bluuebunny/crossref_metadata_2025 huggingface dataset:
CREATIVE OR ANALITICAL WAY FOR CAREER DEVELOPMENT? RELATIONSHIP MARKETING IN THE FIELD OF INTERNATIONAL BUSINESS EDUCATION
Authors: Markova Marina , Modliński Artur , Moreira Pinto Luís
Published: January 2020

The article presents a strategic model of the partnership in the field of business education that takes into
account the specificity of the globalization and current trends on the job markets. The main research tasks were to consider the theoretical
bases of relationship marketing and to examine the major trends and challenges of the job market in Russia. The article includes the results
of the research on the goals in life and motivation of secondary school students, the survey among the university professors on their opinions
about why students decide to study, and also the results of the international research among students of European and Russian universities.
The article present various activities that the business school can use to boost the cooperation between its main shareholders. The authors
suggest a matrix of interaction between universities and partner companies which composes of the tangible/intangible resources and tangible/intangible
effects with the characteristics of their impact and effectiveness for both the companies and universities.
AN ENERGY DISSIPATIVE SPATIAL DISCRETIZATION FOR THE REGULARIZED COMPRESSIBLE NAVIER-STOKES-CAHN-HILLIARD SYSTEM OF EQUATIONS
Authors: Balashov Vladislav , Zlotnik Alexander
Published: January 2020

We consider the regularized 3D Navier-Stokes-Cahn-Hilliard equations describing isothermal flows of viscous compressible two-component fluids with interphase effects. We construct for them a new energy dissipative finite-difference discretization in space, i.e., with the non-increasing total energy in time. This property is preserved in the absence of a regularization. In addition, the discretization is well-balanced for equilibrium flows and the potential body force. The sought total density, mixture velocity and concentration of one of the components are defined at nodes of one and the same grid. The results of computer simulation of several 2D test problems are presented. They demonstrate advantages of the constructed discretization including the absence of the so-called parasitic currents.
The Galactic Halo Contribution to the Dispersion Measure of Extragalactic Fast Radio Bursts
Authors: Yamasaki Shotaro , Totani Tomonori
Published: January 2020

A new model of the Milky Way (MW) halo component of the dispersion measure (DM) for extragalactic sources, such as fast radio bursts, is presented in light of recent diffuse X-ray observations. In addition to the spherical component of isothermal gas (kT ∼ 0.3 keV) in hydrostatic equilibrium with the Galactic gravitational potential, our model includes a disk-like nonspherical hot gas component to reproduce the directional dependence of the observed X-ray emission measure (EM). The total gas mass (1.2 × 1011
M
⊙) is dominated by the spherical component, and is consistent with the total baryon mass of the MW expected from the dark matter mass and the cosmic baryon-to-dark-matter ratio. Our model predicts a mean halo DM of

, with a full range of 30–

over the whole sky. The large scatter seen in the X-ray EM data implies a ∼0.2 dex (rms) fluctuation of the MW halo DM. We provide an analytic formula to estimate the MW halo DM of our model along any line of sight, which can be easily used to compute the total MW component of DM toward extragalactic sources, in combination with existing DM models of the warm ionized medium associated with the Galactic disk.
Local Regimes of Turbulence in 3D Magnetic Reconnection
Authors: Lapenta G. , Pucci F. , Goldman M. V. , Newman D. L.
Published: January 2020

The process of magnetic reconnection when studied in nature or when modeled in 3D simulations differs in one key way from the standard 2D paradigmatic cartoon: it is accompanied by many fluctuations in the electromagnetic fields and plasma properties. We developed a diagnostics to study the spectrum of fluctuations in the various regions around a reconnection site. We define the regions in terms of the local value of the flux function that determines the distance from the reconnection site, with positive values in the outflow and negative values in the inflow. We find that fluctuations belong to two very different regimes depending on the local plasma beta (defined as the ratio of plasma and magnetic pressures). The first regime develops in the reconnection outflows where beta is high and it is characterized by a strong link between plasma and electromagnetic fluctuations, leading to momentum and energy exchanges via anomalous viscosity and resistivity. But there is a second, low-beta regime: it develops in the inflow and in the region around the separatrix surfaces, including the reconnection electron diffusion region itself. It is remarkable that this low-beta plasma, where the magnetic pressure dominates, remains laminar even though the electromagnetic fields are turbulent.
Être en couple et/ou être soi. Se séparer pour faire couple
Authors: Dupré La Tour Monique
Published: January 2020

Pour vivre en couple et rester soi, un écart entre les conjoints est nécessaire. La vie actuelle, quand le tiers est peu ou mal intériorisé, permet aux couples de vivre selon des situations sociales différentes – et variables dans le temps. Parmi celles-ci, la non-cohabitation. Un exemple clinique montre les étapes par lesquelles sont passés les conjoints d’un jeune couple au cours de la thérapie, de la vie en groupe à la non-cohabitation. Quand ils se séparent, ce n’est pas pour se séparer, mais pour expérimenter une relation conjugale pouvant les conduire à un couple psychique dans lequel chacun peut se sentir exister. L’article montre comment ces étapes leur ont permis d’approfondir et de transformer leur relation.
De la séparation à la rupture ?
Authors: Marteau-Fassel Karine
Published: January 2020

