bluuebunny/crossref_metadata_2025 huggingface dataset:
A Platform for Actively Supporting e-Learning in Mobile Networks
Authors: Khan Basit A. , Matskin Mihhail
Published: April 2010

The ubiquitous availability of wireless networks has opened new possibilities for individuals to learn from each other in open learning spaces like cities. Therefore, the changed learning environment must be understood by e-learning systems and technological facilities must be provided for knowledge sharing and construction. Such systems need to be pedagogically sound, yet adaptive to altered modalities. The teacher who was once the central entity to fulfill the learner’s needs may not always be available. Therefore, e-learning systems would fill the gap created by this teacher unavailability by actively participating in learning activities and performing some of the teacher’s roles. This article proposes an architecture designed to meet such challenges in a city-wide context. The authors outline the main components and services needed to fulfill the new requirements and provide the learners with tools, services and educational support for learning activities.
Automatic Pitch Type Recognition System from Single-View Video Sequences of Baseball Broadcast Videos
Authors: Takahashi Masaki , Fujii Mahito , Shibata Masahiro , Yagi Nobuyuki , Satoh Shin’ichi
Published: April 2010

This article describes a system that automatically recognizes individual pitch types like screwballs and sliders in baseball broadcast videos. These decisions are currently made by human specialists in baseball, who are watching the broadcast video of the game. No automatic system has yet been developed for identifying individual pitch types from single view camera images. Techniques using multiple fixed cameras promise highly accurate pitch type identification, but the systems tend to be large. Our system is designed to identify the same pitch types using only the same single-view broadcast baseball videos used by the human specialists, and accordingly we used a number of features, such as the ball’s location, ball speed and catcher’s stance based on the advice of those specialists. The system identifies the pitch type using a classifier trained with the Random Forests ensemble learning algorithm and achieved about 90% recognition accuracy in experiments.
On Quality of Experience in Remote Visualization on Mobile Devices
Authors: Paravati Gianluca , Sanna Andrea , Lamberti Fabrizio , Ciminiera Luigi
Published: April 2010

Quality of Experience (QoE) is a relatively new concept which represents a way of measuring user satisfaction in the use of a certain kind of service. This work investigates issues related to the QoE in manipulating 3D scenes on mobile devices, by focusing on scenarios based on the remote visualization paradigm where a remote server is in charge of computing a flow of compressed images to be delivered to client devices. A novel approach able to dynamically set the encoding parameters at the server side is presented; the considered parameters are frame resolution, frame rate and image quality. The proposed solution is able to tune the above parameters according to both user preferences and network performance. Experimental tests are exploited to assess the relationship between the involved parameters and the QoE. Results obtained by considering low resource hardware (e.g. mobile devices) and unreliable connections (e.g. wireless networks) are presented. User feedback proves the effectiveness of the proposed approach.
Ask and You Will Receive
Authors: Arning Katrin , Ziefle Martina
Published: April 2010

Even though the effective usage of mobile devices has become a mandatory requirement in many professional and private areas, inexperienced users face especially great difficulties in acquiring computer skills. Based on the assumptions of constructivist learning theories, the effect of asking questions and repeated practice on PDA skill acquisition in adults (n = 36) was examined. Learners had the opportunity to ask questions and receive answers during the learning process. One learner group additionally received a manual with basic PDA-operating-principles; a control group received no instructional support at all. As dependent variables task effectiveness, efficiency, subjective ratings of perceived ease of use as well as number and content of questions were assessed. Findings showed that asking questions and repeated practice considerably enhanced PDA-performance in adult novice learners, but not perceived ease of use. Furthermore, the content-analysis of learner questions gave valuable insights into information needs, cognitive barriers and mental models of adult learners, which can contribute to the design of interfaces and computer-based tutors.
Spin Relaxation Mechanisms in the Organic Semiconductor Alq3
Authors: Patibandla Sridhar , Kanchibotla Bhargava , Pramanik Sandipan , Bandyopadhyay Supriyo , Cahay Marc
Published: April 2010

We have measured the longitudinal (T1) and transverse (T2) spin relaxation times in the organic semiconductor tris(8-hydroxyquinolinolato aluminum)—also known as Alq3—at different temperatures. These measurements shed some light on the spin relaxation mechanisms in the organic. The two most likely mechanisms affecting T1 are hyperfine interactions between carrier and nuclear spins, and the Elliott-Yafet mode. On the other hand, the dominant mechanism affecting T2 of delocalized electrons in Alq3 remains uncertain, but for localized electrons (bound to defect or impurity sites), the dominant mechanism is most likely spin-phonon coupling.
Mutual Development
Authors: Mørch Anders I. , Andersen Renate
Published: April 2010

