A Proxy Approach for Interoperability and Common Control of Networked Digital Audio Devices
- Authors: Igumbor, Osedum P , Foss, Richard
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427099 , vital:72414 , https://www.aes.org/e-lib/browse.cfm?elib=15338
- Description: This paper highlights the challenge that results from the availability of a large number of control protocols within the context of digital audio networks. Devices that conform to different protocols are unable to communicate with one another, even though they might be utilizing the same networking technology (Ethernet, IEEE 1394 serial bus, USB). This paper describes the use of a proxy that allows for high-level device interaction (by sending protocol messages) between networked devices. Furthermore, the proxy allows for a common controller to control the disparate networked devices.
- Full Text:
- Date Issued: 2010
Developing an ionospheric map for South Africa
- Authors: McKinnell, Lee-Anne , Okoh, D I , Cilliers, P J
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6822 , http://hdl.handle.net/10962/d1004438 , http://dx.doi.org/10.5194/angeo-28-1431-2010
- Description: The development of a map of the ionosphere over South Africa is presented in this paper. The International Reference Ionosphere (IRI) model, South African Bottomside Ionospheric Model (SABIM), and measurements from ionosondes in the South African Ionosonde Network, were combined within their own limitations to develop an accurate representation of the South African ionosphere. The map is essentially in the form of a computer program that shows spatial and temporal representations of the South African ionosphere for a given set of geophysical parameters. A validation of the map is attempted using a comparison of Total Electron Content (TEC) values derived from the map, from the IRI model, and from Global Positioning System (GPS) measurements. It is foreseen that the final South African ionospheric map will be implemented as a Space Weather product of the African Space Weather Regional Warning Centre.
- Full Text:
- Date Issued: 2010
Does reservoir trophic status influence the feeding and growth of the sharptooth catfish, Clarias gariepinus (Teleostei: Clariidae)?
- Authors: Potts, Warren M , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124309 , vital:35591 , https://doi.org/10.2989/A JAS.2008.33.2.6.503
- Description: The diet and growth of sharptooth catfish, Clarias gariepinus, in an oligotrophic system (Kat River Reservoir, Eastern Cape, South Africa) were compared to those in a eutrophic system (Laing Reservoir, Eastern Cape) to determine if the trophic status of a waterbody had an effect on the growth rate of the species. In order of importance, the diet of catfish in Kat River Reservoir consisted of fish, insects, zooplankton, plant material and other items, while the diet of catfish in Laing Reservoir consisted of fish, plant material, zooplankton, other vertebrates and insects. The diets of catfish in the two reservoirs had a similarity index of 68.1% and there was no significant difference in their nutritional value. Fish prey was the most important dietary component in both reservoirs. Temperature regime and zooplankton and zoobenthos density were similar in both systems. However, fish prey density was significantly higher in the eutrophic Laing Reservoir and catfish grew significantly faster in that system. The slower growth rate in Kat River Reservoir was attributed to the higher energy costs associated with the capture of fish prey, which was less abundant than in Laing Reservoir. Trophic status therefore had an indirect effect on catfish growth by influencing the availability of fish prey.
- Full Text:
- Date Issued: 2010
Factors affecting recapture rates of raggedtooth sharks Carcharias taurus tagged off the east coast of South Africa
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124493 , vital:35618 , https://doi.10.2989/AJMS.2009.31.3.9.997
- Description: Understanding differences in the recapture rate between different tags (A-, B- and C-types), capture methods (rock-and-surf anglers, scientific divers and Natal Sharks Board protection nets) and life-history stages (juvenile and adult) is critical in evaluating the results obtained from cooperative tagging programmes (CTPs). A generalised linear modelling approach, using a log-linear model, was used to determine significant differences in the probability of recapture between these various factors using data from the Oceanographic Research Institute and Port Elizabeth Museum CTPs. Between 1984 and 2004, a total of 3 385 raggedtooth sharks Carcharias taurus was tagged by volunteers from both programmes along the east coast of South Africa. A likelihood ratio test indicated significant differences in the probability of recapture between A- and C-type and B- and C-type tags (p < 0.01), between different capture methods (p < 0.05) and between juvenile and adult sharks (p < 0.01). A comparison of recapture rates between members of the CTPs also indicated a marked variability in the performance of individual taggers. The study highlights important data-quality issues inherent in large CTPs.
