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The economic evaluation of bus and minibus taxi terminals and transfer facilitiesPienaar, Wessel Johannes 12 1900 (has links)
Thesis (PhD (Civil Engineering))--University of Stellenbosch, 1998. / 147 leaves single sided printed, preliminary pages i-v and numbered pages 1-1 to 8-8. Includes bibliography,list of figures and tables. Digitized using a Hp Scanjet 8250 Scanner to pdf format (OCR). / ENGLISH ABSTRACT: The dissertation describes the functions of bus and minibus taxi terminals and transfer facilities. Planning, design and evaluation guidelines are proposed. These proposals are aimed at the following aspects: the geometric features and functional layout of facilities in order to enhance the effective usage thereof by passengers, as well as the smooth flow of vehicles; the location of facilities and traffic control arrangements, which take cognisance of effective traffic flow as well as acceptable walking distance by commuters; and an evaluation methodology which addresses allocative efficiency from an economic viewpoint, supplemented by analysis guidelines which consider distributive efficiency from a viewpoint of equitable distribution of welfare. It is explained how benefits for travellers, the transit operator and the subsidizing authority, and the opportunity costs of supplying the facility can be determined. A model is proposed whereby the non-monetary component of generalised travel costs can be estimated. The use of economic evaluation techniques for the selection and prioritisation of projects is detailed. This is supplemented by an example of an economic evaluation of a proposed bus/minibus taxi terminal. Subsequently it is examined how the design and effectiveness of a real world passenger transport terminal could be affected by the use of the guidelines proposed in the dissertation. The dissertation, lastly, deals with welfare distribution and the more equitable community accessibility and mobility which can be brought about by the creation and use of passenger transport terminals and transfer facilities. Also discussed is the accommodation of welfare distribution with an economic evaluation as a means of achieving greater equity or fairness and the ways in which this can be done. / AFRIKANSE OPSOMMING: Die proefskrif beskryf die funksies van bus- en minibustaxivervoereindpunte en oorstapfasiliteite. Beplannings-, ontwerp- en evalueringsriglyne word voorgestel. Die voorsteUe is gerig op die volgende aspekte: (1) Die geometriese en funksionele uitieg om die doeltreffende gebruik deur passasiers en vloei van voertuie te bevorder; (2) fasiliteitplasing en verkeersbeheermaatreels wat vlot voertuigbeweging sowel as aanvaarbare stapafstand in ag neem; en (3) 'n evalueringsmetodologie wat toewysingsdoeltreffendheid vanuit 'n ekonomiese oogpunt en verdelingsdoeltreffendheid vanuit 'n billike welvaartsverdelingsoogpunt in ag neem. Dit word verduidelik hoe voordele vir reisigers, die transit-operateur en die subsidierende owerheid, en die geleentheidskoste van fasiliteitsvoorsiening bepaal kan word. 'n Model word voorgestel waarvolgens die nie-monetere gedeelte van veralgemeende reiskoste beraam kan word. Die gebruik van ekonomiese evalueringstegnieke vir die keuse en prioritisering van projekte word verskaf. Dit word aangevul met 'n voorbeeld van 'n ekonomiese evaluering van 'n voorgestelde bus/minibustaxi-eindpunt. Vervolgens word dit ondersoek hoe die ontwerp en doeltreffendheid van 'n werklike passasiervervoereindpunt deur die gebruik van die voorgestelde riglyne beinvloed kan word. Ten slotte word welvaartverdeling en die groter toeganklikheid en beweeglikheid behandel wat binne 'n gemeenskap geskep kan word deur die voorsiening en gebruik van passasiersvervoereindpunte en oorstapfasiliteite. Dit word bespreek hoe 'n ekonomiese evaluering aangepas kan word as 'n maatreel om billikheid te bevorder.
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Mix design considerations for cold and half-warm bituminous mixes with emphasis of foamed bitumenJenkins, Kim Jonathan 12 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The use of foamed bitumen and bitumen emulsion as binders for use in road
rehabilitation is gaining favour globally. High-level road facilities through to unpaved
roads requiring attention are being treated with these binders due to environmental,
economic and practical benefits in the use of cold bituminous mixes. In addition,
static and mobile plant with the capability of performing stabilisation using bitumenemulsion
and foamed bitumen has become commercially available and widely
utilised, as a result of development in recycling technology and lapse in patent rights
on foam nozzles.
An understanding of the behaviour and failure mechanisms of these cold mixes, as
well as sound guidelines for the mix design procedures of cold mixes, especially
foamed bitumen, and design guidelines for pavements structures incorporating these
materials, are lacking however. Mix designs are carried out primarily on the basis of
experience and pavement designs are empirically based.
The main objective of this dissertation is to address the need for a fundamental
understanding of foamed bitumen and foamed bitumen mixes, and in so doing to
develop techniques for adjudicating mixes, optimising their composition and
rationalising their design both as mixes and as layers in road pavements. At the
same time the exploration of new applications for foamed bitumen and the
possibilities for progressive related technology, is a priority.
To commence, this study includes an appraisal of most of the literature available on
foamed bitumen. This is followed by a fundamental investigation of the colloidal mass
of foam that is produced when small quantities of cold water are added to hot
bitumen. Factors influencing the quality of the foam are identified and a Foam Index
is developed for characterisation and optimisation of the foam.
The spatial composition of a cold foamed bitumen mix, including Interaction of the
foam with moist mineral aggregate, is also addressed in this dissertation. In
particular, the stiffening of the filler mastic using foamed bitumen as binder is
analysed. Techniques of optimising the sand type and content in the mix are also
developed and guidelines for desired aggregate structures for foam treatment are
established.
The temperature of the mineral aggregate has been shown to have a profound
influence on the behaviour and performance of a foamed bitumen mix. This has been
selected as a focal area of further investigation and the research has lead to the
development of a new process called "The half-warm foamed bitumen treatment
process" that can produce mixes with almost the quality of hot mix asphalt with up to
40% less energy consumption.
Other processes developed in this research include the use of cold mix asphaltic
blocks for construction of road pavements in developing areas. This technology
enhances the use of a high labour component in road construction in an
economically competitive manner. The dissertation provides details for mix design
and construction of the cold mix blocks. Finally, the study includes models for the performance prediction of foamed bitumen
mixes. In particular, foamed mixes that exhibit stress-dependent behaviour have
been investigated and models established on the basis of triaxial testing and
accelerated pavement testing for the prediction of permanent deformation of such
layers under repeated loading.
Practical applications of the research findings are summarised in Appendix F. This
includes:
• methods for optimisation of the foamed bitumen properties,
• guidelines for the selection of the ideal aggregate structure for cold foamed
mixes,
• procedures for carrying out cold mix design in the laboratory (including mixing,
compaction and curing),
• procedures for manufacturing half-warm foamed mixes in the laboratory,
• methods for manufacturing cold mix blocks, and
• pavement design methods for road structures incorporating foamed mix layers.
Appendix G outlines statistical techniques that are relevant to the design of
experiments in pavement engineering including examples of applications of these
procedures. The techniques are applied selectively in the relevant chapters of the
dissertation. / AFRIKAANSE OPSOMMING: Die gebruik van skuim bitumen en bitumen emulsie as bindmidel in pad rehabilitasie
begin groter voorkeur wêreldwyd geniet. Van hoë vlak padfasiliteite tot ongeplaveide
paaie wat aandag benodig, word met hierdie binders behandel vanweë die
omgewings-, ekonomiese en praktiese voordele wat hierdie koue bitumen mengsels
inhou. Voorts is statiese en mobiele masjinerie wat die vermoë het om stabilisasie in
die gebruik van bitumenemulsie en skuimbitumen te bewerkstellig, in die handel
verkrygbaar. Dit word algemeen gebruik as 'n uitvloeisel van ontwikkelings in
herwinningstegnologie en die verslapping van patenteregte op skuim sproeikoppe.
