Learning from abstract and contextualized representations: The effect of verbal guidance

An experiment examined the effects of providing explicit verbal guidance to learners in integrating information with abstract or contextualized representations during computer-based learning of engineering. Verbal guidance supported learners in identifying correspondences and making mental connections among multiple textual and diagrammatic representations. Results from a 2 (abstract (A) or contextualized (C) representation) × 2 (no guidance or guidance) design showed that without guidance, abstract representations led to better transfer than contextualized representations. Moreover, learners in the contextualized representation group benefitted from the guidance, while the abstract representation group did not benefit from guidance. These findings suggest that abstract representations promote the development of deep, transferrable knowledge and that verbal guidance denoting correspondences among representations can facilitate learning when less effective representational formats are utilized.     

Measuring water utility performance using nonparametric linear programming

In this study, a cutting-edge methodology for measuring the performance of water utilities based on two-stage Data Envelopment Analysis (DEA) was applied to individual districts of a California-based water utility. A bootstrap technique involving the construction of confidence intervals was implemented to overcome the deterministic nature of conventional DEA, and a number of exogenous variables were incorporated into the model to help identify the factors affecting technical efficiency. Results indicated high overall performance achieved by the utility on average (92%). The number of connections and precipitation were found to be statistically significant exogenous variables, and both were determined to have a negative impact on efficiencies. The findings of this study are expected to be useful for guiding subsequent managerial improvement initiatives.     

Some physical properties of copper oxide films: The effect of substrate temperature

In this work, copper oxide films were deposited at different substrate temperatures of 200, 250, 300 and 350 ± 5 °C by ultrasonic spray pyrolysis technique and the effect of substrate temperature on the structural, surface, optical and electrical properties of the films was presented. The film structures were studied by X-ray diffraction (XRD). To obtain information about structural properties in detail, the grain size (D), dislocation density (δ) and lattice parameters (a = b = c for cubic structure) for preferential orientations were calculated. The surface properties and elemental analyses were characterised using scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. Optical properties of the films were analyzed by transmission, linear absorption coefficient and reflection spectra, and the optical method was used to determine the band gaps of the films. The current–voltage values were measured with two-probe technique, and the electrical conductivities were calculated. Consequently, it was determined that substrate temperature has a strong effect on the structural, surface, optical and electrical properties of copper oxide films.     

Mask spoofing in face recognition and countermeasures

In this paper, initially, the impact of mask spoofing on face recognition is analyzed. For this purpose, one baseline technique is selected for both 2D and 3D face recognition. Next, novel countermeasures, which are based on the analysis of different shape, texture and reflectance characteristics of real faces and mask faces, are proposed to detect mask spoofing. In this paper, countermeasures are developed using both 2D data (texture images) and 3D data (3D scans) available in the mask database. The results show that each of the proposed countermeasures is successful in detecting mask spoofing, and the fusion of these countermeasures further improves the results compared to using a single countermeasure. Since there is no publicly available mask database, studies on mask spoofing are limited. This paper provides significant results by proposing novel countermeasures to protect face recognition systems against mask spoofing.     

Algae as a promising resource for biofuel industry: facts and challenges

Energy is the main driving force of society today that should be handled as a whole starting from production to consumption. With the rapid increase in the energy necessity, alternative methods and sources are becoming a crucial topic that should be scientifically highlighted with all their pros and cons. Especially the problems related to the fossil sources of energy triggered the search on the renewable alternatives like algae. In order to reach the desired amounts of energy with the satisfactory quality and quantity, understanding the algae as a living thing with the biological mechanism and existing production technologies are the key points to have a projection for commercialization. In this regard, technical facts and challenges on algal biofuel production should be evaluated. Keeping in mind the specifications and possible advantages related to their taxonomy, algae can serve as a promising source to reduce fossil fuel consumption. With the progress in the modern technology, reaching an effective production process will be possible, and this will help the algal biofuels to prove their maturity as a sustainable source for future. Within this context, the aim of this review is to point out the crucial technical challenges about algal fuels comprising both the macroalgae and microalgae as a reliable source of renewable energy. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of palladium loaded activated carbons on hydrogen storage

Pd-loaded high surface area activated carbon (BAC-Pd) was produced from bamboo by carbonization and activation using potassium hydroxide with subsequent loading of palladium. The palladium loaded onto BACs appears to exist more in micropores. The Pd compounds exist mainly as amorphous PdCl₂ with Pd (0) structures in the whole surface of BAC-Pd. The hydrogen adsorption capability of BAC-Pd at 0.1?MPa and room temperature was evaluated for hydrogen storage. The amount of adsorbed hydrogen on BAC-Pd was the maximum among three Pd-loaded activated carbons because the physical properties and the Pd content are the highest among them. According to the effect of Pd content, the amounts of adsorbed hydrogen on BAC-Pd increased linearly as the Pd content increased, and the BET surface area of BAC-Pd decreased. BAC, which had the highest Pd contents in micropores, exhibited excellent adsorption ability for hydrogen at 298?K and 0.1?MPa. The amounts of chemisorbed hydrogen of BAC-Pd increased along with the increase in Pd content. Furthermore, the amount of adsorbed hydrogen of BAC-Pd is expected to increase in conditions with pressure higher than 0.1?MPa.