bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexible Antennas for Wearable Technologies
Authors: Afyf Amal , Larbi Bellarbi , Riouch Fatima , Sennouni Mohamed Adel , Nourdin Yaakoubi
Published: December 2016

Having the merits of being light-weight, energy efficient, in addition to low manufacturing cost, reduced fabrication complexity, and the availability of inexpensive flexible substrates, flexible and wearable technology is being established as an appealing alternative to the conventional electronics technologies which are based on rigid substrates. Furthermore, wearable antennas have been a topic of interest for more than the past decade, and hundreds of scientific papers can be found on the subject. This large number of publications asks for some classification in order to get an overview of the trends and challenges. To this aim, an overview of antennas for wearable technologies is proposed. This chapter is organized into three major sections. In the first part, a detailed review of wearable antennas is presented. The second part of this project deals with the flexible antennas parameters and families. Materials and fabrication methods are discussed in the third part. Wearables advantages, disadvantage and challenges are summarized in the last section.
A Dynamic Reputation-Based Incentive Scheme to Encourage Selfish Nodes in Post-Disaster Situation Using Delay-Tolerant Network
Authors: Chakrabarti Chandrima
Published: December 2016

Modern communication infrastructures that usually keep people always on-line and inform “on-the-go” have repeatedly proved to be unreliable and unavailable during and after major disasters. In those situations the prime need is to quickly re-establish minimal communication infrastructures to start rescue operations. DTN is described by a special kind of mobile ad-hoc network where sparseness, large communication delay and lack of end to end path from source to destination exist. It is evident from this fact that data forwarding is dependent on the cooperation of multiple hops in “store-carry-forward” manner. However, nodes involved in communication may sometimes behave maliciously and may non-cooperate. So, the objective in this perspective is to develop a reliable data forwarding scheme by detecting malicious activities and encourage nodes to participate in Post Disaster Communication environment. Analysis of the proposed system, its protocols and performance studies are implemented and tested using Opportunistic Network Environment (ONE) simulator.
Cross-Layer Scheme for Meeting QoS Requirements of Flying Ad-Hoc Networks
Authors: Khan Bilal Muhammad , Bilal Rabia
Published: December 2016

Recently, Flying Ad-hoc Networks (FANETs), enabling ad-hoc networking between highly mobile Unmanned Aerial Vehicles (UAVs), are gaining importance in several military, commercial and civilian applications. The sensitivity of these missions requires precise and prompt data delivery. Thus, the most important communication requirements that need to be addressed while designing FANETs are of high reliability and low latency. Considering these demands, this chapter focusses on mobility models, MAC protocols and routing protocols.
A Brief Insight into Nanorobotics
Authors: Paul Sanchita
Published: December 2016

The construction of a practical nanorobot is a definite futuristic reality. However development of a Nanorobot is associated with a multitude of challenges and limitations related mainly to its control and behavior aspects in different dynamic work environments. In this chapter a novel Nanorobot movement control algorithms in dynamic environment has being introduced. To avoid obstacles during movement trajectory, swarm intelligence based approach and for sensing, path planning, obstacle avoidance and target detection of nano-robot Quorum and RFID based approach has been utilized. Major proportion of work has been done on Microsoft Robotics Developer Studio 2008 (MSRD, 2008) along with two kinds of programming environment VPL and SPL. The chapter also includes a description of how nanorobotics technology has been applied in medical field. In this context, a non invasive method to treat a brain blood clot using nanorobots has being explained. Various other aspects of application of nanorobots has also been briefly mentioned.
Relational Dynamics
Authors: Bathory David Stefan
Published: December 2016

The effects of global warming are becoming apparent through- out the world. Europe has begun to experience more severe winters and increased rain (Steffen, 2011). Massive flooding in South Eastern Europe has devastated communities and repeatedly strains the economy of these regions resulting in mass trauma to the residents of multiple countries (Sito-Sucic & Djurica, 2014). Intergenerational effects of trauma (Bathory & Celik, 2014; Kaitz, Levy, Ebstein, Faraone, & Mankuta, 2009) have been noted to be an increasing world-wide concern. These traumatic effects are not only psychologically based but result in structural and functional changes within the brain and body (D. Bathory, 2012; D. S. Bathory, 2013a, 2013b; van der Kolk, Roth, Pelcovitz, Sunday, & Spinazzola, 2005). This chapter explores the application of decision making and Relational Dynamics to mass victims of floods by creating healing sites of sustainable energy and rural tourism to assist mass victims of natural disaster flooding.
Engineers' Perceptions of Contract Types' Performances for Highway Construction Projects
Authors: Antoniou Fani , Aretoulis Georgios N. , Konstantinidis Dimitrios K. , Kalfakakou Glykeria P.
Published: December 2016

