Discrete Mechanics and Optimal Control Applied to the Compass Gait Biped

This paper presents a methodology for generating locally optimal control policies for simple hybrid mechanical systems, and illustrates the method on the compass gait biped. Principles from discrete mechanics are utilized to generate optimal control policies as solutions of constrained nonlinear optimization problems. In the context of bipedal walking, this procedure provides a comparative measure of the suboptimality of existing control policies. Furthermore, our methodology can be used as a control design tool; to demonstrate this, we minimize the specific cost of transport of periodic orbits for the compass gait biped, both in the fully actuated and underactuated case

Variational Methods for Control and Design of Bipedal Robot Models

This thesis investigates nonsmooth mechanics using variational methods for the modeling, control, and design of bipedal robots. The theory of Lagrangian mechanics is extended to capture a variety of nonsmooth collision behaviors in rigid body systems. Notably, a variational impact model is presented for the transition of constraints behavior that describes a biped switching stance feet at the conclusion of a step. Next, discretizations of the impact mechanics are developed using the framework of variational discrete mechanics. The resulting variational collision integrators are consistent with the continuous time theory and have an underlying symplectic structure. In addition to their role as integrators, the discrete equations of motion capturing nonsmooth dynamics enable a direct method for trajectory optimization. Upon specifically defining the optimal control problem for nonsmooth systems, examples demonstrate this optimization method in the task of determining periodic gaits for two rigid body biped models. An additional effort is made to optimize bipedal walking motions through modifications in system design. A method for determining optimal designs using a combination of trajectory optimization methods and surrogate function optimization methods is defined. This method is demonstrated in the task of determining knee joint placement in a given biped model.</p

Media-Rich Input Application Liability

Until recently, media-rich online interactions were mostly unidirectional: multimedia content was delivered by the service provider to the user. Input from the user came almost exclusively in the form of text. Even when searching the Internet for images or audio, a user typically entered text into a search engine. In addition, search engines indexed multimedia content by analyzing not the content itself but the text surrounding it. This is rapidly changing. With the rise of multimedia-capable smartphones and wireless broadband, applications that allow users to search using non-textual inputs are quickly becoming popular. These applications go much further than simply allowing content to be uploaded and shared, which is already common to Web 2.0 applications; they actually respond to the user based on the input media.[...] These applications represent a new and growing category that I term media-rich input applications (MRIAs).[...] There are three unique attributes of MRIAs that differentiate them from legacy web behavior and therefore require new analysis. First, unlike legacy search applications in which the service provider makes a copy and presents it to the user, MRIA behavior requires the user to make a copy and present it to the service provider. Thus, the image of the book cover in the previous example is digitized by the user and sent to Google; it is not copied by Google and sent to the user in response to a search. Second, the copied content is not necessarily from the Internet; in our example it is from a physical book. Third, some of these technologies create derivative works in a way that simple web searching and indexing does not. This Essay examines how these unique features of MRIAs interact with current copyright doctrine and how the lack of protection for users may discourage innovation by developers of this new and exciting technology. This Essay also proposes a new user safe harbor that balances the interests of users in using MRIAs with the interests of copyright owners in protecting their exclusive rights

Geometry of unsteady fluid transport during fluid–structure interactions

We describe the application of tools from dynamical systems to define and quantify the unsteady fluid transport that occurs during fluid–structure interactions and in unsteady recirculating flows. The properties of Lagrangian coherent structures (LCS) are used to enable analysis of flows with arbitrary time-dependence, thereby extending previous analytical results for steady and time-periodic flows. The LCS kinematics are used to formulate a unique, physically motivated definition for fluid exchange surfaces and transport lobes in the flow. The methods are applied to numerical simulations of two-dimensional flow past a circular cylinder at a Reynolds number of 200; and to measurements of a freely swimming organism, the Aurelia aurita jellyfish. The former flow provides a canonical system in which to compare the present geometrical analysis with classical, Eulerian (e.g. vortex shedding) perspectives of fluid–structure interactions. The latter flow is used to deduce the physical coupling that exists between mass and momentum transport during self-propulsion. In both cases, the present methods reveal a well-defined, unsteady recirculation zone that is not apparent in the corresponding velocity or vorticity fields. Transport rates between the ambient flow and the recirculation zone are computed for both flows. Comparison of fluid transport geometry for the cylinder crossflow and the self-propelled swimmer within the context of existing theory for two-dimensional lobe dynamics enables qualitative localization of flow three-dimensionality based on the planar measurements. Benefits and limitations of the implemented methods are discussed, and some potential applications for flow control, unsteady propulsion, and biological fluid dynamics are proposed

