scholarly journals Experimental Validation of a Novel Generator of Gas Mixtures Based on Axial Gas Pulses Coupled to a Micromixer

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 715
Author(s):  
Florian Noël ◽  
Claire Trocquet ◽  
Christophe A. Serra ◽  
Stéphane Le Calvé
Keyword(s):  
Experimental Validation ◽  
Gas Mixtures ◽  
Analytical Instrument ◽  
Pure Nitrogen ◽  
Gas Concentration ◽  
Multi Stage ◽  
The Times ◽  
Gas Dilution ◽  
Pollutant Mixtures ◽  
Two Parameters

In this work, a novel generator of gas mixtures previously numerically investigated and based on axial gas pulses coupled to a micromixer has been conceived, manufactured, and validated. Standard gaseous pollutant mixtures and pure nitrogen or pure air were introduced in a microdevice designed to generate alternating axial gas pulses which were downstream homogenized by means of a multi-stage modular micromixer. The dilution, and therefore the final pollutant concentration, was controlled by two parameters: the ratio between the times of each of the two gas pulses and the partial pressure of the pollutant(s) mixture added to the device. The gas mixture generator was coupled to an analyzer to monitor the concentration of aromatic pollutants. The response time was optimized to be lower than 2 min in accordance with the analytical instrument. The quantity of pollutants measured at the micromixer’s outlet increased linearly with the expected gas concentration of 3.7–100 ppb generated by this novel microfluidic generator and fitted perfectly with those obtained by a reference gas dilution bench. At 5 ppb, the precision on the concentration generated is close to that obtained with the conventional gas mixing bench, i.e., around 10%.

A New Approach to Analyzing Gas Mixtures Based on Improved BP Neural Network Algorithm

2012 ◽  
Vol 260-261 ◽  
pp. 548-553
Author(s):  
Teng Li ◽  
Xiao Mei Yuan ◽  
Shi Liang Yang ◽  
Xin Hui Zhang
Keyword(s):  
Neural Network ◽  
Numerical Simulation ◽  
Bp Neural Network ◽  
Array Signal Processing ◽  
Sensor Arrays ◽  
Gas Mixtures ◽  
New Approach ◽  
Gas Concentration ◽  
Network Algorithm ◽  
Neural Network Algorithm

A new approach is presented for analyzing gas mixtures by transforming the problem into a pattern classification one to reduce the effect of the poor repeatability of sensor response on the prediction of gas concentration. The aim of numerical simulation is to determine how successfully the approach using the combination of artificial neural networks with multi-sensor arrays can analyze multi-component gas mixtures. The results indicate that the new approach is realistic for gas mixture analysis, and numerical simulation is a powerful tool to determine the architecture of a network. By constructing improved BP neural network algorithm and basic BP neural network into sensor array signal processing and extracting 6 component as the input of neural network, Our investigation results indicated that recognition results obtained from improved BP neural network algorithm more accuracy than the results obtained from basic BP neural network.

scholarly journals Strupczewski Method for Parametric Design Hydrographs in Ungauged Cross-Sections

2017 ◽  
Vol 64 (1) ◽  
pp. 49-67 ◽  
Author(s):  
Wiesław Gądek ◽  
Beata Baziak ◽  
Tamara Tokarczyk
Keyword(s):  
Cross Sections ◽  
Parametric Design ◽  
Complex Function ◽  
River Catchment ◽  
Flood Hydrograph ◽  
Skewness Coefficient ◽  
Design Hydrographs ◽  
Flow Changes ◽  
The Times ◽  
Two Parameters

AbstractNonparametric hydrographs, constructed by the method suggested by Archer, are usually used for developing parametric design hydrographs. Flow changes in time are described by the UPO ERR Gamma complex function, which denotes a Gamma curve reformulated to have a Unit Peak at the Origin (abbreviated to UPO), supplemented by the Exponential Replacement Recession (ERR) curve. It may be observed, that this solution does not work in some areas of the upper Vistula and middle Odra catchments when the times of the rising limb of a hydrograph are higher than the times of the falling limb, i.e. when the skewness coefficient approximates 0.5 or higher values. Better results can be achieved with the function suggested by Strupczewski in 1964. It is a solution which uses two parameters of the flood hydrograph. The objective of the present paper is to assess the Strupczewski method by comparing it with a complex UPO ERR Gamma function for gauged cross-sections in the upper Vistula and middle Odra catchments. The assessment was carried out for 30 gauged cross-sections (15 in each river catchment). The parameters were optimized for width-hydrograph descriptors W75 and W50, designed by the Archer method, and for the skewness coefficient s. Optimization using only two width-hydrograph descriptors aims to test how the Strupczewski method works for cross-sections for which the values of width-hydrograph descriptors W75 and W50 are known. The assessment of both methods was carried out with reference to a nonparametric hydrograph constructed by the Archer method. The results of these assessments suggest that the Strupczewski method may be used not only for gauged cross-sections, but also for ungauged ones.

