An efficient bifunctional Ni-Nb2O5 nanocatalysts for the hydrodeoxygenation of anisole

The Ni-Nb₂O₅ nanocatalysts have been prepared by the sol–gel method, and the catalytic hydrodeoxygenation (HDO) performance of anisole as model compound is studied. The results show that Nb exists as amorphous Nb₂O₅ species, which can promote Ni dispersion. The addition of Nb₂O₅ increases the acidity of the catalyst. However, when the content of niobium is high, there is an inactive Nb-Ni-O mixed phase. The size and morphology of Ni grains in catalysts are different due to the difference of Nb/Ni molar ratio. The Ni_0.9Nb_0.1 sample has the largest surface area of 170.8 m²·g^-1 among the catalysts prepared in different Nb/Ni molar ratios, which is mainly composed of spherical nanoparticles and crack pores. The HDO of anisole follows the reaction route of the hydrogenation HYD route. The Ni_0.9Nb_0.1 catalyst displayed a higher HDO performance for anisole than Ni catalyst. The selectivity to cyclohexane over the Ni_0.9Nb_0.1 sample is about 10 times that of Ni catalyst at 220 ℃ and 3 MPa H₂. The selectivity of cyclohexane is increased with the increase of reaction temperature. The anisole is almost completely transformed into cyclohexane at 240 ℃, 3 MPa H₂ and 4 h.     

Mechanical and resistometry studies on Al-Zn alloys

Al+1.3, Al+3.2, Al+5.2 and Al+11.5 at % Zn alloys were studied by means of micro-hardness and the electrical resistivity measurements. The results showed that the additive hardness contribution of the solute zinc and the zinc precipitates to the microhardness of pure aluminium can be given by HV_s=22.2C _Zn ^1.36 and HV_p=164C _Zn ^1.05 , respectively. On the other hand, the contributions of electron-phonon scattering and electron-impurity scattering to the resistivity increase atT> has been obtained. In addition, the characteristic temperatures of Guinier-Preston zone formation, the dissolution of the zones, the precipitation of the solute zinc atoms and the dissolution of the precipitates have been determined.     

Characterizations of El Minia limestone for manufacturing paper filler and coating

This study introduces a contribution of using the El Minia carbonate filler pigment for paper making. El Minia limestone samples were grind to very fine powder ranging from 2 to 10 μm, for utilization in paper filler/coating industry, with using testing techniques; X-ray fluorescence (XRF), X-ray diffraction (XRD), Scanning electron microscopy (SEM). The limestone assessment includes more examinations to confirm the suitability of studied samples for alkaline paper manufacture such as, chemical analysis and physical properties, brightness, refractive index, oil & water absorption, moisture content, water soluble, surface area and soundness tests as per paper industry standards.     

Development of a numerically efficient approach based on coupled CFD/FEM analysis for virtual fire resistance tests—Part B: Deformation process of a steel structure

In the present study, the structural analysis of a three-parted steel door during a fire resistance test was examined by FEM simulation. The structural analysis is part of a coupled CFD/FEM simulation approach developed for the prediction of fire resistance tests. The basis of this follow-up work was the calculated temperature in the test specimen from CFD to predict the thermal stresses, deformation and gap formation between the door parts. The spatial information of the temperature in the test specimen was exported. Subsequently, the thermal expansion of the door and the resulting stresses and gaps were calculated. To validate the FEM simulation, the deformation of the steel door was observed. It was found that the simulation predicted the deformation of the steel door in close accordance to the measurement. The maximum displacement was found in the centre of the construction with 141 mm, whereas the simulation predicted a value of 133 mm. In addition to the deformation of the door, also the prediction of the gap formation was validated against the flue gas leakage. The first flue gas exit occurred already after 120 seconds, which was in spatial and temporal conjunction with the maximum gap predicted in the simulation.     

