Influence of surface tension in the surfactant-driven fracture of closely-packed particulate monolayers

A phase-field model is used to capture the surfactant-driven formation of fracture patterns in particulate monolayers. The model is intended for the regime of closely-packed systems in which the mechanical response of the monolayer can be approximated as a linearly elastic solid. The model approximates the loss in tensile strength of the monolayer as the surfactant concentration increases through the evolution of a damage field. Initial-boundary value problems are constructed and spatially discretized with finite element approximations to the displacement and surfactant damage fields. A comparison between model-based simulations and existing experimental observations indicates a qualitative match in both the fracture patterns and temporal scaling of the fracture process. The importance of surface tension differences is quantified by means of a dimensionless parameter, revealing thresholds that separate different regimes of fracture. These findings are supported by newly performed experiments that validate the model and demonstrate the strong sensitivity of the fracture pattern to differences in surface tension.Comment: 10 pages, 11 figures, and 3 table

Vademecum-based GFEM (V-GFEM): optimal enrichment for transient problems

This is the accepted version of the following article: [Canales, D., Leygue, A., Chinesta, F., González, D., Cueto, E., Feulvarch, E., Bergheau, J. -M., and Huerta, A. (2016) Vademecum-based GFEM (V-GFEM): optimal enrichment for transient problems. Int. J. Numer. Meth. Engng, 108: 971–989. doi: 10.1002/nme.5240.], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/nme.5240/fullThis paper proposes a generalized finite element method based on the use of parametric solutions as enrichment functions. These parametric solutions are precomputed off-line and stored in memory in the form of a computational vademecum so that they can be used on-line with negligible cost. This renders a more efficient computational method than traditional finite element methods at performing simulations of processes. One key issue of the proposed method is the efficient computation of the parametric enrichments. These are computed and efficiently stored in memory by employing proper generalized decompositions. Although the presented method can be broadly applied, it is particularly well suited in manufacturing processes involving localized physics that depend on many parameters, such as welding. After introducing the vademecum-generalized finite element method formulation, we present some numerical examples related to the simulation of thermal models encountered in welding processes.Peer ReviewedPostprint (author's final draft

Stress intensity factors computation for bending plates with extended finite element method

The modelization of bending plates with through-the-thickness cracks is investigated. We consider the Kirchhoff–Love plate model, which is valid for very thin plates. Reduced Hsieh–Clough–Tocher triangles and reduced Fraejis de Veubeke–Sanders quadrilaterals are used for the numerical discretization. We apply the eXtended Finite Element Method strategy: enrichment of the finite element space with the asymptotic bending singularities and with the discontinuity across the crack. The main point, addressed in this paper, is the numerical computation of stress intensity factors. For this, two strategies, direct estimate and J-integral, are described and tested. Some practical rules, dealing with the choice of some numerical parameters, are underlined

Stable Generalized Finite Element Method (SGFEM)

The Generalized Finite Element Method (GFEM) is a Partition of Unity Method (PUM), where the trial space of standard Finite Element Method (FEM) is augmented with non-polynomial shape functions with compact support. These shape functions, which are also known as the enrichments, mimic the local behavior of the unknown solution of the underlying variational problem. GFEM has been successfully used to solve a variety of problems with complicated features and microstructure. However, the stiffness matrix of GFEM is badly conditioned (much worse compared to the standard FEM) and there could be a severe loss of accuracy in the computed solution of the associated linear system. In this paper, we address this issue and propose a modification of the GFEM, referred to as the Stable GFEM (SGFEM). We show that the conditioning of the stiffness matrix of SGFEM is not worse than that of the standard FEM. Moreover, SGFEM is very robust with respect to the parameters of the enrichments. We show these features of SGFEM on several examples.Comment: 51 pages, 4 figure

