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  • 4551.
    Zhang, Xingxing
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Lovati, Marco
    Vigna, Ilaria
    Widén, Joakim
    Han, Mengjie
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Gál, Csilla V
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Feng, Tao
    A review of urban energy systems at building cluster level incorporating renewable-energy-source (RES) envelope solutions2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 230, s. 1034-1056Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The emergence of renewable-energy-source (RES) envelope solutions, building retrofit requirements and advanced energy technologies brought about challenges to the existing paradigm of urban energy systems. It is envisioned that the building cluster approach—that can maximize the synergies of RES harvesting, building performance, and distributed energy management—will deliver the breakthrough to these challenges. Thus, this paper aims to critically review urban energy systems at the cluster level that incorporate building integrated RES solutions. We begin with defining cluster approach and the associated boundaries. Several factors influencing energy planning at cluster scale are identified, while the most important ones are discussed in detail. The closely reviewed factors include RES envelope solutions, solar energy potential, density of buildings, energy demand, integrated cluster-scale energy systems and energy hub. The examined categories of RES envelope solutions are (i) the solar power, (ii) the solar thermal and (iii) the energy-efficient ones, out of which solar energy is the most prevalent RES. As a result, methods assessing the solar energy potentials of building envelopes are reviewed in detail. Building density and the associated energy use are also identified as key factors since they affect the type and the energy harvesting potentials of RES envelopes. Modelling techniques for building energy demand at cluster level and their coupling with complex integrated energy systems or an energy hub are reviewed in a comprehensive way. In addition, the paper discusses control and operational methods as well as related optimization algorithms for the energy hub concept. Based on the findings of the review, we put forward a matrix of recommendations for cluster-level energy system simulations aiming to maximize the direct and indirect benefits of RES envelope solutions. By reviewing key factors and modelling approaches for characterizing RES-envelope-solutions-based urban energy systems at cluster level, this paper hopes to foster the transition towards more sustainable urban energy systems.

  • 4552.
    Zhang, Xingxing
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Pan, Song
    Wu, Jinshun
    Xia, Liang
    China leans balance to distributed solar-power projects: challenge and opportunities2017Konferensbidrag (Refereegranskat)
  • 4553.
    Zhang, Xingxing
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Pan, Song
    Wu, Jinshun
    Xia, Liang
    Recycling discarded shipping containers for reliable building envelopes: a design case for senior citizens in Solar Decathlon China 20172017Konferensbidrag (Refereegranskat)
  • 4554.
    Zhang, Xingxing
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Wang, X.
    Zhao, Xiaoyun
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Solar System Design and Energy Performance Assessment Approaches2019Ingår i: Advanced Energy Efficiency Technologies for Solar Heating, Cooling and Power Generation, Springer, 2019, s. 417-451Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Recently, solar system has gained a rapid development in many countries because it is clean and sustainable. Many solar systems including the solar photovoltaic/loop-heat-pipe (PV/LHP), solar loop-heat-pipe (LHP), solar photovoltaic/micro-channel heat pipe (PV/MCHP) system, and solar thermal facade system (STF) have been designed for energy saving. To assess these systems’ performance, there are many approaches such as energy and exergy assessment which is used in this chapter to analyze their performance. Besides the system design, the authors set up dedicated experimental models in combination with computer models to test the systems’ performance. Furthermore, some systems are compared with the conventional system, and the performance of these solar systems is better than the conventional system. In addition, these solar systems are applied in many real buildings and their performance is examined, the results show that the solar systems have more potential to boost the building energy efficiency and create the possibility of solar development in buildings. © 2019, Springer Nature Switzerland AG.

  • 4555.
    Zhang, Xingxing
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Wei, Y.
    He, W.
    Qiu, Z.
    Zhao, Xiaoyun
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Solar Systems’ Economic and Environmental Performance Assessment2019Ingår i: Advanced Energy Efficiency Technologies for Solar Heating, Cooling and Power Generation / [ed] Xudong Zhao, Xiaoli Ma, Springer, 2019, s. 453-486Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The economic and environmental performance assessment of the solar system plays a critical role in building design, operation and retrofit. A dedicated economic model is necessary to assess the investment feasibility on a new technology, which allows investors to decide on a profitable investment, compare investment projects and know about the benefits of the best investment. An environmental model is adopted to predict carbon emission reduction in the solar system relative to the traditional heating and electronic systems. This chapter introduced three up-to-date solar system models and corresponding assessments related to their applications, including solar photovoltaic/loop heat pipe (PV/LHP) heat pump water heating system, loop heat pipe-based solar thermal facade (LHP-STF), heat pump water heating system as well as solar thermal facade (STF). The research results will be able to assist in decision-making in implementation of the proposed PV/T technology and analyses of the associated economic and environmental benefits, thus contributing to realization of regional and global targets on fossil fuel energy saving and environmental sustainability.

  • 4556.
    Zhang, Xingxing
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Wu, J.
    Pan, S.
    Han, Mengjie
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    An economic analysis of the solar photovoltaic/thermal (PV/T) technologies in Sweden: A case study2019Ingår i: IOP Conference Series: Materials Science and Engineering, 2019, Vol. 556, nr 1, artikel-id 012002Konferensbidrag (Refereegranskat)
  • 4557.
    Zhang, Xingxing
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Wu, J
    Zhang, Y
    Pan, S
    Wei, Y
    Xia, L
    Zhang, W
    Numerical study on thermal performance of a gravity assisted loop heat pipe2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article carried out a parametric study of the thermal performance of a novel gravity assisted loop heat pipe (GALHP)with composite mesh-screen wick structure. A refined three-way structure with interior liquid-vapour separator wasdeveloped on top of the evaporator to enable a gravity-assisted operation, which not only simplified the correspondingwick structure but also eliminated the ‘dry-out’ potential in conventional GALHPs. A dedicated simulation model wasdeveloped on basis of the heat transfer and the flow characteristics derived from the governing equations of mass, energyand momentum. The essential impact parameters to the GALHP thermal performance were further discussed. It was foundthat the GALHP thermal performance, represented by the reciprocal of overall thermal resistance, varies directly withapplied heat load, evaporator diameter, and vapour-liquid separator diameter. The research results would be useful fordesign, optimisation and application of such GALHP in the gravity-assisted circumstance for thermal management.

  • 4558.
    Zhang, Xingxing
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik.
    Xiao, M.
    He, W.
    Qiu, Z.
    Zhao, Xiaoyun
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Heat Pump Technologies and Their Applications in Solar Systems2019Ingår i: Advanced Energy Efficiency Technologies for Solar Heating, Cooling and Power Generation / [ed] Xudong Zhao, Xiaoli Ma, Springer, 2019, s. 311-339Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    As the well known that global energy demand is on a trend of continuous growth, reducing energy demand and making good use of renewable energy are thought to be the major routes toward low carbon and sustainable future, in particular for the building sector. Compared to traditional gas-fired heating systems, heat pumps have been proved to be an energy-efficient heating technology which can save fossil fuel energy and consequently reduce CO2 emission. However, the most outstanding challenges for the application of heat pumps lie in their high demand for electrical power, and the insufficient heat transfer between the heat source and the refrigerant. To overcome these difficulties, a solar-assisted heat pump has been proposed to tackle these challenges. A solar-assisted heat pump combines a heat pump with a solar collector, enabling the use of solar energy to provide space heating and hot water for buildings. This chapter introduces heat pump technologies and their applications in solar systems. Two types of solar-assisted heat pump, direct and indirect expansion, are illustrated in details. This work has provided the fundamental research and experience for developing a solar heat pump system and contributing to a significant fossil fuel saving and carbon reduction in the global extent.

