| 1. |
- Weinstein, John N., et al.
(författare)
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The cancer genome atlas pan-cancer analysis project
- 2013
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 45:10, s. 1113-1120
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Forskningsöversikt (refereegranskat)abstract
- The Cancer Genome Atlas (TCGA) Research Network has profiled and analyzed large numbers of human tumors to discover molecular aberrations at the DNA, RNA, protein and epigenetic levels. The resulting rich data provide a major opportunity to develop an integrated picture of commonalities, differences and emergent themes across tumor lineages. The Pan-Cancer initiative compares the first 12 tumor types profiled by TCGA. Analysis of the molecular aberrations and their functional roles across tumor types will teach us how to extend therapies effective in one cancer type to others with a similar genomic profile. © 2013 Nature America, Inc. All rights reserved.
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| 2. |
- Al-Rawi, Ali, 1985, et al.
(författare)
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A new compact wideband MIMO antenna – the double-sided tapered self-grounded monopole array
- 2014
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 62:6, s. 3365 - 3369
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Tidskriftsartikel (refereegranskat)abstract
- We present a new compact wideband multiple input multiple output (MIMO) antenna—the double-sided 4-port arm-tapered self-grounded monopole array, briefly referred to as the butterfly antenna, in the communication. The antenna is very compact with low correlation between ports and high diversity gain. The genetic algorithm optimization scheme has been employed in the design. Simulation results have been verified against measurements. The measured reflection coefficients at all ports are below -7 dB over 0.5–9 GHz and below -4.5 dB over 0.4–0.5 GHz and 9–15 GHz. The measured correlation coefficients are below 0.4 over 0.4–15 GHz and lower than 0.1 in most of the frequency band. This new MIMO antenna is developed as a transmit antenna in reverberation chambers, and we believe that it will find more applications in other systems, such as micro base station antennas in wireless communication systems.
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| 3. |
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| 4. |
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| 5. |
- Al Mouatamid, Faouzi, 1989, et al.
(författare)
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Towards Evaluation of Post Impact Braking Function in Driving Simulator
- 2013
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Ingår i: Proceedings of the IEEE International Conference on Systems, Man, and Cybernetics, Manchester, United Kingdom, Oct 13-16, 2013.. - 9780769551548 ; , s. 4549-4554
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Konferensbidrag (refereegranskat)abstract
- This paper presents a method to evaluate the vehicle Post Impact Braking function in driving simulator environment. This function is designed to apply automatic braking after an initial impact on the vehicle body. Four representative impact scenarios and three typical driving styles are investigated, assuming Anti-lock Brake System (ABS) is either functioned or malfunctioned. The performance of PIB is quantified by comparing certain post impact states when the function is enabled and disabled. The results show that PIB helps the drivers to lower the risk and severity of secondary collisions with respect to reduced displacements and road leaving speed; while it leads to higher risk for possible side collisions due to increased yaw angle; these influences seem to be more considerable when no ABS is available. Passive drivers are found to gain more benefits than Alert-Skilled drivers that it indicates full-braking can degrade the vehicle steerability and thus the lateral and yaw responses to some extent. © 2013 IEEE.
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| 6. |
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| 7. |
- Al-Rawi, Ali, 1985, et al.
(författare)
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The Double-sided 4-port Bow-tie Antenna: A New Compact Wideband MIMO Antenna
- 2013
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Ingår i: 7th European Conference on Antennas and Propagation, EuCAP 2013, Gothenburg, Sweden, 8-12 April 2013. - 2164-3342. - 9788890701832 ; , s. 3731-3735
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Konferensbidrag (refereegranskat)abstract
- We present a new compact ultra-wideband 4-port antenna for use in MIMO systems, such as in reverberation chambers for OTA measurements. The new antenna is based on the self-grounded bow-tie antenna with a very compact size. The design was done through an optimization by employing the genetic algorithm in order to obtain low reflection coefficient and mutual coupling between ports. The designed antenna has an embedded radiation efficiency higher than -0.35 dB, reflection coefficient below -7 dB, mutual coupling between ports below - 12.5 dB (in most frequencies below -20 dB), over a frequency range of 0.4–15 GHz.
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| 8. |
- Han, Guangye, et al.
(författare)
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Hydration of the oxygen-evolving complex of photosystem II probed in the dark-stable S1 state using proton NMR dispersion profiles
- 2014
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; :16, s. 11924-11935
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Tidskriftsartikel (refereegranskat)abstract
- The hydration of the oxygen-evolving complex (OEC) was characterized in the dark stable S1 state of photosystem II using water R1(ω) NMR dispersion (NMRD) profiles. The R1(ω) NMRD profiles were recorded over a frequency range from 0.01 MHz to 40 MHz for both intact and Mn-depleted photosystem II core complexes from Thermosynechococcus vulcanus (T. vulcanus). The intact-minus-(Mn)-depleted difference NMRD profiles show a characteristic dispersion from approximately 0.03 MHz to 1 MHz, which is interpreted on the basis of the Solomon-Bloembergen-Morgan (SBM) and the slow motion theories as being due to a paramagnetic enhanced relaxation (PRE) of water protons. Both theories are qualitatively consistent with the ST = 1, g = 4.9 paramagnetic state previously described for the S1 state of the OEC; however, an alternative explanation involving the loss of a separate class of long-lived internal waters due to the Mn-depletion procedure can presently not be ruled out. Using a point-dipole approximation the PRE-NMRD effect can be described as being caused by 1-2 water molecules that are located about 10 Å away from the spin center of the Mn4CaO5 cluster in the OEC. The application of the SBM theory to the dispersion observed for PSII in the S1 state is questionable, because the parameters extracted do not fulfil the presupposed perturbation criterion. In contrast, the slow motion theory gives a consistent picture indicating that the water molecules are in fast chemical exchange with the bulk (τw < 1 μs). The modulation of the zero-field splitting (ZFS) interaction suggests a (restricted) reorientation/structural equilibrium of the Mn4CaO5 cluster with a characteristic time constant of τZFS = 0.6-0.9 μs.
