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The unknown current distribution (UCD), line leakage current density (LLCD) and other integral characteristics of a linear grounding structure (GS), shaped either as an arbitrary linear star (LS) or polygon (LP), are presented in this paper. The UCD of the GS is determined by numerical solving of system of integral equations of two‐potential (SIE‐TP). The GS is placed in homogeneous and isotropic earth and its integral characteristics are analysed in the power frequency domain.

Seeds and nuts include many dietary minerals as well as trace metals. It is very important to determine the nutritional mineral values in seeds and nuts. Many minerals can be analyzed simultaneously in low concentrations by using inductively coupled plasma-atomic emission spectroscopy. This paper aims to evaluate nutritional values of dietary and trace minerals in selected seeds and nuts.

Dietary minerals in the sunflower seed (Helianthus annuus), pumpkin seed (Cucurbita pepo L.), peanut (Arachis hypogaea) and corn (Zea mays L.) samples collected from the markets in Sakarya city of Turkey have been analyzed. Two digestion procedures were applied by using hydrochloric acid solution and the mixture of nitric acid and hydrogen peroxide solution.

In the evaluation of the mineral contributions of the nuts, the micro-mineral contributions (Cu, Fe, Zn, Mn and Se) were found at higher values than the macro-minerals (Ca, Mg, K and Na). Potassium was determined as the most abundant mineral, and sodium was found at lower levels. The results showed that nuts are trace mineral suppliers and possible Na-K regulator foods in human nutrition.

The obtained results for the mineral profile and daily intake values provide useful information that could sensitize the people on the consumption of seeds and nuts.

Findings from the digestion procedures and the assessments based on the recommended daily intakes have got valuable impact.

The purpose of this paper is to estimate influence of the pillar concrete foundation approximated by a semiconducting semi‐sphere on the pillar grounding system.

Unknown current distributions and impedance of pillar grounding system, which consists of a ferro armature modelled as a single electrode inside concrete foundation, ring electrode and two earthing conductors, are determined in this paper. Concrete foundation is approximated by a semi‐spherical semiconducting inhomogeneity. The expressions for electric scalar potential are formed using the quasi‐stationary image theory, including a recently proposed Green's function for the point source in the presence of a semiconducting sphere. Based on the quasi‐stationary antenna model, unknown currents are determined solving the system of integral equations using the moment method and polynomial approximation for current distributions.

The influence of inhomogeneity is not negligible for real values of specific conductivity of the inhomogeneity domain. The same goes for earthing conductor influence, especially the one on electric scalar potential distribution on the ground surface.

Besides the analyzed system, the model is applicable for solving for example a grounding system in the vicinity of large holes in the ground (pond and small lake) filled with water, treated as semi‐sphere or near vertical container (silage and reservoir) having semi‐spherical basis with a lower one buried in the ground.

Obtained results give possibility to analyze influence of semiconducting ground inhomogenities, which can be treated as semi‐spherically shaped ones, on grounding system. It results in better accordance of projected and real grounding system's characteristics.

The recent rise in online knowledge repositories and use of formalism for structuring knowledge, such as ontologies, has provided necessary conditions for the emergence of tools for generating knowledge assessment. These tools can be used in a context of interactive computer-assisted assessment (CAA) to provide a cost-effective solution for prompt feedback and increased learner’s engagement. The purpose of this paper is to describe and evaluate a tool developed by the authors, which generates test questions from an arbitrary domain ontology, based on sound pedagogical principles encapsulated in Bloom’s taxonomy.

This paper uses design science as a framework for presenting the research. A total of 5,230 questions were generated from 90 different ontologies and 81 randomly selected questions were evaluated by 8 CAA experts. Data were analysed using descriptive statistics and Kruskal–Wallis test for non-parametric analysis of variance.

In total, 69 per cent of generated questions were found to be useable for tests and 33 per cent to be of medium to high difficulty. Significant differences in quality of generated questions were found across different ontologies, strategies for generating distractors and Bloom’s question levels: the questions testing application of knowledge and the questions using semantic strategies were perceived to be of the highest quality.

The paper extends the current work in the area of automated test generation in three important directions: it introduces an open-source, web-based tool available to other researchers for experimentation purposes; it recommends practical guidelines for development of similar tools; and it proposes a set of criteria and standard format for future evaluation of similar systems.

The purpose of this paper is to model multilayer structure surface acoustic wave (SAW) sensors, incorporated in CMOS or micro‐electro‐mechanical system integrated circuits, and to derive the corresponding wave velocity as an analytic expression in terms of the layers‘ thickness and density, which is suitable for analysis and design.

The method is based on an electro‐mechanical equivalent model of multilayer structure SAW sensors. A multilayered SAW device is represented by a two‐port electrical equivalent circuit consisting of three parts: input transducer, output transducer, and between them the delay line, which is the sensing part. The sensing part is modelled as a mechanical two‐port network. The wave velocity is calculated using analogy between the mechanical and electrical quantities and the fact that the wave motion of the SAW extends below the surface to a depth of about one wavelength.

The presented model predicts very efficiently and accurately the velocity of SAW sensors with multilayer substrates in the case where the thicknesses of upper layers are much smaller than the signal wavelength. The velocity can be calculated from the formula, so that elaborate numerical computations involving partial differential equations are avoided.

The model and the velocity calculation can be applied only to acoustically thin upper and middle layers where acoustically thin means that a layer is sufficiently thin and rigid (large shear modulus). The presented results provide a starting‐point for further research in the analysis and design of sensors fabricated using AlGaN, GaN, AlN/diamond.

Since the majority of SAW sensors is designed with acoustically thin layers, the proposed model and calculation can be of interest for many practical material combinations. The presented model and calculation can be used in most cases of the optimal sensor design with respect to the sensor sensitivity or required area on the sensor chip.

The paper presents a new original model of multilayer structure SAW sensors and a new method of SAW velocity calculation. The method gives good results, with much simpler calculations than in the wave equation method, in cases where certain layers are acoustically thin.