bluuebunny/crossref_metadata_2025 huggingface dataset:
Mexico, la ville insoutenable ? (Mexico, the unsustainable city ?)
Authors: Tutin Christian , de la Vega Xavier
Published: April 2015

Résumé. - La ville de Mexico est périodiquement touchée par les manifestations de deux risques naturels majeurs : le risque sismique et le risque volcanologique. Mais les risques générés par la croissance même de la ville sont encore plus importants pour l'avenir de celle-ci. Il s'agit de risques écologiques, qui touchent à l'eau, à l'air et aux sols. La dégradation des conditions du milieu physique, et du milieu urbain lui-même, est telle que des limites sont proches d'être atteintes, au-delà desquelles toutes sortes de catastrophes majeures deviennent possibles. Les actions des pouvoirs publics se développent depuis 1988 en se heurtant à de nombreux obstacles : positions clés de l'industrie pétrolière et automobile, carences de l'organisation politique et administrative. Mexico apparaît de plus en plus ingouvernable. La gestion du risque constitué par l'incompatibilité entre le maintien du milieu et les formes actuelles de la croissance urbaine doit être assumée. Elle passe par l'adoption d'un modèle de croissance économique à long terme, incorporant les modifications du patrimoine urbain, les altérations du milieu physique et les évolutions démographiques.
Lumière des nations et gloire d’Israël. Le programme de Nostra aetate 4 pour le renouvellement de la christologie
Authors: Andrevon Martine-Thérèse
Published: April 2015

La promulgation de Nostra aetate  4 a profondément modifié la relation de l’Église au peuple juif. Elle met aussi en lumière de nouveaux défis théologiques. Parmi eux, la christologie apparaît comme une discipline majeure pour une théologie chrétienne du judaïsme. Mais quelle incidence la judéité retrouvée de Jésus a-t-elle pour le chrétien du xxi e  siècle ? L’article commence par analyser les traces de christologie que l’on peut trouver dans les principaux textes récents du Magistère qui traitent de la question des juifs et du judaïsme. Puis l’A. propose quelques pistes pour élaborer une christologie, non pas de la séparation avec Israël, mais où le Christ constitue le nœud entre juifs et chrétiens, à la fois leur connexion et leurs désaccords.
« Ils seront ses peuples... » (Ap 21,3). Redécouvrir la théologie du peuple de Dieu
Authors: Guggenheim Antoine
Published: April 2015

On a d’abord reçu l’enseignement du concile Vatican ii sur l’Église comme « peuple de Dieu » comme une réponse théologique au contexte de la sécularisation. Sans renier l’apport positif de ces interprétations, on doit relire aujourd’hui les textes du Concile dans le contexte de la globalisation. La transformation des relations avec le judaïsme et l’intensification du dialogue interreligieux, que le Concile a initiées et que demande la rencontre des peuples, renouvelle la compréhension du syntagme « peuple de Dieu » et précise sa pertinence pour exprimer la responsabilité de l’Église et des chrétiens dans le moment présent de l’histoire.
Towards an Immanent Critique of Forms of Life
Authors: Jaeggi Rahel
Published: April 2015

Une critique des formes de vie est-elle possible ? Peut-on dire que des formes de vie sont bonnes, réussies ou même rationnelles ? Tandis que la philosophie a abandonné la question socratique de la vie bonne, la politique des démocraties libérales constitutionnelles se présente comme une manière d’organiser la coexistence en restant neutre quand aux différentes formes de vie. La façon dont nous devons vivre notre vie est reléguée à la sphère privée, comme une préférence singulière qui ne peut pas être questionnée. Dans cet article, l’auteur avance la possibilité d’une critique sociale immanente des formes de vie, dépassant ainsi les distinctions contraignantes entre l’éthique et la morale, la vie bonne et les principes moraux, le bien et le juste. Cela suppose d’expliquer d’abord ce que sont les formes de vie, comment elles fonctionnent, et quelle en est l’ontologie qui les rend réactives à la critique. Pour qu’une critique ne soit pas arbitraire, l’auteur montre ensuite que les raisons et les standards de la critique se trouvent dans la structure même des formes de vie, une fois qu’on les comprend comme des processus historiquement situés de résolution de problèmes. Les formes de vie sont donc en interaction avec leur critique ; celle-ci peut alors être immanente et émancipatrice.
Les sciences sociales au service de la « modernisation » dans la formation de l’encadrement à EDF
Authors: Martin Emmanuel
Published: April 2015

L’encadrement joue un rôle crucial dans la modernisation des entreprises publiques : il est chargé de « conduire le changement ». À cet effet, des dispositifs de formation sont mis en place pour convertir les encadrants à leur rôle de manager, tout au long du processus de modernisation de l’entreprise EDF. Loin d’occuper une place marginale, les sciences sociales (psychosociologie et sociologie, en particulier), implantées de longue date dans cette entreprise, interviennent dans ces dispositifs comme des auxiliaires utiles. Il s’agit de faire accepter aux (futurs) encadrants les contradictions fondatrices associées à leur fonction et à leur position dans la hiérarchie. À ce problème, les sciences sociales apportent une contribution décisive, notamment par le biais de dispositifs qui entraînent les (futurs) encadrants à exercer leur autorité, et cherchent à transformer leur subjectivité. Néanmoins, le recours aux sciences sociales est de moins en moins fréquent, en raison de son coût relatif face à des méthodes plus « pragmatiques ».
Origines contrôlées
Authors: Gauthier Jérémie
Published: April 2015

