Characterisation of unbound aggregate materials considering physical and morphological properties

The objective of this paper is to evaluate the factors affecting resilient and permanent deformation behaviour of unbound granular materials, with a focus on the aggregate physical and morphological characteristics. To evaluate the behaviour of base course, repeated load triaxial testing is commonly used to establish the stress-dependent resilient modulus properties of unbound aggregate base and subbase materials. Although resilient modulus of aggregates is a critical input into mechanistic-empirical pavement design methods, the resilient modulus of unbound base material is often estimated from empirical correlations with index properties in the AASHTOWare Pavement ME design procedure for its simplicity. Since actual field stress conditions and resilient modulus stress states are generally quite different from those generated in the empirical test methods, use of an empirical correlation could lead to an unreliable prediction of resilient modulus and permanent deformation. In order to properly assess the stability of an unbound aggregate layer, it is necessary to establish a proper process to understand the factors affecting fundamental and performance-related properties of unbound granular materials. In this study, aggregate samples from four different sources were tested for resilient modulus and Poisson’s ratio measurements using the Precision Unbound Material Analyzer equipment. Morphological or shape properties of aggregate samples were also measured using an image analysis device. The results demonstrate that aggregate physical and morphological properties affect aggregate resilient and permanent deformation. Further, it is suggested that the resilient modulus of the aggregate should not be used as the sole indicator of rutting performance of aggregate base.     

Boron doped titaniumdioxide nanotube arrays: production,characterization and photocatalytic properties

In numerous studies, regularly oriented anatase titanium dioxide nanotube arrays (TNTAs), obtained through electrochemical anodization, have been employed as catalyst surfaces for photocatalytical applications. However, in many practical applications the phocatalytical activities are restricted due to their wide band gaps. This work shows that photocatalytical activity of TNTAs can be improved by a novel approach which provides boron incorporation into TiO₂ structure during anodization process without any further treatment. Anodization was performed in an aqueous solution containing hydrofluoric acid, oxalic acid and sodium fluoroborate (NaBF₄) at room temperature on titanium (Gr2) substrates. The anodized samples were annealed at 480?°C for 2 h in air in order to obtain anatase transformation and intended crystalline structure. As-prepared B-doped TNT structure was characterized by field emission scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, atomic force microscopy and ultraviolet–visible light diffuse absorbance spectroscopy. The photocatalytic kinetics of B-doped TNTAs for the degradation of methylene blue (MB) under visible light irradiation were evaluated in details.     

Construction of an amperometric pyruvate oxidase enzyme electrode for determination of pyruvate and phosphate

In this study an amperometric biosensor based on pyruvate oxidase was developed for the determination of pyruvate and phosphate. For construction of the biosensor pyruvate oxidase was immobilized with gelatin and insolubilized in film by forming cross-linked bonds with glutaraldehyde. The film was fixed on a YSI type dissolved oxygen (DO) probe, covered with a teflon membrane which is high-sensitive for oxygen. The working principle of the biosensor depends on detection of consumed DO concentration related to pyruvate concentration which is used in enzymatic reaction catalyzed by pyruvate oxidase. The biosensor response shows a linearity with pyruvate concentration between 0.0025 and 0.05 μM and also response time of the biosensor is 3 min. In the optimization studies of the biosensor the most suitable enzyme activity was found as 2.5 U/cm² for pyruvate oxidase, and also phosphate buffer (pH 7.0; 50 mM) and 35 °C were established as providing the optimum working conditions. In the characterization studies of the biosensor some parameters such as reproducibility, substrate specificity, operational stability, determination of phosphate, and interference effects of some compounds on the pyruvate determination were investigated. Finally, the concentration of pyruvate was determined by using spectrophotometric method and the results obtained were compared to results obtained by the biosensor.     

Viscoelastic and Processing Effects on the Fiber-Matrix Interphase Strength. Part II. The Effects of Cure Temperature Time and Curing Agent Content

The effects of curing agent content, cure temperature and time on the adhesion strength between carbon fibers (treated with epoxy sizing) and a thermosetting epoxy (Epon 815) are studied using the single fiber fragmentation test procedure. Theoretical equations describing a majority of the phenomena affecting the adhesion process are also reviewed. The possibility of superposition between percent curing agent content, cure temperature and time is illustrated based on the analytical models presented. Experimental data are presented in the form of percent relative frequency histograms for the fiber fragments in a collective fashion. Such presentation of the data allows for interpretation of the skewness in the data population. Optimum curing agent, cure temperature and time values resulting in highest interfacial strength are also determined.     