Lorsque le couple se sépare, les liens se distendent mais ne sont pas immédiatement rompus. En effet, la séparation effective se trouve retardée pour diverses raisons : d’abord parce que l’un des époux – voire les deux – peut ne pas vouloir, au regard de convictions personnelles, envisager de rompre le lien conjugal ; ensuite parce que les époux peuvent se trouver confrontés aux lenteurs d’une procédure de divorce ; enfin – et plus généralement – parce que la séparation passe aussi par le retour à l’autonomie financière et patrimoniale, imposant à chacun de décider du partage des biens acquis pendant la vie commune. S’agissant des enfants communs, le législateur de 2002 a limité les effets de la rupture du couple parental en tenant l’enfant éloigné des conflits et des bouleversements engendrés par la désunion de ses parents, consacrant ainsi la notion de coparentalité, et ce dans l’intérêt des enfants. Au-delà, il s’agit également de garantir à l’enfant le maintien des liens qu’il a pu entretenir jusqu’à présent avec chaque composante de son entourage familial (frères et sœurs, grands-parents).
Des hommes devenant pères
Authors: Jean-Dit-Pannel Romuald , Riand Raphaël
Published: January 2020

La grossesse (psychique) des pères interroge les capacités psychiques de l’homme devenant père à se saisir fantasmatiquement d’un corps (psychique) pour trois. Le père pré-œdipien est potentiellement un co-acteur dans une co-construction à trois. Si la place des pères auprès de leur bébé et auprès de leur conjointe devenant mère reste socialement à légitimer, les groupes de parole de pères peuvent être un cadre d’étayage à la paternalisation. S’appuyant sur leur expérience, les auteurs articulent leur réflexion autour de trois axes principaux développés lors d’un groupe de pères en crèche : l’établissement et la légitimité des premiers liens père-mère-bébé, le désir et le tabou d’un sein paternel nourricier de la triade, l’accouchement du père, d’une (id)entité père-mère-bébé.
Transformer les violences de père en fils
Authors: de Kernier Nathalie
Published: January 2020

Cet article montre comment la non-élaboration du processus d’adolescence peut se faire sentir chez l’adulte, surtout quand il devient parent et que son enfant devient adolescent. À partir des notes prises juste après chaque séance dans un cadre de soins, l’auteur retrace ici la cure-type d’un homme d’une quarantaine d’années, dont l’adolescence du fils réveille des traumas en lien avec sa relation à son propre père violent, jusqu’alors impensés. La cure permet une transformation des traumas et une reprise du conflit œdipien et favorise une évolution qui peut se résumer par un assouplissement de l’imago paternelle allant de pair avec une position de père plus assurée et des liens père-fils plus consistants.
L’assistant familial : un tuteur de résilience « suffisamment bon » ?
Authors: Mayaux François-Xavier , Derivois Daniel , Viodé Christelle
Published: January 2020

Cet article propose d’étudier les tuteurs de résilience des enfants confiés en famille d’accueil à partir de la théorie de l’attachement dans une perspective psychodynamique. Il met en évidence la complexité de la relation entre l’enfant et l’assistant familial en tant que figure d’attachement alternative, tuteur de résilience possible. Cette réflexion s’appuie sur une pratique de psychologue clinicien travaillant au sein de l’Aide sociale à l’enfance. L’articulation théorico-clinique issue de cette expérience discute des effets résilients potentiels qu’ont les assistants familiaux sur le vécu des enfants confiés en famille d’accueil en termes de processus de consolidation de la base de sécurité de l’enfant par la qualité du caregiving du professionnel. Il pose ainsi la question de la complexité de cette dynamique relationnelle interactive et du danger dans le risque d’utilisation excessive de cette notion de tuteur.
Pouvoir et domination dans les politiques de développement : l’exemple de l’Amérique latine
Authors: Berr Éric
Published: January 2020

Comprendre les raisons qui ont conduit les pays d’Amérique latine à se soumettre au « consensus de Washington », puis à tenter de s’en affranchir, nécessite de fournir une analyse approfondie du concept de pouvoir. Ainsi, à partir des travaux de John Kenneth Galbraith, Kenneth Boulding et Steven Lukes, nous proposons une typologie des relations de pouvoir insistant sur la notion de domination. Nous montrons que la volonté de construire une économie néoclassique exempte (en apparence) de rapports de force conduit à des résultats qui masquent mal la volonté de dominer des prescripteurs de ces politiques économiques. Classification JEL : E10, N16, 011
Économie politique de la dollarisation
Authors: Ponsot Jean-François
Published: January 2020

L’article analyse la dollarisation dans une perspective d’économie politique. Il dresse une typologie des régimes de dollarisation en s’appuyant sur la grille de lecture institutionnaliste de la monnaie. Les ressorts des contestations monétaires à l’œuvre derrière la perte de légitimité de l’unité de compte domestique et l’érosion de la souveraineté monétaire sont mis en évidence. L’étude de la dollarisation officielle et intégrale en Équateur montre qu’elle a consolidé l’ancrage des anticipations à travers un compromis monétaire source de stabilité institutionnelle. Mais elle a aussi accentué la charge de l’ajustement et entravé la mise en œuvre d’une ambitieuse stratégie de développement alternative au consensus de Washington, empêchant ainsi la sortie d’un régime de croissance tiré par les exportations et l’extractivisme. Classification JEL : E42, 023, P16
La crise argentine actuelle. Une perspective historique
Authors: Calcagno Alfredo
Published: January 2020