  • 4559.
    Zhao, Long
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Turismvetenskap.
    Abukadirov, Kudratilla
    Högskolan Dalarna, Akademin Industri och samhälle, Turismvetenskap.
    Europe as Chinese Outbound Travel Market:: Analysing Travel Patterns of Chinese Tourists in Selecting EuropeanDestinations2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    While China has become one of the larger tourism destination regions in the recent years, allindications point to China establishing itself as the biggest tourist outbound market in the nearfuture. As such, numerous countries prepare to attract more Chinese travelers with a higherspending power in order to sustain or extend the current level of tourism related income. Forpotential European destinations, it is therefore essential to understand the travel motivations aswell as the obstacles Chinese travelers face when considering Europe as a travel destination.Therefore, the aim of this research is to contribute to the understanding of the Chinese outboundtourism market towards European destinations. This was achieved by analyzing the impacts oftravel obstacles and the push and pull factors of Chinese travelers. This analysis has been basedupon the development of the travel flows in the past 10 years, in terms of tourist numbers, and isexplained by economic, political and social factors (i.e. push and pull).The method used within this research consists of quantitative secondary data. The data isrecorded from the World Tourism Organization statistics and re-analyzed using the LocationQuotient.While in the past much of the outbound tourism was concentrated in several countries the resultsindicate that destination choices vary more and more while all countries in this study recorded anincrease in Chinese tourists. The analyzing-results also indicated that with the rise of the Chineseeconomy, the number of outbound tourists will relatively rise. Moreover, the findings indicatethat the flow of outbound tourists from China has risen, also owing to relaxation of major staterestrictions and change of intervening obstacles.After analysing the situation of tourism market [during the past decade] between Europe andChina, the authors are able to comment about the future trends. Furthermore, suggestions forfuture investigation are presented.

  • 4560.
    Zhao, Ping
    Högskolan Dalarna, Akademin Industri och samhälle, Datateknik.
    A Contour-based Separation of Vertically Attached Traffic Signs2007Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    This report presents an algorithm for locating the cut points for and separating vertically attached traffic signs in Sweden. This algorithm provides several advanced digital image processing features: binary image which represents visual object and its complex rectangle background with number one and zero respectively, improved cross correlation which shows the similarity of 2D objects and filters traffic sign candidates, simplified shape decomposition which smoothes contour of visual object iteratively in order to reduce white noises, flipping point detection which locates black noises candidates, chasm filling algorithm which eliminates black noises, determines the final cut points and separates originally attached traffic signs into individual ones. At each step, the mediate results as well as the efficiency in practice would be presented to show the advantages and disadvantages of the developed algorithm. This report concentrates on contour-based recognition of Swedish traffic signs. The general shapes cover upward triangle, downward triangle, circle, rectangle and octagon. At last, a demonstration program would be presented to show how the algorithm works in real-time environment.

  • 4561.
    Zhao, Xiaoyun
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Government vs Market in Sustainable Residential Development?: Microdata analysis of car travel, CO2 emission and residence location2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Increasing car usage and travel demands between residential locations and destinations in order to fulfill the various needs of residents is a primary cause of CO2 emissions. To win the battle against climate change, a better understanding of the question relating to which urban residential form may most effectively mitigate the CO2 emissions is the key pathway.

    This dissertation is concerned with the above problem and it mainly considers three objectives in providing insights on answering the question. The first objective is to comprehensively and microscopically understand intra-urban car travel behavior. The second objective is to estimate the induced CO2 emissions from daily intra-urban car travel and to ex-ante evaluate residential plans. The third objective is to assess whether the governmental sustainable residential development objective is aligned with the objectives of the estate market actors. To explore the research questions related to the objectives, a microdata analysis process (data collection, data assessment and transformation, data storage, data analysis and decision-making) is applied and is found essential in gaining access to key variables in exploring the answer of a preferable urban form. The dissertation offers many new solutions to various technical aspects through a microdata analysis process.

    The primary contribution of this dissertation is that it outlines an operational model that comprehensively integrates the investors’ investment strategy, the residents’ choice behavior, and the governmental sustainability objective in the interest of making an ex-ante assessment of residential plans. This ex-ante assessment provides decision-support in sustainable residential development at foremost local level.

    The first finding from the implementation of the model on the case study is that the market actors’ objectives are, in general, aligned with the government’s sustainable residential development objective. The second finding indicates that re-shaping the urban form into a compact city is preferable in mitigating CO2 emissions, in spite of the fact that the case city is of a polycentric urban form. These findings provide support for those advocating the compact city as the ideal for sustainable residential development, and also provide foresight on settling the answer to the preferred re-shaping of urban forms in climate change.

  • 4562.
    Zhao, Xiaoyun
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    On processing GPS tracking data of car-movements in Borlänge, Sweden2014Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The advancement of GPS technology enables GPS devices not only to be used as orientation and navigation tools, but also to track travelled routes. GPS tracking data provides essential information for a broad range of urban planning applications such as transportation routing and planning, traffic management and environmental control. This paper describes on processing the data that was collected by tracking the cars of 316 volunteers over a seven-week period. The detailed information is extracted. The processed data is further connected to the underlying road network by means of maps. Geographical maps are applied to check how the car-movements match the road network. The maps capture the complexity of the car-movements in the urban area. The results show that 90% of the trips on the plane match the road network within a tolerance.

  • 4563.
    Zhao, Xiaoyun
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    On processing GPS tracking data of spatiotemporal car movements: a case study2015Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The advancement of GPS technology has made it possible to use GPS devices as orientation and navigation tools, but also as tools to track spatiotemporal information. GPS tracking data can be broadly applied in location-based services, such as spatial distribution of the economy, transportation routing and planning, traffic management and environmental control. Therefore, knowledge of how to process the data from a standard GPS device is crucial for further use. Previous studies have considered various issues of the data processing at the time. This paper, however, aims to outline a general procedure for processing GPS tracking data. The procedure is illustrated step-by-step by the processing of real-world GPS data of car movements in Borlänge in the centre of Sweden.

  • 4564.
    Zhao, Xiaoyun
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    On processing GPS tracking data of spatio-temporal car movements: a case study2015Ingår i: Journal of Location Based Services, ISSN 1748-9725, Vol. 9, nr 4, s. 235-253Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The advancement of GPS technology has made it possible to use GPS devices as orientation and navigation tools, but also as tools to track spatio-temporal information. GPS tracking data can be broadly applied in location-based services, such as spatial distribution of the economy, transportation routing and planning, traffic management and environmental control. Therefore, knowledge of how to process the data from a standard GPS device is crucial for further use. Previous studies have considered various issues of the data processing at the time. This paper, however, aims to outline a general procedure for processing GPS tracking data. The procedure is illustrated step by step by the processing of real-world GPS data of car movements in Borlänge in the centre of Sweden. 

