Faculty of Engineering and Built Environment

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Chemical oxygen demand (COD) fractionation for process modelling considerations and optimization
(2021-03) Jwara, Thandeka Yvonne Sthembile; Musonge, Paul; Bakare, Babatunde F.
Wastewater treatment is a critical chain in the urban water cycle. Wastewater treatment prevents the toxic contamination of water bodies. The notable consequences of contamination are the loss of aquatic life, upsurge of eutrophication due to nutrient overload, and potential loss of human life as a result of waterborne diseases. Wastewater works (WWW) are therefore an intrinsic component of protecting the urban water cycle and ensuring that water resources are preserved for future generations. The operation of a WWW is subject to compliance with the national legislative requirements imposed by the Department of Water and Sanitation (DWS) to ensure the preservation of water resources. These requirements oblige water and sanitation departments to employ innovative design, control and optimization of WWW. Wastewater modelling packages have presented the opportunity to simulate the wastewater treatment processes in order to maintain and sustain legal compliance with the DWS. The successful implementation of a simulation package for wastewater process optimization and modelling depends on an accurate characterization also known as fractionation of the organic fractions of the WWW influents. This thesis is a result of a comprehensive study reported for Darvill wastewater work. Darvill WWW is a 60 ML/D plant which has been receiving flows of up to 120 ML/D. The importance of the study was to motivate for the upgrade of the wastewater work to account for the increased hydraulic, organic and nutrient loading into the plant. The study looked at the application of the World Engine for Simulation and Training (WEST) and all studies required to generate data that will serve as input with the understanding the current state of Darvill WWW in terms of performance. The study presents the fractionation outcomes of the primary wastewater effluent organic matter as chemical oxygen demand (COD) and the performance by assessing the biological nutrient removal process (BNR) using BNR efficiencies in addition to the development of the Darvill WWW WEST model with the aid of the probabilistic fractionator. The fractionation was achieved through the oxygen uptake rate experiments using the respirometry method. Experiments yielded the following results: biodegradable COD (bCOD) (70.5%) and inert COD (iCOD) (29.5%) of the total COD. Further characterization of the bCOD and iCOD yielded the readily biodegradable fraction (SS) at 75%, slowly degradable (XS) at 25%, particulate inert (XI) was 50.8% and the inert soluble SI at 49.2%. The COD fractions were used and served as input to the development and evaluation of the Darvill WEST model. Calculations of BNR efficiencies were used to evaluate the effects of high inflow to the biological treatability of the activated sludge for the period September 2016 - November 2017. It was found that at inflows above design capacity, the nutrient removal efficiency reduced from an expected 80-90% to an average of 40% with an average soluble reactive phosphorus (SRP) removal efficiency being 64%. A data input file for the period of January – June 2016 was created to serve as input into WEST to develop a baseline average model for the Darvill WWW plant. The model results predicted a mixed liquor suspended solids (MLSS) concentration of 6475 mg/L for the plant during the study period this was comparable with the plant MLSS concentration of 6700 mg/L at the time which was above the design concentration of 4500 mg/L. This was largely due to the plant operating under nutrient overload conditions. The final effluent (FE) concentration in the defractionation model was found to be COD = 41.28 mg/L, ammonia (NH3) = 22.02 mg/L, Total Suspended Solids (TSS) = 32 mg/L, SRP = 2.16 mg/L. Most of these results were expectedly non-compliant to the discharge limits imposed by the DWS with the exception of COD. The plant FE measurements were COD = 45.1 mg/L, NH3 = 3.4 mg/L, TSS = 20.9 mg/L, SRP= 6.67 mg/L. The COD and TSS prediction were comparable to the model prediction however there were limitations in the models ability to predict NH3 and SRP. The model does not account for changes in dissolved oxygen (DO) and temperature as these parameters are kept constant for the purpose of this study. The model assumes a temperature of 20 oC and a DO concentration of 2 mg/L for the aerobic reactor, 0.01 mg/L for the anaerobic reactor and 0.1 mg/L for the anoxic reactor. The model assumes that with the nutrient overload, oxygen compensation occurs within the reactor to maintain a constant DO concentration within the units. This limits the model in the prediction of actual instance where the overload would deplete the DO and where other competing reactions would give rise to greater non-compliances as well as biological growth’s impairment due to cold weather conditions.
