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Various methodologies and tools applied to identification of vehicle and collision impact seek to present more and more accurate solutions to reproduce, restore, recreate and investigate the casualty. Modern computer technology and software provide the tools to solve specific problems developing mathematical modelling of complex mechanical systems...
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... Thus, dynamic processes related to the deformation of the car tire during operation could be modelled with sufficient accuracy (Figs 18 and 19) and the influence of bumpy road surface on driving comfort could be taken into account. The created dynamic car model with 12 generalized coordinates (Karapetkov et al. [21,22]; Uzunov et al. [23,24]) takes into account the effect of the elasticity of suspension, including the tire. The model performs dynamic analyses of a car tire at a fixed value of the elastic constant. ...
The present paper focuses on an elastic properties analysis of new and depreciated tires. The research was carried out using two different methods, field and numerical, respectively. The purpose of the study is to check whether there is a change in the elastic properties of the tire during its depreciation and to what extent these processes affect the comfort of driving and riding. The experimental tests were conducted on a hydraulic test stand and by applying strength and deformation analysis the effect of its structure deformation was additionally considered. The investigation performed on a vehicle-based tire test stand to find out stress-strain and tire deformation was with different vertical loading according to FEM. The numerical solution was reached by implementing SolidWorks - Simulation and Abaqus. The obtained results are graphically compared, and the average value of the elastic constant for a new and depreciated tire has been determined.
... These equations are valid if the friction force is in accordance with Coulomb's law and the wheels slide on the ground without rolling. According to (7), the wheels keep a continuous contact with the road (Karapetkov, & Dimitrov, 2022;Karapetkov et al., 2019). ...
... Main influence Source Air temperature and humidity Ultrasonic signal propagation speed [3,7] Atmospheric pressure and gas composition of the air They can be neglected when measuring the same altitude [1] Measurement distance Operating frequency of ultrasonic sensors [8] Measured material The object of measurement must be located in the far zone of the ultrasonic emitter [4] Angle and distance of reflection Cost angle of transducers and their dimensions [2] From the analysis of the factors influencing the accuracy of measurement, using ultrasonic sensors, it is evident that the humidity and air temperature have the greatest influence. Therefore, they need to be measured periodically in order to make adjustments, validations, using computational methods. ...
In this article, after an examination and thought of the benefits and weaknesses of the current devices of ultrasonic
easurement frameworks, the ultrasonic tool has been created, which takes into account contactless assurance of meat
quality. The vector of ultrasound attributes utilized, decreased with head parts and inert factors, is utilized to acquire relapse
models with stringently characterized numerical strategies, keeping away from the abstract factor in deciding the principle
pointers of meat quality. A proper distance between the ultrasonic sensors and the to acquire the ultrasonic qualities of
chicken meat, which is 20 cm. For pork, this distance is 30 cm. The distance was observed to be explicit to every item
estimated. It was tracked down that 3 principal components and 3 latent variables are expected to depict the scattering in
the element vector got from ultrasound qualities. Models for expectation of principle pointers for the quality of pork and
chicken meat have been created, which can be utilized for determining the difference in these markers. A relative
investigation of the models of the two types of meat was made. While assessing these prescient models for the qualities of
the meat, an expectation exactness of 66-94% for pork was acquired. Lower expectation exactness (46-91%) was
accomplished for chicken meat. There is a comparability in the models of pork and chicken with error rates not surpassing
5%. For these properties, it is suitable to utilize found the middle value of models for the entire gathering of tried meats.
The proposed programming and equipment apparatuses enjoy an upper hand over known arrangements in this field, in light
of the fact that the elements of the oscilloscope utilized in most such frameworks are performed straightforwardly in the
single-board microcomputer controlling the estimating tool. The consequences of the work can possibly be utilized in the
aberrant assurance of key markers of meat quality in the lab and straightforwardly on the production line. Keywords:
ultrasounds, food analysis, meat quality assessment, applications, Regression model
... Interpolationan approach that refers to the determination of intermediate values in the data; Compressed sensingan approach for compressing data with their subsequent facilitated recovery; Samplingan approach that allows sampling of a continuous signal according to Theorem S>2n, where n is the maximum frequency of the signal spectrum. The application of these methods in data transmission and recovery is a topical issue [5]. In particular, no reported studies have been found in the available literature related to the application of the "interpolation" method [6] in the processing of sensor data to determine water stress from drought in cucumbers. ...
