Excessive speed and poor drivers' perception are the causes of a large number of traffic accidents. Analysis of the influence of geometry in drivers' behavior has been widely performed by different ...researchers. One way to improve road safety is to provide adequate visibility in order to help drivers adopt adequate behaviors. When the budget is not sufficient for expensive traffic solutions, innovative but simple solutions can be implemented. In this study, the experiment was performed to explore how drivers' perception and behavior are influenced by two virtual 3D shapes' projections - a 3D alternative crosswalk pattern and speed bumps consisted of triangular prisms. The results show statistically significant differences between drivers' willingness to reduce vehicle speed as a response to the two types of road markings: the first one with the square shape base (rectangular prism) and the second one with triangular shape base (triangular prism).
Three dimensional virtual modelling of existing objects (buildings or structures) is applicable in various fields of science and practice: architecture, civil engineering, urbanism, geology, ...mechanical engineering, video games and movie industry, medicine, archeology, safety of people and goods, etc. Photogrammetry, as a method of obtaining data of three-dimensional spatial structures based on two-dimensional images, is used, thanks to a number of software packages, for creating 3D models of objects and other spatial structures. This study analyses terrestrial semiautomatic and automatic photogrammetric methods, both presented through process of creating 3D model of an old existing historical building - Barutana (military gun powder warehouse), built in Ottoman empire, located in the fortress of the city of Niš in Serbia. The aim of the paper is comparison of two photogrammetric methods - semiautomatic and automatic in accuracy and efficiency through case study of Barutana.
The combination of straight lines of constructive elements and curved
contours of structural shapes is always challenging in the engineering
practice. The 2nd order surface - elliptic hyperboloid of ...one sheet (ELHY)
provides such combination. Given that in the architectural surroundings,
arts, or other scientific fields ELHY is less common, than the other
representatives of the same family of ruled surfaces, it is worth of
attention and research. Here presented constructive geometry approach
resulted in Auto CAD application for generating 3D wire-frame and
triangulated net model of ELHY surface and some examples of structures -
prototypes of structural shapes, designed by using ELHY fragments.
Remote tracking and recognition of various objects in defined space are complex multidisciplinary problems. Depending on selected scene being investigated (object size and dynamics, time needed for ...data processing and estimation), and on chosen optoelectronic system design, several solutions are available. For the fieldwork, the passive remote detection seems to be the most convenient. Economically reasonable approach with selected non-sophisticated modest equipment is proposed, evaluated and discussed. A numerical experiment is performed with own-developed algorithm in which unreal cases are automatically eliminated during the output vector data evaluation. Gaussian distribution method is implemented here. The average calculated times, resulted from simulation, were shorter than simulated values increased by 3 sigma.
We describe a rather simple optical experiment, which many students can easily carry out, but the theoretical explanation of which requires far-from-simple mathematical analysis and application of ...numerical methods. A thin vertical rod, partially immersed in a liquid-filled transparent cylindrical container, is moved from the centre toward the wall and observed laterally. As it moves, the part seen through the air and the part seen through the water start to separate, so that at a certain distance from the centre the lower part of the rod becomes invisible. We show that this happens at the distance for which the refracted ray that reaches the observer's eye is along the tangent to the surface of a cylinder. We derive the expression for this distance as a function of the index of refraction and ratio d r, where d is the distance of the observer from the surface and r is the radius of the container. The locus of image positions is determined by evaluating the intersections of pairs of close rays from the rod which reach the observer's eye after refraction at the surface of the container.
A modern traffic setting poses complex and high requirements for all its participants, and among them, especially for children. At the age when they act as independent road users, they participate in ...traffic, mainly as pedestrians or cyclists. Without a doubt, the journey of children to and from school is a complex and sensitive issue. Children represent a vulnerable population from the standpoint of traffic safety. How do children view the world? What helps them link with their environment? How do children imagining traffic signs? To address this and other questions, this research examines how children react to different heights of traffic signs. This study highlights the importance of ergonomic principles in choosing the height of traffic signs for children. The main conclusion of this study is that children best perceive a traffic sign at the higher of 1.9 m and for him have the shortest reaction time.
In this paper, an analysis of three Serbian medieval Raška churches highlights the significance of the interaction of regular geometric shapes in the composition of their underlying proportional ...scheme. The complex geometry recognised in the layouts and cross-sections of these monastery churches points to the potential use of a unique triangular proportioning system. This proportional system is derived from the initial geometry of Štambuk’s proportional canon, which employs two circles constrained by an equilateral triangle in a specific setting. As the essence of religious medieval structures is often related to their interior, in this paper 3D “empty space moulds” are created by the parametric modelling of each element of the structure. This research shows how the variation of the two critical points of the church interior, the centres of the dome and of the main apse, along with the key triangles incorporated in the proportional scheme, affect the final 3D structural model.
