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101.
The stability of the catalyst used in hydrodeoxygenation (HDO) of biomass-derived oils needs improvement. La has been applied in delaying Al2O3 phase-change under reaction conditions. Lanthanum (0.5–8 wt.%)-γ-alumina was studied as Pt (1 wt.%) carrier aimed at guaiacol (GUA) HDO. Materials characterization included N2 physisorption, X-ray diffraction (XRD), thermal analysis, FTIR, UV–vis, and TPR. Solids pore size (~8–10 nm) was suitable for GUA (kinetic diameter~0.668 nm) hydrotreating. Mixed carriers were amorphous (XRD), suggesting well-dispersed La domains; meanwhile, carbonates/bicarbonates were formed (from CO2) due to the basic surface properties of modified supports (FTIR). That could impart catalyst stability by inhibiting coking through the passivation of Lewis acidity on Al2O3. Pt reducibility increased with La loading in various formulations. However, that was not reflected in enhanced GUA HDO (T = 488 K and P = 3.2 MPa, batch reactor), presumably due to the strong metal–support interaction (SMSI), where LaOx covered the metallic Pt particle surface. GUA HDO on various catalysts was approximated by pseudo-first-order kinetics (integral regime, k), where deviations were observed as La loading increased, presumably by an SMSI state that could affect the rate-determining step of the reaction mechanism. Basic sites provided by rare-earth could contribute to altering HDO reaction pathways as well. At 1 wt.% rare-earth, GUA HDO was maximized (k~25% higher than that on Pt/Al2O3), with that material also exhibiting similar deoxygenation (85%–90% at total GUA conversion) to the latter Pt over pristine alumina. Conversely, both parameters significantly diminished over the catalyst of the highest La content. Materials at low rare-earth concentrations deserve further studies focused on catalyst stability under HDO conditions. 相似文献
102.
Kangzhe He Bin Liu Min Xie Phuc Do Benoit Iung Way Kuo 《Quality and Reliability Engineering International》2021,37(8):3693-3712
With the popularization of big data, an increasing number of discrete event data have been collected and recorded during system operations. These events are usually stored in the form of event logs, which contain rich information of system operations and have potential applications in fault diagnosis and failure prediction. In manufacturing processes, various levels of correlations exist among the events, which can be used to predict the occurrence of failure events. However, two challenges remain to be solved for effective reliability analysis and failure prediction: (1) how to leverage various information from the event log to predict the occurrence of failure events and (2) how to model the effects of multiple correlations on the prediction. To address these issues, this paper proposes a novel reliability model, which integrates Cox proportional hazards (PHs) regression into survival analysis and association rule mining methodology. The model is used to evaluate the probability of failure event, which occurs within a certain period of time conditional on the occurrence history of correlated events. To estimate parameters and predict occurrence of failure events in the model, an effective algorithm is proposed based on piecewise-constant time axis division, Cox PHs model, and maximum likelihood estimation. Unlike the existing literature, our model focuses on the interactions among events. The applicability of the proposed model is illustrated through a case study of a manufacturing company. Sensitivity analysis is conducted to illustrate the effectiveness of the proposed model. 相似文献
103.
Claire Jolly Andres Gomez David Sánchez-Fuentes Dilek Cakiroglu Raïssa Rathar Nicolas Maurin Ricardo Garcia-Bermejo Benoit Charlot Martí Gich Michael Bahriz Laura Picas Adrian Carretero-Genevrier 《Advanced Materials Technologies》2021,6(3):2000831
The development of advanced piezoelectric α-quartz microelectromechanical system (MEMS) for sensing and precise frequency control applications requires the nanostructuration and on-chip integration of this material on silicon material. However, the current quartz manufacturing methods are based on bonding bulk micromachined crystals on silicon, which limits the size, the performance, the integration cost, and the scalability of quartz microdevices. Here, chemical solution deposition, soft-nanoimprint lithography, and top-down microfabrication processes are combined to develop the first nanostructured epitaxial (100)α-quartz/(100)Si piezoelectric cantilevers. The coherent Si/quartz interface and film thinness combined with a controlled nanostructuration on silicon–insulator–silicon technology substrates provide high force and mass sensitivity while preserving the mechanical quality factor of the microelectromechanical systems. This work proves that biocompatible nanostructured epitaxial piezoelectric α-quartz-based MEMS on silicon can be engineered at low cost by combining soft-chemistry and top-down lithographic techniques. 相似文献
104.
Mohamed Boussaa Olivier Barais Gerson Suny Benoit Baudry 《Software Testing, Verification and Reliability》2020,30(1)
Generative software development has paved the way for the creation of multiple code generators that serve as a basis for automatically generating code to different software and hardware platforms. In this context, the software quality becomes highly correlated to the quality of code generators used during software development. Eventual failures may result in a loss of confidence for the developers, who will unlikely continue to use these generators. It is then crucial to verify the correct behaviour of code generators in order to preserve software quality and reliability. In this paper, we leverage the metamorphic testing approach to automatically detect inconsistencies in code generators via so‐called “metamorphic relations”. We define the metamorphic relation (i.e., test oracle) as a comparison between the variations of performance and resource usage of test suites running on different versions of generated code. We rely on statistical methods to find the threshold value from which an unexpected variation is detected. We evaluate our approach by testing a family of code generators with respect to resource usage and performance metrics for five different target software platforms. The experimental results show that our approach is able to detect, among 95 executed test suites, 11 performance and 15 memory usage inconsistencies. 相似文献
105.
