Browsing by Subject "Flow"

Now showing 1 - 7 of 7

Open Access
Algorithms for efficient vectorization of repeated sparse power system network computations
(IEEE, 1995) Aykanat, Cevdet; Özgü, Ö.; Güven, N.
Standard sparsity-based algorithms used in power system appllcations need to be restructured for efficient vectorization due to the extremely short vectors processed. Further, intrinsic architectural features of vector computers such as chaining and sectioning should also be exploited for utmost performance. This paper presents novel data storage schemes and vectorization alsorim that resolve the recurrence problem, exploit chaining and minimize the number of indirect element selections in the repeated solution of sparse linear system of equations widely encountered in various power system problems. The proposed schemes are also applied and experimented for the vectorization of power mismatch calculations arising in the solution phase of FDLF which involves typical repeated sparse power network computations. The relative performances of the proposed and existing vectorization schemes are evaluated, both theoretically and experimentally on IBM 3090ArF.
Open Access
Flow experiences of EFL instructors in Turkey
(2019-06) Belce, Ömür
This study investigated flow experiences of EFL instructors in Turkey by focusing on absorption, work enjoyment, intrinsic work motivation, skills, activities, and time of the day through age, ethnicity, educational level, gender, sexual orientation, and years of experience variables. The study was conducted over a six-week period with 283 EFL instructors working 30 universities. The data were collected via an online survey consisting of three sections. Both descriptive and inferential statistics were used to analyze the data. The results indicated that EFL instructors experience flow in language classes. The findings also showed that work-related flow can be predicted by skills, activities, time of the day, age, educational level, and years of experience. However, no significant relationship was found between flow and ethnicity, gender, sexual orientation.
Open Access
Heat partition evaluation during dry drilling of thick CFRP laminates with polycrystalline diamond drills
(ELSEVIER, 2024-10) Shariar, Fahim; Karagüzel, Umut; Karpat, Yiğit
Since various material properties of carbon fiber-reinforced polymer (CFRP) are temperature dependent, dry drilling of CFRP is a delicate process. Thermal damage can be caused by a rise in temperature during drilling due to a large portion of heat being transferred into the material. Heat partition is used to quantify this, which represents the percentage of total heat being dissipated into the constituent objects during a machining operation. Drill margin and contact conditions at the tool-workpiece interface significantly affect the drilling of CFRP material. Drilling experiments were performed to measure thrust force, torque, and temperatures for five different sets of feed rates and rotational speeds. This study proposes a method for calculating heat partition values during CFRP drilling by developing a finite element-based thermal model. The FE model employs a Gaussian distributed ring-type heat flux that is a function of the equivalent contact length at the interface between the drill and the material surface and the geometry of the workpiece which operates as a moving heat source, emulating the progress of the drill through the CFRP laminate. The tool implements heat fluxes that use characteristic time-point-based step functions to represent the temperature on the drill as it advances through the workpiece during machining. The temperature profiles obtained from the FE analysis and the experiments for the workpiece and tool were subsequently matched iteratively to determine the corresponding heat partition value
Open Access
The impact of choice provision on students' affective engagement in tasks : a flow analysis
(2005) Alperer, Selin
This study was designed to investigate the impact of choice on students’ affective engagement in 19 tasks in an EFL classroom. The choice provision techniques for the tasks included student-generated choice, teacher-assigned choice and no choice. The study was conducted with one group of 26 students who were taking the English 102 course offered at Middle East Technical University (METU). Data was collected using a survey of student affective engagement completed immediately after each task. Individual student means were used to investigate the motivational potential of tasks, and the number of participants in flow and apathy for each task. Data was further analyzed using ANOVA tests for choice and interactional pattern, a MANOVA test for the impact of choice, interactional pattern, and their mediating effect on the three flow dimensions, and t-tests for English proficiency and gender. The analyses indicated that both choice and interactional pattern significantly contributed to students’ affective engagement in tasks, but that interactional pattern played a more important role. Results showed that provision of choice did produce a significant positive difference in affective engagement compared to no choice, but that there was no distinction between student-generated and teacher-assigned choice. The findings also showed that an interactional pattern of group work produced significantly better results, followed by individual work, and a negative trend for whole-class interaction. A MANOVA test showed that while choice had a significant effect on task control and task appeal, interactional pattern showed a significant effect for all three flow dimensions, including focused attention. Moreover, the findings revealed a significant interaction effect between choice and interactional pattern for students’ perceptions of task appeal. Lastly, it was concluded from t-test results that neither English proficiency, nor gender significantly related to affective engagement in tasks.
Open Access
Need satisfaction as a mediator between classroom goal structures and students' optimal educational experience
(Elsevier, 2018) Alp, A.; Michou, Aikaterini; Çorlu, M. S.; Baray, G.
