bluuebunny/crossref_metadata_2025 huggingface dataset:
Occurrences and Ecotoxicological Risk Assessment of Heavy Metals in Surface Sediments from Awash River Basin, Ethiopia
Authors: Dirbaba Niguse Bekele , Yan Xue , Wu Hongjuan , Colebrooke Luanettee’ Lydia , Wang Jun
Published: April 2018

Like many areas in developing nations, rapid population growth, a high urbanization rate, and poor waste management practices have been observed in the Awash River Basin. Moreover, no comprehensive study has been conducted in this basin to evaluate sediment contamination with heavy metals. About 46 sampling locations were considered to study heavy metal concentrations, distributions, pollution levels, and potential ecological risks associated with these contaminants. The results indicate that average concentrations of all metals have exceeded their respective background values except Pb and Hg. A comparison with similar studies also revealed that sediments from the Awash River Basin had a high average value for Cd. The mean enrichment values of heavy metals increased in the order of Hg < As < Pb < Ni < Cu < Cr < Zn < Cd. Multivariate analysis revealed that Ni and Cu had common sources. The average potential ecological risk index (ERI = 355.54) indicates high potential toxicity response in the study area. In general, surficial sediment contamination with heavy metals is causing high ecological hazards in Awash River Basin. This study sheds lights on the current level of contamination of heavy metals which are widely distributed across the sediments of rivers and streams of Awash River Basin.
Numerical Simulation of Coronal Waves Interacting with Coronal Holes. II. Dependence on Alfvén Speed Inside the Coronal Hole
Authors: Piantschitsch Isabell , Vršnak Bojan , Hanslmeier Arnold , Lemmerer Birgit , Veronig Astrid , Hernandez-Perez Aaron , Čalogović Jaša
Published: April 2018

We used our newly developed magnetohydrodynamic (MHD) code to perform 2.5D simulations of a fast-mode MHD wave interacting with coronal holes (CHs) of varying Alfvén speed that result from assuming different CH densities. We find that this interaction leads to effects like reflection, transmission, stationary fronts at the CH boundary, and the formation of a density depletion that moves in the opposite direction to the incoming wave. We compare these effects with regard to the different CH densities and present a comprehensive analysis of morphology and kinematics of the associated secondary waves. We find that the density value inside the CH influences the phase speed and the amplitude values of density and magnetic field for all different secondary waves. Moreover, we observe a correlation between the CH density and the peak values of the stationary fronts at the CH boundary. The findings of reflection and transmission on the one hand and the formation of stationary fronts caused by the interaction of MHD waves with CHs on the other hand strongly support the theory that large-scale disturbances in the corona are fast-mode MHD waves.
Short GRBs: Opening Angles, Local Neutron Star Merger Rate, and Off-axis Events for GRB/GW Association
Authors: Jin Zhi-Ping , Li Xiang , Wang Hao , Wang Yuan-Zhu , He Hao-Ning , Yuan Qiang , Zhang Fu-Wen , Zou Yuan-Chuan , Fan Yi-Zhong , Wei Da-Ming
Published: April 2018

The jet breaks in the afterglow light curves of short gamma-ray bursts (SGRBs), rarely detected so far, are crucial for estimating the half-opening angles of the ejecta (θ
j) and hence the neutron star merger rate. In this work, we report the detection of jet decline behaviors in GRB 150424A and GRB 160821B, and find θ
j ∼ 0.1 rad. Together with five events reported before 2015 and three others “identified” recently (GRB 050709, GRB 060614, and GRB 140903A), we have a sample consisting of nine SGRBs and one long-short GRB with reasonably estimated θ
j. In particular, three Swift bursts in the sample have redshifts z ≤ 0.2, with which we estimate the local neutron star merger rate density to be

or

if the narrowly beamed GRB 061201 is excluded. Inspired by the typical θ
j ∼ 0.1 rad found currently, we further investigate whether the off-beam GRBs (in the uniform jet model) or the off-axis events (in the structured jet model) can significantly enhance the GRB/GW association. For the former, the enhancement is at most moderate, while for the latter the enhancement can be much greater and a high GRB/GW association probability of ∼10% is possible. We also show that the data of GRB 160821B may contain a macronova/kilonova emission component with a temperature of ∼3100 K at ∼3.6 days after the burst and more data are needed to ultimately clarify.
Bimodal Formation Time Distribution for Infall Dark Matter Halos
Authors: Shi Jingjing , Wang Huiyuan , Mo H. J. , Xie Lizhi , Wang Xiaoyu , Lapi Andrea , Sheth Ravi K.
Published: April 2018

We use a 200

a-side N-body simulation to study the mass accretion history (MAH) of dark matter halos to be accreted by larger halos, which we call infall halos. We define a quantity

to characterize the MAH of infall halos, where

and

are the accretion and formation redshifts, respectively. We find that, at given

, their MAH is bimodal. Infall halos are dominated by a young population at high redshift and by an old population at low redshift. For the young population, the

distribution is narrow and peaks at about 1.2, independent of

, while for the old population, the peak position and width of the

distribution both increase with decreasing

and are both larger than those of the young population. This bimodal distribution is found to be closely connected to the two phases in the MAHs of halos. While members of the young population are still in the fast accretion phase at z
peak, those of the old population have already entered the slow accretion phase at

