952 resultados para TCP connection


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The IEEE Wireless LAN standard has been a true success story by enabling convenient, efficient and low-cost access to broadband networks for both private and professional use. However, the increasing density and uncoordinated operation of wireless access points, combined with constantly growing traffic demands have started hurting the users' quality of experience. On the other hand, the emerging ubiquity of wireless access has placed it at the center of attention for network attacks, which not only raises users' concerns on security but also indirectly affects connection quality due to proactive measures against security attacks. In this work, we introduce an integrated solution to congestion avoidance and attack mitigation problems through cooperation among wireless access points. The proposed solution implements a Partially Observable Markov Decision Process (POMDP) as an intelligent distributed control system. By successfully differentiating resource hampering attacks from overload cases, the control system takes an appropriate action in each detected anomaly case without disturbing the quality of service for end users. The proposed solution is fully implemented on a small-scale testbed, on which we present our observations and demonstrate the effectiveness of the system to detect and alleviate both attack and congestion situations.

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Mutually unbiased bases (MUBs) have been used in several cryptographic and communications applications. There has been much speculation regarding connections between MUBs and finite geometries. Most of which has focused on a connection with projective and affine planes. We propose a connection with higher dimensional projective geometries and projective Hjelmslev geometries. We show that this proposed geometric structure is present in several constructions of MUBs.

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Advances in solid-state switches and power electronics techniques have led to the development of compact, efficient and more reliable pulsed power systems. Although, the power rating and operation speed of the new solid-state switches are considerably increased, their low blocking voltage level puts a limits in the pulsed power operation. This paper proposes the advantage of parallel and series configurations of pulsed power modules in obtaining high voltage levels with fast rise time (dv/dt) using only conventional switches. The proposed configuration is based on two flyback modules. The effectiveness of the proposed approach is verified by numerical simulations, and the advantages of each configuration are indicated in comparison with a single module.

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This paper explores Indigenous Australian women’s understanding of wellness, through the lens of social and emotional wellbeing. The authors use a “yarning” approach to explore how wellness is important to Indigenous women who live in North Brisbane (Australia). They discuss the benefits of yarning and its strength as a methodology for conducting research and building activism within Indigenous Australian communities. They argue that, for Indigenous Australian women, wellness is linked to a sense of wholeness and strongly related to the feeling of connection that women get from meeting together and having time for women’s business. They describe the way that their research project developed into a community summit focused on Indigenous women’s wellness.

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Music and dance are art forms that involve a full mind-body experience, integrating the cognitive, affective and kinesthetic domains. To engage in creating music and dance is to use information to express oneself and communicate. In this chapter I explore the information experience of two distinct groups: those who compose music for an audience, and those who dance socially with a partner. For the composer, information sources can be a stimulus for creation. Sounds, feelings, moods, images, ideas and life experiences can trigger a creative idea. These ideas are shaped by existing musical styles and structures, and by the composer’s personal aesthetic. The intention of the composer is to communicate their expressive ideas to an audience. For the social dancer, information sources are those used to communicate with a partner. There is no intention to perform for an audience. A social dancer aims to express the music and style of the dance while creating a strong connection with their partner. Information sources include the music, the partner’s body, the emotions generated by the dance, the position of other couples on the floor and the feeling of the floor. Use of information in the arts is an under-researched experience. Most information studies are based on the assumption that information is documentary and codified. Subjective and affective information is rarely recognised and legitimised. Information-as-it-is-experienced through creative practice such as music and dance is holistic in acknowledging mind, body and spirit as well as traditional documentary forms of information. This chapter draws on empirical research to illustrate experiencing information as creating and expressing.

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Despite advances in the field of workflow flexibility, there is still insufficient support for dealing with unforeseen exceptions. In particular, it is challenging to find a solution which preserves the intent of the process as much as possible when such exceptions are encountered. This challenge can be alleviated by making the connection between a process and its objectives more explicit. This paper presents a demo illustrating the blended workflow approach where two specifications are fused together, a "classic" process model and a goal model. End users are guided by the process model but may deviate from this model whenever unexpected situations are encountered. The two models involved provide views on the process and the demo shows how one can switch between these views and how they are kept consistent by the blended workflow engine. A simple example involving the making of a doctor's appointment illustrates the potential advantages of the proposed approach to both researchers and developers.