Experimental and statistical evaluation of the performance of Chitosan as a coagulant in the treatment of sugar refinery effluents
(2015) Pambi, Ritha-Lorette Luti; Musonge, Paul
The implementation of new water regulations from the local government has been a motivation for most industries to treat the effluent before disposal or reuse within the plant, in order to save costs and avoid sanctions. Tongaat-Huletts sugar refinery has therefore invested in this collaborative research with the Durban University of Technology in order to investigate new technologies for wastewater treatment and water recovery using an organic coagulant called chitosan. Chitosan is a natural non-toxic polymer extracted from the exoskeleton of crustaceans. Chitosan has gained extensive attention as a coagulant in the treatment of wastewaters from various industries. However, no attention has been given to the coagulation of effluents from the sugar industry using this polymer. In this work, chitosan coagulant (CCo) was prepared by dissolution of known amounts of chitosan powder in aqueous acid at 50℃. The solution was diluted to desired concentrations using distilled water at room temperature. The removal of impurities using chitosan was investigated for two effluent streams from the sugar refinery, namely the final effluent (FE) and the resin effluent (RE) by applying the one-factor-at-a-time (OFAT) method. The optimum chitosan loading was found to be 138 mg/l for the RE and 7.41 mg/l for the FE, beyond which the efficiency of the coagulant decreased. The coagulation of FE removed 97% of the total suspended solids (TSS), 61% colour and 35% chemical oxygen demand (COD). The treatment of RE resulted in the removal of 68% TSS, 30% colour and 15% COD due to its high content of impurities. Therefore, RE was not considered for statistical studies. The Box-Behnken (BBD) design, which is a statistical response surface methodology (RSM) model was used to study the simultaneous effect of pH, coagulant loading and settling time on the removal of the COD, TSS and colour, with the help of an overlay plot for the FE. The optimum values from the overlay plot were 92% for TSS, 83% for colour and 29% for COD. The model equations generated by the BBD for individual responses involved all the manipulated variables contrary to the OFAT which only considered one manipulated parameter per response. Moreover, the BBD allowed the simultaneous analysis of all the parameters and the identification of interactions which occur when the effect of one factor is dependent on the level of another. The most important interaction for the removal of TSS was the combination of the variation in pH and coagulant dosage. The COD removal was mostly affected by the interaction between the coagulant loading and the settling time. The colour removal increased with the simultaneous increase of the pH and the settling time. A comparative study between the wastewaters from the sugar industry, the brewery industry and milk processing industry revealed that the performance of the chitosan was also affected by the amount of total dissolved solids (TDS) in the wastewater. A model was developed relating the TSS, COD and TDS from all these wastewaters, and was used to predict the TSS removal for the effluent from the olive oil mills and the wastewater from the winery. Chitosan can be considered as a good alternative to inorganic and synthetic coagulants for the pre-treatment of the FE due to its ability to efficiently remove the levels of TSS and colour. Furthermore, the production of chitosan from crustacean shells is a good method of reducing pollution from the fishery industry. Chitosan can be produced locally at low cost due to both the abundance of crustacean shells in the coastal regions of South Africa and the simplicity of its preparation process. It is recommended that a mathematical model be developed to accurately predict the influence of chitosan on all types of effluent. Such a model will provide an indication of the performance of the chitosan and guide experimenters. It is further recommended that the effect of the use of organic coagulants on the destabilization of dissolved solids in wastewater be given greater attention.
