scholarly journals Hydro Energy Harvesting by Using Compliant Surfaces: Preliminary Experimental Assessment

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Francisco J. Arias ◽  
Salvador De Las Heras
Keyword(s):  
Energy Harvesting ◽  
Relative Velocity ◽  
Static Pressure ◽  
Dynamic Pressure ◽  
Residual Water ◽  
Experimental Assessment ◽  
Harmonic Motion ◽  
Compliant Surface ◽  
The Core ◽  
Compliant Surfaces

Abstract In this work consideration is given for hydro energy harvesting contained in residual water streams. The idea lies in the bifurcation of the stream into two channels separated by a compliant surface or membrane which, albeit with equalized static pressure at both sides, nevertheless with a relative velocity. As a result of the differential dynamic pressure, a steady-state harmonic motion is established which might be transformed into an electrical output. A first experimental assessment of this idea constitutes the core of this presentation.

scholarly journals Dynamic Pressure Pain Hypersensitivity as Assessed by Roller Pressure Algometry in Episodic Cluster Headache

2020 ◽  
Vol 2;23 (4;2) ◽  
pp. 219-227
Author(s):  
César Fernández-de-las-Peñas
Keyword(s):  
Cluster Headache ◽  
Pain Sensitivity ◽  
Static Pressure ◽  
Dynamic Pressure ◽  
Pressure Algometry ◽  
Pressure Pain ◽  
Key Words Cluster Headache ◽  
Pressure Pain Thresholds ◽  
Preventive Medication ◽  
Pressure Algometer

Background: A method for assessing dynamic muscle hyperalgesia (dynamic pressure algometry) has been developed and applied in tension-type and migraine headaches. Objectives: To investigate differences in dynamic pressure pain assessment over the trigeminal area between men with cluster headache (CH) and headache-free controls, and the association between dynamic and static pressure pain sensitivity. Study Design: A case-control study. Setting: Tertiary urban hospital. Methods: Forty men with episodic CH and 40 matched controls participated. Dynamic pressure pain sensitivity was assessed with a dynamic pressure algometry set consisting of 8 rollers with different fixed levels (500, 700, 850, 1,350, 1,550, 2,200, 3,850, and 5,300 g). Each roller was moved at a speed of 0.5 cm/sec over a diagonal line covering the temporalis muscle from an anterior to posterior direction. The dynamic pressure threshold (DPT; load level of the first painful roller) and the pain intensity perceived at the DPT level (roller-evoked pain) were assessed. Static pressure pain thresholds (PPT) were also assessed with a digital pressure algometer applied statically over the mid-muscle belly of the temporalis. Patients were assessed in a remission phase, at least 3 months from the last cluster attack, and without preventive medication. Results: Side-to-side consistency between DPTs (r = 0.781, P < 0.001), roller-evoked pain on DPT (r = 0.586; P < 0.001), and PPTs (r = 0.874; P < 0.001) were found in men with CH. DPT was moderately, bilaterally, and side-to-side associated with PPTs (0.663 > r > 0.793, all P < 0.001). Men with CH had bilateral lower DPT and PPT and reported higher levels of rollerevoked pain (all P < 0.001) than headache-free controls. Limitations: Only men with episodic CH were included. Conclusions: This study supports that a dynamic pressure algometry is as valid as a static pressure algometry for assessing pressure pain sensitivity in patients with CH. Assessing both dynamic and static pain sensitivity may provide new opportunities for differentiated diagnostics. Key words: Cluster headache, dynamic pressure pain, pressure pain threshold

scholarly journals An Implanted Magnetic Microfluidic Pump for In Vivo Bone Remodeling Applications

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 300 ◽  
Author(s):  
Ziyu Chen ◽  
Sunggi Noh ◽  
Rhonda D. Prisby ◽  
Jeong-Bong Lee
Keyword(s):  
Bone Growth ◽  
Static Pressure ◽  
Dynamic Pressure ◽  
The Body ◽  
In Vivo Studies ◽  
Fischer 344 ◽  
Fischer 344 Rat ◽  
Pressure Modulation

