In the context of signal processing, the comparison of time histories is required for different purposes, especially for the model validation of vehicle safety. Most of the existing metrics focus on the mathematical value only. Therefore, they suffer the measuring errors, disturbance, and uncertainties and can hardly achieve a stable result with a clear physical interpretation. This paper proposes a novel scheme of time histories comparison to be used in vehicle safety analysis. More specifically, each signal for comparison is decomposed into a trend signal and several intrinsic mode functions (IMFs) by ensemble empirical mode decomposition. The trend signals reflect the general variation and are free from the influence of high-frequency disturbances. With the help of dynamic time warping, the errors of time and magnitude between trends are calculated. The IMFs, which contain high-frequency information, are compared on frequency, magnitude, and local features. To illustrate the full scope and effectiveness of the proposed scheme, this paper provides three vehicle crash cases.
This paper proposes a passive vibration isolator methodology based on inerters for improving the performance of the famous statue of Michelangelo Buonarroti. More specifically, the five-degree-of-freedom (5DOF) model of the statue based on experimental tests has been presented. Using this developed model, the impact of actuation devices such as tuned mass-damper (TMD) and tuned mass-damper-inerter (TMDI) in vibration reduction of this structure is investigated. Then, the effect of TMDI on the 5DOF model accounting for physical limitations due to system parameters is presented. To have better insight into the effect of inerters in this case, some index functions have been used here. Finally, simulation results are provided to illustrate effectiveness of the passive element of TMDI in vibration reduction transmitted to the statue in vertical direction.
This paper deals with the problem of semiactive vibration reduction in a class of automotive systems. Most conventional suspensions use passive devices to absorb impacts and vibrations, which is generally difficult to adapt to the uncertain circumstances. Semiactive suspension techniques promise a solution to the above problem with some comparatively better features than active and passive suspension devices. In this work, the semiactive suspension with magnetorheological (MR) dampers is applied for the vibration attenuation. Both backstepping and heuristic control strategies are proposed. In the design of backstepping controller, the Dahl model of the MR damper is used to estimate the damping force of the semiactive device taking the control voltage and velocity inputs as variables and the semiactive control law takes into account the hysteretic nonlinearity of the MR damper. Two simple heuristic control strategies are also presented. The performance of the proposed semiactive suspension strategies are evaluated through an experimental platform for the semiactive vehicle suspension available in our laboratory.
This paper investigates the input-to-state stability (ISS) problems for a class of discrete-time nonlinear switched singular systems (SSSs). Two novel ISS criteria are proposed based on average dwell time (ADT) approach and iterative algorithm of discrete-time systems (IADS). In particular, the following two cases are considered for the underlying systems: the first case is that all the sub-systems are exponentially stable, and the other case is that only a few sub-systems are exponentially stable. The corresponding ISS criteria are obtained to guarantee that the closed-loop systems are input-to-state stable via ADT approach and IADS. We neither construct a specific Lyapunov function for ISS in the proof process of the stability criteria nor design a specific structure of the control inputs. The design deficit of the switching controllers is optimized and the design difficulty of the switching controllers is reduced via the proposed criteria. Finally, two numerical examples are provided to illustrate the feasibility of the results obtained.
Thanks to advancements in communication and online social media, there has been a surge of useful online educational resources across the Internet. In addition to supplementing educational materials, these resources could be used in varying education research and potentially advance the quality of education. Nevertheless, conducting such research projects requires using big data techniques and approaches to find meaningful resources and harnessing them in an effective way. In this chapter, we present a roadmap for how to incorporate online social media in education research projects. The roadmap consists of three major components: project initialization, data collection, and data utilization. Furthermore, we present some learned lessons, tips, and tricks, as well as case studies from the Teachers in Social Media project ( www.teachersinsocialmedia.com /). We believe this chapter can be used as a practical reference point for many researchers whose concern is connecting data to their education research endeavors.
