In any developing country an increasingly higher demand for electricity supply exists. South Africa experienced load shedding during late 2007 and early 2008 and again in 2014 due to a supply shortfall. New power stations are being built to increase the capacity of the national power grid. However this is a lengthy process. Demand Side Management (DSM) was adopted by Eskom’s Integrated Demand Management (IDM) division. DSM is a short-term solution to stabilise the national grid in South Africa by managing the electricity demand on the consumer’s or client’s side. DSM aims to reduce the electricity consumption with immediate results in the short-term. DSM projects were successfully implemented at nine South African cement factories since 2012. Cement factories are ideal for the implementation of DSM projects for the following reasons: cement factories are energy intensive; have adequate reserve production capacity; sufficient storage capacity and interruptible production schedules. The aim of this study is to analyse the effect of DSM projects at South African cement factories. A detailed understanding of the cement production process is a prerequisite. Therefore a critical review of energy utilisation in the cement industry was conducted. Previous work done in the cement production field is evaluated to identify the possible literature shortfall on DSM projects. A set of five distinctive parameters was derived from the literature survey to quantify the possible effects of DSM projects at cement factories. The parameters are demand reduction and electricity cost; production targets; infrastructure; product quality and sustainability. One cement factory, Factory #1, was selected as a primary case study for the analysis model. Factory #1 was used to determine and quantify the effects of DSM projects at cement factories. A simulation was developed to verify the analysis model outcome. DSM projects were implemented at various factories in South Africa and the results from nine sites were used to validate the aim of this study. The study concluded that most DSM projects at South African cement factories were sustainable. Both the electricity supplier and the factories benefitted from the projects. The funding received from Eskom to implement DSM projects is a short-term initiative. However, sustainability of DSM projects is made possible in the long-term by the substantial electricity cost savings on the client’s or factory’s side. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Compressed air leakage accounts for up to 42% of electrical energy loss on a typical mine compressed air system. By using underground control valves it is possible to reduce the amount of air leakage. Underground valve control was successfully implemented in a South African mine. The project implementation and achieved results are documented in this study. The implementation of underground control valves initially requires a large capital investment. In this study the electrical and financial savings realised by underground valve control and surface valve control were calculated. The payback periods for each control strategy were determined and compared. It was determined that underground valve control can realise up to 40% higher electrical savings than surface control. Depending on the size of the mine and due to the large initial investment, the payback period for an underground valve control system can be up to six times longer than that of a surface control system. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

South Africa’s electricity supply is under pressure because of inadequate capacity expansion in the early 2000s. One of the initiatives funded by Eskom to alleviate the pressure on the national electricity grid was an aggressive demand-side management (DSM) programme that commenced in 2004. A positive outcome of the DSM programme was that the industrial sector in South Africa benefited from the implementation of a relatively large number of DSM projects. These DSM projects reduced the electricity costs of industrial clients and reduced the demand on the national electricity grid. Unfortunately, the performance of industrial DSM projects deteriorates without proper maintenance. This results in wasted savings opportunities that are costly to industrial clients and Eskom. The purpose of this study was therefore to develop a maintenance strategy that could be applied, firstly, to reverse the deterioration of DSM project performance and, secondly, to sustain and to improve DSM project performance. The focus of the maintenance strategy was to obtain maximum project performance that translated to maximum electricity cost savings for the client. A new performance-centered maintenance (PCM) strategy was developed and proven through practical experience in maintaining industrial DSM projects over a period of more than 60 months. The first part of the PCM strategy consisted of developing a new strategy for the outsourcing of DSM project maintenance to energy services companies (ESCOs) on the company group level of the client. The strategy served as a guideline for both ESCOs and industrial clients to implement and manage a group-level DSM maintenance agreement successfully. The second part of the PCM strategy consisted of a simplified method that was developed to identify DSM projects where applying a PCM strategy would increase or sustain electricity cost savings. The third part of the PCM strategy consisted of practical maintenance guidelines that were developed to ensure maximum project performance. It was based on the plan-do-check-act cycle for continuous improvement with an emphasis on the monitoring of DSM project performance. The last part of the PCM strategy consisted of various alternative key performance indicators that should be monitored to ensure maximum sustainable DSM project performance. The PCM strategy was evaluated by implementing it on ten different DSM projects. The results showed that applying a PCM strategy resulted in an average increase of 64.4% in the electricity cost savings generated by these projects. The average implementation cost of the PCM strategy was 6% of the total benefit generated through it. This indicated that implementing the PCM strategy was a cost-effective manner to ensure that maximum performance of DSM projects was maintained sustainably. / PhD (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2015

