| 1. |
- Claesson, Johan, 1943, et al.
(författare)
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A load-aggregation method to calculate extraction temperatures of borehole heat exchangers
- 2012
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Ingår i: ASHRAE Transactions. - 0001-2505. ; 118:1, s. 530-539
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Konferensbidrag (refereegranskat)abstract
- Hourly simulations of extraction fluid temperatures from borehole heat exchangers tend to be very time consuming. A new load aggregation scheme to perform long-term simulations of borehole heat exchangers is presented. The starting point is the step-response function for the considered borehole heat exchanger and the corresponding long sequence of cells, each with a load and a weighting factor. On the first level, the original weighting factors are kept. On the following levels, 2, 4, 8, etc., the weighting factors are lumped together. The lumped weighting factors are obtained directly from the step-response function. The number of cells to be lumped together is chosen so that the extraction temperatures using lumped weighting factors give a sufficiently good approximation of the non-aggregated scheme. The new scheme is applied to a test case to simulate extraction fluid temperature over a 20-year time period. Comparison of the results from the new scheme with the non-aggregated setting shows that the new scheme can perform very accurate and fast simulations of borehole heat exchangers.
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| 2. |
- Engström, Emelie, et al.
(författare)
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Indirect effects in evidential assessment: A case study on regression test technology adoption
- 2012
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Ingår i: 2nd International Workshop on Evidential Assessment of Software Technologies, EAST 2012. Lund, 22 September 2012. - New York, NY, USA : ACM. - 9781450315098 ; , s. 15-20
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Konferensbidrag (refereegranskat)abstract
- Background: There is a need for effcient regression testing in most software development organizations. Often the proposed solutions involve automation. However, despite this being a well researched area, research results are rarely applied in industrial practice. Aim: In this paper we aim to bridge the gap between research and practice by providing examples of how evidence-based regression testing approaches can be adopted in industry. We also discuss challenges for the research community. Method: An industrial case study was carried out to evaluate the possibility to improve regression testing at Sony Ericsson Mobile Communications. We analyse the procedure undertaken based on frameworks from the evidence based software engineering, EBSE, paradigm (with a focus on the evidence) and automation literature (with a focus on the practical effects). Results: Our results pinpoint the need for systematic approaches when introducing a new tool. Practitioners and researchers need congruent guidelines supporting the appraisal of both the evidence base and the pragmatic effects, both direct but also indirect, of the changes. This is illustrated by the introduction of the automation perspective.
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| 3. |
- Fritzsche, Joachim, 1977, et al.
(författare)
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A lipid-based passivation scheme for nanofluidics
- 2012
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Ingår i: 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012; Okinawa; Japan; 28 October 2012 through 1 November 2012. - 9780979806452 ; , s. 1876-1878
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Konferensbidrag (refereegranskat)abstract
- Stretching DNA in nanochannels allows for direct, visual studies of genomic DNA at the single molecule level. In order to facilitate the study of the interaction of linear DNA with proteins in nanochannels, we have implemented a highly effective passivation scheme based on lipid bilayers. We show long-term passivation of nanochannel surfaces to several relevant reagents and demonstrate that the performance of the lipid bilayer is significantly better compared to standard bovine serum albumin-based passivation. Moreover, we demonstrate how the passivated devices allow us to monitor single DNA cleavage events during enzymatic degradation.
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| 4. |
- Hagerhall, Caroline, et al.
(författare)
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Human eeg responses to exact and statistical fractal patterns.
- 2012
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Ingår i: Human experience in the natural and built environment: Implications for research policy & practice (Abstracts of Presentations).
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Konferensbidrag (refereegranskat)abstract
- Attention Restoration Theory point to nature as a particularly good candidate for restoring the ability to focus and inhibit distractions. However, little effort has been directed to elaborating on what makes nature's visual pattern unique for restoration purposes. One suggested explanation is the fractal properties of natural patterns (Hagerhall, 2005). Both perception studies (Hagerhall et al., 2004) and studies using quantitative electroencephalography, qEEG (Hagerhall et al., 2008) have pointed to that visual patterns with mid fractal dimension, D, seem to be the most relaxing and preferred. However, it has so far not been investigated if these responses are being driven by fractal geometry in general or by the specific form of fractal geometry found in nature. In natural scenery it is so called statistical fractals that are common because of nature's integration of randomness with the underlying fractal scaling properties. A natural fractal hence looks different from an artificial exact fractal (where the patterns repeating are identical at all scales), even if the two patterns have the same D value. We have here conducted the first study in which we consider both types of fractals and morph one type into the other.qEEG was recorded from 35 subjects viewing 9 images, combining 3 fractal dimensions and 3 levels of randomness. Each image was shown for 60 seconds, interspaced by 30 seconds of a neutral grey image. The data was mainly treated by analysis of variance (repeated measures design), including both within-group (fractal dimension, level of randomness) and between-group (order) variances. Bonferroni correction was carried out and the significance level set to p<.005. The study confirmed our hypotheses in that it showed that alpha power (an indicator of a wakefully relaxed state and internalized attention) was largest for fractals found in nature, i.e. fractals incorporating high randomness and mid to low fractal dimension. Statistically a majority of the results were tendencies (with p_.05) but the reaction patterns showed consistencies which point to that human response to the patterns, and the parameters randomness and fractal dimension, have some fundamental base. The results must be considered as preliminary, but encouraging given the relative visual simplicity of the patterns.