Cet article place la crise qui commence en 2018 dans une perspective historique longue de l’Argentine. Il retrace les cinq étapes clés de son processus de développement, et identifie leurs principales caractéristiques et leurs enjeux. Il met ainsi en évidence la responsabilité de l’agenda néolibéral dans la destruction des régimes de croissance qui avaient par le passé, et récemment encore, permis au pays d’avancer sur le chemin du développement. Au-delà de la délicate gestion de la crise en cours, il en tire une série de leçons et de recommandations essentielles pour la restauration d’un régime de croissance viable. Classification JEL : N16, O11, B52
L’appropriation des coopératives d’épargne et de crédit (COOPEC) par leurs membres. Échelle de mesure et déterminants
Authors: Murhula Cubaka Patrick , Balemba Kanyurhi Eddy , Bugandwa MunguAkonkwa Déogratias , Labie Marc
Published: January 2020

L’appropriation psychologique a fait l’objet de quelques études empiriques consacrées uniquement aux employés de plusieurs organisations. Cet article développe une échelle de mesure de l’appropriation des coopératives par leurs membres ainsi que les variables qui sont susceptibles de l’influencer. Les résultats révèlent que l’appropriation psychologique est un construit multidimensionnel composé de sept facteurs. Ils montrent que l’ancienneté et le niveau d’étude l’influencent positivement. Classification JEL : C81, E21, G21, O16
Les signatures spatiales de la criminalité dans les villes du Sud. L’exemple de la ville de Yaoundé
Authors: Bourdin Sébastien , Bertrand Chancelier Wandji
Published: January 2020

Yaoundé, comme la plupart des villes du Sud, est particulièrement touchée par la criminalité. Celle-ci est un véritable fléau pour les autorités locales qui cherchent aujourd’hui à endiguer ce phénomène. Les études en géocriminalité montrent que celle-ci n’est pas localisée au hasard dans l’espace urbain. Elle répond à des logiques territoriales et se concentre bien souvent dans les quartiers les plus en difficulté. À partir de données sociodémographiques et urbanistiques d’une part, et de données sur la criminalité d’autre part, nous tentons de dresser une géographie de la criminalité dans la capitale camerounaise. Nos résultats montrent que les signatures spatiales des faits criminels nécessitent une réponse territorialisée de la part des forces de police et des pouvoirs publics. Classification JEL : C31, C33, O40, R11
Des « boys » aux « travailleurs de maison » au Burundi, ou le politique domestiqué
Authors: Deslaurier Christine
Published: January 2020

Les «  boys  » ( ababoyi ) sont omniprésents dans les foyers urbains du Burundi depuis le début du xx e siècle. Pourtant, la recherche s’intéresse peu à cette catégorie de travailleurs auxquels incombent de multiples tâches ménagères, ailleurs plutôt confiées aux femmes. En proposant une sociohistoire de ces hommes engagés de longue date dans la domesticité, cet article entend les (ré)inscrire dans le champ de l’action et des mobilisations politiques, en montrant qu’ils sont impliqués dans des dispositifs économiques, des relations personnelles et des engagements collectifs qui en font plus que des subordonnés atones. Par-delà les relations de dépendance qui les brident, ils négocient leur émancipation au travers de formes variées d’initiatives.
« Blanchir » la domesticité. La reproduction des hiérarchies de race, de classe et de sexe dans la production d’un personnel de luxe en Afrique du Sud
Authors: Delpierre Alizée
Published: January 2020

Les Butler Academies forment à travers le monde du personnel de maison dédié aux classes supérieures très fortunées. En Afrique du Sud, où près d’un·e active et actif sur dix travaille dans la domesticité, l’ouverture d’une academy est présentée comme une opportunité pour revaloriser ce secteur. Ouverte aux Noir·e·s et aux Blanc·he·s de différents milieux socio-économiques, son projet semble bouleverser le sens des rapports de domination de race, de classe et de sexe à l’œuvre dans la domesticité. L’article montre cependant qu’en promouvant un modèle de butler homme blanc, la formation est un dispositif de reproduction des rapports de domination néocoloniaux.
Essai de mesure et d’analyse de la présence de domestiques dans les ménages en Afrique subsaharienne
Authors: Pilon Marc , Delaunay Valérie , Marcoux Richard , Coulibaly Aminata , Dieme Binta
Published: January 2020

Alors que le travail domestique en Afrique, assuré par des personnes extérieures à la famille, fait l’objet d’un intérêt croissant, la mesure de son ampleur et l’analyse de ses caractéristiques se heurtent à un manque de données adéquates. L’article propose un inventaire critique des sources de données permettant de saisir les situations de domesticité. À partir des données disponibles, il synthétise et compare entre pays les niveaux de prévalence du phénomène, mais en se limitant aux seul·e·s domestiques hébergé·e·s par leur ménage employeur, avec une analyse comparative plus approfondie entre Bamako et Dakar.
Quand le consensus se fissure. Processus révolutionnaire et spatialisation du soulèvement soudanais
Authors: Deshayes Clément , Vezzadini Elena
Published: January 2020