Research focuses on the perceptions of engineers towards highway projects contract types' (CTs) performance and their respective selection criteria (SC). A questionnaire survey evaluated the CTs against the selected criteria. The SPSS database's sample consisted of 91 engineers from Greece and abroad. Factor analysis identified groups of selection criteria representing the performance of each CT and reflecting the engineers' perceptions. Patterns of changes in engineers' assessment of the contract types' performance were noted and justified. Apart from the total sample, analysis considered participants' subgroups, such as Greek and foreign engineers, and experienced engineers in the private and public sector. Nationality and experience of participants influence the factors' content. Moreover, a number of criteria tend to cluster together irrespective of CT and engineers' profile. These pairs of criteria include all uncertainties' criteria, Scope and Process Uncertainty, Contractual Difficulties and Claims, and finally Value for Money and Criticality of Schedule.
Self-Comparison
Authors: Moningka Clara
Published: December 2016

In this chapter, the author is interested in studying more about self-comparison through social media; especially in Jakarta, Indonesia. In Indonesia, social media are commonly used and widely used by various groups. As many as 93% of Internet users in Indonesia are accessing Facebook. Jakarta is even referred as the capital of a text-based social media. The use of social media can be influenced by the collective culture in Indonesia. In this case social media is not just a tool but also the social environment, in which social interaction occurs. This is also influences how individuals view themselves. The topic of the psychological effects of social media has been much discussed. A lot of research conducted on the effect of social on development of self-concept and including self-esteem. Social media becoming a place for comparing oneself to others and it turn out it has a great effect.
Alternative Sexualities and Virtual Communities
Authors: Acosta Leonor , Molinillo Sebastian , Moreno Esperanza , Gomez-Ortiz Beatriz
Published: December 2016

The purpose of this chapter is to analyze online participation on LGBT websites in Spain in order to contribute to the field of social networking site usage and the users' mode of participation with the aim of identifying their expectations and reasons to do it. The main concern is to focus on specific social network sites which are meant to ideologically and politically construct alternative sexual identities, such as lesbians, gays, transsexuals and bisexuals, which could have a difficult access to social recognition and which could be silenced on some heteronormative social networks. Uses and Gratifications Theory has been used as the basic model for the display of constructs, variables and hypotheses, to confirm the identity politics inherent in these practices, which are rather connected with social recognition than with some other needs as companionship or finding sexual partners.
Chinese International Students' Messages on the Family Forum
Authors: Wu Chenwei , Webb Lynne M.
Published: December 2016

We content analyzed the online messages of Chinese international students who are currently studying and living in the United States. We examined messages within the students' ethnic group as they sought and provided assistance to each other in understanding and acculturating to family life in the United States via a popular online forum. We randomly sampled 50 recent, original posts and their accompanying threads (147 pages of text containing 108,723 words). Thematic analysis indicated that students use the forum to achieve three objectives (seeking informational/emotional support, offering information/emotional support, offering topics for discussion) across a wide variety of family issues (e.g., conflict, child rearing/education, appropriate behaviors for husbands and wives). Users provided multiple types of assistance (e.g., informational/emotional support, topics of discussion, questions based on the original posts, self-disclosure, positive feedback, and negative feedback) to the posters.
Diverse Disabilities and Dating Online
Authors: Mazur Elizabeth
Published: December 2016

Although research indicates that almost all emerging adults in the U.S. use the internet, little is known about the online dating experiences of persons with disabilities. Particularly in developed countries, online dating currently accounts for a substantial proportion of the initiation of romantic relationships and promises numerous advantages for persons with disabilities. Online dating includes a way to escape disability stigma, at least initially, access to a wide network of potential partners, and a convenient, private, and efficient method of meeting them. Online daters can be strategic in how they present both themselves and their disabilities, the manner in which they communicate with potential partners, and whether they join a large, popular dating site or a specialized disability-oriented one. The chapter discusses how the nine-step process of online dating might differ for or challenge emerging adults with various types of disabilities, sharing relevant research and media examples when available.
Influence of Social Media on Dating Relationships of Emerging Adults in Nigerian Universities
Authors: Fawole Olufemi Adeniyi , Osho Olasunkanmi Adebiyi
Published: December 2016

Social media play important roles in creating a person's sense of reality, recreating face-to-face interactions on the web by allowing people to interact either publicly of privately. Social networking sites helps in maintaining relationship with individuals who may not be closer to one; used to express romantic relationships through profile pictures or posts on social networking sites like Facebook, Twitter, Uber Social etc. This chapter focused on the influence of Facebook on communication between emerging adults in dating relationships. A total of seventy-seven participants comprising students from the University of Lagos, Nigeria aged between 19 and 29 years, took part in different focus group discussions. Data was analyzed using thematic analysis. The results revealed that majority of the dating couples spent long hours on Facebook daily and they did not feel comfortable with the hours spent on Facebook by their partner chatting with friends on a regular basis.
Victimization or Entertainment?
Authors: Brenick Alaina , Flannery Kaitlin M. , Rankin Emily
Published: December 2016

