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| 2. |
- Larsson, Bengt, 1943-, et al.
(författare)
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The Effect and Cost Impact of Poor Airtightness : Information for Developers and Clients
- 2007
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Ingår i: Thermal Performance of the Exterior Envelopes of Whole Buildings. - Orlando : ASHRAE. - 2166-8469. - 9781933742281
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Konferensbidrag (refereegranskat)abstract
- Air movements in and through the building envelope affect the flows of not only heat, but also moisture, gases and particles, in a building. They often play a decisive part in determining moisture conditions, and thus indoor environmental conditions in the building, and ultimately, the durability of the building structure. Air flows affect thermal comfort and ventilation, and thus air quality. In addition, they also cause heat loss, both directly via ventilation, and through their effect on the performance of what are intended to be high-insulation structures.A previous joint project between SP Technical Research Institute of Sweden and Chalmers University of Technology investigated the importance of airtightness in the construction process. The project found that many types of damage and problems were caused by poor airtightness, that airtightness was seldom given the proper consideration that it deserved and that there was a major need for information on the effect of poor airtightness. One of the conclusions was that it is important to get developers/clients to treat airtightness more seriously.The objective of the follow-on project that is described here is therefore to make developers/clients (more) aware of the potential damage that can be caused by poor airtightness, together with the “cost” of this damage/problem in a life-cycle perspective. Hopefully, developers/clients will then specify and monitor airtightness requirements more clearly. The aim is therefore to develop tools and methods for informing developers/clients of the importance of good airtightness, and of the resulting extra costs that incur from paying insufficient attention to airtightness.The project has identified and assessed various consequences of poor airtightness, such as increased energy use, reduced thermal comfort, reduced air quality and moisture damages.The cost calculations show that the developer/client would benefit in most cases from an increased standard and follow up on airtightness. We have projected the work with three different levels of ambition: 0.2, 0.4 and 0.6 l/m2s (at 50 Pa pressure difference), and believe that the optimal airtightness lies somewhere in the region of these values, depending on the buildings use and equipment.
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| 3. |
- Abbas, Taimoor, et al.
(författare)
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A Measurement Based Shadow Fading Model for Vehicle-to-Vehicle Network Simulations
- 2015
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Ingår i: International Journal of Antennas and Propagation. - : Hindawi Publishing Corporation. - 1687-5869 .- 1687-5877.
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Tidskriftsartikel (refereegranskat)abstract
- The vehicle-to-vehicle (V2V) propagation channel has significant implications on the design and performance of novel communication protocols for vehicular ad hoc networks (VANETs). Extensive research efforts have been made to develop V2V channel models to be implemented in advanced VANET system simulators for performance evaluation. The impact of shadowing caused by other vehicles has, however, largely been neglected in most of the models, as well as in the system simulations. In this paper we present a shadow fading model targeting system simulations based on real measurements performed in urban and highway scenarios. The measurement data is separated into three categories, line-of-sight (LOS), obstructed line-of-sight (OLOS) by vehicles, and non-line-of-sight due to buildings, with the help of video information recorded during the measurements. It is observed that vehicles obstructing the LOS induce an additional average attenuation of about 10 dB in the received signal power. An approach to incorporate the LOS/OLOS model into existing VANET simulators is also provided. Finally, system level VANET simulation results are presented, showing the difference between the LOS/OLOS model and a channel model based on Nakagami-m fading.
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| 4. |
- Böhm, Annette, et al.
(författare)
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Evaluating CALM M5-based vehicle-to-vehicle communication in various road settings through field trials
- 2010
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Ingår i: Proceedings - Conference on Local Computer Networks, LCN, (2010 12 01): 613-620. - Piscataway, N.J. : IEEE Press. - 9781424483877 ; , s. 613-620
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Konferensbidrag (refereegranskat)abstract
- Future cooperative Intelligent Transport Systems (ITS) applications aimed to improve safety, efficiency and comfort on our roads put high demands on the underlying wireless communication system. To gain better understanding of the limitations of the 5.9 GHz frequency band and the set of communication protocols for medium range vehicle to vehicle (V2V) communication, a set of field trials with CALM M5 enabled prototypes has been conducted. This paper describes five different real vehicle traffic scenarios covering both urban and rural settings at varying vehicle speeds and under varying line-of-sight (LOS) conditions and discusses the connectivity (measured as Packet Reception Ratio) that could be achieved between the two test vehicles. Our measurements indicate a quite problematic LOS sensitivity that strongly influences the performance of V2V-based applications. We further discuss how the awareness of these context-based connectivity problems can be used to improve the design of possible future cooperative ITS safety applications.
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| 5. |
- Eklund, Petter, 1989-, et al.
(författare)
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Experimental Evaluation of a Rare Earth-Free Permanent Magnet Generator
- 2021
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Ingår i: IEEE Transactions on Energy Conversion. - Piscataway : Institute of Electrical and Electronics Engineers (IEEE). - 1558-0059 .- 0885-8969. ; 36:1, s. 3-10
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Tidskriftsartikel (refereegranskat)abstract
- Low speed, high torque machines are used in wind turbines where the turbine rotor is directly connected to the generator. A permanent magnet synchronous generator using high-energy rare-earth permanent magnets (PMs) is one common choice for this application, but rare-earth PMs have supply insecurities and cost risks. A rare-earth free 32-pole PM generator, using ferrite PMs in a spoke-type rotor, for use in a 12 kW experimental wind turbine is built and tested. Voltages and currents at load and no load are measured, as well as the magnetic field in the end regions of the machine. The generator can deliver the required power at nominal speed and has low harmonic content in the output. The electrical measurements are compared to two-dimensional finite element design calculations and the experimental results are lower than expected from simulations. The measured voltage is lower than expected, requiring a higher current than calculated for the rated power. Three-dimensional magnetic field simulations show that there are leakage flux paths in the end-regions that the two-dimensional design calculations overlook, explaining the discrepancy between simulations and measurements.