- Full Text:
- Date Issued: 2010
Growth, reproduction and population structure of Diplotaxodon limnothrissa in the southeast arm of Lake Malawi
- Authors: Kanyerere, Geoffrey Z , Weyl, Olaf L F , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124583 , vital:35633 , https://doi.org/10.2989/16085910509503832
- Description: With a surface area of ca 28 800km2, Lake Malawi (9°30’S–14°30’S) is the second largest of the African Rift Valley lakes, supporting at least 500, and possibly 2 000, fish species (Turner 1995). The ichthyofauna is dominated by haplochomine cichlids, most of which are confined to the demersal and littoral zones. As a result of over-fishing, the abundance of many of these species has declined (Turner 1994a, 1995, Bulirani et al. 1999, Allison et al. 2002). In contrast, the lake’s offshore fish stocks are considered to be unexploited or only lightly exploited (Thompson and Allison 1997, Turner et al. 2000) and the redirection of fishing effort to these stocks is a high priority (Thompson and Allison 1997, Turner et al. 2000, Allison et al. 2002). Consequently, the Malawi government is currently collaborating with the African Development Bank to develop the deepwater/ offshore fishery in order to increase yields by an estimated 11 000 tons (MC Banda, National Research co-ordinator, pers. comm.). The most abundant cichlid species in the pelagic zone is the small (<210mm TL) zooplanktivorous Diplotaxodon limnothrissa (Turner 1994, Thompson and Allison 1997). It has been recorded throughout the lake at depths ranging from 20 metres down to the anoxic zone at ca 220 metres (Turner 1994b, Thompson et al. 1996, Duponchelle et al. 2000a) and it makes up ca 52% to the total fish biomass (Thompson and Allison 1997). Diplotaxodon limnothrissa will therefore be a major target species in the pelagic fishery, and already comprises in excess of 50% of the mid-water trawl fishery in the southeast arm (SEA) of the lake (Turner 1996).
- Full Text:
- Date Issued: 2010
Identifying annotations for adventure game generation from fiction text
- Authors: Berkland, Ross , Bangay, Shaun D
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433366 , vital:72965 , https://doi.org/10.1145/1899503.1899506
- Description: Recent advancements in Text-to-Scene research have lead to the devel-opment of systems which automatically extract key concepts from the text of a fiction book and generate computer animated movies depicting the sto-ry. Extracting such annotations from raw fiction text is a laborious process and so in this work we evaluate appropriate candidates to serve as the basis for the required annotations for generating interactive virtual worlds. We val-idate our choice by generating adventure games: interactive virtual worlds which create a stylized representation of the environment described in the text, populate it with characters related to the story and define game goals related to the plot of the fiction story. Our prototype produces a fully playa-ble game, making use of an existing open-source game engine. The pro-cess is evaluated using user tests in which participants are asked to meas-ure the accuracy with which the game represents the events, characters and goals described in the story. The response indicates that the chosen an-notation set is sufficient to define a game that is a plausibly acceptable rep-resentation of the text.
- Full Text:
- Date Issued: 2010
Minimum spanning trees for valley and ridge characterization in digital elevation maps
- Authors: Bangay, Shaun D , de Bruyn, David , Glass, Kevin R
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433247 , vital:72955 , https://doi.org/10.1145/1811158.1811171
- Description: Texture synthesis employs neighbourhood matching to generate appropriate new content. Terrain synthesis has the added constraint that new content must be geographically plausible. The profile recognition and polygon breaking algorithm (PPA) [Chang et al. 1998] provides a robust mechanism for characterizing terrain as systems of valley and ridge lines in digital elevation maps. We exploit this to create a terrain characterization metric that is robust, efficient to compute and is sensitive to terrain properties.
- Full Text:
- Date Issued: 2010
Parallel packet classification using GPU co-processors
- Authors: Nottingham, Alistair , Irwin, Barry V W
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430250 , vital:72677 , https://doi.org/10.1145/1899503.1899529
- Description: In the domain of network security, packet filtering for classification pur-poses is of significant interest. Packet classification provides a mecha-nism for understanding the composition of packet streams arriving at distinct network interfaces, and is useful in diagnosing threats and un-covering vulnerabilities so as to maximise data integrity and system se-curity. Traditional packet classifiers, such as PCAP, have utilised Con-trol Flow Graphs (CFGs) in representing filter sets, due to both their amenability to optimisation, and their inherent structural applicability to the metaphor of decision-based classification. Unfortunately, CFGs do not map well to cooperative processing implementations, and single-threaded CPU-based implementations have proven too slow for real-time classification against multiple arbitrary filters on next generation networks. In this paper, we consider a novel multithreaded classification algorithm, optimised for execution on GPU co-processors, intended to accelerate classification throughput and maximise processing efficien-cy in a highly parallel execution context.