Experimental Validation and Numerical Simulation of Static Pressure in Multi-Stage Ferrofluid Seals

2019 ◽  
Vol 55 (3) ◽  
pp. 1-8 ◽  
Author(s):  
Yanjuan Zhang ◽  
Yibiao Chen ◽  
Decai Li ◽  
Zhengmao Yang ◽  
Yilong Yang
Keyword(s):  
Numerical Simulation ◽  
Experimental Validation ◽  
Static Pressure ◽  
Multi Stage

Modeling and experimental validation of the vibration in an unbalance multi-stage rotor

2019 ◽  
Vol 13 (3) ◽  
pp. 5703-5716
Author(s):  
W. Cruz ◽  
N. Arzola ◽  
O. Araque
Keyword(s):  
Finite Element Method ◽  
Experimental Validation ◽  
Lateral Vibration ◽  
Critical Speeds ◽  
Multi Stage ◽  
Gyroscopic Effects ◽  
Validation Tests ◽  
Method Model ◽  
Rotor Dynamic

This work proposes a finite element method model to predict lateral vibration phenomena arising in the multi-stage rotor (seven stages) with unbalance, including damping and gyroscopic effects. The rotor dynamic analysis includes mathematical and experimental determination of the first and second critical speeds of the rotor and the assessment of the effects induced by the different unbalance combinations. The results show that while considering the unbalance effects in the impellers, critical speeds move to lower frequencies compared to normal conditions when the rotor is properly balanced. Finally, the results obtained analytically achieved a good degree of correspondence with experimental validation tests.

Analysis of Gas Diffusion-Induced Cassie to Wenzel State Transition on a Structured Surface

2016 ◽  
Author(s):  
Jonah Kadoko ◽  
Georgios Karamanis ◽  
Toby Kirk ◽  
Marc Hodes
Keyword(s):  
Concentration Field ◽  
Gas Diffusion ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Gas Concentration ◽  
Structured Surface ◽  
Cassie State ◽  
Wenzel State ◽  
The Times ◽  
Quiescent Liquid

We provide an approximate and one-dimensional solution for transient diffusion of gas between parallel ridges into a degassed and quiescent liquid suspended in the Cassie state above a parallel-ridge type structured surface. At time equal to zero, the liquid and gas are at the same pressure; therefore, the meniscus formed between ridges is flat. The analysis provides the transient gas concentration field in the liquid. It also computes the times when the triple contact line begins to move down the ridges and that when the meniscus contacts the bottom substrate compromising the Cassie state.

INDUCED INFRARED ABSORPTION OF NITROGEN AND NITROGEN – FOREIGN GAS MIXTURES

1965 ◽  
Vol 43 (12) ◽  
pp. 2331-2343 ◽  
Author(s):  
S. Paddi Reddy ◽  
C. W. Cho
Keyword(s):  
Room Temperature ◽  
Gas Mixtures ◽  
Fundamental Vibration ◽  
Molecular Constants ◽  
Pure Nitrogen ◽  
Helium Mixtures ◽  
Vibration Rotation ◽  
The Individual ◽  
Straight Lines ◽  
Good Agreement

The pressure-induced fundamental vibration–rotation absorption band of nitrogen was studied in the pure gas and in nitrogen–argon, nitrogen–hydrogen, and nitrogen–helium mixtures at room temperature for pressures up to 1 500 atm. The shapes of the absorption profiles obtained in each case were discussed. The enhancement absorption profiles of nitrogen–argon mixtures exhibited the sharpening of the individual branches of the fundamental band with a small frequency shift, while those of nitrogen–hydrogen and nitrogen–helium mixtures indicated a splitting of the Q branch. Binary and ternary absorption coefficients were determined for pure nitrogen and nitrogen – foreign gas mixtures. The graph drawn with (1/ρa2) ∫α(ν)dν vs. ρa for pure nitrogen and those drawn with (1/ρaρb) (∫α(ν)dν)enhancement vs. ρb for mixtures were found to be straight lines. Except for nitrogen–helium mixtures all these straight lines had negative slopes, and this was interpreted as a partial cancelation of the induced moments due to ternary collisions. Applying the theory of Van Kranendonk and using the known molecular constants, the molecular quadrupole moment Q of nitrogen and its derivative Q′ with respect to the internuclear distance at its equilibrium position were determined. The values of Q and Q′ were obtained as 1.1ea02 and 0.97ea0 respectively; the value of Q is in good agreement with that determined by previous investigators.

