bluuebunny/crossref_metadata_2025 huggingface dataset:
Edad del material vegetativo y su efecto en el enraizamiento de brotes de café (Coffea arabica) variedad caturra
Authors: Vásquez Inuma Lady Liliana , Ayala Montejo Diana , Vallejos Torres Geomar , Arévalo López Luis Alberto , Bustamante Ochoa Carlos , Calixto Vásquez Eleodoro , Ramos Vásquez Elena
Published: February 2019

La presente investigación se realizó en las instalaciones del invernadero de Biotecnología Clonal de Café del Instituto de Investigaciones de la Amazonía Peruana, sede San Martín-Perú. Tuvo como objetivo determinar la edad apropiada de cosecha de los brotes de café (Coffea arabica L.) para su óptimo enraizamiento bajo condiciones controladas. Se probaron brotes de café con rangos de edades entre55 - 64 y 65 - 74 días. Los brotes fueron sometidos a una desinfección previa y expuestos a una dosisde hormona ácido indol-3- butírico (AIB) de 1 000 ppm, luego se colocaron en pellets de jiffy y finalmente se introdujeron en microtuneles con condiciones controladas para fomentar el enraizamiento. Para el análisis se utilizó un diseño experimental factorial completamente al azar, cuyos factores corresponden a edad de los brotes, tratamiento hormonal (AIB) y 6 repeticiones, con 24 unidades experimentales en total, estando estas últimas comprendidas por 6 brotes de cafeto, haciendo un total de 144 brotes. Después de seis semanas de instalado el ensayo se evaluaron los brotes, para las variables: número de raíz, longitud de raíz, porcentaje de enraizamiento y mortalidad. Los datos fueron sistematizados y sometidos a un análisis de varianza y una prueba de Tukey. Llegando a la conclusión que la edad recomendable de los brotes de café para obtener plantas con óptimo enraizamiento está en el rango de 65 a 74 días.
Holistic Biodiversity Conservation in the Anthropocene: A Southern African Perspective
Authors: Lubbe W. D. , Kotzé Louis J.
Published: February 2019

In the Anthropocene the loss of biodiversity is set to become increasingly critical. Our law and governance institutions have been unable to halt this worrying trend. One of the reasons for this regulatory deficiency is that global law and governance pertaining to biodiversity are fragmented. In response to the need for a greater integration of law and governance directed at the protection of an integrated biosphere and as a measure to counter fragmentation, we argue that global biodiversity law and governance should be based on the connectivity conservation approach. While the debate about connectivity could occur in various geographical contexts, we focus for our present purposes on regional biodiversity governance in Southern Africa. It is our central hypothesis that adopting a holistic approach to biodiversity conservation in this region might go a long way towards preventing the human encroachment on biodiversity that typifies the Anthropocene.
The Right to Property and Compulsory Land Acquisition in Ghana: A Human Rights Perspective
Authors: Nyarko Michael Gyan
Published: February 2019

Using a human rights-based approach and Ghana as a case study, this article examines the scope and content of the right to property in relation to compulsory land acquisition under international law. It argues that while the exact frontiers of the right to property remain quite uncharted at the global level the vacuum has been filled by the regional human rights systems and soft law. In the context of Ghana, the Constitutional protection of the right to property and quite elaborate rules to be followed during compulsory acquisition have not translated into revision of the compulsory acquisition laws, which remain largely incoherent and inconsistent with the requirements of the Constitution and international human rights law.
The Enforceability of Health Rights in Kenya: An African Constitutional Evaluation
Authors: Roux-Kemp Andra Le
Published: February 2019

Kenya's recently promulgated 2010 Constitution has been met with much enthusiasm and expectation after a difficult and protracted history of constitutional development and reform. This article considers and evaluates the key constitutional provisions with regard to the recognition of health rights in Kenya together with other health-related provisions, and with specific reference to the realisation and enforceability thereof. This evaluation will be conducted from a comparative perspective with references made to other African constitutions and case law. It is the objective of this article to offer a critical evaluation of the health rights included in the Kenyan Bill of Rights in relation to its African counterparts and to consider the possibilities and potential obstacles for the realisation and enforcement thereof. It is evident from this comparative evaluation that the Kenyan Bill of Rights contains pioneering provisions with regard to the right to health that can bring about meaningful changes for Kenyan citizens through effective socio-economic rights jurisprudence.
METHODOLOGICAL ASPECTS OF EVALUATION OF STATE BUDGE! PROGRAMMES
Authors: Bivainis Juozas , Butkevičius Algirdas
Published: February 2019

The paper deals with the reasonability of allocation of public financial resources. It presents an integrated evaluation model applicable to budget programmes and capable of deepening the comprehensiveness as well as the objectivity of programme evaluation aimed at benchmarking. The nucleus of the model consists of four components: evaluation of relevance, evaluation of efficiency, evaluation of fitness, and the synthesis of the said evaluations. The contents and main methodological aspects of each component are described.
MODELLING OF NET FLOWS TO INVESTMENT FUNDS
Authors: Simanauskas Leonas , Rutkauskas Aleksandras Vytautas , Kucko Irena
Published: February 2019