  • 4565.
    Zhao, Xiaoyun
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Road network and GPS tracking with data processing and quality assessment2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    GPS technology has been embedded into portable, low-cost electronic devices nowadays to track the movements of mobile objects. This implication has greatly impacted the transportation field by creating a novel and rich source of traffic data on the road network. Although the promise offered by GPS devices to overcome problems like underreporting, respondent fatigue, inaccuracies and other human errors in data collection is significant; the technology is still relatively new that it raises many issues for potential users. These issues tend to revolve around the following areas: reliability, data processing and the related application.

    This thesis aims to study the GPS tracking form the methodological, technical and practical aspects. It first evaluates the reliability of GPS based traffic data based on data from an experiment containing three different traffic modes (car, bike and bus) traveling along the road network. It then outline the general procedure for processing GPS tracking data and discuss related issues that are uncovered by using real-world GPS tracking data of 316 cars. Thirdly, it investigates the influence of road network density in finding optimal location for enhancing travel efficiency and decreasing travel cost.

    The results show that the geographical positioning is reliable. Velocity is slightly underestimated, whereas altitude measurements are unreliable.Post processing techniques with auxiliary information is found necessary and important when solving the inaccuracy of GPS data. The densities of the road network influence the finding of optimal locations. The influence will stabilize at a certain level and do not deteriorate when the node density is higher.

  • 4566.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Carling, Kenneth
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Dan, Zhiguang
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik. Högskolan Dalarna, Akademin Industri och samhälle, Kulturgeografi.
    Network density and the p-median solution2013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The p-medianmodel is commonly used to find optimal locations of facilities for geographically distributed demands. So far, there are few studies that have considered the importance of the road network in the model. However, Han, Håkansson, and Rebreyend (2013) examined the solutions of the p-median model with densities of the road network varying from 500 to 70,000 nodes. They found as the density went beyond some 10,000 nodes, solutions have no further improvements but gradually worsen. The aim of this study is to check their findings by using an alternative heuristic being vertex substitution, as a complement to their using simulated annealing. We reject the findings in Han et al (2013). The solutions do not further improve as the nodes exceed 10,000, but neither do the solutions deteriorate.

  • 4567.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Carling, Kenneth
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    An evaluation of the reliability of GPS-based transportation data2017Ingår i: Proceedings of IAC in Vienna 2017, 2017, s. 323-334, artikel-id IAC201711035Konferensbidrag (Refereegranskat)
    Abstract [en]

    GPS-based data are becoming a cornerstone for real-time transportation applications. Tracking data of vehicles from GPS receivers are however susceptible to measurement errors. The assessment of the reliability of data from GPS receiver is a neglected issue, especially in a real road network setting and in the phase after data transfer but before information identification. An evaluation method is outlined and carried out by conducting a randomized experiment. We assess the reliability of GPS-based transportation data on geographical position, speed, and elevation from three varied receivers GlobalSat BT-338X, Magellan SporTrak Pro and smart phone for three transportation modes: bicycle, car, and bus. The positional error ranging from 0158 meters, and 74% to 100% with an error within 5 meters depending on the transportation mode and route, there is also a non-negligible risk for aberrant positioning. Speed is slightly underestimated or overestimated with errors around 5km/h except for SporTrak Pro which had an error of -10 km/h. Elevation measurements are unreliable with errors bigger than 100 meters.

  • 4568.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Carling, Kenneth
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    An Evaluation of the Reliability of GPS-Based Transportation Data2014Rapport (Övrigt vetenskapligt)
    Abstract [en]

    GPS-based data are becoming a cornerstone for real-time transportation applications. Tracking data of vehicles from GPS receivers are however susceptible to measurement errors. The assessment of the reliability of data from GPS receiver is a neglected issue, especially in a real road network setting and in the phase after data transfer but before information identification. An evaluation method is outlined and carried out by conducting a randomized experiment. We assess the reliability of GPS-based transportation data on geographical position, speed, and elevation from three varied receivers GlobalSat BT-338X, Magellan SporTrak Pro and smart phone for three transportation modes: bicycle, car, and bus. The positional error ranging from 0158 meters, and 74% to 100% with an error within 5 meters depending on the transportation mode and route, there is also a non-negligible risk for aberrant positioning. Speed is slightly underestimated or overestimated with errors around 5km/h except for SporTrak Pro which had an error

  • 4569.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Carling, Kenneth
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    On assessing governmental sustainable residential planning and its alignment with residents’ and estate investors’ objectives2017Rapport (Övrigt vetenskapligt)
    Abstract [en]

    There are three key actors in forming the sustainable spatial distribution of residency in an area, (local) government, the estate investor and the resident, each with its own objective. Most urban planning studies have mainly focused on the ex-post evaluation of residential development by considering the objective of each actor separately. This paper outlines a conceptual model where the three key actors and their unique objectives are integrated with the aim of providing an ex-ante evaluation of residential development for government to make policies operational on a micro level. The methodology is implemented on a Swedish city, where sustainable residential development is in high need due to the influx of immigrants. The case study demonstrates that the model can integrate the macro and micro actors well. The model can provide noteworthy insights for the government on where the objectives of sustainability, livability and profit can be met. A sensitivity check of the parameter settings shows that the implementation of the model is robust for replication in other cities.

  • 4570.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Carling, Kenneth
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik. Högskolan Dalarna, Akademin Industri och samhälle, Kulturgeografi.
    Reliability of GPS based traffic data: an experimental evaluation2014Rapport (Övrigt vetenskapligt)
    Abstract [en]

    GPS tracking of mobile objects provides spatial and temporal data for a broad range of applications including traffic management and control, transportation routing and planning. Previous transport research has focused on GPS tracking data as an appealing alternative to travel diaries. Moreover, the GPS based data are gradually becoming a cornerstone for real-time traffic management. Tracking data of vehicles from GPS devices are however susceptible to measurement errors – a neglected issue in transport research. By conducting a randomized experiment, we assess the reliability of GPS based traffic data on geographical position, velocity, and altitude for three types of vehicles; bike, car, and bus. We find the geographical positioning reliable, but with an error greater than postulated by the manufacturer and a non-negligible risk for aberrant positioning. Velocity is slightly underestimated, whereas altitude measurements are unreliable.

