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Determining the signalling overhead of two common WebRTC methods: JSON via XMLHttpRequest and SIP over WebSocket 确定两种常见的webbrtc方法的信令开销:通过XMLHttpRequest的JSON和通过WebSocket的SIP
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757840
M. Adeyeye, I. Makitla, Thomas Fogwill
{"title":"Determining the signalling overhead of two common WebRTC methods: JSON via XMLHttpRequest and SIP over WebSocket","authors":"M. Adeyeye, I. Makitla, Thomas Fogwill","doi":"10.1109/AFRCON.2013.6757840","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757840","url":null,"abstract":"Web Real-Time Communication (WebRTC) introduces real-time multimedia communication as native capabilities of Web browsers. With the adoption of WebRTC the Web browsers will be able to use WebRTC to communicate with one another (peer-to-peer), and with WebSocket servers such as Mobicents SIP Servlets and other server technologies that support WebSocket communication to enable SIP-to-WebRTC communication. This paper outlines the potential of WebRTC and discusses the two common methods of doing real-time communication in Web browsers through WebRTC. The methods are JavaScript Object Notation (JSON) via XMLHttpRequest (XHR) and Session Initiation Protocol (SIP) via WebSocket. A three-user WebRTC video chat prototype application was developed and used to evaluate both methods. Additional signalling overhead introduced into a browser by each method was determined. The results showed WebRTC-SIP/WS has more overhead than WebRTC-JSON/XHR. These signalling overhead findings are useful in that they could help application developers make decision on their choice of technologies and protocols when developing WebRTC-supported applications.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123580231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 11
Fast technique for mixed Gaussian and impulsive noise suppression in color images 彩色图像中混合高斯和脉冲噪声的快速抑制技术
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757815
B. Smolka, K. Malik
{"title":"Fast technique for mixed Gaussian and impulsive noise suppression in color images","authors":"B. Smolka, K. Malik","doi":"10.1109/AFRCON.2013.6757815","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757815","url":null,"abstract":"In this paper an efficient filtering technique intended for the reduction of mixed Gaussian and impulsive noise in digital color images is presented. The proposed method is utilizing the concept of trimmed cumulative distances assigned to pixels from the local filtering window, which serve as measures of a local image homogeneity. The filter output is defined as a weighted average of the pixels in the processing window and the weights are constructed using the measures of pixel corruption. The proposed design is very fast and outperforms the state-of-the-art denoising schemes in terms of image restoration quality measures.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123978899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Level of infrastructure maintenance management in utilities of the Southern African Power Pool 南部非洲电力联营公用事业基础设施维修管理水平
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757633
L. M. Moeko, J. Visser
{"title":"Level of infrastructure maintenance management in utilities of the Southern African Power Pool","authors":"L. M. Moeko, J. Visser","doi":"10.1109/AFRCON.2013.6757633","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757633","url":null,"abstract":"Utilities of the Southern African Power Pool (SAPP) are confronted with aging generation and transmission assets. There is also a growing demand for electricity in most Southern African countries due to economic growth and construction of new assets is needed to cope with this demand. If maintenance on generation and network assets is neglected, business performance will not be achieved and lower availability and frequent trips will be experienced. Using concepts, frameworks and models described in literature, a framework for maintenance management was developed and tested in SAPP utilities by means of a survey. The survey revealed that all SAPP maintenance management strategies in place. The survey also indicated that shortfalls in specific aspects of maintenance management exist in some of the utilities of the SAPP. The paper recommends that the proposed infrastructure maintenance management framework be adopted and implemented by SAPP utilities to achieve a stable and interconnected electrical network and achieve the desired objective of maintenance management.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130042068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Embedded vision-based Monte-Carlo robot localisation without additional sensors 嵌入式基于视觉的蒙特卡罗机器人定位，无需额外的传感器
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757613
S. Olufs, M. Vincze
