Development of granular sludge for textile wastewater treatment

Microbial granular sludge that is capable to treat textile wastewater in a single reactor under intermittent anaerobic and aerobic conditions was developed in this study. The granules were cultivated using mixed sewage and textile mill sludge in combination with anaerobic granules collected from an anaerobic sludge blanket reactor as seed. The granules were developed in a single sequential batch reactor (SBR) system under alternating anaerobic and aerobic condition fed with synthetic textile wastewater. The characteristics of the microbial granular sludge were monitored throughout the study period. During this period, the average size of the granules increased from 0.02 ± 0.01 mm to 2.3 ± 1.0 mm and the average settling velocity increased from 9.9 ± 0.7 m h⁻¹ to 80 ± 8 m h⁻¹. This resulted in an increased biomass concentration (from 2.9 ± 0.8 g L⁻¹ to 7.3 ± 0.9 g L⁻¹) and mean cell residence time (from 1.4 days to 8.3 days). The strength of the granules, expressed as the integrity coefficient also improved. The sequential batch reactor system demonstrated good removal of COD and ammonia of 94% and 95%, respectively, at the end of the study. However, only 62% of color removal was observed. The findings of this study show that granular sludge could be developed in a single reactor with an intermittent anaerobic-aerobic reaction phase and is capable in treating the textile wastewater.     

Linear Optical Response of Silicon Nanotubes Under Axial Magnetic Field

We investigated the optical properties of silicon nanotubes (SiNTs) in the low energy region, E < 0.5 eV, and middle energy region, 1.8 eV < E < 2 eV. The dependence of optical matrix elements and linear susceptibility on radius and magnetic field, in terms of one-dimensional (1-d) wavevector and subband index, is calculated using the tight-binding approximation. It is found that, on increasing the nanotube diameter, the low-energy peaks show red-shift and their intensities are decreased. Also, we found that in the middle energy region all tubes have two distinct peaks, where the energy position of the second peak is approximately constant and independent of the nanotube diameter. Comparing the band structure of these tubes in different magnetic fields, several differences are clearly seen, such as splitting of degenerate bands, creation of additional band-edge states, and bandgap modification. It is found that applying the magnetic field leads to a phase transition in zigzag silicon hexagonal nanotubes (Si h-NTs), unlike in zigzag silicon gear-like nanotubes (Si g-NTs), which remain semiconducting in any magnetic field. We found that the axial magnetic field has two effects on the linear susceptibility spectrum, namely broadening and splitting. The axial magnetic field leads to the creation of a peak with energy less than 0.2 eV in metallic Si h-NTs, whereas in the absence of a magnetic field such a transition is not allowed.     

Coordinating context building in heterogeneous information systems

We present an architecture to coordinate the construction of the context within which meaningful information between heterogeneous information systems can be exchanged. We call this coordinator SCOPES (Semantic Coordinator Over Parallel Exploration Spaces). A classification of semantic conflicts we proposed elsewhere is used to build and refine the context, by discovering the semantic mapping rules (inter-schema correspondence assertions) between corresponding elements of the communicating systems. A truth maintenance system is used to manage the multiple intermediate contexts. It provides a mechanism to infer or retract assertions on the basis of the knowledge acquired during the reconciliation process. This nonmonotonic technique is used in conjunction with the Dempster-Shafer theory of belief functions to model the likelihood of alternative contexts. Finally, we propose an algorithm which illustrates how the various components of the architecture interact with one another in order to build context.     

An investigation of yield surfaces based on dislocation mechanics—I: Basic theory

With the help of dislocation theory a new hardening law and a yield criterion are introduced and the initial and subsequent yield surfaces for both single crystals and polycrystalline aggregates are studied.     

On shape factors for irregular particles-I. The steady-state problem. Diffusion and reaction : R. Aris, Chem. Engng Sci. 6: 262–268, 1957

The effectiveness of a catalyst particle with diffusion and first-order reaction is governed by a parameter proportional to the ‘size’ of the particle. If that size is taken to be the ratio of the volume to external surface area, the effectiveness factors for all particle shapes come together asymptotically and are reasonably close together over the whole range.     