The article presents and analyzes data from a case study in customer-initiated software product development. We have observed and participated in system development activities in a commercial software house (company) over a period of two years. The company produces project-planning tools for the oil and gas industry, and relies on interaction with customers for further development of its products. Our main research question is how customers and professional developers engage in mutual development mediated by shared software tools (products and support systems). We have used interviews with developers and customers as our main source of data, and identified the activities (from use to development) where customers have contributed to development. We analyze our findings in terms of co-configuration, meta-design and modding to name and compare the various stages of development (adaptation, generalization, improvement request, specialization, and tailoring).
End-User Software Engineering and Why it Matters
Authors: Burnett Margaret
Published: April 2010

End-user programming has become ubiquitous; so much so that there are more end-user programmers today than there are professional programmers. End-user programming empowers—but to do what? Make bad decisions based on bad programs? Enter software engineering’s focus on quality. Considering software quality is necessary, because there is ample evidence that the programs end users create are filled with expensive errors. In this paper, we consider what happens when we add considerations of software quality to end-user programming environments, going beyond the “create a program” aspect of end-user programming. We describe a philosophy of software engineering for end users, and then survey several projects in this area. A basic premise is that end-user software engineering can only succeed to the extent that it respects that the user probably has little expertise or even interest in software engineering.
WOAD
Authors: Cabitza Federico , Simone Carla
Published: April 2010

In this article, we present WOAD, a framework that was inspired and partly validated within a 2-year observational case study at a major teaching hospital. We present the WOAD framework by stating its main and motivating rationales, outlining its high-level architecture and then introducing its denotational language, LWOAD. We propose LWOAD to support users of an electronic document system in declaratively expressing, specifying and implementing content- and event-based mechanisms that fulfill coordinative requirements and make users aware of relevant conditions. Our focus addresses (a) the user-friendly and yet formal expression of local coordinative practices based on the work context; (b) the promotion of awareness of both these conventions and the context to enable actors to quickly respond; (c) the full deployment of coordination-oriented and context-aware functionalities into legacy electronic document systems. We give examples of LWOAD mechanisms taken from the case study and discuss their impact from the EUD perspective.
Dynamic Pricing Model for Substitutable Products
Authors: Wen Ue-Pyng , Chen Yi
Published: April 2010

A dynamic pricing model in airline seat allocation, where a seller offers two substitutable perishable products in the monopolist market, is proposed in this article. The objective is to maximize the total profit gained from both products. We analyze the problem using a multinomial logit model to describe the customer choice behavior. The exact solution is obtained according to the calculated optimal time thresholds. Sellers can dynamically adjust the price policy in the continuous-time process. We also analyze the efficient price strategy according to the marginal expected revenue function. Furthermore, a numerical example is given to illustrate the procedure and the result is compared with the fixed price policy.
Modeling the Experience of Emotion
Authors: Broekens Joost
Published: April 2010

Affective computing has proven to be a viable field of research comprised of a large number of multidisciplinary researchers, resulting in work that is widely published. The majority of this work consists of emotion recognition technology, computational modeling of causal factors of emotion and emotion expression in virtual characters and robots. A smaller part is concerned with modeling the effects of emotion on cognition and behavior, formal modeling of cognitive appraisal theory and models of emergent emotions. Part of the motivation for affective computing as a field is to better understand emotion through computational modeling. In psychology, a critical and neglected aspect of having emotions is the experience of emotion: what does the content of an emotional episode look like, how does this content change over time, and when do we call the episode emotional. Few modeling efforts in affective computing have these topics as a primary focus. The launch of a journal on synthetic emotions should motivate research initiatives in this direction, and this research should have a measurable impact on emotion research in psychology. In this article, I show that a good way to do so is to investigate the psychological core of what an emotion is: an experience. I present ideas on how computational modeling of emotion can help to better understand the experience of motion, and provide evidence that several computational models of emotion already address the issue.
Review of Kansei Research in Japan
Authors: Inokuchi Seiji
Published: April 2010

This article gives a historical review of Kansei-based media technologies in Japan. Kansei is a Japanese word, the meaning of which covers sensibility, sentiment, emotion, and feeling. Kansei research started in the field of music, because music is the most acceptable of the arts to computer science. In the 1990s, the applications of Kansei machine vision became widespread in many industrial fields, including electronic production, automobile manufacture, steel-making, the chemical industry, the food industry, and office appliances, among others. Kansei technologies are also applied to human interface systems, including the field of brain science, for human communication.
Simplifying the Design of Human-Like Behaviour
Authors: Bryson Joanna J. , Tanguy Emmanuel
Published: April 2010

Human intelligence requires decades of full-time training before it can be reliably utilized in modern economies. In contrast, AI agents must be made reliable but interesting in relatively short order. Realistic emotion representations are one way to ensure that even relatively simple specifications of agent behavior will be expressed with engaging variation, and those social and temporal contexts can be tracked and responded to appropriately. We describe a representation system for maintaining an interacting set of durative states to replicate emotional control. Our model, the Dynamic Emotion Representation (DER), integrates emotional responses and keeps track of emotion intensities changing over time. The developer can specify an interacting network of emotional states with appropriate onsets, sustains, and decays. The levels of these states can be used as input for action selection, including emotional expression. We present both a general representational framework and a specific instance of a DER network constructed for a virtual character. The character’s DER uses three types of emotional state as classified by duration timescales, keeping with current emotional theory. We demonstrate the system with a virtual actor. We also demonstrate how even a simplified version of this representation can improve goal arbitration in autonomous agents.
Automatic, Dimensional and Continuous Emotion Recognition
Authors: Gunes Hatice , Pantic Maja
Published: April 2010

