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Investigation on the use of raw time series and artificial neural networks for flow pattern identification in pipelinesGoudinakis, George 03 1900 (has links)
A new methodology was developed for flow regime identification in pipes.
The method utilizes the pattern recognition abilities of Artificial Neural Networks
and the unprocessed time series of a system-monitoring-signal.
The methodology was tested with synthetic data from a conceptual system,
liquid level indicating Capacitance signals from a Horizontal flow system
and with a pressure difference signal from a S-shape riser.
The results showed that the signals that were generated for the conceptual
system had all their patterns identified correctly with no errors what so ever.
The patterns for the Horizontal flow system were also classified very well
with a few errors recorded due to original misclassifications of the data. The
misclassifications were mainly due to subjectivity and due to signals that
belonged to transition regions, hence a single label for them was not adequate.
Finally the results for the S-shape riser showed also good agreement with the
visual observations and the few errors that were identified were again due to
original misclassifications but also to the lack of long enough time series for
some flow cases and the availability of less flow cases for some flow regimes
than others.
In general the methodology proved to be successful and there were a
number of advantages identified for this neural network methodology in comparison
to other ones and especially the feature extraction methods. These
advantages were: Faster identification of changes to the condition of the
system, inexpensive suitable for a variety of pipeline geometries and more
powerful on the flow regime identification, even for transitional cases.
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Investigation on the use of raw time series and artificial neural networks for flow pattern identification in pipelinesGoudinakis, George January 2004 (has links)
A new methodology was developed for flow regime identification in pipes. The method utilizes the pattern recognition abilities of Artificial Neural Networks and the unprocessed time series of a system-monitoring-signal. The methodology was tested with synthetic data from a conceptual system, liquid level indicating capacitance signals from a Horizontal flow system and with a pressure difference signal from a S-shape riser. The results showed that the signals that were generated for the conceptual system had all their patterns identified correctly with no errors whatsoever. The patterns for the Horizontal flow system were also classified very well with a few errors recorded due to original misclassifications of the data. The misclassifications were mainly due to subjectivity and due to signals that belonged to transition regions, hence a single label for them was not adequate. Finally the results for the S-shape riser showed also good agreement with the visual observations and the few errors that were identified were again due to original misclassifications but also to the lack of long enough time series for some flow cases and the availability of less flow cases for some flow regimes than others. In general the methodology proved to be successful and there were a number of advantages identified for this neural network methodology in comparison to other ones and especially the feature extraction methods. These advantages were: Faster identfication of changes to the condition of the system, inexpensive suitable for a variety of pipeline geometries and more powerful on the flow regime identification, even for transitional cases.
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Bend and orifice plate interactions and their influence on the pressure losses in internal flow systemsSalvarli, H. January 1980 (has links)
Experimental work has been carried out with a hydraulic flow test rig in which flows of water up to 65 kgs-l can be measured with a weigh-tank and its diverter valve to an accurary of ± 0.2%. The nature of the experimental work has been to investigate the system pressure losses due to the components in line (i) For interference free flow; (ii) For interactions. The components used are 90 degree circular bends and orifice plates. Bends of radius ratios from R/D - 1.49 to 4.89 and nominally standard single-hole and multi-hole orifice plates of area ratios from m – 0.170 to 0.508 have been tested. To investigate the interaction effects arising from an orifice plate in proximity to bends, various bend-orifice plate (in a few instances orifice plate-bend) combinations have been arranged. The bore diameter of duct (or pipe) and bend is approximately D – 145.05 mm and tests have been performed for Reynolds numbers ranging from Re(D) – 0.7 x 105 to 6 x 10(5). In those instances in which results from the experimental work can be compared directly with published results, agreement is good. However, many of the experimental results, particularly the measurements of interactions between bends and orifice plates, are new.
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A Theoretical and Empirical Investigation into the Application af a Cash-Flow Accounting SystemHabib, Abo-El-Yazeed Tawfik 12 1900 (has links)
The objective of this research is to make a theoretical and empirical investigation into the application of a cashflow accounting system. The theoretical investigation provides a definition for cash-flow accounting; it also examines the major arguments for a cash-flow reporting system. Three hypotheses are proposed for testing. The first states that during periods of changing prices, performance indicators that are based on the conventional accrual accounting will diverge from performance indicators that are based on cash-flow accounting and will continue to diverge over time. The second states that this divergence will disappear if the effects of inflation are partialled out. The third states that cash-flow statements, properly interpreted, will enable users to predict business failure.