À partir de données ethnographiques recueillies dans des commissariats de sécurité publique en région parisienne et à Berlin, cet article propose de comparer les formes de racialisation des discours policiers et des interactions entre police et population. La recherche montre tout d’abord que la manière dont les policiers problématisent l’altérité présente des similitudes entre Berlin et la région parisienne ; ensuite, que si les populations minoritaires font l’objet d’un ciblage policier dans les deux contextes, la nature de ce ciblage diffère entre les cas français et allemand. Les stratégies de prévention mises en place à Berlin conduisent notamment à réduire la fréquence des pratiques policières les plus coercitives. La recherche invite à minorer les explications individuelles au profit d’une approche plus systémique des discriminations policières.
Des communicants en réflexion. Entre quête de savoirs et pratiques réflexives
Authors: Viers Jacques , Charpentier Jean-Marie
Published: April 2015

Depuis 2010, des responsables de communication interne participent chaque année à des sessions de formation proposées par l’ afci (Association française de communication interne) sur l’apport des sciences humaines et sociales à la communication, ainsi qu’à des groupes d’analyse de pratiques. Rencontrant un certain succès de participation, ces démarches qui s’appuient sur les sciences sociales traduisent à la fois des attentes nouvelles de la part des communicants au-delà des seuls savoir-faire de métier, et des questionnements sur leurs pratiques professionnelles en entreprises confrontées à des tensions et des contradictions.
Current Concepts, Classification, and Results in Short Stem Hip Arthroplasty
Authors: Falez Francesco , Casella Filippo , Papalia Matteo
Published: April 2015

Various short hip stems have been introduced with differing implant concepts of femoral fixation and implant length. There is a lack of proper classification for short hip stems, with a clear and accepted definition for implant length and extent of bone preservation in the metaphyseal and diaphyseal femur. This study analyzed the length of short hip stems. Stems were divided into collum, partial collum, and trochanter-sparing implants. An additional category was added, trochanter harming, which was defined as interruption of the circumferential integrity of the femoral neck. For all of the femoral components described, the designs were compared, excluding stems with insufficient clinical data. The 15 finally selected stems were classified as collum (1 stem), partial collum (7 stems), trochanter sparing (4 stems), and trochanter harming (3 stems). Mid-term results (>5 years of follow-up) were available for only 3 designs in the partial collum group. Taking into account the results of short-term studies (<5 years of follow-up), the femoral revision rate per 100 observed component years was <1 for most total hip arthroplasties. However, the studies varied greatly regarding level of significance, and short hip stems without published results are available commercially. Short hip stems cannot be circumscribed by a simple length limit. For some designs, clinical data collected from large patient cohorts showed a survivorship comparable to traditional stems. In cases that must be revised, this often can be performed with a conventional primary stem, fulfilling the promise to preserve bone for potential future revisions in younger patients.
Short Stem Total Hip Arthroplasty in Patients With Rheumatoid Arthritis
Authors: Bause Ludwig
Published: April 2015

Total hip arthroplasty (THA) has proven successful in patients with rheumatoid arthritis (RA). Patients with RA often require multiple revisions, and bone conservation is mandatory. A variety of short stems is currently available with mid-term results for osteoarthritis. This retrospective study evaluated mid-term clinical results of short stem THA in a series of patients with RA. Between 2005 and 2009, a total of 105 cementless short stems were implanted in patients with RA. Average patient age at the time of the index THA was 44.2 years, and average length of follow-up was 5 years. Clinical evaluation included physical examination and documentation of potential adverse events during the postoperative period. No radiographic failures occurred. Femoral and cup components showed some minor radiolucencies with sclerotic lines, but none involved 100% of the bone-prosthesis interface. Complications included femoral component subsidence in 2 hips after initial full weight bearing; 1 case resolved after 3 months, and the other case was revised to a standard shaft. One intraoperative dorsolateral stem tip perforation occurred with revision to a conventional length stem. Migration in 1 cup led to revision without removal of the short stem implant. No infections or joint dislocations were observed. The transfer of the short stem concept to an additional treatment option for patients with RA proved successful in the early to mid-term postoperative period. Complications and revisions were limited to early migration and early loosening of the implants in line with the results reported in the literature of cementless conventional THA in patients with RA.
Chronic innominate artery occlusion with hyperacute intracranial thromboembolism: Revascularization with simultaneous local thromboaspiration and mechanical thrombectomy
Authors: Gordhan Ajeet , Vanle Jesse
Published: April 2015

Chronic innominate artery occlusion with acute right internal carotid terminus thromboembolism and successful revascularization using simultaneous local thromboaspiration and mechanical thrombectomy has not been previously described.  A 51-year-old male presented with transient left hemiparesis. A CT angiogram of the head and neck demonstrated chronic occlusion of the right innominate artery with no intracranial thromboembolism.  More profound symptoms recurred twelve hours after admission.  A diagnostic catheter-based angiogram confirmed occlusion of the innominate artery and identified hyper-acute right carotid terminus thromboembolism. Angioplasty of the innominate artery was followed by simultaneous mechanical and aspiration thrombectomy of the right internal carotid artery terminus.  Combination local thromboaspiration and mechanical thrombectomy was shown in this case to be effective in achieving a favorable clinical outcome.
Annotated checklist of brachyuran crabs (Crustacea: Decapoda) of the Iberian Peninsula (SW Europe)
Authors: Marco-Herrero Elena , Abelló Pere , Drake Pilar , García-Raso Jose Enrique , González-Gordillo Juan Ignacio , Guerao Guillermo , Palero Ferran , Cuesta Jose A.
Published: April 2015

