Enhanced speed control of a DC servo system using PI + DF controller tuned by stochastic fractal search technique

Since Proportional?+?Integral?+?Derivative (PID) controller is still the workhorse in taking over the workload of process control systems, this article introduces a new design methodology toward improving the performance of such controller. After a PI control law with windup protection is given, it is combined with a derivative path employing a first-order low pass filter in an innovative way to develop a performant controller called PI?+?DF controller. In attempting to attain a high level of control performance, gains of this controller including proportional, integral, derivative and filter gains are tuned choosing the recently introduced Stochastic Fractal Search (SFS) algorithm owing to its superiority to many state-of-the-art algorithms considering convergence, accuracy and robustness. To evaluate the efficacy of SFS, Particle Swarm Optimization (PSO) is also applied to the case study. Furthermore, the presented SFS optimized PI?+?DF controller is compared to a recently reported control scheme through simulation and experimental tests on an identical DC servo system. After providing the stability proof, SFS tuned PI?+?DF controller is found to be the pioneer in exhibiting the most accurate speed response profile under complicated scenarios, which is followed by PSO tuned PI?+?DF controller and the existing control approach, respectively.     

Effectiveness of Computer-Based Chemistry Instruction in Enhancing the Learning of Content and Variable Control Under Guided Versus Unguided Conditions

Computerized learning environments offer several possibilities that can be used to improve the teaching of content along with the process. Research indicates that students benefit from additional guidance, particularly when computer-based instruction requires active construction of knowledge. This study examines the relative effectiveness of guided versus unguided computer-based instruction with respect to regular instruction in improving content knowledge and process skills among students with low and high chemistry achievement levels. The results indicate that the effectiveness of computer-based instruction increases when learning is supported by teacher-directed guidance. Computer-based instruction (with or without guidance) was observed to be more effective than regular instruction in improving process skills particularly for students with high chemistry achievement. However, although the students who received regular or guided computer-based instruction showed significant gains in content knowledge, students under unguided condition failed to construct the expected content knowledge.     

Meta-Representation in an Algebra I Classroom

We describe how 1 Algebra I teacher and her 8th-grade students used meta-representational knowledge when generating and evaluating equations to solve word problems. Analyzing data from a sequence of 4 lessons, we found that the teacher and her students used criteria for evaluating equations, in addition to other types of knowledge (e.g., different interpretations of the equal sign) previously reported in the literature. Moreover, the teacher and her students had trouble understanding one another's proposed algebraic models of problem situations due to differences in the criteria that each applied, and this impeded learning. These findings (a) extend an accumulating body of evidence for the role meta-representation plays in mathematics and science learning and (b) add a new dimension to researchers' growing understanding of what teachers must know in order to teach algebra and other complex mathematics and science topics effectively.     

Cyber Bullying @ Schools: What do Turkish Adolescents Think?

Cyber bullying is an emerging form of peer bullying, becoming prominent especially over the past decade. The aim of this study was to investigate through interviews the perceptions of Turkish high school students about cyber bullying. The sample consisted of six male and one female high school students all aged 15 years who identified as being active in cyber bullying. Findings were grouped under four main headings; acts of cyber bullying, reasons for cyber bullying, characteristics of cyber bullies and victims, and suggestions to prevent cyber bullying. The results were discussed in the light of relevant literature.     

Early cognitive and home environmental predictors of reading fluency and reading comprehension in Turkish-speaking children

In this study, we aimed to determine the early cognitive and home environmental predictors of reading in Turkish-speaking children. A total of 362 children participated in the study. We monitored the children for 3 years and assessed the home environmental variables and cognitive skills in kindergarten, reading fluency at the end of the first grade, and reading comprehension at the end of the second grade. We found that home literacy environment and socioeconomic status predicted early literacy skills in kindergarten as they also predicted reading fluency and reading comprehension through early literacy in later years. In addition, we found that phonological awareness, letter knowledge, and rapid naming predicted reading fluency, while language and verbal working memory predicted reading comprehension. The results of the study showed us that it is important to consider reading and reading comprehension in Turkish-speaking children holistically, together with cognitive skills and home environmental variables.     

INVESTIGATING THE EFFECTIVENESS OF AN ANALOGY ACTIVITY IN IMPROVING STUDENTS’ CONCEPTUAL CHANGE FOR SOLUTION CHEMISTRY CONCEPTS

This paper reports on an investigation on the use of an analogy activity and seeks to provide evidence of whether the activity enables students to change alternative conceptions towards views more in accord with scientific views for aspects of solution chemistry. We were also interested in how robust any change was and whether these changes in conceptual thinking became embedded in the students’ long-term memory. The study has its theoretical basis in an interpretive paradigm, and used multiple methods to probe the issues in depth. Data collection consisted of two concept test items, one-on-one interviews, and student self-assessment. The sample consisted of 44 Grade 9 students selected from two intact classes (22 each), from Trabzon, Turkey. The interviews were conducted with six students selected because of evidence as to their significant conceptual change in solution chemistry. The research findings revealed statistically significant differences in pre-test and post-test scores, and pre-test and delayed post-test scores (p<0.05), but no differences between post-test and delayed test scores (p>0.05). This suggests that the analogy activity is helpful in enhancing students’ conceptual understanding of solution chemistry, and that these changes may be stored in the students’ long-term memory.     

The Efficacy of Multimedia Stories in Preschoolers’ Explicit and Implicit Story Comprehension

Oral language provides a foundation for reading comprehension. Story comprehension is a fundamental oral language skill; it covers making inferences, identifying main ideas, monitoring, perspective-taking, and applying working memory capacity. Complex reasoning and perspective-taking are key factors in deep reading comprehension. Preliterate children’s deeper story comprehension skills can be initial indicators of their later reading comprehension. Thus, the purpose of this research is to investigate preliterate preschool children’s story comprehension skills in detail. This study focuses on the additional multimedia features of digital storybooks and whether they hinder or promote young children’s explicit and implicit comprehension in a small group reading activity. The findings revealed that (a) children in the multimedia-enhanced storybook group outperformed the print storybook group in terms of both explicit and implicit story comprehension, (b) explicit story comprehension was higher than implicit story comprehension for both groups, and (c) the children recalled significantly more story elements and the length of the story retellings was greater with the aid of animated illustrations. The findings indicate that a digital storybook provides close temporal contiguity of text and visuals and may enhance story understanding by concretizing the narration. The study provides evidence that multimedia stories can foster children’s implicit story comprehension and inferential thinking about the content of the story.     

The Effect of Conflict Resolution Training on Turkish Elementary School Students: A Quasi-Experimental Investigation

This study investigated the effect of conflict resolution training on Turkish elementary school students' conflict resolution strategies. The participants were 54 fourth grade students. A pre-test, post-test, follow-up control group quasi-experimental design was used. Two 4th grade classes were selected out of three eligible 4th grade classes on the basis of Conflict Scenario Written Measure (Johnson, Johnson, & Dudley, 1992) and randomly assigned as control and experimental group. The experimental group consisted of 28 students (17 boys, 11 girls) and the control group consisted of 26 students (15 boys, 11 girls). Those in experimental group received 45 minutes of conflict resolution training twice a week, for four weeks. The results indicated that treatment was effective in changing the conflict resolution strategies used by the experimental group subjects in three different hypothetical situations and this effect was maintained six months after the treatment.