Modulations of fluid flow inside the bone intramedullary cavity has been found to stimulate bone cellular activities and augment bone growth. However, study on the efficacy of the fluid modulation has been limited to external syringe pumps connected to the bone intramedullary cavity through the skin tubing. We report an implantable magnetic microfluidic pump which is suitable for in vivo studies in rodents. A compact microfluidic pump (22 mm diameter, 5 mm in thickness) with NdFeB magnets was fabricated in polydimethylsiloxane (PDMS) using a set of stainless-steel molds. An external actuator with a larger magnet was used to wirelessly actuate the magnetic microfluidic pump. The characterization of the static pressure of the microfluidic pump as a function of size of magnets was assessed. The dynamic pressure of the pump was also characterized to estimate the output of the pump. The magnetic microfluidic pump was implanted into the back of a Fischer-344 rat and connected to the intramedullary cavity of the femur using a tube. On-demand wireless magnetic operation using an actuator outside of the body was found to induce pressure modulation of up to 38 mmHg inside the femoral intramedullary cavity of the rat.

scholarly journals Monitoring gas hydrate formation with magnetic resonance imaging in a metallic core holder

2019 ◽  
Vol 89 ◽  
pp. 02008
Author(s):  
Mojtaba Shakerian ◽  
Armin Afrough ◽  
Sarah Vashaee ◽  
Florin Marica ◽  
Yuechao Zhao ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Methane Hydrate ◽  
Hydrate Formation ◽  
Residual Water ◽  
Saturated Sand ◽  
Resonance Imaging ◽  
The Core ◽  
T2 Distribution ◽  
Core Holder ◽  
Water Saturated

Methane hydrate deposits world-wide are promising sources of natural gas. Magnetic Resonance Imaging (MRI) has proven useful in previous studies of hydrate formation. In the present work, methane hydrate formation in a water saturated sand pack was investigated employing an MRI-compatible metallic core holder at low magnetic field with a suite of advanced MRI methods developed at the UNB MRI Centre. The new MRI methods are intended to permit observation and quantification of residual fluids in the pore space as hydrate forms. Hydrate formation occurred in the water-saturated sand at 1500 psi and 4 °C. The core holder has a maximum working pressure of 4000 psi between -28 and 80 °C. The heat-exchange jacket enclosing the core holder enabled very precise control of the sample temperature. A pure phase encode MRI technique, SPRITE, and a bulk T1-T2 MR method provided high quality measurements of pore fluid saturation. Rapid 1D SPRITE MRI measurements time resolved the disappearance of pore water and hence the growth of hydrate in the sand pack. 3D π-EPI images confirmed that the residual water was inhomogeneously distributed along the sand pack. Bulk T1-T2 measurements discriminated residual water from the pore gas during the hydrate formation. A recently published local T1-T2 method helped discriminate bulk gas from the residual fluids in the sample. Hydrate formation commenced within two hours of gas supply. Hydrate formed throughout the sand pack, but maximum hydrate was observed at the interface between the gas pressure head and the sand pack. This irregular pattern of hydrate formation became more uniform over 24 hours. The rate of hydrate formation was greatest in the first two hours of reaction. An SE-SPI T2 map showed the T2 distribution changed considerably in space and time as hydrate formation continued. Changes in the T2 distribution are interpreted as pore level changes in residual water content and environment.

Pulsatile and Steady Pressure-Flow Relations in the Vascular Bed of the Hind Leg of the Dog

1956 ◽  
Vol 185 (2) ◽  
pp. 351-354 ◽  
Author(s):  
James E. Randall ◽  
Ralph W. Stacy
Keyword(s):  
Measurement Accuracy ◽  
Static Pressure ◽  
Dynamic Pressure ◽  
Flow Diagram ◽  
Pressure Flow ◽  
Pulsatile Pressure ◽  
Instantaneous Pressure ◽  
Flow Diagrams ◽  
The Mean ◽  
The One

Instantaneous pressure and flow in the femoral artery of the dog were recorded under steady and pulsatile pressure conditions. Static pressure-flow diagrams and dynamic pressure-flow diagrams over the pulse pressure range at different points in the cardiac cycle were constructed. A comparison was made of the flow corresponding to a) normal pulsatile conditions, and b) static pressures equal to the mean of the pulsatile pressures. The static pressure-flow diagrams were consistent with those described by other workers, and were essentially linear in the ranges studied. Changing from steady to pulsating pressures altered the flow from 40.4 ml/min. to 40.9 ml/min. This difference was less than the measurement accuracy of the flow, although statistical analysis indicated significance to 1%. The dynamic pressure-flow diagram appeared as a ‘loop,’ the shape of which indicated that in 12 of 13 animals, the system was mass controlled and the heart rate was higher than the resonant frequency. In the one exception, the phase angle was negligible and the system was apparently in resonance.