  • 4571.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Carling, Kenneth
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Kulturgeografi. Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Residential planning, driver mobility and CO2 emission2016Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In a city there are hotspots that attract the citizens and most of the transportation in the city arises when citizens move between their residence and the hotspots. However, the evaluation between energy-efficient mobility and urban residential planning has been found to be rather weak. In this paper, we propose an ex-ante evaluation method to quantify the impacts in terms of CO2 emissions induced by intra-urban car mobility due to different residential plans implemented at various urban areas. The method is illustrated by a Swedish midsize city which is presently preoccupied with urban planning of new residential areas in response to substantial population growth due to immigration. On average, the CO2 emissions increase from the continued urban core area (CUCA) to the suburban polycentric area (SPA) to the edge urbanization area (EUA), EUA is almost 3 times more than CUCA. The average travel distances also increase in the same sequence, the overall increase is more than 4 times. Apartment buildings could be more effective in meeting residential needs and mitigating CO2 emissions than dispersed single-family houses.

  • 4572.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Carling, Kenneth
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    Residential planning, driver mobility and CO2 emission: a microscopic look at Borlänge in Sweden2017Ingår i: European Planning Studies, ISSN 0965-4313, E-ISSN 1469-5944, Vol. 25, nr 9, s. 1597-1614Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a city there are hotspots that attract citizens, and most of the transportation arises when citizens move between their residence and primary destinations (i.e. hotspots). However, an ex ante evaluation of energy-efficient mobility and urban residential planning has seldom been conducted. Therefore, this paper proposes an ex ante evaluation method to quantify the impacts, in terms of CO2 emissions induced by intra-urban car mobility, of residential plans for various urban areas. The method is illustrated in a case study of a Swedish midsize city, which is presently preoccupied with urban planning of new residential areas in response to substantial population growth due to immigration. In general, CO2 emissions increase from the continued urban core area (CUCA), to the sub-polycentric area (SPA), to the edge urbanization area (EUA), where CO2 emission of EUA is twice that of the CUCA. The average travel distances also increase in the same pattern, though the relative increase is more than four times. Apartment buildings could be more effective in meeting residential needs and mitigating CO2 emissions than dispersed single-family houses. 

  • 4573.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Rebreyend, Pascal
    Högskolan Dalarna, Akademin Industri och samhälle, Datateknik.
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik. Högskolan Dalarna, Akademin Industri och samhälle, Kulturgeografi.
    Does road network density matter in optimally locating facilities?2015Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Optimal location on the transport infrastructure is the preferable requirement for many decision making processes. Most studies have focused on evaluating performances of optimally locate p facilities by minimizing their distances to a geographically distributed demand (n) when p and n vary. The optimal locations are also sensitive to geographical context such as road network, especially when they are asymmetrically distributed in the plane. The influence of alternating road network density is however not a very well-studied problem especially when it is applied in a real world context. This paper aims to investigate how the density level of the road network affects finding optimal location by solving the specific case of p-median location problem. A denser network is found needed when a higher number of facilities are to locate. The best solution will not always be obtained in the most detailed network but in a middle density level. The solutions do not further improve or improve insignificantly as the density exceeds 12,000 nodes, some solutions even deteriorate. The hierarchy of the different densities of network can be used according to location and transportation purposes and increase the efficiency of heuristic methods. The method in this study can be applied to other location-allocation problem in transportation analysis where the road network density can be differentiated. 

  • 4574.
    Zhao, Xiaoyun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Statistik.
    Rebreyend, Pascal
    Högskolan Dalarna, Akademin Industri och samhälle, Datateknik.
    Håkansson, Johan
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik. Högskolan Dalarna, Akademin Industri och samhälle, Kulturgeografi.
    How does the complexity of a road network affect optimal facility locations?2015Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The road network is a necessary component in transportation. It facilitiesspatial movements of people and goods, and it also influences the optimal locations of facilities that usually serve as destinations of the movements. To fulfill the transportation needs and to adapt to the facility development, the road network is often organized hierarchically and asymmetrically with various road levels and spatial structures. The complexity of the road network increases along with the increase of road levels and spatial structures. However, location models locate facilities on a given road network, usually the most complex one, and the influence from the complexity of road network in finding optimal locations is not well-studied. This paper aims to investigate how the complexity of a road network affects the optimal facility locations by applying the widely-applied p-median model. The main result indicates that an increase in road network complexity, up to a certain level, can obviously improve the solution, and the complexity beyond that level does not always lead to better solutions. Furthermore, the result is not sensitive to the choice of algorithms. In a specific case study, a detailed sensitivity analysis of algorithm and facility number further provides insight into computation complexity and location problems from intra-urban to inter-urban.

  • 4575.
    Zhong, Shengtong
    Högskolan Dalarna, Akademin Industri och samhälle, Datateknik.
    The remote control of mobile robot on the Internet2007Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    During last decades, the Internet teleobotics has been growing at an enormous rate due to the rapid improvement of Internet technology. This paper presents the internet-based remote control of mobile robot. To face unpredictable Internet delays and possible connection rupture, a direct continuous control based teleoperation architecture with “Speed Limit Module” (SLM) and “Delay Approximator” (DA) is proposed. This direct continuous control architecture guarantees the path error of the robot motion is restricted within the path error tolerance of the application. Experiment results show the feasibility and effectiveness of this direct Internet control architecture in the real Internet environment.

  • 4576.
    Zhou, Nian
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH.
    Influence of grinding operations on surface integrity and chloride induced stress corrosion cracking of stainless steels2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Stainless steels were developed in the early 20th century and are used where both the mechanical properties of steels and corrosion resistance are required. There is continuous research to allow stainless steel components to be produced in a more economical way and be used in more harsh environments. A necessary component in this effort is to correlate the service performance with the production processes.

    The central theme of this thesis is the mechanical grinding process.  This is commonly used for producing stainless steel components, and results in varied surface properties that will strongly affect their service life. The influence of grinding parameters including abrasive grit size, machine power and grinding lubricant were studied for 304L austenitic stainless steel (Paper II) and 2304 duplex stainless steel (Paper I). Surface integrity was proved to vary significantly with different grinding parameters. Abrasive grit size was found to have the largest influence. Surface defects (deep grooves, smearing, adhesive/cold welding chips and indentations), a highly deformed surface layer up to a few microns in thickness and the generation of high level tensile residual stresses in the surface layer along the grinding direction were observed as the main types of damage when grinding stainless steels. A large degree of residual stress anisotropy is interpreted as being due to mechanical effects dominating over thermal effects.

    The effect of grinding on stress corrosion cracking behaviour of 304L austenitic stainless steel in a chloride environment was also investigated (Paper III). Depending on the surface conditions, the actual loading by four-point bend was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks initiation on the ground surfaces. Grinding along the loading direction was proved to increase the susceptibility to chloride-induced SCC, while grinding perpendicular to the loading direction improved SCC resistance.

    The knowledge obtained from this work can provide a reference for choosing appropriate grinding parameters when fabricating stainless steel components; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.

  • 4577.
    Zhou, Nian
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH, Yt- och korrosionsvetenskap.
    Surface integrity and corrosion behavior of stainless steels after grinding operations2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Stainless steels are widely used in applications where both the mechanical properties of steels and high corrosion resistance are required. There is continuous research to enable stainless steel components to be produced in a more economical way and be used in more harsh environments. A way to achieve this is to correlate the service performance with the production processes.

