Multiple-model adaptive control for interval plants

Multiple-Model Adaptive Control (MMAC) is usually considered suitable for Interval Plants. This paper proposes a multiple model adaptive controller for first order interval plant with large delays. The number of models to be used is investigated and the controller parameters tuning is studied. The proposed scheme is applied to a numerical example for illustration. Simulation results show the applicability of the method.     

A review: production of activated carbon from agricultural byproducts via conventional and microwave heating

Production of activated carbon (AC) from agricultural byproducts is a research field that has gained increased interest in recent years because of its potential for the disposal of agro‐residues. At the same time, a beneficial byproduct that can be used in a number of environmental applications is produced. This paper surveys the developments in the production processes of AC from agricultural byproducts in the past 7 years from 2005 to 2012 via conventional and microwave heating. Emphasis is placed on the applied methodology and the influences of activating conditions, such as carbonization temperature, retention time, and impregnation ratio. From the review of AC production processes, agricultural wastes produced by a chemical method with microwave heating can be a source of AC with relatively higher surface area than that produced via conventional heating. © 2013 Society of Chemical Industry     

New Approach for Tetrachlorosilane Promoted One-Pot,Condensation Reaction for Tetrahydrobenzo[a]Xanthene-11-Ones with Docking Validation as Aurora Kinase Inhibitor

An efficient synthesis is reported for tetrahydrobenzo[a]xanthene-11-ones through a one-pot catalytic reaction by mixing β-naphthol, demidone and aromatic aldehydes in the presence of a catalytic amount of tetrachlorosilane (TCS) in methylene chloride as solvent at ambient temperature compared with other catalysts derived from silicon. Aurora kinase inhibitors have attracted a great deal of interest as a new class of antimitotic agents and so the molecular docking study was carried out on the synthesized compounds compared with pentacyclic AKI-001 to discover a novel class of Aurora inhibitors based on a tetracyclic xanthene scaffold and understand the orientation and the interaction of each molecule inside the active site of the Aurora A enzyme.     

Enhanced high capacity image steganography using discrete wavelet transform and the Laplacian pyramid

Multimedia Tools and Applications - This paper introduces a high capacity image hiding scheme with enhanced stego image quality. This new hiding scheme utilizes a multiscale Laplacian pyramid of...     

A genetic algorithm approach to the integrated inventory-distribution problem

We introduce a new genetic algorithm (GA) approach for the integrated inventory distribution problem (IIDP). We present the developed genetic representation and use a randomized version of a previously developed construction heuristic to generate the initial random population. We design suitable crossover and mutation operators for the GA improvement phase. The comparison of results shows the significance of the designed GA over the construction heuristic and demonstrates the capability of reaching solutions within 20% of the optimum on sets of randomly generated test problems.     

Synthesis and Mechanical Properties of Fully Dense Ti2SC

Because the layered machinable ternary carbide, Ti₂SC, has a significantly shorter c -lattice parameter—as compared with most of the 50+ other so-called M_n+1AX_n (MAX) phase family (M=early transition metal; A=A group element and X=C or N and n=1–3) to which it belongs—it was postulated that its mechanical properties would be significantly different than the other MAX phases. In this work, fine-grained (FG) and coarse-grained (CG) polycrystalline fully dense Ti₂SC samples were fabricated. Hot pressing Ti₂SC powders, at 1500°C under a stress of ∼45 MPa for 5 h resulted in FG (2–4 μm) samples which and upon further annealing for 20 h at 1600°C resulted in CG (10–20 μm) ones. No peaks other than those associated with Ti₂SC and an impurity anatase phase, with a volume fraction of ∼6 vol% were observed in the XRD patterns and micrographs. The average Vickers hardness in the 2–300 N range is 8±2 GPa with the FG samples being slightly harder. This hardness is the highest of any of the MAX phases characterized to date. Also in contrast to all MAX phases, cracks extended from the corners of Vickers indents in the FG samples. From these cracks the fracture toughness was estimated and found to increase more or less linearly with load from ≈4 to 6 MPa·m^1/2 as the Vickers force was increased from 50 to 300 N, respectively. The room temperature compressive stress of the FG samples was 1.4±0.2 GPa; the failure mode was brittle. Its Young's modulus—also one of the highest for a M₂AX phase measured to date—was 316±2 GPa. There was no evidence for incipient kink band formation during simple compression. The latter is attributed, in part, to the fine grain size of the hot-pressed material.     

