Ca2+ ⇌ Pb2+ exchange reaction of calcium silicate hydrate: Ca5Si6O18H2 · 4H2O

Recently it has been demonstrated that synthetic calcium silicate hydrate Ca₅Si₆O₁₈H₂ · 4H₂O shows cation exchange properties. In this paper we give the mass balance and thermodynamic data of the Ca²⁺ Pb²⁺ exchange which occurs in 1.1 nm tobermorite when placed in dilute Pb²⁺ solutions. The solid and solution phases have been analysed. The free energy of the exchange reaction at room temperature has been calculated. The X-ray powder diffraction data of the exchanged product have been reported. The crystallinity of the exchanger remains intact after ion exchange.     

Hybrid Fractal Antenna Using Meander and Minkowski Curves for Wireless Applications

Wireless Personal Communications - This paper describes a novel design of Minkowski and Meander curves based hybrid fractal antenna for mobile devices used for communication in delay tolerant...     

A Comparative Study of Artificial Neural Network and Response Surface Methodology for Optimization of Friction Welding of Incoloy 800 H

This article deals with the optimization of process parameters for friction welding of Incoloy 800 H rod and compares the results obtained by response surface methodology(RSM) and artificial neural network(ANN).The experiments were carried out on the basis of a five-level,four-variable central composite design.The output parameters were the tensile strength and burn-off length(BOL).They were considered as a function of four independent input variables,namely heating pressure(HP),heating time,upsetting pressure(UP),and upsetting time.The RSM results showed that the quadratic polynomial model depicted the interconnection between individual element and response.For optimizing the process parameters,ANN analysis was used,and the optimal configuration of the ANN model was found to be 4–9–2.For modeling aspect,a requisite trained multilayer perceptron neural network was rooted,and a quick propagation training algorithm was used to train ANN.The purpose of optimization was to decide the maximum tensile strength and minimum burn-off length of the welded joint which was done by varying the friction welding process variables.The order of importance of input parameters for friction welding of Incoloy 800 H was HP [ UP [ N [ BOL.After predicting the model using RSM and ANN,a comparison was made for predicting the effectiveness of two methodologies.By analyzing the results,it was observed that as compared to RSM,ANN model was more specific.     

Thermal deactivation studies of coconut shell pyrolysis

The kinetics of pyrolysis of predried coconut shell sample has been investigated in the temperature range of 523 K to 1023 K in an inert atmosphere by captive sample technique. A kinetic scheme has been proposed where two parallel reactions are given for the production of volatiles and char. The reaction rate constants are found to decrease with high temperatures above 673 K due to chemical and physical changes of the reactant during devolatilisation reaction. Several deactivation models have been proposed to give good agreement with the experimental data.     

Experimental modeling and optimization of electric discharge diamond face grinding of metal matrix composite

Machining of metal matrix composites (MMCs) has been a big challenge for manufacturing industries due to its superior mechanical properties. Unconventional machining methods have become an alternative to give desired shapes with intricate profiles and stringent design requirements. The present research investigates the grinding performance of copper–iron–graphite MMC using electric discharge diamond face grinding (EDDFG), which is electric discharge machining-based hybrid machining process. Experiments have been performed on a self-developed experimental setup of EDDFG with scientifically designed experiments. Effects of process input parameters on two important performances, material removal rate (MRR) and surface roughness (SR), have been analyzed. Genetic algorithm-based optimization of MRR and SR models show considerable improvements in both characteristics, as confirmed by verification experiments. Results reveal that peak current is a common significant factor for both MRR and SR.     

Synthesis,characterization, and thermal and antimicrobial studies of newly developed transition metal–polychelates derived from polymeric Schiff base

