the most urgent public health problem today is to devise effective strategies to minimize the destruction caused by the aids epidemic. mathematical models based on the underlying transmission mechanisms of the aids virus can help the medical/scientific community understand and anticipate its spread in different populations and evaluate the potential effectiveness of different approaches for bri...

this experimental study examined the effectiveness of using focused and unfocused tasks on iranianintermediate efl learners’ performance in producing noun, adjective, and adverb clauses. in addition,the aim of this study was to explore the effects of form-focused instruction and the feedback studentsreceived from their teacher after doing focused grammar tasks. data consisted of the scores ofth...

in this paper, two new cascaded inverters are proposed, by using the series connection of new submultilevel inverters. each of the proposed submultilevel inverters consists of three batteries and eight power switches. four algorithms are presented to determine the voltages of these batteries for each of the proposed structures. in this study the comparison between the proposed structures with c...

abstract rockfill dams are a type of hydraulic control structures used to protect river bed in cases where a considerable reservoir volume is available behind these structures; it could mitigate the floods and provide a gradual depletion of incoming volume of water so that the discharge passing downstream is decreased. one of the main issues on utilizing rockfill dams is to keep its permeabilit...

the present study presents an algorithm that models uncertainties at the structural component level to estimate the performance reliability of rc structures. the method calculates the performance reliability using a systemic approach and incorporates the improved response surface method based on sampling blocks using the first-order reliability method and conditional reliability indices. the re...

in this paper, a new enhanced version of the particle swarm optimization (pso) is presented. an important modification is made by adding probabilistic functions into pso, and it is named probabilistic particle swarm optimization (ppso). since the variation of the velocity of particles in pso constitutes its search engine, it should provide two phases of optimization process which are: explorati...

subsea structures such as manifolds, line pipes and flow lines are important investments. also because of the sensitivity of environmental issues, corrosion of these structures is of vital importance. subsea corrosion management is different from on-shore and shallow water off-shore corrosion management in mainly three factors: materials, corrosion management practice and cathodic protection. t...

objectives: language development is often very slower in hearing impaired children compared with their normal peers. hearing impairment during childhood affects all aspects of speech production and language acquisition. it seems that hearing impaired people suffer from language and speech impairments such as production of complex linguistic structures. the purpose of this study is to determine ...

unlike the languages we know, some of the arabic sentences form without any verbs. arab grammarians call these sentences, which contain a subject and a predicate without any linking verbs, nominal sentences. examining theses sentences indicates that their predicate is composed of one of the following words or structures: 1. noun, 2. prepositional phrase, 3. an adverb of time or place, 4. a nomi...