1.  Narayan, J. P. and Kamal: Quantification of effects of geometry of sediment bedrock interface on ground motion in 3D basin with circular free surface.

This paper presents the effects of geometry of sediment bedrock interface (GSBI) of 3D basins with a circular outcropping free surface on the characteristics and the focusing of the basin-generated surface (BGS) waves and associated spatial variations of the average spectral amplification (ASA) and average aggravation factor (AAF). An increase of ASA towards the centre of the semi-spherical (SS-) basin as compared to the 2D basin revealed the focusing of the BGS-waves in the SS-basin. The obtained 2.8 times larger ASA at the centre of the SS-basin to that of 2D basin calls for a special attention in predicting the seismic hazard in such basins for earthquake engineering purposes. The analysis of the simulated results revealed that the amplitude amplification due to the focusing of the BGS-waves was highly affected by the GSBI. For example, the ASA at the centre of a trapezoidal basin with edge slope 200 was 50% larger than that at the centre of a trapezoidal basin with edge slope 450. It is recommended to compute the AAF using the same components of ground motion as that of the incident wave to conservatively aggravate the ground motion to incorporate the 3D basin-effects in the seismic microzonation where it is over based on the 1D response of sediment column.

Keywords: 3D viscoelastic finite-difference simulation, basin-generated surface waves, focusing of surface waves, aggravation factors and average spectral amplifications


2.  Pektaş, A. O. and E. Doğan: Prediction of bed load via suspended sediment load using soft computing methods.

Appropriate and acceptable prediction of bed load being carried by streams is vitally important for water resources quantity and quality studies. Although measuring the rate of bed load in situ is the most consistent method, it is very expensive and cannot be conducted for as many streams as the measurement of suspended sediment load. Therefore, in this study the role of suspended load on bedload prediction was examined by using sensitivity analysis. On the other hand, conventional sediment rating curves and equations can not predict sediment load accurately so recently the usage of machine learning algorithms increase rapidly. Accordingly, soft computational methods are used in the study. These are; artificial neural network (ANN), support vector machine (SVM) models and a decision tree (CHAID) model that is not used before in sediment studies. Some particular parameters are frequently used in these soft computational methods to form input sets. Hence, well known and commonly used three input sets and a new generated set are used as inputs to predict bedload and then the suspended load variable is added in these input sets. The performances of models with respect to input sets are compared to each other. To generate the results and to push the limits of models a very skewed and heterogeneous data is collected from distributed locations. The results indicate that the performance of ANN and CHAID tree models are good when compared to SVM models. The usage of a suspended load as an additional input for the models boosts the model performances and the suspended load has significant contributions to all models.

Keywords: sediment prediction, bed load, suspended load, artificial neural networks, support vector machines, CHAID tree models


3.  Belušić, A., I. Herceg-Bulić and Z. B. Klaić: Using a generalized additive model to quantify the influence of local meteorology on air quality in Zagreb.

This paper reports the estimated response of hourly mean concentrations of selected air pollutants, namely carbon monoxide (CO), sulphur dioxide (SO2), nitrogen dioxide (NO2) and particulate matter with an aerodynamic diameter of up to 10 µm (PM10), to local-scale meteorology in Zagreb, Croatia for the period 2006–2012. A new method is applied here for the urban area of Zagreb. In a general model, a logarithm of hourly mean air pollutant concentrations is expressed as the sum of the nonlinear functions of meteorological and several time variables, with the latter included accounting for temporal variation in emissions. The model can be formulated within the framework of generalized additive models (GAMs) and is additive on the logarithmic scale, which results in multiplicative effects on the original scale. Although the model is nonlinear, it is simple and easy to interpret. It quantifies the impact of meteorological conditions and emissions on air pollution. A measure of the relative importance of each predictor, partial effects and statistical evaluation of the model are also presented. Overall, the results show that the most important predictors are those related to emissions. The aggregate impact of meteorological variables in the model explained 45% of variance in CO, 14% in SO2, 25% in NO2 and 24% in PM10. This indicates that meteorology, at least on a local scale, is a noticeable driver of air quality in Zagreb. Stable atmospheric conditions in the urban area favour the occurrence of higher concentrations of air pollutants. Convection processes dominate under unstable conditions, resulting in the dilution of pollutant concentrations within the boundary layer.

Keywords: atmospheric boundary layer, statistical modelling, urban air quality

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4.  Pantavou, K. and A. Mavrakis: Thermal perception of teenagers in a cool outdoor environment: A case study.

Subjective thermal sensation of late teenagers was examined aiming to reveal potential discrepancies in its estimation compared to adults. Since teenagers have different clothing habits and preferences from adults, it is important to know whether the conclusions reached by studies on thermal sensation, usually involving adults, can be also applied to teenagers. A group of late teenagers was interviewed, based on a structured questionnaire, in an outdoor environment during two winter days and under an unexpected Saharan dust transport event during the second day, while meteorological measurements were obtained by the closest to the interview site weather station. Moreover, the performance of the bioclimatic index Cooling Power in simulating subjects' thermal sensation was evaluated. Although differences in clothing thermal insulation of late teenagers compared to that suggested by similar studies were recognized, generally the results of this study were in agreement with the findings of similar field surveys focusing on individual thermal sensation and with no evidence of effects of the dust transport event on thermal sensation. Cooling Power based on the Mediterranean thermal sensation scale predicted thermal sensation vote fairly well.

Keywords: perception, thermal sensation, questionnaire survey, thermal index, cooling power


5.  Orlić, M. and I. Vrkić: Bibliography of papers, reports and books published by Stjepan Mohorovičić.

A bibliography of papers, reports and books authored by Stjepan Mohorovičić is compiled and is presented in this paper. The bibliography contains 440 entries grouped into five categories: scientific papers (89 entries), professional and popular papers (87 entries), data reports (69 entries), literature reports (189 entries), and monographs and books (6 entries). A significant fraction of the papers and reports were published in international journals. The list reveals that Stjepan Mohorovičić was one of the most versatile and productive scientists working in Croatia in the twentieth century, whereas a brief overview of the impact of his publications, also presented in this paper, shows that he was one of the most creative Croatian scientists as well. It is stressed that Stjepan Mohorovičić's output merits an in-depth evaluation and the bibliography is offered as the starting point for such an endeavor.

Keywords: bibliography, Stjepan Mohorovičić