Influence of multiple gas inlet jets on fluidized bed hydrodynamics using Particle Image Velocimetry and Digital Image Analysis

A rectangular fluidized bed setup was developed to study the evolution of inlet gas jets located at the distributor. Experiments were conducted with varying distributor types and bed media to understand the motion of particles and jets in the grid-zone region of a fluidized bed. Particle Image Velocimetry and Digital Image Analysis were used to quantify the parameters that characterize these jets. A grid-zone phenomenological model was developed to compare these parameters with those available in the literature. It was determined from this study that jet penetration length behavior is consistently different for fluidization velocities below and above the minimum fluidization. For velocities above minimum fluidization, jet lengths were found to increase more rapidly with increase in orifice velocity than for operating conditions below minimum fluidization.     

Influences of polymer matrix melt viscosity and molecular weight on MWCNT agglomerate dispersion

In order to study the influence of melt viscosity and molecular weight on nanotube dispersion and electrical volume resistivity, three different polycarbonates (PCs) varying in molecular weight were melt compounded with 1 wt% multiwalled carbon nanotubes (MWCNTs, Baytubes^® 150 HP) using a small-scale compounder. The experiments were performed at constant melt temperature but at varying mixing speeds, thereby applying different magnitudes of shear stress. Light transmission microscopy was used to access the state of agglomerate dispersion, and electrical resistivities of the composites were measured on pressed plates. The results indicate that with increasing matrix viscosity the agglomerate dispersion gets better when using constant mixing conditions but worse considering comparable shear stress values. To study the effect of molecular weight, in a second set of experiments melt temperatures were adjusted so that all PCs had similar viscosity and mixing was performed at constant mixing speed. As investigated on two viscosity levels, the composites based on the low molecular weight matrix showed smaller sized un-dispersed primary agglomerates as compared to composites with higher molecular weight matrices, highlighting the role of matrix infiltration into primary nanotube agglomerates as the first step of dispersion. The resistivity values of composites prepared using low viscosity matrices were lower than those of composites from high viscosity matrix.     

Formulation development and optimization of alpha ketoglutarate nanoparticles for cyanide poisoning

The purpose of this research work was to formulate and evaluate alpha ketoglutarate nanoparticles as dry powder inhaler for treatment of cyanide poisoning. Non-polymeric particles were prepared by nano-precipitation technique using various stabilizers. Selection of co-solvent and stabilizer was a key to produce stabilized particles. A combination of lutrol F68 and PVA as a crystal growth inhibitor seems to be best in achieving minimum particle size of 110.2 nm. On the basis of preliminary trials a Box-Behnken statistical design was employed to study the effect of independent variables, drug concentration (X₁), stirring speed (X₂), stirring time (X₃), PVA concentration (X₄), poloxomer concentration (X₅) and volume of co-solvent (X₆) on average particle size. Particle size varied from 110 to 875 nm depending upon the significant terms. Optimized formulation was predicted at drug concentration (50 μg/ml), stirring speed (640 rpm), stirring time (1 min), PVA concentration (1%), poloxomer concentration (1.69%) and volume of co-solvent (30 ml) with 104.6% experimental validity. The nanosized particles were further characterized by X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FT-IR) analysis. The results of particle characterization indicate that there was no physical disparity when compared with the commercial α-KG sample.     

Safe design fatigue life of CNT loaded woven GFRP laminates under fully reversible axial fatigue: application of two-parameters Weibull distribution

ABSTRACT

In this work, constant amplitude fully reversible tension-compression (t-c) fatigue behaviour of two-phased epoxy/glass fibre and three-phased MWCNT/epoxy/glass fibre laminates modified with 0.5 and 1.0 vol.-% of MWCNTs is presented. Addition of 0.5 and 1.0 volume fraction of nanoparticles in the matrix phase increased the fatigue strength of the laminates by approximately 10% and 4%, respectively. GFRP laminates subjected to quasi-static compression and t-c fatigue were found to fail by matrix crushing and shearing contrary to matrix crushing, ply splitting and kink band failure presented by CNT modified laminates. Such mechanisms were due to additional matrix toughening imparted by the nanotubes. Two-parameters Weibull distribution was implemented for the statistical evaluation of the fatigue life data. For safety limits of the test results, S-N curves with reliability levels of 0.99, 0.5, 0.368 and 0.10 were produced using Weibull shape and scale parameters.     