Almost 50 years have passed since a group of reputed carcinologists (viz. Lipke B. Holthuis, Isabella Gordon and Jacques Forest) finished the posthumous work of Ricardo Zariquiey Álvarez (1968) on decapod crustaceans of the Iberian Peninsula. No lists of decapod fauna specifically covering this area have been published since then, and an update is needed. The current list of brachyuran crabs of the Iberian Peninsula comprises 140 species, which is 35 species more than the 105 valid species listed in Zariquiey Álvarez (1968). Systematic changes have affected the original classification, so now there are 20 superfamilies, 36 families and 77 genera. Additional species have been recorded in Iberian waters due to natural range expansions from nearby areas (Mediterranean and Atlantic), introductions by anthropogenic activities, and description of new taxa. Also, two species were synonymized. Several of these changes, based on evidence from larval morphology and/ or molecular data, are detailed in this review. Although descriptions of crab species new to science are not expected to occur at a significant rate, an increase in the number of species in the Iberian Peninsula is expected to result from the introduction of alien species.
Physiological adaptation to Mediterranean habitats of the native crab Pachygrapsus marmoratus and the invasive Percnon gibbesi (Crustacea: Decapoda)
Authors: Tejada Silvia , Deudero Salud , Box Antonio , Sureda Antoni
Published: April 2015

Markers of oxidative stress in the hepatopancreas and carotenoid and vitamin E content in the carapace of the invasive crab Percnon gibbesi and the native crab Pachygrapsus marmoratus were compared as indicators of their physiological condition and environmental adaptation. Crabs similar in size were collected from coastal waters of Portals Vells (Mallorca Island, Spain; 39°28’18.79”N, 2°28’19.63”E) at < 1 m depth. Vitamin E levels were significantly higher in P. marmoratus than in P. gibbesi, whereas all carotenoid concentrations, except astaxanthin, were significantly higher in P. gibbesi. Catalase, glutathione peroxidase and glutathione reductase activities were significantly greater in P. marmoratus. Malondialdehyde concentration, a marker of lipid peroxidation, was higher in the hepatopancreas of P. gibbesi. The differences in carotenoid and vitamin E contents and in the antioxidant enzyme activities are a reflection of the different physiological activity of the two species and may suggest that P. gibbesi is not a potential competitor for the native crab P. marmoratus.
Road Safety and Energy Saving Proposed System: A Zigbee WSN Approach
Authors: Alhmiedat Tareq Ali , Omar Firas , Abu Taleb Anas , Alsswey Ahmad
Published: April 2015

The problem of long bended routes in Kingdom of Saudi Arabia (KSA) is one of the annoying problems that harvest a big number of vitalities annually. The problem relays under the fact that these long bended route are in shortage for lighting because of its extremely high cost. Therefore, in this paper, a system will be proposed as a smart alerting system based on ZigBee sensor network. The proposed system targets the roads with weak lights at night time in order to reduce the number of accidents which may occur on such dangerous roads. A number of real experiments were conducted using ZigBee sensor nodes in order to test the efficiency and reliability of the proposed system. Through real experiments, it was demonstrated that the proposed system offers reasonable response time, and achieves low power consumption.
La convention européenne des paysages: quels enseignements pour le Québec?
Authors: Domon Gérald , Ruiz Julie
Published: April 2015

Le paysage est aujourd’hui une ressource importante pour les territoires ruraux. Or, cette reconnaissance tarde à venir au Québec. Pour comprendre cet état de fait et proposer des pistes d’action pour contribuer à combler ce retard, l’article se penche avant tout sur la Convention européenne des paysages (CEP). Quinze ans après son adoption, le bilan de celle-ci ressort comme impressionnant tant au plan de la connaissance des paysages qu’elle a générées que des politiques mises en œuvre au sein des pays signataires. Puis, se tournant cette fois vers le Québec, l’article présente un premier portrait des initiatives de protection et de mise en valeur des paysages qui y ont été initiées. Ce portrait révèle à la fois le grand nombre de démarches régionales et locales en faveur du paysage et une timidité de l’action de l’État qui contraste avec la situation rencontrée en Europe. Misant sur cette diversité des démarches régionales et locales et sur les enseignements de la CEP, l’article propose dans un troisième temps une avenue qui pourrait permettre au Québec de s’offrir comme modèle de prise en compte des paysages en Amérique du Nord.
The Impact of Defense Investment on Economic Growth in the Perspective of Time Series
Authors: Pan Bin , Wei Shih-Yung , Xu Xuanhua , Hong Wei-Chiang
Published: April 2015

By considering the demand and supply effects of defense investment and the uncertainty of the stochastic process of the production and defense investment, this study proposes a stochastic endogenous growth model to explore the impact of defense investment on economic growth. The results suggest that the relationship between defense investment and economic growth rate is nonlinear and obtains the optimal percentage of defense investment to maximize economic growth. Moreover, the impact of defense investment volatility on economic growth rate is subject to production and defense investment interference term's covariance and representative private investment risk preference. Finally, the empirical data are used to illustrate the applicability of the proposed model.
Classification Trees as Proxies
Authors: Scime Anthony , Saiya Nilay , Murray Gregg R. , Jurek Steven J.
Published: April 2015

