scholarly journals A Multisensor System for the Characterization of the Field Pressure in Terrain. Accuracy, Response, and Adjustments

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3942
Author(s):  
Isabel Sicilia ◽  
Sofía Aparicio ◽  
Borja Frutos ◽  
Eduardo Muñoz ◽  
Margarita González ◽  
...  
Keyword(s):  
Concrete Slab ◽  
Pressure Sensors ◽  
Temporal Response ◽  
Generator System ◽  
Multisensor System ◽  
Motion System ◽  
Transport Studies ◽  
Real Model ◽  
In Series ◽  
Physical Phenomena

In different disciplines of science, the knowledge of the resulting pressures in the subsoil can help to understand physical phenomena of mass exchange between the atmosphere and the terrain. The measurement of lower differential pressures is complicated given the low range of detected values. In this paper, a multisensor system has been designed and developed to measure differential pressures in radon gas transport studies. The adequacy of this system has been proven using a purpose-built pressure chamber and an automatic motion system developed by the authors. The temporal response frequencies, the pressure values measured by the sensors, and their ability to link in series were analyzed to offer a multisensor spatial and temporal mapping. At the same time, the influence of the components required for a real deployment were studied using different tube lengths and diameters, connectors, and obstructions across the operating range of the pressure sensors. The system has also been tested for measuring differential pressures in a real model with a concrete slab above the soil and a pressure generator system below. It was found that this system is very suitable for outdoor measurements that demand a quick temporal response and accuracy.

Micromachined Snap-In Resonators

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 001920-001935 ◽  
Author(s):  
Colin Stevens ◽  
Robert Dean ◽  
Chris Wilson
Keyword(s):  
Resonant Frequency ◽  
Proof Mass ◽  
Pressure Sensors ◽  
Mass System ◽  
Dc Voltage ◽  
Movable Electrode ◽  
Mems Resonators ◽  
Spring Force ◽  
In Series ◽  
Fixed Electrode

MEMS resonators have many applications, including micromachined gyroscopes, resonating pressure sensors and RF devices. Typically, MEMS resonators consist of a proof mass and suspension system that allows the proof mass motion in one or two directions. Micromachined actuators provide kinetic energy to the proof mass, usually at its resonant frequency. In the simplest resonators, the actuators are driven with an AC signal at or near the resonant frequency. In more complex resonators, the actuator-proof mass system is placed in an amplifier feedback circuit so that the electromechanical system self-resonates. MEMS parallel plate actuators (PPAs) are simple to realize, yet complex nonlinear variable capacitors. If a DC voltage is applied in attempt to move the proof mass greater than 1/3 of the electrode rest gap distance, the device becomes unstable and the electrodes snap into contact. A current limiting resistor is often placed in series with the PPA to limit short circuit current due to a snap-in event. Consider the effect of placing a large resistor, on the order on 10 meg-Ohms, in series with the PPA. Then apply a DC voltage across the resistor-PPA pair of sufficient voltage to cause snap-in. Once the electrostatic force (ES) exceeds the spring force (SF), the electrodes will accelerate toward each other. The capacitance between the electrodes swells as the separation distance shrinks. Since the large resistor limits the charging rate of the capacitor, the voltage across it drops. Once the SF exceeds the EF, the momentum of the movable electrode brings it into contact with the fixed electrode, discharging the capacitor. The movable electrode then accelerates away from the fixed electrode while the resistor slowly allows recharging. After recharging, the cycle repeats resulting in stable oscillation. This resonator requires only a DC power supply, a resistor and a MEMS PPA.

scholarly journals Velocity Distribution Characteristics Of Sea Water In Conductiv Magnetohydrodynamic (MHD) Homopolar Ducts

2015 ◽  
Vol 21 (3) ◽  
pp. 679-687
Author(s):  
Vasile Dobref ◽  
Petrică Popov ◽  
Silvestru Grozeanu
Keyword(s):  
Sea Water ◽  
Flow Characteristics ◽  
Modern Technology ◽  
Optimum Shape ◽  
Channel Axis ◽  
Electrically Conductive ◽  
Marine Propulsion ◽  
In Series ◽  
Physical Phenomena ◽  
Experimental And Theoretical Studies