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| 9. |
- Huang, Yang, 1985-, et al.
(författare)
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The water R1(ω) NMRD profiles of a hydrated protein from molecular dynamics simulation
- 2013
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : RSC Publishing. - 1463-9076 .- 1463-9084. ; 15:33, s. 14089-14097
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Tidskriftsartikel (refereegranskat)abstract
- The hydration of a protein, peroxiredoxin 5, is obtained from a molecular dynamics simulation and compared with the picture of hydration which is obtained by analysing the water proton R1 NMRD profiles using a generally accepted relaxation model [K. Venu, V.P. Denisov and B. Halle, J. Am. Chem. Soc. 119,3122(1997)]. The discrepancy between the hydration pictures derived from the water R1(ω 0)-NMRD profiles and MD is relevant in a discussion of the factors behind the stretched NMRD profile, the distribution of orientationalorder parameters and residence times of buried water used in the NMRD model.
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| 10. |
- Jacobson, Bengt J H, 1962, et al.
(författare)
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Potential effectiveness of a stability control system for passenger cars after an initial side impact
- 2014
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Ingår i: FISITA 2014 World Automotive Congress - Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- Vehicle multiple-event accidents constitute 1/4-1/3 of all severe accidents. The present paper studies the control of the vehicle’s abnormal motion after being hit by another vehicle. The potential effectiveness of such a stability control system is estimated through accident data analysis and vehicle dynamics simulation. Only side impacts were simulated, but engineering judgments were made to project the effectiveness potential prediction on the total traffic work. Assuming ESC-like control (closed loop control on yaw rate, using wheel brakes) it is found that the function has potential to mitigate accident for up to 10-9 cars per driven km, or up to 0.1% of the cars in the accident database. While assuming Post Impact Stability Control by steering (closed loop control on yaw angle and path deviation, using steering), the corresponding figures are approximately ten times higher.
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| 11. |
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| 12. |
- Jian, Qiuchi, 1984, et al.
(författare)
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Detection of breathing and heartbeat by using a simple UWB radar system
- 2014
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Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014. - 2164-3342. - 9788890701849 ; , s. 3078-3081
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Konferensbidrag (refereegranskat)abstract
- We present the development on an ultra-wideband (UWB) radar system and its signal processing algorithms for detecting human breathing and heartbeat in the paper. The UWB radar system consists of two (Tx and Rx) antennas and one compact CMOS UWB transceiver. Several signal processing techniques are developed for the application. The system has been tested by real measurements. .
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| 13. |
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| 14. |
- Liu, Ting, 1985-
(författare)
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Air-pocket transport in conjunction with bottom-outlet conduits for dams
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Undesired air entrainment in bottom outlet conduits of dams may cause pressure transients, leading to conduit vibrations, blowback, discharge pulsation and even cavitation, and jeopardize the operational safety. Due to design limitations or construction costs, it is impossible to create an air free environment in a pressurized pipe. Therefore, it is essential to understand the air transport in enclosed pipes in order to provide guidance in bottom outlet design and operation. The commonly used criterion of the air-pocket movement in pipe flow is the water flow velocity for starting moving an air pocket, the so-called critical velocity. In this thesis, the classical Volume of Fluid (VOF) model combined with the k-ε turbulence model is adopted for the computation of the critical velocity of a 150-mm pipe. The computed critical velocities are compared with the experimental results. The governing parameters investigated in this study include pipe slope and diameter, wall shear stress and air-pocket volume. Meanwhile, the carrying capacity (air-pocket velocity/ flow velocity) at all pipe slopes are analyzed. The simulation results of air pockets with different volumes in the bottom outlet conduit of Letten Dam in Sweden are presented in this study. Moreover, experimental study was conducted to measure the critical velocity for a 240-mm Plexiglas pipe. The results are in agreement with the experiments performed by HR Wallingford (HRW) in 2003 in terms of the effects of pipe slope and air-pocket volume; however, the critical Froude pipe number is slightly smaller in this study. In rough pipes, a larger critical velocity is required compared with that in the smooth pipe. The removal mechanism in the rough pipe involves the successive loss of air caused by turbulence. This explains that the air-pocket size, with the dimensionless air-pocket volume n < 0.015, has little impact on the critical velocity for the rough pipe. In addition, roughness has little impact on the air-pocket velocity when it moves upstream in the downward inclined pipe. The trapped air bubbles most likely remain permanently in the rough pipe.
