Normal Mode Mixing and Ferromagnetic Resonance Linewidth

The normal modes of an inhomogeneous thin film are obtained by diagonalization of the perturbed Hamiltonian. The resulting modes are mixtures of the spin-wave modes and the uniform mode. We find that the ferromagnetic resonance intensity spectrum of the diagonalized system has a Lorentzian profile, and that the results correspond to the two-magnon model for weak perturbations. For stronger perturbations, the density of states is smoothed, and the spectrum becomes asymmetric due to the low-frequency cutoff of the spin-wave manifold. The technique is expected to be valid for perturbation amplitudes that are large enough to invalidate the assumptions of the two-magnon model

Calculation of Damping Rates in Thin Inhomogeneous Ferromagnetic Films Due to Coupling to Lattice Vibrations

This article describes calculations of ferromagnetic resonance damping rates due to coupling between the magnetization and lattice vibrations through inhomogeneities. The mechanisms we have explored include generation of shear phonons through inhomogeneous anisotropy and generation of both longitudinal and shear phonons through inhomogeneous magnetostriction. In both cases, inhomogeneities couple the uniform precession to finite wave vector phonons. For both coupling mechanisms, the predicted damping rate is on the order of 106 s-21 in transition metals. The damping rate by these mechanisms is inversely proportional to the fifth power of the shear phonon velocity, and may play a significant role in mechanically softer materials such as magnet/polymer nanocomposites

The Adoption and Adaption of Open Innovation: Empirical Evidence from the Biotechnology Industry

The biotechnology sector is one of the most research and development intensive sectors in the healthcare industry. This thesis provides insights into the innovation management approaches and underlying processes to develop radical innovative technologies, products and services. Radical innovation usually does not come from Germany. Despite the history of high quality products, grounded in German engineering and the power of the so called Mittelstand (SMEs), the typical German innovation is essentially incremental, rather than radical. Therefore, this thesis aims to shed light on this myth, by studying the different stages of the founding process of a biotechnology spin-off, led by a serial entrepreneur. The in-depth, longitudinal case study provides a profound, fine grained inside view into the development of radical innovation in the German ecosystem. To broaden the view and be able to draw conclusions for the biotech sector, multiple cases from five successful, mature, biotech SMEs, based in Germany(4) and the Netherlands(1), are included in the study. The theoretical framework proposed, is based on two complementary perspectives by firstly integrating the five key characteristic activities of the open innovation concept: R&D, Intellectual Property, Collaboration, Networking, and Entrepreneur- and Leadership, and secondly, the conceptual framework of open innovation, which covers the management of knowledge. The comprehensive data collection includes 11 interviews, observation and participant observation, as well as a rich, in-depth longitudinal data collection of 210 events that illustrates the different stages of founding the spin-off company. Extensive content analysis, coding and constant comparison, adapting grounded theory methods led to empirical themes for both case study types. This empirical study embraces two different types of organizations to shed light on the innovation processes from multi-level perspectives. These perspectives covering the organizational, intra-organization and the inter-organizational level, strengthened by the project and individual perspective. Therefore, the findings from this thesis filling a gap in the recent literature about open innovation. The outcome of this research emphasizes, that radical innovation, like the Human-on-a-Chip technology are based on the vision of an experienced, serial Entrepreneur, who managed to find and motivate the Right People for this ambitious project. The open attitude and willingness to share knowledge at every stage of the newly founded biotech spin-off, is one of the pre-requisites for their success story. The biotech spin-off TissUse GmbH has created a Beyond open innovation business model. The findings about the mature biotech SMEs suggesting, that at a later stage of business development, Partnerships are at the core of their innovation strategies. Even if three of the five participating CEOs and C-level managers did not know the term open innovation, they are brilliant examples for the adoption and adaption of the open innovation concept. Nevertheless, their demand for external knowledge is driven by their own in-house technology expertise. Findings also suggest, that in context with Partnerships, especially the collaboration with big pharmaceutical companies is shadowed by the different size and culture of these organizations. In summary, this thesis makes contributions to the body of knowledge in a multi-perspective way. Academics can profit from the in-depth, comprehensive findings about biotechnology organizations, practitioners and young potential founders can learn from TissUse' success story and the SMEs innovation journeys. Open innovation moved from a business phenomenon to a real business world concept

Flexible arms provide constant force for pressure switch calibration

In-place calibration of a pressure switch is provided by a system of radially oriented flexing arms which, when rotated at a known velocity, convert the centrifugal force of the arms to a linear force along the shaft. The linear force, when applied to a pressure switch diaphragm, can then be calculated

Reproducing the observed Cosmic microwave background anisotropies with causal scaling seeds

During the last years it has become clear that global O(N) defects and U(1) cosmic strings do not lead to the pronounced first acoustic peak in the power spectrum of anisotropies of the cosmic microwave background which has recently been observed to high accuracy. Inflationary models cannot easily accommodate the low second peak indicated by the data. Here we construct causal scaling seed models which reproduce the first and second peak. Future, more precise CMB anisotropy and polarization experiments will however be able to distinguish them from the ordinary adiabatic models.Comment: 6 pages 2 figures, revtex; minor corrections and references adde

Thermal/acoustical aircraft insulation material

Attempts made to improve the acoustical properties of low density Fiberfrax foam, an aircraft insulation material, are reported. Characterizations were also made of the physical and thermal properties. Two methods, optimization of fiber blend composition and modification of the foam fabrication process, were examined as possible means of improving foam acoustics. Flame impingement tests were also made; results show performance was satisfactory

Low-Complexity Energy-Efficient Broadcasting in One-Dimensional Wireless Networks

In this paper, we investigate the transmission range assignment for N wireless nodes located on a line (a linear wireless network) for broadcasting data from one specific node to all the nodes in the network with minimum energy. Our goal is to find a solution that has low complexity and yet performs close to optimal. We propose an algorithm for finding the optimal assignment (which results in the minimum energy consumption) with complexity O(N^2). An approximation algorithm with complexity O(N) is also proposed. It is shown that, for networks with uniformly distributed nodes, the linear-time approximate solution obtained by this algorithm on average performs practically identical to the optimal assignment. Both the optimal and the suboptimal algorithms require the full knowledge of the network topology and are thus centralized. We also propose a distributed algorithm of negligible complexity, i.e., with complexity O(1), which only requires the knowledge of the adjacent neighbors at each wireless node. Our simulations demonstrate that the distributed solution on average performs almost as good as the optimal one for networks with uniformly distributed nodes.Comment: 17 page

Eigen Modes and Ferromagnetic Resonance Line Width of Inhomogeneous Thin Films

In this paper, we describe modeling of the effects of magnetic inhomogeneity on ferromagnetic resonance line width using eigen mode analyses of inhomogeneous thin magnetic films

Localized Ferromagnetic Resonance in Inhomogeneous Thin Films

The effect of sample inhomogeneity on the ferromagnetic resonance linewidth is determined by diagonalization of a spin wave Hamiltonian for ferromagnetic thin films with inhomogeneities spanning a wide range of characteristic length scales. A model inhomogeneity is used that consist of size D grains and an anisotropy field Hp that varies randomly from grain to grain in a film with thickness d and magnetization Ms. The resulting linewidth agrees well with the two-magnon model for small inhomogeneity, HpD « πMsd. For large inhomogeneity, HpD » πMsd the precession becomes localized and the spectrum approaches that of local precession on independent grains