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To achieve efficient attenuation of noise and vibration characteristics within the helicopter environment, solidstate actuators are seen as one of the most promising smart technologies. The Smart Hybrid Active Rotor Control System project is expected to demonstrate the ability of smart structure systems, employing multiple active material actuators, sensors, and closed-loop controllers, to reduce simultaneously rotorcraft vibration and noise. Within this project, piezoceramic elements were used as actuators to vary the dry friction and the stiffness of the whole helicopter blade system. This active control concept, named Smart Spring, originated a prototype used to demonstrate the ability to attenuate vibrations. Before testing the Smart Hybrid Active Rotor Control System in operative conditions, the dynamic properties of the Smart Spring installed on a nonrotating helicopter blade are investigated. The effects of the Smart Spring actuator on the modal properties are studied through experimental activities carried out at Carleton University. Furthermore, the capability of the Smart Spring to change the dynamic behavior of the helicopter blade is demonstrated by analyzing the shifts in the modal parameters. Finally, a beam finite element model of the blade, with stiffness and mass properties tuned to the experimental structure, is presented.

Methods for the aeroelastic eigensensitivity analysis and the sensitivity analysis of an aeroelastic discrete-gust response were developed, using finite state modeling. An analytical method enables the sensitivity to be estimated and allows the evaluation of the maximum value of the response linked to a discrete-gust input.

Balis Crema, L., G. Coppotelli, and M. Rimondi. Finite element model updating by using 'output-only' experimental data. Proceedings of the 2004 International Conference on Modal Analysis Noise and Vibration Engineering, [...]

06-1437 Agneni, A., R. Brincker, and G. Coppotelli. On modal parameter estimates from ambient vibration tests. Proceedings of the 2004 International Conference on Noise and Vibration Engineering, Leuven, Belgium: 2239-2248, [...]

Coppotelli, G., et al. Damage identification in composite plates by dynamic displacement measurements. Proceedings of the 2004 International Conference on Noise and Vibration Engineering, Leuven, Belgium: 417-432, Sept. 20-22, 2004 [...]

The article presents an analysis of experimental and numerical procedures that analyze an AB 204 helicopter rotor blade's structural properties developed by L. Balis Crema and G. Coppotelli. It describes the development of the dynamic behavior of the blade which is noted to be based on the frequency response-based correlation functions sensitivity to the design parameter changes. The finite element validation of the stiffness distribution of the helicopter rotor blade is evaluated.

Output‐only analysis considers the system excited either by operative or by natural forces, in both cases the input loading which excites the structure is considered, at least in a limited frequency band, as a white noise. Because it is not possible to find directly the spectra, it is necessary to pass through the correlation functions so as to apply the Wiener–Khintchine theorem in order to find the power spectral densities (PSDs). In the past, the modal parameters have been essentially derived by approaches that manipulated the functions mentioned above. In this paper, the modal parameters will be directly estimated from the PSDs, in the frequency domain, and from the correlation functions in the time domain. A particular attention is devoted to the problems regarding the damping ratio overestimation. This effect due to the limited time window in the correlation function estimate is highly present in the low‐frequency modes and could bring to large estimation errors. Experimental examples, carried out both on cantilever beams and on an helicopter blade, are presented. They show the problems related to the techniques using the PSDs, or the correlation functions and the possibility to overcome the overestimation of the damping factors due to the triangular window, also known as Bartlett window. [ABSTRACT FROM AUTHOR]

Mitochondria are thought to have become incorporated within the eukaryotic cell approximately 2 billion years ago and play a role in a variety of cellular processes, such as energy production, calcium buffering and homeostasis, steroid synthesis, cell growth, and apoptosis, as well as inflammation and ROS production. Considering that mitochondria are involved in a multitude of cellular processes, mitochondrial dysfunction has been shown to play a role within several age-related diseases, including cancers, diabetes (type 2), and neurodegenerative diseases, although the underlying mechanisms are not entirely understood. The significant increase in lifespan and increased incidence of age-related diseases over recent decades has confirmed the necessity to understand the mechanisms by which mitochondrial dysfunction impacts the process of aging and age-related diseases. In this review, we will offer a brief overview of mitochondria, along with structure and function of this important organelle. We will then discuss the cause and consequence of mitochondrial dysfunction in the aging process, with a particular focus on its role in inflammation, cognitive decline, and neurodegenerative diseases, such as Huntington's disease, Parkinson's disease, and Alzheimer's disease. We will offer insight into therapies and interventions currently used to preserve or restore mitochondrial functioning during aging and neurodegeneration.