The paper presents the general model of net flows to investment funds, which helps to analyse the flows and to solve the problem structurally. The model includes various investment guidelines and different fund types, aspects of risk influence are discussed separately. Furthermore, the conception and techniques of integrated assets and liabilities portfolio management are applied forming and managing the portfolio of investment fund. Integrated assets and liabilities management is based on computerised decision models that represent both the assets and liabilities associated with the business line, characterise the uncertainty of the future environment and produce strategies for structuring the assets and liabilities in business ways that are profitable across a range of alternative future environments. The methods of imitative modelling are used and obtained results are presented in geometrical form of portfolio sets, their efficiency zones, density and survival functions.
COGNITIVE APPROACH TO DISTANCE LEARNING MATERIALS PREPARATION ADAPTED TO ASYNCHRONOUS MODE
Authors: Zaikine Oleg , Kushtina Emma , Rozewski Przemyslaw
Published: February 2019

The authors discuss the method of designing the distance learning didactic materials for the asynchronous mode. The approach is based on the modular structure of the fundamental knowledge. The new role of the teacher is being discussed as well as its impact on the didactic materials’ structure and content. The paper introduces the knowledge representation model designed to meet the requirements of theoretical knowledge presentation in a selected domain using the Learning Object concept.
YOUTH UNEMPLOYMENT AND ITS REDUCTION MEASURES
Authors: Šileika Algis , Rupšys Valdas , Gruževskis Boguslavas
Published: February 2019

The efficient use of the labour force in post‐industrial society predetermines the competitiveness of the economy and encourages social development. In this context, youth unemployment is a particularly undesirable phenomenon, reducing the efficiency of youth labour force within the level of general labour, raising social costs, and restricting social development. The position of young people on the labour market depends on a number of social, economic and demographic factors, leading to the conclusion that youth unemployment as a socio‐economic phenomenon is a particularly negative result of the interaction between these factors. The aim of the paper is to discuss the theoretical assumptions of the youth integration to the labour market and to discuss the subsequences of their unemployment. Another target of the paper is to propose the policy measures for rising economic activity of the youth. The authors of the article suggest that the youth integration to the labour market could be increased by integrated decisions based on qualified services of vocational training.
SUPPORT TO SMALL AND MEDIUM ENTERPRISES ‐ BUSINESS INCUBATORS IN SLOVAKIA
Authors: Kašjaková Ol'ga
Published: February 2019

In both developed and developing economies, policies supporting small and medium enterprises are widely promoted as their role for economic and social development is universally recognised. Support programs range from technical assistance to tax incentives, from direct supply of capital to regulatory provisions, training, support to innovation and other types of incentives. One of the mechanisms employed to nurture small firms for more than two decades is “business incubation”.
TRANSITION PROCESSES IN LITHUANIA AND OTHER EAST - AND CENTRAL EUROPEAN COUNTRIES: DEVELOPMENT OF UNIVERSITY AND PROFESSIONAL STUDIES SYSTEM
Authors: Melnikas Borisas
Published: February 2019

The present state of university and professional education in Lithuania and major problems of its development are outlined. The possibilities of upgrading university and professional studies are evaluated, taking into account the processes associated with the integration of Lithuania into the European Union. In addition, the prospects of education development are analyzed in the context of transitions characteristic of the states of Central and Eastern Europe.
MULTI-OBJECTIVE OPTIMIZATION FOR FACILITIES MANAGEMENT
Authors: Brauers Willem K.
Published: February 2019

The main point of this article is to present in a short text all aspects of Multi ‐ Objective Optimization for Facilities Management, so to say from the cradle until the grave. Additionally, the combination of Multi ‐ Objective Optimization with Nominal Methods and Scenario Writing represents an innovation. It is also stated that all stakeholders interested in the issue, instead of one decision maker, have to be involved. First, desk research will discover all the surrounding conditions of the issue under consideration. Therefore, during a period of creative thinking in a nominal exercise all the main influencing events are recorded and finally ranked. From this information, scenarios for the future of the facilities sector are deduced. On basis of all these data, objectives and alternatives are simulated. A Multi ‐ Objective Optimization for the facilities sector is made possible by two methods: an additive method with ratios and the application of Reference Point Theory. Automatically, using these methods, all objectives are normalized to dimensionless numbers between zero and one. Nevertheless, a problem of importance for each objective may remain. Therefore, two methods are proposed. First, weights are granted in a nonlinear way. Secondly, an objective becomes more important by introducing different attributes for the same objective. The latter method seems to be more refined. In this way, a final ranking of the alternatives for the fulfillment of the objectives is obtained.
Occupational Safety and Health in Transnational Workplaces: The Case of Posted Workers
Authors: Vah Jevšnik Mojca , Rogelja Nataša
Published: February 2019

The article presents the results of an empirical study on the occupational safety and health (OSH) of posted workers in transnational, multilingual and multi-employer workplaces. The argument is based on data obtained from semi-structured interviews with key stakeholders in Slovenia, which we analyse within the framework of Sargeant and Tucker’s (2009) layered vulnerability approach. We discuss multiple vulnerabilities of posted workers who are disproportionally recruited into hazardous jobs and exposed to numerous health hazards. Possible measures to reduce OSH-related vulnerabilities of posted workers are identified and discussed, including the role of information sharing and awareness raising.
Biografsko učenje in spreminjanje identitete: Migracijske izkušnje Neže Gerkšič − Agnes Lacroix
Authors: Kožar Rosulnik Klara
Published: February 2019

