Size Of Cu Research Articles

Fast intra mode decision and fast CU size decision for depth video coding in 3D-HEVC

3D-HEVC is the new coding standard for both texture and associated depth video. In addition to several new coding tools that are designed for texture video with improved coding efficiency, some tools are specified for depth video, such as depth modeling modes (DMMs), segment-wise DC (SDC) mode and depth intra skip mode. This paper proposes techniques that accelerate the encoding of depth video, including a fast intra mode decision and a fast CU size decision. A hierarchical mode decision is proposed for the fast intra mode decision, based on a statistical analysis of mode distribution. The intra mode can be predicted at a very early stage if the hierarchical comparison of the rate–distortion (R–D) cost for selected candidate modes is satisfied for a given condition. For the fast CU size decision, smaller CU sizes are not evaluated if the current CU has the desired properties. The CU size of the collocated texture is also considered to avoid over-splitting of the current depth CU. The experimental results show that the proposed techniques achieve an average 62.5% time saving with 0.81% increase in the bitrate for the synthesized views under the all intra configuration, compared with the reference software HTM 15.0.

Effect of Calcination Atmosphere and Temperature on the Hydrogenolysis Activity and Selectivity of Copper-Zinc Catalysts

A series of CuZn catalysts with a Cu/Zn ratio of 1.6 was prepared by the calcination of a single precursor, CuZn-P consisting of an equimolar mixture of aurichalcite and zincian malachite, in three different calcination atmospheres (air, nitrogen, and hydrogen) at three temperatures (220, 350, and 500 °C). All catalysts were characterized by XRD and N2-physisorption to assess their phase composition, crystallite sizes and textural properties and tested in dimethyl adipate (DMA) hydrogenolysis in a batch reactor at 220 °C and 10 MPa H2. The XRD examination of these catalysts proved that both parameters, calcination temperature and atmosphere, affected the resulting phase composition of the catalysts as well as their crystallite sizes. In an oxidizing atmosphere, CuO and ZnO in intimate contact prevailed whereas in inert or reducing atmosphere both oxides were accompanied by Cu2O and Cu. The crystallite size of Cu2O and Cu was larger than the size of CuO and ZnO thus indicating a less intimate contact between the Cu-phases and ZnO in catalysts calcined in nitrogen and hydrogen. Catalysts prepared by calcination at 220 °C and CuZn catalyst calcined in the air at 350 °C significantly outperformed the other catalysts in DMA hydrogenolysis with a 59–78% conversion due to the small crystallite size and intimate contact between the CuO and ZnO phases prior to catalyst reduction. Despite the low DMA conversion (<30%), transesterification products were the main reaction products with overall selectivities of >80% over the catalysts calcined in nitrogen or hydrogen at least at 350 °C. The obvious change in the preferred reaction pathway because of the atmosphere calcination and temperature shows that there are different active sites responsible for hydrogenolysis and transesterification and that their relative distribution has changed.

CART-based fast CU size decision and mode decision algorithm for 3D-HEVC

Despite three-dimensional high efficiency video coding (3D-HEVC) has a good performance of 3D video coding and synthesized views, the recursive splitting process of the largest coding unit (LCU) and the best mode deciding process caused huge computational complexity. To reduce this computational burden, this paper presents a classification and regression tree-based (CART) fast coding level decision and mode decision algorithm for 3D depth video. The algorithm contained two parts: CART model training, fast coding level and mode decision. In the part of CART model training, we constructed a CART decision tree, where the complexity of depth map, the optimal depth level of co-located texture and the relativity of neighbor LCU were regarded as feature vectors, and the best coding unit depth level was regarded as class label. In the part of fast coding process, features were extracted to predict the depth level of each LCU of depth map; furthermore, some decision of coding mode could be skipped early. Experimental results show that proposed algorithm can save the times of coding process by 24.6% on average while maintaining almost the same rate distortion performance as the 3D-HEVC reference software.

