bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Faces of Mobile Shopping
Authors: Lee Thaemin , Park Cheol , Jun Jongkun
Published: June 2017

This study examines the positive and negative effects of mobile shopping. It identifies and tests the antecedents and consequences of self-efficacy and impulse buying that result from mobile shopping. The results reveal that perceived convenience, perceived ease of response, and perceived control significantly affect self-efficacy and impulse buying. In addition, the results demonstrate that significant relationships exist between self-efficacy and satisfaction, and impulse buying and regret. Further, the study identifies significant moderating effects of consumer knowledge on casual relationships that exist between some variables. Based on these results, this paper provides a discussion of the implications of this research and offers suggestions for further research.
Comparative Study Among New Payment Systems and New Future Trends in Mobile Payments
Authors: Liébana-Cabanillas Francisco J. , Muñoz-Leiva Francisco , Sánchez-Fernández Juan
Published: June 2017

Over the last few years, the payment systems used in business activities have been altered by recent technological developments. Increasingly, more consumers use their mobile phones to do their purchases. Currently, sales through smartphones are an indicator of the growth potential that these new trade and payment methods have in the future society. In this chapter, the authors carry out a theoretical review of the different payment systems, from the most traditional ones to the new payment systems used on the Internet. They also analyze the different security protocols that are currently operational, with the aim of improving consumers' trust. In this literature review, the authors extract a few implications and recommendations to management of M-Payment-based businesses.
Scientific Information Superhighway vs. Scientific Information Backroads in Computer Science
Authors: Cipolla-Ficarra Francisco V. , Nilson Donald , Alma Jacqueline
Published: June 2017

In the current appendix present a first heuristic study about the scientific publications related to computer science and the human factors that make that some contents travel through highways and others in back roads of scientific information. We also present the first elements which generate that parallel information of the scientific work for financial and/or commercial reasons. Finally, a set of rhetoric questions link two decades of experiences in the university educational context, research and development (R&D) and Transfer of Technology (TOT) in the Mediterranean South and make up a first evaluation guide.
Open and Distance Learning for Sustainable Development in Bangladesh
Authors: Jahan Monira , Arif-Uz-Zaman Md. , Hossain A. N. M. Tofail , Akhter Shamima
Published: June 2017

Bangladesh Open University (BOU) is considered as a Mega University for its continuous growth over the last two decades. The modus operandi of education makes BOU distinct from other traditional universities. In Bangladesh this is the first and only university that adopts Open and Distance Learning (ODL) as a mode of delivery. From its inception, BOU has taken several initiatives for the development of ODL in Bangladesh. The main intention of such initiatives is to contribute national development. The success and sustainability of any organization largely depends on its management capacity to cope with the rapid world-wide change, which is also true for BOU. To evaluate the role of BOU in sustainable development, this chapter outlines the achievements of BOU and challenges that it is facing in delivering effective ODL. This chapter also discusses the origins and meaning of the term “sustainability” and strategies that should be taken into consideration to ensure sustainable ODL, which can provide a framework for its successful implementation linking BOU's contribution to sustainable development.
Involving Diverse Stakeholders for Sustainable Development
Authors: Dobrowolski Jan , Kobylarczyk Justyna , Wagner Aleksandra L. , Mazur Robert
Published: June 2017

The rich pool of tacit knowledge in the minds of a diverse set of stakeholders is a crucial asset for exploring the solutions of Sustainable Development. The education for Sustainable Development can therefore be carried out as an interactive exercise between the stakeholders rather than a one-way flow of knowledge in the conventional class rooms. It calls for paradigmatically new ways of education for addressing the issues of Sustainable Development. The generating of knowledge, its dissemination and devising solutions for Sustainable Development have to go hand in hand. With this perspective in mind the Polish scholars focused on organising workshops for the stakeholders of diverse backgrounds for synthesising, documenting and further devising solutions for Sustainable Development on the basis of their knowledge. Some activities were also focused on social participation which included the residents of the analysed areas.
Open and Distance Learning in India
Authors: Mathur Anshu , Jha Arbind K.
Published: June 2017

Rise of Open and Distance Learning (ODL) systems in India is largely a 20th century phenomenon. The ODL systems have taken up responsibilities to identify the educational needs of diverse segments of people and accordingly plan innovative and flexible systems to meet their requirements. Though ODL systems have been on the priority of the Governments in India for a long time, Post 2015 Development Agenda of United Nations has given a renewed policy thrust for it. Despite their tremendous potential to address the problems in Indian Higher Education, the functioning of ODL systems is constrained by low reach of technology, poor infrastructure and sharp socioeconomic, linguistic and cultural variations in targeted areas. This chapter gives an account of gaps in theory and practices of Open and Distance Learning systems. Recommendations have been made to optimise the practice of ODL to suit Indian context. Existing research studies have been put in to perspective and recommendations have been made for practitioners of Open and Distance Learning systems.
Revisiting Urban Theories
Authors: Benna Umar , Benna Indo
Published: June 2017

