938 research outputs found
Boundary Objects and their Use in Agile Systems Engineering
Agile methods are increasingly introduced in automotive companies in the
attempt to become more efficient and flexible in the system development. The
adoption of agile practices influences communication between stakeholders, but
also makes companies rethink the management of artifacts and documentation like
requirements, safety compliance documents, and architecture models.
Practitioners aim to reduce irrelevant documentation, but face a lack of
guidance to determine what artifacts are needed and how they should be managed.
This paper presents artifacts, challenges, guidelines, and practices for the
continuous management of systems engineering artifacts in automotive based on a
theoretical and empirical understanding of the topic. In collaboration with 53
practitioners from six automotive companies, we conducted a design-science
study involving interviews, a questionnaire, focus groups, and practical data
analysis of a systems engineering tool. The guidelines suggest the distinction
between artifacts that are shared among different actors in a company (boundary
objects) and those that are used within a team (locally relevant artifacts). We
propose an analysis approach to identify boundary objects and three practices
to manage systems engineering artifacts in industry
Determination of the glass transition of powder samples using Dynamic Mechanic Analysis on compacts
Dynamic Mechanic Analysis, DMA, is a
sensitive method to determine the glass
transition temperature (Tg) of materials.
Several different sample geometries such as
three point bending, stretched films or
compressed cylinders, are commonly used.
The Tg of a powder is related to its “sticky
point”, i.e. the temperature when the powder
particles interact instead of flowing freely.
The determination of powder Tg is not
straightforward using DMA due to the
limiting geometry. Here it is demonstrated
that the Tg of powder samples can
be effectively and correctly determined
by DMA on compacts in compression mode,
using a standard wedge shaped probe usually
utilized in three point bend analysis. The
analysis of compacts holds the benefits of
analysing powder samples as received from
manufacturers, being relatively robust with
regard to deformation as the material
becomes rubbery, and enabling easy sample
preparation and handling
High Performance Polysodium Acrylate Superabsorbents Utilizing Microfibrillated Cellulose to Augment Gel Properties
Microfibrillated cellulose was utilized at low concentrations as a filler material, added prior to free radical polymerization, in cross-linked superabsorbent polysodium acrylate hydrogels. The effect of microfibrillated cellulose concentration on equilibrium swelling, shear modulus after synthesis, and shear modulus at equilibrium swelling was studied at different degree of cross-linking. For the characterization of the microfibrillated cellulose optical microscopy, atomic force microscopy, and transmittance analysis were used. The shear modulus of the samples was determined using uniaxial compression analysis. The swelling of the gels was determined using classical gravimetrical measurements. It was found that microfibrillated cellulose was highly efficient in increasing the shear modulus of the gels. Furthermore, the microfibrillated cellulose was found to have the same effect on the swelling and shear modulus at equilibrium swelling as the same mass of the conventional covalent cross-linker N,N'-methylenebisacrylamide (MBA), while in fact improving the fracture resistance of the gels. In conclusion, microfibrillated cellulose shows great potential as an additive to enhance the performance of soft materials
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