| 4421. |
- Lennerstad, Håkan, et al.
(författare)
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Åtta IKT-projekt för matematiken i skolan : empiri och analys
- 2012
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Rapport (refereegranskat)abstract
- Denna rapport presenterar empiri och analys av en granskning av åtta projekt som mottagit medel från Skolverket för att tillämpa IKT i skolans matematikundervisning. Empirin är organiserad enligt aktivitetsteorin, vilken sätter relationerna mellan människa, miljö, aktiviteter och mål i förgrunden. Empirin som presenteras är till stor del sammanställda repliker från lärare och elever vid intervjuerna, organi¬sera¬de för att belysa verksamhetens olika relationer. Det betyder att presentationen är till stor del på de verksammas villkor, och på deras språk.Ett stort antal konkreta slutsatser framkommer ur detta material. En av dem är att klass¬upp-sätt¬ningar av datorer är sällan framgångsrika, på grund av att teknisk support ofta var otillräcklig, och att lärarna inte kan veta hur mycket eleverna använder datorerna till icke-skol-verk¬sam¬het. Dessa problem finns inte för interaktiva skrivtavlor. De framstår däremot som ett socialt verktyg, som gör utbyte och dialog om ämnet lättare att få till stånd. I flera fall framkom indirekt, men ändå tydligt, att utbildningen på tekniken hade varit otillräcklig, trots att lärarna inte uttryckte ett tydligt missnöje med den. Skrivtavlan ökade lärarnas motivation för samarbete. En framåtriktad slutsats är att en lärargrupp som har ett fungerande samarbete och goda didaktiska, ämnesmässiga, ledar- och relationella kompe¬tenser med en interaktiv skrivtavla har en möjlighet att komma längre med elevernas måluppfyllelse.
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| 4422. |
- Lenz, Luca, et al.
(författare)
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Explainable Priority Assessment of Software-Defects using Categorical Features at SAP HANA
- 2020
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Ingår i: ACM International Conference Proceeding Series. - New York, NY, USA : Association for Computing Machinery. - 9781450377317 ; , s. 366-367
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Konferensbidrag (refereegranskat)abstract
- We want to automate priority assessment of software defects. To do so we provide a tool which uses an explainability-driven framework and classical machine learning algorithms to keep the decisions transparent. Differing from other approaches we only use objective and categorical fields from the bug tracking system as features. This makes our approach lightweight and extremely fast. We perform binary classification with priority labels corresponding to deadlines. Additionally, we evaluate the tool on real data to ensure good performance in the practical use case. © 2020 ACM.
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| 4423. |
- Leon, Armando
(författare)
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Non-Linear Vibration and Dynamic Fracture Mechanics of Bridge Cables
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the present work, the non-linear vibrations and the corresponding dynamic fracture mechanics of cables of cable-stayed bridges are studied. The cables are among the most critical components in cable-stayed bridges and there are different damage sources such as corrosion, vibration, fatigue and fretting fatigue that can significantly affect them, thereby reducing the cable’s service life and even producing their failure. Cable-Parametric Resonance is the specific non-linear vibration studied in this research. This type of vibration occurs due to displacements presented at the cable supports. These displacements are induced by the wind and traffic loads acting on the pylon and deck of the bridge. Under certain conditions, unstable cable-vibration of significant amplitude can be registered. Therefore, numerical and experimental analyses are carried out in order to describe this phenomenon and to determine the corresponding instability conditions. Two non-linear models of cable-parametric resonance are studied to predict the cable response. In the simulation method, the non-linear components are treated as external forces acting on the linear systems, which are represented by Single Degree of Freedom systems and described by digital filters. A clear non-linear relationship between the excitation and the cable response is observed in the simulations and the experiments. The corresponding experimental analysis is based on a scaled model (1:200) of the Öresund bridge and a good agreement between the numerical and experimental results is found. After obtaining the relationship between the cable response and the excitation, the cable instability conditions are determined. This is done by finding the minimum displacement required at the cable supports in order to induce nonlinear cable vibration of considerable amplitude. The instability conditions are determined within a wide range of excitation frequencies and conveniently expressed in a simplified and practical way by a curve. The determination process is rather fast and offers the possibility to evaluate all bridge cable stays in a rather short time. Finally, the dynamic fracture mechanics of the cable is considered by studying the fracture toughness characteristics of the material under dynamic conditions. Finite Element simulations on a pre-cracked three-point bending specimen under impact loading are performed. The observed cable instability is equivalently considered as the associated response to impact load conditions, and a crack as a defect on the wires of a cable stay. The simulations are based on an experimental work by using the Split Hopkinson pressure bar (Jiang et al). The dynamic stress intensity factor KI(t) up to crack initiation is then obtained by different methods. The numerical estimations based on the specimen’s crack tip opening displacement (CTOD) and mid-span displacement were closest to the experimental results. It is observed that a better estimation of the dynamic stress intensity factor relies on a proper formulation of the specimen’s stiffness.