Urban theory has been dominated by the accumulation of social theories and has significant impact on global urbanization. The urban is becoming more complex and more global due to the contesting technological, political, social, economic and environmental forces. These disciplinary forces may be added to the global shifts in population and political power from rural to urban and from the developed to the developing nations, creating new global challenges. To cope with these challenges, the prevailing urban theories need a shift. By critically revisiting urban theories and testing them against emerging challenges, this chapter is advocating for and pointing to a new direction. The chapter revisits urban sociological theories, those global theories advocating planetary urbanization, the models responding to glocal forces as well as those promoting world systems. This is followed by an outline of the proposal for Activity Theoretical Framework. Possible future research direction for the inclusive and universal urbanization is identified.
Urbanization and Socio-Economic Growth in South Asia Region
Authors: Chandiramani Jyoti , Airy Aanchal
Published: June 2017

Urbanization in the South Asia Region (SAR) stood at 34% (2014) and is relatively sluggish when compared to that of the World at 54%. The World Urbanization Prospects (2014) and World Bank Report (2016) reveals that the future urbanization globally will be concentrated in Asia and predominantly in the select countries of SAR - Bangladesh, India and Pakistan. The chapter analyses the demographic and socio-economic characteristics of the select countries, which are indicative of the quality of life of citizens, benchmarking it with that of Asia and the world. The analysis reveals the slow, messy and hidden nature of urbanization in the region which is required to be addressed. The conclusions recommend large investment and policy imperatives which should bring about sustainable urbanization ensuring basic urban services resulting in improved demographics, Human Development Indices and other socio-economic characteristics of the people in the region.
Social Costs and Benefits of the Transformation of the Traditional Families in an African Urban Society
Authors: Chirisa Innocent , Mukarwi Liaison , Matamanda Abraham Rajab
Published: June 2017

This chapter analysed the social costs and benefits of changing lifestyles and livelihoods adopted by the families in Africa to fit in the obtaining urban environments. The transformation is in a way to minimise the cost and maximise the benefits of urbanism. The net overall effect of the transformation has been increasing household poverty signified by poor incomes, family instability, increased nucleation of families and disbanding of family rural ties for the city. In most cases, this means increased vulnerability and insecurity of the traditional family. How then do the urbanised traditional families cope with city pressures? The study draws cases from South Africa, Mozambique, Zimbabwe, Nigeria, Ethiopia and Egypt these being countries where urbanisation levels are in critical variation due to varying circumstances including the removal of apartheid restrictions, armed conflict, economic instability, population explosion, existence of pristine conditions, possibility of overurbanisation and proclivity to maintaining tradition, respectively.
Urbanization and New Jobs Creation in Healthcare Services in India
Authors: Medhekar Anita , Haq Farooq
Published: June 2017

Urbanization in developing countries of Asia, Africa, and India is growing at an unprecedented rate. For the last three decades, urbanization has led to migration and concentration of population in urban cities and put pressure on public infrastructure, health, education, and transportation due to population growth. This has caused disparities between the elite and urban-poor in India in terms of shortage of human resources in the public health system, new job creation in the healthcare sector and medical tourism in India in particular and Asian economies engaged in global medical travel business of catering to local and foreign patients. The main contribution of this chapter is to critically discuss the opportunities and challenges faced by public and private hospitals for new job creation in healthcare, due to urbanization and emergence of corporate private hospitals that export health care services in India, followed by policy implications, future research directions, and conclusion.
Construction Site Communication Study Using the RAM Management System for BIM Adaptation
Authors: Shrahily Raid Yahia , Medjdoub Benachir , Klalib Hynda Aoun , Chalal Moulay Larbi
Published: June 2017

The UK's construction industry is witnessing an annual increase in costs due to a lack of communication between the different organizational operators on the construction site that often leads to construction defects. Meanwhile, a cost-reduction strategy plan using BIM has become a fundamental requirement for the government, aiming to keep costs under control. To facilitate BIM adoption in the industry, the BIM strategy was introduced in four phases, with each stage entailing a number of criteria. The industry has seen a global reaction to the Level 2 BIM program and a significant cost saving of 840M in 2013/14 in Europe. However, the industry is unable to match the level 3 BIM, where a collaborative model file server is required as a common sharable platform to achieve efficient communication. This study contributes toward formulating a communication framework in the UK industry to understand communication issues and manage defects. A survey was targeted at construction industry practitioners and academics, with a total number of 328 participants.
Configuring a Trusted Cloud Service Model for Smart City Exploration Using Hybrid Intelligence
Authors: Sarkar Manash , Banerjee Soumya , Badr Youakim , Sangaiah Arun Kumar
Published: June 2017

Emerging research concerns about the authenticated cloud service with high performance of security and assuring trust for distributed clients in a smart city. Cloud services are deployed by the third-party or web-based service providers. Thus, security and trust would be considered for every layer of cloud architecture. The principle objective of cloud service providers is to deliver better services with assurance of trust about clients' information. Cloud's users recurrently face different security challenges about the use of sharable resources. It is really difficult for Cloud Service Provider for adapting varieties of security policies to sustain their enterprises' goodwill. To make an optimistic decision that would be better suitable to provide a trusted cloud service for users' in smart city. Statistical method known as Multivariate Normal Distribution is used to select different attributes of different security entities for developing the proposed model. Finally, fuzzy multi objective decision making and Bio-Inspired Bat algorithm are applied to achieve the objective.
Unsupervised Segmentation of Remote Sensing Images using FD Based Texture Analysis Model and ISODATA
Authors: Hemalatha S. , Anouncia S. Margret
Published: June 2017