Recognition and analysis of human emotions have attracted a lot of interest in the past two decades and have been researched extensively in neuroscience, psychology, cognitive sciences, and computer sciences. Most of the past research in machine analysis of human emotion has focused on recognition of prototypic expressions of six basic emotions based on data that has been posed on demand and acquired in laboratory settings. More recently, there has been a shift toward recognition of affective displays recorded in naturalistic settings as driven by real world applications. This shift in affective computing research is aimed toward subtle, continuous, and context-specific interpretations of affective displays recorded in real-world settings and toward combining multiple modalities for analysis and recognition of human emotion. Accordingly, this article explores recent advances in dimensional and continuous affect modeling, sensing, and automatic recognition from visual, audio, tactile, and brain-wave modalities.
Symbiotic Aspects in e-Government Application Development
Authors: Moulin Claude , Sbodio Marco Luca
Published: April 2010

For e-Government applications, the symbiotic aspect must be taken into account at three stages: at design time in order to integrate the end-user, at delivery time when civil servants have to discover and interact with new services, at run time when ambient intelligence could help the interaction of citizens with specific services. In this article, we focus on the first two steps. We show how interoperability issues must concern application designers. We also present how semantics can help civil servants when they have to deal with e-government service frameworks. We then describe an actual application developed during the European Terregov project where semantics is the key point for simplifying the role of citizens when requesting for health care services.
Retrofitting Existing Web Applications with Effective Dynamic Protection Against SQL Injection Attacks
Authors: Sun San-Tsai , Beznosov Konstantin
Published: April 2010

This article presents an approach for retrofitting existing Web applications with run-time protection against known, as well as unseen, SQL injection attacks (SQLIAs) without the involvement of application developers. The precision of the approach is also enhanced with a method for reducing the rate of false positives in the SQLIA detection logic, via runtime discovery of the developers’ intention for individual SQL statements made by Web applications. The proposed approach is implemented in the form of protection mechanisms for J2EE, ASP.NET, and ASP applications. Named SQLPrevent, these mechanisms intercept HTTP requests and SQL statements, mark and track parameter values originating from HTTP requests, and perform SQLIA detection and prevention on the intercepted SQL statements. The AMNESIA testbed is extended to contain false-positive testing traces, and is used to evaluate SQLPrevent. In our experiments, SQLPrevent produced no false positives or false negatives, and imposed a maximum 3.6% performance overhead with 30 milliseconds response time for the tested applications.
A Formal Approach for Securing XML Document
Authors: Bai Yun
Published: April 2010

With the ever increasing demand for the Web-based applications over the Internet, the related security issue has become a great concern. Web document security has been studied by many researchers and various security mechanisms have been proposed. The aim of this article is to investigate the security issue of the XML documents. We discuss a protection mechanism and investigate a formal approach to ensure the security of Web-based XML documents. Our approach starts by introducing a high level language to specify an XML document and its protection authorizations. We also discuss and investigate the syntax and semantics of the language. The flexible and powerful access control specification can effectively protect the documents from unauthorized attempts.
Reclaiming the Green Continent
Authors: Iannone Pablo
Published: April 2010

This essay examines Latin American technological development and its connections with regional economic development, ecological deterioration, political freedoms’ fluctuations, and globalization processes—understood as the spreading interconnectedness of business, science, technology, politics, and culture through large regions or the entirety of the world. The essay investigates how policy and decision issues resulting from Latin American technological development and its correlates can be plausibly addressed and argues for several theses, most notably, that in dealing with the issues, national legislation and international treaties have attained and are likely to attain their purposes only to a limited extent and in a mixed manner; that less legislation-dependent procedures evidence greater effectiveness and political feasibility; and that some globalization processes help fuel the environmental issues, while others help facilitate their resolution. The essay provides some concrete examples of how the issues can be soundly addressed.
Information Technology Exception Messages
Authors: Amer T.S. , Maris Jo-Mae B.
Published: April 2010

Users of information technology (IT) frequently encounter “exception messages” during their interactions with computing systems. Exception messages are important points of communication with users of IT and are similar in principle to compliance and warning messages that appear on consumer products and equipment (e.g., cigarettes, power tools, etc.), in various environments (e.g., around machinery), and on chemicals. This study reviews the normative elements and information that are included in product, chemical, and environment compliance and warning messages and combines these with recommendations in the IT literature to propose that five elements and information should be included in IT exception messages with a standard format. It is argued that including these elements in the proposed format will improve the consistency and effectiveness of exception messages. Also reported are the results of an investigation of a sample of actual exception messages to determine their degree of conformity with the proposed elements. Results indicate that IT exception messages lack descriptive content.
Designing Practice-Oriented Toolkits
Authors: Akoumianakis Demosthenes
Published: April 2010