L’épisode révolutionnaire soudanais qui débute mi-décembre 2018 dans des villes de province culmine en avril 2019 avec la destitution d’Omar al-Bashir et l’occupation de la place al-Qiyada. Cet épisode marque la fin de la première phase de ce soulèvement populaire. Au-delà de l’aspect événementiel, cet article plaide pour inscrire dans le temps long cette révolte d’une ampleur inégalée dans l’histoire sociale et politique du Soudan. Ce texte entend la décrypter au travers de trois axes d’analyse. Tout d’abord, la révolution soudanaise est à lire au prisme de l’érosion du consensus populaire et idéologique que le régime a cherché à bâtir depuis 1989. Ensuite, cet article replace la période actuelle au sein d’un processus antérieur de massification et de diffusion de contestations protéiformes et multidimensionnelles. Enfin, ce soulèvement dans un espace autoritaire peut être appréhendé au travers de sa spatialisation et d’une géographie des inégalités sociales qui mettent à jour les ressorts d’une révolte dans laquelle des mécanismes de classe autant que de génération sont en jeu.
Informality, Regulation and Predation : Governing Déby’s Chad
Authors: Iocchi Alessio
Published: January 2020

Au Tchad, les recettes générées par les pratiques fiscales informelles sont au cœur des finances publiques. Elles constituent une rente allouée aux alliés et à la clientèle politique des dirigeants au pouvoir. Ce phénomène s’est accéléré au milieu des années 2010 à la faveur de la baisse des cours internationaux du pétrole, mais aussi de la crise suscitée par l’essor de Boko Haram. À partir d’une enquête micro-économique de terrain, l’article interroge la manière dont ces évolutions de grande envergure ont amené le régime tchadien à réviser ses pratiques fiscales et à réorganiser ses réseaux d’échanges, tout en renforçant sa place centrale dans l’économie nationale. Au-delà du cas du Tchad, il s’agit aussi d’ouvrir des perspectives sur les dynamiques internes des États africains postcoloniaux.
Does manufacturers' size affect the prevalence of mycobiota and occurrence of mycotoxins in spices and spice-based products?
Authors: Ahmad-Zaidi A.I. , Ghazali M.A.A. , Nik-Muhammad N.A. , Sazali N.S. , Mahror N. , Yazid S.N.E. , Jinap S. , Samsudin N.I.P.
Published: January 2020

The present work aimed to establish the prevalence of mycobiota and occurrence of mycotoxins (aflatoxins and ochratoxin A) in spices and spice-based products, and correlate these to their manufacturers’ sizes. A total of 90 spice, sauce and paste samples were purchased; 3 manufacturer sizes (small, medium, large) × 3 types of samples (spices, sauces, pastes) × 5 brands × 2 replicates. The prevalence of mycobiota was assessed with dichloran rose bengal chloramphenicol (DRBC) andAspergillus flavus andAspergillus parasiticus (AFPA) medium, while the occurrence of mycotoxins was quantified with HPLC-FLD. Large-scale manufacturers were found to adopt a greater number of safety and quality certifications. Small-scale manufacturers significantly yielded the highest total fungal loads on DRBC (log 5.084±0.417 cfu/g paste, log 6.253±0.407 cfu/g sauce, log 6.662±0.222 cfu/g spice) and AFPA (log 4.461±0.451 cfu/g paste, log 5.661±0.395 cfu/g sauce, and log 6.269±0.432 cfu/g spice). Correlation analysis (Pearson’sr) revealed that manufacturers’ sizes positively influenced (DRBCr=0.781; AFPAr=0.702) the prevalence of mycobiota. Aflatoxin B1 was present in 6/30 (20%) paste samples, 1/30 sauce samples (3.33%) and 12/30 spice samples (40%). Aflatoxin B2 was only present in 2/30 sauce samples (6.67%). Aflatoxin G1 and G2 were absent from all samples. Ochratoxin A was present in 11/30 (36.67%) paste samples, 5/30 sauce samples (16.67%) and 21/30 spice samples (70%). It was found that, to a certain extent, the size of and certification adopted by manufacturers affected the prevalence of mycobiota and the occurrence of mycotoxins in spices and spice-based products analysed in the present work. Nevertheless, it is henceforth recommended that a surveillance study of this nature be extended and widened in terms of number of samples as well as type of spices, sauces and pastes to obtain a more thorough and significant profile of the products’ food safety and quality level.
Impact of the biofungicide tetramycin on the development ofFusarium head blight, grain yield and deoxynivalenol accumulation in wheat
Authors: Shi W.Q. , Xiang L.B. , Yu D.Z. , Gong S.J. , Yang L.J.
Published: January 2020

Fusarium graminearum causesFusarium head blight (FHB), a devastating disease that leads to extensive yield and quality loss in wheat and barley production. Integrated pest management (IPM) is required to control this disease and biofungicides, such as tetramycin, could be a novel addition to IPM strategies. The current study investigatedin vitro tetramycin toxicity inFusarium graminearum and evaluated its effectiveness for the control ofFusarium head blight FHB. Tetramycin was shown to affect three key aspects ofFusarium pathogenicity: spore germination, mycelium growth and deoxynivalenol (DON) production. Thein vitro results indicated that tetramycin had strong inhibitory activity on the mycelial growth and spore germination. Field trials indicated that tetramycin treatment resulted in a significant reduction in both the FHB disease index and the level of DON accumulation. The reduced DON content in harvested grain was correlated with the amount ofTri5 mRNA determined by qRT-PCR. Synergistic effects between tetramycin and metconazole, in both thein vitro and field experiments were found. Tetramycin could provide an alternative option to control FHB.
Maculopathy in Pierre Robin Sequences
Authors: Kaarniranta Kai , Tuppurainen Kaija , Nikolajev Kari
Published: January 2020