New approach for more uniform size of Cu and Cu-CuO (core-shell) nanoparticles by double-salt reduction

We introduced a method for polyol synthesis of Cu-NPs in ethylene glycol (EG). This simple method takes place across the slow reduction of copper ions from copper nitrate and copper sulfate in ethylene glycol in the presence of a polymer surfactant (Polyvinylpyrrolidone: PVP), which was added to preclude agglomeration and provide dispersion stability to the final colloidal nanoparticles. Additionally, a double-salt reduction method enabled high-quality uniform nanoparticles to be obtained. The uniform size of the spherical copper nanoparticles could be controlled within the range of 10–55 nm by varying the synthesis parameters. Additional reducing agents were used to decrease reaction time, but these implantations had effects on the size and shape of the nanoparticles. Copper NPs mostly have a single crystal morphology. We also present an easy way to produce Cu-CuO NPs which can be used in different applications.

Electrodeposition of Cuprous Oxide on Boron Doped Diamond Electrodes

Nowadays, Cu_2O is very promising electrode material for photoelectrochemical applications. In this paper, we report on the controllable synthesis of Cu_2O single particles as well as compact layers on Boron Doped Diamond (BDD) electrodes using potentiostatic deposition in continuous and pulse mode. The BDD layers were prepared with different B/C ratios in the gas phase in order to investigate boron doping level influence on the Cu_2O properties. The effect of electrodeposition conditions such as deposition regime and pulse duration was investigated as well. The Cu_2O covered BDD electrodes were analysed by Scanning Electron Microscopy (SEM) and Raman spectroscopy. Improvement in the homogeneity of the electrodeposit and removal of clusters were achieved when the pulse potentiostatic regime was used. Using the same pulse electrodeposition parameters, we confirmed the possibility of controlling the deposition rate of Cu_2O by varying the BDD conductivity. Finally, we were able to scale the size of Cu_2O particles by changing the number of deposition pulses. The obtained results have shown a great potential of controlling the morphology, amount, size and distribution of Cu_2O films on BDD substrates by changing the boron doping level and electrodeposition conditions as well. The investigations reported herein allowed us to better understand the deposition mechanism of Cu_2O on BDD electrodes which could then be used for preparation of active layers for electrochemical applications and in optoelectronic devices such as solar cells and photodetectors.

Synthesis and characterization of a new nanomagnetic coordination composite from Fe3O4 and Cu(II) complex: as an efficient catalyst in oxidation of benzyl alcohol

New nanomagnetic coordination compound, Cu(salal)@DA@ Fe3O4, was synthesized by bonding between the Cu(II) complex and Fe3O4 nanoparticles. The Cu complex has two aldehyde groups. The surface of Fe3O4 nanoparticles was modified by the dopamine molecules and the amine group of dopamine is free. Therefore, the Cu complex is covalently anchored to Fe3O4 nanoparticle by the formation of imine bonds between the aldehyde and amine groups. On the other hand, a Cu-Schiff base complex is immobilized on nano-Fe3O4 by dopamine as a bridge. Consequently, the homogeneous Cu complex is easily converted to the heterogeneous-magnetic compound in this project. The Cu complex, Fe3O4 and new nanocomposite were characterized by general techniques such as FTIR, TGA, XRD, FESEM, MAP and EDS. The average crystallite size of Fe3O4 and Cu(salal)@DA@ Fe3O4 were calculated by Scherrer’s formula and they are 18.52 and 24.69 nm, respectively. These results indicated the average crystallite size of Fe3O4 nanomaterials is slightly increased by surface modification by Cu complex. The FESEM images show a tiny spherical mushroom morphology for both nanocompounds, and the EDS analysis confirms the presence of Fe, Cu, C and O in the nanomagnetic coordination composite. The catalytic properties of these compounds were studied and compared to oxidation of benzyl alcohol by 30% H2O2 at room temperature. The results show that the catalytic properties Cu complex and Fe3O4 were enhanced by cooperation of both compounds in a nanocoordination composite.

