Sharif Digital Repository

Stock return is usually considered to be affected by firm's financial ratios as well as economic variables. Fundamental method assume that stock returns is not solely related to the stock market. Most result come from the company condition, industry situation and whole economy. In this paper, this relationship between stock return and fundamentals is studied using the data for 22 pharmaceutical companies in Tehran Stock Exchange over a 7 year period, and effective factors on stock return are investigated. Because of our data natural we used panel data model from econometric methods. The results show that 80 pecent of change in stock return can be explained with 9 fundamental variables... 

Deposition of dissolved impurities and corrosion in steam generators is a significant problem in the operation of nuclear power plants. Impurities and corrosion products usually accumulate in the secondary sides of steam generators (SG) and form deposits on the SG surfaces. A high level of impurity concentration close to the SG heating surface causes the corrosion process to occur with more intensity. The aim of this study is to estimate the most probable locations of impurity concentration and deposition in a SG. Equations representing the convection and diffusion in the liquid phase close to the heated surface (the viscous sub layer) are derived. Based on the mass balance of impurities in... 

A new approach has been presented to solve gas-liquid flow numerically in vertical pipes of air-lift pumps. To improve modelling, a new strategy has been employed with the capability of coupling the continuity and momentum equations and enforcing the role of pressure directly in the continuity equation. This is achieved via applying a novel scheme called the Physical Influence Scheme (PIS). The current finite volume solution is compared with other available numerical solutions. Indeed, they are in fair agreement. However, the present predictions are far superior to those obtained from an existing simple method, which is widely used in airlift pump modelling  

A new approach has been presented to solve gas-liquid flow numerically in vertical pipes of air-lift pumps. To improve modelling, a new strategy has been employed with the capability of coupling the continuity and momentum equations and enforcing the role of pressure directly in the continuity equation. This is achieved via applying a novel scheme called the Physical Influence Scheme (PIS). The current finite volume solution is compared with other available numerical solutions. Indeed, they are in fair agreement. However, the present predictions are far superior to those obtained from an existing simple method, which is widely used in airlift pump modelling  

Motivated by the bus escape routing problem in printed circuit boards, we revisit the following problem: given a set of n axis-parallel rectangles inside a rectangular region R, find the maximum number of rectangles that can be extended toward the boundary of R, without overlapping each other. We provide an efficient algorithm for solving this problem in O(n2 log3 n log log n) time, improving over the current best O(n3)-time algorithm available for the problem  

After proposing a semi-analytical solution for swirl laminar flow, macroscopic characteristics of open-end pressure-swirl injector including discharge coefficient and spray cone angle are calculated. In the presence of air core of the axial region inside the injector, the laminar rotational flow equations are simplified, and with the assumption of the quasi-developed axial flow along the nozzle, the equations are iteratively solved employing separation of variables method. The accuracy of the proposed semi-analytical solution is compared by some numerical and experimental results on an open-end injector. The validity of quasi-developed flow defined in the present work is confirmed based on... 

Here, we experimentally investigated the effects of skewness and velocity difference of two Newtonian colliding jets on the formation of a special oscillating liquid sheet pattern with periodic fragmentation, called fishbone, for four liquid sheet regimes known as the triple chain, double chain, close rim, and open rim. We expressed the ranges of the skewness and the velocity difference, where the fishbone pattern was formed for every four regimes. The formation of this special pattern was attributed to the instability of the liquid rim in the past studies. We qualitatively studied the upward and downward directions of the rims branched from the liquid sheet. Besides, the size variations of... 

The Gnutella protocol requires peers to broadcast messages to their neighbors when they search files. The message passing generates a lot of traffic in the network, which degrades the quality of service. We propose the new method to optimize the speed of search and to improve the quality of service in a Gnutella based peer-to-peer environment with using semantic routing and priority of nodes. Once peers generate their "friends lists", they use these lists to route queries in the network. This helps to reduce the search time and to decrease the network traffic by minimizing the number of messages circulating in the system as compared to standard Gnutella