In this paper, an unsupervised segmentation methodology is proposed for remotely sensed images by using Fractional Differential (FD) based texture analysis model and Iterative Self-Organizing Data Analysis Technique Algorithm (ISODATA). Essentially, image segmentation is used to assign unique class labels to different regions of an image. In this work, it is transformed into texture segmentation by signifying each class label as a unique texture class. The FD based texture analysis model is suggested for texture feature extraction from images and ISODATA is used for segmentation. The proposed methodology was first implemented on artificial target images and then on remote sensing images from Google Earth. The results of the proposed methodology are compared with those of the other texture analysis methods such as LBP (Local Binary Pattern) and NBP (Neighbors based Binary Pattern) by visual inspection as well as using classification measures derived from confusion matrix. It is justified that the proposed methodology outperforms LBP and NBP methods.
New Approach of Diagnosis by Timed Automata
Authors: Azzabi Olfa , Ben Njima Chakib , Messaoud Hassani
Published: June 2017

The Discrete Event Systems (DES) is a nonlinear dynamic system with discrete state and event evolution. In this article, we are interested in the diagnosis of failures with Timed Automata. The proposed approach is based on the operating time and it is applicable to any system whose dynamic evolution depends not only on the order of discrete events but also on their periods as in industrial processes. The most important part of this work is the construction of a diagnoser which uses observables events to detect and locate the faults. We present on the last part of this work results of the study of the performance of the diagnosis showing the power of this diagnostic approach. An implementation on a hydraulic system is made to illustrate the proposed steps. It put in evidence the effectiveness of this approach. The model of the simulation phase is done using Matlab / Simulink / stateflow.
Social Education Institution a Way to Achieve Sustainable Education in Remote Areas
Authors: Dhiba Sintia Farach , Prastiti Destyana Cory
Published: June 2017

This research aims to discover the effort of accomplishing Sustainable Development Goals in developing country. Adopting qualitative method and case study approach, this research held in Bajulmati, Indonesia. The result of this research shows that social education institution establishment by society in remote area can answer the problems to reach Sustainable Development Goals. The establishment process is begun by the external party in remote area to provide medium to discuss problem. The first stage of Sustainable Development Goals accomplishment is attained by implementing Sustainable Education by giving long-live learning education for children and training for adult. The second stage is making Sustainable Economic around society by making business from the potential resources. After doing sustainable education and economic, it can achieve Sustainable Development Goals. In this study, it will figure out that social education institution in Bajulmati can be an example for another remote area to achieve Sustainable Development Goals.
Towards the Implementation of Optimal Train Loading Plan in the Athens-Thessaloniki Freight Services
Authors: Ballis Athanasios , Karapetis Fillipos , Ballis Theocharis
Published: June 2017

The main goal of train loading optimization is the proper assignment of loading units onto the wagons, taking under consideration numerous factors like the maximum axle load restrictions, the condition of the railway infrastructure, the operating conditions, safety regulations etc. The typical expression of the problem is usually formulated under one of the two following assumptions: (a) the commodity load is predefined or (b) the number and type of wagons is fixed. The current work describes the steps that were followed and enabled the analysis, optimization and integration of the train loading plan into the information system that supports the new railway service of TRAINOSE for containers transport on the Athens – Thessaloniki line. This new service, named iCS, was launched in December 2013 and ever since operates on a daily basis. The work includes a literature review, a mention of the pragmatic aspects that influence container transport and train loading plan, the presentation of the heuristic which is implemented in the information system of iCS service, a validation process against a mixed integer optimization model and finally concludes with the proposed solution for the iCS wagon loading problem.
Ciência moderna em Portugal: a ‘aula da esfera’ no colégio de Santo Antão
Authors: Oliveira Natália Cristina de , Costa Célio Juvenal , Menezes Sezinando Luiz
Published: June 2017

Com a chegada da Companhia de Jesus a Portugal, em 1540, passam a ser criados pela Coroa os colégios jesuíticos. O Colégio de Santo Antão, em Lisboa, foi a primeira instituição educacional dos jesuítas, criado em 1553. Propomos uma discussão dos principais objetivos, das características e das dificuldades da ordem religiosa jesuítica no território português, bem como uma apresentação de uma das aulas mais importantes desse Colégio: a ‘Aula da Esfera’. Os padres consideravam fundamental o ensino naquele Colégio de questões relacionadas à matemática e à astronomia, pois, por meio dessas disciplinas, abordavam a teoria e a prática de itens e de conceitos, como o telescópio, os logaritmos, as equações, a geometria, entre outras. As grades curriculares desse centro de ensino incluíam, além das Ciências e Matemática, disciplinas como: Latim, Gramática, Humanidades, Retórica e introduções à Teologia Moral, à Teologia Dogmática e à Filosofia, consideradas únicas ao ensino no contexto português. Estudar o Colégio de Santo Antão ajuda-nos também a compreender como eram consideradas essas inovações no ensino, no caso jesuítico, na conjuntura temporal de Portugal no século XVI. Entendemos que o Colégio, principalmente pelas inovações, foi essencial para o desenvolvimento da ciência portuguesa.
Knowledge of pediatricians and the importance of interdisciplinarity in attention to oral health in early childhood
Authors: Emmi Danielle Tupinambá , Lima Aline Fernandes Melo Ribeiro , Lemos Ana Júlia Vieira de , Silva Conceição De Maria Sales da
Published: June 2017