Maculopathy in Pierre Robin Sequences

To the Editors:
Pierre Robin sequence (PRS) is a congenital anomaly defined as micrognathia, glossoptosis, and cleft soft palate. The heterogeneous pathogenetic and phenotypic variations of PRS have prompted the term “Robin sequences.” An estimated 80% of all Pierre Robin cases form as part of a syndrome.1 PRS is most commonly associated with Stickler’s syndrome, cerebrocostomandibular syndrome, and trisomy 18.2,3 Secondary to abnormal gnathia and posterior displacement of the tongue, PRS results in feeding difficulty and respiratory obstruction that varies from mild to severe.4 The prevalence of PRS is documented at 1 per 8,500; the mortality rate ranges from 2.2% to 26%, following obstructive apnea and failure to thrive.4 Ocular manifestations include myopia, strabismus, glaucoma, microphthalmos, cataract, retinal detachment, and nasolacrimal duct obstruction.5,6 [more...]
Evidence Against Mobile Pulleys on the Rectus Muscles and Inferior Oblique Muscle: Central Nervous System Controls Ocular Kinematics
Authors: Jampel Robert S. , Demer Joseph L.
Published: January 2020

Evidence Against Mobile Pulleys on the Rectus Muscles and Inferior Oblique Muscle: Central Nervous System Controls Ocular Kinematics

To the Editors:
This letter is a reply to Joseph L. Demer’s defense of his active pulley hypothesis (APH). Demer believes that independently functioning pulleys in the orbit determine the locations of the rotational axes of the extraocular muscles. He states that my statement that eye movements are commutative is a fundamental error and mathematically absurd.1 He writes: “. . . it is a fundamental mathematical truism that rotations of any sort or object are always noncommutative: the sequence of rotations has an important influence on the final orientation achieved, and there is simply no way around this unless the rotational axes themselves interact mutually.” The validity of the APH rests with this statement. This letter presents evidence that eye movements are in fact commutative (ie, the sequence of rotations has no effect on the final orientation of the eye) and that there is no mechanism in the orbit independent of neural control.1-7 [more...]
Assessment of Renewable Energy Technologies in a Standalone Microgrid System
Authors: Adefarati Temitope , Obikoya G.D.
Published: January 2020

The rapid growth of the global economy has led to a high demand of electric energy and utilization of fossil fuels to meet the power demand. This has motivated the utilities or independent power providers to incorporate renewable energy resources (RERs) into their power systems. Moreover, with the increasing concerns of environmental protection and fossil fuel depletion, RERS are universally accepted as the potential alternative to fossil fuels. Consequently, this work aims at exploring the application of the photovoltaic (PV), electric storage system (ESS) and wind turbine generator (WTG) in a microgrid (MG) system to reduce the total annual cost (TAC) and environmental impact reduction index (EIR) while maintaining the power system constraints and load requirements. The problem is formulated by using the fmincon optimization solver in the MATLAB environment to assess the environmental and economic effects of utilizing RERs in a MG system. The values of TAC and EIR obtained in the study are compared with the base case study where a reciprocating engine is only utilized to meet the same power demand without using RERs and ESS. The results obtained from the study indicate that a WTG/PV/ ESS/ diesel generator MG system has achieved good results. The outcomes of the study demonstrate that utilization of green technologies is suitable for achieving global sustainable energy development.
Well Placement Technique and Production Optimization for Mature Field - A Case Study of L-X Field
Authors: Nwafor Patrick , Bello Kelani
Published: January 2020

A Well placement is a well-known technique in the oil and gas industry for production optimization and are generally classified into local and global methods. The use of simulation software often deployed under the direct optimization technique called global method. The production optimization of L-X field which is at primary recovery stage having five producing wells was the focus of this work. The attempt was to optimize L-X field using a well placement technique.The local methods are generally very efficient and require only a few forward simulations but can get stuck in a local optimal solution. The global methods avoid this problem but require many forward simulations. With the availability of simulator software, such problem can be reduced thus using the direct optimization method. After optimization an increase in recovery factor of over 20% was achieved. The results provided an improvement when compared with other existing methods from the literatures.
Stochastic and Deterministic Petri Networks Model for Joint Management Model for Spare Parts and Maintenance: Simulation Study
Authors: Bounou Oumaima , El Barkany Abdellah , El Biyaali Ahmed
Published: January 2020

Maintenance management is an orderly procedure to address the planning, organization, monitoring and evaluation of maintenance activities and associated costs. The maintenance management allows to have an efficient tool either to the management of the preventive or curative activity, an optimization of the production tool, and finally a follow-up of the costs and the performances. A good maintenance management system can help prevent problems and damages to the operating and storage environment, extend the life of assets, and reduce operating costs.In this paper, we will first present our model on the joint management of spare parts and maintenance. We will do a simulation study of our model, presented in the first section of this paper. The results of this study are presented in the second section through the presentation of the influence of certain parameters of the model on the operation of the system under consideration. This study carried out on the graphical interface of Matlab, which is one of the performance evaluation techniques. It allows to visualize the variations and anomalies which can be reached in the system considered as an overcoming of the repair of the machines by the unforeseen breakdowns.
A Study of Airline Fuel Planning Optimization Using R-Ga
Authors: Okafor Ekene Gabriel , Uhuegho Osaretin Kole , Manshop Christopher , Jemitola Paul Olugbeji , Ubadike Osichinaka Chiedu
Published: January 2020

