Modelling internet network intrusion detection in smart city ecosystems
- Authors: Mfenguza, Wandisa
- Date: 2021-05
- Subjects: Ecosystem management , Smart cities
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22501 , vital:52382
- Description: Smart city systems are intended to enhance the lives of citizens through the design of systems that promote resource efficiency and the real-time provisioning of resources in cities. The benefits offered by smart cities include the use of internet of things (IoT) sensors to gather useful data such as power demand to inhibit blackouts and the average speed of vehicles to alleviate traffic congestion. Nonetheless, earlier studies have indicated a substantial increase in cyber-security issues due to the increase in the deployment of smart city ecosystems. Consequently, IoT cyber-security is recognised as an area that requires crucial scrutiny. This study begins by investigating the current state of intrusion detection in smart city ecosystems. Current intrusion detection frameworks lack the capability to operate under extremely limiting settings such as conditions of low processing power and fast response times. Moreover, the study also identifies that, despite intrusion detection being a highly researched thematic area, a plethora of previous studies tend to propose intrusion detection frameworks that are more suitable for traditional computer networks rather than wireless sensor networks (WSNs) which consist of heterogeneous settings with diverse devices and communication protocols. Subsequently, this study developed two candidate deep learning models, namely a convolutional neural network (CNN) and a long short-term memory (LSTM) network and presents evidence on their robustness and predictive power. Results have indicated that, unlike the CNN model, the LSTM model can quickly converge and offer high predictive power without the vigorous application of regularisation techniques. The proposed LSTM classification model obtained a remarkable 100% in detection rates and further reported 0% in false alarm and false negative rates. This study gives a broad overview of the current state of intrusion detection mechanisms for smart city ecosystems to guide future studies. The study also demonstrates that existing intrusion detection systems (IDSs) can be enhanced through the development of more robust and lightweight models that offer high detection rates and minimal false alarm rates to prevent security risks in smart city ecosystems to ensure sustainable and safe smart cities. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
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- Date Issued: 2021-05
Patterns and drivers of benthic macrofouna to support systematic conservation planning for marine unconsolidated sediment ecosystems
- Authors: Karenyi, Natasha
- Date: 2014
- Subjects: Marine sediments -- Microbiology , Biotic communities , Ecosystem management , Conservation of natural resources
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10355 , http://hdl.handle.net/10948/d1020989
- Description: Marine unconsolidated sediments constitute the largest ecosystems on earth in terms of spatial coverage, but there are still critical gaps in the science required to support conservation and ecosystem-based management. This is mainly due to the inaccessibility of these ecosystems in wave-exposed environments or deeper waters and the difficulty in observing biota in their three-dimensional sedimentary habitat. Currently, the physical driving processes of intertidal unconsolidated sediment ecosystems are much better understood than those of the subtidal ecosystems. However, these ecosystems are linked through water and sediment movement. This thesis, therefore, considers the continuum of unconsolidated sediment ecosystems across the entire continental shelf (i.e. intertidal to the shelf edge). The aim of this thesis was two-fold; (i) to advance the foundational understanding of biodiversity patterns and driving processes in unconsolidated sediment habitats, and (ii) to apply this knowledge in the development of a systematic conservation plan for marine unconsolidated sediment ecosystems. The South African west coast continental shelf was used as a case study in order to represent Eastern boundary upwelling regions. This study sought to investigate biodiversity patterns in macro-infaunal communities and determine their driving processes for incorporation into habitat classifications and the development of a habitat map. Systematic conservation plans require a map of biodiversity patterns and processes, and quantitative conservation targets to ensure representation of all biodiversity features including habitats.in marine protected areas. This thesis provided these key elements by classifying the unconsolidated sediment habitats and determining habitat-specific evidence-based conservation targets to support conservation of these important ecosystems. The application of these elements was then demonstrated in a systematic conservation plan for the unconsolidated sediment ecosystems of the South African west coast. Diversity patterns were examined using physical and macro-infauna data, ranging from the beach to the shelf edge (0-412 m). These data were analysed to develop two different habitat classifications, namely seascapes derived from geophysical and biophysical data, and biotopes derived from the combination of macro-infaunal and physical data. Multivariate analyses of 13 physical variables identified eight seascapes for the unconsolidated sediment samples from 48 sites on the South African west coast. These were based on depth, slope, sediment type, and upwelling-related processes (i.e. maximum chlorophyll concentration, sediment organic carbon content and austral summer bottom oxygen concentration). Latitude and bottom temperature were not considered major drivers of seascapes on the west coast because latitude closely reflected changes in upwelling-related processes and the temperature range was narrow across the shelf. This study revealed