    The central theme of this thesis is surface integrity and corrosion, especially the stress corrosion cracking behavior, after grinding processes. Controlled grinding parameters, including abrasive grit size, machine power and grinding lubricant, were used and the resulting surface properties studied for austenitic 304L and duplex 2304 stainless steels. The abrasive grit size effect was found to have a larger influence. Surface defects, a highly deformed surface layer and the generation of a high level surface tensile residual stresses along the grinding direction were observed as the main types of damage. 

    The effect of grinding on stress corrosion cracking behavior of austenitic 304L, ferritic 4509 and duplex 2304 stainless steels in chloride-containing environments was also investigated.  The abrasive grit size effect on corrosion behavior for the three grades was compared. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks on the ground surface for 304L and 2304; for 4509, grinding-induced grain fragmentation was considered as the main factor for the initiation of extensive micro-pits. For duplex 2304, the microstructure and micro-notches in the as-ground surface also had significant influence. Depending on the surface conditions, the actual loading by four-point bending was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. The knowledge obtained from this work can provide guidance for choosing appropriate stainless steel grades and grinding parameters; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.

  • 4578.
    Zhou, Nian
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH.
    Lin Peng, Ru
    Linköping University.
    Pettersson, Rachel
    Jernkontoret, KTH.
    Surface characterization of austenitic stainless steel 304L after different grinding operations2017Ingår i: International Journal of Mechanical and Materials Engineering, ISSN 2198-2791, Vol. 12, nr 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: The austenitic stainless steel 304L is widely used as a structural material for which the finished surface has significant effect on the service performance. A study of the grinding process with regard to the quality of the ground surfaces is therefore interesting from the point of view of both industrial application and scientific research.

    Method: This work investigates the influence of grinding parameters including abrasive grit size, machine power, and grinding lubrication on the surface integrity of the austenitic stainless steel 304L. The induced normal grinding force, grinding surface temperature, metal removal rate, and surface property changes have been investigated and compared.

    Results and Conclusion: Using grinding, lubrication significantly enhanced the metal removal rate. Surface defects (deep grooves, smearing, adhesive chips, and indentations), a highly deformed thin surface layer up to a few microns in thickness, and high surface tensile residual stresses parallel to the grinding direction have been observed as the main damage induced by the grinding operations. Surface finish and deformation were found to be improved by using smaller abrasive grits or by using lubrication during grinding. Increasing the machine power increased surface deformation while reducing surface defects. The results obtained can provide a reference for choosing appropriate grinding parameters when machining 304L; and can also help to understand the failure mechanism of ground austenitic stainless steel components during service.

  • 4579.
    Zhou, Nian
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH.
    Lin Peng, Ru
    Linköping University.
    Pettersson, Rachel
    Jernkontoret, KTH.
    Schönning, Mikael
    Avesta Research Center - Outokumpu Stainless AB.
    Residual stress in stainless steels after surface grinding and its effect on chloride induced SCC2016Ingår i: Materials Research Proceedings: Residual Stresses 2016: ICRS-10, 2016, s. 289-294Konferensbidrag (Refereegranskat)
    Abstract [en]

    The induced residual stresses in stainless steels as a consequence of surface grinding as well as their influence on the chloride induced stress corrosion cracking (SCC) susceptibility have been investigated. Three types of materials were studied: 304L austenitic stainless steel, 4509 ferritic stainless steel and 2304 duplex stainless steel. Surface grinding using 60# and 180# grit size abrasives was performed for each material. Residual stress depth profiles were measured using X-ray diffraction. The susceptibility to stress corrosion cracking was evaluated in boiling MgCl2 according to ASTM G36. Specimens were exposed without applying any external loading to evaluate the risk for SCC caused solely by residual stresses. Induced residual stresses and corrosion behavior were compared between the austenitic, ferritic and duplex stainless steels to elucidate the role of the duplex structure. For all materials, the grinding operation generated tensile residual stresses in the surface along the grinding direction but compressive residual stresses perpendicular to the grinding direction. In the subsurface region, compressive stresses in both directions were present. Micro-cracks initiated due to high grinding-induced tensile residual stresses in the surface layer were observed in austenitic 304L and duplex 2304, but not in the ferritic 4509. The surface residual stresses decreased significantly after exposure for all specimens.

  • 4580.
    Zhou, Nian
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH.
    Lin Peng, Ru
    Linköping University.
    Schönning, Mikael
    Avesta Research Center–Outokumpu Stainlelss AB.
    Pettersson, Rachel
    Jernkontoret, KTH.
    SCC of 2304 duplex stainless steel - microstructure, residual stress and surface grinding effects2017Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 10, nr 3, artikel-id 221Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of surface grinding and microstructure on chloride induced stress corrosion cracking (SCC) behavior of 2304 duplex stainless steel has been investigated. Grinding operations were performed both parallel and perpendicular to the rolling direction of the material. SCC tests were conducted in boiling magnesium chloride according to ASTM G36; specimens were exposed both without external loading and with varied levels of four-point bend loading. Residual stresses were measured on selected specimens before and after exposure using the X-ray diffraction technique. In addition, in-situ surface stress measurements subjected to four-point bend loading were performed to evaluate the deviation between the actual applied loading and the calculated values according to ASTM G39. Micro-cracks, initiated by grinding induced surface tensile residual stresses, were observed for all the ground specimens but not on the as-delivered surfaces. Loading transverse to the rolling direction of the material increased the susceptibility to chloride induced SCC. Grinding induced tensile residual stresses and micro-notches in the as-ground surface topography were also detrimental.

  • 4581.
    Zhou, Nian
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Peng, R. L.
    Pettersson, R.
    Surface integrity of 2304 duplex stainless steel after different grinding operations2016Ingår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 229, s. 294-304Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface integrity has significant effect on service performance of a component. In this study, the evolution of the surface and sub-surface changes induced by grinding duplex stainless steel (DSS) 2304 was studied with regard to the residual stress, the microstructure, surface roughness and surface defects. The results provide insights into the effect of abrasive grit size, grinding force and lubrication on the surface integrity. The abrasive grit size was found to have the largest influence. Surface defects, a highly deformed surface layer and the generation of tensile residual stresses along the grinding direction have been found to be the main types of damage induced by the grinding operation. Residual stresses induced by mechanical effects dominate over thermal effects in this study. The results obtained can be used to understand the contribution of surface condition and residual stress on failure of duplex stainless steels in service by fatigue or stress corrosion cracking.

  • 4582.
    Zhou, Nian
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH.
    Pettersson, R.
    Schönning, M.
    Peng, R. L.
    Influence of surface grinding on corrosion behavior of ferritic stainless steels in boiling magnesium chloride solution2018Ingår i: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 69, nr 11, s. 1560-1571Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of grinding operations on surface properties and corrosion behavior of a ferritic stainless steel (FSS), EN 1.4509, has been investigated and limited comparisons also made to the grade EN 1.4622. Surface grinding was performed along the rolling direction of the material. Corrosion tests were conducted in boiling magnesium chloride solution according to ASTM G36; specimens were exposed both without external loading and under four‐point bend loading. The surface topography and cross‐section microstructure before and after exposure were investigated, and residual stresses were measured on selected specimens before and after corrosion tests using X‐ray diffraction. In addition, in situ surface stress measurements were performed to evaluate the actual surface stresses of specimens subject to four‐point bend loading according to ASTM G39. Micro‐pits showing branched morphology initiated from the highly deformed ground surface layer which contained fragmented grains, were observed for all the ground specimens but not those in the as‐delivered condition. Grain boundaries under the surface layer appeared to hinder the corrosion process. No macro‐cracking was found on any specimen after exposure even at high calculated applied loads.

