Sr2+–Mg2+-Doped SiAlON Ceramics

In the present work, multi-cation-doped (Sr²⁺–Mg²⁺) SiAlON ceramics were investigated. MgO and SrO were used in 100:0 and 50:50 molar ratios. The mixture was sintered at 1800° and 1830°C for 1 h in a gas pressure-sintering furnace. The results showed that sintered samples were composed of mainly α- and β-SiAlON phases and small amounts of some Sr-containing phases and SiAlON polytypes. According to Rietveld analysis of X-ray diffraction patterns, Mg is incorporated into the α-SiAlON structure. However, the incorporation of Sr is limited.     

Output-associative RVM regression for dimensional and continuous emotion prediction

Many problems in machine learning and computer vision consist of predicting multi-dimensional output vectors given a specific set of input features. In many of these problems, there exist inherent temporal and spatial dependencies between the output vectors, as well as repeating output patterns and input–output associations, that can provide more robust and accurate predictors when modeled properly. With this intrinsic motivation, we propose a novel Output-Associative Relevance Vector Machine (OA-RVM) regression framework that augments the traditional RVM regression by being able to learn non-linear input and output dependencies. Instead of depending solely on the input patterns, OA-RVM models output covariances within a predefined temporal window, thus capturing past, current and future context. As a result, output patterns manifested in the training data are captured within a formal probabilistic framework, and subsequently used during inference. As a proof of concept, we target the highly challenging problem of dimensional and continuous prediction of emotions, and evaluate the proposed framework by focusing on the case of multiple nonverbal cues, namely facial expressions, shoulder movements and audio cues. We demonstrate the advantages of the proposed OA-RVM regression by performing subject-independent evaluation using the SAL database that constitutes naturalistic conversational interactions. The experimental results show that OA-RVM regression outperforms the traditional RVM and SVM regression approaches in terms of accuracy of the prediction (evaluated using the Root Mean Squared Error) and structure of the prediction (evaluated using the correlation coefficient), generating more accurate and robust prediction models.     

Prioritization methodology of dangerous substances for water quality monitoring with scarce data

Monitoring and control of dangerous substances discharged into receiving waters have attracted more attention lately. Since it is not possible to analyze every single substance, a prioritization methodology is needed for the selection of those to be monitored. Existing well-developed models require significant amount of data for reliable outcomes. This paper presents a methodology to prioritize the dangerous substances having adverse effects on freshwaters in Turkey, where data are scarce. Such a methodology will also serve as a solid model for other countries with limited background data. The adopted methodology enabled the elimination of chemicals to generate a candidate list composed of 608 substances among more than 5000 substances. Further screening and prioritization were conducted using different assessment methods (i.e., Total Hazard Value, Total Impact Value, Combined Monitoring-based, and Modelling-based Priority Setting) to obtain a proposed Final Candidate Specific Pollutants List of 150 dangerous substances. The proposed Candidate National Pollutant List of Turkey was established by combining 45 priority pollutants of the European Union with a list of candidate specific pollutants. According to the outcomes of this study, monitoring and controlling of 195 dangerous substances in freshwaters are recommended. Further detailed studies should be conducted in order to observe the actual levels of these dangerous substances in freshwaters followed by a review of the monitoring list accordingly. Moreover, further revisions might be required in the proposed list due to some possible versatile conditions in terms of sampling points (i.e., change in the location of industries).     

Effect of Deep Cryogenic Treatment on Wear Resistance of AISI 52100 Bearing Steel

In this study, the effects of deep cryogenic treatment (DCT) on the wear resistance of AISI 52100 bearing steel were investigated. For this purpose, a number of bearing steel samples were held for different times (12, 24, 36, 48, 60 h) at deep cryogenic temperatures (?145 °C). The wear experiments were carried out in a ball–disk arrangement, by applying loads of 10 and 20 N and a sliding velocity of 0.15 m/s. After conducting the experimental studies, 36 h was found to be the optimal holding time. At this holding time, the wear rate and friction coefficient were decreased, while the hardness reached to maximum values. It was observed that DCT led to significant microstructural changes, which resulted in improved tribological properties.     