that productivity, a biophysical variable not usually included in geo-physical habitat classifications, played a significant role in the definition of seascapes on the South African west coast. It is therefore recommended that productivity be included in future seascape classifications to improve the utility of these classifications particularly in areas of variable productivity. Seascapes should, however, be tested against biological data to improve the understanding of key physical drivers of communities in unconsolidated sediment ecosystems. Macro-infaunal community distributions were determined along with their physical drivers for the unconsolidated sediments of the South African west coast. A total of 44 828 individuals from 469 taxa were identified from 48 sites representing 46.2 m2 of seafloor. Seven distinct macro-infaunal communities were defined through multivariate analyses and their key characteristic and distinguishing species were identified. These communities reflected five depth zones across the shelf, namely beach, inner shelf (10-42 m), middle shelf (60-142 m), outer shelf (150-357 m) and shelf edge (348-412 m). The processes driving the community structure of these depth zones were postulated to be tides, wave turbulence, seasonal hypoxia, habitat stability and homogeneity, and internal tides and/or shelf break upwelling, with drivers listed in order of increasing influence with depth. The middle shelf was further separated into three distinct communities based on sediment type, sediment organic carbon content and frequency of hypoxia. Variations in water turbulence, sediment grain size, upwelling-related variables and riverine sediment input were identified as the likely primary drivers of macro-infaunal community patterns. This chapter culminated in the development of a biotope classification based on the combination of macro-infaunal communities and their physical habitats (i.e. biotopes). South Africa has developed an expert-derived National Marine and Coastal Habitat (SANMC) Classification System which is used as a biodiversity surrogate in ecosystem assessment and spatial planning. This thesis tested the validity of this classification and the data derived Seascape classification against macro-infauna species abundance and biomass data in an effort to determine how well the different classifications represent macro-infaunal diversity of the west coast. These two classifications were also compared to the Biotope classification which combines macro-infaunal communities with their physical habitats. A canonical analysis of principle coordinates (CAP) was utilised to test the success with which each sample was allocated to the relevant habitat type in each classification. The total allocation success for each classification was used as a measure of effectiveness in terms of representing biodiversity patterns. Both classifications had similar allocation successes of 89-92 percent and 92-94 percent for the Seascape and National Habitat Classification respectively, but either over- or under-classified the macrofauna communities. The Biotope classification had the highest allocation success (98 percent), therefore it is the most accurate reflection of the macrofauna biodiversity patterns on the west coast. A key finding of this study was the increasing accuracy of classifications from physically- to expert- to biologically-derived habitat classifications. In this thesis, the Biotope classification was deemed the best representative of biodiversity patterns and was therefore used to produce the Biotope map for use in spatial assessment and planning. The distinct depth patterns that emerged in both the Seascape and Biotope classifications highlighted the need for further investigation of the relationship between depth and biodiversity. Despite variability in macro-infaunal communities, a general unifying pattern in biodiversity across the shelf was sought. Three relationships between depth and species richness have been described in the literature; namely a unimodal pattern, a positively linear relationship with depth, and no relationship between depth and species richness. These hypotheses were tested on the west coast. Two different species richness metrics were utilised to test the depth-diversity relationship, namely observed species density (spp.0.2m-2) and estimated species richness (spp.site-1). Observed species density increased from the beach to the shelf edge (350 m), then decreased to 412 m. The decline may have been due to difficulty in detecting species at greater depths as a result of sampling challenges. The inclusion of an innovative extrapolative method for estimating species richness (the capture-recapture heterogeneity model) within the Bayesian statistical framework mitigated the effects of species detection heterogeneity and revealed that species richness actually increased continuously across the shelf from beach to shelf edge. Thus the general relationship between depth and species richness is positively linear on the west coast of South Africa The new macro-infauna dataset and biotope map provided the opportunity to develop the first habitat-specific evidence-based conservation targets for unconsolidated sediments of the west coast. Species-Area Relationship (SAR) based conservation targets were developed for the biotopes using a modification of the generally accepted methodology. The accepted methodology has three steps (i) the estimation of total species richness for each habitat using the Bootstrap asymptotic estimator, (ii) the calculation of the slope of the species area curve (i.e. the z-value), and (iii) the calculation of targets representing 80 percent of the species. The inclusion of an innovative extrapolative species richness estimator, the Multi-species Site Occupancy Model (MSOM) provided better species richness estimation than the more conventional bootstrap species richness estimator, even though both are based on species accumulation. The MSOM, applied in the Bayesian statistical framework takes detectability of a species into account.
