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[en] Ruthenium-containing catalyst based on an Al-HMS mesoporous aluminosilicate was synthesized, The mesoporous support and the catalyst on its basis were characterized by the methods of low-temperature desorption/adsorption of nitrogen, temperature-programmed desorption of ammonia, transmission electron microscopy, X-ray photoelectron microscopy, and energy-dispersive X-ray fluorescence analysis. The catalyst obtained was examined in the reaction of hydrodeoxygenation of the model compound of bio-oil, furfural, in the presence of water. The reaction was performed at initial hydrogen pressures of 1–7 MPa in the temperature range 200–300°C. It was shown that the catalyst under study exhibits a high activity in the hydrotransformation of furfural: the conversion was 100% in 1 h at a hydrogen pressure of 5 MPa and temperature of 200°C.
[en] A high-pressure flow-mixing isothermal microcalorimeter is used to determine the excess molar enthalpies of five binary systems for ethylformate and (1-propanol, 2-propanol, 1-butanol, 2-butanol, and 1-pentanol) at T=(298.15 and 308.15) K and p=(5 and 10)MPa. The smooth values calculated by Redlich-Kister equation of HmE are also compared with the experimental results
[en] Investigations on the piezoresistive response of composites containing zinc conductive fillers at different concentrations in polydimethylsiloxane (PDMS) polymer matrix are presented here. The composites remain insulating even at high filler concentrations. The piezoresistive behaviour of the Zn-PDMS composites under uniaxial pressure shows the resistivity changes by approximately seven orders of magnitude around 4 MPa pressure. We find that the piezoresistive behaviour of the Zn-PDMS composites can be explained in the framework of electron tunnelling between the metal particles
[en] An easily dismountable arrangement for in situ x‐ray diffraction studies of metal/hydrogen reactions (and other gas/solid reactions) which is usable on any open type of diffractometer is described. Gas pressures to 5.0 MPa (50 atm) and sample temperatures in the range 190–575 K have been used successfully
[en] The interaction between heavy liquid metal, such as LBE, and pressurized water has been analyzed at ENEA Brasimone Research Centre, in order to investigate the evolution of this phenomenon over a wide range of conditions. The study includes an experimental campaign on LIFUS 5 facility and a numerical simulation activity performed with SIMMER III code. The first test of the experimental program was carried out injecting water at 7 MPa and 235 oC in a reaction vessel containing LBE at 350 oC. A pressurization up to 8 MPa was observed in the test section during the short term (about 2 s) of the transient. In the post-test analysis performed with SIMMER III code, two different geometrical models were developed in order to reproduce in the best manner the experimental results and, therefore, to confirm the code's capabilities of reproducing the phenomenology of the LBE-water interaction. The data calculated through both models agreed in a good way with the experimental results, despite the necessary simplifications adopted in the models due to the 2D features of the code.