As texting continues to serve as an increasingly common method of communication among emerging adults, increases in rates of sexting, or sending sexually explicit messages, pictures, or videos, have also been observed. While consensual sexting can facilitate intimacy in relationships, when used as a tool to victimize others, it has been shown to yield a range of negative outcomes- from embarrassment to severe depression and suicide. This chapter aims to review the existing literature on emerging adults' engagement in and evaluations of sexting, while also considering the risks associated with sexting victimization. The role that individual characteristics, such as attachment style and rejection sensitivity, play in the relationship between experiences with and evaluations of using sexting as a tool for victimization will also be explored.
Collaborative Musical Theatre
Authors: Prince Penny
Published: December 2016

The author describes her process of utilizing collaborative musical theatre as a teaching tool in three settings. These include an elementary school in the Bronx, New York, which adheres to the theory of Multiple Intelligences; undergraduate and graduate music education courses at Lehman College, City University of New York; and in a College/Community Collaborative Musical Theatre Project at Lehman College. The chapter depicts how the collaborative process closely resembles the goals of the Multiple Intelligences theory by the way it stimulates, encourages and nurtures the many capacities and ways of expression of the participants: Intrapersonal, Interpersonal, Mathematical/Logical, Spatial, Kinesthetic, Linguistic, Musical and Naturalistic, and therefore, serves as an effective, all-encompassing teaching tool.
Engaging Urban Youth in Critical Media Literacy
Authors: Cho Hyesun , Gomabon Randy
Published: December 2016

This chapter describes how urban youth engaged in critical media literacy in the high school classroom by creating public service announcement (PSA) videos. The study delineates the process in which critical media literacy was implemented into diverse urban high school classrooms in Hawaii over a period of three years. The process included (1) acquiring technological and linguistic skills; (2) critically analyzing media texts; and (3) producing media on social issues. The data were collected from students' reflection journals, interviews with students and teachers, students' electronic portfolios, and participant observations by the researchers/teachers. Students expressed their voice toward positive social actions by producing PSAs on a range of social issues, such as poverty and discrimination. Building on multiliteracies and critical media literacy, this chapter argues for the importance of critical media literacy pedagogy that is deliberate to make curricular space for students' reflections and examinations of social issues.
Flying Faster than the Birds and the Bees
Authors: Burnes Theodore
Published: December 2016

The need for multicultural education to analyze human sexuality education is an area of critical need in research and practice. Many current human sexuality learning experiences contain practices that are shaming to learners, producing values that problematize sexuality. The author of this chapter introduces a sex-positive approach to human sexuality education, honoring multicultural education by intentionally understanding sex-positivity outside of a White, western context. Implications of this approach for education research, practice, training, and advocacy are discussed.
One Teacher's Journey
Authors: Bechard Amber
Published: December 2016

As our sociopolitical context evolves, student populations and teaching expectations become more complex. Teachers who entered the profession under one pretense are finding themselves faced with an entirely different set of circumstances: demographic shifts, increasingly diverse learners, curricular mandates, high-stakes accountability, technological advancements, globalization—the list continues. As the educational environment evolves, so must teacher identities. Contemporary teachers are tasked with creating an entirely new lens from which to develop new techniques and design more complex lessons to reach the diversity of students in their classrooms. This chapter traces one teacher's evolving identity and practice amidst the changing sociopolitical context of education. The author's autobiographical narrative depicts the impact of influential mentors, transformative moments in international teacher travel experiences, vignettes from 28 years as a classroom teacher, and specific instructional techniques developed to ensure effective student engagement in a pluralistic environment.
Value Relevance of Accounting Information in Capital Markets
Authors: Rossi James A.
Published: December 2016

By way of reference to a comparative analysis between three selected jurisdictions from the Middle East, Africa and Asia, this chapter aims to investigate the trends in value relevance of accounting information in these stock markets and exchanges. Further, amongst other goals and objectives, this chapter also seeks to illustrate why in light of recent developments which have resulted in decline of reliability - as a valued attribute, relevance and reliability still constitute fundamental characteristics which are required in the development of global stock markets and economies. It consolidates this aim in view of recent IASB and FASB's initiatives and the resulting framework which categorizes understandability, comparability, timeliness and verifiability as enhancing qualitative characteristics of accounting information.
Revisiting the Value Relevance of Accounting Information in the Italian and UK Stock Markets
Authors: Rossi James A.
Published: December 2016

