Selective catalytic reduction of nitric oxide by propane over vanadia-titania aerogels

An investigation has been carried out of the effect of vanadia loading on the activity and selectivity ofV₂O₅TiO₂ aerogel catalysts, prepared by a two-step procedure, for the reduction of NO by propane. The structure of catalysts have been characterized by laser Raman spectroscopy and XRD measurements. At vanadia loading levels below ca. 4.4 wt%, the vanadia is present in the form of coordinated polymeric species, whereas crystallites of V₂O₅ are formed at higher vanadia contents. At this critical level of 4.4 wt% V₂O₅, the kinetic measurements showed also a maximum in the activity per mass of catalyst which very likely indicated that the coordinated polymeric surface species are more active than crystalline V₂O₅. The selectivity towards the formation of dinitrogen decreased as the loading increased, presumably because of the formation of larger polymeric species and V₂O₅ crystallites, below and above the critical loading level, respectively. For the reduction of NO by propane, titania supported vanadia aerogel catalysts are significantly more active, per mass of catalyst, and more selective towards N₂ formation than conventionalV₂O₅TiO₂ and V₂O₅Al₂O₃ aerogel catalysts, at vanadia loading levels below ca. 11 wt%.     

Micro-patterning of LiPON and lithium iron phosphate material deposited onto silicon nanopillars array for lithium ion solid state 3D micro-battery

The paper deals with the methodology used to form regular pattern of sputtered thin films LiPON/LiFePO₄ material acting respectively as the solid electrolyte and the positive electrode of the lithium ion solid state 3D micro-battery. The micromachining of the silicon periodic nanopillars array (negative electrode of the micro-battery) is also reported. The proposed study clearly demonstrates a breakthrough technology in the field of lithium ion micro-battery as the ecologically friendly LiFePO₄ material has never been evaluated as the positive electrode.     

Low-loss InGaAsP/InP submicron optical waveguides fabricated by ICP etching

The fabrication and characterisation of low-loss InGaAsP/InP optical submicron waveguides made with ICP etching is reported. Their width ranges from 0.2 to 2 /spl mu/m. For the 0.5 /spl mu/m width, the propagation losses at /spl lambda/=1.55 /spl mu/m as low as 4.2 dB/mm have been measured.     

A Highly Efficient Algorithm for Phased-Array mmWave Massive MIMO Beamforming

With the rapid development of the mobile internet and the internet of things (IoT), the fifth generation (5G) mobile communication system is seeing explosive growth in data traffic. In addition, low-frequency spectrum resources are becoming increasingly scarce and there is now an urgent need to switch to higher frequency bands. Millimeter wave (mmWave) technology has several outstanding features—it is one of the most well-known 5G technologies and has the capacity to fulfil many of the requirements of future wireless networks. Importantly, it has an abundant resource spectrum, which can significantly increase the communication rate of a mobile communication system. As such, it is now considered a key technology for future mobile communications. MmWave communication technology also has a more open network architecture; it can deliver varied services and be applied in many scenarios. By contrast, traditional, all-digital precoding systems have the drawbacks of high computational complexity and higher power consumption. This paper examines the implementation of a new hybrid precoding system that significantly reduces both calculational complexity and energy consumption. The primary idea is to generate several sub-channels with equal gain by dividing the channel by the geometric mean decomposition (GMD). In this process, the objective function of the spectral efficiency is derived, then the basic tracking principle and least square (LS) techniques are deployed to design the proposed hybrid precoding. Simulation results show that the proposed algorithm significantly improves system performance and reduces computational complexity by more than 45% compared to traditional algorithms.     

