Sound-Induced Motion of a Nanoscale Fiber

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
R. N. Miles ◽  
J. Zhou
Keyword(s):  
Particle Motion ◽  
Surrounding Medium ◽  
System Response ◽  
Acoustic Excitation ◽  
Mechanical Motion ◽  
Thin Fiber ◽  
Reasonable Approximation ◽  
Wide Range ◽  
Resonant Behavior ◽  
Induced Motion

An analysis is presented of the motion of a thin fiber, supported on each end, due to a sound wave that propagates in the direction perpendicular to its long axis. Predicted and measured results indicate that when fibers or hairs having a diameter measurably less than 1 μm are subjected to air-borne acoustic excitation, their motion can be a very reasonable approximation to that of the acoustic particle motion at frequencies spanning the audible range. For much of the audible range of frequencies resonant behavior due to reflections from the supports tends to be heavily damped so that the details of the boundary conditions do not play a significant role in determining the overall system response. Thin fibers are thus constrained to simply move with the surrounding medium. These results suggest that if the diameter or radius is chosen to be sufficiently small, incorporating a suitable transduction scheme to convert its mechanical motion into an electronic signal could lead to a sound sensor that very closely depicts the acoustic particle motion over a wide range of frequencies.

scholarly journals The effect of water immersion on vection in virtual reality

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Géraldine Fauville ◽  
Anna C. M. Queiroz ◽  
Erika S. Woolsey ◽  
Jonathan W. Kelly ◽  
Jeremy N. Bailenson
Keyword(s):  
Virtual Reality ◽  
Motion Sickness ◽  
Water Immersion ◽  
Sensory Information ◽  
Future Research ◽  
Visually Induced Motion Sickness ◽  
Wide Range ◽  
Induced Motion ◽  
Ground Condition ◽  
The Impact

AbstractResearch about vection (illusory self-motion) has investigated a wide range of sensory cues and employed various methods and equipment, including use of virtual reality (VR). However, there is currently no research in the field of vection on the impact of floating in water while experiencing VR. Aquatic immersion presents a new and interesting method to potentially enhance vection by reducing conflicting sensory information that is usually experienced when standing or sitting on a stable surface. This study compares vection, visually induced motion sickness, and presence among participants experiencing VR while standing on the ground or floating in water. Results show that vection was significantly enhanced for the participants in the Water condition, whose judgments of self-displacement were larger than those of participants in the Ground condition. No differences in visually induced motion sickness or presence were found between conditions. We discuss the implication of this new type of VR experience for the fields of VR and vection while also discussing future research questions that emerge from our findings.

Artificial Neural Network and the Taguchi Method Application for Robust Wheatstone Bridge Design

1994 ◽  
Author(s):  
Jung-eui Hong ◽  
Cihan H. Dagli ◽  
Kenneth M. Ragsdell
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Wheatstone Bridge ◽  
Parameter Design ◽  
System Response ◽  
Measurement Circuit ◽  
Wide Range ◽  
Reduce Measurement Error ◽  
On Line ◽  
Artificial Neural

Abstract The primary function of the Wheatstone bridge is to measure an unknown resistance. The elements of this well-known measurement circuit will take on different values depending upon the range and accuracy required for a particular application. The Taguchi approach to parameter design is used to select values for the measurement circuit elements so as to reduce measurement error. Next we introduce the use of an artificial neural network to extrapolate limited experimental results to predict system response over a wide range of applications. This approach can be employed for on-line quality control of the manufacture of such device.

Numerical simulation of ship propulsion transients and full-scale validation

2003 ◽  
Vol 217 (1) ◽  
pp. 41-52 ◽  
Author(s):  
U Campora ◽  
M Figari
Keyword(s):  
Full Scale ◽  
Operating Conditions ◽  
Dynamics Simulation ◽  
Normal Operation ◽  
System Response ◽  
Prime Mover ◽  
Software Environment ◽  
Simulation Code ◽  
Ship Propulsion ◽  
Wide Range

