| 1. |
- Pålsson, Björn, 1981, et al.
(författare)
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A comparison of track model formulations for simulation of dynamic vehicle–track interaction in switches and crossings
- 2023
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 61:3, s. 698-724
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Tidskriftsartikel (refereegranskat)abstract
- This paper compares different track model formulations for the simulation of dynamic vehicle–track interaction in switches and crossings (S&C, turnouts) in a multi-body simulation (MBS) environment. The investigations are an extension of the S&C simulation Benchmark with the addition of a finite element model of a 60E1-760-1:15 turnout. This model constitutes a common reference from which four different track formulations are derived: co-running, modal superposition, finite element incorporated into the MBS model and finite element coupled to MBS using a co-simulation approach. For the different track models, the difference in modelling technique, results, simulation time, and suitability for different simulation tasks is compared. A good agreement is found between the different track model formulations for wheel–rail contact forces and rail displacements. This study found a better agreement between co-running and structural track models compared to previous studies in the prediction of wheel–rail contact forces. This appears to be due to the increased complexity of co-running track model used in this study together with a tuning of the co-running track model to the reference model in a wider frequency range. For the reader interested to reproduce the results in this paper, the reference track model is available for download.
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| 2. |
- Cristofer, Englund, 1977-, et al.
(författare)
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Future Applications of VANETs
- 2015
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Ingår i: Vehicular Ad Hoc Networks. - Cham : Springer Publishing Company. - 9783319154961 - 9783319154978 ; , s. 525-544
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Bokkapitel (refereegranskat)abstract
- Current transportation systems face great challenges due to the increasing mobility. Traffic accidents, congestion, air pollution, etc., are all calling for new methods to improve the transportation system. With the US legislation in progress over vehicle communications and EU’s finalization of the basic set of standards over cooperative intelligent transportation systems (C-ITS), vehicular ad hoc network (VANET) based applications are expected to address those challenges and provide solutions for a safer, more efficient and sustainable future intelligent transportation systems (ITS). In this chapter, transportation challenges are firstly summarized in respect of safety, efficiency, environmental threat, etc. A brief introduction of the VANET is discussed along with state of the art of VANET-based applications. Based on the current progress and the development trend of VANET, a number of new features of future VANET are identified, together with a set of potential future ITS applications. The on-going research and field operational test projects, which are the major enabling efforts for the future VANET-based C-ITS, are presented. The chapter is of great interest to readers working within ITS for current development status and future trend within the C-ITS area. It is also of interest to general public for an overview of the VANET enabled future transportation system. © Springer International Publishing Switzerland 2015.
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| 3. |
- Yang Lin, Shih, 1979-, et al.
(författare)
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Poster : Adaptive Wavelength Adjustment (AWLA) for Cooperative Speed Harmonization
- 2014
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Ingår i: 2014 IEEE Vehicular Networking Conference (VNC). - Piscataway, NJ : IEEE Press. - 9781479976607 ; , s. 113-114, s. 113-114
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Konferensbidrag (refereegranskat)abstract
- Traffic merge on express-ways creates bottlenecks for traffic flow that potentially lead to traffic jams, especially in dense traffic. Cooperative speed harmonization (CSH), where vehicles are grouped and associated to virtual speed waves for group-wise joining at intersections, is proven to be efficient for on-ramp traffic merge. Based on CSH and considering variations of traffic density from joining roads, an adaptive wavelength adjustment (AWLA) mechanism is proposed in this paper. AWLA extends CSH by dynamically adjusting the length of segments in virtual waves according to the traffic densities of the joining roads. Therefore, roads with denser traffic may have larger segments to carry more vehicles through the intersection, which may improve the overall performance. Simulation results have shown that AWLA can achieve lower CO2 emissions and shorter travel time compared to CSH with static segment settings.
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| 4. |
- Holmberg, Sture, et al.
(författare)
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Drug-resistant bacteria in hospital wards - the role of ventilation
- 2009
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Ingår i: 9th International Conference and Exhibition - Healthy Buildings 2009, HB 2009. ; , s. 596-
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Konferensbidrag (refereegranskat)abstract
- To limit the airborne spread of infectious agents (antibiotic-resistant bacteria) in hospital wards is an increasing world-wide concern. A multi-disciplinary Swedish research team is together with industry focusing on this problem. New knowledge is sought on how building ventilation services should be designed to minimize the risk of airborne infectious agents. In the literature there is strong and sufficient evidence to demonstrate the association between ventilation, air movements in buildings and the transmission/spread of diseases. There is, however, insufficient data to specify and quantify the minimum ventilation requirements in relation to the spread of infectious diseases via the airborne route. The latest developments in the advanced numerical simulation (CFD) methods offer new possibilities to follow the routes of airborne contaminants. Many ventilation parameters, including air flow rates, thermal and pressure conditions as well as the behavior of persons in the room are analyzed. The influence of both local air supply and local air exhaust has been analyzed and very promising results from this part of the work are presented. A bacterium spread from a patient confined to his bed was limited and for certain conditions almost eliminated. Ventilation and spatial parameter combinations to limit and prevent the spread of contaminants are mapped for different hospital wards. The risk of airborne transmission is modeled and discussed. Implementation in practice is sought via close collaboration with industry.