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| 15. |
- Liu, Ting, 1985-
(författare)
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Modelling air―water flows in bottom outlets of dams
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- If air is entrained in a bottom outlet of a dam in an uncontrolled way, the resulting air pockets may cause problems such as blowback, blowout and loss of discharge capacity. In order to provide guidance for bottom outlet design and operation, this study examines how governing parameters affect air entrainment, air-pocket transport and de-aeration and the surrounding flow structure in pipe flows. Both experimental and numerical approaches are used.Air can be entrained into the bottom outlet conduit due to vortex formation at the intake if the intake submergence is not sufficient. The influent of the intake entrance profiles and channel width on the critical submergence were studied in the experiment.The experimental study was performed to investigate the incipient motion of air pockets in pipes with rectangular and circular cross sections. The critical velocity is dependent on pipe slope, pipe diameter, pipe roughness and air-pocket volume. If the pipe is horizontal, air removal is generally easier in a rectangular pipe than in a circular pipe. However, if the pipe is downward-inclined, air removal is easier in a circular pipe.When a bottom outlet gate opens, air can become entrained into the conduit in the gate shaft downstream of the gate. Using FLUENT software, the transient process of air entrainment into a prototype bottom outlet during gate opening is simulated in three dimensions. The simulations show in the flow-pattern changes in the conduit and the amount of air entrainment in the gate shaft. The initial conduit water level affects the degree of air entrainment. A de-aeration chamber is effective in reducing water surface fluctuations at blowout.High-speed particle image velocimetry (HSPIV) were applied to investigate the characteristics of the flow field around a stationary air pocket in a fully developed horizontal pipe flow. The air pocket generates a horseshoe vortex upstream and a reverse flow downstream. A shear layer forms from the separation point. Flow reattachment is observed for large air pockets. The air―water interface moves with the adjacent flow. A similarity profile is obtained for the mean streamwise velocity in the shear layer beneath the air pocket.
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| 16. |
- Lu, B., et al.
(författare)
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Reusability based on life cycle sustainability assessment : Case study on WEEE
- 2014
-
Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271.
-
Konferensbidrag (refereegranskat)abstract
- Reuse is one of the key strategies of Waste Electrical and Electronic Equipment (WEEE) recycling system in China. Reuse can help realize eco-efficient and sustainable WEEE management, with environmentally friendly materials recovery. At present, reusability of products and components is determined only by the products functional situation or the economic cost benefit analysis. It does not cover all the three pillars of sustainability, including environment, economy and society. In this study, the emerging integrated method, Life Cycle Sustainability Assessment (LCSA), is employed to measure reusability of typical electrical and electronic products and components. The results of case studies show that, LCSA based reusability of typical electrical and electronic products and components will help improve WEEE management policy.
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| 17. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Accuracy and Potential Use of a Developed CFD-pyrolysis Model for Simulating Lab-scale Bio Oil Production
- 2012
-
Ingår i: The 20th EU BC&E Online Proceedings 2012. - 9788889407547 ; , s. 953-959
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The paper describes development of a CFD¬pyrolysis model using an Eularian-Eularian framework with an implemented pyrolysis reaction model. The CFD¬pyrolysis model is used to simulate the bubbling fluidized bed reactor integrated in a new experimental fast pyrolysis process for bio oil production. The model is compared to experiments in aspect of outlet gas composition, temperature and bed height. Tar behavior and yield of bio oil are illustrated and a parametric study investigates impact of flow rate and temperature on bio oil yield. The results show a tolerable fit compared to measurements and reasonable tendencies in the parametric study.
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| 18. |
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| 19. |
- Mellin, Pelle, 1985-, et al.
(författare)
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CFD Modelling of Heat Supply in Fluidized Bed Fast Pyrolysis of Biomass
- 2014
-
Ingår i: Proceedings of the 10th International Conference on Computational Fluid Dynamics in the Oil & Gas, Metallurgical and Process Industries (CFD 2014). - 9788214057416
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper investigates the heat supply to the fast pyrolysis process, by addition of oxygen in the fluidizing gas. Since the technology will be further developed, a solution for the heat supply in a large-scale reactor must be conceived, which is one option to achieve the primary target: to operate with as little extra heat as possible.Corrections for the granular bed material and the biomass particles are implemented in the simulation. User Defined Functions (UDF) is extensively used to describe interactions of heat and momentum between the phases and a chemistry model is employed to describe the chemical reactions after pyrolysis.The results are preliminary; however, the oxygen clearly reacts to provide heat. Primarily the secondary tar reacts and a loss of about 30% organic liquid yield is the result in this simulation, at an equivalence ratio of 0.026.If heat only can be recovered from the bed zone, through the bed material, then a higher equivalence ratio than what was investigated in this paper would be needed.If heat can be recovered from the whole reactor then a slight injection of oxygen would result in an autothermal system; which means the necessary heat to generate and pre-heat steam would be available.Temperature instability in the freeboard prevented investigation of higher equivalence ratios, which should be pursued in further work.
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| 20. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Computational fluid dynamics modeling of biomass fast pyrolysis in a fluidized bed reactor, using a comprehensive chemistry scheme
- 2014
-
Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 117:Part A, s. 704-715
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Tidskriftsartikel (refereegranskat)abstract
- The CFD modeling for fast pyrolysis has previously focused on the major pyrolysis products; liquid, charand gas. This paper introduces a new approach to biomass pyrolysis; integrating a complex scheme of reactions including formation of such components as levoglucosan. The 3-D simulation takes into account the complex breakdown of each biomass subcomponent, the fluid dynamics of the process as well as the heat and momentum transfer of three Eulerian phases.The pyrolysis products include reference species that reflects the composition of the bio oil, gas fraction and char fraction. A number of reactions are in addition applied to account for the thermal cracking of tar compounds and the final compositions are compared to experimental yields. The results show that the predicted pyrolysis products reflect the experimental yields satisfactorily, apart from the water content which is under predicted. Most importantly though, the approach is computationally feasible and it should be useful for future work.
