|
|
|
Volume 15, Issue 4, 2008
Chemistry and Chemical Engineering
|
|
|
|
 |
DFT/B3LYP Study of Thermochemistry
of D-Glucosamine, a Representative
Polyfunctional Bioorganic Compound
A. Fattahi (PhD.)
M. Ghorat [PhD.]
A. Pourjavadi [PhD.]
M. Kurdtabar [PhD.]
A.A. Torabi [PhD.]
Preview
Download PDF
|
|
|
D-glucosamine, as a representative polyfunctional compound, is a bioactive amino sugar. In
this study, the gas phase thermochemical properties of D-glucosamine, including its Metal Ion
Anity (MIA), metal binding sites, Anion Anity (AA), acidity and proton anity, have been
explored, using the Density Functional Theory (DFT) and a 6-311++Gbasis set. The summary
of the MIA and AA results (in kcal/mol1) are: Li+= 67.6, Na+= 51.1, K+= 37.3, Mg2+=
207.9, Ca2+= 150.4, Zn2+= 251.2, Cl= 27.4, CN= 28.0. The acidity values calculated
at dierent sites, including four -OH groups and one -NH2 group, range from 344.0 to 373.0
kcal/mol1. These results, surprisingly, indicate how drastically the presence of multiple -OH and
-NH2 groups may vary the thermochemical properties of a polyfunctional bioorganic compound,
such as D-glucosamine. |
|
|
|
|
|
|
|
|
|
|
 |
Determination of Reservoir Model from Well
Test Data, Using an Articial Neural Network
R. Kharrat (PhD.)
S.M. Razavi [PhD.]
Preview
Download PDF
|
|
|
Nowadays, neural networks have a wide range of usage in dierent elds of engineering. In the
present work, this method is used to determine a reservoir model. Model identication, followed
by parameter estimation, is a kind of visual process. Pressure derivative curves showing more
features are usually used to determine the reservoir model based on the shape of the curve
and no calculation is included. So, it is dicult to convert this kind of visual process to an
applicable algorithm for computers. In fact, the model identication is a pattern recognition
which is best done by an Articial Neural Network (ANN). If neural networks were learned
successfully, they would be able to categorize dierent shapes into dierent groups, due to their
visual characterization. So, their use in such a job would seem to be useful. In this work, it is
shown how to train, examine and use neural networks to determine a reservoir model. The input
of an ANN is fty points of the normalized pressure derivative type curve. Each ANN is trained,
based on a specic model, and the output of the ANN is the probability of occurrence of a fed
curve to the related model. |
|
|
|
|
|
|
|
|
|
|
 |
Mathematical Modeling of a
Cross Flow Conveyor Belt Dryer
E. Mirzahoseinkashani (PhD.)
N. Kasiri [PhD.]
Preview
Download PDF
|
|
|
The drying of solids in a cross
ow conveyor belt dryer (continuous operation system), in which
particles (thin-layer) move in a wire net conveyor, was theoretically studied. A mathematical
modeling that considers the in
uence of bed porosity and transient terms in the drying process
was developed and the changes in bed porosity and product density with the moisture content of
seeds have been considered. Also, to have a more accurate model, some changes have been made
to the specic surface of the seed. The nite volume method was used to solve, numerically, the
governing conservation equations. The results of the moisture content of the material (yellow
corn kernel), residence time and conveyor length are presented and analyzed in order to modify
the model, according to bed porosity, product density and the specic surface changes of the
seed. This model can predict humidity ratio, the temperature of air, moisture content and the
temperature of the material throughout the drying process. |
|
|
|
|
|
|
|
|
|
|
 |
Essential Components of an Integrated Data
Mining Tool for the Oil and Gas Industry with
an Example Application in the DJ Basin
Sh.D. Mohaghegh (Professor)
Preview
Download PDF
|
|
|
Data mining seems to be the new buzz word. During the past several years many industries
other than the oil and gas industry have realized the potential benets of da5ta mining and
have established sophisticated operations in order to implement this exciting technology in their
respective organizations. Data mining is not new. It has been around for many years. What
is new about its current implementation is the incorporation of machine learning techniques.
The oil and gas industry has become familiar with machine learning techniques since the early
1990s. Neural networks, genetic optimization and fuzzy logic have been used in numerous
applications, from well log interpretations to hydraulic fracturing optimization. Therefore, the
new interest in data mining in this industry is not surprising. The industry is at its peak state
for beneting from what data mining has to oer, thanks to an abundance of digital data. A
word of caution is in order, which is the main motivation behind writing this paper. As with
many other new tools and technologies, the term \Data Mining" can be, and is currently being,
misused on several occasions. In this paper, an attempt has been made to answer questions such
aswhat is Data Mining? How can it be accomplished? What are the essential components of
an integrated data mining process and what would be the benets of such a process? In addition
to answering questions such as those mentioned above, this paper will provide a road map (a
set of guidelines) for a successful data mining project. Finally, the paper concludes by applying
the presented guidelines to a hydraulic fracturing data set in the DJ basin of the United States
Rockies for a data mining study. |
|
|
|
|
|
|
|
|
 |
Eect of Permeable Contacts on the
Performance of a Gas-Oil Gravity Drainage
Mechanism in a Stack of Matrix Blocks
S. Nejadi (PhD.)
V.A. Sajjadian [PhD.]
