A real-time DSP enabled digital subcarrier crossconnect (DSXC) with resampling filters is demonstrated based on distributed arithmetic (DA) for channel frequency translation. This circuit-based DSXC supports flexible and fine data-rate granularity of subcarrier channels, and offers the capability to improve spectral efficiency in optical networks.
Wheelset vibration response of two Transnet locomotive classes i.e. D39 200 and D44 are investigated using the modal analysis method. These two locomotive classes are the only classes used on the Belfast to Steelpoort railway line in the Limpopo Province of South Africa. The class D44 replaced the class D39 200 locomotives over two years ago. Short-pitch rail corrugation exists on rail track curves of the railway line. The axial (lateral) resonance frequencies of wheelsets from both locomotive classes prove to be more, than resonances in any other direction of vibration. This is in good agreement with the previous tests done on a class D39 200 locomotive wheelset. The axle coupling vibration response was measured in the axial direction by exciting one wheel and measuring accelerance of the opposite wheel on the wheelset. Vibration response for the class D44 wheelset shows more lightly damped resonance modes in the axial direction. The characteristics of the axial vibration response being lightly damped with the highest accelerance implies most of the vibration occurs in this direction and may be associated with most rail track damages.
The current work describes the development, construction and experimental investigation of a simple StandingWave Thermo-Acoustic Engine (SWTAE). This work aims at providing additional clarity on the construction and the performance of simple SWTAEs. The proposed SWTAE will be used to drive a traveling wave thermo-acoustic refrigerator, through the generated sound wave and ultimately induce cooling. For experimental purposes, the heat supply used in this experimental study are electric cartridge heaters. This study provides clarity as far as the temperature supplied to the system is concerned. To characterize the acoustic power of the SWTAE, the onset temperature differences across the stack for the engine to start producing sound has been measured. Three different configurations have been investigated and general trends showing the relationship between the supply heat, the generated sound wave and the minimum temperature required to produce a sound wave have been obtained.
The energy usage of space heating (SH) and water heating (WH) processes may account for approximately 60% and 24% of the total energy consumption in residential buildings, respectively. This paper proposes the optimal control of an integrated system for water and space heating at the Central University of Technology student residence. The system consists of solar PV modules, batteries, electrolyser, hydrogen storage vessel, fuel-cell, heat pump and domestic hot water storage. The main aim of this study is to propose a method to reduce the energy cost, by applying optimal control of the integrated system operating under the variable Time of Use tariff. The background on the problem statement, the literature review, aim, objective, methodology as well as expected results of the study will be discussed in the sections below.
A resistive switching memory behavior has been observed in PVA incorporated with Aluminium doped Zinc Oxide (AZO) nano particles drop cast on Alumiuium tape. An ON/OFF ratio of about 4 orders of magnitude encourages and leads to the development of ReRAM memory cell. The conduction mechanisms of different segments before and after switching has indicated a clear change of activation energies involved.
This paper presents the use of Internet of things (IoT) to solve the challenges encountered in groundwater management. We present a model for predicting the sustainability of groundwater at catchment scale, focusing on the Modder river catchment. IoT has turned out to be a standout amongst the most sought-after research subjects today. On the other hand, the concept of groundwater sustainability considers a long to medium term approach to management of groundwater. The methodology involved a detailed review and understanding most important groundwater processes and factors of an aquifer system that are related to drought management. A reflection on sustainability, the groundwater licensing tool, GIS mapping, impact of drought and sustainability in aquifers. The paper highlights the use of IoT development using the scores and ranking of climate, aquifer, equity and socio-economic factors. For the catchment that was the case study, a comparison of recharge was examined, yields, storativity, aquifer types, and lithology/rock types. This was also in addition to an assessment of the physical processes affecting groundwater systems at Modder catchment scale. A GIS map considering factors such as the climatic (climatic zones precipitation, sunshine, evapotranspiration, slope, topography), was plotted. Based on this approach, an IoTs drought decision making system is presented. Using results and findings, this paper confirms the increasing use of IoT for sustainable groundwater management.
We demonstrate a 100-Gbps (4×25-Gbps) Si Photonic WDM transmitter containing monolithically integrated Si ring modulators (RMs) and BiCMOS driving circuits. Our transmitter is designed with the large-signal circuit model for the Si RM, which allows easy and accurate optimization of the entire WDM transmitter.
In recent decades, composites made of polymers have drawn substantial interest for applications in the industries like construction, automobile, electronics, packaging, aviation, just to mention a few. Another critical area where polymer-based composite materials have found remarkable applications is in the biomedical field. This is a result of the valuable properties like lightweight, easy processing, flexibility, high-strength-to-weight, recyclability and availability. Polymers used for biomedical applications should be biodegradable, biocompatible, non-toxic and meet the right specification for which the material is design for because the human body is constantly in direct contact with the materials. Therefore, the study reported on the method of preparation, improvement of properties and the applications of various polymer-based composites in the human body. From the result, mechanical and physical properties of polymeric composites were improved by the inclusion of nanoparticles.
