scholarly journals Numerical investigation of energy transfer efficiency from microwave radiation to plasma in a cylindrical resonant cavity

2021 ◽  
Vol 2119 (1) ◽  
pp. 012123
Author(s):  
M Y Hrebtov ◽  
M S Bobrov
Keyword(s):  
High Pressures ◽  
Hydrogen Plasma ◽  
Resonant Cavity ◽  
Computational Cost ◽  
Absorption Efficiency ◽  
Energy Transfer Efficiency ◽  
Generation Process ◽  
Plasma Generation ◽  
Wide Range ◽  
Low Pressures

Abstract The paper presents a simplified numerical model of the hydrogen plasma generation process in a microwave resonant cavity. The model assumes electroneutrality and the prescribed electron temperature of the plasma, thus significantly reducing the computational cost. This allows for the parametric study in a wide range of operating pressures end electric field magnitudes (at a frequency of 2.45GHz). The prescribed model allows finding the effective range of operating pressures for the plasma generation. At low pressures, the collision rate is too low to effectively absorb all the emitted energy while at high pressures the electron conductivity drops which also reduces the absorption efficiency.

scholarly journals The influence of pressure on the spontaneous ignition of inflammable gas-air mixtures III—Hexane- and isobutane-air mixtures

1934 ◽  
Vol 146 (856) ◽  
pp. 113-129 ◽  
Keyword(s):  
Critical Pressure ◽  
High Pressures ◽  
Initial Pressure ◽  
Liquid Fuels ◽  
Spontaneous Ignition ◽  
Lower Range ◽  
Ignition Point ◽  
Wide Range ◽  
Temperature Ranges ◽  
Low Pressures

In two recent communications we described the results of investigations into the influence of varying initial pressure up to 15 atmospheres on the spontaneous ignition of butane- and pentane-air mixtures, showing that in each case the ignition were located in two distinct and widely separated temperature ranges, location in the higher range occurring at low pressures and in the lower range at high pressures. Transference of an ignition point from the higher to the lower range occurred sharply, at a critical pressure, which depended upon the hydrocarbon concerned and the composition of its mixture with air. The bearing of these observations upon the problem of knock was also discussed. A wide range of explosive media, comprising mainly the higher hydrocarbons contained in liquid fuels, is now being systematically studied, and the present paper summarizes the results obtained for hexane- and isobutane-air mixtures. So far, our results support the view (also recently endorsed by Neumann and Estrovitch) that the lower group of ignition points is the outcome of the survival and further rapid oxidation of certain intermediate bodies, a process favoured by high pressure. whereas the higher group results from ignitions mainly of the products of their thermal decompositions which are favoured by low pressure.

THERMAL CONDUCTIVITY OF SOLIDS AT HIGH TEMPERATURES AND HIGH PRESSURES

2007 ◽  
Vol 21 (25) ◽  
pp. 4419-4427 ◽  
Author(s):  
S. K. SHARMA ◽  
S. K. SRIVASTAVA ◽  
B. S. SHARMA
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
High Temperatures ◽  
High Pressures ◽  
Equations Of State ◽  
Conductivity Equation ◽  
Thermoelastic Properties ◽  
Thermal Conductivity Equation ◽  
Wide Range ◽  
Low Pressures

In the present study, we have extended the model due to Tang1 based on the thermal conductivity equation due to Leibfried and Schlomann12 so as to make it applicable for a wide range of pressures and temperatures. We have used the Stacey14,15 equations of state (EOS) for determining the thermoelastic properties of NaCl , KCl and Al 2 O 3 at high pressures and high temperatures. These are used to estimate the variations of thermal conductivity with the change in pressure along different isotherms at selected temperatures. The results thus obtained are compared with the values derived from relations, which reproduced available experimental data well at low temperatures and low pressures. Experimental data at high temperatures and high pressures are not available. A close agreement between the two sets of data reveals the validity of the present work.

