Flocculation morphology: effect of particulate shape and coagulant species on flocculation.

Flocculation morphology is a new concept that investigates the morphological characteristics of colloidal particles and coagulants in water during the flocculation process, and the influence that these characteristics have on flocculation process efficiency. This paper is a summary of advances in research on this topic over several years. Morphological characteristics of colloids in natural waters and different kinds of hydrolysed coagulants are investigated, and their effect on colloid stability, flocculation kinetics and efficiency is analysed. It is confirmed that the traditional theory has some deviations in coagulation of nonspherical particles, and these deviations are revised by the flocculation morphology model. Flocculation morphology can not only promote research about flocculation theory, but also instruct the production, application and flocculation control. It can be foreseen that more progress will be made in research and application of flocculation morphology in the near future.     

Tracking-error model-based predictive control for mobile robots in real time

In this paper, a model-predictive trajectory-tracking control applied to a mobile robot is presented. Linearized tracking-error dynamics is used to predict future system behavior and a control law is derived from a quadratic cost function penalizing the system tracking error and the control effort. Experimental results on a real mobile robot are presented and a comparison of the control obtained with that of a time-varying state-feedback controller is given. The proposed controller includes velocity and acceleration constraints to prevent the mobile robot from slipping and a Smith predictor is used to compensate for the vision-system dead-time. Some ideas for future work are also discussed.     

Properties of flash hydrated and agglomerated particles of CFB fly ashes

The fly ash (high carbon content and high unreacted CaO) recirculation in CFB is a typical method to improve the carbon burnout efficiency and the calcium utilization ratio. While the effectiveness of it is limited by the resident time and the reactivity of the re-injected fly ash particles. In the present research, an improved fly ash recirculation method is suggested in which the CFB fly ash is mixed with water or the mixtures of additives (such as waste water of paper mill, cement, sodium silicate, and carbide slag) and water in a blender. Then, this mixture is re-injected into the combustion chamber of CFB by a sludge pump. Because the temperature in CFB is higher, the fly ash was flash hydrated. At the same time, it was dehydrated and agglomerated. The size of agglomerates is bigger than that of original particle and their attrition rate is lower. Therefore the resident time of agglomerates is much longer than that of fine fly ash particles. The absorption of SO₂ is higher than that of original particles, too. This results in high carbon burnout efficiency. The hydrated lime also improves the calcium utilization.     

Experimental investigation of the heat and mass transfer between air and liquid desiccant in a cross-flow regenerator

The regenerator is one of the essential components in a liquid desiccant air-conditioning system, whose efficiency directly influences the system performance. A performance test-bed for a cross-flow regenerator was established in the present analysis. Celdek structured packings were used in the regenerator and LiBr aqueous solution was used as the liquid desiccant. Moisture removal rate and regenerator effectiveness are adopted to describe the mass transfer performance of the regenerator. Effects of air and desiccant inlet parameters on the regenerator performance are experimentally investigated, and performance comparisons between present cross-flow regenerator and other counter-flow configurations available in the literature are also carried out. The comparison results show that the impacts of air and desiccant inlet parameters show similar tendency with those of counter-flow regenerators. A dimensionless mass transfer correlation is proposed, which gives results in good agreement with the experimental findings.     

Effect of Magnetotactic bacteria on the susceptibility in Chinese loess–paleosol sequences

A simulated experiment of Magnetotactic bacteria (MB) effect on susceptibility in the samples from the 5th to 6th loess layers (L₅–S₅–L₆) in Xifeng and Duangjiapo sections was performed. It is demonstrated that MB can increase the susceptibility of the samples and promote newly produced magnetic minerals from paleosol layers under the suitable condition. The tiny magnetic particles and arranged as a chain in the minerals less than 30 μm were found in the paleosol sample of Duangjiapo section.     

Experimental Study on Energy Consumption of Combined Conventional and Dehumidification Drying

Conventional drying, dehumidification drying, and combined conventional-dehumidification drying of wood were experimentally studied in this article. The results showed that the energy consumption in the dehumidification drying is the least but its drying time is the longest. The energy consumption in the combined drying is more than that in the dehumidification drying but less than that in the conventional drying, and the drying time is half of that in the dehumidification drying. The advantages of the combined conventional and dehumidification drying are discussed from the experiments results.