In data analysis, when data are unattainable, it is common to select a closely related attribute as a proxy. But sometimes substitution of one attribute for another is not sufficient to satisfy the needs of the analysis. In these cases, a classification model based on one dataset can be investigated as a possible proxy for another closely related domain's dataset. If the model's structure is sufficient to classify data from the related domain, the model can be used as a proxy tree. Such a proxy tree also provides an alternative characterization of the related domain. Just as important, if the original model does not successfully classify the related domain data the domains are not as closely related as believed. This paper presents a methodology for evaluating datasets as proxies along with three cases that demonstrate the methodology and the three types of results.
A High-Performance Parallelization and Load-Balancing Approach for Modern Power-Systems
Authors: Khaitan Siddhartha Kumar , McCalley James D.
Published: April 2015

Due to the recent trends of chip-miniaturization, the performance of a single-core is plateauing and hence, improving the performance of serial-execution based legacy code has become challenging. Since the expansion in power system operation continues to increase the number of contingencies to be examined, serial-execution platforms present a crucial bottleneck in analyzing sufficiently large number of contingencies within a reasonably small time for performing power-system stability analysis. This paper presents an approach to parallelize power system contingency analysis over multicore processors using Chapel language. To achieve load-balancing for avoiding wastage of computation resources, the authors use efficient work-stealing scheduling. They discuss the important features of Chapel and design choices which enable us to achieve high performance gains. The approach is evaluated using hundreds of contingencies of a large 13029-bus power system. The authors compare the performance of serial-execution with that obtained using 2, 4, 8 and 16 threads. The simulation results have shown that the approach outperforms a conventional scheduling technique, namely master-slave scheduling and also scales effectively with increasing number of threads. It is believed that the performance gains obtained from the approach would be highly useful for control center operators in analyzing a large number of contingencies and thus taking suitable corrective and preventive action against catastrophic events. Also, the insights gained from these experiments will be useful in several business enterprises.
F3N
Authors: Elmazi Donald , Spaho Evjola , Matsuo Keita , Oda Tetsuya , Ikeda Makoto , Barolli Leonard
Published: April 2015

Sensor networks supported by recent technological advances in low power wireless communications along with silicon integration of various functionalities are emerging as a critically important computer class that enable novel and low cost applications. There are many fundamental problems that Wireless Sensor Networks (WSNs) research will have to address in order to ensure a reasonable degree of cost and system quality. Cluster formation and cluster head selection are important problems in WSN applications and can drastically affect the net- work's communication energy dissipation. However, selecting of the cluster head is not easy in different environments which may have different characteristics. In this paper, in order to deal with this problem, the authors propose a power reduction algorithm for WSNs based on Fuzzy Logic (FL) and Number of Neighbour Nodes (3N). They call this system F3N. The authors evaluate F3N and LEACH by many simulation results. The performance of F3N system is evaluated for tree different parameters: Remaining Battery Power of Sensor (RPS); Degree of Number of Neighbour Nodes (D3N); and Distance from Cluster Centroid (DCC). From the simulation results, they found that the probability of a sensor node to be a cluster head is increased with increase of number of neighbour nodes and remained battery power and is decreased with the increase of distance from the cluster centroid.
Decision Method of Optimal Investment Enterprise Selection under Uncertain Information Environment
Authors: Liao Xiaoyong
Published: April 2015

To select an optimal investment enterprise is the key to effectively reduce the investment risk for an investment company. In this paper, the author studies the problem of optimal investment enterprise selection decision under uncertain information environment (fuzzy information and grey information coexist), and present a fuzzy grey multi-attribute group decision making model to select the optimal investment enterprise. In this model, the author defines the concept and operations of fuzzy grey number, and present a ranking method based on fuzzy grey deviation degree to rank the alternative investment enterprises. The author also gives an application example of selecting optimal investment enterprise to highlight the implementation, availability, and feasibility of the proposed decision making model.
Chance Single Sampling Plan for Variables
Authors: Sundaram Sampath , Madhavachari Lalitha Singhan , Balu Ramya
Published: April 2015

This paper considers the design of single sampling plan for variables when the experimental values are treated as observations on independently and identically distributed normal random variables with fuzzy mean value. The design makes use of Liu's (2008) model IV of Chance Theory. Sampling Plans determined by the sample sizes and acceptance numbers are constructed for situations involving imprecise parameter on using chance theory. The process of determining sample sizes and acceptance threshold values has been carried out on assuming the observed values have hybrid normal distribution. Optimal chance sampling plans for variables are also determined by using minimum angle criterion for different choices of fuzzy risks.
Investigation of the Effect of Cutting Conditions and Tool Edge Radius on Micromachining with the Use of the Finite Elements Method
Authors: Markopoulos Angelos P. , Hadjicostas Christos , Manolakos Dimitrios E.
Published: April 2015

Micromachining comprises manufacturing processes that are in the forefront of contemporary industry. The need for high efficiency, high precision, better quality and lower cost makes the study of these processes and the phenomena of the micro regime that accompany, e.g. the size effect, of great importance. The quite popular for modeling manufacturing processes Finite Element Method is applicable in micromachining, too. However, assumptions and simplifications need to be made in order to provide a realistic simulation. In the present paper a numerical simulation using the Third Wave AdvantEdge® software is presented. A FEM model of micromachining of AISI 1045 is used for a parametric analysis of the simulation of micro-cutting. The effect of cutting conditions and tool geometry are investigated and size-effect theories are tested with the aid of the numerical model. From the analysis several useful conclusions are drawn.
Model-Based Exploration of Societal Aging in the Netherlands
Authors: Pruyt Erik , Logtens Tom
Published: April 2015