H infintity control of large-scale jump linear systems via averaging and aggregation

This paper studies, under state feedback policies, the H infinity control design for large-scale jump linear systems where the form process admits strong and weak interactions. Through an analysis that covers both finite and infinite horizon cases and using averaging and aggregation techniques, an aggregate jump linear system of considerably smaller order has been obtained, along with a corresponding (compatible) cost function. This reduced-order (aggregate) problem is another piecewise-deterministic H infinity control problem, and, on the basis of the solution of this problem, we obtain the asymptotic limit of the optimal performance level for the full-order system, as well as an approximate controller that can asymptotically achieve any desired performance level for the full-order system. A by-product of this analysis is a similar decomposition for the piecewise-deterministic linear-regulator problem.     

Instrumented indentation and scratch testing evaluation of tribological properties of tin-based bearing materials

This paper describes a study of some fundamental tribological behavior of two different tin-based bearing materials using scratch and Martens hardness techniques. The scratch test results obtained from the two different tin-based bearing materials were correlated with a function of scratch hardness and coefficient of friction. It is easily observed that the friction coefficients of WM5 are lower than those of WM2 under all scratch test conditions. Beside this, it is clearly distinguished that both materials give higher friction coefficients at higher normal loads and scratch velocities. Also it is found that scratch hardness values of the WM5 materials are higher than WM2 generally. Moreover, optical microscopy was used to determine the scratch hardness of two different tin-based bearing materials by examining the scratch widths. Scanning electron microscopic observations of two different tin-based bearing materials were performed in order to identify the scratch-deformation mechanisms and trace morphology. Beside scratch tests, Martens hardness tests were carried out to evaluate the indentation of materials by considering both the force and displacement during plastic and elastic deformation. By monitoring the complete cycle of increasing and removal of the test force, hardness values were determined.     

锻造和热处理对Al-Si和Al-Pb轴承合金在油润滑条件下耐磨性的影响

研究了锻造态和热处理态不同成分铝基轴承合金在油润滑条件下的摩擦行为，以及材料的硬度、热处理制度和锻造对材料耐磨性的影响。所用材料是 Al-8.5Si-3.5Cu 和 Al-15Pb-3.7Cu-1.5Si-1.1Fe。在锻造过程中，应变范围为10%~20%。并对材料进行T6热处理。在销-盘式磨损试验机上对材料的摩擦性能进行测试。结果表明，锻造过程使材料的硬度得到增加；铸造应变在10%~20%的范围内对材料的摩擦磨损影响不明显。     

Main-chain polybenzoxazine nanofibers via electrospinning

Here we report the successful production of nanofibers from main-chain polybenzoxazines (MCPBz) via electrospinning without using any other carrier polymer matrix. Two different types of MCPBz (PBA-ad6 and PBA-ad12) were synthesized by using two types of difunctional amine (1,6-diaminohexane and 1,12-diaminododecane), bisphenol-A, and paraformaldehyde as starting materials through a Mannich reaction. ¹H NMR and FTIR spectroscopy studies have confirmed the chemical structures of the two MCPBz. We were able to obtain highly concentrated homogeneous solutions of the two MCPBz in chloroform/N,N-dimethylformamide (DMF) (4:1, v/v) solvent system. The electrospinning conditions were optimized in order to produce bead-free, uniform and continuous nanofibers from these two MCPBz by varying the concentrations of PBA-ad6 (30–45%, w/v) and PBA-ad12 (15–20%, w/v) in chloroform/DMF (4:1, v/v). The bead-free fiber morphology was evidenced under SEM imaging when PBA-ad6 and PBA-ad12 were electrospun at solution concentration of 40% and 18% (w/v), respectively. The nanofibrous mats of MCPBz were obtained as free-standing material, yet, PBA-ad12 mat was more flexible than and PBA-ad6 mat. Furthermore, the curing studies of these MCPBz nanofibrous mats were performed to obtain cross-linked materials.