Quantifying the grain boundary segregation strengthening induced by post-ECAP aging in an Al-5Cu alloy

Hardening on annealing (HOA) has been frequently observed in nanostructured metals and alloys. For nanostructured materials obtained by severe plastic deformation (SPD), HOA has been attributed to the reduction of dislocation sources within grains and grain boundary relaxation during annealing. In the present work, it is shown that when a bimodal grain structured (a mixture of micron-sized and ultrafine grains) Al-5Cu alloy prepared by equal channel angular pressing (ECAP) was subjected to post-ECAP natural and artificial aging treatments, the alloy shows a completely different precipitation behavior with an accelerated precipitation kinetics. No coherent θ'' or semi-coherent θ' precipitates form in the bulk of grains, while a large fraction of stable incoherent θ precipitates form along high angle boundaries. After artificial aging at low temperatures for a short time, a significant improvement of both ultimate tensile strength and uniform elongation was achieved without sacrificing the yield strength. A systematic microstructure characterization by EBSD, TEM and APT has been carried out to investigate the evolution of grain size, dislocation density and solid solution level of Cu as well as the precipitation of Al-Cu precipitates during natural and artificial aging treatments. A quantitative evaluation of different supposed strengthening mechanisms revealed that the segregation of Cu elements at grain boundaries plays a more important role than grain boundary relaxation and the dislocation source-limited strengthening to compensate the yield strength reduction caused by the decrease in dislocation density and solute content of Cu in solid solution.

Substitution of Zn in Earth‐Abundant Cu2ZnSn(S,Se)4 based thin film solar cells – A status review

Cu2ZnSnS4 (CZTS) and Cu2ZnSn(S,Se)4 (CZTSSe) are the most promising quaternary earth abundant photo-absorber materials for thin film solar cells, with reported power conversion efficiencies (PCE) of more than 12%. In CZTS and CZTSSe based solar cells, similar atomic sizes of Cu and Zn is thought to be the main reason for CuZn and ZnCu antisite defect formation, resulted in severe potential fluctuations and tail states that can be inhibited by an incorporation of alternative bigger atoms such as Cd and Mn. In addition, the large open-circuit voltage deficit observed in CZTS and CZTSe device because of existence of Cu and Zn cation disorder in kesterite crystal. Recently, in the development of CZTS based thin film solar cells the reduction of antisite defects by cation substitution has received considerable attention. This also opens up the possibility to explore materials with similar crystal structures and band gaps as CZTS/CZTSSe such as Cu2XSnS4 (where X = Mn, Cd, Fe, Co, Ni and Ba). In this review, the effect of substituting other metals for Zn is discussed, providing a way to alter defects and tail states in the absorber material of CZTS/CZTSSe thin film solar cells.

Bayesian-theory-based Fast CU Size and Mode Decision Algorithm for 3D-HEVC Depth Video Inter-coding

Bayesian-theory-based Fast CU Size and Mode Decision Algorithm for 3D-HEVC Depth Video Inter-coding

Development of novel ultrafine grain cu metal matrix composites reinforced with Ti-Cu-Co-M (M: Ni, Zr) amorphous-nanocrystalline powder

Novel ultrafine grain composites of Cu matrix reinforced with 2-50 wt. % of Ti48Cu39.5Ni10Co2.5 and Ti48Cu39.5Zr10Co2.5 (at. %) amorphous-nanocrystalline alloy particles have been fabricated by powder metallurgy. The composites showed a homogeneous structure. The characterization of composites was performed by optical and scanning electron microscopy (SEM), X-ray powder diffraction (XRD), micro- and macrohardness, as well as density measurements. After hot-pressing the crystallite size of Cu was smaller than 200 nm and nanocrystalline phases of reinforcing powder were 5-35 nm. Densities of 97-76 % relative to calculated values of consolidated composites were obtained, depending on the reinforcing weight fraction. Additionally, the mechanical properties and electrical resistivity of composites have been investigated. The results reveal that the 0.2% offset compressive yield strength of composites increases by two and five times, with respect to pure Cu matrix, for the composites reinforced with 2 and 50 wt. % of reinforcing particles, respectively. Electrical resistivity increases continuously, with higher values after 30 wt. % of addition. Changes in mechanical and electrical properties were produced by the increase of amorphous-nanocrystalline additive.

