Materials and Energy Research Center
International Journal of Engineering
1025-2495
1
2
1988
08
01
Chained Vector Simplex
79
84
70980
EN
S.
Khanmohammadi
Electerical Engineering, University of Tabriz
Journal Article
1970
01
01
An algorithm for solving linear programming problems whose matrix of coefficients contains a large number of "zero" entries is studied. This algorithm is more useful when it is generated as a sub-program in a real-time program. The singly linked lists for storing only the non-zero entries of the coefficients matrix is used. The modified Revised Simplex Method is also used for solving such problems because of its advantages.
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1
2
1988
08
01
A Microcomputer-Based Simulator for Digital Control Systems
85
96
70981
EN
B.
Farhang-Boroujeny
Electerical Engineering, Isfahan University of Technology
Journal Article
1970
01
01
A microcomputer-based simulator for digital control systems is proposed. The proposed simulator is a hybrid system in which the plant is simulated by conventional method of analog computers and other parts of the system including generation of input signal is performed digitally, using a Z-80 based microcomputer. To overcome the difficulty of programming in assembly language, and at the same time to have a fast system, a special purpose simulating language is suggested. Examples of programming in the new language are also presented.
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1
2
1988
08
01
Connectivity as a Measure of Power System Integrity
97
110
70982
EN
R.
Schinzinger
, University of California
A.
Peiravi
Electerical Engineering, Ferdowsi University of Mashhad
Journal Article
1970
01
01
Measures of network structural integrity useful in the analysis and synthesis of power systems are discussed. Signal flow methodology is applied to derive an expression for the paths between sources and sinks in a power network. Connectivity and reach ability properties of the network are obtained using the minors of a modified connectivity matrix. Node-connectivity, branch connectivity and mixed connectivity of power system are discussed.
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1
2
1988
08
01
Reoxidation Rate of Sponge Iron Pellets, Briquettes and Iron Powder Compressed to Various Compressions in Air
111
116
70983
EN
N.
Towhidi
Materials Engineering, University of Tehran
Journal Article
1970
01
01
The reoxidation rate of sponge iron pellets and briquettes and oxidation of pure iron powder with compressibility between 27% and 55% in air and within the temperature range 300-900°C has been investigated. Factors affecting the oxidation rate are presented. These include the effect of temperature, compressibility, and sintering of Fe-powder before and during the oxidation.
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1
2
1988
08
01
Flow and Pressure Distributions in Short Heat Exchanger Cores with Abrupt Entrance and Exit
117
128
70984
EN
Esmaeil
Khoshravan-Azar
Mechanical Engineering, University of Tabriz
Journal Article
1970
01
01
The typical installation of a heat exchange device usually involves a flow contraction at the core entrance and a flow expansion at the core exit. Repeated flow Contraction and expansion are experienced in the flow passages of some compact heat exchangers. The latter refers to the flow passages in the plate-fin type with louvered fins or stripped fins and in the tubular type with dimpled-circular or flat tubes. Similar flow situations are encountered in flat-edged orifices. The majority of these constrictions are characterized by small length-to-hydraulic diameter ratio so that the flow after being disrupted has a little time in developing into an appropriate pattern before it is disrupted again. This work deals with a flow system consisting of a parallel channel with a flow constriction of small . The flows at both ends of the channel are laminar, fully developed. The full Navies-Stokes equations for the steady two-dimensional flow are solved numerically using the finite-difference technique. Some preliminary results are obtained for the distributions of velocity components, streamline and pressure. The result for a flow of small Reynolds number show qualitative agreement with the flow pattern of a similar flow system obtained by visualization method.
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1
2
1988
08
01
Longitudinal Conduction in Cross Flow Heat Exchanger with Condensation
129
138
70985
EN
A. A.
Rostami
, Isfahan University of Technology
Journal Article
1970
01
01
The deterioration of the performance of a cross flow heat exchanger with condensation due to the longitudinal conduction was investigated. For a relatively small change of wall temperature along the flow directions which was shown to be common in many applications, the energy equations were solved numerically. An iterative method was used to solve the resulting equations of the finite difference form in Order to obtain the hot fluid, the cold fluid and the wall temperature distributions and the exchanger thermal effectiveness. A comparison was made between the effects of longitudinal conduction on the exchanger performance, without and with condensation. The results indicated that with the same values of NTU, the capacity ratio and the conduction parameter, λ, the performance deterioration of a cross flow heat exchanger with condensation is not as strong as the case of pure heat transfer.
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1
2
1988
08
01
Simulation of Low Reynolds Number Isotropic Turbulence Including the Passive Scalar
139
148
70986
EN
Ebrahim
Shirani
Mechanical Engineering, Isfahan University of Technology
Journal Article
1970
01
01
Full simulations of homogeneous isotropic turbulence containing a homogeneous passive scalar were made at low Reynolds numbers and various Prandtl numbers. The results show that the spectral behavior of the two fields are quite similar; both fields decay as power-law functions of time. However. the decay exponent is quite dependent on both the Reynolds and Prandtl numbers. The decay exponent of the velocity field seems to felt off somewhat faster as a function of Reynolds number than experiments indicate. The behavior of the velocity derivative skew ness is in good agreement with the experimental results but indicates a different trend with Reynolds number than the experiments.
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1
2
1988
08
01
Resurgent Cauldrons and Their mineralization between Narigan, Esfordi, Kushk, and Seh Chahoon, Central Iran
149
161
70987
EN
S.
Sennewald
, RWTH Aachen University
Journal Article
1970
01
01