This article aims to develop a conceptual frame of reference for analyzing and gaining insight to virtual community practices. The author’s normative perspective is that the vast majority of studies on virtual communities concentrate on managing (i.e., identifying, forming and sustaining) virtual communities, dismissing the practice the community is about. On the other hand, there is evidence to suggest that practice-oriented insights may offer new grounds for innovative engagement in virtual settings. Following a thorough analysis of seemingly heterogeneous concepts from new media, community-oriented thinking and practice-based approaches the article discusses what is it that differentiates offline from online practice, how these two are intertwined and why the literature lacks detailed insights on the actual practice virtual communities become engaged in. In light of this discussion, the Community-media-Practice grid is proposed as a guide for designing practiceoriented toolkits fostering a shared language for co-engagement in linguistic domains.
eLearning in the Cloud
Authors: Sclater Niall
Published: April 2010

Elearning has grown rapidly in importance for institutions and has been largely facilitated through the “walled garden” of the virtual learning environment. Meanwhile many students are creating their own personal learning environments by combining the various Web 2.0 services they find most useful. Cloud computing offers new opportunities for institutions to provide dynamic and up-to-date Internet-based, e-learning applications while ensuring high levels of service, and compliance with institutional policies and legislation. The cloud is rapidly evolving in its architecture, the services offered and the logistics of deployment. It brings with it risks but also possibilities for learners and for educational institutions to reduce costs and enhance services. It is likely to severely disrupt the business model developed by existing vendors of VLEs who provide an integrated suite of e-learning tools, installed and maintained by the institution’s IT services department.
Designing Effective Spaces, Tasks and Metrics for Communication in Second Life Within the Context of Programming LEGO NXT Mindstorms™ Robots
Authors: Vallance Michael , Martin Stewart , Wiz Charles , van Schaik Paul
Published: April 2010

Science education is concerned with the meaningful pursuit of comprehension, knowledge and understanding of scientific concepts and processes. In Vygotskian social constructivist learning, personal interpretation, decision-making and community cooperation fosters long-term understanding and transference of learned concepts. The construction of knowledge requires learners to be actively involved in the process of learning. For effective science learning to take place an instructor’s pedagogical approach must be anchored in meaningful contexts so that students have actual opportunities to experience science. This paper presents the early stages of a research project that attempts to assess and define effective measurements for evaluating strategies for communicating science by using LEGO robots and Mindstorms™ RCX controllers that are collaboratively constructed and programmed by students using virtual technologies while physically situated in different locations.
Homo Virtualis
Authors: Jarmon Leslie
Published: April 2010

This article previews the emergence of homo virtualis. Drawing on data from seven research studies, peerreviewed published research articles, and selected excerpts of 30 months of field notes taken in Second Life, the article examines virtual learning environments and embodiment through the lens of interactions of avatars with other avatars, virtual objects, landscapes, sounds, and spatial constructs. Analysis is grounded in the polyvocal evidence provided by select participants who experienced a sense of embodied co-presence and connection with others across geo-physical distances. The discourse ranges from that of high school girls, professional retirees, toxicology and design undergraduates, interdisciplinary graduate students, to educators and researchers from K-12 through university full professors collaborating in SL. In an ecology of virtual contexts, learners inhabit a broader landscape of their own and others’ making that allows them to be teachers, designers, researchers, communicators, and collaborators.
Evaluating Games-Based Learning
Authors: Hainey Thomas , Connolly Thomas
Published: April 2010

A highly important part of software engineering education is requirements collection and analysis, one of the initial stages of the Software Development Lifecycle. No other conceptual work is as difficult to rectify at a later stage or as damaging to the overall system if performed incorrectly. As software engineering is a field with a reputation for producing graduate engineers who are ill-prepared for real-life software engineering contexts, this paper suggests that traditional educational techniques (e.g. role-play, live-through case studies and paper-based case studies) are insufficient in themselves. In an attempt to address this problem we have developed a games-based learning application to teach requirements collection and analysis at the tertiary education level. One of the main problems with games-based learning is that there is a distinct lack of empirical evidence supporting the approach. This paper will describe the evaluation of the requirements collection and analysis process using a newly developed framework for the evaluation of games-based learning and will focus on evaluation from a pedagogical perspective.
Toward Introducing Semantic Capabilities for WSRP
Authors: Wilkinson Kevin , Polgar Jana
Published: April 2010

The emergence of web services technology has introduced a problem: how can we ensure that requests are successfully matched with advertisements when consumers and producers may use different terminology to describe the same service or the same terminology to describe different ones? Popular approaches to solving this problem are reviewed which involve the use of ontologies to improve the semantic content of the matchmaking process. When services are presentation-oriented rather than merely data-oriented, another layer of difficulty is introduced. The architecture of Web Services for Remote Portlets is discussed extensively, including the interaction cycle between the client and the producer to maintain state variables for each remote session of a portlet to provide sufficient background for readers. A comparison is made between the way concepts are implemented in two different portlet specifications – IBM Portlet API and JSR168 specification. Architecture is proposed to support the automated use of dynamic services for remote portlets, the motivation for which is the lack of expressivity of the current standards to represent the semantic requirements and capabilities of data and user-facing web services.
A Cloud Portal Architecture for Large-Scale Application Services
Authors: Jeng Jun-Jang , Mohindra Ajay , Yang Jeaha , Chang Henry
Published: April 2010

