| 11. |
- Elgammal, Karim, et al.
(författare)
-
Density functional calculations of graphene-based humidity and carbon dioxide sensors : effect of silica and sapphire substrates
- 2017
-
Ingår i: Surface Science. - : Elsevier. - 0039-6028 .- 1879-2758. ; 663, s. 23-30
-
Tidskriftsartikel (refereegranskat)abstract
- We present dispersion-corrected density functional calculations of water and carbon dioxide molecules adsorption on graphene residing on silica and sapphire substrates. The equilibrium positions and bonding distances for the molecules are determined. Water is found to prefer the hollow site in the center of the graphene hexagon, whereas carbon dioxide prefers sites bridging carbon-carbon bonds as well as sites directly on top of carbon atoms. The energy differences between different sites are however minute - typically just a few tenths of a millielectronvolt. Overall, the molecule-graphene bonding distances are found to be in the range 3.1-3.3 (A) over circle. The carbon dioxide binding energy to graphene is found to be almost twice that of the water binding energy (around 0.17 eV compared to around 0.09 eV). The present results compare well with previous calculations, where available. Using charge density differences, we also qualitatively illustrate the effect of the different substrates and molecules on the electronic structure of the graphene sheet.
|
|
| 12. |
- Eriksson, Ola, et al.
(författare)
-
Life cycle assessment of fuels for district heating : A comparison of waste incineration, biomass- and natural gas combustion
- 2007
-
Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215 .- 1873-6777. ; 35:2, s. 1346-1362
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this consequential life cycle assessment (LCA) is to compare district heating based on waste incineration with combustion of biomass or natural gas. The study comprises two options for energy recovery (combined heat and power (CHP) or heat only), two alternatives for external, marginal electricity generation (fossil lean or intense), and two alternatives for the alternative waste management (landfill disposal or material recovery). A secondary objective was to test a combination of dynamic energy system modelling and LCA by combining the concept of complex marginal electricity production in a static, environmental systems analysis. Furthermore, we wanted to increase the methodological knowledge about how waste can be environmentally compared to other fuels in district-heat production. The results indicate that combustion of biofuel in a CHP is environmentally favourable and robust with respect to the avoided type of electricity and waste management. Waste incineration is often (but not always) the preferable choice when incineration substitutes landfill disposal of waste. It is however, never the best choice (and often the worst) when incineration substitutes recycling. A natural gas fired CHP is an alternative of interest if marginal electricity has a high fossil content. However, if the marginal electricity is mainly based on non-fossil sources, natural gas is in general worse than biofuels.
|
|
| 13. |
- Finnveden, Göran, et al.
(författare)
-
Policy instruments towards a sustainable waste management
- 2013
-
Ingår i: Sustainability. - Basel : MDPI AG. - 2071-1050. ; 5:3, s. 841-881
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to suggest and discuss policy instruments that could lead towards a more sustainable waste management. The paper is based on evaluations from a large scale multi-disciplinary Swedish research program. The evaluations focus on environmental and economic impacts as well as social acceptance. The focus is on the Swedish waste management system but the results should be relevant also for other countries. Through the assessments and lessons learned during the research program we conclude that several policy instruments can be effective and possible to implement. Particularly, we put forward the following policy instruments: “Information”; “Compulsory recycling of recyclable materials”; “Weight-based waste fee in combination with information and developed recycling systems”; “Mandatory labeling of products containing hazardous chemicals”, “Advertisements on request only and other waste minimization measures”; and “Differentiated VAT and subsidies for some services”. Compulsory recycling of recyclable materials is the policy instrument that has the largest potential for decreasing the environmental impacts with the configurations studied here. The effects of the other policy instruments studied may be more limited and they typically need to be implemented in combination in order to have more significant impacts. Furthermore, policy makers need to take into account market and international aspects when implementing new instruments. In the more long term perspective, the above set of policy instruments may also need to be complemented with more transformational policy instruments that can significantly decrease the generation of waste.
|
|
| 14. |
- Fritzin, Jonas, et al.
