• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 66
  • 29
  • 6
  • 4
  • 4
  • 4
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 139
  • 139
  • 69
  • 30
  • 30
  • 28
  • 28
  • 24
  • 20
  • 16
  • 13
  • 12
  • 12
  • 11
  • 11
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Investigation of the Ramotswa Transboundary Aquifer area, groundwater flow and pollution

Modisha, Reshoketswe Caroline Oudi January 2017 (has links)
A research report submitted to the Faculty of Science, in partial fulfilment of the requirements for the degree of Master of Science in Hydrogeology, School of Geosciences, University of the Witwatersrand. Johannesburg, June 2017. / Groundwater is a principal source of water for many semi-arid countries, including Botswana and South Africa. This is especially true for the rural communities within these regions that lie on the periphery of local water scheme pipelines and make direct use of groundwater. The Ramotswa transboundary aquifer, which supplies local communities and nearby cities with fresh groundwater, is a highly productive and unique karst sequence shared by South Africa and Botswana. The objective of the study was to contribute to the available hydrogeological data by means of evaluating groundwater flow, nitrate pollution and the median recession index and master recession curve for the aquifer. The interpreted airborne geophysical data revealed the presence of collapsed features in the northeastern area corresponding to the karst morphology. A piezometric map of the area shows the groundwater flow is towards the north-northeast, which is supported by salinity increase across the study area. Increased nitrate concentrations were identified in areas with increased rainfall, shallow groundwater and a mature karst system. Only 3% of the 36 sample sites had nitrate concentrations exceeding the WHO guideline limit of 50 mg/l. This was attributed to the legacy of unlined pit latrines in karstified areas. Pollution is entirely anthropogenic and generally from non-point sources. A median recession index computed by RECESS program from the Dinokana spring discharge data was 295.7 days per log cycle and the generated master recession curve’s gentle slope alludes to massive storage potential within the karst compartment. The results of the study can alert stakeholders alike of the health risk of direct consumption of the groundwater without pretreatment. Establishing an understanding of the nitrate pollution sources and groundwater flow direction, and estimating the recession index provides informed groundwater pollution and vulnerability management options. This can improve the aquifer resource assessment and the livelihoods of local communities in the face of increasing climate change. / XL2017
12

Application of water pinch to an integrated pulp and paper Kraft mill with an already highly closed water system.

January 2009 (has links)
Sappi's Ngodwana integrated Kraft pulp and paper mill was used as case study for the application and evaluation of the water pinch technique. The technique of water pinch originates from energy pinch, but uses mass flow and contaminant concentration to identify water and effluent reduction opportunities. The classical meaning of pinch, as defmed by energy pinch has however been changed to a more modem meaning. Historically the terms water or energy pinch was used to refer to the points where two composite curves touched on energy or water graphs. This graphical meaning of pinch is gradually being replaced to refer to the optimal po int proposed by a numerical solver beyond which improvement of the water network is no longer possible for the given inputs. The water pinch technique was applied by means of a numerical solver that used mixed integer non-linear programming to optimise to the minimum cost for running the water network under investigation. The problem defmition was defined in terms of costs associated with the use of utilities, raw material, treatment facilities and process units. It was also possible to define factors such as environmental impact, corrosion, fouling, scaling, cooling tower treatment cost, legal risk etc in terms of a penalty cost. The water pinch technique has been refined in software packages that are user friendly, ca~ble of handling multi-contaminants and suitable for varying flows. The software package WaterPinch by Linnhoff March was used. The case study was applied on Ngodwana mill that has an already highly closed water system with effluent generation rates as low 20 kL per ton of pulp and paper. The pinch study included sodium, chloride, calcium, suspended solids and COD as contaminants. The study investigated different applications of the pinch technique. The following was concluded: • The mill's understanding of its current restrictions, ()l pinch points, of its water network was confirmed. No new pinch points have been identified of which the mill was not aware. This indicates that the mill was already highly knowledgeable about its water system. This was expected of a mill that has a very low specific-effluent-generation rate. Water pinch was unable to significantly improve on the effluent generation rate of the mill. • The pinch analysis has identified opportunities of mixing small quantities of waste streams into process water streams to replace fresh water. These changes can introduce minor water savings and new risks to the process that have to be understood better before implementation. • The mill has progressed far with the design and costing of a proposed effluent treatment plant (ERPl). The integration of this treatment plant into the water network was investigated using the pinch technique. The pinch solver suggested a totally different approach to the integration of the ERPI plant compared to design of the mill. The mill's design revolves around the treatment of low chloride streams in the ERPl plant and using of the treated water as make-up to the cooling towers. Sodium was recovered as raw material from the cooling towers' blow-down. Pinch proposed treatment of the high cWoride containing streams and returning the streams to users suitable of using high chloride water. The network proposed by mill's design generates 8.2 MLlday effluent less than the pinch proposal, and recovers sodium as raw material. The proposal presented by pinch is not recommended and points to the difficulty in simulating factors, such as raw material recovery, in a pinch analysis. • Users for the excess storm water were identified using water pinch and will be suitable for implementation. The mill has mwever decided on alternative sinks for the storm water based on considerations such as process inter-dependency, risks associated with contamination and general management philosophy for the different systems in the mill. These considerations could have been included into the pinch solver, but were not because it was of interest what the second best option would be. • The pinch investigation proved useful to confirm certain understandings of the mill. The investigation confirmed the difficulty of improving the water systems of the mill due to the fact that Ngodwana is already a highly closed and integrated mill. Numerous smaller process changes have been identified by the pinch solver and could be investigated further for smaller process improvements. • It i; recommended that pinch technology be applied again when the mill plans to make major process changes or expansions. It is also recommended to use water pinch on a more frequent basis in smaller sections of the mill or for other evaluations in the mill. As a group Sappi could benefit from the use of water pinch, especially in situations where the water network of the mill is not already water efficient. • The recommendations and conclusions in this report have not been subjected to technical and economical feasibility studies. Extensive further studies must be conducted before implementation of any of the results. Further studies must include impacts from process dynamics, long term effects, impacts from other contaminants that have not been simulated, etc. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.
13

