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| 2. |
- Balkur, Shrisha, et al.
(author)
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A cost and time effective novel methodology to determine specific heat capacity of lithium-ion cells
- 2021
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In: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 500
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Journal article (peer-reviewed)abstract
- A cost and time-effective novel method for determining the specific heat capacity of prismatic and pouch lithium-ion cells using a simple setup and easily available equipment is presented in this paper. Specific heat capacity is an important thermal parameter of lithium-ion cells which is not readily available or provided by the cell manufacturers. The results found in this work are compared with the calorimetrically determined values of the specific heat capacity and a maximum error of 5% and 1.4% have been found for the pouch and the prismatic cells, respectively. The minimum error in the specific heat capacity for the pouch and the prismatic cells are 0.7% and 0.1%, respectively. The thermal parameters obtained using this methodology have been used to model the surface temperature of a prismatic cell during the application of a dynamic pulsed power as well as New European Driving Cycle (NEDC) and Worldwide harmonized Light vehicles Test Cycle (WLTC) drive cycles-based power traces. The excellent matching of the measured and simulated cell's surface temperature during both the NEDC and WLTC drive cycles demonstrates that the thermal parameters determined using this new method can be used to model the surface temperature of the cell.
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| 3. |
- Bergman, Becky, 1970, et al.
(author)
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Reflections on an Integrated Content and Language Project-Based Design of a Technical Communication Course for Electrical Engineering Students.
- 2013
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In: Journal of Academic Writing. - 2225-8973. ; 3:1, s. 1-14
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Journal article (peer-reviewed)abstract
- Effective ways of teaching technical communication skills to engineering students have been much discussed. This article reflects on one setting, a first year course in Technical Communication at a university in Sweden, where electrical engineering teachers, language and communication teachers and student counsellors work in close, team-based cooperation using a project model which requires the students to analyse, implement and communicate technical problems. The paper discusses the change in this course - from an EAP course primarily prioritizing language training which ran parallel with a project course - to one unified ICL course. The progression is described through the changes in the organization of the course, and the article focuses on one learning activity: interdisciplinary tutorials on project reports. Through a pilot study where these sessions were video recorded and mapped, we conclude that the presence of different roles became an asset for the range of what the students see as relevant for their project report. In particular, the technical report genre was critically analysed, including problematic areas such as textual sequencing and display of technical problems; data visualisation and commentary; and referencing.
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| 5. |
- Doughty, Tyler, 1987, et al.
(author)
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Stress-induced expression is enriched for evolutionarily young genes in diverse budding yeasts
- 2020
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 11:1
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Journal article (peer-reviewed)abstract
- The Saccharomycotina subphylum (budding yeasts) spans 400 million years of evolution and includes species that thrive in diverse environments. To study niche-adaptation, we identify changes in gene expression in three divergent yeasts grown in the presence of various stressors. Duplicated and non-conserved genes are significantly more likely to respond to stress than genes that are conserved as single-copy orthologs. Next, we develop a sorting method that considers evolutionary origin and duplication timing to assign an evolutionary age to each gene. Subsequent analysis reveals that genes that emerged in recent evolutionary time are enriched amongst stress-responsive genes for each species. This gene expression pattern suggests that budding yeasts share a stress adaptation mechanism, whereby selective pressure leads to functionalization of young genes to improve growth in adverse conditions. Further characterization of young genes from species that thrive in harsh environments can inform the design of more robust strains for biotechnology.
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| 6. |
- Engel, Robin Y., et al.
(author)
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Electron population dynamics in resonant non-linear x-ray absorption in nickel at a free-electron laser
- 2023
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In: Structural Dynamics. - : American Institute of Physics (AIP). - 2329-7778. ; 10:5
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Journal article (peer-reviewed)abstract
- Free-electron lasers provide bright, ultrashort, and monochromatic x-ray pulses, enabling novel spectroscopic measurements not only with femtosecond temporal resolution: The high fluence of their x-ray pulses can also easily enter the regime of the non-linear x-ray-matter interaction. Entering this regime necessitates a rigorous analysis and reliable prediction of the relevant non-linear processes for future experiment designs. Here, we show non-linear changes in the L-3-edge absorption of metallic nickel thin films, measured with fluences up to 60 J/cm(2). We present a simple but predictive rate model that quantitatively describes spectral changes based on the evolution of electronic populations within the pulse duration. Despite its simplicity, the model reaches good agreement with experimental results over more than three orders of magnitude in fluence, while providing a straightforward understanding of the interplay of physical processes driving the non-linear changes. Our findings provide important insights for the design and evaluation of future high-fluence free-electron laser experiments and contribute to the understanding of non-linear electron dynamics in x-ray absorption processes in solids at the femtosecond timescale.
