Protection from windblown sand is one of the key engineering issues for construction and maintenance of human infrastructures in arid environments. In the last decades, a number of barrier-type Sand ...Mitigation Measures with different shapes have been proposed in order to overcome this problem. Sand barriers are often deployed alongside long line-like infrastructures crossing vast desert regions. It follows that highly optimized preliminary design of the barrier cross section is of paramount importance in the perspective of a large-scale production, in order to minimize the construction costs per unit length, and maximize the aerodynamic performances. The present computational study aims to adapt and apply aerodynamic optimization to a windblown sand barrier. The search for the optimum is carried out on Computational Fluid Dynamics simulations, without recourse to surrogate models. Both gradient-based method and genetic algorithm are used, in the light of the features of the goal function previously sampled by extensive sensitivity studies. The approach is applied to two constructive forms of the same barrier having increasing complexity. Results are critically discussed by combining complementary remarks on the optimization convergence, the phenomenological reading of the flow around the optimized barrier, and its design and construction.
•Aerodynamic shape optimization of barriers against windblown sand is developed.•Barrier trapping performances are maximised, and construction costs minimized.•Computational Wind Engineering simulations are carried out to evaluate the goal function.•Sensitivity of the barrier aerodynamics to design parameters is preliminary assessed.•Performances of both gradient-based and genetic algorithm optimizations are discussed.
Binaural synthesis with head tracking is often used in spatial audio systems. The devices used for head tracking must provide data on the orientation of the listener's head. These data need to be ...highly accurate, and they need to be provided as fast and as frequently as possible. Therefore, head-tracking devices need to be equipped with high-quality inertial measurement unit (IMU) sensors. Since IMUs readily include triaxial accelerometers, gyroscopes, and magnetometers, it is crucial that all of these sensors perform well, as the head orientation is calculated from all sensor outputs. This paper discusses the challenges encountered in the process of the performance assessment of IMUs through appropriate measurements. Three distinct hardware platforms were investigated: five IMU sensors either connected to Arduino-based embedded systems or being an integral part of one, five smartphones across a broad range of overall quality with integrated IMUs, and a commercial virtual reality unit that utilizes a headset with integrated IMUs. An innovative measurement method is presented and proposed for comparing the performance of sensors on all three platforms. The results of the measurements performed using the proposed method show that all three investigated platforms are adequate for the acquisition of the data required for calculating the orientation of a device as the input to the binaural synthesis process. Some limitations that have been observed during the measurements, regarding data acquisition and transfer, are discussed.
We provide the first systematic analysis of the ISO/IEC 11770 standard for key management techniques (
2009
,
2009
), which describes a set of key establishment, key agreement, and key transport ...protocols. We analyse the claimed security properties, as well as additional modern requirements on key management protocols, for over 30 protocols and their variants. Our formal, tool-supported analysis of the protocols uncovers several incorrect claims in the standard. We provide concrete suggestions for improving the standard.
Digital documents created to evoke emotional responses are intentionally stored in special affective multimedia databases, along with metadata describing their semantics and emotional content. These ...databases are routinely used in multidisciplinary research on emotion, attention, and related phenomena. Affective dimensions and emotion norms are the most common emotion data models in the field of affective computing, but they are considered separable and not interchangeable. The goal of this study was to determine whether it is possible to statistically infer values of emotionally annotated pictures using the discrete emotion model when the values of the dimensional model are available and vice versa. A positive answer would greatly facilitate stimuli retrieval from affective multimedia databases and the integration of heterogeneous and differently structured affective data sources. In the experiment, we built a statistical model to describe dependencies between discrete and dimensional ratings using the affective picture databases NAPS and NAPS BE with standardized annotations for 1356 and 510 pictures, respectively. Our results show the following: (1) there is a statistically significant correlation between certain pairs of discrete and dimensional emotions in picture stimuli, and (2) robust transformation of picture ratings from the discrete emotion space to well-defined clusters in the dimensional space is possible for some discrete-dimensional emotion pairs. Based on our findings, we conclude that a feasible recommender system for affective dataset retrieval can be developed. The software tool developed for the experiment and the results are freely available for scientific and non-commercial purposes.
This paper introduces a novel approach to the creation and application of confusion matrices for error pattern discovery in spellchecking for the Croatian language. The experimental dataset has been ...derived from a corpus of mistyped words and user corrections collected since 2008 using the Croatian spellchecker available at ispravi.me. The important role of confusion matrices in enhancing the precision of spellcheckers, particularly within the diverse linguistic context of the Croatian language, is investigated. Common causes of spelling errors, emphasizing the challenges posed by diacritic usage, have been identified and analyzed. This research contributes to the advancement of spellchecking technologies and provides a more comprehensive understanding of linguistic details, particularly in languages with diacritic-rich orthographies, like Croatian. The presented user-data-driven approach demonstrates the potential for custom spellchecking solutions, especially considering the ever-changing dynamics of language use in digital communication.
