Integrability,soliton solutions and modulation instability analysis of a (2+1)-dimensional nonlinear Heisenberg ferromagnetic spin chain equation

We consider the Heisenberg ferromagnetic spin chain equation, which is governed by the (2+1)-dimensional nonlinear Schrödinger-type equation. Based on the Ablowitz–Kaup–Newell–Segur frame, we study the integrability of the equation by deriving its Lax pair and infinite conservation laws. By introducing a potential transformation, we obtain its Hirota bilinear form and soliton solutions. Based on the resulting lax pair, we construct Darboux transformation and multi-soliton solutions of the equation. Furthermore, we also find the other type of soliton solutions for the equation by considering its Bäcklund transformation. Finally, we discuss the linear stability analysis by considering its stability condition for the stationary solution of the equation, which can be used to analyze modulation instability. The technique presented in this work is analytical, which can be used to enrich the dynamical of the Heisenberg ferromagnetic spin chain equation.     

User and design requirements and production of evidence: using incident analysis data to (1) inform user scenarios and bow ties,and (2) generate user and design requirements

This paper reports on an innovative human–machine interaction methodology adopted to assess the case, role and requirements for a new ground collision awareness technology. Specifically, this paper reports on the analysis of ground collision incident data and the subsequent advancement of user scenarios and bow-ties based on this data analysis, for the purpose of generating preliminary user and design requirements for this technology. In so doing, the requirements elicitation and validation methods used in this research are framed from an epistemological perspective. Accordingly, the particular methods adopted are presented and discussed in terms of concepts of evidence, bearing witness and the distinction between facts and values. As such, this paper promotes thinking about evidence-based design practices. Overall, this evidence-based approach aims to improve the development of scenarios and associated problem solving around technology cases, user requirements and user interface design features. The proposed method is useful in terms of bridging the gap from data analysis to design, and validating design decisions. In this regard, it is argued that the generation of user scenarios based on the analysis of incident data (i.e. data coding and statistical analysis), and the reframing of such scenarios in terms of bow-ties for the purpose of requirements/design envisionment, extends existing scenario-based design approaches. Although the use of bow-ties is not new, the advancement of bow-ties from data-driven scenarios is. Specifically, the bow-tie method was applied in a design context, to support problem solving around design decisions, as opposed to formal risk analysis.