Critiquing cooperation : the dynamic effects of transboundary water regimes

Kistin, Elizabeth James January 2011 (has links)
The purpose of this study is to develop a deeper understanding of the formation and performance of the international water management institutions operating in the Orange-Senqu basin shared between Lesotho, South Africa, Botswana, and Namibia. The research examines the influence of interstate interaction on adaptive capacity and the allocation of water and related benefits within the Orange-Senqu basin and provides explanations for how and why particular cooperative arrangements emerged and produce differential effects. By applying a structure-agent approach to regime analysis, this study draws attention to four key factors underpinning the formation and performance of the Orange-Senqu water governance regime: power asymmetry, problem structure (i.e., the combination of interest asymmetry and uncertainty), expert networks, and political context. The study demonstrates that each of these four factors provides important and complementary insight into the process of interaction of and the positive and negative effects produced by international water management institutions in the basin and opportunities for generating change. Among these factors, the study argues, power asymmetry and problem structure are critical for understanding transboundary water governance dynamics and identifying strategies for challenging the status quo.
14

Knowledge Sharing Between Competing Suppliers in the Customer's Supply Chain Network

Ho, Hillbun, Ho, Hillbun January 2008 (has links)
Drawing on the marketing, strategic management, and supply management literature, this dissertation develops and empirically tests a theoretical model that delineates knowledge sharing and collaboration between competing suppliers in serving a buying organization. Data were collected through the means of a conjoint-decision study and a survey of suppliers in the optics and the automotive industries. One hundred and forty-six executive MBA students participated in the conjoint-decision study, and one hundred and ten companies participated in the survey. Statistical analysis results from both studies show strong empirical support to the theoretical model. This dissertation advances our understanding of the relative impacts of different factors in promoting or constraining knowledge sharing between competing suppliers when they collaborate with each other to create superior value for the customer. This dissertation demonstrates that a focal supplier's transfer of knowledge to its counterpart hinges not solely on the characteristics of the collaboration. More importantly, knowledge sharing between two competing suppliers is related to different facets of the customer's relationship with the focal supplier. In conclusion, this dissertation provides substantial insights into the role and influences of the customer on competing suppliers' knowledge sharing and collaboration, as well as the value of knowledge sharing to the strategic outcomes of the inter-supplier collaboration.
15

Superstructure optimisation of a water minimisation network with a embedded multicontaminant electrodialysis model

