Optimal Protection from Impact, Shock, and Vibration

Geometrically nonlinear mode approximations for impulsively loaded homogeneous viscous beams and frames

Effect of forcing frequency on nonlinear dynamic pulse buckling of imperfect rectangular plates with different boundary conditions

Understanding the dynamic response of accelerometers is critical to interpreting data obtained in impulsive loading conditions. While this information is commonly provided by manufacturers, the estimated properties are typically obtained at levels below the full range of the sensor. Using high bandwidth operating data of varying amplitudes, the damping ratio and principle resonant frequency of shock accelerometers are estimated using a simple dynamic model. While the resonance is shown to be essentially amplitude-invariant, the damping ratio is shown to vary with the excitation amplitude. Possible causes related to the frequency content of the excitation and the presence of repeated roots are discussed.KeywordsShock accelerometersMicroelectromechanical systems (MEMS)SensorsDampingOperating modal analysis

With the means of rigid-elastic coupled tire model, the in-plane vibration characteristic of heavy truck tire is investigated and the time-domain vibration response with the proposed tire model is discussed. With the means of finite difference method, rigid–elastic coupled tire model is developed from flexible beam on elastic foundation tire model and the nonlinear radial stiffness of sidewall is derived and related with the inflation pressure and geometrical feature of sidewall curved arc. In-plane vibration characteristic of heavy truck tire, including transfer function and modal parameters is investigated by experimental hammer test. Taking the error between the analytical and experimental modal frequency as the object value, Genetic Algorithm is utilized to identify the un-known structural parameters. In-plane time-domain dynamics response of heavy truck tire utilizing the proposed tire model with linear/nonlinear sidewall radial stiffness is researched and compared with experimental result. Experimental and theoretical results shows that in-plane rigid–elastic coupled tire model with nonlinear sidewall stiffness can be used to better the precision on predicting the vibration feature excited by the random irregular signal. Rigid–elastic coupled tire model with nonlinear sidewall stiffness can be extended to other heavy truck tire with a large section ratio or tires under impulsive loading conditions.

Numerical and experimental testing of vehicle tyre under impulse loading conditions

Distributed admission control solutions share the idea that no coordination among network routers (ie, explicit signaling) is necessary, when the decision whether to admit or reject a new offered flow is pushed to the edge of the IP network. Proposed solutions differ in the degree of complexity required in internal network routers, and result in a different robustness and effectiveness in controlling the accepted traffic. This paper builds on a recently proposed distributed admission control solution, called GRIP (Gauge and Gate Reservation with Independent Probing), designed to integrate the flexibility and scalability advantages of a fully distributed operation with the performance effectiveness of admission control mechanisms based on traffic measurements. We show that, in the assumption that traffic sources are dual-leaky-bucket shaped, GRIP allows providing deterministic performance guarantees. Tight QoS performances are made possible even in impulsive load conditions (i.e., sudden activation of several flows), thanks to the introduction of a mechanism in each network node. A thorough performance evaluation of the conservative effects of the stack shows that the throughput reduction brought about by this mechanism is tolerable, and limited to about 15%.

The highly mathematical nature of introductory level vibrations and control theory courses results in students struggling to understand the concepts. Hands-on activity demonstrated in class can help them better understand the concepts. However, there is still an ongoing effort to lower the currently substantial cost of educational laboratory equipment for undergraduate-level engineering courses. Also, with the COVID-19 crisis, the Spring 2020 academic year took an unexpected turn for academics and students all over the world. Engineering faculty who teach laboratories had to move online and instruct from home. Online course preparation takes more time and effort compared to traditionally designed face-to-face courses and was compounded considering the unprecedented situation where many instructors didn't have time to record data from existing lab equipment or record video in their laboratories. In this paper, we present a Matlab Simscape GUI program designed to simulate modeling and control of dynamical systems for vibrations and control theory courses, and their associated laboratories, as one potential solution for online instruction. To complement the simulation program, online classroom and homework activities were designed using a learning sciences approach connecting several critical educational theories which can bolster student motivation, engagement with the material, and overall learning performance. The simulation is presented along with data from 19 students who completed the associated classroom and homework activities. Survey results probing student perceptions about the value of the learning tasks for the simulation were overwhelmingly positive and indicate this approach holds promise in supporting student learning.