This chapter aims to investigate the results of the value relevance of accounting information with reference to the study: “The value relevance of accounting information in the Italian and UK stock markets”. Results revealed from this study are as follows: - First, evidence shows the greater value relevance of accounting information in Italy than in the UK, even if this result must be explained according to the sample's characteristics. Second, the study underlines that in Italy the most value relevant accounting data refer to earnings while in the UK the focus is mainly on cash flows. The chapter also seeks to contribute to the gap in the literature on the value relevance of accounting information in the UK and Italy. In so doing it investigates the relevance and reliability of results derived in this study, their applicability to current market developments – as well as recent fluctuations and volatility in the financial markets.
The Determinants of Stock Market Development in Emerging Economies
Authors: Newton Sarah
Published: December 2016

“The chief concerns of EMEs (emerging market economies) in relation to their financial systems remain developmental rather than regulatory: increasing financial savings to accelerate growth and development, and deepening their financial system to develop long term funding instruments for infrastructure financing, absorb large inflows of capital to counter the uphill backwash from EMEs to AMEs, reduce the cost of capital and reduce the leads and lags in monetary policy transmission. Advanced market economies (AMEs), on the other hand, need major regulatory changes that inoculate them more effectively against the new risks their financial systems face.” As well as investigating these observations, this chapter is aimed at investigating the validity of Efficient Markets Hypothesis and Efficient Capital Markets Hypothesis in emerging economies – as contrasted with advanced market economies. In so doing, it aims to contribute to the extant literature on stock market liquidity and liquidity in capital markets.
The Value Relevance of Financial and Non-Financial Information
Authors: Saha Amitav , Bose Sudipta
Published: December 2016

Value-relevance research is an important domain of modern capital market research. Accounting researchers have used the value-relevance research framework in many ways with the aim of measuring whether accounting information has a predicted association with equity market values. One of the most widely used models in value-relevance research is a modification of the Ohlson (1995) market valuation model in which the market value of a firm's equity is presumed to be a function of its book value of equity and abnormal earnings. Furthermore, using the Ohlson (1995) model, accounting researchers have documented the value relevance of different types of financial and non-financial information. Drawing on a selected number of recently published studies that have documented the value relevance of different types of financial and non-financial information, this chapter reviews and integrates recent findings, highlighting challenges and providing future directions for further research in this area.
Cybersecurity and Data Breaches at Schools
Authors: Shen Libi , Chen Irene , Su Anchi
Published: December 2016

Has anyone considered his/her family information going viral and through his/her trusted, chosen school district? This is an age where a mis-sent e-mail with student data can represent enormous liabilities, and a lost laptop can cause newspaper headlines. School institutes are facing new cyber security challenges in the Information Age. A number of school institutes were grappling with the loss of confidential information and protecting students on the Internet. How should school authorities react in case of data breach? What should they do to prevent data breaches at schools? What are upcoming trends in cybersecurity? The purpose of this chapter is to explore data breaches at K-12 schools as well as to examine the ways to improve cybersecurity. In this chapter, the researchers attempt to provide suggestions, solutions, and recommendations on cybersecurity after examining the problems of data breaches.
Connections at the Family Level
Authors: Martin Caitlin K. , Pinkard Nichole , Erete Sheena , Sandherr Jim
Published: December 2016

We discuss the multiple roles played by parents and other caring adults in the homes of young STEM learners, highlighting existing knowledge and connections as well as desired supports. We report on a series of workshops for parents and other caring adults, held in conjunction with a 20-week computational making program for middle school girls from underrepresented communities. The workshops accomplish three tasks: 1. build a community of participants who engage in collaborative work and share best practices, resources, and knowledge; 2. introduce a framework of roles to ground what participants do to support the girls' STEM learning; and 3. engage participants in technical design processes as they work through projects similar to those completed by the middle school girls in the program. We share insights and challenges that emerged from our analysis of these workshops, and present ideas for refinement and adaptation of our workshop model based upon lessons learned.
Access, Power, and the Framework of a CS Education Ecosystem
Authors: Bobb Kamau , Brown Quincy
Published: December 2016

In the 21st century, the ability to shape, drive and innovate in computing spaces is unequivocally associated with power. However, students of color disproportionately experience the afflictions of poverty and powerlessness. Moving them from being consumers to producers of technology is one approach for changing that narrative. In the context of Computer Science (CS) education, there is much more at stake for students of color than simply joining the technical workforce. The shift to being producers of technology has disproportionate significance to students of color who would be able to perceive themselves as being in positions of technical power. This shift must begin in the current reality of the CS education ecosystem. Applying best practices for increasing diversity in engineering, we argue for a reformation of the CS education ecosystem that redistributes access and power to empower future generations of students of color, thereby broadening participation in CS.
Stochastic Evaluation of Capacity and Demand Management of the Airline Industry
Authors: Tesfay Yohannes Yebabe
Published: December 2016