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| 4424. |
- Leon, Armando, et al.
(författare)
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On Determining Instability Conditions for Stay Cables Subjected to Parametric Resonance
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Parametric Resonance Vibration in cables of cable-stayed bridges is mainly studied when the excitation frequency is close to or twice the cable natural frequency. It is, however, important to consider other cases for this frequency relationship, since among other factors, cable-parametric resonance vibrations are strongly depending on the displacement amplitude at the cable supports. Consequently, the present research work is focused on determining, by experimental and numerical analysis, the instability conditions for stay cables subjected to parametric resonance within a wide range of frequency ratios. This is accomplished, by finding the minimum displacement required at the cable supports in order to induce non-linear vibration of considerable amplitude at the cable. Once the cable characteristics (geometry, material properties, inherent damping and initial tensile preload) are known, the instability conditions are identified and expressed in a simplified and practical way in a diagram. Numerical results are compared to those obtained by experimental analysis carried out on a simplified scaled model (1:200) of the Öresund Bridge. A good agreement between numerical and experimental results is found.
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| 4425. |
- Leon, Armando, et al.
(författare)
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Simulations and Identification of Non-Linear Models for Cables of Cable-Stayed Bridges
- 2010
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Konferensbidrag (refereegranskat)abstract
- Simulations and identification of non-linear parameters are applied on two models that describe the vibration due to parametric resonance in cables of cables-stayed bridges. The aim of this work is to study the dynamic response predicted by the two models under random excitation, as well as to develop a suitable strategy for system identification from random data. In one model the parametric excitation is treated as an arbitrary displacement introduced in one end of the cable. In the second model, such excitation is coming from an external force acting on the pylon or deck of the bridge to which the cable is coupled. The pylon or deck is modeled as a Single Degree of Freedom System. In both models the cable response is obtained by a simulation method based on digital filters. The studied identification technique is based on random excitation. In this method the non-linearity is modeled as a feedback forcing term acting on an underlying linear system or systems and the parameter estimation is performed in the frequency domain by using conventional MI/SO techniques.
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| 4426. |
- Leshob, Abderrahmane, et al.
(författare)
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A value-oriented approach to business process specialization : Principles, proof-of-concept, and validation
- 2017
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Ingår i: Journal of Systems and Software. - : Elsevier. - 0164-1212 .- 1873-1228. ; 127, s. 120-149
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Tidskriftsartikel (refereegranskat)abstract
- Organizations build information systems to support their business processes. Precise modeling of an organization's processes is a prerequisite for building information systems that support those processes. Our goal is to help business analysts produce detailed models of the business processes that best reflect the needs of their organizations. To this end, we propose to a) leverage the best practices in terms of a kernel of generic business processes, and b) provide analysts with tools to customize those processes by generating new process variants. We use business patterns from the Resource Event Agent ontology to identify variation points, and to codify the transformations inherent in the generation of the process variants. We developed a prototype process specialization tool using the Eclipse modeling ecosystem. We tested our approach on a set of processes from the Enterprise Resource Planning literature, and a set of variation points to assess the extent to which: 1) the identified variation points made sense, and 2) whether the generated variants made sense, from a business point of view. The results showed that 94.12% of the variation points made sense, and that 80.6% of the generated process variants corresponded to what the business process management specialists expected.
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| 4427. |
- Levy Franca, César, et al.
(författare)
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Exploring the Nexus of Product-Service Systems, Business Models and Sustainability - a need for strategic and practical approaches
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Product-Service Systems (PSS) have been identified as potentially important for addressing sustainability challenges. However, progress has been relatively slow as regards realizing this potential, and a lack of practical approaches to the design of business models capable of supporting implementation of such PSS has been proposed as a partial reason. The aim of this study is to explore connections and the potential functional nexus between the three fields of PSS, Business Models and Sustainability, in pursuit of possible key enablers to further realization of the potential for sustainability-promoting PSS. A systematic review and analysis of the academic literature is performed. The review shows that, although a relatively new and unexplored endeavor, there is growing effort at the interface of the three fields. The review indicates that the main deficit so far is that the PSS and business model fields lack concrete guidelines and practical tools for how to embrace the sustainability dimension in a strategic way. Especially the strategic dimension emerges as a general finding from diverse sources as a potential key enabler for mutual benefits across the three fields. The study thus points to the need for research aiming at developing such guidelines and tools, and also at exploring case-based applications to create experiential knowledge, to fill the gaps in current theory and practice.