Barring Judicial Review

Whether judicial review is available is one of the most hotly contested issues in administrative law. Recently, laws that prohibit judicial review have sparked debate in the Medicare, immigration, and patent contexts. These debates are continuing in challenges to the recently created Medicare price negotiation program. Yet despite debates about the removal of judicial review, little is known about how often, and in what contexts, Congress has expressly precluded review. This Article provides new insights about express preclusion by conducting an empirical study of the U.S. Code. It creates an original dataset of laws that expressly preclude judicial review of agency action, which this Article refers to as “judicial review bars.” The findings reveal that express preclusion is a phenomenon: at least 190 statutory provisions expressly bar judicial review of agency actions. This Article then creates a taxonomy of actions barred from review. Most review bars target internal management decisions, such as decisions about how to allocate resources, set priorities, and manage personnel. Because judicial review has traditionally been considered a core tool for overseeing agencies, this Article next investigates alternative oversight tools for actions barred from judicial review. When judicial review is barred, other structures often exist for political oversight, internal supervision, and public participation. Strikingly, review bar statutes often expressly create structures to facilitate such oversight. Alternative oversight structures include requirements to send reports to Congress, establish internal procedures, consult with stakeholders, and publish decisions. Furthermore, many review bars involve government spending programs, which are subject to appropriations oversight. Like judicial review, alternative oversight tools play an important role in promoting democratic values of deliberation, inclusiveness, and public accountability in the administrative state. A recent example at the Patent Office illustrates how the combination of review bars and alternative oversight tools can balance efficient implementation of programs with the need to protect individual interests and democratic values. Given the significance of alternative oversight tools in monitoring agencies, this Article argues that courts should consider the availability of alternative oversight tools when construing review bars, and policymakers should do the same when designing regulatory programs

Cardiovascular system response to therapeutic water treadmill walking in older adults /

Director: Jennifer L. Caputo.Because older adults have a greater propensity toward musculoskeletal problems, aquatic exercise is a valuable modality for rehabilitation and physical training. However, little research has been completed concerning the effects of therapeutic water walking on the cardiovascular system of older persons. Therefore, the purpose of this study was to examine the cardiovascular responses to slow, medium, and fast water treadmill walking on older adults. Healthy adults (n=20) between 55 and 64 years of age were tested in a therapeutic pool. Comparisons of cardiovascular responses to water treadmill walking in 92 degrees F (33 degreesC) water with land treadmill walking at 70 degrees F (21 degrees C) ambient temperature were completed. Water depth was at the superior aspect of the iliac crest (waist level) and treadmill speeds were at 2.0 mph, 2.5 mph, and 3.0 mph for both water and land treadmills. Following land and water treadmill acclimation, all participants performed five-minute bouts of exercise at each speed. Oxygen consumption (VO2), heart rate (HR), systolic blood pressure (SBP), and rating of perceived exertion (RPE) were measured during each exercise bout. The conclusions of this study indicate that VO 2, HR, and RPE measures statistically increased with each speed increase during both land and water treadmill walking. BP statistically increased with each speed increase during water treadmill walking but not land treadmill walking. Likewise, VO2, HR, SBP, and RPE measures were statistically higher during therapeutic water treadmill walking compared to land treadmill walking at 2.5 mph and 3.0 mph.Ph.D

