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Carling, K., Håkansson, J., Meng, X. & Rudholm, N. (2017). The effect on CO2 emissions of taxing truck distance in retail transports. Transportation Research Part A: Policy and Practice, 97, 47-54
Open this publication in new window or tab >>The effect on CO2 emissions of taxing truck distance in retail transports
2017 (English)In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 97, p. 47-54Article in journal (Refereed) Published
Abstract [en]

To finance transportation infrastructure and to address social and environmental negative externalities of road transports, several countries have recently introduced or consider a distance based tax on trucks. In competitive retail and transportation markets, such tax can be expected to lower the demand and thereby reduce CO2 emissions of road transports. However, as we show in this paper, such tax might also slow down the transition towards e-tailing. Considering that previous research indicates that a consumer switching from brick-and-mortar shopping to e-tailing reduces her CO2 emissions substantially, the direction and magnitude of the environmental net effect of the tax is unclear. In this paper, we assess the net effect in a Swedish regional retail market where the tax not yet is in place. We predict the net effect on CO2 emissions to be positive, but off-set by about 50% because of a slower transition to e-tailing.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Spatial distribution of e-tailing and consumers; CO2 emissions measurement; online retailing; environmental taxes; carbon footprint; road network
National Category
Transport Systems and Logistics
Research subject
Complex Systems – Microdata Analysis, General Microdata Analysis - transports; Complex Systems – Microdata Analysis, General Microdata Analysis - retail
Identifiers
urn:nbn:se:du-23917 (URN)10.1016/j.tra.2017.01.010 (DOI)000395612300004 ()
Funder
Swedish Retail and Wholesale Development Council
Available from: 2017-01-11 Created: 2017-01-11 Last updated: 2017-11-15Bibliographically approved
Carling, K. & Meng, X. (2016). On statistical bounds of heuristic solutions to location problems. Journal of combinatorial optimization, 31(4), 1518-1549
Open this publication in new window or tab >>On statistical bounds of heuristic solutions to location problems
2016 (English)In: Journal of combinatorial optimization, ISSN 1382-6905, E-ISSN 1573-2886, Vol. 31, no 4, p. 1518-1549Article in journal (Refereed) Published
Abstract [en]

Solutions to combinatorial optimization problems, such as problems of locating facilities, frequently rely on heuristics to minimize the objective function. The optimum is sought iteratively and a criterion is needed to decide when the procedure (almost) attains it. Pre-setting the number of iterations dominates in OR applications, which implies that the quality of the solution cannot be ascertained. A small, almost dormant, branch of the literature suggests using statistical principles to estimate the minimum and its bounds as a tool to decide upon stopping and evaluating the quality of the solution. In this paper we examine the functioning of statistical bounds obtained from four different estimators by using simulated annealing on p-median test problems taken from Beasley’s OR-library. We find the Weibull estimator and the 2nd order Jackknife estimator preferable and the requirement of sample size to be about 10 being much less than the current recommendation. However, reliable statistical bounds are found to depend critically on a sample of heuristic solutions of high quality and we give a simple statistic useful for checking the quality. We end the paper with an illustration on using statistical bounds in a problem of locating some 70 distribution centers of the Swedish Post in one Swedish region.

Keywords
p-median problem;simulated annealing; jack-knife; discrete optimization; extreme value theory
National Category
Probability Theory and Statistics
Research subject
Complex Systems – Microdata Analysis, General Microdata Analysis - methods
Identifiers
urn:nbn:se:du-16828 (URN)10.1007/s10878-015-9839-0 (DOI)000373574300012 ()
Available from: 2015-02-09 Created: 2015-02-09 Last updated: 2017-12-04Bibliographically approved
Meng, X. & Rebreyend, P. (2016). On transforming a road network database to a graph for localization purpose. International Journal of Web Services Research, 13(2), 46-55
Open this publication in new window or tab >>On transforming a road network database to a graph for localization purpose
2016 (English)In: International Journal of Web Services Research, ISSN 1545-7362, E-ISSN 1546-5004, Vol. 13, no 2, p. 46-55Article in journal (Refereed) Published
Abstract [en]