. This bimodal distribution is not found for the whole halo population, nor is it seen in halo merger trees generated with the extended Press–Schechter formalism. The infall halo population at

are, on average, younger than the whole halo population of similar masses identified at the same redshift. We discuss the implications of our findings in connection to the bimodal color distribution of observed galaxies and to the link between central and satellite galaxies.
Magnetic Shocks and Substructures Excited by Torsional Alfvén Wave Interactions in Merging Expanding Flux Tubes
Authors: Snow B. , Fedun V. , Gent F. A. , Verth G. , Erdélyi R.
Published: April 2018

Vortex motions are frequently observed on the solar photosphere. These motions may play a key role in the transport of energy and momentum from the lower atmosphere into the upper solar atmosphere, contributing to coronal heating. The lower solar atmosphere also consists of complex networks of flux tubes that expand and merge throughout the chromosphere and upper atmosphere. We perform numerical simulations to investigate the behavior of vortex-driven waves propagating in a pair of such flux tubes in a non-force-free equilibrium with a realistically modeled solar atmosphere. The two flux tubes are independently perturbed at their footpoints by counter-rotating vortex motions. When the flux tubes merge, the vortex motions interact both linearly and nonlinearly. The linear interactions generate many small-scale transient magnetic substructures due to the magnetic stress imposed by the vortex motions. Thus, an initially monolithic tube is separated into a complex multithreaded tube due to the photospheric vortex motions. The wave interactions also drive a superposition that increases in amplitude until it exceeds the local Mach number and produces shocks that propagate upward with speeds of approximately 50 km s−1. The shocks act as conduits transporting momentum and energy upward, and heating the local plasma by more than an order of magnitude, with a peak temperature of approximately 60,000 K. Therefore, we present a new mechanism for the generation of magnetic waveguides from the lower solar atmosphere to the solar corona. This wave guide appears as the result of interacting perturbations in neighboring flux tubes. Thus, the interactions of photospheric vortex motions is a potentially significant mechanism for energy transfer from the lower to upper solar atmosphere.
Pre-eruptive Magnetic Reconnection within a Multi-flux-rope System in the Solar Corona
Authors: Awasthi Arun Kumar , Liu Rui , Wang Haimin , Wang Yuming , Shen Chenglong
Published: April 2018

The solar corona is frequently disrupted by coronal mass ejections (CMEs), whose core structure is believed to be a flux rope made of helical magnetic field. This has become a “standard” picture; though, it remains elusive how the flux rope forms and evolves toward eruption. While one-third of the ejecta passing through spacecraft demonstrate a flux-rope structure, the rest have complex magnetic fields. Are they originating from a coherent flux rope, too? Here we investigate the source region of a complex ejecta, focusing on a flare precursor with definitive signatures of magnetic reconnection, i.e., nonthermal electrons, flaring plasma, and bidirectional outflowing blobs. Aided by nonlinear force-free field modeling, we conclude that the reconnection occurs within a system of multiple braided flux ropes with different degrees of coherency. The observation signifies the importance of internal structure and dynamics in understanding CMEs and in predicting their impacts on Earth.
The X-Ray Modulation of PSR J2032+4127/MT91 213 during the Periastron Passage in 2017
Authors: Li K. L. , Takata J. , Ng C. W. , Kong A. K. H. , Tam P. H. T. , Hui C. Y. , Cheng K. S.
Published: April 2018

We present the Neil Gehrels Swift Observatory (Swift), Fermi Large Area Telescope (Fermi-LAT), and Karl G. Jansky Very Large Array (VLA) observations of the γ-ray binary PSR J2032+4127/MT91 213, of which the periastron passage recently occurred in 2017 November. In the Swift X-ray light curve, the flux was steadily increasing before 2017 mid-October, however, a sharp X-ray dip on a weekly timescale is seen during the periastron passage, followed by a post-periastron X-ray flare lasting for ∼20 days. We suggest that the X-ray dip is caused by (i) an increase of the magnetization parameter at the shock, and (ii) the suppression due to the Doppler boosting effect. The 20-day post-periastron flare could be a consequence of the Be stellar disk passage by the pulsar. An orbital GeV modulation is also expected in our model; however, no significant variability is seen in the Fermi-LAT light curve. We suspect that the GeV emission from the interaction between the binary’s members is hidden behind the bright magnetospheric emission of the pulsar. The pulsar gating technique would be useful to remove the magnetospheric emission and recover the predicted GeV modulation, if an accurate radio timing solution over the periastron passage is provided in the future.
Discovery of a New Fundamental Plane Dictating Galaxy Cluster Evolution from Gravitational Lensing
Authors: Fujita Yutaka , Umetsu Keiichi , Rasia Elena , Meneghetti Massimo , Donahue Megan , Medezinski Elinor , Okabe Nobuhiro , Postman Marc
Published: April 2018

