109,720 research outputs found
Implementing the Lean Sigma Framework in an Indian SME: a case study
Lean and Six Sigma are two widely acknowledged business process improvement strategies available to organisations today for achieving dramatic results in cost, quality and time by focusing on process performance. Lately, Lean and Six Sigma practitioners are integrating the two strategies into a more powerful and effective hybrid, addressing many of the weaknesses and retaining most of the strengths of each strategy. Lean Sigma combines the variability reduction tools and techniques from Six Sigma with the waste and non-value added elimination tools and techniques from Lean Manufacturing, to generate savings to the bottom-line of an organisation. This paper proposes a Lean Sigma framework to reduce the defect occurring in the final product (automobile accessories) manufactured by a die-casting process. The proposed framework integrates Lean tools (current state map, 5S System, and Total Productive Maintenance (TPM)) within Six Sigma DMAIC methodology to enhance the bottom-line results and win customer loyalty. Implementation of the proposed framework shows dramatic improvement in the key metrics (defect per unit (DPU), process capability index, mean and standard deviation of casting density, yield, and overall equipment effectiveness (OEE)) and a substantial financial savings is generated by the organisation
Towards a model for protein production rates
In the process of translation, ribosomes read the genetic code on an mRNA and
assemble the corresponding polypeptide chain. The ribosomes perform discrete
directed motion which is well modeled by a totally asymmetric simple exclusion
process (TASEP) with open boundaries. Using Monte Carlo simulations and a
simple mean-field theory, we discuss the effect of one or two ``bottlenecks''
(i.e., slow codons) on the production rate of the final protein. Confirming and
extending previous work by Chou and Lakatos, we find that the location and
spacing of the slow codons can affect the production rate quite dramatically.
In particular, we observe a novel ``edge'' effect, i.e., an interaction of a
single slow codon with the system boundary. We focus in detail on ribosome
density profiles and provide a simple explanation for the length scale which
controls the range of these interactions.Comment: 8 pages, 8 figure
Does OO sync with the way we think?
Given that corrective-maintenance costs already dominate the software life cycle and look set to increase significantly, reliability in the form of reducing such costs should be the most important software improvement goal. Yet the results are not promising when we review recent corrective-maintenance data for big systems in general and for OO in particular-possibly because of mismatches between the OO paradigm and how we think
Transport on a Lattice with Dynamical Defects
Many transport processes in nature take place on substrates, often considered
as unidimensional lanes. These unidimensional substrates are typically
non-static: affected by a fluctuating environment, they can undergo
conformational changes. This is particularly true in biological cells, where
the state of the substrate is often coupled to the active motion of
macromolecular complexes, such as motor proteins on microtubules or ribosomes
on mRNAs, causing new interesting phenomena. Inspired by biological processes
such as protein synthesis by ribosomes and motor protein transport, we
introduce the concept of localized dynamical sites coupled to a driven lattice
gas dynamics. We investigate the phenomenology of transport in the presence of
dynamical defects and find a novel regime characterized by an intermittent
current and subject to severe finite-size effects. Our results demonstrate the
impact of the regulatory role of the dynamical defects in transport, not only
in biology but also in more general contexts
Lifetime reduction of surface states at Cu, Ag and Au(111) caused by impurity scattering
We present density-functional results on the lifetime of the (111) surface
state of the noble metals. We consider scattering on the Fermi surface caused
by impurity atoms belonging to the 3d and 4sp series. The results are analyzed
with respect to film thickness and with respect to separation of scattering
into bulk or into surface states. While for impurities in the surface layer the
overall trends are similar to the long-known bulk-state scattering, for
adatom-induced scattering we find a surprising behavior with respect to the
adatom atomic number. A plateau emerges in the scattering rate of the 3d
adatoms, instead of a peak characteristic of the d resonance. Additionally, the
scattering rate of 4sp adatoms changes in a zig-zag pattern, contrary to a
smooth parabolic increase following Linde's rule that is observed in bulk. We
interpret these results in terms of the weaker charge-screening and of
interference effects induced by the lowering of symmetry at the surface
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