Research on techniques for teaching computer programming to novice learners has suggested that introducing programming concepts and theories is extremely difficult because the learners have to assimilate syntactical methods of the programming language as well as their interface to the programming world. Computer programming for the novice requires the understanding of a variety of different areas such as logic and mathematical concepts, syntax, the language interface, algorithms, flowcharts, and pseudocode associated with programming theory, which can overwhelm the learner and increase levels of stress and frustration (cognitive load). The central theme of this research was to examine the effects of scaffolding tools on cognitive load levels as participants completed laboratory assignments within a Visual Basic for Applications programming course, and to compare final course grades in Phase I and Phase II of the research. Participants were asked to evaluate their cognitive load as they completed assignments throughout the course. Course grades were also collected because all students in Phase I of the research eventually received the scaffolding tool prior to the final exam. Phase I of this study showed that within the major groups of online and face-to-face learners, and the subgroups of treatment and control, some benefit (as determined by the statistical means) was obtained by the use of the scaffolding tool to reduce cognitive load and improve laboratory scores. In the second phase of this research the students did not receive the scaffolding tool. A comparison of Phase I and Phase II indicates that the Group with the Scaffolding Tool (Phase I) experienced lower levels of cognitive load and attained higher laboratory and course scores than did the Group without the Scaffolding Tool.

IEEE 802.11 distributed coordination function (DCF) is a popular protocol used for the physical and medium access control layers in most ad hoc networks. DCF employs carrier sense multiple access with collision avoidance and a binary slotted exponential back off. It has been observed that the hidden and exposed terminal problems among stations degrade DCF's performance in terms of throughput and fairness. Hence, the effectiveness of the IEEE 802.11 DCF mechanism in ad hoc networks has attracted many research studies. Many collision avoidance schemes were proposed to address the IEEE 802.11 DCF weaknesses as the performance of the medium access control layer directly impacts the performance of higherlayer protocols and hence the entire network. An evaluation of representative schemes under the same conditions will be helpful in understanding the limitations and strengths of these schemes. This paper surveys various collision avoidance schemes, classify them on the basis of their mechanism, and then provide a comparative study of representative schemes based on their performance. They are evaluated on a chain topology, a pair topology, and a random topology with static environment to measure their throughput, fairness, collision probabilities, and delay. On the basis of the evaluation, we conclude that gentle DCF is the best scheme that has lesser collisions with improved throughput and fairness. A comparison with the legacy carrier sense multiple access with collision avoidance suggests that these proposed schemes do tend to be promising and would inspire future researchers who are interested to find solutions to the age-old collision and fairness issues in ad hoc networks. reducing the lifetime of battery-powered wireless devices.The problem of collisions is worse in a multi-hop environment than in a single-hop environment [2]. CA is implemented in the MAC layers. A MAC protocol should provide an effective mechanism to share the available limited spectrum resources while delivering high throughput and fairness to all the stations [3].In the past few years, multiple MAC protocols were developed to improve throughput, fairness, delay, and CA. A MAC protocol can be contention or reservation based. Contention-based MAC protocols are used for applications requiring bursty traffic under a light network load and low delay. A reservation-based MAC protocol is generally used for applications with real-time requirements provid-

No abstract

No abstract

No abstract