'n Leemte bestaan in die begrip van die gedrags- en swigtingsmeganismes van
hierdie koue mengsels, asook goeie riglyne vir die mengselontwerp van koue
mengsels en in besonder skuimbitumen, en ontwerpriglyne vir plaveisel strukture
waar hierdie materiaal geinkorporeer is. Mengselontwerpe word hoofsaaklik
uitgevoer op grond van ondervinding, terwyl plaveiselontwerpe empiries gebaseer is.
Die hoofdoel van die verhandeling is om die behoefte vir 'n fundamentele begrip van
skuim bitumen en skuimbitumen mengsels aan te spreek, en daardeur tegnieke te
ontwikkel vir die be-oordeling van mengsels, optimsering van hul samestelling en
rasionalisering van hulontwerp vir beide mengsels en plaveisellae. Terselfdertyd is
die ondersoek na nuwe toepassings van skuim bitumen en die moontlikhede van
nuwe tegnologie 'n prioriteit.
As beginpunt sluit hierdie studie 'n waardeskatting van die meeste literatuur
beskikbaar op skuim bitumen in. Dit word gevolg deur 'n basiese ondersoek na die
kolloidale massa van skuim wat geproduseer word wanneer klein hoeveelhede koue
water by warm bitumen gevoeg word. Faktore wat die gehalte van die skuim
beinvloed word uitgewys en 'n Skuim Indeks is ontwikkel vir die karakterisering en
optimisering van die skuim.
Die ruimtelike samestelling van 'n koue bitumen mengsel, wat die interaksie van die
skuim met vogtige minerale samevoegings (aggregate) insluit, word ook
aangespreek. Besondere aandag word gewy aan die verharding van die vuiler
mastiekgom wat gebruik word as bitumen binder. Tegnieke om die sandtipe en
inhoud van die mengsel te optimiseer is ontwikkel en riglyne vir die verlangde
samevoegingstrukture (aggregate strukture) vir skuimbehandeling is opgestel.
Daar is bevind dat die temperatuur van die minerale aggregaat 'n duidelike invloed
op die gedrag en verrigting van 'n skuimbitumen mengsel het. Dit is gekies as In
fokuspunt vir verdere studie en die navorsingswerk daarop het gelei tot die
ontwikkeling van In nuwe proses wat "Die half-warm skuim bitumen behandelings
proses" genoem word. Hierdie proses produseer mengsels wat byna gelykstaande is
aan die gehalte van warm gemengde asfalt, maar met tot 40% minder energie
verbruik.
Ander prosesse wat met dié navorsing ontwikkel is, sluit koue gemengde asfaltiese
blokke in, wat gebruik word in die konstruksie van padplaveisel in ontwikkelende
gebiede. Hierdie tegnologie bevorder die ekonomiese gebruik van 'n hoë arbeidskomponent in padkonstruksie. Die studie stel besonderhede vir die
mengselontwerp en konstruksie vir koue gemengde blokke voor.
Laastens sluit die studie modelle in vir die werkverrigtingsvoorspelling van
skuimbitumen mengsels. Op basis van drie-assige proewe in die laboratorium en
versnelde belasting van paaie is modelle ontwikkel vir skuim bitumen mengsels wat
spanningsafhanklike gedrag vertoon (die sogenaamde "granulêre" groep) om die
permanente deformasie in die lae as gevolg van herhaalde verkeersbelasting te
voorspel.
'n Opsomming van al die praktiese toepassings van die ontwikkelings van die
navorsing word in Appendix F verskaf. Dit sluit in:
• optimesering van die eienskappe van skuimbitumen,
• riglyne vir gewenste samestelling van aggregaat in skuimbitumen mengsels,
• ontwerp metodes vir koue skuimbitumen mengsels in die laboratorium (meng,
verdigting en curing),
• produksie metodes vir half-warme mensels in die laboratorium,
• produksie metodes vir blokke wat met koue mengsels gemaak word, en
• plaveiselontwerp metodes van strukture wat skuimbitumen lae inkorporeer.
Appendix G gee 'n oorsig van statistiese tegnieke wat relevant is vir die ontwerp van
eksperimente, insluitend voorbeelde van toepassings van die prosedures in
plaveiselingenieurswese. Die tegnieke word selektief toegepas in die relevante
hoofstukke van die verhandeling.
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A computerised decision support system for the implementation of strategic logistics management optimisation principles in the planning and operation of integrated urban public transportDuff-Riddell, W. R. (Wayne Russell) 12 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Public and private transport system planning and operation have tended to be fragmented
functions. In particular, public transport is often planned and operated independently of the
"private" transport system. South African government policy now requires that comprehensive,
strategic transport plans be prepared by metropolitan transport authorities. These plans are
expected to conform to national strategic objectives as well as including local current and longterm
objectives. This planning is required in the environment of a multi-modal, multi-operator,
public-private partnership scenario that is new for most of the role players. The lack of
experience is accompanied by a lack of any existing model for dealing with this scenario. This
dissertation describes such a model. The model is based on the principles of strategic logistics
management commonly employed in commerce and industry, including service-oriented
industries. The modelling process is thus based on achieving a combination of customer service
and long-term objectives.
The model comprises a number of separate components and steps:
• A transport network model (Emme/2).
~ A multi-class, generalised-cost assignment of private and public transport demand onto a
network, modified to be modeless to the public transport users, is performed. This
assignment allows for the imposition of generalised-cost reflecting urban-planning
objectives in addition to more conventional costs such as travel cost. In this assignment,
the interaction of public and private transport is accounted for and results in an associated
modal choice.
~ A series of single-class generalised-cost assignments is then used to "focus" public
transport demand to create corridors of demand adequate to justify public transport
routes. This process can be enhanced to develop a design promoting switching from
private to public transport. It also allows for multi-period route design.
~ The results of this modelling process are output to a text file and then subject to the
processes described below. The results of these processes are then input into the network
model where a standard transit assignment is performed and used to modify the proposed
lines and update the network design data with respect to boardings and alightings at
nodes. This information is used to design fixed infrastructure. • A Microsoft Access database and route extraction program.
);> The network model data is drawn into the database where it is subject to a route
extraction program that converts the assignment results from the network model into a set
of mode specific potential public transport route definitions. These route definitions are
based on paths of maximum demand. The extraction process is controlled by parameters
specified by the planner, such as minimum route lengths and the demand level for various
categories of service.
);> After route extraction, vehicle allocation, and transit assignment, the database provides
details of the boardings and alightings and number and details of transit lines using each
node and link in the network. This data is used to design fixed infrastructure.
• A Microsoft Excel spreadsheet vehicle operating cost model.
);> For each vehicle type, the operating cost given the anticipated vehicle mileage and
operating speed is determined. This is used to guide the choice of vehicles for different
routes.
• A Lingo goal-programming model.
);> The potential routes and the available or potential fleet are subjected to a goalprogramme
in which the optimum choice of vehicle allocation is determined. The
allocation parameters can be controlled by the planner. These parameters may include
costs, energy, fuel consumption, and vehicle and route limitations amongst others. Multiperiod
design is included in the modelling process so that the optimum design may be for
the operating period, daily, or weekly cycle.