Abstract Shortcomings of conventional propeller propulsion can theoretically be removed by using a modern technology - unconventional hydroelectromagnetic propeller or magnetohydrodynamic (MHD thruster), that highlights an application of great interest about physical phenomena that occur in the interaction between electromagnetic fields and electrically conductive fluids. In application to marine propulsion, investigations of a variety of physical phenomena was carried out, including the flow characteristics in a MHD duct, thrust efficiency and optimum shape of the duct. This paper presents related interaction phenomena between a magnetic induction, created by a d.c. electromagnet and d.c. current, perpendicular to the field, imposed by a voltage difference between two electrodes in the conductive sea water. The fluid is forced to the direction perpendicular to the plane where magnetic and electric fluxes are intersecting, this force is called the Lorentz force. Experimental and theoretical studies were carried out on small magnetohydrodynamic model (DC homopolar model) having two channels arranged in series or parallel. Each time the speed distribution was followed over the channel axis and perpendicular to channel axis.

Development of Optimal Control Strategy for a Plug-In Series Hybrid Electric Vehicle With an On-Board Engine-Generator System for Overall Fuel Economy Improvement and Reduction in Tail-Pipe Emissions

2017 ◽  
Author(s):  
Aman V. Kalia ◽  
Brian C. Fabien
Keyword(s):  
Fuel Economy ◽  
Hybrid Electric Vehicle ◽  
Control Algorithms ◽  
Optimal Control Strategy ◽  
Generator System ◽  
Tail Pipe ◽  
Series Hybrid Electric Vehicle ◽  
In Series ◽  
Fuel Economy Improvement ◽  
Hybrid Electric

This research study focuses on determining optimal points of operation for the engine-generator system and regenerative braking at the wheels in a plug-in series hybrid electric Chevrolet Camaro. The goal is to improve overall fuel economy of the vehicle as well as reducing overall tail-pipe emissions. An abstract mathematical model of the series hybrid electric Chevrolet Camaro is being used to simulate the overall energy consumption of the vehicle. Previously tested and published control algorithms and strategies are studied, discussed and a viable scheme is chosen for optimization. The results from the optimal strategy considered are compared against the unoptimized results. An improvement of ∼ 8.9% in fuel economy and ∼ 8.2% reduction in tail-pipe emissions is estimated.

Proposal of a Conceptual Model as Tool for the Hydraulic Design of Vegetated Roof

2014 ◽  
Vol 641-642 ◽  
pp. 326-331 ◽  
Author(s):  
Marco Carbone ◽  
Francesca Principato ◽  
Gennaro Nigro ◽  
Patrizia Piro
Keyword(s):  
Conceptual Model ◽  
Quantitative Information ◽  
Full Scale ◽  
Urban Drainage ◽  
Hydraulic Behavior ◽  
Good Ability ◽  
Vegetated Roofs ◽  
Vegetated Roof ◽  
In Series ◽  
Physical Phenomena

Vegetated roof technique is becoming increasingly popular, particularly in highly urbanized areas, among the Sustainable Urban Drainage Systems (SUDS) for urban stormwater management. Several studies [1,2] have shown that vegetated roofs may significantly reducing the runoff volume and hydrograph peaks, as well as slowing the contribution to the urban drainage network.This study proposes a conceptual model to predict the hydraulic behavior of a full-scale physical model of a vegetated roof. The model idealizes the vegetated roof as a system consisting of three individual components in series. A mass balance equation is applied to each block, taking into account the specific physical phenomena occurring in each module [3]. The model is validated using dataset observed from the monitoring campaign carried out on the prototype of a full-scale vegetated roof.This study aims to provide quantitative information about the hydraulic performance of vegetated roofs, and identify the most sensitive parameters for describing the hydraulic behavior. The results show a good ability of the model to fit the measured data.

scholarly journals Theoretical comparison of subgrid turbulence in the atmosphere and ocean

