Ceria and zirconia modified natural clay based nickel catalysts for dry reforming of methane

Ce and Zr promoted Fe/Cu-modified natural clay based catalysts were prepared and tested in dry reforming of methane (DRM) at temperatures from 600 to 800 °C. The physicochemical properties of these catalysts were analyzed by means of N₂ adsorption, X-ray diffraction (XRD). H₂-temperature programmed reduction (H₂-TPR) and CO₂-temperature programmed desorption (TPD). Ce and Zr promotion resulted in a considerable increase of the catalytic activity. This increase can be mainly ascribed to an improved reducibility of Ni species, together with slightly higher Ni⁰ crystal size, that, on the other hand, also catalyze undesired parallel reactions resulting in carbon formation, such as direct methane decomposition. Both Ce and Zr presence also promoted the presence of weak and medium strength basic sites, which are thought to favor CO₂ adsorption and desorption on the catalyst surface, leading to enhanced catalytic activity.     

A Parallel Concatenated Convolutional-Based Distributed Coded Cooperation Scheme for Relay Channels

In this paper, we investigate a coded cooperation diversity scheme suitable for L-relay channels operating in the soft-decode-and-forward (soft-DF) mode. The proposed scheme is based on parallel concatenated convolutional codes (PCCC). To improve the overall performance through diversity, the coded cooperation operates by sending the systematic and the first parity outputs via L?+?1 independent fading paths. Instead of using only a centralized turbo code system at the source node, we have proposed a DCC scheme, where the first recursive systematic coding is done at both source and relay nodes. At the destination, the received replicas are combined using the maximal ratio combining (MRC). The entire codeword, comprising the MRC sequence and the second parity part, is decoded via the maximum a-posteriori (MAP) algorithm and turbo decoding principle. We analyze the proposed scheme in terms of bit error rate (BER). In fact, we define the explicit upper bounds for error rate assuming Binary phase shift keying (BPSK) transmission for fully interleaved channels with channel state information (CSI). We use the Rayleigh fading channels with independent fading. Our study shows that the full diversity order is achieved when the source-relay link is more reliable than the other links. Otherwise, the diversity decreases. However, in both cases, it is shown that significant performance improvements are possible to achieve over non-cooperative coded systems. Theorical and simulation results are presented to demonstrate the efficacy of the proposed scheme.     

Enhancing confidence in indirect analog/RF testing against the lack of correlation between regular parameters and indirect measurements

The greedy specification testing remains mandatory for analog and radio frequency (RF) integrated circuits because of the accuracy of the sorting based on these measurements. Unfortunately, to be implemented, this kind of testing method often incurs very high costs (expensive instruments, long test time…). A common approach, in the literature, is the so-called indirect/alternate test strategy. This strategy consists in deriving targeted specifications from low-cost Indirect Measurements (IMs). During the industrial test phase, the estimation of regular specifications using IMs is based on a correlation model that has been built previously, during a training phase. Despite the substantial test cost reduction offered by this strategy, its deployment in industry is limited, mainly because of a lack of confidence in the accuracy of estimations made by the correlation model. A solution to increase the confidence in the estimation of specifications using the indirect approach is to implement redundancy in the prediction phase. In this paper, we demonstrate that the redundancy implementation brings more than identifying rare misjudged circuits from a high-correlated model. Indeed redundancy massively increases the accuracy despite of the lack of accurate models that have been assumed in previous implementations of redundant indirect testing. This approach is illustrated on a real case study for which we have experimental measurements on a set of 10,000 devices.     

Characterising the elastic behaviour of fine-grained subgrade soils under traffic loading

Resilient modulus is a measure of the elastic behaviour of subgrade soil under traffic loading. The design thickness of a pavement structure and its predicted performance are highly dependent on subgrade modulus. Characterisation of subgrade resilient modulus involves conducting advanced repeated loading triaxial testing that requires special equipment and technical experience that are not available in many soil laboratories. The objectives of this paper were to characterise the resilient modulus of typical fine-grained subgrade soils and develop design inputs for the Mechanistic-Empirical Pavement Design Guide. The resilient modulus of subgrade soil samples was tested at different levels of moisture content. Results of the laboratory testing were used to develop prediction models for resilient modulus as function of physical properties of the subgrade soil and stress state. The proposed models were compared to those developed under the Long-Term Pavement Performance programme. The results showed that the proposed models provided more reliable predictions with lower root mean square error.     

Developing semantic VR-shops for e-Commerce

Increased bandwidth, cheaper and faster hardware, dedicated technology and the success of e-commerce make VR-shops feasible. VR-shops are similar to the e-shops currently available on the Web, with the difference that the products are visualized as 3D objects in a virtual world. Although VR-shops do not require sophisticated VR technology, they should be very flexible: it should be easy to add, remove and rearrange products; and to add, change or remove functionality. Therefore, an appropriate approach that can be used by a non-VR expert and which provides a short development time and easy maintenance is necessary. Also usability is very important because this is crucial for the success of VR-shops. In this paper, we present an approach to develop VR-shops that meet these requirements. It allows specifying a VR-shop using high-level conceptual specifications and in terms of domain terminology; semantics are captured by ontologies; existing product information can be incorporated; and the actual code is generated.     

Ternary Pt@TiO2/rGO Nanocomposite to Boost Photocatalytic Activity for Environmental and Energy Use

This work explores the effect of ternary nanostructure for the enhanced photocatalytic degradation of pollutants and dyes. One-pot solvothermal-assisted approach was used for producing nanosized Pt@TiO₂ hybrid nanoparticles (NPs) decorated on reduced graphene oxide (rGO) layers. The microstructure, morphology, chemical composition, and optical absorption of the designed photocatalyst was successfully characterized (using XRD, TEM, Raman, UV–visible absorption spectra, and XPS techniques). The ternary Pt@TiO₂-rGO photocatalyst consist of monodisperse quasi-spherical Pt@TiO₂ NPs with an average size of 11 nm deposited on the rGO nanosheets. Furthermore, Pt@TiO₂-rGO was further investigated for the photodegradation of pesticide and dyes under UV and visible light. The ternary Pt@TiO₂-rGO photocatalyst proved a significant improvement on the photodecomposition of pollutants compared to hybrid Pt@TiO₂. The Pt@TiO₂-rGO photocatalyst was found to show seven- and threefold increase in the photocatalytic activity compared to TiO₂ and Pt@TiO₂ NPs, respectively which resulted from the high surface area of rGO and as well as the strong Pt/TiO₂/rGO interactions which ensured excellent properties of charge separation. On the other hand, the ternary photocatalyst exhibited very good recycle and reuse capacity up to five cycles.

     

Familial lymphohistiocytic hemophagocytosis: apropos of a case

In the second of a three-part series, the author draws further on the Sainsbury Centre for Mental Health's Acute Care In-Patient study for a critical look at life as a patient on an acute psychiatric ward.