The problems of finding best facility locations require complete and accurate road networks with the corresponding population data in a specific area. However the data obtained from road network databases usually do not fit in this usage. In this paper we propose a procedure of converting the road network database to a road graph which could be used for localization problems. Several challenging problems exist in the transformation process which are commonly met also in other data bases. The procedure of dealing with those challenges are proposed. The data come from the National road data base in Sweden. The graph derived is cleaned, and reduced to a suitable level for localization problems. The residential points are also processed in ordered to match the graph. The reduction of the graph is done maintaining the accuracy of distance measures in the network.

Keywords
road network, graph, population, GIS
National Category
Economic Geography
Research subject
Complex Systems – Microdata Analysis
Identifiers
urn:nbn:se:du-17361 (URN)10.4018/IJWSR.2016040103 (DOI)000384810100004 ()
Available from: 2015-05-07 Created: 2015-05-07 Last updated: 2017-12-04Bibliographically approved
Carling, K. & Meng, X. (2015). Confidence in heuristic solutions?. Journal of Global Optimization, 63(2), 381-399
Open this publication in new window or tab >>Confidence in heuristic solutions?
2015 (English)In: Journal of Global Optimization, ISSN 0925-5001, E-ISSN 1573-2916, Vol. 63, no 2, p. 381-399Article in journal (Refereed) Published
Abstract [en]

Solutions to combinatorial optimization problems frequently rely on heuristics to minimize an objective function. The optimum is sought iteratively and pre-setting the number of iterations dominates in operations research applications, which implies that the quality of the solution cannot be ascertained. Deterministic bounds offer a mean of ascertaining the quality, but such bounds are available for only a limited number of heuristics and the length of the interval may be difficult to control in an application. A small, almost dormant, branch of the literature suggests using statistical principles to derive statistical bounds for the optimum. We discuss alternative approaches to derive statistical bounds. We also assess their performance by testing them on 40 test p-median problems on facility location, taken from Beasley’s OR-library, for which the optimum is known. We consider three popular heuristics for solving such location problems; simulated annealing, vertex substitution, and Lagrangian relaxation where only the last offers deterministic bounds. Moreover, we illustrate statistical bounds in the location of 71 regional delivery points of the Swedish Post. We find statistical bounds reliable and much more efficient than deterministic bounds provided that the heuristic solutions are sampled close to the optimum. Statistical bounds are also found computationally affordable.

Keywords
p-median problem, deterministic bounds, statistical bounds, jackknife, discrete optimization, extreme value theory
National Category
Probability Theory and Statistics Computational Mathematics
Research subject
Komplexa system - mikrodataanalys, General Microdata Analysis - methods
Identifiers
urn:nbn:se:du-17153 (URN)10.1007/s10898-015-0293-4 (DOI)000361485700009 ()
Available from: 2015-03-17 Created: 2015-03-17 Last updated: 2017-12-04Bibliographically approved
Carling, K., Han, M., Håkansson, J., Meng, X. & Rudholm, N. (2015). Measuring transport related CO2 emissions induced by online and brick-and-mortar retailing. Transportation Research Part D: Transport and Environment, 40, 28-42
Open this publication in new window or tab >>Measuring transport related CO2 emissions induced by online and brick-and-mortar retailing
Show others...
2015 (English)In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 40, p. 28-42Article in journal (Refereed) Published
Abstract [en]