- Full Text:
- Date Issued: 2010
The death of the animal in South African history
- Authors: Wylie, Dan
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450096 , vital:74882 , https://www.scielo.org.za/pdf/hist/v55n2/v55n2a21.pdf
- Description: Matthew Calarco in his contribution to Paola Cavalieri's collection, The Death of the Animal (2009). Running through the conversations comprising this book is a thread of dissention at the Socratic, rationalistic approach taken by analytic philosophy to the question of rights for animals.
- Full Text:
- Date Issued: 2010
Vice-Chancellor's welcoming address 2010
- Authors: Badat, Saleem
- Date: 2010
- Language: English
- Type: text
- Identifier: vital:7590 , http://hdl.handle.net/10962/d1006581
- Description: From introduction: Rhodes University, which means, you and I and academics and support staff, exists to serve three purposes. The first is to produce knowledge, so that we can advance understanding of our natural and social worlds and enrich our accumulated scientific and cultural heritage. As a university our second purpose is to disseminate knowledge and to cultivate minds. Our goal is to ensure that you can think imaginatively, “effectively and critically”; that you “achieve depth in some field of knowledge”; that you can critique and construct alternatives, that you can communicate cogently, orally and in writing, and that you have a “critical appreciation of the ways in which we gain knowledge and understanding of the universe, of society, and of ourselves” Our final purpose as a university is to undertake community engagement. On the one hand this involves your voluntary participation in community projects undertaken thorough our Community Engagement office. On the other hand, it involves service-learning, in which through your academic courses you take part “in activities where both the community” and you benefit, “and where the goals are to provide a service to the community and, equally, to enhance (your) learning through rendering this service”
- Full Text:
- Date Issued: 2010
Visual technology for the autonomous learning of mathematics:
- Authors: Linneweber-Lammerskitten, Helmut , Schäfer, Marc , Samson, Duncan
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140949 , vital:37931 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC20930
- Description: This paper describes a collaborative research and development project between the University of Applied Sciences Northwestern Switzerland and Rhodes University in South Africa. The project seeks to establish, disseminate and research the efficacy and use of short video clips designed specifically for the autonomous learning of mathematics. Specific to the South African context is our interest in capitalising on the ubiquity of cellphone technology and the autonomous affordances offered by mobile learning. This paper engages with a number of theoretical and pedagogical issues relating to the design, production and use of these video clips. Although the focus is specific to the contexts of South Africa and Switzerland, the discussion is of broad applicability.
- Full Text:
- Date Issued: 2010
Business Management: BEC 121 & BEC 121E
- Authors: Masocha, Reginald , Rungani, Ellen , Puchert, Juliet
- Date: 2010-01
- Subjects: Industrial management
- Language: English
- Type: Examination paper
- Identifier: vital:17434 , http://hdl.handle.net/10353/d1010244
- Description: Business Management BEC 121 & BEC 121E, supplementary examination January 2010.
- Full Text: false
- Date Issued: 2010-01
Communication and Life Skills: CLS 121F
- Authors: Formson, C , Scott, R
- Date: 2010-01
- Subjects: Life skills
- Language: English
- Type: Examination paper
- Identifier: vital:17948 , http://hdl.handle.net/10353/d1010519
- Description: Communication and Life Skills: CLS 121F, supplementary examination Jan/Feb 2010.
- Full Text: false
- Date Issued: 2010-01
Business Management: BEC 121 & 121E
- Authors: Ramoscha, Reginald , Rungani, Ellen , Puchert, Juliet
- Date: 2009-11
- Subjects: Business enterprises -- Finance
- Language: English
- Type: Examination paper
- Identifier: vital:17449 , http://hdl.handle.net/10353/d1010262
- Description: Examination on Business Management: BEC 121 & 121E, November 2009.
- Full Text: false
- Date Issued: 2009-11
Business Management: BEC 312 / 312E
- Authors: Fatoki, O O , Rowles, M , Tait, M
- Date: 2009-06
- Subjects: Business management
- Language: English
- Type: Examination paper
- Identifier: vital:17444 , http://hdl.handle.net/10353/d1010256
- Description: Business Management: BEC 312 / 312E, June 2009, Supplementary examination, Selected topics on financial management.