The extraction of power and fresh water from the ocean off the coast of KZN utilising ocean thermal energy conversion (OTEC) techniques
(2021-02) Gumede, Makhosonke; Naidoo, Pat; D'Almaine, George Frederick
Ocean thermal energy conversion (OTEC) is an electric power generation system which uses the temperature difference between warm water at the surface (26 oC) and cold water from the depths (5 oC) of the ocean. Generating electricity is not the only function of OTEC as it can also produce significant amounts of fresh water. This can be very important, for example on islands and in some regions, such as Port Edward, where fresh water is limited. This thesis sets out to harness this fluidic energy, thus generating significant amounts of useful electric power for insertion into the national grid, as well as fresh water in Port Edward on the KwaZulu-Natal (KZN), South Coast. The site of Port Edward is naturally suited to the establishment of alternate energy collection sources such as OTEC; the geographical location of this region is additionally suited to the development of Open Cycle - Ocean Thermal Energy Conversion (OC- OTEC). Port Edward lies just beneath the tropic of cancer and on the shore of the Indian Ocean thus two important elements needed for OTEC namely constant sunlight and large coastal areas can easily be found in this region. More importantly, the steep drop in water depth down to 3000 meters makes this an ideal research site for ocean thermal energy conversion in KwaZulu-Natal (KZN). If the proposed theories are correct, this can possibly be used for base generated energy capacity and fresh water. The results are presented with reference to the temperature difference between the sea surface and the sea bottom because it is an important parameter in choosing an actual plant site and system design of OC-OTEC. This research is mainly laboratory based concentrating on design, calculations, modelling and simulation of OC-OTEC. The thermodynamic fluid calculations were undertaken with a view to design the main mechanical components of an OC-OTEC system, i.e. flash evaporator, condenser and steam turbine. SOLID EDGE software was utilized to design OC-OTEC plant and ASPEN PLUS V8.6 software was used to simulate and model the experiment. An OC-OTEC demonstration plant was designed and constructed in an Electrical Power Laboratory at Durban University of Technology (DUT). The experimental study was carried out on the demonstration plant with consideration given to water temperature, mass flow rate of fluid, and pressure. The measurements were taken before and after each component. The selection of a good process modelling and simulation tool was of extreme importance for the success of this work. Throughout the measurements, we found that the thermal efficiency (%) and the power output increased with increasing temperature difference Δt = tw - tc. The power output was produced when the total temperature difference was sufficient to allow heat transfer within the evaporator and provide a pressure drop across the turbine. There was more heat transfer (steam produced) in the flash evaporator at a constant flow rate because the warm water continuously supplied heat energy to the evaporator without losing much energy through the process, therefore continuous feed to the turbine improved constant power output. The thermal efficiencies were increased with increasing pressure across the turbine. The increase of pressure drops across the steam turbine caused the output power to increase. The larger flow rates of the warm water lead to higher amounts fresh water produced from the condenser. The final step in this process was the design of the main components of a practical plant to be used as a pilot plant at a selected location on the KwaZulu-Natal South coast. This will address the problem of lack of water in the region.
Green roofs and stormwater runoff quality in the urban landscape in South Africa
(National Research Council Canada, 2021-06-20) Sucheran, Arisha; Sucheran, Reshma
A number of sustainable urban drainage systems (SuDS), such as green roofs, are being developed and implemented in cities around the world to help reduce stormwater runoff and improve stormwater runoff quality. This study compares the water quality of green roofs with that of conventional roofs in the eThekwini region, South Africa. Samples of stormwater runoff from the different green roof systems on the eThekwini Green Roof Pilot Project were collected to test their level of contaminants and pollutants. The tests focused on all physical, aesthetic, chemical, and microbiological determinants pertaining to stormwater runoff. For all tests, the level of contaminants and pollutants were measured against the South African Water Quality Guidelines Volume 7 for Aquatic Ecosystems. The data revealed significant variations in pollutant concentrations between the green roofs and the conventional roof. Moreover, runoff water quality varied across the various roof types, which may indicate that the substrate composition has the greatest impact on green roof performance regarding rainwater quality. Overall, the results suggest that these green roof systems do not have the ability to filter pollutants out of stormwater runoff, but rather increase their levels of concentration.