Avtorica v prispevku migracijske izkušnje svoje pratete Neže Gerkšič oz. Agnes Lacroix obravnava kot polje učenja in ga interpretira s teorijo biografskega učenja. Biografsko učenje obravnava kot proces, ki se dogaja v vsakdanjem življenju in (re)konstruira identiteto, znanje, veščine, stališča in vrednote. Z analizo avtobiografskega zapisa prikaže, kako je akterka migracij z različnimi strategijami (s prilagajanjem, z osebnostno rastjo, razvojem individualnega sloga življenja, s poseganjem v družbena pravila okolja, z inovativnim učenjem) oblikovala svoja znanje in identiteto. Avtorica strategije učenja predstavi kot orodje, s katerim analizira in interpretira učenje ob izkušnji migracije.
The European Digital Fortress and Large Biometric EU IT Systems: Border Criminology, Technology, and Human Rights
Authors: Završnik Aleš
Published: February 2019

Today, at a time when we are witnessing the “multiplication of borders”, borders are occupying new domains. The article focuses on the erection of digital borders by means of biometric technology, which is creating new knowledge through the compilation of large biometric databases in the EU. By “tattooing” borders onto immigrant bodies, disciplinary power is being superseded by the post-disciplinary power of “instant surveillance”. The article continues by analysing re-bordering practices by means of seemingly apolitical information technology, and concludes by delving into the new harms caused by re-bordering, including violations of human rights and the emergence of multi-layered criminal law.
Rejected Syrians: Violations of the Principle of “Non-Refoulement” in Turkey, Jordan and Lebanon
Authors: Badalič Vasja
Published: February 2019

The article analyses the practices used by Turkey, Jordan and Lebanon to prevent Syrians from exercising their right to seek and enjoy asylum. The article consists of two sections. The first section examines how all three host countries violated the principle of non-refoulement by employing a range of unlawful practices (e.g. border closures and “pushbacks”, arbitrary detentions and deportations etc.). The second section examines how Lebanon resorted to practices that created circumstances for constructive refoulement of Syrian asylum seekers and refugees (e.g. shutting down the authority responsible for processing asylum claims, stripping Syrian refugees of their protected status etc.).
BIG IDEAS IN TINY HOUSE RESEARCH AT NORWICH UNIVERSITY
Authors: Lutz Matthew
Published: February 2019

INTRODUCTION

A small but notable trend that may offset energy consumption is emerging in a grassroots architectural counterculture movement focused on designing and building tiny houses. These small dwellings, ranging between 120 square feet and 400 square feet, simultaneously aim to consolidate, simplify, and minimize the energy requirements of the average size house while relieving their occupants of the burdens that come with owning a typical house. Tiny houses are entering the mainstream, showing up in unexpected places and catering to people from diverse backgrounds. Full-scale design/build prototype tiny houses developed at Norwich University serve as case-studies that may help prove, disprove and bring into question the effectiveness of the tiny house. This article will examine the second prototype house designed and built by Norwich University and will dive into some of the dynamic forces behind the tiny house movement and question how that movement might evolve and adapt to accommodate future scenarios.
Une histoire provinciale
Authors: Christol Michel
Published: February 2019

Les trente-cinq études de ce volume, revues et mises à jour, retracent l’histoire de la Gaule méridionale, appelée d’abord Transalpine puis Narbonnaise, des premiers temps de la présence romaine aux débuts de l’Antiquité tardive et montrent les transformations d’un monde provincial sous l’empreinte de Rome. Une nouvelle géographie économique apparaît avec le déplacement des centres de gravité, de Narbonne vers la vallée du Rhône et Lyon. La romanisation de la société est autant politique que religieuse. On assiste à une intégration réussie des élites - notables issus de l’Italie et descendants des grandes familles aristocratiques indigènes - mais également à l’ascension des représentants de la société civique provinciale - le commun des détenteurs des magistratures et des sacerdoces. S’épanouit alors au cours de la seconde moitié du premier siècle av. J.-C. une culture de l’écrit qui se manifeste, en particulier par l’abondante production épigraphique, dans les lieux funéraires, les grandes demeures et les espaces publics urbains.

L’accès des grandes familles à l’ordre équestre et à l’ordre sénatorial, puis leur participation au gouvernement de l’Empire viennent concrétiser, dès le premier siècle ap. J.-C., le rapprochement entre l’Italie et cette partie de l’Empire romain, dont le destin apparaît alors comme singulier, selon l’expression de Pline l’Ancien : À la vérité, plus l’Italie qu’une province.

Cette somme érudite est appelée à devenir une œuvre de référence sur l’histoire de la Gaule narbonnaise.
D’une réforme à l’autre (816-934)
Authors: Gaillard Michèle
Published: February 2019

Les dates de deux réformes monastiques, 816 et 934, encadrent le propos de ce livre. Entre ces deux dates, l’empire carolingien a changé de visage, la région étudiée est passée du statut de cœur d’un empire à celui de région disputée entre les deux principales entité politiques, la Francie de l’Est et la Francie de l’Ouest, avec pour arbitres les grandes familles aristocratiques qui étendent leurs emprises sur les sièges épiscopaux et les communautés religieuses.

Dans leur processus et leurs motivations, les deux réformes de 816 et de 934 se ressemblent peu. La première, initiée par l’empereur Louis le Pieux et son conseiller Benoît d’Aniane, doit s’appliquer à tous les monastères de l’Empire carolingien. Elle est guidée par un souci d’uniformisation et d’efficacité de la prière des moines. La seconde, appuyée par l’évêque de Metz Adalbéron Ier, grand aristocrate lotharingien, est menée à l’initiative de clercs et de moines pieux des diocèses de Metz, Toul et Verdun, regroupés dans l’ancien monastère de Gorze sous la direction d’Einold et de Jean de Vandières. Cependant, à l’origine des deux réformes s’exprime la même volonté de restaurer la vie monastique par l’observance de la règle de Saint Benoit de Nursie et la remise en ordre du temporel monastique.