Failure of in-pavement light fixtures prompted the Port Authority of New York and New Jersey (PANYNJ) to conduct an in-depth evaluation of the in-service light fixtures in their jurisdiction followed by an instrumentation study. For the study, the L-868B light fixture bases were instrumented with four horizontal and four vertical strain gauges. The Federal Aviation Administration (FAA) embarked on a study in 2019 to replicate and verify PANYNJ results using four different configurations of L-850 light fixtures and corresponding bases with the same instrumentation configuration. A total of eight fixtures with varying combinations of spacer rings, studs, and extension were embedded and instrumented in a conventional flexible pavement test bed. The installed fixtures were subjected to impulse, static, and dynamic loading conditions. This paper summarizes the interaction between light fixtures and slow-rolling aircraft wheel load in terms of observed strains. Following a predefined lateral wander, the test items were trafficked at five different incremental load levels using a 3D-gear traversing bidirectionally at a consistent speed of 4 km/h (2.5 mph). Variations in strains along the two axial directions were examined against the nine different wander tracks. The transition of polarity in base strains with loading distance indicated a larger zone of influence than that from the direct impact of the moving wheel loads on the fixtures.

This paper is devoted to a cycle of laboratory works on the control theory course for students of MPEI. This course was developed for the bachelor students of Institute of Thermal and Nuclear Power Engineering studying on the educational program Automation of technological processes in thermal power engineering, so dynamical characteristics of plants and processes under consideration are typical for thermal ones, for example, surface heat exchangers. The cycle consists of five laboratory works which may be carried out in Matlab/Simulilnk or Scilab/Xcos. Short descriptions of the laboratory works are given, the purpose of each of them, the skills and knowledge being improved, developed or obtained through each laboratory works are specified. The paper also describes how the laboratory works are connected with other aspects of the control theory course and with other bachelor and master courses and how the results obtained by the students may be further used. In order to make the classes more interesting and useful for all students, some variants of varying laboratory works are described. Advantages of using Scilab/Xcos for these laboratory works are given.

Analysis and design of tee joints with double support

Towards a Modern Concept for Teaching Control Engineering

Wave propagation/impediment in a stratum and wave impeding block (WIB) measured for SSI response reduction

The numerical realization of the dynamic programming principle for continuous-time optimal control leads to nonlinear Hamilton--Jacobi--Bellman equations which require the minimization of a nonlinear mapping over the set of admissible controls. This minimization is often performed by comparison over a finite number of elements of the control set. In this paper we demonstrate the importance of an accurate realization of these minimization problems and propose algorithms by which this can be achieved effectively. The considered class of equations includes nonsmooth control problems with $\ell_1$-penalization which lead to sparse controls.

Robust Gain-Scheduled PSD Controller Design from Educational Perspective

Technical characteristics of an innovative prototype e-learning platform using satellite communications for control theory courses are exposed. A detailed account of all necessary tools and mechanisms is presented enabling real time text, and audio/video based communication between tutors and learners. The provided end-user driven services include: a virtual classroom, offline operation, sharing of applications, private/public chatting, audio/video streaming. In addition a concise description of the pilot network architecture depending on the DVB-RCS standard is presented justifying further the choice of the communications platform. Simulation results concerning the teaching of fundamental issues in Networked Control Theory within the proposed architecture are provided. Connections with hybrid configurations such as wireless terrestrial broadband technologies (DVB-RCS/ WiMAX, DVB-RCS/Wi-Fi) are further analyzed and justified. Finally some conclusive anticipated directions related to the future of modern control courses education in connection with state of art technological advances are explored. AMS (classification): 97U50, 97U70, 97U80, 97D99