  • 4583.
    Zhou, Nian
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH.
    Pettersson, Rachel
    KTH; Jernkontoret.
    Peng, Ru Lin
    Linköping universitet.
    Schonning, Mikael
    Outokumpu Stainless AB, Avesta.
    Effect of surface grinding on chloride induced SCC of 304L2016Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 658, s. 50-59Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of surface grinding on the stress corrosion cracking (SCC) behavior of 304L austenitic stainless steel in boiling magnesium chloride has been investigated. SCC tests were conducted both without external loading and with varied levels of four-point bend loading for as-delivered material and for specimens which had been ground parallel or perpendicular to the loading direction. Residual stresses due to the grinding operation were measured using the X-ray diffraction technique. In addition, surface stress measurements under applied load were performed before exposure to evaluate the deviation between actual applied loading and calculated values according to ASTM G39. Micro-cracks initiated by a high level of tensile residual stress in the surface layer were observed for all the ground specimens but not those in the as-delivered condition. Grinding along the loading direction increased the susceptibility to chloride induced SCC; while grinding perpendicular to the loading direction improved SCC resistance. Surface tensile residual stresses were largely relieved after the initiation of cracks. (C) 2016 Elsevier B.V. All rights reserved.

  • 4584. Zhu, Chaoyi
    et al.
    Gluesenkamp, Kyle R
    Yang, Zhiyao
    Blackman, Corey
    Högskolan Dalarna, Akademin Industri och samhälle, Energiteknik. SaltX Technology; Mälardalens högskola.
    Unified thermodynamic model to calculate COP of diverse sorption heat pump cycles: Adsorption, absorption, resorption, and multistep crystalline reactions2019Ingår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 99, s. 382-392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A straightforward thermodynamic model is developed in this work to analyze the efficiency limit of diverse sorption systems. A method is presented to quantify the dead thermal mass of heat exchangers Solid and liquid sorbents based on chemisorption or physical adsorption are accommodated. Four possible single-effect configurations are considered: basic absorption or adsorption (separate desorber, absorber, condenser, and evaporator); separate condenser/evaporator (two identical sorbent-containing reactors with a condenser and a separate direct expansion evaporator); combined condenser/evaporator (one salt-containing reactor with a combined condenser/evaporator module); and resorption (two sorbent-containing reactors, each with a different sorbent). The analytical model was verified against an empirical heat and mass transfer model derived from component experimental results. It was then used to evaluate and determine the optimal design for an ammoniate salt-based solid/gas sorption heat pump for a space heating application. The effects on system performance were evaluated with respect to different working pairs, dead thermal mass factors, and system operating temperatures. The effect of reactor dead mass as well as heat recovery on system performance was also studied for each configuration. Based on the analysis in this work, an ammonia resorption cycle using LiCl/NaBr as the working pair was found to be the most suitable single-effect cycle for space heating applications. The maximum cycle heating coefficient of performance for the design conditions was 1.50 with 50% heat recovery and 1.34 without heat recovery.

    Publikationen är tillgänglig i fulltext från 2020-06-30 23:36
  • 4585.
    Zhu, Fangqun
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Nationalekonomi.
    Sun, Pei
    Högskolan Dalarna, Akademin Industri och samhälle, Nationalekonomi.
    The Relationship between Transport Infrastructure and Economic Growth: An Empirical Analysis Comparing Developing and Developed Countries2009Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Gross domestic product (GDP) is generally considered as the most important index and comprehensive measure of the size of economy. This paper investigates empirically the relationship between transport infrastructure (focus on highways) and GDP growth based on a production function approach. The physical stocks of transport infrastructure were used instead of monetary data to measure public capital together with several other variables (labor and private capital) that were hypothesized to affect economic growth. Then we explore a number of subsequent studies that use panel data covering the period between 1992 and 2004. An investigation was done to compare developed countries and developing countries. Results indicate that physical units are positively and significantly related to economic growth. Furthermore there was an interesting finding that the output elasticity with respect to physical units for developed countries is higher than developing countries.

  • 4586. Zhu, H.
    et al.
    Duncan, Tara
    Högskolan Dalarna, Akademin Industri och samhälle, Turismvetenskap.
    Tucker, H.
    The issue of translation during thematic analysis in a tourism research context2019Ingår i: Current Issues in Tourism, ISSN 1368-3500, E-ISSN 1747-7603, Vol. 22, nr 4, s. 415-419Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This research note discusses issues with translation of non-English text during qualitative analysis in tourism research using examples from the newly emergent phenomenon of Chinese working holidaymakers in New Zealand. In particular, this note highlights an additional translation step in the thematic analysis process with non-English interview quotes and excerpts. This note argues the merit of researchers’ dual role as researcher/translator and discusses how researchers can undertake translation in cross-language research to maintain the rigour of qualitative tourism research. © 2017 Informa UK Limited, trading as Taylor & Francis Group

  • 4587. Zhu, Hongrui
    et al.
    Duncan, Tara
    Högskolan Dalarna, Akademin Industri och samhälle, Turismvetenskap.
    Tucker, Hazel
    Personal Changes of Young Chinese through Working Holidays in New Zealand2019Ingår i: Journal of China Tourism Research, ISSN 1938-8160, E-ISSN 1938-8179, s. 1-16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study aims to explore the personal changes of Chinese youth from their working holiday experiences in New Zealand. By drawing on semi-structured interviews, this study recruited thirty-four Chinese working holiday makers (WHMs) in New Zealand. A modified thematic analysis was adopted to analyze the interview transcriptions. Five themes have been developed, including independence, bravery, tolerance, marriage attitudes, and friends making. The findings of this study demonstrate the complexities and multi-dimensions of Chinese WHMs? personal changes during their working holiday experiences and contribute to the literature by delving into the relationship between these personal changes and the social-cultural context in which they are from. The findings also offer insightful suggestions for future studies.

  • 4588.
    Zidén, Karl
    Högskolan Dalarna, Akademin Industri och samhälle, Industriell ekonomi.
    Strategi och modell för underhållsverksamhet under avveckling: En studie av underhållsverksamheten på tunnelbanevagn modell C62014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Många industriföretag måste arbeta med att reducera sina kostnader för att överleva på

    marknaderna som blir allt hårdare. Samtidigt har medvetenheten om fördelarna med att arbeta

    för att förlänga livslängden på det som underhålls blivit det företagen arbetar mot.

