1,720,968 research outputs found
IP address auto-configuration for wireless ad-hoc networks
Get PDFA thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy (Computer Science) in the Department of Computer Science, Faculty of Science and Agriculture, University of Zululand, 2019.In an ad hoc network, nodes collaborate to allow communication without the presence of network infrastructure. Lack of manual management in ad hoc networks means that automatic configuration is highly desirable. The need for automatic configuration capabilities will become significantly more intense when one considers the networked home of the future, with IP-enabled appliances, such as microwave ovens, thermostats, alarm clocks, speakers, and various kinds of sensors. High levels self-organisation provides an out-of-the-box functionality such that very little technical expertise is required to set up a network. However, efficiently providing unique IP addresses in ad hoc networks is still an open research question.
This study is a successful attempt to investigate automatic IP addressing in wireless ad hoc networks as both Multicriteria decision making (MCDM) problem and a challenge of building a system that converges towards the global desired goal. Consequently, the solution proposed in this thesis is inspired by observing swam systems’ ability to converge towards a global goal from local interactions. The investigation reported in this thesis first answered the question of how different network conditions affect the address auto-configuration process. Experiments to investigate the effect of mobility, network traffic and DAD timeout period on address auto-configuration were conducted.
The results of these experiments informed the design of the new protocol, D-DAD, proposed in this work. The proposed IP address auto-configuration mechanism was simulated in Ns2 and results were compared with existing Wise-DAD and StrongDAD protocols. We performed five experiments to investigate the effect of network size, node density, node arrival rate, mobility, and network traffic on communication overhead, address uniqueness and latency. The results showed that D-DAD outperformed StrongDAD in all the metrics used for comparison. However, in some instances, D-DAD recorded more communication overhead in comparison to Wise-DAD but had better latency and fewer address conflicts
Design of an IP address Auto-Configuration scheme for Wireless Multi-Hop Networks
Get PDFA dissertation submitted in fulfilment of the requirements for the degree of
Master of Science (Computer Science)
Department of Computer Science, Faculty of Science and Agriculture,
University of Zululand,
2008.The importance of wireless ad-hoc networks (eg wireless mesh networks) in community and
commercial connectivity cannot be underestimated in view of the benefits associated with
such networks. An ad-hoc network must assemble itself from any devices that happen to be
nearby, and adapt as devices move in and out of wireless range. High levels of self organization
will minimize the need for manual configuration. In essence, self-organization
provides an out-of-the-box functionality such that very little technical expertise is required to
setup a network. However, efficiently providing unique IP addresses in ad-hoc networks is
still an open research question. The goal of this study, on wireless multi-hop networks, was
to develop algorithms for IP address auto-configuration. These algorithms should address
the following among other problems: Achieving high levels of address uniqueness without
compromising on latency and communication overhead.
To achieve the overall goal of this research we proposed changes to the traditional DAD
procedure, the Wise-DAD protocol was proposed. We introduced state information
maintenance, which is passively collected and synchronized. Passively collecting state
information reduced the number of DAD trials thereby reducing latency and communication
overhead. Simulations were done in NS-2 to test the performance of the proposed protocol.
A comparative analysis was then conducted. Wise-DAD was compared with the Strong-DAD
protocol. Experiments on the effect of network size, node density and node arrival rate on
communication overhead, address uniqueness and latency were conducted.
Results from the simulation experiments show that Wise-DAD outperforms Strong-DAD in
all the three metrics used for performance evaluation. First, Wise-DAD showed better
scalability since it performed better than Strong-DAD when network size was increased.
