Modeling and performance prediction of chromate reduction by iron oxide coated sand in adsorber reactors

Iron oxide coated sand (IOCS) as an adsorbent medium for removing hexavalent chromium (Cr(VI)) from industrial wastewater, as well as in permeable reactive barriers for remediation of Cr(VI) in aquifers is investigated in this study. An important feature was the use of a mathematical model for performance forecasting and process upscaling of IOCS fixed‐bed adsorber systems for Cr(VI) removal. Another significance aspect was the elucidation of IOCS surface mechanisms and interactions responsible for Cr(VI) sorption and reduction to the less toxic Cr(III). The adsorption equilibrium and mass‐transfer parameters for modeling were obtained from independent laboratory studies. Adsorber studies validated the predictive model and established the effectiveness of IOCS for Cr(VI) removal under different conditions. Model simulation studies demonstrated that adsorbent capacity, surface diffusion, and film transfer significantly influenced process dynamics. The study showed that IOCS can be used to remove Cr(VI) from contaminated waters, meeting the overall objectives of regulatory agencies. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3717–3729, 2016     

Photooxidation and biotrickling filtration for controlling industrial emissions of trichloroethylene and perchloroethylene

A two-stage process integrating ultraviolet oxidation and biotrickling filtration (UV-BTF) was developed for treatment of industrial air streams contaminated with trichloroethylene (TCE) and perchloroethylene (PCE). Laboratory-scale studies demonstrated that the UV-BTF system consistently achieved contaminant removal efficiencies of 99-100% under optimal conditions. The UV-BTF process employs an advanced oxidation process (AOP) such as UV photooxidation as pretreatment for alleviating biological toxicity attributed to high and/or fluctuating contaminant concentrations, and for transforming the contaminants to more easily biodegradable products. The UV-BTF process showed significantly better performance than the BTF process without UV photooxidation pretreatment. Free-radical reaction mechanisms, pathways, and product formations were proposed for the UV photolysis of TCE and PCE. The photooxidation was mediated by chlorine atom reactions, and the principal products for TCE were phosgene, dichloroacetyl chloride (DCAC), low levels of trichloroacetyl chloride (TCAC), carbon monoxide, and hydrochloric acid; while those for PCE were phosgene, TCAC, low levels of DCAC, carbon dioxide, and hydrochloric acid. These products were identified and quantified by a combination of techniques, namely, gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared (FTIR) spectroscopy. These photooxidation products were completely removed in the BTF stage of the UV-BTF process, as indicated by subsequent GC-MS analyses. The destruction of photolysis products in the BTF stage occurred by a combination of hydrolysis, adsorption and microbial degradation.     

An objective function for vertically partitioning relations in distributed databases and its analysis

Partitioning and allocation of relations is an important component of the distributed database design. Several approaches (and algorithms) have been proposed for clustering data for pattern classification and for partitioning relations in distributed databases. Most of the approaches used for classification use square-error criterion. In contrast, most of the approaches proposed for partitioning of relations are eitherad hoc solutions or solutions for special cases (e.g., binary vertical partitioning).In this paper, we first highlight the differences between the approaches taken for pattern classification and for distributed databases. Then an objective function for vertical partitioning of relations is derived using the square-error criterion commonly used in data clustering. The objective function derived generalizes and subsumes earlier work on vertical partitioning. Furthermore, the approach proposed in this paper is shown to be useful for comparing previously developed algorithms for vertical partitioning. The objective function has also been extended to include additional information, such as transaction types, different local and remote accessing costs and replication. Finally, we discuss the implementation of a distributed database design testbed. Recommended by: A. Sheth     

Conduction studies in anthraquinone derivatives. VI

Contrary to the results of the early 1960s, it has been found that the anthraquinone (AQ) and its derivatives can be made photoconductive (I _ph/I_D 10³) by substituting suitable donors in the periphery of the benzenoid rings. The conductivity of the AQ derivatives, generally speaking, are not as good as those of the charge transfer kind. The darkcurrent in the case of AQ derivatives ranges from 10^–14–10^–12 for 9,10-AQ to 10^–10–10^–8 for 1,4,5,8-tetra amino AQ. The AQs are n-type semiconductors with electrons being the majority charge carriers. In the present article, we describe the charge carrier generation and transport processes in three di-substituted AQ derivatives whose spectral properties have been well studied. The magnetic field effect has been observed for the first time in these compounds.     