The modelling process provides two main outputs:
• A set of fully described and costed transit lines ill terms of both routing and vehicle
allocation. These transit line definitions can be output to the level of driver instructions if
necessary.
• Details of the type and location of infrastructure to be provided on the network. / AFRIKAANSE OPSOMMING: Openbare en private vervoerstelsel-beplanning en -bedryf IS geneig om gefragmenteerde
funksies te wees. Dit is veral waarneembaar in die openbare vervoerstelsels waarvan die
beplanning en bedryf onafhanklik van die "private" vervoerstelsels plaasvind. Die beleid van die
Suid-Afrikaanse regering vereis dat omvattende strategiese vervoerplanne deur die
metropolitaanse vervoer owerhede voorberei word. Daar word van hierdie planne verwag om
aan die nasionale strategiese doelwitte, asook die plaaslike bestaande en langtermyn doelwitte te
voldoen. Hierdie beplanning word vereis deur 'n omgewing wat nuut is vir die meeste rolspelers
en bestaan uit multi-modale, multi-operateur en openbare-private vennootskap scenario's. Die
tekort aan ondervinding gaan gepaard met 'n tekort aan 'n bestaande model wat gebruik kan
word om hierdie scenario's te hanteer. So 'n model word deur hierdie verhandeling beskryf.
Die model is gebasseer op die beginsels van strategiese logistieke bestuur wat algemeen gebruik
word in die handel en industrie, insluitende die diens-georïenteerde industrieë. Die
modelleringsproses wil dus 'n kombinasie van diens aan kliënte en langtermyn doelwitte bereik.
Die model bestaan uit onderskeie komponente en stappe:
• 'n Vervoernetwerkmodel (Emmel2)
}i;> 'n Multi-klas, veralgemeende-koste toedeling van private en openbare vervoeraanvraag
op 'n netwerk, aangepas om modusloos te wees vir die openbare vervoergebruiker, word
uitgevoer. Hierdie toedeling laat nie net die heffing van meer konvensionele kostes, soos
reiskoste toe nie, maar ook veralgemeende kostes wat staatsbeplarmingsdoelwitte
reflekteer. In hierdie opdrag word die interaksie van openbare- en private vervoer
ondersoek waarvan die uiteinde 'n geassosieerde modale keuse is.
}i;> 'n Reeks enkelklas veralgemeende koste toedelings word dan gebruik om op openbare
vervoeraanvraag te fokus en daardeur korridors van aanvraag, wat gepas is om openbare
vervoerroetes te regverdig, te skep. Hierdie proses kan verfyn word om 'n plan te
ontwikkel wat die verskuiwing van private vervoer na openbare vervoer sal bevorder.
Dit laat ook die ontwerp van multi-periode roetes toe.
}i;> Die resultate van hierdie modelleringsproses word uitgevoer na 'n tekslêer en dan aan die
prosesse, wat hier onder beskryf word, onderwerp. Die resultate van hierdie prosesse
word dan ingevoer in die netwerkmodel waar 'n standaard publieke vervoertoedeling
uitgevoer word. Dit word dan gebruik om die voorgestelde roetes te wysig en die netwerk data, met betrekking tot die aantal persone wat op en af klim by nodes, op te dateer.
Hierdie inligting word gebruik vir die ontwerp van infrastrukture.
• 'n Microsoft Access databasis en roete-ontrekkingsprogram
);> Die netwerkmodel data word in die databasis ingetrek waar dit aan 'n roeteontrekkingsprogram
onderwerp word. Hierdie program skakel die toedelingsresultate
van die netwerkmodel om na 'n stel potensiële modus spesifieke openbare vervoerroete
definisies. Hierdie roete definisies word gebasseer op paaie van maksimum aanvraag.
Die ontrekkingsproses word deur parameters, soos minimum lengte van roetes en die
vlak van aanvraag van verskeie kategorieë van diens, wat deur die beplanner
gespesifiseer word, gekontroleer.
);> Na die ontrekking van roetes, voertuigtoekenning en vervoertoedeling, voorsien die
databasis besonderhede van die aantal persone wat op en af klim asook die aantal en
details van vervoerroete wat elke node en skakel in die netwerk gebruik. Hierdie data
word gebruik om infrastrukture te ontwerp.
• 'n Microsoft Excel sigblad voertuig bedryfskoste model
)i> Vir elke tipe voertuig word die bedryfskoste, volgens die verwagte afstand en spoed
van die spesifieke voertuig, bepaal. Die resultate word gebruik om die keuse van
voertuie vir verskillende roetes te bepaal.
• 'n Lingo doelprogrameringsmodel
);> Die potensiële roetes en die beskikbare of potensiële vloot word onderwerp aan 'n
doelprogram waarin die optimum keuse van voertuigtoekenning bepaal word. Die
toekenningsparameters kan deur die beplanner gekontroleer word. Die parameters kan
onder andere kostes, energie, brandstofverbruik en voertuig- en roete beperkings,
insluit. Multi-periode ontwerp is ingesluit in die modelleringsproses sodat die
optimum ontwerp vir die bedryfsperiode, daaglikse of weeklikse siklusse, kan wees.
Die modelleringsproses lewer twee hoofuitkomste:
• 'n Stel volledig beskrywende en koste berekende vervoerroete wat, indien nodig, na die
vlak van bestuurder instruksies, uitgevoer kan word.
• Details van die tipe en plek van infrastruktuur wat benodig word deur die netwerk.
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Longshore sediment transport : applied wave power approach, field data analysis and evaluation of formulaeSchoonees, Jacobus Stefanus 12 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The process of sand being moved parallel to the coast by wave and current action is called longshore
(sediment) transport. Knowledge oflongshore transport is essential for the design of breakwaters at
harbour entrances, for navigation channels and for calculating the amount of dredging they require,
for beach improvement schemes and for the determination of the stability of inlets and estuaries.
Different aspects oflongshore transport have been investigated, namely, (1) analysis offield data, (2)
evaluation oflongshore transport formulae and (3) the development of the wave power approach as
an alternative method to calculate longshore transport.
In the development of a better understanding oflongshore sediment transport, the following has been
done for the first time: (1) a comprehensive data set has been compiled covering almost a full range
of conditions occurring on natural beaches; and (2) virtually all longshore transport formulae have
been evaluated against this extensive data set. A new improved method, the applied wave power
approach, has been developed and extensively calibrated against the same data set. Based on this
evaluation, guidelines are now available for design engineers as to which are the best bulk and
detailed predictors oflongshore sediment transport. These are respectively, the recalibrated Kamphuis
formula and the applied wave power approach.
Another useful first, is the derivation of confidence intervals for a longshore transport formula,
showing what accuracy can be obtained and that accurate predictions are now possible. In addition,
it has now been determined what the minimum required measurement period should be and what the
most cost-effective way is for obtaining the true long-term mean net longshore transport rate at a
particular site. / AFRIKAANSE OPSOMMING: Die proses waarvolgens sand ewewydig aan die kus deur golf- en stroomwerking vervoer word, word
langsstrandse (sediment-) vervoer oflangsvervoer genoem. Kennis van langsvervoer is noodsaaklik
vir die ontwerp van golfbrekers by hawe-ingange, navigasiekanale en vir die berekening van die
hoeveelheid baggerwerk daarvoor benodig, strandverbeteringskemas en vir die bepaling van die
stabiliteit van inlate en getyriviere.