Costs saving measures are important for South African gold producers due to increasing energy costs and decreasing production volumes. Demand Side Management (DSM) is an effective strategy to reduce electricity consumption and costs. DSM projects have been implemented widely on South African mining systems such as pumping, refrigeration, rock transport and compressed air. Implementations have, however, been limited on gold processing plants despite the significant amounts of energy that this section consumes. The main objective of gold processing plants is production orientated and energy management is not a primary focus. This rationale is re-evaluated owing to high electricity price inflation and availability of DSM incentives. This study investigated the cost saving potential of DSM interventions on gold plants. Electrical load management was identified as a key opportunity that can deliver substantial cost savings. These savings were shown to be feasible in respect of the required capital expenditure, effort of implementation and maintenance of operational targets. Investigation procedures were compiled to identify feasible load management opportunities. The most potential for electricity cost savings was identified on comminution equipment. Consequently, a methodology was developed to implement electrical load management on the identified sections. The methodology proposed simulation techniques that enabled load management and subsequent electricity cost optimisation through production planning. Two electrical load management case studies were successfully implemented on comminution equipment at two gold processing plants. Peak period load shift of 3.6 MW and 0.6 MW, respectively, was achieved on average for a period of three months. The annual cost savings of these applications could amount to R1.4-million and R 660 000. This results in specific electricity cost reductions of 3% and 7% for the two respective case studies. Results from the two case studies are an indication of potential for electrical load management on South African gold processing plants. If an average electricity cost saving of 5% is extrapolated across the South African gold processing industry, the potential cost savings amount to R 25-million per annum. Although the costs saving opportunities are feasible, it is influenced by the reliability of the equipment and the dynamics of ore supply. This insight plays a decisive role in determining the feasibility of DSM on gold processing plants. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

MIng (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2015 / Demand side management (DSM) initiatives have been introduced by Eskom to reduce the deficit between the electricity generation capacity and the electricity usage within the country. DSM projects enable Eskom to reduce electricity demand instead of increasing generation capacity. DSM projects are more economical and can be implemented much faster than constructing a new power station. One particular industry where DSM projects can be implemented is on mines. Mines consume about 14.5% of South Africa’s electricity. Producing compressed air, in particular, is one of the largest electricity users on mines. It consumes 17% of the electricity used on mines. The opportunity, therefore, arises to implement DSM projects on the compressed air system of mines. Not only do these projects reduce Eskom’s high electricity demand, but they also induce financial and energy savings for the mine itself. However, during the implementation of a compressed air energy savings project, various challenges arise. These include, among others, operational changes, control limitations, industrial actions and installation delays. All of these can lead to a project not being delivered on time, within budget or with quality results. The purpose of this study is to investigate and address various problems that occur during the implementation of such a compressed air energy savings project. The study shows that although these problems have an impact on the results achievable with the project, significant savings are still possible. Project savings are achieved by reducing the amount of compressed air that is supplied, thereby delivering sufficient compressed air while minimising the amount of compressed air being wasted. During this study, a gold mine’s compressed air network was optimised. The optimisation resulted in an evening peak-clip saving of 2.61 MW. This saving was achieved daily between 18:00 and 20:00 when Eskom’s electricity demand was at its highest. It is equivalent to an annual cost saving of R1.46 million based on Eskom’s 2014/2015 tariffs. When savings from all periods throughout the day are taken into account, the project will produce an annual cost saving of R1.91 million.

