16 research outputs found
Factors affecting vessel turnaround time at the port of Richards Bay dry bulk terminal.
Masters Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF
Historia, evolución y perspectivas de futuro en la utilización de técnicas de simulación en la gestión portuaria: aplicaciones en el análisis de operaciones, estrategia y planificación portuaria
Programa Oficial de Doutoramento en Análise Económica e Estratexia Empresarial. 5033V0[Resumen]
Las técnicas de simulación, tal y como hoy las conocemos, comenzaron a mediados del siglo
XX; primero con la aparición del primer computador y el desarrollo del método Monte Carlo, y
más tarde con el desarrollo del primer simulador de propósito específico conocido como GPS y
desarrollado por Geoffrey Gordon en IBM y la publicación del primer texto completo dedicado a
esta materia y llamado the Art of Simulation (K.D. Tocher, 1963).
Estás técnicas han evolucionado de una manera extraordinaria y hoy en día están plenamente
implementadas en diversos campos de actividad.
Las instalaciones portuarias no han escapado de esta tendencia, especialmente las dedicadas al
tráfico de contenedores.
Efectivamente, las características intrínsecas de este sector económico, le hacen un candidato
idóneo para la implementación de modelos de simulación con propósitos y alcances muy diversos.
No existe, sin embargo y hasta lo que conocemos, un trabajo científico que compile y analice
pormenorizadamente tanto la historia como la evolución de simulación en ambientes portuarios,
ayudando a clasificar los mismos y determinar cómo estos pueden ayudar en el análisis económico
de estas instalaciones y en la formulación de las oportunas estrategias empresariales.
Este es el objetivo último de la presente tesis doctoral.[Resumo]
As técnicas de simulación, tal e como hoxe as coñecemos, comezaron a mediados do século XX;
primeiro coa aparición do computador e o desenvolvemento do método Monte Carlo e máis tarde
co desenvolvemento do primeiro simulador de propósito específico coñecido como GPS e
desenvolvido por Geoffrey Gordon en IBM e a publicación do primeiro texto completo dedicado
a este tema chamado “A Arte da Simulación” (K.D. Tocher, 1963).
Estas técnicas evolucionaron dun xeito extraordinario e hoxe en día están plenamente
implementadas en diversos campos de actividade.
As instalacións portuarias non escaparon desta tendencia, especialmente as dedicadas ao tráfico
de contenedores.
Efectivamente, as características intrínsecas deste sector económico, fanlle un candidato idóneo
para a implementación de modelos de simulación con propósitos e alcances moi variados.
Con todo, e ata o que coñecemos, non existe un traballo científico que compila e analiza de forma
detallada tanto a historia como a evolución da simulación en estes ambientes portuarios,
clasificando os mesmos e determinando como estes poden axudar na análise económica destas
instalacións e na formulación das oportunas estratexias empresariais.
Este é o último obxectivo da presente tese doutoral.[Abstract]
Simulation, to the extend that we understand it nowadays, began in the middle of the 20th century;
first with the appearance of the computer and the development of the Monte Carlo method, and
later with the development of the first specific purpose simulator known as GPS developed by
Geoffrey Gordon in IBM. This author published the first full text devoted to this subject “The Art
of Simulation” in 1963.
These techniques have evolved in an extraordinary way and nowadays they are fully implemented
in different fields of activity.
Port facilities have not escaped this trend, especially those dedicated to container traffic.
Indeed, the intrinsic characteristics of this economic sector, make it a suitable candidate for the
implementation of simulation with very different purposes and scope.
However, to the best of our knowelegde, there is not a scientific work that compiles and analyzes
in detail both, the history and the evolution of simulation in port environments, contributing to
classify them and determine how they can help in the economic analysis of these facilities and in
the formulation of different business strategies.
This is the ultimate goal of this doctoral thesis
XVIII International Coal Preparation Congress
Changes in economic and market conditions of mineral raw materials in recent
years have greatly increased demands on the ef fi ciency of mining production. This
is certainly true of the coal industry. World coal consumption is growing faster than
other types of fuel and in the past year it exceeded 7.6 billion tons. Coal extraction
and processing technology are continuously evolving, becoming more economical
and environmentally friendly. “ Clean coal ” technology is becoming increasingly
popular. Coal chemistry, production of new materials and pharmacology are now
added to the traditional use areas — power industry and metallurgy. The leading role
in the development of new areas of coal use belongs to preparation technology and
advanced coal processing. Hi-tech modern technology and the increasing interna-
tional demand for its effectiveness and ef fi ciency put completely new goals for the
University. Our main task is to develop a new generation of workforce capacity and
research in line with global trends in the development of science and technology to
address critical industry issues.