A Distinction Without a Difference: Convergence in Claim Construction Standards

In 2007, a district court found a patent for a medical device valid. While the district court litigation was pending, however, the Patent and Trademark Office ( PTO ) found the exact same patent invalid. The Court of Appeals for the Federal Circuit then affirmed both decisions. At first glance, the idea that a patent could be found valid in one forum but invalid in another seems absurd. Yet the law condones these results: district courts and the PTO apply different claim construction standards. The Leahy-Smith America Invents Act of 2011 ( AIA ) created new post-grant proceedings at the PTO to challenge patent validity, which increased the stakes of the dual claim construction regime. In particular, the inter partes review ( IPR ) proceeding has become extremely popular. Over 5,200 inter partes review petitions have been filed at the PTO since the proceeding\u27s inception in September 2012. The popularity is due, in part, to the fact that the proceedings have turned out to be surprisingly lethal to granted patents: eighty-four percent of final written decisions have invalidated some or all challenged claims, making the proceeding very attractive to patent challengers. This high invalidation rate sparked debate about the differing claim construction standards. The PTO applies the broadest reasonable interpretation ( BRI ) standard, which liberally construes terms. District courts, in contrast, apply the Phillips standard, which more narrowly looks to the ordinary and customary meaning of a term based on the written patent document. The difference in construction has the potential to affect a patent\u27s validity because when a term is construed broadly, the patent is more likely to cover preexisting ideas or inventions and to therefore be considered unworthy of patent protection. Thus, some commentators believe the BRI standard employed by the PTO is more likely to invalidate a patent than the Phillips standard applied in district courts

Barring Judicial Review

Whether judicial review is available is one of the most hotly contested issues in administrative law. Recently, laws that prohibit judicial review have sparked debate in the Medicare, immigration, and patent contexts. These debates are continuing in challenges to the recently created Medicare price negotiation program. Yet despite debates about the removal of judicial review, little is known about how often, and in what contexts, Congress has expressly precluded review. This Article provides new insights about express preclusion by conducting an empirical study of the U.S. Code. It creates an original dataset of laws that expressly preclude judicial review of agency action, which this Article refers to as “judicial review bars.” The findings reveal that express preclusion is a phenomenon: at least 190 statutory provisions expressly bar judicial review of agency actions. This Article then creates a taxonomy of actions barred from review. Most review bars target internal management decisions, such as decisions about how to allocate resources, set priorities, and manage personnel. Because judicial review has traditionally been considered a core tool for overseeing agencies, this Article next investigates alternative oversight tools for actions barred from judicial review. When judicial review is barred, other structures often exist for political oversight, internal supervision, and public participation. Strikingly, review bar statutes often expressly create structures to facilitate such oversight. Alternative oversight structures include requirements to send reports to Congress, establish internal procedures, consult with stakeholders, and publish decisions. Furthermore, many review bars involve government spending programs, which are subject to appropriations oversight. Like judicial review, alternative oversight tools play an important role in promoting democratic values of deliberation, inclusiveness, and public accountability in the administrative state. A recent example at the Patent Office illustrates how the combination of review bars and alternative oversight tools can balance efficient implementation of programs with the need to protect individual interests and democratic values. Given the significance of alternative oversight tools in monitoring agencies, this Article argues that courts should consider the availability of alternative oversight tools when construing review bars, and policymakers should do the same when designing regulatory programs

Public Patent Powers

Congress has created multiple structures for agencies to control how patents are used, but that institutional design choice has received little academic attention. This Article provides the first comprehensive survey of existing laws that expressly authorize agencies to control patents. I locate 113 express conditions across 68 laws that expressly authorize executive actors to make some form of decision about patents. These powers, which I refer to as “public patent powers,” allow the government to use patented inventions, to obtain patents, to authorize third parties to use patented inventions, and to regulate how patents are used. Agencies have used many of these powers, but they have been reluctant to use others. Notably, agencies have refused to grant compulsory licenses on patents covering federally funded drugs, despite multiple requests to do so. The descriptive account of public patent powers has several implications for patent regulation. Public patent powers show different actions that the executive branch could take without the need for any legislative action when patents create policy concerns, as is currently happening with high drug prices. Themes in public patent powers and their use also reveal consistent policy judgments present throughout the history of patent regulation in the United States. These themes create a framework for identifying contexts where executive control over patents may be appropriate and politically feasible. The descriptive account further suggests that the Supreme Court’s decision in Oil States v. Greene’s Energy may have broader implications than previously recognized. Moving forward, this Article contends that the executive branch should create an interagency framework to guide how agencies use public patent powers and that courts should consider themes in public patent powers when deciding whether to grant injunctions in patent cases