In the airline industry, the term load factor defined as the percentage of seats filled by revenue passengers and is used to measure efficiency and performance. This metric evaluates the airlines capacity and demand management. This paper applies stochastic models to analyse the load factor of the Association European Airlines (AEA) for flights of Europe - North Africa and Europe- Sub Saharan Africa. The estimation result prevails that the airlines have better demand management in the flights of Europe- Sub Saharan Africa than in the flight of Europe - North Africa. However, the capacity management of the airlines is poor for both regional flights. The autocorrelation structures for the load factor for both regional flights have both periodic and serial correlations. Consequently, the use of ordinal panel data models is inappropriate to capture the necessary variation of the load factor of the regional flights. Therefore, in order to control for the periodic autocorrelation, the author introduces dynamic time effects panel data regression model. Furthermore, in order to eliminate serial correlation the author applies the Prais–Winsten methodology to fit the model. Finally, the author builds realistic and robust forecasting model of the load factor of the Europe- North Africa and Europe-Sub Saharan Africa flights.
Brand Awareness Quotient
Authors: Ratra Komal , Neelam Netra
Published: December 2016

There is a need to appropriately measure the effectiveness of Employer branding initiatives taken by an organization. There are a lot of questions to be addressed while measuring the effectiveness of the past or existing initiatives and formulating a new Employer branding strategy such as: Do the objectives of the Employer branding completely meet the initiative? What is the reach of the initiatives? Whether to continue with the same initiative or not in future? Hence while designing a new improved Employer branding strategy, there needs to be an appropriate initiative measurement methodology which can address the above questions quantitatively. This paper is an attempt to create A matrix “Brand Awareness Quotient” which will help in measuring the efficacy and support decision making for formulating the new strategy the same. This quantitative way of scoring and analyzing each and every initiative provides a 360-degree overview of the complete Employer branding strategy of the organization.
Decision Trees and Financial Variables
Authors: Rada Roy , Wimmer Hayden
Published: December 2016

A decision tree program for forecasting stock performance is applied to Compustat's Global financial statement data augmented with International Monetary Fund data. The hypothesis is that certain Compustat variables will be most used by the decision tree program and will provide insight as to how to make investing decisions. Surprisingly, the authors' experiments show that the most frequently used variables come from the International Monetary Fund and that variables provided exclusively for Financial Industry stocks were not useful for forecasting financial stock performance. These experiments might be part of a constellation of such experiments that help people map financial forecasting problems to the variables most useful for solving those problems. The research shows the value of using decision tree methodologies as applied to finance.
Efficient Implementation of Hadoop MapReduce based Business Process Dataflow
Authors: Meddah Ishak H.A. , Belkadi Khaled , Boudia Mohamed Amine
Published: December 2016

Hadoop MapReduce is one of the solutions for the process of large and big data, with-it the authors can analyze and process data, it does this by distributing the computational in a large set of machines. Process mining provides an important bridge between data mining and business process analysis, his techniques allow for mining data information from event logs. Firstly, the work consists to mine small patterns from a log traces, those patterns are the workflow of the execution traces of business process. The authors' work is an amelioration of the existing techniques who mine only one general workflow, the workflow present the general traces of two web applications; they use existing techniques; the patterns are represented by finite state automaton; the final model is the combination of only two types of patterns whom are represented by the regular expressions. Secondly, the authors compute these patterns in parallel, and then combine those patterns using MapReduce, they have two parts the first is the Map Step, they mine patterns from execution traces and the second is the combination of these small patterns as reduce step. The results are promising; they show that the approach is scalable, general and precise. It reduces the execution time by the use of Hadoop MapReduce Framework.
The Role of Technology and Social Media in Tacit Knowledge Sharing
Authors: Dalkir Kimiz
Published: December 2016

Technology-mediated knowledge sharing has become almost unavoidable given the globalization of work. Co-workers are not necessarily in close enough proximity to have face-to-face interactions despite the fact that these are the most effective means of sharing knowledge. Information and communication technologies (ICTs) differ in a number of key attributes. While traditional technologies are well suited for sharing explicit knowledge, that has been articulated and documented as text or other media, tacit knowledge is more challenging. Tacit knowledge is typically experiential knowledge that is very difficult to put into words or document in any way. This paper proposes an ICT selection method based primarily on media richness (extent to which multimedia content can be shared) and social presence (extent to which people feel they are connecting with other people and not technology). These characteristics can serve as a preliminary basis to select the most appropriate channel for sharing tacit knowledge.
Efficient Vision-based Smart Meter Reading Network
Authors: Chen Ching-Han , Chen Ching-Yi , Hsia Chih-Hsien , Wu Guan-Xin
Published: December 2016