We develop a method for empirically measuring the difference in transport related carbon footprint between traditional and online retailing (“e-tailing”) from entry point to a geographical area to consumer residence. The method only requires data on the locations of brick-and-mortar stores, online delivery points, and residences of the region’s population, and on the goods transportation networks in the studied region. Such data are readily available in most countries. The method has been evaluated using data from the Dalecarlia region in Sweden, and is shown to be robust to all assumptions made. In our empirical example, the results indicate that the average distance from consumer residence to a brick-and-mortar retailer is 48.54 km in the studied region, while the average distance to an online delivery point is 6.7 km. The results also indicate that e-tailing increases the average distance traveled from the regional entry point to the delivery point from 47.15 km for a brick-and-mortar store to 122.75 km for the online delivery points. However, as professional carriers transport the products in bulk to stores or online delivery points, which is more efficient than consumers’ transporting the products to their residences, the results indicate that consumers switching from traditional to e-tailing on average reduce their transport CO2 footprints by 84% when buying standard consumer electronics products. 

Keywords
E-tailing; Spatial distribution of firms and consumers; p-median model; Emission measurement; Emission reduction
National Category
Economic Geography Environmental Sciences
Research subject
Complex Systems – Microdata Analysis, General Microdata Analysis - transports; Complex Systems – Microdata Analysis, General Microdata Analysis - retail
Identifiers
urn:nbn:se:du-18930 (URN)10.1016/j.trd.2015.07.010 (DOI)000364896200003 ()
Available from: 2015-07-28 Created: 2015-07-28 Last updated: 2017-12-04Bibliographically approved
Meng, X. (2015). Optimization heuristic solutions, how good can they be?: With empirical applications in location problems. (Doctoral dissertation). Borlänge: Dalarna University
Open this publication in new window or tab >>Optimization heuristic solutions, how good can they be?: With empirical applications in location problems
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Combinatorial optimization problems, are one of the most important types of problems in operational research. Heuristic and metaheuristics algorithms are widely applied to find a good solution. However, a common problem is that these algorithms do not guarantee that the solution will coincide with the optimum and, hence, many solutions to real world OR-problems are afflicted with an uncertainty about the quality of the solution. The main aim of this thesis is to investigate the usability of statistical bounds to evaluate the quality of heuristic solutions applied to large combinatorial problems. The contributions of this thesis are both methodological and empirical. From a methodological point of view, the usefulness of statistical bounds on p-median problems is thoroughly investigated. The statistical bounds have good performance in providing informative quality assessment under appropriate parameter settings. Also, they outperform the commonly used Lagrangian bounds. It is demonstrated that the statistical bounds are shown to be comparable with the deterministic bounds in quadratic assignment problems. As to empirical research, environment pollution has become a worldwide problem, and transportation can cause a great amount of pollution. A new method for calculating and comparing the CO2-emissions of online and brick-and-mortar retailing is proposed. It leads to the conclusion that online retailing has significantly lesser CO2-emissions. Another problem is that the Swedish regional division is under revision and the border effect to public service accessibility is concerned of both residents and politicians. After analysis, it is shown that borders hinder the optimal location of public services and consequently the highest achievable economic and social utility may not be attained.

Abstract [sv]

Kombinatoriska optimeringsproblem, är en av de viktigaste typerna av problem i operationsanalys (OR). Heuristiska och metaheuristiska algoritmer tillämpas allmänt för att hitta lösningar med hög kvalitet. Ett vanligt problem är dock att dessa algoritmer inte garanterar optimala lösningar och sålunda kan det finnas osäkerhet i kvaliteten på lösningar på tillämpade operationsanalytiska problem. Huvudsyftet med denna avhandling är att undersöka användbarheten av statistiska konfidensintervall för att utvärdera kvaliteten på heuristiska lösningar då de tillämpas på stora kombinatoriska optimeringsproblem. Bidragen från denna avhandling är både metodologiska och empiriska. Ur metodologisk synvinkel har nyttan av statistiska konfidensintervall för ett lokaliseringsproblem (p-median problemet) undersökts. Statistiska konfidensintervall fungerar väl för att tillhandahålla information om lösningens kvalitet vid rätt implementering av problemen. Statistiska konfidensintervall överträffar även intervallen som erhålls vid den vanligen använda Lagrange-relaxation. I avhandlingen visas även på att metoden med statistiska konfidensintervall är fungerar väl jämfört med många andra deterministiska intervall i ett mer komplexa optimeringsproblem som det kvadratiska tilldelningsproblemet. P-median problemet och de statistiska konfidensintervallen har implementerats empiriskt för att beräkna och jämföra e-handelns och traditionell handels CO2-utsläpp från transporter, vilken visar att ehandel medför betydligt mindre CO2-utsläpp. Ett annat lokaliseringsproblem som analyserats empiriskt är hur förändringar av den regionala administrativa indelningen av Sverige, vilket är en aktuell och pågående samhällsdiskussion, påverkar medborgarnas tillgänglighet till offentlig service. Analysen visar att regionala administrativa iv gränserna lett till en suboptimal placering av offentliga tjänster. Därmed finns en risk att den samhällsekonomiska nyttan av dessa tjänster är suboptimerad.