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| 21. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Processing of biomass to Hydrocarbons – using a new catalytic steam pyrolysis route
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Obtaining renewable transportation fuel has been identified as one of the main challenges for a sustainable society. Catalytic pyrolysis followed by hydrotreatment has been demonstrated as one possible route for producing transportation fuels. Using steam in this process could have a number of benefits as given by our research effort. For this paper, we will show that a catalyst together with steam prolongs the activity of the catalyst by preventing coking. This means that both steam and catalyst mutually benefits the deoxygenation. The presented mass and energy balance shows that up to 40% of the calorific value of biomass remains in the deoxygenated oil, on dry basis. This is in contrast to the mass yield, which for the same case was 25%; meaning that the oil is of significantly higher quality with a high content of hydrocarbons. In addition, CFD studies have shown steam is able to redistribute the heat flux and provide more uniform operating conditions compared to for example nitrogen. In conclusion, this route using steam shows promise for displacing fossil transportation fuels, by upgrading of the liquid in existing refineries or next-generation bio refineries. In additional support of this, we have published a number of papers describing conventional fast pyrolysis using steam, CFD modeling for further understanding and experimental work using a combination of steam and firstly a bimetallic catalyst (Ni, V) then a metal modified HZSM5 catalyst (Ni, V, Zeolite, Binder). This paper connects all these individual studies and provides further understanding of the role of steam and the role of steam in combination with a catalyst, in the fast pyrolysis process.
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| 22. |
- Nam, Youngwoo, 1983, et al.
(författare)
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Quantum Hall effect in graphene decorated with disordered multilayer patches
- 2013
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:233, s. 233110-
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Tidskriftsartikel (refereegranskat)abstract
- Quantum Hall effect (QHE) is observed in graphene grown by chemical vapour deposition using platinum catalyst. The QHE is even seen in samples which are irregularly decorated with disordered multilayer graphene patches and have very low mobility (
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| 23. |
- Nam, Youngwoo, 1983, et al.
(författare)
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Unusual thermopower of inhomogeneous graphene grown by chemical vapor deposition
- 2014
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 104:2, s. 021902 -
-
Tidskriftsartikel (refereegranskat)abstract
- We report on thermopower (TEP) and resistance measurements of inhomogeneous graphene grown by chemical vapor deposition (CVD). Unlike the conventional resistance of pristine graphene, the gate-dependent TEP shows a large electron-hole asymmetry. This can be accounted for by inhomogeneity of the CVD-graphene where individual graphene regions contribute with different TEPs. At the high magnetic field and low temperature, the TEP has large fluctuations near the Dirac point associated with the disorder in the CVD-graphene. TEP measurements reveal additional characteristics of CVD-graphene, which are difficult to obtain from the measurement of resistance alone.
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| 24. |
- Paas, Ruth, 1985, et al.
(författare)
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Pedestrian shoulder and spine kinematics in full-scale PMHS tests for human body model evaluation
- 2012
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Ingår i: 2012 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, Dublin:12 through14 September 2012. ; , s. 730-750
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Konferensbidrag (refereegranskat)abstract
- Tools such as human body models are required to show the benefit of restraints needed to reduce risk of injuries and fatalities for pedestrians. To assess the biofidelity of these tools, representative, detailed validation data are required. One aim was to investigate shoulder and spine response in pedestrian/vehicle collisions by analysing new and existing post mortem human subject (PMHS) full-scale tests. Furthermore, assessment was performed whether the specific loading conditions in these PMHS tests were similar to existing component tests and representative of real-life accidents. A full-scale PMHS test was conducted for detailed 6DOF analysis, and three tests were re-analysed. The hands were not tied together in any of the tests, different leg positions were used. To compare loading conditions with real life, accident data was analysed. Beginning with pelvis impact, the spine was drawn inferiorly while the head rotated contralaterally. Before elbow-to-vehicle contact, the ipsilateral scapula rotated upwards, elevated and adducted. Following elbow contact it elevated rapidly until shoulder-to-vehicle impact. Elbow contact appeared to affect the thorax and head kinematics; the head rotated towards the vehicle worsening the head impact. The results underline the necessity to collect additional 6DOF elbow, scapula and spine data in full-scale pedestrian impacts.
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| 25. |
- Raza Zaidi, Syed Hasan, 1977, et al.
(författare)
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Measurement of Radiation Efficiency of Multiport Antennas With Feeding Network Corrections
- 2012
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 11, s. 89-92
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Tidskriftsartikel (refereegranskat)abstract
- Multiport antennas are widely used and often integrated with active components, such as low noise amplifiers, in antenna systems. It is important to verify and evaluate the radiation efficiency of a multiport antenna before being integrated in the system. When the radiation efficiency of a multiport antenna is measured, a multiport feeding network is always needed in order to provide the same antenna excitation as it is during its operation after being integrated in the system. This letter addresses how to measure the radiation efficiency of a multiport antenna excluding the losses in the feeding network used for the measurement, particularly when the impedance match between the antenna and the feeding network is not perfect. A rigorous feeding network correction approach is introduced by using measurement data of the radiation efficiency of the whole antenna with feeding network and the mbi S-matrices of both the feeding network and the antenna. As an example of this approach, the radiation efficiency of a multiport Eleven antenna has been determined and verified against the simulated results.
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| 26. |
- Raza Zaidi, Syed Hasan, 1977, et al.
(författare)
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Wideband Compact 4-Port Dual Polarized Self-Grounded Bowtie Antenna
- 2014
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 62:9, s. 4468-4473
-
Tidskriftsartikel (refereegranskat)abstract
- We present a dual-polarized self-grounded bowtie antenna. The antenna is mechanically simple and wideband. One of the characteristics is its flexibility: it can be used either as a 4-port antenna in multiple-input-multiple-output (MIMO) systems or as a directional 2-port dual-polarized antenna in radar or sensor systems. The latter application requires a balun. The 4-petal geometry of the antenna has been optimized for the best matching to 50 coax over 1.5-3 GHz. Both simulated and measured results are presented to verify the design. The antenna radiates over parts of the bandwidth similar to four Huygens source, one from each petal, each having directivity close to 4.8 dBi.