The Short-Time Compressibility of Elastohydrodynamic Lubricants

1991 ◽  
Vol 113 (2) ◽  
pp. 361-370 ◽  
Author(s):  
K. T. Ramesh
Keyword(s):  
High Pressures ◽  
Elastohydrodynamic Lubrication ◽  
Deformation Analysis ◽  
Plate Impact ◽  
Wide Range ◽  
Density Relationship ◽  
Short Time ◽  
Impact Experiments ◽  
Low Pressures ◽  
Short Times

Elastohydrodynamic (EHD) lubricants are subjected to very large pressures (several GPa) for very short times (10−4 seconds) in typical EHD contacts. However, measurements of EHD lubricant compressibilities to date have primarily been made for quasistatic deformations and only for relatively low pressures. This paper presents some experimental results on the variation of the density of the lubricant 5P4E over a very wide range of pressures and over two distinct timescales, from 10−6 seconds to 10−4 seconds. The very short time (10−6 seconds) data are obtained from plate-impact experiments, and the data near 10−4 seconds are obtained with a new experimental technique using the compression Kolsky bar. It is observed that the commonly used Dowson-Higginson relationship represents too stiff a response at the high pressures for these short times, at least for this synthetic lubricant. A full finite deformation analysis of the plate impact problem is used to obtain the material response function for the large compressibilities observed. On the basis of these results, we suggest a new form of the pressure-density relationship for an elastohydrodynamic lubricant that appears to hold over the entire range of pressures and for time durations on the order of those actually occurring in elastohydrodynamic lubrication.

Wide-range equations of state for organic liquids

2007 ◽  
Vol 5 ◽  
pp. 113-120 ◽  
Author(s):  
R.Kh. Bolotnova
Keyword(s):  
High Pressures ◽  
Equations Of State ◽  
Organic Liquids ◽  
Liquid Phases ◽  
Wide Range ◽  
High Pressures And Temperatures

The method of construction the wide-range equations of state for organic liquids, describing the gas and liquid phases including dissociation and ionization which occurs during an intense collapse of steam bubbles and accompanied by ultra-high pressures and temperatures, is proposed.

scholarly journals BLAINDER—A Blender AI Add-On for Generation of Semantically Labeled Depth-Sensing Data

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2144
Author(s):  
Stefan Reitmann ◽  
Lorenzo Neumann ◽  
Bernhard Jung
Keyword(s):  
Point Clouds ◽  
Training Data ◽  
Sensor Data ◽  
Generation Process ◽  
Data Generation ◽  
Depth Sensor ◽  
Depth Sensing ◽  
Depth Sensors ◽  
3D Point Clouds ◽  
Wide Range

Common Machine-Learning (ML) approaches for scene classification require a large amount of training data. However, for classification of depth sensor data, in contrast to image data, relatively few databases are publicly available and manual generation of semantically labeled 3D point clouds is an even more time-consuming task. To simplify the training data generation process for a wide range of domains, we have developed the BLAINDER add-on package for the open-source 3D modeling software Blender, which enables a largely automated generation of semantically annotated point-cloud data in virtual 3D environments. In this paper, we focus on classical depth-sensing techniques Light Detection and Ranging (LiDAR) and Sound Navigation and Ranging (Sonar). Within the BLAINDER add-on, different depth sensors can be loaded from presets, customized sensors can be implemented and different environmental conditions (e.g., influence of rain, dust) can be simulated. The semantically labeled data can be exported to various 2D and 3D formats and are thus optimized for different ML applications and visualizations. In addition, semantically labeled images can be exported using the rendering functionalities of Blender.

Respiratory Mechanics of Sound Production in Chickens and Geese

1978 ◽  
Vol 72 (1) ◽  
pp. 229-250
Author(s):  
J. H. BRACKENBURY
Keyword(s):  
Respiratory System ◽  
Simultaneous Measurement ◽  
Sound Production ◽  
High Pressures ◽  
Respiratory Mechanics ◽  
Air Flow ◽  
Tracheal Pressure ◽  
Wide Range ◽  
Range Of Values ◽  
Respiratory Movements

1. Air flow, air sac pressure and tracheal pressure were measured in chickens and geese during a variety of different vocal and non-vocal activities. 2. Air flow and air sac pressure may rise to 500 ml s−1 and 60 cmH2O (6 103 N/m2) respectively during a crow in the chicken. During a sequence of honks in the goose the corresponding values are 650 ml s−1 and 25 cmH2O(2.5 × 10 3 N/m2) respectively. 3. The volume of air delivered through the respiratory system during a single crow is more than 400 ml, almost equivalent to the total volume of the lung air sac system. 4. The efficiency of the chicken syrinx as a sound producing instrument, estimated by comparing the sound energy radiated with the energy consumed in the expulsion of air during a crow, appears to be less than 2 %. 5. Cutting the paired sternotrachealis muscles had no effect on vocalization. 6. The measured rates of clucking, cheeping and honking in adult chickens, young chicks and adult geese respectively are comparable to the characteristic rates of panting in these animals. This points to a similarity in the nature of the respiratory movements involved in each case. 7. Simultaneous measurement of tracheal flow and pressure indicate that the glottis is capable of controlling air flow over a wide range of values in the presence of high pressures. During defaecation the valve is closed whilst during coughing it is wide open.

