This paper presents an evaluation of the QoS enhancements to the IEEE 802.11 standard, named IEEE 802.11e, currently under specification. Both the Enhanced Distributed Coordination Function (EDCF) and Hybrid Coordination Function (HCF) modes of Medium Access Control (MAC) operation are analysed and compared with legacy Distributed Coordination Function (DCF) and Point Coordination Function (PCF...

introduction: objective structured clinical examination (osce) is used for the evaluation of the clinical competence in medicine for which it is essential to measure validity and reliability. this study aimed to investigate the validity and reliability of osce for residents of obstetrics and gynecology at kermanshah university of medical sciences in 2011. methods: a descriptive-correlation stud...

In this paper, we present an approach for verifying that trusted programs correctly enforce system security goals when deployed. A trusted program is trusted to only perform safe operations despite have the authority to perform unsafe operations; for example, initialization programs, administrative programs, root network daemons, etc. Currently, these programs are trusted without concrete justi...

The strategic lazy incremental copy graph unification method is a combination of two methods for unifying hmture structures. One, called the lazy incremental copy graph unification method, achieves structure sharing with constant order data access time which reduces the cequired memory. The other, cal led ti~e s t r a t eg ic incremental copy graph unification method, uses an early fai lure f i...

agriculture is an important engine of growth and poverty reduction in much of africa, nigeria inclusive. but the sector is underperforming in part because women, who are often crucial resource in agriculture and rural economy, face constraints that reduce their productivity. an understanding of these constraints is a prerequisite to devising policies to improve agricultural production and produ...

the purpose of this study was to studying the affecting organizational factors oneducational failure of kashan university’ students, the outcomes of educational failureand providing solutions for overcoming or decreasing it. in the present study, thequalitative grounded theory method has been used. in addition, for more access to thedata, institutional analysis methods and analysis of documents...

Most ad hoc networks do not implement any network access control, leaving these networks vulnerable to resource consumption attacks where a malicious node injects packets into the network with the goal of depleting the resources of the nodes relaying the packets. To thwart or prevent such attacks, it is necessary to employ authentication mechanisms to ensure that only authorized nodes can injec...

Random Multi-access Protocols has been used as the MAC protocol over Multi-access channels. They are specially recommended when there are a large population of users with low and bursty traffic as for example it will be in HFC (Hybrid Fiber-Coax) networks with multimedia services, we should be sure that the access to the network copes with the QoS. each type of traffic requires. We will describ...