Modelling the backwash process in micro filtration

Microfiltration separates fine solids from a liquid substrate, but requires a process to remove the accumulated solids from the filtering device. In this study, a backwash process was examined, in which a flow of high-pressure air in the direction opposite to the usual fluid flow, is used to dislodge and remove the particles. The dynamics of the original air penetration of the filtering fibres, the flux balances of the displaced liquid, and the distribution of pressures through a network of modules were all studied. They fall naturally into a classification by increasing spatial scales

Volcanic studies by members of the Royal Society of London 1665 - 1780

Late seventeenth century ideas about volcanic activity were largely derived from classical sources. The Philosophical Transactions of the Royal Society of London provided a vehicle for publication of information about volcanoes where many ancient notions were refuted and new hypotheses suggested. Volcanic studies by members included detailed field reports, eyewitness accounts of eruptions as well as expeditions to extinct or dormant volcanic peaks, experiments with volcanic rocks, and speculation on the nature of subterranean "fires" and causes of eruptions. The development of theories concerning the formation of the columnar basalts of the Giant's Causeway is also traced. By the 1770's there appeared a general acceptance among members of the Royal Society of the igneous origin of basalt, the existence of ancient extinct volcanoes and the implications of past geologic change

American Progressives and the European Left

Until comparatively recently, historians treated progressivism of the early twentieth century variety as if it were a purely American affair. In 1952, Eric F. Goldman argued that progressivism was ‘as exclusively national a movement as the United States ever knew’. But in the years that followed, a number of works appeared which challenged the validity of this narrowly national interpretation. Arthur Mann, in 1956, suggested that American reformers were much influenced by British social thought. Gertrude Almy Slichter drew attention to the European background of American reform in a 1960 dissertation. A number of essays then showed that progressivism itself could be regarded as part of an international movement. Peter F. Clarke pointed out that there had been a progressive movement in England which, in fact, predated the American equivalent. Kenneth O. Morgan, reviewing the nature of the links between British and American reformers, thought it meaningful to write in terms of ‘ Anglo-American Progressivism’. Other historians, looking at the matter in a more general, European context, were struck by the apparent similarities between American progressives, British Liberals or Labourites, and French and German socialists. George E. Mowry argued that American progressives should be regarded as part of western ‘social democracy’. Arthur A. Ekirch came to much the same conclusion

Wave-Slope Soaring of the Brown Pelican

We theoretically assess the energy savings associated with wave-slope soaring of the brown pelican over near-shoaling ocean surface waves. The steady, constant altitude flight of a pelican is analyzed as a control. The airflow induced by a passing wave, or the “wave-induced wind,” is theoretically analyzed for shallow water solitary waves. These waves are assumed to be well described by the KdV equation. We use potential flow theory to describe the wave- induced wind. Using a regular expansion of the Stokes stream function and the Green’s function for Laplace in 2D with Dirichlet boundary conditions, we obtain integral expressions for the horizontal and vertical components of the wave-induced wind in a frame of reference moving with the wave. The theory results in expressions wherein provided with the amplitude and period of an incoming swell, horizontal and vertical components of the wave-induced wind in a frame of reference moving with the wave are produced. Wave-slope soaring flight is analyzed over near-shoaling solitary waves on size scales corresponding to wind swell, with amplitude of 1m and period of 10s. We find an upper bound benefit of 57.6% decrease in required mechanical power output as compared with flight out of ground effect and 52.4% benefit as compared with standard ground effect flight. The theory in this work define sufficient evidence that wave- slope soaring could become a viable strategy for energy efficient flight of unmanned autonomous vehicles (UAVs)

Teaching Manuscripts in the Digital Age

This chapter reflects on the author’s practical experience teaching palaeography in several different contexts at the start of the so-called “digital age”. Material for manuscript-studies is becoming available at an enormous rate: perhaps most obvious are the results of the large-scale digitisation programmes which are making high-quality colour facsimiles of manuscripts available online to wide audiences. At the same time, Virtual Learning Environments provide new possibilities for teaching and learning, and many tools for research on manuscripts can also be used for teaching. Perhaps more fundamentally, however, it has often been noted that scholarship is changing as a result of digital tools, resources, and methods. What, then, of teaching? Should the teaching of manuscript studies also change along with the scholarly discipline, bringing the Digital Humanities into our classes on palaeography and codicology? To begin answering this question, and to suggest some pedagogical possibilities brought about by technology, the author’s own experiences are discussed. Some limitations of technology for teaching are then considered, and some general remarks are then provided on the relationship between palaeography and Digital Humanities, two fields which are both fighting for recognition as full academic disciplines and not “mere” Hilfswissenschaften

