Weighted backprojection approach to cone beam 3D projection reconstruction for truncated spherical detection geometry

A new analytical three-dimensional cone beam reconstruction algorithm is presented for truncated spherical detection geometry. The basic idea of the proposed algorithm is the formation of spatially invariant 3D blurred back-projected volumetric image by the use of the weighted backprojection of cone beam projection data and subsequent 3D filtering using an acceptance angle dependent rho filter. The backprojection weighting function is calculated on the basis of each given geometrical condition, i.e. detection geometry or degree of truncation, position of cone beam apex, and backprojection point. The proposed algorithm is derived analytically and is computationally efficient. Performance of the algorithm is evaluated by the reconstruction of 3D volumetric images using simulated data from arbitrarily truncated spherical detector geometries.     

Peak-Average-Power Ratio Techniques for 5G Waveforms Using D-SLM and D-PTS

Multicarrier Waveform (MCW) has several advantages and plays a very important role in cellular systems. Fifth generation (5G) MCW such as Non-Orthogonal Multiple Access (NOMA) and Filter Bank Multicarrier (FBMC) are thought to be important in 5G implementation. High Peak to Average Power Ratio (PAPR) is seen as a serious concern in MCW since it reduces the efficiency of amplifier use in the user devices. The paper presents a novel Divergence Selective Mapping (DSLM) and Divergence Partial Transmission Sequence (D-PTS) for 5G waveforms. It is seen that the proposed D-SLM and PTS lower PAPR with low computational complexity. The work highlighted a combination of multi-data block partial transmit schemes along with tone reservation. In this, an overlapping factor is used to determine the number of data blocks for every group. Here, considering only those data blocks that have minimum signal power, the use of DSLM and DPTS are required to eliminate the segment’s peaks. Simulation results reveal that the suggested hybrid technique proves to be better than the conventional PTS scheme. Furthermore, the power saving performance of FBMC and NOMA is compared with the Orthogonal Frequency Division Multiplexing (OFDM) waveform.     

New spherical PET design with fresnel aperture orientation

A new spherical PET using Fresnel aperture is being designed, and construction is in progress. In the new design, the original spherical geometry is modified to accommodate a more flexible gantry construction and data processing while preserving the focused geometry of the original design. The performance of this new Fresnel aperture-SPET (F-SPET) is expected to follow closely with that of the original S-PET design. An analysis of an F-SPET designed with nine modular layers, with each modular layer being four rings, was performed in terms of the counting statistics and solid angle and compared with the original S-PET as well as the conventional cylindrical PET. According to the simulation results, the sensitivity gain of the Fresnel aperture-SPET remains a factor of 2 over the equivalent cylindrical system and has nearly the same performance as the original S-PET, while offering a simpler means in construction and data handling for the image reconstruction.     

Remediation of CCA-C treated wood using chelating agents

This study evaluates the effects of the common chelating agents, ethylenediaminetetracetic acid (EDTA), nitrilotriacetic acid (NTA), and oxalic acid (OA) on the removal of copper, chromium, and arsenic from CCA-C treated wood. In the study, the removal of the metal oxides from treated chips and sawdust by EDTA and NTA in conjunction with OA in dual extraction processes was investigated using batch-leaching experiments. Exposing CCA-C treated chips and sawdust to chelat extraction enhanced the removal of CCA-C components compared to extraction by deionized water. Grinding CCA-C treated wood chips into 40-mesh sawdust provided greater access to and removal of CCA-C components. Extraction with EDTA/OA and NTA/OA in dual extraction processes removed about 100% copper and arsenic and 90% chromium from CCA-C treated sawdust. However dual extraction of CCA-C treated chips resulted in about 80% copper and arsenic, and 70% chromium removal. In single extraction processes, EDTA and NTA removed significant amounts of copper from CCA-C treated chips and sawdust compared to other components.