Effect of milling on dispersion of graphene nanosheet reinforcement in different morphology copper powder matrix

The effective dispersion of Graphene Nanosheet (GNS) as reinforcement was studied with various morphology of Copper (Cu) powder as matrix. High energy milling was used for modifying the morphology of the Cu powders. The Cu powder with Spherical and dentric shape was used in this study. Using high energy milling both the powders were milled for 8 h and 16 h respectively. The morphology of Cu powders was altered as flake shape upon milling. GNS (2 wt. %) was added as reinforcement uniformly with various morphology Cu powder used as matrix. The effect of size and shape of Cu as matrix on Cu/GNS composite properties was comprehensively studied. The Cu/GNS composite was prepared using powder metallurgy technique. Using the different shape and size of the Cu as matrix the interface of GNS has been studied. The hardness properties of Cu/GNS composite are evaluated. The effect of GNS interface in Cu particles has a significant influence on mechanical properties of composites. The hardness of Cu matrix composite has improved up to 20% compared to that of pure Cu. Thus morphology of Cu has the ability to improve the mechanical properties with GNS reinforcement.

Stabilizing the metastable γ phase in Ga2O3 thin films by Cu doping

The metastable cubic γ phase Ga2O3 with a defect spinel structure presents several fascinating properties, which may be a more attractive material than the stable β form. Herein, we found that the metastable γ-Ga2O3 can be stabilized by copper (Cu) doping through a simple operation and low cost method of sol-gel. The γ-Ga2O3 thin films were prepared under the annealing of 700 °C in nitrogen atmosphere for Cu doping. The β phase Ga2O3 ones were obtained at the same condition without the Cu dopant. While the Cu doped γ phase Ga2O3 will transform to β phase for a high annealing temperature above 800 °C. The grain size of Cu doped γ-Ga2O3 and undoped β-Ga2O3 thin films increases with the increase of the annealing temperature. The UV–Vis absorption spectrum of the β-Ga2O3 thin film exhibits a sharp intrinsic absorption edge at ∼250 nm, whilst Cu doped γ-Ga2O3 thin film displays an obvious red-shift. The band gap decreases from 4.90 eV to 4.38 eV for the Cu doping. The photoluminescence intensity at the ultraviolet and blue region of Cu doped γ-Ga2O3 thin films are stronger than undoped β-Ga2O3, which can be attributed to the introduction of more defects such as oxygen vacancies in γ phase by Cu doping.

Non-monotonic variation of the grain size in Cu nanopowders subjected to ball milling

Ball milling (BM) a Cu nanopowder resulted in an increase of the average grain size from 8 to 52 nm, followed by a gradual decrease to 19 nm. In contrast, the grain size of coarse-grained Cu decreased monotonically from 290 nm to 19 nm. Fitting a model to the kinetic curves indicates that the two processes have similar activated volumes during collisions. It also reveals that particles over 100 nm are formed when nanoparticles are compressed during a collision for the first time.

Two-stage method to enhance the grain size of Cu(In,Ga)Se2 absorbers based on sputtering quaternary Cu(In,Ga)Se2 target

Preparing CIGS thin films with grain size above 1 μm based on quaternary CIGS target is difficult, which is a barrier for the further enhancement of CIGS cell efficiency. We proposed a two-stage method to overcome this problem. Cu-rich CIGS thin film was prepared from quaternary CIGS and Cu target and then converted into Cu-poor CIGS by depositing the In2Se3 layer on the Cu-rich CIGS with the subsequent annealing. CIGS absorbers with micrometer-sized crystal based on quaternary CIGS target was prepared. The influence of the In2Se3 deposition on the physical properties of the CIGS absorber and CIGS cells has been investigated. The thickness of In2Se3 layer has been optimized which can result in the highest conversion efficiency of 9.5% in Cu-rich CIGS based solar cells.