Discrepancies between the NMR and X-ray structures of uncomplexed barstar: analysis suggests that packing densities of protein structures determined by NMR are unreliable

The crystal structure of the C82A mutant of barstar, the intracellular inhibitor of the Bacillus amyloliquefaciens ribonuclease barnase, has been solved to a resolution of 2.8 A. The molecule crystallizes in the space group I41 with a dimer in the asymmetric unit. An identical barstar dimer is also found in the crystal structure of the barnase-barstar complex. This structure of uncomplexed barstar is compared to the structure of barstar bound to barnase and also to the structure of barstar solved using NMR. The free structure is similar to the bound state, and there are no significant main-chain differences in the 27-44 region involved in barstar binding to barnase. The C82A structure shows significant differences from the average NMR structure, both overall and in the binding region. In contrast to the crystal structure, the NMR structure shows an unusually high packing value based on the occluded surface algorithm, indicating errors in the packing of the structure. We show that the NMR structures of homologous proteins generally show large differences in packing value, while the crystal structures of such proteins have very similar packing values, suggesting that protein packing density is not well determined by NMR.     

Numerical and Physical Simulation of the Fluid Flow in a Beam Blank Mold Fed Through the Center of the Web

Metallurgical and Materials Transactions B - Fluid flow inside a beam blank mold fed through a three-port SEN (two lateral ports and one bottom port), positioned at the center of the mold, has been...     

A CAD system design to diagnosize alzheimers disease from MRI brain images using optimal deep neural network

Memory related issues in brain are mainly caused by Alzheimer disease (AD) which is the most common form of dementia. This disease must be diagnosed in its prodromal stage known as Mild Cognitive Impairment (MCI) also it needs an accurate detection and classification technique. In this paper, a computer-aided diagnosis (CAD) system is implemented on Magnetic resonance imaging (MRI) data from ADNI database. This disease highly affects the Hippocampus and cerebrum regions which are normally found in the grey matter region of brain. At first, MNI/ICBM atlas space of every three dimensional MRI images are constructed using normalization procedure, then grey matter region of brain is extracted. Subsequently, feature extraction is done by two dimensional Gabor filter in three scales and eight orientations. Then, the proposed optimal Deep Neural Network (DNN) classifier is used to classify the images as Cognitive normal (CN), Alzheimer disease (AD), and Mild Cognitive Impairment (MCI). Here, DNN classifier is optimized by selecting optimal weight parameter using Enhanced Squirrel Search Algorithm. The experimental results prove an efficiency of the proposed method using MR images. The proposed algorithm beats existing techniques in terms of accuracy, sensitivity, and specificity.

     

Weaves: A Framework for Reconfigurable Programming

This paper presents a language independent runtime framework—called Weaves—for object based composition of unmodified code modules that enables selective sharing of state between multiple control flows through a process. Furthermore, the framework allows dynamic instantiation of code modules and control flows through them. In effect, weaves create intra-process modules (similar to objects in OOP) from code written in any language. Applications can be built by instantiating Weaves to form Tapestries of dynamically interacting code. The framework enables objects to be arbitrarily shared—it is a true superset of both processes as well as threads, with code sharing and fast context switching time similar to threads. Weaves does not require any special support from either the language or application code—practically any code can be weaved. Weaves also include support runtime loading and linking of object modules enabling the next generation of highly dynamic applications. This paper presents the elements of the Weaves framework and its implementation on the Linux platform over source-code independent ELF object files. The current implementation has been validated over Sweep3D, a benchmark for 3D discrete ordinates neutron transport (Koch et al. Trans. Am. Nucl. Soc. 65 (198) [1992]), and a user-level port of the Linux 2.4 family kernel TCP/IP protocol stack.     

Joint space-time interpolation for distorted linear and bistatic array geometries

This paper presents a new joint space-time interpolation technique (STINT) to improve the small sample support performance of space-time adaptive processing (STAP) with distorted linear monostatic arrays and linear bistatic array configurations. Brennan's rule for the space-time clutter covariance matrix rank is extended to monostatic linear arrays with arbitrary intersensor spacing, distorted linear arrays and bistatic geometries. It is shown that both distortion in the array geometry and bistatic operation increase the clutter rank and cause the space-time clutter covariance matrix to become range dependent. This results in lower output signal-to-interference-plus-noise ratio (SINR) for the same number of adaptive degrees of freedom and reduced available sample support. This motivates the development of the STINT technique aimed at compensating for the clutter rank inflation, while also making the clutter statistics appear more stationary across range. More specifically, a linear transformation is designed that maps the received clutter across space and time to that which would be received by a "virtual" monostatic side-looking ULA. By mapping the data to form a reduced rank clutter covariance matrix, fewer snapshots are needed for a statistically stable matrix inversion as required in STAP, thereby improving the short observation time performance. Simulation results for a typical airborne radar scenario indicate up to 10-dB SINR improvement can be obtained using STINT with limited sample support.