In cold dark-matter (CDM) cosmology, objects in the universe have grown under the effect of gravity of dark matter. The intracluster gas in a galaxy cluster was heated when the dark-matter halo formed through gravitational collapse. The potential energy of the gas was converted to thermal energy through this process. However, this process and the thermodynamic history of the gas have not been clearly characterized in connection with the formation and evolution of the internal structure of dark-matter halos. Here, we show that observational CLASH data of high-mass galaxy clusters lie on a plane in the three-dimensional logarithmic space of their characteristic radius r

s
, mass M

s
, and X-ray temperature T
X with a very small orthogonal scatter. The tight correlation indicates that the gas temperature was determined at a specific cluster formation time, which is encoded in r

s
and M

s
. The plane is tilted with respect to T
X ∝ M

s
/r

s
, which is the plane expected in the case of simplified virial equilibrium. We show that this tilt can be explained by a similarity solution, which indicates that clusters are not isolated but continuously growing through matter accretion from their outer environments. Numerical simulations reproduce the observed plane and its angle. This result holds independently of the gas physics implemented in the code, revealing the fundamental origin of this plane.
Asymmetry of Line Profiles of Stellar Oscillations Measured by Kepler for Ensembles of Solar-like Oscillators: Impact on Mode Frequencies and Dependence on Effective Temperature
Authors: Benomar O. , Goupil Mjo. , Belkacem K. , Appourchaux T. , Nielsen M. B. , Bazot M. , Gizon L. , Hanasoge S. , Sreenivasan K. R. , Marchand B.
Published: April 2018

Oscillation properties are usually measured by fitting symmetric Lorentzian profiles to the power spectra of Sun-like stars. However, the line profiles of solar oscillations have been observed to be asymmetrical for the Sun. The physical origin of this line asymmetry is not fully understood; though, it should depend on the depth dependence of the source of wave excitation (convective turbulence) and details of the observable (velocity or intensity). For oscillations of the Sun, it has been shown that neglecting the asymmetry leads to systematic errors in the frequency determination. This could subsequently affect the results of seismic inferences of the solar internal structure. Using light curves from the Kepler spacecraft, we have measured mode asymmetries in 43 stars. We confirm that neglecting the asymmetry leads to systematic errors that can exceed the 1σ confidence intervals for seismic observations longer than one year. Therefore, the application of an asymmetric Lorentzian profile should be favored to improve the accuracy of the internal stellar structure and stellar fundamental parameters. We also show that the asymmetry changes sign between cool Sun-like stars and hotter stars. This provides the best constraints to date on the location of the excitation sources across the Hertzsprung–Russel diagram.
New European records of Ditomyia macroptera Winnertz (Diptera: Ditomyiidae) with notes on its distribution
Authors: Kurina Olavi , Chandler Peter
Published: April 2018

Ditomyia macroptera Winnertz, the rarest European ditomyiid fly, is known only by a few specimens across the collections. Besides a single male specimen from Sakhalin Island, all other documented records are from Central Europe.

New records of Ditomyia macroptera Winnertz from Bulgaria and France are presented representing the second rearing event after its initial description. Illustrations of the general facies and male terminalia are given. The study of old collection material reveals exclusion of the species from the Belgian list and allows us to discuss the origin of two specimens in the collection of C.R. Osten-Sacken in St. Petersburg, Russia.
Les besoins en informations dans les entreprises
Authors: Tchouassi Gérard
Published: April 2018

L’objectif de cette contribution est d’analyser les besoins en information dans les entreprises. Cette analyse s’effectue sous le prisme de l’intelligence économique, des systèmes d’aide à la décision, tout en valorisant les principaux canaux de circulation de l’information en entreprise. Les besoins en information sont de deux types : permanents et ponctuels. La définition des besoins en information conduit à une conception d’axes stratégiques de veille économique sur lesquels le dispositif de l’entreprise va se focaliser. Le système d’aide à la décision permet d’évaluer l’information qui provient de l’intérieur ou de l’extérieur de l’entreprise.
Filiations humaines, filiation divine
Authors: Lefebvre Philippe
Published: April 2018

La Bible commence par affirmer que toute filiation vient de Dieu. Elle ne concerne pas seulement le « coup d’envoi » que représente la création des humains. Chaque humain se découvre en effet « façonné » par Dieu, voulu, prévu, annoncé. Comment dès lors penser les engendrements, les tôledôt , dont les déploiements fleurissent dans la Genèse notamment ? Paradoxalement, les stériles qui malgré tout enfantent donnent la norme de toute naissance humaine en mettant en lumière l’initiative divine. Mais entrer dans la filiation n’est ni un dû ni un acquis : un acquiescement est nécessaire, une disposition à cheminer. Femmes et hommes ne sont pas situés de la même manière sur l’« axe » de la filiation : les unes témoignent d’un Dieu Père, les autres ont à devenir fils-devant-Dieu.
Filiation et procréation dans l’éthique catholique
Authors: de Longeaux Jacques
Published: April 2018

