| 1. |
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| 2. |
- Okda, Sherif, et al.
(författare)
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Testing of the Aerodynamic Characteristics of an Inflatable Airfoil Section
- 2020
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Ingår i: Journal of Aerospace Engineering. - 1943-5525 .- 0893-1321. ; 33:5
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Tidskriftsartikel (refereegranskat)abstract
- Inflatable structures are characterized by being light and easy to manufacture and deploy. Hence, they find many applications in aerospace and aeronautical engineering. In this paper, an inflatable segment with a The National Advisory Committee for Aeronautics (NACA) 0021 airfoil cross-section is designed, fabricated, and tested. The geometrical accuracy of the manufactured inflatable segment is measured using laser scanning. Measurements show that the average normalized error of the chord length and thickness are 2.97% and 0.554%, respectively. The aerodynamic behavior of the inflatable segment is then tested in a wind tunnel at different wind speeds and angles of attack. Lift forces are measured using a six-component balance, while the drag forces are calculated from the wake measurements. The lift and drag coefficients of the inflatable section are compared to those of a standard NACA 0021 airfoil. Finally, flow visualization is examined at different angles of attack using two methods: smoke and tufts. Both methods show that flow separation starts at 15° and full stall occurs at 25°. Results indicate that inflatables can find more applications in the design and construction of aerodynamic structures, such as wings.
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| 3. |
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| 4. |
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INNOTRACK: Concluding technical report
- 2010
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- The track structure, rails, switches and crossings account for more than 50% of maintenance and renewal costs for the rail industry. To improve the competitiveness of rail transportation, the cost-efficiency of these areas needs to be addressed.This the background to INNOTRACK, an integrated research project funded by the European Commission’s 6th research framework pro- gramme. Running from September 2006 to December 2009, INN- OTRACK has developed a multitude of innovative solutions in the areas of track substructure, rails & welds, and switches & crossings. The solutions have been assessed from technical, logistics and life cycle cost point of views.This Concluding Technical Report of INNOTRACK includes an overview of the project. It further details implementable results, and clusters them into ”highlight” areas. In addition, the book acts as a ”key” to the vast amount of information from INNOTRACK: All sections refer to project reports where more information can be found.
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| 5. |
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| 6. |
- Heshmati, Mohsen, 1987, et al.
(författare)
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Dependency of cohesive laws of a structural adhesive in Mode-I and Mode-II loading on moisture, freeze-thaw cycling, and their synergy
- 2017
-
Ingår i: Materials and Design. - : Elsevier BV. - 1873-4197 .- 0264-1275. ; 122, s. 433-447
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, adhesive bonding has found its way to construction applications such as bridges. Given the harsh conditions that such structures are usually exposed to, it is necessary to account for environmental factors, particularly moisture and temperature, in the design phase. Cohesive zone modelling has attracted much attention in the last decade as a promising method to design adhesive joints. Despite this interest, the effects of moisture and thermal cycles on cohesive laws have not been investigated to the knowledge of the authors. In this paper, we present a method to directly measure the environmental-dependent cohesive laws of a structural adhesive loaded in pure Mode-I and Mode-II. Special consideration is given to overcome issues such as the time-consuming nature of moisture ingression and specimen dimensions, which could be problematic due to the size-limitations of conditioning equipment. The accuracy of this method was verified through simulation of the experiments using the finite element analysis. The effects of exposure to 95% relative humidity, immersion in saltwater and distilled water, and freeze-thaw cycles in the presence or absence of moisture were investigated. The results indicate the damaging effects of combined saltwater and freeze-thaw cycles which were clearly reflected on the shape of the cohesive laws.
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| 7. |
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| 8. |
- Stylidis, Kostas, 1978, et al.