Verskillende aspekte van langsvervoer is ondersoek, naarnlik, (1) die ontleding van velddata, (2) die
beoordeling van langsvervoerformules en (3) die ontwikkeling van die golfdrywingsbenadering as 'n
altematiewe metode om langsvervoer mee te bereken ..
Tydens die ontwikkeling van 'n beter begrip van langsstrandse sedimentvervoer is die volgende vir
die eerste keer gedoen: (1) 'n omvattende datastel is versamel wat bykans aIle toestande wat aan
natuurlike strande voorkom, dek; en (2) feitlik aile langsvervoerformules is teen hierdie uitgebreide
datastel beoordeel. 'n Nuwe verbeterde metode, die aangewende golfdrywingsbenadering, is
ontwikkel en omvattend teen dieselfde datastel geyk. Gebaseer op hierdie beoordeling, is riglyne nou
vir ontwerp-ingenieurs beskikbaar rakende watter totaal- en detail-iangsvervoervoorspellers die beste
is. Dit is onderskeidelik die hergeykte Kamphuisformule en die aangewende golfdrywingsbenadering.
Nog 'n nuttige eerste is die afleiding van betroubaarheidsgrense vir 'n langsvervoerformule, wat wys
watter akkuraatheid nou haalbaar is en dat noukeurige voorspellings nou moontlik is. Verder is dit
nou vasgestel wat die vereiste meettydperk behoort te wees en wat die mees koste-effektiewe manier
is waarop die ware langtermyn-gemiddelde netto langsvervoertempo by 'n spesifieke terrein verkry
kan word.
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A unit stream power model for the prediction of local scourArmitage, Neil Philip 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Local scour is the erosion of a riverbed resulting from the flow of the river around an
obstacle. It is a principal cause of failure of bridges and other hydraulic structures.
Current design practice relies on the use of empirical formulae that are often
extremely inaccurate, or on the use of physical models that are very expensive.
Recent advances in the power of microcomputers have however made numerical
simulation increasingly attractive. One obstacle to numerical simulation though is
that there is no general agreement on the concept of incipient motion, that critical
point at which motion - and hence scour - begins.
In this dissertation, the unit stream power model developed by Rooseboom (1992) is
extended to handle the complex three-dimensional flow conditions that pertain close
to the riverbed in the vicinity of an obstacle. The relationship between unit stream
power (the dissipation function) and the Movability Number (the ratio of the shear
velocity to the terminal settling velocity of the critical sediment particles) is clearly
indicated. Since incipient motion is probabilistic in nature, a relationship was
established between the Movability Number and the intensity of motion with
allowance for bed-slope and relative depth. An extension of this work resulted in a
new bed-load transportation equation that could be used to determine the rate of scour
development. Physical modelling in a laboratory flume aided the selection of suitable
critical conditions for the onset of scour.
The usefulness of the above-mentioned relationships was then demonstrated through
the construction of a simple mathematical model of scour and deposition around a
structure. This model was used in conjunction with commercially available
computational fluid dynamics (CFD) software to predict the scour potential around
typical engineering structures. Physical model data was obtained for four situations,
and the measured scour was compared with that predicted by the numerical model.
There was reasonable agreement between the different models and such differences as
there were could be readily attributed to constraints on the numerical model, in
particular the lack of a free-surface routine and the coarseness of the grid.
This dissertation has opened up a new method for the prediction of local scour that
could be readily extended to include all types of scour. With the advent of
increasingly fast computers, it could become a useful engineering tool that would
assist engineers in the design of safe and cost-effective foundations for hydraulic
structures. / AFRIKAANSE OPSOMMING: Plaaslike uitskuring is die erosie van 'n rivierbed as gevolg van vloei verby 'n
obstruksie. Dit is 'n belangrike oorsaak van die swigting van brfïe en ander
hidrouliese strukture. Bestaande ontwerppraktyk berus op empiriese vergelykings wat
dikwels hoogs onakkuraat is, of op fisiese modelle, wat baie duur is. Numeriese
simulasie het die afgelope tyd 'n al hoe meer aantreklike opsie geword danksy die
snelle toename in die kapasiteit van mikro-rekenaars. 'n Struikelblok met numeriese
simulasies is die gebrek aan konsensus oor die konsep van begin-van-beweging,
daardie kritieke toestand waarby beweging en derhalwe uitskuring begin.
In hierdie proefskrif is die eenheidstroomdrywing model, ontwikkel deur Rooseboom
(1992), uitgebrei om die komplekse drie-dimensionele vloeitoestande, wat teenaan die
rivierbodem verby 'n obstruksie heers,te hanteer. Die verwantskap tussen Eenheid
Stroomdrywing (Dissipasiefunksie) en die Beweeglikheidsgetal (verhouding tussen
sleursnelheid en die ewewigvalsnelheid van die kritieke sedimentpartikels ) is duidelik
uitgewys. Aangesien begin van beweging probabilisties van aard is, is die
verwantskap bepaal tussen die Beweeglikheidsgetal en die Intensiteit van Beweging,
met voorsiening vir bodernhelling en relatiewe diepte. Verdere uitbreiding het gelei
tot 'n nuwe bedvrag vervoervergelyking wat gebruik kan word om die tempo van
uitskuring te bepaal. Kritieke toestande, waarby uitskuring begin, is met fisiese
modelle in die laboratorium gekwantifiseer.
Die bruikbaarheid van bogenoemde verbande is gedemonstreer deur die ontwikkeling
van 'n eenvoudige wiskundige model van uitskuring en afsetting rondom 'n struktuur.
Hierdie model is saam met bestaande kommersiële sagteware vir vloeidinamika
berekenings (CFD) ingespan om uitskuringspotensiaal rondom tipiese
ingenieurstrukture te voorspel. Fisiese modelmetings van uitskuring vanaf vier
uitlegte is vergelyk met die numeries voorspelde waardes. Bevredigende ooreenkoms
is gevind en verskille kon geredelik gewyt word aan beperkings van die numeriese
model, veral die gebrek aan' n vryvlakroetine en die growwe maas.
Die proefskrif stel 'n nuwe metode vir die voorspelling van uitskuring daar wat
geredelik uitgebrei kan word na ander vorms van uitskuring. Met die ontwikkeling
van al vinniger rekenaars kan dit 'n nuttige hulpmiddel vir ingenieurs word om veilige
en koste-doeltreffende fondamente in waterlope te ontwerp.
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Comparative evaluation of the model-centred and the application-centred design approach in civil engineering softwareSinske, A. N. (Alexander Nicholas) 12 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: In this dissertation the traditional model-centred (MC)design approach for
the development of software in the civil engineering field is compared to a
newly developed application-centred (AC)design approach.
In the MC design software models play the central role. A software model
maps part of the world, for example its visualization or analysis onto the
memory space of the computer. Characteristic of the MC design is that the
identifiers of objects are unique and persistent only within the name scope
of a model, and that classes which define the objects are components of the
model.
In the AC design all objects of the engineering task are collected in an application.
The identifiers of the objects are unique and persistent within the name
scope of the application and classes are no longer components of a model,
but components of the software platform. This means that an object can be a
part of several models.
It is investigated whether the demands on the information and communication
in modern civil engineering processes can be satisfied using the MC
design approach. The investigation is based on the evaluation of existing software
for the analysis and design of a sewer reticulation system of realistic
dimensions and complexity. Structural, quantitative, as well as engineering
complexity criteria are used to evaluate the design. For the evaluation of the
quantitative criteria, in addition to the actual Duration of Execution, a User Interaction
Count, the Persistent Data Size, and a Basic Instruction Count based
on a source code complexity analysis, are introduced.