Application services entail multi-billion dollars of market in IT industry. However, to construct an application service is a labor- intensive and error-prone process. Application services developed through traditional development methods expose the same
Part of the Tool Kit
Authors: Wong Kee , Adamson Greg
Published: April 2010

Portals, and Service Oriented Architecture in general, simplify the process of delivering services to users. But this doesn’t represent a fundamental change to the user experience. Changing the user experience depends on business intent, and while Web 2.0
Migrating Web Services in Mobile and Wireless Environments
Authors: Park Myung-Woo , Kim Yeon-Seok , Lee Kyong-Ho
Published: April 2010

Mobile devices enabled with Web services are being considered as equal participants of the Web services environment. The frequent mobility of devices and the intermittent disconnection of wireless network require migrating or replicating Web services onto adjacent devices appropriately. This article proposes an efficient method for migrating and replicating Web services among mobile devices through code splitting. Specifically, the proposed method splits the source code of a Web service into subcodes based on users’ preferences for its constituent operations. The subcode with a higher preference is migrated earlier than others. The proposed method also replicates a Web service to other devices to enhance its performance by considering context information such as network traffic or the parameter size of its operations. To evaluate the performance of the proposed method, the effect of the code splitting on migration was analyzed. Furthermore, to show the feasibility of the proposed migration method, three application scenarios were devised and implemented.
Estimating the Privacy Protection Capability of a Web Service Provider
Authors: Yee George O.M.
Published: April 2010

The growth of the Internet has been accompanied by the growth of Web services (e.g., e-commerce, e-health, etc.), leading to important provisions put in place to protect the privacy of Web service users. However, it is also important to be able to estimate the privacy protection capability of a Web service provider. Such estimates would benefit both users and providers. Users would benefit from being able to choose (assuming that such estimates were made public) the service that has the greatest ability to protect their privacy (this would in turn encourage Web service providers to pay more attention to privacy). Web service providers would benefit by being able to adjust their provisions for protecting privacy until certain target capability levels of privacy protection are reached. This article presents an approach for estimating the privacy protection capability of a Web service provider and illustrates the approach with an example.
Managing the Replaceability of Web Services Using Underlying Semantics
Authors: Peng Dunlu , Wang Xiaoling , Zhou Aoying
Published: April 2010

In the context of web services, service replaceability refers to the ability of substituting one service for another. With the bloom of service-oriented computing, the effective management of service replaceability is important to make the applications unaffected once the requested service cannot work. This work studies the quantitative aspect of the replaceability of web services. FCA (Formal Concept Analysis) method is applied to reveal the pairwise replaceable relationship among web services. A novel structure, called RSLattice, is proposed to index web services on the basis of the underlying semantics, and the replaceability among services at the operation level is represented accurately. It ensures that the services having mutual replaceability are organized in the same path of RSLattice. Based on this property, we can greatly reduce the search space when retrieving the replaceable services in RSLattice. Experimental evaluation shows that RSLattice is an efficient and flexible structure for service replaceability management.
Changes in Microstructures and Properties of Al2O3/ZrO2 (Y2O3) with Different Content of ZrO2
Authors: Pan Chuan Zeng , Zhang Long , Zhao Zhong Min , Qu Zhen Sheng , Yang Quan , Huang Xue Gang
Published: April 2010

Based on preparation of Al2O3/ZrO2 (4Y) by combustion synthesis in high-gravity field, the microstructure transformation and properties of the materials are investigated through adjusting the ZrO2 (4Y) content in the composites. As the content of ZrO2 changed from 37% to 40%, the microstructures of the ceramics transformed the sphere-like tetragonal ZrO2 crystals from the rod-shaped colonies with nanocrystalline structures. Al2O3/33%ZrO2 (4Y) had the maximum relative density, hardness and flexural strength due to the low solidification temperature, the highest volume fraction of the colonies, small-size defect and high fracture toughness, whereas Al2O3/44%ZrO2 (4Y) was somewhat weakened in strength in despite of its highest fracture toughness.
Preparation and Mechanical Properties of HA/PHB Composites
Authors: Zhuo Zhi Qi , Dong Li Min , Wang Cheng , Zan Qing Feng , Tian Jie Mo
Published: April 2010

