Prediction of interfacial crack path: a direct boundary integral approach and experimental study

This paper presents the development of a higher-order direct boundary integral-displacement discontinuity method for crack propagation in layered elastic materials. The method is based on the dual boundary integral equations of linear elasticity which are solved by means of a quadratic boundary element formulation. The analytical solution for a point force within a bonded half-plane region is used to derive the kernel functions of the boundary integral equations. Square-root displacement-discontinuity elements are used to model the crack tips, and stress intensity factors may be computed using the numerically predicted values of the displacement discontinuity components at the midpoints of these crack-tip elements. An algorithm based on the maximum tensile-stress criterion is then developed and incorporated into the boundary element model to predict the paths of cracks propagating in layered elastic materials.In the experimental part of this study, crack profiles for straight-through-cracked, compact-tension specimens of the anodically bonded silicon/Pyrex glass system are measured by profilometry. The plane strain prediction of the crack-propagation path is compared with the experimentally measured crack profiles. Consistent with the prediction, the interfacial crack is observed to kink away from the strong, anodically-bonded interface and propagate into the more compliant glass layer. The predicted initial kink angle of 26° agrees very well with the average measured value of 28°. The measured path of the crack is also in very good agreement with the predicted path over about the first 120 microns of crack growth with increasing deviation observed beyond that.     

Advanced oxidation of commercial textile biocides in aqueous solution: effects on acute toxicity and biomass inhibition.

In the present study, the decomposition of two biocides used in the textile finishing process with Advanced Oxidation Processes (AOPs) has been studied. Different AOPs, i.e O3/OH-, TiO2/UV-A and Fe2+/H2O2 have been used representing mutually combined components of the chemically and photochemically driven advanced oxidation systems. The course of reaction was examined by changes in chemical oxygen demand (COD), total organic carbon (TOC) and acute toxicity towards the water flea Daphnia magna (assessed in terms of the effective dilution ratio LD50). Particular attention has been paid to determine the inhibitory effect of raw and ozonated biocides on biological activated sludge consortium at concentrations typically encountered in textile finishing effluents. Significant oxidation and mineralization of both biocides could be achieved employing ozonation at pH = 11.5 and heterogeneous photocatalysis (TiO2/UV-A) at pH = 5.0, whereas Fenton's reagent appeared to be less effective in COD and acute toxicity abatement.     

Functionalization of cotton fabric with nanosized TiO<Subscript>2</Subscript> coating for self-cleaning and antibacterial property enhancement

In this study, titanium dioxide (TiO₂) was used as coating compound to add self-cleaning and antibacterial functionality properties to the cotton fabric. TiO₂-consisting coating compounds were prepared at four different processing temperatures (20, 40, 60, and 80°C) in order to examine the influence of process temperature on average particle size. Among the prepared solutions, the one prepared at 80°C process temperature was selected for the dip coating application of the 100% cotton fabric, which formed a transparent nanosized TiO₂ film on the fibrous structure of fabric. Dip coating trials were done at five coating temperatures of 20, 40, 60, 80, and 100°C. TiO₂-coated and uncoated fabric samples were then tested to evaluate their self-cleaning and antibacterial activities. A self-cleaning activity test was conducted using uncoated and TiO₂-coated fabric samples which were stained with hot tea solution via dipping method. Stained fabric samples were illuminated under a solar simulator for the color changes to measure photocatalytic degradation of stain colors. Antibacterial performance of TiO₂-coated and uncoated fabric samples was determined against pure cultures of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213.     

Estimation of bearing capacity of basalts at the Atasu dam site,Turkey

This paper describes the results of the engineering geological investigations and bearing capacity studies carried out at the proposed site of the rock fill Atasu Dam, to be constructed on basalts and pyroclastics. Rock mass strength and modulus of elasticity of the rock mass were determined using the Hoek–Brown empirical strength criterion. Rock mass classifications for the dam rock foundation were undertaken following the RMR, Q and GSI systems and the stress distributions using the finite element technique. To estimate the bearing capacity of the basalts, different empirical equations were used and compared.      

Online video scene clustering by competitive incremental NMF

Efficient clustering and categorizing of video are becoming more and more vital in various applications including video summarization, content-based representation and so on. The large volume of video data is the biggest challenge that this task presents, for most the clustering techniques suffer from high dimensional data in terms of both accuracy and efficiency. In addition to this, most video applications require online processing; therefore, clustering should also be done online for such tasks. This paper presents an online video scene clustering/segmentation method that is based on incremental nonnegative matrix factorization (INMF), which has been shown to be a powerful content representation tool for high dimensional data. The proposed algorithm (Comp-INMF) enables online representation of video content and increases efficiency significantly by integrating a competitive learning scheme into INMF. It brings a systematic solution to the issue of rank selection in nonnegative matrix factorization, which is equivalent to specifying the number of clusters. The clustering performance is evaluated by tests on TRECVID video sequences, and a performance comparison to baseline methods including Adaptive Resonance Theory (ART) is provided in order to demonstrate the efficiency and efficacy of the proposed video clustering scheme. Clustering performance reported in terms of recall, precision and F1 measures shows that the labeling accuracy of the algorithm is notable, especially at edit effect regions that constitute a challenging point in video analysis.     