(författare)
-
Linearity, intermodulation distortion and ACLR in outphasing amplifiers
- 2013
-
Ingår i: 2013 IEEE MTT-S International Microwave Symposium Digest. - : IEEE conference proceedings. - 0149-645X. - 9781467361767 - 9781467321419
-
Konferensbidrag (refereegranskat)abstract
- The distortion from amplitude and phase imbalance in outphasing amplifiers is discussed. The relation between dynamic range (DR) and suppression of distortion is shown to approximately follow a simple linear relationship depending on the DR. Approximate relations between adjacent channel leakage power ratio (ACLR) for different kinds of commonly used communication signals and two-tone intermodulation distortion are given. Relations between loss in output power and reduction of DR as functions of duty cycle in switching-based outphasing amplifiers are also given. An approximate method to evaluate the possible performance of digital pre-distortion (DPD) is also given by considering a DPD capable of correcting all distortions except amplitude imbalance. The predicted performance is compared to the performance obtained using a DPD-model found in the literature. The results show that the method is in good agreement, demonstrating that the proposed method can be used for design and evaluation of predistorted outphasing amplifiers.
|
|
| 15. |
- Fäldt, Åke, 1950, et al.
(författare)
-
The gyroscopic effect and moment of inertia
- 2023
-
Ingår i: Physics Education. - : IOS Press. - 0031-9120 .- 1361-6552. ; 58:2
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes a lab to help students develop their understanding of rotational motion. The focus is on moment of inertia, which the students investigate by rolling cylinders down a ramp and determine in two different ways for a bicycle wheel. The most important and original part of the lab is the exploration of the gyroscopic effect, where measurements of precession and rotation frequencies are made using the variation of the detected magnetic field, enabling the calculation of the moment of inertia. The lab is received well by the students and can be done with relatively simple equipment easily accessible to them.
|
|
| 16. |
- Gren, Åsa, et al.
(författare)
-
How smart is smart growth? : Examining the environmental validation behind city compaction
- 2019
-
Ingår i: Ambio. - : Springer Netherlands. - 0044-7447 .- 1654-7209. ; 48:6, s. 580-589
-
Forskningsöversikt (refereegranskat)abstract
- Smart growth (SG) is widely adopted by planners and policy makers as an environmentally friendly way of building cities. In this paper, we analyze the environmental validity of the SG-approach based on a review of the scientific literature. We found a lack of proof of environmental gains, in combination with a great inconsistency in the measurements of different SG attributes. We found that a surprisingly limited number of studies have actually examined the environmental rationales behind SG, with 34% of those studies displaying negative environmental outcomes of SG. Based on the insights from the review, we propose that research within this context must first be founded in more advanced and consistent knowledge of geographic and spatial analyses. Second, it needs to a greater degree be based on a system's understanding of urban processes. Third, it needs to aim at making cities more resilient, e.g., against climate-change effects.
|
|
| 17. |
- Gunnarsson, Bengt, 1954, et al.
(författare)
-
Effects of biodiversity and environment-related attitude on perception of urban green space
- 2017
-
Ingår i: Urban Ecosystems. - : Springer Science and Business Media LLC. - 1083-8155 .- 1573-1642. ; 20:1, s. 37-49
-
Tidskriftsartikel (refereegranskat)abstract
- Green space in cities contributes to the quality of life for city dwellers, e.g., by increasing the opportunity for recreation. However, perception of urban green space is influenced by multiple factors. We investigated effects of biodiversity and environment-related attitudes on visual and auditory perceptions of urban green space. Field measurements of biodiversity were conducted in six sites across an urban gradient in Gothenburg, Sweden, and three categories of biodiversity—high, medium, low—were established. Households were sent a survey on aesthetic perception of urban green space, sound perception and the importance of trees and plants for the perception of bird species. Each respondent focused on the site that was located nearby. The environment-related attitudes comprised “Nature-oriented” and “Urban-oriented” persons and were based on participants’ own attitude estimations. It was shown that participants’ “subjective” aesthetic and sound-related perception of urban greenery were in line with the “objectively” measured subdivisions of high, medium and low biodiversity. So also were their estimations of the importance of trees and plants for perception of bird species in urban greenery, although differing only between high and medium/low biodiversity conditions. Persons rating themselves as highly nature-oriented were shown to give higher scores to urban green space aesthetics and to value greenery-related sounds higher, and to attach greater importance to trees and plants in their perception of bird species in urban greenery, than less nature-oriented persons. Highly urban-oriented persons compared to less urban-oriented persons did the same, but only regarding urban greenery-related aesthetics and sounds of nature. We conclude that environment-related attitudes influence perceptions of green space. Moreover, our findings support the idea that biodiversity per se also influences perceptions; people value green space significantly more with high than with low measured biodiversity. Urban planning needs to provide city inhabitants with green spaces that are species-rich, lush, varied and rich with natural sounds.