Le magistère de l’Église catholique a publié depuis cinquante ans plusieurs documents importants sur l’éthique de la procréation et de la filiation. Cet article tente de mettre en évidence les lignes de force de cet enseignement que l’on ne peut réduire à l’affirmation de la valeur normative des processus biologiques. La réflexion sur le corps, comme expression de la personne, lieu de la relation et épreuve du réel, occupe une place centrale, particulièrement dans la pensée de Jean-Paul II. Elle garde toute son actualité à notre époque où la question de la valeur de notre appartenance au monde des vivants se fait plus pressante. Est-il sage de vouloir à tout prix contourner les déterminations fondamentales de notre existence corporelle ?
L’essor des techniques de dépistage prénatal
Authors: Thiel Marie-Jo
Published: April 2018

Le diagnostic prénatal né dans les années 1970 connaît aujourd’hui un développement dans son efficience, son extension et la complexité des données mobilisées. Il vient à englober des tests médicaux et génétiques réalisés à divers moments : le diagnostic préimplantatoire, le dépistage prénatal orienté dans lequel le DPNI (dépistage prénatal non invasif) ouvre potentiellement la voie à l’analyse de l’ensemble du génome de l’enfant à naître, et donc son éventuelle élimination pour non-conformité aux attentes (individuelles et sociétales). Insidieusement, la sélection s’élargit, interrogeant, en particulier dans le contexte socio-politique français (gratuité du suivi, confiance en la science), sur les pratiques mises en place, leur caractère discriminant, voire eugéniste (pour la trisomie 21).
De la vulnérabilité à la capacitation
Authors: Wayezu Justine Mbelu
Published: April 2018

La vulnérabilité se comprend de plusieurs manières. Une signification transversale et permanente est celle de l’exposition à la blessure, au risque et à la menace. Les entretiens accordés aux femmes membres d’un réseau de solidarité des femmes enceintes de Kinshasa permettent d’étudier divers degrés de vulnérabilité vécus par ces femmes, ainsi que la possibilité d’en faire un espace de résilience. Après une définition du terme vulnérabilité et du contexte du réseau de solidarité, l’article montre les résultats des entretiens et indique les niveaux de vulnérabilité selon les femmes. L’analyse montre que la vulnérabilité d’abord vécue comme manque d’argent et précarité de la situation des femmes au Congo, peut progressivement devenir une source de capacitation pour la mise en place d’un réseau de solidarité.
Les technocrates du ministère des Finances et le tournant de la rigueur de 1983
Authors: Descamps Florence
Published: April 2018

Entre 1981 et 1983, les hauts fonctionnaires français du ministère des Finances rétablissent progressivement leur audience et leur crédit auprès des gouvernants socialistes, qui avaient dans un premier temps donné la priorité à un programme politique social et à une relance économique d’inspiration keynésienne. À l’occasion de la crise financière de 1982-1983 qui conduit le président François Mitterrand à faire le choix de l’Europe et à rectifier la politique économique, ils militent pour un plan de redressement des finances publiques et s’engagent dans une politique de lutte contre l’inflation dont il conviendra de déterminer si elle témoigne ou non d’une conversion au néolibéralisme.
Quand Pierre Mauroy résistait avec rigueur au « néolibéralisme » (1981-1984)
Authors: Fulla Mathieu
Published: April 2018

Cet article interroge l’idée d’une conversion précoce et résolue des élites socialistes françaises aux charmes du néolibéralisme au début des années 1980. François Mitterrand endosserait-il les habits de Ronald Reagan en mars 1983, tandis que Pierre Mauroy ferait du néolibéralisme sans le savoir ? L’examen des archives de la présidence de la République et de Matignon révèle le caractère néolibéral extrêmement discret, pour ne pas dire introuvable, de la politique économique socialiste. Si entrée de la France dans une forme de néolibéralisme économique il y eut, celle-ci est bien davantage à chercher dans les politiques suivies par les gouvernements Fabius et Chirac que dans celles menées par Pierre Mauroy.
L’impossible réforme de la Banque de France dans les années 1980
Authors: Blancheton Bertrand
Published: April 2018

Cet article met en perspective les projets de réformes de l’autonomie de la Banque de France dans les années 1980. Il analyse les débats théoriques anglo-saxons autour de l’indépendance, la lenteur de leur pénétration en France, l’évolution du degré d’autonomie juridique et opérationnelle de la Banque de France sous les gouvernements Mauroy et Fabius. L’échec de trois projets de réforme révèle l’attachement des responsables politiques et administratifs à la maîtrise des leviers monétaires et budgétaires et un scepticisme sur la capacité de l’autonomie à mieux garantir la stabilité des prix.
Le spectre de la crise financière française de 1983
Authors: Warlouzet Laurent
Published: April 2018

Cet article revisite le « tournant de la rigueur » de mars 1983 grâce à de nouvelles archives ouest-européennes issues des gouvernements britanniques et allemands, de la Bundesbank, et de la Confédération européenne des syndicats. Il montre qu’un tournant véritable eut lieu en mars 1983 du fait du risque de crise financière, avec une possible intervention du Fonds monétaire international. La résolution de la crise a été essentiellement franco-allemande. Elle a permis une convergence des politiques économiques qui traduit moins un tournant néolibéral, que l’adoption de politiques de libre-marché perçues comme mieux adaptées au défi de la mondialisation, sans être incompatibles avec des politiques sociales.
Modelling Regional Networks and Local Adaptation: West-Central Sicilian Relief Louteria
Authors: Ward Andrew Farinholt
Published: April 2018