Prediction of Daily Pan Evaporation using Wavelet Neural Networks

Prediction of daily evaporation has an important role in reservoir management, regional water planning and evaluation of drinking-water supplies. The main purpose of this study was to assess different types of mother wavelet as activation functions instead of commonly used sigmoid for finding the main differences in the results of daily pan evaporation prediction in the Lar synoptic station. So, using conjunction of wavelet theory and multilayer perceptron (MLP) network, two mother Wavelets named Mexican Hat and polyWOG1 are considered for developing hybrid WNNs. The algorithms were trained and tested using a 6-year data record (1999 daily values) from 2005/01/01 to 2010/09/01. Instead of using common sigmoid activation functions in MLP network, wavelet function was applied to construct the wavelet neural network. Results show that Mexican hat wavelet neural network in the best topology presents 98.35?% accuracy in training phase and 96.04?% in testing and PolyWOG1 wavelet neural network in the best topology presents 95.92?% accuracy in training phase and 91.03?% in testing of model. In the MLP model with standard sigmoid function results were 90.6?% in training and 87.63?% in testing. Comparison of WNN and MLP shows that Mexican hat mother wavelet could have better accuracy in the daily pan evaporation modeling.     

The identification of the allylic nitrite and nitro derivatives of methyl linoleate and methyl linolenate by negative chemical ionization mass spectroscopy

The autoxidation of polyunsaturated fatty acids is initiated bothin vivo andin vitro by nitrogen dioxide. The mechanism of the initiation process is believed to involve both addition reactions and hydrogen atom abstraction reactions, with hydrogen abstraction predominating at low levels of nitrogen dioxide. Therefore low levels of nitrogen dioxide should react with polyunsaturated fatty acids to give allylic derivatives; in an anaerobic system these derivations should be allylic nitro and nitrite compounds. Using negative methane chemical ionization mass spectrometry and other analytical techniques, we have identified these allylic nitrite and nitro compounds from the reactions of low levels of nitrogen dioxide with methyl linoleate and methyl linolenate in the absence of oxygen.     

Short-echo-time magnetic resonance phase-shift velocity mapping for assessment of heart valve and great vessel stenoses: three years' experience

Shortening the echo times of magnetic resonance (MR) sequences used for phase-shift velocity mapping to 3.6 ms has extended use of the technique to measurement of velocities in turbulent, poststenotic jet flows. We used a 0.5-T MR machine and field even-echo rephasing (FEER) sequences with 3.6 ms echo times for jet velocity mapping.In vitro trials used continuous flow through a phantom with a 6-mm stenosis. Fifteen patients with mitral and/or aortic valve stenosis and 20 patients with repaired aortic coarctation were studied prospectively, with Doppler ultrasonic measurement of peak jet velocity performed independently on the same day. The clinical contribution of MR jet velocity mapping, used during a 3-year period in 306 patients with congenital and acquired disease of heart valves, great vessels, and conduits, was assessed retrospectively. The 3.6-ms sequence allowed accurate measurement of jet velocities up to 6 m s^–1 in vitro (r=0.996). Prospective studies in patients showed good agreement between MR and Doppler measurements of peak velocity:n=38; range, 1.2–6.1 m s^–1; mean, 2.7 m s^–1; mean of differences (Doppler-MR), 0.22 ms^–1; standard deviation of differences, ±0.38 m s^–1 (±14%). MR jet velocity mapping proved particularly valuable for assessment and localization of stenoses at sites where ultrasonic access was limited. The technique represents a diagnostic advance which can obviate the need for catheterization in selected cases.     

MODCAD

This paper discusses the development of a predetermined time system software that utilizes graphics as a method of interaction with the user. The software uses MODAPTS as the basis of analysis and AutoCAD/AutoLisp to create graphic tools in the analysis.     

Multiple oxidation reactions and diffusion in the catalytic layer of monolith reactors

Oxidation reactions of mobile exhaust gas in a catalytic monolith are considered in this paper. The exhaust gas is described by four concentrations, namely those of the carbon monoxide, fast- and slow-oxidizing hydrocarbons and hydrogen. The problem of multiple reactions and diffusion in the catalytic layer of the monolith walls is studied first. The diffusional resistance of the catalytic layer is often significant in spite of its thinness and it seems important to allow for both the hydrogen and hydrocarbon oxidation reactions in analyzing the system for steady-state. The influence of hydrogen on the multiplicity of steady-state wall temperatures is also studied and it is found to be important, because hydrogen reacts rapidly at lower temperatures.