Characterization and modeling of aperiodic pressure oscillations in combustion chambers

Classification of the long-term dynamical behavior of pressure oscillations in a laboratory combustion chamber has been performed using methods of modern dynamical systems theory. The method involves the construction of a phase-space representation from a single pressure record or time series using the time-delay embedding method. The pointwise correlation dimension of the resulting attractor in phase-space provides a lower bound on the number of modes that participate in the oscillations. The results show that the oscillations are quasiperiodic with a dimension near two over an order of magnitude of amplitudes. Quasiperiodicity is a result of the incommensurate frequencies of the system acoustic modes. A model for the dynamics is constructed by converting the governing equations to a kicked-oscillator model. When compared with the experimental data, the model results have similar pressure and velocity spectra and the attractor dimension verifies that quasiperiodic oscillations are present

How Does Leadership Matter? Developing and Teaching a Definition of Hands-On Science, a Prerequisite for Effective Inquiry Teaching

This descriptive case study describes leadership skills and planning for setting clear directions by program leaders for a statewide professional development initiative to extend improvement in science teaching and learning. For science teachers and leaders in Virginia, a critical part of setting clear goals that everyone can understand is defining key science terms. One of the four key terms, hands-on science, is defined here. Materials to develop teachers\u27 understanding of the term for effective implementation of classroom inquiry activities are shared, along with a rubric for evaluation by and for teachers. Understanding of the term hands-on science is necessary before inquiry-based science teaching can be fully implemented. Authentic science materials, when safe, are necessary for doing authentic, inquiry-based science teaching in a way similar to how a scientist investigates science

Teaching and Learning Seminar for Science and Mathematics Faculty

A yearlong seminar for science and mathematics faculty to investigate teaching and learning is in its second year at George Mason University in Fairfax, Virginia. This article describes the seminar and preliminary findings from the first year

The Teacher Shortage: National Trends for Science and Mathematics Teachers

The shortage of science and mathematics teachers is a growing problem in the United States. This article looks at what research says about the causes for the growing teacher shortage and its effects on student achievement. As the teacher shortage worsens, teachers without a science or mathematics backgrounds are tasked to teach science and mathematics or underqualified teachers are being hired to fill the shortage. These underqualified teachers are not remaining in the profession, thus not solving the teacher shortage problem and creating an even higher turnover rate for teachers. In addition, experienced teachers are leaving the profession in greater numbers due to low salaries and job dissatisfaction. Research indicates that the initial preparation and support of teachers as they enter the profession is critical to surviving the beginning years and remaining in the profession. Additionally, well-prepared teachers have the largest impact on effective classroom practice and high student achievement

Third International Mathematics and Science Study (TIMSS) and the Nature of College Courses

The TIMSS report leads to some strong conclusions concerning the effectiveness of various approaches for teaching mathematics and science in grades K-8. This presentation will focus on a description of the findings of TlMSS concerning effective teaching. Although the TIMSS study and its findings relate directly to teaching prior to college, the findings do have a lot to say about effective teaching at the college level. At the very least, they describe the type of teaching and learning that future teachers must experience if they are to bring about this type of learning in their own courses

Maximizing the Impact of Professional Development for Earth Science Teachers

This study examines the extent to which follow-up sessions can provide support for earth science teachers as they apply what they learn from professional development coursework during the academic year with their own students. Data include direct observation of follow-up sessions of courses for teachers; interviews with course co-instructors and teacher participants; and, document analysis of teacher products with a focus on the lesson plans, laboratory/activity sheets for students, and virtual field trips that teacher participants submitted and shared during follow-up sessions. Strategies are recommended to assist earth science content faculty in increasing the impact of their work with teachers and hence, student instruction