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| 2. |
- Bensow, Rickard, 1972, et al.
(författare)
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Using a PANS Simulation Approach for the Transient Flow around the Japan Bulk Carrier
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this study, a PANS, Partially averaged Navier-Stokes, modelling approach developed based on the k − ω turbulence model has been applied to the flow around the Japan Bulk Carrier. Three different meshes has been employed for a fixed physical resolution for the PANS modelling. The results are encouraging, with small scale flow dynamics being allowed to develop on reasonably small mesh sizes, but more studies are required before reliable predictive simulations can be performed.
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| 3. |
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| 4. |
- Chen, Fu qiang, et al.
(författare)
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Pressure analysis on two-step high pressure reducing system for hydrogen fuel cell electric vehicle
- 2017
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 42:16, s. 11541-11552
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen fuel cell electric vehicle (FCEV) can achieve zero exhaust emission and zero pollution. In order to make FCEV reach a farther travel distance, greater demands are put on its pressure reducing system. In this paper, a two-step high pressure reducing system for FCEV is proposed. The system is made up of two parts, a new high multi-stage pressure reducing valve (HMSPRV) and a multi-stage muffler. As a new system, its feasibility has to be verified. Since the valve opening condition has a great effect on hydrogen flow, pressure reduction and energy consumption, different valve opening conditions are taken as the research point. The flow field analysis of the new HMSPRV is conducted on three aspects: pressure field, velocity field and energy consumption. It can be found that both the pressure reducing and velocity increasing gradients mainly reflect at those throttling components for all valve openings. For energy consumption, in the comprehensive study of flow vortexes and turbulent dissipation rate, it can be found that the larger of the valve opening, the larger of energy consumption. Then, a thermo-fluid-solid coupling analysis is conducted on the new HMSPRV, and it is concluded that the new system meets strength requirement. Furthermore, as the second step of the high pressure reducing system, the flow and pressure fields of multi-stage muffler are investigated. The five-stage muffler is exactly designed to complete the whole pressure reducing process. This study can provide technological support for achieving pressure regulation in the hydrogen transport system of FCEV when facing complex conditions, and it can also benefit the further research work on energy saving and multi-stage flow of pressure reducing devices.
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| 5. |
- Chen, Fei, et al.
(författare)
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Wheat gluten/chitosan blends : A new biobased material
- 2014
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 60, s. 186-197
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Tidskriftsartikel (refereegranskat)abstract
- Wheat gluten and chitosan are renewable materials that suffer from some poor properties that limit their use as a potential replacement of petroleum-based polymers. However, polymer blends based on wheat gluten and chitosan surprisingly reduced these shortcomings. Films were cast from acidic aqueous or water/ethanol solutions of wheat gluten and chitosan. Wheat gluten was the discontinuous phase in the 30-70 wt.% wheat gluten interval investigated. The most homogeneous films were obtained when reducing agents were used (alone or together with urea or glycerol). They consisted mainly of 1-2 mu m wheat gluten particles uniformly distributed in the continuous chitosan phase. Slightly smaller particles were also observed in the water/ethanol solvent system, but together with significantly larger particles (as large as 200 mu m). Both small and large particles were observed, albeit in different sizes and contents, when surfactants (both with and without a reducing agent) or urea (without a reducing agent) were used. The particles were often elongated, and preferably along the film, the most extreme case being observed when the glyoxal crosslinker was used together with sodium sulfite (reducing agent), showing particles with an average thickness of 0.6 mu m and an aspect ratio of 4.2. This film showed the highest transparency of all the blend films studied. For one of the most promising systems (with sodium sulfite), having good film homogeneity and small particles, the mechanical and moisture solubility/diffusivity properties were studied as a function of chitosan content. The extensibility, toughness and moisture solubility increased with increasing chitosan content, and the moisture diffusivity was highest for the pristine chitosan material. It is noteworthy that the addition of 30 wt.% wheat gluten to chitosan reduced the moisture uptake, while the extensibility/toughness remained unchanged.
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| 6. |
- Dán, György, et al.
(författare)
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Challenges in Power System Information Security
- 2012
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Ingår i: IEEE Security and Privacy. - : IEEE Computer Society. - 1540-7993 .- 1558-4046. ; 10:4, s. 62-70
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Tidskriftsartikel (refereegranskat)abstract
- Achieving all-encompassing component-level security in power system IT infrastructures is difficult, owing to its cost and potential performance implications.
