| 261. |
- Lind, Hans, 1950-, et al.
(författare)
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Incitament för energieffektivisering i 60- och 70-talets bostadsbestånd
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Startpunkten för det projekt som sammanfattas i denna rapport var ett antal observationer och hypoteser. Det första konstaterandet var att den stora del av vårt bostadsbestånd som byggdes under det sk miljonprogrammet nu står inför omfattande renoveringar. Det ligger då nära tillhands att se detta som en möjlighet att samtidigt göra insatser som minskar energiförbrukningen. En andra utgångspunkt för projektet var dock att bostadsföretagen agerade väldigt olika i denna situation. Vissa gjorde stora insatser för att minska energiförbrukningen medan andra inte gjorde det. Frågan uppstod hur incitamenten egentligen såg ut för att energieffektivisera i samband med upprustningen av miljonprogramshus.Lite tillspetsat kan man säga att det fanns två konkurrerande huvudhypoteser. Den ena hypotesen sa att orsaken till att inte mer gjordes helt enkelt var att det inte var lönsamt att göra så mycket. Den andra hypotesen sa att det fanns många lönsamma åtgärder men att företagen av olika anledningar inte genomförde dem.Resultaten från studien kan sammanfattas i följande punkter:- Det finns en stor potential för energieffektivisering i bostadsbeståndet från 60- och 70-talen Även om det naturligtvis finns stora variationer beroende på hur husen fungerar idag kan det handla om besparingar på kring 30%. Många företag har redan gjort betydande insatser och fler planerar åtgärder.- Resultaten i denna studie talat enligt vår mening för att den andra hypotesen ovan: Orsaken till att inte mer görs är helt enkelt att det inte är mer som är lönsamt. Kan det vara en tillfällighet att inga privata företag i denna studie klassats som ”ambitiösa”, dvs gjort eller planerar mycket genomgripande insatser för att minska energiförbrukningen? Kan alla dessa företag ”räkna fel”? Och varför verkade de företag som gjort mest vara minst intresserade av att diskutera ekonomiska kalkyler och ekonomiska resultat? Den metod som sägs visa att många åtgärder är lönsamma – genom att man räknar med ”paket” av åtgärder innebär i praktiken att man sänker avkastningskravet på investerade medel.- När det gäller kalkylering rekommenderar vi att nuvärdesmetoden används eftersom den är tydlig och transparent så att antaganden om investeringskostnader, besparingar ochavkastningskrav blir tydliga. Det är också viktigt att skilja mellan lönsamheten hos själva åtgärden och hur det kan påverka företagets redovisade resultat. Kalkyler handlar dock inte bara om att bedöma om en åtgärd är lönsam utan också om vad som är den rätta tidpunkten för en åtgärd. Samspelet mellan tekniska åtgärder, ekonomiska incitament ochbeteende förändringar måste också tas hänsyn till i kalkylen.- Det finns incitamentsproblem när det gäller energieffektiviseringar men dessa är enligt vår mening inte så allvarliga. Genom förhandlingar mellan hyresvärd och hyresgäst kan man hantera de problem som har att göra med kallhyra/varmhyra. Ju mer kvalitetsinriktad som hyressättningen generellt blir, desto mer gynnsamt är det ur ett incitamentsperspektiv. Fjärrvärmetaxor har ofta en rörlig del som är större än marginalkostnaden vilket stärker energisparincitamenten. Om vår bedömning är korrekt, och det inte sker några stora tekniska genombrott, krävs ytterligare statliga åtgärder för att nå de långsiktiga målen.
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| 262. |
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| 263. |
- Lind, Hans, et al.
(författare)
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Sustainable Renovation Strategy in the Swedish Million Homes Programme : A Case Study
- 2016
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 8:4
-
Tidskriftsartikel (refereegranskat)abstract
- Sweden has a large multifamily housing stock that was built between 1960 and 1975. An important current issue is how this stock can be renovated in a sustainable way. The article analyses a strategy used by a suburban municipal housing company that had clear social ambitions and offered the tenants three options of renovation: Mini, Midi and Maxi. Most tenants chose the Mini alternative which meant that they could afford to stay and that there was no increase in costs for the social authorities. An investment analysis showed that the Mini alternative had a positive net present value, but that the Midi and Maxi alternatives were more profitable. Even though there was no clear environmental focus in the renovation, energy use was reduced by 8%. As a conclusion, the study shows that a sustainable renovation is possible but that there are a number of conflicts between the different dimensions of sustainability.
