| 1. |
- Habibi, Habibi, 1978-, et al.
(författare)
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Aggregation of alternatives and its influence on prediction
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In car type choice models, alternatives are usually grouped into categories by some of their main characteristics such as make, model, vintage, body type and/or fuel type. Each of these categories contains di erent versions of the cars that are usually not recognized in the applied literature. In this study we empirically investigate whether including the heterogeneity of these versions in the modeling does matter in estimation and prediction or not. We use detailed data on alternatives available on the market down to the versions level of each model, which enables us to account for heterogeneity in the model. We also have Swedish car registry data to represent demand. We estimate separate discrete choice models with diferent methods of correction for alternative aggregation, including nesting structure. These models are estimated based on year 2006 Swedish registry data for new cars, and predict for 2007. The results show that including heterogeneity of cars' versions in the model improves model tness but it does not necessarily improve prediction results.
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| 2. |
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| 3. |
- Hunka, Agnieszka D., 1978-, et al.
(författare)
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What drives demand for paid access to a sharing box with underused items? : A choice experiment with Swedish consumers
- 2023
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 393
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Tidskriftsartikel (refereegranskat)abstract
- Determinants of consumer demand for subscription to a sharing platform for underused tools and hobby items were investigated in a series of choice experiments. The stated-preference study with a census-representative sample of 702 Swedish adults, tested four types of offers (sharing boxes) containing: gardening and power tools, photo and video equipment, kitchen and household tools and outdoor/sport equipment. Respondents faced hypothetical buying scenarios: they were asked to choose a subscription to a maintained and insured sharing box located in a public space and containing premium-segment items from one of the above categories. Results show that a possible location for a sharing box depends on its content - for instance, the sharing box with garden tools was preferred by small garden owners. It was also tested, in a demand simulation scenario, how measures aimed at managing utilisation of shared items, such as booking in advance, booking limits or location of the sharing box would affect the preference for the offer. Findings suggest that respondents would be willing to accept these inconveniences of sharing, provided the subscription price was set accordingly (25% lower than the average used across all experiments). Moreover, respondents seem to be using familiar digital subscriptions as a benchmark to determine a fair price for the offers used in the study. © 2022 The Author(s)
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| 4. |
- Melkamu Daniel, Aemiro, et al.
(författare)
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Expert elicitation of remote meat inspection prerequisites in Sweden using best-worst scaling (case 1)
- 2024
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Ingår i: Food Control. - : Elsevier Ltd. - 0956-7135 .- 1873-7129. ; 162
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Tidskriftsartikel (refereegranskat)abstract
- Remote work technologies offer unprecedented flexibility to modernise official meat inspection (MI). Remote meat inspections, alongside on-site controls have a potential to make MI more sustainable when it comes to working conditions, logistic control hurdles and travel-related emissions. Nevertheless, preferences of meat control staff for features and technological set up of remote MI remain unknown. The paper investigates preferences of official Swedish MI staff for different features of remote MI. The study utilises a quantitative method, namely best-worst scaling to compare the relative importance of six aspects of remote inspections: camera location and settings, connectivity, availability of personnel at abattoirs, communication and language, security and fraud prevention, and ability to relay olfaction and haptics. The survey, administered in September–October 2023 was answered by 54.7% of the Swedish meat control staff employed by the Swedish Food Agency. The results show that respondents rate security and fraud prevention (Security) as the most important aspect for remote MI followed by connectivity and camera placement (Camera). Communication and language (Communication) and ability to relay olfaction and haptics (Senses) are considered the least important aspects. The latter findings can be explained by the fact that Official Veterinarians, which represent the majority of respondents (49%), do not routinely communicate directly with slaughter personnel who are often seasonal workers coming from outside Sweden. Moreover, olfaction and haptics could be considered naturally impractical with remote technologies. The study also finds that respondents from different administrative units and job titles have different preferences for the features of remote MI. Respondents from the headquarter generally have higher preferences for connectivity than respondents from other units. Additionally, respondents with more hands-on experience in MI, such as Official Veterinarians, tend to rate security issues higher than respondents with leading or support roles. Overall, it seems possible to meet the control staff expectations and preferences regarding the prerequisites of remote MI by legal and technical adaptations needed for this type of control flexibility. © 2024 The Authors
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| 5. |
- Elhadi Adam, Rania, et al.
(författare)
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ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation
- 2019
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:15, s. 8271-8279
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Tidskriftsartikel (refereegranskat)abstract
- Ag-based compounds are excellent co-catalyst that can enhance harvesting visible light and increase photo-generated charge carrier separation owing to its surface plasmon resonance (SPR) effect in photoelectrochemical (PEC) applications. However, the PEC performance of a ZnO/Ag/Ag2WO4 heterostructure with SPR behavior has not been fully studied so far. Here we report the preparation of a ZnO/Ag/Ag2WO4 photo-electrode with SPR behavior by a low temperature hydrothermal chemical growth method followed by a successive ionic layer adsorption and reaction (SILAR) method. The properties of the prepared samples were investigated by different characterization techniques, which confirm that Ag/Ag2WO4 was deposited on the ZnO NRs. The Ag2WO4/Ag/ZnO photo-electrode showed an enhancement in PEC performance compared to bare ZnO NRs. The observed enhancement is attributed to the red shift of the optical absorption spectrum of the Ag2WO4/Ag/ZnO to the visible region (>400 nm) and to the SPR effect of surface metallic silver (Ag0) particles from the Ag/Ag2WO4 that could generate electron–hole pairs under illumination of low energy visible sun light. Finally, we proposed the PEC mechanism of the Ag2WO4/Ag/ZnO photo-electrode with an energy band structure and possible electron–hole separation and transportation in the ZnO/Ag/Ag2WO4 heterostructure with SPR effect for water oxidation. ER
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| 7. |
- Englund, Cristofer, et al.