{"title":"Embedded vision-based Monte-Carlo robot localisation without additional sensors","authors":"S. Olufs, M. Vincze","doi":"10.1109/AFRCON.2013.6757613","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757613","url":null,"abstract":"This paper presents a fast approach for vision-based self-localisation in the RoboCup middle size league without additional e.g. dead reckoning sensors. An omni-directional vision system extracts a few features from image that are mapped to an sparse a-priori known map of the environment using Monte Carlo filters. The Monte Carlo filters are also used to model a virtual odometry (mass-inertia model) which is maintained through the filter itself. The precision of approach is directly compared to a traditional approach using the identical data. We show that the approach is stable and reactive while keeping the processing time low.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129684120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
An unequal error protection scheme for SPIHT image transmission with prioritised retransmissions and de-noising 一种具有优先重传和去噪的SPIHT图像传输的不等错误保护方案
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757769
T. P. Fowdur, D. Indoonundon, K. Soyjaudah
{"title":"An unequal error protection scheme for SPIHT image transmission with prioritised retransmissions and de-noising","authors":"T. P. Fowdur, D. Indoonundon, K. Soyjaudah","doi":"10.1109/AFRCON.2013.6757769","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757769","url":null,"abstract":"This paper proposes a robust resilient transmission scheme for images that have been compressed using the Set Partitioning In Hierarchical Trees (SPIHT) algorithm. The scheme employs Unequal Error Protection (UEP), prioritised Automatic Repeat reQuest (ARQ) and two-dimensional adaptive Wiener filtering. In order to apply UEP, the SPIHT coded bit-stream is partitioned into bit-classes of unequal importance. UEP is then applied at two levels. Firstly, Rate Compatible Punctured Convolutional (RCPC) codes are used to encode the bit-classes with different code-rates hence providing them with different levels of protection. Secondly, prioritized retransmissions are used such that the more important bit-classes are allocated a greater number of retransmissions than the less important ones. Equal gain combining is also performed to further improve the performance. The proposed U E P s c h e m e provides an average gain of 3 dB in P e a k S i g n a l to Noise Ratio (PSNR) over a conventional Equal Error Protection (EEP) in the range 0dB≤Eb/No≤6dB with 16-QAM and an average gain of 3.5 dB in PSNR in the range 0dB≤Eb/No≤3dB with BPSK modulation. Moreover, de-noising with a two dimensional Wiener filter provides an additional gain of 0.76 to 0.90 dB.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128630695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
SSVEP enhancement based on Canonical Correlation Analysis to improve BCI performances 基于典型相关分析的SSVEP增强提高脑机接口性能
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757776
Emmanuel K. Kalunga, Karim D Djouani, Y. Hamam, S. Chevallier, É. Monacelli
{"title":"SSVEP enhancement based on Canonical Correlation Analysis to improve BCI performances","authors":"Emmanuel K. Kalunga, Karim D Djouani, Y. Hamam, S. Chevallier, É. Monacelli","doi":"10.1109/AFRCON.2013.6757776","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757776","url":null,"abstract":"Brain Computer Interfaces (BCI) rely on brain waves signal, such as electro-encephalogram (EEG) recording, to endow a disabled user with non-muscular communication. Given the very low signal-to-noise ratio of EEG, a signal enhancement phase is crucial for ensuring decent performances in BCI systems. Several methods have been proposed for EEG signal enhancement, such as Independent Component Analysis, Common Spatial Pattern, and Principal Component Analysis. We show that Canonical Correlation Analysis (CCA), initially introduced to SSVEP-based BCI as a feature extraction method, is a good candidate for such preprocessing state. Evaluation is performed on a recording from 5 subjects during a BCI task based on Steady-State Visual Evoked Potentials (SSVEP). The authors demonstrate that CCA significantly improves classification performances in SSVEP-based BCIs.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130543631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 31
Polar coded MQAM with no noise variance estimation for capacity and soft decision metric 极性编码MQAM，对容量和软决策度量进行无噪声方差估计
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757866
P. Akuon, Hongjun Xu