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Entgiftung von CCA-C behandelte Holz mit Chelaten

Zusammenfassung Der Effekt von chelierenden Agenzien wird abgeschätzt. Zum Einsatz kamen Ethylendiamintetraacetat (EDTA), Nitriloessigsäure (NTA) und Oxalsäure (OA) zum Entfernen von Kupfer, Chrom und Arsen aus CCA-C-behandelten Spänen und Sägemehl. Untersucht wurde das Entfernen der Metalloxide mit EDTA und NTA in Kombination mit Oxalsäure in einer zweifachen Extraktion im Batchverfahren. Der Zusatz von Chelaten zu CCA-C-behandelten Spänen und Sägemehl verbessert die Entfernung von CCA-C-Komponenten im Vergleich zur Extraktion mit deionisiertem Wasser. Die Doppelte Extraktion entfernte Kupfer zu 100% und Chrom zu 90% aus CCA-C-benadeltem Sägemehl. Dagenen wurden aus Spänen nur 80% Kupfer und 70% Chrom entfernt. Auch die einfache Extraktion entfernt bereits beträchtliche Mengen an Kupfer im Vergleich zu den anderen Komponenten aus dem behandelten Holz.

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The authors acknowledge the support of Toktas Wood Impregnation Inc. and Unipole Forest Product Trading Ltd., a private Finnish-Turkish Joint Venture Corporation, Adana, TurkeyThe use of trade or firm names in this publication is for reader information only and does not imply endorsement by Forestry Faculty, Istanbul University of any product or service.     

Unit helium requirements for superconductive energy applications in the USA

Estimates of the helium requirements for superconductive magnetic energy storage, magnetically confined fusion reactors, superconducting power transmission lines, magnetohydrodynamic units, superconducting motors and generators, and particle accelerators are presented. The approach entails surveying estimates from system studies, then developing simple scaling laws to calculate helium inventories. Helium loss rates are discussed and applied to estimate annual helium makeup.     

Removal of phosphate from aqueous solutions by electro-coagulation

The aim of this paper was to investigate the feasibility of the removal of phosphate from aqueous solution by electro-coagulation (EC). The current density (CD) between 2.5 and 10 mA cm(-2) and duration in the limits of 5-20 min were tried for different concentrations. In order to determine optimal operating conditions, the EC process used for the phosphate removal was examined in dependence with the CD, initial concentrations and time. The results of the experimental batch processing showed high effectiveness of the EC method in removing phosphate from aqueous solutions.     

An ethanol electrooxidation study on carbon-supported Pt-Ru nanoparticles for direct ethanol fuel cells

Carbon supported Pt-Ru catalysts were prepared at varying Pt:Ru ratios by polyol method. The crystallite sizes of these catalysts were determined by X-ray diffraction technique. The specific surface areas of these catalysts were also defined by Brunauer–Emmett–Teller technique. Cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy measurements were conducted on these carbon supported Pt-Ru catalysts to investigate the effect of ruthenium on the ethanol electrooxidation kinetics. Results indicated that Pt-Ru (25:1) catalyst showed the best ethanol electrooxidation activity. In conclusion, ethanol electrooxidation mechanism was proposed.     

Spray drying of the mountain tea (Sideritis stricta) water extract by using different hydrocolloid carriers

The water extract of the mountain tea was spray-dried by using different food hydrocolloids viz. β-cyclodextrin (BCD), arabic gum (AG), and maltodextrins (MD19 and MD12) as carrier materials. Powdered samples were then subjected to product yield, moisture content, water activity, bulk density, solubility, color (Lab) and SEM particle microstructure analyses. Furthermore, color (Lab), turbidity (NTU), total phenolic content (TPC), total antioxidant activity (TAA) and volatile compound (β-pinene) analyses were performed on the reconstituted mountain tea samples. The product yield increased with the addition of the carrier materials whereas decreased at higher drying temperatures. The inlet air temperature of 155 °C provided the better retention for β-pinene. Almost all physicochemical properties of the spray-dried mountain tea samples were significantly (P < 0.05) affected by the inlet air temperature, the type and concentration of the carrier materials.