The objective of this study was to evaluate the knowledge of pediatricians on the integrality of attention to oral health in early childhood. A cross-sectional study was conducted with a sample consisting of 70 doctors, working in public and private services, in the city of Belém, state of Pará, Brazil. Data were collected using a questionnaire with approaches on: the professional profile; the knowledge of oral health of children; the use of fluoride; and self-perception on knowledge of oral health. A descriptive analysis of the data was performed, and the association between variables was verified with the Chi-square test, with p = 0.05. The average age of respondents was 41 years. Most professionals were females (88.57%) and featured more than 20 years of professional experience (38.57%). In general, most pediatricians answered satisfactorily the questions related to knowledge of children's oral health. However, when questioned about the knowledge of the use of fluoride, most professionals (92.86%) presented outdated knowledge that could result in inappropriate conduct. It was concluded that most pediatricians have knowledge of oral health promotion, although some concepts and conducts should be updated, especially the importance of fluorides in the control of tooth decay.
Proposição de um modelo de maturidade para sustentabilidade corporativa
Authors: Hepper Eduardo Luiz , Souza Osmar Tomaz de , Petrini Maira De Cássia , Silva Carlos Eduardo Lobo e
Published: June 2017

A Responsabilidade Social Corporativa (RSC) surgiu para expandir a responsabilidade das empresas. Além de produzir bens e serviços necessários para a sociedade, obtendo lucro e assegurando a continuidade dos seus negócios, a organização passa a contar também com o aspecto da responsabilidade legal e o respeito às regras; da responsabilidade ética, que diz respeito a um componente orientador das demais dimensões; e da responsabilidade discricionária, que introduz a filantropia às atividades da empresa. Após reconhecerem que a sua responsabilidade não se limita apenas à questão econômica, mas também aos aspectos sociais e ambientais, as organizações passaram a incorporar as práticas de sustentabilidade nos seus negócios. Os modelos de maturidade servem para orientar e guiar as empresas no avanço deste processo, com a finalidade de atingir estágios avançados de incorporação da sustentabilidade nos negócios. Partindo do conceito de RSC e da sustentabilidade corporativa, o objetivo deste ensaio teórico é promover uma discussão sobre a incorporação das iniciativas de sustentabilidade nas organizações, através da pesquisa teórica sobre os modelos de maturidade da sustentabilidade corporativa. Baseado em sete modelos que possuem o foco na sustentabilidade, foi elaborado um modelo de maturidade das iniciativas de sustentabilidade mais generalista, sendo esta a contribuição deste ensaio.
Microstructure and Mechanical Properties of X80 Girth Welds with Different Welding Processes
Authors: Wu Qian , Tao Han , Yong Wang , Zhang Hong Jie
Published: June 2017

X80 pipeline steels were employed to investigate the effects of two different welding processes (swing welding and row welding) on the quality of weld joints. The welding thermal cycles of multi-pass welding were tested and the microstructures of the two kinds of weld joints were studied by optical microscope. The hardness tests as well as low-temperature impact tests combined with fracture analysis with scanning electron microscope (SEM) were carried out to evaluate the properties of weld joints. The results showed that under the similar condition of heat input, the grain of swing welding joint is bigger than that of row welding. The joint of row welding has lower hardness and better toughness, suggesting that the process of row welding can improve the properties of weld metal. Consequently, though swing welding is simple in operation and good in production efficiency, row welding is better in terms of microstructure and properties of weld joints.
Abnormal Grain Growth on the Surface of Cold-Rolled AA1235 Aluminum Plate during the Annealing Process
Authors: Zhu Y.Z. , Li Xiao Hui , Li J.C. , Fan Wei Long , Xia Cheng Wei , Liu Ran
Published: June 2017

AA1235 aluminum alloys were twin roll cast into a 7.0 mm-thick billet and further rolled into a plate with 70% reduction, followed by annealing at 500 C for 8 h. Abnormal grains were found to be formed on the plate bottom surface. SEM, EBSD, and micro X-ray diffraction were used to analyze the mechanism underlying the abnormal growth of these grains. Results showed that the {100} <001> texture was formed in the surrounding normal grains adjacent to the abnormal grain. The orientation angle between the abnormal grain and its adjacent normal grains was 45°. The {100} <001> texture formed during rolling and annealing accelerated abnormal grain growth. The partially dissolved Fe precipitates were heterogeneously distributed in the plate bottom heterogeneously, which also mainly explained abnormal grain growth.
A Predictive Model of Hot Rolling Flow Stress by Multivariate Adaptive Regression Spline
Authors: Yu Wan Huan , Yao Chang Gui , Yi Xiang De
Published: June 2017

