비만아 부모의 돌봄 경험: q 방법론

Annual review of condensed matter physics

Dynamics of Phononic Materials and Structures: Historical Origins, Recent Progress, and Future Outlook

Climate phenomena and their relevance for future regional climate change

The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority was given to completeness of coverage, but a limited, uniform set of attributes is attached to each of the � 198 000 glaciers in its latest version, 3.2. Satellite imagery from 1999-2010 provided most of the outlines. Their total extent is estimated as 726 800 � 34 000 km 2 . The uncertainty, about � 5%, is derived from careful single-glacier and basin-scale uncertainty estimates and comparisons with inventories that were not sources for the RGI. The main contributors to uncertainty are probably misinterpretation of seasonal snow cover and debris cover. These errors appear not to be normally distributed, and quantifying them reliably is an unsolved problem. Combined with digital elevation models, the RGI glacier outlines yield hypsometries that can be com- bined with atmospheric data or model outputs for analysis of the impacts of climatic change on glaciers. The RGI has already proved its value in the generation of significantly improved aggregate estimates of glacier mass changes and total volume, and thus actual and potential contributions to sea-level rise.

https://www.eoas.ubc.ca/~vradic/Pfeffer_et_al2014.pdf

The Randolph Glacier inventory: a globally complete inventory of glaciers

The capacity of different auto-supplied devices using shunted piezoelectric circuits are studied here to improve structural damping by avoiding implementation of complex and heavy control devices. The presented technique uses a dedicated numerical piezo-mechanical model combining both mechanical and electrical coupling parameters. An original methodology are also introduced for optimizing the parameters of electrical shunt circuits connected to piezoelectric elements and also structural locations of these integrated transducers. The results, experimentally validated (on beams and a plate), demonstrate that vibrations can be significantly reduced when shunted piezoelectric devices are mounted on a real structure. Finally, the proposed methodology is used for optimizing shape and location of the shunted piezoelectric patches to damp several modes of a plate.

/pdf/structural-multi-modal-damping-by-optimizing-shunted-4puvs8peyc.pdf

Structural multi-modal damping by optimizing shunted piezoelectric transducers

The control of vibrating structures using piezoelectric elements attached to simple control circuits, known as shunts, is a widely studied field. Many different shunt circuits have been researched that have been shown to obtain effective performance in both narrow and broadband frequency ranges. Yet, the choice for the exact parameters of the circuit elements for these vibration-suppressing shunts can be found by various methods. In this study, a new method of selecting the circuit parameters of a negative capacitance shunt is presented. The method predicts the magnitude of the strain-induced voltage caused by the vibrating substrate computed from a single voltage measurement. Therefore, minimizing the strain-induced voltage will mean that the deflection of the structure is also minimized. The tuning theory is confirmed experimentally, which validates that it is possible to experimentally obtain the shunt parameters that produce maximum control through measurement of the shunt response. The suppression ab...

Response-based tuning of a negative capacitance shunt for vibration control:

New miniaturization and integration capabilities available from emerging microelectromechanical system (MEMS) technology will allow silicon-based artificial skins involving thousands of elementary actuators to be developed in the near future. Smart structures combining large arrays of elementary motion pixels are thus being studied so that fundamental properties could be dynamically adjusted. This paper investigates the acoustical capabilities of a network of distributed transducers connected with a suitable controlling strategy. The research aims at designing an integrated active interface for sound attenuation by using suitable changes of acoustical impedance. The control strategy is based on partial differential equations (PDE) and the multiscaled physics of electromechanical elements. Specific techniques based on PDE control theory have provided a simple boundary control equation able to annihilate the reflections of acoustic waves. To experimentally implement the method, the control strategy is discretized as a first order time–space operator. The obtained quasi-collocated architecture, composed of a large number of sensors and actuators, provides high robustness and stability. The experimental results demonstrate how a well controlled active skin can substantially modify sound reflectivity of the acoustical interface and reduce the propagation of acoustic waves.

Experimental implementation of acoustic impedance control by a 2D network of distributed smart cells

Modal filter concept is introduced for structural vibration analysis and control. The modal filter is a means to extract the modal coordinates of each mode from the system outputs by mapping the response vector from the physical space to the modal space. This concept was used originally to deal with the spill-over problem in the control of a continuous system. We have chosen to optimize some semi-distributed piezo-electric layers by minimizing the influence of unwanted modes on the sensors and actuators. Confirmation of our computation was obtained by an experimental set-up of optimal active modal control on a thin composite plate. Thus, experimental optimal control in the independent modal space of this plate has been possible without any effect of spill-over. The efficiency and the robustness of this procedure was demonstrated by our experimental analysis.

Active modal control with piezo-electric layers optimization

In this paper, novel harvesting systems are proposed and studied to obtain enhanced energy from transient waves. Each of these systems contains a piezo-lens to focus waves and a harvester to yield energy from the induced focused waves. The piezo-lens comprises a host plate and piezoelectric patches bonded on the plate surfaces. The piezoelectric patches are shunted with negative capacitance (NC) circuits in order to control the spatial variation of the effective refractive index inside the piezo-lens domain. The harvester is placed at the designed focal point of the piezo-lens, two different synchronized switch harvesting on inductor (SSHI) based harvesters are analyzed in the studies. Corrected reduced models are developed to predict the transient responses of the harvesting systems. The performances of the systems incorporating SSHI-based harvesters in transient wave energy harvesting are studied and compared with the system using a standard DC harvester. The focusing effect of the piezo-lens on transient waves and its capability to improve the harvested energy are verified. Since the NC circuits are active elements, an energy balance analysis is performed. Applicability of the harvesting systems is also discussed.

Manuel Collet

Papers

Structural multi-modal damping by optimizing shunted piezoelectric transducers

Response-based tuning of a negative capacitance shunt for vibration control:

Experimental implementation of acoustic impedance control by a 2D network of distributed smart cells

Active modal control with piezo-electric layers optimization

Smart metacomposite-based systems for transient elastic wave energy harvesting