Techno-economic comparison of renewable energy systems using multi-pole system analysis (MPSA)

The recently published method of multi-pole system analysis (MPSA) is used to techno-economically compare two wind-energy converters: offshore wind turbines and the energy ship concept. According to the method, both systems are (i) modeled, (ii) energetically and economically analyzed, (iii) technoeconomically optimized and, finally, (iv) expected uncertainties are calculated and assessed. The results of the method are used to derive the necessary cost reduction of the wind-energy converters to be economically competitive to fossil-fuel-based technologies.The authors would like to thank the Deutsche Forschungsgemeinschaft (DFG) for the financial support in the framework of the Excellence Initiative, Darmstadt Graduate School of Excellence Energy Science and Engineering (GSC 1070)

Results for Channel Error Profiles for DECT

This letter presents the main statistical characterization of the underlying error process obtained in the case of the Digital European Cordless Telecommunications (DECT) radio system. By simulation of the transmission link, error sequences are generated for different channel parameters. Relevant statistics are then computed for the purpose of efficient channel coding design and evaluation

On pressure and temperature waves within a cavitation bubble

The presented work is about the detailed pressure, temperature and velocity distribution within a plane, cylindrical and spherical cavitation bubble. The review of Plesset & Prosperetti (1977) and more recently the review of Feng & Leal (1997) describe the time behavior of the gas within a spherical bubble due to forced harmonic oscillations of the bubble wall. We reconsider and extend those previous works by developing from the conversation laws and the ideal gas law a boundary value problem for the distribution of temperature and velocity amplitude within the bubble. This is done for a plane, cylindrical, or spherical bubble. The consequences due to shape differences are discussed. The results show that an oscillating temperature boundary layer is formed in which the heat conduction takes places. With increasing dimensionless frequency, i.e. Péclet number, the boundary-layer thickness decreases and compression modulus approaches its adiabatic value. This adiabatic behaviour is reached at lower frequencies for the plane geometry in comparison with cylindrical and spherical geometry. This is due to the difference in the volume specific surface, which is 1, 2, 3 times the inverse bubble height/radius for the plane, cylindrical and spherical bubble respectively. For the plane bubble the analysis ends up in an eigenvalue problem with four eigenvalues and modes. The analytical result is not distinguishable from the numerical result for the plane case gained by a finite element solution. Interestingly if the diffusion time for the temperature distribution is of the order of the traveling time of a pressure wave no adiabatic behavior is observed. A parameter map for the different regimes is given. Since only the behavior of the gas within the bubble is considered the analysis is independent of the surface tension coefficient and the inertia of the surrounding liquid. For the plane bubble since there is no curvature there is no pressure change over the free surface. Despite of this a plane bubble is manly academic, since due to inertia the pressure within the fluid would have to be infinity if the liquid volume around the bubble is unbounded.http://deepblue.lib.umich.edu/bitstream/2027.42/84253/1/CAV2009-final57.pd

Magneto-Optical Spectrum Analyzer

We present a method for the investigation of gigahertz magnetization dynamics of single magnetic nano elements. By combining a frequency domain approach with a micro focus Kerr effect detection, a high sensitivity to magnetization dynamics with submicron spatial resolution is achieved. It allows spectra of single nanostructures to be recorded. Results on the uniform precession in soft magnetic platelets are presented.Comment: 5 pages, 7 figure

Scalable multicomponent spectral analysis for high-throughput data annotation

Orchestrating parametric fitting of multicomponent spectra at scale is an essential yet underappreciated task in high-throughput quantification of materials and chemical composition. We present a systematic approach compatible with high-performance computing infrastructures using the MapReduce model and task-based parallelization. Our approach is realized in a software, pesfit, to enable efficient generation of high-quality data annotation and online spectral analysis as demonstrated using experimental materials characterization datasets

Direct Measurement of Quantum Confinement Effects at Metal to Quantum-Well Nanocontacts

Model metal-semiconductor nanostructure Schottky nanocontacts were made on cleaved heterostructures containing GaAs quantum wells (QWs) of varying width and were locally probed by ballistic electron emission microscopy. The local Schottky barrier was found to increase by ∼0.140 eV as the QW width was systematically decreased from 15 to 1 nm, due mostly to a large (∼0.200 eV) quantum-confinement increase to the QW conduction band. The measured barrier increase over the full 1 to 15 nm QW range was quantitatively explained when local "interface pinning" and image force lowering effects are also considered

Valence band structure and band offset of 3C- and 4H-SiC studied by ballistic hole emission microscopy

p-type Schottky barriers in Pt/3C-SiC contacts have been measured using ballistic hole emission microscopy (BHEM) and estimated to be ???0.06 eV higher than identically prepared Pt/p-type 4H-SiC contacts. This indicates the 3C-SiC valence band maximum (VBM) is ???0.06 eV below the 4H-SiC VBM, consistent with the calculated ???0.05 eV type-II valence band offset between these polytypes. We also observe no evidence of an additional VBM in 3C-SiC, which supports the proposal that the second VBM observed in BHEM spectra on 4H-SiC is a crystal-field split VBM located ???110 meV below the highest VBM.open6

Nanometer-resolution measurement and modeling of lateral variations of the effective work function at the bilayer Pt/Al/SiO2 interface

A ballistic electron emission microscopy (BEEM) comparison of the dependence on gate voltage of the average energy barrier of a metal bilayer Pt/Al/ SiO2 /Si sample and a Pt/ SiO2 /Si sample suggests that the metal/oxide interface of the Pt/Al/ SiO2 /Si sample is laterally inhomogeneous at nm length scales. However, BEEM images of the bilayer sample do not show significantly larger lateral variations than observed on a (uniform) Pt/ SiO2 /Si sample, indicating that any inhomogeneous "patches" of lower-energy barrier height have size smaller than the lateral resolution of BEEM, estimated for these samples to be ???10nm. Finite element electrostatic simulations of an assumed inhomogeneous interface with nm size patches of different effective work function can fit the experimental data of the bilayer sample much better than an assumed homogenous interface, indicating that the bilayer film is laterally inhomogeneous at the nm scale.open2

The analytic structure of 2D Euler flow at short times

Using a very high precision spectral calculation applied to the incompressible and inviscid flow with initial condition $\psi_0(x_1, x_2) = \cos x_1+\cos 2x_2$, we find that the width $\delta(t)$ of its analyticity strip follows a $\ln(1/t)$ law at short times over eight decades. The asymptotic equation governing the structure of spatial complex-space singularities at short times (Frisch, Matsumoto and Bec 2003, J.Stat.Phys. 113, 761--781) is solved by a high-precision expansion method. Strong numerical evidence is obtained that singularities have infinite vorticity and lie on a complex manifold which is constructed explicitly as an envelope of analyticity disks.Comment: 19 pages, 14 figures, published versio