A new approch for measuring ocean vertical velocities

Compared to horizontal components, the vertical components of ocean currents are generally very weak (a few mm/s) in all oceanic regions of the world. Due to their major role in the vertical distribution of physical and biogeochemical properties of sea water, their extended knowledge is of utmost importance for oceanographers. However, their in-situ measurement represents a real technical challenge, even using sophisticated instruments such as ADCPs.As a complement to the ADCP method presented in another session (Comby et al.), we have developed an original alternative instrument, called the VVP (Vertical Velocity Profiler). It was inspired by several published works which exploit the difference between the real vertical speed Wr of a submarine glider (~dP/dt, from the onboard pressure sensor) and its theoretical vertical speed Wth extracted from a flight model. The oceanic vertical speed Woc is thus expressed by the simple difference Woc = Wr - Wth at any&#160; point in the water column.The very first prototype of the VVP consisted of a float and a friction disc, ballasted to sink at a very low speed (~ 0.1 m / s) and dragged down to the desired depth by a dead-weight which was automatically released after a suitable delay. The release system was developped in-house (patent filled in March 2020), based on a textured insert trapped in a volume of ice melting at controlled speed. Since then, the concept of the profiler has evolved considerably. The last design uses an electric thruster that drives the profiler down to a predefined setpoint depth. Once the depth is reached, the thruster is stopped and the profiler then rises slowly (~0.1 m/s) to the surface under the sole effect of its slightly positive buoyancy. The mechanical balance between buoyancy and hydrodynamic drag results in a constant vertical speed of ascent in water at rest. Any deviation from this constant speed is then interpreted as an oceanic&#160; vertical velocity signal. This new design allows a very large number of consecutive profiles to be collected, the number of descent-ascent cycles and the setpoint depth being programmed and controlled using an ARDUINO microcontroller board. The selected Li-Io battery allows for several hours of continuous profiling.&#160; When on surface, the profiler is currently located by a commercial GPS tracker integrated into the electronic case. The vertical velocity of the profiler is accurately measured at&#160; high frequency (2Hz) thanks to the fast-response pressure sensor of the onboard RBR-CONCERTO autonomous CTD, which also measures the sea water density involved in&#160; drag and buoyancy.Trials both in deep pool and in the field are scheduled in spring 2021 in order to refine the prototype design and to definitely set the flight model parameters. This development benefits from CNES (Centre National d'Etudes Spatiales) financial support in the framework of the BIOSWOT international program.

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Alcohol-based highly conductive polymer for conformal nanocoatings on hydrophobic surfaces toward a highly sensitive and stable pressure sensor

NPG Asia Materials ◽

10.1038/s41427-020-00238-z ◽

2020 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Jung Joon Lee ◽

Srinivas Gandla ◽

Byeongjae Lim ◽

Sunju Kang ◽

Sunyoung Kim ◽

...

Keyword(s):

Pressure Sensor ◽

Mechanical Stability ◽

Exchange Process ◽

Conductive Polymer ◽

High Sensitivity ◽

Fast Response ◽

Pdms Surface ◽

Practical Applications ◽

Sensor Applications ◽

Water Based

Abstract Conformal and ultrathin coating of highly conductive PEDOT:PSS on hydrophobic uneven surfaces is essential for resistive-based pressure sensor applications. For this purpose, a water-based poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) solution was successfully exchanged to an organic solvent-based PEDOT:PSS solution without any aggregation or reduction in conductivity using the ultrafiltration method. Among various solvents, the ethanol (EtOH) solvent-exchanged PEDOT:PSS solution exhibited a contact angle of 34.67°, which is much lower than the value of 96.94° for the water-based PEDOT:PSS solution. The optimized EtOH-based PEDOT:PSS solution exhibited conformal and uniform coating, with ultrathin nanocoated films obtained on a hydrophobic pyramid polydimethylsiloxane (PDMS) surface. The fabricated pressure sensor showed high performances, such as high sensitivity (−21 kPa−1 in the low pressure regime up to 100 Pa), mechanical stability (over 10,000 cycles without any failure or cracks) and a fast response time (90 ms). Finally, the proposed pressure sensor was successfully demonstrated as a human blood pulse rate sensor and a spatial pressure sensor array for practical applications. The solvent exchange process using ultrafiltration for these applications can be utilized as a universal technique for improving the coating property (wettability) of conducting polymers as well as various other materials.

