Creation Of Air Bubbles Research Articles

Effect of the spatial variation of permeability on air bubble creation and compression

Tow bundles inside a quasi-unidirectional non-crimp fabric are maintained by sewing threads that induce variation in the bundles’ shape. Indeed, the sewing threads apply a light clamping force that gives a periodical and sinusoidal shape to the tow’s cross-sectional area. This tow cross-sectional area heterogeneity, as a function of position in the fabric, induces a variation of the permeability values. Consequently, while injecting liquid into the fibrous bed, preform's impregnation is influenced as well as the fabric’s void content. The aim of this paper is to consider the effect of tow cross-sectional area heterogeneity on the quality of the manufactured composite part. It leads to reveal the influence of the fibrous reinforcement’s microstructure on the air bubble creation and compression phenomena, especially in terms of process time and the micro and macro air bubble distribution.

Elucidation of rapid reduction of water flow through concrete crack regarded as self-healing phenomenon

ID No : 75 ABSTRACT The development of self-healing concrete has witnessed several strides in the last three decades. Among these is the understanding of the mechanisms of self-healing concrete, as well as the realization of new technologies of enhancing crack selfhealing in concrete. Previous research suggests that crack closing mechanism occurs due to mainly 1) Hydration of anhydrous cement, 2) Formation and crystallization of Calcium Carbonate, 3) Swelling of cement matrix and 4) Sedimentation of particles in the crack interstices. In this research however, after a one by one investigation, it was found that these mechanisms do not fully explain the drastic water flow recovery that occurs in the initial stages of water permeation through cracked concrete. This preliminary finding then prompted direct visual observation of water flow through cracks’ narrow spaces. This was achieved by using acrylic resin and glass as transparent media over the concrete surface of split and machine cut cracks respectively. With this, an interesting observation was made – the creation of air bubbles (waterless spaces inside the interstices) following the condition of full water saturation. It was observed that water flow through the narrow crack openings creates air bubbles by probably various water action mechanisms. The created air bubbles narrow water flow paths in the crack, causing significant water flow reduction in the initial and later stages of water supply condition.

Degradation of Reactive Blue by the mixed culture of Aspergillus versicolor and Rhizopus arrhizus in membrane bioreactor (MBR) system

The main purpose of this study was to investigate reactive dye removal capability of mixed fungal biomasses (Rhizopus arrhizus and Aspergillus versicolor) under non-sterile conditions with the inherent advantages of the submerged membrane bioreactor (MBR) system. Decolorization of Reactive Blue in synthetic textile wastewater by mixed filamentous fungi was carried out in the Erlenmeyer flasks (sterile conditions) and MBR system (non-sterile conditions). The Lab/Pilot Scale MBR system had a working volume of 170 L and was equipped with a coarse and fine air bubble creation mechanism for membrane and biological aeration, respectively. The dye and chemical oxygen demand (COD) concentration values were measured daily in influent as well as effluent to evaluate the removal efficiencies. Most of the analytical techniques used in this study were mentioned in the standard methods. The removal efficiency of color and COD were 90.71 and 90% in the MBR system, respectively. Using mixed fungal strains in the MBR system is a feasible technique to remove reactive dyes from the textile wastewater. To our knowledge, this is the first report showing the application of mixed filamentous fungal strains in the pilot scale (MBR) system.

Factors affecting fine bubble creation and bubble size for activated sludge

AbstractThis paper addresses a study of air bubble creation in wastewater treatment system using both computational fluid dynamic (CFD) and experimental techniques. Based on the results found in this work, it was found that the bubble size depends on several factors such as flow rate, inlet pressure and contact angle for rubber membrane. Among these factors, it was found that the flow rate has the largest effect on the bubble size followed by membrane material contact angle. The punch size has a moderate effect on the bubble size while the punch length and punch direction have slight effect on bubble size. Finer bubbles are desired and they provide larger surface area and longer residency time which will improve the standard oxygen transfer.

Interfacial and foaming properties of some food grade low molecular weight surfactants

During aeration of food matrices it is important to control the formation and stabilization of air bubbles. An optimal control of air bubble creation allows to modulate the stability and microstructural properties (bubble size) of foamed food products. In this work, we investigated the relationship between the surface properties of different commercially available surfactants with their foaming characteristics. It was found that lamellar phase forming surfactants such as the sodium stearoyl lactylate (SSL) or the mono-, di-glyceride (Cremodan) induced a better foam stability and a lower gas permeability coefficient through a gas/liquid interface than a whey protein isolate (WPI) or micelle forming surfactant Tween 80. This was coupled with the formation of foams having a finer microstructure (bubble size). The obtained foam stability data could be correlated with equilibrium surface tension data.

Design and Implementation of an Auto Bonding Manufacturing Process for Space Solar Cells

This article presents a new manufacturing process of bonding anti-irradiation cover glasses to silicon solar cells with silicone adhesive. Due to the disadvantages of traditional manual operation, a new manufacturing process was designed considering the characteristics of solar cells, cover glasses, and silicone adhesive, and was complemented by an automatic system based on an industrial robot. Experiments indicated that the new approach could ensure the thickness of adhesive layer among 100–150 μm and effectively restrain the creation of air bubbles. The automatic system was tested to have high efficiency and reliability and it was going to make volume-produce.

Near-Field Optical Microscopy of Defects in Cholesteric Oligomeric Liquid Crystal Films

This paper describes formation of 2-D-hexagonal structures with a periodicity ∼0.5–0.8 μm in the defects of thin films of cholesteric oligomeric liquid crystals prepared by the evaporation of the solvent from the oligomer solution on the substrate. These regular arrays were observed by scanning near-field optical and concurrent atomic force microscopy. The mechanisms considered are both Bénard-Marangoni and buoyancy convections induced by solvent evaporation and air-bubble creation around the condensed water droplets from the air during evaporative cooling. Hexagonal structures prepared by this method can be used in photonic devices for emission enhancement, for instance, in liquid crystal lasers and single photon sources with oligomeric liquid crystal hosts.