On Reduced Input-Output Dynamic Mode Decomposition

The identification of reduced-order models from high-dimensional data is a challenging task, and even more so if the identified system should not only be suitable for a certain data set, but generally approximate the input-output behavior of the data source. In this work, we consider the input-output dynamic mode decomposition method for system identification. We compare excitation approaches for the data-driven identification process and describe an optimization-based stabilization strategy for the identified systems

Goal-setting And Achievement In Activity Tracking Apps: A Case Study Of MyFitnessPal

Activity tracking apps often make use of goals as one of their core motivational tools. There are two critical components to this tool: setting a goal, and subsequently achieving that goal. Despite its crucial role in how a number of prominent self-tracking apps function, there has been relatively little investigation of the goal-setting and achievement aspects of self-tracking apps. Here we explore this issue, investigating a particular goal setting and achievement process that is extensive, recorded, and crucial for both the app and its users' success: weight loss goals in MyFitnessPal. We present a large-scale study of 1.4 million users and weight loss goals, allowing for an unprecedented detailed view of how people set and achieve their goals. We find that, even for difficult long-term goals, behavior within the first 7 days predicts those who ultimately achieve their goals, that is, those who lose at least as much weight as they set out to, and those who do not. For instance, high amounts of early weight loss, which some researchers have classified as unsustainable, leads to higher goal achievement rates. We also show that early food intake, self-monitoring motivation, and attitude towards the goal are important factors. We then show that we can use our findings to predict goal achievement with an accuracy of 79% ROC AUC just 7 days after a goal is set. Finally, we discuss how our findings could inform steps to improve goal achievement in self-tracking apps

Fast Computation of Sepλ_\lambda via Interpolation-based Globality Certificates

Given two square matrices $A$ and $B$, we propose a new approach for computing the smallest value $\varepsilon \geq 0$ such that $A+E$ and $A+F$ share an eigenvalue, where $\|E\|=\|F\|=\varepsilon$. In 2006, Gu and Overton proposed the first algorithm for computing this quantity, called $\mathrm{sep}_\lambda(A,B)$ ("sep-lambda"), using ideas inspired from an earlier algorithm of Gu for computing the distance to uncontrollability. However, the algorithm of Gu and Overton is extremely expensive, which limits it to the tiniest of problems, and until now, no other algorithms have been known. Our new algorithm can be orders of magnitude faster and can solve problems where $A$ and $B$ are of moderate size. Moreover, our method consists of many "embarrassingly parallel" computations, and so it can be further accelerated on multi-core hardware. Finally, we also propose the first algorithm to compute an earlier version of sep-lambda where $\|E\| + \|F\|=\varepsilon$.Comment: Revision #3, March 22, 202

Junior Recital:Tyler Mitchell, violin

This recital is presented in partial fulfillment of the requirements for the degree Bachelor of Music in Performance Mr. Mitchell studies violin with Helen Kim.https://digitalcommons.kennesaw.edu/musicprograms/1646/thumbnail.jp

The Promise of Johannesburg: Fisheries and the World Summit on Sustainable Development

This article briefly examines the world fish crisis and the factors that drive overuse of ocean resources. It identifies some of the major trends in ocean fishing that have led to over-exploitation and briefly reviews the weaknesses of international fishery arrangements that led to WSSD. It describes and evaluates the outcomes of the WSSD and suggests some measures that can and must be taken to the address the crisis facing world ocean fish stocks

Phase VI Glove Durability Testing

The current state-of-the-art space suit gloves, the Phase VI gloves, have an operational life of 25 -- 8 hour Extravehicular Activities (EVAs) in a dust free, manufactured microgravity EVA environment. Future planetary outpost missions create the need for space suit gloves which can endure up to 90 -- 8 hour traditional EVAs or 576 -- 45 minute suit port-based EVAs in a dirty, uncontrolled planetary environment. Prior to developing improved space suit gloves for use in planetary environments, it is necessary to understand how the current state-of-the-art performs in these environments. The Phase VI glove operational life has traditionally been certified through cycle testing consisting of International Space Station (ISS)-based EVA tasks in a clean environment, and glove durability while performing planetary EVA tasks in a dirty environment has not previously been characterized. Testing was performed in the spring of 2010 by the NASA Johnson Space Center (JSC) Crew and Thermal Systems Division (CTSD) to characterize the durability of the Phase VI Glove and identify areas of the glove design which need improvement to meet the requirements of future NASA missions. Lunar simulant was used in this test to help replicate the dirty lunar environment, and generic planetary surface EVA tasks were performed during testing. A total of 50 manned, pressurized test sessions were completed in the Extravehicular Mobility Unit (EMU) using one pair of Phase VI gloves as the test article. The 50 test sessions were designed to mimic the total amount of pressurized cycling the gloves would experience over a 6 month planetary outpost mission. The gloves were inspected periodically throughout testing, to assess their condition at various stages in the test and to monitor the gloves for failures. Additionally, motion capture and force data were collected during 18 of the 50 test sessions to assess the accuracy of the cycle model predictions used in testing and to feed into the development of improved cycle model tables. This paper provides a detailed description of the test hardware and methodology, shares the results of the testing, and provides recommendations for future work