JOURNAL OF SCIENCE (KHARAZMI UNIVERSITY)
Year:2002 | Volume:1 | Issue:3-4|Papers Count:9

In this paper, the numerical algorithms for solving "fuzzy ordinary differential equations" are considered. A scheme based on the 4th order Runge-Kutta method is discussed in detail and it is followed by a complete error analysis. The algorithm is illustrated by solving some linear and nonlinear fuzzy Cauchy problems.

Let R be a ring with identity, n≥1, Mn(R) be the ring of n´n matrices over R, and for each 1≤i, j≤n, Iij be a right ideal of R such that for all j,Iij=R. In the present paper we determine the structure of derivations of certain subrings of Mn(R) of the form Mn(Iij) consisting of all matrices P=[Pij] with PijÎIij for all i,j. Using this result we determine the structure of derivations of semisimple rings. Note that the latter result is an extension of a result of S.P. Coelho and C.P. Milies and a result of S. JÆndrup.

Inter-pixel correlation in natural images is very high, and it affects the indices of vector- quantized image in such a way that the probability of having neighboring blocks with an identical index, at low bit rate, is high. This paper exploited block index characteristic to achieve more compression. We can employ the proposed scheme in conjunction with any traditional vector quantization technique to obtain an improved performance. At least an improvement of 28 percent has been observed in the result of simulations reported in this paper. In addition, the performance of the new coder is significantly better than the JPEG coding standards at very low bit rates.

A part of Alburz Mountains which is located between Damghan plain (in the south) and Gorgan plain (in the north) structurally is a S-SE vergence thin-skinned fold-thrust belt. Sequential thrusting and related folding during Cimmerian and Alpine orogeny have been the most deformation style since late Triassic. Tectonostratigraphy of Alburz Based on foreland stratigraphical evolution models reveals that structural evolution of Alburz had taken place at three stages: 1) Late Triassic - Early Jurassic duo to Cimmerides; 2) Late Cretaceous - Early Paleocene duo to middle Alpine compress ional movements; 3) Neogene duo to Late Alpine compress ional movements. South - ward migration of Alburz in each stage accompanied by generation of new thrust faults, uplift and unroofing in fold- thrust belt and caused southward marine transgression and synorogenic classic sedimentation in Foreland basin. Each stage of structural evolution followed by a relaxation period that is characterized by isostatic rebound, reducing of erosion and shallow marine sedimentation in foreland basin duo to north ward marine regression.

Karkheh River is the third largest river in the west part of Iran, regarding its high flow. During raining seasons the overflow of Karkheh River destroys villages, bridges, pumping stations and farms in Khozestan plain.In this research by taking samples from water and river banks and beds, and performing different test such as conducting sediment logical and geotechnical test, the capability of marginal erosion and its causes were taken into consideration.Investigations show that the river progresses few meters per year toward the outer- bank. The reasons for this process are as follows.a. Low-grade compaction of the bank sediments. b. Differences between the compaction of the marginal layers.c. Low cohesive of sedimentary layers, which are exposed. d. The presence of disperses minerals in some layers.e. Disregarding the control factors for preventing the marginal erosion.In order to prevent marginal erosion of the river the use of plant cover, construction structures such as retaining wall, rock mesh structure or the construction of artificial cut-off are proposed.

The effect of the air pollution was studied on anther development, microsporogenesis, cellular material release, ptotein content and electrophoretic profile of polluted, non polluted and unmature pollen. In condition, in prophase I, the size of tapetum layer cells increased. These cells were vacuolated and enlarged in meiosis n. In this stage, their inner walls were degenerated into loculs and their contents transferred to separating tetrads. Eventually, in the stage of pollen development, secretory tapetum converted to plasmodial tapetum and place between developing microspores. Mature pollen is tetraporous and exine contains needle like sculptures. In polluted areas, tapetum layer and tetrads were abnormal. In some pollen, exine has less needle like sculptures and its surface becomes rough. In some other ones, it forms branched and gigantic ubnormal pollens. Pollen cellular material releasee allergens) increase in polluted conditions.Total protein content changes in polluted pollen. Electrophoretic profile between polluted and non polluted pollen doesn't show any significant difference but some difference was obvious between mature and unmature.

This research is done on 300 samples inclucting 50 samples of packed beef, 50 samples of packed chicken meat, 100 eggs throughout Tehran, consisting of 100 samples from the contents of the eggs and 100 samples from the eggs, crust. Totally 30 strain including 8 variety of serology were recognized. Complete biochemistry serology tests as well as sensitivity test were done on these, in order to obtain a suitable pattern for medical resistance.The obtained results show that salmonella Entrititidis is superior to other salmonellas, and that the most strains were resistance against two or more medicines. This kind of salmonella, which was separated from egg and chicken meat, had more resistance than other kinds with multiple resistance patterns. Tifimoryom or paratyphi salmonella had less resistance proportionate to other kinds. Although vector people and ill people have contribution in salmonella distribution, mostly this contamination is distributed through food stuff. So the issue of hygienic food and environment is of vital importance in human health. We should consider the risk of resistant strains, serious because its treatment in general infections is nearly difficult, thus it is worth attract the attention of hygienic and health centers to the importance of resistant bacteria's their distribution in environment and the risks resulted from this distribution so that excess prescription of antibiotics is prevented.

One of the Methods of scarce plants protection and proliferation as Ulmus elegantissima Jacqueline Hillier is tissue culture. U.elegantissima is a beautiful tree that is advised for parks and gardens. A micro propagation technique was developed for U elegantissima using shoots explants. Maximum shoot proliferation was obtained on MS medium supplemented with BAP (2 mg/l) and inositol (100 mg/l) from the third subculture onwards; the shoot could be multiplied by omission of inositol and reduction of BAP (1 mg/l) concentration. The best rooting response was obtained with a 24-h pulse treatment of the shoots with 1 mg/l IBA in darks and MS medium.