Le présent ouvrage est né d’une interrogation sur la notion de réforme, en particulier dans le milieu monastique, et sur son corollaire, la notion de décadence, amplement invoquée par les réformateurs. Par-delà l’histoire de la réforme monastique en Lorraine carolingienne, l’ouvrage met en évidence la façon dont les communautés religieuses ont construit leur patrimoine et leur histoire, les relations étroites de ces communautés avec le pouvoir, royal, aristocratique ou épiscopal, ainsi que la façon dont ces communautés ont exercé leur fonction essentielle, celle de la prière et de la mémoire.
La cité et l’Empereur
Authors: Hostein Antony
Published: February 2019

Comment, pendant plus de cinq siècles, les dirigeants de Rome ont-ils pu assurer l'unité d'un vaste empire s'étendant de l'Écosse actuelle aux confins du désert arabique ? Une réponse à ce questionnement est apportée par des orateurs de la fin du iiie siècle de notre ère, originaires d'Autun en Gaule, auteurs de discours rassemblés dans le recueil des Panégyriques latins. Ce livre propose une relecture inédite des Panégyriques latins V(9) et VIII(5), témoins uniques des modes de communication qui pouvaient s'établir entre les représentants d'une communauté civique et les autorités impériales.

Dans cet échange mélangeant enjeux administratifs et rituels de cour, convaincre le prince passait par une utilisation habile de la rhétorique de l'éloge. Héritiers de traditions élaborées en Orient à l'orée du Principat, les panégyristes éduens montrent leur maîtrise du genre appelé « discours d'ambassade », mobilisé pour formuler des requêtes officielles ou défendre les intérêts locaux. Dans la stratégie persuasive à l'œuvre, les fleurs de rhétorique, loin de n'être que de vaines paroles, révèlent une multitude d'informations sur la vie municipale, l'évergétisme, la culture des notables, les rituels du pouvoir et bien d'autres choses encore.

Par cette réhabilitation d'une documentation longtemps négligée, l'analyse apporte des éclairages nouveaux sur la survie des institutions et des idéaux civiques en Gaule au lendemain de la crise du iiie siècle et, chemin faisant, sur la phase ultime du processus de romanisation. En dernier lieu, ces discours révèlent l'existence, au sein de l'Empire, d'un phénomène unique dans l'histoire, produit d'un mélange subtil de pratiques administratives et de tractations diplomatiques entre les cités et le pouvoir central. Le dialogue noué dans le cadre de la « diplomatie intérieure », source de compromis et d'équilibre entre ces deux échelons de gouvernement, a joué un rôle essentiel dans la cohésion de l'imperium Romanum.
Évolution de la formation en conservation-restauration en Allemagne
Authors: Buchholtz Christina von , Becker Julia
Published: February 2019

La profession de conservateur-restaurateur s'est de plus en plus structurée au cours du dernier siècle grâce aux chartes internationales sur la conservation des biens culturels et aux accords européens sur l'enseignement supérieur, à la suite du processus de Bologne initié en 1999. Cet article a pour but de retracer le développement de la formation des restaurateurs en Allemagne depuis les années 1950 jusqu'à nos jours, sans prétendre à l'exhaustivité.
Une « recommandation pour la conservation-restauration du patrimoine culturel »
Authors: Castaldi Monica Martelli , Cueco David Aguilella , Hutchings Jeremy , Organisations E.C.C.O. European Confederation of
Published: February 2019

Le projet de première recommandation Européenne pour la conservation-restauration du patrimoine culturel proposé par l’E.C.C.O., écrit avec le soutien de l’ICCROM et la participation de l’ENCoRE, constitue un pas en avant pour garantir la préservation du patrimoine culturel et une meilleure reconnaissance des acteurs de ce domaine.La recommandation considère la nécessité de définir et de réglementer le domaine en tant que tel dans son ensemble. Cet article présente ce document et le replace dans le contexte du travail effectué par l’E.C.C.O. qui comprend bien d’autres contributions visant à définir la profession de conservateur-restaurateur, à sensibiliser et à assurer la préservation du patrimoine culturel dans son ensemble.
La Prise de Calais, une campagne de conservation-restauration épique ?
Authors: Verheyden Olivier
Published: February 2019

Retrouvée dans une cave, une toile monumentale de 25 m2, réplique d’époque d’une œuvre du XIXe siècle, menace ruine. Sa conservation-restauration engage une équipe d’étudiants dans une expérience pédagogique hors pair.
Restoring Lumino-Kinetic art
Authors: Olivier Steib
Published: February 2019

This paper sum up the different steps and decisions taken in the restoration of two “Mobiles Lumineux” made by Nino Calos (1926-1990) and conserved in the Museum of Modern Art of Paris. This article highlights the problematic of the obsolescence of the lighting systems, and how to resolve it.
Un nouveau cursus en conservation-restauration à l’Académie des Beaux-Arts de Kinshasa
Authors: Gesché-Koning Nicole
Published: February 2019