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| 4428. |
- Levy França, César
(författare)
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Introductory Approach to Business Model Design for Strategic Sustainable Development
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The interrelated challenges of systematic degradation of ecosystems, social inequalities, financial instability and resource constraints are redefining the overall conditions for business in the twenty-first century. Addressing these challenges both demands and brings great opportunity for innovation. An important but sometimes neglected aspect of innovation is the design or redesign of business models. This has been identified as a greater source of lasting competitive advantage than new products and services per se. The majority of managers among those who say that their company´s sustainability activities have added to profits also say that these activities have led to business model changes. However, integrating business model design and sustainable innovation practices is a relatively underexplored area of research. The aim of this work is to develop an approach to business model design that supports the realization of sustainability-driven strategies. In this thesis, it is argued that a major barrier to sustainable innovation is the usual unawareness of an operational definition of sustainability and of guidelines for how an organization can support sustainable development while strengthening its own competitiveness. Therefore, a Framework for Strategic Sustainable Development (FSSD), which includes such an operational definition of sustainability and such strategic guidelines, is used as an overarching methodology for this work. Specific research methods include literature reviews, data collection, data and document analysis, explorative workshops and action research, mainly with partners in the district heating sector. To be able to design a business model that supports a sustainability-driven strategy, it is necessary to have, or to be able to develop, such a strategy. The literature review revealed that there is currently no business model design tool that in itself includes support for developing sustainability-driven strategies. However, as regards business model design as such, a tool known as the Business Model Canvas (BMC) is frequently referenced and by many seen as a kind of de-facto standard support tool for business model design. A combination of the FSSD (bringing the sustainability perspective) and the BMC (bringing the generic building blocks of business models) is therefore explored. Depending on the context it is necessary to also combine this with other methods and tools; in this work specifically with methods and tools for energy systems modeling and simulation. Both as a way to develop a combined approach and as a way to start validating it, a prototype of a handbook for sustainable innovation in the district heating sector was developed and tested iteratively. The use of early versions of this handbook preliminary indicates that the combined approach helps organizations to, e.g., self-assess their maturity in terms of strategic sustainability work, clarify strengths and weaknesses of current business models from a strategic sustainability perspective and generate of new solutions, including mutually supportive actions and business models within their wider value network.
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| 4429. |
- Lewenhagen, Kenneth, et al.
(författare)
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An Interdisciplinary Web-based Framework for Data-driven Placement Analysis of CCTV Cameras
- 2021
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Ingår i: Proceedings of the 2021 Swedish Workshop on Data Science, SweDS 2021. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665418300
-
Konferensbidrag (refereegranskat)abstract
- This paper describes work in progress of an interdisciplinary research project that focuses on the placement and analysis of public close-circuit television (CCTV) cameras using data-driven analysis of crime data. A novel web-based prototype that acts as a framework for the camera placement analysis with regards to historical crime occurrence is presented. The web-based prototype enables various analyses involving public CCTV cameras e.g., to determine suitable locations for both stationary CCTV cameras as well as temporary cameras that are moved around after a few months to address crime seasonality. The framework also opens up for other analyses, e.g. automatically highlighting crimes that are carried out closed by at least one camera. The research also investigates to what extent it is possible to generate estimates on the amount of detail captured by a camera given the distance to the crime light conditions. The research project includes interdisciplinary competences from various areas such as criminology, computer and data science as well as the Swedish Police. © 2021 IEEE.
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| 4430. |
- Li, Bing, et al.
(författare)
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Capacity of Advance Right-Turn Motorized Vehicles at Signalized Intersections for Mixed Traffic Conditions
- 2019
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Ingår i: Mathematical problems in engineering (Print). - : HINDAWI LTD. - 1024-123X .- 1563-5147.
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Tidskriftsartikel (refereegranskat)abstract
- Right-turn motorized vehicles turn right using channelized islands, which are used to improve the capacity of intersections. For ease of description, these kinds of right-turn motorized vehicles are called advance right-turn motorized vehicles (ARTMVs) in this paper. The authors analyzed four aspects of traffic conflict involving ARTMVs with other forms of traffic flow. A capacity model of ARTMVs is presented here using shockwave theory and gap acceptance theory. The proposed capacity model was validated by comparison to the results of the observations based on data collected at a single intersection with channelized islands in Kunming, the Highway Capacity Manual (HCM) model and the VISSIM simulation model. To facilitate engineering applications, the relationship describing the capacity of the ARTMVs with reference to the distance between the conflict zone and the stop line and the relationship describing the capacity of the ARTMVs with reference to the effective red time of the nonmotorized vehicles moving in the same direction were analyzed. The authors compared these results to the capacity of no advance right-turn motorized vehicles (NARTMVs). The results show that the capacity of the ARTMVs is more sensitive to the changes in the arrival rate of nonmotorized vehicles when the arrival rate of the nonmotorized vehicles is 500(veh/h)similar to 2000(veh/h) than when the arrival rate is some other value. In addition, the capacity of NARTMVs is greater than the capacity of ARTMVs when the nonmotorized vehicles have a higher arrival rate.
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