فهرست مطالب hosseini rad

Wireless sensor network a powerful network contains many wireless sensors with limited power resource, data processing, and transmission abilities. Wireless sensor capabilities including computational capacity, radio power, and memory capabilities are much limited. Moreover, to design a hierarchy topology, in addition to energy optimization, find an optimum clusters number and best location of cluster heads are two important issues. Many routing protocols are introduced to discover the optimal routes in order to remove intermediate nodes to reduce the sensors energy consumption. Therefore, for energy consumption optimization in a network, routing protocols and clustering techniques along with composition and aggregation of data are provided. In this paper, to design a hierarchy topology, a hybrid evolutionary approach, a combination of genetic and imperialist competition algorithms is applied. First, the genetic algorithm is applied to achieve an optimal clusters number where all effective network parameters are taken in into account. Aftermath, the optimal positions of cluster heads inside every cluster are calculated utilizing the imperialist approach. Our results show a significant increment in the network lifetime, lower data-packet lost, higher robust routing compared with standard LEACH and the ICA based LEACH.

Due to the resource constraint and dynamic parameters, reducing energy consumption became the most important issues of wireless sensor networks topology design. All proposed hierarchy methods cluster a WSN in different cluster layers in one step of evolutionary algorithm usage with complicated parameters which may lead to reducing efficiency and performance. In fact, in WSNs topology, increasing a layer of cluster is a tradeoff between time complexity and energy efficiency. In this study, regarding the most important WSN’s design parameters, a novel dynamic multilayer hierarchy clustering approach using evolutionary algorithms for densely deployed WSN is proposed. Different evolutionary algorithms such as Genetic Algorithm (GA), Imperialist Competitive Algorithm (ICA) and Particle Swarm Optimization (PSO) are used to find an efficient evolutionary algorithm for implementation of the clustering proposed method. The obtained results demonstrate the PSO performance is more efficient compared with other algorithms to provide max network coverage, efficient cluster formation and network traffic reduction. The simulation results of multilayer WSN clustering design through PSO algorithm show that this novel approach reduces the energy communication significantly and increases lifetime of network up to 2.29 times with providing full network coverage (100%) till 350 rounds (56% of network lifetime) compared with WEEC and LEACH-ICA clsutering.

Introduction & Gallstone is the most common disease of gallbladder. Laparoscopic cholecystectomy is a gold standard for the treatment of patients with symptomatic gallstones. However laparascopic surgery may have complications. Post cholecystectomy retained common bile duct (CBD) stone accounts as one of these complications seems to have a high incidence. Therefore¡ the aim of this study is investigating the prevalence of symptomatic retained CBD stone after laparoscopic cholecystectomy.
This descriptive-analytical study was conducted on all patients underwent laparoscopic cholecystectomy due to gallstone¡ in the hospitals affiliated to Babol University of Medical Sciences during March 2013 till 2015. Demographic data was collected¡ as well as diagnosis prior to surgery¡ duration of surgery¡ postoperative duration of hospitalization¡ number of gallstones¡ detection time of retained CBD stones after surgery and diagnostic methods .all data were entered in to the SPSS (version 21) and P Of total number of 609 individuals 536 patients were included. 472 (88.1%) of theme were women and 64 (11.9%) were men. the mean age of patients was 42.61±13.95. 20 patients (3.7%) had proved to have CBD stones during the period of three month follow up. ERCP or other supportive treatments were needed in these patients. We found that older age (P = 0.001) was significantly associated and higher number of gallstones before surgery (P = 0.056) was in borderline range of association with the incidence of common bile duct stones. There was no association between the other variables and the occurrence of common bile duct stones.
The retained CBD stone after laparoscopic cholecystectomy is a rare complication yet our finding recommend a more punctual method of surgery particularly in the patients with risk factors like older age and presence of more than 3 gallstones.

Routing is an important challenge in WSN due to the presence of hundreds or thousands of sensor nodes. Low Energy Adaptive Clustering Hierarchy (LEACH) is a hierarchical routing and data dissemination protocol. LEACH divides a network domain into several sub-domains that are called clusters. Non-uniformity of cluster distribution and CHs selection without considering the positions of other sensors may reduce the quality of cluster selection. Sensor nodes send data packets over long distances. Imperialist Competitive Algorithm (ICA) is an optimization algorithm inspired by social phenomenon. It considers colonization process as a stage of socio-political evolution. We improve performance of the LEACH algorithm using imperialist approach and study efficacy of it in terms of energy consumption, coverage and cluster uniformity and compare with those of the LEACH algorithm. Selection of suitable value for radio communication radius over the network lifetime is a trade-off between connectivity and sensors energy consumption. Empowering LEACH with ICA helps to find the best location of a CH in every cluster, it can conserve energy significantly, increase network lifetime, and maintain network connectivity. It can significantly reduce the number of active sensors going out of range over the lifetime of a network.

This paper investigates the relation between product market competition and earnings management of the companies listed in Tehran Stock Exchange (TSE). Therefore, the Herfindahl-Hirschman, Lerner, and Modified Lerner indexes were employed as a proxy for product market competition. Also, in our research use the discretionary accruals as a proxy for earnings management. The research population composes of 67 companies listed on Tehran Stock Exchange which have been studied during the years 2004 to 2011. Multivariate linear regression statistical analysis was used to test the hypotheses of the research. The results suggest that there is a significant negative relationship between product market competition (i.e., Herfindahl-Hirschman, Lerner, and Modified Lerner indexes) and earnings management.