Grâce à un partenariat entre l’Académie des Beaux-Arts de Kinshasa et l’École nationale supérieure des Arts visuels de la Cambre, l’année 2013 a vu le lancement, à Kinshasa, d’une Licence en Conservation-restauration d’œuvres d’art – Bois et céramique. L’occasion de questionner le rôle et la position du conservateur-restaurateur en Afrique.
Témoignage d’une ex - jeune lectrice
Authors: Berducou Marie
Published: February 2019

L'article constitue un témoignage personnel sur la découverte des ouvrages-clés de la conservation-restauration, dans les années 70.
La restauration problématique d’une œuvre lumineuse conceptuelle
Authors: Steib Olivier
Published: February 2019

L’œuvre Erlauf de Jenny Holzer est un panneau lumineux faisant partie d’une série, réalisée en 1998. Une étude préalable a été menée en vue de sa restauration, qui a soulevé les difficultés relatives à ce type d’objet. Ce cas a permis une collaboration internationale entre l’atelier de l’artiste, des techniciens et des musées, dont le Conservateur-Restaurateur a la charge de la coordination et de la gestion des points de vue parfois opposés de chacun.
De l’intention de l’artiste à l’effet de l’œuvre. Changer l’approche en conservation ?
Authors: Verbeeck Muriel
Published: February 2019

L’art contemporain n’invite plus à la contemplation (où esthétique et histoire se conjoignent), mais à l’action et l’interaction. L’artiste utilise des moyens au service d’une fonction esthétique : le but est d’obtenir un « effet ». L’analyse matérielle et fonctionnelle, l’approche technique et analytique sont insuffisantes pour expliquer ces mutations. La pensée de Gérard Genette pourrait fournir au conservateur-restaurateur d’intéressantes pistes de réflexion. Sa définition de l’œuvre d’art et le concept d’attentionnalité sont en effet particulièrement utiles à une révision méthodologique.
Low Cycle Fatigue Behavior of N80Q Steel under the Influence of Mean Strains
Authors: Wei Wen Lan , Han Li Hong , Feng Yao Rong , Zhang Jian Xun , Wang Hang
Published: February 2019

The service conditions of thermal recovery wells make the casing repeatedly bear the tension and compression load and form low cycle fatigue. Meanwhile, many factors, such as pre-strain and creep, lead to the formation of asymmetrical low cycle fatigue (R≠-1), which is the low cycle fatigue behavior under the influence of mean strain. This work studied the effect of mean strain on low cycle fatigue behavior of N80Q steel. Different strain amplitude conditions were selected for low cycle fatigue test, which were 0.5%, 0.7%, 1.0%, 1.5% and 2.0% respectively. Then tests at mean strains of-0.8%, 0%, 0.5% and 1.0% were conducted under constant strain amplitude. And the microstructure and fracture surface of the material after the tests were characterized using scanning electron microscopy and transmission electron microscopy, respectively. The results show that the mean strain makes the fatigue life reduce significantly under the condition of constant strain amplitude, and is related to the amplitude of the mean strain. The value of the mean strain and the strain amplitude will ultimately affect the fatigue life. And the fatigue life is related to the maximum absolute value of strain and has a linear relationship in the double logarithmic coordinate system. The SEM results of fracture morphology show that the brittleness feature of the crack growth area with high mean strain decreases significantly. And the fracture cross-section observation shows that the crack propagation is transgranular propagation. The TEM results show that a large number of dislocations pile-up is formed at lath subgrain boundary.
Properties of CT130 Grade Coiled Tubing
Authors: Liu Yun , Xian Lin Yun , Yu Han , Li Hong Bin , Wei Feng
Published: February 2019

CT130 coiled tubing has high strength and high resistance to pressure, it is an important tool and has unique advantages in solving stimulation and stable production problems in ultra-deep and extended reach horizontal well, especially for the multiple stage fracturing and the plug milling in shale gas. In this paper the microstructure, mechanical properties, fatigue resistance of CT130 coiled tubing is studied. The results show that the microstructure of CT130 grade coiled tubing is the side plate ferrite and granular bainate. The properties analysis indicates that CT130 coiled tubing possesses 938MPa yield strength, 1018 MPa tensile strength, and the hardness is less than 333HV0.5，all these properties are met the industry design standard. It also possess superior internal and external pressure resistance. the collapse pressure of tube body is 200.4MPa，and bursting pressure reaches up to 219.1MPa. The fatigue life of Φ50.8×4.8mm CT130 coiled tubing is 31.2 percent higher compared with the same size of CT110 coiled tubing and the running depth increased 18.1 percent at least under the same condition.
Stress Analysis and Microstructure Evolution of Titanium Alloy Pipe during Flattening Processing
Authors: Chen Jun , Xin She Wei , Zhou Wei , Li Qian , Zhang Si Yuan , Li Lei , Yang Hai Ying , Wang Ting Xun
Published: February 2019