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Peroxyoxalate Chemiluminescence for Miniaturized Analytical Flow SystemsJonsson, Tobias January 2003 (has links)
<p>This thesis deals with the peroxyoxalate chemiluminescence (POCL) reaction and its application as a detection technique in flow systems for chemical analysis. Particularly, miniaturized flow systems aimed for separation of molecules. In such systems, a high light intensity and a rapid development of the emission are the desired reaction characteristics, for reasons discussed in this text. The work tries to develop an understanding of the chemical processes involved in POCL, with special emphasis to the species favoring or hindering a rapid light evolution. Hence, is the focus placed on the nature of catalysis and the desired properties of substances acting as catalysts in this reaction. Consequently, the scientific papers on which this work is founded includes both systematic stopped-flow studies of catalyst candidates and of the causes for diminished light emission. In addition, multivariate strategies for reaction optimization in practical analysis situations are treated, and the application of the POCL technique to detection of serum-extracted neuroactive steroids, derivatized with fluorescent moieties, is presented.</p><p>From the experiments in this thesis it is clear nucleophilic catalysts are the most efficient enhancing compounds, which means that they must possess a carefully balanced characteristics of nucleophilicity, leaving group ability, and basicity. The investigations also conclude that the feature of basicity efficiently can be delegated to a non-nucleophilic co-catalyst, which allow the use of nucleophilic catalysts that need to be deprotonated to be active. This thesis also shows the importance of minimizing the amount of competing nucleophiles at the site of reaction to maintain the emission. This implies that also solvents and buffer substances should be carefully chosen not to interfere with the emission process.</p><p>The most promising combination of catalysts found in this work was 4,5- dichloroimidazole together with 1,2,2,6,6-pentamethylpiperidne. This arrangement was capable of speeding the reaction more than tenfold while increasing the maximum emission intensity by about the same factor.</p>
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Peroxyoxalate Chemiluminescence for Miniaturized Analytical Flow SystemsJonsson, Tobias January 2003 (has links)
This thesis deals with the peroxyoxalate chemiluminescence (POCL) reaction and its application as a detection technique in flow systems for chemical analysis. Particularly, miniaturized flow systems aimed for separation of molecules. In such systems, a high light intensity and a rapid development of the emission are the desired reaction characteristics, for reasons discussed in this text. The work tries to develop an understanding of the chemical processes involved in POCL, with special emphasis to the species favoring or hindering a rapid light evolution. Hence, is the focus placed on the nature of catalysis and the desired properties of substances acting as catalysts in this reaction. Consequently, the scientific papers on which this work is founded includes both systematic stopped-flow studies of catalyst candidates and of the causes for diminished light emission. In addition, multivariate strategies for reaction optimization in practical analysis situations are treated, and the application of the POCL technique to detection of serum-extracted neuroactive steroids, derivatized with fluorescent moieties, is presented. From the experiments in this thesis it is clear nucleophilic catalysts are the most efficient enhancing compounds, which means that they must possess a carefully balanced characteristics of nucleophilicity, leaving group ability, and basicity. The investigations also conclude that the feature of basicity efficiently can be delegated to a non-nucleophilic co-catalyst, which allow the use of nucleophilic catalysts that need to be deprotonated to be active. This thesis also shows the importance of minimizing the amount of competing nucleophiles at the site of reaction to maintain the emission. This implies that also solvents and buffer substances should be carefully chosen not to interfere with the emission process. The most promising combination of catalysts found in this work was 4,5- dichloroimidazole together with 1,2,2,6,6-pentamethylpiperidne. This arrangement was capable of speeding the reaction more than tenfold while increasing the maximum emission intensity by about the same factor.
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Pervaporation Of Organic/water Mixtures By Mfi Type Zeolite Membranes Synthesized In A Flow SystemDede, Ozlem 01 August 2007 (has links) (PDF)
Zeolite membrane synthesis is conventionally carried out in batch systems. Recently, several
attempts have been performed to synthesize zeolite membranes in flow systems which can
allow preparation of membranes with large specific surface areas.
Membranes synthesized in the recirculating flow system had comparable N2/SF6 and n-
C4H10/i-C4H10 ideal selectivities with the membranes prepared in the batch system, indicating
that good quality membranes can be produced by this method. The objective of this study is to
separate organic/water mixtures by pervaporation by using MFI type membranes synthesized
in the flow system. Effect of number of synthesis steps and synthesis method on the
separation factor and flux was investigated.
