1,720,992 research outputs found
Context management and situation reasoning for ubiquitous applications in mobile peer-to-peer environments
No full textRecent advances in mobile computing, networking and sensing technologies have enabled mobile devices to become a major development platform for various applications, such as disaster prevention, environmental monitoring and intelligent transportation systems. These devices can be programmed to individually sense and capture context information and develop situation awareness. Mobile devices typically have limited capacity in terms of processing and sensing capabilities. Thus, to gain a better understanding of their surrounding situations, co-located mobile devices can jointly establish a mobile peer-to-peer (MP2P) environment and share captured context information. However, available context information may be uncertain, ambiguous, obsolete or even irrelevant. These issues can influence the reliability of the produced context information used for situation reasoning and/or adaptation criteria. This dissertation proposes, develops and validates a novel distributed middleware framework for context management and situation reasoning for ubiquitous applications in MP2P environments. The first contribution of this dissertation is our theoretical model termed CoMoS (Context Mobile Spaces), which is an approach to represent context and situations for ubiquitous applications in MP2P environments. Our second contribution is the formulation, development and validation of a theoretical approach to estimate the reliability of context information captured in MP2P environments. A data fusion technique based on Dempster-Shafer theory is integrated into the proposed context and situation model as the basis for situation reasoning using the captured context information. Our third contribution is the design, implementation and validation of DiFraCSi2 (Distributed Framework for Context Management and Situation Reasoning for Ubiquitous Applications in MP2P environments) middleware. This middleware implements the proposed concepts, models and algorithms of CoMoS. To minimise processing overheads, an event-based strategy to control the related processes is also developed and validated. We evaluate the contributions of the proposed theoretical model and framework through extensive experimental studies. The high accuracy of the situation recognition rate when using the DiFraCSi2 middleware in different situation scenarios highlights the significance of this research project’s contribution in providing situation-reasoning services. Performance of the proposed middleware functionality is also reported and analysed. The experimental results highlight the feasibility, significance and usability of DiFraCSi2 middleware in managing context and reasoning services. Thus, the research work presented in this dissertation takes a step forward in enabling reliable context management and situation reasoning for ubiquitous applications in MP2P environments. The results of this research project have been published in five peer-reviewed international conference papers, one technical report and one journal article submitted for review
Perancangan Dan Pembuatan Perangkat Lunak Untuk Segmentasi Citra Dengan Transformasi Watershed
Full text linkProses pengelompokan data sering dilakukan dalam analisis data. Dengan
mengelompokkan data berdasarkan kriteria keseragaman tertentu, maka analisis
data akan dapat dilakukan dengan relatif lebih mudah. Demikian pula untuk data
citra.
Segmentasi citra adalah proses pembagian citra kedalam bagian-bagian
ataupun kelompok-kelompok yang disebut obyek berdasarkan suatu kriteria
keseragaman tertentu. Segrnentasi adalah salah satu komponen terpenting dalam
analisis citra secara otomatis, karena obyek-obyek yang terdapat dalam citra akan
digunakan sebagai acuan untuk pengolahan data yang lebih lanjut seperti deskripsi
dan interprestasi citra ataupun pengenalan pola.
Transformasi watershed memandang citra sebagai sebuah relief topografi
dimana intensitas setiap pixel merepresentasikan ketinggian topografinya. Dalam
sebuah permukaan topografi, apabila air hujan jatuh diatasnya, sesuai dengan
hukum gravitasi maka air tersebut akan mengalir melewati jalur yang lebih rendah
sampai ia mencapai ketinggian yang paling rendah atau minima dimana ia tidak
dapat mengalir kemana-mana lagi.
Himpunan titik-titik pada permukaan topografi citra dimana aliran air
yang melewatinya menuju ke minima tertentu yang sama, menjadi sebuah
catchment bas in ( cekungan yang terisi air) yang berasosiasi dengan minima
tersebut dan membentuk sebuah region citra.
Watershed terbentuk dilokasi dimana air dari kedua catchment basin yang
berdekatan bertemu dan merupakan batas dari dua buah catchment basin tersebut.