TA24 titanium alloy pipe with 638mm diameter and 19mm wall thickness is carried out continuous load flatten test, and the stress of internal and external pipe wall during flatten process is studied in this paper. The results show that the TA24 titanium alloy tube has good flattening performance, and the flattening process has experienced original stage, flattened oblate stage, flattened straight wall stage, flattened depressed stage, flattened concave contact stage. During the flattening process, the outer layer of the upper and lower wall of the tube is subjected to compressive stress, and the inner layer material is subjected to tensile stress. The tensile and compressive forces cause the vertical part of the upper and lower walls to be concave. The outer layer of the left and right circular arc parts is subjected to tensile stress and the inner layer is subjected to tensile stress. The compressive stress also causes the radius of the arc to decrease due to the combined force of the tensile and compressive forces, that is, the flattening occurs. With the decrease of and pressing distance under continuous loading condition, the metal on the left and right sides of the pipe gathers toward the middle depression, which aggravates the deformation of the upper and lower walls until the upper and lower walls contact, and the arc radius of the left and right walls decreases until the outer surface cracks. The pipe microstructure changes significantly into elongated deformation structure during the flattening process. The most severe part of the deformation is the left and right end arc of the pipe, followed by the upper and lower end depression.
Influence Mechanism of Cu on High Temperature Oxidation Behavior of Titanium Alloys
Authors: Chen Hang , Mi Guang Bao , Li Pei Jie , Cao Chun Xiao
Published: February 2019

The oxidation behavior and mechanism of Ti-Cu alloys (0≤w(Cu)≤20%) in the temperature range of 1000°C～1300°C are studied by thermogravimetric analysis(TGA) combined with SEM, EDS and XRD analysis methods. The results show that the oxidation rates of Ti-Cu alloys increase sharply when the temperature rises above 1000°C. The oxidation products have a three-layer structure, from the outside to the inside, which are dense outer oxide layer of TiO2, porous inner oxide layer of low valence oxide of Ti and Cu-enriched layer. With the increase of the temperature, the thicknesses of oxide layers of Ti-Cu alloy increase and the Cu-enriched phase increases gradually and melts. The melting Cu-enriched phase flows to the oxidation surface along the grain boundaries of the oxide layer. The high temperature oxidation resistance of Ti-Cu alloys declines with the increase of Cu content. The main reason is that more liquid Cu-enriched phase is formed and flows to the oxidation surface along the oxide grain boundaries in the Ti-Cu alloy, and Ti and O ions can diffuse more easily along the liquid Cu-enriched phase, which increases the oxidation rates.
Preparation and Properties of SBS Modified Deoiled Asphalt and Slurry Blends
Authors: Gu Yi , Li Yu Shi , Huang Xiao Qiao , Yu Jian Ying
Published: February 2019

Deoiled asphalt (DOA) and slurry are by-products of petroleum refining process. In this paper, blending asphalt (DST) based on DOA, slurry and vacuum gas oil and SBS modified DST (SMDST) were prepared. The aging resistance of SMDST was investigated by thermal aging (TA) and ultraviolet (UV) aging. Meanwhile, the chemical structure and microstructure of SMDST before and after aging were characterized by Fourier transform infrared spectroscopy (FTIR) and fluorescence microscopy. The results showed that the softening point, ductility at 5 °C and low temperature flexibility of SMDST increased gradually with the increase of SBS content. When SBS content was 12 wt%, the softening point, ductility at 5 °C and low temperature flexibility of SMDST were 105 °C, 55 cm and -25 °C, respectively. After TA and UV, the low temperature flexible reductions of SMDST with 12 wt% SBS were 3 °C and 2 °C, respectively, which demonstrated that aged SMDST still had good crack resistance in low temperature. FTIR analysis indicated that the carbonyl (C=O) and the sulfoxide (S=O) characteristic peaks of SMDST were enhanced after aging to a certain extent. However, the fluorescence microscope observation showed the network structure of SMDSB was not damaged significantly, which implies that SMDST has a favourable anti-aging performance.
High Temperature Deformation Behavior in the Isothermal Compression of Ti-5Al-4Mo-2Cr-4Zr-2Sn-1Fe Alloy
Authors: Sun Hua Mei , Qi Yun Lian , Liu Wei , Mao Xiao Nan
Published: February 2019

The deformation behavior in isothermal compression of Ti-5Al-4Mo-2Cr-4Zr-2Sn-1Fe alloy was investigated at the deformation temperature of 800°C, 850°C, 900°C, 950°C and 1000°C, the strain rate of 0.01s-1, 0.1s-1, 1.0s-1and 10.0s-1, and the height reduction of 70%. The flow stress increases rapidly with the increasing of strain at the beginning of deformation. When the strain exceeds a certain value, the flow stress begins to decline and becomes steady. With the increasing of deformation temperature and decreasing of strain rate, the steady stress and peak stress decrease significantly. The effect of strain on the processing maps of Ti-5Al-4Mo-2Cr-4Zr-2Sn-1Fe alloy is obvious. As the strain increases, the instable region moves towards high temperature and high strain rate area. Meanwhile, the contour of efficiency of power dissipation becomes more and more intensive, and the region with high efficiency of power dissipation reduces. Strain rate of 0.01s-1and deformation temperature of 900°C are the optimum processing parameters for Ti-5Al-4Mo-2Cr-4Zr-2Sn-1Fe alloy forging under strain of 0.3.
Numerical Simulation of Dendrite Growth and Micro Segregation of Ni-Cu Alloy
Authors: Wang Ming Guang , Jiang Shan
Published: February 2019

Dendrite growth of Ni-0.4083%Cu alloy was simulated by the phase-field method in the paper. The impact of super-cooling degree and super-saturation degree and solute segregation on dendrite growth was studied systematically. solute segregation increased initially then tended to decrease. The increase of super-saturation can promote the growth of lateral branch and destroy the constancy of the dendrite tip at the same time. The simulation result was compared with the microscopic theory and they have a good agreement.
Phase Stability and Mechanical Properties of FCC Structural CoCrCu0.5FeNi High-Entropy Alloy with Silicon or Boron Addition
Authors: Chen Chen , Liu Ning , Zhou Peng Jie , Xiang Hong Fu
Published: February 2019