Membranes were synthesized from clear solutions with a molar composition of
80SiO2:16TPAOH:1536H2O at 95oC and atmospheric pressure. The synthesis solution was recirculated through the tubular alumina support with a flow rate of 6 ml/min for 72 h. The
membranes were characterized by X-ray diffraction for phase identification and scanning
electron microscopy for morphology determination. Single gas permeances of N2, H2, CH4,
CO2, n-C4H10 and i-C4H10 were measured between 25 and 200oC. Mixtures of 5 wt%
ethanol/water, 2-propanol/water and acetone/water were separated by pervaporation at
different temperatures.
The single gas permeances decreased with increasing temperature for weakly adsorbed gases.
For n-C4H10 the permeance passed through a maximum and i-C4H10 permeance was nearly
constant. For a membrane synthesized by two consecutive synthesis steps, the ideal
selectivity for n-C4H10/i-C4H10 was 132 at 200oC. The selectivity in the pervaporation
separation of ethanol-water mixture was 43 with a permeate flux of 0.2 kg/m2h at 25oC. With
increasing temperature, selectivity decreased but the flux increased, the selectivity was 23 and
the flux was 1.9 kg/m2h at 85oC. 2-propanol/water and acetone/water separation factors were
36 and 1024 with 0.2 and 0.1 kg/m2h fluxes, respectively. The separation factors and fluxes
for membranes synthesized in the flow system were comparable with membranes synthesized
in the batch system.
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Synthesis Of Low Silica/alumina Zeolite Membranes In A Flow SystemAkbay, Sezin 01 September 2007 (has links) (PDF)
Zeolite A-type membranes are usually synthesized from hydrogels and rarely
synthesized from clear solutions mostly in batch systems. Few studies were carried
out using semi-continuous systems for zeolite A membrane synthesis. Zeolite A
membranes are mainly used in pervaporation processes for separation of water from
water/organic mixtures because of their hydrophilic property.
In this study, zeolite A membranes were synthesized on -alumina supports from a
clear solution with a molar composition of 49Na2O: 1Al2O: 5SiO2: 980H2O.
Synthesis was done both in a batch system and in a flow system in which solution
was circulated through the support under atmospheric pressure. Effects of synthesis
temperature, time, flow rate and seeding on membrane formation were investigated.
The membranes were characterized by X-ray diffraction (XRD), scanning electron
microscopy (SEM), single gas permeation measurements and pervaporation tests.
In batch system, pure zeolite A membranes having cubic form of zeolite A was
obtained for the syntheses carried out at 60° / C for 24 h and 80° / C for 8 h.
Thicknesses of the membranes synthesized at 80° / C and 60° / C were about 2 µ / m and
4 µ / m, respectively. N2 permeances were 2*10-8 mol/m2sPa and 8*10-8 mol/m2sPa
for of the membranes synthesized in the batch system at 60° / C and 80° / C,
respectively. When synthesis was carried out in flow system pure and continuous
zeolite A membranes were obtained for all conditions. Membranes synthesized at
60° / C and 80° / C had thicknesses of about 1.5 and 2 µ / m, respectively. Lower N2
permeations were obtained for the membranes synthesized in flow system. It was
observed that flow rate and seeding did not significantly affect the thickness of the
membrane layer. The membranes synthesized in this study are significantly thinner
than the membranes reported in the literature. Single gas permeation tests at 25° / C
for the membranes showed that comparable membranes with the ones in literature
were obtained in this study. For a double layer membrane synthesized in flow
system at 80° / C for 8h separation factor about 3700 was obtained for the separation
of 92:8 (wt.%) ethanol/water mixture at 45° / C.
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Characterization Of Zeolite Membranes By Gas PermeationSoydas, Belma 01 June 2009 (has links) (PDF)
Zeolite membranes are attractive materials to separate gas and liquid mixtures.
MFI is a widely studied zeolite type due to its ease of preparation and
comparable pore size with the molecular size of many substances. In this
study MFI type membranes were synthesized over porous & / #945 / -Al2O3 supports
and characterized with XRD, SEM and gas permeation measurements.
In the first part of this study the effect of soda concentration of the synthesis
solution on the membrane morphology and crystal orientation was investigated.