The analysis of the MCdesign shows that the solution of an engineering task
requires several models. The interaction between the models proves to be
complicated and inflexible due to the limitation of object identifier scope: The
engineer is restricted to the concepts of the software developer, who must
provide static bridges between models in the form of data files or software transformers.
The concept of the ACdesign approach is then presented and implemented in
a new software application written in Java. This application is also extended
for the distributed computing scenario. Newbasic classes are defined to manage
the static and dynamic behaviour of objects, and to ensure the consistent
and persistent state of objects in the application. The same structural and
quantitative analyses are performed using the same test data sets as for the
MCapplication.
It is shown that the AC design approach is superior to the MC design approach
with respect to structural, quantitative and engineering complexity
.criteria. With respect to the design structure the limitation of object identifier
scope, and thus the requirement for bridges between models, falls away,
which is in particular of value for the distributed computing scenario. Although
the new object management routines introduce an overhead in the
duration of execution for the AC design compared to a hypothetical MC design
with only one model and no software bridges, the advantages of the design
structure outweigh this potential disadvantage. / AFRIKAANSE OPSOMMING: In hierdie proefskrif word die tradisionele modelgesentreerde (MC)ontwerpbenadering
vir die ontwikkeling van sagteware vir die siviele ingenieursveld
vergelyk met 'n nuut ontwikkelde applikasiegesentreerde (AC) ontwerpbenadering.
In die MContwerp speel sagtewaremodelle 'n sentrale rol. 'n Sagtewaremodel
beeld 'n deel van die wêreld, byvoorbeeld die visualisering of analise op die
geheueruimte van die rekenaar af. Eienskappe van die MContwerp is dat die
identifiseerders van objekte slegs binne die naamruimte van 'n model uniek
en persistent is, en dat klasse wat die objekte definieer komponente van die
model is.
In die AC ontwerp is alle objekte van die ingenieurstaak saamgevat in 'n applikasie.
Die identifisieerders van die objekte is uniek en persistent binne
die naamruimte van die applikasie en klasse is nie meer komponente van die
model nie, maar komponente van die sagtewareplatform. Dit beteken dat 'n
objek deel van 'n aantal modelle kan vorm.
Dit word ondersoek of daar by die MC ontwerpbenadering aan die vereistes
wat by moderne siviele ingenieursprosesse ten opsigte van inligting en kommunikasie
gestel word, voldoen kan word. Die ondersoek is gebaseer op
die evaluering van bestaande sagteware vir die analise en ontwerp van 'n
rioolversamelingstelsel met realistiese dimensies en kompleksiteit. Strukturele,
kwantitatiewe, sowel as ingenieurskompleksiteitskriteria word gebruik
om die ontwerp te evalueer. Vir die evaluering van die kwantitatiewe kriteria
word addisioneel tot die uitvoerduurte 'n gebruikersinteraksie-telling, die persistente
datagrootte, en 'n basiese instruksietelling gebaseer op 'n bronkode
kompleksiteitsanalise , ingevoer.
Die analise van die MC ontwerp toon dat die oplossing van ingenieurstake
'n aantal modelle benodig. Die interaksie tussen die modelle bewys dat dit kompleks en onbuigsaam is, as gevolg van die beperking op objekidentifiseerderruimte:
Die ingenieur is beperk tot die konsepte van die sagteware
ontwikkelaar wat statiese brue tussen modelle in die vorm van lêers of
sagteware transformators moet verskaf.
Die AC ontwerpbenadering word dan voorgestel en geïmplementeer in 'n nuwe
sagteware-applikasie, geskryf in Java. Die applikasie word ook uitgebrei vir
die verdeelde bewerking in die rekenaarnetwerk. Nuwe basisklasse word
gedefinieer om die statiese en dinamiese gedrag van objekte te bestuur, en om
die konsistente en persistente status van objekte in die applikasie te verseker.
Dieselfde strukturele en kwantitatiewe analises word uitgevoer met dieselfde
toetsdatastelle soos vir die MC ontwerp.
Daar word getoon dat die AC ontwerpbenadering die MC ontwerpbenadering
oortref met betrekking tot die strukturele, kwantitatiewe en ingenieurskompleksiteitskriteria.
Met betrekking tot die ontwerpstruktuur val die beperking
van die objek-identfiseerderruimte en dus die vereiste van brue tussen modelle
weg, wat besonder voordelig is vir die verdeelde bewerking in die rekenaarnetwerk.
Alhoewel die nuwe objekbestuurroetines in die AC ontwerp in
vergelyking met 'n hipotetiese MC ontwerp, wat slegs een model en geen sagteware
brue bevat, langer uitvoerduurtes tot gevolg het, is die voordele van die
ontwerpstruktuur groter as die potensiële nadele.
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PAVDAM - probabilistic and volumetric design of asphalt mixturesSmit, Andre de Fortier 12 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The dissertation presents a design procedure for HMA mixes based on probabilistic
and volumetric approaches, hereafter referred to as PAVDAM. Central to PAVDAM
is the use of an analytical model for estimating the voids in the mineral aggregate
(VMA) of asphalt mixes. Validation of the mix design procedure was done through accelerated
pavement testing (APT) with the Model Mobile Load Simulator (MMLS3)
at the National Center for Asphalt Technology (NCAT) test track in Opelika, Alabama.
In addition, the semi-circular bending (SCB) test was evaluated to serve as
an analysis tool to augment the proposed mix design procedure. Non-linear finite element
analyses using a quasi-isotropic material model were done using the CAPA-3D
finite element system developed at the Technical University of Delft in the Netherlands
to better characterise the tensile strength properties of specimens tested with
the SCB.
PAVDAM is partly based on performance related and analytical procedures such
as the Stategic Highway Research Program (SHRP) Superpave and the Belgium Road
Research Centre (BRRC) design method. The mix design system was developed based
on gyratory compaction procedures. In this regard, the criteria relating gyratory
compaction to design traffic as specified in Superpave are used. PAVDAM differs
from other mix design methods in that a probabilistic approach is used to account
for the variabilities associated with mixture components and properties during the
manufacturing stage. It serves as a subset of the volumetric optimisation stage of the
mix design process.
The development of an analytical model to estimate the VMA of an asphalt mix
was the central theme of the dissertation. The analytical model developed is based
on modified Aim and Toufar (MAT) packing models developed under SHRP research
and used in the concrete industry. The MAT packing models are based on the theory underlying the packing of monosized spheres and the combination of successive binary
systems. These models were further refined for use in the asphalt industry. A probabilistic
procedure based on the BRRC PRADO packing model is used to account for
the influence of size ratio of the successive monosized binary systems. The result was
a model that allows an estimation of the VMA of a mix from the gradation of the
mix, the voids in the filler and the porosities of the individual aggregate fractions
making up the mix. Research was undertaken to couple VMA estimates with gyratory
compaction levels. This allowed estimates to be made of the optimum binder
contents of mixes for different design traffic levels.
The VMA of a mix is difficult to estimate accurately since it is difficult to quantify
the factors influencing VMA such as gradation, particle shape, angularity, texture and
rugosity. Furthermore, the influence of binder content and compaction must be taken
into account. The MAT packing model underestimates the VMA of mixes compared
to measured values. For this reason it is necessary to calibrate the model to allow
more accurate estimations. More sophisticated models are required to more accurately
estimate the VMA of mixes. It is recommended that the development of these be
explored further.