The consumption and adaptation of Greek material culture by non-Greek peoples in ancient western Sicily, and the wider Mediterranean, has been an ongoing point of contention in scholarship: do Greek objects influence the peoples that use them, and by their movement and trade are these objects and their figured surfaces active agents of Hellenization? Acknowledging that framing future discussion through postcolonialism only perpetuates the anachronistic colonialist model, this dissertation applies the materialist theory of transculturality to an understudied class of terracotta objects distributed and adapted through Ancient Sicily: louteria, arulae, and other ritual furniture impressed with cylinder-roll matrices. This announcement summarizes the results of an interdisciplinary methodology combining technical and iconographic analyses of the stamp series, reconstruction of the then-stamped terracottas’ contexts, and spatial and statistical modelling of their distribution patterns. This holistic approach to material study reveals a highly complex network of exchange, adaptation, and local production in sixth and fifth century Sicily far more dynamic than the simple binary of colonizer and colonized.
Negotiating Streets and Space in Transnational Trade Marketplaces in Oran (Algeria) and Cairo (Egypt): “Place Struggle” in the Commercial City
Authors: Bouhali Anne
Published: April 2018

Built on empirical material from field study conducted between 2011 and 2014 and based on a qualitative methodology, this paper aims at highlighting the struggles for power within the appropriation of commercial streets inside two transnational trade centralities, al-Muski in Cairo (Egypt) and Medina J’dida in Oran (Algeria). It demonstrates that street vendors have known how to benefit from the weakening and/or the weakness of urban authorities and have been able to negotiate their place and their presence in the public space. First, the paper presents the general development of street vending in the two transnational commercial centralities. Then, it analyses the unsettled and often tense relationships between street vendors and urban authorities, where the control of public space and, through it, the control of the city at large is at stake. Finally, it highlights the complex power relationships between street vendors and official traders who compete for marketplace access. In summary, while facing an ever-changing environment filled with contradictions, street vendors constantly have to negotiate their place in these two marketplaces, and through them, in the city.
Client-Awareness Resource Allotment and Job Scheduling in Heterogeneous Cloud by Using Social Group Optimization
Authors: Phani Praveen S.  , Rao K. Thirupathi
Published: April 2018

Often cloud providers and cloud clients illustrate several constraints and thus allocation of resources in a heterogeneous cloud is a difficult job. As the traffic flow is quite subjective and Client necessities and applications size vary regularly, the major challenge and concern is to map the external job requests to available virtual machines. To reduce the gap among regularly altering client requirements and existing resources, Client-Awareness Allocation of Resources and Scheduling of jobs in cloud by using social group optimization (SGOCARAJS) is proposed. This algorithm is mainly split into two phases namely allocation of resources using SGO and shortest job first scheduling. The main aim is to map the jobs to virtual machines of cloud group to attain higher client satisfaction and lowest makespan time. Experiments are conducted on datasets and results are compared with present scheduling techniques. This model proved that this algorithm outrun the available algorithms based on concerned metrics.
China Digital Governance Development Review Over the Past Two Decades
Authors: Kang Wei , Wang Yang
Published: April 2018

This article describes how with the emergence of ubiquitous technology, intelligence, and the rise of social networks facilitated by mobile Internet, big data, cloud computing and other emerging technologies, it has become a global trend that digital governance has been employed in the executive branches of many countries in the world. This article explores the data of quantity of published articles, researchers, research institutes, high-frequency key words, etc., obtained through CiteSpaceIII. The analysis of the articles related to digital governance for the recent 20 years are used to perform content analysis on the research topic and evolution. The development situations and problems of digital governance research in China are analyzed based on the literature review. The future study direction is prospected.
Optimal Descriptor Based QSPR Models for Catalytic Activity of Propylene Polymerization
Authors: Begum Sanija , Achary P. Ganga Raju
Published: April 2018

A heterogeneous Ziegler–Natta (ZN) catalyst is an important catalyst in the field of the polypropylene polymerization industry. The role of electron donors has been crucial in the ZN catalyzed polypropylene polymerization process. In this article, quasi-SMILES-based QSPR models are elaborated for the prediction of catalytic activities. The representations of the molecular structure by quasi-simplified molecular input line entry system were the basis to build the desired QSPR model. These models were developed by means of the Monte Carlo optimization involving the available methods classic scheme (CS), balance of correlations (BC) and balance of correlation with ideal slopes (BCIS). The best QSPR model showed r2 = 0.813 (for external validation set), rm2 (avg)=0.73 and ∆rm2= 0.03.
QSAR and QAAR Studies on Mixtures of 3-(Benzylidene)Indolin-2-One Isomers as Leads to Develop PET Radiotracers for Detection of Parkinson's Disease
Authors: Bhayye Sagar S. , Saha Achintya
Published: April 2018

