Year:2003 | Volume:36 | Issue:4 (78)|Papers Count:11

Ferric chloride and alum are the two coagulating substances, which are used for the elimination of organic matters and turbidity of water. The power of coagulation and suitable pH range of ferric chloride is more than alum. However, the concern and precaution about the use of ferric chloride is its severe corrosiveness. In this work, alum and ferric chloride were used as coagulating matters for Isfahan and synthesized water. The corrosion rate of copper in synthesized water containing chloroform for adjusting the organic material concentration in water with the added concentrations of coagulating material in there different pH were evaluated. In addition, the corrosion rate of copper in Isfahan water containing different concentrations of coagulating matter were investigated. The results indicated that the water with pH=6.5 had an optimum concentration 4 ppm for ferric chloride, which was equivalent to 6 ppm for alum. In pH=7.5, the optimum concentration was 6 ppm for ferric chloride which was equivalent to 12 ppm for alum. In pH=9, the optimum concentration was found to be 12 ppm for ferric chloride which was equivalent to 24 ppm for alum. An optimum concentration of ferric chloride is a concentration in which the corrosion rate of copper in water is qual or even less than that in the equivalent concentration of alum. In Isfahan water in pH=7, the optimum concentration of ferric chloride is 5 ppm which is equivalent to 10 ppm of alum.

The ultra spherical polynomials form a orthogonal system on I=[-1,1] for the measure dμα(x)=(1-x2)α dx for α>-1/2 . The Gegenbauer's multiplication formula shows that the Gegenbauer Kernel is stochastic. By means of the Gegenbauer Kernel we construct a Markov operator Pα,x and by using the abstract result for a Markov Operators we prove its asymptotic stability for o≤ α ≤1/2. This result will be generalized for all α≥1/2 by use of the Harmonic analysis techniques

Dynamic equation of a simply supported beam with a lump mass in the midspan subjected to harmonic axial excitation, whose one end can move along the beam freely, is a nonlinear differential equation with no explicate solution. In this article we start extracting the equation of motion. Existence of periodic solution, under some condition, are investigated and proved using green function and Schaunders fixed point theorem; also noting into the structure of differential equation of motion, existence of oscillating response investigated, independently. By this analysis, it becomes possible to predict whether the solution converges to a point (zero) or a periodic answer

For any fixed integers m, n, with m≥n+1, we consider classes of graphs, that are n-connected with the minimum number of edges. Gmn Graphs are examples of graphs with maximum connectivity. This property makes them useful to network designers and thus it is of interest to study the behavior of other stability parameters for these graphs. In this paper we study the tenacity of the Gmn when "m" is even and "n" is odd number.

The application of the transfer function is discussed at present as a method for on-site monitoring and diagnoses of power transformers with regard to mechanical damages of the winding. In order to be able to evaluate the measurements, the correlation between the characteristics of transfer functions and possible damages must be known. Radial deformation of transformer windings have been studied experimental and theoretical. The primary winding of the test transformer has 30 double disk coils (1.2 MVA, 10 kV) and the secondary is a one layer winding with 23 turns (1.2 MVA, 400 V). A detailed mathematical model was developed for the test object and a comparison between measured and calculated results was carried out. A numerical method for the calculation of inductances is suggested, which is independent of the shape of the windings turns. For the calculation of the earth capacitances a relationship is given. An independent simulation confirmed the accuracy of this relationship by using finite elements method. It is shown that the developed model can represent the behavior of transformer windings in the frequency domain in case of sound and deformed conditions.

Researchers have shown that appropriate heating of the cancer cells during the mitosis damages and kill them. This is referred to as hyperthermia cancer therapy. In this process, it is crucial to focus the heat on the cancerous tissue (target) so that the surrounding normal tissue is not damaged by the therapy. Several methods have been proposed for hyperthermia treatment; ultrasound is most commonly proposed and applied, and is the focus of our research. Phased arrays are the means to focus the ultrasound beam and concentrate the ultrasound energy on the target tissue. This paper presents design, development, and evaluation of our ultrasound phased array system for hyperthermia therapy. The system is controlled by a computer and consists of both hardware (phased array and electronic circuits) and computer software. Based on the effective errors measured in the system evaluation phase, we have developed approaches to mitigate the errors. These approaches add voltage and phase feedback to the system. Experimental results illustrate that the most appropriate response is obtained using the phase feedback approach.

