In this paper, a mathematical model for symmetrical multi-layer sheet rolling, in which the layers are unbounded before rolling, by using the upper bound method and Stream function theorem is proposed. Using this model, we can investigate the plastic deformation behavior of sheets at the roll gap during rolling. Effect of various rolling conditions such as initial and final thickness and flow stress of sheets, friction factors, rolling velocity and etc. on the rolling power and force, the thickness reduction of each layer, the relative length of plastic region in each layer and etc. are discussed. The velocity field derived from the newly proposed Stream function can automatically satisfy the volume constancy and velocity boundary conditions within the roll gap. The optimized velocity fields are obtained through the minimization of total power, which is expressed by the function of five pseudo-independent parameters, during the plastic deformation. The analytical predictions from the proposed model were compared with the analytical and experimental results of other investigators and a good agreement is shown. Present model is applicable for simulating and online control applications of the rolling process of multilayer sheets.

in this research, their effects on the flight of airplanes were investigated. The study area is the country of Iran, and the flight routes of Kermanshah, Ahvaz and BandarAbbas to Tehran. The research data includes maps of the Vertical Transect (profile) of the jet Stream, the daily average of the Zonal wind (U-Wind) and meridional wind (V-Wind) components for the winter period of 2018 through NOAA/NCEP environmental databases. Also, flight route information was received from FlightRadar24 and Flightaware systems. First, by using Vertical Transect maps, the days containing strong U-Wind were extracted, and the average position of the core of the Jet Streams in the Zonal and meridional wind components, the Tropospheric level of 200 HP was detected. The list of flights was prepared, and the Zonal Wind maps were produced. Finally, the height of the flights was compared with the level of the currents of the Jet Streams, and the influence or lack of influence of the Jet Streams on the flights was studied. According to the results of the research, all the Jet Streams caused turbulence for all flights, and they caused a decrease in the speed of flights between Ahvaz and BandarAbbas to Tehran and an increase in the speed of flights between Kermanshah and Tehran according to the direction and type of Jet Streams. It was also found that all the Jet Streams had a speed of more than 90 knots, so the capacity to create tension and turbulence such as CAT was seen in them

In analyzing the frequency of drought as a multifaceted phenomenon, summarizing the event in one variable reduces the reliability of the results. Bivariate and multivariate drought frequency analysis using copula functions makes it possible to estimate the return period of a drought event with specific intensity, duration and peak. In the present study, the Stream drought index (SRI-12) was used to investigate the characteristics of drought using the monthly Stream of Barnetin Station of the Esteghlal Minab Dam watershed. Spearman's correlation coefficient was used to analyze the dependence between hydrological drought variables and six marginal distribution functions for their modeling. Then, by using Archimedean and elliptical family copula, the best joint was selected and conditional multivariate analysis of hydrological drought was done. The results showed that gamma, lognormal, and Weibull distributions are the best marginal distribution functions for drought intensity, duration, and peak, respectively. The results of the copula fit show that the best copula function in analyzing the dependence between variables is Frank's copula. The three-variable conditional probability of drought severity in 20, 50, 80, and 100-year continuities and peaks of 1 and 1.5 were investigated. These thresholds were chosen considering that they were the most frequent in the study area. The results showed that the probability of drought intensity decreases with the drought duration remaining constant and the peak increase from 1 to 1.5, but with the drought duration and intensity increasing, the drought peak also increases.

A characteristic of Data Envelopment Analysis (DEA) is to allow individual decision making units (DMUs) to select the factor weights which are the most advantageous for them in calculating their efficiency scores. This flexibility in selecting the weights, on the other hand, deters the comparison among DMUs on a common base. For dealing with this difficulty and assessing all the DMUs on the same scale, this paper proposes using a multiple objective linear programming (MOLP) approach based on scalarizing function for generating common set of weights under the DEA framework. This is an advantageous of the proposed approach against general approaches in the literature which are based on multiple objective nonlinear programming.

The study seeks to address the importance of urban Stream ecosystems from the perspective of urban ecology, human health and social well-being in the context of urban planning. The case study area is Paveh Stream in the City of Paveh. The data from the case study area were gathered from questionnaire, existing scientific and library studies and by conducting interviews with residents and authorities. Once the importance of the biodiversity of the Stream had been studied based on the existing ecological data, the social importance of the Stream and the linkages between human health, social well-being and the biodiversity of the Stream ecosystem were addressed.Based on the results of the survey and other sources of information, it was discussed that urban Stream ecosystems can be rich in biodiversity and function as ecological movement corridors for species .Urban Stream corridors can thus be an important part of the urban green infrastructure .Also we can make the weather fine, extend green space, prepare peaceful environment for residents and bring the countryside effects of nature into cities through improvement of Stream landscape.Finally, regarding the finding of this study some suggestions and implications are mentioned to improve the quality of the Stream.

In the present paper, a new penalization method is proposed for implementation of the rigid surfaces on the Navier-Stokes equations in the vorticity-Stream function formulation. In this method, a rigid body is considered as a region in the fluid flow, where the time is stopped. Therefore, by stopping the fluid particles, this region plays the role of a rigid body. In this regard, a new transformation is introduced and applied to the governing equations and a set of modified equations are obtained. Then, in the modified equations, the time dilation of the solid region is approached to infinity, while the time dilation of the fluid region remains unit. In the article, the physical and mathematical properties of modified equations are investigated and satisfaction of the no-slip and no-penetration conditions are justified. Then, a suitable numerical algorithm is presented for solving the modified equations. In the proposed algorithm, the modified vorticity equation is time integrated via the Crank– Nicolson method, and the spatial discretization is performed with the second-order finite differencing on a uniform Cartesian grid. The method is applied to the fluid flow around a square obstacle placed in a channel, the sudden flow perpendicular to a thin flat plate, and the flow around a circular cylinder. The results show that the no-slip and no-penetration conditions are satisfied accurately, while the flow fields are also solenoidal high level of accuracy.

Background: Based on the studies which have been done till now, resynchronization of ventricular contraction results in clinical improvement in patients who suffer from moderate to severe heart failure with intraventricular conduction disturbance. and using this method is increasing in our country. Study in this filed seems to be necessary.Material and methods: Sixty-five consecutive patients with advanced heart failure, NYHA Class III and IV, LV ejection fraction (EF)£35%, QRS³120 were studied before and 3 months after CRT. Mean age was 60, 57 and 8 patients with NYHA class III and IV respectively. All patients received furosemide, spironolactone, carvedilol, ACE inhibitors and angiotensin II –receptors blockers at the optimal tolerated dosage. Mean LVEF was 20.83%. Echocardiographic (Tissue Doppler Imaging), ECG and function class (NYHA) were assessed at baseline before implantation and 3 months after.Result: LV ejection fraction increased +6.8% (21.10±7 vs. 27.93±8.4%, P<0.001). Mitral valve regurgitation severity reduced (P<0.013). Interventricular mechanical delay reduced (53.83ms±18.45 vs. 26.53ms±13.90 P=0.000) and also Intra ventricular mechanical delay reduced (62.53ms±25.08 vs. 45.55ms±13.47, P=0.000). Dilated cardiomyopathic group has more mean changes in LVEF than Ischemic group (+9.06%±7.3 vs. +4.08%±6.5, P=0.01).Conclusion: Biventricular pacing results in significant clinical improvement in patients who have moderate to severe heart failure.