(författare)
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Perceived quality framework in product generation engineering: an automotive industry example
- 2019
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Ingår i: Design Science. - : Cambridge University Press (CUP). - 2053-4701 .- 2053-4701. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Perceived quality refers to customers’ cognitive and emotional responses to a particular design, often also associated with craftsmanship and customer satisfaction. Previous research defined a taxonomy of perceived quality and provided understanding about how engineering design decisions impact customer satisfaction. Furthermore, development of new products is frequently based on carrying over attributes of existing products, either from the same producer or from competitors. Previous research offered a new product development methodology combining variations of subsystems to carry over from existing products. This brief presents how these two lines of research combined to design the central console of the Porsche Panamera automobile and discusses the opportunities and challenges posed in the practical implementation of this research.
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| 9. |
- Eriksson, Sören, 1953-
(författare)
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China's aircraft industry: collaboration and technology transfer - the case of Airbus
- 2010
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Ingår i: International Journal of Technology Transfer and Commercialisation (IJTTC). - : Inderscience Enterprises Ltd. - 1470-6075 .- 1741-5284. ; 9:4, s. 306-325
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Tidskriftsartikel (refereegranskat)abstract
- China has moved a long way in economic and industrial development during the last decades and has developed into a global player in many industries. With increased knowledge in high-technology industries, China has ambitions to move into sectors that necessitate a high level of research and development, such as the aerospace industry. China is now in the process of establishing a modern aircraft industry based on domestic efforts as well as agreements with foreign partners in the manufacturing of complete aircraft. This paper analyzes what measures have been taken by Airbus in the form of technology transfer and other supportive measures to strengthen its position in the Chinese market. The findings conclude that Airbus’ transfer should be looked upon as a broad spectrum of technology and knowledge transfer, which include aircraft manufacturing technology, as well as cabin crew training centre, establishment of a warehouse and suppliers ”village”, an engineering centre, maintenance and various service functions.
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| 10. |
- Wadekar, Sandip, 1989
(författare)
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Large-Eddy Simulation of Gasoline Fuel Spray Injection at Ultra-High Injection Pressures
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gasoline direct injection is a state-of-the-art technique that reduces hydrocarbon and particulate emissions. However, further improvement is needed to meet current as well as future emission regulations. A prominent solution is to increase the fuel injection pressure which allows faster fuel droplet atomization, quick evaporation and improves fuel-air mixture formation under realistic engine conditions. In this work, the gasoline fuel injection process at ultra-high injection pressures ranging from 200 to 1500 bar was analyzed using numerical models. In particular, the Large-Eddy Simulation (LES) method, with the standard Smagorinsky turbulence model, was utilized using the Eulerian formulation for the continuous phase. The discrete droplet phase was treated using a Lagrangian formulation together with spray sub-models. In the first part of study, spray was injected into an initially quiescent constant volume chamber using two different nozzle hole shape geometries: divergent and convergent. The numerical results were calibrated by reproducing experimentally observed liquid penetration length and efforts were made to understand the influence of ultra-high injection pressures on spray development. The calibrated models were then used to investigate the impact of ultra-high injection pressures on mean droplet sizes, droplet size distribution, spray-induced large-scale eddies and entrainment rate. The results showed that, at ultra-high injection pressures, the mean droplet sizes were significantly reduced and the droplets achieving very high velocities. Integral length scales of spray-induced turbulence and air entrainment rate were better for the divergent-shaped injector, and considerably larger at higher injection pressures compared to lower ones. In the second part of the study, four consecutive full-cycle cold flow LES simulations were carried out to generate realistic turbulence inside the engine cylinder. The first three cycles were ignored, with the fourth cycle being used to model the injection of the fuel using the divergent-shaped injector only (which was found to be better in the previous part of this study) at different injection pressures. In addition to the continuous gas phase (Eulerian) and the dispersed liquid (Lagrangian), the liquid film feature (Finite-Area) was used to model the impingement of fuel spray on the engine walls and subsequent liquid film formation. The simulation results were used to evaluate spray-induced turbulence, fuel-air mixing efficiency and the amount of liquid mass deposited on the walls. The limitation of the high-pressure injection technique with respect to liquid film formation was optimized using a start of injection (SOI) sweep. Overall results showed that the mixing efficiency increased at high injection pressure and that SOI should occur between early injection and late injection to optimize the amount of mass being deposited on the engine walls.
