Hole quality plays a crucial role in the production of close-tolerance holes utilized in aircraft assembly. Through drilling experiments of carbon fiber-reinforced plastic composites (CFRP), this study investigates the impact of varying drilling feed and speed conditions on fiber pull-out geometries and resulting hole quality parameters. For this study, hole quality parameters include hole size variance, hole roundness, and surface roughness. Fiber pull-out geometries are quantified by using scanning electron microscope (SEM) images of the mechanically-sectioned CFRP-machined holes, to measure pull-out length and depth. Fiber pull-out geometries and the hole quality parameter results are dependent on the drilling feed and spindle speed condition, which determines the forces and undeformed chip thickness during the process. Fiber pull-out geometries influence surface roughness parameters from a surface profilometer, while their effect on other hole quality parameters obtained from a coordinate measuring machine is minimal.

This paper aims to investigate the effectiveness of super-hard ceramic coatings by evaluating tool wear when drilling carbon fiber-reinforced plastics (CFRP) composite. The drilling experiments of CFRP are conducted with diamond-like carbon (DLC) coated, AlMgB14 (BAM) coated, AlCrN and Si3N4 and TiN (simply denoted as (AlCrSi/Ti)N) coated, and uncoated tungsten carbide drills. Each coating, dictated by its unique processing technique, provides unique thickness and morphology, and its physical properties, which makes the comparison among the coatings much difficult but enables to deduce the desirable attributes in the prospective coating ideally suited in drilling CFRP. To do so, after the drilling experiments, the tool wear was captured using the scanning electron and confocal laser scanning microscopes to construct the wear evolution that enables us to evaluate each coating qualitatively as well as quantitatively. Among the drills tested, the (AlCrSi/Ti)N-coated drills provided the best performance despite of the fact that (AlCrSi/Ti)N coating particularly are not harder than any other coating. The superior performance of the (AlCrSi/Ti)N coating can be explained by the comparable stiffness to the carbide substrate, 7.3 μm-thick coating consisting of the numerous nanoscale alternating layers between nanocomposite of AlCrN and Si3N4 and TiN coatings and the enhanced adhesion, which provide the effective cutting of carbon fibers. However, the thin DLC coating despite of its superior hardness and the BAM coating despite of its low friction did not perform at the level that the (AlCrSi/Ti)N coating was able to achieve.

This exploratory study focuses on the use of ChatGPT, a generative artificial intelligence (GAI) tool, by undergraduate engineering students in lab report writing in the major. Literature addressing the impact of ChatGPT and AI on student writing suggests that such technologies can both support and limit students' composing and learning processes. Acknowledging the history of writing with technologies and writing as technology, the development of GAI warrants attention to pedagogical and ethical implications in writing-intensive engineering classes. This pilot study investigates how the use of ChatGPT impacts students’ lab writing outcomes in terms of rhetorical knowledge, critical thinking and composing, knowledge of conventions, and writing processes. A group of undergraduate volunteers (n= 7) used ChatGPT to revise their original engineering lab reports written without using ChatGPT. A comparative study was conducted between original lab report samples and revisions by directly assessing students’ lab reports in gateway engineering lab courses. A focus group was conducted to learn their experiences and perspectives on ChatGPT in the context of engineering lab report writing. Implementing ChatGPT in the revision writing process could result in improving engineering students’ lab report quality due to students’ enhanced lab report genre understanding. At the same time, the use of ChatGPT also leads students to provide false claims, incorrect lab procedures, or extremely broad statements, which are not valued in the engineering lab report genre.

In support of the spiral wave theory of reentry, simulation studies and animal models have been utilized to show various patterns of spiral wave tip motion such as meandering and drifting. However, the demonstration of these or any other patterns in cardiac tissues have been limited. Whether such patterns of spiral tip motion are commonly observed in fibrillating cardiac tissues is unknown, and whether such patterns form the basis of ventricular tachycardia or fibrillation remain debatable. Using a computerized dynamic activation display, 108 episodes of atrial and ventricular tachycardia and fibrillation in isolated and intact canine cardiac tissues, as well as in vitro swine and myopathic human cardiac tissues, were analyzed for patterns of nonstationary, spiral wave tip motion. Among them, 46 episodes were from normal animal myocardium without pharmacological perturbations, 50 samples were from normal animal myocardium, either treated with drugs or had chemical ablation of the subendocardium, and 12 samples were from diseased human hearts. Among the total episodes, 11 of them had obvious nonstationary spiral tip motion with a life span of >2 cycles and with consecutive reentrant paths distinct from each other. Four patterns were observed: (1) meandering with an inward petal flower in 2; (2) meandering with outward petals in 5; (3) irregularly concentric in 3 (core moving about a common center); and (4) drift in 1 (linear core movement). The life span of a single nonstationary spiral wave lasted no more than 7 complete cycles with a mean of 4.6+/-4.3, and a median of 4.5 cycles in our samples. Conclusion: (1) Patently evident nonstationary spiral waves with long life spans were uncommon in our sample of mostly normal cardiac tissues, thus making a single meandering spiral wave an unlikely major mechanism of fibrillation in normal ventricular myocardium. (2) A tendency toward four patterns of nonstationary spiral tip motion was observed. (c) 1998 American Institute of Physics.

Background: The lab report is a commonly assigned genre in engineering lab courses; however, students often have difficulties meeting the expectations of writing in engineering labs. At the same time, it is challenging for engineering faculty to instruct lab report writing because they are often under-supported in writing pedagogies and usually unfamiliar with the extent of students’ prior writing knowledge. Literature review: Literature on technical communication in engineering addresses the importance of a rhetorical approach to writing instruction, as well as an emphasis on genre. Extending this literature, research into writing transfer provides valuable insight for better understanding how undergraduates negotiate the engineering lab report as a new genre within this distinct rhetorical context. Research questions: 1. How effective is a transfer-focused writing pedagogy in supporting students’ understanding of the genre conventions of engineering lab reports? 2. How does the transfer-focused writing pedagogy impact students’ writing quality in five categories (rhetorical knowledge, organization, evidence, critical thinking, and disciplinary conventions)? 3. What are the rhetorical features that engineering students improve or struggle with the most with lab report writing? Research methodology: Four engineering instructors and two English instructors participated in this study to design and develop the lab report writing instructional module, and implemented the module materials into their engineering lab courses. The module, consisting of lab report writing instruction and assessment resources, shares a rhetorical approach and foundational writing terms with first-year composition courses to emphasize a writing-transfer pedagogy. We collected and analyzed undergraduates’ lab report samples to evaluate the impact of the module on students’ writing performance. Two sets of lab reports were collected for analysis: the sample sets before (control), during the 2015–2016 academic year; and after (experimental) implementation of the module, during the 2016–2017 academic year. Results and conclusions: Data collected via pre- and post-implementation writing artifacts show that a rhetorical approach to teaching lab reports helped students better understand the expectations of the lab report as a discipline-specific genre, and it developed students’ understanding of the rhetorical features of engineering writing. The pilot module positively impacted the quality of students’ lab reports, a finding that suggests that using a transfer-focused writing pedagogy can successfully support the transfer and adaptation of writing knowledge into gateway or entry-level engineering laboratory courses.