Today Russia, like the rest of the world faces rapid and profound changes
affecting all spheres of life. The de fi ning feature of modern era has been a rapid
development of high technology, intellectual capital being its main asset and
resource. The dynamics of scienti fi c and technological development requires acti-
vation of University research activities. The University must be a generator of ideas
to meet the needs of the economy and national development. Due to the high
intellectual potential, University expert mission becomes more and more called for
and is capable of providing professional assessment and building science-based
predictions in various fi elds.
Coal industry, as well as the whole fuel and energy sector of the global economy
is growing fast. Global multinational energy companies are less likely to be under
state in fl uence and will soon become the main mechanism for the rapid spread of
technologies based on new knowledge. Mineral resources will have an even greater
impact on the stability of the economies of many countries. Current progress in the
technology of coal-based gas synthesis is not just a change in the traditional energy markets, but the emergence of new products of direct consumption, obtained from
coal, such as synthetic fuels, chemicals and agrochemical products. All this requires
a revision of the value of coal in the modern world economy
Dimensionamiento y optimización de la operativa en las terminales de graneles sólidos = Dimensioning and optimization of operations for dry bulk terminals
This thesis studies the factors that influence the optimization, and sizing, of dry bulk terminals, while looking for a model to reflect them.
At the same time it provides an overview of dry bulk shipping, and its marine operations, while identifying literature linked to the sector.
In the first part (Chapter 1 y 2) we study and analyze all the factors that tend to influence or affect the characteristics of a port terminal.
In the second part (Chapter 3 and 4) a series of international terminals are analyzed, called "Wold Champions" and a part of the largest bulk terminals in the spanish coast, as well.
After analyzing in detail the different types of terminals, it concludes by pointing out those decisive factors considered in the terminal design, such as ships dimensions, while considering that the sector volatility sometimes can force strategy changes due expected traffic modificationsEsta tesis estudia los factores que influyen en la optimización y dimensionamiento de las terminales de graneles sólidos, a la vez que busca un modelo para reflejarlos. A la vez pretende aportar una visión general del mundo del transporte marítimo de graneles sólidos, y su operativa, agrupando e identificado la bibliografía ligada al sector. En una primera parte (Capítulos 1 y 2) se estudian, y analizan, todos aquellos factores que influyen en las características de una terminal portuaria de graneles sólidos. En una segunda parte(Capítulos 3 y 4) se analizan una serie de terminales internacionales de graneles sólidos, las denominadas "campeones mundiales", y una gran parte de las mayores terminales ubicadas en el litoral español. Tras analizar detalladamente las diferentes tipologías de terminales se concluye señalando aquellos factores determinantes a la hora de proceder al diseño de la terminal, como son las dimensiones del buque, ala vez que se indica la volatilidad que sufre el sector y que en ocasiones puede obligar a cambios de estrategia por modificaciones sobre los tráficos previstos.Postprint (published version
A reclaimer scheduling problem arising in coal stockyard management
We study a number of variants of an abstract scheduling problem inspired by
the scheduling of reclaimers in the stockyard of a coal export terminal. We
analyze the complexity of each of the variants, providing complexity proofs for
some and polynomial algorithms for others. For one, especially interesting
variant, we also develop a constant factor approximation algorithm.Comment: 26 page
Time Localization of Abrupt Changes in Cutting Process using Hilbert Huang Transform
Cutting process is extremely dynamical process influenced by different phenomena such as chip formation, dynamical responses and condition of machining system elements. Different phenomena in cutting zone have signatures in different frequency bands in signal acquired during process monitoring. The time localization of signal’s frequency content is very important.
An emerging technique for simultaneous analysis of the signal in time and frequency domain that can be used for time localization of frequency is Hilbert Huang Transform (HHT). It is based on empirical mode decomposition (EMD) of the signal into intrinsic mode functions (IMFs) as simple oscillatory modes. IMFs obtained using EMD can be processed using Hilbert Transform and instantaneous frequency of the signal can be computed.
This paper gives a methodology for time localization of cutting process stop during intermittent turning. Cutting process stop leads to abrupt changes in acquired signal correlated to certain frequency band. The frequency band related to abrupt changes is localized in time using HHT. The potentials and limitations of HHT application in machining process monitoring are shown
The measurement of supply chain efficiency : theoretical considerations and practical criteria
Thesis (PhD (Logistics))--University of Stellenbosch, 2010.ENGLISH SUMMARY: In an effort to compete globally, South African supply chains must achieve and maintain a competitive
advantage. One way of achieving this is by ensuring that South African supply chains are as efficient
as possible. Consequently, steps must be taken to evaluate the efficiency levels of South African
supply chains. This dissertation develops the composite supply chain efficiency model using variables
specifically identified as problem areas experienced by South African supply chains. The composite
supply chain efficiency model evaluates the overall efficiency of a supply chain based on three criteria,
namely, reliability efficiency, cost efficiency and speed efficiency. It identifies bottlenecks along the
supply chain and in so doing identifies key focus areas for firms if they want to improve their overall
efficiency and become more competitive.