Kostantine Katcko Etienne Urbain Franck Ngassam Lalit Kandpal Bhavishya Chowrira Filip Schleicher Ufuk Halisdemir Di Wang Torsten Scherer Damien Mertz Benoit Leconte Nicolas Beyer Daniel Spor Pierre Panissod Arnaud Boulard Jacek Arabski Christophe Kieber Emmanuel Sternitzky Victor Da Costa Michel Hehn François Montaigne Armel Bahouka Wolfgang Weber Eric Beaurepaire Christian Kübel Daniel Lacour Mébarek Alouani Samy Boukari Martin Bowen 《Advanced functional materials》2021,31(15):2009467
The quantum states of nano-objects can drive electrical transport properties across lateral and local-probe junctions. This raises the prospect, in a solid-state device, of electrically encoding information at the quantum level using spin-flip excitations between electron spins. However, this electronic state has no defined magnetic orientation and is short-lived. Using a novel vertical nanojunction process, these limitations are overcome and this steady-state capability is experimentally demonstrated in solid-state spintronic devices. The excited quantum state of a spin chain formed by Co phthalocyanine molecules coupled to a ferromagnetic electrode constitutes a distinct magnetic unit endowed with a coercive field. This generates a specific steady-state magnetoresistance trace that is tied to the spin-flip conductance channel, and is opposite in sign to the ground state magnetoresistance term, as expected from spin excitation transition rules. The experimental 5.9 meV thermal energy barrier between the ground and excited spin states is confirmed by density functional theory, in line with macrospin phenomenological modeling of magnetotransport results. This low-voltage control over a spin chain's quantum state and spintronic contribution lay a path for transmitting spin wave-encoded information across molecular layers in devices. It should also stimulate quantum prospects for the antiferromagnetic spintronics and oxides electronics communities. 相似文献
106.
Rosellyne Serewane Deramne Gisèle Laure Lecomte-Nana Claire Peyratout Benoit Naït-Ali Gado Tchangbedji 《International Journal of Applied Ceramic Technology》2020,17(6):2638-2648
The present study aimed at using plant waste (Musa Paradisiaca) for manufacturing clay-based ceramics in order to promote lower sintering temperature while preserving the properties of use. Two kaolinic-illitic clays (NZ1 and KO) from Central African Republic were used mixed with 1 to 10 mass% of the plant waste (MP). The clays and the waste exhibited accessory phases: quartz and iron oxides, and K2O respectively. MP was collected, dried and sieved (<100 μm) previously to its mixture with clays. According to the sintering behavior of KO and NZ1 derived from thermodilatometry, the densification was obtained after firing at 1200°C. Results showed that open porosity decreased from 35% to 17% with increasing temperature in the range 900 to 1200°C for KO and NZ1. This porosity remained in the range 30%-40% while increasing the MP content (firing at 1000°C for 1h.). The optimized MP content was 3 and 5 mass% for KO and NZ1 clay materials respectively. The compressive strength and thermal conductivities were improved compared to clay samples without MP fired at 1200°C. Moreover a significant decrease in the sintering temperature was achieved, leading to energy saving in line with sustainability issues. 相似文献
107.
A Benoit De Coignac C Bisbal B Lebleu T Salehzada 《Canadian Metallurgical Quarterly》1998,209(1-2):149-156
This study was designed to test the hypothesis that the immune changes seen during in vivo whole body hyperthermia are mediated by elevations in the plasma concentrations of either catecholamines, growth hormone or beta-endorphins. Eight healthy volunteers were immersed in a hot water bath (WI; water temperature 39.5 degrees C) for 2 h during which their rectal temperature rose to 39.5 degrees C. In a single blind, randomized, cross-over study the stress hormone effects were blocked one at a time by administration of propranolol, somatostatin or naloxone; the results were compared to those obtained during saline infusion (control). Blood samples were collected before, at the end of 2 h of WI (body temperature 39.5 degrees C), and 2 h later. Hormone blockade did not abolish the hyperthermia-induced recruitment of natural killer (NK) cells to the blood, and no influence was observed on the percentages or concentrations of any other subpopulations of blood mononuclear cells, except that the number of cluster designation (CD)3+ cells slightly increased after hyperthermia only in the propranolol experiment. Furthermore, the NK cell activity, both unstimulated and interferon-alpha or interleukin-2 stimulated, did not differ from the control situation. It is of interest, however, that somatostatin partly abolished the hyperthermia induced increase in the neutrophil number. Based on these data and previous results showing that growth hormone infusion increases the concentration of neutrophils in the blood, it is suggested that growth hormone is at least partly responsible for hyperthermia induced neutrocytosis. 相似文献
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