Specification and Verification of Generic Cell Rate Algorithms in PVS

Formal verification methods have been considered as a powerful complementary approach to define standards and to prove correctness of the systems. In this work, formal specification of Generic Cell Rate Algorithms are defined and proved. The specification process enables standardization for constructing Generic Cell Rate Algorithms. Standardization is an important process in the Asynchronous Transfer Mode (ATM) networks. By employing formal methods, the necessary standards could be constructed to allow different algorithms to be employed which still meet system requirements. Those system requirements are quantified in the Quality of Service (QOS). Congestion management is a vital concept for networks in that when the congestion occurs it would collapse the network performance. ATM network resources that can become congested include switch ports, buffers, transmission links, ATM layer processors and connection admission control processors. In ATM, congestion is defined as the condition where the offered load approaches or exceeds the network design limits for guaranteeing the Quality of Service (QOS) specified in the traffic contract. In order to avoid congestion at the cell base, the users\u27 contracted network parameters must be monitored to ensure that the users obey their contracts. Otherwise, the network should take an action to the cells by tagging or discarding. These actions are termed User Parameter Control (UPC) functions. The most common Usage Parameter Control function is the Generic Cell Rate Algorithm (GCRA). It has advantage over other UPC functions because of its simplicity of hardware along with its quick response time. This thesis concentrates on Generic Cell Rate Algorithms, applying formal verification methods. Formal methods are used to build a specification model of GCRA and prove desired properties of the system. The Prototype Verification System (PVS) is chosen providing a specification language, a type checker, and a mechanical theorem prover. Some of the benefits of PVS include: the ability to represent abstract modeling connections, the advantage of building modular representations and using the libraries, and the ability to create requirements on future designs. In the present study the GCRA algorithms Virtual Scheduling and Leaky bucket are separate]y specified and certain properties are verified. It is shown that analyzing with PVS can provide complete coverage and understanding of the Generic Cell Rate Algorithm. In addition to this confidence of knowledge about GCRA, this work provides necessary background to improve the functionality of GCRA

the process of constructing knowledge from text

The authors examined the impact of elaborative interrogation on knowledge construction during expository text reading, specifically, the interactions among elaborative interrogation, knowledge, and interest. Three measures of learning were taken: recall, inference, and coherence. Elaborative interrogation affected all aspects of learning measured, with a significant interaction between elaborative interrogation and interest with regard to inference. The experimental effect on the measure of inference was larger for the students who had less interest than for the students who had more interest. There was also an interaction effect between knowledge and elaborative interrogation for coherence. The experimental effect on coherence was higher for students who had less knowledge than students who had more knowledge

Student Ratings of Instructors

Problem Statement: One way to delineate the main characteristics of effective teaching within the higher education system is to gather college students' opinions of an effective instructor. Research based on students' perceptions of efficient teaching revealed a series of teaching behaviors setting the distinction between good and poor teaching. However, studies also indicate differences across culture, and in Turkey, there has been little research on the topic.Purpose of Study: The goal of this study was to determine instructor and course characteristics and teaching dimensions that discriminate between instructors who received the highest and the lowest student ratings within a Turkish college setting, by incorporating both quantitative and qualitative methods.Method: A total of 23,814 students across different departments in the university rated 630 instructors on a scale developed to assess students' perceptions of instructors' performance. In addition, students were asked to respond to an open-ended question to provide their own impressions of each instructor. Then, students' ratings were analyzed by means of discriminative functional analysis, and written statements provided by students were analyzed via content-analysis techniques by using a combination of manual and computer-assisted methods (NVivo 9).Findings and Results: According to the quantitative analyses, although course and instructor characteristics were weak in discriminating the groups, all teaching dimensions (relationships with students, effective teaching, exams and evaluation, contribution to generic skills, class interaction, and organization and planning) were very useful in discriminating the instructors who received the best and the poorest ratings. Also, qualitative analysis revealed 4 themes consistently distinguishing the two groups: lecturing, relationship with the students, knowledge and expertise, and exams and evaluation.Conclusions and Recommendations: This study replicates the existing literature on student perceptions of effective teaching, with a culturally different, large sample. It also adds support to the notion that there are teaching behaviors, such as lecturing skills, fair evaluations, respect and interest toward students, and demonstrating expertise, that help draw the distinction between good and poor teaching in the eyes of students and that could therefore assist the improvements efforts of teacher education