Oligopolistic competition in heterogeneous access networks under asymmetries of cost and capacity

With the rapid development of broadband wireless access technologies, multiple wireless service provider (WSPs) operating on various wireless access technologies may coexist in one service area to compete for users, leading to a highly competitive environment for the WSPs. In such a competitive heterogeneous wireless access market, different wireless access technologies used by different WSPs have different bandwidth capacities with various costs. In this paper, we set up a noncooperative game model to study how the cost asymmetry and capacity asymmetry among WSPs affect the competition in this market. We first model such a competitive heterogeneous wireless access market as an oligopolistic price competition, in which multiple WSPs compete for a group of price- and delay-sensitive users through their prices, under cost and capacity asymmetries, to maximize their own profits. Then, we develop an analytical framework to investigate whether or not a Nash equilibrium can be achieved among the WSPs in the presence of the cost and capacity asymmetries, how the asymmetries of cost and capacity affect their equilibrium prices and what impact a new WSP with a cost and capacity advantage entering the market has on the equilibrium achieved among existing WSPs

Optimizing capacity assignment in multiservice MPLS net-works

Abstract: The general Multiprotocol Label Switch (MPLS) topology optimisation problem is complex and concerns the optimum selection of links, the assignment of capacities to these links and the routing requirements on these links. Ideally, all these are jointly optimised, leading to a minimum cost network which continually meets given objectives on network delay and throughput. In practice, these problems are often dealt with separately and a solution iterated. In this paper, we propose an algorithm that computes the shortest routes, assigns optimal flows to these routes and simultaneously determines optimal link capacities. We take into account the dynamic adaptation of optimal link capacities by considering the same Quality of Service (QoS) measure used in the flow assignment problem in combination with a blocking model for describing call admission controls (CAC) in multiservice broadband telecommunication networks. The main goal is to achieve statistical multiplexing advantages with multiple traffic and QoS classes of connections that share a common trunk present. We offer a mathematical programming model of the problem and proficient solutions which are founded on a Lagrangean relaxation of the problem. Experimental findings on 2-class and 6-class models are reported

TB detection using modified Local Binary Pattern features

Abstract: This paper explores a computer-aided detection scheme to aid radiologists in making a higher percentage of correct diagnoses when analysing chest radiographs. The approach undertaken in the detection process is to use several proprietary image processing algorithms to adjust, segment and classify a radiograph. Firstly, a Difference of Gaussian (DoG) energy normalisation method is applied to the image. By doing this, the effect of differing equipment and calibrations is normalised. Thereafter, the lung area is detected using Active Shape Models (ASMs). Once identified, the lungs are analysed using Local Binary Patterns (LBPs). This technique is combined with a probability measure that makes use of the the locations of known abnormalities in the training dataset. The results of the segmentation when compared to ground truth masks achieves an overlap segmentation accuracy of 87,598±3,986%. The challenges faced during classification are also discussed

Measurement of digital photographic image quality : survey of psychophysics just noticeable threshold difference method

Abstract: The modeling and quantification of digital photographic image quality has, from a psychophysics perspective, traditionally followed two paths, one of which is the discriminable small or just noticeable difference (local psychophysics) as detected in an image pair; further extended to cover a wide range of attribute artefactual quality variation. This method has its roots in the mathematical and psychological modeling of psychophysics and boasts a long history starting with the work of researchers such as Bernoulli, Weber and Fechner (18th, 19th century). The method models human perception of difference as a full scale logarithmic law and will be surveyed for its value in the determination of the quantitative quality of digital images

Foreground segmentation in atmospheric turbulence degraded video sequences to aid in background stabilization