- Full Text: false
- Date Issued: 2009-06
A Framework for the Rapid Development of Anomaly Detection Algorithms in Network Intrusion Detection Systems
- Authors: Barnett, Richard J , Irwin, Barry V W
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428644 , vital:72526 , https://www.researchgate.net/profile/Johan-Van-Niekerk-2/publication/220803295_E-mail_Security_awareness_at_Nelson_Mandela_Metropolitan_University_Registrar's_Division/links/0deec51909304b0ed8000000/E-mail-Security-awareness-at-Nelson-Mandela-Metropolitan-University-Registrars-Division.pdf#page=289
- Description: Most current Network Intrusion Detection Systems (NIDS) perform de-tection by matching traffic to a set of known signatures. These systems have well defined mechanisms for the rapid creation and deployment of new signatures. However, despite their support for anomaly detection, this is usually limited and often requires a full recompilation of the sys-tem to deploy new algorithms.
- Full Text:
- Date Issued: 2009
An Integrated Connection Management and Control Protocol for Audio Networks
- Authors: Foss, Richard , Gurdan, Robby , Klinkradt, Bradley , Chigwamba, Nyasha
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427111 , vital:72415 , https://www.aes.org/e-lib/browse.cfm?elib=15135
- Description: With the advent of digital networks that link audio devices, there is a need for a protocol that integrates control and connection management, allows for streaming of all media content such as audio and video between devices from different manufacturers, and that provides a common approach to the control of these devices. This paper proposes such a protocol, named XFN, currently being standardized as part of the AES X170 project. XFN is an IP-based peer to peer network protocol, in which any device on the network may send or receive connection management, control, and monitoring messages. Essential to the XFN protocol is the fact that each parameter in a device can be addressed via a hierarchical structure that reflects the natural layout of the device.
- Full Text:
- Date Issued: 2009
Evaluating text preprocessing to improve compression on maillogs
- Authors: Otten, Fred , Irwin, Barry V W , Thinyane, Hannah
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430138 , vital:72668 , https://doi.org/10.1145/1632149.1632157
- Description: Maillogs contain important information about mail which has been sent or received. This information can be used for statistical purposes, to help prevent viruses or to help prevent SPAM. In order to satisfy regula-tions and follow good security practices, maillogs need to be monitored and archived. Since there is a large quantity of data, some form of data reduction is necessary. Data compression programs such as gzip and bzip2 are commonly used to reduce the quantity of data. Text preprocessing can be used to aid the compression of English text files. This paper evaluates whether text preprocessing, particularly word replacement, can be used to improve the compression of maillogs. It presents an algorithm for constructing a dictionary for word replacement and provides the results of experiments conducted using the ppmd, gzip, bzip2 and 7zip programs. These tests show that text prepro-cessing improves data compression on maillogs. Improvements of up to 56 percent in compression time and up to 32 percent in compression ratio are achieved. It also shows that a dictionary may be generated and used on other maillogs to yield reductions within half a percent of the results achieved for the maillog used to generate the dictionary.
- Full Text:
- Date Issued: 2009
Extending the NFComms: framework for bulk data transfers
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430164 , vital:72670 , https://doi.org/10.1145/1632149.1632170
- Description: Packet analysis is an important aspect of network security, which typi-cally relies on a flexible packet filtering system to extrapolate important packet information from each processed packet. Packet analysis is a computationally intensive, highly parallelisable task, and as such, clas-sification of large packet sets, such as those collected by a network tel-escope, can require significant processing time. We wish to improve upon this, through parallel classification on a GPU. In this paper, we first consider the OpenCL architecture and its applicability to packet analy-sis. We then introduce a number of packet demultiplexing and routing algorithms, and finally present a discussion on how some of these techniques may be leveraged within a GPGPU context to improve packet classification speeds.
- Full Text:
- Date Issued: 2009
Flies in the ointment a morphological and molecular comparison of Lucilia cuprina and Lucilia sericata (Diptera: Calliphoridae) in South Africa
- Authors: Tourle, Robyn , Downie, Douglas A , Villet, Martin H
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442156 , vital:73963 , https://doi.org/10.1111/j.1365-2915.2008.00765.x
- Description: Complementary nuclear (28S rRNA) and mitochondrial (COI) genes were sequenced from blowflies that phenotypically resembled Lucilia cuprina (W.), Lucilia sericata (Meigen) or exhibited characters of both species. The aim was to test a long‐held hypothesis that these species hybridize under natural conditions in South Africa (Ullyett, 1945). Blowflies were obtained predominantly from the Cape Town metropolitan area, but reference samples were acquired for L. sericata from Pretoria. Several L. cuprina‐like flies were shown to possess a conflicting combination of nuclear and mitochondrial genes that has also been seen in Hawaiian specimens. Homoplasy, sampling of pseudogenes, hybridization and incomplete lineage sorting are discussed as possible hypotheses for the pattern and the latter is concluded to represent the most likely explanation.
- Full Text:
- Date Issued: 2009