Hybrid syntactic foam core cased natural-glass fibre sandwich composite
(2023-05) Afolabi, Olusegun Adigun; Kanny, Krishnan; Mohan, Turup Pandurangan
Composite materials comprised of two separates with different properties to form a single material that reflect the properties of the combined materials. Syntactic foam composites (SFC) are made from the combination of hollow glass microspheres and epoxy resin. They are lightweight and used as a core in the hybrid sandwich composite. Hollow glass microspheres (HGM) are high strength microballoons that provide closed cell porosity and help to reduce material weight. SFCs made of HGM, and resin matrix are used as the core in sandwich composite material and reinforced with natural or synthetic fiber materials. The sandwich syntactic foam composite (SSFC) has a wide range of applications in the marine, aerospace, structural, and automobile industry. Therefore, it is important to investigate their physical, mechanical, thermal, and morphological properties to achieve high strength and low density. Most of the previous work in literature employed the use of different fillers and core materials in sandwich composite but are limited in strength because of their high density. In this study, a single HGM filler was employed as heterogeneous and homogenous by varying into four different particle sizes to investigate the effect of these particle sizes on the mechanical and physio-mechanical properties of the SFC used as the core in the SSFC. The effect of wall thickness and radius ratio of the HGM on the microstructural properties of SFC was also determined. The heterogeneous and homogeneous SFC was fabricated by degassing method mixing the epoxy matrix with HGM filler, the filler was varied into five-volume fractions of 5, 10, 15, 20, and 25%. The functional group of the HGM filler and the neat epoxy was determined and compared with that of the SFCs fabricated using Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the filler contain various functional groups such as hydroxyl group, phenol-OH, aldehyde C-H group, aromatic proton, epoxy group, which enhanced the bonding process. It was determined that the intensity of the SFCs for all the volume fractions increased more than the neat epoxy due to the shifts in the peaks representing the filler and the matrix groups. The physical (density, water absorption, buoyancy) properties and the mechanical (hardness, tensile, flexural, and impact) properties of the SFCs improved significantly compared with the neat epoxy. The Scanning Electron Microscopy (SEM), Dynamic Mechanical Analysis (DMA), and Thermo-gravimetric Analysis (TGA) were also used to determine the morphological structure, the viscoelastic properties, and degradation temperature of the HGM and the neat epoxy and compared with the fabricated SFCs. The surface of the HGM showed the microballoons in their different sizes before separation. The surface of the SFCs showed the epoxy matrix, matrix porosity, microballoons porosity, and microballoons structure in their mixed state. It was an indication of good interaction between the epoxy matrix and the HGM filler using degassing processing method. The DMA showed improved storage and loss modulus values by 9% and above 100% respectively compared to the neat epoxy and the TGA showed better glass transition Tg values of 4.5% and 2.7% at 20% and 55% weight loss respectively compared to the neat epoxy. This indicated that good interaction and interfacial bonding existed between HGM and the epoxy matrix and because of lower density and void content. The SFC was used as the core to fabricate a lightweight sandwich syntactic foam composite (SSFC). The SSFC was made into four different orientations (kenaf-SFC-kenaf, as KK; glass –SFCglass, as GG; glass/kenaf – SFC – kenaf/glass, as GK; and kenaf/glass –SFC- glass/kenaf, as KG) using kenaf and glass fibers as reinforcement. The physical properties (density, water absorption capacity, and buoyancy), mechanical properties (hardness, tensile, compression, and flexural), morphological properties (SEM), and acoustic properties were determined. The porosity of KK increased by 21.6% because the kenaf fiber is less dense and more porous in terms of water absorption which makes it require higher buoyancy force to stay afloat. The mechanical properties results showed that GK and KG have the highest hardness, flexural and compressive strength of 70.2%, 74.4%, and 42.7% respectively, while GG has improved tensile strength of 210.96% increase than KK. The acoustic properties results showed that GG improved in sound level (P) dB by 24.1% compared to KK, while the sound pressure (Lp) dB does not show a significant difference in the SSFC. In conclusion, the degassing processing method of SFCs improved its physical and mechanical properties by reducing the density using particle distribution analysis (PSA) and particle variation analysis (PVA) with the aid of a gas pycnometer, and porosity values thereby making it a suitable core material for the sandwich composite. A novel sandwich syntactic foam composite (SSFC) material was fabricated by hybridizing the face-sheets in different layering pattens. The SSFC physical and mechanical properties improved significantly with the use of hybrid fibers. Hence, this study has demonstrated that for structural and marine purposes, hybrid fibers can perform better as reinforcement in the sandwich composite than using a single fiber.