3AFRIKAANSE OPSOMMING: In ’n poging om wˆereldwyd te kompeteer, moet Suid-Afrikaanse voorsieningskettings ’n mededingende
voordeel behaal en handhaaf. Een manier om dit te bereik is om te verseker dat Suid-Afrikaanse voorsieningskettings
so doeltreffend as moontlik funksioneer. Gevolglik moet stappe gedoen word om die
doeltreffendheidsvlakke van die Suid-Afrikaanse voorsieningskettings te evalueer. Hierdie proefskrif het
die saamgestelde voorsieningsketting doeltreffendheidsmodel ontwikkel wat veranderlikes gebruik wat
spesifiek ge¨ıdentifiseer is as probleemgebiede in Suid-Afrikaanse voorsieningskettings. Die saamgestelde
voorsieningsketting doeltreffendheidsmodel evalueer die algehele doeltreffendheid van ’n voorsieningsketting
gebaseer op drie kriteria, naamlik, betroubaarheidsdoeltreffendheid, koste-doeltreffendheid en
spoed-doeltreffendheid. Dit identifiseer knelpunte in die voorsieningsketting en identifiseer belangrike
fokusareas vir ondernemings wat aangespreek moet word as hul algehele doeltreffendheid wil verbeter
en meer mededingend raak.jfl201
Leader Firms: The value of companies for the competitiveness of the Rotterdam seaport cluster
The port of Rotterdam is the largest seaport in Europe and a huge industrial complex. This seaport has been the focal point of several studies that merely view the port as a transport node. This neglects the fact that it is also a collection of thousands of related businesses that together form the Rotterdam seaport cluster.
This PhD thesis deals with the companies in the Rotterdam seaport cluster and their value for the competitiveness of the port. Companies active in many sectors, such as stevedoring, transport, logistics, off-shore and shipbuilding.
The competitiveness of the port of Rotterdam is dependent on the behavior of the firms located in the port cluster. Some firms create substantially more positive effects than others and are called ‘leader firms’. The Characteristics and the behavior of these leader firms are analyzed in this study.
The Rotterdam port cluster is defined and the business structure is researched to select the leader firms. Nine forms of leader firm behavior are identified in the fields of innovation, internationalization and cluster governance. With the use of a qualitative comparative analysis it is researched which firm characteristics foster leader firm behavior.
Conclusions are drawn about the role of leader firms in clusters and the stimulus and obstacles for leader firm behavior. Recommendations are formulated for the business community, government and the leader firms
Comparison of techniques for measuring the water content of soil and other porous media
The measurement of water in soil on a potential, gravimetric or volumetric basis is considered, with studies concentrating on the measurement of water by dielectric and neutron moderation methods. The ability of the time-domain reflectometry technique to measure water content simultaneously at different spatial locations is an important advantage of the technique. The reported apparent dielectric by the TRASE� time-domain reflectometer and Pyelab time-domain reflectometry systems is sensitive to change in extension cable length. In some soil, e.g. a commercial sand, the response to increasing extension length of extension cable is linear. For other soil a linear response occurs for certain lengths of cable at different moisture contents. A single model accounting for clay content, extension cable length, time-domain reflectometry system, probe type and inherent moisture conditions explained 62.2 % of variation from the control (0 m extension) cable. The extension cable causes a decrease in the returning electromagnetic-wave energy; leading to a decline in the slope used in automatic end-point determination. Calibration for each probe installation when the soil is saturated, and at small water contents is recommended. The ability of time-domain reflectometry, frequency-domain and neutron moderation techniques in measuring soil water content in a Brown Chromosol is examined. An in situ calibration, across a limited range of water contents, for the neutron moderation method is more sensitive to changing soil water content than the factory supplied 'universal' calibration. Comparison of the EnviroSCAN� frequency-domain system and the NMM count ratio indicates the frequency-domain technique is more sensitive to change in soil water conditions. The EnviroSCAN� system is well suited to continuous profile-based measurement of soil water content. Results with the time-domain reflectometry technique were disappointing, indicating the limited applicability of time-domain reflectometry in profile based soil water content measurement in heavy-textured soil, or soil with a large electrical conductivity. The method of auguring to a known depth and placement of the time-domain reflectometry probe into undisturbed soil is not recommended. A time-domain reflectometry system is adapted for in situ measurement of water in an iron ore stockpile. The laboratory calibration for water content of the processed iron ore compares favourably to a field calibration. In the field study, the 28 m extension cable used to connect the probes to the time-domain reflectometry affected the end-point determination of the time-domain reflectometry system. To account for this, 0.197 should be subtracted from the reported apparent dielectric before calculation of volumetric moisture content