Mismanagement of societal aging is an important threat to health care, social security, and the economy of many nations. A System Dynamics simulation model related to societal aging in the Netherlands and its implications for the Dutch welfare system is used here to generate exploratory scenarios and to test policy robustness across many scenarios. Key concerns derived from this research are (i) the existence of plausible scenarios with severe labor scarcity, especially in health care, (ii) unsustainable evolutions of health care costs, and (iii) insufficient labor productivity, especially in health care. The authors' analysis shows that labor productivity may be cause of, and cure for, many of undesirable evolutions. The authors conclude that there is a need for: (i) sufficient increases in labor productivity, especially in health care, without pinching the necessary workers in care, and (ii) sufficiently raising the retirement age as well as raising the willingness to work longer and to employ older people. These conclusions are derived from the systematic data analysis documented in the appendix.
Appraisal and Mental Contents in Human-Technology Interaction
Authors: Saariluoma Pertti , Jokinen Jussi P.P.
Published: April 2015

User experience has become a key concept in investigating human-technology interaction. Therefore it has become essential to consider how user experience can be explicated using psychological concepts. Emotion has been widely considered to be an important dimension of user experience, and one obvious link between modern psychology and the analysis of user experience assumes the analysis of emotion in interaction processes. In this paper, the focus is on the relationship between action types and elicited emotional patterns. In three experiments including N = 40 participants each, it is demonstrated that the types of emotions experienced when people evaluate and use technical artefacts differ based on the stances they take toward these artefacts. One cannot approach user experience irrespective of the careful analysis of the situation-specific emotional themes. It is essential to any theory of user experience to consider the nature of the situation and relevant actions.
Effect of Ammonium Polyacrylate and Pre-Oxidation on Rheological Properties of Si3N4 Slurries
Authors: Cheng Chuan Bing , Fan Run Hua , Yan Ke Lan , Sun Kai , Li Qian Qian , Hou Qing , Liu Gui Fang , Xie Pei Tao
Published: April 2015

The key for gel-casting is the preparation of ceramic aqueous slurries with excellent rheological properties. The effect of ammonium polyacrylate and pre-oxidation on rheological properties of Si3N4 slurries was investigated. The Si3N4 isoelectric point (IEP) is between 3 and 4 in premix solution and particle surface potential is maximum at pH between 9.5 and 10.5. PAA-NH4 of dispersant can obviously decrease the viscosity of Si3N4 slurries, and the optimal dosage is about 1.6wt% of Si3N4 powders. Meanwhile, the Si3N4 slurries exhibit pseudoplastic fluid with the characteristic of shear-thinning behavior. Due to the improvement of powder surface characteristic, the pre-oxidation significantly improve the rheological properties of the Si3N4 slurries.
Double Negative Property in Co/YIG Prepared by Low Temperature Impregnation Process
Authors: Wang Xu Ai , Fan Run Hua , Shi Zhi Cheng , Chen Min , Yan Ke Lan , Sun Kai , Hou Qing , Zhang Zi Dong , Qian Lei
Published: April 2015

Impregnation method was used for fabricating Co/YIG (Y3Fe5O12) composites under low temperature, and the electromagnetic properties were tuned by adjusting the content (0 wt% - 35 wt%) and microstructure of the metal in composites. The XRD and SEM were used to analyze the phase and microstructure. Electromagnetism properties including reactance, permittivity and permeability of the composites were tested using impedance analyzer (10 MHz~1 GHz). The results indicated that, the high cobalt content leads to the formation of three-dimensional cobalt networks on the pore walls of porous YIG gradually, and their electromagnetic properties have also been changed significantly with the Co content increasing. Especially, double negative properties were achieved in Co/YIG composites when the content of Co reached 35 wt% at the frequency band of 575 MHz-1 GHz. The appearance of double negative properties in cermets provides promising applications in electromagnetic stealth materials, microwave antenna, and traveling wave tubes.
Tunable Electromagnetic Properties of Yttrium Iron Garnet Ceramics
Authors: Wang Xu Ai , Fan Run Hua , Shi Zhi Cheng , Chen Min , Yan Ke Lan , Sun Kai , Hou Qing , Zhang Zi Dong , Qian Lei
Published: April 2015

Different porosity Y3Fe5O12 (YIG) ceramics (32% - 62%) were prepared from ceramic powders, which was synthesised by high temperature solid-phase reactions, and the effects of porosity on their electromagnetic properties were investigated. XRD and SEM were used to analyze the phase composition and microstructure of the porous composites. Electromagnetism properties including alternate current conductivity, permittivity and permeability of the composites were tested by HP4991 impedance analyzer (10 MHz~1 GHz). The results indicated that, the porosity and pore diameter were increasing with the addition of pore former by pressureless sintering; the real permeability and permittivity of YIG ceramic decreased when the porosity increasing, at the same time, the peaks of magnetic loss were moved to high frequency. That is to say, the electromagnetism properties of YIG ceramic composites could be adjusted by its porosity. Yttrium iron garnet ceramic can be widely used for high frequency devices due to its excellent and tunable magnetic properties.
Preparation of Cf/HfC Composite by Reactive MeltInfiltration Using Hf-Based Alloy
Authors: Yang Zhen Huan , Zhang Hong , Ye Yi Cong
Published: April 2015

