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The use of ultrasonic guided wave, which has been widely accepted as a conventional, screening NDE tool to overcome the inaccessibility of large scale structural integrities is now being extended to early stage damage detection in conjunction with its nonlinear features for more precise material characterization. The status of guided wave based NDE is evolved from detecting geometric defects to monitoring strength related ones. Combining guided wave based NDE schemes with its nonlinearity is challenging due to the existence of multiple modes, the dispersive manner and the need of proper mode tuning. In this paper, some key concepts for the success will be introduced along with recent accomplishments including nonlinear guided wave imaging and application to composites.

Sonication with fast scanning method can generate homogeneous lesions without complex planning. But when the target region is large, switching focus too fast will reduce the heat accumulation, the margin of which may not ablated. Furthermore, high blood perfusion rate will reduce this maximum volume that can be ablated. Therefore, fast scanning method may not be applied to large volume tumor. To expand the therapy scope, this study combines the fast scan method with multiple mode strategy. Through simulation and experiment, the feasibility of this new strategy is evaluated and analyzed.

In a course organized around the development of diverse representations, no single mode of expression offers a complete picture of participants’ understanding of the nature of energy. Instead, we argue, their understanding is actively constructed through the simultaneous use of a range of quite different kinds of representational resources (Goodwin, 2000; Hutchins, 1995; Ochs, Gonzales, & Jacoby, 1996), including not only words and prosody but also gestures, symbolic objects, participants moving their bodies in concert, and whatever other communicative modes the course invites them to use. Examples are provided from a teacher professional development course on energy.

A periodic multimode waveguide provides contradirectional feedback of all its modes. The relative constancy of feedback strength results in regular bands and stripes of minigaps at zone edges. A critical coupling strength was recently shown to flatten the bands and provide collective slow light. We connect these aspects to the “Littrow lasing” geometry and to spontaneous emission modification on the application side or to “dark modes” on the theoretical side.

Problem‐solving is an important part of physics teaching, learning and assessment. It is widely assumed that the way that experts solve problems, and students should, is by systematic application of basic physics principles. Model solutions are laid out this way, and teaching of problem‐solving usually consists of ‘going over’ such solutions step by step. However, while this does represent the physics structure of the final solution, it does not adequately reflect how people actually think when tackling problems. Real cognition is complex. This study was prompted by students trying to ‘map across’ result features recalled from previous cases instead of working from basics. Since our instruction emphasizes the power and generality of basic principles, our first response was to re‐emphasize principles, but we found that experts in fact draw extensively and effectively on rich compiled case knowledge. We investigated cognition in detail for geometrical optics. Research methods included analysis of written so...