Rensselaer Polytechnic Institute

About: Rensselaer Polytechnic Institute is a education organization based out in Troy, New York, United States. It is known for research contribution in the topics: Terahertz radiation & Population. The organization has 19024 authors who have published 39922 publications receiving 1414699 citations. The organization is also known as: RPI & Rensselaer Institute.

The integration of lean management and Six Sigma

Abstract: Purpose – To eliminate many misconceptions regarding Six Sigma and lean management by describing each system and the key concepts and techniques that underlie their implementation. This discussion is followed by a description of what lean organizations can gain from Six Sigma and what Six Sigma organizations can gain from lean management.Design/methodology/approach – Comparative study of Six Sigma and lean management using available literature, critical analysis, and knowledge and professional experience of the authors.Findings – The joint implementation of the programs will result in a lean, Six Sigma (LSS) organization, overcoming the limitations of each program when implemented in isolation. A thorough analysis of the two programs provides some likely reasons why the programs alone may fail to achieve absolute perfection.Practical implications – A lean, Six Sigma (LSS) organization would capitalize on the strengths of both lean management and Six Sigma. An LSS organization would include three primary t...

Distant side-walls cause slow amplitude modulation of cellular convection

Abstract: The effect of vertical boundaries on convection in a shallow layer of fluid heated from below is considered. By means of a multiple-scale perturbation analysis, results for horizontally unbounded layers are modified so that they ‘fit in’ to a rectangular region. The critical Rayleigh number and critical wave-number are determined. Motion is predicted to have the form of finite ‘rolls’ whose axes are parallel to the shorter sides of the dish. Aspects of the non-linear development and stability of this motion are studied. The general question of convective pattern selection in a bounded layer is discussed in the light of available theoretical and experimental results. This paper deals with an aspect of the theory of convection in a bounded horizontal layer of fluid heated from below. Almost all previous theoretical investigations of this problem have assumed that the layer is unbounded. (When we speak of an unbounded or a bounded layer we shall be referring to whether or not the layer extends to infinity in horizontal directions.) A premise of such investigations has been that the inevitable presence of side-walls has little or no effect in a sufficiently shallow layer. What follows is a first attempt to demonstrate that the concept of slow amplitude modulation can be employed to show how shallow the layer need be if the side-walls are to have ‘essentially ’ no effect and to estimate what their effect is if that effect is not too large. Readers unfamiliar with developments in convection theory for unbounded layers might find it useful to consult one or more of the surveys by Brindley (1967), Gortler & Velte (1967), or Segel (1966). Directly relevant is the recent paper by Davis (1967), who considered rectangular dishes with length to depth ratios which varied from to 6. His linear stability analysis, using the Galerkin method, showed that convection should commence in the form of finite rolls parallel to the shorter side-wall of the dish. If co-ordinates are chosen so that the side-walls are parallel to the 5- and y-axes then the two possible types of finite rolls are calledfinite y rolls andfinite x rolls. The latter is a motion which is periodic (or nearly so) in the 2-direction and has a zero velocity component in the y-direction (v 3 0). Finite y rolls have a corresponding definition. As Davis did, we emphasize the three-dimensional nature of finite rolls, which have no velocity component in the axial direction but depend on all three spatial co-ordinates.