This work presents a combined theoretical-experimental study of strain rate behavior in metals. The method is to experimentally calibrate and validate an Internal State Variable (ISV) constitutive model with a wide range of strain rate sensitivity. Therefore a practical apparatus and methodology for performing highly sought-after intermediate strain rate experimentation was created. For the first time in reported literature, the structure-property relations of Rolled Homogeneous Armor is quantified at the microscale and modeled with varying strain rates, temperatures, and stress states to capture plasticity and damage with a single set of constants that includes intermediate strain rates. A rolled homogeneous armor (RHA) was used as a material system to prove the methodology. In doing so, a newly implemented strain rate dependent nucleation parameter for RHA was implemented to transition the dominant damage mechanism from void growth to void nucleation as strain rate increased. The ISVs were utilized in finite element analysis for robust predictability of mechanical performance as well as predictability of microstructural evolution with regards to void size and number distribution. For intermediate strain rate experiments, robust load acquisition was achieved using a novel serpentine transmittal bar that allowed for long stress waves to traverse a short bar system; this system eliminated load- ringing that plagues servo-hydraulic systems. A direct hydraulic loading apparatus was developed to provide uniform strain rates throughout intermediate rate tests to improve on the current limitations of the state-of-the-art. Key recommendations on the advancement of predictive modeling of dynamic materials, as well as performing advanced dynamic experimentation, are elucidated.

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No description available.

Using photochemical and emulsion pro­cedures, a study has been made of the liquid-phase oxida­tion of p-cymene with respect to the nature of the result­ing hydroperoxides and their decomposition products, and the relative extent of oxidative attack at the methyl and iso­propyl groups. Hydroperoxide decomposition was negligible in the photochemical oxidations at 60C, and the product was shown to consist of 20% primary and 80% tertiary hydroper­oxide by reduction of the total product and fractionation of the resulting alcohols. The following compounds were shown to be present in the emulsion oxidation product in addition to the above mentioned hydroperoxides: dimethyl-p-tolylcarbinol, p-methylacetophenone, p-isopropylphenylcarbinol, cumic acid, p-acetobenzoic acid, p-A-hydroperoxyisopropyl, benzoic acid, and p-(I-hydroxyisopropyl) benzoic acid. By chromatographic separation of the acids and reduction of the other products, the relative extent of attack at the two positions was shown to be 1:4, identical with that of the photochemical oxidation. Pure tertiary hydroperoxide has been obtained for the first time. / Thesis / Master of Science (MS)

No description available.

Currently, most students with disabilities (SWDs) receive a majority of their education in the general education classroom (U.S. Department of Education, 2019). This inclusive practice reflects educational and accountability requirements described in the Individuals with Disabilities Education Improvement Act (2004) and the Every Student Succeeds Act (2015). To address these requirements, schools seek service delivery models that support SWDs and close achievement gaps (Murawski & Goodwin, 2014). In this study, the researcher investigated the lived experiences of highly effective middle school teachers using co-teaching as a service delivery model to support SWDs in the general education classroom. The researcher used a phenomenological qualitative approach for this study. The research was conducted in a large urban district in the western United States. The researcher conducted face-to-face interviews with individual teachers with three pairs of co-teachers assigned to a co-teach model in a middle school mathematics classroom. The researcher was also able to observe one planning session between one pair of co-teachers. Using a spiral analysis procedure, three themes emerged from the interview and observation data as well as six subthemes. The three themes were (a) collaboration of lesson development, (b) student learning, and (c) parity. The researcher described the themes using thick, rich descriptions, provides a connection between research and the findings, and suggests recommendations for future research.

This corpus-based, qualitative descriptive study examines the vocabulary in digital science resources for middle school students in the United States. In brief, two corpora, each of approximately 2.7 million tokens, were assembled: the Digital Science Corpus (DSC) and the Digital Fiction Corpus (DFC). The 3,456 digital science resources included in the DSC were selected based on the findings of a detailed survey of 91 U.S.-based middle school teachers. In this study, AntWordProfile (Anthony, 2021), AntConc (Anthony, 2019), and WordSmith Tools (Scott, 2020) were used to (a) lexically profile the corpus to determine the vocabulary load of vocabulary in the corpus, (b) lexically profile the corpus to estimate the extent to which a combination of well-known word lists (GSL+AWL+ EAP Science List, the top 570 AVL word families, GSL+MSVL for Science) might help students to reach text coverage that could result in reasonable comprehension of the texts in the corpus (i.e., lexical coverage), and (c) create a Digital Science List (DSL) that captures the most frequent words types in the corpus. The word types in the DSL were validated with the Digital Fiction Corpus (DFC), a corpus formed from an approximately equal number of tokens as the DSC but gathered from fiction novels. The findings of this study show that the top 570 word families in the AVL (Gardner & Davies, 2014) provide 75% more lexical coverage in the digital corpus than the 570 word families in the older AWL (Coxhead, 2000) (10.07% vs. 5.76%). To reach a threshold of 95% coverage that is conventionally deemed to facilitate minimal reading comprehension (Laufer, 2020), middle school (MS) students must recognize the first 6,000 most frequent BNC/COCA (Nation, 2012) word families plus proper nouns or the first 11,000 most frequent BNC/COCA word families without proper nouns. Furthermore, to reach 98% coverage for optimal reading comprehension of digital science texts requires recognizing words within the 19,000 most frequent word families in the BNC/COCA plus proper nouns. In contrast, the GSL, AWL, and EAP Science List with far fewer word families ( < 3,000) offer a striking 88.35% lexical coverage across the corpus, while the GSL and the MSVL for Science with fewer than 2,500 word families offer a remarkable 87.79% lexical coverage across the corpus. The DSL produced from this research identified 412 types based on seven corpus-based and judgment-based criteria. The lexical profiling analysis of the DSL across the DSC revealed that the DSL provides 8.64% lexical coverage. While the DSL can be used as a teaching and learning tool in middle school classrooms, this list is specifically helpful for second language (L2) because it contains 136 general high-frequency types with a specialized meaning (e.g., dating, work, etc.). The study addresses methodological, theoretical, and pedagogical implications so that middle school learners can gain better support in their science vocabulary development and achieve better science reading comprehension of digital science texts.

