40,169 research outputs found
Concept-based Analysis of Surface and Structural Misfits (CASSM) Tutorial notes
Concept-based Analysis of Surface and Structural Misfits (CASSM) in a novel approach to usability analysis that focuses attention on misfits between user and system concepts. We believe that as an approach it has several desirable qualities: o It focuses on concepts rather than tasks or procedures. Consequently, it complements the majority of existing approaches to usability evaluation. In particular, it analyses conceptual misfits between user and system. o By intentionally supporting âsketchyâ analysis, CASSM avoids the âdeath by detailâ that plagues many evaluation techniques. CASSM analyses do not have to be complete or consistent to be useful â though of course a thorough analysis is likely to have these properties. Also, CASSM analyses are often quite succinct, compared to (for example) a Cognitive Walkthrough (Wharton et al, 1994), Heuristic Evaluation (Nielsen, 1994) or GOMS analysis (John & Kieras, 1996). o As a notation, it provides a âbridgeâ between the core ideas underpinning work on mental models and design issues, and may thus make prior work on mental models more readily accessible to design practice. [This should be regarded as a hypothesis that has not yet been tested.] o The CASSM notation provides a relatively formal definition of many of Greenâs Cognitive Dimensions (see, for example, Green, 1989; Green & Petre, 1996; Blackwell & Green 2003). In this way, it further supports assessment of a system in terms of CDs. This is discussed in detail towards the end of this document. Although the name (CASSM: Concept-based Analysis of Surface and Structural Misfits) emphasises the importance of misfits, you should be aware that there are other kinds of userâsystem misfits that are outside the scope of CASSM; for example, inconsistencies in procedures for similar tasks would be picked up by other techniques but are not directly addressed within CASSM. CASSM focuses on conceptual structures
Experimental and numerical investigation on micro deep drawing process of stainless steel 304 foil using flexible tools
Flexible forming technology provides significant application potential in various areas of manufacturing, particularly at a miniaturized level. Simplicity, versatility of process and feasibility of prototyping makes forming techniques by using flexible tools suitable for micro sheet metal forming. This paper reports the results of FE simulation and experimental research on micro deep drawing processes of stainless steel 304 sheets utilising a flexible die. The study presents a novel technique in which an initial gap (positive or negative) is adopted between an adjustment ring and a blank holder employed in the developed forming system. The blank holder is moveable part and supported by a particular spring that provides the required holding force. The forming parameters (anisotropy of SS 304 material, initial gap, friction conditions at various contact interfaces and initial sheet thickness) related with the forming process are in details investigated. The FE models are built using the commercial code Abaqus/Standard. The numerical predictions reveal the capability of the proposed technique on producing micro metallic cups with high quality and large aspect ratio. To verify these results, number of micro deep drawing experiments is conducted using a special set up developed for this purpose. As providing a fundamental understanding is required for the commercial development of this novel forming technique, hence the optimization of the initial gap in accordance with each sheet thickness, thickness distribution and punch force/stroke relationship are detected
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Stardust microcrater residue compositional groups
Compositional groups are defined in residue from Stardust craters (1-9 Dc) by qualitative EDS. These compositional groups are being further studied by a FIB-SEM technique to determine representative residue compositions
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Kalb-Ramond fields in the Petiau-Duffin-Kemmer formalism and scale invariance
Kalb-Ramond equations for massive and massless particles are considered in
the framework of the Petiau-Duffin-Kemmer formalism. We obtain
matrices of the relativistic wave equation of the first-order and solutions in
the form of density matrix. The canonical and Belinfante energy-momentum
tensors are found. We investigate the scale invariance and obtain the conserved
dilatation current. It was demonstrated that the conformal symmetry is broken
even for massless fields.Comment: 9 pages, no figure
Finite nilpotent semigroups of small coclass
The parameter coclass has been used successfully in the study of nilpotent
algebraic objects of different kinds. In this paper a definition of coclass for
nilpotent semigroups is introduced and semigroups of coclass 0, 1, and 2 are
classified. Presentations for all such semigroups and formulae for their
numbers are obtained. The classification is provided up to isomorphism as well
as up to isomorphism or anti-isomorphism. Commutative and self-dual semigroups
are identified within the classification.Comment: 11 page
Kepler problem in Dirac theory for a particle with position-dependent mass
Exact solution of Dirac equation for a particle whose potential energy and
mass are inversely proportional to the distance from the force centre has been
found. The bound states exist provided the length scale which appears in
the expression for the mass is smaller than the classical electron radius
. Furthermore, bound states also exist for negative values of
even in the absence of the Coulomb interaction. Quasirelativistic expansion of
the energy has been carried out, and a modified expression for the fine
structure of energy levels has been obtained. The problem of kinetic energy
operator in the Schr\"odinger equation is discussed for the case of
position-dependent mass. In particular, we have found that for highly excited
states the mutual ordering of the inverse mass and momentum operator in the
non-relativistic theory is not important.Comment: 9 page
Quantum simulation of an extra dimension
We present a general strategy to simulate a D+1-dimensional quantum system
using a D-dimensional one. We analyze in detail a feasible implementation of
our scheme using optical lattice technology. The simplest non-trivial
realization of a fourth dimension corresponds to the creation of a bivolume
geometry. We also propose single- and many-particle experimental signatures to
detect the effects of the extra dimension.Comment: 5 pages, 3 figures, revtex style;v2 minor changes, references adde
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