The paper describes a mathematical model for the dynamics simulation of ship propulsion systems. The model, developed in a MATLAB-SIMULINK software environment, is structured in modular form; the various elements of the system are described as individuals blocks (hull, prime mover, gear, waterjet, etc.) and linked together to take their interactions into account. In this way it is possible to characterize the dynamic behaviour of both the single component and the whole propulsion plant. The model may be used to analyse the system response at off-design and transient conditions. In particular, the developed computer simulation code may be considered as a useful tool to facilitate the correct matching of the prime mover (diesel or gas turbine) to the propulsor (waterjet or propeller) in a wide range of operating conditions. The paper shows the application of the methodology to a cruise ferry used to validate the model results through a full-scale test campaign conducted by the authors during normal operation of the ship.

scholarly journals Autonomic Nervous System Response during Light Physical Activity in Adolescents with Anorexia Nervosa Measured by Wearable Devices

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2820 ◽  
Author(s):  
Lucia Billeci ◽  
Alessandro Tonacci ◽  
Elena Brunori ◽  
Rossella Raso ◽  
Sara Calderoni ◽  
...  
Keyword(s):  
Physical Activity ◽  
Heart Rate ◽  
Nervous System ◽  
Anorexia Nervosa ◽  
Autonomic Nervous System ◽  
System Response ◽  
Light Physical Activity ◽  
Autonomic Nervous ◽  
Wide Range ◽  
Low Energy Availability

Anorexia nervosa (AN) is associated with a wide range of disturbances of the autonomic nervous system. The aim of the present study was to monitor the heart rate (HR) and the heart rate variability (HRV) during light physical activity in a group of adolescent girls with AN and in age-matched controls using a wearable, minimally obtrusive device. For the study, we enrolled a sample of 23 adolescents with AN and 17 controls. After performing a 12-lead electrocardiogram and echocardiography, we used a wearable device to record a one-lead electrocardiogram for 5 min at baseline for 5 min during light physical exercise (Task) and for 5 min during recovery. From the recording, we extracted HR and HRV indices. Among subjects with AN, the HR increased at task and decreased at recovery, whereas among controls it did not change between the test phases. HRV features showed a different trend between the two groups, with an increased low-to-high frequency ratio (LF/HF) in the AN group due to increased LF and decreased HF, differently from controls that, otherwise, slightly increased their standard deviation of NN intervals (SDNN) and the root mean square of successive differences (RMSSD). The response in the AN group during the task as compared to that of healthy adolescents suggests a possible sympathetic activation or parasympathetic withdrawal, differently from controls. This result could be related to the low energy availability associated to the excessive loss of fat and lean mass in subjects with AN, that could drive to autonomic imbalance even during light physical activity.

System Dynamic Modeling of Vapor Compression Cycles

2012 ◽  
Author(s):  
Eric S. Miller ◽  
Soumya S. Patnaik ◽  
Milind A. Jog
Keyword(s):  
Thermal Management ◽  
Dynamic Behavior ◽  
Lagrangian Method ◽  
System Response ◽  
Vapor Compression ◽  
Wide Range ◽  
Compression Cycle ◽  
Cycle Systems ◽  
Component Models ◽  
And Control

Vapor Compression cycle Systems (VCSs) are being considered for thermal management aboard modern aircraft where dynamic changes in heat loads are very common. Predicting dynamic behavior of VCSs is critical to design, sizing, and control of aircraft thermal management systems. A novel Lagrangian method to model the dynamic behavior of VCSs has been developed. This approach divides each fluid flow into a large number of elements having fixed mass, but variable volume and position. At discrete time steps, heat transferred to or from each mass element is determined by component models. This paper gives simulation results showing system startup under PID feedback control. Then, from steady state, the system response to an increase in heat load, an increase in sink availability, a decrease in valve throttle and an increase in compressor speed are simulated and the results reported. Results indicate that the Lagrangian method can provide results for a wide range of cases and that VCC systems require extensive control to meet performance objectives.