Asphaltic materials are inherently heterogeneous and there are a large number of
factors that influence their volumetric properties. Because of this, Monte Carlo simulation
techniques are used in PAVDAM to evaluate the combined effect of the variabilities
of significant material properties. The dissertation expands on the different
variabilities and the effects of variability on mixture volumetrics and mix design verification.
The dissertation outlines the algorithms and procedures used in PAVDAM
to estimate the binder content of a mix. In order to validate the PAVDAM model,
analyses were done to determine the reliability of specific NCAT MMLS3 test section
mixes in terms of densification in the field. A comparison of PAVDAM estimated
and field binder contents allowed a ranking of the reliabilities of the different section
mixes in terms of field densification at the design traffic level. This ranking compared
favourably with that obtained from an analysis of actual densification trends
monitored in the field under full-scale trafficking.
Initial FEM analyses of the SCB using linear elastic isotropic modelling allowed the development of equations to characterise the tensile strength and modulus characteristics
of specimens tested using the SCB. It was emphasized that these equations
do not provide a realistic assessment of the strengths or moduli of asphaltic materials.
The strengths and moduli of these materials are influenced by strain rates within the
materials that cannot be assessed using a simple linear elastic approach. To address
this, an alternative FEM analyses using CAPA-3D was undertaken. An approach was
adopted to account for the influence of tensile and compressive strain rates on modulus.
The analyses made use of a quasi-isotropic material model and it was shown to
better characterise the tensile strengths of HMA materials using the SCB. The analyses
also indicated that the tensile strengths determined using the equations initially
developed based on a linear elastic approach result in strengths that are unrealistically
high. It is recommended that further finite element research be done using non-linear
material modelling to evaluate the very complex stress-strain conditions within an
SCB specimen to better characterise fracture response. It is also recommended that
the fatigue characterisation of HMA be explored based on strength tests using the
SCB.
PAVDAM represents a rational approach to mix design, a shift from experimental
empiricism towards scientific fundamentalism. PAVDAM can be used to define the
spatial composition of asphalt mixes. The influence of mix component variability may
be addressed and reliability assessments of candidate gradations are possible during
volumetric optimisation. Furthermore, changes in the volumetric properties of asphalt
mixes may be investigated. As such, PAVDAM is a mix design management tool and
can only be effective when used as part of a system that closely monitors variability
and systematically refines the underlying packing model. / AFRIKAANSE OPSOMMING: Die verhandeling lewer 'n asfalt mengselontwerp metode gebaseer op statistiese en
volumetriese metodes, genaamd PAVDAM. PAVDAM gebruik 'n analitise model om
'n skatting te maak van die ruimtes in die aggregaat (VMA) van asfalt mengsels.
Stawing van die mengselontwerp metode is gedoen deur vesnelde plaveisel toetse met
die Model Mobiele Las Simuleerder (MMLS3) op die National Center for Asphalt
Technology (NCAT) se toetsbaan in Opelika, Alabama. Die Semi-Circular Bending
(SCB) toets is ook geëvalueer om die voorgestelde ontwerp metode te analiseer. Nielineêre
eindige element analise met gebruik van 'n kwasi-isotropiese materiaal model is
gedoen met die CAPA-3D eindige element (FEM) stelselontwikkel deur die Tegniese
Universitieit van Delft in Nederland om die treksterkte van monsters getoets met die
SCB beter te karakteriseer.
PAVDAM is deels gebaseer op gedragsverwante en analitise prosedures soos die
Strategic Highway Research Program (SHRP) Superpave en die Belgium Road Research
Centre (BRRC) ontwerp metodes. Die mengselontwerp stelsel is ontwikkel
gebaseer op girator verdigtingsmetodes. Die girator verdigtingskriteria soos voorgeskryf
in Superpave is gebruik. PAVDAM verskil van ander mengselontwerp metodes omdat
daar gebruik gemaak word van statistiese metodes om die veranderlikhede geassosieer
met mengsel komponente en ontwerp prosedures gedurende die vervaardigingsfase.
Dit dien as 'n komponent van die volumetriese optimeringsfase van 'n mengsel ontwerp
proses.
Die sentrale tema van die verhandeling was die ontwikkeling van 'n analitisie
model om 'n skatting te maak van die VMA van asfalt mengsels. Die analitise model
wat ontwikkel is is gebaseer op gewysigde Aim and Toufar (MAT) pakkingsmodelle
ontwikkel as deel van SHRP navorsing en wat gebruik word deur die betonindustrie.
Die MAT pakkingsmodelle is gebaseer op die teorie van die pakking van eenvormige groote sfere en die kombinasie van binêre sisteme. Die modelle is verder ontwikkel
vir gebruik in die asfaltindustrie. 'n Statistiese prosedure gebaseer op die BRRC
se PRADO pakkingsmodel is gebruik om die invloed van groote verhouding (size
ratio) van opeenvolgende binêre sisteme in ag te neem. Die gevolg was 'n model
wat gebruik kan word om 'n skatting te maak van die VMA van 'n mengsel vanaf
die mengsel gradering, ruimtes in die vulstof en die porositeit van die individuele
aggregaat fraksies wat die mengsel saamstel. Navorsing is gedoen om die VMA te
koppel aan girator verdigtingsvlakke. Die gevolg is dat skattings gemaak kan word van
die optimum bindstof inhoude van mengsels vir verskillende verkeer ontwerp vlakke.
Dit is moeilik om 'n akkurate skatting van die VMA van mengsels te maak omdat
dit moelik is om faktore wat VMA beïnvloed te kwantifiseer, soos byvoorbeeld
gradering, partikel vorm, hoekigheid en tekstuur. Die invloed van bindstof inhoud
en verdigting moet ook in ag geneem word. Die MAT pakkings modelonderskat die
VMA van mengsels in vergeleke met gemete waardes. Daarom is dit noodsaaklik dat
die model gekalibreer word om meer akkurate skattings van mengsel VMA te maak.
'n Meer gesofistikeerde model is nodig om meer akkuraat die VMA van mengsels te
skat. Dit word voorgestel dat die ontwikkeling van hierdie modelle verder ondersoek
word.
Asfalt materiaale is inherent heterogeen en daar is 'n groot aantal faktore wat die
volumetriese einskappe van die mengsels beïnvloed. Om hierdie rede word gebruik
gemaak van Monte Carlo simulasie in PAVDAM om die gekombineerde effek van veranderlikheid
in ag te neem. Die verhandeling brei verder uit op verskillende veranderlikhede
en die effek van veranderlikheid op die volumetriese einskappe van mengsels
en die stawing van die model. Die algoritme en prosedures wat deur PAVDAM gebruik
word om 'n skatting te maak van die optimum bindstof inhoud van 'n mengsel
word in die verhandeling uiteengesit. Vir stawing van PAVDAM is analises gedoen
om die betroubaarheid van NCAT MMLS3 toets seksies in terme van verdigting in
die veld te bepaal. Vergelykings tussen PAVDAM geskatte en veld bindstof inhoude
het gelei tot 'n rangorde van die betroubaarheid van die verskillende seksie mengsels
in terme van verdigting in die veld onder die ontwerp vervoer. Hierdie rangorde het
goed vergelyk met die wat gekry is van analise van die werklike verdigtingstendense
soos in die veld gemonitor is onder volskaalse verkeer. Voorlopige FEM analise van die 8CB met gebruik van lineêr isotropiese modelering
het gelei tot die ontwikkeling van vergelykings om die treksterke en styfheidseienskappe
van monsters getoets met die 8CB te skat. Dit word beklemtoon dat
hierdie vergelykings nie 'n realistiese skatting van die treksterkte of styfhede van asfalt
materiaale gee nie. Die treksterkte en styfhede van die materiaale word beïnvloed
deur verplasingstempo's binne die materiaale wat nie deur lineêr elastiese benaderings
bepaal kan word nie. Om dit aan te spreek is alternatiewe FEM analise gedoen deur
gebruik te maak van CAPA-3D. 'n Benadering is gevolg om die invloed van trek en
druk verplasingstempo's op styfheid in ag te neem. Die analise het gebruik gemaak
van 'n kwasi-isotropiese materiaal model en dit het 'n beter karakterisering van die
treksterkte van asfalt mengsels tot gevolg gehad. Dit word voorgestel dat verdere
eindige element navorsing gedoen word met gebruik van nie-lineêre materiaal modellering
om die breekgedrag van 8CB monsters beter te kan karakteriseer. Dit word
ook voorgestel dat die vermoeiings eienskappe van asfalt mengsels ondersoek word
gebaseer op treksterketoetse met gebruik van die 8CB.
