Flow regime transition identification in three phase co‐current bubble columns

Bubble columns have wide applications in absorption, bio‐reactions, catalytic slurry reactions, coal liquefaction; and are simple to operate, have less operating costs; provide good heat and mass transfer. Experiments have been performed for identifying transition regime in a 15 cm diameter bubble column with liquid phase as water and air as the gas phase. Glass beads of mean diameter 35 µm have been used as solid phase. The superficial gas velocity is in the range 0 ≤ U_g ≤ 16.3 cm/s and superficial liquid velocity in the range of 0 ≤ U_l ≤ 12.26 cm/s. Solid loading up to 9% (w/v) has been used. Pressure signals have been measured using differential pressure transducers (DPTs) at four different axial locations. Classical analysis (Wallis approach and Zuber–Findlay approach), Statistical analysis and Fractal analysis have been used for regime transition identification. Statistical analysis and Fractal analysis have shown almost the same transition points for all the liquid and gas velocities. Effect of solid concentration, liquid velocity and gas velocity over transition regime has also been studied. As the solid concentration is increased it has insignificant effect over transition regime for lower values (<1%), while transition values decrease for higher solid concentration (>1%). © 2012 Canadian Society for Chemical Engineering     

The dissolution of iron from the negative material in pocket plate nickel-cadmium batteries

A common mode of failure of nickel-cadmium flooded pocket plate cells is iron poisoning of the positive plate due to transfer of iron into the active material from active materials and materials of construction. Nickel plated steel pockets are sometimes used to minimize iron dissolution, particularly on the positive electrode. Sometimes-Fe₂O₃ is used as an additive to the cadmium electrode. This paper assesses the extent of dissolution of iron from-Fe₂O₃ by using electron microscopy, X-ray crystallography, cyclic voltammetry, coulometric and atomic absorption measurements.     

The effect of systemic insecticides and nitrogen on oil-filling in developing seeds of toria (Brassica campestris cv. toria)

The systemic insecticides Metasystox and Temik reduced the oil content and increased the free fatty acid and phospholipid contents of the oil of toria seeds at early stages of their development. The oil level was, however, restored when the seeds were sown in soil supplied with nitrogen. At a later developmental stage (30 days after fertilisation), Temik increased, and Metasystox decreased the triacylglycerol content in the oil. Both insecticides increased the relative proportion of erucic acid in the oil, however this increase levelled off in the developing seeds when the toria crop was supplied with nitrogen fertiliser. In in-vivo studies, Metasystox at 10 μg ml^?1 was sufficient to lower the rate of [1-¹⁴C]acetate incorporation into lipids of developing seeds. The effect of Temik on lipid biosynthesis was not as pronounced as that of Metasystox.     

Successful replication of parvovirus B19 in the human megakaryocytic leukemia cell line MB-02

The pathogenic human parvovirus B19 has been shown to undergo productive replication in the erythroid lineage in primary normal human hematopoietic progenitor cells. However, none of the established erythroleukemia cell lines has allowed B19 virus replication in vitro. The remarkable erythroid tissue tropism of B19 virus was evaluated with a human megakaryocytic leukemia cell line, MB-02, which is dependent on the growth factor granulocyte-macrophage colony-stimulating factor but can be induced to undergo erythroid differentiation following treatment with erythropoietin (Epo). Whereas these cells did not support B19 virus DNA replication in the presence of granulocyte-macrophage colony-stimulating factor alone, active viral DNA replication was observed if the cells were exposed to Epo for 5 to 10 days prior to B19 virus infection, as detected by the presence of the characteristic B19 virus DNA replicative intermediates on Southern blots. No replication occurred if the cells were treated with Epo for 3 days or less. In addition, complete expression of the B19 virus genome also occurred in Epo-treated MB-02 cells, as detected by Northern blot analysis. B19 progeny virions were released into culture supernatants that were biologically active in secondary infection of normal human bone marrow cells. The availability of the only homogeneous permanent cell line in which induction of erythroid differentiation leads to a permissive state for B19 virus replication in vitro promises to yield new and useful information on the molecular basis of the erythroid tissue tropism as well as parvovirus B19-induced pathogenesis.     