Increasing the use of fibre-reinforced composites in the Sasol group of companies : a case study
(2007) Mouton, Jacques
A composite material comprises two or more materials with properties that are superior to those of the individual constituents. Composites have become important engineering materials, especially in the fields of chemical plant, automotive, aerospace and marine engineering. The development of more advanced materials and manufacturing techniques in composites has grown from humble beginnings in the 1930s to a recognized and well-respected engineering discipline, providing solutions to conventional and challenging applications. At present, fibre-reinforced composites (FRCs) are amongst the most common types of composites used. They are produced in various forms with different structural properties, and designers, specifiers and end-users can choose from an almost endless list of these materials, providing design flexibility as well as low manufacturing and maintenance cost. Many suggest that composites have revolutionised the chemical and petro-chemical industries. Examples of applications include tanks and chemical reactor vessels that contains many hundreds of litres of hazardous chemicals, reinforced pipes measuring up to several meters in diameter conveying dangerous gases and so on. The South Africa Coal, Oil and Gas Corporation Limited (SASOL) was established in September 1950. From a small start-up, the company has grown to be a world leader in the commercial production of liquid fuels and chemicals from coal and crude oil. Sasol manufactures more than 200 fuel and chemical products at its main plants in Sasolburg and Secunda in South Africa as well as at several other plants abroad. Its products are exported to more than 90 countries around the world. The use of composites in general, and fibre reinforced composites in particular has received little support in Sasol through the years. Some sporadic use of these materials in the construction of process equipment, e.g. tanks, vessels and piping has taken place with varying degrees of success. While the use of equipment fabricated with fibre-reinforced composites has proven extremely successful in the chlorine producing facility in Sasolburg, catastrophic failures have taken place in Secunda in critical fire water systems made of these materials. The history of correct use and application of fibre-reinforced equipment has shown that the cost of ownership of such equipment is significantly lower than similar metallic equipment, therefore reducing costs and safety risks. However, even though this technology brings a company like Sasol closer to the realisation of the vast number of advantages and solutions offered by these materials, the reality is that most engineering personnel are still applying traditional (viz. steel and wood) technology as used by our predecessors. The work presented here attempts to indicate the relevance of fibre-reinforced composites for Sasol, and to detail efforts aimed at the raising of awareness amongst appropriate personnel at Sasol to increase the use of these materials in major capital projects and day-to-day maintenance contracts, therefore taking advantage of the superior performance of fibre-reinforced composites in demanding applications. In support of this drive, part of the work presented indicates the status as well as progress of the composites industry in the last few years. This project was therefore aimed at identifying the level of utilization of fibre-reinforced composites at Sasol, and the possible improvement in benefits of using these technologies. A methodology was developed, using engineering as well as marketing principles, to reach the engineering personnel in various divisions and seniority levels of Sasol to increase the awareness of the capabilities of composites materials, specifically regarding fibre-reinforced composites. Questionnaires were used to gauge the level of awareness while various methods, e.g. one-on-one meetings, seminars, conferences, electronic media, etc were used to upgrade the target groups’ knowledge. The results of the initial survey to determine the status of various dimensions in the company are indicated as well as the outcomes at the end of the research period. In support of the process in Sasol, the development, interaction and cross-pollination of international and national role-players in the fibre-reinforcement industry with respect to chemical containment and Sasol are indicated. The importance of this two-legged process is demonstrated: it ensures a professional national support framework for companies like Sasol. Results are indicated, compared and discussed to give future direction in this ongoing process. As important to this process was the development of appropriate technical resources (like design standards and codes) to enable their use within the group. It was recognised early on that raising the level of awareness of the target groups was not enough and that these resources had to be in-place down the line so that those who chose to could start to implement these material technologies with the aid of the resources. The development of the necessary resources is also discussed. Finally, it will be shown that significant growth has taken place regarding the awareness within the group over the course of implementation of this project. Specifically, about 20% of the target groups have moved from a stage of no knowledge to higher levels of confidence. In terms of use of these materials, significant growth has also taken place judging by the number of plant requests, activity on major capital projects and so on. In fact, from almost nothing in 1999, over the last 5 years in excess of R137 Million has been spent on capital equipment manufactured from composite materials, with the majority in the last 2 years.