PAVDAM is 'n rasionele benadering tot mengselontwerp, 'n paradigma skuif weg
van empiriese metodes tot wetenskaplik fundamentele metodes. PAVDAM kan gebruik
word om die ruimtelike samestelling van asfalt mengsels te definieer. Die invloed
van veranderlikheid kan in ag geneem word en betroubaarheidsskattings van kandidaat
mengsels is moontlik gedurende die volumetriese optimiseringsfase. Verder kan
veranderings in die volumetriese eienskappe van mengsels ondersoek word. As sulks
is PAVDAM 'n hulpmiddel vir die bestuur van mengselontwerp en kan net effektief
wees wanneer dit gebruik word as deel van 'n stelsel wat die mengselveranderlikheid
monitor en sistematies die onderliggende pakkings model verbeter.
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Structural analysis in a distributed collaboratoryVan Rooyen, G. C. (Gert Cornelis) 12 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Structural analysis is examined in order to identify its essential information
requirements, its fundamental tasks, and the essential functionalities that applications
which support it should provide. The special characteristics of the information content
of structural analysis and the algorithms that operate on it are looked into and
exploited to devise data structures and utilities that provide proper support of the
analysis task within a local environment, while presenting the opportunity to be
extended to the context of a distributed network-based collaboratory as well. Aspects
regarding the distribution of analysis parameters and methods are analysed and
alternatives are evaluated. The extentions required to adapt the local data structures
and utilities for use in a distributed communication network are developed and
implemented in pilot form. Examples of collaborative analysis are shown, and an
evaluation of the overhead involved in distributed work is performed. / AFRIKAANSE OPSOMMING: 'n Ondersoek van die struktuuranalise-taak word uitgevoer waarin die kerninligtingsbehoeftes
en fundamentele take daarvan, asook die vereisde funksionaliteit
van toepassings wat dit ondersteun bepaal word. Die besondere eienskappe van
struktuuranalise-inligting en die algoritmes wat daarop inwerk word ondersoek en
benut om data strukture en metodes te ontwikkel wat die analise-taak goed
ondersteun in In lokale omgewing, en wat terselfdertyd die moontlikheid bied om
sodanig uitgebrei te word dat dit ook die taak in 'n verspreide
samewerkingsgroepering kan ondersteun. Aspekte van die verspreiding van analiseparameters
en metodes word ondersoek en alternatiewe oplossings word evalueer.
Die uitbreidings wat nodig is om die datastrukture en metodes van die lokale
omgewing aan te pas vir gebruik in verspreide kommunikasienetwerke word
ontwikkel en in loodsvorm toegepas. Voorbeelde van samewerking-gebasseerde
analise word getoon, en die oorhoofse koste verbonde aan analise in 'n verdeelde
omgewing word evalueer.
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Towards the extension of the knowledgebase to further the understanding and modelling of driver behaviourPoolman, Pieter 04 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The problem of how the mind relates to the brain stands as one of the greatest challenges today.
The materialistic worldview and pragmatic approach to social problems are both being transformed
by discoveries of how human experience and culture arise in cerebral activity. Even so, this effort,
spearheaded by neuroscience, has seen the important and contentious issue of driver behaviour
somehow been left behind.
From an extensive literature study, it can be concluded that gross disregard of the neural
underpinnings of such behaviour tied to a behaviouristic approach is endemic to the field.
Numerous qualitative psychological models (each associated with debates about their validity) and
Artificial Intelligence models, which effectively only imitate robots 'impaired' to display some
humanlike characteristics, were come across. Although neural networks are derived from current
knowledge of computation within the brain and deployed in industry, human driver behaviour
modelling is not benefiting from this revolution in humanlike information processing.
To date, very little has been done to determine what makes road users speed, drive while drunk,
overtake, or yield at crossroads. As the central nervous system is the human measuring device in
and of the world and thus key affector of human behaviour, it is ofutrnost importance to invest
resources in 'inoculating' the field of driver behaviour modelling onto a robust basis provided by
neuroscience. Being a human driver incorporates a broad complement of interrelated brain systems
to perform driving tasks (psychological functions) at hand, such as lane keeping, speed choice, risk
perception, and obstacle avoidance. The proper level of analysis of such a psychological function
is the level at which that function is represented in the brain. Providing a theoretical model of
human behaviour, based on biological facts of the brain as a whole, is surely a challenge for
decades to come, but the field of driver behaviour should be part of such an effort.
Collaboration is needed among investigators from the fields of neuroscience, psychology,
mathematics, computer science, and engineering to further driver behaviour modelling. It is
uncommon that professionals from these fields have a thorough understanding of the other fields
involved, but the author, not pretending to be an expert, argues that such a union of fields will be of
significant value not only to transportation, but all behavioural sciences. The wealth of to-date
knowledge amassed in neuroscience lies ready to be tapped by researchers interested in explaining human driver behaviour. To this end, the use of modem brain-imaging techniques will be
invaluable in pinning down the neural correlates of particular driving subtasks, bearing in mind the
extent of structural impacts on the brain of each individual, brought about by a lifetime of
interaction with the environment.
Thus, based on the findings of this literature study, the author proposes that supplementary work be
conducted by a multi-disciplinary team to roll-out an experiment to study the nature of
environmental stimuli as instigators of aggression and road rage, by drawing on knowledge about
brain imaging and (amygdala) activation. / AFRIKAANSE OPSOMMING: Die vraagstuk hoe die verstand [denke] met die brein in verband staan, is een van die grootste
uitdagings tans. Die materialistiese wêreldbeskouing sowel as die pragmatiese benadering van
maatskaplike probleme word verander deur ontdekkings aangaande die wyse waarop menslike
ervaring en kultuur hul in serebrale aktiwiteit voordoen. Desondanks is in hierdie poging, met die
neurowetenskap aan die spits, die belangrike en omstrede kwessie van bestuurdersgedrag om een of
ander rede agterweë gelaat.
Uit 'n uitgebreide literatuurstudie kan afgelei word dat grootskaalse verontagsaming van die neurale
basis van sodanige gedrag gekoppel aan 'n behavioristiese benadering endemies is aan die gebied.
