Damage Boundary Study of Crystal Oscillators under Shock Environment

The crystal oscillator is a widely used electronic component in a circuit, whose accuracy is strongly affected by the external mechanical environment. To depict the failure mechanism of the crystal oscillator, the damage boundary of this component under the shock environment is studied experimentally in this paper. Through subjecting “step-up” loads on different groups of crystal oscillators, two failure modes (frequency jumping and structural fracture) are monitored and validated. Experimental results prove that “frequency jumping” failure mode is governed by the value of the acceleration shock response spectrum (ASRS) in a certain frequency range, while the failure mode “structural fracture” is governed by the peak value of the ASRS. Through analyzing the shock response spectrum, damage boundaries are given for these two failure modes, which can provide a reference for component design and failure assessment.

Performance Analysis of a Travelling-Wave Ultrasonic Motor under Impact Load

With the increased application of ultrasonic motors, it is necessary to put forward higher demand for the adaptability to environment. Impact, as a type of extreme environment, is widespread in weapon systems, machinery and aerospace. However, there are few reports about the influence of impact on an ultrasonic motor. This article aimed to study the reasons for the performance degradation and failure mechanism of an ultrasonic motor in a shock environment. First, a finite element model is established to observe the dynamic response of ultrasonic motor in a shock environment. Meanwhile, the reasons of the performance degradation in the motor are discussed. An impact experiment is carried out to test the influence of impact on an ultrasonic motor, including the influence on the mechanical characteristic of an ultrasonic motor and the vibration characteristic of a stator. In addition, the protection effect of rubber on an ultrasonic motor in a shock environment is verified via an experimental method. This article reveals the failure mechanism of ultrasonic motors in a shock environment and provides a basis for the improvement of the anti-impact property of ultrasonic motors.

Particle acceleration by transient structures around Earth’s bow shock

<p>Upstream of Earth’s bow shock, the foreshock is filled with particles that have been reflected at the bow shock and are streaming away from it. Interaction of these particles with solar wind particles and discontinuities within this region can cause foreshock transients to form. Downstream of Earth’s bow shock, localized magnetosheath jets with high dynamic pressure are frequently observed. When such a fast magnetosheath jet compresses the ambient magnetosheath plasma, an earthward compressional bow wave/shock can form. Here we present that foreshock transients and magnetosheath jets can accelerate particles through shock drift acceleration, Fermi acceleration, and the betatron acceleration. Foreshock transients and magnetosheath jets therefore can increase the particle acceleration efficiency of the parent shock by providing additional acceleration. The shock environment relevant for particle acceleration is not just the shock itself, but also the nonlinear transient structures both upstream and downstream of it.</p>

Peculiarities of organization of the environment of nongovernmental rehabilitation centers

The subject of this research is the peculiarities of organization of the environment of specialized centers that focus on recovery of the patients. The object of this research is the national and foreign nongovernmental rehabilitation centers for drug addicts and alcoholics. The author examines such aspects of problem as the organization of rehabilitation centers in Russia and abroad, as well as outlines the key vectors in formation of the environment for rehabilitation those who faced alcohol or drug addiction. Particular attention is given to the peculiarities of environmental organization of rehabilitation centers. In this context, the space-planning solution is of major importance. The main conclusion consists in description of nuances of the environment of rehabilitation centers defined based on their organization (comfort, safe, friendly, shock environment). The author’s special contribution lies in identification of typological characteristics of the existing rehabilitation centers (VIP houses; hotel, family, country style; with focus on labor or motivation), and their functionality. The scientific novelty lies in the comprehensive study that determined the key characteristics of environmental organization of rehabilitation centers, as well as their typological features, which allows outlining the prospects of their establishment and development.