobilisés pour catégoriser l’espace socioprofessionnel aujourd’hui en France à partir des matériaux originaux issus d’un dispositif expérimental confrontant 547 enquêtés à un « jeu de cartes ». Il leur était demandé de classer des professions puis de formuler librement des noms pour désigner les groupes ainsi constitués. Dans une première partie, nous décrivons la grande diversité des lexiques utilisés par les enquêtés. L’identification des lexiques les plus courants permet d’interroger la proximité et les écarts qui existent entre les deux activités (classement et dénomination). Dans un second temps, nous analysons l’espace des dénominations des groupes socioprofessionnels en interrogeant les manières dont ont été dites ou tues les hiérarchies. Cela nous conduit à discuter la permanence du vocable des groupes professionnels pour exprimer ces différenciations sociales et à analyser les rapports entre les taxinomies pratiques mobilisées par les individus et les nomenclatures officielles, au premier rang desquelles les PCS. Nous mettons alors en évidence l’émergence d’un vocable de la responsabilité et de l’encadrement, et discutons de la présence de registres moraux ou critiques, moins normés, mobilisés par certains de nos enquêtés.
Entre ordonnancement hiérarchisé des professions et regroupement des métiers par domaine d’activité. La double asymétrie des représentations ordinaires
Authors: Amossé Thomas , Penissat Étienne
Published: September 2019

À partir d’un dispositif d’enquête sur tablette numérique, cet article étudie les représentations ordinaires de l’espace social. Comment les individus délimitent‑ils deux milieux sociaux dans un ensemble fermé de 11 professions appartenant à une fraction limitée de l’espace social ? Réalisés successivement sur des professions classiquement considérées comme relevant du « haut » et du « bas » de l’espace social, les classements des enquêtés démontrent en premier lieu la force toujours actuelle de l’opposition entre les professions d’employés et d’ouvriers : comme point saillant, elle délimite le principal clivage interne aux classes populaires. Pour les professions de cadres et de chefs d’entreprise ensuite, trois représentations (positionnelle, statutaire et fonctionnelle) se dégagent des classements réalisés, dont la première est clairement hiérarchisée. L’opposition selon le secteur public ou privé se retrouve dans les deux séquences de façon transversale. L’article conclut à une double asymétrie des représentations ordinaires : les hiérarchies professionnelles et sociales sont plus souvent évoquées pour et par les individus occupant une position élevée dans la société, alors que ce sont davantage des oppositions transversales (statutaires ou fonctionnelles) qui sont utilisées pour et par ceux situés plus bas dans l’échelle des emplois et des positions sociales.
Le temps du paysage. La représentation de la nature dans l’œuvre de Poussin
Authors: de Negroni Barbara
Published: September 2019

Poussin a utilisé de façon très subtile ce genre pictural qu’est le paysage, en jouant sur toutes les possibilités qu’il offre. Il réussit ainsi à raconter des histoires : les éléments narratifs sont traduits par des éléments du paysage – chemins, monuments, ciels plus ou moins paisibles, diversité des arbres ; les hommes eux-mêmes apparaissent comme des parties de la nature, dont le comportement et les actions répondent également à des lois. Le paysage devient ainsi un moyen plastique extraordinaire qui offre au spectateur l’occasion d’un déchiffrage patient pour pouvoir être pris ensuite par la force d’une expérience sensible, par le plaisir d’une composition d’ensemble, des couleurs et de la lumière.
Le métier de paysagiste
Authors: Benech Louis , de Negroni Barbara
Published: September 2019