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| 27. |
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| 28. |
- Sun, Fei, 1985-
(författare)
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Transformation Optics for Controlling DC Magnetic Field
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Based on the form-invariant of Maxwell’s equations under coordinate transformations, we extend the theoryof transformation optics to transformation magneto-statics, which can design magnets through coordinatetransformations. Some novel DC magnetic field illusions created by magnets (e.g. rescaling magnets,cancelling magnets and overlapping magnets) are designed and verified by numerical simulations. Ourresearch will open a new door to designing magnets and controlling DC magnetic fields.
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| 29. |
- Wang, C., et al.
(författare)
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Injection of solid biomass products into the blast furnace and its potential effects on an integrated steel plant
- 2014
-
Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; , s. 2184-2187
-
Konferensbidrag (refereegranskat)abstract
- This study is to investigate different types of biomass products' injection into the blast furnace (BF) to replace pulverized coal injection (PCI). The biomass products covered in the study are charcoal, torrefied material and wood pellets on the basis of Swedish forests. The modelling work has been performed in a specialized BF model. The modelling results show that charcoal has the significant effects on the BF operation. PCI can be replaced fully by charcoal, and only limited amount of torrefied material and wood pellets can be injected into BF. For the studied BF, the annual CO2 emission reduction potential from the replaced amount of PCI when injecting charcoal, torrefied material and wood pellets are about 1140 kton, 260 kton and 230 kton, respectively. In addition, a possible energy saving can be achieved for charcoal injection. A slightly higher P content in the hot metal may occur when injecting torrefied material.
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| 30. |
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| 31. |
- Wu, Yueshi, 1985-
(författare)
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Computational Fluid Dynamics Modeling of Biomass Gasification in Fixed-bed Reactors Using Highly Preheated Agent
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biomass gasification is considered to be one of the most promising energy recovery technologies for the widespread utilization of biomass. Mathematical models have been developed to understand the gasification process inside gasifiers. As the oldest type of gasifier, fixed-bed gasifiers have been widely studied by using zero-dimensional and one-dimensional models; however, only a limited number of two-dimensional models for this type of reactor can be found in existing literature.The primary goal of this thesis is to develop a two-dimensional computational fluid dynamics (2-D CFD) model for fixed-bed gasifiers that considers the complex kinetic mechanisms, the flow field, and a series of chemical reactions inside gasifiers. The model was evaluated for both downdraft and updraft fixed-bed gasifiers through comparison with existing data from a demonstration-scale high temperature agent gasification (HTAG) system. The results demonstrated that this model can reasonably predict the performance of fixed-bed gasifiers when high-temperature air/steam is used as the gasifying agent. The performances of fixed-bed gasifiers were also discussed under the framework of HTAG technology. This CFD model is a potentially powerful tool for analyzing the performance sensitivity of a fixed-bed gasifier, which will further aid in the design and operation of this type of system.Biomass should be produced in an ecologically and economically sustainable manner. Therefore, the optimization of the gasification process was further studied to improve gasification performance and efficiency. A zero-dimensional kinetic-free model was introduced based on an updraft fixed-bed gasifier. A thermodynamic analysis was conducted based on the first and second laws of thermodynamics for various S/B ratios and preheating temperatures of the gasifying agent. A practical operating region for the HTAG process was proposed for industrial applications.According to the results, the HTAG technology relies on an external heat source and uses super-heated air combined with steam; this results in a limited need for feedstock combustion and produces syngas with a high H2 fraction and a low tar content. Based on energy and exergy efficiency analyses from a HTAG application, plasma melting of municipal solid waste (MSW), HTAG technology is demonstrated to be preferable from environmental and energy (exergy) efficiency perspectives.
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| 32. |
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| 33. |
- Yang, Derong, 1985, et al.
(författare)
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A nonlinear post impact path controller based on optimised brake sequences
- 2012
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 50:SUPPL. 1, s. 131-149
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates brake-based path control of a passenger vehicle, aimed at reducing secondary collision risk following an initial impact in a traffic accident. Previous results from numerical optimisation showed that, at varying severity levels of post-impact states, there exist three identifiable components within the optimal control strategy so as to reduce the lateral deviation. The paper presents a path controller, based on nonlinear optimal control theory, that incorporates the three components. It is shown that friction adaptation may be implemented in a very efficient manner; the controller deals with different levels of road friction by scaling the dynamic variables from a fixed reference level. The approach provides an algorithm for adapting switching thresholds between the different components of the controller. In this study it is verified that the controller can deal with a wide range of kinematic conditions, and compares favorably with previous results of open-loop trajectory optimisation.
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| 34. |
- Yang, Derong, 1985, et al.
(författare)
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An Optimal Path Controller Minimizing Longitudinal and Lateral Deviations after Light Collisions
- 2013
-
Ingår i: Proceedings of 16th International IEEE Conference on Intelligent Transportation Systems, Hague, The Netherlands, Oct 6-9, 2013.. - 2153-0009. ; , s. 899-904
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Konferensbidrag (refereegranskat)abstract
- This paper considers the problem of path control for a road vehicle immediately after it is disturbed by an initial light collision. Assuming that the driver cannot adequately control the vehicle during such an event, active chassis controls such as front steering and friction brakes are applied to minimize the risk and/or severity of a secondary impact, e.g. with roadside objects. Statistics have shown that traffic accidents where a vehicle suffers more than one collision comprise about 25% of all passenger car accidents. In this paper, the crash risk for secondary collisions is formulated via a cost function and an optimal controller is developed. The cost function may penalize both longitudinal and lateral deviations from the point of initial impact, and is assumed here to be a time-integrated quadratic function of position. For closed-loop implementation this is further approximated using a simple terminal velocity cost, the direction of which represents predicted locations of maximum risklharm. A six-state quasi-linear path controller is developed using nonlinear optimal control theory. Example cases are presented, verifying approximate equivalency between cost functions and satisfactory control performance compared with independent open-loop numerical optimizations.