This paper focuses on the influence on the mechanical properties of hydroxyapatite / poly-hydroxybutyrate (HA / PHB) composites by different HA contents, and the effect of Silane coupling agent on improving the interface of HA/PHB composite materials. The HA/PHB composites were prepared by ball milling, hot-pressing, the HA content were 0, 5, 10, 15, 20 and 30wt%, respectively. Silane coupling agent was used for HA surface treatment in HA/PHB composites to compare with not having HA surface treatment in HA/PHB composite materials. The impact strength and flexural strength of HA / PHB composites were tested, and the microstructure of the fracture surface was observed by SEM. The results showed that HA could enhance the bending strength of HA/PHB composites. With HA content increased, the bending strength increased first and then decreased, when the HA content was 10wt%, the maximum bending strength reached 32.74MPa, increased about 41% comparing with pure PHB. Silane coupling agent can improve the interface of HA / PHB, then enhance the mechanical strength. When the HA content was 15wt%, the maximum bending strength reached 46.6MPa, Increased about 56% comparing with the same proportion of untreated HA/PHB composite material, and about double comparing with pure PHB.
Application of ANN Back-Propagation for An Alloy Reinforced Ceramics/Metal Composite under Extra-Low Cycle Bending Fatigue Loading
Authors: Rui Zhi Yuan , Duan Hong Yan , Lei Chun Li , Wei Xing Chun
Published: April 2010

Artificial neural network (ANN) back-propagation model was developed to predict the fracture design parameters in reinforced ceramic matrix composites (CMCS).Training ANN model was introduced at first. And then the Training data for the development of the neural network model was obtained from the experiments. The input parameters, the presetting deflection and tip radius of the notch, and the output, the cycle times of fracture were used during the network training. The neural network architecture is designed. The ANN model was developed using back propagation architecture with three layers jump connections, where every layer was connected or linked to every previous layer. The number of hidden neurons was determined according to special formula. The performance of system is summarized at last. The ANN model exhibited excellent comparison with the experimental results. It was concluded that predicted fracture design parameters by the trained neural network model seem more reasonable compared to approximate methods. It is possible to claim that, ANN is fairly promising prediction technique if properly used.
Investigation on Al2O3/YSZ Eutectic Ceramics Lining in the Pipes Prepared by Combustion Synthesis
Authors: Xu Bao Cai , Zhang Long , Wang Chun Mei , Duan Rong Xia
Published: April 2010

The Al2O3/YSZ eutectic composite ceramics-lined pipes have been prepared by combustion synthesis. By adding ZrO2 (4Y) to the thermit, the influences of centrifugal force and eutectic composition on the microstructure, mechanical properties, strengthening and toughening of ceramics lining are researched. The growth of melt is based on eutectic transformation under high degree of under-cooling at centrifugal force above 200G. The linings are comprised of rod-shaped Al2O3 matrix eutectic grains. The diameters of tetragonal lattice ZrO2 fiber in rod-shaped grains are on nano-micron scale. Causing the strengthening and toughening of ceramics to be promoted, and the Al2O3/YSZ eutectic composite ceramics-lined pipes have high comprehensive mechanical properties.
Effects of Heat-Treatment Temperature on the Properties of Negative CTE Eucryptite Ceramics
Authors: Li Yong , Wei Qi Hong , Li Ling , Wang Chong Hai , Zhang Xiao Li , Gao Fang
Published: April 2010

In this paper, negative thermal expansion coefficient eucryptite powders were prepared by sol-gel method using silica-sol as starting material. The raw blocks were obtained by dry pressing process after the powder was synthesized, and then the raw blocks were heat-treated at 600º, 1150º, 1280º, 1380º, 1420º and 1450°C, respectively. Variations of density, porosity and thermal expansion coefficient at different heat treatment temperatures were investigated. Phase transformation and fracture surface morphology of eucryptite heat-treated at different temperatures, respectively, were observed by XRD and SEM. The results indicate that, with the increasing heat- treatment temperature, the grain size and the bending strength increased, porosity decreased, thermal expansion coefficient decreased continuously. Negative thermal expansion coefficient of -5.3162×10-6~-7.4413×10-6 (0~800°C) was obtained. But when the heat-treatment temperature was more than 1420°C, porosity began to increase, bending strength began to decrease, which were the symbols of over-burning, while the main crystal phase didn’t change.
High Temperature Oxidation Behavior of the B4C/BN Composites
Authors: Jiang Tao , Jin Zhi Hao , Yang Jian Feng , Qiao Guan Jun
Published: April 2010

The B4C/BN composites were fabricated by hot-pressing process. The microstructure, mechanical properties and oxidation resistances of the B4C/BN composites were investigated. It was shown that the h-BN particles were distributed in the B4C ceramics matrix. The mechanical properties of the B4C/BN microcomposites and the B4C/BN nanocomposites decreased gradually with the increasing content of h-BN. The mechanical properties of the B4C/BN nanocomposites were significantly improved in comparison with the B4C/BN microcomposites. The oxidation processes were performed at 1000oC, 1100oC, 1200oC, 1300oC for 20h. The oxidation curves of the B4C monolith, the B4C/BN microcomposites and the B4C/BN nanocomposites decreased gradually with the increase of oxidation temperature and oxidation time. The specimen’s weight and the oxidation resistance decreased gradually with the increase of oxidation temperature and oxidation time. The specimens remained good oxidation resistance at 1000oC; the oxidation resistance decreased remarkably at 1300oC. The decreasing specimen’s weight was attributed to the evaporation of B2O3 which produced by oxidation process of B4C and h-BN. The phase composition and microstructure of specimen’s surface after oxidation process were investigated by XRD and SEM.
Preparation of Fe Coating Al2O3 Nanometer Composite Powder and its Mechanical Properties after Hot Press Sintering
Authors: Lu Hong Xia , Wei Zhang , Zhang Rui , Xu Hong Liang , Wang Hai Long , Chen De Liang , Yang Dao Yuan
Published: April 2010