In any developing country an increasingly higher demand for electricity supply exists. South Africa experienced load shedding during late 2007 and early 2008 and again in 2014 due to a supply shortfall. New power stations are being built to increase the capacity of the national power grid. However this is a lengthy process. Demand Side Management (DSM) was adopted by Eskom’s Integrated Demand Management (IDM) division. DSM is a short-term solution to stabilise the national grid in South Africa by managing the electricity demand on the consumer’s or client’s side. DSM aims to reduce the electricity consumption with immediate results in the short-term. DSM projects were successfully implemented at nine South African cement factories since 2012. Cement factories are ideal for the implementation of DSM projects for the following reasons: cement factories are energy intensive; have adequate reserve production capacity; sufficient storage capacity and interruptible production schedules. The aim of this study is to analyse the effect of DSM projects at South African cement factories. A detailed understanding of the cement production process is a prerequisite. Therefore a critical review of energy utilisation in the cement industry was conducted. Previous work done in the cement production field is evaluated to identify the possible literature shortfall on DSM projects. A set of five distinctive parameters was derived from the literature survey to quantify the possible effects of DSM projects at cement factories. The parameters are demand reduction and electricity cost; production targets; infrastructure; product quality and sustainability. One cement factory, Factory #1, was selected as a primary case study for the analysis model. Factory #1 was used to determine and quantify the effects of DSM projects at cement factories. A simulation was developed to verify the analysis model outcome. DSM projects were implemented at various factories in South Africa and the results from nine sites were used to validate the aim of this study. The study concluded that most DSM projects at South African cement factories were sustainable. Both the electricity supplier and the factories benefitted from the projects. The funding received from Eskom to implement DSM projects is a short-term initiative. However, sustainability of DSM projects is made possible in the long-term by the substantial electricity cost savings on the client’s or factory’s side. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Compressed air leakage accounts for up to 42% of electrical energy loss on a typical mine compressed air system. By using underground control valves it is possible to reduce the amount of air leakage. Underground valve control was successfully implemented in a South African mine. The project implementation and achieved results are documented in this study. The implementation of underground control valves initially requires a large capital investment. In this study the electrical and financial savings realised by underground valve control and surface valve control were calculated. The payback periods for each control strategy were determined and compared. It was determined that underground valve control can realise up to 40% higher electrical savings than surface control. Depending on the size of the mine and due to the large initial investment, the payback period for an underground valve control system can be up to six times longer than that of a surface control system. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Side effects of seizure medications in individuals with intellectual disabilities (ID) may affect speech and language development for this population. Research information about these effects may be useful for speech-language pathologist practitioners, since they will most likely work in environments that involve assessing and treating individuals with ID. In this meta-analysis, a total of 19 articles were reviewed to examine the side effects of AEDs in individuals with ID and seizure disorders. Side effects from AEDs were found; however, research regarding how AEDs and seizure disorders affected speech and language development was not available. Based on the findings, participants on AEDs regimens experienced a variety of side effects that included behavioral side effects, adverse cognitive side effects, and non-behavioral side effects. However, information regarding AEDs side effects and speech and language development was nonexistent. Based on the findings, further research in this is much needed for practicing speech-language pathologists in this topic. / text

Modern cryptography responds to the need for security that has arisen with the emergence of communication appliances. However, its adapted integration in the wide variety of existing communication systems has opened new design challenges. Amongst them, this thesis addresses two in particular, related to hardware integration of cryptographic algorithms: constrained environments and side-channel security. In the context of constrained environments, we propose to study the interest of the Scalable Encryption Algorithm SEA for constrained hardware applications. We investigate both the FPGA and ASIC contexts and illustrate, using practical implementation results, the interest of this algorithm. Indeed, we demonstrate how hardware implementations can keep its high scalability properties while achieving interesting implementation figures in comparison to conventional algorithms such as the AES. Next, we deal with three complementary aspects related to side-channel resistance. We first propose a new class of dynamic and differential logic families achieving low-power performance with matched leakage of information to state of-the-art countermeasures. We then discuss a power consumption model for these logic styles and apply it to DyCML implementations. It is based on the use of the isomorphism existing between the gate structures of the implemented functions and the binary decision diagrams describing them. Using this model, we are not only able to predict the power consumption, and therefore attack such implementations, but also to efficiently choose the gate structures achieving the best resistance against this model. We finally study a methodology for the security evaluation of cryptographic applications all along their design and test phases. We illustrate the interest of such a methodology at different design steps and with different circuit complexity, using either simulations or power consumption measurements.

No description available.