[en] Using a high-damping thermoplastic as a standard reference material, the purpose of this work is to compare measured values of the complex modulus as determined by dynamic nanoindentation and dynamic mechanical analysis (DMA). Experiments were performed at approximately 22 deg. C and seven frequencies over the range 1-50 Hz. The indentation measurements were performed using a 103 μm diameter flat punch and a newly developed test method that optimizes the accuracy and precision of the measured stiffness and damping. As determined by dynamic nanoindentation, values of the storage modulus and loss factor (tangent delta) ranged from 4.2 to 10.2 MPa, and 0.28 to 1.05, respectively. Over the range 1-25 Hz, DMA confirmed the nanoindentation results to within 15% or better. Collectively, these data and the testing methods used to generate them should help future investigators make more accurate and precise measurements of the dynamic properties of viscoelastic solids using nanoindentation
[en] We calculated the Coulomb failure stress change generated by the 1976 Tangshan earthquake that is projected onto the fault planes and slip directions of large subsequent aftershocks. Results of previous studies on the seismic failure distribution, crustal velocity and viscosity structures of the Tangshan earthquake are used as model constraints. Effects of the local pore fluid pressure and impact of soft medium near the fault are also considered. Our result shows that the subsequent Luanxian and Ninghe earthquakes occurred in the regions with a positive Coulomb failure stress produced by the Tangshan earthquake. To study the triggering effect of the Tangshan, Luanxian, and Ninghe earthquakes on the follow-up small earthquakes, we first evaluate the possible focal mechanisms of small earthquakes according to the regional stress field and co-seismic slip distributions derived from previous studies, assuming the amplitude of regional tectonic stress as 10 MPa. By projecting the stress changes generated by the above three earthquakes onto the possible fault planes and slip directions of small earthquakes, we find that the “butterfly” distribution pattern of increased Coulomb failure stress is consistent with the spatial distribution of follow-up earthquakes, and 95% of the aftershocks occurred in regions where Coulomb failure stresses increase, indicating that the former large earthquakes modulated occurrences of follow-up earthquakes in the Tangshan earthquake sequence. This result has some significance in rapid assessment of aftershock hazard after a large earthquake. If detailed failure distribution, seismogenic fault in the focal area and their slip features can be rapidly determined after a large earthquake, our algorithm can be used to predict the locations of large aftershocks.
[en] Highlights: • Multi-directional vortexes are found in the annulus of flapper–nozzle pilot stage. • CFD results show better agreement to momentum conversation based flow force model. • Conner vortex forces increase with increment of inlet pressure and null clearance. • Smaller flappers are favorable to reduce impact of flow reattachment. • Energy loss increases with increasing of inlet pressure and null clearance. - Abstract: A well understanding on the flow forces and energy loss characteristics in a flapper–nozzle pilot valve is necessarily important in the performance improvement of a two-stage electrohydraulic servo-valve. This paper presents the CFD analysis of flow forces and energy loss characteristics in a flapper–nozzle pilot valve with different null clearances. Five different flapper–nozzle structures with three different null clearances of 0.1 mm, 0.05 mm and 0.033 mm are considered in this analysis. For every flapper–nozzle structure, the systematic CFD simulations of flow forces and energy loss characteristics are performed for seven different flow conditions varying nozzle inlet pressures from 1 MPa to 7 MPa. Experimental measurements are also conducted for energy loss characteristics and then compared with simulated results. Meanwhile, the CFD flow force results are verified with the results of exiting simplified flow force models and vice versa. From each nozzle side, the main flow force acting on the flapper is accompanied by four tiny lateral forces resulted from the impact of radial jet reattachment on the flapper curved surface. For each of given null clearances, the main flow force and lateral forces linearly increase with the increment of nozzle inlet pressure. For the same null clearance, applying larger flapper can give 1.5–13.6% larger lateral force in drag direction and 1.5–10.2% larger lateral force in lift direction compared to deploying smaller flapper. Compared to the main flow force, the magnitudes of the lateral forces on each corner of the flapper are found in the range of 0.8–3.2% in drag direction and 1.6–7.5% in lift direction. For main flow forces, the CFD simulated results show a good agreement with that of flow force model based on momentum conservation. Both existing flow force models are undoubtedly applicable in the prediction of flow forces for small null clearances (less than 0.05). Having a good agreement between each other, both experimental and numerical results show that the energy loss increases with the increment of null clearance and nozzle inlet pressure
[en] Prediction of dryout point is experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap respectively. The annulus with narrow gap is bilaterally heated by AC current power supply. The experimental conditions covered a range of pressure from 0.8 to 3.5 MPa, mass flux of 26.6 to 68.8 kg·m2·s-1 and wall heat flux of 5 to 50 kW·m-2. The location of dryout is obtained by observing a sudden rise in surface temperature. Kutateladze correlation is cited and modified to predict the location of dryout and proved to be not a proper one. Considering in detail the effects of geometry of annuli, pressure, mass flux and heat flux on dryout, an empirical correction is finally developed to predict dryout point in narrow annular gap under low flow condition, which has a good agreement with experimental data. (author)