Abstract: Video sequences captured over a long range through the turbulent atmosphere contain some degree of atmospheric turbulence degradation (ATD). Stabilization of the geometric distortions present in video sequences containing ATD and containing objects undergoing real motion is a challenging task. This is due to the difficulty of discriminating what visible motion is real motion and what is caused by ATD warping. Due to this, most stabilization techniques applied to ATD sequences distort real motion in the sequence. In this study we propose a new method to classify foreground regions in ATD video sequences. This classification is used to stabilize the background of the scene while preserving objects undergoing real motion by compositing them back into the sequence. A hand annotated dataset of three ATD sequences is produced with which the performance of this approach can be quantitatively measured and compared against the current state-of-the-art

Appropriate solar spectrum usage : the novel design of a photovoltaic thermal system

Abstract: The path towards zero energy buildings is fraught with many challenges, the onsite renewable energy production to drive consumer appliances that are not low or zero energy is an important challenge. Therefore, developing the energy production such that the production mode is matched to the usage mode is the simplest manner to improve efficiency. As such, energy consumption for lighting could be significantly reduced by optimizing the building`s design to maximize direct daylight usage, similarly cooking using solar stoves, or water heating using solar geysers eliminates the need for PV cells to generate electricity. The most important energy consumption in most buildings is HVAC (accounting for approximately 40% of a building`s energy consumption) which can be addressed with the use of a solar power absorption chiller. This article introduces the design of a novel solar concentrated photovoltaic thermal (CPVT) system that produces electricity and thermal energy simultaneously from the same surface area. The goal of the proposed system is to provide sufficient heat for an absorption cooling system, water heating as well as to produce electricity in a cost effective way. The CPVT system is designed to operate over a wide spectrum (400nm upward contains around 90% of the incident solar radiation spectrum). In the proposed system, solar irradiation is highly concentrated (to the equivalent intensity of approximately 100 suns) onto a single point, using a dual axis sun tracking concentrator with a Fresnel lens. A filter then separates the infrared (IR) from the visible light (VL) components using an imaging lens (viz. a hot mirror which has approximately a 98% filter efficiency). The IR is then utilized for heating while the VL components power the PV cell. The efficiency of the electricity generation in the PV cell improves when the IR component is removed from the incident solar irradiance. High-temperature high pressure water, at approximately 95-120oC (203–248oF), is generated by the IR and serves as a heat source for the absorption cooling system (lithium bromide water / ammonia-water). The proposed system is expected to deliver electricity at the rate of 0.08 W/cm2 (0.2032 W/in2) of PV cell area, and around 0.04W/cm2 (0.1.016 W/in2) collector area. Given that the ratio of collector area to PV cell area is ±9:1 this allows us to design the relative size to suit the building requirements

Particulate matter and atherosclerosis: role of particle size, composition and oxidative stress

Air Pollution has been associated with significant adverse health effects leading to increased morbidity and mortality. Cumulative epidemiological and experimental data have shown that exposure to air pollutants lead to increased cardiovascular ischemic events and enhanced atherosclerosis. It appears that these associations are much stronger with the air particulate matter (PM) component and that in urban areas, the smaller particles could be more pathogenic, as a result of their greater propensity to induce systemic prooxidant and proinflammatory effects. Much is still unknown about the toxicology of ambient particulates as well as the pathogenic mechanisms responsible for the induction of adverse cardiovascular health effects. It is expected that better understanding of these effects will have large implications and may lead to the formulation and implementation of new regulatory policies. Indeed, we have found that ultrafine particles (<0.18 μm) enhance early atherosclerosis, partly due to their high content in redox cycling chemicals and their ability to synergize with known proatherogenic mediators in the promotion of tissue oxidative stress. These changes take place in parallel with increased evidence of phase 2 enzymes expression, via the electrophile-sensitive transcription factor, p45-NFE2 related transcription factor 2 (Nrf2). Exposure to ultrafine particles also results in alterations of the plasma HDL anti-inflammatory function that could be indicative of systemic proatherogenic effects. This article reviews the epidemiological, clinical and experimental animal evidence that support the association of particulate matter with atherogenesis. It also discusses the possible pathogenic mechanisms involved, the physicochemical variables that may be of importance in the greater toxicity exhibited by a small particle size, interaction with genes and other proatherogenic factors as well as important elements to consider in the design of future mechanistic studies