A new modeling method called multivariate adaptive regression spline (MARS) was firstly employed to predict the hot rolling flow stress and explain the relationship among flow stress and various parameters such as major chemical compositions, rolling temperature, rolling speed, compression ratio, thickness, roll radius, furthermore, analyze the importance of the predictor variables. The results showed that the error of training and testing was less than 2%, and rolling temperature, rolling speed, and strip thickness had much contribution to flow stress. Moreover, the impact of various factors on the flow stress can be validated by real production data, which proved the reliability of MARS model to predict the flow stress and guide the practical production.
Microstructure and Magnetic Properties of (Nd1-2xPrxYx)2.28Fe13.58B1.14 Melt-Spun Alloys
Authors: Rong M.H. , Ma J. , Wang Jiang , Zhou H.Y. , Rao G.H.
Published: June 2017

As a rapid solidification technology, strip casting (SC) technology is one of importance method in the production of Nd2Fe14B-based rare-earth permanent magnets. (Nd1-2xPrxYx)2.28Fe13.58B1.14 (x=0.05, 0.10, 0.15, 0.20) alloys prepared by arc melting method under an argon atmosphere were annealed at 1173 K for 360 hrs and then were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC). Magnetic properties of the ribbons prepared by melt-spinning method with high cooling rate were measured by Physical Property Measurement System (PPMS). The XRD and SEM results showed that the annealed (Nd1-2xPrxYx)2.28Fe13.58B1.14 (x=0.10, 0.15, 0.20) alloys had a single phase with tetragonal Nd2Fe14B-tpyed structure, while the annealed (Nd0.90Pr0.05Y0.05)2.28Fe13.58B1.14 alloy contained Nd2Fe14B phase and α-Fe secondary phase. On the other hand, the coercivities (Hcj) of (Nd1-2xPrxYx)2.28Fe13.58B1.14 (x=0.05, 0.10, 0.15, 0.20) melt-spun alloys were about 13.42 kOe, 13.49 kOe, 7.97 kOe and 8.36 kOe, respectively, while the remanences (Br) of the alloys were 7.52 kGs, 7.48 kGs, 9.14 kGs and 7.48 kGs, respectively. In addition, The Curie temperature (Tc) of the annealed (Nd1-2xPrxYx)2.28Fe13.58B1.14 (x=0.05, 0.10, 0.15, 0.20) alloys were determined to be 573 K, 574 K, 579 K and 580 K, respectively.
Numerical Simulation of Hot Die Forging Process of Ti-6Al-4V Alloy Blade
Authors: Chen Jia Hao , Li Jin Shan , Tang Bin , Du Li Hua , Kou Hong Chao
Published: June 2017

Ti-6Al-4V alloy is used extensively in aerospace industries due to its excellent properties. In this paper, the hot die forging process of the Ti-6Al-4V alloy blade was simulated by using 3D finite element method. Based on the model, the effect of process parameters on the deformation was investigated. The results show that the increase of temperature is beneficial to improving the uniformity of stress distribution. The slower the declining velocity of upper die is, the larger the strain gradient of severe deformation area will be. In addition, the stress distribution gets uniform with velocity decreasing. The large friction coefficient can make strain distribution uneven and cause symmetry of stress distribution. The proposed numerical simulation of hot die forging of blade in the present work may yield important information for the development of hot die forging techniques and the manufacture of blade.
Effects of Uniaxial Strain on the Structures of Vacancy Clusters in FCC Metals
Authors: Ye Fei , Xv Hong Bo , Liu Jin Mei , Tong Ke
Published: June 2017

The effects of [001] uniaxial strain on the stable structures and structural evolution of vacancy clusters in fcc metals, Cu, Ni, Al and Fe, have been studied and compared. Under uniaxial strain, the clusters in all these metals tend to align parallel or perpendicular to the strain axis under tensile or compressive strain. Moreover, both the body cluster and the {001} planar cluster become the dominant types. In addition, the stacking fault tetrahedron cluster becomes another dominant type in Al under compressive strain. The cluster structures in Fe are disordered under strain possibly because the pure fcc Fe is thermodynamically unstable under the current simulation condition.
TiN-Al Composite Coatings on A356 Alloy by Mechanical Alloying
Authors: Yuan Zhen Gui , Pan Lu Yao , Jiang Shan , Wang Li Hong , Zuo Min , Zhao De Gang
Published: June 2017

The TiN-Al composite coatings on A356 alloy were successfully synthesized by mechanical alloying (MA) of Al, TiN and C powders under argon atmosphere. Meanwhile, the optimal parameters for mechanical milling processing were determined by changing the material ratio (Al: TiN: C), milling time and the ball-to-powder weight ratio, which might have a significant improvement on the wear resistance of A356 alloys. The microstructures and mechanical properties of A356 alloy samples with TiN-Al composite coatings were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and Brinell hardness test. It was found that under the optimal conditions, i.e. the material ratio of (Al: TiN: C= 17.5:1.5:1), the ball-to-powder weight ratio of 14:1 and the milling duration of 12 h, the Brinell hardness of sample-6 could be remarkably increased to 143.80 HBW. With the TiN-Al coatings fabricated by MA process, the mechanical properties of aluminum alloys could be significantly improved.
Microstructure, Mechanical and Tribological Properties of NbN/Ni Coatings
Authors: Ren Ping , Wen Mao , Du Su Xuan , Meng Q.N. , Zhang Kan , Zheng Wei Tao
Published: June 2017