    Utvecklingen och tiden leder till att introduceringar och avvecklingar genomförs men i

    dagsläget finns inga tydliga teorier och modeller för hur dessa bör genomföras i ett

    underhållsperspektiv.

    Under en period över 2017-18 ska 88 stycken tunnelbanevagnar av modell C6, vilka används i

    Stockholms tunnelbanenätverk, avvecklas. Detta beror av planerade inleveranser av en ny

    modell vilken benämns C30. Då tidigare avvecklingar genomförts har indikationer från

    inblandade getts gällande att de kunnat ske på smartare sätt. Eftersom tid finns innan

    avvecklingen påbörjas ges möjlighet till att se över hur den bör utformas. Vid utformningen

    finns tre grundpelare vilka måste beakta och de är; säkerheten, driftsäkerheten och kostnaden.

    Syftet med arbetet är dels att motivera för vilken strategi som ska väljas gällande underhållet

    under perioden. Vidare ska en avvecklingsmodell arbetas fram vilken svarar mot hur antalet

    vagnar ska reduceras. Resultatet av studien förväntas vidare vara applicerbar på nästa

    vagnsmodell samt bidra till ett generellt bidrag till det förhållande mellan avveckling och

    underhåll som idag saknar teorier och modeller.

    De undersökningar som bedrivits resulterade i att underhållsplanens rådande utformning inte

    ska frångås. Istället ska den modell som arbetats fram styra det urval som görs varje gång ett

    antal vagnar ska tas ur bruk.

    Den modell som arbetats fram testades på historiska data för att simulera en avveckling

    baserad på data fri från antaganden. Resultatet blev att en tredjedel av kostnaden under

    perioden kunde sparas, närmare 2,2 miljoner kronor.

    Viss indikation gavs gällande att driftsäkerheten genom urvalet kunde höjas. Vidare tar

    modellen hänsyn till många aspekter vilka inte alltid är lätta att värdesätta samt att den är

    anpassningsbar till de förutsättningar gällande avvecklingen som kan förändras.

  • 4589.
    Zimmergren, Anette
    Högskolan Dalarna, Akademin Industri och samhälle, Företagsekonomi.
    Hur företagsledare bidrar till kreativa tillvägagångssätt vid problemlösande för sina anställda2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Fokuset i studien ligger på det transformativa ledarskapet och chefernas möjligheter till de anställda att göra karriär och utvecklas i arbetet. Det har länge funnits bland annat två stora ledarskapstyper, transaktionellt och transformativt ledarskap. Efter att ha läst flera vetenskapliga artiklar inom området transformativt ledarskap och skapande av kreativitet, har det konstaterats att det finns begränsad empirisk forskning inom området. För att ta reda på hur empirin ser ut har intervjuer genomförts med tre transformativa chefer från tre olika företag och två av deras anställda för att se hur cheferna ger möjligheter till de anställda att göra karriär och utvecklas i arbetet. Med hjälp av intervjuerna som genomförts går det att se hur ledarskapet fungerar i praktiken och hur väl det stämmer överens med tidigare forskning.

    Resultatet i studien visar att mycket av chefernas tid går till det transaktionella ledarskapet eftersom de vill ha kontroll över vad de anställda gör. Dock är det en svår balansgång för företagen att hålla mellan att vara transaktionella och transformativa, de ska både kunna ge eget ansvar samt ha kontroll. Däremot är det en konkurrensfördel som cheferna har bland traditionella företag på konkurrensutsatta marknader då de ger utrymme till de anställda att utvecklas genom att gå på utbildningar. Detta ökar de anställdas engagemang vilket är kopplat till företagets produktivitet.

    Skulle de anställda behöva mer hjälp än den stöttning som de får, finns cheferna där och coachar dem på rätt spår igen samt att cheferna finns där ifall någon vill bolla sina idéer med dem. Cheferna försöker att skapa kreativitet bland sina anställda, både på individuella och gemensamma plan inom företagen.

    Chefernas ledarskap stämmer inte överens med alla punkter av min tolkning av det transformativa ledarskapet men de är på god väg att uppfylla dessa. Den tidigare forskningen beskriver inte exakt hur ledarskapet ska utövas utan det är mer riktlinjer.

  • 4590.
    Zivkovic, Marko
    et al.
    Stevens Institute of Technology.
    Jääskeläinen, Markku
    Högskolan Dalarna, Akademin Industri och samhälle, Fysik. Department of Physics and Engineering Physics, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA.
    Search, Christopher P.
    Stevens Institute of Technology.
    Djuric, Ivana
    Stevens Institute of Technology.
    Sagnac rotational phase shifts in a mesoscopic electron interferometer with spin-orbit interactions2008Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 77, nr 11, artikel-id 115306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Sagnac effect is an important phase coherent effect in optical and atom interferometers where rotations of the interferometer with respect to an inertial reference frame result in a shift in the interference pattern proportional to the rotation rate. Here, we analyze the Sagnac effect in a mesoscopic semiconductor electron interferometer. We include in our analysis the Rashba spin-orbit interactions in the ring. Our results indicate that spin-orbit interactions increase the rotation-induced phase shift. We discuss the potential experimental observability of the Sagnac phase shift in such mesoscopic systems.

  • 4591.
    Zou, Luyi
    Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.
    An Investigation of the LDA based Topic Model Approachfor Data Mining Twitter Social Network2015Självständigt arbete på avancerad nivå (masterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In recent years, Twitter has become a highly popular form of social media.Twitter provides a platform for users to post short messages for followers to read inan on-or off-line fashion. Twitter is used in a variety of ways, from posting aboutpersonal daily life, to keeping up to date with current events.This thesis aims to find a reliable pipeline to analyse and visualize hottest topics(or trends) that people are talking about on Twitter during a period of time. Topicmodel is used to cluster Twitter messages and identify topic words, then topic wordscombined with the tweets’ influences are graphically represented by visualizationsoftware to reflect the trend under the topic. However, two limitations of Twittermessages prevent normal topic model tools from being applied their full potentials:Twitter messages are short and and colloquial. Twitter message provides little usefulinformation for the topic model to work properly. Thus, we proposed an poolingschema to enhance the performance of a topic model on Twitter data. Meanwhile, toidentify a reliable pipeline to do the task, we compared different methodologiesduring the process. We compared performance with and without pooling schema inthe data sampling step, performance with and without TF*IDF in the data processingstep; and finally compare performance of Latent Dirichlet allocation (LDA) withCorrelated Topic Models (CTM) to identify a topic. The results show thatLDA-TF*IDF with pooling schema is the most accurate model to identify Twittertrend.