Nezungai, Chiedza Demetria Maputsa January 2016 (has links)
A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / The water-energy nexus considers the relationship between water and energy resources. Increases in environmental degradation and social pressures in recent years have necessitated the development of manufacturing processes that are conservative with respect to both these resources, while maintaining financial viability. This can be achieved by process integration (PI); a holistic approach to design which emphasises the unity of processes. Within the realm of PI, water network synthesis (WNS) explores avenues for reuse, recycle and regeneration of effluent in order to minimise freshwater consumption and wastewater production. When regeneration is required, membrane-based treatment processes may be employed. These processes are energy intensive and result in a trade-off between water and energy minimisation, thus creating an avenue for optimisation. Previous work in WNS employed a black box approach to represent regenerators in water minimisation problems. However, this misrepresents the cost of regeneration and underestimates the energy requirements of a system. The aim of the research presented in this dissertation is to develop an integrated water regeneration network synthesis model to simultaneously minimise water and energy in a water network. A novel MINLP model for the design of an electrodialysis (ED) unit that is capable of treating a binary mixture of simple salts was developed from first principles. This ED model was embedded into a water network superstructure optimisation model, where the objective was to minimise freshwater and energy consumption, wastewater productions, and associated costs. The model was applied to a pulp and paper case study, considering several scenarios. Global optimisation of the integrated water network and ED design model, with variable contaminant removal ratios, was found to yield the best results. A total of 38% savings in freshwater, 68% reduction in wastewater production and 55% overall cost reduction were observed when compared with the original design. This model also led to a 80% reduction in regeneration (energy) cost. / GS2016
16

Hydrochemical and environmental isotope based investigation of the Masama Ntane Sandstone Aquifer, Botswana

Mofokeng, Thelma January 2017 (has links)
A research report submitted to the Faculty of Science school of Geosciences in partial fulfillment of the requirements for the degree of Masters of Science in Hydrogeology. Johannesburg, June 2017. / The Masama Sandstone Aquifer is located in a semi-arid region of south-eastern Botswana where there are no perennial rivers. Groundwater is the main source of water supply for the communities. Historically many water drilling programs have been carried out in this area and the hydrogeological system has been conceptualized. An integrated approach coupling environmental isotopes, radioisotopes and multivariate statistical analysis of the hydrochemical variables was employed to study the origin, age, recharge conditions, rock-water interaction and the hydrological link between the aquifer and geological structures. The major ions in this area are Na+, Ca2+, Mg2+ and HCO-3. Groundwater in the Masama area fall in the transition from a Na-HCO-3 –type through Ca-Na-HCO-3 to Ca-Mg-HCO-3 -type waters from the western to the eastern part of the area. The water types are as a result of cation exchange, carbonate dissolution and rock-weathering processes. The δ18O and δ2H values vary spatially depending on the source of moisture, rainfall season, geology, topography and groundwater circulation depth. Deep circulating groundwaters are isotopically depleted whilst shallow circulating groundwaters are isotopically enriched with respect to winter rain. Low tritium values < 0.8TU and 14C values < 80pmc testifies for recharge. Recent rainfall amount in the area is not sufficient enough to make a profound replenishment in the aquifer. Tritium, 14C and Chloride Mass Balance helped in identifying recharge location and hydrologic connections between structures and the sandstone aquifer elucidating that recharge zones are in the NE and NW of the study area. High recharge rates occur in the north-eastern part and the Makhujwane fault act as a conduit for groundwater recharge. This study provides a better understanding of the aquifer and the information contained herein can be incorporated into future works for sustainable use of the groundwater resource. / XL2017
17

Infra - structuring architecture: rethinking the ideas of water management within an urban Johannesburg context

Vincer, Lionel Ross 29 April 2015 (has links)
This document is submitted in partial fulfilment for the degree: Master of Architecture [Professional] at the University of the Witwatersrand, Johannesburg, South Africa, in the year 2014. / No matter the reasons for the birth of a city, water sits at the very heart ensuring a healthy working population. Johannesburg is one of the only cities in the world that has no major water source of its own and as a result has its water pumped uphill from the Vaal Dam into the city. At the same time the city faces a crisis that is based on both the supply and demand for water. In South Africa, an already water stressed country, it is predicted that precipitation will reduce over the next century, reducing runoff and the supply of fresh water together with demand eventually over taking supply. Through rethinking how the inner city of Johannesburg deals with the saving, purifying and redistribution of its available surface water, the idea of water infrastructure can become something more than a subconscious operation controlled from a far off location and pumped unsustainably back into the city, and more like a series of upgraded machines dispersed about the city within localized contexts, supplementing the existing vital operations on a very obvious and conscious level in order to protect its populations by better protecting it’s most important resource of all. Located within the Maboneng Precinct and more specifically located over a channel of water that becomes the Braamfontein Spruit, this thesis aims at designing a building that will incorporate a water treatment facility together with research laboratories to purify grey water to a standard that is usable for most needs including drinking. Water however does not exist by itself when placed within the context of any environment that has an established infrastructural system. It exists together with the many various machines and pipes hidden from our everyday lives; they are the subconscious networks of the city’s mind, constantly working in the back(under)ground to maintain a reliable flow and quality while the populations go about their conscious, daily functions. The aim is twofold; firstly to show how developing technologies can be experimented on a smaller neighbour-hood scale in order to encourage the development of new thinking and secondly, by developing a Water treatment facility and laboratory coupled with daily social functions as well as offices sited in an urban environment, I hope to show that infrastructural projects that are usually located on the outskirts of cities, away from every day activity, can enhance the civic quality of an urban space. With every system becoming more reliant on technology, water needs to be seen not only as an entity that exists within the natural cycles of the planet, but one that also exists very much within the mechanized systems of the city’s infrastructure, with its availability relying heavily on those systems that manage it as well as the daily social functions that hinge off of it.
18

