Modeling of Progressive Damage in Fiber-Reinforced Ceramic Matrix Composites

An analytic methodology is developed to model the response of fiber-reinforced ceramic matrix composites (CMOs) when subjected to monotonic and fatigue loadings. The analysis requires the formulation of (1) a micromechanics model which defines the laminate\u27s geometry and constitutive relationship; (2) failure criteria which estimate the extent of microstructural damage, and, finally, (3) a means of analyzing frictional slip, fiber pull-out, interfacial wear and laminate failure. For the present study, the behavior of unidirectional and crossply CMOs is investigated using modified shear-lag theory in conjunction with a set of failure criteria with a minimum reliance on empirical data. The damage mechanisms considered are matrix cracking, fiber/matrix interfacial debonding and fiber fracture. The stress-strain response under monotonic tensile loading, and the fatigue life (S-N relationship) and stress-strain hysteresis under cyclic loading obtained from the present solution are compared with their experimental counterparts. They are in good agreement with one another. As expected, the assumed degradation in the frictional resistance along the constituent interface plays a dominant role in determining the material response

Risks to Student Achievement in Higher Education

Abstract. A university system sets out to deliver educational experiences that meet set goals such as the achievement of learning outcomes for individual courses and program outcomes for degree programs. There are many factors that impact the successful achievement of student learning outcomes and therefore success-ful program design and implementation. If courses are not effectively designed with assessments properly aligned to learning outcomes, student achievement is challenging to measure. If faculty do not consistently adhere to college and/or uni-versity policies regarding submission of assignments, student behavior and per-ceptions of expectations in future courses may be skewed. In addition, students may, for various reasons make choices that result in failure to submit assignments that serve as measures of achievement for learning objectives. All of these fac-tors could lead to a system breakdown and subsequent research location failure to meet the established goals, i.e. student learning outcomes. In this case study, an introduction to aeronautics course used to determine if the failure to submit assignments significantly impacted the achievement of stated program outcomes using a systems engineering approach. Data from core courses required for degree completion were used in the study. The results indicated that the lack of assign-ment submission presents a flaw in the system design and that the risk of not meeting learning objectives and program outcomes is very high when students fail to submit assignments

Risks to Student Achievement in Higher Education

A university system sets out to deliver educational experiences that meet set goals such as the achievement of learning outcomes for individual courses and program outcomes for degree programs. There are many factors that impact the successful achievement of student learning outcomes and there-fore successful program design and implementation. If courses are not effec-tively designed with assessments properly aligned to learning outcomes, student achievement is challenging to measure. If faculty do not consistently adhere to college and/or university policies regarding submission of assignments, student behavior and perceptions of expectations in future courses may be skewed. In addition, students may, for various reasons make choices that result in failure to submit assignments that serve as measures of achievement for learning objec-tives. All of these factors could lead to a system breakdown and subsequent re-search location failure to meet the established goals, i.e. student learning out-comes. In this case study, an introduction to aeronautics course used to deter-mine if the failure to submit assignments significantly impacted the achieve-ment of stated program outcomes using a systems engineering approach. Data from core courses required for degree completion were used in the study. The results indicated that the lack of assignment submission presents a flaw in the system design and that the risk of not meeting learning objectives and program outcomes is very high when students fail to submit assignments

Evaluation of sUAS Education and Training Tools

The wide distribution and demographic composition of students seeking small unmanned aircraft system (sUAS) education presents a need to fully understand the capabilities, limitations, and dependencies of effective training tools. Concepts, practices, and technologies associated with modeling and simulation, immersive gaming, augmented and mixed-reality, and remote operation have demonstrated efficacy to support engaged student learning and objective satisfaction. Identification and comparison of key attributes critical to an aviation educational framework, such as competency-based training, enables educational designers to identify those tools with the highest potential to support successful learning. A series of factors, such as system performance, regulatory compliance, environmental conditions, technological familiarity, and personal experience, require consideration in the selection, optimization, and application of such tools. Embry-Riddle and the Sinclair College National UAS Training and Certification Center have overseen the development, launch, and sustainment of respective sUAS education programs. Effectiveness of these programs is dependent on continuous evaluation of tools, specific to educational settings. A relevant example was the assessment of popular multirotor sUAS conducted by ERAU-W, which led to publication of the “Small Unmanned Aircraft System Consumer Guide” and selection of the Parrot BeBop 2 platform to support sUAS operations curricula. The intent of this work is to present critical considerations, including influencing factors and dependencies, associated with the selection and adoption of technological tools best supporting sUAS education. Background details; emerging approaches, models, and technologies; and examples of past tool evaluation, inclusive of assessment criteria and observations, are discussed. Finally, a series of reflective remarks, including recommendations, relating to evaluation, adaptation, and incorporation of future tools supporting sUAS education are presented

Viability and Application of Mounting Personal PID VOC Sensors to Small Unmanned Aircraft Systems

Using a UAS-mounted sensor to allow for a rapid response to areas that may be difficult to reach or potentially dangerous to human health can increase the situational awareness of first responders of an aircraft crash site through the remote detection, identification, and quantification of airborne hazardous materials. The primary purpose of this research was to evaluate the remote sensing viability and application of integrating existing commercial-off-the-shelf (COTS) sensors with small unmanned aircraft system (UAS) technology to detect potentially hazardous airborne contaminants in emergency leak or spill response situations. By mounting the personal photoionization detector (PID) with volatile organic compound VOC sensor technology on UAS platforms, the needed information may be obtained at an optimum range and resolution without needlessly exposing a human to possible adverse conditions

Carotid Baroreflex Activation: Past, Present, and Future

Electrical activation of the carotid baroreceptor system is an attractive therapy for the treatment of resistant hypertension. In the past, several attempts were made to directly activate the baroreceptor system in humans, but the method had to be restricted to a few selected patients. Adverse effects, the need for better electrical devices and better surgical techniques, and the lack of knowledge about long-term effects has greatly hampered developments in this area for many years. Recently, a new and promising device was evaluated in a multicenter feasibility trial, which showed a clinically and statistically significant reduction in office systolic blood pressure (>20 mm Hg). This reduction could be sustained for at least 2 years with an acceptable safety profile. In the future, this new device may stimulate further application of electrical activation of the carotid baroreflex in treatment-resistant hypertension