Birds-Eye-View of R.F. Learned and Son Saw Mill, Natchez, Miss.

https://egrove.olemiss.edu/ms_pcards/1141/thumbnail.jp

Orthogonal, solenoidal, three-dimensional vector fields for no-slip boundary conditions

Viscous fluid dynamical calculations require no-slip boundary conditions. Numerical calculations of turbulence, as well as theoretical turbulence closure techniques, often depend upon a spectral decomposition of the flow fields. However, such calculations have been limited to two-dimensional situations. Here we present a method that yields orthogonal decompositions of incompressible, three-dimensional flow fields and apply it to periodic cylindrical and spherical no-slip boundaries.Comment: 16 pages, 2 three-part figure

Local estimates for entropy densities in coupled map lattices

We present a method to derive an upper bound for the entropy density of coupled map lattices with local interactions from local observations. To do this, we use an embedding technique being a combination of time delay and spatial embedding. This embedding allows us to identify the local character of the equations of motion. Based on this method we present an approximate estimate of the entropy density by the correlation integral.Comment: 4 pages, 5 figures include

The laboratory telerobotic manipulator program

New opportunities for the application of telerobotic systems to enhance human intelligence and dexterity in the hazardous environment of space are presented by the NASA Space Station Program. Because of the need for significant increases in extravehicular activity and the potential increase in hazards associated with space programs, emphasis is being heightened on telerobotic systems research and development. The Laboratory Telerobotic Manipulator (LTM) program is performed to develop and demonstrate ground-based telerobotic manipulator system hardware for research and demonstrations aimed at future NASA applications. The LTM incorporates traction drives, modularity, redundant kinematics, and state-of-the-art hierarchical control techniques to form a basis for merging the diverse technological domains of robust, high-dexterity teleoperations and autonomous robotic operation into common hardware to further NASA's research

Drama and the representation of affect: structures of feeling and signs of learning

The way in which school students represent affective aspects of human relationships in drama and what this reveals about learning in drama is the focus of this paper. Such an enquiry traverses the borders between affect, intellect and physicality. Affect and its representation in drama have been themes in the history of drama and theatre and is a current concern in the field of applied theatre and drama. Writers on drama in schools have hitherto been mostly concerned with affect in terms of feelings experienced and emotions represented by students participating in drama. There has, however, been little theorisation of what students’ representation of affective human relations might reveal about the complexity of learning processes involved. Cultural theories of representation and learning are related to an example, drawn from field notes, of school student drama in which students present a stylised representation of a relationship. Because affect is intimately connected with both the bodilyness and modes of representation in drama, multimodal social semiotic analysis will be used as one component of a framework to draw attention to the body as a principal material and tool for making meaning in drama. Theoretically, explanations of learning will be taken from the work of Vygotsky, who maintained a lifelong interest in both drama and learning and the relationship between the two. Concepts taken from the cultural theories of Raymond Williams are also referred to – specifically to the ways in which cultural activity and artefacts represent ‘structures of feeling’

Reactive Control Improvisation

Reactive synthesis is a paradigm for automatically building correct-by-construction systems that interact with an unknown or adversarial environment. We study how to do reactive synthesis when part of the specification of the system is that its behavior should be random. Randomness can be useful, for example, in a network protocol fuzz tester whose output should be varied, or a planner for a surveillance robot whose route should be unpredictable. However, existing reactive synthesis techniques do not provide a way to ensure random behavior while maintaining functional correctness. Towards this end, we generalize the recently-proposed framework of control improvisation (CI) to add reactivity. The resulting framework of reactive control improvisation provides a natural way to integrate a randomness requirement with the usual functional specifications of reactive synthesis over a finite window. We theoretically characterize when such problems are realizable, and give a general method for solving them. For specifications given by reachability or safety games or by deterministic finite automata, our method yields a polynomial-time synthesis algorithm. For various other types of specifications including temporal logic formulas, we obtain a polynomial-space algorithm and prove matching PSPACE-hardness results. We show that all of these randomized variants of reactive synthesis are no harder in a complexity-theoretic sense than their non-randomized counterparts.Comment: 25 pages. Full version of a CAV 2018 pape

The Role of the Environment in Chaotic Quantum Dynamics

We study how the interaction with an external incoherent environment induces a crossover from quantum to classical behavior for a particle whose classical motion is chaotic. Posing the problem in the semiclassical regime, we find that noise produced by the bath coupling rather than dissipation is primarily responsible for the dephasing that results in the ``classicalization'' of the particle. We find that the bath directly alters the phase space structures that signal the onset of classical chaos. This dephasing is shown to have a semiclassical interpretation: the noise renders the interfering paths indistinguishable and therefore incoherent. The noise is also shown to contribute to the quantum inhibition of mixing by creating new paths that interfere coherently.Comment: 10 pages RevTex. Three figures in Postscript as a uuencoded compressed tar file have been submitted as wel

Measurement of the Eta Production in Proton Proton Collisions with the COSY Time of Flight Spectrometer

The reaction pp -> pp eta was measured at excess energies of 15 and 41 MeV at an external target of the Juelich Cooler Synchrotron COSY with the Time of Flight Spectrometer. About 25000 events were measured for the excess energy of 15 MeV and about 8000 for 41 MeV. Both protons of the process pp eta were detected with an acceptance of nearly 100% and the eta was reconstructed by the missing mass technique. For both excess energies the angular distributions are found to be nearly isotropic. In the invariant mass distributions strong deviations from the pure phase space distributions are seen.Comment: 15 pages, 14 figures, 4 table

Evolution of Ultracold, Neutral Plasmas

We present the first large-scale simulations of an ultracold, neutral plasma, produced by photoionization of laser-cooled xenon atoms, from creation to initial expansion, using classical molecular dynamics methods with open boundary conditions. We reproduce many of the experimental findings such as the trapping efficiency of electrons with increased ion number, a minimum electron temperature achieved on approach to the photoionization threshold, and recombination into Rydberg states of anomalously-low principal quantum number. In addition, many of these effects establish themselves very early in the plasma evolution ($\sim$ ns) before present experimental observations begin.Comment: 4 pages, 3 figures, submitted to PR

"Poof! a'm heppily saving the Lord...": multimodality and evaluative discourses in male toilet graffiti at the University of the Western Cape

This paper explores the use of punctuation, capitalisation, linguistic forms and images in the construction of evaluative discourses in male toilet graffiti at the University of the Western Cape. Of particular interest is how male students use these devises in the discursive construction of the appraisal resource of Attitude, Graduation and Evaluation. Using over 150 tokens of graffiti, the paper uses a multimodal approach employing notions of resemiotisation and remediation to show how taboo language, font size, images and sketches are repurposed to aid the evaluation of the 'self' and the 'other' in toilet graffiti. The paper shows that through utilising multimodal texts, graffiti writers are able to reformulate and situate novel meanings in contexts; and in terms of appraisal, the verbal and non-verbal semiotic material are strategically combined to engender novel evaluations