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| 7. |
- Geng, Zeyang, 1991, et al.
(author)
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A Time- and Cost-Effective Method for Entropic Coefficient Determination of a Large Commercial Battery Cell
- 2020
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In: IEEE Transactions on Transportation Electrification. - 2332-7782. ; 6:1, s. 257-266
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Journal article (peer-reviewed)abstract
- The entropic coefficient of a lithium-ion battery cell is used to calculate the reversible heat of a battery during operation, which is a nonnegligible part of the battery thermal modeling. The contribution of this article is to propose a novel method to establish the entropic coefficient profile of a 26-Ah commercial pouch cell and compare the results with those obtained from the traditional potentiometric and calorimetric methods, and all are found to be in a good agreement. The originality of this article is to use a method, which consists of supplying a square pulse current waveform at a certain frequency, and thus, the resulting heat variation could be successfully linked to the input current using Fourier analysis. The current magnitudes used were 1 and 1.5 C, which are representative of the normal operation current in an electrified vehicle application. The method proposed is found to be cost efficient with a short experiment time and simple experiment setup. In fact, it can be used to characterize cells that are already mounted in a pack without access to a climate chamber or calorimeter.
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| 8. |
- Geng, Zeyang, 1991, et al.
(author)
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On-board Impedance Diagnostics Method of Li-ion Traction Batteries Using Pseudo-Random Binary Sequences
- 2018
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In: 2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe.
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Conference paper (peer-reviewed)abstract
- This work deals with the on-board impedance measurements of Li-ion batteries on hybrid electric vehicles/electric vehicles by using pseudo-random binary sequences (PRBSs). The impedance of the battery can be related to its state of charge (SOC) and state of health (SOH). However the battery impedance is frequency dependent which makes it difficult to perform the measurement on a pack level in the vehicles. By using an excitation signal like PRBS, it is possible to extract the impedance information of the battery packs. Experiments are performed with different set-ups to verify the PRBS method. A non-parametric method is used to process the data and extract the impedance measurement. Experiments in the laboratory at different state of charge levels and temperatures are made to validate the PRBS method. It is shown that the PRBS method can produce a valid electrochemical impedance spectrum in a limited frequency range, similar to the result from a high accuracy laboratory impedance analyzer. The method is stable at different SOC levels and temperatures. A simulation of the excitation signal in the vehicle is performed where the electric motor is used as the load. It shows that it is possible to some extent to use the driveline in a hybrid electric vehicle/electric vehicle to perform an on-board battery impedance measurement.
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| 9. |
- Groot, Jens, 1980
(author)
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Battery Benchmarking and Cyclelife Test Methods
- 2010
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In: Transport Research Arena Europe 2010, Brussels, 2010-06-07...2010-06-10.
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Conference paper (peer-reviewed)abstract
- The energy storage in an HEV powertrain is probably the most critical component regarding total cost, reliability and performance. Hence, substantial and fundamental knowledge about battery performance, battery lifetime and system design is vital for the outcome of the hybridisation of vehicles for road transport. In particular, the hybridisation of heavy-duty vehicles faces severe challenges with first and foremost cost and accurate estimation of cyclelife and dynamic performance. This paper presents new test methods for energy storage benchmarking and cyclelife testing. The method is developed to address critical performance measures for HEVs such as peak power, energy and efficiency. To evaluate the method a limited series of laboratory tests of a Li-ion cell is performed. A short comparison to test results from standardised test methods is also included to highlight different aspects of the subject.In addition, issues and methods related to load cycle development for cyclelife is discussed. In particular, the use of synthetic load cycles extracted from measured battery usage is evaluated by comparing test results from ongoing cyclelife tests.
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| 10. |
- Groot, Jens, 1980, et al.
(author)
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Energy storage system optimisation of a plug-in HEV
- 2008
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In: International Journal of Electric and Hybrid Vehicles. - 1751-4088. ; 1:3, s. 319-331
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Journal article (peer-reviewed)abstract
- This paper deals with the optimisation of the energy storage system of a parallel hybrid plug-in car. The objective is to study how the electric driving range is influenced by factors such as package volume and auxiliary power consumption. Simulation and optimisation are used to find the most cost effective battery arrangement for specified electric driving range, volume, power and lifetime requirements. Two battery technologies, NiMH and Li-ion, are included in the simplified case study. The result indicates that the battery cost and size are highly dependent on the required electric driving range. It is found that a 3±5km electric driving range is possible with a minor cost increase. An electric driving range of 15±25km is possible, but results in a more bulky, and much more costly, battery system. It is important to point out that the results are not general. The electric driving range can be significantly extended by decreasing the roll and/or the air resistance.
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