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First Unsteady Pressure Measurements With a Fast Response Cooled Total Pressure Probe in High Temperature Gas Turbine Environments

Volume 3: Controls, Diagnostics and Instrumentation; Cycle Innovations; Marine ◽

10.1115/gt2010-23630 ◽

2010 ◽

Cited By ~ 2

Author(s):

Mehmet Mersinligil ◽

Jean-Franc¸ois Brouckaert ◽

Julien Desset

Keyword(s):

High Pressure ◽

Pressure Sensor ◽

Total Pressure ◽

Fast Response ◽

Design Stage ◽

Absolute Pressure ◽

Pressure Probe ◽

Probe Design ◽

Flame Tube ◽

Blade Passing Frequency

This paper presents the first experimental engine and test rig results obtained from a fast response cooled total pressure probe. The first objective of the probe design was to favor continuous immersion of the probe into the engine to obtain time series of pressure with a high bandwidth and therefore statistically representative average fluctuations at the blade passing frequency. The probe is water cooled by a high pressure cooling system and uses a conventional piezo-resistive pressure sensor which yields therefore both time-averaged and time-resolved pressures. The initial design target was to gain the capability of performing measurements at the temperature conditions typically found at high pressure turbine exit (1100–1400K) with a bandwidth of at least 40kHz and in the long term at combustor exit (2000K or higher). The probe was first traversed at the turbine exit of a Rolls-Royce Viper turbojet engine, at exhaust temperatures around 750 °C and absolute pressure of 2.1bars. The probe was able to resolve the high blade passing frequency (≈23kHz) and several harmonics up to 100kHz. Besides the average total pressure distributions from the radial traverses, phase-locked averages and random unsteadiness are presented. The probe was also used in a virtual three-hole mode yielding unsteady yaw angle, static pressure and Mach number. The same probe was used for measurements in a Rolls-Royce intermediate pressure burner rig. Traverses were performed inside the flame tube of a kerosene burner at temperatures above 1600 °C. The probe successfully measured the total pressure distribution in the flame tube and typical frequencies of combustion instabilities were identified during rumble conditions. The cooling performance of the probe is compared to estimations at the design stage and found to be in good agreement. The frequency response of the probe is compared to cold shock tube results and a significant increase in the natural frequency of the line-cavity system formed by the conduction cooled screen in front of the miniature pressure sensor were observed.

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Single-Layer Pressure Textile Sensors with Woven Conductive Yarn Circuit

Applied Sciences ◽

10.3390/app10082877 ◽

2020 ◽

Vol 10 (8) ◽

pp. 2877 ◽

Cited By ~ 2

Author(s):

Gaeul Kim ◽

Chi Cuong Vu ◽

Jooyong Kim

Keyword(s):

Pressure Sensor ◽

Pressure Sensors ◽

Single Layer ◽

Fast Response ◽

Resistance Change ◽

Load Pressure ◽

Pressure Sensitive ◽

High Durability ◽

Textile Sensors ◽

Conductive Fibers

Today, e-textiles have become a fundamental trend in wearable devices. Fabric pressure sensors, as a part of e-textiles, have also received much interest from many researchers all over the world. However, most of the pressure sensors are made of electronic fibers and composed of many layers, including an intermediate layer for sensing the pressure. This paper proposes the model of a single layer pressure sensor with electrodes and conductive fibers intertwined. The plan dimensions of the fabricated sensors are 14 x 14 mm, and the thickness is 0.4 mm. The whole area of the sensor is the pressure-sensitive point. As expected, results demonstrate an electrical resistance change from 283 Ω at the unload pressure to 158 Ω at the load pressure. Besides, sensors have a fast response time (50 ms) and small hysteresis (5.5%). The hysteresis will increase according to the pressure and loading distance, but the change of sensor loading distance is very small. Moreover, the single-layer pressure sensors also show high durability under many working cycles (20,000 cycles) or washing times (50 times). The single-layer pressure sensor is very thin and more flexible than the multi-layer pressure sensor. The structure of this sensor is also expected to bring great benefits to wearable technology in the future.

