Continuous supercritical water gasification of isooctane: A promising reactor design

A new design of supercritical water gasification system was developed to achieve high hydrogen gas yield and good gas–liquid flow stability. The apparatus consisted of a reaction zone, an insulation zone and a cooling zone that were directly connected to the reaction zone. The reactor was set up at an inclination of 75° from vertical position, and feed and water were introduced at the bottom of the reactor. The performances of this new system were investigated with gasification of isooctane at various experimental conditions – reaction temperatures of 601–676 °C, residence times of 6–33 s, isooctane concentrations of 5–33 wt%, and oxidant (hydrogen peroxide) concentrations up to 4507 mmol/L without using catalysts. A significant increase in hydrogen gas yield, almost four times higher than that from the previous up-down gasifier configuration (B. Veriansyah, J. Kim, J.D. Kim, Y.W. Lee, Hydrogen Production by Gasification of Isooctane using Supercritical Water, Int. J. Green Energy. 5 (2008) 322–333) was observed with the present gasifier configuration. High hydrogen gas yield (6.13 mol/mol isooctane) was obtained at high reaction temperature of 637 °C, a low feed concentration of 9.9 wt% and a long residence time of 18 s in the presence of 2701.1 mmol/L hydrogen peroxide. At this condition, the produced gases mainly consisted of hydrogen (59.5 mol%), methane (14.8 mol%) and carbon dioxide (22.0 mol%), and a small amount of carbon monoxide (1.6 mol%) and C₂–C₃ species (2.1 mol%). Reaction mechanisms of supercritical water gasification of isooctane were also presented.     

Adjoint EKF learning in recurrent neural networks for nonlinear active noise control

In this paper, active noise control using recurrent neural networks is addressed. A new learning algorithm for recurrent neural networks based on Adjoint Extended Kalman Filter is developed for active noise control. The overall control structure for active noise control is constructed using two recurrent neural networks: the first neural network is used to model secondary path of active noise control while the second one is employed to generate control signal. Real-time experiment of the proposed algorithm using digital signal processor is carried-out to show the effectiveness of the method.     

Continuous synthesis of surface-modified zinc oxide nanoparticles in supercritical methanol

Continuous synthesis of surface-modified zinc oxide (ZnO) nanoparticles was examined using surface modifiers (oleic acid and decanoic acid) in supercritical methanol at 400 °C, 30 MPa and a residence time of ∼40 s. Wide angle X-ray diffraction (WAXD) analysis revealed that the surface-modified nanoparticles retained ZnO crystalline structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the surface modifiers changed drastically the size and morphology of the ZnO nanoparticles. When the molar ratio of oleic acid to Zn precursor ratio was 30, 10 nm size particles with low degree of aggregation were produced. The surface-modified ZnO nanoparticles had higher BET surface areas (29-36 m²/g) compared to unmodified ZnO particles synthesized in supercritical water (0.7 m²/g). Fourier transform infrared (FT-IR) and thermogravimetric analysis (TGA) indicated that aliphatic, carboxylate and hydroxyl groups were chemically attached on the surface of ZnO nanoparticles. Long-term (80 days) dispersion test using ultraviolet transmittance showed that the surface-modified ZnO particles had enhanced dispersion stability in ethylene glycol.     

The dependence of microdroplet size on the parameters governing the dewetting process on circular micropillar arrays

We theoretically investigated the correlation among the size of microdroplet, the geometrical parameters of circular micropillars, and the parameters governing the dewetting process. Dimensional analysis is used to determine independent dimensionless groups to characterize the diameter of microdroplet, i.e., the Ohnesorge number (Oh), the capillary number (Ca), the dimensionless liquid thickness (H), and the contact angle (θ). The simulation results show that the size of microdroplet on the top surface of micropillar depends on the parameters in the dewetting process. The dimensionless droplet diameter (d) grows with the increase of H, where d becomes saturated provided H reaches a critical value of 2.5. The decrease of Ohnesorge number results in microdroplets with large diameter. For small contact angle, the top surface of micropillar is mostly wetted, which leads to large microdroplets. When the value of the capillary number increases, the viscous force on the top surface of micropillar magnifies, and leads to the growth of droplet diameter until the value of Ca reaches a critical value. For H < 2.5, the magnitude of the critical capillary number (Ca^c) depends on Oh, θ, and H*, while Ca^c is a constant for H ≥ 2.5. The dimensionless droplet diameter (d) can be determined by the product of functions of Oh, θ, H*, and Ca*.     