Louis Benech s’est formé au métier de paysagiste en faisant d’abord un travail d’ouvrier horticole, et il garde une grande passion pour tout ce qui relève de la botanique, du jardinage et de la culture des jardins. Paysagiste de renommée internationale aujourd’hui, il considère que jardiner est le plus beau métier du monde, et sa passion pour son métier donne un éclairage fondamental à ce qu’est un paysage : le paysage relève à la fois de la nature et du travail des hommes, il se définit tout autant par ses caractéristiques géographiques que par toutes les aventures historiques qu’il a pu connaître.
Applications of the GPR Technique to indoor, bridge deck and pier structures: case studies in Turkey
Authors: Drahor Mahmut G. , Öztürk Caner , Ongar Atilla , Berge Meriç A.
Published: September 2019

This paper presents the results of three ground‐penetrating radar case studies applied to indoor, bridge deck, and pier construction types in Turkey. In these studies, 270‐MHz and 1600‐MHz anten‐nas were employed to determine the ability limits for construction materials and diagnostic problems associated with the materials. In addition, the importance of the selected survey direction was tested during measurement. Analysing the significance of the migration technique during the data processing stage was another important goal of these case studies. The first case study analyses the indoor applications (e.g., house, villa, and fabric) of ground‐penetrating radar and aims to identify possible cracks, structural defects, and corrosion damage. The second case applies ground‐penetrating radar to a bridge deck. The third case investigates pier construction by establishing the layout of the construction materials. Identifying possible defects, including structural problems within the pier structure, was another goal. These case studies provide interesting results in terms of physically characterizing the concrete structure and the locations of rebar and slab conditions; the work also reveals the moisture and corrosion effects inside the construction materials on indoor, bridge and pier applications of ground‐penetrating radar.
Demonstrating the contribution of dielectric permittivity to the in‐phase EMI response of soils: example from an archaeological site in Bahrain
Authors: Benech Christophe , Lombard Pierre , Rejiba Fayçal , Tabbagh Alain
Published: September 2019

Electromagnetic induction instruments (also called loop–loop, dipole–dipole, or Slingram) are now commonly used in archaeological prospecting. They are truly light instruments, which are able to measure both the apparent electrical conductivity and the apparent magnetic susceptibility of the ground. During a field test in Bahrain Island where the soil has a high clay content and a high salt content, surprisingly high values of in‐phase response were obtained at all inter‐coil spacings using CMD “Mini‐Explorer” (GF Instruments Ltd., Brno, Czech Republic) at 30 kHz, in both horizontal coplanar and vertical coplanar configurations, and the horizontal coplanar and vertical coplanar susceptibility variations were in total opposition. This apparent discrepancy is explained by considering the in‐phase responses to be dominated by the relative dielectric permittivity. Using the raw and in‐phase vertical coplanar and horizontal coplanar data, it is possible to determine and map the apparent permittivity and apparent magnetic susceptibility. For this case of slated soils with high clay content, the relative permittivity is strong but in agreement with both experimental data at lower frequencies and theoretical models reported in the literature.
Higher‐order correlative stacking for seismic data denoising based on the multiple‐domain combination
Authors: Li Jinghe , Qi Rui , Zhang Yujie , Xiong Bin
Published: September 2019

To improve the denoising performance of seismic data contaminated with random and coherent noises, a hybrid denoising scheme is proposed in this paper. It aims to whiten the random noise and identify the coherent noise for the preserved or prominent seismic features. Using the wavelet and curvelet basis functions in curvelets alternately, the hybrid denoising scheme utilises the representation of edges and singularities along curves. Then it adapts the wavelet‐based higherorder correlative stacking denoising method from seismic exploration sequentially. With regard to seismic records for bedrock surface detection after the artificial backfill, the noisy data are significantly improved both in terms of denoising and improving fidelity. To illustrate the advantage of the hybrid denoising scheme, a comparison of the performances between the different individual denoising methods, including the higher‐order correlative stacking method and curvelets with wavelet and curvelet basis functions, has been presented for the complex seismic records contaminated with different noises. Numerical case studies and a field data analysis have been used to show that the proposed hybrid denoising scheme is more effective for seismic data containing complex features than the individual denoising methods.
High‐resolution reflection seismic imaging for the planning of a double‐train‐track tunnel in the city of Varberg, southwest Sweden
Authors: Dehghannejad Mahdieh , Malehmir Alireza , Svensson Mats , Lindén Mattias , Möller Henrik
Published: September 2019