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The increasing demand for mobile video has attracted much attention from both industry and researchers. To satisfy users and to facilitate the usage of mobile video, providing optimal quality to the users is necessary. As a result, quality of experience (QoE) becomes an important focus in measuring the overall quality perceived by the end-users, from the aspects of both objective system performance and subjective experience. However, due to the complexity of user experience and diversity of resources (such as videos, networks and mobile devices), it is still challenging to develop QoE models for mobile video that can represent how user-perceived value varies with changing conditions. Previous QoE modelling research has two main limitations: aspects influencing QoE are insufficiently considered; and acceptability as the user value is seldom studied. Focusing on the QoE modelling issues, two aims are defined in this thesis: (i) investigating the key influencing factors of mobile video QoE; and (ii) establishing QoE prediction models based on the relationships between user acceptability and the influencing factors, in order to help provide optimal mobile video quality. To achieve the first goal, a comprehensive user study was conducted. It investigated the main impacts on user acceptance: video encoding parameters such as quantization parameter, spatial resolution, frame rate, and encoding bitrate; video content type; mobile device display resolution; and user profiles including gender, preference for video content, and prior viewing experience. Results from both quantitative and qualitative analysis revealed the significance of these factors, as well as how and why they influenced user acceptance of mobile video quality. Based on the results of the user study, statistical techniques were used to generate a set of QoE models that predict the subjective acceptability of mobile video quality by using a group of the measurable influencing factors, including encoding parameters and bitrate, content type, and mobile device display resolution. Applying the proposed QoE models into a mobile video delivery system, optimal decisions can be made for determining proper video coding parameters and for delivering most suitable quality to users. This would lead to consistent user experience on different mobile video content and efficient resource allocation. The findings in this research enhance the understanding of user experience in the field of mobile video, which will benefit mobile video design and research. This thesis presents a way of modelling QoE by emphasising user acceptability of mobile video quality, which provides a strong connection between technical parameters and user-desired quality. Managing QoE based on acceptability promises the potential for adapting to the resource limitations and achieving an optimal QoE in the provision of mobile video content.

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Scaffolds for bone tissue engineering should be designed to optimize cell migration, enhance new bone formation and give mechanical support. In the present study, we used polycaprolactone-tricalciumphosphate (PCL/TCP) scaffolds with two different fibre lay down patterns which were coated with hydroxyapatite and gelatine as an approach for optimizing bone regeneration in a critical sized calvarial defect. After 12 weeks bone regeneration was quantified using microCT analysis, biomechanical testing and histological evaluation. Notably, the experimental groups containing coated scaffolds showed lower bone formation and lower biomechanical properties within the defect compared to the uncoated scaffolds. Surprisingly, the different lay down pattern of the fibres resulted in different bone formation and biomechanical properties; namely 0/60/120° scaffolds revealed lower bone formation and biomechanical properties compared to the 0/90° scaffolds in all the experimental groups. The different architecture of the scaffold fibres may have an effect on nutrition supply as well as the attachment of the newly formed matrix to the scaffold. Therefore, future bone regeneration strategies utilising scaffolds should consider scaffold architecture as an important factor during the scaffold optimisation stages in order to move closer to a clinical application.

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Effective digital human model (DHM) simulation of automotive driver packaging ergonomics, safety and comfort depends on accurate modelling of occupant posture, which is strongly related to the mechanical interaction between human body soft tissue and flexible seat components. This paper presents a finite-element study simulating the deflection of seat cushion foam and supportive seat structures, as well as human buttock and thigh soft tissue when seated. The three-dimensional data used for modelling thigh and buttock geometry were taken on one 95th percentile male subject, representing the bivariate percentiles of the combined hip breadth (seated) and buttock-to-knee length distributions of a selected Australian and US population. A thigh-buttock surface shell based on this data was generated for the analytic model. A 6mm neoprene layer was offset from the shell to account for the compression of body tissue expected through sitting in a seat. The thigh-buttock model is therefore made of two layers, covering thin to moderate thigh and buttock proportions, but not more fleshy sizes. To replicate the effects of skin and fat, the neoprene rubber layer was modelled as a hyperelastic material with viscoelastic behaviour in a Neo-Hookean material model. Finite element (FE) analysis was performed in ANSYS V13 WB (Canonsburg, USA). It is hypothesized that the presented FE simulation delivers a valid result, compared to a standard SAE physical test and the real phenomenon of human-seat indentation. The analytical model is based on the CAD assembly of a Ford Territory seat. The optimized seat frame, suspension and foam pad CAD data were transformed and meshed into FE models and indented by the two layer, soft surface human FE model. Converging results with the least computational effort were achieved for a bonded connection between cushion and seat base as well as cushion and suspension, no separation between neoprene and indenter shell and a frictional connection between cushion pad and neoprene. The result is compared to a previous simulation of an indentation with a hard shell human finite-element model of equal geometry, and to the physical indentation result, which is approached with very high fidelity. We conclude that (a) SAE composite buttock form indentation of a suspended seat cushion can be validly simulated in a FE model of merely similar geometry, but using a two-layer hard/soft structure. (b) Human-seat indentation of a suspended seat cushion can be validly simulated with a simplified human buttock-thigh model for a selected anthropomorphism.

