| 1. |
- Andersson, Patrik, 1974, et al.
(författare)
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Framtidsbilder för samhällsbyggnad
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Framtidsbilder för samhällsbyggnad 2020De kommande 15 åren står institutionen för Bygg- och miljöteknik inför stora förändringar. Därför har institutionen initierat projektet Framtidsbilder 2020 där man engagerat en framtidspanel bestående av elva yngre disputerade forskare. Arbetet inleddes med ett breddgruppsmöte där 110 personer representerande institutionens personal och studenter deltog. Vid mötet identifierades ett antal trender och osäkra utvecklingar som påverkar framtiden inom samhällsbyggnadsområdet. Deltagarna bidrog också med idéer till en önskvärd utveckling, vilket har sammanställts och utgör grunden till en gemensam önskvärd framtid/vision för institutionen. Materialet från breddgruppsmötet har bearbetats av Framtidspanelen och resulterat i fyra scenarier som beskriver hur samhällsbyggnadsområdet kan se ut år 2020. Syftet med framtidsbilderna är att de ska vara vägledande för institutionens beslut och förhållningssätt under de kommande åren.Fyra scenarierTurning TorsoSamhället präglas av en ekonomi som är på uppgång, och av ett nytänkande och öppet samhälle. Materiell status och individualism är viktigt. Detta leder till en hög arbetsbelastning samt krav på exklusiva varor av hög kvali-tet. Det finns en stor medvetenhet om miljöpåverkan och klimatförändringar och lösningarna för att klara energiförsörjningen är innovativa.Eco-metropolenDet sveper en grön våg genom dagens samhälle. Under de senaste 15 åren har vi insett att jorden skall vara en bebolig plats även åt dem som kommer efter oss. Vi söker ständigt efter nya, mer förfinade metoder att tillvarata de resurser vi har. Samhället och individen är i balans. Ekonomin är god och vi är miljömedvetna, trygga och integrerade. Nytänkande premieras och icke- materialistiska värderingar står högt i kurs. Vi tänker individuellt, men agerar mer än gärna för kollektivets bästa. Utbildning är gratis TrädgårdsstadenEtt samhälle där vi lärt oss hantera stress, men känner oss otrygga och helst umgås i slutna sociala sammanhang. Vi bor enkelt inne i stan, eller gärna på landsbygden nära storstäderna. Minskade behov av högutbildade i samhället gör att vi har svårt att rekrytera studenter till teknikutbildningar. Det traditionella tankesättet leder till kulturkrockar med företag och personer från andra länder.Gated communitiesFörsämrad ekonomi och ökad egoism har lett fram till ett stressat, otryggt och segregerat samhälle. Accelererande klimatförändringar och ökad miljö-påverkan skrämmer oss, men trots det åtgärdar vi inte problemen, utan koncentrerar oss på konsekvenserna. Arbetslöshet i samhällsbyggnadssek-torn leder till sänkt status för samhällsbyggaren. Vi har därför svårt att rekrytera studenter, och även forskningen har låg status.
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| 2. |
- Ahrens, Jens, 1978, et al.
(författare)
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Tutorial on scaling of the discrete fourier transform and the implied physical units of the spectra of time-discrete signals
- 2020
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Ingår i: 148th Audio Engineering Society International Convention.
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Konferensbidrag (refereegranskat)abstract
- The combination of the time-discrete property of digital signals together with the commonly employed definition of the discrete Fourier transform (DFT) can cause ambiguity when interpreting magnitude spectra with respect to the physical unit of the signal under consideration. Standardized scaling of spectra increases the comparability of frequency-domain data that are published in scientific articles or data sheets of commercial products. We present and discuss in this tutorial a collection of the most relevant scaling options for DFT spectra to yield amplitude spectra, power spectra, and power density spectra, and we illustrate how an implied physical unit of the underlying signal is reflected by the magnitude of the spectrum. The tutorial is accompanied by Matlab/Octave scripts that demonstrate the different cases.
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| 3. |
- Almefelt, Lars, 1968, et al.
(författare)
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Exploring Requirements Management in the Automotive Industry
- 2003
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Ingår i: 14th International Conference on Engineering Design Research for Practice - innovative products, processes and organisations.
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Konferensbidrag (refereegranskat)abstract
- This paper presents an empirical study carried out in the automotive industry, with the aim to bring forward new experiences and knowledge on management of requirements in practice. Adopting a qualitative systems approach, and using multiple information sources, the requirements management process during the development of a passenger car cockpit has been mapped out. The logical reconstruction of the requirements management process is complemented with descriptions of associated phenomena, such as important events and attitudes. Findings are presented, analysed and discussed considering also factors underlying observed phenomena.