For building the big data collection infrastructure, a vision-based smart meter-reading network and its gateway is provided for a community gas supply system that uses traditional mechanical meters. In the network architecture, the gas meter readings are captured by embedded image sensor nodes and then transmitted to a newly designed gateway for image recognition and are collected in the embedded database of gateway. The Web-based monitoring system designed using HTML5 is applicable to a mobile device which allows a user to monitor household gas consumption and history and allows a gas company to develop an effective energy management system to analyze community users' energy consumption models using the big data collected in the database.
Research on Torsion Beam with High Strength Steel Materials Forming
Authors: Yu Kai , Xiong Fei , Liu Kai , Cheng He Fa
Published: December 2016

In order to study the temperature field, stress field, strain field, thinning rate and phase distribution in the hot forming process of torsion beam. The finite element software was used in this paper. Study found: Due to the different regions of part contact with the mould in the different order, the maximum principal strain area is in the highest temperature region, the maximum principal stress area is located in the lower temperature region; In the process of hot forming, the slow cooling rate of the part is 77°C/S, which is greater than critical cooling rate of martensitic transformation that is 30°C /S; With the increase of the initial temperature of sheet metal, the maximum content of austenite and thinning rate of the parts increase, and the forming quality of the parts decreases; With the increase of stamping speed, the thinning rate of parts is violent fluctuation. When the stamping speed is too large, the temperature of parts is greater than the martensite transformation temperature in some regions at the end of forming; With the increase of friction coefficient, the thinning rate and the minimum content of martensite increase at the beginning and then decrease, the maximum content of austenite decreases at the beginning and then increases. Research shows that: when the initial temperature of blank is 850°C, stamping speed is75mm/s and coefficient of friction is 0.45, the quality of the parts is the best and thinning rate is 5.804%. At the end of forming, the minimum temperature of parts is 285°C; minimum martensite content is 75.63% and the maximum austenite content is 24.36%.
Method Studied on the Tensile and Compression Strength Prediction of Friction Stir Welding Aircraft Panel
Authors: Hu Zhen Dong , Chen Yang Liu , Song Xin
Published: December 2016

The tensile and compression strength of the Z shaped stiffened-welded plate is studied in this paper. Through the analysis of the main influential factors of the panel strength, the theoretical calculation formula of the tensile and compression strength of the panel plate which are verified by the experimental values is established in this paper,. And the tensile strength prediction value is 8.4% larger than the experimental value while the compression strength prediction value is 4.36% smaller than the experimental value. This method can provide reference for the selection of welding structure.
The Deduction of Double-Layer Material’s Dielectric Constant in High Q Cavity
Authors: Li En , Zeng Meng Wei , Gao Chong , Xu Jin Qiu
Published: December 2016

In this paper, the method applied to test permittivity and permeability of multilayer materials is introduced. On the basis of research from Professor Li En, the algorithm to measure each layer’s permittivity and permeability of a double-layer material is derived by using exact field solution. When the double-layer material of which each layer’s permittivity and permeability are unknown is putted into the High Q Cavity, the every layer’s electromagnetic field distribution in High Q Cavity can be derived by theoretical analysis. According to the electromagnetic field distribution and boundary condition, the algorithm that is used to calculate permittivity and permeability can be derived. In this algorithm, the unknown parameters include resonant frequency of operating mode TE01p and the quality factor can be obtained by the High Q Cavity. In order to verify the validity of this proposed algorithm, a double-layer material composed of beryllia and quartz is selected.
Materials Machining Study of Titanium Alloy Using a High Speed Camera
Authors: Polishetty Ashwin , Littlefair Guy , Tumma Sanjay
Published: December 2016

The research aim is to study and analyze the shear zone by application of merchant circle during machining of titanium alloy (Ti6Al4V). The thermo-mechanical reaction during machining plays an important role in defining machinability of titanium alloys. The scientific community is concerned about machining of titanium alloy due to problems occurring in the shear zone that affect tool life. Studying the cutting action contributes to understanding and addressing these problems effectively. For this purpose, an experimental setup, utilizing a high speed camera will be used to study the shear zone. The shear zone characteristics are studied by analyzing the images captured by a high speed camera placed near to the shear zone during machining. The experimental design consists of conducting a series of turning trials using combination of cutting parameters namely constant spindle speed (n) 770 rpm; feed rate (f) of 2 and 4 mm/rev; and depth of cut (d) of 1 and 2 mm. The length of cut (L) of 10 mm remains constant and no coolant is used for all trials. The images obtained from the camera are analyzed against the theory of orthogonal cutting using merchants circle.
Study on Electro-Discharge Machining Technology of Superalloy Impeller
Authors: Li Yan , Ren Lian Sheng , Liu Jian Yong
Published: December 2016

