Methacrylic acid–acrylamide-g-poly(ethyleneterephthalate) fibres for urea hydrolysis

This paper presents the results of urease immobilization onto methacrylic acid–acrylamide grafted poly(ethyleneterephthalate) fibres. The graft yield strongly affected the maximum activity of the immobilized enzyme up to a value of 70·2%. Higher grafting caused a decline in urease activity and led to the degradation of the fibres. The minor changes observed in K_m and V_max demonstrated that the conformational changes existed during immobilization were not extensive. However, 70·2% methacrylic acid–acrylamide-g-fibres containing urease were more stable towards acidic and alkaline pH, high temperature and storage conditions compared with free enzyme. Apart from the increase in stability to heat inactivation, the initial enzymatic activity of the urease–fibre system remained almost unchanged even after 40 repeated assays corresponding to 10 h of operation in 4 months, indicating the excellent durability of the system.     

HihO: accelerating artificial intelligence interpretability for medical imaging in IoT applications using hierarchical occlusion

Neural Computing and Applications - In the medical imaging domain, nonlinear warping has enabled pixel-by-pixel mapping of one image dataset to a reference dataset. This co-registration of data...     

Robust control of variable speed autonomous underwater vehicle

Set point tracking control of autonomous underwater vehicle (AUV) via robust model predictive control (RMPC) is considered. Input-constrained RMPC with integral action, which has been developed in our previous work, is used to control the AUV in this study. In order to derive a RMPC control rule, non-linear dynamics of AUV with six degree of freedom is linearized at certain operating points. So, horizontal and vertical plane dynamics of system are represented by linear models which have polytopic uncertainties. Since the derived control rule will be used in real time, the computation time should be reduced. To overcome this computational time problem and get rid of trial–error step of Algorithm 1, a new algorithm is proposed here. The simulations are carried out using the control rule based on this algorithm and these results are presented.     

Prioritized Mobile Robot Exploration Based on Percolation Enhanced Entropy Based Fast SLAM

The major aim in search and rescue using mobile robots is to detect and reach trapped survivors and to support rescue operations through disaster environments. Our motivation is based on the fact that a search and rescue (SAR) robot can navigate within and penetrate a disaster area only if the area in question possesses connected voids. Traversability or penetrability of a disaster area is a primary factor that guides the navigation of a search and rescue (SAR) robot, since it is highly desirable that the robot, without hitting a dead end or getting stuck, keeps its mobility for its primary task of reconnaissance and mapping when searching the highly unstructured environment. We propose a novel percolation guidance that collaborates with entropy based SLAM under a switching control setting the priority to either position or map accuracy. This newly developed methodology has proven to combine the superiority of both percolator guidance and entropy based prioritization so that the active SLAM becomes speedy, with high coverage rate of the area as well as increased accuracy in localization. Our percolator guidance stems from a frontier based conditioning of a-posteriori occurrences of upcoming connected voids that uses the fact that every obstacle partially seen at the frontier of the explored domain has a spatial continuity into the unexplored area. The developed modular architecture is introduced in details and demonstrative examples are provided and discussed.     

Verifying anonymity in voting systems using CSP

We present formal definitions of anonymity properties for voting protocols using the process algebra CSP. We analyse a number of anonymity definitions, and give formal definitions for strong and weak anonymity, highlighting the difference between these definitions. We show that the strong anonymity definition is too strong for practical purposes; the weak anonymity definition, however, turns out to be ideal for analysing voting systems. Two case studies are presented to demonstrate the usefulness of the formal definitions: a conventional voting system, and Prêt à Voter, a paper-based, voter-verifiable scheme. In each case, we give a CSP model of the system, and analyse it against our anonymity definitions by specification checks using the Failures-Divergences Refinement (FDR2) model checker. We give a detailed discussion on the results from the analysis, emphasizing the assumptions that we made in our model as well as the challenges in modelling electronic voting systems using CSP.     

Prediction of suspended sediment concentration from water quality variables

This study investigates use of water quality (WQ) variables, namely total chromium concentration, total iron concentration, and turbidity for predicting suspended sediment concentration (SSC). For this purpose, the artificial neural networks (ANNs) and regression analysis (RA) models are employed. Seven different RA models are constructed, considering the functional relation between measured WQ variables and SSC. The WQ and SSC data are fortnightly obtained from six monitoring stations, located on the stream Harsit, Eastern Black Sea Basin, Turkey. A total of 132 water samples are collected from April 2009 to February 2010. Model prediction results reveal that ANN is able to predict SSC from WQ data, with mean absolute error (MAE) of 10.30 mg/L and root mean square error (RMSE) of 13.06 mg/L. Among seven RA models, the best one, which has the form including all independent parameters, produces results comparable to those of ANN, with MAE = 14.28 mg/L and RMSE = 15.35 mg/L. The sensitivity analysis results reveal that the most effective parameter on the SSC is total chromium concentration. These results have time- and cost-saving implications.     