The The performance of the centrifugal pump drops because the suction of the pump does not allow a smooth flow of the fluid as the fluid enters the pump. The high pressure in the pump causes cavitation, and this is because the high pressure is not enough. This can result in the component of the pump breaking. The purpose of the project is to design a centrifugal pump and develop a model that can predict the amount of flow required at the suction to keep the centrifugal pump running efficiently. Suitable material was chosen based on application criteria. For most water and other noncorrosive services, grey cast iron material satisfies these criteria for the impeller and the casing of the pump. Design constraints and limitations were identified. Boundary conditions were selected. Design of the pump assembly was done on SolidWorks. Results obtained from SolidWorks were interpreted and simulated in ANSYS to determine high stress points and deformation. Different suction diameter sizes were used to simulate, the sizes were 55mm, 65mm and 75mm. Theoretical calculations were done and the results were compared with the results obtained from ANSYS. From all the results, it is found that an increase in suction diameter size can help limit cavitation and pump failure.
In this work, a walk-through survey for the geysers and boilers used in the residences at the Central University of Technology has been conducted. The survey was conducted based on the rated power, storage tank sizes and period of operation in a day. The aim of the project is to review the energy efficiency and energy consumption of the geysers and boilers. From the survey, it shows that these water heating systems are operated 24 hours without any other control or energy management activities. Which means that power is supplied 24 hours a day and the thermostats automatically switch on to heat water whenever the water temperature decreases, even when there is no hot water demand. Also, seeing that load shifting can be a challenge mainly for the morning peak period due to the high hot water demand during that time because the majority of students' classes starts in the mornings. The energy consumption during peak periods is charged more than during normal or off-peak periods. Energy management activities can be applied to water heating processes in order to reduce the energy consumption and can therefore reduce the institution's energy costs. However, the hot water consumption and human behaviour profiles of the occupants are the most important precondition to a potential energy saving.
Water heating is the major energy user in the residential sector. The hot water contribution in the residential sector of South Africa is up to 60% on an average monthly basis and accounts for more than 50% of the monthly electricity cost. Electric storage tank water waters are the main contributors to the high energy consumption in the residences and most of the heating process takes place during the peak times, when electricity is more expensive than off-peak and normal time. This and the growing population and living standards of the economy has led to the high demand of electricity and energy shortage in the country. Reducing the desired end users' water temperature has been proposed as a solution to reduce the energy consumption this practice increases chances of diseases like legionella pneumophila. The water heating process could be incorporated with the time-of-use (TOU) tariff to reduce the energy consumption by load shifting from peak demand to off-peak or normal time. Renewable energy source technologies can also be used to reduce the energy consumption; however, the renewable energy systems show a common disadvantage in meeting the energy demand during certain climate conditions. And therefore, the hybrid energy systems can be implemented to promote energy conservation and energy efficiency of the renewable energy system. To further reduce the energy consumption, the TOU tariff can be used for optimal control and energy management of the hybrid system.
The trend in humanoid robots is increasing as we move into the 4th Industrial revolution. Researchers are in a quest to design the efficient humanoid robots. However, most of the robots that have been developed up to date still suffer from high power usage as the robots are fully electrical. Furthermore, these robots are designed to be autonomous and thus cannot or have limited interaction with humans. This paper proposes an electro-hydraulic Collaborative humanoid robot system. This type of system can help humans and robots work together in achieving a task. Furthermore, an electro-hydraulic approach helps reduce the operational and idle power consumption of the entire robot though the design of an efficient control system.
Gait disorder is a deviation from the smooth and normal walking pattern. Loss of balance which greatly contributes to fall, a prevalent cause of reduced life expectancy and premature death of aging persons, is closely related to a disordered gait. Augmentative assistive mobility devices such as canes, crutches and walkers, have been employed in the rehabilitation of gait dysfunction and other mobility impairments. The rate of abandonment of these devices due to difficulty and cumbersomeness in their usage has recently directed the focus of researchers in the area of design of robotic walkers. This paper presents a review of the different existing literatures in the area of the dynamic model of wheeled mobile robot, human-robot interface design, and control algorithm formulation for assistive mobility tasks as it relates to holonomic robotic walker design.
This paper proposes a framework to explore the existing mode of communication between the Mangaung Metropolitan Municipality, the representative of water affairs (which include Bloemwater) and the communities of the Free State province in South Africa. The main problem has been identified supported by proper literature review focusing on the study area. The objective as well as a proper methodology that can be used when conducting this work have been provided with the expected goal improving the communication strategy between the different stakeholders involved in the water service delivery.
Traffic congestion in urban areas is a global challenge - leading to stifled economic growth, increased road accidents and atmospheric pollution, among other negative trends. Existing traffic management solutions have proven to be largely ineffective in medium-size African cities. Wireless sensor networks have emerged as possible cost-effective solutions, especially in under-developed countries. In this paper, we present a solution for detection and quantification of traffic congestion at signaled isolated four-way junctions in order to optimize traffic flow. The research utilizes optical sensors to collect road parameters and fuzzy logic to quantify and then prioritize entry. Simulations are used to compare strategies employed by traffic signals; the interest being to observe which of the two traffic light management schemes is more effective. The two schemes compared in this paper implement fairly weighted round-robin and fuzzy algorithms.