(författare)
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Method for prediction of utilization rate of electric vehicle free-floating car sharing services using data mining
- 2018
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Ingår i: 31st International Electric Vehicle Symposium and Exhibition, EVS 2018 and International Electric Vehicle Technology Conference 2018, EVTeC 2018.
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Konferensbidrag (refereegranskat)abstract
- Free-floating car sharing is a form of car rental used by people for short periods of time where the cars can be picked up and returned anywhere within a given area. In this paper, we have collected free-floating car sharing data, for electric as well as fossil fueled cars, and data regarding e.g. size of the city, number of cars in the service, etc. The utilization rates of the free-floating car sharing services vary much between the cities, greatly influencing the success of the services. This paper presents the most important factors influencing the utilization rate, and also a methodology to predict the utilization rate for new cities, using data mining based on Random Forests.
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| 8. |
- Habibi, Shiva, 1978, et al.
(författare)
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An empirical study on aggregation of alternatives and its influence on prediction in car type choice models
- 2019
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Ingår i: Transportation. - : Springer Science and Business Media LLC. - 0049-4488 .- 1572-9435. ; 46:3, s. 563-582
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Tidskriftsartikel (refereegranskat)abstract
- Assessing and predicting car type choices are important for policy analysis. Car type choice models are often based on aggregate alternatives. This is due to the fact that analysts typically do not observe choices at the detailed level that they are made. In this paper, we use registry data of all new car purchases in Sweden for two years where cars are observed by their brand, model and fuel type. However, the choices are made at a more detailed level. Hence, an aggregate (observed) alternative can correspond to several disaggregate (detailed) alternatives. We present an extensive empirical study analyzing estimation results, in-sample and out-of-sample fit as well as prediction performance of five model specifications. These models use different aggregation methods from the literature. We propose a specification of a two-level nested logit model that captures correlation between aggregate and disaggregate alternatives. The nest specific scale parameters are defined as parameterized exponential functions to keep the number of parameters reasonable. The results show that the in-sample and out-of-sample fit as well as the prediction performance differ. The best model accounts for the heterogeneity over disaggregate alternatives as well as the correlation between both disaggregate and aggregate alternatives. It outperforms the commonly used aggregation method of simply including a size measure.
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| 9. |
- Habibi, Shiva, 1978, et al.
(författare)
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Car fleet policy evaluation: The case of bonus-malus schemes in Sweden
- 2019
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Ingår i: International Journal of Sustainable Transportation. - : Informa UK Limited. - 1556-8318 .- 1556-8334. ; 13:1, s. 51-64
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we evaluate the bonus-malus schemes proposed by governmental investigation in Sweden in 2014. The objective was to reach the target of maximum 95 g/km of average emissions for new car sales by 2020. Two bonus-malus schemes along with several other policies were introduced in different scenarios as measures to reach the target. The scenarios differ in design regarding bonus-malus schemes, vehicle circulation tax, clean car premiums, company car benefits tax, and fuel tax. Both private and company car segments are targeted in these scenarios. We use a nested logit model for car type choice to predict the effects of the proposed policy scenarios on Swedish new car sales. Moreover, we introduce a methodology to predict the future of car supply. Our model results show that none of the three proposed policy scenarios is successful enough to meet the average emissions target. Furthermore, although the number of electric, plug-in hybrid, and alternative fuel cars will increase, new car sales will still be dominated by fossil-fueled cars in all scenarios. The average emissions in the scenarios containing bonus-malus schemes are not lower than that of the business-as-usual scenario. However, introducing bonus-malus schemes on its own would reduce emissions showing that interacting with other non--differentiated policies counteracts their effects. Moreover, bonus-malus schemes are predicted to give a budget surplus effect.
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| 10. |
- Habibi, Shiva, 1978, et al.
(författare)
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Carsharing
- 2021
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Ingår i: International Encyclopedia of Transportation: Volume 1-7. ; , s. 623-628
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Despite all of the benefits that have been reported from the use of carsharing services, their impacts on the transport system remain uncertain. One main reason for this uncertainty is that the modeling efforts in the area are still limited due to the lack of suitable data, and complex behavior of both supply and demand. In this chapter, methods used in the literature to model both demand and supply as well as their potential limitations are discussed, with the focus on the demand side. Carsharing will benefit from any methodological contribution to forecasting its impacts on travel demand, transport network, and land use patterns. The expected future growth of these services, and the possible integration of shared autonomous vehicles into the picture, make the need for policy-sensitive tools even more essential. These models will be useful for policymakers, city planners, and operators.
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