Providing a Safe, In-Person, Residential College Experience During the COVID-19 Pandemic

Due to the COVID-19 pandemic, higher education institutions were forced to make difficult decisions regarding the 2020–2021 academic year. Many institutions decided to have courses in an online remote format, others decided to attempt an in-person experience, while still others took a hybrid approach. Hope College (Holland, MI) decided that an in-person semester would be safer and more equitable for students. To achieve this at a residential college required broad collaboration across multiple stakeholders. Here, we share lessons learned and detail Hope College's model, including wastewater surveillance, comprehensive testing, contact tracing, and isolation procedures that allowed us to deliver on our commitment of an in-person, residential college experience

Modeling and Control of Bi-directional Discrete Linear Repetitive Processes

Abstract—Repetitive processes are characterized by a series of sweeps or passes through a set of dynamics defined over a finite duration where the output produced on any pass acts as a forcing function on, and hence contributes to, the dynamics of the next pass. The resulting control problem is that the output sequence of pass profiles can contain oscillations that increase in amplitude in the pass-to-pass direction. This paper considers bi-directional operation, i.e. a pass is completed and at the end the next one begins but in the opposite direction. In particular, a model for such a process in the case of discrete dynamics is first proposed and new results on stability and control law design for stabilization and performance developed

Stabilization of discrete linear repetitive processes with switched dynamics

Repetitive processes are a distinct class of 2D systems (i.e. information propagation in two independent directions) of both systems theoretic and applications interest. They cannot be controlled by direct extension of existing techniques from either standard (termed 1D here) or 2D systems theory. Here we give new results on the relatively open problem of the design of physically based control laws. These results are for a sub-class of discrete linear repetitive processes with switched dynamics in both independent directions of information propagation

Multi-machine operations modelled and controlled as switched linear repetitive processes

Many industrial processes involve the processing of a single workpiece by successively passing it through a sequence of machines. The most common example is metal rolling where the metal strip of finite length is shaped by passing it through different sets of rolls and the output from one forms the input to the next and so on. In this paper, we develop a new approach to the analysis and overall control of such systems by first modelling them as a linear repetitive process with switched dynamics. The end result is control law design algorithms which can be implemented using LMI based computations

Switched Differential Linear Repetitive Processes

Differential linear repetitive processes are a distinct class of 2D systems where information propagation in one of the two directions only occurs over a finite duration, termed the pass length. Information propagation in one direction of information propagation is governed by a linear differential equation, and in the second by a linear difference equation. Moreover, the output, or pass profile, produced on any pass acts as a forcing function on, and hence contributes to, the dynamics of the next one. The exact sequence of operation is that a pass is completed and then the process is reset to the original location for the start of the next one and so on, and the result can be oscillations that increase in amplitude in the pass-to-pass direction. In this paper, the general problem considered is where the along the pass dynamics switch at the end of each pass. In particular, stability tests are developed which extend to allow control law design for this property and can be computed using Linear Matrix Inequality (LMI) methods

Modelling of the oxygen decomposition process of silage

Analizowano wpływ wybranych warunków początkowych na zmiany stężenia tlenu i koncentracji drożdży w odkrytej warstwie kiszonki bezpośrednio po otwarciu silosu. W tym celu wykorzystano prosty model matematyczny tlenowego rozkładu kiszonek, który uwzględnia zmiany przestrzenno-czasowe tlenu i temperatury opisane równaniami dyfuzji.The impact of selected initial conditions on changes in oxygen concentration and yeast concentration in open silage layer immediately after opening the silo was analyzed. A simple mathematical model of oxygen decomposition of silage was used for this purpose, taking into account spatial and temporal changes of oxygen and temperature, described by using diffusion equations