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Deploying wireless networks in networked control systems (NCSs) has become more and more popular during the last few years. As a typical type of real-time control systems, an NCS is sensitive to long and nondeterministic time delay and packet losses. However, the nature of the wireless channel has the potential to degrade the performance of NCS networks in many aspects, particularly in time delay and packet losses. Transport layer protocols could play an important role in providing both reliable and fast transmission service to fulfill NCS’s real-time transmission requirements. Unfortunately, none of the existing transport protocols, including the Transport Control Protocol (TCP) and the User Datagram Protocol (UDP), was designed for real-time control applications. Moreover, periodic data and sporadic data are two types of real-time data traffic with different priorities in an NCS. Due to the lack of support for prioritized transmission service, the real-time performance for periodic and sporadic data in an NCS network is often degraded significantly, particularly under congested network conditions. To address these problems, a new transport layer protocol called Reliable Real-Time Transport Protocol (RRTTP) is proposed in this thesis. As a UDP-based protocol, RRTTP inherits UDP’s simplicity and fast transmission features. To improve the reliability, a retransmission and an acknowledgement mechanism are designed in RRTTP to compensate for packet losses. They are able to avoid unnecessary retransmission of the out-of-date packets in NCSs, and collisions are unlikely to happen, and small transmission delay can be achieved. Moreover, a prioritized transmission mechanism is also designed in RRTTP to improve the real-time performance of NCS networks under congested traffic conditions. Furthermore, the proposed RRTTP is implemented in the Network Simulator 2 for comprehensive simulations. The simulation results demonstrate that RRTTP outperforms TCP and UDP in terms of real-time transmissions in an NCS over wireless networks.

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This thematic issue on education and the politics of becoming focuses on how a Multiple Literacies Theory (MLT) plugs into practice in education. MLT does this by creating an assemblage between discourse, text, resonance and sensations. What does this produce? Becoming AND how one might live are the product of an assemblage (May, 2005; Semetsky, 2003). In this paper, MLT is the approach that explores the connection between educational theory and practice through the lens of an empirical study of multilingual children acquiring multiple writing systems simultaneously. The introduction explicates discourse, text, resonance, sensation and becoming. The second section introduces certain Deleuzian concepts that plug into MLT. The third section serves as an introduction to MLT. The fourth section is devoted to the study by way of a rhizoanalysis. Finally, drawing on the concept of the rhizome, this article exits with potential lines of flight opened by MLT. These are becomings which highlight the significance of this work in terms of transforming not only how literacies are conceptualized, especially in minority language contexts, but also how one might live.

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Higher-order thinking has featured persistently in the reform agenda for science education. The intended curriculum in various countries sets out aspirational statements for the levels of higher-order thinking to be attained by students. This study reports the extent to which chemistry examinations from four Australian states align and facilitate the intended higher-order thinking skills stipulated in curriculum documents. Through content analysis, the curriculum goals were identified for each state and compared to the nature of question items in the corresponding examinations. Categories of higher-order thinking were adapted from the OECD’s PISA Science test to analyze question items. There was considerable variation in the extent to which the examinations from the states supported the curriculum intent of developing and assessing higher-order thinking. Generally, examinations that used a marks-based system tended to emphasize lower-order thinking, with a greater distribution of marks allocated for lower-order thinking questions. Examinations associated with a criterion-referenced examination tended to award greater credit for higher-order thinking questions. The level of complexity of chemistry was another factor that limited the extent to which examination questions supported higher-order thinking. Implications from these findings are drawn for the authorities responsible for designing curriculum and assessment procedures and for teachers.