Separation units are one of the most important parts in the chemical processes, and distillation towers are one of them. In recent years, reactive distillation has received a great attention in optimization of the process and has got a good development. In order to evaluate a reactive distillation system, MESH equations are solved and with the results out of this calculation, composition, temperature, and pressure are evaluated. MESH equations are nonlinear in nature and their solution is very crucial and, therefore, conventional methods are not reliable to solve this system. Therefore, in this work it has been tried to use Homotopy continuation method to find the solution. Homotopy Continuation can guarantee with any initial guess and it can be applied to other process design problem.

The high annual rate of production of rice bran in our country usually results in accumulation of a large quantity of bran. This fact promoted us to evaluate different sample of rice bran for oil constituents. This research work was the extraction of oil from different varieties of bran collected from the North and the Southern parts of Iran. The total oil content, the quantity and their suitability for use as edible oil and/or in soap manufacturing were compared. Based on their resolution power and solvents availability, n-hexane was eventually selected as the suitable extraction solvent. The extracted oil was desolventized in the vacuum rotary evaporator. Analysis of this oily fraction showed the presence of oleic acid as the major constituents. All the extracted oil samples were analyzed for a number of parameters like PH, Iodine number, Specification number etc followed by decolonization using activated carbon and/ or acid activated clay toward final purification. Based on our results and findings, the oil samples obtained were edible but the total oil content of the Northern samples were higher than the those collected from the South of Iran. The oil content of these samples was ranged from 1.2 to 5.3 percent. Therefore, rice bran can be considered as an alternative source of edible oil which may be used in preparation of foodstuffs and dietary supplements.

In this work, a rotary regenerator is simulated by solving a developed mathematical model and optimized. A novel experimental rotary wheel has been designed and setup in the laboratory scale. The effects of parameters on the system performance have been investigated using an experimental design method. A new model for the system efficiency in which three parameters (rotor speed, hot and cold stream flow rates) are involved has been presented for the prediction of the rotary regenerator performance

The objective of present research work was the study of sodium nitrite function as an anodic inhibitor on corrosion behavior of mild steel in concrete. For this purpose, cyclic potentiodynamic polarization technique was applied on steel in Simulated Concrete Pore (SCP) solution. The experimental results illustrated that the presence of nitrite ions in solution containing Cl- will form a passive film on the metal surface and consequently, potential of pit nucleation, Epit, would be considerably increased in positive direction. However, with increasing sodium nitrite concentration, at first the protection potential of pits, Epro, is increased and then it remained constant. For this reason the Epro didn't come up to Epit. So the pits werent entirely repaired. The microscopy of the surface after cyclic polarization confirmed the electrochemical observation.

Effect of Hydrogen on Mechanical Behavior, strength and ductility properties and related fracture mechanisms in a low carbon and low alloy 2.25 Cr- 1 Mo biotitic steel were studied. Entrance of hydrogen into the microstructure was done by cathodic charging in 1N sulfuric acid containing arsenic trioxide as a catholic poison. Immediately after catholic hydrogen charging, slow strain rate testing (SSRT) at strain rates of 10-6 to 10-4s-1, as well as ordinary tension test and sustained load test were performed. Fractographic investigation were performed using stereo and scanning electron microscopes. The process of hydrogen charging into the alloy steel brings about reductions in strength and ductility properties leading to a completely brittle mechanical behavior. The results of fractographic studies showed that hydrogen induced cracking was initiated at subsurface inclusion-matrix interfaces, which initially propagated by an inter-granular cracking mechanism, and was followed by extensive low energy quasi-cleavage mode at later stages of crack growth. Crack growth mechanisms under various testing conditions are presented in a schematic model and discussed.