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| 4. |
- Andersson, Fredrik, 1974, et al.
(författare)
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Computer Based Requirements and Concept Modelling - Information Gathering and Classification
- 2000
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Ingår i: 12th International Conference on Design Theory and Methodology. 2000 ASME International Design Engineering Technical Conferences.
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a requirement and concept model based on a functional decomposition of mechanical systems. It is an object-oriented approach to integrate the representation of the design artefact and the design activity, through the decisions made during the design evolution. The requirements co-evolve simultaneously with the formation of the conceptual layout, through the opportunity to alter between function and physical/abstract solutions. This approach structures the design requirements and concepts in such a way that it supports the ability to document their sources, to allow for validation and verifications of both requirements and design solutions. First, the proposed model is presented from a theoretical viewpoint. Secondly, a methodology for modelling requirements and concepts in an object-oriented fashion is discussed. Finally, the model is implemented in METIS software and tested in a case study of an electric window winder on a truck door.
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| 5. |
- Andersson, Martin, 1974, et al.
(författare)
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Vesicle and bilayer formation of diphytanoylphosphatidylcholine (DPhPC) and diphytanoylphosphatidylethanolamine (DPhPE) mixtures and their bilayers' electrical stability
- 2011
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 82:2, s. 550-561
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Tidskriftsartikel (refereegranskat)abstract
- Lipid bilayers are of interest in applications where a cell membrane mimicking environment is desired. The performance of the lipid bilayer is largely dependent on the physical and chemical properties of the component lipids. Lipid bilayers consisting of phytanoyl lipids have proven to be appropriate choices since they exhibit high mechanical and chemical stability. In addition, such bilayers have high electrical resistances. Two different phytanoyl lipids, 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) and 1,2-diphytanoyl-sn-glycero-3-phosphoethanolamine(DPhPE), and various combinations of the two have been investigated with respect to their behavior in aqueous solutions, their interactions with solid surfaces, and their electrical stability. Dynamic light scattering, nuclear magnetic resonance diffusion, and cryogenic transmission electron microscopy measurements showed that pure DPhPC as well as mixtures of DPhPC and DPhPE consisting of greater than 50% (mol%) DPhPC formed unilamellar vesicles. If the total lipid concentration was greater than 0.15 g/l, then the vesicles formed solid-supported bilayers on plasma-treated gold and silica surfaces by the process of spontaneous vesicle adsorption and rupture, as determined by quartz crystal microbalance with dissipation monitoring and atomic force microscopy. The solid-supported bilayers exhibited a high degree of viscoelasticity, probably an effect of relatively high amounts of imbibed water or incomplete vesicle fusion. Lipid compositions consisting of greater than 50% DPhPE formed small flower-like vesicular structures along with discrete liquid crystalline structures, as evidenced by cryogenic transmission electron microscopy. Furthermore, electrophysiology measurements were performed on bilayers using the tip-dip methodology and the bilayers' capacity to retain its electrical resistance towards an applied potential across the bilayer was evaluated as a function of lipid composition. It was shown that the lipid ratio significantly affected the bilayer's electrical stability, with pure DPhPE having the highest stability followed by 3DPhPC:7DPhPE and 7DPhPC:3DPhPE in decreasing order. The bilayer consisting of 5DPhPC:5DPhPE had the lowest stability towards the applied electrical potential.
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| 6. |
- Andersson, Patrik, 1974
(författare)
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A contact model for predicting adherence force and noise generation in the tyre / road contact
- 2005
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Ingår i: Proceedings of NOVEM (Noise and Vibration: Emerging Methods), Saint-Raphaël, France.
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Konferensbidrag (refereegranskat)abstract
- Adhesion forces influence the automotive tyre / road surface contact for certain tyre / road combinations, leading to enhanced rolling resistance, tyre vibrations, and noise excitation. A model was developed to predict the contact force and noise generation for hastily separation of two macroscopic objects. The model is formulated in the time domain for two elastic bodies in non-linear dynamic contact. The contact area is spatially discretised in contact points and the dynamic response is calculated convolving the contact forces with pre-calculated impulse responses of the interacting objects. The adhesion forces are included allowing negative forces through the contacts, which break at a given condition; at a critical force in its simplest form. Parameters on a micro-scale influencing this condition are discussed. Time records of contact forces and sound pressures as samples of tyre tread are hastily separated from road surfaces samples were acquired. A qualitative comparison between calculated and measured data demonstrates the feasibility of the model.
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| 7. |
- Andersson, Patrik, 1974, et al.