In this study, airline planning optimization problem based on ferry strategy was considered. Cost was the study objective function subject to forty equality and inequality constraints. Regression analysis as well a genetic algorithm (GA) was used to solve the problem. The mathematical relationship between flight fuel consumption and flight time was established using regression analysis, while GA was used for the optimization. The established mathematical model was used to predict the fuel consumption for the twenty scheduled flight consider based on their respective flight time. The result was found to be satisfactory, as optimal fuel lift plan was achieved in approximately twenty seconds of program run time, as against the large time usually spend using human effort to solve the fuel planning problem. The optimized fuel lift plan was compared with the actual fuel lift plan executed by the airline for the twenty scheduled flight considered. The result revealed thirty percent savings using the optimized plan in comparison to the actual fuel lift plan executed by the airline.
Formation and Corrosion Behavior of Nickel/Alumina Nanocomposites
Authors: Tishkevich D.I. , Vorobjova A.I. , Vinnik Denis
Published: January 2020

Ni nanopillars (Ni NPs) composite materials formation technology was presented. The morphological and structural properties of the composite material were investigated using scanning electron microscopy, atomic force microscopy, X-ray diffraction. The corrosion resistance of the nanocomposite materials has been studied by potentiodynamic polarization curves analysis. The composite represents the array of vertically ordered Ni NPs with the identical size in alumina matrix. XRD investigation indicates that Ni NPs are polynanocrystalline material. It has been shown that Ni NPs and the composite material have sufficient corrosion resistance in a 0.9% aqueous NaCl solution. Porous alumina matrix is the neutral and protective component of the composite. These nanocomposite materials can be excellent candidates for practical use in different applications.
Atomic Layer Deposition of Lithium-Silicon-Tin Oxide Nanofilms for High Performance Thin Film Batteries Anodes
Authors: Nazarov Denis , Mitrofanov Ilya , Maximov Maxim Yu.
Published: January 2020

Tin oxide is the most promising material for thin film anodes of Li-ion batteries due to its cycling performance and high theoretical capacity. It is assumed that lithium-tin oxide can demonstrate even higher performance. Lithium-silicon-tin oxide nanofilms were prepared by atomic layer deposition (ALD), using the lithium bis (trimethylsilyl) amide (LiHMDS), tetraethyltin (TET) as a metal containing reagents and ozone or water or oxygen plasma as counter-reactants. Monocrystalline silicon (100) and stainless steel (316SS) were used as supports. The thicknesses of the nanofilms were measured by spectral ellipsometry (SE) and scanning electron microscopy (SEM). It was found that oxygen plasma is the most optimal ALD counter-reactant. The composition and structure were studied by Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS) and X-ray diffraction (XRD). The nanofilms contain silicon as impurity, whose source is the ALD precursor (LiHMDS). The nanofilms deposited on stainless steel have shown the high Coulombic efficiency (99.1-99.8%) and cycling performance at a relatively high voltage (0.01 to 2.0V).
Processing of Used Wooden Slippers by Thermal Method
Authors: Tuntsev Denis V. , Safin Rushan G. , Khayrullina Milausha
Published: January 2020

The paper provides an overview of the methods of utilization and processing of used wooden sleepers. The advantages and disadvantages of these methods are revealed. A mathematical description of the process of processing used sleepers by the method of fast pyrolysis is presented. We presented the results of theoretical and experimental studies of the volume of yield of thermal decomposition products in dependence on the process temperature, the hold-up time of the steam-gas mixture in the reaction zone, and the used wooden sleepers’ particle size.
Pressure Leaching of Chalcopyrite Concentrate: Ultra-Fine Milling as Process Acceleration Method
Authors: Kritskii Aleksei , Karimov Kirill , Naboichenko Stanislav
Published: January 2020

Ural enrichment plants processing copper-porphyry deposits are produced chalcopyrite concentrates of the following chemical composition, %: 21.5 Cu, 0.1 Zn, 26.59 S, 24.52 Fe, 0.05 Pb, 0.04 Ni, 16.28 SiO2 [1]. According to previous studies [2, 3, 21], such concentrates can be effectively treated using pressure oxidative leaching (POX). At temperature of 190–200 °C, partial oxygen pressure 4–6 bar and [H2SO4] = 15–30 g / L during 100-120 min about 98 % Cu was extracted. In this paper, an inluence of chalcopyrite concentrate preliminary grinding on efficiency of the POX stage was studied. It was found that even the finest grinding of the particle size class P80 = 13 μm does not lead to significant intensification of process kinetics.
The Influence of Fiber Reinforcement on the Properties of the Self-Compacting Concrete Mix and Concrete
Authors: Goncharova Margarita A. , Krokhotin Vladimir V. , Ivashkin Alexander N.
Published: January 2020

The paper considers the influence of fiberglass on the rheological and stress-strain properties of self-compacting concretes. The use of fiberglass in self-compacting concrete compositions makes it possible to achieve a sufficient coefficient of grain separation in coarse and fine fillers, which significantly influences the mobility and technological effectiveness of self-compacting mixes. Optimum compositions of self-compacting concretes are obtained, rational volumes of the hyper-plasticizing additive and of fiberglass are determined. The components were selected experimentally, in order to optimize the composition according to rheological characteristics. It is established that the use of fiberglass positively influences the stress-strain characteristics of concrete: it raises the compressive strength, as well as the bending tensile strength without deteriorating the workability and spreadabilityof the self-compacting concrete mix.
Sodium Lignosulfonate and Sodium Dodecyl-Sulfate Mixtures Influence on Zinc Concentrate Pressure Leaching and Zinc Electro-Winning
Authors: Kolmachikhina Elvira B. , Ryzhkova E.A. , Dmitrieva D.V.
Published: January 2020