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| 35. |
- Yang, Derong, 1985, et al.
(författare)
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Application of An Optimal Vehicle Path Controller on Curved Roads after Collisions
- 2014
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Ingår i: 12th International Symposium on Advanced Vehicle Control AVEC'14.
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Konferensbidrag (refereegranskat)abstract
- This paper considers the problem of vehicle path control directly after an initial light collision. Accidentstatistics have shown that 25% of all passenger car accidents have at least one vehicle exposed to subsequentcollisions after the initial one. In previous research, an optimal path controller has been designed to minimizethe collision risk in terms of the maximum lateral deviation from the original path on a straight road. Thepresent paper further develops the controller for minimizing the maximum off-tracking on curved roads. Asimple cost function which penalizes a combination of longitudinal and lateral terminal velocity is applied toapproximate the original cost function, i.e. maximum off-tracking in curve. The weighting factor in the costfunction is adaptable in connection with the prescribed road curvature and vehicle post-impact kinematicsstates. This cost function is found to be favourable for the closed-loop implementation of the optimal control.Results from numerical optimizations have shown the equivalence between the two different cost functions,and satisfactory performance of the closed-loop controller.
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| 36. |
- Yang, Derong, 1985, et al.
(författare)
-
Closed-loop Controller for Post-Impact Vehicle Dynamics Using Individual Wheel Braking and Front Axle Steering
- 2012
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Ingår i: Proceedings of the 2012 International Conference on Advanced Vehicle Technologies and Integration, Changchun, China, July, 2012..
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Konferensbidrag (refereegranskat)abstract
- This paper presents a vehicle path controller forreducing the maximum lateral deviation (Ymax) after an initialimpact in a traffic accident. In previous research, a quasilinearoptimal controller (QLOC) was proposed and applied to asimple vehicle model with individually controlled brake actuators.QLOC uses nonlinear optimal control theory to provide a semiexplicitapproximation for optimal post impact path control, andin principle can be applied to an arbitrary number of actuators.The current work extends and further validates the controlmethod by analyzing the effects of adding an active front axlesteering actuator, as well as increasing the fidelity of the vehiclemodel. As expected, performance with respect to Ymax can beimproved by the additional actuator, though the extent of theimprovement is found to depend on the post-impact kinematicstates. The applicability of QLOC is confirmed by comparisonwith new results from open-loop numerical optimization.
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| 37. |
- Yang, Derong, 1985, et al.
(författare)
-
Closed-loop Controller for Post Impact Vehicle Dynamics Using Individual Wheel Braking and Front Axle Steering
- 2014
-
Ingår i: International Journal of Vehicle Autonomous Systems. - 1471-0226 .- 1741-5306. ; 12:2, s. 158-179
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a vehicle path controller for reducing the maximum lateral deviation (Ymax) after an initial impact in a traffic accident. In previous research, a Quasi-Linear Optimal Controller (QLOC) was proposed and applied to a simple vehicle model with individually controlled brake actuators. QLOC uses non-linear optimal control theory to provide a semiexplicit approximation for optimal post-impact path control, and in principle can be applied to an arbitrary number of actuators. The current work extends and further validates the control method by analysing the effects of adding an active front axle steering actuator at different post-impact kinematics, as well as increasing the fidelity of the vehicle model in the closed-loop controlled system. The controller performance is compared with the results from openloop numerical optimisation which uses the same vehicle model. The inherent robustness properties of the QLOC algorithm are demonstrated by its direct application to an independent high-fidelity multi-body vehicle model. Towards real-time implementation, the algorithm is further simplified so that the computational efficiency is enhanced, whereas the performance is shown not to be degraded.
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| 38. |
- Yang, Derong, 1985, et al.
(författare)
-
Minimizing Vehicle Post Impact Path Lateral Deviation Using Optimized Braking And Steering Sequences
- 2014
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Ingår i: International Journal of Automotive Technology. - : Springer Science and Business Media LLC. - 1229-9138 .- 1976-3832. ; 15:1, s. 7-17
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the optimal control of a vehicle, after a light impact during a traffic accident. To reduce the risk of secondary events, the control target is set: to minimize the maximum lateral deviation from the initial path. In previous analysis path control was achieved by the active control of individual wheel braking. The present paper examines potential benefits from the additional control of front steering angles. Numerical optimization is used to determine optimal control sequences for both actuator configurations. It is found that steering provides significant control benefits, though not for all post-impact kinematics. For all cases considered, the optimal control operates at the boundary of the control domain of available forces and moments. This domain is expanded when steering is available, and there exists an expanded range of conditions for which coupled control of yaw moments and lateral forces is the most effective control strategy. The sensitivity of vehicle response to the individual actuator controls is studied; it reveals this sensitivity is related to the actuator bandwidth and the lack of any dynamic cost in the longitudinal direction. This motivates a further analysis which includes longitudinal and lateral dynamics in the cost function. This is broadly related to real-world crash risks. Further, different versions of such cost functions are compared as a basis for implementation in a closed-loop controller.
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| 39. |
- Yang, Derong, 1985, et al.
