Discharge Characteristics of Polydisperse Powders through Conical Hoppers. Part 2: Predictions for Coarse,Granular, Free Flowing Powders

Abstract

The tribo/contact electrification theory of materials is envisaged from the chemical Lewis acid-base concept and an attempt has been made to find a correlation between these two phenomena. The donor-acceptor/acid-base properties of apatite, calcite, feldspar, quartz and wollastonite mineral samples have been determined by electrokinetic studies in water and in different organic solvents having different donicity values. From the results, the donicity values for mineral samples were defined and the position of Fermi level in the forbidden gap energy was estimated. The charge acquired by a single mineral particle of varying sizes was determined after contacting with plate and cyclone type tribochargers made up of different materials. The work functions of the mineral samples were estimated.

The results showed a good correlation between the physical tribo-electrification process and the chemical acceptor-donor property of the minerals. The results also demonstrate the feasibility of arranging the minerals into triboelectric series and thereby to predict their triboelectric charge characteristics and their separation behavior in an electric field with reference to a particular tribocharger medium.     

Environmental Impacts of Dams Constructed in Iran

Construction of dams is essential for an arid country like Iran so water can be stored to assure the availability of a reliable supply to satisfy domestic, industrial and agricultural requirements, control floods and generate hydroelectricity. Dams are thus essential for the country's socio-economic development. While dams have contributed to very significant benefits, their construction has also resulted in many negative environmental impacts. Only these negatives impacts are analysed in this paper. Assessments and understanding of these negative impacts will contribute to more efficient water management practices in the future.     

Expected distortion of simultaneous transmission of multiple source symbols with multicarrier frequency hopping modulation

Wireless Networks - In this paper, we consider the problem of transmitting a Gaussian source over a slow-fading channel, when the aim is to adjust system parameters so that the source is...     

Characterization of Erbium,Indium, and Erbium–Indium co-doped 8%mol Yttria-stabilized Zirconia

Journal of Materials Science: Materials in Electronics - In this work, the cubic structure of Yttria-stabilized Zirconia (8YSZ) and Indium and Erbium co-doped 8YSZ nanopowders have been prepared by...     

Electrospun poly (N-isopropylacrylamide-co-acrylic acid)/cellulose laurate blend nanofibers containing adapalene: Morphology,drug release,and cell culture studies

In this work, a thermo- and pH-sensitive polymer based on poly (N-isopropylacrylamide-co-acrylic acid)/cellulose laurate blend [P(NIPAAm-co-AAc)/CL] was electrospun to produce nanofibers containing adapalene. The synthesized P(NIPAAm-co-AAc), and CL were characterized by ATR-FTIR and ¹H NMR spectroscopies. The thermal behavior of the electrospun nanofibrous samples were determined by a DSC. Afterward, the drug release in different temperatures and pHs from the nanofibers was investigated by UV-vis spectrophotometry and then the LCST behavior of the samples containing adapalene was observed by an ESEM. Moreover, the fibroblast cells culture was carried out with and without adapalene and the cell cytotoxicity of the samples was evaluated via MTT assay. The results from (H&E) and DAPI staining of the viable cells onto the samples surfaces revealed the adapalene has a remarkable short-term potential for the fibroblast cells mortality. It was found that the adapalene loaded electrospun nanofibrous samples enabled to minimize the adverse side effects of the drug by controlling release during three days of cell culture.     

Nonparametric variational learning of multivariate beta mixture models in medical applications

Clustering as an essential technique has matured into a capable solution to address the gap between the growing availability of data and deriving the knowledge from them. In this paper, we propose a novel clustering method “variational learning of infinite multivariate Beta mixture models.” The motivation behind proposing this technique is the flexibility of mixture models to fit the data. This approach has the capability to infer the model complexity and estimate model parameters from the observed data automatically. Moreover, as a label‐free method, it could also address the problem of high costs of medical data labeling, which can be undertaken just by medical experts. The performance of the model is evaluated on real medical applications and compared with other similar alternatives. We demonstrate the ability of our proposed method to outperform widely used methods in the field as it has been shown in experimental results.     

Assessing wood in sounding boards considering the ratio of acoustical anisotropy

The main objective of this study was to investigate the versatility of the ratios in longitudinal sound velocity to transverse as acoustic indicators. Due to independent factors of density, ring-width and extractive content, these indicator ratios were investigated and defined in terms of damping and acoustical coefficient in timbers of Morus alba and Cupressus arizonica planted in Iran. Experiments were replicated for five times in different locations from pith to bark of the trunks. In C. arizonica specimens, the major definition was made in terms of reverse correlation coefficients between indicator ratios and damping. Higher indicator ratios were subjected to lower damping which were affected by ring-width variations where no significant correlations were obtained between indicator ratios and acoustical coefficients. However, narrower rings were observed in specimens with smaller damping and higher indicator ratios in C. arizonica. In M. alba specimens, higher values of indicator ratios showed higher values of acoustical coefficients which were affected by total extractive content variations. In contrast to C. arizonica, no significant correlations were identified between indicator ratios and damping coefficient in M. alba. Smaller amounts of extractive content were observed in specimens with higher indicator ratios and acoustical coefficients.     

Facile Synthesis of Co<Subscript>3</Subscript>O<Subscript>4</Subscript>/CoO Nanoparticles by Thermal Treatment of Ball-Milled Precursors

Co₃O₄/CoO nanoparticles have been synthesized by a simple method which is based on the ball-milling and calcination of cobalt acetate and citric acid. The samples were characterized using X-ray diffraction, transmission electron microscope, and Fourier transform infrared spectroscopy. The results show that Co₃O₄ nanoparticles with an average particle size of ∼40 nm can be obtained by calcination of ball-milled precursors at relatively low temperature (350 °C) for 3 hours. It should be noted that it is possible to control the size of Co₃O₄ particles by calcination temperature, calcination time and also by ball-milling duration using this method. Meanwhile, the pure CoO nanoparticles were obtained successfully by thermal decomposition of Co₃O₄ at 950 °C and quickly quenching to liquid nitrogen.     

Design of a diffractive optical element for pattern formation in a bilingual virtual keyboard

Pattern formation is one of the many applications of diffractive optical elements (DOEs) for display. Since DOEs have lightweight and slim nature compared to other optical devices, using them as image projection device in virtual keyboards is suggested. In this paper, we present an approach to designing elements that produce distinct intensity patterns, in the far field, for two wavelengths. These two patterns are images of bilingual virtual keyboard. To achieve this with DOEs is not simple, as they are inherently wavelength specific. Our technique is based on phase periodic characteristic of wavefront using iterative algorithm to design the phase profiles.     

In-core thermal high-neutron fluence measurement by TLD-activation method

Thermal neutron fluence between 10¹⁴ and 10¹⁸ n/cm² in the Health Physics Research Reactor-Core of Tehran was measured conveniently by a TLD reader using the ⁶Li(n,)³H reaction in TLD-700. The primarily induced thermoluminescence (TL) by irradiation of the crystal in the reactor core was first cleared by annealing. The secondary TL of TLD-700 produced after a storage time by the absorbed energies of decayed tritons in crystal was used as a basis for assessment of prior exposure to neutrons. A thermal treatment stabilized the readings of the high-dose-irradiated dosimeters and reduced the influence of radiation damage in TLD-700. The response reduction as a consequence of high-dose radiation was corrected by Elemental Correction Coefficients (ECC) using gamma responses prior to in-core irradiation. The resulting correlation between neutron fluence and build-up TL of TLD-700 as a consequence of internal activity is presented.