A review of computerized tomography with application to two-phase flows

The technique of computerized tomography (Ct) has established itself as a leading tool in diagnostic radiology over the past twenty years and is catching on fast in the non-destructive evaluation area in a variety of situations. Ct instrumentation involves a source and a detector system to scan the object of interest. The source can be acoustic, microwave, X-ray, gamma-ray, etc. depending upon the type of material being investigated. For fluid-flows, gamma-rays are quite suitable. There are basically two types of data collection geometries — fan-beam and parallel beam. Fan-beam requires less number of sources as one source feeds several detectors arranged in a fan-beam. The use ofCt in multi-phase flow studies has been limited presently to only a few laboratory experiments and the results indicate thatCt does hold a lot of promise as an effective investigative methodology to understand some of the complex phenomena encountered in multi-phase flows. Some newCt algorithms developed specifically for pipe-flows have shown good results on some air-water flow data for a 15 cm dia pipe.     

Steam generator transient studies using a simplified two-fluid computer code

A simplified two-fluid computer code has been used to simulate reactor-side (or primary-side) transients in a PWR steam generator. The disturbances are modelled as ramp inputs for pressure, internal energy and mass flow-rate for the primary fluid. The CPU time for a transient duration of 4 s is approx. 10 min on a DEC-1090 computer system. The results are thermodynamically consistent and encouraging for further studies.     

Detecting and Classifying Darknet Traffic Using Deep Network Chains

The anonymity of the darknet makes it attractive to secure communication lines from censorship. The analysis, monitoring, and categorization of Internet network traffic are essential for detecting darknet traffic that can generate a comprehensive characterization of dangerous users and assist in tracing malicious activities and reducing cybercrime. Furthermore, classifying darknet traffic is essential for real-time applications such as the timely monitoring of malware before attacks occur. This paper presents a two-stage deep network chain for detecting and classifying darknet traffic. In the first stage, anonymized darknet traffic, including VPN and Tor traffic related to hidden services provided by darknets, is detected. In the second stage, traffic related to VPNs and Tor services is classified based on their respective applications. The methodology of this paper was verified on a benchmark dataset containing VPN and Tor traffic. It achieved an accuracy of 96.8% and 94.4% in the detection and classification stages, respectively. Optimization and parameter tuning were performed in both stages to achieve more accurate results, enabling practitioners to combat alleged malicious activities and further detect such activities after outbreaks. In the classification stage, it was observed that the misclassifications were due to the audio and video streaming commonly used in shared real-time protocols. However, in cases where it is desired to distinguish between such activities accurately, the presented deep chain classifier can accommodate additional classifiers. Furthermore, additional classifiers could be added to the chain to categorize specific activities of interest further.     

Design and Implementation of a State-feedback Controller Using LQR Technique

The main objective of this research is to design a state-feedback controller for the rotary inverted pendulum module utilizing the linear quadratic regulator (LQR) technique. The controller maintains the pendulum in the inverted (upright) position and is robust enough to reject external disturbance to maintain its stability. The research work involves three major contributions: mathematical modeling, simulation, and real-time implementation. To design a controller, mathematical modeling has been done by employing the Newton-Euler, Lagrange method. The resulting model was nonlinear so linearization was required, which has been done around a working point. For the estimation of the controller parameters, MATLAB LQR function has been utilized. Simulation has been performed for the designed controller and it also has been implemented and tested over the real inverted pendulum. From the results, it is vivid that the designed controller keeps the inverted pendulum in an upright position and rejects the disturbances and falling under gravitational force by adjusting the rotation of the horizontal link.     

Hybrid digital-optical correlation employing a chirp-encoded simulated-annealing-based rotation-invariant and distortion-tolerant filter

The simulated annealing (SA) algorithm based on entropy optimization is a technique of synthesizing distortion-invariant matched filters capable of discriminating very similar images. The synthesis of rotation-invariant filters using modified SA-based filter equations and their tolerance to distortions are studied. The filters are trained with true class images rotated in-plane at 3 degrees intervals between 0 degrees and 360 degrees . A total of seven filters are required over the whole range for both CCD or thermal images. Optical correlation in a hybrid digital-optical correlator results in an unwanted zero-order dc along with two first-order (+/-1) correlation peaks. A chirp function multiplied with the filter separates out the three peaks to three different planes, and only one peak in focus is captured in a camera. The performance of the modified SA-based filter has been studied in comparison to the conventional SA filter as well as with other filters.