Place, publisher, year, edition, pages
Borlänge: Dalarna University, 2015. p. 200
Series
Dalarna Doctoral Dissertations in Microdata Analysis ; 2
National Category
Computational Mathematics
Research subject
Complex Systems – Microdata Analysis
Identifiers
urn:nbn:se:du-17353 (URN)978-91-89020-94-8 (ISBN)
Public defence
2015-04-23, Clas Ohlson, Borlänge, 10:00 (English)
Opponent
Supervisors
Available from: 2015-05-07 Created: 2015-05-06 Last updated: 2019-06-17Bibliographically approved
Meng, X. (2015). Statistical bound of genetic solutions to quadratic assignment problems. Borlänge: Högskolan Dalarna
Open this publication in new window or tab >>Statistical bound of genetic solutions to quadratic assignment problems
2015 (English)Report (Other academic)
Abstract [en]

Quadratic assignment problems (QAPs) are commonly solved by heuristic methods, where the optimum is sought iteratively. Heuristics are known to provide good solutions but the quality of the solutions, i.e., the confidence interval of the solution is unknown. This paper uses statistical optimum estimation techniques (SOETs) to assess the quality of Genetic algorithm solutions for QAPs. We examine the functioning of different SOETs regarding biasness, coverage rate and length of interval, and then we compare the SOET lower bound with deterministic ones. The commonly used deterministic bounds are confined to only a few algorithms. We show that, the Jackknife estimators have better performance than Weibull estimators, and when the number of heuristic solutions is as large as 100, higher order JK-estimators perform better than lower order ones. Compared with the deterministic bounds, the SOET lower bound performs significantly better than most deterministic lower bounds and is comparable with the best deterministic ones. 

Place, publisher, year, edition, pages
Borlänge: Högskolan Dalarna, 2015. p. 20
Series
Working papers in transport, tourism, information technology and microdata analysis, ISSN 1650-5581 ; 2015:02
Keywords
quadratic assignment problem, genetic algorithm, Jack-knife, discrete optimization, extreme value theory
National Category
Computer Engineering
Research subject
Komplexa system - mikrodataanalys
Identifiers
urn:nbn:se:du-17034 (URN)
Available from: 2015-03-02 Created: 2015-03-02 Last updated: 2018-01-11Bibliographically approved
Carling, K., Håkansson, J., Meng, X. & Rudholm, N. (2015). The effects of taxing truck distance on CO2 emissions from transports in retailing.
Open this publication in new window or tab >>The effects of taxing truck distance on CO2 emissions from transports in retailing
2015 (English)Report (Other academic)
Abstract [en]

To finance transportation infrastructure and to address social and environmental negative externalities of road transports, several countries have recently introduced or consider a distance based tax on trucks. In the competitive retail market such tax can be expected to lower the demand and thereby reduce CO2 emissions of road transports. However, as we show in this paper, such tax might also slow down the transition towards e-tailing. Considering that previous research indicates that a consumer switching from brick-and-mortar shopping to e-tailing reduces her CO2 emissions substantially, the direction and magnitude of the environmental net effect of the tax is unclear. In this paper, we assess the net effect in a Swedish regional retail market where the tax not yet is in place. We predict the net effect on CO2 emissions to be positive, but off-set by about 50% because of a slower transition to e-tailing.