(författare)
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A Method for Experimental Collection of Global Material Data for Tyres
- 2001
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Ingår i: Nordic Vibration Research 2001, Stockholm, Sweden (The Scandianvian Vibration Society, www.svib.se).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- For the modelling of the dynamic behaviour of tyres material data are required. Depending on the character of the model these will have different quality. Modelling with global structures such as beams or plates, representative data for the global bending stiffness, global mass etc. are needed. These data do not represent the details of the tyre structure but the combined properties of the structure. Therefore it is not possible to cut out samples of the tyre and determine the global material properties by measurements on these samples. Consequently it is necessary to estimate the material parameter by measurements carried out on the complete tyre. Results from such measurements will be related to the model used for the tyre (e.g. ring model, orthotropic plate, etc.). The material data obtained in such way are consequently a function of both the tyre structure and the model, which is used to update the data. A method for experimental collection of global material data for tyres has been developed. This method is based on the experimental characterisation of tyres by driving point and transfer mobilities and the use of the orthotropic plate tyre model for updating the material data.
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| 8. |
- Andersson, Patrik, 1974, et al.
(författare)
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A study of forces and noise generation in a contact including adhesive bonds
- 2004
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Ingår i: Nordic Vibration Research 2004, June 3-4, (The Scandinavian Vibration Society, www.svib.se).
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Konferensbidrag (refereegranskat)abstract
- Paper to be published.Adhesive forces are present in the contact between a road surface and a rolling tyre. Theses forces may add up to substantial adherence forces, causing stick-snap excitation of tread blocks, high frequency noise generation, and increased rolling resistance. An experimental setup was designed to study the process when a tyre tread block sample was pressed onto a road surface sample, and hastily removed. Time variation of contact forces and sound pressure were measured. The same situation was modelled using a time domain model of two elastic bodies in non-linear dynamic contact. The contact area is spatially discretised in contact points and the contact problem is solved using an elastic half-space. The response of the block is calculated by convoluting the forces with pre-calculated impulse responses of the same block, which is modelled as a mass-spring system. The adhesive bounds are included by allowing negative contact forces; the contact at a point breaks when the calculated contact force reaches a specified negative value. Typical results from the experimental setup and the model are presented. It is concluded that the experimental setup is suitable for investigating the detachment process of the tread block and that the model is able to qualitatively capture the contact force and noise generation.
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| 9. |
- Andersson, Patrik, 1974
(författare)
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Boundary element formulation using modified Green's functions for media with random distribution of scattering objects
- 2009
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Ingår i: Proceedings of NOVEM 2009 Noise and Vibration: Emerging Methods, Oxford, UK.
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Konferensbidrag (refereegranskat)abstract
- The engine bay of an automotive vehicle is a partly open enclosure that is densely filled with numerous objects such as accessory parts, pipes, tubes, and cables. These objects cause scattering of the sound waves inside the engine bay, which leads to an increased absorption of sound power compared to an enclosure without objects. However, it is time-consuming to include all the details of the geometry and acoustical properties of the objects in numerical simulations, predicting the sound power radiated to the exterior. This paper presents how a deterministic boundary element model and a statistical intensity/power model can be combined to give an approximate description of the sound field for cases with randomly distributed scatterers. The boundary element formulation describes the coherent part of the wave field by using modified Green's functions that include the average effect of the scattering objects. The waves scattered at the objects are assumed to result in an incoherent field that is described by an intensity model. The modelling approach is evaluated by calculating the power radiated from a partly open enclosure in a two-dimensional geometry. The results are convincing and it is concluded that the approach is suitable.
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| 10. |
- Andersson, Patrik, 1974, et al.
(författare)
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Boundary Element Method for Intensity Potential Approach : Predicting the Radiated Sound Power from Partially Enclosed Noise Sources
- 2012
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Ingår i: Acta Acoustica united with Acustica. - : S. Hirzel Verlag. - 1610-1928 .- 1861-9959. ; 98:4, s. 588-599
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes the boundary element method for the intensity potential for prediction of high-frequency sound power flow through partial enclosures. The intensity potential approach is based on the local power balance in a lossless medium and the Helmholtz decomposition of the vector field of time-averaged sound intensity. The result is a Poisson equation for a scalar intensity potential. The intensity potential formulation and the boundary element method are both suitable for exterior problems. The governing equations of the intensity potential and the boundary element method for solving this problem are presented. Results from the proposed method are compared with experimental results, for the case of radiated sound power in one-third-octave bands from sources in a partial enclosure. The results show that the method is applicable for estimation of global radiated sound power in one-third-octave bands in the high-frequency range.
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