Preview
Download PDF
|
|
|
In the gas invaded zone of a well fractured carbonate reservoir, gravity drainage mechanism
plays the main role in expelling oil from dense, low permeability matrix blocks. Whenever the
active mechanism is gravity drainage, reinltration and capillary continuity phenomena notably
in
uence the rate and amount of oil recovery from matrix blocks. In the current research, six
experiments were performed to study the eects of a permeable contact area (between two blocks
located on top of each other) on reinltration and capillary continuity. Two of the experiments
were performed using single blocks of 30 and 60 cm height, whilst others were stacks of two 30
cm high blocks. Results of the experiments reveal that, by increasing the permeable contact area
between blocks, due to capillary continuity and reinltration, there will be more communication
between them, consequently, both ultimate oil recovery and production rate will improve. It is
also noticeable that, if the permeable contact area is approximately greater than 20% of the total
block surface area, the stack of blocks behaves analogous to a unique block with a height equal
to that of the stack. The outcome of the present work, along with data from other studies, such
as the eects of horizontal fracture apertures and fracture dips, can be utilized in order to have
a better understanding of block to block eects. By this, the modeling of the gravity drainage
mechanism, while injecting gas into fractured carbonate formations, would be improved. |
|
|
|
|
|
|
|
|
 |
Determination of Traces of 2,4-Dichlorophenoxy
Acetic Acid in Environmental Samples
A. Safavi (PhD.)
N. Maleki [PhD.]
F. Hasanpour [PhD.]
H.R. Shahbaazi [PhD.]
Preview
Download PDF
|
|
|
drop electrode in aqueous media and in the presence of Britton-Robinson buer as the electrolyte.
In this study, the electroinactive 2,4-D was rst converted to electroactive nitrated 2,4-D.
Subsequent determination was carried out by dierential pulse polarography. Under optimum
conditions (pH = 11 = 90 mV s1modulation amplitude = 120 mV), the relative standard
deviation was 4.5% and limit of detection in terms of nitrated 2,4-D was 5 g L1 (1:88108 M)
with linear concentration range from 8 to 300 g L1(3108 1:12106M). The proposed
method oered high sensitivity as well as good selectivity. A mechanistic study, showed fourelectron
reduction of nitrated 2,4-D to its hydroxylamine derivative. The proposed method was,
also, applied to the determination of 2,4-D in environmental samples such as soil samples. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
Application of Response Surface Methodology
in Study of the Product Yield Distribution
of Thermal Cracking of Atmospheric Gasoil
J. Towfighi (PhD.)
S.Z. Abghari [PhD.]
R. Karimzadeh [PhD.]
M. Omidkhah [PhD.]
Preview
Download PDF
|
|
|
In order to determine the yield distribution of thermal cracking of gasoil, a pilot plant was
designed and setup. A systematic experimental design was utilized based on CCD (central
composite design). The feed
ow rate, steam ratio and temperature were considered as factors
to design the experiments. Some statistical models were tuned based on the results of conducted
experiments. The models were evaluated with lack-of-t and R-squared tests. The results of
the analysis proved that the models tted well with the experimental results of the considered
products. Based on the experiments and statistical models the pilot plant was optimized in order
to maximize the net prot. At the optimum point coil outlet temperature, the feed
ow rate
and steam ratio were, respectively, equal to 843.8C, 6.02 g/min and 0.46. Regarding these
conditions, the yield of ethylene, propylene and butadiene and rate of coke formation would be
23.82 wt%, 12.13 wt%, 2.42 wt% and 14:44 107 g/cm2.sec, respectively. |
|
|
|
|
|
|
|
|
 |
Feed Stu Production from Methanol
by Methylotrophic Microorganisms
G.M. Zamani (PhD.)
P. Jafari [PhD.]
F. Almasian [PhD.]
B. Medi [PhD.]
N. Ghaemi [PhD.]
A. Nohi [PhD.]
S. Mehrabian [PhD.]
Preview
Download PDF
|
|
|
Methanol has been of great interest as a substrate for production as a novel feed grade protein
in Iran. Up to 160 methylotrophic strains were isolated at the Jahad-e Agriculture Research
Engineering Center for Scientic Research and various batch experiments were carried out at
dierent pH, temperature, agitation, aeration rate and methanol concentrations. By these
experiments, optimum production conditions were determined for one of the strains using the
Taguchi method. The results showed optimum pH around 8 at temperatures of 26 to 30C,
aeration equal to 3 vvm and agitation about 800 rpm. The methanol was found to be optimum
at concentration equal to 18 g.l1 . In this condition, the biomass yield coecient was 0.52
g/g methanol, biomass dry weight was 20-25 g/l and the crude protein content was about 70-
78%. A deep jet fermentor of 1 m3 capacity, with a working volume of 600 liters, was used for
SCP production using isolated strains. In this continuous system, dilution rates ranging from
0.15 to 0.2 lit.h1 were used to establish optimal condition for biomass production. Under
this condition, 30 kg cell dry weight per day was obtained. These experiments showed that
the selected methylotrophic strain has good potential for SCP production from methanol as a
substrate. |
|
|
|
|
|