A newly developed broadband digital‐based seismic landstreamer system was employed for the planning of a double‐train‐track tunnel in the city of Varberg, southwest Sweden. Twenty‐five seismic profiles, totalling more than 7.5 km of data, were acquired using a 2‐ to 4‐m receiver and source spacing. At places where it was not possible to move the streamer such as road crossings, wireless recorders connected to 28‐Hz geophones were used. In addition to the earlier refraction data analysis and first‐break traveltime tomographic modelling, reflection processing of the data was considered in this study, given the realisation of reflections in raw shot gathers and their good quality. Bedrock is strongly reflective in most cases but is not evident in the sections when it gets near the surface. Bedrock undulation is noticeable in most reflection sections, and at one occasion, strong diffraction is observed in the bedrock or near to it. The diffraction is originated, not known during the survey, from a 400‐m3 cylindrical (of about 3‐m‐height and 13‐m‐diameter) concrete‐made fire‐protection water tank situated in the bedrock and used in emergency situations. Reflection seismic data greatly complement the tomographic models and support deep bedrock where the excavation of the tunnel is planned in downtown Varberg. This interpretation implies different reinforcements and tunnel construction methods (e.g., roofed concrete) at this section of the tunnel. In addition, weakness zones associated with fracture systems are inferred from the reflection characteristics and in conjunction with the velocity models requiring verification by additional boreholes.
Magnetic imaging of the Kurungnakh Island ice complex upper layer structure, Lena Delta, Russia
Authors: Tsibizov Leonid , Rusalimova Olga
Published: September 2019

Ground‐based detailed magnetic surveys have so far been minimally used in permafrost research but they have a great potential to explore near‐surface structures and to reveal their hidden features. This study presents the results of a two‐elevation magnetic survey on a Pleistocene ice complex covered by Holocene deposits and penetrated by ice wedges. A polygonal pattern, which is not distinctly visible on the surface, is successfully identified in the anomalous magnetic field. Obtained data allow to allocate confidently the polygon distribution and to discriminate the ice wedges of different thicknesses. Typical values of total magnetic field anomalies related to ice wedges and frozen sediments in between are about several nanoteslas measured at the elevations of 0.4 and 1.15 m above the surface. Magnetic susceptibility of the permafrost samples is on the order of 10‐4. Observed data were modelled using a numerical magnetic model to estimate quantitatively geometrical and magnetic parameters of the ice complex structure. The best‐fitting model provides the following results: the upper part of the Pleistocene and Holocene ice wedges shows a thickness of 8 and 3 m, respectively, and the upper boundary of the Pleistocene ice wedges where they contact with Holocene wedges rests at 1 m depth. The magnetic susceptibility of frozen sediments between ice wedges is about 0.14 × 10‐3. An anomalously high vertical gradient within the study area has been observed. The presumable sources for this anomaly were considered. Our results suggest that detailed magnetometry could be efficient as it is a rapid and non‐invasive reconnaissance permafrost research.
Unique insight into the seasonal variability of geophysical properties of field soils: practical implications for near‐surface investigations
Authors: Boddice Daniel , Metje Nicole , Chapman David
Published: September 2019