In these modern times electricity is one of the major forms of energy that is mostly consumed and is also in high demand by the increasing global population in to which Sierra Leone is not an exception. As a result of the high demand competing for the low generation capacity of the utilities, the Ministry of Energy of the Sierra Leone Government administration, charged with the responsibility of generating and supplying electricity, is unable to meet this demand. The rationale of carrying out this research is to see how raising awareness levels on the significance of energy efficiency practices, as a recommendation through an energy audit process, would help bring a solution to how to meet the high electricity demand.A quantitative data analysis method was used in this research. 120 structured questionnaires were used in collecting data. From the results analysis, respondents agreed that energy efficiency practices in buildings around Freetown, capital o0f Sierra Leone, would reduce electricity consumption. Furthermore, respondents agreed that an energy audit in buildings around the city of Freetown would help in detecting electricity wastage in these buildings.From the research it is recommended that building owners installed energy efficient equipment during the construction of their buildings. Universities/colleges should make energy studies compulsory for all students entering their institutions, policy makers must recommend to government the reduction of custom duties on all energy efficient electrical products imported into Sierra Leone.
This paper reflects the joint role of government, parents and the traditional custodians in reducing the high rates of mortality in the traditional initiation schools of South Africa. The main argument raised by this paper is that, traditional initiation schools are very important as they symbolize and signifies the traditional teachings and education employed when initiating young boys to manhood. Many authors recognize that accurate custom practices in initiation could reduce high number of deaths especially in the AmaXhosa clan. However, the solution towards problem in question should be applied across different clan where initiation schools are common in South Africa, and such include the involvement of government to support with legislative framework, traditional custodian to provide guidance and parents to provide necessary support where it is deemed essential for children to attend initiation schools.
In the arena of energy, there is a global integration of renewable energy technologies (RETs) into various national energy policies in order to reduce the risk of climate change. Although the Nigerian energy policy (2005) stipulated increased deployment of renewable energy technologies, concern remains about the implementations and public acceptance of the technologies. Unless the factors that constitute barriers to public adoption are identified and addressed, successful deployment of these technologies will be unattainable. This paper discusses the technical barriers to acceptance of RETs in the understanding of the Nigerian populace. The study was carried out in Oyo State of Nigeria. Using a convergent parallel mixed-method research approach, data was collected via a survey (quantitative) and focus group interviews (qualitative). There was a survey of 600 participants and four focus group interviews conducted including 23 participants. Four common technical themes emerged from the data: accessibility, complexity, maintenance, and durability. Unless the factors that constitute barriers to public adoption of the technologies are identified and addressed, successful deployment of these technologies will be unattainable. The findings of this study underscore the need for collaboration between the government, the industry, the academic and the public in the implementation of RETs in the country. This study will be a guide for policy makers in Nigeria and other African countries in developing policy interventions to address such barriers
Reducing energy demand in residential sector is an important problem worldwide. This study focuses on the awareness of residents to energy conservation and on the potential of reducing energy demand through energy-saving activities. The knowledge about demand variation in households is fairly limited in South Africa as well as the use of various tools used to analyze the demand. Due to the frequent increase of energy cost at a significant rate, many consumers are looking for ways to reduce the monthly electricity bill. The aim of the project is to identify possible areas where the consumer could reduce consumption in order to reduce the monthly bills. To achieve this, a real-time energy monitoring device "Efergy E2" was installed in the distribution board of a residential home. Among other benefits, the hourly load data analysis can provide the detailed characteristics of load demand, define the consumption patterns and can help to identify where the consumer could reduce the electricity bill. The analysis of results shows that a huge amount of electrical energy is used during peak billing periods of the day under the TOU tariff. With this information the consumer could make use of demand shifting to help reduce the bill.
Proper knowledge representation and conceptual analysis often require clear ontological support. This is particularly true for large domains in which explicit formal specifications of the terms is required for encoding knowledge, thus making it understandable to the end users. In the Internet of Things (IoT), there is a substantial development of solutions for a wide range of devices and IoT platforms. These solutions are based on existing known patterns which require interoperability for seamless connection and cross-platform resource sharing. However, to the best of our knowledge, pattern relationships for facilitating interoperability in the IoT are undocumented. The activity of developing a domain-specific ontology for the interoperability of the IoT patterns is therefore one of the fundamental steps in the organization of the IoT paradigm. It is clear, however, that this activity as well as other engineering activities, particularly with regard to the development of ontologies is often made complex by the use of confusing semantic terminologies and dense ontological structures. This often lead to ontological explicative horrors in which the essence of the ontology is hidden instead of highlighted. In this paper, we thus prefer to develop a lightweight ontology that clearly display relational dimensions between the IoT patterns. We use empirical analysis to identify core objects underneath the interoperability of the IoT technologies and patterns at a large-scale.