The synthesis was carried out from solutions with a molar composition of (0-
6.5)Na2O:25SiO2:6.9TPABr:1136H2O at 150oC. At soda concentrations
between 0.45 and 1.8 the membrane layers with (h0h)/c-directed orientation
were obtained. At lower and higher soda concentrations membrane layer
formed from randomly oriented crystals. The (h0h)/c-oriented membranes
showed H2/n-C4H10 ideal selectivities of 478 and 36 at 25° / C and 150° / C,
respectively.In the second part, MFI membranes were synthesized from mixtures with
different concentrations of template molecules. Tetrapropylammonium
hydroxide, tetrapropylammonium bromide or mixture of both types were used
as template. The nucleation period, the size of MFI crystals, membrane
thickness decreased as the tetrapropylammonium hydroxide concentration
increased. Besides conversion of SiO2 in the synthesis solution to MFI passed
through a maximum with increasing concentration of tetrapropylammonium
hydroxide in the synthesis solution. When tetrapropylammonium bromide
was used as template thicker membranes were obtained.
In the third part MFI type membranes with a thickness of 1.5-2 & / #956 / m were
synthesized by mid-synthesis addition of silica to the synthesis medium. The
membranes synthesized with and without mid-synthesis addition of silica have
n-C4H10/i-C4H10 ideal selectivities of 47 and 8 at 100oC, respectively. The
change of composition during the synthesis increases the crystal growth rate
and the size of the crystals forming the membrane, thus better quality
membranes can be obtained by mid-synthesis addition of silica to the synthesis
medium.
In the last part of this study, thin MFI type zeolite membranes were synthesized
in a recirculating flow system at 95° / C on the inner side of the tubular & / #945 / -
alumina supports. A membrane synthesized by two consecutive synthesis steps
had a separation selectivity of 38 and 86 for equimolar mixtures of n-
C4H10/CH4 and n-C4H10/N2 at 25oC, respectively. The membrane selectively
permeated large n-C4H10 over small CH4 and N2, suggesting that the separation
is essentially adsorption-based and the membrane has few nonselective
intercrystalline pores.
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Pervaporation Of Ethanol/water Mixtures By Zeolite A Membranes Synthesized In Batch And Flow Systems(arican) Yuksel, Berna 01 January 2011 (has links) (PDF)
Zeolite A membranes have great potential in pervaporation separation of ethanol/water mixtures with high flux and selectivity. Zeolite membranes usually synthesized from hydrogels in batch systems. In recent years, zeolite membranes are prepared in semicontinuous, continuous and recirculating flow systems to allow the synthesis of zeolite membranes with enlarged surface areas and to overcome the limitations of batch system at industrial level production.
The purpose of this study is to develop a synthesis method for the preparation of good quality zeolite A membranes in a recirculated flow system from hydrogels and to test the separation performance of the synthesized membranes by pervaporation of ethanol/water mixture. In this context, three different experimental synthesis parameters were investigated with zeolite A membranes synthesized in batch system. These parameters were the composition of the starting synthesis hydrogel, silica source and the seeding technique. Syntheses were carried out using hydrogels at atmospheric pressure and at 95 ° / C. The membranes were characterized by X-ray diffraction, scanning electron microscopy and pervaporation of 90 wt% ethanol-10 wt% water mixtures.
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Pure zeolite A membranes were synthesized both in batch and flow systems. The membranes synthesized in batch system have fluxes around 0.2-0.3 kg/m2h and selectivities in the range of 10-100. Membranes with higher selectivities were obtained in batch system by using waterglass as silica source, seeding by dip-coating wiping method, and with a batch composition of 3.4Na2O:Al2O3:2SiO2:155H2O. The membranes prepared in flow system have higher pervaporation performances than the ones prepared in batch system in considering both flux and the selectivity. Fluxes were around 0.3-3.7 kg/m2h and selectivities were in the range of 102-104 for the membranes prepared in flow system which are comparable with the data reported in literature for batch and flow systems.
A high quality zeolite A membrane was also synthesized from 3.4Na2O:Al2O3:2SiO2:200H2O hydrogel at 95 ° / C for 17 hours in flow system. Pervaporation flux of this membrane was 1.2 kg/m2h with a selectivity > / 25,000 at 50° / C. Although the synthesis method is resulted with high quality membrane, reproducibility of the synthesis method is poor and it should be improved.
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