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A Real Time Controlled Test Rig for High Bandwidth Force Control

8th FPNI Ph.D Symposium on Fluid Power ◽

10.1115/fpni2014-7813 ◽

2014 ◽

Author(s):

Alessandro Bertucci ◽

Andrea Mornacchi ◽

Giovanni Jacazio ◽

Massimo Sorli

Keyword(s):

Real Time ◽

Force Control ◽

Medium Size ◽

Feedback Signal ◽

Model Parameters ◽

Hydraulic Actuator ◽

Critical Feature ◽

Velocity Signal ◽

Stability Margins ◽

High Bandwidth

This paper describes an electronically controlled active force control system developed to test the tail rotor actuator of a new medium size helicopter. As for all hydraulic force control systems, the critical control issue is to mitigate the disturbance generated by the actuator velocity. For this particular case, the problem was accrued by the high bandwidth of the tail rotor actuator. To define the optimum control algorithm a model based approach was followed, estimating, when unable to measure directly, mechanical and hydraulic model parameters with a dedicated experimental campaign. A controller was eventually developed able to cope with the severe dynamic disturbances by introducing velocity and acceleration compensation laws. The controller was then implemented in a high recursion rate real time machine interfacing with a servovalve controlling the flow to a hydraulic actuator provided with hydrostatic bearings to minimize the friction force. The actuator force was sensed by a load cell providing the feedback signal for the force servoloop. A critical feature of the control was the need to develop a dedicated complex filter for the velocity signal able to cancel out the signal noise while allowing to retain the correct real time information of the actuator velocity and maintain adequate stability margins.

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Locally Controlled Sensing Properties of Stretchable Pressure Sensors Enabled by Micro-Patterned Piezoresistive Device Architecture

Sensors ◽

10.3390/s20226588 ◽

2020 ◽

Vol 20 (22) ◽

pp. 6588

Author(s):

Jun Ho Lee ◽

Jae Sang Heo ◽

Keon Woo Lee ◽

Jae Cheol Shin ◽

Jeong-Wan Jo ◽

...

Keyword(s):

Pressure Sensor ◽

Silver Nanowires ◽

Pressure Sensors ◽

High Sensitivity ◽

Fast Response ◽

Large Area ◽

Site Specific ◽

Sensing Properties ◽

Sensing Range ◽

Wide Range

For wearable health monitoring systems and soft robotics, stretchable/flexible pressure sensors have continuously drawn attention owing to a wide range of potential applications such as the detection of human physiological and activity signals, and electronic skin (e-skin). Here, we demonstrated a highly stretchable pressure sensor using silver nanowires (AgNWs) and photo-patternable polyurethane acrylate (PUA). In particular, the characteristics of the pressure sensors could be moderately controlled through a micro-patterned hole structure in the PUA spacer and size-designs of the patterned hole area. With the structural-tuning strategies, adequate control of the site-specific sensitivity in the range of 47~83 kPa−1 and in the sensing range from 0.1 to 20 kPa was achieved. Moreover, stacked AgNW/PUA/AgNW (APA) structural designed pressure sensors with mixed hole sizes of 10/200 µm and spacer thickness of 800 µm exhibited high sensitivity (~171.5 kPa−1) in the pressure sensing range of 0~20 kPa, fast response (100~110 ms), and high stretchability (40%). From the results, we envision that the effective structural-tuning strategy capable of controlling the sensing properties of the APA pressure sensor would be employed in a large-area stretchable pressure sensor system, which needs site-specific sensing properties, providing monolithic implementation by simply arranging appropriate micro-patterned hole architectures.

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High-sensitivity, fast-response flexible pressure sensor for electronic skin using direct writing printing

RSC Advances ◽

10.1039/d0ra04431h ◽

2020 ◽

Vol 10 (44) ◽

pp. 26188-26196 ◽

Cited By ~ 2

Author(s):

Xiaojun Chen ◽

Xitong Lin ◽

Deyun Mo ◽

Xiaoqun Xia ◽

Manfeng Gong ◽

...

Keyword(s):

Human Computer Interaction ◽

Pressure Sensor ◽

High Sensitivity ◽

Fast Response ◽

Wearable Electronics ◽

Direct Writing ◽

Electronic Skin ◽

Medical Health ◽

Flexible Pressure Sensor ◽

Health Diagnosis

Bionic electronic skin with human sensory capabilities has attracted extensive research interest, which has been applied in the fields of medical health diagnosis, wearable electronics, human–computer interaction, and bionic prosthetics.

