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81.
82.
In this paper, we address the problem of localizing extrema points and iso-contours of ambient environmental fields (specifically,
ocean bottom landscape and underwater plumes) using a networked formation of autonomous underwater vehicles. We propose the
use of the Nelder-Mead extension to the basic simplex nonlinear optimization algorithm. In these robust gradient-free strategies,
decisions are solely made based on field values measured by the individual vehicles, while measurements are fused and actions
decided according to the algorithm. A main goal of this paper is to trigger interest in direct search methods as pertains
to this type of robotic problem. 相似文献
83.
Capturing software design knowledge is important because it tends to evaporate as software systems evolve. This has severe consequences for many software projects. To counteract this phenomenon, effective, systematic documentation of design knowledge is important. However, many proposed approaches for capturing design knowledge are still experimental or in an early-adoption stage. In this article, we discuss existing and new approaches to deal with parts of the knowledge evaporation problem. 相似文献
84.
Akram El Hasni Stefan Pfirrmann Anett Kolander Erwin Yacoub-George Martin König Christof Landesberger Anja Voigt Gabi Grützner Uwe Schnakenberg 《Microfluidics and nanofluidics》2017,21(3):41
We present a new epoxy-based negative-tone dry film photoresist (DFR) for fabricating multilayer microfluidic devices using a lamination process combined with a standard photolithography technology. As proof-of-concept, a complex 3D-hydrodynamic focusing device was produced via a six-layer lamination process of 33 µm-thick DFR layers. The bonding strength of the new DFR was tested on silicon, glass, and titanium substrates, respectively. A maximum bonding strength of 37 MPa was obtained for the dry film photoresist laminated on glass. No leakage was found, and burst tests proved excellent robustness and sealing reliability of the microchannels. 相似文献
85.
Investigations on metal-cutting machining processes that were conducted since the second half of the twentieth century have
considerably contributed to disclosing the principles underlying the cutting process. Although numerous studies have been
carried out on this subject, a generally valid model of the cutting process and the interactions in the separating processes
does not exist yet. Such a model could guarantee the disclosure of the principles of thermodynamic interactions between the
cutting process and the involved machine structure. This contribution is twofold and presents an experimental setup used to
determine cutting forces and temperatures in orthogonal cutting processes. The results are then used as a reference for simulations
made with the Discrete Element Method (DEM). The DEM is due to its meshless nature well suited to capture large deformations
and rupture of material which is included very naturally. It is examined to which extent the measured results can be captured
with the DEM model. 相似文献
86.
The Autosar standard represents an emerging approach to unifying virtually all aspects of the development workflow of automotive embedded software. The standard features an XML schema used as a basis for interchanging documents containing Autosar model content. Although the schema is primarily for document exchange, it could also be the basis for creating a metamodel. However, a tool metamodel should probably be designed differently. 相似文献
87.
88.
Hans-Juergen Odenthal Uwe Thiedemann Udo Falkenreck Jochen Schlueter 《Metallurgical and Materials Transactions B》2010,41(2):396-413
The oscillation of argon oxygen decarburization (AOD) converters is flow related and depends on the process parameters (e.g., vessel geometry, melt fill height, process gas type and blowing rate, vessel tilting angle, as well as geometry, number,
and arrangement of the side-wall nozzles). For a 120-ton AOD converter with seven submerged side-wall nozzles, plant tests,
physical simulations on a 1:4 scale water model, and computational fluid dynamics simulations have been done. The investigations
show that the penetration depth of an inert gas jet into the melt does not exceed approximately 0.4 m. The plumes are located
close to the nozzle-side converter wall and induce a large-scale primary vortex as well as intensive surface movements; both
are responsible for the oscillation. Several process mechanisms were investigated. The oscillation is highest in the last
stage of the dynamic blow and is still high during the reduction stage. As the amount of inert gas increases, the vibration
level also increases. Inert gas has a greater influence on the oscillation than oxygen. Tilting the converter around 8 deg
clearly leads to more intensive oscillations. Increasing the blowing rate increases the forces and torques acting on the vessel,
whereas the oscillation frequency remains nearly constant. A varying fill level does not influence the vibration level the
same way as the blowing rate. The operational test shows, for example, that the maximum torque does not depend on the heat
size when the latter varies between –8 pct and +21 pct of the nominal heat size. The water model test shows decreasing forces
and torques with a rising fill level. 相似文献
89.
Angela Gerlach Enrico Preuss Paul Uwe Thamsen Flemming Lykholt-Ustrup 《Journal of Mechanical Science and Technology》2017,31(4):1711-1719
We did a numerical study of the internal flow field of a vortex pump. Five operating points were considered and validated through a measured characteristic curve. The internal flow pattern of a vortex pump was analyzed and compared to the Hamel-Oseen vortex model. The calculated flow field was assessed with respect to the circumferential velocity, the vorticity and the axial velocity. Whereas the trajectories of the circumferential velocity were largely in line with the Hamel-Oseen vortex model, the opposite was true for vorticity. Only the vorticity at strong part load was in line with the predictions of the Hamel-Oseen vortex model. We therefore compared the circumferential velocity and vorticity for strong part load operation to the analytical predictions of the Hamel-Oseen vortex model. The simulated values were below the analytical values. The study therefore suggests that a vortex similar to the Hamel-Oseen vortex is only present at the strong part load operation. 相似文献
90.