The article provides a classification of factors affecting the efficiency of the DVRE system in operating conditions in mountain quarries. A detailed classification of factors affecting the reliability of mining heavy-duty dump trucks operating in mining quarries for such groups of features as design, technological, operational and road-climatic is provided. In addition, the article provides a classification of factors based on controllability. To assess the influence of the stochastic nature of external influences that determine the dynamics of the interaction of the vehicle with the roadway, rational methods based on probability theory are substantiated. Three of them are recommended for an adequate assessment of the influence of external influences on the output indicators of a career heavy-duty dump truck, in particular for evaluating the process of interaction of a vehicle with a roadbed, which is probabilistic in nature. Among the recommended estimation methods are included such as the method of approximating the external load with a periodic function such as a sinusoid with certain values of the amplitude and period of oscillation, the method of expanding the periodic function in Fourier series and the probabilistic-statistical method, which is based on taking into account the action of many random factors characterized by a stable frequency.

Исследована низкочастотная дисперсия комплексной диэлектрической проницаемости нематических жидких кристаллов (НЖК) в диапазоне частот (10-10 5) Гц в температурном интервале, охватывающем нематическую и изотропную фазы. В качестве объектов были выбраны НЖК, как с положительной, так и отрицательной диэлектрической анизотропией: 4-н-амил-4'-н-гексокси цианстильбен, 4-цианофениловый эфир 4'-н-октилоксибензойной кислоты, 4-гептилокси-4'цианостильбен. Представлена принципиальная схема экспериментальной установки для исследования сквозной электропроводности жидкокристаллических веществ. Из экспериментально полученных зависимостей комплексной диэлектрической проницаемости следует, что у всех НЖК диэлектрическая проницаемость на средних частотах (τ < 1) имеет равновесное значение, т. е. ε′, ε″(tgδ) практически не зависят от частоты ν. На низких частотах электрического поля (τ << 1) наблюдается значительный рост диэлектрической проницаемости ε эфф. и тангенса угла диэлектрических потерь tgδ. Установлено, что возрастание ε эфф. и tgδ при низких частотах электрического поля обусловлено влиянием сквозной электропроводности. Изучена зависимость сквозной электропроводности от температуры в нематической и изотропной фазах. Обсуждаются способы исключения вклада сквозной проводимости в комплексную диэлектрическую проницаемость жидких кристаллов на низких частотах. Ключевые слова: диэлектрическая проницаемость жидких кристаллов, низкочастотная дисперсия, сквозная электропроводность жидких кристаллов.

This article studies the dielectric constants of the nematic ε, ε, and isotropic εis phases of a highly polar liquid crystal of 4-cyanophenyl ether of 4′-n-octyloxybenzoic acid in the megahertz range of electric field frequencies (105-108) Hz, as well as the anisotropy of the dielectric constant Δε = ε − ε. The authors have revealed the relaxation processes and mechanisms responsible for them. In addition, they calculated the relaxation times, dipole polarization activation energy, and deceleration parameters in the nematic phase. The design of a measuring cell is presented, which allows studying the dielectric constant of the liquid crystal at various orientations of the director (provided by the magnetic field) relative to an alternating electric field with small volumes of matter. The results show that the dispersion of the dielectric constant in the investigated frequency range of the electric field is characterized by two relaxation processes with τ ~3 ∙ 10−8 s and (τ)в ~ 1,5 ∙ 10−9 s. The dispersion mechanisms are due to the rotation of polar molecules about their short and long axes respectively. The dispersion of the dielectric constant corresponds to the spectrum of relaxation times. The dispersion mechanisms are associated with two relaxation processes: the precession of molecules along a cone within the spatial angle allowed by the value of the order parameter of the liquid crystal S < 1, and the rotation of molecules around the longitudinal axes. The relaxation times corresponding to these mechanisms are commensurate with each other. The dispersion of the dielectric constant in the isotropic phase is characterized by a relaxation process with τis ~ 6 ∙ 10−9 s. The dispersion mechanism is due to the rotation of molecules around short axes.

No abstract