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| 264. |
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| 265. |
- Linde, Erik, et al.
(författare)
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Time- and Feedback-Dependent DLO Phenomena in Oxidative Polymer Aging
- 2021
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Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 189
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Tidskriftsartikel (refereegranskat)abstract
- Polymer degradation under oxidative conditions, particularly under accelerated stresses such as increased temperatures and irradiation, often exhibits spatially heterogeneous oxidation profiles. This well-known behavior is the result of diffusion-limited oxidation (DLO), which occurs when the oxidation rate is faster than the resupply of oxygen through diffusion into the material. So far most theoretical model descriptions have focused on DLO in equilibrium situations in which the underlying material properties do not change with increasing degradation levels or are constant (i.e. time-independent) variables. An extension of a previously developed finite element model is now presented, which accommodates time-dependent variables that are either explicitly time-dependent (i.e. changes homogeneously throughout the material), or through a feedback mechanism driven by the localized degree of oxidation, which results in spatial variations in the material properties responsible for specific DLO behavior. This model is realized in COMSOL Multiphysics and is capable of geometries in 1D up to 3D. Additionally, specific theoretical cases in 1D are shown which relate to known non-stationary phenomena in polymer degradation. They illustrate the effect on the resulting oxidation profile, when the oxygen diffusivity, solubility or oxidation rate properties change over time and in space. With COMSOL based FEM, it is now possible to model DLO for whatever material behavior may exist or could be envisaged.
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| 266. |
- Lindestad, Per Å, et al.
(författare)
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Voice source characteristics in mongolian throat singing studied with high-speed imaging technique, acoustic spectra, and inverse filtering
- 2001
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Ingår i: Journal of Voice. - 0892-1997 .- 1873-4588. ; 15:1, s. 78-85
-
Tidskriftsartikel (refereegranskat)abstract
- Mongolian “throat singing” can be performed in different modes. In Mongolia, the bass-type is called Kargyraa. The voice source in bass-type throat singing was studied in one male singer. The subject alternated between modal voice and the throat singing mode. Vocal fold vibrations were observed with high-speed photography, using a computerized recording system. The spectral characteristics of the sound signal were analyzed. Kymographic image data were compared to the sound signal and flow inverse filtering data from the same singer were obtained on a separate occasion. It was found that the vocal folds vibrated at the same frequency throughout both modes of singing. During throat singing the ventricular folds vibrated with complete but short closures at half the frequency of the true vocal folds, covering every second vocal fold closure. Kymographic data confirmed the findings. The spectrum contained added subharmonics compared to modal voice. In the inverse filtered signal the amplitude of every second airflow pulse was considerably lowered. The ventricular folds appeared to modulate the sound by reducing the glottal flow of every other vocal fold vibratory cycle.
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| 267. |
- Lindström, Stefan B., et al.
(författare)
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Biopolymer network geometries : Characterization, regeneration, and elastic properties
- 2010
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755 .- 1550-2376. ; 82:5, s. 051905-
-
Tidskriftsartikel (refereegranskat)abstract
- We study the geometry of biopolymer networks and effects of the geometry on bulk mechanical properties. It is shown numerically that the physical network geometry can be quantified statistically and regenerated from its statistical description, so that the regenerated network exhibits the same network mechanics as the physical network in the elastic regime. A collagen-I biopolymer network is used for validation. The method enables parametric studies of the network geometry, whose parameters are often difficult to vary independently in experiments.
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| 268. |
- Lindström, Stefan B, 1974-, et al.