Um estudo sobre a gestão da terceirização de serviços de tecnologia da informação baseados em modelos de governança / A study on the management of outsourcing services information technology based models of governance

Cristofoli, Fulvio 30 August 2011 (has links)
O objetivo deste trabalho é o de avaliar a gestão da terceirização de serviços de tecnologia da informação (TI) baseados nas práticas de governança de TI (GTI) por meio de revisão bibliográfica e pesquisa quantitativa em organizações brasileiras. Diversas organizações enfrentam dificuldades na gestão dos serviços terceirizados e por essa razão adotam práticas recomendadas por diversos modelos de GTI. O estudo sobre a natureza da relação entre as práticas recomendadas de gestão de TI e seus resultados partiu da análise de 37 modelos de governança, sendo 15 específicos de GTI, dos quais três modelos foram escolhidos – CObIT vs.4.1, eSCM-CL vs.1.1 e ITIL vs.3 – por representarem quase que a totalidade de processos e ações práticas de todos os outros modelos relacionados à GTI. O instrumento foi aplicado junto a 299 gestores de TI de empresas de grande e médio porte dos setores industrial, comercial e de serviços da Região Metropolitana de São Paulo, sendo realizadas análise fatorial exploratória e análise confirmatória por meio de modelagem de equações estruturais estimados por PLS (Partial Least Square). O instrumento final contém 43 itens que ficaram distribuídos em sete fatores, a saber: estratégias de serviços, operações de serviços, monitoramentos de serviços, desenvolvimento do fornecedor, trabalho tecnológico, satisfação e melhoria nos processos de negócio. Esses fatores agrupam-se em duas dimensões – práticas recomendadas e resultados esperados. A pesquisa evidencia que grande parte das organizações utiliza modelos de GTI, sendo as de grande porte sua maior parte e com predominância do modelo ITIL. Podê-se observar ainda, que os melhores resultados obtidos pelas organizações, estão associados à adoção de contratos formais detalhados com uso de service level agreement, aumentando seu foco na área de atuação em função da terceirização de serviços de TI. A expectativa era a de que a adoção de práticas recomendadas de modelos de GTI contribuísse significativamente no resultado da terceirização de serviços de TI, entretanto, isto não ficou caracterizado. A complexidade que envolve a adoção de práticas recomendadas e seus resultados leva-nos a refletir e a apontar outros aspectos que podem estar relacionados a fim de se obter resultados mais significativos da gestão da terceirização de serviços de TI. / The objective of this research is evaluate the management of the outsourcing of information technology (IT) practices based on IT governance (GTI) through a review and quantitative research in Brazilian organizations. Several organizations are facing difficulties in managing outsourced services and therefore adopting practices recommended derived from the various models of GTI. The study on the nature of the relationship between best practices for IT management and its results came from analysis of 37 models of governance, 15 GTI-specific, including three models were chosen - COBIT vs.4.1, eSCM CL-vs. 1.1 and ITIL vs.3 - because they represent almost the entire process and practicalities of all other models related to the GTI. The instrument was applied to 299 IT managers at large and medium-sized companies in the industrial, commercial and service sectors within São Paulo Metropolitan Region and was conducted exploratory factor analysis and confirmatory analysis using structural equation modeling estimated by PLS (Partial Least Square). The final instrument contained 43 items that were distributed in seven factors, namely: service strategies, service operations, monitoring of services, supplier development, technological work, satisfaction and business processes improvement. These factors were grouped into two dimensions - best practices and results. The research shows that most organizations use models of GTI, and the large and mostly with a predominance of ITIL. It can also be observed, is that the best results obtained by the organizations, are associated with adoption of formal contracts with detailed use of service level agreement, increasing its focus on the scope depending on the outsourcing of IT services. The expectation was that the adoption of best practices models GTI contributed significantly in the outcome of outsourcing of IT services, however, this has not been characterized. The complexity surrounding the adoption of best practices and their results leads us to reflect and point to other aspects that may be related to be the most significant results of the management of outsourcing IT services.
19

