Background and Objectives: Downstream of grade control structures in watershed engineering, it is necessary to create a hydraulic jump to dissipate excess energy to prevent the destruction of the structure. A roughened bed of stilling basins of the hydraulic jump type to increase the amount of energy loss and reduce the length of the hydraulic jump can lead to economic savings in watershed management. In this study, a new type of roughness, which is similar to the appearance of the ripple bed in alluvial rivers, was experimentally investigate to increase the energy loss, reduce the stilling basin length and to prevent sedimentation in between the rough elements. Materials and Methods: The experiments of this research were carried out in a rectangular flume with width, height and length of 0. 3, 0. 4 and 12 meters respectively. Five different arrangements of the bed form along with a case of no bed form were tested under five different Froude numbers, Fr= 3. 5 to 5. 5. An Ogee weir with a height of 32 cm was installed 3 meters downstream of the flume inlet to create a hydraulic jump, and the minimum flow depth on the crest of the weir was set to be more than 3 cm to avoid the effect of surface tension. During the experiment, the water level profiles at the hydraulic jump site were measured by a point gauge with an accuracy of ±, 1 mm. During the experiment, digital photos were also taken and the required data was extracted by digitizing these photos. The average flow depth measured and extracted from the photos was used in the analysis to reduce the error. Rolling length, jump length and water surface profile were measured in each experiment and repeated three times. These lengths were also extracted from the photos and the average values were used in the analysis. Results and Conclusion: The results of the investigation of the variation of the ratio of conjugate depths versus Fr for all types of the bed forms showed that by changing the layout of the bed form from type 1 to type 4 of the current study, the ratio of conjugate depths (y2/y1) decreases. A maximum decrease of 10. 2% was observed for the type 4 bed form compared to the case of no bed form. The variation of relative energy loss (Δ, E/E1) versus Fr also showed that by changing the layout of the bed form, the ratio of Δ, E/E1 increases, and in the type 4 bed form, compared to the control bed form, a maximum of 23% increase in energy loss was observed. In the investigation of the relative length of the hydraulic jump (Lj/Y2) and also the relative roller length of the jump (Lr/Y2), it was observed that by changing the bed form from type 1 to type 4, the ratio Lj/Y2 and Lr/Y2 decreases and the maximum reduction in comparison to the case of no bed form, was found in the type 4 bed form, which was in the order of 32% and 34% respectively.

The conventional literature suggests a positive relationship between the expected return and the conditional volatility, but according to the empirical evidence there is not a specific and constant relationship between them. In this regard, the study investigates the role of significant characteristics of financial asset prices including time-varying conditional volatility and jump in the relationship between risk and return in Tehran stock market. For this purpose the ARJI-GARCH model which includes both features is applied and the results are compared with two more simple models i.e. GARCH-M and GARCH- JUMP.The former consists of the conditional variance and the latter has both features but with the constant probability of the jump. The empirical findings using daily data from September 9th 1997 to March 15th 2015 imply that the jump component has a significant impact, and the risk of Iran’s stock returns includes both smoothly changing variance and jump events. Therefore, the traditional GARCH-M model cannot explain correctly the relationship between risk and return in Iran’s stock market. Also, the analysis of the time-varying risk premium shows that in the short-run only the risk arising from jump is significant.

Abstract: The forging model for cold rolling is one of the rolling models which is used in rolling calculations. In this model, the final rolling pressure is an average value and it is not as accurate for actual and industrial cases. Also, by using forging model, friction hill curves are plotted due to the central point of rolling bite length while frictional stresses intersect at the neutral point of rolling bite. In this study, a new model based on the forging model is presented to determine the rolling pressure during cold rolling process for using in a reversing tandem mill, where this is called “Improved forging model”. In the proposed model, the intersection of the frictional forces is the neutral point. Finally, the computing results from this new model coincide well with the precedent investigations.

In this article with simulation of Tehran subway second type rolling stock, dynamic performance of this train has been studied. Dynamic simulation of Tehran subway has been simulated in UM (universal mechanism) package. At first train bogie parts has been drawn in 3D software package Solid works and moment of inertia and mass of each part has been extracted. In Solid works software the bogie part has been attached and complete model of bogie imported to Dynamic simulation software. In Dynamic simulation of Tehran subway rolling stock, primary and secondary suspensions were differ from conventional bogies that has been used in Iranian railway and simulation should be done exactly. After this work dynamic simulation has been done for hunting speed of wagon and acceleration of wagon body has been obtained in vertical and lateral directions. with the result that has been extracted from dynamic performance of train, the effect of hunting speed on lateral wheelset lateral displacement and angle of attack in left wheel of first wheelset has been comprised. ride index criteria for calculation of Tehran subway has been explained. for simulation of train, track irregularity inputted in UM software for ride index has been calculated in lateral and vertical directions. According to secondary suspension of Tehran subway train body acceleration and ride comfort of this train simulated. According to ride comfort result of this train, the result of Tehran subway rolling stock has been compared with standard value.

Obtaining temperature distribution data of slabs under rolling is essential as the mechanical and metallurgical properties of the metal under this process vary with temperature. Using the control volume method, a mathematical model is employed in this study to predict slab temperature in the hot roll process at Mobarakeh Steel Company. The effects of different parameters including the heat resulting from plastic deformation and slab material are investigated. Additionally, heat conduction along the rolling direction in the slab, ignored in most previous studies, is included in our investigation. The study indicates the importance of this term in the accuracy of the results obtained.