  • 4592.
    Älmeby, Anna
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Grafisk teknik.
    Fält, Olle
    Högskolan Dalarna, Akademin Industri och samhälle, Grafisk teknik.
    Ny förpackning för Renat Brännvin åt Vin & Sprit AB2001Självständigt arbete på grundnivå (kandidatexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    The purpose of this degree project is to come up with a new package to Renat Brännvin for »Vin & Sprit AB« and make the product more attractive on the market of bars, restaurants and hotels. The commission has included to decide the material of the package, whether it´s possible to manufacture the product and to make an estimation of the costs. The conditions that »Vin & Sprit AB« set up was to make the product attractive to a younger target group, in this case people from 20 to 40 years old. As Renat Brännvin is considered to be a product of first class it´s of great importance that the package reflects the look of a premium product. At first we looked at the history of the company »Vin & Sprit AB« and Renat Brännvin. We decided that the package schould consist of a bottle, glasses and a device used when serving the liquor. To get inspiration before sketching we studied different kinds of bottles, glasses and serving devices. We made a lot of different sketches to start with after which we consult with Ingrid Florén – our supervisor from »Vin & Sprit AB« – agreed on one. That one we developed and we made more accurate sketches in 3DStudioMAX. At last we looked at the opportunities to produce the bottle by questioning different manufacturers. We wanted to know the limitations to consider when making a bottle.

  • 4593.
    Åberg, Anna Cristina
    et al.
    Högskolan Dalarna, Akademin Utbildning, hälsa och samhälle, Medicinsk vetenskap. Uppsala University.
    Halvorsen, Kjartan
    Uppsala University.
    From, Ingrid
    Högskolan Dalarna, Akademin Utbildning, hälsa och samhälle, Omvårdnad.
    Bergman Bruhn, Åsa
    Högskolan Dalarna, Akademin Industri och samhälle, Arbetsvetenskap.
    Oestreicher, Lars
    Uppsala University.
    Melander-Wikman, Anita
    Luleå University of Technology.
    A study protocol for applying user participation and co-learning: lessons learned from the eBalance project2017Ingår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 14, nr 5, artikel-id 512Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The eBalance project is based on the idea that serious exergames—i.e., computer gaming systems with an interface that requires physical exertion to play—that are well adapted to users, can become a substantial part of a solution to recognized problems of insufficient engagement in fall-prevention exercise and the high levels of fall-related injuries among older people. This project is carried out as a collaboration between eight older people who have an interest in balance training and met the inclusion criteria of independence in personal activities of daily living, access to and basic knowledge of a computer, four staff working with the rehabilitation of older adults, and an interdisciplinary group of six research coordinators covering the areas of geriatric care and rehabilitation, as well as information technology and computer science. This paper describes the study protocol of the project’s initial phase which aims to develop a working partnership with potential users of fall-prevention exergames, including its conceptual underpinnings. The qualitative methodology was inspired by an ethnographical approach implying combining methods that allowed the design to evolve through the study based on the participants’ reflections. A participatory and appreciative action and reflection (PAAR) approach, accompanied by inquiries inspired by the Normalization Process Theory (NPT) was used in interactive workshops, including exergame testing, and between workshop activities. Data were collected through audio recordings, photos, and different types of written documentation. The findings provide a description of the methodology thus developed and applied. They display a methodology that can be useful for the design and development of care service and innovations for older persons where user participation is in focus.

  • 4594. Ågerfalck, P
    et al.
    Eriksson, Owen
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Usability in Social Action: Reinterpreting Effectiveness, Efficiency and Satisfaction2003Ingår i: ECIS 2003 The 11th European Conference on Information Systems, Naples, Italy, 2003Konferensbidrag (Refereegranskat)
  • 4595. Ågerfalk, P.
    et al.
    Eriksson, Owen
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Socio-instrumental usability: IT is all about social action2006Ingår i: JIT. Journal of information technology (Print), ISSN 0268-3962, E-ISSN 1466-4437, Vol. 21(1), nr MarchArtikel i tidskrift (Refereegranskat)
  • 4596. Ågerfalk, Pär J
    et al.
    Eriksson, Owen
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Action-Oriented Conceptual Modelling2004Ingår i: European Journal of Information Systems, ISSN 0960-085X, E-ISSN 1476-9344, Vol. 13, nr 1, s. 80-92Artikel i tidskrift (Refereegranskat)
  • 4597. Ågerfalk, Pär J
    et al.
    Eriksson, Owen
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Pragmatization of Conceptual Modelling2002Ingår i: Proceedings of the Xth European Conference of Information Systems, Gdansk Polen, 2002Konferensbidrag (Refereegranskat)
  • 4598.
    Ågren, Simon
    Högskolan Dalarna, Akademin Industri och samhälle, Grafisk teknik.
    Produktion av marknadsförings- och korrespondensmaterial för DUCIS2003Självständigt arbete på grundnivå (kandidatexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    The report describes the production of graphic correspondence and marketing material for DUCIS (Dalarna University Centre for Irish Studies). A logotype symbol is created on the basis of an element from the Celtic art, and a graphic material that harmonies with this ideal of style is built around the symbol. A unique visiting card, correspondence card and letterhead is produced to strengthen the identity of DUCIS outwards. The work proceeds with an international education folder which is an important element in the marketing work for the MA-education which starts in the autumn of 2003. Two posters, one for the opening of DUCIS in may 2003 and one for a conference in 2004, are produced. Finally, a redesign of the book cover for NIS, Nordic Irish Studies, is carried out. The report describes the working process consisting of meetings, practical work and other elements within the process. The conclusion is that the work has been quite successful and that this, to a large extent, depended on an engaged and supporting commissioner. The commissioner also is very satisfi ed with the results. The in-depth studies of the project is about the art and design of the Celtic culture throughout history. The text gives an account for the history and expressions of Celtic art from its birth, 2800 years ago, until its death in 13th century Ireland and Scotland. Special attention is payed to the golden age of Christian Celtic art on the british islands, the era from which the pattern of the DUCIS logotype originates.

  • 4599.
    Åhnström, Sara
    Högskolan Dalarna, Akademin Industri och samhälle, Företagsekonomi.
    Place marketing in small Swedish municipalities: A case study of Avesta municipality2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Background: Kotler et al (1999) tell that places are facing some major challenges: the globalization, the urban evolution, a growing competition of attracting scarce resources and that places have to rely on their own local resources to face the growing competition. Due to these factors it is getting harder for places to retain and attract residents, especially for smaller places. But Hospers (2011) tells that communities and cities undertake place marketing in order to fight these challenges and to be attractive for both existing and potential residents.

    Purpose: The aim of this research is to find out how small Swedish municipalities promote themselves in order to retain and attract residents.

    Method: A case study strategy with a semi-structured interview and documentary secondary data as data collection methods.

    Findings: It is beneficial for small Swedish municipalities to promote unique and realistic characteristics as they want to be identified with and to promote existing residents in promotion campaigns in order to display that the municipality value the residents. Furthermore, it is also beneficial for small Swedish municipalities to promote a well thought through place brand that builds on a set of characteristics that form a place’s brand identity. However, promotion of the place brand and unique and realistic characteristics together with the reputation of an area create images of a place. In order to create a good reputation of a place existing residents must be satisfied as they can be seen as ambassadors for the municipality and spread a good word-of-mouth to potential residents.

  • 4600.
    Åkerblom, Leif
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Eriksson, Owen
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Tourist Information Systems based on Trail Network Information2003Ingår i: ENTER2003, Helsinki, Finland, 2003Konferensbidrag (Refereegranskat)
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