Deposition of α–synuclein, tau and β–amyloid protein plaques in brain leads to neurodegeneration. A series of indolin derivatives, which can bind to α–synuclein and detect Parkinson's disease (PD), were used for development of QSAR and QAAR models. It is the first attempt of QSAR for any radiotracer agents used for detection of PD. The binding affinity against α–synuclein was used as dependent variable while independent variables, such as structural, topological, E-state keys, electronic, molecular shape analysis and spatial molecular descriptors were used for QSAR modeling. For QAAR modeling, the binding affinities of molecules for tau and β–amyloid along with different molecular descriptors were used as independent variables. All models were successfully developed using multiple linear regression method, and validated internally and externally, based on different standard criteria. This article describes how the derived models postulate that conformation of molecules and presence of unsaturated hydrocarbon chains, nitro, methoxy and amine functionalities play an important role in determining binding affinity.
Cooperation in Incremental Innovation Activities
Authors: Sadgui Rachid , Benchekara Mohamed
Published: April 2018

This paper analyses the impact of cooperation strategies on incremental innovation capacity, and the determinants of the cooperative arrangements for innovation. More precisely, the authors identify the cooperation strategies that should be preferred in the case of incremental innovation and the determinants of cooperation for innovation, depending on the partner with whom cooperation is established. The data they use come from the National Innovation Survey. The authors' results suggest, on the one hand, that incremental innovation is achieved through vertical and institutional cooperation (except universities). On the other hand, it has proved that there are complementarities between the various cooperation strategies for innovation and that the determinants of cooperation differ significantly between partners. Furthermore, the results confirm the interdependence of cooperation strategies revealing heterogeneity in the determinants of cooperation strategies. These findings and their implications are discussed.
The AHP Method for the Evaluation and Selection of Complementary Products
Authors: Lamaakchaoui Chaimae , Azmani Abdellah , El Jarroudi Mustapha
Published: April 2018

This article describes how when having already purchased one product, it is likely that a consumer may look for complementary ones. That is why almost recommender systems integrate modules for managing complementarity between products and services. An Analytic Hierarchy Process (AHP) based model is described in the present paper, whose objective is to help recommend to customers among a set of complementary products the best ones. Selecting the best complementary products is done through an evaluation process of the alternatives according to a number of criteria.
An Analysis of the Factors Influencing the Adoption of Online Shopping
Authors: Tarhini Ali , Alalwan Ali Abdallah , Al-Qirim Nabeel , Algharabat Raed , Masa'deh Ra'ed
Published: April 2018

This article aims to identify the main influencing factors that may influence the adoption of online shopping in the UK by integrating Unified Theory of Acceptance and Use of Technology2 (UTAUT2) and DeLone-McLean model of IS Success with trust (TR), product variety (PRDV) and product guarantee. Data was collected from 388 British online shopping consumers using a structured self-administrated questionnaire. Structural equation modeling (SEM) showed that behavioural intention (BI) was influenced by performance expectancy (PE), convenience (CON), service quality (SerQ), trust (TR), product guarantee (PG), product guarantee (PRDV) and compatibility (COMP), in their order of influencing strength and all together accounted for 70.4% of the variance in BI. Contrary to the authors' expectations, effort expectancy (EE) and social influence (SI) did not have an influence on BI. The implications of this article to both theory and practice is discussed at the end.
Automated Model Building: The Next AI Frontier in Predictive Maintenance
Authors: Herve P. , Haddad G. , Moore K. , Rosner M.
Published: April 2018

Predictive maintenance has become the paradigm of choice for the largest industrial companies because of the value it derives, including reduced downtime, improved efficiency, reduced maintenance costs, and others. Success of predictive maintenance programs is achieved when data, analytics, and subject matter expertise intersect. While data and subject matter expertise are always available, analytics talent is often lacking or facing numerous challenges which hinders the success of predictive maintenance programs.

Automated model building (AMB) aims at delivering artificial intelligence to the fingertips of industrial companies and hence ensuring the success of predictive maintenance programs without the need of large data science organizations.

The automated model building platform ingests the operational (sensor) and failure/fault data and automatically builds AI models to predict the remaining useful life for the asset. The patented technology behind the platform drives feature engineering and model selection which allows customers to automatically create numerous new variables from the sensor data and tests thousands of different models. The platform will then select the optimal set of variables and the model that will achieve the best performance.

The entire process can be performed in a matter of few minutes without the need to know the details of all AI models. The platform also gives details on the selected models, which aids with interpretability.
Numerical Modeling of High Length-to-Diameter Ratio Riser Subjected to VIV
Authors: Kara M. C. , Jaiswal V. , Sharma P. P. , Tulimilli B. , Cosgrove S.
Published: April 2018

Modeling of long marine risers subjected to VIV is a challenging problem to solve using 3D Computational Fluid Dynamics (CFD) due to the high length-to-diameter ratio and usage of different VIV suppression devices. The scale of the problem can also get extremely large as the risers may have lengths up to thousands of meters, which makes it hard to use 3D CFD simulations. However, CFD is unique to capture complex flow around bluff structures and able to model risers with and without suppression devices and involve effects of nonlinear structural response inherently.