Adaptive coordination control strategy of renewable energy sources, hydrogen production unit, and fuel cell for frequency regulation of a hybrid distributed power system

The ‘mismatch losses’ problem is commonly encountered in distributed photovoltaic (PV) power generation systems. It can directly reduce power generation. Hence, PV array reconfiguration techniques have become highly popular to minimize the mismatch losses. In this paper, a dynamical array reconfiguration method for Total-Cross-Ties (TCT) and Series–Parallel (SP) interconnected PV arrays is proposed. The method aims to improve the maximum power output generation of a distributed PV array in different mismatch conditions through a set of inverters and a switching matrix that is controlled by a dynamic and scalable reconfiguration optimization algorithm. The structures of the switching matrix for both TCT-based and SP-based PV arrays are designed to enable flexible alteration of the electrical connections between PV strings and inverters. Also, the proposed reconfiguration solution is scalable, because the size of the switching matrix deployed in the proposed solution is only determined by the numbers of the PV strings and the inverters, and is not related to the number of PV modules in a string. The performance of the proposed method is assessed for PV arrays with both TCT and SP interconnections in different mismatch conditions, including different partial shading and random PV module failure. The average optimization time for TCT and SP interconnected PV arrays is 0.02 and 3 s, respectively. The effectiveness of the proposed dynamical reconfiguration is confirmed, with the average maximum power generation improved by 8.56% for the TCT-based PV array and 6.43% for the SP-based PV array compared to a fixed topology scheme.     

Natural citric acid (lemon juice) assisted synthesis of ZnO nanostructures: Evaluation of phase composition,morphology, optical and thermal properties

In recent years, because of their excellent electrocatalytic action and applications in different fields, metal oxide nanostructures have received massive consideration from scientists. Zinc oxide nanostructures are useful materials for a range of sensing applications and possess admirable electrocatalytic properties and stability. The current research presents the natural citric acid assisted synthesis of ZnO nanostructures and their structural, optical, morphological and thermal properties. X-ray diffraction was studied for the phase assessment of as prepared (Z1) and annealed ZnO (Z2) nanostructures and the crystallite sizes of the Z1 and Z2 samples were also located in the range between 35 nm and 38 nm. FESEM and TEM experiments were carried out to explore the surface features of Z1 and Z2 samples. The polycrystalline existence of the samples is demonstrated by the hexagonal, cubic and spherical shaped ZnO nanostructures. The energy band gap of Z1 and Z2 samples was determined (3.16 eV for Z1 and 3.12 eV for Z2) from the UV spectrum. The impact of annealing treatment on the thermal stability of ZnO nanostructures was studied and the main peak was observed for the Z1 sample at ~249 °C and for the Z2 sample at ~289 °C.     

Utilization of granite sludge for production of cordierite ceramics by direct coagulation casting

In this work, an attempt to produce cordierite ceramics from granite sludge waste, talc and alumina was performed by direct coagulation casting process. To optimize the conditions for cordierite formation, three mix-compositions were firstly prepared by processing the starting materials in different conditions. The first mix was prepared by firing the mix of granite sludge, talc and alumina up to 1300 °C while the second and third mixes were fabricated by firing alumina and talc at 1300 °C or 1350 °C, respectively, then the granite sludge was added. Both batches were fired at different temperatures. According to the percentage of formed cordierite, the third mix was selected to be solidified by direct coagulation casting method followed by sintering at different temperatures. The casted cordierite was examined by thermal analysis while the sintered bodies were tested for their physical, mechanical and electrical properties. The results indicated that the pre-heating of alumina and talc at 1350 °C (third mix) enhanced the formation of cordierite and some amounts of spinel. For the casted sintered specimens, the porosity was decreased with increasing the sintering temperature. Also, there was an increase in compressive strength for the samples sintered up to 1250 °C. The dielectric constant values were varied between 4.5 and 5.89 while the dielectric loss was varied between 2 × 10^?3 and 7 × 10^?3, at room temperature.     

Design of Defected Ground Structure Band Stop/Band Pass Filters Using Dielectric Resonator

Wireless Personal Communications - MultiACK-Slotted Floor Acquisition Multiple Access (MultiACK-SFAMA) is a medium access control (MAC) protocol that has been proposed for underwater acoustic...     

Automated Design Error Debugging of Digital VLSI Circuits

Journal of Electronic Testing - As the complexity and scope of VLSI designs continue to grow, fault detection processes in the pre-silicon stage have become crucial to guaranteeing reliability in...