Electromagnetic wave propagation methods are extensively used in geophysical prospecting, such as in archaeological and utility surveys. The signal penetration and attenuation of electromagnetic waves depend strongly on the apparent permittivity and electrical conductivity of the soil, which vary on a seasonal basis, affecting the detection of buried features, especially their detected depth. Nevertheless, there is a significant lack of high‐quality long‐term seasonal field monitoring data of electromagnetic properties in different soil conditions to aid the understanding of how these properties vary in field conditions. The results reported in this paper will contribute to addressing this scarcity of data. Long‐term data are presented and analysed from bespoke time‐domain reflectometry monitoring stations designed to enable collection of apparent relative dielectric permittivity, bulk electrical conductivity, and temperature data at a high temporal resolution (hourly) from three remote sites with different soils over an extended period of time (16–23 months). In addition to providing an extensive dataset, the data highlight the importance of using accurate electromagnetic soil data for geophysical prospecting. The greatest changes in geophysical properties for all sites are detected in the near‐surface soils (< 0.5 m), where many buried utilities are generally found, with rapid wetting events and slower drying events greatly affecting both the apparent relative dielectric permittivity and the bulk electrical conductivity. However, the most critical factor for determining these properties is the soil water holding capacity, which, in turn, is a function of the clay mineralogy and content. An analysis of the ratio of energy loss to energy storage shows that the optimum time for ground penetrating radar surveying is during the dry periods and when the soil temperature is low, displaying the significance of soil temperature on survey outcomes, due to its significant effect on the bulk electrical conductivity. The results from this paper will aid survey planning, thereby ensuring a better underground target detection rate.
Self‐potential for monitoring soil remediation by smouldering: a proof of concept
Authors: Ebrahimzadeh Mehrnoosh , Tsourlos Panagiotis , Gerhard Jason I.
Published: September 2019

Near‐surface soils contaminated with non‐aqueous phase liquids, such as coal tar, crude oil, and chlorinated solvents, remain a serious problem. Smouldering remediation is a technique now being applied in the field for in situ destruction of non‐aqueous phase liquids. Based on a self‐sustaining exothermic reaction, smouldering remediation generates a hot region (>400 °C) that propagates through the subsurface. Self‐potential is here considered for the first time as a non‐destructive means for monitoring the smouldering remediation process. First, a series of sandbox experiments were conducted to investigate the magnitude of the thermoelectric coupling coefficient () for different sand sizes, water contents, and heat sources. Measured values ranged from ‐0.47 mV/°C for coarse, water‐saturated sand to ‐0.05 mV/°C for fine sand with a saturation of 30%. Next, self‐potential measurements were conducted during several laboratory smouldering remediation experiments, examining the response as a function of both space and time. A significant self‐potential anomaly was observed on the surface during the smouldering period. Moreover, the magnitude of the self‐potential anomaly was demonstrated to be highly correlated to the separation distance between the (moving) reaction front and the (stationary) self‐potential electrode positions. Overall, this research suggests that the self‐potential method has a significant promise as a non‐invasive monitoring tool for in situ smouldering remediation of contaminated sites.
Tuning, interference and false shallow gas signatures in geohazard interpretations: beyond the rule
Authors: Barrett Bonita J. , Huws Dei G. , Booth Adam D. , Wergeland Øystein , Mattias Green J.A.
Published: September 2019

Shallow gas presents a significant geohazard for drilling operations, with implications for costly well deviations and inherent blowout risks. The archetypal seismic signature of shallow gas—a “bright spot”—can be falsely induced by tuning, whereby reflections from closely separated horizons stack and constructively interfere. According to established guidelines, maximum constructive interference is typically expected where horizons are separated by one‐quarter wavelength of the seismic wavelet. Here, we test the circumstances in which false gas signatures can be induced from tuning and the conditions in which the guidelines for interference become problematic. We simulate normal‐incidence seismic data for a variety of reflectivity models, incorporating different contrasts in reflectivity magnitude and polarity. We simulate acoustic impedance by supplying initial geological parameters to Gassmann’s rock physics equations, allowing bulk density and compressional (P‐) wave velocity to vary between 1200–2100 kg/m3 and 1460–1670 m/s, respectively, for non‐gassy sediments and 1160 kg/m3 and 170–200 m/s for gassy sediments. Tuning is considered for a Ricker wavelet source pulse, having both peak frequency and effective bandwidth of 60 Hz. Tuning effects are able to mask a gas pocket, corresponding to a “false negative” signature that represents a significant hazard for drilling operations. Furthermore, the widely adopted assumption for constructive interference is not always valid as the brightest seismic responses can appear for thicker and thinner beds, depending upon the stratigraphy. Similar observations are made both qualitatively and quantitatively for real seismic responses, in which reflections from a series of dipping clinoforms interfere with those from an overlying unconformity. We conclude that greater attention should be paid to the interpretation of shallow gas risk; specifically, the effect of reflector geometries should not be overlooked as a means of producing or masking seismic amplitudes that could be indicative of a hazardous gas accumulation.
Identifying and mitigating against potential seafloor and shallow drilling hazards at a complex Gulf of Mexico Deepwater site using HR3D seismic and AUV data
Authors: Kassarie Kern , Mitchell Stephen , Albertin Martin , Hill Andrew , Carney Robert
Published: September 2019