Compensator Design for a MEMS Gyroscope With Quadratic Optimal Control

2010 ◽  
Author(s):  
Wei Cui ◽  
Wei Xue ◽  
Xiaolin Chen
Keyword(s):  
Dynamic Range ◽  
Linear Quadratic Regulator ◽  
Control Algorithms ◽  
System Response ◽  
Linear Quadratic ◽  
Control Effort ◽  
Mems Gyroscope ◽  
Compensator Design ◽  
Wide Range ◽  
Parameter Perturbations

A number of control algorithms have been reported to adopt force balancing scheme into MEMS vibratory gyroscope systems. In practice, however, many algorithms are difficult to implement with electronic circuits. This paper designs and analyzes a lead compensator for a MEMS gyroscope via the Linear Quadratic Regulator (LQR) technique. LQR optimizes and balances the control effort and system response swiftness. Simulation shows the gyroscope achieves high linearity, wide dynamic range, and high robustness to fabrication uncertainties with this efficient compensator design. The closed-loop scale factor uniformity error is 0.7% under ±10% parameter perturbations. The compensator designed in this paper exhibits comparable outstanding performance compared to other reported control algorithms. The method reported in this paper is proved to be effective and can be used in a wide range of applications.

The Effect of Gravity and Rotor Configuration on Dry Friction Whip and Safe Rotor/Stator Clearance

2019 ◽  
Author(s):  
Rajiv Kumar Vashisht
Keyword(s):  
Mathematical Model ◽  
Fault Diagnosis ◽  
Dry Friction ◽  
Rotating Machinery ◽  
Degree Of Freedom ◽  
System Response ◽  
Rich Variety ◽  
Wide Range ◽  
Clearance Level ◽  
High Degree

Abstract A mathematical model is developed for a real rotor/stator system with high degrees-of-freedoms, multiple disks, flexible bearing supports and couplings. The safe clearance level for coasting up of the rotor is calculated for a general high degree-of-freedom rotor/stator system. The harmful phenomena of dry friction whip, which is generally observable for simple 2 degree-of-freedom Jeffcott rotors in the absence of gravity only, can be proved to exist (in real rotor/stator systems) even in the presence of gravity for a wide range of clearance levels. In case of Jeffcott rotors, by fixing the clearance and increasing the rotor spin frequency, the response of the system follows the pattern: No rub - Forward Annular Rub (FAR) - Partial Forward Whirl (PFW) - Partial Backward Whirl (PBW) - dry whip (WHIP). In case of a real rotor/stator system, at certain frequencies, the system directly jumps to dry whip. The simulated results show a rich variety of system dynamics including FAR, PFW and WHIP in case of vertical rotors where the effect of gravity is neglected. For horizontal rotors, under the effect of gravity, the system response contains multi-harmonics, chaotic responses and multi-period vibrations. Based on these responses, a robust fault diagnosis strategy can be designed to identify the rubbing action in rotating machinery.

Modeling Insect Filiform Hair Motion Using the Penalty Immersed Boundary Method

2007 ◽  
Author(s):  
Toma´sˇ Gedeon ◽  
Jeff J. Heys ◽  
B. C. Knott ◽  
Jonas Mulder-Rosi
Keyword(s):  
Immersed Boundary Method ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Wide Range ◽  
Fluid Environment ◽  
Induced Motion ◽  
Acheta Domestica ◽  
Model Equations ◽  
Surrounding Fluid ◽  
Filiform Hair

Many insects are able to sense their surrounding fluid environment through induced motion of their filiform hairs. The mechanism by which the insect can sense a wide range of input signals using the canopy of filiform hairs of different length and orientation is of great interest. Most of the previous filiform hair models have focused on a single, rigid hair in an idealized air field. We have developed [1] a model for a canopy of filiform hairs that are mechanically coupled to the surrounding air. The model equations are based on the penalty immersed boundary method. The key difference between the penalty immersed boundary method and the traditional immersed boundary method is the addition of forces to account for density differences between the immersed solid (the filiform hairs) and the surrounding fluid (air). In this work we validate the model by comparing the model predictions to experimental results on cricket Acheta domestica cercal system.