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| 11. |
- Liu, Yuanhua, 1971, et al.
(författare)
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Considering the importance of user profiles in interface design
- 2009
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Ingår i: User Interfaces. ; , s. 23-
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- User profile is a popular term widely employed during product design processes by industrial companies. Such a profile is normally intended to represent real users of a product. The ultimate purpose of a user profile is actually to help designers to recognize or learn about the real user by presenting them with a description of a real user’s attributes, for instance; the user’s gender, age, educational level, attitude, technical needs and skill level. The aim of this chapter is to provide information on the current knowledge and research about user profile issues, as well as to emphasize the importance of considering these issues in interface design. In this chapter, we mainly focus on how users’ difference in expertise affects their performance or activity in various interaction contexts. Considering the complex interaction situations in practice, novice and expert users’ interactions with medical user interfaces of different technical complexity will be analyzed as examples: one focuses on novice and expert users’ difference when interacting with simple medical interfaces, and the other focuses on differences when interacting with complex medical interfaces. Four issues will be analyzed and discussed: (1) how novice and expert users differ in terms of performance during the interaction; (2) how novice and expert users differ in the perspective of cognitive mental models during the interaction; (3) how novice and expert users should be defined in practice; and (4) what are the main differences between novice and expert users’ implications for interface design. Besides describing the effect of users’ expertise difference during the interface design process, we will also pinpoint some potential problems for the research on interface design, as well as some future challenges that academic researchers and industrial engineers should face in practice.
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| 12. |
- Nybacka, Mikael, et al.
(författare)
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Project: CASTT - Centre for Automotive Systems Technologies and Testing
- 2007
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Annan publikation (populärvet., debatt m.m.)abstract
- Through the Centre for Automotive Systems Technologies and Testing, Luleå University of Technology aims to first of all support automotive winter testing in Northern Sweden. This means to support the local automotive test entrepreneurs and through them their customers: the car manufacturers and their suppliers. To succeed in this task, the center relies on the university's areas of leading research and most importantly on the cooperation between those areas.
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| 13. |
- Skagestad, Ragnhild, 1978, et al.
(författare)
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GCCSI Webinar: Cutting Cost of CO2 Capture in Process Industry (CO2stCap) Project overview & first results for partial CO2 capture at integrated steelworks
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- GCCSI Webinar: Cutting Cost of CO2 Capture in Process Industry (CO2stCap) Project overview & first results for partial CO2 capture at integrated steelworks This publication has the format of a webinar: The CO2StCap project is a four year initiative carried out by industry and academic partners with the aim of reducing capture costs from CO2 intensive industries (more information here). The project, led by Tel-Tek, is based on the idea that cost reduction is possible by capturing only a share of the CO2 emissions from a given facility, instead of striving for maximized capture rates. This can be done in multiple ways, for instance by capturing only from the largest CO2 sources at individual multi-stack sites utilising cheap waste heat or adapting the capture volumes to seasonal changes in operations. The main focus of this research is to perform techno-economic analyses for multiple partial CO2 capture concepts in order to identify economic optimums between cost and volumes captured. In total for four different case studies are developed for cement, iron & steel, pulp & paper and ferroalloys industries. The first part of the webinar gave an overview of the project with insights into the cost estimation method used. The second part presented the iron & steel industry case study based on the Lulea site in Sweden, for which waste-heat mapping methodology has been used to assess the potential for partial capture via MEA-absorption. Capture costs for different CO2 sources were discussed, demonstrating the viability of partial capture in an integrated steelworks.
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| 14. |
- Kyprianidis, Konstantinos, 1984, et al.