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- Date Issued: 2014
Strategic adaptive management and the efficiency of invasive alien plant management in South African national parks
- Authors: Loftus, Wynand Johan
- Date: 2013
- Subjects: Biodiversity -- South Africa -- Management , Alien plants -- South Africa , Invasive plants -- South Africa , Ecosystem management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10755 , http://hdl.handle.net/10948/d1020089
- Description: It is well known that invasive alien plants (IAPs) pose a significant threat to natural biodiversity and human well-being. Through various pressures exerted on natural ecosystems, IAPs decrease and alter natural processes that provide important ecosystems services and livelihoods to human communities. These plants also displace and out-compete natural plant communities in the areas in which they invade. Management of IAPs is a complex issue with social, environmental and financial challenges. The long-term sustainable management of IAPs requires a management approach that monitors and measures the outcomes of current management practices, and considers the lessons learnt in future decision making. Adaptive management is such an approach and is characterised by monitoring, assessment, reflection and adaptation. In this dissertation I explore IAP management within the South African National Parks (SANParks) organisation. I focus on the quality of the available IAP clearing data for monitoring and environmental decision-making and explore how strategic adaptive management (SAM) is being applied to IAP management. Strategic adaptive management is a form of adaptive management that SANParks adopted to deal with the inherent unpredictability of the social ecological systems they manage, and is primarily a learning-by-doing approach. In chapter one I describe the various impacts that IAPs have on natural environments. I also discuss management of IAPs, the national Working for Water (WfW) programme and how SANParks control IAPs in partnership with WfW. Clearing of IAPs within the borders of SANParks is funded by the Department of Environmental Affairs‘ (DEA) Natural Resource Management programmes and carried out through the Working for Water programme, under SANParks‘ Biodiversity Social Projects programme and is done on a contract basis. Contract data are stored in the Working for Water Information Management System (WIMS) database. Although IAP clearing is well established, the efficiency of overall clearing operations within the parks, and quality and reliability of the data available in the WIMS, needs to be examined. In Chapter two, I (i) assess the status of IAP clearing and the direct clearing costs in each of the five national parks (costs are inflated to 2012 equivalents using the consumer price index), (ii) assess the accuracy of workload estimations for WfW IAP clearing, and (iii) discuss the utility of WIMS as a system to collate and store accurate data for monitoring purposes, focusing on the integrity and reliability of the data, the accuracy of density estimations and whether it can inform sound decision making. The planning of future clearing contracts lacks efficiency due to inaccuracies and unreliability of input data, specifically estimates of invasive alien plant density. The accuracy of density estimation and cost of clearing varies greatly between parks and does not appear to reflect the reality on the ground. In Chapter 3, through an interview process with IAP managers, I 1) unpack the steps in the SAM ‗cycle‘ and investigate the effectiveness of implementation of each step according to respondents; 2) assess the barriers that are currently keeping managers from implementing effective IAP management; 3) discuss whether learning and adaptation is taking place, and 4) discuss how the SAM process can be modified to promote its effectiveness.
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- Date Issued: 2013
A comparison of ecosystem health and services provided by subtropical thicket in and around the Bathurst commonage
- Authors: Stickler, Meredith Mercedes
- Date: 2010
- Subjects: Ecosystem services -- South Africa -- Bathurst , Ecosystem management , Commons -- South Africa -- Bathurst , Natural resources, Communal -- South Africa -- Bathurst , Land use, Rural -- South Africa -- Eastern Cape , Ecosystem health -- South Africa -- Bathurst
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4766 , http://hdl.handle.net/10962/d1007169 , Ecosystem services -- South Africa -- Bathurst , Ecosystem management , Commons -- South Africa -- Bathurst , Natural resources, Communal -- South Africa -- Bathurst , Land use, Rural -- South Africa -- Eastern Cape , Ecosystem health -- South Africa -- Bathurst
- Description: Municipal commonage in South Africa offers previously disadvantaged, landless residents access to both direct ecosystem goods and services (EGS) that provide additional income options and indirect social and cultural services. Given that EGS production is a function of ecosystem health, it is imperative that commonage land be managed to maximize current local benefit streams while ensuring future options through the maintenance of natural ecosystem functions. The payments for ecosystem services (PES) model potentially offers an opportunity for contributing to local economic development while providing fiscal incentives for environmentally sustainable natural resource management. PES depends on the demonstration of quantifiable changes in EGS delivery due to improvement in or maintenance of high ecosystem health that are a verifiable result of modifications in management behavior. This thesis therefore compared spatial variations in (i) ecosystem health and (ii) nine direct and indirect EGS values derived from natural resources on the Bathurst municipal commonage and neighboring Waters Meeting Nature Reserve (NR) to explore how different land use intensities affect ecosystem health and the resulting provision of EGS. The results indicate that the total economic value of annually produced EGS on the study site is nearly R 9.8 million (US$ 1.2 million), with a standing stock of natural capital worth some R 28 million (US$ 3.4 million). Nearly 45% of the total annual production is attributed to Waters Meeting NR, with roughly 34% from the low use zone of the commonage and the remaining 22% from the high use zone. Of the total annual production value on the study site, roughly 59% is derived from indirect (non-consumptive) uses of wildlife for the study site as a whole, though this proportion varies from 25% in the high use zone of the commonage to 94% on Waters Meeting NR. The two largest annual production values on the study site derive from ecotourism (R 3.5 million, US$ 0.4 million) and livestock production (R 2.6 million, US$ 0.3 million), suggesting that while increased production of indirect EGS could generate significant additional revenues, especially on Waters Meeting NR and in the low use zone of the commonage, direct (consumptive) EGS will likely remain an important component of land use on the commonage. A PES project to support the adoption of silvo-pastoral practices could provide positive incentives for improved land use practices on the commonage and potentially be financed by conservation-friendly residents of the Kowie River catchment and/or increased ecotourism revenues from Waters Meeting NR. Allowing carefully designed and monitored local access to natural resources within Waters Meeting NR could also reduce pressure on commonage resources. Together, these approaches could lead to a more sustainable subtropical thicket landscape and ensure that critical natural resources remain available to support local livelihoods in the long-term.
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- Date Issued: 2010