Bioreactor Scale-up for Water-Gas Shift Reaction
E. C.
Clausen
Chemical Engineering, University of Arkansas
author
R.
Basu
Chemical & Petroleum Engineering, University of Arkansas
author
Ghasem
Najafpour
Biochemical & Chemical Engineering, Noshirvani University of Technology, Babol
author
text
article
1996
eng
A scale-up study has been performed with three different size reactors to establish the optimum operating conditions for the hydrogen production from synthesis gas by biological water-gas shift reaction using the photosynthetic bacterium Rhodosprilliunt rubrum. Optimum medium composition and operating conditions previously determined in a bench scale 1.25 L continuous stirred tank reactor (CSTR) were used for this study with geometrically similar 2.5, 5.0 and 14.0 L CSTR. The hydrogen production rate, cell concentration and carbon monoxide (CO) conversion were monitored in this scale-up study. The light energy supply was linearly increased with the working volume of the reactors. The agitation rates were determined by the equal power/volume rule. There were good agreement between the calculated agitation rates and the experimentally observed values for all the three different reactors, A 70% carbon monoxide conversion was obtained with 30, 60 and 150 sccm gas flow rate for the 2.5, 5.0 and 14.0 L fermentors respectively. At 70% CO conversion the 2.5 and 5.0 L reactors showed 25% improvement ir~ performance and the 14.0 L reactor showed 11% improvement. The estimated mass transfer coefficients for all four reactors showed very similar values under the optimum operating condition (average KLa= 117 h-1). A 664 h long performance of the process show very stable behavior.
International Journal of Engineering
Materials and Energy Research Center
1025-2495
9
v.
3
no.
1996
121
129
https://www.ije.ir/article_71153_e3fd84e1fba21b9a1cba2eef0b127c06.pdf
Concepts and Application of Three Dimensional Infinite Elements to Soil Structure-Interaction Problems
J.
Noorzaie
Civil Engineering, university putra Malaysia
author
text
article
1996
eng
This study is concerned with the formulation of three dimensional mapped infinite elements with 1/r and 1/ decay types. These infinite elements are coupled with conventional finite elements and their application to some problems of soil structure interaction are discussed. The effeciency of the coupled finite-infinite elements formulation with respect to computational effort, data preparation and the far field representation of the unbounded domain is investigated and brought out.
International Journal of Engineering
Materials and Energy Research Center
1025-2495
9
v.
3
no.
1996
131
142
https://www.ije.ir/article_71154_f7b855d0212cd6cb06a538e90e6d0ec9.pdf
The Study of Breakdown Voltages for Triggered Spark Gap Switches
H.
Golnabi
Water & Energy, Sharif University of Technology
author
text
article
1996
eng
This study explains the breakdown mechanism in different triggered spark gap switches. Two different trigger electrode configurations are tested for the switch predischarge operation in a nitrogen laser circuit. The behavior of the breakdown voltage, when a trigger pulse is applied to the trigger electrode, is investigated, and the results are reported. Based on the experimental measurements new empirical expressions for breakdown voltages are obtained. The self triggered breakdown voltage is also calculated and the differences between the self triggered and external triggered breakdown voltages are reported.
International Journal of Engineering
Materials and Energy Research Center
1025-2495
9
v.
3
no.
1996
143
150
https://www.ije.ir/article_71155_cc44358f068c5262c841c0426b5281bc.pdf
Neural Network Implementation of a Three Phase Regulated PWM AC to Dc Convener with Input Unbalance Correction
H. R.
Mohammadi
Electerical Engineering, University of Tabriz
author
S. H.
Hosseini
Electerical Engineering, University of Tabriz
author
text
article
1996
eng
Under unbalanced supply condition low order harmonics will appear at the input and output terminals of the PWM AC to DC converter. Based on the positive and negative sequence components, an unbalanced transfer matrix in terms of the input phase voltages is derived. An on-line method using a neural network (NN) is used to implement this transfer matrix. It is shown that by using an additional load feedback loop the unbalance correction property is not affected.
International Journal of Engineering
Materials and Energy Research Center
1025-2495
9
v.
3
no.
1996
151
158
https://www.ije.ir/article_71156_463133292dac65b84cf7d25f0041e694.pdf
Rcd Rules and Power Systems Observability
N. M.
Tabatabaei
Electerical Engineering, Iran University of Science & Technology
author
H. A.
Shayanfar
Electerical Engineering, Iran University of Science & Technology
author
text
article
1996
eng
Power system state estimation is a process to find the bus voltage magnitudes and phase angles at every bus based on a given measurement set. The state estimation convergency is related to the sufficiency of the measurement set. Observability analysis actually tests this kind of problem and guarantees the state estimation accuracy. A new and useful algorithm is proposed and applied in this paper for power system observability. Through the use of this practical method, one can test the observability of power systems for a specific measurement set. In this new method, which we call Row-Column Diagonal (RCD) method, the electric power network is transformed to a useful graphical network named pseudo-network and then observability study is applied. This new method is implemented on some example networks which are already tested.
International Journal of Engineering
Materials and Energy Research Center
1025-2495
9
v.
3
no.
1996
159
168
https://www.ije.ir/article_71157_9430f89aa5475ffe9b0372976feb8edb.pdf
Queue with Heterogeneous Server Under Resequencing Constraint
I.
Dhyani
Mathematics, D.A.V. (PG) College
author
Madhu
Jain
Department Of Mathematics, IIT Roorkee,Roorkee,India
author
text
article
1996
eng
In this paper, a markovian queue with two types of servers and buffer space is considered. The resequencing constraint is imposed according to which the customers leave the system in the same order in which they entered it. For finite buffer queue, the steady state queue size distribution has been obtained.?
International Journal of Engineering
Materials and Energy Research Center
1025-2495
9
v.
3
no.
1996
169
174
https://www.ije.ir/article_71158_aad14b8ba8a0872b4252fff41e7965b3.pdf
Confidence Interval Estimation of the Mean of Stationary Stochastic Processes: a Comparison of Batch Means and Weighted Batch Means Approach (TECHNICAL NOTE)
S.T.A.
Niaki
Industrial Engineering, Sharif University of Technology
author
text
article
1996
eng
Suppose that we have one run of n observations of a stochastic process by means of computer simulation and would like to construct a condifence interval for the steady-state mean of the process. Seeking for independent observations, so that the classical statistical methods could be applied, we can divide the n observations into k batches of length m (n= k.m) or alternatively, transform the correlated batch means vector into an independent vector. These methods are known as (ordinary) batch means and weighted batch means, respectively. In this paper, using the probability of coverage and the half length of a confidence interval as criteria for comparison, we empirically show that weighted batch means is superior to ordinary batch means, and that it is less sensitive to batch sizes and total number of observations.
International Journal of Engineering
Materials and Energy Research Center
1025-2495
9
v.
3
no.
1996
175
179
https://www.ije.ir/article_71159_68e8af29e53dbb1b10f7784bbd84afca.pdf