Investigation on the application of solar chimney for multi-storey buildings

This paper presents investigation on the use of solar chimney (SC) in high-rise building. To this end, two small scale models of a three storey building were built. The floor dimensions of each storey are 1.2 × 2 × 1 m. Solar chimneys were integrated into the south-faced walls of one unit whereas the other unit served as a reference. Two design configurations were considered including connected and non-connected solar chimney: The first is a tall SC with an inlet opening at each floor and one outlet opening at the third floor. While for the second, an inlet and outlet openings were installed at each floor. Data recorded included room temperature, air gap temperature and velocity of the induced air flow in the solar chimney.First, a comparison between the SC building models and a common model without openings (SC) demonstrated that multi-storey solar chimney is a good alternative. Room temperature of the solar chimney model was lower than the room temperature of the common model, depending on the floor level by up to 5 °C. Next comparison between the two SC configurations showed that the best configuration is that with an inlet opening at each floor and one outlet opening at the third floor as temperature difference between room and ambient was the lowest. Reasonable agreement between the experimental data and those derived from our mathematical model developed using electric analogies validated our model. Therefore multi-storey solar chimney is an interesting option and could be applied for hot climate like in Thailand to save energy and environment.     

The joint use of sequence features combination and modified weighted SVM for improving daily activity recognition

Two serious problems affecting the implementation of human activity recognition algorithms have been acknowledged. The first one corresponds to non-informative sequence features. The second is the class imbalance in the training data due to the fact that people do not spend the same amount of time on the different activities. To address these issues, we propose a new scheme based on a combination of principal component analysis, linear discriminant analysis (LDA) and the modified weighted support vector machines. First we added the most significant principal components to the set of features extracted using LDA. This work shows that a suitable sequence feature set combined with the modified WSVM based on our criterion classifier achieves good improvement and efficiency over the traditional used methods.     

Treatment of gases and dust using “droplet columns”

The properties of the air-water state diagram, representing the liquid holdups according to gas velocities, in a 0.075 m diameter column are restated. After measurement of the interfacial areas and mass-transfer coefficients, the part of the diagram corresponding to high gas velocities and low liquid contents (10 < U_G < 14 m/s and 0.005 < U_L < 0.04 m/s) was chosen for the treatment of polluted gas streams. Under these conditions, it was shown that a “droplet column” is very efficient for the treatment of gases polluted by acid vapors (SO₂, HCl) and dust (iron oxide, talc, etc.). The cost of energy appeared more favorable than for classical bubble columns.     

Enhancing dependability through profiling in the collaborative internet of things

Multimedia Tools and Applications - The future of the Internet of Things (IoT) is the Collaborative Internet of Things (C-IoT) in which different IoT deployments collaborate to provide better...     

A comparative study of a direct and pulse electrodeposition method of TiO2 films and its effect on photoelectrocatalytic degradation of methyl orange dye

The present study reports the titanium dioxide (TiO2) films synthesized from TiCl3 precursor on ITO glass substrates using two electrochemical techniques, namely direct electro-deposition (DE) and pulse electro-deposition (PE). The synthesis potential during the time-on (Ton) period was fixed at ?1.5 V. However, the open-circuit potential was applied during the time-off (Toff) period. The effect of the technique of electro-deposition and Toff duration on the properties of TiO2 films and their photoelectron-catalytic activity were investigated. The obtained films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-VIS spectrometer, and photocurrent measurement respectively. It is found that the use of the PE technique at different Toff improves the properties of TiO2 films compared to the DE technique. The XRD patterns show the anatase phase with a marked preferential orientation along the (101) direction for all samples. From the SEM analysis, it is seen a significant change from big multigrain agglomerates at DE to a dense film structure and small multigrain agglomerates at different Toff. As the Toff decreases from 3 s to 1 s, the photocurrent response rises and reaches a high value of about 12 mA/cm2. Compared with DE, and under UV light the photocatalytic property of TiO2 film synthesis via PE has been improved in the degradation of methyl orange (MO). Finally, the films deposited at low Toff (Toff =1 s) show a faster degradation of MO.     

Dynamic and multiphysic PEM electrolysis system modelling: A bond graph approach

Proton exchange membrane (PEM) electrolysis technology appears as a key technology in the development of hydrogen-energy market applications such as energy storage or fuel for mobility. Its coupling with renewable electrical sources involves some issues related to the intermittent operation of PEM electrolysis systems. Within this framework, modelling is an essential tool to understand these issues, provide a thorough analysis and suggest some design optimization. A bibliographic analysis was carried out to identify existing models. State of the art highlighted that, although it is critical for the conception of such systems, only a few models take into account the dynamic of the whole system including balance of plant. Therefore, in this paper a new dynamic and multiphysic model of a proton exchange membrane electrolysis system is presented. It was first developed under a graphical modelling formalism: the bond graphs (BG). Regarding dynamic and multiphysic modelling of complex systems, the BG have many advantages: it involves four levels of modelling using only one tool; it is a unified multiphysic approach; the parameters used have a physical meaning; the BG model can be refined very easily by adding new elements without having to start again the modelling process. Finally, because of its causal and structural properties, BG is suitable for modelling but also for control, sizing and diagnosis analysis. The model was then transcribed systematically into block diagrams in modular fashion for reutilisability of model libraries components. After a validation process, the model was proved to describe accurately the dynamic behaviour of a semi-industrial PEM electrolysis system (25 kW). The dynamic model can now be used to achieve some analyses through BG structural properties and simulations. Thus, it is a powerful tool to improve the design of PEM electrolysis systems powered by intermittent electrical sources.     

Efficiency of a Gas‐Liquid Contactor for the Oxygenation of Activated Sludge: Assessment of Mass Transfer Coefficient

The aim of this work is to investigate a co‐current air‐liquid downward flow bubble column with air entrainment by liquid injection nozzle in order to use it as an aerator in activated sludge treatment plants. The study concerns the determination of mass transfer efficiency by measuring the mass transfer coefficient, k_La, both in clean water and in activated sludge. In clean water, this parameter is determined by three methods, i.e., gassing out method, absorption with chemical reaction and off‐gas method. In activated sludge medium, k_La values are measured by two methods, i.e., sludge reoxygenation and the hydrogen‐peroxide method. The values of k_La obtained in clean water are compared to those obtained in sludge, enabling the assessment of the α factor, i.e., ratio of oxygen transfer coefficient sludge/clean water. The results are in good agreement with those reported previously in the literature.     

Study of the combustion efficiency of polymers using a pyrolysis–combustion flow calorimeter

The combustion efficiency of various polymeric materials was studied using a pyrolysis–combustion flow calorimeter (PCFC). Decreasing the combustion temperature in a PCFC leads to partial combustion and lower heat release rates. Combustion efficiency versus combustion temperature was modeled using a phenomenological equation and model parameters were related to the chemical structures of eight pure polymers. The flame inhibition effect was evaluated for two classical approaches in flame retardancy by plotting the combustion efficiency versus the combustion temperature. In the first one (the reactive approach), polystyrenes with different chemical groups substituted on the aromatic ring were studied. In the second one (the additive approach), three well-known flame retardants were incorporated into an ABS matrix: ammonium polyphosphate, tetrabromobisphenol A (TBBA), and a TBBA/antimony trioxide system. Results confirm the flame inhibition effect of halogenated compounds in both approaches. Finally, a correlation between peaks of heat release rate (pHRR) in a cone calorimeter and in a PCFC was attempted. Predicting pHRR in a cone calorimeter using a PCFC appears possible when no barrier effect is expected, if PCFC tests are carried out at a precise combustion temperature, for which the combustion efficiencies in both tests are the same.