|
|
| 18. |
- Hedblom, Marcus, et al.
(författare)
-
Reduction of physiological stress by urban green space in a multisensory virtual experiment
- 2019
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Although stress is an increasing global health problem in cities, urban green spaces can provide health benefits. There is, however, a lack of understanding of the link between physiological mechanisms and qualities of urban green spaces. Here, we compare the effects of visual stimuli (360 degree virtual photos of an urban environment, forest, and park) to the effects of congruent olfactory stimuli (nature and city odours) and auditory stimuli (bird songs and noise) on physiological stress recovery. Participants (N = 154) were pseudo-randomised into participating in one of the three environments and subsequently exposed to stress (operationalised by skin conductance levels). The park and forest, but not the urban area, provided significant stress reduction. High pleasantness ratings of the environment were linked to low physiological stress responses for olfactory and to some extent for auditory, but not for visual stimuli. This result indicates that olfactory stimuli may be better at facilitating stress reduction than visual stimuli. Currently, urban planners prioritise visual stimuli when planning open green spaces, but urban planners should also consider multisensory qualities.
|
|
| 19. |
- Hedblom, Marcus, et al.
(författare)
-
Sounds of Nature in the City: No Evidence of Bird Song Improving Stress Recovery
- 2019
-
Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1660-4601 .- 1661-7827. ; 16:8
-
Tidskriftsartikel (refereegranskat)abstract
- Noise from city traffic is one of the most significant environmental stressors. Natural soundscapes, such as bird songs, have been suggested to potentially mitigate or mask noise. All previous studies on masking noise use self-evaluation data rather than physiological data. In this study, while respondents (n = 117) watched a 360 degrees virtual reality (VR) photograph of a park, they were exposed to different soundscapes and mild electrical shocks. The soundscapesbird song, bird song and traffic noise, and traffic noisewere played during a 10 min recovery period while their skin conductance levels were assessed as a measure of arousal/stress. No significant difference in stress recovery was found between the soundscapes although a tendency for less stress in bird song and more stress in traffic noise was noted. All three soundscapes, however, significantly reduced stress. This result could be attributed to the stress-reducing effect of the visual VR environment, to the noise levels being higher than 47 dBA (a level known to make masking ineffective), or to the respondents finding bird songs stressful. Reduction of stress in cities using masking with natural sounds requires further studies with not only larger samples but also sufficient methods to detect potential sex differences.
|
|
| 20. |
- Hilletofth, Per, et al.
(författare)
-
Coordinating new product development and supply chain management
- 2010
-
Ingår i: International Journal of Value Chain Management. - : InderScience Publishers. - 1741-5357 .- 1741-5365. ; 4:1/2, s. 170-192
-
Tidskriftsartikel (refereegranskat)abstract
- Effective implementation of the new product development (NPD) process not only enables management to coordinate the efficient flow of new products, but will also assist to support ramp-up of various supply chain activities and other related activities supporting the commercialisation of the product. Thus, companies need to address all these issues in parallel to be successful and this requires some kind of integrative product development approach. The purpose of this research is to increase the understanding of how NPD is connected to supply chain management (SCM) by investigating how the NPD process is structured and executed in two international manufacturing companies seeking to realise an innovative, predictable and efficient product development. Several essential linkages between NPD and SCM have been derived from case study findings concerning important issues for successful product development.
|
|