Nano-Fe particles coating Al2O3 composite powders were prepared by heterogeneous precipitation method with nanometer -Al2O3 and Fe(NO3)3•9H2O as raw materials. The composite powders were analyzed by DSC-TG, XRD,SEM and Zeta potential. Results showed that Fe coating Al2O3 nanometer composite powders were obtained in the condition of being sintered at 500°C for 30min and reduced at 700°C for 1h in H2. The coating Fe nanometer particles are in the shape of sphericity with diameter about 30nm and the dispersion of the powders is uniform. Al2O3/Fe composite ceramics were obtained by hot-pressing (30MPa). The mechanical properties of the composite were investigated after hot press at different temperatures. With the increasing of Fe content in composite ceramics, the hardness of the composite is decreased. Fracture toughness of 10mol%Fe content is 5.62MPa after sintered at 1400°C, which is increasing 57% high than that of monolithic Al2O3 ceramics.
High Temperature Ceramifying Behavior of SR/Al2O3 Composites
Authors: Xiong Yuan Lu , Shen Qiang , Chen Fei , Zheng Jin , Zhang Lian Meng
Published: April 2010

In this work, silicone/alumina composites with 33 wt.% silicone content are prepared by compression mould technique. TGA, XRD and SEM were used to characterize the ceramifying behavior when the samples were heated from 600 to 1600°C. XRD results suggest that the ceramic residue of SR could restrain the phase transformation of γ-Al2O3 below 1100°C, indicating that the chemical bonds preserve the mechanism strength of SR/Al2O3 composites under high temperature. The flexural strength increases from 18.19 MPa to 75.31 MPa with the increasing temperature from 600 to 1600°C, owing to the sintering reaction between SiO2 and Al2O3 forming mullite phase under higher temperature. It has low liner shrinkage after firing and nearly no macrocracks or deformation under any temperature, illustrating that the SR/Al2O3 composites can be used as organic fire-retardancy materials.
Carbothermal Reduction Synthesis of Zirconium Diboride Powders Assisted by Microwave
Authors: Wang Hai Long , Zhang Shi Xun , Chen De Liang , Han Qian Fei , Lu Hong Xia , Xu Hong Liang , Wang Chang An , Zhang Rui
Published: April 2010

ZrB2 powder has been prepared through carbothermal reduction boronization of zirconia/boron carbide/carbon mixtures heating assisted by microwave. The powder characteristics were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), nitrogen absorption (BET model) and scanning electron microscope (SEM). The experiments indicated that excessive B4C is necessary and the carbothermic reaction reacts severely at a higher temperature and complete at 1600oC. The crystallite size has ranged from 50-100 nm, according to the calculated surface area. Highest purity of ZrB2 powder, which was synthesized at 1600oC, is 99.67 wt%. The surface area of ZrB2 powder synthesis at 1600oC is 18.33 m2/g. Vibration of temperature should affect the purity of ZrB2, as the sub reaction acted.
Mechanical Behaviors of Ultra-High Temperature Ceramics
Authors: Zhou Fei Fei , Zeng Tao , Fang Dai Ning , Jiang Li Li
Published: April 2010

The parameters, such as thermal expansion coefficient and Young's modulus, are considered as a function of temperature and incorporated into ANSYS code to calculate the stress field of UHTCs under high temperature condition in the present work. The stress fields of two kinds of heating cases are calculated and compared. By establishing the relation between the temperature and the mechanical properties of the UHTCs, it is found that the mechanical behavior of UHTCs is strongly affected by the oxide film thickness, initial temperature and the heating rate.
Sol-Gel Synthesis and Characterization of LaAlO3 Nanoparticles Using Gelatin as Organic Precursor
Authors: Tian Zhong Qing , Yang You Li , Lin Lin
Published: April 2010

LaAlO3 has gained attention in the last few years because of its favorable microwave dielectric properties, excellent lattice matching and a good matching for thermal expansion. Nanoparticles of LaAlO3 were produced by using gelatin as an organic precursor. The optimum temperature for the phase formation of the precursor sample is found out by TG/DTA analysis. The specific surface area of the powder was measured by the BET technique with nitrogen. X-ray diffraction (XRD) was used to determine the phases present in the calcined powders and to estimate particle size. The morphology of LaAlO3 powder was studied by transmission electron microscopy (TEM). Microwave dielectric properties were measured using a HP8722ET network analyzer. The results demonstrate that pure perovskite LaAlO3 powder formed at 800 °C for 2 h. And the crystallite size was in the range of 17-48 nm. The specimen sintered at 1450 °C for 8 h shows 97.4% of the theoretical density and gave the excellent microwave dielectric properties: εr=23.3 and Qf=32300 GHz.
Preparation of HfO2 Thin Film through Self-Assembled Monolayers on Si Substrate
Authors: Zheng Yu Qin , Tan Guo Qiang , Miao Hong Yan , He Zhong Liang , Xia Ao , Bo Hai Yang
Published: April 2010