scholarly journals A3.4 - Measuring Flow Velocity and Gas Concentration in Binary Gas Mixtures Using Thermal Sensors

2011 ◽  
Author(s):  
Ch. Hepp ◽  
F. Krogmann ◽  
J. Polak ◽  
M. Lehmann ◽  
G. Urban ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Gas Mixtures ◽  
Thermal Sensors ◽  
Gas Concentration

An AFM Study of The Effect of Growth Method and Conditions on The Microstructure of A-Si:H

1997 ◽  
Vol 467 ◽  
Author(s):  
Daewon Kwon ◽  
J. David Cohen ◽  
Ricardo Garcia
Keyword(s):  
Grain Size ◽  
Particle Production ◽  
Chemical Vapor ◽  
Gas Mixtures ◽  
Micro Structure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Growth Method ◽  
Gas Dilution ◽  
Substrate Temperatures

ABSTRACTWe utilized atomic force microscopy (AFM) to investigate the microstructure at the surface of thick (>4000 Å) hydrogenated amorphous silicon films. The films were prepared by standard glow discharge (GD) as well as hot wire chemical vapor deposition (HWCVD) techniques. We studied a series of films with substrate temperatures ranging between 200 °C and 400 °C. We also studied the effects of various gas mixtures at fixed growth temperature on the observed microstructure. We found that the average feature grain size in the micro structure varied between 40 nm and 90 nm as the substrate temperature was changed and also as the different gas mixtures were employed during growth. The grain size decreased with increasing substrate temperatures for the films grown from 100 % silane independent of whether the growth method were GD or HWCVD. Gas dilution with argon or hydrogen also resulted in a size reduction, as did PH3 doping at dilute levels. These results rule out the possibilities that the observed features arise from particle production in the reactor chamber itself. The relation of the observed micro structure to the electronic properties of a-Si:H is discussed.

Rough Road Identification Method Based on Engine Speed Variation Rate

2013 ◽  
Vol 300-301 ◽  
pp. 959-966
Author(s):  
Yu Long Lei ◽  
Shun Bo Li ◽  
Hong Bo Liu
Keyword(s):  
Frequency Domain ◽  
Engine Speed ◽  
Threshold Value ◽  
Speed Variation ◽  
The Road ◽  
Variation Rate ◽  
The Times ◽  
Set Up ◽  
Shift Point ◽  
Two Parameters

On rough road busy-shifting often occurs when shifting law is built based on traditional two parameters (i.e., velocity and throttle). In order to resolve this problem, this paper provides a method of recognizing rough road and modifying shift point. At first, a dynamic model was set up to demonstrate the possibility of identifying rough road by longitudinal acceleration. Furthermore, advantages of the engine speed variation rate were analyzed, so engine speed variation rate distinguishing the rough road was proved better. Then the analysis of time-domain and frequency-domain of the engine speed variation rate was carried out .On the basis of the result, the method of frequency domain based on the FFT and “Cross Meter Method” based on the times of the instantaneous values of engine speed variation rate greater than the threshold value was proposed. At last, the method of modifying shift strategy was proposed on the rough road. Through the road test, it was effective to prevent busy-shifting on rough road.

Development and Experimental Validation of a Compressor Dynamic Model

2004 ◽  
Author(s):  
M. Venturini
Keyword(s):  
Experimental Validation ◽  
Test Facility ◽  
Response Analysis ◽  
Model Parameters ◽  
Modular Model ◽  
Multi Stage ◽  
Model Response ◽  
Dynamic Analyses ◽  
The University ◽  
And Control

In recent years, transient response analysis of energy systems is becoming more and more important in optimizing plant operation and control. Furthermore, dynamic analyses are also used to integrate steady-state diagnostic analyses, since they allow the detection of malfunctions characterized by time-dependent effects. The paper deals with the development of a non-linear modular model for compressor dynamic simulation. After developing the compressor mathematical model through a physics-based approach (laws of conservation and thermal balances), the model is implemented through the Matlab® Simulink tool. Then, a sensitivity analysis is carried out to evaluate the influence of model parameters on the model response. Finally, the model is calibrated on a multi-stage axial-centrifugal small size compressor running in the test facility of the University of Ferrara (Italy) and validated through experimental data taken on the compressor under investigation.

Sign in / Sign up

Export Citation Format

Share Document