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| 7. |
- Di Bari, Chiara, et al.
(författare)
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Laccase-modified gold nanorods for electrocatalytic reduction of oxygen
- 2016
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Ingår i: Bioelectrochemistry. - : Elsevier. - 1567-5394 .- 1878-562X. ; 107, s. 30-36
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Tidskriftsartikel (refereegranskat)abstract
- The multicopper oxidase Trametes hirsuta laccase (ThLc) served as a bioelectrocatalyst on nanostructured cathodes. Nanostructuring was provided by gold nanorods (AuNRs), which were characterized and covalently attached to electrodes made of low-d. graphite. The nanostructured electrode was the scaffold for covalent and oriented attachment of ThLc. The bioelectrocatalytic currents measured for oxygen redn. were as high as 0.5 mA/cm2 and 0.7 mA/cm2, which were recorded under direct and mediated electron transfer regimes, resp. The exptl. data were fitted to math. models showing that when the O2 is bioelectroreduced at high rotation speed of the electrode the heterogeneous electron transfer step is the rate-liming stage. The electrochem. measurement hints a wider population of non-optimally wired laccases than previously reported for 5-8 nm size Au nanoparticle-modified electrode, which could be due to a larger size of the AuNRs when compared to the laccases as well as their different crystal facets.
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| 8. |
- Kanerva, M., et al.
(författare)
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Automatization and stress analysis data of CoCr laser weld fatigue tests
- 2019
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Ingår i: Data in Brief. - : Elsevier. - 2352-3409. ; 26
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Tidskriftsartikel (refereegranskat)abstract
- This work includes raw and analyzed test data when using a recently developed fatigue test method for miniature laser welds in cobalt-chromium (CoCr) alloy joints [1]: 10.1016/j.jmbbm.2019.07.004. The automization of fatigue tests is crucial for saving costs and personnel resources and that is the reason why the atomization threshold and the resulting spectrum data related to CoCr welds are provided here. The finite element method based stress computation output is provided related to shearing-mode tests to support the dataset as a whole. In addition, the compositional data of the parent material and the laser weld are given.
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| 9. |
- Wang, Yue, et al.
(författare)
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Flow-structures Generated by Valve and Piston Motion in an Exhaust Port of a Truck Engine
- 2013
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Ingår i: Proceedings of the 4th International Conference on Jets, Wakes and Separated Flows-IV.
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Konferensbidrag (refereegranskat)abstract
- The exhaust port of a truck internal combustion engine forms the interface between the combustion engine and the turbocharger. Approximately 30-40% of the energy potential is lost in the exhaust gasses after combustion, which can be partially recuperated in a turbocharger. Hence, energy losses in the connection are highly undesired. However, due to the high occurring velocities and the complex geometry, flow separation, flowstructure formation, and secondary flow motion are the major sources of energy losses. Within the exhaust process, the valves open while the piston continues moving in the combustion camber. This process is often analyzed by modeling the piston and valves at fixed locations, but conserving the total mass flow. Using advanced methods, this process can be simulated numerically in a more accurate manner. This study compares Large Eddy Simulation based data, assessing the implied differences due to the choise of method for simulating the exhaust process from an engine cylinder. A simple case using fixed positions for valve and piston is contrasted with the cases where static valve and moving piston, and moving valve and moving piston are considered, respectively. The generated flow phenomena are compared within the cases.
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| 10. |
- Zhiyi, He, et al.
(författare)
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Transfer fault diagnosis of bearing installed in different machines using enhanced deep auto-encoder
- 2020
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Ingår i: Measurement. - : Elsevier. - 0263-2241 .- 1873-412X. ; 152
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Tidskriftsartikel (refereegranskat)abstract
- The collected vibration data with labeled information from bearing is far insufficient in engineering practice, which is challenging for training an intelligent diagnosis model. For this purpose, enhanced deep transfer auto-encoder is proposed for fault diagnosis of bearing installed in different machines. First, scaled exponential linear unit is used to improve the quality of the mapped vibration data collected from bearing. Second, nonnegative constraint is adopted for modifying the loss function to improve reconstruction effect. Then, the parameter knowledge of the well-trained source model is transferred to the target model. Finally, target training samples with limited labeled information are adopted for fine-tuning the target model to match the characteristics of the target testing samples. The proposed approach is applied for analyzing the measured vibration signals of bearings installed in different machines. The analysis results show that the proposed approach holds better transfer diagnosis performance compared with the existing approaches.
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