{"title":"Polar coded MQAM with no noise variance estimation for capacity and soft decision metric","authors":"P. Akuon, Hongjun Xu","doi":"10.1109/AFRCON.2013.6757866","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757866","url":null,"abstract":"Polar coding (PC) separates the codeword into free and frozen sets of channels. In this paper, the construction of the two sets of channels and decoding are carried out based on the channel capacity and soft decision metric, respectively with unity noise variance. Additionally, the capacity for which signal and noise power are equal results in an interesting capacity spectrum whose average value is used in the PC construction. Simulations results show that this simplified soft metric achieves the same bit error rate (BER) when compared to the exact metric with receive overhead advantage. Transmission of symbols is made via flat fading Rayleigh channels. We see that the simulations results are well bounded within the theoretical performance limits.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121645567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
The SUMO toolbox: A tool for automatic regression modeling and active learning SUMO工具箱:用于自动回归建模和主动学习的工具
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757594
I. Couckuyt, D. Gorissen, K. Crombecq, D. Deschrijver, T. Dhaene
{"title":"The SUMO toolbox: A tool for automatic regression modeling and active learning","authors":"I. Couckuyt, D. Gorissen, K. Crombecq, D. Deschrijver, T. Dhaene","doi":"10.1109/AFRCON.2013.6757594","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757594","url":null,"abstract":"Many complex, real world phenomena are difficult to study directly using controlled experiments. Instead, the use of computer simulations has become commonplace as a feasible alternative. Due to the computational cost of these high fidelity simulations, surrogate models are often employed as a dropin replacement for the original simulator, in order to reduce evaluation times. In this context, neural networks, kernel methods, and other modeling techniques have become indispensable. Surrogate models have proven to be very useful for tasks such as optimization, design space exploration, visualization, prototyping and sensitivity analysis. We present a fully automated machine learning tool for generating accurate surrogate models, using active learning techniques to minimize the number of simulations and to maximize efficiency.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121919947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Some reflector and feed antenna inventions that made a difference: Fundamentals and examples from radio telescopes, satellite communications and radio links 一些反射器和馈电天线的发明产生了影响:射电望远镜、卫星通信和无线电链路的基本原理和例子
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757834
P. Kildal
{"title":"Some reflector and feed antenna inventions that made a difference: Fundamentals and examples from radio telescopes, satellite communications and radio links","authors":"P. Kildal","doi":"10.1109/AFRCON.2013.6757834","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757834","url":null,"abstract":"The paper will review some inventions within reflector antennas and feeds that represented a large step forward when they were introduced, in terms of both performance and industrial or scientific usefulness. The fundamental design principles as well as the actual solutions will be overviewed in a simple manner. The overview covers dipole-disk with ring for ship Earth stations, corrugated horns, hat-fed antennas for radio links, and wideband log-periodic “eleven” feed for SKA and VLBI 2010 radio telescopes. The inventions can in all cases be associated with simple fundamental EM principles, and an improvement of a fundamental subefficiency.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116005301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 8
Evaluating ALWadHA for providing secure localisation for wireless sensor networks 评估ALWadHA为无线传感器网络提供安全定位
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757656
A. Abu-Mahfouz, G. Hancke
{"title":"Evaluating ALWadHA for providing secure localisation for wireless sensor networks","authors":"A. Abu-Mahfouz, G. Hancke","doi":"10.1109/AFRCON.2013.6757656","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757656","url":null,"abstract":"Most of the proposed localisation algorithms studied the problem of location discovery in a non-adversarial environment. Although these types of algorithm are vulnerable to several types of security attack, less work has been done to implement secure localisation algorithms that are able to work in a hostile environment. An attacker could compromise, or masquerade as, a beacon node and send incorrect location information. Localisation in a hostile environment is a critical problem in wireless sensor networks (WSNs) because compromising the localisation system could disturb and subvert the entire functioning of the WSN. In this paper we investigate the security of recently proposed localisation algorithm, called ALWadHA, which enables nodes to live with the malicious reference nodes without disturbing the location estimation.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122250614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 32
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