Hindcasting VIM-Induced Mooring Fatigue for the Genesis Spar

2004 ◽  
Author(s):  
David W. Smith ◽  
H. M. Thompson ◽  
T. Kokkinis ◽  
W. L. Greiner
Keyword(s):  
Eddy Current ◽  
High Amplitude ◽  
Mooring Line ◽  
System Response ◽  
Mooring System ◽  
Remaining Life ◽  
Original Design ◽  
Fatigue Design ◽  
Induced Motion ◽  
Wear Damage

A number of spars are being installed in deepwater areas in the Gulf of Mexico (GoM) which are subject to loop / eddy current conditions and require that their mooring system be designed for Vortex Induced Motion (VIM). This paper presents insights into fatigue and wear issues for mooring systems of spars subject to VIM, and illustrates the importance of reassessing industry practices for mooring strength and fatigue design for mooring systems that must resist VIM. During the GoM Millennium Eddy Current Event in April 2001, the ChevronTexaco Genesis spar platform, which is installed in Green Canyon Block 205 in the GoM, underwent VIM which was greater than anticipated during the original design of the mooring and riser systems. A key part of developing a permanent solution for ensuring integrity in future large VIM events was the assessment of fatigue and wear damage accumulated in past VIM events, for the purpose of ensuring fitness of the components of the mooring system for future service. The main elements of this assessment were: (a) The hindcast of the mooring line tensions from measured platform motions. (b) The evaluation of stress concentration on the mooring chain in the fairleads. (c) The assessment of fatigue damage for high amplitude/low cycle conditions, and (d) The assessment of accumulated wear. The results of this fatigue assessment led to a decision to replace the fairlead chain segments on 4 of the 14 mooring legs of Genesis, in order to ensure that they would have adequate fatigue endurance under the Stepped Line Tensioning (SLT) solution developed to mitigate the risk of VIM of the spar in the future. The project team’s unique understanding of mooring system response under VIM and resulting mooring component fatigue and wear issues led to the development of novel fatigue and wear hindcasting procedures that allowed the project to reliably assess the remaining life of the mooring components, and make decisions to selectively replace some of the components to ensure integrity for the remaining life of the platform under the SLT solution.

scholarly journals FaIRv2.0.0: a generalized impulse response model for climate uncertainty and future scenario exploration

2021 ◽  
Vol 14 (5) ◽  
pp. 3007-3036
Author(s):  
Nicholas J. Leach ◽  
Stuart Jenkins ◽  
Zebedee Nicholls ◽  
Christopher J. Smith ◽  
John Lynch ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Impulse Response ◽  
Climate Models ◽  
Global Climate ◽  
Climate System ◽  
System Response ◽  
Common Denominator ◽  
Response Model ◽  
Wide Range ◽  
Complex Models

Abstract. Here we present an update to the FaIR model for use in probabilistic future climate and scenario exploration, integrated assessment, policy analysis, and education. In this update we have focussed on identifying a minimum level of structural complexity in the model. The result is a set of six equations, five of which correspond to the standard impulse response model used for greenhouse gas (GHG) metric calculations in the IPCC's Fifth Assessment Report, plus one additional physically motivated equation to represent state-dependent feedbacks on the response timescales of each greenhouse gas cycle. This additional equation is necessary to reproduce non-linearities in the carbon cycle apparent in both Earth system models and observations. These six equations are transparent and sufficiently simple that the model is able to be ported into standard tabular data analysis packages, such as Excel, increasing the potential user base considerably. However, we demonstrate that the equations are flexible enough to be tuned to emulate the behaviour of several key processes within more complex models from CMIP6. The model is exceptionally quick to run, making it ideal for integrating large probabilistic ensembles. We apply a constraint based on the current estimates of the global warming trend to a million-member ensemble, using the constrained ensemble to make scenario-dependent projections and infer ranges for properties of the climate system. Through these analyses, we reaffirm that simple climate models (unlike more complex models) are not themselves intrinsically biased “hot” or “cold”: it is the choice of parameters and how those are selected that determines the model response, something that appears to have been misunderstood in the past. This updated FaIR model is able to reproduce the global climate system response to GHG and aerosol emissions with sufficient accuracy to be useful in a wide range of applications and therefore could be used as a lowest-common-denominator model to provide consistency in different contexts. The fact that FaIR can be written down in just six equations greatly aids transparency in such contexts.

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