This paper presents an integrated and iterative approach to the identification and understanding of seafloor and shallow geohazards at a complex geologic setting in the deepwater Gulf of Mexico. The approach, focusing on geophysical data gathering and processing, allowed continuous improvement in the understanding of individual geohazard risks ahead of any eventual selection of wildcat drilling locations.

The progressive development of increased image resolution has included the use of the following data types: exploration 3D, autonomous underwater vehicle seabed clearance, short‐offset 3D, a full‐waveform inversion velocity model, HR3D acquisition, HR3D, autonomous underwater vehicle high‐resolution sonar, and seabed photographic transects.

Data have assisted in revealing the presence and the understanding of, numerous seafloor and sub‐seafloor geologic features that could potentially affect the choice of well location, well trajectory, and final drilling practices. Features that have been defined have included active benthic communities, widespread seafloor faulting, multi‐scale active seabed expulsion features, slope‐failure scarps, mass transport complexes, shallow gas, and various effects from the presence and transmission of shallow overpressure towards the seafloor.

The final, integrated geologic model that is developed will allow selection of well surface locations and trajectories that meet local regulatory requirements for safe drilling and environmental protection, as well as the adoption of safe drilling practices to mitigate identified hazards.
A petrophysical approach to the investigation of shallow marine geology
Authors: Andrew Buckley Francis , Cottee Lewis
Published: September 2019

Interpretations of commercial marine shallow seismic data are generally limited to a prognosis of lithologies based on sparse ground truth data and regional stratigraphic models and a probability assessment of encountering perceived geohazards. However, an approach based on analyses of available petrophysical data can provide a more robust assessment of shallow marine lithologies and a more confident interpretation of shallow gas and overpressured formations. Generation of well‐ and borehole‐log acoustic impedance curves provides the starting point for these investigations and, although not all of the requisite data may be present in shallow section wireline suites, the Faust and Gardner equations, and other empirically derived relationships, can supply acceptable mathematical approximations. Impedance inversions of reflection seismic data facilitate more confident interpretations of lithological units, especially when combined with additional datasets such as gamma‐ray, resistivity, porosity, and S‐wave sonic, as elastic and extended elastic inversions. Anomalous seismic events interpreted to represent a probability of encountering shallow gas using traditional interpretation methods may be further investigated using amplitude‐versus‐offset cross‐plotting techniques, including fluid factor calculations, and the potential for overpressured gas accumulations or flow sands may be estimated from velocity‐derived pore pressure calculations. Geological and synthetic seismic modelling exercises provide the opportunity to test petrophysical interpretations in the absence of ground truth control data.
How understanding past landscapes might inform present‐day site investigations: a case study from Dogger Bank, southern central North Sea
Authors: Cotterill Carol , Phillips Emrys , James Leo , Forsberg Carl‐Fredrik , Tjelta Tor Inge
Published: September 2019