Electro-discharge machining (EDM) is one of the preferred machining methods for closed impeller. A 3D model of the closed impeller was obtained by using three-dimensional software. Combined with EDM processing method, two kinds of partition schemes were proposed and a better partition scheme was gotten. A set of electrodes were designed based on the partition scheme. Motion simulation and interference checking were carried out. Experiments were conducted and a qualified closed impeller was machined successfully. So the design method for electrodes and the feasibility of processing are proven.
Research and Manufacture of Microwave Material Automatic Measurement System of Slotted Line
Authors: Cui Hong Ling , Ji Zhong Jian , Li En , Zheng Meng Long
Published: December 2016

In this paper we designed a microwave material measurement system by using slotted line waveguide.Compared with the VNA,this system have the smaller size and lower cost.Considering the test technical specifications, test methods of complex permittivity of microwave materials, and the performance of test system,we used the short-circuited line method to test the complex permittivity of the microwave material, and used the TI DSP [1] (TMS320C6747) as a minimum core processor system. Developed a set of X-band automatic slotted line system, this paper carried out the design of the prototype test system and the programing of the system's automated testing software. Finally,we used the measuring system to test two kinds of sample(fiberglass and quartz) and compare the result with the other result testing by the VNA.it is not difficult to conclude the measured result is relatively accurate.
Study on Microstructure and Mechanical Properties of Explosive Welding Composite Plate
Authors: Wang Zhi Ling
Published: December 2016

We used the Q345R/ composite panels by explosive composite method,and studied the microstructure and properties of the composite plate by the means of optical microscope and mechanical property test in this paper. We can see that the interface of explosive composite board is in a wave shape, the microstructure in the region next to the bonding interface of the composite plate consists of three parts: distorted grain area, fibrous zone and fine grained region. The composite explosive plate is still of high tensile strength and ductility, and its impact absorbing energy is to 68J, the hardness of the interface for the composite plate of 304 is higher and rise more remarkable than the base metal of Q345R.
New Method for Diamond-Like Carbon Deposition on Ceramic Cutting Tools in Vacuum-Arc Plasma
Authors: Volosova Marina
Published: December 2016

A study of diamond-like carbon coatings deposition has been carried out. The coatings were deposited on ceramic cutting tools. Vacuum-arc plasma has been used for deposition. Dependencies of the coatings microhardness and density on the tools bias voltage U are presented. The microhardness reaches 50 GPa at U=100 V. With increasing U and temperature it decreases to 15 GPa at U=500 V. Effect of the coatings on oxide ceramics properties was revealed. They were used for lathe turning of hardened steel. The tests proved a high efficiency of the coatings.
The Natural Aging Effect on the Activation Energy of the Precipitation Processes in the Al-Mg-Si Alloy
Authors: Hamdi Ines , Boumerzoug Zakaria
Published: December 2016

The precipitation sequence of an Al-Mg-Si alloy depends on many parameters. In this study the natural aging effect on the activation energy of the precipitation sequence in the Al-Mg-Si alloy have been investigated by differential scanning calorimetry (DSC). The precipitation sequence of an Al-Mg-Si alloy has been established. The activation energy of the precipitation process was calculated using Kissinger model. The results obtained using this method showed a change in the activation energy for all precipitated phases. The activation energy of the metastable phases (β″ and β′) and the stable phase β formation in the Al-Mg-Si alloy aged at room temperature have been determined.
Design and Numerical Analysis of Leaf Spring Using Composite Materials
Authors: Gaffar Abbas M.Kamaleldin , Niakan Aliasghar , Chia Chee Ming , Singh Ramesh , Teo Patrick
Published: December 2016

This paper describes design and analysis of composite a leaf spring made of E-glass/epoxy reinforced polymer. The aim of this paper is to introduce a new design as well as to compare the stiffness, load capacity and weight reduction of composite material with that of steel leaf spring. A comparative study of steel and composite material with respect to weight and strength was carried out on ANSYS 16.2 under the same boundary conditions in order to obtain the maximum deflection and stress. It found that the maximum deflection and stress in steel are higher than E-glass/epoxy, which recorded lowest deflection and stress by 51.7% and 57.1%, respectively. E-Glass/epoxy composite material reduced the weight of leaf spring 67.7 % compared to steel leaf spring.
Milling of Dielectric Ceramics by Fast Argon Atoms
Authors: Grigoriev Sergei
Published: December 2016

A new method for dielectric materials milling has been developed. Instead of well-known ion milling used for metals the dielectrics were processed by broad beams of fast argon atoms. The fast atoms were produced due to charge exchange collisions of accelerated ions. Plasma emitter of the ions was generated in hollow cathode glow discharge. Emissive grid of a circular cross-section beam source consisted of six segments. Energy of the fast atoms ranged from 1 to 3 keV. The beam source was used for production of contoured grooves on flat surfaces of hard ceramic materials. On the surface of movable seal ring made of α-corundum were produced grooves with depth of 20±0.5 μm and roughness of Ra ≈ 0.4 µm. The rate of α-corundum etching amounted to 3 μm/h.
Optimal Design of Multi-Layer Absorbent Honeycomb Cellular Composite Material Structure
Authors: Zhang Xiao Hu , Sun Qin , Xu Shao Feng
Published: December 2016

