2,804 research outputs found
Part 1: a process view of nature. Multifunctional integration and the role of the construction agent
This is the first of two linked articles which draw s on emerging understanding in the field of biology and seeks to communicate it to those of construction, engineering and design. Its insight is that nature 'works' at the process level, where neither function nor form are distinctions, and materialisation is both the act of negotiating limited resource and encoding matter as 'memory', to sustain and integrate processes through time. It explores how biological agents derive work by creating 'interfaces' between adjacent locations as membranes, through feedback. Through the tension between simultaneous aggregation and disaggregation of matter by agents with opposing objectives, many functions are integrated into an interface as it unfolds. Significantly, biological agents induce flow and counterflow conditions within biological interfaces, by inducing phase transition responses in the matte r or energy passing through them, driving steep gradients from weak potentials (i.e. shorter distances and larger surfaces). As with biological agents, computing, programming and, increasingly digital sensor and effector technologies share the same 'agency' and are thus convergent
Global well-posedness for passively transported nonlinear moisture dynamics with phase changes
We study a moisture model for warm clouds that has been used by Klein and
Majda as a basis for multiscale asymptotic expansions for deep convective
phenomena. These moisture balance equations correspond to a bulk microphysics
closure in the spirit of Kessler and of Grabowski and Smolarkiewicz, in which
water is present in the gaseous state as water vapor and in the liquid phase as
cloud water and rain water. It thereby contains closures for the phase changes
condensation and evaporation, as well as the processes of autoconversion of
cloud water into rainwater and the collection of cloud water by the falling
rain droplets. Phase changes are associated with enormous amounts of latent
heat and therefore provide a strong coupling to the thermodynamic equation.
In this work we assume the velocity field to be given and prove rigorously
the global existence and uniqueness of uniformly bounded solutions of the
moisture model with viscosity, diffusion and heat conduction. To guarantee
local well-posedness we first need to establish local existence results for
linear parabolic equations, subject to the Robin boundary conditions on the
cylindric type of domains under consideration. We then derive a priori
estimates, for proving the maximum principle, using the Stampacchia method, as
well as the iterative method by Alikakos to obtain uniform boundedness. The
evaporation term is of power law type, with an exponent in general less or
equal to one and therefore making the proof of uniqueness more challenging.
However, these difficulties can be circumvented by introducing new unknowns,
which satisfy the required cancellation and monotonicity properties in the
source terms
A history of grape production and winemaking in Canterbury, New Zealand 1840-2002
Grapes were first planted in Canterbury in 1840, but commercial production only began
in 1978. This research paper examines the history of grape and wine production in
Canterbury. It considers the different factors constraining the commercial development
of wine production initially and reviews the key actors and processes influencing
developments since then. The role of Lincoln College, later University, is shown to be
pivotal to the development of grape growing and wine making in Canterbury and the
cooler parts of New Zealand. While Canterbury has only a small part of the overall New
Zealand vineyard area, its contribution, through Lincoln, to research, publication,
education and development of the New Zealand Wine Industry has been considerable.
Canterbury is currently enjoying a period of rapid vineyard development.
This research report provides much of the historical detail underlying the first three
chapters of Canterbury Grapes and Wines 1840-2002 by Danny Schuster, David Jackson
and Rupert Tipples (2002, Shoal Bay Press: Christchurch). It is the working document of
an industry historian and first hand observer of the developments since 1977. As such, it
is not a polished final publication manuscript of the form which appears in the book, but
very much the working document, with all the limitations implied
A Solutions to 'Too Few' Working Down on the Farm - The Human Capability in Agriculture and Horticulture Initiative
This paper des cribes and analyses how a labour and skills shortage in agriculture (used in the generic and inclusive sense) emerged here in New Zealand towards the end of the twentieth century and how it has been responded to by the industry and government. It delineates a collaborative response to a type of problem affecting many sectors of the New Zealand economy at the present time. A serendipitous conjunction of improved industry economics, productive policy provision, and ministerial and industry will facilitated the creation of a new pan primary industry organisation with the somewhat unwieldy title Human Capability in Agriculture and Horticulture. A picture of what happened has been built up using a range of methodologies (historical- both documentary and oral; case studies; participant observation: and action research) to explain what led to its formation and sub sequent progress. Prospects for the future are reviewed with a view to isolating critical features which may be of benefit to other industries experiencing similar labour and skills shortages
Broadband THz study of excitonic resonances in the high-density regime
We report the first terahertz study of the intra-excitonic 1s-2p transition
at high excitation densities in GaAs/AlGaAs quantum wells. A strong shift,
broadening, and ultimately the disappearance of this resonance occurs with
increasing density, after ultrafast photoexcitation at the near-infrared
exciton line. Densities of excitons and unbound electron-hole pairs are
followed quantitatively using a model of the composite terahertz dielectric
response. Comparison with near-infrared absorption changes reveals a
significantly enhanced energy shift and broadening of the intra-excitonic
resonance.Comment: 4 pages, 4 figure
Onset of collective and cohesive motion
We study the onset of collective motion, with and without cohesion, of groups
of noisy self-propelled particles interacting locally. We find that this phase
transition, in two space dimensions, is always discontinuous, including for the
minimal model of Vicsek et al. [Phys. Rev. Lett. {\bf 75},1226 (1995)] for
which a non-trivial critical point was previously advocated. We also show that
cohesion is always lost near onset, as a result of the interplay of density,
velocity, and shape fluctuations.Comment: accepted for publication in Phys. Rev. Let
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