The NbN/Ni coatings were deposited by co-sputtering on Si (100) substrates. The structure, hardness and tribological properties were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscopy (SEM), nanoindentation test and ball-on-disc tribometer. XRD revealed that the NbN/Ni coatings exhibited a NaCl-type NbN structure but no sign of any nickel phase. For the coatings with various nickel powers ranged from 20 W to 40 W, the shrinkage of the lattice parameter of NbN indicated that Ni atoms might be incorporated into the NbN lattice with a substitution of Nb atoms by the smaller Ni atoms. Further increasing of Ni powers, the degree of crystallinity of the coatings became worse. The NbN coating doped with a certan power of Ni (40 W) exhibited the best degree of crystallinity among all samples. It also displayed a maximum microhardness of 25 GPa combined with a better resistance to plastic deformation, which could attribute to the grain refinement and the solid solution strengthening. Tribilogical properties of NbN/Ni coatings were also found to be depentent on nickel powers significantly. For the pure NbN coating, the coefficient of friction (CoF) was 0.7 approximately, while it decreased to 0.54 when the power of Ni increased to 40 W. Simultaneously, the wear resistance of the NbN/Ni coatings was improved due to the spontaneous oxidation of the wear track surfaces caused by the addition of a certain amount of nickel to the niobium nitride coatings.
Optimization of MAO Process Parameters and Effect of Subsequent Sealing Treatment on Corrosion Resistance of Aluminum Alloy
Authors: Bui Duc Thu , Yang Sen
Published: June 2017

Micro-arc oxidation (MAO) coatings were obtained on the substrate of AlSi12Cu aluminum alloy in Na2SiO3 electrolyte. Then, the MAO coatings were sealed in stearic acid and sodium silicate solution, respectively. Experiments were conducted by varying current density, oxidation time and the frequency. L9 (33) of orthogonal experiments were chosen to optimize the processing parameters in the process of MAO technique. Through the above orthogonal experiments, the optimal process conditions were determined: the current density of 30 A/dm2, the oxidation time of 20 min, and the frequency of 600 Hz. The results showed that the MAO coating consisted of α-Al2O3 and γ-Al2O3. There were lots of pores and micro-cracks on the coating surface. The corrosion current of the aluminum alloy after MAO combination with stearic acid sealing treatments was significantly reduced, decreased 100 times more than the substrate and the corrosion potential increased 272 mV, signifying enhanced corrosion resistance. The corrosion rate of the aluminum alloy after MAO treatment in the washing powder solution decreased 25 times more than that of the substrate.
Microstructure Evolution of Mg-4.5Zn-0.75Er Alloy Containing I-Phase during Hot Compression
Authors: Sun Cui Cui , Liu Ke , Du Wen Bo , Zhou Ji Xue , Yang Yuan Sheng
Published: June 2017

The microstructure evolution of the Mg-4.5Zn-0.75Er alloy containing quasicrystalline phase (I-phase) during heat treatment and hot compression was investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the as-cast alloys mainly consisted of α-Mg matrix and I-phase. The I-phase with different morphologies could be found at both matrix and interdentritic boundaries. The I-phase almost dissolved into the matrix at 460 °C, meanwhile, some magnesium-rare earth phase (Mg-Er phase) was precipitated and the volume fraction increased with prolonging the solid solution time. The true stress-strain curve obtained from the hot compression test showed the flow stress first increased to a maximum and then decreased to a steady state. It indicated that the dynamic competition took place between the working hardening and working softening during hot compression. Moreover, the main deformation mechanism was twining at strain of 0.08 for the as-solution alloy; with the increase of the strain, dynamic recrystallization (DRX) grains appeared at original grains and twins boundaries. Lots of nanoscale I-phase which pined and hindered dislocation precipitated within the matrix during hot compression process.
Deposition and Characterization of C-NbN/NbCN Multilayers on Si(100) Substrates
Authors: Zhang Kan , Li X. , Du Su Xuan , Ren Ping , Wen Mao , Zheng Wei Tao
Published: June 2017

The cubic-NbN/NbCN multilayers with modulation periodicity (Λ) ranging from 4.2 to 39.1 nm were deposited on Si (100) substrate by reactive magnetron sputtering in a mixture of Ar and N2 gases. The Λ dependent structural, mechanical and tribological properties for resulting c-NbN/NbCN multilayers were explored. As Λ varied from 4.2 to 39.1 nm, all the films exhibited an obvious modulated structure. Increasing the Λ, the Nb (C,N)(111) peak in XRD gradually shifted to bigger angles and the peak intensity of NbN(111) became stronger. The stress for all multilayers was compressive ranging in between the stress for both NbN and NbCN single layers, and the stress value was stable with increasing Λ. The NbN layer was beneficial to relaxing the compressive stress which induced by NbCN layer. In addition, as Λ increases, the hardness (H) first increased, and then decreased after reaching a maximum value. The obvious enhancement in hardness for multilayers was observed, whose maximum value approaches 43.3 GPa when Λ = 8.4 nm, 37% larger than that obtained by the rule of mixture value. The friction coefficient values of NbN/NbCNmultilayers ranging between 0.34 and 0.4 were much lower than that of NbN monolayer but higher than that of NbCN monolayer were.
Synthesis and Characterization of Magnetic Al/NiO Composite Pigments with Low Infrared Emissivity
Authors: Liu Yun Feng , Xie Jian Liang , Luo Mei , Peng Bo , Deng Long Jiang
Published: June 2017