(författare)
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New insights in paper forming from particle-level process simulations
- 2009
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Ingår i: Papermaking Research Symposium 2009. - Kuopio, Finland : University of Kuopio. - 9789512710164 ; , s. 38-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- By virtue of the recent developments in simulation techniques for fibre suspensions flows, it is now possible to directly simulate forming of the paper sheet at a particle level under realistic flow conditions. This opens up a window of opportunity to better understand the microscale development of the paper structure, and to attribute particular features of the structure to different drainage elements.The simulations are based on a particle-level fibre suspension model, in which fibres are represented by chains of cylindrical fibre segments. The fibre model includes curled shapes and the torsion and bending of the fibres. It also captures the two-way interactions between the fibres and the fluid phase. The fluid motion is integrated from the Navier--Stokes equations.To illustrate the usage of the simulation tool, a sample parametric study of the effects of different fibre furnishes on the paper structure and wet strength is presented. Such an investigation could almost as easily have been performed with experiments. Simulations, however, have some advantages: First, the cost is almost nothing as compared to pilot trials. Secondly, the parameters of the simulations can be controlled one at a time, whereas in pilot trials, changing one process parameter will affect the others. Thirdly, every detail of the evolving paper structure is accessible at every instant in the simulations. That is, the forming process needs no longer be considered a "black box". Simulations also have some drawbacks. For instance, it is not possible to include the smallest particles, due to their vast number, while maintaining sufficiently large flow geometry. Therefore, simulations must target paper grades of low fines contents.In this communication, the pros and cons of particle-level simulations are discussed, and put into the context of previous forming and dewatering models in the literature. The development of the paper microstructure predicted in the simulations shows that thickening is the dominant forming mechanism, while filtration only occurs in the most dilute end of the typical range of consistencies used in the industry. This predicted behaviour is compared with the conventional view of dewatering, which holds filtration as the dominant forming mechanism.
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| 269. |
- Lindström, Stefan B, Professor, 1974-, et al.
(författare)
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Pulp Particle Classification Based on Optical Fiber Analysis and Machine Learning Techniques
- 2024
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Ingår i: Fibers. - : MDPI AG. - 2079-6439. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- In the pulp and paper industry, pulp testing is typically a labor-intensive process performed on hand-made laboratory sheets. Online quality control by automated image analysis and machine learning (ML) could provide a consistent, fast and cost-efficient alternative. In this study, four different supervised ML techniques—Lasso regression, support vector machine (SVM), feed-forward neural networks (FFNN), and recurrent neural networks (RNN)—were applied to fiber data obtained from fiber suspension micrographs analyzed by two separate image analysis software. With the built-in software of a commercial fiber analyzer optimized for speed, the maximum accuracy of 81% was achieved using the FFNN algorithm with Yeo–Johnson preprocessing. With an in-house algorithm adapted for ML by an extended set of particle attributes, a maximum accuracy of 96% was achieved with Lasso regression. A parameter capturing the average intensity of the particle in the micrograph, only available from the latter software, has a particularly strong predictive capability. The high accuracy and sensitivity of the ML results indicate that such a strategy could be very useful for quality control of fiber dispersions.
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| 270. |
- Lindström, Stefan, et al.
(författare)
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Mechanosorptive creep in nanocellulose materials
- 2012
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Ingår i: Cellulose. - : Springer. - 0969-0239 .- 1572-882X. ; 19:3, s. 809-819
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Tidskriftsartikel (refereegranskat)abstract
- The creep behavior of nanocellulose films and aerogels are studied in a dynamic moisture environment, which is crucial to their performance in packaging applications. For these materials, the creep rate under cyclic humidity conditions exceeds any constant humidity creep rate within the cycling range, a phenomenon known as mechanosorptive creep. By varying the sample thickness and relative humidity ramp rate, it is shown that mechanosorptive creep is not significantly affected by the through-thickness moisture gradient. It is also shown that cellulose nanofibril aerogels with high porosity display the same accelerated creep as films. Microstructures larger than the fibril diameter thus appear to be of secondary importance to mechanosorptive creep in nanocellulose materials, suggesting that the governing mechanism is found between molecular scales and the length-scales of the fibril diameter.
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