Verifying the Safety of a Flight-Critical System

This paper describes our work on demonstrating verification technologies on a flight-critical system of realistic functionality, size, and complexity. Our work targeted a commercial aircraft control system named Transport Class Model (TCM), and involved several stages: formalizing and disambiguating requirements in collaboration with do- main experts; processing models for their use by formal verification tools; applying compositional techniques at the architectural and component level to scale verification. Performed in the context of a major NASA milestone, this study of formal verification in practice is one of the most challenging that our group has performed, and it took several person months to complete it. This paper describes the methodology that we followed and the lessons that we learned.Comment: 17 pages, 5 figure

What Does an Exemplary Middle School Mathematics Teacher Look Like? The Use of a Professional Development Rubric

A School University Research Network (SURN) committee composed of current mathematics teachers, central office math supervisors, building administrators, mathematicians, and mathematics educators researched numerous sources regarding best practices in mathematics instruction. The resulting professional development rubric synthesizes their findings and can serve a professional development role by providing teachers and administrators with a tool to develop clarity and consensus on best mathematics instructional practices, and how these practices are implemented in the classroom. It is also being used as a tool for cooperating teachers in their supervision of student teachers and as a reflective method for self-evaluation

The JKind Model Checker

JKind is an open-source industrial model checker developed by Rockwell Collins and the University of Minnesota. JKind uses multiple parallel engines to prove or falsify safety properties of infinite state models. It is portable, easy to install, performance competitive with other state-of-the-art model checkers, and has features designed to improve the results presented to users: inductive validity cores for proofs and counterexample smoothing for test-case generation. It serves as the back-end for various industrial applications.Comment: CAV 201

Certification Considerations for Adaptive Systems

Advanced capabilities planned for the next generation of aircraft, including those that will operate within the Next Generation Air Transportation System (NextGen), will necessarily include complex new algorithms and non-traditional software elements. These aircraft will likely incorporate adaptive control algorithms that will provide enhanced safety, autonomy, and robustness during adverse conditions. Unmanned aircraft will operate alongside manned aircraft in the National Airspace (NAS), with intelligent software performing the high-level decision-making functions normally performed by human pilots. Even human-piloted aircraft will necessarily include more autonomy. However, there are serious barriers to the deployment of new capabilities, especially for those based upon software including adaptive control (AC) and artificial intelligence (AI) algorithms. Current civil aviation certification processes are based on the idea that the correct behavior of a system must be completely specified and verified prior to operation. This report by Rockwell Collins and SIFT documents our comprehensive study of the state of the art in intelligent and adaptive algorithms for the civil aviation domain, categorizing the approaches used and identifying gaps and challenges associated with certification of each approach

Amplification and reversal of Knudsen force by thermoelectric heating

We show that the Knudsen thermal force generated by a thermally-induced flow over a heated beam near a colder wall could be amplified significantly by thermoelectric heating. Bidirectional actuation is achieved by switching the polarity of the thermoelectric device bias voltage. The measurements of the resulting thermal forces at different rarefaction regimes, realized by changing geometry and gas pressure, are done using torsional microbalance. The repulsive or attractive forces between a thermoelectrically heated or cooled plate and a substrate are shown to be up to an order of magnitude larger than for previously studied configurations and heating methods due to favorable coupling of two thermal gradients. The amplification and reversal of the Knudsen force is confirmed by numerical solution of the Boltzmann-ESBGK kinetic modelequation. Because of the favorable scaling with decreasing system size, the Knudsen force with thermoelectric heating offers a novel actuation and sensing mechanism for nano/microsystems

Role of the Semi-lunar Process in Locust Jumping

We have developed a software toolkit, AnimatLab, which allows researchers to build and test virtual organisms. We used this software to build a virtual locust, and then asked how the semi-lunar process is utilized during jumping, and how manipulation or removal of the virtual SLP influences jump dynamics

Application of Dynamic System Identification to Timber Beams - part I

In this first part of a two-part paper, development of a method of dynamic system identification for timber beams is presented with an analytical verification of the method using a finite-element model. A method of global nondestructive evaluation for identifying local damage and decay in timber beams is investigated in this paper. Experimental modal analysis is used in conjunction with a previously developed damage localization algorithm. The damage localization algorithm utilizes changes in modal strain energy between the mode shapes of a calibrated model, representing the undamaged state of the beam of interest, and the experimentally obtained mode shapes for a timber beam. Analytical evaluations were performed to demonstrate and verify the use of this method of global nondestructive evaluation for the localization of damage or decay in timber beams. In a companion paper, experimental laboratory tests are presented that verify the use of dynamic system identification to locate damage within timber beams