A HfZrSiTa alloy of low melting point was designed by phase diagram calculation and smelted. The Cf/HfC composite was then prepared by reactive melt infiltration at relative low temperature. The open porosity of specimen was 8.45%. By SEM, XRD and EDS, it was found that the melt infiltration microstructure mainly consists of HfC, ZrC, Hf2Si, Zr2Si phases and a small amount of Hf, Zr phases. The as-received Cf/HfC composite, with the flexural strength of 165 MPa, displayed a typical brittle fracture behavior. Ablation properties of the Cf/HfC composite were tested by an oxyacetylene flame. The linear ablation rate was 0.03 mm/s. An oxide barrier layer was formed on the ablation surface and the ablation resistance of the composite has been largely improved.
Preparation of Diamond Coatings on Alumina by Hot Filament Chemical Vapor Deposition
Authors: Li Jun Sheng , Huang Chao , Luo Hao , Wei Qiu Ping , Zhou Yong Jiang , Tong Si Cao
Published: April 2015

Diamond coatings were prepared on alumina by hot filament chemical vapor deposition, which constituted an insulator used in a laser pump. The composition and morphologies of the diamond coatings were characterized by Raman spectra and scanning electron microscope. The effects of the pressure of the deposition chamber and the distance from the filament to the base on the composition and structure of the deposited diamond coatings were studied.
Anomalous Strain Rate Sensitivity of Nanocrystalline Ni Induced by Rolling Deformation
Authors: Cao Z.H. , Meng Xiang Kang
Published: April 2015

The strain rate sensitivity of rolled nanocrystalline (NC) Ni was studied by nanoindentation. The grain continuously grows from 20 nm to 92 nm after rolling deformation. The stress driven grain boundary migration accompanied by dislocation emission leads to the grain growth. The strain sensitivity first increase and then decrease with the increased rolling strain, which has a similar variation of dislocation density in rolled NC Ni. The remarkable shift of rate sensitivity is attributed to the dislocation supported grain boundary mediated process.
Influence of Ethyl Acetoacetate on the Structure and Thermal Stability of Alumina Aerogel
Authors: Xu Lin , Jiang Yong Gang , Feng Jun Zong , Feng Jian
Published: April 2015

Alumina aerogels were prepared from aluminum sect-butoxide via sol-gel process and supercritical drying. The influence of Ethyl acetoacetate (Etac) on the aerogel properties, microstructure, and thermal stability was systematically studied. At the same time, reaction mechanism was also investigated. The results show that, without and with Etac addition, the alumina aerogels are consisted of crystalline boehmite and amorphous network, respectively. When nEtac/nAl molar ratio is 0.01~0.15:1, Al2O3 aerogels have larger surface area (71~98 m2/g) than pure alumina aerogel (61m2/g) after heated at 1200°C, a proper ratio of Etac is helpful to increases the gelation time and stability of alumina sol, and is useful to improve the thermal stability of Al2O3 aerogels.
Failure Mechanism of 7YSZ Splat as Thermal Barrier Coating
Authors: Zhang Xiao Feng , Zhou Ke Song , Xiao Xiao Ling , Liu Min
Published: April 2015

An investigation of spallation behaviors of plasma-sprayed ZrO2-7wt.%Y2O3 (7YSZ) splat at high temperature was carried out to understand the failure mechanism of thermal barrier coating (TBC). In present work, 7YSZ splats prepared by atmospheric plasma spray (APS) were collected on mirror polished NiCoCrAlYTa bond coating holding at 250 °C, where the nickel base superalloy K4169 was used as substrate. Then the samples with splats were taken into air furnace for isothermal oxidation test at 900 °C for different time. The surface of splat and cross section of splat-bond coating interface during isothermal test were characterized using a focused ion beam (FIB) assisted field emission scanning electron microscope (FE-SEM). Besides, the compositions of thermally grown oxide (TGO) layer at splat-bond coating interface were analyzed after oxidation test. In addition, the schematic diagram of spallation process and oxidation model of splat has been presented at relatively high temperature.
Influence of Small Amounts of Si and Al on the Synthesis of Ti3SiC2 by Spark Plasma Sintering
Authors: Dong Hong Ying , Zhu Li Wei , Tian Xin , Jin Xi Long , Bai Yu , Ma Wen
Published: April 2015

Ti/Si/C element powders were used to synthesize Ti3SiC2 by spark plasma sintering. The synthesized products consisted of Ti3SiC2, together with TiC and Ti5Si3 as impurities. The addition of Al, excess Si, and appropriate sintering temperature increased the purity of Ti3SiC2 in the products. From the 3Ti/1.2Si/2C/0.2Al mixture, Ti3SiC2 with the purity 99 mass % was synthesized at 1300 °C for 5 min at 30 MPa.
Thermophysical Properties of (Sm1-xNdx)2Ce2O7 Ceramic Oxides
Authors: Chen Xiao Ge , Wei Yuan , Zhang Xian Ping , Zhang Hong Song
Published: April 2015

(Sm1-xNdx)2Ce2O7 ceramics was synthesized by solid reaction method at 1873K for 10h in the present investigation. The density, phase structure, thermal conductivity and thermal expansion coefficient of (Sm1-xNdx)2Ce2O7 ceramics were studied by the Archimedes method, X-ray diffraction (XRD), laser-flash and pushing rod. The (Sm1-xNdx)2Ce2O7 ceramics have pure fluorite-structure. The thermal conductivity of (Sm1-xNdx)2Ce2O7 ceramics decreased with an increase of Nd2O3 content at identical temperature conditions, and the thermal expansion coefficient increased with increasing Nd-doping content. The synthesized (Sm1-xNdx)2Ce2O7 ceramics can be explored as an ideal candidate material for future thermal barrier coatings.
Microstructure and Properties of AlSn20 Coating Deposited via Magnetron Sputtering
Authors: Guo Qiao Qin , Li Jian Ping
Published: April 2015