(författare)
-
Optimized brake-based control of path lateral deviation for mitigation of secondary collisions
- 2011
-
Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 225:D12, s. 1587-1604
-
Tidskriftsartikel (refereegranskat)abstract
- This paper considers brake-based lateral control of a passenger vehicle, for reducing secondary collision risk following an initial impact in a traffic accident. Since secondary collisions are associated with deviations from the original travel path, the control problem is formulated via brake control sequences that minimize lateral path deviation. Optimal sequences are found not to conform to any simple control mode; sometimes all brakes are released, sometimes all wheels are locked, or the brakes may be applied in differential mode. In general, the optimal strategy combines several such actuation modes, and analysis shows it is related to the utilization of instantaneous vehicle force and moment capacity, indicating that a closed-loop control strategy may be developed based on the real-time estimation of tyre force limits during the post-impact event. Yaw motion control is related to response discontinuity and multiple equilibria found in the optimal response - a small change in initial yaw velocity generates large changes in the ensuing vehicle motion and thus in the aimed equilibrium point of the vehicle's orientation. Overall it is found that braking control strongly influences the post-impact path of the impacted vehicle, and may therefore form the basis of a practical system for avoiding secondary collisions in future traffic accidents.
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| 40. |
- Yang, Derong, 1985, et al.
(författare)
-
Post-Impact Vehicle Path Control by Optimization of Individual Wheel Braking Sequences
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper the effectiveness of brake-based path control under typical post-impact conditions is investigated. Accident analysis shows that the secondary collision in multiple-events accidents can be mitigated or avoided by reducing the lateral path deviation. In this study a numerical optimization scheme is formulated to minimize the maximum deviation from the original intended lane using individual wheel braking. The optimal braking sequences are analyzed and dynamic switching between several strategies is found to be necessary. In particular, two distinguished strategies are qualified at the vehicle body level. The results can be used to develop a robust closed-loop control strategy.
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| 41. |
- Yang, Derong, 1985
(författare)
-
Post Impact Vehicle Path Control in Multiple Event Accidents
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recent statistics show that multiple-event accidents (MEAs) possess an increasing fraction of all vehicle traffic accidents. They are characterized by having at least one vehicle subjected to more than one harmful event, such as collision with another vehicle. MEAs now comprise approximately 25% of all passenger vehicle accidents. The scope of the research presented in this thesis is to develop vehicle Post Impact Control (PIC) strategies in order to avoid or mitigate any secondary events in MEAs.To characterize the problematic areas for PIC, an analysis was conducted in an in-depth accident database: cars which have potentials to gain safety benefits from PIC were identified; several representative accident cases were selected; post impact vehicle dynamics were analyzed taking the overall accident scenario into account; benefit measures were determined for each case. It was found that reduction of kinetic energy and path lateral deviation would be mostly beneficial under post impact circumstances.To analyze the capability of influencing vehicle path after the first impact, trajectory optimization was done using braking sequences which minimize the maximum path lateral deviation. It was found that effective control across the very wide range of post impact kinematic conditions can be significantly achieved by switching between three sub-strategies established on vehicle body level. The resulting interventions were found to be qualitatively different to classical Electronic Stability Control (ESC) systems, and also to interventions proposed in other studies on post-impact control which prioritize the minimization of any large post impact yaw rate or longitudinal velocity.For closed-loop implementation of the path controller, one of the three sub-strategies is particularly challenging: control of global lateral force and yaw moment simultaneously. A closed-loop quasi-linear optimal controller (QLOC) was proposed and verified against the trajectory optimization results.
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| 42. |
- Yang, Derong, 1985, et al.
(författare)
-
Quasi-linear Optimal Path Controller Applied to Post-Impact Vehicle Dynamics
- 2012
-
Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 13:4, s. 1586-1598
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates brake-based path control ofa passenger vehicle, aimed at reducing secondary collision risk,following an initial impact in a traffic accident. This risk maybe reduced if lateral deviations from the preimpact path can beminimized, at least on straight roads. Numerical optimizationhas previously shown that coupled control of lateral forces andyaw moments can be applied to effectively minimize such pathdeviations. In this paper, a quasi-linear optimal controller (QLOC)is proposed to achieve this control target. QLOC uses nonlinearoptimal control theory to provide a semiexplicit approximationfor optimal post impact (PI) path control. The controller designmethod is novel, combining linear costate dynamics with nonlinearconstraints due to tire friction limits. A fully closed-loop formof the controller is presented; it is applicable to multiple-eventaccidents occurring on straight roads, including adaptive estimationof the time instant at maximum deviation. The controllerachieves performance that is very similar to that of open-loopnumerical optimization. Assuming that the vehicle remains on theroad surface after the impact and that the brake actuators remainoperational, it is verified that the path controller is effective overa wide range of PI kinematic conditions. It is expected that theQLOC controller will prove useful in other cases where chassissystems directly control the vehicle path, e.g., in crash-imminentavoidance maneuvers.
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| 43. |
- Yang, Derong, 1985
(författare)
-
Vehicle Dynamics Control after Impacts in Multiple-Event Accidents
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Accidents statistics show that multiple-event accidents (MEAs) represent a considerable and increasing proportion of all vehicle traffic accidents. MEAs are characterized by having at least one vehicle subjected to more than one harmful event. MEAs now comprise approximately 25% of all passenger vehicle accidents. This thesis aims to make systematic progress towards developing a vehicle Post Impact Control (PIC) function so as to avoid or mitigate any secondary event in MEAs.To characterize the vehicle motion control problems for PIC, a number of MEAs from an accident database were analyzed. Post impact vehicle dynamics were studied considering the overall accident scenarios of exemplar cases. Reduction of kinetic energy and path lateral deviation were found to be most critical and beneficial for the vehicles after impacts. To understand the mechanism of influencing the post impact vehicle path, numerical optimization was applied to minimize the maximum path lateral deviation. It was found that effective control can be achieved across a wide range of kinematic conditions, by switching between three sub-strategies established at vehicle body level. Results also showed that active front-axle steering, in addition to individual-wheel braking, provides significant control benefits, although not for all post-impact kinematics.For closed-loop design of the path control, a Quasi-Linear Optimal Controller (QLOC) was proposed and verified with the numerical optimization results. The design method is novel – it well combines the linear co-states dynamics and nonlinear constraints due to tyre friction limits. The algorithm was further adapted to penalize both longitudinal and lateral path deviations, using a generalized cost function.To verify the function with driver interaction, a number of exploratory methods were investigated regarding the driver safety, as well as the capability and accuracy to reproduce the real-world post-impact vehicle kinematics. A scheme of the function design for real-time implementation was proposed and applied to the experiments in a driving simulator environment.
