Las locuciones son unidades léxicas complejas que se caracterizan por su alto grado de idiomaticidad y su inmutabilidad formal, razón por la cual para los estudiantes de lengua extranjera (LE), ...comprender y aprender estas expresiones estereotipadas no es una tarea fácil, por lo tanto, se suelen quedar en un segundo plano en la clase de LE. En el presente artículo, tenemos como objetivo investigar el tratamiento que reciben las locuciones en los manuales de ELE más recientes con el fin de revelar las deficiencias que existen.
Several circuit-level techniques are described which are used to reduce or cancel thermal noise and break the so-called kT/C limit. kT/C noise describes the total thermal noise power added to a ...signal when a sample is taken on a capacitor. In the first proposed technique, the sampled thermal noise is reduced by altering the relationship between the sampling bandwidth and the dominant noise source, providing a powerful, new degree of freedom in circuit design. In the second proposed technique, thermal noise sampled on an input capacitor is actively canceled using an amplifier, so that the noise at the amplifier output can be controlled independently of input capacitor size. Measurements from two test chips are presented which demonstrate sampled thermal noise power reduction of 48% and 67%, respectively, when compared with conventional kT/C-limited sampling.
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-TPR and FTIR were used to characterize the nature of the Cu ions present in the Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ...ions at two distinct cationic positions in the SSZ-13 framework.
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-TPR and FTIR were used to characterize the nature of the Cu ions present in the Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions at two distinct cationic positions in the SSZ-13 framework.
A 14-bit SAR ADC is presented that achieves 73.6 dB SNDR at 80 MSPS while using a 1.2-V-only supply. In order to overcome throughput limitations common to conventional SAR ADCs, several techniques ...are proposed. First, a flash sub-ADC is utilized to resolve the 5 MSBs quickly prior to SAR sequential decisions of the LSBs. Second, the DAC operation is time-interleaved by a factor of 2, increasing speed while allowing a single comparator to be shared between all DACs. Third, fully on-chip DAC charge redistribution allows the DAC settling time to be improved by more than an order of magnitude compared to conventional techniques. Finally, the ADC is fully self-timed through the use of a replica timer circuit in order to take full advantage of the fast DAC settling and comparator decisions. Despite the increased speed, the ADC consumes only 31.1 mW and occupies a core area of 0.55 mm 2 .
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► Ammonia adsorbed to both Brønsted and Lewis acid sites of Cu-SSZ-13 can react with NOx molecules. ► Copper-bound ammonia reacts faster with NOx than proton-adsorbed one and produces ...N2 selectively. ► High N2 formation selectivities were observed with NO+O2, and NO2+O2 oxidizing gas mixtures, while NH3 oxidation also produced N2O when NO2 was the only oxidizing agent present.
DRIFT spectroscopy combined with mass spectrometry was used to investigate the oxidation of adsorbed ammonia by NO2, NO+O2 and NO2+O2 on a copper ion exchanged SSZ-13 (Cu-SSZ-13) zeolite. Compared with both NO2 and NO, the adsorption of ammonia is much stronger on the Cu-SSZ-13 zeolite. Two adsorbed ammonia species were found over the Cu-SSZ-13 zeolite studied here, notably ammonia on Brønsted acid sites (proton) and ammonia on Lewis acid sites (copper ions). These adsorbed ammonia species present different activity profiles and selectivity to N2 during NH3 oxidation. The results obtained suggest that ammonia adsorbed onto copper ions in Cu-SSZ-13 is more active at low temperatures than proton-adsorbed NH3, and give rise to a higher selectivity to N2. The formation of N2O is associated primarily with the reaction of NOx with proton-adsorbed NH3 via the formation and subsequent thermal decomposition of NH4NO3.
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Coastal ship tracking is used in many applications, such as autonomous navigation, maritime rescue, and environmental monitoring. Many general object-tracking methods based on deep learning have been ...explored for ship tracking, but they often fail to accurately track ships in challenging scenarios, such as occlusion, scale variation, and motion blur. We propose a memory-guided perception network (MGPN) to address these issues. MGPN has two main innovative improvements. The dynamic memory mechanism (DMM) in the proposed method stores past features of the tracked target to enhance the model’s feature fusion capability in the temporal dimension. Meanwhile, the hierarchical context-aware module (HCAM) enables the interaction of different scales, global and local information, to address the scale discrepancy of targets and improve the feature fusion capability in the spatial dimension. These innovations enhance the robustness of tracking and reduce inaccuracies in the bounding boxes. We conducted an in-depth ablation study to demonstrate the effectiveness of DMM and HCAM. Finally, influenced by the above two points, MGPN has achieved state-of-the-art performance on a large offshore ship tracking dataset, which contains challenging scenarios such as complex backgrounds, ship occlusion, and varying scales.