In view of the present reality of sputtered plating bearings imported in our country, unbalanced magnetron sputtering deposition techniques was used to fabricate AlSn20 anti-friction coating on aluminum bearing alloy. Microstructure characterization of the coating was performed by SEM. Micro-hardness testing of Coating were measured with a Vickers indenter. Adhesion testing was carried out with a scratch tester. Wear and friction tests were performed with a pin-on-disc tribometer. The results revealed that the AlSn20 anti-friction coating (bias voltage in the range of-60V~-100V) showed finer crystal, better corrosion resistance (Ecorr=-1.25V), higher hardness (up to 80HV0.025), better adhesion with substrate (up to 35N), and lower friction coefficients down to 0.15.
Effect of Annealing Time on the Microstructure and Mechanical Properties of the AlCrFeNi2Ti0.5 High Entropy Alloys
Authors: Jiang Li , Jiang Hui , Lu Yi Ping , Han Jing Yu , Cao Zhi Qiang , Wang Tong Min , Li Ting Ju
Published: April 2015

As-cast AlCrFeNi2Ti0.5 high entropy alloy was annealed at 600 °C and 800 °C for 6 h, 12 h and 24 h, respectively. The effect of annealing time on the microstructure and mechanical properties were investigated intensively. The as-cast sample showed a fine and homogeneous microstructure, and owned an excellent ductility of 16.3%. While the 600 °C, 12 h annealed sample showed the highest compressive strength of 2658 MPa and yield strength of 2046 MPa. The mechanical properties of the samples after 800 °C annealed for 12 h and 24 h deteriorated obviously. High annealing temperature promotes the growth of the crystal grains, and the new generated FeCr-type intermetallic phase leads to the embrittlement of the alloy.
Effects of Quenching Rate on the Microstructures and Mechanical Properties of the Heat Treatable Mg-4.2Y-2.3Nd-1.0Gd-0.6Zr Magnesium Alloy
Authors: Kang Y.H. , Wu D. , Chen Rongshi , Han En-Hou
Published: April 2015

The effects of quenching rate on the microstructures and mechanical properties of the heat treatable Mg-4.2Y-2.3Nd-1.0Gd-0.6Zr (wt.%) (WE43) sand-cast alloy have been studied using a combination of mechanical testing, Vickers hardness testing, optical microscopy (OM) and scanning electron microscope (SEM). Two quenching conditions, either air quenching or 60°C water quenching, were employed. The results indicate that some precipitates have formed in the matrix and grain boundaries in the air-quenched solutionized alloy. And the Vickers hardness and yield strength (YS) is HV77 and 155 MPa, respectively, which is slightly more than the 60°C water-quenched solutionized alloy. However, the ultimate tensile strength (UTS) and yield strength (YS) of the peak-aged at 250°C (T6) of the two quenching conditions are both 273 MPa and 212 MPa, respectively. And they have similar age hardening curves at 250°C and the T6 microstructure. So the results indicate that in this work of quenching rate range WE43 alloy has few quench sensitivity effect.
Grain Refining Behavior of Zr, Al2Y and Al4C3  Particles in Magnesium Alloys by the First-Principles Calculations
Authors: Pan Jun Ling , Peng Qiu Ming , Guo Jian Xin , Li Hui
Published: April 2015

Grain refining is one of the most important issues in the applications of Mg alloys, which directly determines mechanical properties and deformability. Therefore the understanding of grain refining mechanism during solidification will be benefit to develop new grain refiners. Herein refining role was elucidated by the first principles calculations based on adsorption behavior of a Mg atom on the closest-packed planes of grain refiners (Zr (001), Al2Y(311) and Al4C3(102)). Taking into account different sites, the site with the maximum adsorption energy value generally corresponded to the most possible location. The adsorption energy results show that the possible refining turn follows Al4C3(102)>Zr (001)>Al2Y(311). Meanwhile, the structural optimization confirmed that the Mg atom connected with two C atoms on the top of zig-zag plane of Al4C3(102), three Zr atoms at the hcp position on Zr (001), and two Y atoms and one Al atom at the bottom of zig-zag plane of Al2Y(311). The density of states revealed that the variation of d-orbital electrons of Mg atom became apparent during adsorption process. The values of Mulliken charges were 0.898 e in Al4C3(102), 0.410 e in Zr (001) and 0.245 e in Al2Y(311), respectively. This tendency agrees well with the previous experimental results. It indicates the adsorption energy on the closest-packed planes can be regarded as a prerequisite to select new grain refiners for Mg alloys in future.
Influences of Tensile Temperature on the Mechanical Properties of Rolled Mg-Zn-Gd Sheets with Non-Basal Texture
Authors: Yan H. , Chen R.S. , Han En-Hou
Published: April 2015

Mg-2.0Zn-xGd sheets with non-basal texture were fabricated by common rolling process, which showed excellent ductility and formability at room temperature. In this paper, tensile tests were carried out at moderate temperature along the rolling direction and transverse direction to evaluate the influences of tensile temperature on mechanical properties and formability of the sheet. The microstructural evolution during tensile deformation was also investigated to analysis deformation mechanisms. The results showed that the elongation of the sheets increased from 57% at 373K to 253% at 573°C along the rolling direction, while the yield strength decreased with the increase of tensile temperature. The microstructure observation indicated that twining was one of the deformation modes and no dynamic recrytallization took place during deformation at 373K. With temperature increasing up to 473K, dynamic recrystallization took place and led to finer microstructure. This suggests that the formability of the Mg-Zn-Gd sheets with high ductility at room temperature could be further improved by increasing temperature up to 473K, which could refine the microstructure leading to higher strength during second forming process.
Investigation on the Compound Phosphate Film Formed in Bath with Cerium Salts on the Magnesium Aluminum Alloy
Authors: Niu Li Yuan , Chang Shiuan Ho , Lin Ji Xing , Su Yi Chang , Li Guang Yu
Published: April 2015

