eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
1994-05-01
7
2
61
74
71098
The Role of Aldehydes as Degenerate Branching Intermediate in the Oxidation of Hydrocarbons
K. Hessam
hasnomail@ije.ir
1
Chemical & Petroleum Engineering, Imperial College of Science and Technology
The thermal oxidation of propane in the temperature range 350-425oC was studied in order to elucidate the role of higher aldehydes as degenerate branching intermediates in the oxidation of hydrocarbons. In the slow combustion of propane, the high yield of propylene and methanol as the primary products, the formation of hydrogen peroxide, carbon monoxide, carbon dioxide, formaldehyde and steam as the final products and the presence of propylperoxy radicals and acetaldehyde as the branching intermediate are confirmed. The effect of the addition of small quantities of acetaldehyde to propane! oxygen mixtures was being monitored for the reduction and removal of the induction period and also changes in the maximum rate using mass spectrometry. It is concluded that the higher aldehydes and, in particular, acetaldehyde, are the degenerate branching agents in the combustion of hydrocarbons. An activation energy of 161 KJ mole-' was measured for propane oxidation which decreased when the reaction was initiated by acetaldehyde. The reaction kinetics as well as the mechanistic feature of the propane/oxygen mixture and the competitive oxidations of propane-acetaldehyde system have been investigated. The kinetics data obtained by the mass spectrometer have been analysed by computer programming and the results were represented by the appropriate kinetics plots.
https://www.ije.ir/article_71098_2ff03219548b2c2aa5be564e1a0221b0.pdf
Combustion
Thermal Oxidation
Degenerate Branching
Organic Fuels
Ignition
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
1994-05-01
7
2
75
84
71099
Optimal Design of Geometrically Nonlinear Structures Under a Stability Constraint
S. Pezeshk
hasnomail@ije.ir
1
Civil Engineering, Memphis State University
This paper suggests an optimization-based methodology for the design of minimum weight structures with kinematic nonlinear behavior. Attention is focused on three-dimensional reticulated structures idealized with beam elements under proportional static loadings. The algorithm used for optimization is based on a classical optimality criterion approach using an active-set strategy for extreme limit constraints on the design variables. A fixed-point iteration algorithm based on the criterion that at optimum the nonlinear strain energy is equal for all members is used. Several examples are given to evaluate the validity of the underlying assumptions and to demonstrate some of the characteristics of the proposed procedure.
https://www.ije.ir/article_71099_7bc542c915fa43ed6561f83efe2b3f43.pdf
Optimal design
Optimality Criteria
Stability Constraints
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
1994-05-01
7
2
85
94
71100
A Two Level Approximation Technique for Structural Optimization
Eysa Salajegheh
eysasala@mail.uk.ac.ir
1
Civil Engineering, Shahid Bahonar University of Kerman
This work presents a method for optimum design of structures, where the design variables can he considered as Continuous or discrete. The variables are chosen as sizing variables as well as coordinates of joints. The main idea is to reduce the number of structural analyses and the overal cost of optimization. In each design cycle, first the structural response quantities such as forces, displacements, etc. are approximated as functions of the design variables or some intermediate variables. By employing these approximated quantities, an explicit approximate problem will be available, which is in general a nonlinear programming problem. Now, this approximate design task is transformed into a number of second level approximation of separable froms, each of which can be solved by a dual strategy with continuous or discrete variables. The objective of the first level approximation is to reduce the number of structural anlyses required in the optimization problem and that of the second level approximation is to reduce the computational cost of the optimization technique. Two examples are offered to demonstrate the efficiency and reliability of the proposed method.
https://www.ije.ir/article_71100_5c9b59f45a7e17618b2298aa3768de2c.pdf
Structural Optimization
Approximation Technique
Discrete Variables
Dual Methods
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
1994-05-01
7
2
95
110
71101
Neural Network Modelling of Optimal Robot Movement Using Branch and Bound Tree
S. Khanmohammadi
khan@tabrizu.ac.ir
1
Electerical Engineering, University of Tabriz
In this paper a discrete competitive neural network is introduced to calculate the optimal robot arm movements for processing a considered commitment of tasks, using the branch and bound methodology. A special method based on the branch and bound methodology, modified with a travelling path for adapting in the neural network, is introduced. The main neural network of the system consists of different subnets, each of which is designed for a special propose. The common neuron for competitive layers and the state presentation neurons for different layers are also presented and used in the design of neural network architecture. Sigma P1 neurons are used to increase the calculation's performance. A case study with different commitments of tasks is simulated and the results are compared with Hopfield and Tank net from different view points.
https://www.ije.ir/article_71101_2db276aad3a417e1836645f7e4b24984.pdf
Branch and bound
Sequence Path
Compatative NNT
Cyclic Competition
Sigma PI Neurons
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
1994-05-01
7
2
111
118
71102
A Procedure for Building Confidence Interval on the Mean of Simulation Output Data
S.T.A. Niaki
niaki@sharif.edu
1
Industrial Engineering, Sharif University of Technology
One of the existing methods to build a confidence interval (c.i.) for the mean response in a single steady state simulation system is the batch means method. This method, compared to the other existing methods (autoregressive representation, regenerative cycles, spectrum analysis, standardized time series), is quite easy to understand and to implement and performs relatively well. However, the most serious source of error is the underestimation of the variance of the sample mean due to the correlation of batch means. In the new method, which is essentially based on the batch means approach, weights are assigned to the batch means such that they become uncorrelated. Then based on the assumption that the output data are obtained from steady-state simulation, as expression is developed for obtaining the confidence interval on the mean.
https://www.ije.ir/article_71102_fc99583a903d1483927f802f3f3e6a16.pdf
Simulation
Output Analysis
Batch Means
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
1994-05-01
7
2
119
123
71103
Determining the Proper compression Algorithm for Biomedical Signals and Design of an Optimum Graphic System to Display Them (TECHNICAL NOTES)
H. Movahedian
hasnomail@ije.ir
1
S.A. Motamedi
motamedi@aut.ac.ir
2
Engineering, Amirkabir University of Technology
Electerical Engineering, Amirkabir University of Technology
In this paper the need for employing a data reduction algorithm in using digital graphic systems to display biomedical signals is firstly addressed and then, some such algorithms are compared from different points of view (such as complexity, real time feasibility, etc.). Subsequently, it is concluded that Turning Point algorithm can be a suitable one for real time implementation on a microprocessor-based graphic system. The remainder of the paper is devoted to a discussion of a Biomedical Signals-Display System using aGraphic Display Processor (GDP). This section includes a brief introduction of 9365 GDP, as well as some features of a Z 80 - based ECG data display system employing this chip.
https://www.ije.ir/article_71103_54adfd89caa09b7b1f52b6ec06697c5b.pdf
Compression Algorithm
real
Time Display
Turning
Point Algorithm
Biomedical Signals
ECG Signals