Betriebliches Energiemanagement – Analysen, Methoden und Bewertungsmodelle zur Effizienzsteigerung

In recent years, the EU has been trying to increase political awareness of the energy problem. In 2007 and 2009, the first European energy strategy was adopted, the energy management standard EN 16001, which has been replaced by ISO 50001, was introduced in 2011. The introduction of an energy management standard in a company can contribute significantly to an increase of efficiency – already fixed in the Energy Efficiency Directive of the EU. The development of the Energy Pentagon – a model based on the decision-oriented business administration – allows individual industries to implement a customized holistic energy management. The model takes into account the three levels of management, namely the normative, strategic, and operational planning, and the five management functions, namely organization, personnel management, information, and control as well as the dynamic element of the development. The importance of enterprise energy management system is increasingly due to higher energy costs and a strong environmental awareness. In the future the focus should be increasingly on the implementation in SMEs and on a cost-effective analysis and evaluation of the efficiency gains particularly through the advancements in operational energy controlling.     

Coupling of head and body movement with motion of the audible environment.

The authors asked whether standing posture could be controlled relative to audible oscillation of the environment. Blindfolded sighted adults were exposed to acoustic flow in a moving room, and were asked to move so as to maintain a constant distance between their head and the room. Acoustic flow had direct (source) and indirect (reflected) components. Participants exhibited strong coupling of postural motion with room motion, even when direct information about room motion was masked and was available only in reflected sound. Patterns of hip–ankle coordination closely resembled patterns observed in previous research involving coupling of sway with a visible moving room. The results demonstrate that blindfolded adults can control the dynamics of stance relative to motion of the audible environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Metamodels in Europe: Languages, Tools, and Applications

Editor's note:This article provides an overview of current efforts in Europe for using metamodeling in the integrated development of critical systems such as automotive electronics. It distinguishes between lightweight versus heavyweight approaches, surveys a number of related current European projects, and gives details about the Speeds project to illustrate the role of metamodeling-driven system engineering.—Sandeep Shukla, Virginia Tech     

Characterization of the Martensitic Transformation in NiPtAl Alloy Using Digital Holographic Imaging

Surface reliefs due to phase transformations in a 56.8Ni-5.6Pt-37.6Al at. pct alloy were characterized in situ using digital holographic imaging during thermal cycling from room temperature up to 405 K (132 °C). The 3D images of the surface revealed that the austenite plates formed during heating are exactly the same for each cycle, which is not the case for the martensite plates formed during cooling. The martensite start temperature was found to vary by up to ~ 20 K from one grain to another within the same specimen. The absence of Ni₃Al γ′ precipitates, due to the relatively high Al content, results in the propagation of the martensitic transformation over grains up to a millimeter in size. Bright-field optical imaging showed the formation of large martensite plates in some grains, with cracks perpendicular to these plates, upon cycling. Cracks were also observed at grain boundaries and could be related to the height variations across the grain boundaries.     

Serrated plastic flow behavior and microstructure in a Zr-based bulk metallic glass processed by surface mechanical attrition treatment

The serrated plastic flow, microstructure and residual stress of a Zr55 Cu30 Ni5 Al10 bulk metallic glass (BMG) undergone surface mechanical attrition treatment (SMAT) have been investigated by a combina-tion of compression tests with scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and the incremental hole-drilling strain-gage method.It is found that SMAT leads to various microstructural modifications and residual stress distribution in the surface layers of the Zr-based BMG due to the mechanically-induced nanocrystallization and generation of shear bands.As a re-sult, the BMG alloy exhibits a remarkable work-hardening like behavior and significant increase of plastic strain from less than 1% to 15%, and its plastic deformation dynamics yields a power-law distribution of shear avalanches.Based upon the analysis of the experimental results, it is indicated that this can be con-nected to the SMAT-induced microstructural modifications and the resulting residual compressive stress in the Zr-based BMG.     