Monomeric Schiff base derived from salicylaldehyde and 1,3‐diaminopropane was subjected to polycondensation reaction with formaldehyde and piperazine in basic medium. The resin was found to form polychelates readily with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) metal ions. The materials were characterized by elemental analysis, spectral studies (IR, ¹H‐NMR, ¹³C‐NMR, and UV–visible), magnetic moment measurements, and thermal analysis. The electronic spectra and magnetic moment measurements of the synthesized polychelates confirmed the geometry of the central metal ion. Metal–resin bonds were registered in the IR spectra of the polychelates. The thermogravimetric analysis data indicated that the polychelates were more stable than the corresponding polymeric Schiff base. All the synthesized metal–polychelates showed excellent antibacterial activities against the selected bacteria. The antimicrobial activities were determined by using the shaking flask method, where 25 mg/mL concentrations of each compound were tested against 10⁵ CFU/mL bacteria solutions. The number of viable bacteria was calculated by using the spread‐plate method, where 100 μL of the incubated antimicrobial agent in bacteria solutions were spread on agar plates, and the number of bacteria was counted after 24 h of incubation period at 37°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A Graph Drawing Based Spatial Mapping Algorithm for Coarse-Grained Reconfigurable Architectures

Recently coarse-grained reconfigurable architectures (CGRAs) have drawn increasing attention due to their efficiency and flexibility. While many CGRAs have demonstrated impressive performance improvements, the effectiveness of CGRA platforms ultimately hinges on the compiler. Existing CGRA compilers do not model the details of the CGRA, and thus they are i) unable to map applications, even though a mapping exists, and ii) using too many processing elements (PEs) to map an application. In this paper, we model several CGRA details, e.g., irregular CGRA topologies, shared resources and routing PEs in our compiler and develop a graph drawing based approach, split-push kernel mapping (SPKM), for mapping applications onto CGRAs. On randomly generated graphs our technique can map on average 4.5times more applications than the previous approach, while generating mappings which have better qualities in terms of utilized CGRA resources. Utilizing fewer resources is directly translated into increased opportunities for novel power and performance optimization techniques. Our technique shows less power consumption in 71 cases and shorter execution cycles in 66 cases out of 100 synthetic applications, with minimum mapping time overhead. We observe similar results on a suite of benchmarks collected from Livermore loops, Mediabench, Multimedia, Wavelet and DSPStone benchmarks. SPKM is not a customized algorithm only for a specific CGRA template, and it is demonstrated by exploring various PE interconnection topologies and shared resource configurations with SPKM.     

Two-warehouse inventory model with ramp-type demand and partially backlogged shortages

In this article, we consider an inventory model for items that are stored in two-warehouses when demand is a general ramp-type function of time. Shortages are allowed and a constant fraction of shortages is backlogged. The existence and uniqueness of optimal solution is proved for both – the single-warehouse and the two-warehouse models. An algorithm is developed to facilitate the choice between the two-warehouse and the single-warehouse systems and hence to obtain the optimal replenishment policy. Numerical examples are presented. Sensitivity analysis with respect to the parameters of the model is performed.     

1‐(bromoacetyl)pyrene and its arsonium salt as novel photoinitiators for styrene polymerization

The photopolymerization of styrene (Sty) in DMSO induced by pyrene (Py), 1‐Acetylpyrene (AP), 1‐(Bromoacetyl) pyrene (BP), and 1‐Acetylpyrene triphenyl arsonium bromide (APAS) has been investigated. Under all conditions employed, Py was completely ineffective. Incorporation of a chromophoric (? COCH₃) moiety introduces photoinitiating activity into Py. It was observed that introduction of Br into AP markedly accelerated the rate of UV irradiation‐induced polymerization. BP was further modified to its arsonium salt (APAS). The kinetics and mechanism of polymerization using BP and APAS as initiators have been investigated in detail. The polymerization with BP followed nonideal kinetics (R_p ∝ [BP]^0.8 [Sty]^1.1) with respect to initiator concentration whereas ideal kinetics (R_p ∝ [APAS]^0.48 [Sty]^1.1) was observed when APAS was used as initiator. Degradative transfer is thought to be mainly responsible for this unusual kinetic behavior for BP–Sty system. The kinetic data proved that BP was more effective and faster initiator than APAS. In both the cases, the mechanism of polymerization was free radical as evident by inhibiting the effect of hydroquinone and ESR studies. IR and NMR spectra showed the atactic nature of polystyrene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1793–1798, 2006     

Soybean plant foliar disease detection using image retrieval approaches

Multimedia Tools and Applications - A research to solve the soybean foliar disease detection problem is proposed through the image retrieval method. We explore the suitability of image retrieval...