(författare)
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Multidisciplinary Analysis of a Geared Fan Intercooled Core Aero-Engine
- 2014
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 136:1
-
Tidskriftsartikel (refereegranskat)abstract
- The reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, along with the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. The thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is very little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to analyze the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. With minimum mission fuel in mind, the results indicate as optimal values a pressure ratio split exponent of 0.38 and an intercooler mass flow ratio of 1.18 at hot-day top of climb conditions. At ISA midcruise conditions a specific thrust of 86 m/s, a jet velocity ratio of 0.83, an intercooler effectiveness of 56%, and an overall pressure ratio value of 76 are likely to be a good choice. A 70,000 lbf intercooled turbofan engine is large enough to make efficient use of an all-axial compression system, particularly within a geared fan configuration, but intercooling is perhaps more likely to be applied to even larger engines. The proposed optimal jet velocity ratio is actually higher than the value one would expect by using standard analytical expressions, primarily because this design variable affects core efficiency at midcruise due to a combination of several different subtle changes to the core cycle and core component efficiencies at this condition. The analytical expressions do not consider changes in core efficiency and the beneficial effect of intercooling on transfer efficiency, nor do they account for losses in the bypass duct and jet pipe, while a relatively detailed engine performance model, such as the one utilized in this study, does. Mission fuel results from a surrogate model are in good agreement with the results obtained from a rubberized-wing aircraft model for some of the design parameters. This indicates that it is possible to replace an aircraft model with specific fuel consumption and weight penalty exchange rates. Nevertheless, drag count exchange rates have to be utilized to properly assess changes in mission fuel for those design parameters that affect nacelle diameter.
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| 15. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:7
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Forskningsöversikt (refereegranskat)abstract
- Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.
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| 16. |
- Mirkhalaf, S. Mohsen, 1982, et al.
(författare)
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A finite element based orientation averaging method for predicting elastic properties of short fiber reinforced composites
- 2020
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Ingår i: Composites Part B-Engineering. - : Elsevier BV. - 1359-8368. ; 202
-
Tidskriftsartikel (refereegranskat)abstract
- Short fiber reinforced composites have a variety of micro-structural parameters that affect their macromechanical performance. A modeling methodology, capable of accommodating a broad range of these parameters, is desirable. This paper describes a micro-mechanical model which is developed using Finite Element Analysis and Orientation Averaging. The model is applicable to short fiber reinforced composites with a wide variety of micro-structural parameters such as arbitrary fiber volume fractions, fiber aspect ratios and fiber orientation distributions. In addition to the Voigt and Reuss assumptions, an interaction model is developed based on the self-consistent assumption. Comparisons with experimental results, and direct numerical simulations of Representative Volume Elements show the capability of the model for fair predictions.
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| 17. |
- Esmaeili, Ali, 1983, et al.
(författare)
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Modelling of temperature and strain rate dependent behaviour of pearlitic steel in block braked railway wheels
- 2021
-
Ingår i: Railway Engineering Science. - : Springer. - 2662-4745 .- 2662-4753. ; 29:4, s. 362-378
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Tidskriftsartikel (refereegranskat)abstract
- Block braked railway wheels are subjected to thermal and rolling contact loading. The thermal loading results in high temperatures and thermal stresses which cause slow time dependent processes such as creep, relaxation and static recovery of the wheel material. At the same time, the rolling contact loading implies a very fast mechanical load application. This paper is focused on material modeling of pearlitic steel for a wide range of loading rates at elevated temperatures. The starting point is a viscoplasticity model including nonlinear isotropic and kinematic hardening. The Delobelle overstress function is employed to capture strain rate dependent response of the material. The model also includes static recovery of the hardening to capture slower viscous (diffusion dominated) behaviour of the material. Experiments for the pearlitic wheel steel ER7 in terms of cyclic strain-controlled uniaxial tests with hold-time, uniaxial ratchetting tests including rapid cycles and biaxial cyclic tests with tension/compression and torsion are used to calibrate the material model. These experiments were performed under isothermal conditions at different temperatures. In the ratchetting tests, higher loading rates are obtained and these have been used to calibrate the high strain rate response of the viscoplasticity model. The paper is concluded with a numerical example of a block braked wheel where the importance of accounting for the viscoplasticity in modelling is highlighted.
