Search results for "Mechanical systems"
showing 10 items of 45 documents
Sprint mechanics evaluation using inertial sensor-based technology: A laboratory validation study.
2018
Advances in micro-electromechanical systems have turned magnetic inertial measurement units (MIMUs) into a suitable tool for vertical jumping biomechanical evaluation. Thus, this study aimed to determine whether appropriate reliability and agreement reports could also be obtained when analyzing 20-m sprint mechanics. Four bouts of 20-m sprints were evaluated to determine whether the data provided by a MIMU placed at the lumbar spine could reliably assess sprint mechanics and to examine the validity of the MIMU sensor compared to force plate recordings. Maximal power (P0), force (F0), and velocity (V0), as well as other mechanical determinants of sprint performance associated with the force-…
Practical strategies for stable operation of HFF-QCM in continuous air flow
2013
Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to…
Entanglement control in hybrid optomechanical systems
2012
We demonstrate the control of entanglement in a hybrid optomechanical system comprising an optical cavity with a mechanical end-mirror and an intracavity Bose-Einstein condensate (BEC). Pulsed laser light (tuned within realistic experimental conditions) is shown to induce an almost sixfold increase of the atom-mirror entanglement and to be responsible for interesting dynamics between such mesoscopic systems. In order to assess the advantages offered by the proposed control technique, we compare the time-dependent dynamics of the system under constant pumping with the evolution due to the modulated laser light.
Power Consumption Analysis of Operating Systems for Wireless Sensor Networks
2010
In this paper four wireless sensor network operating systems are compared in terms of power consumption. The analysis takes into account the most common operating systems-TinyOS v1.0, TinyOS v2.0, Mantis and Contiki-running on Tmote Sky and MICAz devices. With the objective of ensuring a fair evaluation, a benchmark composed of four applications has been developed, covering the most typical tasks that a Wireless Sensor Network performs. The results show the instant and average current consumption of the devices during the execution of these applications. The experimental measurements provide a good insight into the power mode in which the device components are running at every moment, and t…
On Leonov’s method for computing the linearization of the transverse dynamics and analysis of Zhukovsky stability
2019
The paper focuses on a comprehensive discussion of G. A. Leonov’s results aimed at analyzing the Zhukovsky stability of a solution to a nonlinear autonomous system by linearization. The main contribution is deriving the linear system that approximates dynamics of the original nonlinear systems transverse to the vector-flow on a nominal behavior. As illustrated, such a linear comparison system becomes instrumental in the analysis and re-design of classical feedback controllers developed previously for the stabilization of motions of nonlinear mechanical systems.
Microfabrication of hybrid fluid membrane for microengines
2015
International audience; This paper describes the microfabrication and dynamic characterization of thick membranes providing a technological solution for microengines. The studied membranes are called hybrid fluid-membrane (HFM) and consist of two thin membranes that encapsulate an incompressible fluid. This work details the microelectromechanical system (MEMS) scalable fabrication and characterization of HFMs. The membranes are composite structures based on Silicon spiral springs embedded in a polymer (RTV silicone). The anodic bonding of multiple stacks of Si/glass structures, the fluid filling and the sealing have been demonstrated. Various HFMs were successfully fabricated and their dyna…
Tunable Strong Coupling of Mechanical Resonance between Spatially Separated FePS3 Nanodrums
2021
Coupled nanomechanical resonators made of two-dimensional materials are promising for processing information with mechanical modes. However, the challenge for these types of systems is to control the coupling. Here, we demonstrate strong coupling of motion between two suspended membranes of the magnetic 2D material FePS$_3$. We describe a tunable electromechanical mechanism for control over both the resonance frequency and the coupling strength using a gate voltage electrode under each membrane. We show that the coupling can be utilized for transferring data from one drum to the other by amplitude modulation. Finally, we also study the temperature dependence of the coupling, and in particul…
A LiDAR Prototype with Silicon Photomultiplier and MEMS Mirrors
2018
In this paper, we present a low cost prototype of a Time-Of-Flight (TOF) LiDAR system, employing a SiPM as photo detector and MEMS mirrors in order to steer the nanosecond pulsed optical beam with a scanning angle of +/-6°. Preliminary TOF measurements have been performed both indoor and outdoor to test the limits of the system.
Low-frequency band gap in cross-like holey phononic crystal strip
2018
International audience; A silicon-based cross-like holey phononic crystal (PnC) strip is proposed for the control of elastic waves in the field of micro-electro-mechanical systems (MEMS). The goal is to obtain a broad bandgap at low frequencies with a lightweight structure. In this respect, the effects of varying the in-plane and the out-of-plane geometry parameters are discussed. After design, a gap-to-midgap ratio of 47% is obtained with an intermediate filling fraction of the solid material and a small thickness of the strip. The band gap can be moved to an extremely low frequency range while keeping the strip significantly smaller than previously reported PnC strips. The transmission pr…
Dynamics of human cancer cell lines monitored by electrical and acoustic fluctuation analysis.
2010
Early determination of the metastatic potential of cancer cells is a crucial step for successful oncological treatment. Besides the remarkable progress in molecular genomics- or proteomics-based diagnostics, there is a great demand for in vitro biosensor devices that allow rapid and selective detection of the invasive properties of tumor cells. Here, the classical cancer cell motility in vitro assays for migration and invasion relying on Boyden chambers are compared to a real-time biosensor that analyzes the dynamic properties of adherent cells electro-acoustically with a time resolution on the order of seconds. The sensor relies on the well-established quartz crystal microbalance technique…