Generally, traditional low infrared coatings based on metallic pigments cannot have low lightness, low infrared emissivity and low radar reflectivity simultaneously. Herein, we used a simple and efficient method to synthesize magnetic Al/NiO composite pigments which possessed all these attributes to a degree. The results indicated that the covering area of NiO on the aluminum flake could be tuned by the addition amount of NiCO3 and the reaction temperature of hot-flowing, both of which played a key role on the VIS/IR spectral reflectance and magnetic properties. The magnetic Al/NiO composite pigments with low lightness and low infrared emissivity could be obtained at 130 °C for 24 h in hot flowing liquid. The lightness L* could be decreased to 75.94, however the infrared emissivity (8-14 μm) was also low to 0.421. Compared with the single aluminum flakes, the Al/NiO magnetic composite pigments presented stronger magnetic properties. Therefore, the Al/NiO magnetic composite pigments offered a new choice for the pigments of multispectral stealth coating.
The Effect of Mill Addition of Quartz Glass on Thermal Shock Resistance of Sheet Steel Enamels
Authors: Chen Li Yun , Wu Yan Yan , Jiang Wei Zhong , Ye Jia Yi , Jin Hui Le , Liu Ai Li , Mao Xin Nan
Published: June 2017

Sheet steel enamels with mill addition of quartz glass were manufactured successfully in accordance with the ordinary enamel manufacturing technology. The effect of mill addition of quartz glass on thermal shock resistance and acid resistance of enamels was analyzed through XRD and SEM etc. The results show that the thermal shock of the enamel can be increased greatly by mill addition of quartz glass, and there is the rational range of mill addition of quartz glass in order for the enamel to achieve both the superior acid resistance and the excellent thermal shock.
Numerical Simulation of the Forming Limit of Superplastic AZ31B Magnesium Alloy Sheet
Authors: Song Mei Juan , Huang Chuan Hui , He Min , Luo Xiao Dong , Li Bao Shun
Published: June 2017

Numerical simulation of superplastic forming limit of AZ31B magnesium alloy sheet was investigated. The damage evolution equation based on the law of the micro-damage evolution and statistical mechanics was derived, and damage characteristic parameters as well as the critical value of damage variable were identified to provide a theoretical ground on which the plastic forming technology of magnesium alloy sheet can be optimized. The theoretical prediction was made with the numerical simulation program, and the results were verified by experiments. The forming limit curve of the theoretical prediction drawn by numerical simulation was established by the basic adaptation of the forming limit curve based on the experimental data.
Synthesis and Characterization of Si3N4 Nanopowder by RF Induction Thermal Plasma
Authors: Zhao Xuan , Chen Hai Yan , Shu Chen Yang , Dong Li Hua , Yin Yan Sheng
Published: June 2017

Nano-Si3N4 has been synthesized by the thermal plasma with silicon tetrachloride (SiCl4) as the Si source, liquid ammonia (NH3) as the N source, and silane (SiH4) as the catalyst. And the prepared Nano-Si3N4was heat-treated atfour different temperatures of 1350°C, 1400°C, 1450°C, 1500°C. The as-prepared samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). The results showed that the particle size of the nano-Si3N4 powder was less than 100 nm and it was amorphous when the temperature below 1450°C. At 1500°C, the synthesized Si3N4 powder with the grain size of 10 nm was crystallized, and the α-phase Si3N4 reached more than 90%.
Dependence of Peak Frequency of Microwave Absorption for Co2Z Composite on the Thickness
Authors: Tan Guo Guo , Gu Xi Sheng , Chen Shu Wen , Man Qi Kui , Chang Chun Tao , Li Run Wei , Li Fa Shen , Wang Xin Min
Published: June 2017

A map displaying the reflection loss (RL) properties including the frequency and intensity for Co2Z barium ferrite composite was developed based on the matching model. In quarter-wavelength matching map, the number and the frequency positions of absorbing peaks presenting in RL curve for Co2Z barium ferrite composite with a certain thickness could be approximately predicted by quarter-wavelength matching model. From impedance map, the intensity of absorbing peaks in measured RL curves was analyzed. Moreover, the presence of absorbing peak in RL curve could be illustrated and understood physically and clearly using a picture of interference cancellation of two EM waves reflected by the absorber layer interface and a backed metal plate.
Preparation of Anisotropic Nd-Lean Nd-Fe-B Magnets with Improved Coercivity
Authors: Shen Qian , Ma Yi Long , Yin Xue Guo , Zhou Tao
Published: June 2017