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As a cultural field, the world of fashion is usually associated with ‘exclusive’ qualities such as celebrity, glamour and the value of being young beautiful and size 10. By and large fashion design courses adhere to this model of fashion production and consumption training their graduates to compete successfully in an industry that seems far removed from the notions inclusivity and connection of community engagement. However, alternative models can and do exist. This presentation tells the story of ‘the stitchery collective’ a group of graduates from QUTs Creative Industries Fashion program who are developing an innovative model of fashion practice focussed around the ideas and values both of community engagement and community cultural development. Their work to date has included projects that target specific community groups – such as “Fashioning Social Inclusion” (2010-2011) that works with Brisbane women who belong to migrant and refugee communities, as well as more recently “WARM” a workshop delivered to children at the 3rd International Kids’ Carnival hosted by La Biennale in Venice (February 2012). A common thread across these programs is a desire to investigate the premise that clothing and dress can potentially act as a lingua franca that enables connection and communication; and that in fact aspects of ‘fashion’ culture can be mobilised in a community focussed context to enhance cultural exchange. The issue of how ‘learning’ happens in these contexts provides rich scope for analysis and discussion – given the innovative and engaged nature of the work our discussion will particularly highlight the ‘leaning through doing’ that occurs as well as the ‘collective’ nature of the design processes we develop and promote. The story will include the voices and perspectives of several of the stitchery collective’s members as well as community partners.

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Reading plays an important role in establishing lifelong learning and providing the reader with an avenue to new experiences and a language with which to express their ideas and feelings (Owen 2003; Hamston & Love 2005). In particular adolescents need a language that allows them to 'play with their identities in a safe and controlled manner to explore who they want to be in this ever changing world' (Koss & Teale 2009, 569). Block (1995) advances that there is a distinct correlation between what we read and how we live in the world, and argues 'if what we read influences our identity in the world, the ways we are able to imagine and live in the world, then there is some responsibility to address these various texts, their readers and possible reading experiences' (Koss & Teale 2009, 569). Within my research I attempt to take on this responsibility by establishing a connection between reluctant adolescent male readers, and their reading experiences and by using their opinions to create a novella that seeks to more fully engage them. Centred within the larger debate about boys and books are two central discussions: why don't boys read and what should boys read? While a number of reasons why adolescent boys don't read are mentioned in this paper and it might not be possible to fully account for why many are reluctant readers, it is possible to argue that specific forms of literature addressing certain themes and topics relevant to the age group might appeal to reluctant readers. The conceptual framework for this research was structured using a mixed-method approach consisting of four phases. In positioning my research for determining literature that reluctant readers may want to read I draw on a variety of material which tends to support the longevity of S.E Hinton's (1967) argument that 'teenagers today, want to read about teenagers today' (cited in Smith & Wilhelm 2002, 6). My practice-based research was conducted within a high school in Brisbane, Australia. Six participants were selected and required to read three recently published Australian Young Adult novels, and opinion was collected via semi-structured interviews on these case studies. Grounded Theory (Charmaz 2003; Charmaz 2006; Glaser & Strauss 2011) informed the design of the questions, and the process of concurrent interviews and analysis of opinion. This analysis led to construction of my theory: adolescent male reluctant readers want to read about female relationships and family conflict within a story that consists of an adventure that, although unlikely to happen, could happen. From this study there are two main contributions, which have theoretical and practical implications for stakeholders with a vested interest in the discussion regarding boys and books. First, this study, through the research methodology, presents key findings that indicate that reluctant readers are interested in realistic texts addressing themes that will help with the construction of, and understanding of, their own lives. Secondly, the grounded theory derived from these findings is applied to my own praxis and my creative artefact (Duende) is included with this exegesis as a text intended to create a connection between engaging texts and adolescent male reluctant readers.

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The term empathy has only existed in English for a little over a hundred years, but the idea of feeling with another person is an old one. Because of its perceived connection to moral behaviour, empathy and its development are of great interest to educators, policy makers, psychologists, and philosophers. Reading children’s literature is often considered important for developing (among other things) children’s ethical and empathic understandings of society and its people. However, claims as to the impact of reading on readers’ ability to become more empathic, tolerant, and better people are divided. While many readers may attribute positive influences that authors and texts have had on shaping their attitudes and actions, there is no guarantee that a desirable affective and cognitive response will follow the reading experience. The complexity of readers and texts refuses to be reduced to simple universal statements about the capacity of narrative empathy to create a particular kind of empathic reader or person: fiction that engages a reader with the emotional plight of a character does not necessarily translate into actions in the real world towards people who are similarly suffering, marginalized, or victimized. This chapter asks: Does children’s literature foster empathy? There are two implicit features of this question: one concerns narrative empathy; the other concerns empathic reader response. The discussion will focus on how a selection of ‘multicultural’ picture books attempts to create narrative empathy by focussing on cultural and spatial differences.