Mathematical Model of Ilmenite Separation Efficiency Using a High Gradient Plate Magnetic Separator

High gradient magnetic separation is widely used in magnetic minerals upgrading, and its separation performance is significant depending on the parameters. In this investigation, the Mathematical model of the plate high gradient magnetic separator is established, the magnetic induction and the flow field distribution are investigated based on the COMSOL multi-physical simulation, and then the separation efficiency and TiO2 grade are analyzed using the plate high gradient magnetic separator. Additionally, the key factors affecting the efficiency of mineral separation are detailed in the experimental separation, the separation efficiency is demonstrated and its feasibility is verified by experiments. It is founded that the mathematical model and simulation results are basically validated by the experimental separation process, and the TiO2 grade can be effectively upgraded from 5.2% to 11.5% with the rinsing water consumption 9.5 L/min and the belt rotating speed 2 r/min. It is thus concluded that plate high gradient magnetic separator has provided an effective way in upgrading ilmenite quality

Codage de sources de Slepian-Wolf utilisant des codes LDPC et application à la télévision interactive

Many multimedia applications such as Free Viewpoint Television (FTV) use a distant service provider that offers customized services depending on the user request. The main challenge is the efficient storage of a huge amount of data and the real-time extraction of a small fraction of these data upon request. In some applications such as FTV, the requests previously addressed by the user can help to optimize both the storage and the extraction. The problem can thus be seen as a source coding problem with side information at the user side. This PhD thesis fits into this context. It is part of the CominLabs project InterCom that focuses on solutions for massive random access to subsets of correlated data. In this thesis, we investigate practical lossless source coding schemes with side information based on Low Density Parity Check (LDPC) codes. State-of-the-art approaches use rate-adaptive LDPC codes such as rateless codes and LDPC accumulate (LDPCA) codes. Rateless codes perform poorly at low coding rates while LDPCA is not adapted to high-rates. In this thesis, we combine both methods to constructrate-adaptive LDPC codes offering a wide range of rates. However LDPCA does not allow to optimize the code degree distribution, nor to control the amount of short cycles at all rates. This is why we propose two novel rate-adaptive LDPC code constructions to replace the LDPCA part. Simulation results show improved performance compared to LDPCA. Finally, we incorporate the proposed lossless code construction into a complete lossy source coding scheme that was developped for FTV in the framework of the InterCom project.La Télévision Interactive (FTV) est un service de vidéo à la demande qui permet au client de choisir l’angle de vue de la vidéo. Le défi principal est de stocker un d’énorme volume de données et d’extraire une petite partie de ces données à la demande et en temps réel. Pour améliorer le décodage de l’information, on peut supposer que les vues précédemment reçues sont conservées par l’utilisateur. Le problème ainsi posé devient un problème de codage de sources avec information adjacente du côté de l’utilisateur. Cette thèse s’inscrit dans ce contexte. Elle s’intègre au projet CominLabs InterCom dont l’objectif est de proposer des solutions pour l’accès massif aléatoire à des sous-ensembles de données corrélées. Dans cette thèse, nous proposons des schémas pratiques de codage de sources sans perte sous l’hypothèse d’une information adjacente. Ces schémas sont basés sur des codes de type Low Density Parity Check (LDPC). Les méthodes de l’état de l’art utilisent des solutions adaptatives en débit s’appuyant sur des codes LDPC de type Rateless ou LDPC Accumulés (LDPCA). Mais les codes Rateless fonctionnent mal aux débits faibles, et les codes LDPCA ne sont pas adaptés aux débits élevés. Dans cette thèse, on combine les deux méthodes pour construire des codes LDPC aux débits adaptables offrant une large gamme de débits. Cependant, la technique LDPCA ne permet pas d’optimiser la distribution des degrés du code, ni de contrôler le nombre de cycles courts pour tous les rendements. C’est pourquoi nous proposons deux nouvelles méthodes de construction pour remplacer le code LDPCA. Les résultats de la simulation montrent une amélioration des performances par rapport à LDPCA. Enfin, nous intégrons la construction de codes sans perte dans un schéma complet de codage de source avec pertes développé pour l’application FTV dans le cadre du project InterCom

Rate-adaptive LDPC code construction for Free-Viewpoint Television

National audienceThis paper considers source coding for Free-Viewpoint television. It proposes a novel rate-adaptive LDPC code construction that allows to adapt the coding rate depending on the successive user requests. The propose construction greatly reduces the source coding rate compared to existing solutions

DEM–FEM Coupling Simulation of the Transfer Chute Wear with the Dynamic Calibration DEM Parameters

Transfer chutes for bulk material conveying systems have significant importance in ship loading and unloading and are ‘worn’ from large mass flow and fast granular material flow conditions. In this investigation, the impact forces of different granular materials on the transfer chute wear process are considered; the DEM–FEM (Discrete Element Method–Finite Element Method) coupling method was used to calculate the wear and the deformation of the transfer chute. The stress–strain and cumulative contact energy from three different granular materials were analyzed under different working conditions. The results show that the wear, stress–strain, and cumulative contact energy of the transfer chute are closely related to the belt speed, the chute inclination angle, and the types of granular materials; the impact force and the stress–strain on the transfer chute achieves maximum value under a 4 m/s belt speed condition; meanwhile, with the increase of belt speed by 0.5 m/s, the wear of the transfer chute increases 25% and the deformation increases 20%; the shape variable, wear area, and normal cumulative contact capacity of the transfer chute are the smallest with a transfer chute inclination angle from 40° to 45°

Optimized Short-Length Rate-Adaptive LDPC Codes for Slepian-Wolf Source Coding

International audienceThis paper proposes a new construction of rate-adaptive coding schemes based on Low Density Parity Check (LDPC) codes for Slepian Wolf source coding. Unlike standard rate-adaptive source coding schemes, the code construction we propose is based on finite-length code design tools that permit to greatly improve the decoding performance at short to moderate length. In particular, our method permits to limit the number of short cycles in the codes at all rates of interest, and to avoid eliminating some source bits from the code constraints. The proposed method shows a performance improvement of up to an order of magnitude at almost all the considered rates compared to the standard LDPCA construction

Optimized Rate-Adaptive Protograph-Based LDPC Codes for Source Coding with Side Information

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Construction de Codes LDPC Compatibles en Rendement pour le Codage de Sources avec Information Adjacente

National audienceDans cette communication, nous nous intéressons au problème de codage de sources avec information adjacente au décodeur. Nous considérons le cas où le modèle statistique entre la source et l'information adjacente peut varier d'une transmission à l'autre. Pour construire un schéma de codage pratique pour ce problème, on peut utiliser des codes de type Low Density Parity Check (LDPC) compatibles en rendement. Nous proposons ici une nouvelle méthode de construction de codes LDPC compatibles en rendement pour le codage de sources avec information adjacente. Notre construction permet de réduire le nombre de cycles courts dans tous les codes utilisés aux différents débits, et montre ainsi un gain en performance appréciable par rapport aux solutions existantes

A review of moisture migration in bulk material

Moisture migration in bulk materials can cause many problems for bulk material handling. The review aims to find an appropriate method for dynamic moisture migration in unsaturated bulk materials during processing. A large amount of research on moisture migration has been done from both macroscopic and microscopic views. From the macroscopic view, moisture migration in bulk materials such as soil, sand, and grain, were relatively well understood based on the diffusion theory and infiltration theories. The microscopic theory, liquid bridge rupture, and vibration were also well developed. The theories and simulation models can be widely used in geotechnology, food engineering and process control of bulk material. However, current research concerns little about dynamic moisture migration in unsaturated bulk material. Some further development of theories and simulation models are needed