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101.
M. Wegener M. Fevre A.R. Paschedag M. Kraume 《International Journal of Heat and Mass Transfer》2009,52(11-12):2543-2551
Marangoni instabilities in dispersed liquid/liquid systems occur if the local solute concentration varies over the interface. The additional shear stress at the interface between a droplet and an ambient phase generates complex convection patterns which increase temporarily the global drag coefficient of the drop and thus retard the drop rise velocity. When Marangoni effects get weaker, the shear forces decrease and the drop reaccelerates. In the present experimental study, the transient drop rise velocity has been intensely investigated in the system toluene(d)/acetone(s)/water(c) for different initial solute concentrations and different drop diameters. Both mass transfer directions have been considered. The reacceleration time as an indicator of the end of Marangoni dominance can be expressed as a function of drop diameter and initial solute concentration. 相似文献
102.
Tanja E. J. Vos Felix F. Lindlar Benjamin Wilmes Andreas Windisch Arthur I. Baars Peter M. Kruse Hamilton Gross Joachim Wegener 《Software Quality Journal》2013,21(2):259-288
During the past years, evolutionary testing research has reported encouraging results for automated functional (i.e. black-box) testing. However, despite promising results, these techniques have hardly been applied to complex, real-world systems and as such, little is known about their scalability, applicability, and acceptability in industry. In this paper, we describe the empirical setup used to study the use of evolutionary functional testing in industry through two case studies, drawn from serial production development environments at Daimler and Berner & Mattner Systemtechnik, respectively. Results of the case studies are presented, and research questions are assessed based on them. In summary, the results indicate that evolutionary functional testing in an industrial setting is both scalable and applicable. However, the creation of fitness functions is time-consuming. Although in some cases, this is compensated by the results, it is still a significant factor preventing functional evolutionary testing from more widespread use in industry. 相似文献
103.
A new model MISOS is proposed for the simulation of the borehole filling (grout) of double U-pipe heat exchangers. When simulating ground-coupled heat pumps, a suitable model of the filling is necessary because the temperature of the filling effects the temperature of the heat carrier fluid. The filling is divided into three elements whose geometry corresponds to the different temperature zones. For each time step, the temperatures of the filling elements can be calculated from energy balances. MISOS is very fast compared to computational fluid dynamics (CFD) algorithms. CFD calculations were performed for different shank spacings, and results compared with those obtained from MISOS. If the pipe shanks are situated between the axis and the wall of the borehole, nearly the same difference of the fluid temperature between inlet and outlet is predicted by MISOS and CFD. For a minimal shank spacing, heating is overpredicted by about 6% for an extraction period of 3 h while an underprediction of about 9% is obtained for maximal shank spacing. 相似文献
104.
Using three high sensitive pressure transducers located inside a slit-die of a capillary rheometer and applying a set of advanced mathematical tools to process the acquired time dependent pressure signals, we are able to detect in-situ pressure fluctuations associated with sharkskin instabilities. Other distortions, as spurt and gross melt fracture, can also be in-situ detected. This originates from a factor of 103 and 102 improvement in terms of time and pressure resolution achieved using the new set-up and data analysis that it will be described in detail in this article. Our approach quantifies the effect of polymer topology and shear rate on the characteristic frequency and amplitude of these pressure fluctuations inside the die. Depending on the polymer structure and the shear rate, different instabilities with large deviation in their main properties at melt-state, can be determined. Based on our results, a polymer-independent power law relationship between the characteristic frequency of the instability and the apparent shear stress has been found. Combining this new technique with the advanced mathematical analysis used, clear evidences concerning the origin and location of these instabilities, could be established. According to our analysis, the spurt instability starts in the entrance of the die and it propagates downstream while increasing its velocity along the die. This was confirmed by non-zero-time-lags in the cross-correlation function between the transducers located inside the slit-die. In case of sharkskin instability, pressure fluctuations inside the die indicate that its origin could also be already inside the die instead of being exclusively located at the die-exit region, as stated in earlier investigations. 相似文献
105.
Jens Bender Dennis Kügler Marian Margraf Ingo Naumann 《Datenschutz und Datensicherheit - DuD》2010,34(5):295-298
Dieser Artikel beschreibt im Detail die datenschutzfreundliche Ausgestaltung des Sperrmanagements, wie es im neuen deutschen
Personalausweis zum Einsatz kommt. 相似文献
106.
Ingo Franke Oliver HentschelDavid Nitsche Michael StopsHans-Dieter Bauer Birgit Scheppat 《International Journal of Hydrogen Energy》2013
An experimental set-up has been developed to carry out in-situ measurements on hydrogen storage materials. It has been used to perform FTIR–ATR measurements on sodium alanate samples during hydrogen desorption and, in parallel, to perform gravimetrical measurements on the same sample. The ATR spectra showed the typical broad Al–H vibrational features, changing according to the phase change the material undergoes during the load cycle. It is shown that the absorbance of the material at these bands and the hydrogen content correspond to each other in a reproducible way. This behavior may be used to measure the hydrogen mass released by an alanate hydrogen reservoir by measuring the optical absorbance at defined wavelengths. In this paper the results of these experiments that may give rise to the realization of a level sensor in future hydrogen storage applications are presented. 相似文献
107.
It is known that if a Boolean function f in n variables has a DNF and a CNF of size then f also has a (deterministic) decision tree of size exp(O(log n log2
N)). We show that this simulation cannot be made polynomial: we exhibit explicit Boolean functions f that require deterministic trees of size exp where N is the total number of monomials in minimal DNFs for f and ?f. Moreover, we exhibit new examples of explicit Boolean functions that require deterministic read-once branching programs
of exponential size whereas both the functions and their negations have small nondeterministic read-once branching programs.
One example results from the Bruen—Blokhuis bound on the size of nontrivial blocking sets in projective planes: it is remarkably
simple and combinatorially clear. Other examples have the additional property that f is in AC0.
Received: June 5 1997. 相似文献
108.
A. Krajewski A. Ravaglioli R. Valmori S. Sturlese S. M. Ingo 《Journal of Materials Science》1986,21(5):1625-1630
A correlation between composition and quality of a biological glass used as a bioglaze and an industrial glaze for sheet-steel coating was carried out. Apart from the extremely different conditions, particularly relative to the temperature for application of the coating to the metallic substrate, it was noted that the compositions are not very much different; this led us to think that the doping of the vitreous system with substances favouring the bonding of glaze to support (according what has been suggested by enamellists) is trustworthy in this case too. Some hypotheses relative to the role of nickel and the fluidity of the vitreous system were made to explain the observations, and to suggest the best way to improve the adhesion of metal to glaze. 相似文献
109.
110.