2015 ◽  
Vol 2 (6) ◽  
pp. 1675-1704
Author(s):  
V. Kitsios ◽  
J. S. Frederiksen ◽  
M. J. Zidikheri
Keyword(s):  
General Circulation ◽  
Scaling Laws ◽  
General Circulation Models ◽  
Computational Effort ◽  
Geophysical Research ◽  
Scaling Properties ◽  
Transport Studies ◽  
Subgrid Model ◽  
Operational Activities ◽  
Physical Phenomena

Abstract. Due to the massive disparity between the largest and smallest eddies in the atmosphere and ocean, it is not possible to simulate these flows by explicitly resolving all scales on a computational grid. Instead the large scales are explicitly resolved, and the interactions between the unresolved subgrid turbulence and large resolved scales are parameterised. If these interactions are not properly represented then an increase in resolution will not necessarily improve the accuracy of the large scales. This has been a significant and long standing problem since the earliest climate simulations. Historically subgrid models for the atmosphere and ocean have been developed in isolation, with the structure of each motivated by different physical phenomena. Here we solve the turbulence closure problem by determining the parameterisation coefficients (eddy viscosities) from the subgrid statistics of high resolution quasi-geostrophic atmospheric and oceanic simulations. These subgrid coefficients are characterised into a set of simple unifying scaling laws, for truncations made within the enstrophy cascading inertial range. The ocean additionally has an inverse energy cascading range, within which the subgrid model coefficients have alternative scaling properties. Simulations adopting these scaling laws are shown to reproduce the statistics of the reference benchmark simulations across resolved scales, with orders of magnitude improvement in computational efficiency. This reduction in both resolution dependence and computational effort will improve the efficiency and accuracy of geophysical research and operational activities that require data generated by general circulation models, including: weather, seasonal and climate prediction; transport studies; and understanding natural variability and extreme events.

scholarly journals Theoretical comparison of subgrid turbulence in atmospheric and oceanic quasi-geostrophic models

2016 ◽  
Vol 23 (2) ◽  
pp. 95-105 ◽  
Author(s):  
Vassili Kitsios ◽  
Jorgen S. Frederiksen ◽  
Meelis J. Zidikheri
Keyword(s):  
General Circulation ◽  
Scaling Laws ◽  
General Circulation Models ◽  
Computational Effort ◽  
Geophysical Research ◽  
Scaling Properties ◽  
Transport Studies ◽  
Subgrid Model ◽  
Operational Activities ◽  
Physical Phenomena

Abstract. Due to the massive disparity between the largest and smallest eddies in the atmosphere and ocean, it is not possible to simulate these flows by explicitly resolving all scales on a computational grid. Instead the large scales are explicitly resolved, and the interactions between the unresolved subgrid turbulence and large resolved scales are parameterised. If these interactions are not properly represented then an increase in resolution will not necessarily improve the accuracy of the large scales. This has been a significant and long-standing problem since the earliest climate simulations. Historically subgrid models for the atmosphere and ocean have been developed in isolation, with the structure of each motivated by different physical phenomena. Here we solve the turbulence closure problem by determining the parameterisation coefficients (eddy viscosities) from the subgrid statistics of high-resolution quasi-geostrophic atmospheric and oceanic simulations. These subgrid coefficients are characterised into a set of simple unifying scaling laws, for truncations made within the enstrophy-cascading inertial range. The ocean additionally has an inverse energy cascading range, within which the subgrid model coefficients have different scaling properties. Simulations adopting these scaling laws are shown to reproduce the statistics of the reference benchmark simulations across resolved scales, with orders of magnitude improvement in computational efficiency. This reduction in both resolution dependence and computational effort will improve the efficiency and accuracy of geophysical research and operational activities that require data generated by general circulation models, including weather, seasonal, and climate prediction; transport studies; and understanding natural variability and extreme events.