Microstructures, phase stability and properties of the as-solidified CoCrCu0.5FeNi(Si/B)x alloys were studied in this work. Intermetallic compounds are found when Si or B was added in a FCC structural CoCrCu0.5FeNi high-entropy alloy, and B possess a better intermetallic formation ability than Si. On the other, solute ability of Si is better than that of B in CoCrCu0.5FeNi alloy. The strength of CoCrCu0.5FeNi high-entropy alloy was improved after the addition of Si and B, and the strengthen mechanism was discussed. Moreover, parameter g can provide a reference to predict the ability of forming intermetallic compounds in CoCrCu0.5FeNi(Si/B)x alloys. The increase of δ is prone to the forming of intermetallic compounds. But the volume fraction of intermetallic compounds increase with the decrease of Ω in the same alloy system.
The Effects of Current Density on Microstructure and Properties of Electrolytic Copper Foils
Authors: Cheng Xi , Li Yan Feng , Huang Guo Jie , Yin Xiang Qian , Li Yong Zhen , Yao En Dong , Ma Xiu Ling , Xie Xiang Sheng , Qi Shan Long , Li Zi Ming
Published: February 2019

Under the condition of controlling the relevant electrolysis process parameters, 12μm-thick electrolytic copper foils were prepared by adjusting the electrodeposition time under different current densities. The surface morphology, mechanical properties and textures of the electrolytic copper foil at different current densities were studied using SEM, XRD, EBSD and universal testing machines. The fracture mechanism of the copper foil at different current densities was also analyzed in this paper. The results show that as the current density increases, the surface of the copper foil become larger and sharper. The main orientation of the crystal surface is {220}, and the preference firstly increases and then decreases. The high preference of the {220} crystal surface of the copper foil reduces its tensile strength. When the current density is from 8 to 14 A/dm2, the preferential degree of {111} decreases with the increase of current density, while the preferential degree of {220} increases, and the tensile strength of copper foil decreases. When the current density is from 14 to 26 A/dm2, the preferential degree of {111} and {311} increases with the increase of current density, while the preference of {220} crystal surface decreases, and the tensile strength of copper foil increases. The elongation of copper foil is affected by the fracture mechanism. When the current density is 8 A/dm2, the copper foil is plastically fractured and has high elongation. When the current density is 14A/dm2, the copper foil is brittle fracture and the elongation is low. When the current density is 26 A/dm2, the copper foil is plastically fractured but the effect of hydrogen evolution at high current density reduces the plasticity of the copper foil.
Evolution of Grain Boundary Character Distribution in Pure Copper during Low-Strain Thermomechanical Processing
Authors: Wu Guo Qing , Chen Zi Yun , Huang Ming , Qin Yuan , Ablat Alimjan , Jiang Han Lu , Yang Sen
Published: February 2019

In order to get optimal grain boundary character distribution (GBCD) and grain boundary properties, thermomechanical processing (TMP) is usually adopted in grain boundary engineering. However, the mechanism behind the TMP treatments and GBCD optimization is still unclear. The present study has conducted a series experiments involving low-strain TMPs to study the relationship between TMP parameters and the behind microstructural evolution. The experimental results indicate that in the scope of low-strain TMP, strain induced boundary migration (SIBM) is the most effective process for GBCD optimization. Besides, SIBM and grain growth would gradually transfer to recrystallization with the increase of pre-deformation level and annealing temperature. Further quasi in-situ EBSD results infer that SBIM is activated locally in some region with high stored energy, and further gradual initiation of SIBM from one region to another contributes to the gradual increase of special boundaries with annealing time.
Optimization Technology of Roll Contours during Skin-Pass Rolling Process of Hot-Rolled Strip
Authors: Song Guang Yi , Wang Xiao Chen , Yang Quan , Zhao Jian Wei
Published: February 2019

The hot-rolled strip skin-pass mill is the important technological equipment of finishing process in the hot rolling plant, and its role is to apply a slight thickness reduction of approximately 1% - 4% to the finished products cooled to room temperature to repair flatness defects and improve the surface quality and mechanical properties. In this study, the initial flat roll contours were optimized to solve some problems such as the serious and non-uniform wear of work rolls and the poor shape control abilities of the strip. A three-dimensional rolls–strip coupling model of hot-rolled strip skin-pass mill was established using the nonlinear finite element software ABAQUS. The effects of the roll contours on the contact pressure between rolls and the control effect of bending forces were analyzed, and a variable contact-length backup roll (VCR) contour configured with a positive crown contour for work rolls was proposed. Compared with the initial flat roll contours, the average replacement cycle of work rolls for the optimized roll contours increased from 465.4 tons to 701.3 tons, the non-uniform wear amount was reduced by nearly 15%, and the adjustment ratio of the negative bending forces decreased from -100% to -40% by industrial experiments in the 1580 mm single-stand four-high hot-rolled strip skin-pass mill.
Study on Continuous Cooling Transformation and Microstructure of 500 Mpa Grade Steel for Railway Freight Car Body
Authors: Jiang Mao Lin , Yu Wei
Published: February 2019