Life cycle assessment of the production of cement : a South African case study
(2021-12-01) Olagunju, Busola Dorcas; Olanrewaju, Oludolapo Akanni
The relentless ongoing pursuit of innovation, development, urbanization and immigration for a better quality of life has impacted the natural environment. Also, the various consequences of continuous industrial activities are seen in the departure from what is supposed to be the norms of nature and an ideal environment free of toxicity, pollution and unquantifiable instantaneous changes. One of these is variation in temperature experienced in recent times as against what it was about 2000 years ago before the industrial revolution. A world with an increasing population requires infrastructure to support this growth. The construction industry is able to support this growth by building necessary structures that will accommodate environmental sustainability. However, the construction industry is responsible for several environmental impacts as a result of various activities. Concrete is one of the major base materials used in the construction industry and cement is an essential ingredient in concrete production. Several environmental impacts ranging from high greenhouse gas (GHG) levels to high energy consumption (fossil fuel and electricity) to high resource usage are associated with cement production. Quantifying these impacts is a major roadmap to reducing them. In this study an analysis of the production model of South African cement plants was carried out so as to quantify its impacts, and know how they consequently affect the lives of South Africans, her resources as well as the ecosystem; so that proper mitigation strategies can be recommended. The study carried out a Life cycle assessment (LCA) of cement using both the midpoint and endpoint approaches of the LCIA. LCA is a tool used to analyze the environmental impact of a process or product from start to finish. This study carried out a cradle-to-gate analysis of 1kg of cement produced in a typical South African plant using data from the Ecoinvent database and SimaPro 9.1.1 software. The result showed that for every 1kg of cement produced, O.993 CO2 eq, was emitted into the atmosphere; 98.8% was actual CO2 emission and its resultant effect was global warming which causes changes in climatic conditions. Also, 1.6kg of 1,4-Dichlorobenzene (1,4-DCB) eq was emitted into the air and water, which caused high toxicity in these media and for every 1kg of cement produced, 0.139kg of oil eq was produced and its effect was seen in fossil resources scarcity. Of this value, 0.125kg was from the burning of coal In both approaches, the result was further analyzed with respect to five major production processes: (1) Clinker production (2) Raw material consumption (3) Electricity usage (4) Fuel consumption and (5) Transportation. The results showed that the clinker production stage contributed 76.3% to global warming; and raw material consumption contributed 95.9%, 99.9%, 90.7%, and 77.9% to ionization radiation, mineral scarcity, fossil resource scarcity and terrestrial ecotoxicity, respectively. Fuel consumption contributed 98.6%, 96.3%, 85.7% and 76.9% to freshwater eutrophication, marine eutrophication, human carcinogenic toxicity, and human non-carcinogenic toxicity, respectively. Electricity usage contributed 65.8% and 64.8% to stratospheric ozone depletion and fine particulate matter formation, respectively. Though South Africa relies on the importation of clinker and cement, in the endpoint approach an estimation was carried out based on the annual requirement of cement in South Africa without importing either commodity. The result showed that 55 404 was the potential number of human lives that could be endangered annually; 133 species had the potential to be endangered annually, and the effect of a potential scarcity of resources caused total a marginal price increase of R6.2 billion due to these damages. The results of the analysis are in line with previously published literature but with slight variations. In conclusion, the study prescribed mitigation and adaptation strategies to counter these environmental impacts.