Aanpassingsprobleme van Afrikaanssprekende leerders in die internasionale, multikulturele, privaatskole van Botswana (Afrikaans)

The aim of this study is to investigate the probable adaptability problems Afrikaans speaking pupils experience in the international, multicultural, private schools of Botswana and how these problems concerning adaptability can have an influence on their academic success. Over the last forty years Botswana has made name for itself as the most stable country in Africa. Here is no dictators craving for power, no poverty because of mismanagement and no violent oppression or unconstitutional behavior visible. On the contrary, since the country became independent in 1966, it only knew the road to prosperity. When the country became independent there was only eight kilometers of tarred road found in the whole of Botswana. Today the main routes don’t have to stand back one step for those found in South Africa. The local currency, the Pula, is stronger than the rand and there is less crime as what is the case in South Africa as well as much less visible poverty. Al the facts mentioned above are only a few reasons why Botswana became an attractive refuge, close but still outside the borders of South Africa, for so many South African citizens. Approximately 80% of all the companies found in the capital, Gaborone have South African roots. Since 1990 the number of South Africans that relocated to Botswana has tripled. Education plays a very important role in the prosperity of Botswana and the country spends in the vicinity of 22% of its annual budget on education. Because of the huge influx of foreigners, especially over the last ten years, a number of international, English medium, private schools were founded. In the past, these English medium schools provided mostly education for foreign learners. The current tendency is however that more and more local learners start attending especially the secondary, private schools because of the international curriculums these schools offer. Afrikaans speaking learners coming from Afrikaans medium schools in South Africa are faced with definite problems concerning adapting when they visit the international, multicultural private schools of Botswana for the first time. The four most important concepts identified in the study were the international education environment of the multicultural, private schools in Botswana, multicultural education, and the concepts culture and milieu-handicapped. The problems concerning adaptability experienced by Afrikaans speaking pupils are mostly found on the social- and cultural domains as well as adapting to the new medium of education. There are several factors, internally as well as externally from the school environment identified which can play a leading role in the successful adaptation of these learners. The social- en psychological development of the child as well as the style of education portrayed by the parents can both play a leading role in the successful adaptation of these learners. Factors that can all contribute to a more or less extend to the successful social adaptation of Afrikaans speaking pupils include the role of the school, community, peer group, church and media. Concerning the successful cultural adaptation of Afrikaans speaking pupils several factors are identified. These include cultural differentiation, cultural integration, cultural continuity, cultural relativity, cultural pluralism, the philosophy of life concerning culture, the economic technical cultural domain, the social welfare cultural domain as well as the spiritual cultural domain. Lastly the study looked at the adaptation regarding the medium of education Afrikaans speaking pupils face. Factors which play a role here include the differences of the language spoken at school, in the home and in the community as well as the influence language and culture have. The successful social- and cultural adaptation and adaptation regarding the medium of education of Afrikaans speaking pupils can all contribute to the successful academic performance of these learners. A poor academic record, limited intellectual possibilities, unfavorable personality characteristics, inadequate study methods as well as school migration can contribute to the successful academic performance of Afrikaans speaking pupils. By means of a comprehensive study of literature the factors which can play a role in the adaptation of Afrikaans speaking pupils in the international, multicultural, private schools are in detail examined and discussed. An empiric investigation, where both the Afrikaans speaking pupils and their parents played a part, was done after the study of literature. The investigation proofs that Afrikaans speaking pupils do suffer from adaptation problems and are mostly experienced in the cultural domain. Continuing research in the field of adaptation problems of Afrikaans speaking pupils, not only in Botswana but globally, should be undertaken. With the huge number of South Africans leaving South Africa this research can be a source of information to both parents and learners alike.Thesis (PhD (Curriculum Studies))--University of Pretoria, 2005.Curriculum Studiesunrestricte