Influence of the position of the center of mass of a trailer category O1 on the stability of the road train

In a number of operational properties of motor vehicle (ATZ) at the tendency of increase of speeds of movement the most important indicators of the kept quality, in any modes, are stability and controllability. The choice of constructive parameters of ATZ providing these properties increases active safety of operation and reduces probability of road accidents during the execution of transport operations. From the point of view of practical purposes at operation of ATZ not only the reason of infringement of stability becomes important, and reaction of ATZ to it and control actions of the driver which are ambiguous and unstable. Therefore, it is assumed that the stability and controllability of the ATZ movement should be provided by the design parameters of the machine itself. The result of the analysis of the course stability of the road train was the expression of the critical speed of rectilinear motion. According to the developed mathematical model, the critical velocity is determined. Calculations were made for a road train consisting of a VAZ-2107 car and the uniaxial trailer for different loads of the trailer and different location of its center of mass. According to the initial data inherent in the nominal load of the car and the maximum load of the trailer and the location of the center of mass of the trailer on the longitudinal axis and in the center of mass of the loading platform, the critical speed is about 36 m/s (129.6 km/h). In transient modes of movement, such as "entering the circle and moving in a circle", "jerk of the steering wheel", "shift", "snake", displacement of the center of mass of the trailer in both the longitudinal and transverse planes, the critical speed decreases, and more significantly reduction occurs when the transverse displacement of the center of mass. Thus, if at the maximum displacement of the center of mass of the trailer on the x-axis (x = -0.75 m) the rate of oscillation instability decreases by 36.4% (Gn = 350 kg), 38.4% (Gn = 500 kg) and 44.3% (Gn = 750 kg) in comparison with this speed in the absence of displacement, then at the maximum displacement along the y -axis in the rate of oscillation instability decreases by 45.4%, 55.2% and 63.6%, respectively. In the case of such a trailer loading, the center of mass of the trailer shifts along both the x-axis and the y-axis, there is a further decrease in both the critical speed of the road train and the rate of oscillation instability. This must be taken into account when loading the trailer.

A study of self-oscillation instability in varicap-based electrical networks: analytical and numerical approaches

Проведено аналитическое и численное исследование разрушения решения одного нелинейного уравнения cоболевского типа, которое описывает процессы в электрических схемах на основе варикапов. Аналитическое исследование проводилось энергетическим методом. Для численного решения исходное уравнение в частных производных аппроксимировалось с помощью метода прямых системой обыкновенных дифференциальных уравнений, которая затем решалась с помощью одностадийной схемы Розенброка с комплексным коэффициентом. В основе численной диагностики разрушения решения исследуемого уравнения лежало вычисление апостериорной асимптотически точной оценки погрешности приближенного решения на последовательно сгущающихся сетках. The blowup of solutions is analytically and numerically studied for a certain Sobolevtype equation describing processes in varicapbased electrical networks. The energy method is used for the analytical study. For the numerical analysis, the original partial differential equation is approximated using a system of ordinary differential equations solved by the onestage Rosenbrock scheme with a complex coefficient. The numerical diagnostics of solutions blowup is based on a posteriori asymptotically exact error estimation on sequentially condensed grids.

Behavior of the solutions of a partial differential equation with a piecewise constant argument

In this paper, we consider a partial differential equation with a piecewise constant argument. We study existence and uniqueness of the solutions of this equation. We also investigate oscillation, instability and stability of the solutions.