Lighting up the future of ports with LED
(SAICE, 2016) Naicker, Rowen; Allopi, Dhiren
Ports and terminals compete fiercely for container traffic. Those with the most efficient operations stand to win the most business and generate the highest profits. Driving down costs is crucial to remaining competitive. Upgrading to the latest light emitting diode (LED) lighting technology contributes to terminal cost control. Light fixtures installed on port container cranes endure constant vibration, moisture and corrosion - elements always present in marine environments. These extreme conditions result in premature lighting fixture failure, demanding constant maintenance and increasing material and labour costs. Installing properly designed LED fixtures on port container cranes can immediately reduce energy usage, reduce crane maintenance costs and increase operator safety, while moving terminal operators closer to the universal goals of safety, sustainability and profitability (Hertel 2009: 70).
A meta-analysis of channel switching approaches for reducing zapping delay in internet protocol television
(Institute of Advanced Engineering and Science, 2021-06) Adeliyi, Timothy T.; Ogunsakin, Ropo E.; Adebiyi, Marion O.; Olugbara, Oludayo O.
Channel zapping delays are inconveniences that are often experienced by the subscribers of Internet protocol television (IPTV). It is a major bottleneck in the IPTV channels switching system that affect the quality of experience of users. Consequently, numerous channels switching approaches to minimize zapping delay in IPTV have been suggested. However, there is little knowledge reported in the literature on the determination of the strength of the evidence presented on the approaches of reducing zapping delay in IPTV, which is the prime purpose of this study. The extraction of the relevant articles was designed following the technique of preferred reporting items for systematic reviews and meta-analyses (PRISMA). All the included research articles were searched from the widely used databases of Google Scholar, and Web of Science. All statistical analyses were performed with the aid of the random-effects model implementation in Stata version 15. The overall pooled estimated delay component was presented in forest plots. Overall, thirteen studies were included in the meta-analysis and the overall pooled estimate was 10% (95% CI: 7%, 30%)). Experimental studies have shown that virtual elimination of IPTV zapping delay is possible for a relevant chunk of channel switching requests.
Methodologies for the optimal design of fibre-reinforced composite structures
(2003) Smith, Ryan Elliot; Walker, Mark
Composites have become important engineering materials, especially in the fields of automotive, aerospace and marine engineering. This is due to the high specific strength and stiffness properties they offer. At present, fibre-reinforced plastic (FRP) laminates are some of the most common types of composite used. They are produced in various forms with different structural properties. As with all engineering materials, there is the existence of both advantages and disadvantages. One of the main disadvantages is the expense involved in producing both the material and the finished product. The design time is also costly as the material has to be designed concurrently with the structure.
Reducing straddle carrier accidents at the Port
(IOSR Journals, 2015) Naicker, Rowen; Allopi, Dhiren
Abstract: The Straddle Carrier (SC) is a very popular piece of equipment. These carriers can undertake a variety of handling operations such as loading, unloading, stacking and transport of containers between the landside and waterside. Its popularity is due to its space efficiency and flexibility. Traffic incidents are a serious problem at marine terminals, where heavy equipment is used to load and unload ships and move freight from place to place in the terminal. The work is fast-paced, conducted at any time of the day or year, and often performed in inclement weather. Vehicular traffic endangers any worker walking in a marine terminal In a typical straddle carrier operation, what procedures/methods can be put in place to move towards a zero accident policy? It goes without saying that the operator should be properly trained. But how do you make sure that it is the trained operator that is driving, and what mechanisms can you put in place to monitor and review the safe operation of the equipment. Waiting for the next accident is not an option (Lambert 2009:1).
A study to assess the energy savings potential in the ocean going trawler 'Roxana Bank'
(1990) Fiddler, David Michael; Gowans, B.; Calder, P.
