Extraordinary surface voltage effect in the invisibility cloak with an active device inside

The electromagnetic field solution for a spherical invisibility cloak with an active device inside is established. Extraordinary electric and magnetic surface voltages are induced at the inner boundary of a spherical cloak, which prevent electromagnetic waves from going out. The phase and handness of polarized waves obliquely incident on such boundaries is kept in the reflected waves. The surface voltages due to an electric dipole inside the concealed region are found equal to the auxiliary scalar potentials at the inner boundary, which consequently gain physical counterparts in this case

Triangular Bézier sub-surfaces on a triangular Bézier surface

This paper considers the problem of computing the Bézier representation for a triangular sub-patch on a triangular Bézier surface. The triangular sub-patch is defined as a composition of the triangular surface and a domain surface that is also a triangular Bézier patch. Based on de Casteljau recursions and shifting operators, previous methods express the control points of the triangular sub-patch as linear combinations of the construction points that are constructed from the control points of the triangular Bézier surface. The construction points contain too many redundancies. This paper derives a simple explicit formula that computes the composite triangular sub-patch in terms of the blossoming points that correspond to distinct construction points and then an efficient algorithm is presented to calculate the control points of the sub-patch

Virtual Organizational Learnign in Open Source Software Development Projects

We studied the existence of virtual organizational learning in open source software (OSS) development projects. Specifically, our research focused on learning effects of OSS projects and factors that affect the learning process. The number and percentage of resolved bugs and bug resolution time of 118 SourceForge.net OSS projects were used to measure the learning effects> Projects were characterized by project type, number and experience of developers, number of bugs, and bug resolution time. Our results provide evidence of virtual organizational learning in OSS development projects.Virtual organizational leraning: Organizational learning curve: Virtual organization: Open source software development: Project performance

Generation of the global workspace roadmap of the 3-RPR using rotary disk search

Path planning for parallel manipulators in the configuration space can be a challenging task due to the existence of multiple direct kinematic solutions. Hence the aim of this paper is to define a generalised hierarchical path planning scheme for trajectory generation between two configurations in the configuration space for manipulators that exhibit more than one solution in their direct kinematics. This process is applied to the 3-RPR mechanism, constrained to a 2-DOF system by setting active joint parameter ρ1 to a constant. The overall reachable workspace is discretised and deconstructed into smaller patches, which are then stitched together creating a global workspace roadmap. Using the roadmap, path feasibility is obtained and local path planning is used to generate a complete trajectory. This method can determine a singularity-free path between any two connectible points in the configuration space, including assembly mode changes. © 2014 Elsevier Ltd

Path planning and assembly mode-changes of 6-DOF Stewart-Gough-type parallel manipulators

© 2016 International Federation for the Promotion of Mechanism and Machine Science The Stewart-Gough platform (SGP) is a six degree-of-freedom (DOF) parallel manipulator whose reachable workspace is complex due to its closed-loop configuration and six DOF outputs. As such, methods of path planning that involve storing the entire reachable workspace in memory at high resolutions are not feasible due to this six-dimensional workspace. In addition, complete path planning algorithms struggle in higher dimensional applications without significant customisations. As a result, many workspace analysis algorithms and path planning schemes use iterative techniques, particularly when tracking the manipulator's many direct kinematic solutions. The aim of this paper is to present the viability of singularity-free path planning in the Stewart-Gough platform's 6-dimensional workspace on modern-day computing systems by demonstrating its assembly mode-changing capability. The entire workspace volume is found using flood-fill algorithms with smooth and singularity-free trajectories generated within this known workspace. Workspace volume analysis was also performed with results comparable to other works

Digital and Non-Digital Distractions for IT Professionals’ Remote Work

The pandemic has forced many firms to adopt remote work practices. However, recent surveys show that remote work productivity is mixed. Primary negative factors against productivity are digital and non-digital distractions at home. Considering that IT professionals heavily rely on digital devices, how is their remote work productivity affected by digital and non-digital distractions? The survey data from 60 IT professionals shows that IT professionals’ productivity is not significantly affected by digital distractions compared to those in their office work. On the other hand, non-digital distractions at home lower their productivity. However, their work/life goal commitment counters distractions at home. Implications and future research agendas are discussed

Entangling two superconducting LC coherent modes via a superconducting flux qubit

Based on a pure solid-state device consisting of two superconducting LC circuits coupled to a superconducting flux qubit, we propose in this paper that the maximally entangled coherent states of the two LC modes can be generated for arbitrary coherent states through flux qubit controls.Comment: 5 pages, 2 figure

Full-range and long-term behaviour of prestressed concrete bridges with corrugated steel webs

Prestressed concrete bridges with corrugated steel webs have emerged as a promising bridge form due to their remarkable advantages such as efficient prestressing of concrete, high buckling strength of steel webs and lightness. The full-range and long-term behaviour of these bridges was studied both numerically and experimentally. A sandwich beam theory was developed to investigate both the static and dynamic behaviour numerically. In the development of numerical models, special emphasis was placed on the modelling of corrugated steel webs, external prestressing tendons, diaphragms, and the interaction between web shear deformation and local flange bending. The numerical models were verified by tests. By using the numerical models proposed, the static service behaviour, dynamic properties and long-term behaviour were studied. The sectional ductility, deformability and strength were evaluated by nonlinear analysis taking into account the actual stress-strain curves and path-dependence of materials. The failure mechanisms were studied experimentally and numerically for more accurate evaluation of safety-related attributes such as ultimate load, ductility and deformability. The formation of plastic hinge and its size were also studied thoroughly in view of their importance in the prediction of full-range behaviour. The long-term behaviour was also studied numerically and experimentally. Some design recommendations are provided here.published_or_final_versio