Integral control of port-Hamiltonian systems: non-passive outputs without coordinate transformation

In this paper we present a method for the addition of integral action to non-passive outputs of a class of port-Hamiltonian systems. The proposed integral controller is a dynamic extension, constructed from the open loop system, such that the closed loop preserves the port-Hamiltonian form. It is shown that the controller is able to reject the effects of both matched and unmatched disturbances, preserving the regulation of the non-passive outputs. Previous solutions to this problem have relied on a change of coordinates whereas the presented solution is developed using the original state vector and, therefore, retains its physical interpretation. In addition, the resulting closed loop dynamics have a natural interpretation as a Control by Interconnection scheme.Comment: 8 pages, 2 figure

IMLS Sparks Ignite IL Framework Cooperative Project Final Performance Report, Appendix D: Focus Group Report

This appendix to the Final Performance Report for the IMLS Sparks IL Cooperative Project grant is the report on the focus groups. The focus group research summarized herein represents a segment of the overall IMLS grant proposal process, and should be viewed not as a separate endeavor, but rather as an integrated approach to the overall research questions in the grant proposal. In conjunction with the pre-test/post-test survey driven component, the findings from the focus group research help to strengthen the case for the value of librarian-driven pedagogy in positively impacting the academic and intellectual growth of all students, and potentially at-risk students in particular, at the participating colleges

Identifying ILI Cases from Chief Complaints: Comparing the Accuracy of Keyword and Support Vector Machine Methods

We compared the accuracy of two methods of identifying ILI cases from chief complaints. We found that a support vector machine method was more accurate than a keyword method

Influence of thickness and interface on the low-temperature enhancement of the spin Seebeck effect in YIG films

The temperature dependent longitudinal spin Seebeck effect (LSSE) in heavy metal (HM)/Y3Fe5O12 (YIG) hybrid structures is investigated as a function of YIG film thickness, magnetic field strength, and different HM detection material. The LSSE signal shows a large enhancement with reducing the temperature, leading to a pronounced peak at low temperatures. We find the LSSE peak temperature strongly depends on the film thickness as well as on the magnetic field. Our result can be well explained in the framework of magnon-driven LSSE by taking into account the temperature dependent effective propagation length of thermally excited magnons in bulk. We further demonstrate that the LSSE peak is significantly shifted by changing the interface coupling to an adjacent detection layer, revealing a more complex behavior beyond the currently discussed bulk effect. By direct microscopic imaging of the interface, we correlate the observed temperature dependence with the interface structure between the YIG and the adjacent metal layer. Our results highlight the role of interface effects on the temperature dependent LSSE in HM/YIG system, suggesting that the temperature dependent spin current transparency strikingly relies on the interface conditions

Incorporating High-Frequency Weather Data into Consumption Expenditure Predictions

Recent efforts have been very successful in accurately mapping welfare in datasparse regions of the world using satellite imagery and other non-traditional data sources. However, the literature to date has focused on predicting a particular class of welfare measures, asset indices, which are relatively insensitive to short term fluctuations in well-being. We suggest that predicting more volatile welfare measures, such as consumption expenditure, substantially benefits from the incorporation of data sources with high temporal resolution. By incorporating daily weather data into training and prediction, we improve consumption prediction accuracy significantly compared to models that only utilize satellite imagery

Experimental Study of Arcing on High-voltage Solar Arrays

The main obstacle to the implementation of a high-voltage solar array in space is arcing on the conductor-dielectric junctions exposed to the surrounding plasma. One obvious solution to this problem would be the installation of fully encapsulated solar arrays which were not having exposed conductors at all. However, there are many technological difficulties that must be overcome before the employment of fully encapsulated arrays will turn into reality. An alternative solution to raise arc threshold by modifications of conventionally designed solar arrays looks more appealing, at least in the nearest future. A comprehensive study of arc inception mechanism [1-4] suggests that such modifications can be done in the following directions: i) to insulate conductor-dielectric junction from a plasma environment (wrapthrough interconnects); ii) to change a coverglass geometry (overhang); iii) to increase a coverglass thickness; iiii) to outgas areas of conductor-dielectric junctions. The operation of high-voltage array in LEO produces also the parasitic current power drain on the electrical system. Moreover, the current collected from space plasma by solar arrays determines the spacecraft floating potential that is very important for the design of spacecraft and its scientific apparatus. In order to verify the validity of suggested modifications and to measure current collection five different solar array samples have been tested in large vacuum chamber. Each sample (36 silicon based cells) consists of three strings containing 12 cells connected in series. Thus, arc rate and current collection can be measured on every string independently, or on a whole sample when strings are connected in parallel. The heater installed in the chamber provides the possibility to test samples under temperature as high as 80 C that simulates the LEO operational temperature. The experimental setup is described below

Exponential Stability and Local ISS for DC Networks

In this letter, we consider the problem of regulating the voltage of an islanded Direct Current (DC) network subject to (i) unknown ZIP-loads, i.e., nonlinear loads with the parallel combination of constant impedance (Z), current (I) and power (P) components, and (ii) unknown time-varying disturbances. Using the port-Hamiltonian framework, two decentralized passivity-based control schemes are designed. It is shown that, using the proposed controllers, the desired equilibrium is exponentially stable and local input-to-state stable (LISS) with respect to unknown time-varying disturbances

The Lost Cafeteria: Poems

Taking its cues from the twentieth century life writing of Robin Blaser, Frank O’Hara, William Everson, Sylvia Plath and Alden Nowlan, The Lost Cafeteria is a stylistically shapeshifting bildungsroman-in-verse which examines and attempts to resolve the author’s parochially religious upbringing with his secular, peripatetic adulthood. Exploring the shape of the “I-within-history,” Ferguson mixes confessional lyric poetry with experimental détournements of texts from high and low culture to visit (and revisit) issues of labour, rebellion, family (biological and chosen), class, travel, memory (personal and historical), religion, place, and the meanings of the word “home.