Development of analytical models of switched reluctance motor in two-phase excitation mode: extended Miller model

This paper models the magnetic coupling effects of phase windings in a typical two-phase excited 6/4 switched reluctance motor (SRM). The flux-linkage characteristics, obtained from the two-dimensional finite-element analysis of the motor, show the major effect of the mutual coupling between the phases particularly for high levels of phase currents. Because the flux-linkage characteristic fully describes the motor behavior, the flux-linkage model is the base for this analysis. Taking into account the advantages of the Miller model, we extended it to two-phase excitation. Even though we used a simple, low-cost, and easily implemented model, it can reasonably predict the flux-linkage characteristics of the two-phase excited SRM. We compared the proposed method with the results of the method reported by Essah and Sudhoff and found that more accurate results are achieved with the proposed method.     

The Effect of Magnetic Field on Optical Conductivity of Hexagonal Boron-Nitride Sheet

Journal of Superconductivity and Novel Magnetism - The main purpose of this work is to investigate the effect of external magnetic field on the optical absorption of single-layer hexagonal boron...     

LARA: Locality-aware resource allocation to improve GPU memory-access time

The Journal of Supercomputing - Memory access as a primary performance bottleneck of each processing unit also plays a significant role in GPU performance. In addition to high challenging parts of...     

Core designing of a new type of TVS-2M FAs: neutronics and thermal-hydraulics design basis limits

One of the most important aims of this study is to improve the core of the current VVER reactors to achieve more burn-up (or more cycle length) and more intrinsic safety. It is an independent study on the Russian new proposed FAs, called TVS-2M, which would be applied for the future advanced VVERs. Some important aspects of neutronics as well as thermal hydraulics investigations (and analysis) of the new type of Fas are conducted, and results are compared with the standards PWR CDBL. The TVS-2M FA contains gadolinium-oxide which is mixed with UO₂ (for different Gd densities and U-235 enrichments which are given herein), but the core does not contain BARs. The new type TVS-2M Fas are modeled by the SARCS software package to find the PMAXS format for three states of CZP and HZP as well as HFP, and then the whole core is simulated by the PARCS code to investigate transient conditions. In addition, the WIMS-D5 code is suggested for steady core modeling including TVS-2M FAs and/or TVS FAs. Many neutronics aspects such as the first cycle length (first cycle burn up in terms of MW_thd/kgU), the critical concentration of boric acid at the BOC as well as the cycle length, the axial, and radial power peaking factors, differential and integral worthy of the most reactive CPS-CRs, reactivity coefficients of the fuel, moderator, boric acid, and the under-moderation estimation of the core are conducted and benchmarked with the PWR CDBL. Specifically, the burn-up calculations indicate that the 45.6 d increase of the first cycle length (which corresponds to 1.18 MW_thd/kgU increase of burn-up) is the best improving aim of the new FA type called TVS-2M. Moreover, thermal-hydraulics core design criteria such as MDNBR (based on W3 correlation) and the maximum of fuel and clad temperatures (radially and axially), are investigated, and discussed based on the CDBL.     

Kinetics studies of nano-structured cobalt–manganese oxide catalysts in Fischer–Tropsch synthesis

The nano-structured cobalt/manganese oxide catalyst was prepared by thermal decomposition of [Co(NH₃)₄CO₃]MnO₄ precursor, and was tested for the Fischer–Tropsch reaction (hydrocarbon forming) in a fixed-bed micro-reactor. Experimental conditions were varied as follow: reaction pressure 1–10 bar, H₂/CO feed ratio of 1–2 and space velocity of 3600 h^?1 at the temperature range of 463.15–523.15 K. On the basis of carbide and/or enolic mechanisms and Langmuir–Hinshelwood–Hougen–Watson (LHHW) type rate equations, 30 kinetic expressions for CO consumption were tested and interaction between adsorption HCO and dissociated adsorption hydrogen as the controlling step gave the most plausible kinetic model. The kinetic parameters were estimated with non-linear regression method and the activation energy was 80.63 kJ/mol for optimal kinetic model. Kinetic results indicated that in Fischer–Tropsch synthesis (FTS) rate expression, the rate constant (k) has been increased by decreasing the catalyst particle size. The catalyst characterization was carried out using different methods including powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area measurements.     

Patterning of porous silicon nanostructures and eliminating microcracks on silicon nitride mask using metal assisted chemical etching

A method for selective formation of reproducible, high fidelity and controllable nano and micrometer size porous Si areas over n-type Si wafers is provided. A 400 nm thick Silicon Nitride layer was used as the mask layer while Platinum and Palladium nanoparticles were deposited over the unprotected areas to obtain porous areas through metal assisted chemical etching process. Nanoparticles were deposited by electroless plating solutions containing H₂PtCl₆ and PdCl₂. Good controls over pore size and depth were obtained with well defined and sharp edges of the patterned areas. The results were compared to porous structures obtained via electrochemical etching process, indicating the superiority of metal assisted etching in terms of its simplicity as well as the ability of Silicon Nitride layer acting as the mask layer.     

Selective solid-phase extraction of trace Pb(II) from aqueous solution using Pb(II)-ion imprinted polymer

In this work, we synthesized several ions imprinted polymers based on the inclusion of 8-hydroxyquinoline, vinyl benzoic acid, and diazoaminobenzene as ligands into the polymer matrix to complex with lead ions. Besides, to optimize various parameters for the selective extraction and enrichment of lead ions using the best synthesized imprinted polymers, the selectivity of the chosen inorganic ions was investigated. These investigations indicated that the synthesized imprinted polymer particles have good potential for selective enrichment of lead ions compared with other heavy metal ions, and the selectivity of lead ion-imprinted polymers for lead ion was higher than non-imprinted polymer.     

Soft Reconstruction of Speech in the Presence of Noise and Packet Loss

Exploiting the residual redundancy in a source coder output stream during the decoding process has been proven to be a bandwidth efficient way to combat the noisy channel degradations. In this paper, we consider soft reconstruction of speech spectrum, in GSM adaptive multirate and IS-641 vocoders, transmitted over a channel disturbed with noise and/or packet loss. Several schemes are presented which exploit different levels of intraframe and interframe residual redundancy for improved source decoding at the receiver. A packetization strategy is proposed which is matched to the presented error concealment units. For decoders that exploit the residual redundancy, extensive complexity has been a serious concern, especially as the quantizer bitrate increases . In this paper, a novel method is presented to construct reduced complexity algorithms. The proposed methodology is based on the classification of the signal domain and efficient approximation of the residual redundancy or the a priori transition probabilities. The presented schemes provide high quality error concealment solutions for code excited linear prediction (CELP) coders