Organizational culture and willingness to share knowledge: A competing values perspective in Australian context

A considerable amount of research has confirmed the relationship between organizational culture and knowledge sharing behaviours. However, less research has been conducted on the impact of project sub-cultures in relation to the sharing of knowledge between projects, particularly in project based organizations (PBOs). The unique structures and contexts characterized by PBOs indicate the need to investigate further the impact of cultures present within PBOs and their effect on knowledge sharing. We report on a rich case study of four large Australian-based PBOs whereby the cultural values of these large organizations were seen to impact significantly on whether project teams were more or less likely to improve inter-project knowledge sharing. Furthermore, this research demonstrates the utility of using Cameron and Quinn's (2005) Competing Values Framework to evaluate culture in the context of PBOs.     

A novel colorimetric food package label for fish spoilage based on polyaniline film

A novel colorimetric method based on polyaniline (PANI) film for the development of smart packaging, as a chemical sensor for real-time monitoring of the microbial breakdown products in the headspace of packaged fish is described. This on-package indicator contains PANI film, that responds through visible color change to a variety of basic volatile amines (specifically known as total volatile basic nitrogen (TVBN)) released during fish spoilage period. The PANI film characteristics and its response to TVBN were studied. A kinetic approach was used to correlate the ammonia response of the PANI film to that of the fish spoilage. Color changes, in terms of total color difference of PANI, correlated well with TVBN levels of fish. Apart from TVBN, trials on milkfish sample (Chanos chanos) have verified that the PANI film response also correlates well with microbial growth patterns in fish samples, especially the changing microbial populations (total viable count (TVC) and Pseudomonas spp.). These responses enabled the real-time monitoring of fish spoilage either at various constant temperatures or with temperature fluctuations. The PANI film can be recycled several times using an acid solution to regenerate the PANI surface. Thus, PANI film can be considered as a low-cost sensor suitable for smart packaging applications.     

New Design of Conduit Plasma Atomization for Fabricating Spherical Metal Powder and its Optimization Using Design of Experiments Method

Powder Metallurgy and Metal Ceramics - This research presents a new design of plasma atomization conducted using a graphite plasma conduit to assure prolonged interaction between molten metal and...     

The Effect of Stearic Acid on Expanded Organoclay and Rheometric Properties of Natural Rubber/Expanded Organoclay Nanocomposites

The effect of stearic acid on expanded organoclay and rheometric properties of natural rubber （NR）/expanded organoclay （OCSA） was studied. The expanded organoclay was prepared by melting of stearic acid （SA） in an oven at 100 ~C for 1 h. NR/expanded organoclay nanocomposites were prepared by melt intercalation technique using a laboratory open mill followed by compression molding. The characterizations were carried out by means of X-ray diffraction, field emission scanning electron microscopy （FESEM） and moving die rheometer. The results showed that the stearic acid intercalated in the gallery of organoclay （OC） Cloisite~ 20A, so the d-spacing of organoclay increased with increasing of stearic acid concentration. The rheometric properties showed that the increasing concentration of stearic acid in NR compound improved the resistance to reversion but contrary for NR/OCSA compounds. The curing time of NR filled expanded organoclay compounds were faster than NR compounds. The increasing of stearic acid in rubber compounds and NR/expanded organoclay compounds increased the curing time （tgo） of compounds. The increasing concentration of stearic acid reduced the size of aggeragate especially for ratio OC：SA - 1：l which OCSA dispersed uniformly in NR matrix.