Narrow Results

In this work we are study the Fuzzy Initial Value Problem (FIVP) with parameters and/or initial conditions given by fuzzy sets. Starting from the flow equation of the deterministic Initial Value Problem (IVP) associates to FIVP, we obtain the FIVP flow, through the principle of Zadeh. Follow, we introduce the concept of fuzzy equilibrium stability of FIVP and some examples are given.

Online communities (OCs) have become an important source for identifying the needs and problems of users, supporting companies in innovation. This development was fostered by IT/Internet technologies and has also been strengthened through recent social changes in user behavior within "Web 2.0." In contrast to its growing relevance, user innovation activities within OCs are still underexplored. Companies that wish to successfully utilize and integrate innovative OC members into their NPD process need a better understanding of the drivers and changes of user motivation in such communities. In this paper we analyze, categorize and integrate different motivational factors that play a major role here and develop several propositions concerning motivation within innovation communities.

This paper examines the relationship between the perceived team climate for innovations and the experience of flow and worry and the moderating effect of team size. The research contains a multi-organization dataset with 323 software product development team members. The results show that the perceived climate for innovation is significantly positively related to the experience of flow and worry. However, the findings did not support the moderation with no differences in working in smaller or larger teams. This study indicates that the perceived climate for innovations positively relates to positive and negative individual effects without the importance of team size.

Friction stir welding (FSW) experiments were conducted, using a work hardened aluminium alloy and a cast aluminium alloy followed by examination focusing on the upper weld zone. The examination has revealed the feature of the major forward flow due to the forward motion of the shoulder. A thin shear layer was identified between the tool shoulder and the workpiece with a distinctive shear flow direction. The thickness of the shear layer was alloy dependent. An embedded layer in the upper weld zone has also been identified. The flow phenomena leading to this will be discussed. A velocity profile in the shear layer, based on the apparent alignment of Si particles in the cast alloy after FSW, has suggested a dominant sliding contact condition.

In this work, we show that the bailout embedding method is responsible for creating different dynamical behaviors and for destroying intrinsic features present in mixed phase spaces of the area-preserving Hamiltonian maps, where the sticking to regular (or resonant) islands degrades chaotic properties. In particular, the base map chosen for the study is the two-dimensional (2D) Web Map (WM). The four-dimensional (4D) embedded Web Map dynamics is governed by four-parameters: ($K,q$) in the WM control the nonlinearity and the type of symmetry structures (crystalline or quasi-crystalline) in phase space, respectively; ($\alpha ,\gamma$) in the embedding equations determine the mass density ratio and dissipation, respectively. For specific parameter combinations we explore the existence of transient chaos phenomenon, hyperchaotic dynamics and control the degradation of the underlying diffusive behaviors observed in phase space of the WM. If the WM is subjected to large enough dissipation through the embedding equations, stable periodic points (inside resonance islands) become sinks attracting almost all the surrounding orbits, destroying all invariant curves which divide the phase space into chaotic and regular domains. As area-preserving maps obtained from Hamiltonian flows usually share the crucial property that resonance islands can be found immersed in chaotic sea (characterizing the mixed phase space) for appropriated parameter combinations, the results obtained here for the 4D embedded WM should be considered generic for such whole class of nonlinear systems.

Let k be a positive integer and G be a graph. If d(u) + d(v) ≥ 4k - 3 for any uv ∈ E(G), then G admits a star decomposition in which all stars have size at least k. In particular, every graph G with δ(G) ≥ 2k - 1 admits such a decomposition. The bounds are best possible, in the sense that there exist infinitely many graphs G with δ(G) ≥ 2k - 2 and without such a decomposition.