Federal Circuit Patent Precedent: An Empirical Study of Institutional Authority and IP Ideology

In this paper, we aim to better understand the institutional authority of the Federal Circuit as a source of law as well as the influence of pro-patent and anti-patent ideological forces at play between the Supreme Court, Federal Circuit, and the district courts. Our specific focus is on the district courts and how they cite Federal Circuit precedent relative to Supreme Court precedent to support their decisions, whether they be pro-patent or anti-patent. Using a variety of citation approaches and statistical tests, we find that federal district courts treat the Federal Circuit as more authoritative (compared to the Supreme Court) on patent law, than they treat the regional circuits (compared to the Supreme Court) on copyright law. Second, the Federal Circuit\u27s precedent tends to be relied on more in pro-patent opinions than in anti-patent opinions. In addition, both of these effects are stronger in how the district courts use the precedent—i.e., how many times precedent is cited—than in what higher court precedent is used

Variational Collision Integrators and Optimal Control

This paper presents a methodology for generating locally optimal control policies for mechanical systems that undergo collisions at point contacts. Principles of nonsmooth mechanics for rigid bodies are used in both continuous and discrete time, and provide impact models for a variety of collision behaviors. The discrete Euler-Lagrange (DEL) equations that follow from the discrete time analyses yield variational integration schemes for the dierent impact models. These DEL equations play a pivotal role in the method of Discrete Mechanics and Optimal Control (DMOC), which generates locally optimal control policies as the solution to equality constrained nonlinear optimization problems. The DMOC method is demonstrated on a 4-link planar walking robot model, generating locally optimal periodic walking gaits

Case report for an internet- and mobile-based intervention for internet use disorder

Background and aimsInternet use disorder (IUD), characterized as the inability to control one’s internet use, is associated with reduced quality of life and mental health comorbidities such as depression, substance abuse, or anxiety. Evidence-based treatment options are scarce due to the novelty of the diagnosis. Internet- and mobile-based interventions (IMI) may be an effective means to deliver psychological treatment to individuals with IUD as they address affected individuals in their online setting. This study presents a newly developed IMI for IUD disclosing treatment satisfaction and preliminary effects by exemplifying with a case report.MethodsThe case of a female participant with IUD, characterized by an excessive use of social media, is analyzed. The case report follows the CARE guidelines and presents qualitative and quantitative outcomes regarding potential symptom reduction measured by the Internet Addiction Test (IAT) and Compulsive Internet Use Scale (CIUS), treatment satisfaction measured by the Client Satisfaction Questionnaire (CSQ) and feasibility by analyzing participant’s written feedback during treatment.ResultsThe case report shows that internet- and mobile-based interventions may be feasible in supporting an individual in reducing symptoms of IUD as well as depressive symptoms, anxiety and procrastination behavior. Treatment satisfaction was reported as good.Discussion and conclusionsThis case report illustrates that IMIs can have the potential to be an easily accessible and possibly effective treatment option for IUD. Case studies on IMIs may provide insights into important mechanisms for symptom change. Further studies are needed to expand our understanding of this diverse disorder to provide adequate treatment

Adenoviral-vectored epigraph vaccine elicits robust, durable, and protective immunity against H3 influenza A virus in swine

Current methods of vaccination against swine Influenza A Virus (IAV-S) in pigs are infrequently updated, induce strain-specific responses, and have a limited duration of protection. Here, we characterize the onset and duration of adaptive immune responses after vaccination with an adenoviral-vectored Epigraph vaccine. In this longitudinal study we observed robust and durable antibody responses that remained above protective titers six months after vaccination. We further identified stable levels of antigen-specific T cell responses that remained detectable in the absence of antigen stimulation. Antibody isotyping revealed robust class switching from IgM to IgG induced by Epigraph vaccination, while the commercial comparator vaccine failed to induce strong antibody class switching. Swine were challenged six months after initial vaccination, and Epigraph-vaccinated animals demonstrated significant protection from microscopic lesion development in the trachea and lungs, reduced duration of viral shedding, lower presence of infectious virus and viral antigens in the lungs, and significant recall of antigen-specific T cell responses following challenge. The results obtained from this study are useful in determining the kinetics of adaptive immune responses after vaccination with adjuvanted whole inactivated virus vaccines compared to adenoviral vectored vaccines and contribute to the continued efforts of creating a universal IAVS vaccine