Complete the composition design and laboratory smelting of high strength weathering steel for railway freight car body of grade 500MPa. The actual continuous cooling transformation curve (CCT curve and cold speed of 0.5-50 °C/s) was measured through the Gleeble3500 thermal simulation test machine with expansion method and alloy phase method, observing the microstructures by optical microscope and SEM. The hardness of the samples under different cooling rates were measured by Vivtorinox hardness tester. Study on the effect of cooling rates on the microstructures and hardness of the steels.
Solution Treatment of 20LH5 Chromium-Manganese Austenitic Stainless Steel
Authors: Su Yang , Song Ren Bo , Cai Heng Jun , Wen Jian , Wang Tian Yi
Published: February 2019

In this study, based on the existing 20LH5 austenitic stainless steel for sieve, the influence of different solution treatment parameters on the microstructure and properties were studied. Through the simulation before the experiment, the suitable theoretical solution treatment temperature range for the steel plate is 800 °C~1100 °C according to the empirical formula, and the optimal holding time range is 5 s-15 s. In the optimal temperature range and the best solution treatment time, the gradient was set in the interval and then cooled by water and air after heating. The results show that the grain of the sample steel before pre-treatment (cold rolled then pre-annealed before leaving the factory) is coarser, and the microstructure of the steel plate after solution treatment has obvious refinement tendency and a large number of annealing twins are formed. The softening effect is remarkable. At 800 °C + 15 s + water cooling and 950 °C + 10 s + water cooling, the tensile strength of the two processes are greater than 1000 MPa, the yield strength of the two processes are greater than 440 MPa, and the elongation of the two processes are greater than 46%.The steel sheets obtained by solution treatment under both experimental parameters can achieve good mechanical properties and meet the expected specifications of the products.
Double Annealing Processes of Ti-5Al-5Mo-5V-1Cr-1Fe Titanium Alloy
Authors: Wang Qing Rui , Sha Ai Xue , Huang Li Jun , Li Xing Wu , Mi Guang Bao
Published: February 2019

In this work, double annealing processes of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy were systemically investigated, and the microstructure and property of different processes were compared. The results show that, when the first stage annealing is air cooling, the microstructure with continuous and straight grain boundary is obtained, and corresponding mechanical property is not very good; When the first stage annealing is furnace cooling, the influence of first stage annealing temperature on microstructure and property is obvious. Excellent comprehensive property can be obtained when β grain boundary and a phase are discontinuous and tortuous. Further, based on this research, a new double annealing process is developed, which can obtain excellent ductility when large size forging is fabricated above the phase transformation point and has small deformation.
Optimization of Quenching Process Parameters of 15CrNiMo Steel Used for Roller Bit Bits
Authors: Su Sheng Rui , Song Ren Bo , Chen Chi , Ji Wen Sheng , Li Shi De , Li Mei Ling
Published: February 2019

The microstructure and mechanics of 15CrNiMo steel with different quenching temperatures (800°C, 825°C, 850°C, 875°C, 900°C) and different quenching holding time (15min, 25min, 35min) were studied for steel 15CrNiMo for roller bit. The relationship between the properties of different quenching parameters and the mechanical properties such as microstructure, impact toughness and hardness was analyzed. The results show that the microstructure of the annealed precursor is mainly ferrite and pearlite. With the increase of quenching temperature, the ferrite is gradually reduced, the lath martensite is gradually increased, and the martensite grains tend to grow. The strength increases first and then decreases, and the plasticity increases slightly. The quenching and holding time has no obvious effect on the test steel, and the austenitization of the core is the best time. The best quenching temperature is 850°C, the best holding time is 25 min, (tempering temperature is 220°C, tempering holding time is 50 min) and the mechanical properties are optimal.
Corrosion Behavior and Mechanism of Heat-Resistant Steel T91 in High-Temperature Carbon Dioxide Environment
Authors: Gui Yong , Liang Zhi Yuan , Yu Miao , Zhao Qin Xin
Published: February 2019

Corrosion behavior of martensitic heat resisting steel T91 in high-temperature carbon dioxide environment at 500-700 °C was investigated. X-ray diffraction, scanning electron microscopy and glow-discharge optical emission spectrometry were employed to characterize the corrosion products. The results showed that the corrosion kinetics of T91 followed a parabolic law with experimental time. The oxide scale thickness of T91 followed an exponential growth law from 500 °C to 700 °C. Internal carburization was detected underneath the corrosion scale. What’s more, the carburization depth was larger than the corrosion scale. The variations of Cr and C elements distribution were discussed.
Analysis of Transverse Cracks Forming in a Railway Axle
Authors: Yin Hong Xiang
Published: February 2019

Surface defect is the main form of axle failure. In this paper, the cause of surface defect on wheel seat of a certain type of dynamic axle is analyzed systematically. In the test, the macroscopic chemical component of inspection axle was determined using spectrometer. And the chemical composition near the crack was detected by energy disperse spectroscopy and X-ray photoelectron spectroscopy analysis. The microstructure of the crack area was observed by optical microscope, while the crack microscopic characteristic was characterized using scanning electron microscope and confocal laser scanning microscope. The study found that, the defect is transverse crack, which was distributed circumferentially along the wheel seat. Further more, the typical features of wear or friction and iron oxide was observed on the wheel seat near the crack area. It was concluded that, due to surface presure and the existence of stress concentration, which the wheel and axle interference fit resulted in, wear abrasion and fretting fatigue initiated fatigue crack.