This paper is describing an investigation of sodium lingo-sulfonate and sodium dodecyl-sulfate mixtures influence on zinc concentrates high temperature oxidative pressure leaching and zinc electro-winning. For this purpose, surfactants concentration at leaching tests was varied from 200 to 800 mg∙l-1. It was established that the maximum zinc extraction (99 %) at leaching was achieved in the presence of mixture containing 800 mg∙l-1 lignosulfonate and 200 mg∙l-1 sodium dodecyl-sulfate. Therefore, this mixture can be recommended for high temperature oxidative pressure leaching of zinc concentrates. Sulfur-sulfide pellets formation also was observed at a low lingo-sulfonate concentration (200 mg∙l-1) in a mixture with sodium dodecyl-sulfate. This phenomenon can lead to emergency shut down of autoclave. It was observed that the mixture usage of 800 mg∙l-1 lignosulfonate and 200 mg∙l-1 sodium dodecyl-sulfate had no significant impact on zinc current efficiency, it was in the rage of 92-93 %. The mixture usage of 200 mg∙l-1 lignosulfonate and 600 mg∙l-1 sodium dodecyl-sulfate allowed to increase current efficiency up to 95 %. Increasing sodium dodecyl-sulfate concentration in mixtures with lignosulfonates leads to decrease of current efficiency, to formation of deep pores and defects on cathode zinc surface.
Zinc Techno-Genic Formations: Physico-Chemical Features of its Extraction
Authors: Sheshukov O.Yu. , Mikheenkov M.A. , Lobanov D.A.
Published: January 2020

In technogenic formations, zinc is found in oxide and sulphide forms. Extraction of zinc oxide from technogenic formations is widely used in industry. Removing zinc sulfide from technogenic formations is difficult and is currently almost never used. In the present work, the physicochemical features of zinc extraction from technogenic formations, in which zinc is presented in oxide and sulphide forms, are considered. Thermodynamic features of the processes and possible ways to extract zinc sulphide are shown. This work also considers the ways of valuable commercial products obtaining from the roasting products.
Comparison of Iron and Chromium Reduction from Chrome Ore Concentrates by Solid Carbon and Carbon Monoxide
Authors: Mukashev N.Zh. , Kosdauletov N.Y. , Suleimen B.T.
Published: January 2020

The possibility of reduction of chromium and iron from complex oxides by gaseous carbon monoxide and solid carbon was investigated. The chromium ore concentrates of Kempirsai and Aganozero deposits used in present study had different ratio of iron and chromium content. The Reduction in CO gas atmosphere did not result in reduction of chromium and iron from spinels; however, it resulted in reduction of fines from the drying apparatus, where the particles of coke presented along with the particles of the Kempersai chromite. At the same time, iron and nickel were reduced from the silicates of the gangue minerals. In the samples mixed with solid carbon a continuous layer of carbides formed on the surface of the spinel grains. The formation of a continuous shell retarded and practically stopped the reduction process. The further development of reduction was possible after destruction of the shell that occurred as a result of smelting of the carbides and silicides mixture that constitute the shell.
Quality Control of Building Materials According to Uncertainty of Measurement and Stability of the Technological Process of Production
Authors: Loganina Valentina , Skachkov Yuri Petrovich , Lesovik Valery
Published: January 2020

Information on the influence of the state of the production process of production and the uncertainty of the measurement on the decision on the product's suitability is given. It is shown on the example of brick production that the decision to accept a batch of bricks, taking into account the measurement uncertainty under unstable condition of the production process, may be erroneous. Three variants of the state of the production process for the production of 100-grade brick are considered. The first option - the average value of compressive strength does not coincide with the middle of the tolerance field, the production process is characterized as unstable, the second option - the average value of compressive strength does not coincide with the middle of the tolerance field, a greater value of the spread of the indicators compared with the first version and is characterized as an unstable process, the third option is the average value of the tensile strength, and compression coincides with the middle of the tolerance field, is characterized as a stable and reproducible process. It is established, that, if the production process is in a state of statistical controllability, i.e. stable, then taking into account the uncertainty of measurement, the brick grade remains 100. In an unstable process with an increase in the value of the standard uncertainty of type A, the controller's decision to identify the brand of brick 100 may be erroneous. Statistically stable and reproducible process makes it possible to increase the reliability of product quality control and to avoid mistakes in deciding on the rejection of products.
Device for Testing Pipe Billet
Authors: Aung Phyo Wai , Maryin S.B.
Published: January 2020

Experimental studies of the influence of the heating temperature on the properties of pipe billets made of titanium alloys OT4 and OT4-1 in the formation of parts for the installation of pipeline systems without a protective atmosphere are presented.
Indentation Size Effect during Measuring the Hardness of Materials by Spherical Indenter
Authors: Udalov Andrey A. , Udalov Aleksander V. , Parshin Sergey V.
Published: January 2020

The work balance method was used to study the effect of the indenter diameter on the indentation size effect when measuring Brinell hardness. It is shown that the main criterion for the indentation size effect is the specific work of plastic deformation when an indenter is introduced. The conditions of indentation are established to ensure the smallest deviation of the actual hardness value from the true one. The results of the study can be used in determining the mechanical characteristics of materials and in the practice of metal forming processes.
Study оf the Diffusion Interaction between Titanium and Aluminum in the Composition AMg6-AD1-VT1-0 after Rolling with Different Compression
Authors: Gurulev Dmitrii N. , Palatkina Lyubov' V.
Published: January 2020