Next generation aircraft rely heavily on lightweight honeycomb composite structures for improved electromagnetic wave scattering and stealth capabilities. This paper investigated the optimal design and analysis methods of multi-layer absorbent honeycomb composite structures. The effective electromagnetic parameters of anisotropic object were calculated accompany with the formulation of reflectivity for incident wave. A genetic algorithm is employed to optimize the RCS of the absorptive honeycomb composite in desired angle range. The thickness and the volume fraction of absorptive materials are adopted to optimize the effective electromagnetic parameters under different polarized modes. Single and multi layer absorptive honeycomb composite were been studied. The results show that the thickness of the first absorptive layer plays a key role on the reflectivity of honeycomb structure. Therefore, it is advised to arrange the absorptive layers such that the EM absorption properties increases from outside to inside.
The Low Temperature Liquefaction Characteristic Test of Sulfur Hexafluoride Gas Used in Electrical Equipment
Authors: Li Guo Xing , Li Lin , Jiang Zi Qiu
Published: December 2016

To study the low temperature liquefaction characteristics of SF6 for the operation security of electric equipments in cold area, the writer carries out the low temperature liquefaction test of SF6 respectively in laboratory and outdoors by using SF6 gas low temperature experimental apparatus. According to the results of the test and the Beattie-Bridgman SF6 empirical formula, SF6 gas state parameter curve is plotted and a concise practical SF6 gas state parameter formula is got. This formula is more applicable to electric equipments outdoors. The results show that SF6 gas is easier to liquefy in cold area, and the liquefaction temperature of SF6 gas is in proportion to gas pressure. So the liquefaction temperature of electric equipments operated in cold area should not be higher than the lowest area temperature. Otherwise, measures must be taken to prevent SF6 gas from liquefaction.
Fracture and Failure Mechanism Analysis of the 45CrNiMoVA Gear
Authors: Qin Hao , Tang Xiao Ying , Yao Wen Qing , Wu Feng Qi
Published: December 2016

Aiming at the failure mechanism of 45CrNiMoVA gear, the FEM method, fracture theroy caculuation and metallographic examination are employed to analyze the gear failure form, working stress condition and microscopic metallographic structure. The conclusion is that the dominated reasion of the gear fracture failure is the insufficient fatigue strength, and the defect of the relative craft and testing method are the root causes. Some specific suggessions are put forward for the gear failure mechanism simultaneously.
Influence of Materials Hardenability Parameters on the Machine Parts Characteristics after Unloading
Authors: Ogar P.M. , Gorokhov D.B.
Published: December 2016

This paper studies the problem of the relative area changing on a decrease of the load applied to the joint of roughness surfaces. The penetration of a rigid rough sphere (indenter) into the elastic hardenable half-space is initially considered, then the elastic crater restoring by unloading is considered. To defining elastic-plastic material, Hollomon’s power law is used. To describe a contact of a rigid rough surface with an elastic plastic half-space, the discrete model of a rough surface is used. Microasperities are represented as a set of identical spherical segments, the height distribution of which corresponds to the bearing profile curve of the real surface. The dependence the dimensionless force elastic-geometric parameter Fq on a relative amount of indentation ε at loading and the dependence of analogous parameter Fqe on amount of ε-Dε at unloading are obtained. The relations of relative contact areas h and he on dimensionless loading Fq and Fqe at loading and unloading for different values of a hardening exponent n and parameter are given. The obtained results are of practical importance for the performance prediction of fixed machine elements’ joints at the design stage, in particular for tightness supply of flange couplings and high pressure vessels seals.
Stress Intensity Factor of Interface Crack in the Cermet Cladding Material Structure under Steady Mechanical-Thermal Coupled Loads
Authors: Yang Jun Ru , Chi Yu Rong , Wang Ming Lan , Zhu Ran
Published: December 2016

In the paper, the crack parallel to and lying on the interface in the hard cermet cladding material structure is taken as the study object. Theoretical models of the stress intensity factor (SIF) of the interface crack under steady mechanical-thermal coupled loads are built. Based on which the interface crack SIFs in the cermet cladding material of 5Cr2Ni08C/Q235 under the same loads are analyzed with the finite element method. The crack SIF change laws under the coupled loads are obtained. KI increases with the increase of the temperature, the mechanical load and the crack length respectively. The absolute values of KII have the same change laws. And KI corresponding to the coupled loads is bigger than that to the single load. The research results are very important to develop the interface crack propagation theory. And they will also improve the optimization designs of the hard cladding material parts, and expand their applications.