Goal emulation and planning in perceptual space using learned affordances

In this paper, we show that through self-interaction and self-observation, an anthropomorphic robot equipped with a range camera can learn object affordances and use this knowledge for planning. In the first step of learning, the robot discovers commonalities in its action-effect experiences by discovering effect categories. Once the effect categories are discovered, in the second step, affordance predictors for each behavior are obtained by learning the mapping from the object features to the effect categories. After learning, the robot can make plans to achieve desired goals, emulate end states of demonstrated actions, monitor the plan execution and take corrective actions using the perceptual structures employed or discovered during learning. We argue that the learning system proposed shares crucial elements with the development of infants of 7–10 months age, who explore the environment and learn the dynamics of the objects through goal-free exploration. In addition, we discuss goal emulation and planning in relation to older infants with no symbolic inference capability and non-linguistic animals which utilize object affordances to make action plans.     

Seismic based strengthening of steel and RC telecommunication poles based on fem analysis

This study describes a numerical projection of pre- and post-retrofitted conditions of telecommunication poles subjected to seismic hazards. The absence of explicit guidelines for the rehabilitation of existing poles motivated the investigation of the effectiveness of steel jacketing for the retrofitting of self-supporting steel and reinforced concrete (RC) telecommunication poles. Effects of mast flexibility, variable damping on dynamic response, and significance of period on base shear amplification were investigated. The overall effectiveness of retrofitting against base excitation was assessed for RC and steel poles through the application of modal analyses and response spectrum approach based on a set of strong motion accelerograms recorded during the 1994 Northridge earthquake. Based on a serviceability approach, the analysis of results shows effectiveness of the steel jacketing in increasing load carrying capacity of the poles by enabling stress redistribution.     

Synthesis and characterization of poly(1,3‐thiazol‐2‐yl‐carbomoyl) methyl methacrylate: Its metal complexes and antimicrobial activity studies

Poly(1,3‐thiazol‐2‐yl‐carbomoyl) methyl methacrylate [poly(TCMMA)] is prepared in dimethyl sulfoxide using 2,2′‐azobisisobutyronitrile as an initiator at 60°C. Poly(TCMMA) is characterized by IR and ¹H‐NMR spectroscopic techniques. Cadmium(II), copper(II), and nickel(II) chelates of poly(TCMMA) were synthesized. An elemental analysis of the polychelates suggests a metal/ligand ratio of 1:2. The polychelates are further characterized by IR and magnetic susceptibility measurements. The thermal properties of the polymer and metal chelates are also discussed. The molecular weights of the poly(TCMMA) are determined by the gel permeation chromatography technique. The antimicrobial activities of the polymer and metal chelates are tested against Staphylococcus aureus COWAN I (bacteria), Escherichia coli ATCC 25922 (bacteria), Listeria monocytogenes SCOTTA (bacteria), Bacillus subtilis LMG (bacteria), Enterobacter aeroginosa CCM 2531 (bacteria), Klebsiela pneumania FMCS (bacteria), Candida albicans CCM 314 (Mayo yeast), and Saccharamyces cerevisiae UGA 102 (Mayo yeast). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3244–3251, 2003     

Integrated approach for reorganizing purchasing: Theory and a case analysis on a Turkish company

Gaining strategic advantages require companies to adopt customer satisfaction as a core strategy that constitutes the fundamentals of total quality management and just in time philosophies. Total quality management and just in time have been used for some time in manufacturing; however, this research extends the idea into purchasing by adapting qualitative and quantitative tools to create a methodology that can be used to design purchasing processes. This paper solely presents the supplier selection and performance management system dimensions of the methodology followed by a case study to illustrate application in the purchasing department of a Turkish steel company.     

Steering self-organized robot flocks through externally guided individuals

In this paper, we study how a self-organized mobile robot flock can be steered toward a desired direction through externally guiding some of its members. Specifically, we propose a behavior by extending a previously developed flocking behavior to steer self-organized flocks in both physical and simulated mobile robots. We quantitatively measure the performance of the proposed behavior under different parameter settings using three metrics, namely, (1) the mutual information metric, adopted from Information Theory, to measure the information shared between the individuals during steering, (2) the accuracy metric from directional statistics to measure the angular deviation of the direction of the flock from the desired direction, and (3) the ratio of the largest aggregate to the whole flock and the ratio of informed individuals remaining with the largest aggregate, as a metric of flock cohesion. We conducted a systematic set of experiments using both physical and simulated robots, analyzed the transient and steady-state characteristics of steered flocking, and evaluate the parameter conditions under which a swarm can be successfully steered. We show that the experimental results are qualitatively in accordance with the ones that were predicted in Couzin et al. model (Nature, 433:513–516, 2005) and relate the quantitative differences to the differences between the models.