Increasing fuel prices have forced marine engineers and diesel engine manufacturers to look at methods of. reducing fuel consumption without a loss in output power. Engineers are always Investigating the following points: (1) decreasing the specific fuel consumption (2) enabling engines to use worse fuels ... (3) extending part load capability (4) using as much waste heat as possible. The sources of heat loss are investigated and the design of an efficient heat recovery system has been evaluated for Ideal temperature and heat conditions. after taking lnto consideration the various methods of heat recovery that are possible on the fishing trawler MFV Roxana Bank. Sources of heat loss identified by engine manufacturers are found primarily in engine cooling water and exhaust systems. These methods are investigated and extra heat transfer systems have become apparent. The use of exhaust gas boilers in diesel engine installations has become widespread as there is always a demand for heating services regardless of vessel type. The predominant form of heat transfer on the Roxana Bank is by forced convection and fluids must always remain in a turbulent state when passing through heat exchange apparatus. The introduction to heat exchangers shows that a high degree of turbulence in both primary and secondary fluids will the overall heat transfer coefficient and also reduce fouling. The design parameters of the heat recovery systems discussed as suitable for the Roxana Bank require the existing cooling water system to be scrapped and a fresh water system with one central cooler to be designed with a high temperature and a low temperature circuit together with a variable speed pump arrangement. should be fitted with such central cooling systems for a number of reasons. The central cooler system Is discussed In detail and it is shown that existing ships and/or new buildings The heat recovery system requires a certain degree of automation to prevent undercooling of the main engine systems and to maintain set Inlet and outlet temperatures to makers specifications. After attending the Roxana Bank on the 09/10 November 1989, the monitored operati~g parameters show a marked deviation to the Ideal temperatures, particularly In the cylinder cooling water circuit ... temperatures. The adverse effects these deviations have on the heat recovery and combined engine load fluctuations found on the Roxana Bank show that steady state heat recovery Is difficult to achieve on this particular type of vessel. Through calculation it Is shown that the envisaged steam turbine alternator is not practical due to the combination of low feed water inlet temperatures to the boiler and insufficient driving steam. The consequence of the reduction in electrical load on the power take off alternators have on the exhaust gas mass flow rates due to reduced engine load are also discussed. A brief mention is also made of organic fluid and thermal oil systems as a form heat recovery and possibilities for efficient heat transfer using these systems. ii Recommendations are made to Irvin and Johnson with regards to a centralised cooling system and the benefits that can be realised with regard to more efficient heat exchanger operations, but that heat recovery on the Roxana Bank from the proposed sources is not a viable proposition.
A taxonomy on smart healthcare technologies : security framework, case study, and future directions
(Hindawi Limited, 2022-07-05) Chaudhary, Sachi; Kakkar, Riya; Jadav, Nilesh Kumar; Nair, Anuja; Gupta, Rajesh; Tanwar, Sudeep; Agrawal, Smita; Alshehri, Mohammad Dahman; Sharma, Ravi; Sharma, Gulshan; Davidson, Innocent E.
There is a massive transformation in the traditional healthcare system from the specialist-centric approach to the patient-centric approach by adopting modern and intelligent healthcare solutions to build a smart healthcare system. It permits patients to directly share their medical data with the specialist for remote diagnosis without any human intervention. Furthermore, the remote monitoring of patients utilizing wearable sensors, Internet of Things (IoT) technologies, and artificial intelligence (AI) has made the treatment readily accessible and affordable. However, the advancement also brings several security and privacy concerns that poorly maneuvered the effective performance of the smart healthcare system. An attacker can exploit the IoT infrastructure, perform an adversarial attack on AI models, and proliferate resource starvation attacks in smart healthcare system. To overcome the aforementioned issues, in this survey, we extensively reviewed and created a comprehensive taxonomy of various smart healthcare technologies such as wearable devices, digital healthcare, and body area networks (BANs), along with their security aspects and solutions for the smart healthcare system. Moreover, we propose an AI-based architecture with the 6G network interface to secure the data exchange between patients and medical practitioners. We have examined our proposed architecture with the case study based on the COVID-19 pandemic by adopting unmanned aerial vehicles (UAVs) for data exchange. The performance of the proposed architecture is evaluated using various machine learning (ML) classification algorithms such as random forest (RF), naive Bayes (NB), logistic regression (LR), linear discriminant analysis (LDA), and perceptron. The RF classification algorithm outperforms the conventional algorithms in terms of accuracy, i.e., 98%. Finally, we present open issues and research challenges associated with smart healthcare technologies