The Design, Development and Validation of an Innovative High Strength, Self Monitoring, Composite Pipe Liner for the Restoration of Energy Transmission Pipelines

2006 ◽  
Author(s):  
Kyle Bethel ◽  
Steven C. Catha ◽  
Melvin F. Kanninen ◽  
Randall B. Stonesifer ◽  
Ken Charbonneau ◽  
...  
Keyword(s):  
High Pressures ◽  
Large Diameter ◽  
Cylindrical Tube ◽  
High Strength ◽  
Design Development ◽  
Energy Transmission ◽  
Engineering Research ◽  
Wide Range ◽  
Transmission Pipelines

The research described in this paper centers on a composite of thermoplastic materials that can be inserted in a degraded steel pipe to completely restore its strength. Through the use of fabrics consisting of ultra high strength fibers that are co-helically wrapped over a thin walled thermoplastic cylindrical tube that serves as a core, arbitrarily high pressures can be achieved. This paper first outlines the design, manufacturing and installation procedures developed for this unique material to provide a context for the engineering research. Based on this outline, the technological basis that has been developed for assuring the strength and long term durability of this concept during its insertion, and in its very long term service as a liner in energy transmission pipelines, is presented in detail. The research that is described includes burst testing of the material in stand alone pipe form, load/elongation testing of ultra high strength fabrics, and linear and nonlinear elastic and viscoelastic analysis models. This body of work indicates that the concept is fundamentally feasible for restoring a wide range of large diameter natural gas and liquid transmission pipelines to be able to carry arbitrarily high pressures over very long lifetimes. It also indicates that liners can be safely installed in long lengths even in lines with severe bends in a continuous manner. With further research the concept has the potential for eliminating hydro testing and smart pigging during service, and could possibly be installed in some lines that are currently unpiggable.

scholarly journals The Open Global Glacier Model (OGGM) v1.0

2018 ◽  
Author(s):  
Fabien Maussion ◽  
Anton Butenko ◽  
Julia Eis ◽  
Kévin Fourteau ◽  
Alexander H. Jarosch ◽  
...  
Keyword(s):  
Mass Balance ◽  
Open Source ◽  
Sea Level ◽  
Computational Cost ◽  
Balance Model ◽  
Climate Data ◽  
Estimation Model ◽  
Model Framework ◽  
Validation Data ◽  
Wide Range

Abstract. Despite of their importance for sea-level rise, seasonal water availability, and as source of geohazards, mountain glaciers are one of the few remaining sub-systems of the global climate system for which no globally applicable, open source, community-driven model exists. Here we present the Open Global Glacier Model (OGGM, http://www.oggm.org), developed to provide a modular and open source numerical model framework for simulating past and future change of any glacier in the world. The modelling chain comprises data downloading tools (glacier outlines, topography, climate, validation data), a preprocessing module, a mass-balance model, a distributed ice thickness estimation model, and an ice flow model. The monthly mass-balance is obtained from gridded climate data and a temperature index melt model. To our knowledge, OGGM is the first global model explicitly simulating glacier dynamics: the model relies on the shallow ice approximation to compute the depth-integrated flux of ice along multiple connected flowlines. In this paper, we describe and illustrate each processing step by applying the model to a selection of glaciers before running global simulations under idealized climate forcings. Even without an in-depth calibration, the model shows a very realistic behaviour. We are able to reproduce earlier estimates of global glacier volume by varying the ice dynamical parameters within a range of plausible values. At the same time, the increased complexity of OGGM compared to other prevalent global glacier models comes at a reasonable computational cost: several dozens of glaciers can be simulated on a personal computer, while global simulations realized in a supercomputing environment take up to a few hours per century. Thanks to the modular framework, modules of various complexity can be added to the codebase, allowing to run new kinds of model intercomparisons in a controlled environment. Future developments will add new physical processes to the model as well as tools to calibrate the model in a more comprehensive way. OGGM spans a wide range of applications, from ice-climate interaction studies at millenial time scales to estimates of the contribution of glaciers to past and future sea-level change. It has the potential to become a self-sustained, community driven model for global and regional glacier evolution.

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