180,702 research outputs found
Integrating modes of policy analysis and strategic management practice : requisite elements and dilemmas
There is a need to bring methods to bear on public problems that are inclusive, analytic, and quick. This paper describes the efforts of three pairs of academics working from three different though complementary theoretical foundations and intervention backgrounds (i.e., ways of working) who set out together to meet this challenge. Each of the three pairs had conducted dozens of interventions that had been regarded as successful or very successful by the client groups in dealing with complex policy and strategic problems. One approach focused on leadership issues and stakeholders, another on negotiating competitive strategic intent with attention to stakeholder responses, and the third on analysis of feedback ramifications in developing policies. This paper describes the 10 year longitudinal research project designed to address the above challenge. The important outcomes are reported: the requisite elements of a general integrated approach and the enduring puzzles and tensions that arose from seeking to design a wide-ranging multi-method approach
Macroscopic simulation of the liner honing process
The form quality, the roughness and the surface appearance produced by honing minimizes the friction of the piston in the liner. The process is however mechanically complex and the selection of the process parameters is currently based on empirical methods. The aim of this paper is thus to develop a macroscopic simulation environment of complete real honing cycles, which will help end-users during the setting-up. This virtual tool is based on a space-time discretization and a macroscopic cutting model taking into account local contacts between the workpiece and the abrasive tool. The space-time discretization allows representing the machine environment with the tool, the workpiece and the kinematics. Simulation results are finally validated by comparison with industrial experiments.ThĂšse CIFRe Renault SAS / MSMP PĂŽleProcess ECO
Applications of lean thinking: a briefing document
This report has been put together by the Health and Care Infrastructure Research and Innovation Centre (HaCIRIC) at the University of Salford for the Department of Health.
The need for the report grew out of two main simple questions,
o Is Lean applicable in sectors other than manufacturing?
o Can the service delivery sector learn from the success of lean in manufacturing and realise the benefits of its implementation?The aim of the report is to list together examples of lean thinking as it is evidenced in the
public and private service sector. Following a review of various sources a catalogue of evidence is put together in an organised manner which demonstrates that Lean principles
and techniques, when applied rigorously and throughout an entire organization/unit, they can have a positive impact on productivity, cost, quality, and timely delivery of services
Quantitative Genetics and Functional-Structural Plant Growth Models: Simulation of Quantitative Trait Loci Detection for Model Parameters and Application to Potential Yield Optimization
Background and Aims: Prediction of phenotypic traits from new genotypes under
untested environmental conditions is crucial to build simulations of breeding
strategies to improve target traits. Although the plant response to
environmental stresses is characterized by both architectural and functional
plasticity, recent attempts to integrate biological knowledge into genetics
models have mainly concerned specific physiological processes or crop models
without architecture, and thus may prove limited when studying genotype x
environment interactions. Consequently, this paper presents a simulation study
introducing genetics into a functional-structural growth model, which gives
access to more fundamental traits for quantitative trait loci (QTL) detection
and thus to promising tools for yield optimization. Methods: The GreenLab model
was selected as a reasonable choice to link growth model parameters to QTL.
Virtual genes and virtual chromosomes were defined to build a simple genetic
model that drove the settings of the species-specific parameters of the model.
The QTL Cartographer software was used to study QTL detection of simulated
plant traits. A genetic algorithm was implemented to define the ideotype for
yield maximization based on the model parameters and the associated allelic
combination. Key Results and Conclusions: By keeping the environmental factors
constant and using a virtual population with a large number of individuals
generated by a Mendelian genetic model, results for an ideal case could be
simulated. Virtual QTL detection was compared in the case of phenotypic traits
- such as cob weight - and when traits were model parameters, and was found to
be more accurate in the latter case. The practical interest of this approach is
illustrated by calculating the parameters (and the corresponding genotype)
associated with yield optimization of a GreenLab maize model. The paper
discusses the potentials of GreenLab to represent environment x genotype
interactions, in particular through its main state variable, the ratio of
biomass supply over demand
Can a Lamb Reach a Haven Before Being Eaten by Diffusing Lions?
We study the survival of a single diffusing lamb on the positive half line in
the presence of N diffusing lions that all start at the same position L to the
right of the lamb and a haven at x=0. If the lamb reaches this haven before
meeting any lion, the lamb survives. We investigate the survival probability of
the lamb, S_N(x,L), as a function of N and the respective initial positions of
the lamb and the lions, x and L. We determine S_N(x,L) analytically for the
special cases of N=1 and N--->oo. For large but finite N, we determine the
unusual asymptotic form whose leading behavior is S_N(z)\simN^{-z^2}, with
z=x/L. Simulations of the capture process very slowly converge to this
asymptotic prediction as N reaches 10^{500}.Comment: 13 pages, 6 figures, IOP format; v2: small changes in response to
referee and editor comment
Coherent-state path integral versus coarse-grained effective stochastic equation of motion: From reaction diffusion to stochastic sandpiles
We derive and study two different formalisms used for non-equilibrium
processes: The coherent-state path integral, and an effective, coarse-grained
stochastic equation of motion. We first study the coherent-state path integral
and the corresponding field theory, using the annihilation process
as an example. The field theory contains counter-intuitive quartic vertices. We
show how they can be interpreted in terms of a first-passage problem.
Reformulating the coherent-state path integral as a stochastic equation of
motion, the noise generically becomes imaginary. This renders it not only
difficult to interpret, but leads to convergence problems at finite times. We
then show how alternatively an effective coarse-grained stochastic equation of
motion with real noise can be constructed. The procedure is similar in spirit
to the derivation of the mean-field approximation for the Ising model, and the
ensuing construction of its effective field theory. We finally apply our
findings to stochastic Manna sandpiles. We show that the coherent-state path
integral is inappropriate, or at least inconvenient. As an alternative, we
derive and solve its mean-field approximation, which we then use to construct a
coarse-grained stochastic equation of motion with real noise.Comment: 29 pages, 33 figures. This is a pedagogic introduction to stochastic
processes, their modeling, and effective field theory. Version 2: writing
improved + a new appendi
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