A composite phosphate film was formed on magnesium aluminum (Mg-Al) alloy which was impregnated in phosphating solution containing phosphate, cerium salt, organic ammonium and corrosion inhibitor. The sample was examined by scanning electron microscope (SEM), X-ray diffraction (XRD), and Energy Dispersive Spectrometer (EDS) to analyze the organization and structure of the film. Additionally, the corrosion resistance of the film of composite phosphate was also investigated by salt spray test. As a result, it shows that the components of the film formed on Mg-Al alloy contain phosphates and elemental zinc. On the other hand, the composite phosphate film possessing photo-absorption property can be used for protective layer and laser pretreatment of Mg-Al alloy.
Microstructural Evolution and Mechanical Behavior of AZ31 Magnesium Alloy Sheets with Li Addition
Authors: Yang Qing Shan , Jiang Bin , Jiang Wei , Song Bo , Luo Su Qing , Pan Fu Sheng
Published: April 2015

AZ31 magnesium alloy and its alloy with 5% lithium were extruded to 1mm in thickness sheets at 380 oC with extrusion ratio of 101. Microstructure evolution and mechanical behavior of the extruded Mg alloy sheets were examined. The microstructure and texture evolution were investigate by electronic backscattered diffraction (EBSD) and X-ray diffraction (XRD). Mechanical performance was carried out by tensile tests at room temperature. In addition, the evolution of neutral layer and microstructure was also examined by V-bending. It was found that Li addition resulted in the strong divergence of the grain orientation. (0002) basal texture of AZ31 alloy sheets with 5% lithium has been weakened. The room temperature ductility of these textural sheets was enhanced owing to the tilted weak basal texture. Moreover, it exhibits superior ductility during V-bending process at room temperature.
Microstructure of Directionally Solidified Mg-Zn Alloy with Different Growth Rates
Authors: Jia Hong Min , Feng Xiaohui , Yang Yuan Sheng
Published: April 2015

The influence of withdrawal rate on the microstructure of directionally solidified Mg-x%Zn (x=2, 4, 6) alloys was investigated in this paper. It was found that with the withdrawal rates increased from 20 μm/s to 60 μm/s, the morphology of the solid-liquid interface changed from planer to cellular dendrite. When the growth rate was further increased to 120 μm/s, the solidification microstructure appeared to be the typical dendrite structure with the developed secondary dendrite arms. Meanwhile, the dendrite arm spacing decreased with the increase of growth rate. Under the same solidification conditions, the microstructure went through cell branch transformation with the increase of Zn content within a lower withdrawal rate range; while the Zn content did not affect the morphology at a higher withdrawal rate. As well, the microstructure was refined gradually with the increase of Zn content. The effects of withdrawal rate and alloying content on morphology were analyzed by constitutional supercooling and the MS theory.
Effect of Additional Shear Stress on Microstructure Evolution of AZ31 Sheet by Differential Speed Rolling
Authors: Shen Yu Teng , Ou Xin Ran , Chen Ze Jun
Published: April 2015

Asymmetric rolling of deformed magnesium alloys sheet can accelerate refine the grain size, reduce the basal texture, and improve the subsequent formability. This happens because the additional shear stress and strain are introduced during the differential speed rolling. This paper investigates the relationship of shear stress and microstructure evolution by the experiment in conjunction with the FEM (Finite Element Method) simulation. The differential speed ratio (1, 1.2 and 1.5) and rolling reduction (8% and 15%) were executed at room temperature. The additional shear strain field is simulated for corresponding asymmetric rolling conditions. The results showed that the additional shear stress and strain were the essential influence factors of microstructure evolution and formability of AZ31 sheet for the differential speed rolling. It is helpful in enhancing and improving the formability of rolled magnesium alloys.
Microstructures and Mechanical Properties of Extruded High-Purity Magnesium
Authors: Feng Xiaohui , Jia Hong Min , Luo Tian Jiao , Liu Yun Teng , Zhou Ji Xue , Li Yang De , Li Wei Rong , Yang Yuan Sheng
Published: April 2015

The microstructure and mechanical properties of the high-purity magnesium (99.99wt.% Mg) extruded by single direct extrusion experiment were investigated. For the extrusion speed of 0.2mm/s, the microstructure of extruded Mg rods was composed of equiaxed fine dynamical recrystallized (DRXed) grains and some elongated coarse un-DRXed grains. The yield strength (YS) and the elongation of the extruded bars were 105.3MPa and 46.7% respectively. In the case of extrusion speed of 4.0mm/s, the DRXed grains were remarkably coarsened and the elongated coarse un-DRXed grains vanished, meanwhile lots of twins occurred and the intensity of basal-plane texture increased a little. With the extrusion speed being raised from 0.2mm/s to 4.0mm/s, the YS and the elongation decreased to 60.5MPa and 22.1% respectively, but the ultimate tensile strength (UTS) was improved from 154.7MPa to 178.8MPa.