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| 6. |
- Ge, Yu, 1995, et al.
(författare)
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Experimental Validation of Single Base Station 5G mm Wave Positioning: Initial Findings
- 2022
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Ingår i: 2022 25th International Conference on Information Fusion, FUSION 2022. - Piscataway : IEEE.
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Konferensbidrag (refereegranskat)abstract
- 5G cellular networks can utilize millimeter wave signals, and support large bandwidths and large antenna arrays, which provide more geometric-based signals and higher delay and angle resolutions. These merits bring new opportunities in positioning the user with limited infrastructure through the use of combined angle and delay information. However, there are many practical challenges to overcome, in order to have a functioning single base station 5G mmWave positioning system. In this paper, we describe a deployed single base station mmWave positioning system, and provide an example of the measurement data. Furthermore, we perform measurement validation on a limited measurement data set by performing base station localization. Additional evaluations performed on simulation model data provide guidelines on the required size of the data set and receiver antenna configuration, which will be implemented in upcoming measurements.
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| 7. |
- Habibi, Shiva, 1978, et al.
(författare)
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Comparison of free-floating car-sharing services in cities
- 2017
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Ingår i: ECEEE Summer Study, 29 May - 3 June, 2017. - 2001-7960. - 9789198387810 ; 2017
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Konferensbidrag (refereegranskat)abstract
- In recent years, free-floating car sharing services (FFCS) have been offered by many organizations as a more flexible option compared to traditional car sharing. FFCS allows users to pick up and return cars anywhere within a specified area of a city. FFCS can provide a high degree of utilization of vehicles and less usage of infrastructure in the form of parking lots and roads and thus has the potential to increase the efficiency of the transport sector. However, there is also a concern that these compete with other efficient modes of transport such as cycling and public transport. The aim of this paper is to better understand how, when and where the vehicles are utilized through logged data of the vehicles’ movements. We have access to data collected on FFCS services in 22 cities in Europe and North America which allows us to compare the usage pattern in different cities and examine whether or not there are similar trends. In this paper, we use the collected data to compare the different cities based on utilization rate, length of trip and time of day that the trip is made. We find that the vehicle utilization rates differ between cities with Madrid and Hamburg having some of the highest utilization levels for the FFCS vehicles. The results form a first step of a better understanding on how these services are being used and can provide valuable input to local policy makers as well as future studies such as simulation models.
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| 8. |
- Vedantha Krishna, Amogh, 1990-, et al.
(författare)
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Potential approach towards effective topography characterization of 316L stainless steel components produced by selective laser melting process
- 2018
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Ingår i: European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 18th International Conference and Exhibition, EUSPEN 2018. - Bedford : euspen. - 9780995775121 - 0995775125 ; , s. 259-260
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Konferensbidrag (refereegranskat)abstract
- In this paper, an attempt is made to explain the surface texture of Selective Laser Melting (SLM) parts more satisfyingly than the existing methods. Investigations were carried out on the 316L stainless steel SLM samples. To account for most of the surface conditions, a truncheon artefact was employed for the analysis. A Stylus Profilometer was employed as a metrology tool for obtaining the 3D surface measurements. A methodology is proposed to extract and characterize the topographic features of Additive Manufactured (AM) surfaces. Here, the overall roughness of the surface is segregated into the roughness of the powder particles and the waviness due to thermal and the "staircase" effects. Analyzing these features individually results in an increased understanding of the AM process and an opportunity to optimize machine settings.
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| 9. |
- Dimkovski, Zlate, 1974-, et al.
(författare)
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Towards 3D Characterisation of Cylinder Liner Surfaces
- 2008
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Ingår i: Proceedings / XII. International Colloquium on Surfaces January 28th and 29th, 2008, Chemnitz, Germany = XII. Internationales Oberflächenkolloquium. - Aachen : Shaker Verlag. - 9783832269128 ; , s. 15-24
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Konferensbidrag (refereegranskat)abstract
- Cylinder liner surface has a direct impact on the oil consumption and frictional losses in the internal combustion engines which are in common interest to be as lower as possible. Thus, the optimisation of the liner surface, its function and manufacture is often on the agenda of the automotive industry. Since the liner surface finish is a subject of improving, there is a need of improving and facilitating of its 3D characterisation preliminary when the parameter control limits are unknown, as well as later when it is experimentally verified and the limits are better determined. For that purpose a method for quality control in 3D of cylinder liners is proposed here. A tool was developed and implemented for rating of cylinder liner surfaces, computing of 3D groove parameters (groove width, height and distance between grooves) and determination of a needed number of measurements.
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| 10. |
- Flys, Olena, 1971-, et al.
(författare)
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Characterization of surface topography of a newly developed metrological gloss scale
- 2015
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics (IOP). - 2051-672X. ; 3:4
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Tidskriftsartikel (refereegranskat)abstract
- In the European Joint Research Project 'Multidimensional Reflectometry for Industry', a new gloss scale was developed with the aim to represent different levels of gloss, hue, roughness, and refractive indices. In this paper, the surfaces of six selected samples were thoroughly investigated using various measuring techniques in order to verify the outcome of the novel manufacturing processes in terms of distinct levels as well as types of surface roughness. The aim of the evaluation was to capture surface structures in different wavelength intervals utilizing a confocal microscope, a coherence scanning interferometer, and an atomic force microscope. Power spectral density functions were also calculated from the measurements and used to determine suitability of techniques for different roughness scales. The measurements show that the expected surface characteristics as well as different RMS roughness values are intimately connected to the perceived glossiness.
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