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| 18. |
- Shahroozi, Zahra, 1992-
(författare)
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Survivability control using data-driven approaches and reliability analysis for wave energy converters
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wave energy, with five times the energy density of wind and ten times the power density of solar, offers a compelling carbon-free electricity solution. Despite its advantages, ongoing debates surround the reliability and economic feasibility of wave energy converters (WECs). To address these challenges, this doctoral thesis is divided into four integral parts, focusing on optimizing the prediction horizon for power maximization, analyzing extreme waves' impact on system dynamics, ensuring reliability, and enhancing survivability in WECs.Part I emphasizes the critical importance of the prediction horizon for maximal power absorption in wave energy conversion. Using generic body shapes and modes, it explores the effect of dissipative losses, noise, filtering, amplitude constraints, and real-world wave parameters on the prediction horizon. Findings suggest achieving optimal power output may be possible with a relatively short prediction horizon, challenging traditional assumptions.Part II shifts focus to WEC system dynamics, analyzing extreme load scenarios. Based on a 1:30 scaled wave tank experiment, it establishes a robust experimental foundation, extending into numerical assessment of the WEC. Results underscore the importance of damping to alleviate peak forces. Investigating various wave representations highlights conservative characteristics of irregular waves, crucial for WEC design in extreme sea conditions.Part III explores the computational intricacies of environmental design load cases and fatigue analyses for critical mechanical components of the WEC. The analysis is conducted for hourly sea state damage and equivalent two-million-cycle loads. Finally, a comparison of safety factors between the ultimate limit state and fatigue limit state unfolds, illustrating the predominant influence of the ultimate limit state on point-absorber WEC design.Part IV, centers on elevating survivability strategies for WECs in extreme wave conditions. Three distinct controller system approaches leverage neural networks to predict and minimize the line force. Distinct variations emerge in each approach, spanning from rapid detection of optimal damping to integrating advanced neural network architectures into the control system with feedback. The incorporation of a controller system, refined through experimental data, showcases decreases in the line force, providing a practical mechanism for real-time force alleviation.This thesis aims to contribute uniquely to the goal of advancing wave energy conversion technology through extensive exploration.
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| 19. |
- Binder, Christian, 1988-, et al.
(författare)
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Phosphor Thermometry for In-Cylinder Surface Temperature Measurements in Diesel Engines
- 2019
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Ingår i: Measurement science and technology. - 0957-0233 .- 1361-6501.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Surface temperature measurements in technically relevant applications can be very hallenging and yet of great importance. Phosphor thermometry is a temperature measurement technique that has previously been employed in technically relevant applications to obtain surface temperature. The technique is based on temperature-dependent changes in a phosphor’s luminescence. To improve the accuracy and precision of temperature measurements with this technique, the present study considers, by way of example, the impact of conditions inside the cylinder of a diesel engine on decay time based phosphor thermometry. After an initial, general assessment of the effect of prevailing measurement conditions, this research investigates errors caused by soot luminosity, extinction, signal trapping and changes of phosphors’ luminescence properties due to exposure to the harsh environment. Furthermore, preferable properties of phosphors which are suitable for in-cylinder temperature measurements are discussed. 16 phosphors are evaluated, including four which – to the authors’ knowledge –have previously not been used in thermometry. Results indicate that errors due to photocathode bleaching, extinction, signal trapping and changes of luminescence properties may cause an erroneous temperature evaluation with temperature errors in the order of serval tens of Kelvin.
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| 20. |
- Yang, Shun-Han, 1987, et al.
(författare)
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Parametric study of the dynamic motions and mechanical characteristics of power cables for wave energy converters
- 2018
-
Ingår i: Journal of Marine Science and Technology. - : Springer Science and Business Media LLC. - 0948-4280 .- 1437-8213. ; 23:1, s. 10-29
-
Tidskriftsartikel (refereegranskat)abstract
- A case study of a point-absorber wave energy converter (WEC) system is presented. The WEC system forms an array, with several WECs located around a central hub to which they are each connected by a short, free-hanging power cable. The objective of the study is to analyse the dynamic characteristics and estimate the fatigue life of the power cable which is not yet in use or available on the commercial market. Hence, a novel approach is adopted in the study considering that the power cable’s length is restricted by several factors (e.g., the clearances between the service vessel and seabed and the cable), and the cable is subject to motion and loading from the WEC and to environmental loads from waves and currents (i.e., dynamic cable). The power cable’s characteristics are assessed using a numerical model subjected to a parametric analysis, in which the environmental parameters and the cable’s design parameters are varied. The results of the numerical simulations are compared and discussed regarding the responses of the power cables, including dynamic motion, curvature, cross-sectional forces, and accumulated fatigue damage. The effects of environmental conditions on the long-term mechanical life spans of the power cables are also investigated. Important cable design parameters that result in a long power cable (fatigue) service life are identified, and the cable service life is predicted. This study contributes a methodology for the first-principle design of WEC cables that enables the prediction of cable fatigue life by considering environmental conditions and variations in cable design parameters.