Publisher
p. 14
Series
Working papers in transport, tourism, information technology and microdata analysis, ISSN 1650-5581 ; 2015:07
Keywords
Spatial distribution of e-tailing and consumers; CO2 emissions measurement; online retailing; environmental taxes; carbon footprint; road network
National Category
Economics Transport Systems and Logistics Other Earth and Related Environmental Sciences
Research subject
Komplexa system - mikrodataanalys, General Microdata Analysis - transports; Komplexa system - mikrodataanalys, General Microdata Analysis - retail
Identifiers
urn:nbn:se:du-17860 (URN)
Available from: 2015-06-12 Created: 2015-06-12 Last updated: 2015-07-01Bibliographically approved
Carling, K. & Meng, X. (2014). Confidence in heuristic solutions?. Borlänge: Högskolan Dalarna
Open this publication in new window or tab >>Confidence in heuristic solutions?
2014 (English)Report (Other academic)
Abstract [en]

Solutions to combinatorial optimization problems frequently rely on heuristics to minimize an objective function. The optimum is sought iteratively and pre-setting the number of iterations dominates in operations research applications, which implies that the quality of the solution cannot be ascertained. Deterministic bounds offer a mean of ascertaining the quality, but such bounds are available for only a limited number of heuristics and the length of the interval may be difficult to control in an application. A small, almost dormant, branch of the literature suggests using statistical principles to derive statistical bounds for the optimum. We discuss alternative approaches to derive statistical bounds. We also assess their performance by testing them on 40 test p-median problems on facility location, taken from Beasley’s OR-library, for which the optimum is known. We consider three popular heuristics for solving such location problems; simulated annealing, vertex substitution, and Lagrangian relaxation where only the last offers deterministic bounds. Moreover, we illustrate statistical bounds in the location of 71 regional delivery points of the Swedish Post. We find statistical bounds reliable and much more efficient than deterministic bounds provided that the heuristic solutions are sampled close to the optimum. Statistical bounds are also found computationally affordable.

Place, publisher, year, edition, pages
Borlänge: Högskolan Dalarna, 2014. p. 26
Series
Working papers in transport, tourism, information technology and microdata analysis, ISSN 1650-5581 ; 2014:12
National Category
Economic Geography Probability Theory and Statistics
Research subject
Komplexa system - mikrodataanalys
Identifiers
urn:nbn:se:du-14457 (URN)
Available from: 2014-06-23 Created: 2014-06-23 Last updated: 2015-05-07Bibliographically approved
Meng, X. & Rebreyend, P. (2014). From the road network database to a graph for localization purposes. Borlänge: Högskolan Dalarna
Open this publication in new window or tab >>From the road network database to a graph for localization purposes
2014 (English)Report (Other academic)
Abstract [en]

The problems of finding best facility locations require complete and accurate road network with the corresponding population data in a specific area. However the data obtained in road network databases usually do not fit in this usage. In this paper we propose our procedure of converting the road network database to a road graph which could be used in localization problems. The road network data come from the National road data base in Sweden. The graph derived is cleaned, and reduced to a suitable level for localization problems. The population points are also processed in ordered to match with that graph. The reduction of the graph is done maintaining most of the accuracy for distance measures in the network.

Place, publisher, year, edition, pages
Borlänge: Högskolan Dalarna, 2014
Series
Working papers in transport, tourism, information technology and microdata analysis, ISSN 1650-5581 ; 2014:09
Keywords
road network, graph, population, GIS
National Category
Computer and Information Sciences
Research subject
Komplexa system - mikrodataanalys
Identifiers
urn:nbn:se:du-14066 (URN)
Available from: 2014-05-05 Created: 2014-05-05 Last updated: 2018-01-11Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2970-9622

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