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Delft University of Technology

1. Hermans, Carlos (author). Several approaches to model multi-commodity dynamical flow: on a package transport network.

Degree: 2019, Delft University of Technology

This thesis investigates several kinds of models of describing multi-commodity dynamical flow. Three models have been developed for a spatial logistic network, on which packages are delivered by vehicles and another model was developed to describe interactions between the customers, the stores and the deliverers, which does not explicitly take delivery time into account like before. The former three models consist of an agent-based model (ABM), and two different (differential) equation-based models (EBMs). One of the EBMs is built from the bottom up, and was created by averaging the randomness in the ABM. The other EBM was built top-down and involved optimizing a general model with respect to some parameters, such that its solution resembles the ABM solution as closely as possible. These three models were tested and compared in the first half of the thesis. In the second part of the thesis, the focus shifted to a generalized model (GM) approach of underlying interactions on multi-commodity dynamical flow networks; especially the dynamics describing order placement, scheduling and delivery. Such a network is cyclic and contains a feedback loop, where customers are less likely to order more products if they were recently delivered. This can range from someone not needing to purchase a car if they just bought a brand new one to one not needing to order dinner when they just did so. Such networks are in general described by four kinds of elasticities in this thesis, namely the elasticities to stock, inventory level, saturation, and co-production. These influence different parts in the network. For example, the negative elasticities to inventory level model that high inventory levels inhibit more inventory production, to prevent build-up, and low inventory levels allow for larger inventory production, to prevent drainage. The other elasticities fulfil similar roles. This model was tested using a bifurcation analysis, a statistical ensemble method and by computing influences and sensitivities of parts and nodes in the network.

Computational Science and Engineering

Advisors/Committee Members: Dubbeldam, Johan (mentor), Stam, Andries (mentor), Schuttelaars, Henk (graduation committee), van Essen, Theresia (graduation committee), Delft University of Technology (degree granting institution).

Subjects/Keywords: Agent-Based Modeling; Differential Equations; Generalized Models; Dynamical flow; Multi-commodity; Logistics; Bifurcation; Package transport

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hermans, C. (. (2019). Several approaches to model multi-commodity dynamical flow: on a package transport network. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:cb378d8b-02b9-42dd-812c-36556a0f6902

Chicago Manual of Style (16th Edition):

Hermans, Carlos (author). “Several approaches to model multi-commodity dynamical flow: on a package transport network.” 2019. Masters Thesis, Delft University of Technology. Accessed November 30, 2020. http://resolver.tudelft.nl/uuid:cb378d8b-02b9-42dd-812c-36556a0f6902.

MLA Handbook (7th Edition):

Hermans, Carlos (author). “Several approaches to model multi-commodity dynamical flow: on a package transport network.” 2019. Web. 30 Nov 2020.

Vancouver:

Hermans C(. Several approaches to model multi-commodity dynamical flow: on a package transport network. [Internet] [Masters thesis]. Delft University of Technology; 2019. [cited 2020 Nov 30]. Available from: http://resolver.tudelft.nl/uuid:cb378d8b-02b9-42dd-812c-36556a0f6902.

Council of Science Editors:

Hermans C(. Several approaches to model multi-commodity dynamical flow: on a package transport network. [Masters Thesis]. Delft University of Technology; 2019. Available from: http://resolver.tudelft.nl/uuid:cb378d8b-02b9-42dd-812c-36556a0f6902


University of Southern California

2. Zipfel, Ruth A. Network accessibility and population change: historical analysis of transportation in Tennessee, 1830-2010.

Degree: MS, Geographic Information Science and Technology, 2015, University of Southern California

This thesis examines how potential accessibility (A(P)) through transportation over the time span of this study (1830-2010) affected population growth by county for the state of Tennessee. It focuses on shifts in transportation networks from waterways to rail, and rail to roadways, using decennial census data and likewise temporally adjusted county boundaries. The span of this study was broken into four individual time periods to best measure major transitions in transportation: waterways (1830-1850), railways (1860-1920), historic roads (1930-1970), and modern roads (1980-2010). Potential accessibility, which was anticipated to have influenced the population change taking place within the state over time, was measured using Esri ArcMap geographical information system (GIS) and a series of network datasets. Calculations of population sums, geographic measurements, and network accessibility were accomplished using both Microsoft (MS) Excel and Esri ArcMap. Linear regression modeling was performed using Statistical Package for the Social Sciences (SPSS). The results suggest that the variable influence was dependent on the study period, and although conclusively correlated at times, other variables in addition to or other than transport accessibility also proved significant in several of the study periods. Specifically, the waterways study period showed a direct correlation with the population growth and transport networks during this time, though additional variables could have contributed to population change as well. The railway network did not significantly contribute to population changes going on during this time, likely directly related to the onset of the Civil War which hindered the development and growth of this transport system. While starting population share proved to be significant, with higher growth in counties that started out with larger populations, again additional variables could help explain population growth during the railway study period. Potential accessibility and starting share collectively explained almost 90% of the variance within the historic road model, proving significant and likewise leaving very little of the change in population unexplained during that time period. Oddly, while the potential accessibility was significant, unlike theorized within this study counties less accessible to transport networks actually grew more quickly than those with higher accessibility. Finally, modern roads were found to be significant in population change as well and highly correlated. Additional steps to improve on this study in the future would include considering connections outside of the state, particularly in non-Tennessee peripheral localities with high populations. Secondly, investigation of additional variables such as economic data over a shorter overall time span, or using dasymetric allocation methods, could also provide further explanation behind population changes taking place over time. Advisors/Committee Members: Swift, Jennifer N. (Committee Chair), Vos, Robert O. (Committee Member), Rigby, David (Committee Member).

Subjects/Keywords: Network Analyst; GIS; geographical information systems; SPSS; Tennessee; history; transport networks; linear regression model; census data; historic transport; waterway transport; railway transport; road network; Statistical Package for the Social Sciences

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Zipfel, R. A. (2015). Network accessibility and population change: historical analysis of transportation in Tennessee, 1830-2010. (Masters Thesis). University of Southern California. Retrieved from http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/607074/rec/4363

Chicago Manual of Style (16th Edition):

Zipfel, Ruth A. “Network accessibility and population change: historical analysis of transportation in Tennessee, 1830-2010.” 2015. Masters Thesis, University of Southern California. Accessed November 30, 2020. http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/607074/rec/4363.

MLA Handbook (7th Edition):

Zipfel, Ruth A. “Network accessibility and population change: historical analysis of transportation in Tennessee, 1830-2010.” 2015. Web. 30 Nov 2020.

Vancouver:

Zipfel RA. Network accessibility and population change: historical analysis of transportation in Tennessee, 1830-2010. [Internet] [Masters thesis]. University of Southern California; 2015. [cited 2020 Nov 30]. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/607074/rec/4363.

Council of Science Editors:

Zipfel RA. Network accessibility and population change: historical analysis of transportation in Tennessee, 1830-2010. [Masters Thesis]. University of Southern California; 2015. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/607074/rec/4363

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