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| 5. |
- Huang, Zhe, 1986, et al.
(författare)
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Characterization and application of forced cooling channels for traction motors in HEVs
- 2012
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Ingår i: 2012 20th International Conference on Electrical Machines, ICEM 2012; Marseille; France; 2 September 2012 through 5 September 2012. - 9781467301428 ; , s. 1212-1218, s. 1212-1218
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Konferensbidrag (refereegranskat)abstract
- This paper presents the characterization of forced cooling channels with three different shapes which are applied in traction motors mounted in Hybrid Vehicles (HEVs) or Zero Emission Vehicles (ZEVs). Generally, there are two different positions of forced cooling channels in electric motors. One way is by drilling holes or cutting cooling channels inside the housing, which is called indirect cooling approach. The other way is to cut the cooling channels at the edges of housing or/and stator back to form direct cooling channels, where the coolant is in direct contact with the hot stator back. In both cases, choosing suitable shapes of cooling channels are necessary. In this paper, both heat transfer coefficient hf and pump power Wpump are calculated. The dimensional parameters are easily understood and also used for further thermal analysis of the completed machine by either Finite Element Analysis (FEA) or lumped parameter approaches. In addition, the dimensionless parameters Nusselt number Nu and Darcy friction factor f are evaluated with the aim to understand the characterizations for different channels. These parameters are easily used for further cooling channels optimization. In the end, the thermal analyses for a stator segment with three different shaped channels are carried on by applying the calculated results from Computational Fluid Dynamics (CFD) simulations.
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| 6. |
- Jagtap, Santosh, et al.
(författare)
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Ideation Metrics: Interdependency between Average Novelty and Variety
- 2012
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Ingår i: DS 70: Proceedings of DESIGN 2012, the 12th International Design Conference, Dubrovnik, Croatia. - 1847-9073. - 9789537738174 ; , s. 1881-1892, s. 1881-1892
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Konferensbidrag (refereegranskat)abstract
- Abstract in Undetermined The importance of ideation in the conceptual design phase has been widely accepted. Shah et al. (2003) developed four key metrics for evaluating a designer’s exploration and expansion of design space. The four metrics are: novelty, variety, quality, and quantity of designs. The mean of novelty scores of ideas in a set (i.e. Average Novelty - AN) has also been used in some ideation studies. However, many of the studies that have computed AN and variety, have not examined the interdependency between them. This research aims at examining the interdependency between AN and variety.
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| 7. |
- Javed, Saqib, 1978, et al.
(författare)
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A method to evaluate thermal response tests on groundwater-filled boreholes
- 2012
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Ingår i: ASHRAE Transactions. - 0001-2505. ; 118:1, s. 540-549
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Konferensbidrag (refereegranskat)abstract
- The design of borehole heat exchangers for ground source heat pump system applications requires thermal properties, like ground thermal conductivity and borehole thermal resistance, as inputs. These properties are often determined from an in-situ thermal response test of a pilot borehole. For groundwater-filled boreholes, the ground thermal conductivity and borehole resistance estimations are affected by the heat-injection rates used during the test. Most existing methods for evaluating thermal response tests were not originally developed to analyze tests on groundwater-filled boreholes, and these methods can sometimes give erroneous results in such situations. This paper presents a new method for the evaluation of thermal response tests on grouted and groundwater-filled boreholes. The method is based on an analytical solution, which considers the thermal capacities, thermal resistances, and thermal properties of all borehole elements. The proposed method simplifies the evaluation of thermal response tests on groundwater-filled boreholes and provides accurate estimations of ground thermal conductivity and borehole thermal resistance.
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