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A Kinematic/Kinetic Hybrid Airplane Simulator Model

Volume 1: Advances in Aerospace Technology ◽

10.1115/imece2008-66430 ◽

2008 ◽

Cited By ~ 1

Author(s):

Gerard T. Fairley ◽

Seamus McGovern

Keyword(s):

Hybrid Model ◽

Vertical Velocity ◽

Vertical Acceleration ◽

Text Data ◽

Program Complexity ◽

Aircraft Performance ◽

Flight Regimes ◽

High Level ◽

Flight Model ◽

Aircraft Data

A kinematics-based flight model, for normal flight regimes, currently uses precise flight data to achieve a high level of aircraft realism. However, it was desired to further increase the model’s accuracy, without a substantial increase in program complexity, by determining the vertical velocity and vertical acceleration using EUROCONTROL’s Base of Aircraft DAta (BADA) model [1]. BADA is a well-known aircraft performance database model maintained and developed by EUROCONTROL Experimental Centre in France. The hybrid model uses the BADA algorithm to determine the vertical velocity and gives original results for determining the vertical acceleration. The approximate accuracy of these vertical parameters was checked by comparing them with preexisting test distributions [2] and an in-house flight simulator application. The hybrid model uses kinematic algorithms for all other functions and parameters. To obtain specific results, C code was written to access text data from BADA’s collection of approximately one hundred airplanes. Accessing this database causes an increase in overall program execution time that was deemed acceptable due to the infrequency of changing plane types. Also, by examining many airplane trajectories obtained from different BADA airplanes, we determined that the model is accurate enough to uniquely represent many different types of aircraft.

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Image gathers of SV-waves in homogeneous and factorized VTI media

Geophysics ◽

10.1190/1.2052468 ◽

2005 ◽

Vol 70 (5) ◽

pp. D55-D64 ◽

Cited By ~ 1

Author(s):

Ramzy M. Al-Zayer ◽

Ilya Tsvankin

Keyword(s):

Shear Wave ◽

Vertical Velocity ◽

Migration Velocity ◽

P Wave ◽

Model Parameters ◽

Velocity Analysis ◽

Wave Data ◽

Migration Velocity Analysis ◽

Wave Migration ◽

Vti Media

Reflection moveout of SV-waves in transversely isotropic media with a vertical symmetry axis (VTI media) can provide valuable information about the model parameters and help to overcome the ambiguities in the inversion of P-wave data. Here, to develop a foundation for shear-wave migration velocity analysis, we study SV-wave image gathers obtained after prestack depth migration. The key issue, addressed using both approximate analytic results and Kirchhoff migration of synthetic data, is whether long-spread SV data can constrain the shear-wave vertical velocity [Formula: see text] and the depth scale of VTI models. For homogeneous media, the residual moveout of horizontal SV events on image gathers is close to hyperbolic and depends just on the NMO velocity [Formula: see text] out to offset-to-depth ratios of about 1.7. Because [Formula: see text] differs from [Formula: see text], flattening moderate-spread gathers of SV-waves does not ensure the correct depth of the migrated events. The residual moveout rapidly becomes nonhyperbolic as the offset-to-depth ratio approaches two, with the migrated depths at long offsets strongly influenced by the SV-wave anisotropy parameter σ. Although the combination of [Formula: see text] and σ is sufficient to constrain the vertical velocity [Formula: see text] and reflector depth, the tradeoff between σ and the Thomsen parameter ε on long-spread gathers causes errors in time-to-depth conversion. The residual moveout of dipping SV events is also controlled by the parameters [Formula: see text], σ, and ε, but in the presence of dip, the contributions of both σ and ε are significant even at small offsets. For factorized v(z) VTI media with a constant SV-wave vertical-velocity gradient [Formula: see text], flattening of horizontal events for a range of depths requires the correct NMO velocity at the surface, the gradient [Formula: see text], and, for long offsets, the parameters σ and ε. On the whole, the nonnegligible uncertainty in the estimation of reflector depth from SV-wave moveout highlights the need to combine P- and SV-wave data in migration velocity analysis for VTI media.

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Ultrahigh Sensitivity Micro-cliff Graphene Wearable Pressure Sensor Made by Instant Flash Light Exposure

Nanoscale ◽

10.1039/d1nr04333a ◽

2021 ◽

Author(s):

Yachu Zhang ◽

Han Lin ◽

Fei Meng ◽

Huai Liu ◽

David Mesa ◽

...

Keyword(s):

Health Monitoring ◽

Pressure Sensor ◽

Biomedical Applications ◽

Light Exposure ◽

Pressure Sensors ◽

High Sensitivity ◽

Fast Response ◽

Highly Sensitive ◽

Ultrahigh Sensitivity ◽

Sensitive Pressure

Wearable and highly sensitive pressure sensors are of great importance for robotics, health monitoring and biomedical applications. Simultaneously achieving high sensitivity within a broad working range, fast response time (within...

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