Keseluruhan watershed yang terbentuk menghasilkan seluruh kontur tertutup
yang ada pada citra dan merepresentasikan obyek-obyek dalam citra yang telah
tersegrnentasi
Metode Deteksi Terputusnya Koneksi Tcp Pada Receiving Host Berdasarkan Packet Inter-Arrival Timeout
Full text linkAbstract. Novel Method to Detect Failed TCP Connection on Receiving Host Based on Packet Inter-arrival Timeout. TCP use retransmission timeout (RTO) as a standard mechanism to detect connection failure. Nevertheless, RTO can only be used by the sending host, and not by the receiving host. Until today there is no standardized mechanism for the receiving host to detect connection failure. Meanwhile a study on internet traffic shows that majority of internet traffic is unidirectional. This means the receiving host in majority of internet traffic does not have a standardized method to detect connection failure. This paper propose a novel method to detect failed TCP connection based on history of packet inter-arrival time. Simulation using NS2 shows the effectiveness of the proposed method.Keywords: Failed TCP connection detection, receiving host, packet inter-arrival timeoutAbstrak. TCP menggunakan retransmission timeout (RTO) sebagai mekanisme standar untuk mendeteksi terputusnya koneksi. Namun RTO hanya dapat dimanfaatkan pihak pengirim data (sending host), sedangkan pihak penerima data (receiving host) tidak memiliki mekanisme untuk mendeteksi terputusnya koneksi. Sementara itu sebuah studi menunjukkan bahwa sebagian besar traffic internet bersifat satu arah. Ini berarti pihak penerima data pada sebagian besar traffic internet tidak memiliki metode yang terstandarisasi untuk mendeteksi terputusnya koneksi. Penelitian ini mengajukan sebuah metode baru bagi receiving host untuk mendeteksi terputusnya koneksi TCP berdasarkan jeda waktu antar paket data (packet inter-arrival timeout) yang diterima. Simulasi menggunakan NS2 menunjukkan efektivitas metode yang diajukan.Kata Kunci: Deteksi terputusnya koneksi TCP, receiving host, packet inter-arrival timeoutÂ
Context management and situation reasoning for ubiquitous applications in mobile peer-to-peer environments
No full textRecent advances in mobile computing, networking and sensing technologies have enabled mobile devices to become a major development platform for various applications, such as disaster prevention, environmental monitoring and intelligent transportation systems. These devices can be programmed to individually sense and capture context information and develop situation awareness. Mobile devices typically have limited capacity in terms of processing and sensing capabilities. Thus, to gain a better understanding of their surrounding situations, co-located mobile devices can jointly establish a mobile peer-to-peer (MP2P) environment and share captured context information. However, available context information may be uncertain, ambiguous, obsolete or even irrelevant. These issues can influence the reliability of the produced context information used for situation reasoning and/or adaptation criteria.
This dissertation proposes, develops and validates a novel distributed middleware framework for context management and situation reasoning for ubiquitous applications in MP2P environments. The first contribution of this dissertation is our theoretical model termed CoMoS (Context Mobile Spaces), which is an approach to represent context and situations for ubiquitous applications in MP2P environments. Our second contribution is the formulation, development and validation of a theoretical approach to estimate the reliability of context information captured in MP2P environments. A data fusion technique based on Dempster-Shafer theory is integrated into the proposed context and situation model as the basis for situation reasoning using the captured context information. Our third contribution is the design, implementation and validation of DiFraCSi2 (Distributed Framework for Context Management and Situation Reasoning for Ubiquitous Applications in MP2P environments) middleware. This middleware implements the proposed concepts, models and algorithms of CoMoS. To minimise processing overheads, an event-based strategy to control the related processes is also developed and validated.
We evaluate the contributions of the proposed theoretical model and framework through extensive experimental studies. The high accuracy of the situation recognition rate when using the DiFraCSi2 middleware in different situation scenarios highlights the significance of this research project’s contribution in providing situation-reasoning services. Performance of the proposed middleware functionality is also reported and analysed. The experimental results highlight the feasibility, significance and usability of DiFraCSi2 middleware in managing context and reasoning services. Thus, the research work presented in this dissertation takes a step forward in enabling reliable context management and situation reasoning for ubiquitous applications in MP2P environments.
The results of this research project have been published in five peer-reviewed international conference papers, one technical report and one journal article submitted for review
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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