Wireless sensor networks offer theoretical and practical challenges related to their application capabilities. Leaf
temperature is a valuable indicator of the physiological status of plants, corresponding to both biotic and abiotic stressors.
The disadvantage of thermal cameras is that they produce large images, which makes them unsuitable for use in wireless
sensor network systems. The solution to this problem is the use of thermopile sensors. In the present work, a comparative
analysis is made and a suitable method for interpolation of data from a thermopile sensor is selected in the analysis of the
physiological state of cucumbers in a period of drought. It was found that a suitable method for interpolation of data from
a thermopile sensor for the purpose of their scaling is spline interpolation, because when using it there is a minimal
difference in the data from the histograms of the obtained data for the measured temperature of cucumbers compared to
those from a thermal camera. A comparative analysis of the obtained results with those from available literature sources
was made. Recommendations for the practical application of the obtained results are given and guidelines for future
research in the subject area are given.
... The aim of the present paper is to design and come up with a dynamic model of a vehicle-fixed barrier front crash in three separate motion phases and to investigate the inertial forces' impact on occupant behavior in the passenger compartment. While predicting dynamically changing values and inertial forces, the impact of passive safety systems has been also determined [7][8][9][10][11][12]. ...
... ∑ → F i is the acting resistance forces. After separating the variables and integrating, for the time interval from initial rotation to impact, we obtain the following: (11) where the friction force is F τ = −µ·m·g. Here, µ = 0.8. ...
In most cases, the dynamic investigation of vehicle collisions with stationary obstacles concerns solutions to complex tasks related to the identification of occupant position in the vehicle. The motion of the bodies in the car is determined by the intensity of the inertial coordinate system, also known as moving reference frame, invariably fixed to the vehicle’s center of mass. The focus of the study is on how forces of inertia change their magnitude and direction in the car’s motion. This requires specific analysis carried out by dividing the vehicle trajectory into separate stages according to certain indicators, such as free motion, impact process, and post-impact residual motion. Particular attention has been paid to the impact itself, in which the forces of inertia are the most intense, and their magnitude and direction change abruptly. A solution to a Cauchy problem has been found, in which initial kinematic parameters of the crash process are considered, satisfying the kinematic values at rest position.
... The requirements for high accuracy in the study of an impact between cars, in particular when determining the location of the impact and the velocities before the impact, necessitates the use of more accurate methods based on precise mechano-mathematical modeling and computer simulation. We have been working for a long time on a new approach, which is described in [14][15][16]. In [14], a research method is proposed, which is based not only on the theorem for the change in the amount of movement of each car for the time of the impact but also on the theorem for the change in the kinetic moment. ...
... In [14], a research method is proposed, which is based not only on the theorem for the change in the amount of movement of each car for the time of the impact but also on the theorem for the change in the kinetic moment. The movement of the cars after the impact is identified by a spatial dynamic model and computer simulation [15,16]. ...
... In order to determine the quantities involved in expressions (8) and (9), mechanomathematical modeling and computer simulation of the movement of vehicles after the impact are applied [2,[14][15][16]. According to the available traces and findings in a first approximation, the position of the cars at the moment of impact is selected, corresponding to the phase of maximum deformation, respectively, when forming the maximum impact force. ...
Although vehicles as a whole are symmetric, car crashes rarely follow the symmetric line (crashes are axisymmetric). In this paper, we examine car crashes by an updated Momentum 360 method, and car symmetry helps us easily find out what happens within the accident. We propose an improvement of the Momentum 360 method by taking into account the frictional forces between the wheels and the road surface during the time of impact. According to the momentum change theorem for the duration of the impact for each car and the kinetic moment change theorem for the relative motion of the given vehicle around its center of mass, the impact problem is introduced and solved. The solution considers the impulses of the principal vectors of the wheel friction forces, the gravity force, and the aerodynamic force for each car at the time of impact, as well as the principal moments of the friction forces between the tires and the road surface as a function of time. A mechano-mathematical multi-mass 3D model and a computer simulation of the movement (“Expertcar” software) are used to study the movement of each vehicle after the impact. Through successive approximations, the velocity vectors of the mass centers of the vehicle immediately before the impact are determined, and the location of the impact is identified. The presented decision model significantly improves the accuracy of road accident investigations.
... The relative motion of the wheels, differential/s and the engine is characterized by a system of four differential equations obtained by Lagrange method [6,7], which has the type ...