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An oversampled continuous-time (CT) pipeline ADC clocked at 9 GHz achieving 1.125-GHz bandwidth and -164 dBFS/Hz average small-signal noise density is presented. In contrast to traditional ...discrete-time (DT) pipeline ADCs, the system processes the signals in CT form throughout all the pipeline stages and thus sampling-induced artifacts such as aliasing and high-peak ADC driving current are mitigated. Despite the oversampled nature of the ADC, its digitization bandwidth is on par with that of traditional non-interleaved DT pipeline ADCs since CT signal processing is not constrained by settling time requirements. The ADC was fabricated in a 28-nm CMOS process technology and consumes 2.3 W.
The adsorption of CO and NO over Cu-SSZ-13 zeolite catalysts, highly active in the selective catalytic reduction of NO(x) with NH(3), was investigated by FTIR spectroscopy, and the results obtained ...were compared to those collected from other Cu-ion exchanged zeolites (Y,FAU and ZSM-5). Under low CO pressures and at room temperature (295 K), CO forms monocarbonyls exclusively on the Cu(+) ions, while in the presence of gas phase CO dicarbonyls on Cu(+) and adsorbed CO on Cu(2+) centers form, as well. At low (cryogenic) sample temperatures, tricarbonyl formation on Cu(+) sites was also observed. The adsorption of NO produces IR bands that can be assigned to nitrosyls bound to both Cu(+) and Cu(2+) centers, and NO(+) species located in charge compensating cationic positions of the chabasite framework. On the reduced Cu-SSZ-13 samples the formation of N(2)O was also detected. The assignment of the adsorbed NO(x) species was aided by adsorption experiments with isotopically labeled (15)NO. The movement of Cu ions from the sterically hindered six member ring position to the more accessible cavity positions as a result of their interaction with adsorbates (NO and H(2)O) was clearly evidenced. Comparisons of the spectroscopy data obtained in the static transmission IR system to those collected in the flow-through diffuse reflectance cell points out that care must be taken when general conclusions are drawn about the adsorptive and reactive properties of metal cation centers based on a set of data collected under well defined, specific experimental conditions.
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•Many Rh catalysts were tested for N2O decomposition under diesel conditions.•Rh/CeO2 is the only catalyst with good activity in a wet feed after aging.•Aging does not deactivate ...Rh/CeO2 but significantly increases its activity.•Removal O2 from the catalyst has been demonstrated to be the rate limiting step.
Numerous Rh catalysts were evaluated for N2O decomposition for automotive applications. Some Rh-containing spinel materials exhibit excellent fresh activities in the absence of H2O but become inactive after hydrothermal aging or when tested in a wet feed. Rh catalysts supported on zeolites can be very active in a dry feed even after aging but are extremely sensitive to H2O. Rh/CeO2 is an exceptional catalyst for this reaction in the presence of both H2O and O2. Hydrothermal aging (750 °C/20 h) significantly increases its activity. A similar activity enhancement was found by calcining the support before Rh impregnation. XPS results show a surface enrichment of Rh species on the aged Rh/CeO2 catalyst relative to the fresh catalyst. Aberration corrected STEM images reveal that Rh is buried in the bulk on the fresh catalyst and pulled out onto the surface of the support after thermal treatments. All catalysts are inhibited by H2O with the zeolite-based Rh catalysts being the worst. The aged Rh/CeO2 catalyst is less sensitive to H2O relative to others. DRIFTS data show that H2O sensitivity is related to catalyst hydrophilicity; a high coverage of OH groups on a catalyst reduces its N2O decomposition activity. H2-TPR results show that a Rh/CeO2 catalyst can be readily reduced at < 100 °C. On a reduced Rh/CeO2 catalyst, near complete N2O conversion can be obtained with a lean feed at 250 °C for a duration equivalent to its oxygen storage capacity. The N2O-DRIFTS experiments over a pre-reduced Rh/CeO2 catalyst show that Ce3+ sites are quickly oxidized to Ce4+ upon contacting N2O at room temperature, resulting N2 and adsorbed O, with the latter being an efficient oxidizer. Based on these results, a N2O decomposition mechanism is proposed for the Rh/CeO2 catalyst.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The biaxial loading properties of carbon-fiber-reinforced polymer (CFRP) are critical for evaluating the performance of composite structures under the complex stress state. There are currently no ...standardized specimens for the CFRP biaxial experiments. This work developed a new design criterion for the cruciform specimen coupled with the Hashin criterion. The finite element analysis was conducted to investigate the effect of geometric parameters on the stress distribution in the test area. The embedded continuous laying method (ECLM) was proposed to achieve the thinning of the center of the test region without introducing defects. The manufacturing quality of the cruciform specimens was verified by the ultrasonic C-scanning test. The biaxial test platform consisting of the biaxial loading system, digital image correlation (DIC) system, strain electrical measurement system, and acoustic emission detection system was constructed. The biaxial tensile tests under different biaxial loading ratios were conducted. The results showed that the biaxial failure efficiently occurred in the test area of the cruciform specimens designed and manufactured in this paper. The failure modes and morphology were characterized using macro/microscopic experimental techniques. The biaxial failure envelope was obtained. The results can be used to guide the design of composite structures under biaxial stress.
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