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This paper investigates the design of hybrid interval observers (IOs) of switched linear systems involving additive disturbances, whose subsystems need not to be cooperative. We first propose the definition of IOs for switched systems and extend the coordinate transformation for non-switched linear systems into switched ones. Based on the switched coordinate transformation, the considered switched linear system is converted into a hybrid cooperative system, whose states jump at each switching times. Then, by using the multiple Lyapunov functions method, IOs for switched linear systems are designed in two cases, that is, all of the subsystem matrices are Hurwitz and some of the subsystem matrices are not Hurwitz. Moreover, by exploiting the stabilization property of switching behaviors, IOs for switched systems, whose subsystem matrices are not all Hurwitz, are proposed based on multiple discretized Lyapunov functions. The constructed IOs for the considered switched systems are hybrid dynamical systems and the initialized states of the IOs at each switching time are coupled, since the transformation matrices for different subsystems are different. Finally, we afford an example to illustrate the validity of the derived results.
This paper is devoted to design an event-triggered data-driven control for a class of disturbed nonlinear systems with quantized input. A uniform quantizer reconstructed with decreasing quantization intervals is employed to reduce the quantization error. A neural network-based estimation strategy is proposed to estimate both the pseudo partial derivative and disturbances. Consequently, an input triggering rule for single-input single-output systems is provided by incorporating the estimated disturbances, the quantization error bound and tracking errors. Resorting to the Lyapunov method, sufficient conditions for synthesized error systems to be uniformly ultimately bounded are presented. The validity of the proposed scheme is demonstrated via a simulation example.
The aim of this study is focusing the issue of traditional clustering algorithm subjects to data space distribution influence, a novel clustering algortihm combined with rough set theory is employed to the normal clustering. The proposed rough clustering algorithm takes the condition attributes and decision attributes displayed in the information table as the consistency principle, meanwhile it takes the data supercubic and information entropy to realize data attribute shortcutting and discretizing. Based on above discussion, by applying assemble feature vector addition principle computiation only one scanning information table can realize clustering for the data subject. Experiments reveal that the proposed algorithm is efficient and feasible.
This paper is concerned with the problem of multilevel association rule mining for bridge resource management (BRM) which is announced by IMO in 2010. The goal of this paper is to mine the association rules among the items of BRM and the vessel accidents. However, due to the indirect data that can be collected, which seems useless for the analysis of the relationship between items of BIM and the accidents, the cross level association rules need to be studied, which builds the relation between the indirect data and items of BRM. In this paper, firstly, a cross level coding scheme for mining the multilevel association rules is proposed. Secondly, we execute the immune genetic algorithm with the coding scheme for analyzing BRM. Thirdly, based on the basic maritime investigation reports, some important association rules of the items of BRM are mined and studied. Finally, according to the results of the analysis, we provide the suggestions for the work of seafarer training, assessment, and management.
This paper is dedicated to studying the mean square exponential stability of switched stochastic time‐varying delay neural networks with asynchronous switching aperiodic intermittent control. By utilizing the Halanay‐type inequality and designing appropriate asynchronous switching aperiodic intermittent control, several novel stability criteria of switched stochastic delay neural networks with asynchronous aperiodic intermittent control are presented under the Lyapunov function method and Lyapunov functional method. Among them, asynchronous switching aperiodic intermittent controllers are more practical and flexible compared to state feedback controllers. Finally, we provide two examples to verify the effectiveness of the theoretical results.
This paper investigates the problems of stability and L 1 -gain controller design for positive switched systems with mixed time-varying delays. The mixed time-varying delays are presented in the forms of discrete delay and distributed delay. The purpose of this paper is to design a class of switching signals and a state feedback controller for the considered system such that the resulting closed-loop system is exponentially stable with L 1 -gain performance. By constructing an appropriate co-positive type Lyapunov–Krasovskii functional and using the average dwell time approach, we propose a sufficient condition to ensure the exponential stability with weighted L 1 -gain performance for the system. On the basis of the obtained results, an effective method for designing such controller is established. Finally, a numerical example is presented to demonstrate the feasibility of the results obtained.