HfO2 thin film was successfully prepared on the silicon substrate by the Liquid Phase Deposition (LPD) and functionalized organic self-assembled monolayers (SAMs) method. Measurement of contact angle showed that SAMs surface characteristics changed from hydrophobic to hydrophilic after UV irradiation. Photographs of Metallographic Microscope showed that octadecyl trichlorosilane-self- assembled monolayers (OTS-SAMs) had an active effect on the deposition of HfO2 thin film. XRD, SEM and AFM images indicated that the HfO2 thin film with cubic crystal structure was smooth, uniform and dense. Its grain size was between 40-100 nm and the height of thin film varies between 20 and 100 nm.
Structure and Multiferroic Properties of Bi0.9Y0.1FeO3-PbTiO3 Ceramics
Authors: Feng Bao Lin , Wang Chong Hai , Zhou Chang Ling , Sun Cheng Gong , Xiong Zhao Xian , Xue Hao
Published: April 2010

Bismuth ferrite, BiFeO3, was an important multiferroic material, which simultaneously exhibited ferroelectric ordering and antiferromagnetic ordering in the bulk form. The solid solutions of Bi0.9Y0.1FeO3 with PbTiO3 were prepared by the conventional solid state reaction. It was clear that in Bi0.9Y0.1FeO3-PbTiO3 solid solution, the structure remined rhobohedral for 85 mole% of Bi0.9Y0.1FeO3, from 80 to 70mole% it were rhobohedral and tetragonal, and below 65 mole%, the structure transformed to tetragonal. The dielectric and ferroelectric properties of the ceramics had been significantly improved by means of ionic substitution of Ti4+ for Fe3+, which reduced the electric conductivity. The dielectric constants of the ceramic samples were enhanced from 84 to 241 and the remnant polarizations were improved from 0.494 to 2.17 μC/cm2.
Synthesis and Characterization of BiFeO3 on OH-Functionalized Organic SAMs by Metalorganic
Authors: Song Ya Yu , Tan Guo Qiang , Miao Hong Yan , Xia Ao , Bo Hai Yang , Liu Yan
Published: April 2010

Polycrystalline BiFeO3 (BFO) thin films were grown via metal organic deposition method on OH-functionalized organic self-assembled monolayers (SAMs) on glass. The stable BiFeO3 precursor solutions were obtained by using iron nitrate and bismuth nitrate as raw materials, acetic acid and glycol as solvent and citric acid as chelating agent. Firstly, the preparation and functionalization of octadecyltrichlorosilane (OTS) self-assembled monolayers on the hydroxylated glass substrates was investigated. Water contact angle measurement and atomic force microscopy (AFM) confirmed the presence of a uniform, complete monolayer. After BiFeO3 was prepared on glass substrates, the film- forming and heat treatment processing of BiFeO3 films were studied. The BFO film was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectrograph (EDS). XRD pattern indicated that the grains of sample began to grow at 450 °C, and which was made up of BiFeO3 and some impure phase. With the increase of temperature, impure phase were disappeared and the intensity of diffraction peaks strengthened. Pure BiFeO3 phase were obtained at 500 °C ~ 600 °C. When the heat treatment temperature increased above 650 °C, the impure phase appeared. SEM showed that the BFO thin film possessed a dense microstructure on OH-functionalized SAMs.
Preparation and Microwave Absorbing Properties of Cu-Doped Ni-Zn Spinel Ferrites
Authors: Gao Fen , Zhao Dong Lin , Shen Zeng Min
Published: April 2010

Ni-Zn spinel ferrite and Cu-doped spinel ferrite were prepared by a conventional ceramic processing method. Microwave absorption, complex permittivity and permeability of the (Ni0.5Zn0.5)Fe2O4 and (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrites within the frequency range of 0.5-18 GHz were investigated. The reflection loss calculation results show that the Ni-Zn spinel ferrite and Cu-doped Ni-Zn spinel ferrite are good electromagnetic wave absorbers in the microwave range. The single layer (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrite absorber with a thickness of 9.2 mm achieved a reflection loss below -10 dB (90% absorption) at 0.5-2.3 GHz, and the minimum value is -35.63 dB at 1.1 GHz. When the first layer and second layer are (Ni0.5Zn0.5)Fe2O4 and (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrites respectively, the laminated absorbers with double spinel ferrite layers with a thickness of 3 mm achieved a reflection loss below -10 dB at 9.9-12.3 GHz, and the minimum value is -35.3 dB at 11.7 GHz.