Relative brittleness characterization of some selected granitic building stones: Influence of mineral grain size

Being crystalline materials, brittleness may be an important issue for granitic rocks, especially when they are subject to certain loading conditions. Therefore, in practice, more specifically in their usage as a natural building stone, there is a need for their brittleness characterization. This paper reports a study carried out on some selected granitic rock types in order to determine their relative brittleness index values and relate it to their mineral grain size. For this purpose, three different types of granitic rocks similar in mineral composition, but diverse in grain sizes were selected for the execution of the study. The relative brittleness index values of the studied rock types were determined from the size effect method by using the point load test apparatus. Based on the results of this investigation it is was concluded that, rather than the proportions of the rock forming minerals such as quartz and feldspars, the grain size of feldspars could be the dominant parameter affecting relative brittleness values of the tested rocks.     

The effect of post surface silanization and luting agents on the push-out bond strengths of adhesively inserted fiber reinforced posts

The effect of silane treatment on the push-out bond strengths of three different luting agents to fiber-reinforced composite (FRC) posts after thermocycling was evaluated.Sixty single-rooted human maxillary central incisors were sectioned below the cemento-enamel junction, and the roots were endodontically treated. RelyX Fiber Posts (size #2) were inserted using etch-and-rinse, self-etch, and self-adhesive luting agents (cementing agents). For half of the specimen in each group, the fiber posts were treated with a silane coupling agent. Bonded specimens were cut (2-mm-thick sections) and push-out tests were performed (crosshead speed, 0.5 mm/min). Failure modes were evaluated using a stereomicroscope at original magnification ×40.For each luting agent the use of silane did not result in any statistically significant difference at any level of the root compared to those of the control groups except for Variolink II and RelyX Unicem luting agents in apical root section (p<0.05; one-way ANOVA). The post hoc analysis showed that regardless of the pre-treatment procedures, Variolink II achieved significantly higher bond strengths than Panavia F 2.0 and RelyX Unicem in all root sections (p<0.05).The use of a silane coupling agent had no influence on bond strengths depending on the luting agent used, whereas the type of luting agent (etch-and-rinse, self-etch, and self-adhesive) appeared to be a significant influence on the push-out bond strength values independent of the pre-treatment used. Therefore, pre-treatment of fiber posts with a silane coupling agent does not seem to be mandatory, which saves time in the clinical situation.     

Realisation of current-mode low pass filters using CFCCIIs

A synthesis procedure for generating current-mode low pass filters using a pair of four terminal p-type active current conveyors (CFCCII _p) is presented, and a circuit that realises nth-order low pass current transfer function is given     

Empirical Correlations for Estimating Filtrate Volume of Water Based Drilling Fluids

Standard American Petroleum Institute (API) filter press is generally used for identifying the filtrate volume of drilling fluids and works only at very low pressures. In fact, during a drilling operation, at downhole conditions, the pressures encountered are significantly higher than what is used during standard API filter press tests. A relationship between the well-known fluid properties and the filtrate volume test is developed. In this study, experiments have been conducted for different water-clay mixtures with varying concentrations at different pressure values by using standard API filter press and HP&HT (high-pressure high-temperature) filter press. The relationship between physical and chemical properties of water-clay mixtures and filtrate volume is analyzed. An empirical correlation has been developed for estimating filtrate volume using basic information of the mud (i.e., rotational viscometer readings, density, pressure, cation exchange capacity, and chemical composition). The developed correlation can estimate filtrate volume with an error less than 20% for a wide range of pressure values.     

Heat transfer enhancement in a tube using circular cross sectional rings separated from wall

A numerical study was undertaken for investigating the heat transfer enhancement in a tube with the circular cross sectional rings. The rings were inserted near the tube wall. Five different spacings between the rings were considered as p = d/2, p = d, p = 3d/2, p = 2d and p = 3d. Uniform heat flux was applied to the external surface of the tube and air was selected as working fluid. Numerical calculations were performed with FLUENT 6.1.22 code, in the range of Reynolds number 4475–43725. The results obtained from a smooth tube were compared with those from the studies in literature in order to validate the numerical method. Consequently, the variation of Nusselt number, friction factor and overall enhancement ratios for the tube with rings were presented and the best overall enhancement of 18% was achieved for Re = 15,600 for which the spacing between the rings is 3d.