Kreiranje trodimenzijskih virtualnih modela postojećih objekata primjenjuje se u različitim područjima znanosti i prakse. Ovakvi 3D modeli se koriste u arhitekturi, građevinarstvu, urbanizmu, ...geologiji, strojarstvu, industriji video igara, filmskoj industriji, medicini, arheologiji, za sigurnost ljudi i dobara itd. Fotogrametrija kao metoda dobivanja podataka trodimenzijske prostorne strukture na osnovu dvodimenzijskih fotografija, zahvaljujući mnogobrojnim softverskim paketima koristi se za izradu 3D modela objekata i prostornih struktura. U ovom radu su analizirane zemaljska poluautomatska i automatska metoda fotogrametrije. Obje pomenute metode su u radu predstavljene kroz studiju slučaja izrade 3D modela Barutane iz doba otomanske imperije, koja se nalazi u Niškoj tvrđavi u Srbiji. Cilj rada je da se kroz studiju slučaja izrade virtualnog 3D modela Barutane provede analiza poluautomatske i automatske metode fotogrametrije i usporedi njihova preciznost.
VEHICLE - MOTORCYCLE COLLISION ANALYSIS 3.1 Typical situations of vehicle - motorcycle collision The consequences of a collision between a motorcycle and a vehicle depend on a number of factors; ...among the most important are the type and mass of the vehicle, the road-type, road coordinates and the impact direction, as well as the characteristics of the road and the environment Among motorcycle accidents, the motorcycle-vehicle type are reported as most frequent and severe collisions (Figure 2). To frame the large number of data registered from real-life situations, six types of collisions were defined 2: a) Type 1 collision (90° ± 20°): front vehicle - lateral motorcycle; b) Type 2 collision (180 ° ± 70°): front vehicle - front motorcycle; c) Type 3 collision (90 ° ± 20 °): lateral vehicle - front motorcycle; d) Type 4 collision: corner vehicle - front motorcycle; e) Type 5 collision: rear vehicle - front motorcycle; f) Type 6 collision: front vehicle - rear motorcycle. 3.2 Parameters used in the reconstruction of motorcycle - vehicle collisions Where: Sm - the distance traveled by the motorcyclist until the center of mass reaches the maximum height Spa - the distance traveled by the motorcyclist until the impact with the road Ss - the distance traveled by the motorcyclist on the road, until he reaches the final position The vertical displacement of the motorcyclist, as presented in Figure 3, is characterized by the equation 3: ... 5.IDENTIFICATION OF COLLISION PHASES In case of a vehicle-motorcycle impact, the following phases of the collision can be identified, Figure 18: * Pre-collision phase: the moment before the two vehicles collides. * Impact moment: the first contact between the vehicle and the motorcycle, as the cause of control loss of the driving direction by motorcyclist. * The final position of the vehicles and the motorcyclist: after being projected on the road, from inertia, the motorcyclist is subjected to translation movements on the road until it reaches the final position. 6.RESULTS The software processes a preliminary computation, the input parameter is the speed of the vehicle before the collision, and hence compute the speed variations at the time of separation. Based on the diagram from Figure 20, the following parameters can be extracted: - the vehicle distance traveled before impact: 1.90 m - the motorcycle distance traveled before impact: 2.40 m - the vehicle distance traveled after the impact: 10 m - the motorcycle distance traveled after impact: 14.30 m - the motorcyclist distance traveled before impact: 2.40 m - the motorcyclist distance traveled after impact: 17.40 m 7.CONCLUSION The graphical method applied within the present paper indicates the stages carried out to complete the virtual modeling of a traffic accident, namely an accident between a vehicle and a motorcycle-motorcyclist assembly via Virtual Crash software.
Touchscreen devices have dramatically increased the accessibility and usage of technology, causing escalating usage, especially by very young children. Although the effects of screen time have been ...shown to produce serious (negatively effects on executive functioning, attention problems, school difficulties, sleep and eating disorders, and obesity) and even life-threatening consequences (due to radiation emission), technology can be beneficial if it is carefully used. Child-centered technology is especially designed to be as entertaining and captivating as possible. In order to examine how touchscreen devices, influence the acquisition of some important spatial concepts and provide exciting opportunities for learning new abilities, an experimental research was conducted aimed to determine whether the type of device used (computers or tablets) in the natural kindergarten environment influences young children performances. For the purpose of this work, geometrical symbols on traffic signs were used to test spatial relationships - left/right, and longer/shorter relations. The test was carried out on a sample of 30 pre-school children. The results show significant differences between the two-testing media for identifying the longer vs. shorter relationships in favor of Tablet PC. Based on the results obtained, it can be concluded that the kinesthetic characteristics of tablets, the novelty factor and the opportunity to learn through playing, provide a positive approach to the early childhood education. Besides, the interactive environment created in a kindergarten by using tablets contributes to introduce new teaching methods which are expected to amplify the pedagogical capacity, changing the way of spatial concepts acquisition, as well as, children traffic education take place within.
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