Communication overhead in Wise-DAD was generally low whilst the latency was generally
uniform. The number of IP address duplicates recorded was reasonably low. Second, Wise-
DAD was not affected by node arrival rate on all the three metrics that were recorded. On the
other hand, the number of address duplicates in Strong-DAD decreased as the node arrival
rate was increased. Interference significantly affected communication overhead recorded in
Strong-DAD. Wise-DAD, on the other hand, was not affected by interference. The number of
address conflicts in both protocols showed an inverse relationship to interference. However,
the number of conflicts for both protocols was significantly different; Wise-DAD recorded
much less address conflicts than Strong-DAD.Telkom, Thrip and Huawei, and NRF
Conștientizarea dezvoltării software de securitate: studiu de caz al dezvoltatorilor de licență
No full textAs ubiquitous computing becomes an increasingly inherent component of everyday life due to the rapid growth of communication technologies and globalization, threats against information systems have taken a more latent yet lethal dimension. This emergent digital security challenge has correspondingly motivated a proactive change in the software engineering process in recent decades. This change has inspired more intense research scrutiny on security as a crucial component of any software system. Moreover, in today’s virtual world of hyperconnectivity, the most significant vulnerabilities in modern information systems security are software centred. Nevertheless, research shows that software developers often lack the required knowledge and skills in secure software systems development (SSD). Such knowledge ensures that all the resultant software components of each development lifecycle are correctly implemented rather than merely following the SSD lifecycle. Also, the knowledge engenders software security consciousness as a professional attitude amongst developers. Therefore, investigating students’ awareness of SSD principles can generate insight into evolving the undergraduate software development curriculum – a path to building future career developers. The study used a voluntary online survey to recruit a sample of 76 undergraduate developers and employed a descriptive approach to data analysis. Among other findings, the study revealed that participants' perception of the threat of software vulnerability impacts their attitude towards security on online and mobile platforms. And that though over 90% of the undergraduate developers took software vulnerability threats either “serious” or “extremely serious”, this disposition did not reflect the depth of their knowledge and experience in SSD.Pe măsură ce computerul omniprezent devine o componentă din ce în ce mai inerentă a vieții de zi cu zi datorită creșterii rapide a tehnologiilor de comunicare și globalizării, amenințările la adresa sistemelor informaționale au luat o dimensiune mai latentă, dar letală. Această provocare emergentă de securitate digitală a motivat în mod corespunzător o schimbare proactivă în procesul de inginerie software în ultimele decenii. Această schimbare a inspirat o cercetare mai intensă a securității ca componentă crucială a oricărui sistem software. Mai mult, în lumea virtuală de astăzi a hiperconectivitatii, cele mai semnificative vulnerabilități în securitatea sistemelor informatice moderne sunt centrate pe software. Cu toate acestea, cercetările arată că dezvoltatorii de software nu au adesea cunoștințele și abilitățile necesare în dezvoltarea sistemelor software securizate (SSD). O astfel de cunoaștere asigură că toate componentele software rezultate ale fiecărui ciclu de viață de dezvoltare sunt implementate corect, mai degrabă decât să urmărească pur și simplu ciclul de viață SSD. De asemenea, cunoștințele generează conștiința securității software ca atitudine profesională în rândul dezvoltatorilor. Prin urmare, investigarea gradului de conștientizare de către studenți a principiilor SSD poate genera o perspectivă asupra evoluției curriculum-ului de dezvoltare software pentru licență - o cale către construirea viitorilor dezvoltatori de carieră. Studiul a folosit un sondaj online voluntar pentru a recruta un eșantion de 76 de dezvoltatori de licență și a folosit o abordare descriptivă a analizei datelor. Printre alte constatări, studiul a arătat că percepția participanților asupra amenințării vulnerabilității software influențează atitudinea lor față de securitate pe platformele online și mobile. Și că, deși peste 90% dintre dezvoltatorii de licență au considerat amenințările de vulnerabilitate software fie „serioase” fie „extrem de grave”, această dispoziție nu a reflectat profunzimea cunoștințelor și experienței lor în SSD
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Social Media and the COVID-19: South African and Zimbabwean Netizens’ Response to a Pandemic
Get PDFSince the end of 2019, the world faced a major health crisis in the form of the Coronavirus (COVID-19) pandemic. To mitigate the impact of the pandemic, governments across the globe instituted measures such as restricting local and international travel and in many cases, ordering citizens to stay indoors. Considering the social and economic impact of these restrictions it becomes crucial to investigate internet citizens’ (netizens) perception about the precautionary measures adopted. The study is anchored in the digital public sphere theory, which treats social media applications as virtual platforms where netizens commune to share ideas and debate about issues that affect them. Social media platforms already have critical public views on the current pandemic. However, the majority of this data is unstructured and difficult to interpret. Natural language processing (NLP), on the other hand, makes the task of gathering and analysing vast amounts of textual data feasible. Extracting structured knowledge from natural language, however, comes with unique challenges due to diverse linguistic properties including abbreviation, spelling mistakes, punctuations, stop words and non-standard text. In this work, The Latent Dirichlet Allocation (LDA) algorithm was applied to tweeter data to extract topics discussed by netzens from Zimbabwe and South Africa. The primary focus of this paper, is to comparatively explore the variety of topics that occupied twitter communities from the two countries. We examine whether or not the national identities that define and differentiate citizens of these countries also exist on Twitter as evident in the emerging topics. Furthermore, this work investigated public opinion by analysing how citizens discuss the issues around the COVID-19 pandemic on social medi
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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