PBT/Thermoplastic Elastomer Blends—Mechanical,Morphological, and Rheological Characterization

The blends of poly(butylene terephthalate) (PBT) with thermoplastic elastomer (TPE) at a blending composition of 10–30 wt.% TPE were prepared with an objective to enhance impact toughness of PBT. Two different grades of PBT were selected based on carboxyl end group and viscosity. Melting behavior, mechanical properties, morphology, and rheology of the blends were studied. At all levels of TPE, PBT showed negligible changes in its melting and crystallization temperature; however, percentage crystallinity decreased with an increase in the amount of thermoplastic elastomer. The notched as well as unnotched Izod impact strength of PBT increased with the incorporation of TPE, the increase being about 47% (unnotched) and 54% (notched) with low molecular weight PBT and 18% (unnotched) and 70% (notched) with high molecular weight PBT at 10% TPE level. The tensile strength and tensile modulus of the blends decreased steadily as the weight percent of TPE increased. Analysis of the tensile data using predicted theories indicated that at TPE levels of 30 wt.%, the blends cannot take excessive stress because the interfacial adhesion is lowered. Small angle light scattering (SALS) studies of the samples indicated the decreased rate of crystallization and, hence, an increase in spherulitic radius in the presence of TPE. The increasing incorporation of TPE in PBT/TPE blends increased the shear thinning behavior and hence eased processability.     

Efficient spectral response of locally uncertain linear systems

It is difficult to model any real dynamical system with fully deterministic characteristics and yet, capture its behavior reasonably. Randomness arises from many sources, such as uncertain material properties, assumptions involved in structural modeling, and the stochastic nature of input forces. Thus, the random vibration analysis of systems with uncertain parameters is a crucial component of structural design and optimization procedures. In this paper, a new method is presented for fast spectral analysis of locally uncertain systems subjected to random inputs based on the response of one such system (called the nominal system). Unlike other methods, such as modal expansion methods, the proposed method is applicable to general uncertainties in the damping and stiffness matrices with the sole restriction that the system remains stable with probability one. Moreover, the proposed method yields exact responses for the perturbed systems and its accuracy is not affected by the size or magnitude of the uncertainties. However, the degree of locality of the uncertainty dictates the observed gains in computational efficiency when using the proposed method. When the uncertainty is extremely localized, one can expect gains in computational efficiency of two to three orders of magnitude while only modest gains of 2–3 times are observed when half the model is uncertain. Two numerical examples are presented to illustrate the accuracy and gains in computational efficiency of the proposed method.     

Competition between Electronic Cooling and Andreev Dissipation in a Superconducting Micro-Cooler

We discuss very low temperature experiments on superconducting micro-coolers made of a double Normal metal–Insulator–Superconductor junction. We investigate with a high resolution the differential conductance of the micro-cooler as well as of additional probe junctions. There is an explicit crossover between the single quasi-particle current and the phase-coherent Andreev current. We establish a thermal model by considering the thermal contribution due to the Andreev current. The related increase of the electron temperature is discussed, including the influence of several parameters like the phase-coherence length or the tunnel junction transparency.     

A combined theoretical and experimental investigation of the valorization of mechanical and thermal properties of the fly ash-reinforced polypropylene hybrid composites

Journal of Materials Science - Fly ash (FA) particles were surface modified with cetyltrimethylammonium bromide (Ctab) and hybridized with graphene oxide (GO) and carboxymethyl cellulose (CMC)...     

Smart Healthcare Monitoring System

Wireless Personal Communications - Under ultra-wideband indoor channels, the characteristic of fine multipath resolution allows Rake collectors to combine the multipaths as well as to maximize the...     

Energetic and exergetic investigation of single slope solar still with sponge and circular hollow fins at different water depths

In this investigation, the experimental analysis of single slope solar still (SSSS) using hollow pin fins and sponge is done. The analysis of a SSSS using various sizes of water depth located in the basin was investigated based on energy and exergy analysis. The performance was estimated for the different water depths such as 15, 30, and 45 mm in basin. Four types are considered, type 1: traditional solar still (TSS), type 2: TSS with sponge, type 3: TSS with circular hollow fins and type 4: TSS with sponge and circular hollow fins. The effects of the sponge, water depth and the use of hollow pin fins were also examined. The performance was estimated for the variation of water depth such as 15, 30, and 45 mm in basin. The energy efficiency of Type 4 (TSS with sponge and circular hollow fins) is 20% higher than that of Type 3 (TSS with circular hollow fins), 38.47% higher than that of Type 2 (TSS with sponge) and 79.98% higher than that of Type 1 (TSS).