ExxonMobil's high quality data on the behavior of high length-to-diameter ratio (L/D) risers subjected to vortex induced vibrations (VIV) in uniform and sheared flow (Marintek, 2003) exposes some of the physical details of full-scale riser response and compares the multi-mode VIV response of risers without suppression devices to that of risers with varying lengths of suppression coverage. In this paper, ExxonMobil data is investigated and validated using CFD code AcuSolveTM, which uses a strongly coupled numerical method that simultaneously solves fluid phase equations and structural equations of motion through modal analysis to predict the vibration response. Numerical simulations for high L/D bare riser response show that the method provides a good estimation of VIV responses in both in-line and crossflow directions by comparing numerical results against available field data.
Maximize EOR Potential by Optimizing Miscible CO2 Injection Parameters in Carbonate Reservoirs
Authors: Chen Peila , Kalam Mohammed Zubair , Al Kindi S A , Abolhag Yasser Hazem , Shtepani Edmond
Published: April 2018

CO2 injection to improve oil recovery has been successfully implemented in many oil reservoirs worldwide for almost half century. Conventional CO2 injection strategies, such as continuous CO2 flooding, water-alternating-gas (WAG) or carbonated water injection (CWI), were usually studied for their technical viability and cost effectiveness before deployment. This paper aimed to optimize the parametric design of CO2 injection schemes in a carbonate reservoir, and evaluated the impacts of WAG slug size, WAG sequence, and the initial gas saturation (Sgi) on the incremental oil recovery factors.

This paper presents the results from experimental and numerical studies on the different forms of CO2 floods. We compared the secondary and tertiary recovery modes, and studied the effects of initial gas saturation on EOR performance, through a series of core flood experiments under reservoir conditions and detailed compositional simulation in a commercial simulator.

The EOR core flood experiments were performed in a 2-ft long composite of carbonate cores, which were restored to reservoir wettability at reservoir conditions. The experiment indicates that carbonated water injection (CWI) in tertiary mode renders additional oil recovery ~ 20% OOIP above the waterflood (42% OOIP). In the cases of zero initial gas saturation or the reservoir pressure is above the bubble point, all three forms of CO2 injection (i.e. CO2 continuous, CO2-brine WAG and Brine-CO2 WAG) achieved > 93% OOIP recovery factor in the laboratory coreflood studies. If the reservoir was injected with produced/injector gas under immiscible conditions to support the reservoir pressure, the miscible gas EOR using CO2 WAG dropped by 10-15% OOIP compared with the corresponding cases of zero initial gas saturation. Therefore, it is recommended to implement miscible CO2 WAG flood after the initial gas saturation is minimized. Simulation studies with EOS model were carried out to simulate all of these EOR corefloods, taking into account of the effects of relative permeability hysteresis, wettability and Sorm (residual oil saturation) on oil recovery. The simulation results agree well with the laboratory results.

In Summary, the presence of initial gas saturation in carbonate reservoirs reduces CO2 EOR performance under the miscible conditions. Without the presence of Sgi, the recovery factors from all the forms of CO2 EOR appear to be very similar in laboratory scale study. CWI was proved to be a good alternative to CO2 WAG, only when a significant amount of CWI is injected into the reservoir. These key findings have been validated by core flood experiments and compositional simulation studies with tuned EOS models.
AOGV: New Method for Process Isolation
Authors: Rosén Kenneth O. , Aamodt Kjetil , Mikkelsen Kurt
Published: April 2018

Inserting a positive isolation spade on live pipe flanges is a game changer. The purpose of the tool is to enable safe isolations and to reduce extent and duration of production shutdowns, adding value of 2-20 MUSD per application. The principle design was developed within the Company addressing shortcomings of traditional isolation methods. The tool is field proven on a platform on the NCS.

Plants have large volumes which require substantial preparation and start up activities in relation to performing maintenance operations. The isolation tool can shorten shut down periods significantly thereby reducing cost.

Typical applications may include replacement of valves and piping, isolate heat exchangers for chemical cleaning or replacing leaking flange gasket with new gaskets and bolts. The live isolation tool can turn the original spectacle blinds on live systems, replace elements connected to piping systems, floating hulls, connections to high volume tanks.

The tool can be installed on a pair of flanges at the maintenance location and significantly reduces the need for drainage, venting purging and flushing.

A field proven tool for live process isolation has been demonstrates as a safe and cost saving technology. The technology is patented and is significantly different from existing methods of line stopping. There is a wide range of application areas in Facilities and Production Operations and the new tool will increase plant uptime.

The case study is based on the first field application of the live isolation tool on a 24" flange without draining the inventory. No conventional isolation methods were feasible in this isolation case to facilitate chemical cleaning of a heat exchanger thereby sustaining uptime in a large process plant on major offshore platform NCS.
Wet Gas Production from a Semi-Submersible with On-Board Condensate Storage
Authors: Rijken Oriol
Published: April 2018

A semi-submersible is a field proven solution that allows for hydrocarbon production through steel catenary risers for locations subjected to very intense hurricane / cyclonic / typhoon conditions. The semi-submersible can be made applicable to a broader range of offshore fields if it is able to export a dry gas. The produced liquids – condensate – may be stored onboard the semi-submersible and be off-loaded via a shuttle tanker.

