| 1. |
- Pettersson, Pär, 1985, et al.
(author)
-
A proposal for an operating cycle description format for road transport missions
- 2018
-
In: European Transport Research Review. - : Springer Science and Business Media LLC. - 1867-0717 .- 1866-8887. ; 10:2
-
Journal article (peer-reviewed)abstract
- Purpose: This article presents a proposal for an operating cycle format for describing transport missions of road vehicles, for example a logging truck fetching its cargo. The primary application is in dynamic simulation models for evaluation of energy consumption and other costs of transportation. When applied to product development, the objective is an ensemble of components and functions optimised for specific tasks and environments. When applied to selection of vehicle configuration, the objective is a vehicle specification tailored for its task. Method: The proposal is presented and its four main parts: road, weather, traffic and mission, are thoroughly explained. Furthermore, we implement the proposal in an example of a dynamic forward simulation model. Results: The example model is used for two case studies: a synthetic example of a complex transport mission (a logging truck fetching its cargo) that shows some advanced format features, and an example from a real vehicle log file (cargo transport) that seeks to compare the resulting simulated speed profile to the measured one. Conclusion: The results show that the proposed format works in practice. It can represent complex transport missions and it can be used to reproduce the main features of a logged speed profile even when combined with simple driver and vehicle models.
|
|
| 2. |
- Pettersson, Pär, 1985, et al.
(author)
-
A statistical operating cycle description for prediction of road vehicles’ energy consumption
- 2019
-
In: Transportation Research Part D. - : Elsevier Ltd. - 1361-9209 .- 1879-2340. ; 73, s. 205-229
-
Journal article (peer-reviewed)abstract
- We propose a novel statistical description of the physical properties of road transport operations by using stochastic models arranged in a hierarchical structure. The description includes speed signs, stops, speed bumps, curvature, topography, road roughness and ground type, with a road type introduced at the top of the hierarchy to group characteristics that are often connected. Methods are described how to generate data on a form (the operating cycle format) that can be used in dynamic simulations to estimate energy usage and CO2 emissions. To showcase the behaviour of the description, two examples are presented using a modular vehicle model for a heavy-duty truck: a sensitivity study on impacts from changes in the environment, and a comparison study on a real goods transport operation with respect to energy usage. It is found that the stop intensity and topography amplitude have the greatest impact in the sensitivity study (8.3% and 9.5% respectively), and the comparison study implies that the statistical description is capable of capturing properties of the road that are significant for vehicular energy usage. Moreover, it is discussed how the statistical description can be used in a vehicle design process, and how the mean CO2 emissions and its variation can be estimated for a vehicle specification.
|
|
| 3. |
- Pettersson, Pär, 1985, et al.
(author)
-
Influence of hill-length on energy consumption for hybridized heavy transports in long-haul transports
- 2016
-
In: 7th Commercial Vehicle Workshop Graz, 20160513, Graz.
-
Conference paper (peer-reviewed)abstract
- Goods transports are big producers of CO2, i.e. consumers of energy. The conventional transport vehicles such as tractor-semitrailers can be replaced by long combination vehicles (LCVs). By doing so, fuel consumption will be reduced drastically, with up to 30%, mainly thanks to the reduced aerodynamic resistance per pay load mass and/or volume. Further reduction of CO2 improvements can be made by hybridization, if the road topography demands variable propulsion power due to up- and downhills. This gain is emphasized for heavier vehicles. So, hybridized LCVs are of special interest.When developing vehicles, or selecting vehicle for a certain transport, one needs to assume an operating cycle. To describe the operating cycle correctly is very important for this purpose. Traditionally, the magnitude of road grades is the only topography measure used to characterise the road. In this paper it is studied how an additional measure, hill length, influences these heavy hybridized LCVs. Together one can see these two measures as amplitude and wavelength.It is shown how energy saving varies for different types of roads (combinations of grade magnitude and hill-length) and different energy buffer sizes. Road topography is statistically generated for a good coverage of road types, but also examples of real roads are marked within these synthetic roads. The result can be combined with estimates of hybridization costs and conclusions can be drawn when it is beneficial to hybridize and with how large buffer. The main takeaways from the paper are that the potential energy savings for heavy LVCs due to hybridization are significant and that the hill-length is an important characteristic measure to include in operating cycle definitions.
|
|
| 4. |
- Pettersson, Pär, 1985, et al.
(author)
-
Intrinsic differences between backward and forward vehicle simulation models
- 2020
-
In: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 2405-8963.
