Establishing the conditions for the formation of a near-wall layer of solid granular fill of a rotating drum

This paper reports the assessment of the influence of dynamic motion parameters on the formation and disappearance at the cylindrical surface of the chamber of the rotating drum of the near-wall layer of non-loose granular fill. Based on the results of experimental visualization of the flow, the effect of solidity on the behavior of granular fill was revealed. The hydrodynamic effect of fill quasi-liquefaction under the action of solidity has been established, which involves the occurrence of a connecting interaction between adjacent layers and the surface of the chamber. Conversion of shear circulation flow to homogeneous dense clustered stream with slipping and rolling without relative movement of particles was detected. The hydrodynamic characteristics of circulation flow transition to the near-wall layer mode during rotation acceleration have been defined. Such a transition is implemented by smoothly increasing the thickness of the layer when the rest of the fill is circulated at the bottom of the chamber. The effect of the rheological hysteresis of the movement of the rotating chamber fill, caused by quasi-liquefaction of non-loose granular environment, has been established. The effect implies exceeding the speed limit ωfl in the formation of a near-wall layer, at rotation acceleration, above the boundary ωdl of the layer disappearance when the rotation slows down. The manifestation of hysteresis mainly increases with an increase in Reynolds number. The intensity of increased hysteresis manifestation increases with a decrease in the degree of filling the chamber. The value of the Froud number for the ωfl and ωdl boundaries increases with the increase in Re. It has been established that at the relative particle size of the dispersed fill ψdc≈(0.065–1.04)·10‑3 and Re=30–500, Fr=1–2.9, for the ωfl boundary, and Fr=0.5–1.4, for the ωdl boundary. The Fr value for the ωfl limit was found to exceed this value for the ωdl boundary by 1.6–2.1 times. The established effects make it possible to substantiate the rational parameters for the grinding process in drum-roll mills

Aging Response in Selective Laser Melted AlSi10Mg Alloy as Function of Distance from the Substrate Plate

Selective Laser Melting (SLM) builds a metallic part in a layer-by-layer mode with growth occurring along the vertical axis. Metallic powder layers are melted by a laser beam by programmed scan sequences inducing specific mechanical properties in the as-built samples according to process parameters. Post heat treatments are usually performed to optimise the mechanical behaviour. In this work, the effects induced by heat treatments at 175°, 200° and 225°C on SLMed bars of Al10SiMg were investigated as function of distance from the substrate plate. The bars were 300 mm height and in the as-built condition, Vickers microhardness and tensile strength decreased along the built direction, while the elongation increased from the bottom to the top of the billet. After heat treatments, Vickers microhardness resulted lower of 10HV at the top of the bar compared to its bottom in contact with the hot substrate; microhardness decreased with time at constant temperature compared to the as-built. Tensile properties showed variations of 50 MPa and 1% elongation between the top and the bottom of the billet when aging was performed at 175°C for 4h; the strength and ductility gradients were reduced to 20 MPa and 0,5% respectively by increasing the aging time to 6h. Microstructure investigations performed by scanning electron microscopy confirmed the different evolution of Silicon particles and precipitated particles at different height of the bars.

Production of raw copper through continuous converting of copper-nickel sulphide materials

The conventional technology of converting copper mattes in horizontal converters has its drawbacks and fails to conform with the current environmental norms and regulations applicable to metallurgical processes. Therefore, it should be replaced with an environmentally sustainable technology. This paper considers the results of a lab and pilot scale study that looked at converting nickel-bearing copper material into raw copper and running nickelbearing slag. It is demonstrated that the continuous converting process can be stable in both three-layer mode (i. e. slag – white matte – copper) and two-layer mode (i. e. slag – copper). With the help of scanning electron microscopy and electron microprobe analysis, it was established that most of copper, nickel and cobalt get wasted in a soluble form. Choice of fluxes produces a significant effect of the process performance. Fluxes were added to maintain the total concentration of SiO2 and CaO in the slag at 32%. At the same time, varying SiO2/CaO ratios were used depending on the operating mode — from pure Fe – Si slag to pure Fe – Ca slag. It is noted that a rising SiO2/CaO ratio leads to a higher recovery of nickel into slag. A pure Fe – Si slag mode is associated with foaming. The results of the lab study were verified through test heats carried out in a pilot Vanyukov furnace. The obtained raw copper has the following composition, wt %: 3.6–4.2 Ni; 0.6–1.2 S; 0.006–0.06 Fe; and it needs to be final converted for better refining.

Electrical Conductivity Study of the Adsorbate-Induced Si(111) Surface Reconstructions after C60 Adsorption

Electrical conductance of Si(111)6×6-Tl and Si(111)β√3×√3-Bi surfaces has been monitored in the course of fullerenes deposition. It has been found that dependence of surface conductivity on the adsorbed C60 dose can be understood in terms of charge transfer induced by interaction of fullerene molecules and substrate which can be explained by the acceptor-like behavior of fullerenes. For the Si(111)6×6-Tl surface decreasing of conductance is connected with depletion of metallic bands of the Tl double layer. For the Si(111)β√3×√3-Bi surface the conductivity is almost unchanged with C60 dose, but due to the fact that C60 layer on this surface form close-packed hexagonal arrays in the layer-by-layer mode, it can be used as a template for alkali-induced ultra-thin fulleride formation.

Deep Latent Low-Rank Fusion Network for Progressive Subspace Discovery

Low-rank representation is powerful for recover-ing and clustering the subspace structures, but it cannot obtain deep hierarchical information due to the single-layer mode. In this paper, we present a new and effective strategy to extend the sin-gle-layer latent low-rank models into multi-ple-layers, and propose a new and progressive Deep Latent Low-Rank Fusion Network (DLRF-Net) to uncover deep features and struc-tures embedded in input data. The basic idea of DLRF-Net is to refine features progressively from the previous layers by fusing the subspaces in each layer, which can potentially obtain accurate fea-tures and subspaces for representation. To learn deep information, DLRF-Net inputs shallow fea-tures of the last layers into subsequent layers. Then, it recovers the deeper features and hierar-chical information by congregating the projective subspaces and clustering subspaces respectively in each layer. Thus, one can learn hierarchical sub-spaces, remove noise and discover the underlying clean subspaces. Note that most existing latent low-rank coding models can be extended to multi-layers using DLRF-Net. Extensive results show that our network can deliver enhanced perfor-mance over other related frameworks.

Developing Augmented Reality Hybrid Marker using Pictorial Quick Response Code for Community Products

Applying augmented reality technology correctly helps businesses grow and attract more consumers, but using the marker that is the QR code does not directly interpret. On the other hand, if using pictorial markers, although they can convey meaning, it still takes time to process to extract the hidden information. This paper proposes to develop the hybrid marker for augmented reality by mixing the community brand image with the QR code for community product entrepreneurs, and develop the mobile application for scanning the hybrid marker then respond to the augmented reality content in several styles. The hybrid marker was generated into two modes. The opacity layer mode was set the opacity value of QR code to 55%. And overlapping mode is designed to invert the pixel color between pictorial band image and QR code. This system was evaluated in black-box testing. As a result, the efficiency of the hybrid marker and mobile application is the highest level of user acceptance while being used in this system.