Prevention of Transformer Tank Explosion: Part 3—Design of Efficient Protections Using Numerical Simulations

2009 ◽  
Author(s):  
Ryan Brady ◽  
Sebastien Muller ◽  
Margareta Petrovan-Boiarciuc ◽  
Guillaume Perigaud ◽  
Benjamin Landis
Keyword(s):  
Electricity Markets ◽  
Static Pressure ◽  
Mechanical Response ◽  
Dynamic Pressure ◽  
Pressure Vessels ◽  
Simulation Software ◽  
Two Phase ◽  
Pressure Peak ◽  
Electrical Faults ◽  
Volume Method

Electricity markets are very competitive and in order to limit costs, companies often reduce their investments by using aging equipment and by overloading their transformers. For these reasons, oil-filled transformer explosions are becoming more and more frequent. They are caused by electrical arcs occurring in transformer tanks. Within milliseconds, arcs vaporize the surrounding oil and the generated gas is pressurized because the liquid inertia prevents its expansion. The pressure difference between the gas bubble and the surrounding liquid oil generates a dynamic pressure peak, which propagates and interacts with the tank. Then, the reflections generate pressure waves that build up the static pressure, leading to tank rupture since tanks are not designed to withstand such levels of static pressure. This results in dangerous explosions, expensive damages and possible environmental pollution. Despite all these risks, and contrarily to usual pressure vessels, no specific standard has been set to protect sealed transformer tanks subjected to large dynamic overpressures. To limit the consequences of an explosion, protective walls surrounding transformers can contain the explosion while sprinklers may extinguish the induced fire. In order to extend this chain of protections to the transformer itself, a strategy to avoid transformer tank rupture was developed and presented at the previous PVP08 Conference (PVP2008-61526 - Prevention of Transformer Tank Explosion: Part 1). The concept of this strategy is based on the direct mechanical response of a depressurization set to the inner dynamic pressure induced by electrical faults. In the same paper, the efficiency of this depressurization strategy was experimentally shown: if the oil evacuation through the depressurization set is activated within milliseconds by the first dynamic pressure peak before static pressure increases, the explosion can be prevented. The use of these protections eliminates the need to design transformer tanks as pressure vessels, which by application of the ASME standard would require a significant increase of the the shell thickness. Complementarily, a compressible two-phase flow numerical simulation tool based on a 3D finite volume method was developed to study transformer explosions and possible strategies for their prevention. Its theoretical bases were detailed in the PVP08 ASME Conference (PVP2008-61453 - Prevention of Transformer Tank Explosion: Part 2). The current paper shows the applications of this simulation software as a decision making tool, especially toward improving the design of real mechanical transformer protections. Some guidelines to optimize the efficiency of transformer protections are suggested thus contributing to a possible standard setting.

Aerodynamic Torque Acting on a Butterfly Valve. Comparison and Choice of a Torque Coefficient

1999 ◽  
Vol 121 (4) ◽  
pp. 914-917 ◽  
Author(s):  
C. Solliec ◽  
F. Danbon
Keyword(s):  
Pressure Drop ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Low Cost ◽  
Normalization Method ◽  
Pressure Drops ◽  
Torque Coefficient ◽  
Aerodynamic Torque ◽  
Valve Pressure

Most technological devices use butterfly valves to check the flow rate and speed, through piping. Their main advantages are their low cost, their mechanical suitability for fast operation, and their small pressure drops when they are fully open. The fluid dynamic torque about the axis of large valves has to be considered as the actuator could be overstrained. This torque is generally defined using a nondimensional coefficient KT, in which the static pressure drop created by the valve is used for normalization. When the valve is closed downstream of an elbow, the valve pressure drop is not well defined. Thus, the classic normalization method gives many ambiguities. To avoid the use of the pressure drop, we define another torque coefficient CT in which the dynamic pressure of the flow is the normalization factor instead of the pressure drop. Advantages and drawbacks of each normalization method are described in the following.

Numerical Simulation of Dense Phase Pneumatic Conveying Gypsum in Stepped Pipeline

2011 ◽  
Vol 306-307 ◽  
pp. 1387-1392
Author(s):  
Wei Xiang Wu ◽  
Zong Ming Liu ◽  
Guang Bin Duan
Keyword(s):  
Static Pressure ◽  
Fluid Model ◽  
Dynamic Pressure ◽  
Phase Flow ◽  
Pneumatic Conveying ◽  
Dense Phase ◽  
Two Phase ◽  
Simulation Results ◽  
Two Fluid Model ◽  
Two Fluid

The process of dense phase pneumatic conveying gypsum in stepped pipeline was simulated by using an Euler-Euler two fluid model of dense gas-particle two phase flow based on the kinetic theory of gas and granular. The simulation results showed dynamic pressure increased while static pressure decreased in the first two tapered pipe, but this trend became opposite in the last diffuser pipe. The gas and particle velocity both increased in the 80-65mm and 65-50mm tapered pipe, but decreased in 50-80mm diffuser pipe. In a short, the results showed that the simulation was consistent with the fact, which proved the feasibility of our simulation.