Simulation and Hardware Development of a New Electronic Simulator of Photovoltaic Generators

Photovoltaic simulators are practical and useful tools for the evaluation of photovoltaic energy production system components, avoiding time-consuming and expensive field-testing process. This article presents an original electronic bench simulating a photovoltaic generator system including photovoltaic modules, DC-DC converters, and loads. This new electronic simulator allows the development and optimization of different topologies of generators or different converters. It can replace the load and inverter working under random external parameters. It can be used for works about photovoltaic grid injection as well as stand-alone photovoltaic systems. This simulator constitutes a specific tool for a laboratory to test photovoltaic modules under various temperature and illumination conditions, making transparent many other issues and thus allowing a complete set of simulation parameters not easily and repeatedly available in practice for the development of new photovoltaic generators. For validating the efficiency of the simulator, a detailed analytical study, using the OrCAD® PSpice® software environment of a distributed generator based on a high-voltage DC bus topology, is presented and compared to in situ experimental results achieved with the operational prototype finally developed.     

High thermally induced index variations with short response time in InP/GalnAsP/InP waveguide Schottky diodes

Thermally induced index variations as high as 0.1 were recorded in InP/GaAsInP_1.15/InP waveguide Schottky diodes for 1 W/mm electrical power per electrode length. Pulse response characterisation showed almost 700 ns response time for 1 ms square pulses under forward biased conditions (I = 20 mA, V = 300 mV).     

Studies on the curing behavior,thermal, and mechanical properties of epoxy resin-co-amine-functionalized lead phthalocyanine

A high performance copolymer was prepared by using epoxy (EP) resin as matrix and 3,10,17,24-tetra-aminoethoxy lead phthalocyanine (APbPc) as additive with dicyandiamide as curing agent. Fourier-transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetric analysis (DSC), and thermogravimetric analysis (TGA) were used to study the curing behavior, curing kinetics, dynamic mechanical properties, impact and tensile strength, and thermal stability of EP/APbPc blends. The experimental results show that APbPc, as a synergistic curing agent, can effectively reduce the curing temperature of epoxy resin. The curing kinetics of the copolymer was investigated by non-isothermal DSC to determine kinetic data and measurement of the activation energy. DMA, impact, and tensile strength tests proved that phthalocyanine can significantly improve the toughness and stiffness of epoxy resin. Highest values were seen on the 20 wt% loading of APbPc in the copolymers, energy storage modulus, and impact strength increased respectively 388.46 MPa and 3.6 kJ/m², T_g decreased 19.46°C. TGA curves indicated that the cured copolymers also exhibit excellent thermal properties.     

High‐performance polymeric materials with greatly improved mechanical and thermal properties from cyanate ester/benzoxazine resin reinforced by silane‐treated basalt fibers

This present article investigates the effect of silane‐treated basalt fibers (TBFs) on the morphological, mechanical and thermal properties of cyanate ester/benzoxazine (CE/BOZ) resin composites. The characterization was made using a scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), flexural test, impact strength (IS) test, microhardness test, dynamic scanning calorimetry, and thermogravimetric analysis. The mechanical test results inferred the distinctive improvements in the values of the flexural strength and modulus, IS, and microhardness of the CE/BOZ composites. The thermal stabilities in terms of the T_g, T_5%, T_10%, and T_HRI were appreciably improved and were higher than those of the pure CE/BOZ resin. Data from the SEM and FTIR tests ascertained the good dispersion and adhesion between the TBFs and the resin matrix, which might be behind the significant enhancement in the ultimate performances of the composites, with respect to the distinguished properties of BFs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46283.     

Dynamic behaviour of PV generator trackers under irradiation and temperature changes

Maximum power point trackers (MPPTs) have a decisive role to extract power from the photovoltaic (PV) generators as they have to assume the maximum power output (MPP) whatever are the continuous changes of temperature and irradiation conditions. Therefore, they take a prior place in the global PV system efficiency. These trackers are driven by MPPT algorithms and lot of these MPPT algorithms are proposed in literature. The two most common implemented algorithms for power optimisation are the Perturb and Observe (P&O) and the Incremental of Conductance (IncCond) algorithms, which present a high simplicity of implementation within electronics programmable circuits. With an approach based on realistic parameters such as those found when the generator is integrated in a real photovoltaic installation, the two MPPT techniques are dynamically compared using testing procedures developed with Matlab/Simulink. The study leads us to conclude that both algorithms can be performed for PV exposures in unfavourable but realistic external conditions.