Papers by Keyword: Collision

Abstract: The use of Unmanned Aerial Vehicles (UAVs) is increasing as their usage enhance many activities in our modern world. These include their specific roles in warfare, surveillance, agricultural activities, entertainments with attendant economic importance. In areas grappling with insecurity challenges due to banditry, kidnappings, oil spillage and theft, farmers and herdsmen clashes, utilizing more than one UAV in an area for surveillance is not only good but more advantageous. If many UAVs are used in an area at the same time, they are termed swarm or group of UAVs. Their operations in this manner, are seen as more scalable and reliable mode of using UAVs in current and future applications. Thus, usage of multiple UAVs that operate together as a cohesive unit are redundant and scalable, performing tasks that would be challenging or inefficient for a single UAV to accomplish. However, operating a group of UAVs as one unit can become expensive and risky if they are not properly coordinated. The UAVs may collide, causing catastrophic damage and requiring costly repairs. The need for autonomous coordination therefore comes from the vast number of vehicles, which might be intrinsic members of the system as a whole. Also, all UAVs in the swarm are to contribute to the effective execution of task without wasting resources. These imply that an intelligent coordination algorithm that implements awareness for swarm UAVs to avoid risky states is required. This paper presents the development and implementation of an algorithm for intra-swarm collision avoidance by treating each UAV in a swarm unit as individual agent capable of a homogenous number of tasks modelled as contours using their field of view and received signal strength indication.

Abstract: This paper aims to show that the fully differential ionization cross section when an antiproton collision with a hydrogen atom can be directly expressed as a time-dependent wave function. For the projectile, wave function corresponding to the specific scattering angle was converted by two-dimensional Fourier transform from the wave functions of corresponding to impact parameters. This wave function shows how the ejected electron probability density distribution varies with time. We are shown that the calculation of the fully differential cross section of ionization can be directly determined by the local value of the wave function without the need to calculate the spatial integral for calculating the transition amplitude. It has been shown that the direct determination of the fully differential cross section by this time-dependent wave function is in good agreement with the results of determined the traditional method is by the transition amplitude.

Abstract: Dijkstra algorithms are typically used to find the shortest path from a source node to a destination node. It is widely used in various applications due to its reliability and less complexity. This paper presents the extended Dijkstra Algorithm with lower latency and consumes less computing memory intended for implementation in many AGVs networks for effective decentralized task distribution path planning. This paper proposed linear regression normalization across the node network in Dijkstra architecture to reduce computing time and memory consumption. The issue addressed through this optimization focused on reducing the possibilities of collision between AGVs and deadlock. The extended Dijkstra algorithm significantly reduces computing time compared to the traditional Dijkstra algorithm. In addition, the proposed solutions suggest better AGV routing for collision avoidance and deadlock prevention possibilities.

Abstract: According to official statistics, road transport is one of the most dangerous and costly in terms of life and costs of hospitalization and post-accident medication. Thus, safety is a matter of great interest at national level and, perhaps internationally. Road safety on public roads in Romania is low compared to international standards. The mortality rate is more than twice the EU average. Given that road traffic and victim maintenance costs are a real economic problem, a European harmonization of the recording and assessment of events involving the bodily injuries of those involved in road events is necessary. Road events are one of the main causes of mortality in modern society. For this reason, the safety of motor vehicles has become the most important issue in their development. Road traffic injuries are a problem that can be controlled by proper attention to traffic avoidance strategies. Side impact is the second major cause of mortality and injury after frontal impact in road traffic analysis.

Abstract: Abstract: The combined effect of variable viscosity and thermal conductivity on dissipative flow of oil-based nanofluid over a permeable vertical plate with suction has been studied. The governing partial differential equations have been transformed into a coupled third-order ordinary differential equations using similarity techniques. The resulting third-order ordinary differential equations were then reduced into a system of first-order ordinary differential equations and solved numerically using the fourth-order Runge-Kutta algorithm with a shooting method. The results revealed that both viscosity and thermal conductivities of CuO oil-based nanofluid enhances the intensity of the skin friction coefficient and the rate of heat transfer at the surface of the plate. Furthermore, the thermal boundary layer thickness is weakened by the viscosity of CuO oil-based nanofluid, the Prandtl number, the suction parameter, the permeability of the medium and the thermal Grashof number

Abstract: The developments of the high power proton accelerators become a worldwide interest to provide various applications, where the targets are demanded to efficiently produce secondary beams and to survive intensive MW class proton beam power supplied by the accelerators. Solid metal targets might be melted by very high heat flux that is caused by the intensive proton beam bombardment. In fact, the incident occurred at J-PARC (Japan Proton Accelerator Research Complex), in which the gold solid target was locally melted to explosively jet molten gold. The molten gold jet collided with a structural beryllium flange plate that has a function of vacuum boundary. Some parts of molten gold were splashed and the other stuck on the flange plate. The relationship between the impact velocity and the morphology of the sticking pattern on the plate was quantitatively evaluated by introducing fractal analysis. It was found that the fractal dimension is correlated with the impact velocity and might be a useful factor to indicate the localized impact force and behavior.

Abstract: The paper presents the analysis of plastic indentations resulting after the impact between a steel ball and a disc made of mild steel, rotating about a vertical axis. The imprints are analysed using a laser scanner, the profiles of the mark, in normal and tangent section about the impact point radius, being relevant. It is shown that the use of parabolas is sufficient to approximate the profiles of the imprint. The profiles from the two sections are interpolated and then brought for comparison into the same coordinate system. Finally, the curvature radii of the profiles from the two sections are found and the remark that increasing the angular speed of the disc presents opposite effects to the curvature radius in the two sections.

Abstract: This article discusses regularity between the temperature fluctuation of environment, in which operates the transmitting device, and a random frequency shift of a carrier. Shows how frequency stability over temperature of reference oscillators of transmitting devices influences the probability of packet loss as a result of collisions in asynchronous radio system without feedback. Particular solutions for the uniform and Gaussian distribution of random frequency shift are presented.

Abstract: Long-span bridge across the river in cold areas, is often impacted by the drift ice in spring, thus having some severe effects on the stability and vibration of the bridge structure. With a long-span prestressed concrete T-rigid frame bridge as studied object, based on the display analysis function of the LS-DYNA software, this paper represents the simulating process of the contact and collision between the drift-ice and T-rigid frame bridge pier, and the influence of various factors was analyzed, such as model boundary condition, contact types of river ice and pier, algorithm and element connection transition area. Thus the reasonable calculation model of the collision force caused by drift-ice to pier was determined. The result has important theoretical and practical value to ensure the safety of the bridge in cold area, as well as to reduce the project cost.

Abstract: Based on the coupling of PC-Crash program and MADYMO software, thekinematics laws of pedestrian in the contact process for automobile-pedestrian collision are analyzed through modeling and simulation by establishing vehicle model and pedestrian model, and selecting main influencing factors on contact phase as independent variables for simulation tests.