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| 5. |
- Chen, Shih-Ying, et al.
(författare)
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Transport of Contaminated Agents in Hospital Wards - Exposure Control with a Personalized Healthcare Ventilation System: Numerical Study
- 2021
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Konferensbidrag (refereegranskat)abstract
- Contaminated agents in hospital wards are the source of nosocomial infections known as hospital-acquired infection (HAI) or healthcare-associated infections (HAIs). Ventilation plays an essential role in the spreading and minimizing the transport of airborne infectious diseases such as Covid-19 and SARS in the hospital ward. The goal of this study is to explore elimination strategies for an efficient removal of contaminated agents, targeting the influence of using local air diffuser and exhaust. Computational Fluid Dynamics (CFD) technique was used to model the airflow field and contamination distribution in the ward environment. Simulated results showed that the bacteria spread from a patient confined to his bed was limited and under certain conditions significantly eliminated. Consequently, a relatively high efficiency of particle removal and a moderated transmission were obtained. Thus, this strategy is able to shorten the exposure time of patient and healthcare staff, as a result, mitigating cross-infection risk at the hospital.
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| 6. |
- Hashemi, Ehsan, et al.
(författare)
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Fault Tolerant Consensus for Vehicle State Estimation : A Cyber-Physical Approach
- 2019
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Ingår i: IEEE Transactions on Industrial Informatics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1551-3203 .- 1941-0050. ; 15:9, s. 5129-5138
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Tidskriftsartikel (refereegranskat)abstract
- A novel cyber physical method is proposed and experimentally verified for reliable distributed estimation of vehicle longitudinal velocity, robustly to road friction condition variations. In this method, the vehicle speed estimated at each of the four corners of the vehicle, using a linear parameter-varying observer in the physical layer, and speed data measured by a conventional low-cost GPS are incorporated in a distributed structure (in the cyber layer) to enhance the reliability of the estimate. The method minimizes a cost function quantizing the effect of disturbances on each corner's estimation and adversaries due to occasional GPS signal drops. A fault-tolerant estimation policy is integrated to deal with large deviations in corner estimations, which have unexpectedly high levels of confidence. The main advantages of the proposed method are increased reliability on various road surface conditions and robustness to faults, as confirmed by road tests. Several experimental tests, including lane change and low-excitation maneuvers, with various powertrain configurations on dry and slippery roads demonstrate the efficiency of the algorithm.
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| 7. |
- Minzioni, Paolo, et al.
(författare)
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Roadmap for optofluidics
- 2017
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Ingår i: Journal of Optics. - : Institute of Physics (IOP). - 2040-8978 .- 2040-8986. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Optofluidics, nominally the research area where optics and fluidics merge, is a relatively new research field and it is only in the last decade that there has been a large increase in the number of optofluidic applications, as well as in the number of research groups, devoted to the topic. Nowadays optofluidics applications include, without being limited to, lab-on-a-chip devices, fluid-based and controlled lenses, optical sensors for fluids and for suspended particles, biosensors, imaging tools, etc. The long list of potential optofluidics applications, which have been recently demonstrated, suggests that optofluidic technologies will become more and more common in everyday life in the future, causing a significant impact on many aspects of our society. A characteristic of this research field, deriving from both its interdisciplinary origin and applications, is that in order to develop suitable solutions a combination of a deep knowledge in different fields, ranging from materials science to photonics, from microfluidics to molecular biology and biophysics, is often required. As a direct consequence, also being able to understand the long-term evolution of optofluidics research is not easy. In this article, we report several expert contributions on different topics so as to provide guidance for young scientists. At the same time, we hope that this document will also prove useful for funding institutions and stakeholders to better understand the perspectives and opportunities offered by this research field.
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| 8. |
- Reza, Bagger, et al.
(författare)
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RF LDMOS Power Amplifier Integrated Circuits for Cellular Wireless Base Station Applications
- 2006
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Konferensbidrag (refereegranskat)abstract
- Three broadband RF LDMOS Power Amplifier Integrated Circuits (PA ICs) for cellular base station applications have been developed in Si LDMOS IC technologies. They can be used for all typical modulation formats from 800 MHz to 2300 MHz, and power levels from 30 W to 50 W depending on application. GSM/EDGE PA IC achieved 35 dB gain and 30 W with 200 MHz bandwidth (22% bandwidth) at 900_MHz. CDMA2000 PA IC achieved 30 dB gain and 40 W with 300 MHz bandwidth (15% bandwidth) at 1900 MHz. TD-SCDMA/WCDMA PA IC achieved 27 dB gain and 50 W under TD-SCDMA signal and 40 W under WCDMA signal with 400 MHz bandwidth (20% bandwidth) at 2100 MHz. All three PA ICs have been characterized under all typical modulations formats and showed excellent linear power, efficiency, and bandwidth. The excellent performances of these three PA ICs, simplify power amplifier designs, enable a small footprint and help lower the cost of the modern base-station.
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