This qualitative, ethnographically informed case-study examines how social, psychological, and organizational factors of a culture impact writing instruction and practice within an English Language Arts middle school class. In order to explore possible reasons for stagnant writing instruction in middle schools, two research questions guided this study: (RQ1) What do the components of writing instruction look like in one middle school class?, and (RQ2) How does one middle school ELA class exhibit identity distinction, writing development, and discourse surrounding writing instruction? I examined how one middle school class exhibits identity distinction among students and teachers within writing, development of writing, and discourse surrounding writing instruction and practice. Data were collected through observations, field notes, interviews, and cultural artifacts (i.e., lesson plans, student data, student work samples, and district curriculum) over a five week period for a total of 18 data collection days (16 of which were observations). Observations were conducted in one seventh grade teacher's class period and lesson planning meetings. The seventh grade teacher, students, and Testing Coordinator were interviewed for member checking sessions pertaining to observations and student work. Semi-structured interview verbatim transcripts were audio recorded and transcribed, after which the following themes emerged: understanding of writing instruction, understanding of writing workshop, confidence in students' writing abilities, establishing spaces for student engagement, feedback on student writing, and teacher and student identities. Also included are recommendations for establishing a positive writing culture through improved middle school writing instruction.

The purpose of this study was to investigate how the lived experiences and views of fourth- and fifth-grade math teachers who implemented project-based learning (PBL) addressed the needs of their at-risk students in urban schools. The researcher examined the use of PBL in mathematics-impacted instruction, seeking to understand teacher beliefs related to the influence of exposure to PBL experiences on students' academic outcomes. When deliberately planned and embedded into teaching, the implementation of PBL helps students retain content, improve attitudes about learning, and improve their ability to collaborate with others (Cervantes et al., 2015). A literature review was conducted to explore PBL and its relationship with constructivism, growth mindset, and cooperative learning and the degree to which these teaching methods affect student learning. A growth mindset enables students to consider inquiry, exploration, and student collaboration (Larmer et al., 2015). Also present in PBL are cooperative learning activities, which Slavin (2015) found encouraged students to work together on projects that required the inclusion and student application of content standards. Qualitative research methodology using the phenomenological method was implemented in this study. The study investigated the lived experiences of fourth and fifth-grade math teachers who implemented PBL in urban schools. The researcher interviewed teachers who have participated in project-based learning with their students. Results and discussion are included for the research question as well as implications of the findings, recommendations, and suggestions for future research.

High-quality and effective professional development is necessary and "…should be made available to all teachers" (Borko, 2004, p. 3). This dissertation focuses on teacher professional development (PD) and an exploration into the meaning teachers attribute to a PD experience. Stemming from interdisciplinary questions such as, how do we align PD to meet teachers' needs and expectations? and how do teachers learn?, this study aims to examine the experiences and meanings of specific sixth grade ELA teachers in their participation in District PD, a district-led PD series using Interpretative Phenomenological Analysis (IPA). IPA stems from qualitative and ontology research perspectives and captures the context of human experience, phenomena, and life. After thorough analysis of each participant interview transcript and reflection, the results of this dissertation shed light about the reality of the District PD experience for each of the three participants. Moreover, these findings indicated five themes: Teacher Embodiment, the District PD Experience, the Meaning of PD, the Success and Value of District PD, and Unexpected Findings. These themes demonstrated the need for teachers to be heard, their epistemological beliefs to be acknowledged, their meanings of a PD experience, and the design of PD that enhances task value, expectancies for success, and cost across all PD experiences. Results suggested the flexibility of IPA and its application to current PD practices of teachers' experiences and meaning. Implications and recommendations such as, a prescreening survey given to future participants would aid the development of an aligned PD for teacher participations and collecting data across all four sessions of District PD would better inform this phenomenon. Further research into teacher PD and IPA across other disciplines are also presented and discussed. These include researching participatory research approaches, a longitudinal study of District PD over a course of two years, and the intersectionality of teacher PD, Interpretative Phenomenological Analysis, and Expectancy Value Theory (EVT).