This paper proposes to use variable time steps in CIRCUIT ENVELOPE simulation. The CIRCUIT ENVELOPE is a general-purpose simulation technique for the transient and steady state analysis of microwave communication systems and CIRCUITs. When a microwave CIRCUIT is excited with a time variant ENVELOPE signal as digital modulated signal, CIRCUIT ENVELOPE simulation method may be used. In this paper a new technique is proposed to improve the efficiency of the CIRCUIT ENVELOPE simulation. Using this technique, a millimeter wave power amplifier is simulated and its results are presented. The evaluation of the results with the existing literature proves the accuracy and efficiency of the new technique.

The purpose of this research was to investigate and compare the performance of a synthetic drainage ENVELOPE material with a granular ENVELOPE material vastly used in drainage projects of the region. This study was conducted in the soil and water research laboratory of Chamran University. Upward flow cylinder infiltrometers was used in these experiments. Granular ENVELOPE was designed according to USBR recommenedations, and synthetic the ENVELOPE used was PP450. Drain outlet discharge variation, soil-ENVELOPE hydraulic conductivity under fixed hydraulic head and gradient ratio (GR) in the two ENVELOPEs were measured and compared. The results of GR test indicated that clogging potential was greater in the synthetic ENVELOPE. In regard to hydraulic conductivity, the performance of both ENVELOPEs was acceptable and could be used as drainage ENVELOPE material satisfactorily. Under all hydrylic heads used in these experiments, drain outlet discharge for the granular ENVELOPE was higher than synthetic ENVELOPE material.

Background and Objectives: The effect of mineral clogging by soil particles is one of the main factors affecting the performance of drainage systems. Many drainage systems designs do not pay attention to laboratory and local studies on certain important parameters and some of them use to be specific for a given conditions. Several studies carried out in The Netherlands have shown that nearly 80% of drainage projects’ failure happens as a result of inappropriate performance of drain filters. Since field studies in order to evaluate drain ENVELOPEs is not economical from viewpoint of time and cost. Therefore laboratory evaluation is proper for ENVELOPEs. The main goal of this study was obtaining a set of empirical equations in order to estimate hydraulic and clogging parameters using hydraulic head and discharge through drains which are easy to measure. Removing the effect of piezometers installed the Permeameter was another goal.Materials and Methods: To conduct this research, The Permeameter which designed and was made according to ASTM-5101 standard, was used PP-450 and gravel ENVELOPE were evaluated according to USBR standard. Required soil for this experiment was collected from a drainage project in the north of Khorramshahr at 1.65 m depth. The test was conducted in laboratory using Permeameter by producing 4 different hydraulic pressure head (25, 50, 75, 100 cm). In this study, special parameters (ENVELOPE hydraulic conductivity, soil hydraulic conductivity, soil-ENVELOPE hydraulic conductivity, gradient ratio) were calculated by measurement of outflow changes in soil ENVELOPE system and hydraulic pressure head of manometer.Results: After the tests were completed, the values of hydraulic conductivity for soil-ENVELOPE system, soil and geotextile ENVELOPE were estimated as functions of hydraulic head and outflow values. Furthermore, other relations were proposed for gradient ratio. The relations between different parameters were analyzed by Sigma Plot software and proper relations were proposed. The errors of the fitting equations and the difference between measured and estimated values were analyzed using the statistic indices. Results showed that these models are accuracy estimation of assessed parameters.Conclusion: Correlation coefficient of these equations for pp450 ENVELOPE for soil-ENVELOPE hydraulic conductivity, soil hydraulic conductivity, ENVELOPE hydraulic conductivity and gradient ratio are 0.96, 0.96, 0.62 and 0.96 respectively and for gravel ENVELOPE for soil-ENVELOPE hydraulic conductivity, soil hydraulic conductivity and ENVELOPE hydraulic conductivity are 0.98, 0.98 and 0.63 respectively. Low correlation coefficient for estimation of ENVELOPE hydraulic conductivity is related to ENVELOPE clogging during experiment time. Using of proposed equations can be estimate clogging and hydraulic performance of drainage ENVELOPEs in different conditions.

Let R be a commutative ring with identity and M a unitary R-module. The concept of prime submodule of an R-module M has been discussed. In this paper, we investigate the concept of semiprime submodule of an R-module M. We also, consider relation between the semiprime submodule N of an r-module M and the semiprime ideal (N: M) of R and we focus our attention on relation between E (N) and N.

Argerami and Farenick have found conditions for the injective ENVELOPE of a separable C∗-algebra to be a von Neumann algebra. In this paper, we introduce an equivalent version of this result by finding conditions for the G-injective ENVELOPE of a separable G-C∗-algebra A to be a von Neumann algebra, when G is a discrete group acting on A.

According to General Circulation Model (GCM), zonal thermal belts are 1- Inter-Tropical Convergence Zones (ITCZ) around eqator; 2- Sub Tropical High (STH) belt around 30 degree latitude; 3- Sub Polar Low (SPL) belt around high latitudes. The belt of Inter-Tropical Convergence Zone (ITCZ) displaces in meridional path, about 5o over the oceans and up to 40o over continents, during the seasons of a year. The position of Sub-Tropical High (STH) belt is also affected by ITCZ movement. STH displacement may change the area covered by the westerly Baroclinic Waves (BW) in temperate regions. The position of the STH is an important issue for changing precipitation regime and onset of precipitation events in Iran. The goal of this research is to determine the position of STH belt over Iran in monthly scale during 1948-2010 period undertaking its meridional displacement. Geopotential height data was extracted from NCEP/NCAR reanalysis with 2.5 degrees resolutions (42.5o E, 45o E, 47.5o E, 50o E, 52.5o E, 55o E, 57.5o E, 60o E and 62.5o E) for nine meridians over Iran ranging from 42.5o E to 62.5o E. Goal of this research consist of: 1- Position determination of Sub Tropical High (STH) belt in monthly scale passing over Iran in 1948 - 2010 period; 2- Evalution of meridional displacement of STH position over Iran in 1948 - 2010 period in order to assess climate changes. By consecutive observations of 756 of 500 hPa monthly maps in GrADS (Grid Analysis and Display System) scope, 5840 gpm contour was indicated as the STH indicator. It is because the southern area of 5840 gpm contour, almost covered by northern latitude of the system while the northern area is occupied by the westerly waves during monthly round maps. This result agrees with previous studies. The strip of northern latitude is determined by 20 m width ranging from 5830 gpm to 5850 gpm. Monthly time series of STH position (unit: degree of northern latitude) was then detected using GrADS programming. Results show that the position of STH is between 10o N and 47.5o N as the most extremes in winter and summer respectively. For the long term means, the minimum northern latitude was averagely observed in January placed on 18o N zone, while maximum happened in August crossing 39o N zone during the investigated period. Its meridional displacement then reaches 21o over Iran averagely. Moreover climatic means of STH positions during 1981 - 2010 period with respect to 1951-1980 period were migrated approximately 2.8o northward. It is concluded that STH position was moved toward higher latitudes, about 2.8 degrees, in recent decade. The non-parametric Mann - Kendall trend test was applied on time series of STH position in monthly and annual scale. Results showed generally rising trends under 0.01 significance level, with 0.07 slope approximations during 1948 - 2010 period. It demonstrated the signal of climatic variability of atmospheric circulation over Iran. It is suggested that the time series of Sub Tropical High position be as the input of climate prediction models yielding temperature and precipitation as well as drought study.