Mathematical study of the effects of applied stress, T-stress and back stress in photoelastic fringe patterns

This work is an attempt at developing a novel mathematical model to describe the stresses near the crack tip, taking into consideration the effects of plasticity. The focus is on describing how the applied stress normal to the crack, herein referred to as the K-stress, Tstress and ‘back stress’ induced by plasticity along the crack flank and in the crack tip plastic zone influence the crack tip elastic stress fields. The important features emerging from this study are that the sign and magnitude of each term can substantially alter the crack tip stress fields, and hence influence the photoelastic fringe patterns. To validate the mathematical model, polycarbonate compact tension specimens have been used and observed in a transmission polariscope in order to study the single effect of a pure ‘back stress’ (acting as an interfacial shear stress at the elastic-plastic boundary) and combination effects of K-stress, Tstress and ‘back stress’. It is observed that the fringe patterns obtained through experiment show good agreement with those derived by mathematical modelling

Dr. Martin Hillenbrand to Receive University of Dayton Distinguished Alumnus Award

News release announcing the University of Dayton will Award Assistant Secretary of State for European Affairs, Dr. Martin Hillenbrand, with the Distinguished Alumnus Award

The level of Marzano higher-order thinking skills among polytechnic students

This study aims to identify polytechnic students' level of Marzano Higher-Order Thinking Skills (HOTS) based on two dimensions, 'Extension and Refinement of Knowledge' and 'Meaningful Use of Knowledge,' and to analyze the difference in the students' level of Marzano HOTS based on these two dimensions depending on the students' demographic factors. This study design was a survey using quantitative methods. A total of 313 students were randomly selected as the survey sample. A questionnaire in the form of closed-ended questions was used as the research instrument. Data were analyzed using frequency percentage and MANOVA test. The findings showed no significant differences in the eight HOTS in the dimension of 'Extension and Refinement of Knowledge' with the gender and socio-economic status (SES) factors. However, there were significant differences in the eight HOTS with the academic achievement factor. Meanwhile, based on the dimension of 'Meaningful Use of Knowledge,' the findings showed no significant differences in the five HOTS in this dimension with the gender and academic achievement factors. The paper includes implications of the Higher-Order Thinking Skills (HOTS) for students to improve their academic performance. In future research, the authors can further identify university students' HOTS levels in the technical area

Tapered microchannel for multi-particles passive separation based on hydrodynamic resistance

Researches on separation of multi-particles utilizing microfluidic have been flourishing in recent years with the aid from advancements in microfabrication design and technology. Generally, separation is beneficial for biomedical application especially involving heterogeneous samples. Due to inherent problems of samples isolation, a simple and efficient separation device is required. Here, we present a passive tapered microchannel for multi-particles separation using hydrodynamic principle. Our emphasis is on the effect of hydrodynamic resistance coupled with tapered microchannel design. In the experiment, successful multi-particles samples separation was observed. The results were further analyzed and were in agreement with the proposed concept. This method opens the route toward robust, low-cost and high-throughput, thus it may holds potential to be integrated as one functional module in Micro Total Analysis System (µTAS)