While at first sight a typical semi-submersible has ample room for storage of condensate, the storage and off-loading requirements introduce a whole new set of functional, regulatory and safety requirements to the system. Operator requirements and operator preferred practices impose additional requirements. In a sense, the semi-submersible with storage fulfills several of the functions also found on an FPSO, though volumetric quantities are much smaller, a range of 100,000 bbls to 150,000 bbls of storage is considered.

Regulatory requirements, such as set forth in IMO, MODU, MARPOL, Flag State and Class, are typically intended for oil tanker / FPSO application, and their applicability to semi-submersible can be ambiguous. Regulatory requirements to consider include double-hull requirement, whether unsegregated storage is allowed and the definition of Classified Spaces and confined spaces, whether hydrocarbon storage during (hurricane) abandonment is allowed, etc.

Whether to store the hydrocarbons separately or unsegregated is one of the most important decisions that affect the layout, geometry and thus cost of the semi-submersible. Also the off-load frequency, the off-load parcel size, and whether to allow for a varying draft or to maintain draft and compensate for the varying condensate payload, have a significant impact on the overall concept. The storage compartments inside the hull will have to be compatible with the hull framing and equipment already located inside the hull.

Producing wet gas into a dry gas and condensate is proven technology on a semi-submersible and FPSO. Analogous to the FPSO, the produced condensate is first kept in storage tanks and is then transferred to an off-loading vessel. The location of the offloading equipment and tank cleaning, as performed on an FPSO, are additional operational aspects be addressed. Above all, the marine crew on the semi-submersible will now have to be much more familiar with marine operations than what they are today.

This paper identifies and discusses the additional requirements that are the result of storing condensate (hydrocarbons) in the hull of a semi-submersible. Many of these requirements have a large impact on the design and operation of the semi-submersible. The paper indicates that a semi-submersible with condensate storage of 125,000 bbls is practical and a layout is provided at concept level.
Wind-Induced Fatigue of Onshore Frame Structures
Authors: Lee Won Ho , Malinowski Grzegorz , Szalewski Piotr
Published: April 2018

The paper presents a proposed methodology to evaluate wind-induced fatigue of onshore slender frame structures with lattice-type design. The methodology for fatigue evaluation is based on a similar offshore industry design practice and has been repurposed for large onshore structures fabricated from tubular pipes, square tubes, and angle bars exposed to wind loading, including wind buffeting loads and wind vortex shedding.

Multiple cracks resulting from wind-induced fatigue have been experienced on offshore installed flare booms and flare towers. Consequently, design codes were introduced, and it has been a standard design practice to evaluate potential fatigue damage of slender frame structures due to vibrations induced by vortex shedding, as well as buffeting loads due to gusting. This is, however, not yet standard design practice for land-based slender frame structures despite obvious similarities in terms of structural configuration, size, wind loads, and consequences of failure. Some operators have internal requirements to assess these operational risks.

In this study, wind-induced fatigue design and analysis methodologies have been developed and calibrated based on offshore design practices. The proposed methodology uses a spectral analysis method that considers wind data, and includes simplified design checks as well as advanced analysis approaches. Further comparisons are presented for structural configuration and various end connection types with relevant examples. Both welded and gusset-type bolted connection of tubular members are investigated. This paper provides designers with methodology guidance to calculate structural fatigue damage due to both wind buffeting loads and vortex shedding vibrations. Key design considerations for wind fatigue analysis, typical design solutions and recommendations for improvements of fatigue life, and practical ways for the global fatigue screening are also provided.
Reservoir Management of the Campos Basin Brown Fields
Authors: Dumas Guilherme E. S. , Freire Ednilson B. , Johann Paulo R. S. , Silva Luciana S. , Vieira Roberto A. B. , Bruhn Carlos H. L. , Pinto Antonio C. C.
Published: April 2018

Over the last 40 years Petrobras has developed several oilfields in the prolific Campos Basin, including giant fields such as Marlim, Roncador and Jubarte, among others. All of these giant fields produce mostly from siliciclastic turbidite reservoirs, ranging in age from Albian to Miocene, which contain medium API gravity oil (mostly 18 – 24°API). Sea water injection is the main method for improving oil recovery. Reservoir management is particularly complex because of the deep to ultra-deep water depth and the use of subsea well completion. Therefore, several methodologies, tools and technologies are required to help reservoir management, such as: (1) data acquisition for reducing reservoir uncertainties, including extended well tests in the development plan design phase; (2) continuous improvement in the reservoir characterization and modeling incorporating dynamic data; (3) 4D seismic for monitoring oil and gas production, allowing the identification of areas with bypassed oil and secondary gas caps; (4) single well and inter-well tracers and production logs, also to help tracking the remaining oil; (5) infill drilling, to replace high water cut wells by wells located in areas with low water saturation; (6) produced water reinjection; (7) remote well treatment to restore water injectivity, as well as to inhibit or remove inorganic scaling in production wells; and (8) active reservoir management aiming the optimization of well production and injection rates, based on the flow simulator and field responses. The results have been so far very good, with the reduction of production losses and the gradual increasing in the ultimate recovery factor. A good example is provided by the Marlim Field, that already reached an oil recovery of 40%, and the actions planned for the field revitalization indicate an ultimate recovery factor of over 50%.