Simulating chaos: An evaluation of the driven pendulum experiment

This paper reports on the use of the Driven Pendulum software as part of the teaching for the Open University course Discovering Physics and provides an account of some of the findings from its evaluation as part of the learning experience provided to students. A driven damped pendulum is a suitable instrument for experimental studies of chaotic motion. The main aim of the simulation was to allow students both to observe some of the generic features of chaotic motion, and to explore ways in which these may be represented graphically. This simulation formed the basis of a three‐hour experiment for students which provided them with a number of learning opportunities, e.g. the opportunity to build up state‐space trajectories for various types of pendulum motion, in order to appreciate the advantages of the state‐space representation for analysing complicated behaviour, and providing consolidation of ideas about oscillations, damping and resonance. An evaluation of the Driven Pendulum at the residential school in 1995 was conducted as part of a university‐wide project run by the Computers and Learning Research Group investigating computer use in learning science and technology, and developing evaluation methodologies. It was both formative in that the evaluation results were used to redesign the notes guiding students through the activities, and summative in that we were able to draw some conclusions about the role played by the simulation in students’ learning. The students were extremely positive about the contribution made to their learning by the program, and students’ performance indicated learning gains. However, the observation data suggested that students were unclear about the distinction between complex and chaotic behaviour

A survey of adaptive control technology in robotics

Previous work on the adaptive control of robotic systems is reviewed. Although the field is relatively new and does not yet represent a mature discipline, considerable attention has been given to the design of sophisticated robot controllers. Here, adaptive control methods are divided into model reference adaptive systems and self-tuning regulators with further definition of various approaches given in each class. The similarity and distinct features of the designed controllers are delineated and tabulated to enhance comparative review

The works metallurgist: An evaluation of a CAL package on phase diagrams

The Works Metallurgist is used in the Open University course: Materials — Engineering and Science. It is being evaluated as part of a larger study of CAL teaching in Science and Technology at the Open University. With 540 students, the course provides a sufficiently large sample for a range of evaluation methods to be employed in a variety of settings (e.g. home, residential school). The methods used include questionnaires, attitude scales and pre/post achievement tests, observations and interviews. The focus of the evaluation exercise is on the effectiveness of CAL in contributing to student learning. The issue of the educational quality of the program and its instructional features are considered in this paper, in association with the goals of the program

Dynamic modeling, property investigation, and adaptive controller design of serial robotic manipulators modeled with structural compliance

Research results on general serial robotic manipulators modeled with structural compliances are presented. Two compliant manipulator modeling approaches, distributed and lumped parameter models, are used in this study. System dynamic equations for both compliant models are derived by using the first and second order influence coefficients. Also, the properties of compliant manipulator system dynamics are investigated. One of the properties, which is defined as inaccessibility of vibratory modes, is shown to display a distinct character associated with compliant manipulators. This property indicates the impact of robot geometry on the control of structural oscillations. Example studies are provided to illustrate the physical interpretation of inaccessibility of vibratory modes. Two types of controllers are designed for compliant manipulators modeled by either lumped or distributed parameter techniques. In order to maintain the generality of the results, neither linearization is introduced. Example simulations are given to demonstrate the controller performance. The second type controller is also built for general serial robot arms and is adaptive in nature which can estimate uncertain payload parameters on-line and simultaneously maintain trajectory tracking properties. The relation between manipulator motion tracking capability and convergence of parameter estimation properties is discussed through example case studies. The effect of control input update delays on adaptive controller performance is also studied

Impact of the Context of Socioscientific Issues on Discourse Patterns Used in Science Classes

This study is a qualitative study conducted to examine the effect of socioscientific issues (SSI) on discourse patterns used in the classroom. The research was conducted with four elementary science teachers working in a public school. The research was designed as case studies of these four teachers and data resources were video recordings of these teachers’ routine and SSI based lessons. The data was analyzed through discourse analysis. The discourse patterns used by teachers were examined in terms of adjacent the utterance, triadic, and chain discourse patterns. The results indicated that the discourse patterns used by the teachers in their routine lessons changed dramatically in the context of SSI and the chain discourse pattern came to the fore in the courses processed in the context of the SSI

