The Study of Optimization of Thrust Vector Control Systems

Reliability analyses and failure probabilities of S-4B stage automatic pilots and hydraulic thrust vector control system configurations, and compatibility with actuato

A simple proposal for parallel computation over time of an evolutionary process with implicit time stepping

Evolutionary processes arise in many areas of applied mathematics, however since the solution at any time depends on the solution at previous time steps, these types of problems are inherently difficult to parallelize. Whilst an explicit time stepping scheme can be easily parallelized, stability considerations for such methods impose significant restriction on the size of the time step, particularly for parabolic problems. In this paper, we make a simple proposal of a parallel approach for the solution of evolutionary problems with implicit time step schemes. We derive and demonstrate our approach for the linear diffusion equation. Using an all-at-once approach, we solve for all time steps simultaneously using a preconditioned iterative method. The application of the preconditioner is parallelizable over time and significant speed up compared to standard sequential solving methods is achieved. In this short paper, we have not compared to any of the more sophisticated parallel in time methods, but rather simply describe our own elementary approach

The Stability of Angiotensin I Formed at Room Temperature in the Presence of Ethylenediaminetetraacetate to Subsequent Incubation at 37 °C

Peer Reviewe

Refined saddle-point preconditioners for discretized Stokes problems

This paper is concerned with the implementation of efficient solution algorithms for elliptic problems with constraints. We establish theory which shows that including a simple scaling within well-established block diagonal preconditioners for Stokes problems can result in significantly faster convergence when applying the preconditioned MINRES method. The codes used in the numerical studies are available online

Implications of domain growth in morphogenesis

Domain growth can play an important role in pattern formation during early embryonic development. By considering the Turing reaction-diffusion model for pattern formation, we show how growth can influence patterning. We consider how growth affects mode selection and robustness of patterns. Specifically, we investigate ligament patterns in arcoid bivalves

Individual Behavior Drives Ecosystem Function and the Impacts of Harvest

Current approaches for biodiversity conservation and management focus on sustaining high levels of diversity among species to maintain ecosystem function. We show that the diversity among individuals within a single population drives function at the ecosystem scale. Specifically, nutrient supply from individual fish differs from the population average \u3e80% of the time, and accounting for this individual variation nearly doubles estimates of nutrients supplied to the ecosystem. We test how management (i.e., selective harvest regimes) can alter ecosystem function and find that strategies targeting more active individuals reduce nutrient supply to the ecosystem up to 69%, a greater effect than body size–selective or nonselective harvest. Findings show that movement behavior at the scale of the individual can have crucial repercussions for the functioning of an entire ecosystem, proving an important challenge to the species-centric definition of biodiversity if the conservation and management of ecosystem function is a primary goal

A preconditioner for the Ohta-Kawasaki equation

We propose a new preconditioner for the Ohta-Kawasaki equation, a nonlocal Cahn-Hilliard equation that describes the evolution of diblock copolymer melts. We devise a computable approximation to the inverse of the Schur complement of the coupled second-order formulation via a matching strategy. The preconditioner achieves mesh independence: as the mesh is refined, the number of Krylov iterations required for its solution remains approximately constant. In addition, the preconditioner is robust with respect to the interfacial thickness parameter if a timestep criterion is satisfied. This enables the highly resolved finite element simulation of three-dimensional diblock copolymer melts with over one billion degrees of freedom

‘Fake news’ is the invention of a liar: How false information circulates within the hybrid news system

Alarmed by the oversimplifications related to the ‘fake news’ buzzword, researchers have started to unpack the concept, defining diverse types and forms of misleading news. Most of the existing works in the area consider crucial the intent of the content creator in order to differentiate among different types of problematic information. This article argues for a change of perspective that, by leveraging the conceptual framework of sociocybernetics, shifts from exclusive attention to creators of misleading information to a broader approach that focuses on propagators and, as a result, on the dynamics of the propagation processes. The analytical implications of this perspective are discussed at a micro level (criteria to judge the falsehood of news and to decide to spread it), at a meso level (four possible relations between individual judgements and decisions), and at a macro level (global circulation cascades). The authors apply this theoretical gaze to analyse ‘fake news’ stories that challenge existing models