The six days and the deluge: some ideas on earth history in the Royal Society of London 1660-1775

The influence of the biblical story of Creation and the Deluge on ideas of earth history during the period 1660-1775 is examined with particular reference to papers on the subject published in the Philosophical Transactions of the Royal Society of London. Topics examined in more detail include the controversies over the origin of marine fossils and bones of prehistoric animals, ideas on natural causes of the Deluge and its role in shaping landforms, and the age of the earth. Despite the inhibiting effect of the Genesis account, there was considerable flexibility in interpretation of both the Creation and Deluge stories in terms of current scientific knowledge. The later papers display a good deal of uniformitarian thinking within the framework of a catastrophic deluge hypothesis

On perceptual expertise

Expertise is a cognitive achievement that clearly involves experience and learning, and often requires explicit, time-consuming training specific to the relevant domain. It is also intuitive that this kind of achievement is, in a rich sense, genuinely perceptual. Many experts—be they radiologists, bird watchers, or fingerprint examiners—are better perceivers in the domain(s) of their expertise. The goal of this paper is to motivate three related claims, by substantial appeal to recent empirical research on perceptual expertise: Perceptual expertise is genuinely perceptual and genuinely cognitive, and this phenomenon reveals how we can become epistemically better perceivers. These claims are defended against sceptical opponents that deny significant top-down or cognitive effects on perception, and opponents who maintain that any such effects on perception are epistemically pernicious

Computer-Aided Palaeography, Present and Future

The field of digital palaeography has received increasing attention in recent years, partly because palaeographers often seem subjective in their views and do not or cannot articulate their reasoning, thereby creating a field of authorities whose opinions are closed to debate. One response to this is to make palaeographical arguments more quantitative, although this approach is by no means accepted by the wider humanities community, with some arguing that handwriting is inherently unquantifiable. This paper therefore asks how palaeographical method might be made more objective and therefore more widely accepted by non-palaeographers while still answering critics within the field. Previous suggestions for objective methods before computing are considered first, and some of their shortcomings are discussed. Similar discussion in forensic document analysis is then introduced and is found relevant to palaeography, though with some reservations. New techniques of "digital" palaeography are then introduced; these have proven successful in forensic analysis and are becoming increasingly accepted there, but they have not yet found acceptance in the humanities communities. The reasons why are discussed, and some suggestions are made for how the software might be designed differently to achieve greater acceptance. Finally, a prototype framework is introduced which is designed to provide a common basis for experiments in "digital" palaeography, ideally enabling scholars to exchange quantitative data about scribal hands, exchange processes for generating this data, articulate both the results themselves and the processes used to produce them, and therefore to ground their arguments more firmly and perhaps find greater acceptance

On the gauge of the natural lineshape

We use a general formulation of nonrelativistic quantum electrodynamics in which the gauge freedom is carried by the arbitrary transverse component of the the Green's function for the divergence operator to calculate the natural lineshape of spontaneous emission, thus discerning the full dependence of the result on the choice of gauge. We also use a representation of the Hamiltonian in which the virtual field associated with the atomic ground state is explicitly absent. We consider two processes by which the atom is excited; the first is resonant absorption of incident radiation with a sharp line. This treatment is then adapted to derive a resonance fluorescence rate associated with the Lamb line in atomic hydrogen. Second we consider the atom's excitation due to irradiation with a laser pulse treated semi-classically. An experiment could be used to reveal which of the calculated lineshape distributions is closest to the measured one. This would provide an answer to a question of fundamental importance; how does one best describe atom-radiation interactions with the canonical formalism?Comment: 17 pages, 2 figures, 3 table

Irreducibility of configurations

In a paper from 1886, Martinetti enumerated small $v_3$-configurations. One of his tools was a construction that permits to produce a $(v+1)_3$-configuration from a $v_3$-configuration. He called configurations that were not constructible in this way irreducible configurations. According to his definition, the irreducible configurations are Pappus' configuration and four infinite families of configurations. In 2005, Boben defined a simpler and more general definition of irreducibility, for which only two $v_3$-configurations, the Fano plane and Pappus' configuration, remained irreducible. The present article gives a generalization of Boben's reduction for both balanced and unbalanced $(v_r,b_k)$-configurations, and proves several general results on augmentability and reducibility. Motivation for this work is found, for example, in the counting and enumeration of configurations