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61.
Schwaiger Josef Hammerl Timo Florian Johannsen Leist Susanne 《Information Systems and E-Business Management》2021,19(4):1275-1320
Information Systems and e-Business Management - The digital transformation, with its ongoing trend towards electronic business, confronts companies with increasingly growing amounts of data which... 相似文献
62.
Pin Yang Carolina A. Gomez Samantha Andrews Josef D. Sorenson Ken S. Chen 《Journal of the American Ceramic Society》2021,104(7):3247-3259
The electric discharge across a varistor granule filled air gap under a fast-rising voltage pulse was investigated for surge protection applications. The effects of temperature and pressure on the arc and the electrical conduction were analyzed by the characteristic changes in voltage waveforms triggered by a fast-rising high voltage pulse. In addition to the gap size, experimental results show that competing mechanisms among arc conduction, conduction through the varistor granule network, thermionic emission from Joule heating at granule-to-granule contact points, and the magnitude of the switching voltage dictate the maximum surge protection voltage for the filled air gap. Experimental evidence indicated that accumulated degradation was created at small contact points between varistor granules by repetitive assaults from longer duration, high voltage pulses. The uniqueness of using varistor over other dielectric granules in an air gap for surge protection is identified and discussed. 相似文献
63.
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65.
L. Wieth K. Kelemen S. Braun R. Koch H.-J. Bauer H. P. Schuchmann 《Microfluidics and nanofluidics》2016,20(2):42
High-pressure homogenization is a widely used process in the food, pharmaceutical, and cosmetic industry for producing emulsions. Because of small dimensions and high velocities, the experimental and numerical investigation of such a process is challenging. Hence, the development of products is mostly based on trial and error. In this paper, simulations of a generic high-pressure homogenization process using the Lagrangian, mesh-free smoothed particle hydrodynamics (SPH) method are presented and compared to experimental findings using Micro-Particle Image Velocimetry (μ-PIV). The SPH code has been developed and validated with the scope of simulating technical relevant multi-phase problems (Höfler et al. 2012). The present simulations cover the investigation of two different dynamic viscosities of the dispersed phase as well as different droplet trajectories. The comparison between the simulations and the experiments focusses on the velocity distribution of the continuous phase and the droplet deformation and breakup. In both cases a qualitatively good agreement is observed, demonstrating the ability of our SPH implementation for simulating technical relevant two-phase flows. 相似文献
66.
67.
Christian Bauer 《Computer Networks》2013,57(5):1078-1100
The Network Mobility (NEMO) protocol is needed to support the world-wide mobility of aircraft mobile networks across different access networks in the future IPv6 based aeronautical telecommunications network (ATN). NEMO suffers from the constraint that all traffic has to be routed via the home agent though. The already existing correspondent router (CR) protocol solves this triangular routing problem and permits to route packets on a direct path between the mobile network and the ground based correspondent nodes. We identify security deficiencies of this protocol that make it unsuitable for use within the ATN. We therefore propose a new route optimization procedure based on the CR protocol that provides a higher level of security. We evaluate our new protocol in three ways. We first conduct a simulation based handover performance study using an implementation of a realistic aeronautical access technology. We then investigate the mobility signaling overhead. Finally, we specify a threat model applicable for the aeronautical environment and use it to perform a security analysis of both the old and our new protocol. It is shown that our protocol is not only more secure but also provides better handover latency, smaller overhead in the aeronautical scenario and a higher level of resilience when compared to the original CR protocol. 相似文献
68.
J. Rögner B. Okolo S. Kurzenhäuser M. Müller W. Bauer H.-J. Ritzhaupt-Kleissl E. Kerscher V. Schulze 《Microsystem Technologies》2008,14(12):1831-1837
Due to size effects the mechanical behavior of micro-components with dimensions in the range of some 100 μm and structure
details of about 10 μm differs markedly from those of larger components. This is a crucial aspect for the design of micro-components
for applications where demands for high strength are critical. The present study, which was performed in the frame of the
Collaborative Research Centre 499 (SFB 499), approaches this issue by investigating the relationship between production process,
microstructure and the mechanical properties of micro-specimens made from zirconia using two different feedstocks. The specimens
were produced by a sintering process. The sintering temperature was varied between 1,300 and 1,500°C. Mechanical and tribological
behavior of the specimens was determined by three-point bending tests as well as static and sliding friction tests, respectively.
Properties derived from these tests were then correlated to the surface states in the specimens such as porosity, edge radius
and roughness. The strength of the micro-specimens was found to be significantly influenced by these surface features. Whilst
low porosity alone is not sufficient for high strength, notch effects resulting from pores as well as surface roughness can
lower the strength. With increasing edge radius the strength of the material also increases. The porosity, edge radius and
surface roughness were mathematically correlated with the strength to allow for a forecast. Within the SFB 499 feedstocks
with specific properties were designed and reliable processes were developed to guarantee desirable surface roughness and
porosity in the specimens. A characteristic bending strength of about 2,000 MPa is realizable in the micro-specimens within
a good statistical reliability. The tribological tests revealed that the wear properties of the zirconia micro-components
are strongly dependent on the quality of the feedstock. 相似文献
69.
B. Holzapfel M. Leghissa P. Bauer G. Kreiselmeyer M. Kraus S. Bouffard L. Schultz G. Saemann-Ischenko 《Journal of Superconductivity》1994,7(1):205-207
Epitaxial YBa2Cu3O7–
thin films (YBCO) and YBa2Cu3O7–
/PrBa2Cu3O7–
multilayers (Y/Pr) were irradiated with high-energy heavy ions (770 Mev208Pb) under various directions relative to thec-axis. The irradiation resulted in columnar defects tilted by from thec-axis. The angular dependence of their pinning activity was studied by measuring the anisotropy of the critical current density. TheJ
c
(B, T,) behavior of the irradiated YBCO thin films showed an additional peak, which exceeds the intrinsic pinning peak, exactly at the irradiation direction. The Y/Pr multilayers, however, showed an isotropicT
c
-enhancement by a factor of 5, without any additional structure in theJ
c(B, T,) curve. 相似文献
70.