CFD SIMULATION OF THE GAS-SOLID FLOW IN THE RISER OF A CIRCULATING FLUIDIZED BED WITH SECONDARY AIR INJECTION

A comprehensive investigation was carried out to study hydrodynamics aspects of secondary air injection in circulating fluidized beds. This article presents modeling and results of computational fluid dynamics simulations of gas-solid flow in the riser section of a laboratory-scale (ID = 0.23 m, height = 7.6 m) circulating fluidized bed with a radial secondary air injector. The gas-solid flow model is based on the two-fluid (Eulerian-Eulerian) approach, where both gas and solids phases are treated as interpenetrating continua. A granular kinetic theory model is used to describe the solids phase stresses. The simulation results are compared with measured pressure drop and axial particle velocity profiles; reasonable agreement is obtained. Qualitatively, excellent agreement is obtained in predicting the increase in solids volume fraction below secondary air ports, the accumulation of solids around the center of the riser due to momentum of secondary air jets, and the absence of the solids down-flow near the wall above the secondary air injection ports, which are the prominent features of secondary air injection observed in the experiments.     

Degradation of 4-chloro-2-methylphenol in aqueous solution by electro-Fenton and photoelectro-Fenton processes

Degradation of 4-chloro-2-methylphenol (PCOC), a refractory toxic chemical emitted to the environment from the industrial production of phenoxy herbicides was studied in aqueous solution. Electro-Fenton and photoelectro-Fenton processes were used as the degradation methods. H₂O₂, produced by the reduction of oxygen at carbon cathode reacted with dissolved metal ions to form hydroxyl radicals, which in turn reacted with PCOC sequentially to degrade the aromatic ring. The effects of using different [Fe²⁺]/[PCOC]₀ and the effect of replacing Fe²⁺ by Mn²⁺ ion have been examined. It was found that degradation rate was increased with increasing [Fe²⁺]/[PCOC]₀ ratio from 2 to 4. However, the total charge utilized during the treatment was also increased. The efficiency of PCOC degradation was observed to be higher when Mn²⁺ was used as the catalyst. The mineralization of aqueous solutions of PCOC, withdrawn from the reactor at certain time interval, has been followed by total organic carbon (TOC) decay and dechlorination. A fast and complete degradation of the aromatic ring was achieved in photoelectro-Fenton system. 41.7% TOC decay and complete dechlorination were observed by consuming only 141.4 C electrical charge during a 300 min photoelectron-Fenton treatment. In the case of electro-Fenton system, 280.7 C electrical charge was consumed during 450 min of electrolysis to attain a similar degradation of PCOC. 14.9% TOC removal and 89.3% dechlorination have been obtained in this system under the applied conditions.     

Poly(Li‐2‐hydroxyethyl methacrylate)‐co‐poly(4‐vinyl pyridine): Molar mass effects on strong electrorheological response

Electrorheological (ER) fluids display remarkable rheological behavior, being able to convert rapidly and repeatedly from a fluid to a solid‐like when an external electric field (E) is applied or removed. In this study, electrical and ER properties of poly(Li‐2‐hydroxyethyl methacrylate)‐co‐poly(4‐vinyl pyridine), poly(Li‐HEMA)‐co‐poly(4‐VP), copolymeric salts (ionomers) were investigated. For this purpose six ionomers were synthesized with different molar masses. They were then ground‐milled for a few hours to obtain micron size ionomers. The particle sizes of the ionomers were determined by dynamic light scattering. Suspensions of ionomers were prepared in silicone oil (SO), at a series of concentrations (c = 5–30%, m/m). The gravitational stability of suspensions against sedimentation was determined at constant temperature (T = 25°C). Flow times of the suspensions were measured under no electric field (E = 0 kV/mm), and under an external applied electric field (E ≠ 0 kV/mm) strengths and a strong ER activities were observed for all the poly(Li‐HEMA)‐co‐poly(4‐VP)/SO suspensions. Further, the effects of suspension concentration, mole ratios of poly(HEMA) and poly(4‐VP), and the overall molar mass of the copolymers, shear rate, electric field strength, frequency, promoter, and temperature onto ER activities of ionomer suspensions were investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1065–1074, 2006