The integration of geophysical and geotechnical datasets acquired during a site survey for the Dogger Bank wind farm has enabled a new litho‐ and seismo‐stratigraphy to be established. Although previously believed to be a relatively simple “layer‐cake”, the data reveal that the sedimentary sequence within the foundation zone includes a complex series of buried landscapes with implications for both foundation siting and design. The most significant is a Weichselian glacially derived landscape dominated by a large thrust‐block moraine complex buried beneath a thin Holocene sequence. This glacial landscape profoundly affects the structure and physical properties of sediments within the foundation zone due to locally intense glaciotectonic deformation and the occurrence of sub‐aerially desiccated horizons recording fluctuating palaeo‐climatic conditions. Understanding these landscapes, coupled with the geophysical and geotechnical data, enables the development of a predictive “geo‐model” that may be used to target areas of uncertainty, reducing the requirement for boreholes (over Cone Penetration Tests) at every potential foundation location.
Resistivity and chargeability survey for tunnel investigation: a case study on toxic black shale in Norway
Authors: Bazin Sara , Lysdahl Asgeir K. , Viezzoli Andrea , Günther Thomas , Anschütz Helgard , Scheibz Jürgen , Pfaffhuber Andreas A. , Radic Tino , Fjermestad Halldis
Published: September 2019

In the past few years, the focus on Alum shale hazards and the need for efficient mapping tools have increased in Norway. Alum shale is highly toxic and poses a substantial obstacle to infrastructure development such as tunnel projects. We present an evaluation of the ground‐based electrical resistivity tomography, induced polarisation, and airborne electromagnetic methods for mapping purposes using a recent case study. This evaluation is done in combination with resistivity and chargeability laboratory measurements applied to drill cores. The aim of the geophysical survey was to improve the knowledge of Alum shale occurrence to assist a tunnel project in Gran, southeast Norway. Resistivity and chargeability models derived from an electrical resistivity tomography/induced polarisation survey enabled us to map the presence of Alum shale during the tunnel investigation. The resistivity models point to geological layers that are in agreement with the rock types observed from early drillings together with subsequent geological logging during tunnelling. The time‐domain chargeability models are imperfect but nonetheless reveal the presence of polarisable minerals. These are likely due to the high levels of sulphides contained in black shale. An airborne electromagnetic survey was done close to the area of interest, which enabled us to fly some sparse lines across the tunnel alignment as a piggyback survey. Although the airborne electromagnetic resolution is lower than electrical resistivity tomography, the successful test flight lines illustrate the potential of airborne electromagnetic surveys for Alum shale mapping in Norway and affirm the promise of airborne electromagnetic in the early stages of project exploration.
Three‐dimensional reconstruction of a masonry building through electrical and seismic tomography validated by biological analyses
Authors: Cardarelli Ettore , De Donno Giorgio , uliveti Ilaria , Scatigno Claudia
Published: September 2019

In this paper, we present an integrated approach, for assessing the condition of an ancient Roman building, affected by rising damp and cracking phenomena. The combination of high‐resolution geophysical methods, such as seismic and electrical tomography, with biological information, allowed a more detailed evaluation of the state of conservation of the masonry building. A preliminary three‐dimensional electrical survey was conducted to detect the existing building foundations and to determine the variation of the resistivity in the ground. Then, electrical and seismic tomography investigations were carried out on an inner wall of opus caementicium, subjected to rising damp effects and cracks. This approach was adopted to obtain a high‐resolution image of the wall, which allowed to identify the inner mortar and the outer brick component from resistivity and velocity contrasts. Furthermore, the geophysical results revealed evidence of wall fractures (indicated by low velocity and high resistivity values) and a significant volume where rising of damp was taking place (resulting in a low resistivity zone). Biological analyses validated the geophysical model: in fact, the biological proliferation occurred up to a height of 0.75 m, where the interface between high and low resistivity values was recovered. This approach can be employed to reconstruct a three‐dimensional model of masonry structures in order to plan recovery actions.