Talle kwalitatiewe sielkundige modelle en kunsmatige intelligensiemodelle is teëgekom, elk
gepaard met debatte oor die geldigheid daarvan. Hoewel neurale netwerkmodelle gebaseer word
op huidige kennis van verwerking binne die brein en ontplooi word in die industrie, trek menslike
bestuurdersgedragmodellering nie voordeel uit hierdie revolusie in neurale inligtingsverwerking nie.
Tot op hede is baie min gedoen om vas te stel waarom padgebruikers jaag, dronkbestuur,
verbysteek of by kruispaaie toegee. Aangesien die sentrale senuweestelsel die menslike
meettoestel in en van die wêreld is en dus die sleutelbeïnvloeder van menslike gedrag is, is dit van
die uiterste belang om middele te investeer in die fundering van die gebied van
bestuurdersgedragmodellering op 'n stewige basis daargestel deur die neurowetenskappe. Om'n
menslike bestuurder te wees behels 'n omvattende komplement van verbandhoudende breinstelsels
om bestuurstake (sielkundige funksies) te verrig, soos spoedkeuse, risikowaarneming en die
vermyding van obstruksies. Die gepaste ontledingsvlak van so 'n sielkundige funksie is die vlak
waarop daardie funksie in die brein verteenwoordig word. Die daarstelling van 'n teoretiese model
van menslike gedrag, gebaseer op biologiese feite van die brein in die geheel, is gewis nog vir
komende dekades 'n uitdaging, maar die gebied van bestuurdersgedrag moet deel uitmaak van so 'n
pogmg.
Samewerking is nodig tussen navorsers uit die neurowetenskappe, sielkunde, wiskunde,
rekenaarwetenskap en ingenieurswese om bestuurdersgedragmodellering te bevorder. Dit is
ongewoon dat vakkundiges uit hierdie velde 'n deeglike begrip het van die ander gebiede wat
betrokke is, maar die outeur, sonder om voor te gee dat hy 'n deskundige is, betoog dat so 'n samesnoering van vakgebiede van betekenisvolle waarde sal wees, nie net vir die vervoerwese nie,
maar ook vir al die gedragwetenskappe. Die omvang van die jongste kennis wat in die
neurowetenskappe vergaar is, lê gereed om deur navorsers benut te word wat belang stel in die
verklaring van menslike bestuurdersgedrag. Met dié doel sal die gebruik van moderne
breinskanderingstegnieke van onskatbare waarde wees om die neurale korrelate van bepaalde
bestuursubtake vas te pen, gedagtig aan die omvang van strukturele impakte op die brein van elke
indiwidu teweeggebring deur 'n leeftyd van interaksie met die omgewing. Daarom, gebaseer op die bevindinge van hierdie literatuurstudie, stel die outeur voor dat
addisionele werk gedoen word deur 'n multi-dissiplinêre span ten einde 'n eksperiment uit te voer,
waarin die aard van stimuli uit die omgewing, wat lei tot padwoede, bestudeer kan word, met
inagneming van die beskikbare kennis oor breinskandering en (amygdala) -aktiveringpatrone.
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Wind climatology of South Africa relevant to the design of the built environmentKruger, Andries Coenrad 03 1900 (has links)
Thesis (PhD (Civil Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: In South Africa, wind constitutes the most critical environmental loading affecting the
design of the built environment. The wind climatic information, which is currently
incorporated in structural design standards, is based on the analysis of records from a
limited number of wind recording stations, mainly located in large cities, and was done
several decades ago. In view of the size and the climatological diversity of South Africa,
this information cannot be deemed to be adequate. Therefore, the incorporation of welldistributed
and updated information on wind climate is essential. The present study
endeavoured to address this issue. A strong wind climatology was developed with the
use of observed climate data, with the most significant result that a mixed strong wind
climate is prevalent in the greater part of South Africa. Statistical approaches to
estimate extreme wind speeds were investigated with applicable wind data, with the
optimum approach guided by the unique climatological environment and the statistical
properties of the utilised data set: For the wind gust analysis the Peak-Over-Threshold
method with the exponential distribution is recommended, while in a mixed strong wind
climate the “mixed climate” approach is preferred. For the analysis of the hourly mean
wind speeds the choice is between the Gumbel distribution and the mixed climate
approach, depending on the strong wind climate. The estimation and incorporation of
environmental correction factors to the measured wind speeds were necessary as the
surroundings of most weather stations did not correspond to the reference Terrain
Category. For some of the weather stations it was impossible to compensate for the
inadequate exposure and surrounding complex topography, so that a reduced number
of weather stations were available for the strong wind analyses. The values estimated
for the design wind speeds, adjusted for the short lengths of data records, as well as
techniques developed to guide the spatial interpolation of the quantiles, were utilised to
develop updated maps of the regional design wind speeds. A comparative study
between the results of this study, and that of the previous study on which the current
loading code in South Africa is based, indicates that the present study should produce
more reliable quantile estimations. / AFRIKAANSE OPSOMMING: Wind vorm die mees kritieke omgewingslading wat die ontwerp van die beboude
omgewing in Suid-Afrika beïnvloed. Die windklimaat-inligting wat tans gebruik word in
die ontwerp spesifikasies is gebaseer op die statistiese analiese van veskeie dekades
gelede op ‘n beperkte aantal windmeting-stasies, hoofsaaklik gesentreer in groot stede.
Indien die grootte sowel as die klimatologiese diversiteit van Suid-Afrika in ag geneem
word kan hierdie inligting nie as voldoende gereken word nie. Die gebruik van heelwat
beter verspreide en opgedateerde inligting oor die windklimaat is daarom noodsaaklik
en die studie poog om hierdie leemte aan te spreek. ‘n Sterk-wind klimatologie van
Suid-Afrika is ontwikkel deur die gebruik van waargenome klimaatdata, met die mees
betekenisvolle bevinding dat ‘n gemengde sterk-wind klimaat in die grootste gedeelte
van Suid-Afrika heers. Statistiese benaderings om ekstreme winde te beraam is
ondersoek met die beskikbare winddata, met die optimale benadering wat sal afhang
van die klimatologiese omgewing van die weerstasie en die statistiese eienskappe van
die betrokke windrekord: Vir die wind-stoot analieses word die “Piek-Oor-Drumpel”
metode met die eksponensïele verdeling aanbeveel, behalwe in ‘n gemengde sterkwind
klimaat waar die “gemengde klimaat” benadering gebruik word. Vir die analiese
van die uurlikse gemiddelde winde is die keuse tussen die Gumbel verdeling en die
gemengde klimaat benadering, afhangende van die sterk-wind klimaat. Die skatting en
toepassing van omgewingskorreksiefaktore vir die windspoed was nodig, aangesien die
omgewings waarin die meeste weerstasies is nie ooreenkom met die verwysings
Terrein Kategorie nie. Vir sommige weerstasies was dit onmoontlik om vir die
onvoldoende blootstelling te vergoed, met die gevolg dat minder stasies beskikbaar was
vir die sterk wind analiese. Die geskatte waardes vir die ontwerp-windsnelhede, asook
tegnieke ontwikkel vir ruimtelike interpolasie, is gebruik vir die ontwikkeling van kaarte
van die omgewings-ontwerpsnelhede, na verstellings van die waardes om te vergoed
vir die kort data rekords wat gebruik is. ‘n Kritiese vergelykingstudie wat gedoen is
tussen die resultate van die huidige studie, en die vorige waarop die huidige laskodes
vir Suid-Afrika gebaseer is, dui aan dat die huidige studie betroubaarder skattings van
die kwantiele behoort op te lewer.
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