Catch and size selectivity of small-scale fishing gear for the smooth-hound shark Mustelus mustelus (Linnaeus, 1758) (Chondrichthyes: Triakidae) from the Aegean Turkish coast

Catch rate, CPUE, biomass ratios and size selectivity from traditional longline and trammel nets of Turkish coastal small-scale fisheries were investigated in order to describe the Smooth-hound shark (Mustelus mustelus) fishery. The SELECT method was used to estimate the selectivity parameters of a variety of models for the trammel nets inner panel of 150 and 170 mm mesh sizes. Catch composition and proportion of the species were significantly different in longline and trammel nets. While mean CPUE of longline was 119.2±14.3 kg/1000 hooks, these values for 150 and 170 mm trammel nets were 5.3±1.2 kg/1000 m of net and 12.7±3.9 kg/1000 m of net, respectively. Biomass ratios of the by catch to Smooth-hound catch were found to be 1:0.32 for 150 mm trammel net, 1:0.65 for longline and 1:0.73 for 170 mm trammel net. The estimated modal lengths and spreads were found to be 91.1 and 16.2 cm for 150 mm and 103.2 and 18.4 cm for 170 mm, respectively. The modal lengths of the species as well as the spread values increased with mesh size

o TijelrnK A New Subspecies, Ablepharus kitaibelii (Bibron & Borry, 1833) budaki n. ssp. (Sauria: Scincidae) From the Turkish Republic of Northern Cyprus

Abstract: A new subspecies. Ablepharus kitaibelii budbki n. spp. that is distinguished from previously described subspecies, is recognized. Designation of A. k. budaki as a new subspecies, separate from the other subspecies, is based on the following characteristics: (a) the ventral side colouration of the trunk and tail. (b) the number of the vertical rows of scales between the masseteric and ear opening and (c) the size of the ear openings. Moreover, it is pointed out that the population of A. kitaibelii and especially the taxonomical status of A. k. chernovi in Turkey should be considered again

RC-SERVO AND IR-SENSOR CONTROL ON MOBILE PLATFORMS

ABSTRAC

The evolution of the Aristolochia pallida complex (Aristolochiaceae) challenges traditional taxonomy and reflects large-scale glacial refugia in the Mediterranean

The taxonomy of the Mediterranean Aristolochia pallida complex has been under debate since several decades with the following species currently recognized: A. pallida, A. lutea, A. nardiana, A. microstoma, A. merxmuelleri, A. croatica, and A. castellana. These taxa are distributed from Iberia to Turkey. To reconstruct phylogenetic and biogeographic patterns, we employed cpDNA sequence variation using both noncoding (intron and spacer) and protein-coding regions (i.e., trnK intron, matK gene, and trnK-psbA spacer). Our results show that the morphology-based traditional taxonomy was not corroborated by our phylogenetic analyses. Aristolochia pallida, A. lutea, A. nardiana, and A. microstoma were not monophyletic. Instead, strong geographic signals were detected. Two major clades, one exclusively occurring in Greece and a second one of pan-Mediterranean distribution, were found. Several subclades distributed in Greece, NW Turkey, Italy, as well as amphi-Adriatic subclades, and a subgroup of southern France and Spain, were revealed. The distribution areas of these groups are in close vicinity to hypothesized glacial refugia areas in the Mediterranean. According to molecular clock analyses the diversification of this complex started around 3–3.3 my, before the onset of glaciation cycles, and the further evolution of and within major lineages falls into the Pleistocene. Based on these data, we conclude that the Aristolochia pallida alliance survived in different Mediterranean refugia rarely with low, but often with a high potential for range extension, and a high degree of morphological diversity.Turkish Science Foundatio