Hidden Waters: Groundwater Histories of Iran and the Mediterranean

Schade, Abigail E. January 2011 (has links)
This dissertation in environmental history is concerned with human landscapes of groundwater extraction. Using temporal and spatial comparison, it examines the role of groundwater tunnel-wells and human understandings of groundwater availability in the Western Desert of Egypt; the Balearic Islands of Spain; and Iran. In an Epilogue and final chapter, it examines conceptions of 20th-century expertise for environmental knowledge and economic development.
20

Extended food supply chain traceability with multiple automatic identification and data collection technologies.

January 2008 (has links)
Hu, Yong. / Thesis submitted in: October 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 127-129). / Abstracts in English and Chinese. / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1. --- Background and Motivation --- p.1 / Chapter 1.2. --- Objectives of the Thesis --- p.3 / Chapter 1.3. --- Scope of the Thesis --- p.6 / Chapter 1.4. --- Structure of the Thesis --- p.6 / Chapter Chapter 2. --- Review of Related Technologies --- p.8 / Chapter 2.1. --- Scope and Requirements of the Supply Chain Traceability --- p.9 / Chapter 2.2. --- Automatic Identification and Data Collection Technologies --- p.14 / Chapter 2.2.1. --- Introduction to the AIDC Technologies --- p.14 / Chapter 2.2.1.1. --- The Barcode --- p.14 / Chapter 2.2.1.2. --- The Radio Frequency Identification (RFID) --- p.17 / Chapter 2.2.1.3. --- The Sensors for Food --- p.19 / Chapter 2.2.1.4. --- The Global Positioning System (GPS) --- p.23 / Chapter 2.2.2. --- Frequencies of the RFID Systems --- p.25 / Chapter 2.2.3. --- Encoding Mechanisms for the RFID Tags and Barcode Labels --- p.30 / Chapter 2.3. --- Standards and Specifications of the EPCglobal --- p.34 / Chapter 2.3.1. --- The EPCglobal Architecture Framework --- p.34 / Chapter 2.3.2. --- The EPCglobal EPCIS Specification --- p.39 / Chapter 2.3.3. --- The EPCglobal Tag Data Standards --- p.42 / Chapter 2.4. --- RFID Applications in Food Supply Chain Management --- p.43 / Chapter 2.5. --- Anti-counterfeit Technologies and Solutions --- p.45 / Chapter 2.6. --- Data Compression Algorithms --- p.47 / Chapter 2.7. --- Shelf Life Prediction Models --- p.49 / Chapter Chapter 3. --- Architecture and Scope of the Application System --- p.54 / Chapter 3.1. --- Application System Architecture --- p.54 / Chapter 3.2. --- Application System Scope --- p.55 / Chapter Chapter 4. --- The Tracking and Tracing Management Module --- p.60 / Chapter 4.1. --- Overview --- p.60 / Chapter 4.2. --- AIDC Technologies Adopted for the Traceable Items --- p.62 / Chapter 4.3. --- Mechanism to Achieve the Nested Visibility --- p.70 / Chapter 4.4. --- Information Integration in the EPCIS --- p.75 / Chapter 4.5. --- Anti-counterfeit Mechanism --- p.82 / Chapter Chapter 5. --- The Storage and Transportation Monitoring Module --- p.90 / Chapter 5.1. --- Overview --- p.90 / Chapter 5.2. --- Compression of the Sensor Data --- p.93 / Chapter 5.3. --- Management of the Sensor Data --- p.95 / Chapter 5.4. --- Responsive Warning Mechanism --- p.102 / Chapter Chapter 6. --- The Sensor Networks Enabled Assessment Module --- p.108 / Chapter 6.1. --- Overview --- p.108 / Chapter 6.2. --- Management of the Sensor Network Data --- p.110 / Chapter 6.3. --- Active Warning Mechanism --- p.114 / Chapter Chapter 7. --- Conclusions --- p.122 / Chapter 7.1. --- Contributions --- p.122 / Chapter 7.2. --- Future Work --- p.124

Page generated in 0.0971 seconds