Microchannels in Series With Gradual Contraction/Expansion

2000 ◽  
Author(s):  
Wing Yin Lee ◽  
Sylvanus Yuk Kwan Lee ◽  
Man Wong ◽  
Yitshak Zohar
Keyword(s):  
Reynolds Number ◽  
Flow Resistance ◽  
Pressure Sensors ◽  
Separated Flow ◽  
Narrow Channel ◽  
Blood System ◽  
Multiple Channels ◽  
Added Resistance ◽  
Wide Channel ◽  
In Series

Abstract Fluidic systems usually contain multiple channels connected together, and the blood system or the lungs are typical examples. Microdevices consisting of a pair of microchannels in series, integrated with pressure sensors, were fabricated to study fluid flow in such complex microsystems. The dimensions of the channels are about 40μm×1.2μm×2000μm for the wide channel and about 20μm×1.2μm×2000μm for the narrow one. The channels are connected via an expansion/contraction section with an included angle of either 15° or 90°. Nitrogen was passed through the micro devices under inlet pressures up to 50psi. Each device was tested in the expansion, flow from narrow to wide channel, and contraction mode, flow from wide to narrow channel. Mass flow rate was first measured as a function of the overall pressure drop. Then the detailed pressure distribution along the channels was measured to understand the flow pattern around the expansion/contraction section. The reduced Reynolds number for such flows is about 0.001, suggesting that the flow is of the Hele-Shaw type with no separation. However, our results show that the flow resistance is higher than the friction losses, indicating that the flow may separate at the transition between the channels, and the added resistance due to the separated flow is not negligible although the channels are very long.

scholarly journals Influence of the Selection of the Core Shape and Winding Arrangement on the Accuracy of Current Transformers with Through-Going Primary Cable

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1932
Author(s):  
Elzbieta Lesniewska
Keyword(s):  
Current Transformer ◽  
Analytical Models ◽  
Current Transformers ◽  
Accuracy Class ◽  
Real Model ◽  
Current Error ◽  
Location Change ◽  
Measurement Location ◽  
Physical Phenomena ◽  
Metrological Requirements

The current transformers with split-core are used for installation in places where it is impossible to install classic current transformers. Moreover, this design allows for any measurement location change, and even switching one current transformer into several different shapes of bars or cables. Power network operators, striving for more accurate current measurements, require producers to provide current transformers with a special accuracy class 0.2S. Therefore, manufacturers and designers try to meet the market requirements and, similarly to non-demountable current transformers, i.e., with a toroidal core, design current transformers with split-core class 0.2S. To meet the high metrological requirements, 3D analyses of electromagnetic fields were performed, taking into account physical phenomena and not approximate analytical models. Two types of cores and four different arrangements of the secondary windings of the measuring current transformers were considered. The magnetic field distributions, current error, and phase displacement diagrams of all current transformer models were analyzed, and the model of the transformer structure with the best accuracy was selected. Computations were conducted based on the finite element numerical method, and the results were compared with the real model tests.

Microchannels in series connected via a contraction/expansion section

2002 ◽  
Vol 459 ◽  
pp. 187-206 ◽  
Author(s):  
WING YIN LEE ◽  
MAN WONG ◽  
YITSHAK ZOHAR
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Flow Direction ◽  
Pressure Sensors ◽  
Narrow Channel ◽  
Narrow Channels ◽  
Pressure Losses ◽  
Transition Section ◽  
In Series ◽  
Straight Segments

Fluid flow in microdevices consisting of pairs of microchannels in series was studied. The dimensions of the channels are about 40 μm × 1 μm × 2000 μm for the wide and about 20 μm × 1 μm × 2000 μm for the narrow channels. Pairs of wide and narrow channels, with integrated pressure sensors, are connected via transition sections with included angles varying from 5° to 180°. Minor pressure losses (not due to friction) were studied by passing nitrogen through the channels under inlet pressures up to 60 p.s.i. Each device was tested in the contraction mode, flow from wide to narrow channel, and in the opposite expansion mode, flow from narrow to wide channel. Mass flow rate was first measured as a function of the overall pressure drop. The detailed pressure distribution along the straight segments and around the transition section was then measured in order to understand the flow pattern. The Reynolds number for these flows is less than 1, suggesting the flow to be of the Hele-Shaw type with no separation such that the results for all the devices should be similar. However, the flow rate was found to decrease and the pressure loss to increase significantly with increasing included angle of the transition section, regardless of the flow direction. Flow separation due to the transition sections, if indeed there is any, cannot explain the large pressure drop since the kinetic energy is negligible.

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