Formation of black glass to be used in solar collectors as absorbent and CuO and Fe2O3's effect on this glass

Solar energy has the highest potential among novel and renewable energies. In order for solar energy to be used it should first be collected. In this study, a black glass was formed by doping silicate glass with Co₃O₄ at a high concentration to be used as absorbent, and in addition, this black glass was also doped with CuO and Fe₂O₃. Optical absorptions, electrical conductivities, thermal diffusion coefficients, SEM images and EDX spectra of all glasses were obtained and effects of transition metal oxides on glass were examined.     

Cluster based wireless sensor network routing using artificial bee colony algorithm

Due to recent advances in wireless communication technologies, there has been a rapid growth in wireless sensor networks research during the past few decades. Many novel architectures, protocols, algorithms, and applications have been proposed and implemented. The efficiency of these networks is highly dependent on routing protocols directly affecting the network life-time. Clustering is one of the most popular techniques preferred in routing operations. In this paper, a novel energy efficient clustering mechanism, based on artificial bee colony algorithm, is presented to prolong the network life-time. Artificial bee colony algorithm, simulating the intelligent foraging behavior of honey bee swarms, has been successfully used in clustering techniques. The performance of the proposed approach is compared with protocols based on LEACH and particle swarm optimization, which are studied in several routing applications. The results of the experiments show that the artificial bee colony algorithm based clustering can successfully be applied to WSN routing protocols.     

Effect of a chemical synthesis‐based pharmaceutical wastewater on performance,acetoclastic methanogenic activity and microbial population in an upflow anaerobic filter

The performance of an upflow anaerobic filter (UAF) treating a chemical synthesis‐based pharmaceutical wastewater was evaluated under various operating conditions. During start‐up, the UAF was initially fed by glucose till an organic loading rate (OLR) of approximately 7.5 kg COD m^?3 day^?1 with a hydraulic retention time of 2.3 days. A soluble COD removal efficiency of 98% was achieved before the addition of the wastewater. Initially, the filter inertia was acclimatized to the wastewater by sequential feeding of 10% (w/v), 30% (w/v) and 70% (w/v) of the pre‐aerated wastewater mixed with glucose followed by a 100% (w/v) pre‐aerated wastewater. During the operation, the COD removal efficiency and methane yield decreased to 75% and 0.30 m³ CH₄ kg^?1 COD_removed respectively. As the UAF became accustomed to the pre‐aerated wastewater, raw wastewater was fed in increasing ratios of 20% (w/v), 60% (w/v) and 80% (w/v) with the pre‐aerated wastewater as the remaining part. During this stage of the operation, a COD removal efficiency in a range of 77–86% was achieved and the methane yield decreased to 0.24 m³ CH₄ kg^?1 COD_removed. Finally, 100% (w/v) raw wastewater was fed and a COD removal efficiency of 65% was achieved with a methane yield of 0.20 m³ CH₄ kg^?1 COD_removed. At the end of the operation, acetoclastic methanogenic activity was only measured in the bottom section of the UAF, this showed a 90% reduction in comparison with activity of inoculation sludge. Microscopic examinations revealed that rod‐shaped methanogens remained as the dominant species whereas Methanosarcina‐like species and filaments were present only in insignificant numbers along the UAF. © 2002 Society of Chemical Industry     

A Neurogenetic approach for the resource-constrained project scheduling problem

A variety of metaheuristic approaches have emerged in recent years for solving the resource-constrained project scheduling problem (RCPSP), a well-known NP-hard problem in scheduling. In this paper, we propose a Neurogenetic approach which is a hybrid of genetic algorithms (GA) and neural-network (NN) approaches. In this hybrid approach the search process relies on GA iterations for global search and on NN iterations for local search. The GA and NN search iterations are interleaved in a manner that allows NN to pick the best solution thus far from the GA pool and perform an intensification search in the solution's local neighborhood. Similarly, good solutions obtained by NN search are included in the GA population for further search using the GA iterations. Although both GA and NN approaches, independently give good solutions, we found that the hybrid approach gives better solutions than either approach independently for the same number of shared iterations. We demonstrate the effectiveness of this approach empirically on the standard benchmark problems of size J30, J60, J90 and J120 from PSPLIB.     

Structuring ship design project approval mechanism towards installation of operator-system interfaces via fuzzy axiomatic design principles

Managing the verification of primary design projects for ship machinery systems is one of the crucial stages in ship building processes. In particular, the design of operator-system interfaces such as remote controls, displays, alarms, workstations, and labels requires a high level of technical expertise and systematic control. This paper focuses on structuring a ship design project approval mechanism (SDPAM) based on fuzzy axiomatic design (FAD) methodology which is concerned with the system design of relevant interfaces on an engine room control console. Design characteristics such as accessibility and operational requirements are treated as “hard” constraints being encountered in this complex problem. Hence, the proposed methodology requires performance assessment using fuzzy values. This study provides original contributions to the existing approval procedures of classification societies, which are non-governmental construction and classification organizations in the shipping industry. Furthermore, the study proposes a new approach to handle uncertainty and vagueness by an axiomatic design extension to ship project execution problems.