In the present study, technical analysis of an experimental research has been carried out to verify tire-road friction coefficient of a vehicle with an anti-lock braking system (ABS) in the process of maximum braking force and in different types of surfaces. The study was conducted using three independent methods, including effective braking distance reading, deceleration measurement with an accelerometer, and a numerical experiment to study vehicle deceleration. The obtained polynomial determined the dependence of the coefficient of friction as a function of the velocity of the center of mass. Verification of experimental results from the first and second experiment was carried out by numerical analysis on the vehicle's deceleration implementing mechanical-mathematical model with ABS module. The results obtained from both the conducted experiment and numerical analysis on tire-road friction coefficient were processed by the methods and means for statistical analysis and expert assessments to determine the extent of results validity and credibility of the performed experiments. Considering the conducted dynamic study on the vehicle braking performance with an anti-lock braking system and the displayed graphic dependences, it has been proved that the maximum braking delay is achieved at constant pressure on the brake pedal. The coefficient of friction decreases with the increase of initial speed for different types of surfaces. High coefficient of friction is explained by the fact that the wheels of the car roll on the highest available slip and the coefficient of friction is similar to that at rest.
... That may be tied to time to reach the studied speed using proving values of vehicle acceleration on relevant condition as present paper give. The same is true for important area of traffic accident analyses described in some papers by Karapetkov and etc. in [9] and [10]. In these cases may be search relation between established acceleration and deceleration of vehicles in other point of view according to commitment with totality of their qualities. ...
... Analysis shows that the right one of the right turning flows (3)(4)(5)(6)(7)(8)(9)(10)(11) have an average acceleration rate as straight ahead flows and this is not from reasons related with distances, curves radii and other of reported data for this study. ...
Acceleration of vehicles is a parameter needed of calculation intergreen time of cycle length at signalized junctions. Its value is vary for different vehicles and must be averaged for aim of that calculation or be taken its maximum. The paper present acceleration rate of cars study in real traffic flows entered in three traffic light crossroads in Sofia city. The goal is determinate average and maximum value of that parameter due the road infrastructure condition of vehicles movement related with move direction, curves radii, slope of the road, etc. The result obtained in the research would be useful for intergreen time compute in case of traffic light time determination in similar movement condition.
... Macro simulation of vehicle motion in case of loss of lateral stability is observed in an arbitrarily accepted absolute coordinate system [5][6][7][8][9][10]. To study the car motion, it has been assumed that its own coordinate system ′ ′ ′ is movable and permenantly connected to the vehicle center of mass (Fig. 1a). ...
Active control systems of today's cars have been used over a vast domain of applications, as they seem to represent a complex compromise between car handling, stability and ride comfort. Finding a balance between these three components is of paramount importance to stability, a well-known prerequisite, directly proportional, for road safety. Active suspension means active control of certain parameters of vehicle suspension and their changes over time in their equilibrium state. The aim is to maintain vehicle stability going round bends. Setting a tolerance for these parameters results in a compromise in ride quality of vehicle carbody. This is usually accomplished by changing the elasticity of the springs in suspension and increasing their elastic constant to hardening. Thus, a minimum tolerance in the rotation of the carbody around the transverse and longitudinal axes can be guaranteed, respectively a reduction of the centrifugal iner-tial forces as a function of the rotation defined. To solve this problem a dynamic study of a car model is needed, taking into account elasticity of spring suspension and wheel suspensions, dampers and tyre damping as well as tire-road friction forces. An indicator of this is the variable friction coefficient as a function of the velocity of the contact point.
... The simplest and easiest way to solve the problem when two vehicles are impacted is by applying Momentum Conservation Principle that has the form [11][12][13][14][15][16][17]: ...
Globally, statistical analysis reports show that the most serious vehicle collisions mainly constitute of two-vehicle accidents. The dynamic and kinematic model of car crashes is particularly challenging when requirements for improved accuracy of the analysis are introduced. For more sophisticated models the more accurate the analysis, the more variables in each phase of motion and impact need to be introduced. Two basic problems must be solved, defined by the final rest position of the cars: whether it is known or must be found by solving Cautchy problem. This article presents a dynamic impact analysis between two vehicles, using data for known final rest position and avoiding the uneasy task of selecting the correct coefficient of restitution. Undeniably, it represents the ratio between post impact and prior to impact relative velocity of the centers of mass of the two vehicles in projection in the direction of the crash pulse. The presented results were obtained by simulation and graphical dependencies of the proposed algorithm for reliability analysis estimation, followed by the deduced discrete positions of post-impact vehicles motion, which confirms the useful application of the proposed algorithm. A comparative study was carried out based on the known treds from first-hand inspection in the field accident.