Role of initial water content in glycerol hydrogenolysis to 1,2-propanediol over Cu–ZnO catalyst

The work aims to investigate the role of initial water content in the glycerol hydrogenolysis to 1,2-propanediol over Cu–ZnO in depth by characterizing the fresh and spent catalysts in detail with ICP, XRD, XPS, EDS, HRTEM, N2 sorption, N2O chemisorption, H2-TPD and NH3-TPD. The glycerol conversion and 1,2-propanediol selectivity gradually reduce simultaneously with increasing initial water content. At higher initial water content, more CuO are formed, bringing about a decrease in the 1,2-propanediol selectivity. The sizes of Cu and ZnO crystallites increase tremendously with increasing initial water content, lowering the active surface area and acidity. Furthermore, the surface Cu content reduces along with the increase of surface Zn content at higher initial water content. The two aspects make a decrease in the glycerol conversion. This work would aid the glycerol hydrogenolysis to 1,2-propanediol over Cu–ZnO with high catalytic efficiency.

Exceptional catalytic performance of ultrafine Cu2O nanoparticles confined in cubic mesoporous carbon for 4-nitrophenol reduction

Different types of Cu-based nanoparticles, namely Cu2O, Cu and CuO were homogeneously dispersed on cubic ordered mesoporous carbon CMK-8 (denoted as Cu2O@CMK-8, Cu@CMK-8 and CuO@CMK-8, respectively) and their performances for catalytic reduction of 4-nitrophenol (4-NP) were comparatively studied. The average particle size of Cu2O, Cu, and CuO nanoparticles confined in CMK-8 were estimated to be 4.0, 8.1, and 4.3nm, respectively. In comparison to Cu@CMK-8 and CuO@CMK-8, the Cu2O@CMK-8 nanocomposite exhibits an outstanding rate constant of 2.21×10−2s−1 and an exceptionally high activity parameter of 203s−1gCu−1 when the actual Cu loading is considered. The uniform particle size distribution along with high BET surface area and the ability to generate highly active nascent Cu(0) nanoparticles during the catalytic process activate both the 4-NP and BH4− to be efficiently adsorbed on the active sites of Cu2O@CMK-8. It is found that the catalytic properties of these Cu-based CMK-8 nanocomposites strongly depend on the state of Cu and their particle size. Furthermore, Cu2O@CMK-8 is highly reusable for five successive cycles without significant degradation of its activity.

A Cu-Au bimetallic co-catalysis for the improved photocatalytic activity of TiO2 under visible light radiation

This study represents the co-catalytic activity of mono/bimetallic loaded titanium dioxide (TiO2) nanocomposite of copper (Cu) & gold (Au) for the photo-reduction of aromatic nitro compounds and the photo-oxidation of salicylic acid. It was observed that the average hydrodynamic size of Cu (∼21 nm) and Au (∼25 nm) increased after the formation of core-shell structure (∼36 nm and∼38 nm for [email protected] and [email protected] respectively). The morphological studies revealed the uniform coating of Cu-shell of thickness∼2.1 nm over Au core. Moreover, in optical analysis a considerable blue-shift in the absorption band of [email protected] (600 nm-559 nm) and a red-shift in [email protected] (528–580 nm) with significant change in color were observed with increasing the amount of Au and Cu, respectively. Under visible light irradiation these bimetallic/TiO2 nanocomposite showed higher activity for the reduction of 3-nitroacetophenone and 1-chloro-3-nitrobenzene and oxidation of salicylic acid comparative to their monometallic counter parts with a higher rate constant k = 0.97 × 10−2 min−1 ([email protected]/TiO2), k = 0.65 × 10−2 min−1 ([email protected]/TiO2) relative to monometallic (k = 0.34 × 10−2 min−1 (Cu/TiO2) and k = 0.29 × 10−2 min−1)) for the oxidation of salicylic acid. The higher activity of bimetallic/TiO2 nanocomposite is ascribed to the decrease in work function (4.2 for [email protected]/TiO2 & 4.6 for [email protected]/TiO2) resulting in the proficient transfer of electrons at bimetallic-TiO2 interface.

Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

The TiCp/Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiCp/Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu–Cr–Zr alloys to fabricate the nano-sized TiCp-reinforced Cu–Cr–Zr composites. Results show that nano-sized TiCp can effectively refine the grain size of Cu–Cr–Zr alloys. The morphologies of grain in Cu–Cr–Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiCp. The grain size decreased from 82 to 28 μm with the nano-sized TiCp content. Compared with Cu–Cr–Zr alloys, the ultimate compressive strength (σUCS) and yield strength (σ0.2) of 4 wt% TiCp-reinforced Cu–Cr–Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu–Cr–Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiCp-reinforced Cu–Cr–Zr composites decreased with the increasing TiCp content under abrasive particles. The eletrical conductivity of Cu–Cr–Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu–Cr–Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

Preparation and application of Cu/ZnO catalyst by urea hydrolysis method for low-temperature methanol synthesis from syngas

The Cu/ZnO catalyst prepared by urea hydrolysis method was investigated for low-temperature methanol synthesis from syngas containing CO2. Concurrently, the activity of the conventional Cu/ZnO catalyst prepared by co-precipitation method was also compared. The effects of precipitation temperature, urea content, stirring speed and the introduction of Al on the catalytic performance of Cu/ZnO were deeply studied. It was found that the total carbon conversion of the Cu/ZnO catalyst prepared by urea hydrolysis method was increased to 45.0% from 32.8%, comparing with that of the catalyst prepared by co-precipitation method. The structure, BET surface area, surface morphology of the catalyst were characterized by XRD, BET, EDX and SEM. The catalyst prepared by urea method obtained higher BET surface area and larger metallic surface area of Cu than those of the co-precipitation method. The crystals sizes of Cu by urea method were smaller than those of co-precipitation method. Surface structure prepared by urea method had needle shape, and it could increase the surface area, different from the catalyst by co-precipitation method. Both the increased BET surface area of the catalysts and the enhanced metallic surface area of Cu0 promoted the catalyst activity for the low-temperature methanol synthesis. The deactivation of the Cu-ZnO catalysts prepared by urea method was not observed in low-temperature methanol synthesis here.

Structural, bandgap tuning and electrical properties of Cu doped ZnO nanoparticles synthesized by mechanical alloying

Cu doped ZnO nanoparticles abbreviated as Zn1−xCuxO (x = 0, 0.01 and 0.03) were synthesized by mechanical alloying. The change in structure, morphology, band gap and dielectric properties of the synthesized nanoparticles were investigated by XRD, FE-SEM, FTIR, UV–Vis and impedance analyzer respectively. The incorporation of the dopant Cu into ZnO hexagonal wurtzite structure has been verified by X-ray diffraction (XRD) and the Cu doping on the structural bonding of ZnO has been verified by fourier transformation infrared spectra (FTIR).The XRD spectra shows that all the synthesized nanoparticles are single phase, hexagonal wurtzite structure and belong to the space group of P63mc.Crystallite size of Cu doped ZnO (15 nm) nanoparticles is smaller than pure ZnO (18 nm) and peak broadening exists in the system. FE-SEM analysis indicates that Cu doping affects the surface morphology of ZnO. The band gap (Eg) of ZnO decreases with Cu doping which can be attributed to sp-d exchange interaction between the ZnO band electrons and localized d electrons of Cu2+ ions. The dielectric constant of ZnO decreases with Cu doping.