The three-layer composite AMg6–AD1–VT1-0, obtained by explosion welding, is widely used as transition elements in the creation of critical structures made of titanium and aluminum alloys. In welded joints of dissimilar metals, which are limited soluble in each other and form intermetallic compounds, mutual diffusion can occur at elevated temperatures, and when the concentration corresponding to the limit of solubility at a given temperature is reached, conditions are created for the nucleation and growth of intermetallic phases. When studying the effect of heat treatment on the properties of welded joints of such metals, it is necessary to take into account the structure, properties and features of the formation of intermetallic phases, as well as the factors that contribute to their appearance and intensive growth. The latter include hardening, obtained by the composite material after blasting and further technological operations, associated with pressure treatment, which accelerate the diffusion processes, due to fragmentation and development of the block structure.
Investigation of Magnetic Properties of Various Structural Classes Steels in Weak Magnetic Fields Characteristic for Generation of Thermoelectric Currents in Electron Beam Welding
Authors: Kharitonov I.A. , Rodyakina R.V. , Goncharov A.L.
Published: January 2020

The results of studies of magnetic and thermoelectric properties of pearlite, martensitic and austenitic steels, as well as cobalt and nickel based alloys are presented. The magnetization curves for materials from among the studied ones, as well as dependences of absolute thermoelectric power on the material temperature, are obtained. It was found that for ferromagnetic substances in weak magnetic fields the dependence of magnetic induction on the magnetic field strength is non-linear. This allows to conclude that magnetic permeability of such medium is not a constant, but can be described, for example, by a third-order polynomial.
Investigation of Composition and Technological Parameters of Highly Porous Gypsum Products Obtaining
Authors: Ilina Lilia V. , Zavadskaya Lubov V. , Ilina Anastasia I.
Published: January 2020

A highly porous structure of a gypsum product creation is possible due to the porisation of gypsum mass, using new types of complex gas-forming components. At the same time, it is necessary to determine the technological conditions for the optimal formation of porous gypsum products structure and methods for increasing their strength. The article proposed to use dispersed calcium carbonate and aluminum sulphate, which interaction is the reaction with the release of СО2 for the porisation of the gypsum cast mixture. Micro-reinforcing additives, such as polymeric, basalt and glass fibers were introduced into gypsum composition together with building gypsum and finely ground calcium carbonate to improve the physico-mechanical properties of gas-gypsum. The best results were shown by the gas-gypsum, which included fiberglass. Glass fiber was pre-ground to a specific surface of 190-240 m2 / kg, in order to improve further the physico-mechanical properties of gas-gypsum.
A Study of the Influence of Thickness of Anti-Diffusion Layer on the Structure and Thermal Resistance of Composite А5-Cr-St3
Authors: Kuz'min Vladimir I. , Lysak Vladimir I. , Kuz’min Evgeniy V.
Published: January 2020

The paper presents the results of research on the creation of heat-resistant composite A5-Cr-St3 with diffusion barrier. It considers the influence of the thickness of the chromium layer and the kinematic parameters of the structure and thermal steel-aluminum composite.
Composite Materials Based on Plasma Treated Basalt Fibers for Heavy-Duty Concrete Products
Authors: Amerkhanova Gulnara I. , Khatsrinov Aleksey I. , Zenitova Lyubov A.
Published: January 2020

The paper investigates the effect of plasma treatment of basalt fiber on its wettability, which is determined by the ability to absorb water. As the treatment time increases the wettability becomes higher, up to 10 minutes. The wettability-treatment power dependence passes through a maximum. The highest value is observed at a treatment power of 0.6 kW both on the day of treatment and after a 5-day rest period. A further growth in power not only does not increase this value, but in fact decreases it. The retreatment after a 5-day curing period yields lower results, but remains sufficiently high. The highest wettability is observed at a treatment power of 0.6 kW, gas flow rate of 0.04 g/s, chamber pressure of 20 Pa, air/argon mixture (1:1) as plasma support gas. The strength of concrete specimens BST V40 P2 was tested with two treatment modes: in mode 1 the treatment time was 10 minutes, the treatment power was 1.5 kW; and in mode 2 the treatment time was 5 minutes, the treatment power was 0.6 kW, with the addition of plasma treated basalt fiber (0.5 and 3 mass percent). Concrete has the highest strength when basalt fiber (3 mass percent) is subjected to plasma treatment in mode 2. In addition, the strength increases by 18 mass percent in comparison with the reference.
Activating Effect of Aluminum Chloride in the Technology of Poly-Sulfides and Materials Based on them
Authors: Yusupova Alsu , Khatsrinov Aleksey I. , Shafigullin Lenar N.
Published: January 2020

The paper investigates the influence of an electrophilic agent in the inorganic polysulfide technology. A tight contact between the modified silicate filler and sulfur (when heated and then pressed) results in the appearance of new interatomic bonds and interphase interaction forces to ensure the best possible structure formation in a system in the micro and macro level. Cross-linking of silica gel by disulfide fragments shows greater stability. The activation energies were calculated for insertion of diatomic sulfur (singlet and triplet) by an oxygen atom and a silicon atom, with the substitution of OH-group, as well as for addition of diatomic sulfur to the surface of silica gel modified with aluminum chloride. Aluminum chloride acts as an activator for both a silica-containing material and sulfur, and encourages the chemical interaction between the components, and formation of polysulfides and sulfur materials from them, which have high physical mechanical properties.