249,907 research outputs found
Achieving excellence in construction
The UK construction industry at its best is excellent. Nonetheless there is a
deep concern that the industry as a whole is underachieving. Problems such as low and
unreliable profitability, a lack of research and development, a shortage of skills, usage of
tender price evaluations, and a fragmented industry structure, are widely recognised by the
industry. These problems must be tackled in order to modernise (Egan, 1998). Developed
using Egan’s principles ‘Constructing excellence’ has been formed to help the industry deliver
world -class products and services. In general management practice the principles of business
excellence models are used to realise the similar objective of ‘delivering world-class products
and services. This enables the application of business excellence models in construction.
EFQM excellence model & MBNQA are two well known internationally recognised
excellence models. This paper compares Egan’s principles with those of widely used business
excellence models to identify areas that may point the way forward in achieving excellence in
constructio
Envelope Expansion with Core Collapse. III. Similarity Isothermal Shocks in a Magnetofluid
We explore MHD solutions for envelope expansions with core collapse (EECC)
with isothermal MHD shocks in a quasi-spherical symmetry and outline potential
astrophysical applications of such magnetized shock flows. MHD shock solutions
are classified into three classes according to the downstream characteristics
near the core. Class I solutions are those characterized by free-fall collapses
towards the core downstream of an MHD shock, while Class II solutions are those
characterized by Larson-Penston (LP) type near the core downstream of an MHD
shock. Class III solutions are novel, sharing both features of Class I and II
solutions with the presence of a sufficiently strong magnetic field as a
prerequisite. Various MHD processes may occur within the regime of these
isothermal MHD shock similarity solutions, such as sub-magnetosonic
oscillations, free-fall core collapses, radial contractions and expansions. We
can also construct families of twin MHD shock solutions as well as an
`isothermal MHD shock' separating two magnetofluid regions of two different yet
constant temperatures. The versatile behaviours of such MHD shock solutions may
be utilized to model a wide range of astrophysical problems, including star
formation in magnetized molecular clouds, MHD link between the asymptotic giant
branch phase to the proto-planetary nebula phase with a hot central magnetized
white dwarf, relativistic MHD pulsar winds in supernova remnants, radio
afterglows of soft gamma-ray repeaters and so forth.Comment: 21 pages, 33 figures, accepted by MNRA
Lyapunov Functions in Piecewise Linear Systems: From Fixed Point to Limit Cycle
This paper provides a first example of constructing Lyapunov functions in a
class of piecewise linear systems with limit cycles. The method of construction
helps analyze and control complex oscillating systems through novel geometric
means. Special attention is stressed upon a problem not formerly solved: to
impose consistent boundary conditions on the Lyapunov function in each linear
region. By successfully solving the problem, the authors construct continuous
Lyapunov functions in the whole state space. It is further demonstrated that
the Lyapunov functions constructed explain for the different bifurcations
leading to the emergence of limit cycle oscillation
The Current Status of Binary Black Hole Simulations in Numerical Relativity
Since the breakthroughs in 2005 which have led to long term stable solutions
of the binary black hole problem in numerical relativity, much progress has
been made. I present here a short summary of the state of the field, including
the capabilities of numerical relativity codes, recent physical results
obtained from simulations, and improvements to the methods used to evolve and
analyse binary black hole spacetimes.Comment: 14 pages; minor changes and corrections in response to referee
Boolean network model predicts cell cycle sequence of fission yeast
A Boolean network model of the cell-cycle regulatory network of fission yeast
(Schizosaccharomyces Pombe) is constructed solely on the basis of the known
biochemical interaction topology. Simulating the model in the computer,
faithfully reproduces the known sequence of regulatory activity patterns along
the cell cycle of the living cell. Contrary to existing differential equation
models, no parameters enter the model except the structure of the regulatory
circuitry. The dynamical properties of the model indicate that the biological
dynamical sequence is robustly implemented in the regulatory network, with the
biological stationary state G1 corresponding to the dominant attractor in state
space, and with the biological regulatory sequence being a strongly attractive
trajectory. Comparing the fission yeast cell-cycle model to a similar model of
the corresponding network in S. cerevisiae, a remarkable difference in
circuitry, as well as dynamics is observed. While the latter operates in a
strongly damped mode, driven by external excitation, the S. pombe network
represents an auto-excited system with external damping.Comment: 10 pages, 3 figure
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