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| 44. |
|
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| 45. |
- Yang, Jian, 1960, et al.
(författare)
-
Arrangements and Applications of Self-grounded Antennas
- 2014
-
Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014, The Hague, The Netherlands 6-11 April 2014. - 2164-3342. - 9788890701849 ; , s. 79 - 83
-
Konferensbidrag (refereegranskat)abstract
- The self-grounded antenna is a new type of compact ultra-wideband antennas with simple geometries. One of the characteristics of this type antenna is its high flexibility: the configuration of the antenna can be arranged in many different ways for different applications. In this paper, we overview the typical arrangements of the self-grounded antennas, and their performance for different applications.
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| 46. |
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| 47. |
- Yang, Jian, 1960, et al.
(författare)
-
Several new ultra-wideband antenna systems for radio telescopes and industry sensor imaging process
- 2012
-
Ingår i: 2012 14th International Conference on Electromagnetics in Advanced Applications, ICEAA 2012. Cape Town, 2 - 7 September 2012. - 9781467303354 ; , s. 1281-1284
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an overview of several ultrawideband (UWB) antenna systems recently developed at Chalmers for applications in future UWB radio telescopes and industry sensor imaging process.
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| 48. |
- Yang, Lei, 1985-
(författare)
-
Hole Transport Materials for Solid-State Mesoscopic Solar Cells
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The solid-state mesoscopic solar cells (sMSCs) have been developed as a promising alternative technology to the conventional photovoltaics. However, the device performance suffers from the low hole-mobilities and the incomplete pore filling of the hole transport materials (HTMs) into the mesoporous electrodes. A variety of HTMs and different preparation methods have been studied to overcome these limitations. There are two types of sMSCs included in this doctoral thesis, namely solid-state dye-sensitized solar cells (sDSCs) and organometallic halide perovskite based solar cells.Two different types of HTMs, namely the small molecule organic HTM spiro-OMeTAD and the conjugated polymer HTM P3HT, were compared in sDSCs. The photo-induced absorption spectroscopy (PIA) spectra and spectroelectrochemical data suggested that the dye-dye hole conduction occurs in the absence of HTM and appears to be of significant importance to the contribution of hole transport.The PIA measurements and transient absorption spectroscopy (TAS) indicated that the oxidized dye was efficiently regenerated by a small molecule organic HTM TPAA due to its excellent pore filling. The conducting polymer P3HT was employed as a co-HTM to transfer the holes away from TPAA to prohibit the charge carrier recombination and to improve the hole transport.An alternative small molecule organic HTM, MeO-TPD, was found to outperform spiro-OMeTAD in sDSCs due to its more efficient pore filling and higher hole-mobility. Moreover, an initial light soaking treatment was observed to significantly improve the device performance due to a mechanism of Li+ ion migration towards the TiO2 surface.In order to overcome the infiltration difficulty of conducting polymer HTMs, a state-of-the-art method to perform in-situ photoelectrochemical polymerization (PEP) in an aqueous micellar solution of bis-EDOT monomer was developed as an environmental-friendly alternative pathway with scale-up potential for constructing efficient sDSCs with polymer HTMs.Three different types of HTMs, namely DEH, spiro-OMeTAD and P3HT, were used to investigate the influence of HTMs on the charge recombination in CH3NH3PbI3 perovskite based sMSCs. The photovoltage decay measurements indicate that the electron lifetime (τn) of these devices decreases by one order of magnitude in the sequence τspiro-OMeTAD > τP3HT > τDEH.
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| 49. |
- Yu, Yinan, 1985, et al.
(författare)
-
A new UWB radar system using UWB CMOS chip
- 2011
-
Ingår i: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9788882020743 ; , s. 771-775
-
Konferensbidrag (refereegranskat)abstract
- A complete ultra-wideband (UWB) radar system is presented in this paper. The radar system consists of UWB CMOS radar transceiver and two compact directional UWB antennas for the purpose of transmission and reception. Different possible applications were investigated in the domain of ranging and tracking using this system along with fast and efficient signal processing algorithms. The results obtained are very promising for this new technology.
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| 50. |
- Yu, Yinan, 1985, et al.
(författare)
-
Compact UWB Indoor and Through-Wall Radar with Precise Ranging and Tracking
- 2012
-
Ingår i: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; 2012, s. Article ID 678590-
-
Tidskriftsartikel (refereegranskat)abstract
- Ultrawideband (UWB) technology has many advantages compared to its narrowbandcounterpart in many applications. We present a new compact low-cost UWB radar forindoor and through-wall scenario. The focus of the paper is on the development of the signalprocessing algorithms for ranging and tracking, taking into account the particular propertiesof the UWB CMOS transceiver and the radiation characteristics of the antennas. Theoreticalanalysis for the algorithms and their evaluations by measurements are presented in the paper. The ranging resolution of this UWB radar has achieved 1-2 mm RMS accuracy for a movingtarget in indoor environment over a short range, and Kalman tracking algorithm functionswell for the through-wall detection.
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