Multitrack Digital Data Storage: A Reduced Complexity Architecture

We describe a low-complexity noniterative detector for magnetic and optical multitrack high-density data storage. The detector is based on the M-algorithm architecture. It performs limited breadth-first detection on the equivalent one-dimensional (1-D) channel obtained by column-by-column helical unwinding of the two-dimensional (2-D) channel. The detection performance is optimized by the use of a specific 2-D minimum-phase factorization of the channel impulse response by the equalizer. An optimized path selection scheme maintains the complexity close to practical 1-D Viterbi. This scheme is based on an approximate path metric parallel sort network, taking advantage of the metrics' residual ordering from previous M-algorithm iterations. Such an architecture approaches maximum-likelihood performance on a high areal density uncoded channel for a practical number of retained paths M and bit error rate (BER) below 10^-4. The performance of the system is evaluated when the channel is encoded with multi-parity check (MPC) block inner code and an outer interleaved Reed-Solomon code. The inner code enhances the minimum error distance of the equalized channel and reduces the correct path losses of the M-algorithm path buffer. The decoding is performed noniteratively. Here, we compare the performance of the system to the soft iterative joint decoding of the read channels for data pages encoded with low-density parity check (LDPC) codes with comparable rates and block length. We provide an approximation of the 2-D channel capacity to further assess the performance of the system     

Probing a Device's Active Atoms

Materials science and device studies have, when implemented jointly as “operando” studies, better revealed the causal link between the properties of the device's materials and its operation, with applications ranging from gas sensing to information and energy technologies. Here, as a further step that maximizes this causal link, the paper focuses on the electronic properties of those atoms that drive a device's operation by using it to read out the materials property. It is demonstrated how this method can reveal insight into the operation of a macroscale, industrial‐grade microelectronic device on the atomic level. A magnetic tunnel junction's (MTJ's) current, which involves charge transport across different atomic species and interfaces, is measured while these atoms absorb soft X‐rays with synchrotron‐grade brilliance. X‐ray absorption is found to affect magnetotransport when the photon energy and linear polarization are tuned to excite Fe? O bonds parallel to the MTJ's interfaces. This explicit link between the device's spintronic performance and these Fe? O bonds, although predicted, challenges conventional wisdom on their detrimental spintronic impact. The technique opens interdisciplinary possibilities to directly probe the role of different atomic species on device operation, and shall considerably simplify the materials science iterations within device research.     

3D Ordering at the Liquid–Solid Polar Interface of Nanowires

The nature of the liquid–solid interface determines the characteristics of a variety of physical phenomena, including catalysis, electrochemistry, lubrication, and crystal growth. Most of the established models for crystal growth are based on macroscopic thermodynamics, neglecting the atomistic nature of the liquid–solid interface. Here, experimental observations and molecular dynamics simulations are employed to identify the 3D nature of an atomic-scale ordering of liquid Ga in contact with solid GaAs in a nanowire growth configuration. An interplay between the liquid ordering and the formation of a new bilayer is revealed, which, contrary to the established theories, suggests that the preference for a certain polarity and polytypism is influenced by the atomic structure of the interface. The conclusions of this work open new avenues for the understanding of crystal growth, as well as other processes and systems involving a liquid–solid interface.     

High-frequency homogenization for checkerboard structures: defect modes, ultrarefraction, and all-angle negative refraction

The counterintuitive properties of photonic crystals, such as all-angle negative refraction (AANR) [J. Mod. Opt.34, 1589 (1987)] and high-directivity via ultrarefraction [Phys. Rev. Lett.89, 213902 (2002)], as well as localized defect modes, are known to be associated with anomalous dispersion near the edge of stop bands. We explore the implications of an asymptotic approach to uncover the underlying structure behind these phenomena. Conventional homogenization is widely assumed to be ineffective for modeling photonic crystals as it is limited to low frequencies when the wavelength is long relative to the microstructural length scales. Here a recently developed high-frequency homogenization (HFH) theory [Proc. R. Soc. Lond. A466, 2341 (2010)] is used to generate effective partial differential equations on a macroscale, which have the microscale embedded within them through averaged quantities, for checkerboard media. For physical applications, ultrarefraction is well described by an equivalent homogeneous medium with an effective refractive index given by the HFH procedure, the decay behavior of localized defect modes is characterized completely, and frequencies at which AANR occurs are all determined analytically. We illustrate our findings numerically with a finite-size checkerboard using finite elements, and we emphasize that conventional effective medium theory cannot handle such high frequencies. Finally, we look at light confinement effects in finite-size checkerboards behaving as open resonators when the condition for AANR is met [J. Phys. Condens. Matter 15, 6345 (2003)].