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| 21. |
- Chen, Zhe, et al.
(författare)
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Nano-scale characterization of white layer in broached Inconel 718
- 2017
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Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - Amsterdam : Elsevier BV. - 0921-5093 .- 1873-4936. ; 684, s. 373-384
-
Tidskriftsartikel (refereegranskat)abstract
- The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718.TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.
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| 22. |
- Vernersson, Tore V, 1968, et al.
(författare)
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Wear of brake blocks for in-service conditions-Influence of the level of modelling
- 2014
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Ingår i: Wear. - : Elsevier BV. - 0043-1648. ; 314:1-2, s. 125-131
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Tidskriftsartikel (refereegranskat)abstract
- Wear of brake blocks at tread braking of railway wheels is one of the key factors that control the time period between scheduled train maintenance and hence has a substantial impact on the life cycle cost of the vehicle. Wear simulations using two different numerical models, one thermal model and one thermoelastic model, are presented implementing wear rates for some brake block materials exploiting results from previously performed temperature-controlled pin-on-disc tests. It is found that the thermal model and the thermoelastic model give the same wear for cases when thermoelastic instability effects are small. However, for cases when the thermoelastic effects increase the local contact pressures and surface temperatures, large differences are found.
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| 23. |
- Midya, Surajit, et al.
(författare)
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DC Component From Pantograph Arcing in AC Traction System : Influencing Parameters, Impact, and Mitigation Techniques
- 2011
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Ingår i: IEEE transactions on electromagnetic compatibility (Print). - : IEEE conference proceedings. - 0018-9375 .- 1558-187X. ; 53:1, s. 18-27
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Tidskriftsartikel (refereegranskat)abstract
- Pantograph arcing in ac traction system generates transients, and causes asymmetries and distortion in supply voltage and current waveforms. These asymmetric voltage and current lead to a net dc component and harmonics that propagate within the traction power and signalling system and cause electromagnetic interference. This problem is enhanced during winter because of the layer of ice/snow on the overhead contact wire. The sliding contact becomes poor and a visible arc moves along with the pantograph. In this paper, it is shown how different parameters like traction current, line speed, power factor, and supply voltage influence the arcing, its characteristics, and the dc components. It is shown that the dc current component increases with increasing train speed and traction current, and reduces at a lower power factor. It is also discussed how the presence of an ice layer influences the arcing and the dc components. It is found that running the trains below the normal operating power factors is an effective choice to mitigate this problem. The findings presented in this paper could be beneficial to estimate the probable limit of the dc component at the planning stage so that proper precautions can be taken at the design stage itself.
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| 24. |
- Ribeiro, Luis, et al.
(författare)
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Industrial Agents for the Fast Deployment of Evolvable Assembly Systems
- 2015. - 1st ed.