Anisotropic bulk nanocrystal Nd-lean Nd-Fe-B magnets were prepared by hot-pressing the mixture of Nd11.5Fe81.5Nb1B6 melt-spun ribbons and pure Zn powder and subsequent hot-deforming. The effects of deformation on the magnetic properties and microstructure were also studied. The magnetic properties increased significantly for hot-deformed (HD) samples due to the formation of good c-axis texture with increasing deformation. The remanence Mr and maximal energy product (BH)m increased and reached their maximal values at 65% deformation due to the increasing orientation. On the other hand, the grains increased and were elongated normal to the press direction gradually with increasing deformation. The variation trend was similar to that of traditional Nd-Fe-B magnets. However, there was an obvious improvement for coercivity in the initial stage of hot-deformation resulting from the adequate Zn diffusion into grain-boundary. When the deformation was larger than 65%, the magnetic properties were deteriorated due to abnormal grain growth. In order to improve further the coercivity Hci, the samples with Dy addition were prepared. The coercivity of 12300 Oe could be obtained for anisotropic bulk Nd9.5Dy2Fe81.5Nb1B6.
Microstructure and Properties of Rolled Magnesium Alloy Thick Plate at Different Positions
Authors: Zhu Wei Bo , Jin Qiu , Jiang Ai Min , Ding Yu Fan
Published: June 2017

The microstructure and properties of rolled AZ31 magnesium alloy sheet with the change of normal position were investigated by electronic universal testing machine, ZEISS optical microscopy and scanning electron microscopy. The tensile test results showed that the mechanical properties of sample selected at the depth of 8mm, which is 2/5 of the whole thickness counting from rolling plane are closest to the properties for whole sheet. Microstructure characterization indicated that a large number of tiny grains are distributed around the large grains. The majority of these grains are equiaxed grains, and the few twins could be observeded. The fracture mechanism was ascribed to mixed ductile and brittle fractures.
Effects of Annealing on Ferroelectric, Optical and Electrically Controlled Light Scattering Properties of PLZT Transparent Ceramics
Authors: Nie Lei Tao , He Xi Yun , Zeng Xia , Qiu Ping Sun , Cheng Wen Xiu , Chang Cheng Kang
Published: June 2017

PLZT (X/70/30) ceramics with different La contents (X=7.45, 7.54, 7.63 mole%) were fabricated by hot-press sintering techniques. The effects of annealing on ferroelectric, optical and electrically controlled light scattering properties of PLZT transparent ceramics were examined and analyzed. The XRD patterns indicated that all the samples were crystallized into a pure perovskite phase without the second phase. The SEM exhibited fully dense, uniform microstructures with well-developed grains. The annealing treatment weakened the degree of squareness of the ferroelectric hysteresis loop, and even the anti-ferroelectric phase occurred as the La content increasing to X=7.63. The remnant polarization (Pr) and coercive electric field (Ec) decreased with the annealing treatment for all samples. The slow annealing treatment resulted in the lager increase of both transmittance and contrast ratio than those of the rapid annealing treatment at λ=632.8nm. The electrically controlled light scattering properties were obviously enhanced by the annealing treatment. Especially, the PLZT (7.63/70/30) ceramics exhibited the different electrically controlled light scattering performance which indicated it could hold high transmittance and symmetry in a wide electric field range with the slow annealing treatment.
Effect of Bimodal Granularity Distribution on the Properties of Silica-Based Ceramic Cores
Authors: Liu Xiao Guang , Li Xin , Tang Ding Zhong , Yao Jian Sheng , Niu Shu Xin
Published: June 2017

In this work, the effects of the bimodal particle size distribution of fused silica on the properties of silica-based ceramic cores have been investigated. In order to simulate a casting process condition, the core specimens were sintered at 1220°C, tested at above 1500°C. Three point bending tests were carried out on all the prepared specimens. Phase evolution and microstructure were investigated by XRD and SEM respectively. The results showed that with the bimodal granularity distribution broaden and the content of coarse particles increasing, the contraction, flexural strength and creep deformation of ceramic cores decreased linearly, as the content of mineralizer was determined. Coarse particles served as the skeleton to relieve the contraction in ceramic matrix and avoided sharp decrease of flexural strength. The high temperature properties were largely determined by the combined effects of crystallization and skeleton network. The crystallization depended mostly on the fine particles, and the skeleton network was prerequisite to avoid creep deformation.
High Frequency Electrical and Magnetic Properties of Al/Epoxy Composites Prepared by Insulation Coating Process
Authors: Qu Yun Peng , Xie Pei Tao , Liu Yao , Wang Yong , Fan Run Hua , Wu Yu Lin , Tian Yuan
Published: June 2017

Al/Epoxy composites with different Al content were prepared by insulation coating process including high energy ball milling and hot press. The electrical properties and magnetic performance including ac conductivity, permittivity, reactance and permeability were investigated in detail. The frequency dispersions of ac conductivity followed the power law, indicating the hopping conduction behavior. The real part of permittivity for composites increased with higher Al content, which was attributed to the more interface between Al and epoxy. Besides, the real part of the relative permeability decreased with higher Al content in high frequency.