Goal-related messages in a classroom are associated with students’ experiences and functioning in learning. However, little is known about need satisfaction as a mediator that translates the classroom messages into students’ optimal educational experience. In the present studies, we investigated in a sample of 171 (in Study 1) and 255 (in Study 2) Turkish undergraduate students (60% females; Mage = 19.79, SD = 1.68 and 45% females, Mage = 19.75, SD = 1.67 respectively), the relation of classroom goal structures to students’ educational satisfaction (or vitality) and state flow through their experience of need satisfaction considering it as the psychological mediator. Path analysis with bootstrap showed that mastery goal structures (i.e., classroom environment focuses on learning and self-improvement) were positively related to need satisfaction while performance goal structures (i.e., classroom environment focuses on normative success) were either negatively related (Study 1) or unrelated (Study 2) to need satisfaction. Path analysis with bootstrap also showed that mastery goal structures were related to vitality, educational satisfaction and flow in class-related tasks through need satisfaction. Understanding need satisfaction as a mediator of classroom goal structures and optimal educational experience help teachers to reconsider their goal-related messages in the classroom.
Open Access
Stability analysis of volatile liquid films in different evaporation regimes
(American Physical Society, 2024-09-20) Mohamed, Omair A. A.; Biancofiore, Luca
We investigate the role of the evaporation regime on the stability of a volatile liquid film flowing over an inclined heated surface using a two-fluid system that considers the dynamics of both the liquid phase and the diffusion of its vapor into the ambient environment. Consequently, the evaporation process is necessarily governed by the competition between (1) the thermodynamic disequilibrium tied to the liquid film's local thickness and (2) the diffusion effects dependent on the interface's curvature. We (1) modify the kinetic-diffusion evaporation model of Sultan et al. [J. Fluid Mech. 543, , 183 (2005)] to allow for the reduction in film thickness caused by evaporative mass loss and (2) combine it with the liquid film formulation of Joo et al. [J. Fluid Mech. 230, , 117 (1991)], and then (3) utilize long-wave theory to derive a governing equation encapsulating the effects of inertia, hydrostatic pressure, surface tension, thermocapillarity, and evaporation. We employ linear stability theory to derive the system's dispersion relationship, in which the Marangoni effect has two distinct components. The first results from surface tension gradients driven by the uneven heating of the liquid interface and is always destabilizing, while the second arises from surface tension gradients caused by imbalances in its latent cooling tied to vapor diffusion above it, and is either stabilizing or destabilizing depending on the evaporation regime. These two components interact with evaporative mass loss and vapor recoil in a rich and dynamic manner. Moreover, we identify an evaporation regime where the kinetic and diffusion phenomena are precisely balanced, resulting in a volatile film that is devoid of the vapor recoil and mass loss instabilities. Additionally, we clarify the dependence of the mass loss instability on the wave number under the two-fluid formulation, which we attribute to the presence of a variable vapor gradient above the liquid's surface. Furthermore, we investigate the effect of film thinning on its stability at the two opposing limits of the evaporation regime, where we find its impact in the diffusion-limited regime to be dependent on the intensity of evaporative phenomena. Finally, we conduct a spatiotemporal analysis which indicates that the strength of vapor diffusion effects is generally correlated with a shift towards absolute instability, while the thinning of the film is observed to cause convective-to-absolute-to-convective transitions under certain conditions.
Open Access
Teachers' and students' perceptions of flow in speaking activities
(2010) Ak Şentürk, Burcu
This study was designed to investigate the degree to which flow occurred in different kinds of tasks in speaking courses and examined teachers’ and students’ perceptions about the existence of flow experience in speaking courses. The study was conducted over a two-week period with 163 elementary level university students and their eight instructors of English in eight different speaking classes at Zonguldak Karaelmas University English Language Preparatory School. Designated speaking tasks were class discussion, role-play, language games, interview, information-gap, problem solving, picture narration, and storytelling. Data were collected through the administration of a questionnaire to measure students’ affective responses to tasks after each designated task, a short survey on teachers’ perceptions about each task and interviews with these eight teachers about their perceptions about flow theory, their flow experiences in their lessons and the degree to which students experience flow in the activities. Student means were used to investigate the motivational potential of tasks. Data were further analyzed using ANOVA tests in order to explore the differences in the experience of flow among the eight different activities. The qualitative and quantitative analyses indicated that flow exists in language classes; however, there is a significant difference among each task. The findings revealed that the class discussion activity produced more flow for both teachers and the students, whereas the information-gap activity resulted in more apathy. Results also showed that there is a significant relationship between the type of the activity and affective engagement in terms of students’ perception of task control, task appeal, focused attention and challenge. Overall the analysis showed that when activities included the four dimensions of flow, the students were more likely to perceive flow. The findings also revealed that teachers could facilitate the flow experience for students by developing tasks that might lead to flow. Lastly, the findings showed that an interactional pattern of group work produced significantly better results.