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Ingår i: Industrial Agents. - Amsterdam, Netherlands : Elsevier. - 9780128003411 ; , s. 301-321, s. 301-322
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Bokkapitel (refereegranskat)abstract
- The current manufacturing scenario is characterized by high market unpredictability. Agility is therefore a central challenge for modern companies that need to understand and be proactive towards their product offer in respect to “what is offered, when it is offered, where, how and by whom” (Brown & Bessant 2003).The “what” and the “when” are particularly relevant to the research in emerging paradigms as they account for variety, customization and volume; and timing, speed and seasonality (Brown & Bessant 2003).In this scenario, several design approaches and models have been proposed in the last decade to enable re-configurability and subsequently enhance the companies’ ability to adjust their offer in nature and time.From a paradigmatic point of view research has concentrated on the organizational structure of the shop-floor and the associated controls aspects. Concepts like Reconfigurable Manufacturing Systems (RMS) (Koren & Shpitalni 2010) and Fractal Factories (FF) (Montreuil 1999) support the physical construction of production systems by regulating their layout and making a few assumptions on their logical organization. On the other hand, concepts like Bionic Manufacturing Systems (BMS)(Ueda 1992), Holonic Manufacturing Systems (HMS)(Van Brussel et al. 1998), Evolvable Assembly Systems (Ribeiro et al. 2010) essentially provide the theoretical guidelines for the logical/computational organization of the system (see (Tharumarajah 1996) for a comparison between BMS, HMS and FF and (Setchi & Lagos 2004) for the rationale supporting the shift from Dedicated Lines to Flexible Manufacturing System and finally RMS).While these paradigms provide the conceptual framework and the main design guidelines their actual interpretation and implementation has led to a wider set of architectures (Monostori, Váncza & Kumara 2006; Leitão 2009; Parunak 2000; Pěchouček & Mařík 2008).These architectures align the high-level principles with the technological offer and limitations while seeking to address the re-configurability requirements of (Mehrabi, Ulsoy & Koren 2000; Rösiö & Säfsten 2013):module mobility – modules are easy and quick to move and install;“diagnosability” – it is quick to identify the sources of quality and reliability problems;“integrability” – modules are easy to integrate into the rest of the system.“convertibility” – it is easy and quick to switch between existing products and it is easy to adapt the system to future products;scalability – it is easy to enlarge and downsize the production system;“automatibility” – a dynamic level of automation is enabled;modularity – all system elements are designed to be modular;customization – the capability and flexibility of the production system is designed according to the products to be produced in the system.Instant deployment, as addressed in the present chapter directly addresses mobility, “integrability”, “convertibility”, scalability and customization. Mechatronic modularity is a prerequisite and is enforced by the proposed architecture and the considered modular design. “Diagnosability” was not specifically tackled.In this context, the chapter analyses the agent-based architecture related with the Instantly Deployable Evolvable Assembly System (IDEAS) project that is inspired by the Evolvable Assembly System (EAS) paradigm (Ribeiro et al. 2010) as a mechanism to enable fast deployment of mechatronic modules. EAS advocates the use of process-oriented modules and envisions the production system as a collection of processes and the associated interacting agents.The architecture and the related test cases are used to draw the main lessons learned in respect to technological and conceptual implications.In this context, the remainder of this text is organized as follows: section 1.1 discusses the main deployment challenges, section 1.2 details the reference architecture and associated concepts, section 1.3 presents the principal implementation decisions, section 1.4 features the main lessons learned, sections 1.5 discusses the benefits of the proposed approach and finally section 1.6 reflects on the main conclusions.
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| 25. |
- Kleyko, Denis, et al.
(författare)
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Vehicle Classification using Road Side Sensors and Feature-free Data Smashing Approach
- 2016
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Ingår i: 2016 IEEE 19th International Conference on Intelligent Transportation Systems (ITSC). - Piscataway : IEEE. - 9781509018895 - 9781509018888 - 9781509018901 ; , s. 1988-1993
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Konferensbidrag (refereegranskat)abstract
- The main contribution of this paper is a study of the applicability of data smashing - a recently proposed data mining method - for vehicle classification according to the "Nordic system for intelligent classification of vehicles" standard, using measurements of road surface vibrations and magnetic field disturbances caused by passing vehicles. The main advantage of the studied classification approach is that it, in contrast to the most of traditional machine learning algorithms, does not require the extraction of features from raw signals. The proposed classification approach was evaluated on a large dataset consisting of signals from 3074 vehicles. Hence, a good estimate of the actual classification rate was obtained. The performance was compared to the previously reported results on the same problem for logistic regression. Our results show the potential trade-off between classification accuracy and classification method's development efforts could be achieved.
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