-
Conference paper (peer-reviewed)abstract
- Two common methods for predicting the energy usage in vehicles through mathematical simulation, the `backward' and the `forward' schemes, are discussed and compared in terms of what longitudinal vehicle behaviour they predict. In the backward scheme, the input driving cycle is initially assumed to be followed perfectly and therefore the vehicle speed is not a dynamic state. In the forward scheme, a driver model controls the vehicle in an attempt to follow the input driving cycle, and the vehicle speed is intrinsically a dynamic state. A theoretical study is made with a simple mathematical vehicle model, where it is shown that the two methods neither predict the same expected energy use nor energy variation. Next, the simulation model that is used for the CO2 rating of heavy-duty trucks in Europe, VECTO, is used as an example of the backward method, and an equivalent implementation in a forward scheme is attempted. Two numerical experiments are made with these models: a detailed study of the longitudinal vehicle behaviour on a reference mission; and a study of the predicted CO2 emissions on a family of stochastically generated missions. The conclusion is that the backward method is easier to use but the forward method has a greater potential to predict realistic behaviour.
|
|
| 5. |
- Belov, Ilja, et al.
(author)
-
The effect of variations in temperature cycling profile and mechanical properties of solder on thermo-mechanical reliability of a lead-free BGA package
- 2015
-
In: Proceedings of the 16th International Conference IEEE EuroSimE 2015. - Piscataway : IEEE Press. - 9781479999514 ; , s. 165-169, s. 165-169
-
Conference paper (peer-reviewed)abstract
- The paper investigates the effect of variations both in temperature cycling profile and in SAC305 solder Young's modulus in the PBGA256 package on the thermo-mechanical reliability. FE simulations quantify the effect of cycle reduction and counting techniques by introducing different temperature profiles having identical dwell- and period time characteristics. A difference of 30% in predicted accumulated creep strain energy density per cycle has been determined for the studied profiles. Under the provided modelling assumptions and simplifications, the maximum variation of the thermal fatigue life of SAC305 solder joints is within 30% as the result of experimentally determined Young's modulus variation in as-delivered packages.
|
|
| 6. |
|
|
| 7. |
- Bjarnadottir, Olöf, et al.
(author)
-
Targeting HMG-CoA reductase with statins in a window-of-opportunity breast cancer trial
- 2013
-
In: Breast Cancer Research and Treatment. - : Springer Science and Business Media LLC. - 0167-6806 .- 1573-7217. ; 138:2, s. 499-508
-
Journal article (peer-reviewed)abstract
- Lipophilic statins purportedly exert anti-tumoral effects on breast cancer by decreasing proliferation and increasing apoptosis. HMG-CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate pathway, is the target of statins. However, data on statin-induced effects on HMGCR activity in cancer are limited. Thus, this pre-operative study investigated statin-induced effects on tumor proliferation and HMGCR expression while analyzing HMGCR as a predictive marker for statin response in breast cancer treatment. The study was designed as a window-of-opportunity trial and included 50 patients with primary invasive breast cancer. High-dose atorvastatin (i.e., 80 mg/day) was prescribed to patients for 2 weeks before surgery. Pre- and post-statin paired tumor samples were analyzed for Ki67 and HMGCR immunohistochemical expression. Changes in the Ki67 expression and HMGCR activity following statin treatment were the primary and secondary endpoints, respectively. Up-regulation of HMGCR following atorvastatin treatment was observed in 68 % of the paired samples with evaluable HMGCR expression (P = 0.0005). The average relative decrease in Ki67 expression following atorvastatin treatment was 7.6 % (P = 0.39) in all paired samples, whereas the corresponding decrease in Ki67 expression in tumors expressing HMGCR in the pre-treatment sample was 24 % (P = 0.02). Furthermore, post-treatment Ki67 expression was inversely correlated to post-treatment HMGCR expression (rs = -0.42; P = 0.03). Findings from this study suggest that HMGCR is targeted by statins in breast cancer cells in vivo, and that statins may have an anti-proliferative effect in HMGCR-positive tumors. Future studies are needed to evaluate HMGCR as a predictive marker for the selection of breast cancer patients who may benefit from statin treatment.
|
|
| 8. |
|
|
| 9. |
- Engström, Jens, et al.
(author)
-
Offshore Measurements and Numerical Validation of the Mooring Forces on a 1:5 Scale Buoy
- 2023
-
In: Journal of Marine Science and Engineering. - : MDPI. - 2077-1312. ; 11:1
-
Journal article (peer-reviewed)abstract
- Wave energy conversion is a renewable energy technology with a promising potential. Although it has been developed for more than 200 years, the technology is still far from mature. The survivability in extreme weather conditions is a key parameter halting its development. We present here results from two weeks of measurement with a force measurement buoy deployed at Uppsala University’s test site for wave energy research at the west coast of Sweden. The collected data have been used to investigate the reliability for two typical numerical wave energy converter models: one low fidelity model based on linear wave theory and one high fidelity Reynolds-Averaged Navier–Stokes model. The line force data is also analysed by extreme value theory using the peak-over-threshold method to study the statistical distribution of extreme forces and to predict the return period. The high fidelity model shows rather good agreement for the smaller waves, but overestimates the forces for larger waves, which can be attributed to uncertainties related to field measurements and numerical modelling uncertainties. The peak-over-threshold method gives a rather satisfying result for this data set. A significant deviation is observed in the measured force for sea states with the same significant wave height. This indicates that it will be difficult to calculate the force based on the significant wave height only, which points out the importance of more offshore experiments. © 2023 by the authors.
|
|
| 10. |
|
|