The paper presents a model of scientific approach to problem solving. The model is based on a gradual approach, preparation, resolution, verification and improvement of solutions. Each of the steps ...in the process of solving a problem or task requires thorough consideration and analysis after which the question "satisfied?". The affirmative answer points to the next, while the negative requires further analysis or a return to one of the previous steps. The presented approach can be successfully used to solve problems and tasks in economic systems and in scientific research in general. The presented model confirmed its simplicity and practicality in concrete scientific research.
The Nencki Affective Picture System (NAPS; Marchewka, Żurawski, Jednoróg, & Grabowska,
Behavior Research Methods
, 2014) is a standardized set of 1,356 realistic, high-quality photographs divided ...into five categories (people, faces, animals, objects, and landscapes). NAPS has been primarily standardized along the affective dimensions of valence, arousal, and approach–avoidance, yet the characteristics of discrete emotions expressed by the images have not been investigated thus far. The aim of the present study was to collect normative ratings according to categorical models of emotions. A subset of 510 images from the original NAPS set was selected in order to proportionally cover the whole dimensional affective space. Among these, using three available classification methods, we identified images eliciting distinguishable discrete emotions. We introduce the basic-emotion normative ratings for the Nencki Affective Picture System (NAPS BE), which will allow researchers to control and manipulate stimulus properties specifically for their experimental questions of interest. The NAPS BE system is freely accessible to the scientific community for noncommercial use as supplementary materials to this article.
Worms can be produced using special machines or standard lathes equipped with a whirling thread-cutting device. A blank is placed on the mandrel and tightened using the three-jawed chuck of the ...standard lathe. If the workpiece diameter is excessively large, passage through the driven pulley is not possible, and the workpiece cannot be supported. Therefore, a new tool holder for whirling devices is needed. During the whirling process, vibrations in the form of machine velocity amplitudes were measured. After whirling was complete, roughness values were calculated. Using numerical procedures of Wolfram Mathematica 10, vibration peaks were extracted, from which frequencies and maximum amplitudes were determined. The data were then inputted into Design Expert, and the rotational speed and amount of separated material were optimized. The results of the study showed that the quality of the processed surface did not improve with processing in two passes of the tool. The measured vibration amplitudes on the lathe carrier and thread whirling attachment increased with cutting speed at the same cutting depth, whereas the quality of the machined surface was best at the smallest and largest cutting depths.
Clustering is a very popular machine-learning technique that is often used in data exploration of continuous variables. In general, there are two problems commonly encountered in clustering: (1) the ...selection of the optimal number of clusters, and (2) the undecidability of the affiliation of border data points to neighboring clusters. We address both problems and describe how to solve them in application to affective multimedia databases. In the experiment, we used the unsupervised learning algorithm k-means and the Nencki Affective Picture System (NAPS) dataset, which contains 1356 semantically and emotionally annotated pictures. The optimal number of centroids was estimated, using the empirical elbow and silhouette rules, and validated using the Monte-Carlo simulation approach. Clustering with k = 1–50 centroids is reported, along with dominant picture keywords and descriptive statistical parameters. Affective multimedia databases, such as the NAPS, have been specifically designed for emotion and attention experiments. By estimating the optimal cluster solutions, it was possible to gain deeper insight into affective features of visual stimuli. Finally, a custom software application was developed for study in the Python programming language. The tool uses the scikit-learn library for the implementation of machine-learning algorithms, data exploration and visualization. The tool is freely available for scientific and non-commercial purposes.
This data description introduces a comprehensive knowledge graph (KG) dataset with detailed information about the relevant high-level semantics of visual stimuli used to induce emotional states ...stored in the Nencki Affective Picture System (NAPS) repository. The dataset contains 6808 systematically manually assigned annotations for 1356 NAPS pictures in 5 categories, linked to WordNet synsets and Suggested Upper Merged Ontology (SUMO) concepts presented in a tabular format. Both knowledge databases provide an extensive and supervised taxonomy glossary suitable for describing picture semantics. The annotation glossary consists of 935 WordNet and 513 SUMO entities. A description of the dataset and the specific processes used to collect, process, review, and publish the dataset as open data are also provided. This dataset is unique in that it captures complex objects, scenes, actions, and the overall context of emotional stimuli with knowledge taxonomies at a high level of quality. It provides a valuable resource for a variety of projects investigating emotion, attention, and related phenomena. In addition, researchers can use this dataset to explore the relationship between emotions and high-level semantics or to develop data-retrieval tools to generate personalized stimuli sequences. The dataset is freely available in common formats (Excel and CSV).
PDF