Intramolecular energy transfer and photoisomerization in stilbene dendrimers

2017 ◽  
Vol 95 (9) ◽  
pp. 1013-1023 ◽  
Author(s):  
Masahiro Taima ◽  
Yuka Ishida ◽  
Tatsuo Arai
Keyword(s):  
Energy Transfer ◽  
Energy Harvesting ◽  
Photophysical Properties ◽  
Intersystem Crossing ◽  
Intramolecular Energy Transfer ◽  
The Core ◽  
Transfer Processes ◽  
Trans Isomerization ◽  
Photophysical Processes ◽  
In Cis

Stilbene dendrimers with energy harvesting chromophores, such as naphthalene and benzophenone, have been prepared and their photochemical and photophysical properties have been examined. These dendrimers underwent trans–cis mutual photoisomerization on excitation of the core stilbene or the peripheral naphthalene and benzophenone chromophores through several energy transfer processes, and photophysical processes such as intersystem crossing finally resulted in cis-trans isomerization of the core stilbene.

Measurement and Analysis of an Efficient Turbine Rotor Pump Work Reduction System Incorporating Pre-Swirl Nozzles and a Free Vortex Pressure Augmentation Chamber

2004 ◽  
Author(s):  
V. Laurello ◽  
M. Yuri ◽  
K. Fujii ◽  
K. Ishizaka ◽  
T. Nakamura ◽  
...  
Keyword(s):  
Relative Velocity ◽  
Static Pressure ◽  
Tangential Velocity ◽  
Pressure Rise ◽  
Turbine Rotor ◽  
Vortex Chamber ◽  
Free Vortex ◽  
Pressure Losses ◽  
Cooling Air ◽  
Velocity Pressure

Measurements and analysis of an efficient turbine rotor pump work reduction system is presented. The system features; a “low” radius pre-swirl nozzle comprised of cascade vanes with a radial orientation, equal radius seals downstream of the nozzle, “jumper” tubes across the nozzle, and a free vortex chamber. A scaled experimental rig was utilized to measure and compare with predictions the following; rotor pump work, average tangential velocity exiting the nozzle, tangential velocity variation in the axial and radial direction, free vortex chamber static pressure rise, effect of relative velocity pressure losses, and effect of “pollution” by seal flow. The effort focused on measuring pump work reduction and the efficiency of the pressure augmentation system. In contrast to aero-engines where the main objective of pre-swirl is to reduce cooling air temperature to the blades, the main objective for this industrial gas turbine is to reduce pump work and increase output. An external pre-cooler is utilized to achieve the large cooling air temperature reduction required to maintain disk material limits. The analytical results and rig test data are presented and compared. The results substantiated the following: the level of reduced rotor pump work due to pre-swirl, the static pressure rise in the free vortex chamber, the effect of eliminating “pollution”, and relative velocity pressure losses. CFD analytical results are compared with the rig data.

Steam Explosion Experiments Using ZrO2 and ZrO2/UO2 Mixture

2002 ◽  
Author(s):  
Jinho Song ◽  
Ikkyu Park ◽  
Yongseung Sin ◽  
Jonghwan Kim ◽  
Seongwan Hong ◽  
...  
Keyword(s):  
Steam Explosion ◽  
Static Pressure ◽  
Dynamic Pressure ◽  
Pressure Profile ◽  
Conversion Ratio ◽  
Water Pool ◽  
Energy Research ◽  
Melt Temperature ◽  
Water Interaction ◽  
Made In

Korea Atomic Energy Research Institute (KAERI) has been carrying an experimental research program on the steam explosion named “Test for Real cOrium Interaction with water (TROI)” since 1997. The objective of the program is to investigate whether the corium would lead to an energetic steam explosion and to measure the conversion ratio of the energetic steam explosion. In the first series of tests using several kg of ZrO2 where the melt/water interaction were made in the water pool at 30 ∼ 95 °C, either a quenching or a spontaneous steam explosions was observed. In the second series of tests using the mixture of UO2/ZrO2 performed in a similar manner as that of ZrO2, it also resulted in either a quenching or energetic steam explosion. The morphology of debris and pressure profile clearly indicate the differences in those two phenomena. The process parameters including the dynamic pressure, dynamic impulse, water and melt temperature, static pressure inside the containment chamber were measured.

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