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81.
Frank Bierbrauer 《Computers & Fluids》2007,36(7):1199-1212
The CFD modeling of two-dimensional multiphase flows is a useful tool in industry, although accurate modeling itself remains a difficult task. One of the difficulties is to track the complicated topological deformations of the interfaces between different phases. This paper describes a marker-particle method designed to track fluid interfaces for fluid flows of at least three phases. The interface-tracking scheme presented in this paper is the first part of a series of papers presenting our complete model based on a one-field Godunov marker-particle projection scheme (GMPPS). In this part, we shall focus on the presentation of the interface-tracking scheme and the kinematic tests we conducted to examine the scheme’s ability to accurately track interfacial movements typified by vorticity-induced stretching and tearing of the interface. Our test results show that for a set of carefully designed and commonly used error measures, relative percentage errors never exceed 2% for all of the tests and grid sizes considered, provided a sufficient number of marker particles are used. We shall also demonstrate that the method is of second-order accuracy and the interface transition width remains constant never exceeding three cell widths. 相似文献
82.
S. Salar Behzadi Silvester Ölzant Reinhard Länger Christian Koban Frank M. Unger Helmut Viernstein 《European Food Research and Technology》2006,223(2):238-245
Inversion of sucrose is a stability problem particularly of candies with acidic taste that contain sucrose and small amounts of organic acids such as citric acid, since the free d-fructose produced by hydrolysis is hygroscopic. The following possibilities were investigated for preventing the hydrolysis of sucrose in tablets containing sucrose and citric acid: Adding various amounts of tri-sodium citrate to the formulation to neutralize the citric acid, (Hot) melt coating of citric acid and tri-sodium citrate with a vegetable fat at different coating ratios, variation of the ratio of coated citric acid and tri-sodium citrate in formulations, and compressing the formulations with different compression forces. After tablet processing and storage of tablets, the concentration of d-fructose was determined on the basis of enzymatic reactions. A response surface central composite design was used. The above-mentioned variations were chosen as independent variables and the amount of d-fructose was chosen as response variable. The lowest rates of inversion could be achieved by increasing the content of tri-sodium citrate and the ratio of coating material and decreasing the ratio of coated citric acid and tri-sodium citrate in the tablet formulations. The compression force had no significant effect on the inversion of sucrose. 相似文献
83.
Athanasios Eftaxias Josep Font Agusti Fortuny Azael Fabregat Frank Stüber 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(6):677-687
The wet air oxidation of phenol over a commercial active carbon catalyst was studied in a trickle bed reactor (TBR) in the temperature and oxygen partial pressure ranges of 120–160 °C and 0.1–0.2 MPa, respectively. The performance of the active carbon was compared in terms of phenol and COD destruction. The weight change of active carbon due to reaction was also measured. Finally, oxic phenol adsorption isotherms were assessed in batch conditions at 25, 125 and 160 °C. In order to use the conversion data obtained from the TBR for a kinetic study, special care was taken to check the kinetic control in the TBR experiments. Several kinetic models including power law or Langmuir–Hinshelwood expressions were considered to describe the catalytic oxidation of phenol over active carbon. The simple power law model with first order dependence on both phenol and oxygen concentration predicted satisfactorily the experimental data not only over the entire range of operating conditions studied, but also outside its validity range. Copyright © 2005 Society of Chemical Industry 相似文献
84.
Witt Ellen; Frank Rainer; Hengstenberg Wolfgang 《Protein engineering, design & selection : PEDS》1993,6(8):913-920
The 6-phospho-ß-galactosidase of Staphylococcus aureus,Lactococcus lactis and Lactobacillus casei and 6-phospho-ßglucosidaseB of Escherichia coli build a subfamily inside a greater enzymefamily, named the glycosal hydrolase family 1, which, hi addition,contains nine ß-glycosidases of different origins.Kinetic and immunological evidence is provided in this reportwhich strengthens the relationship of the four 6-phospho-ß-glycosidases.It is shown that the 6-phospho-ß-galactosidases and6-phospho-ß-glucosidase B are able to split aromaticß-galactoside phosphates and ß-glucosidephosphates. The turnover numbers of hydrolysis of substrateswith different epimerization at C-4 of the glycon vary up to15-fold only. Two polydonal antisera, one derived against thenative 6-phospho-ß-galactosidase from S.aureus andthe other derived against the 6-phospho-ß-glucosidaseB, cross-reacted with both enzymes. Peptides of the proteinswere separated by reverse phase HPLC. The cross-reacting peptideswere sequenced and shown to be localized at almost the sameposition in the aligned primary structures of both enzymes.An insertion of nine amino adds near these antigenic domainsis unique for the 6-phospho-ß-glycosidases and missingwithin the sequences of the ß-glycoside-specific membersof the family. The lacG gene of a 6-phospho-ß-galactosidasenegative S.aureus mutant was doned into E.coli and sequenced.In the totally inactive mutant protein only the glycine at position332 was changed to an arginine. This amino acid is part of thesequence insertion near the antigenic domain reacting with bothantisera. These data support the assumption that the regionis of great importance for the function of the enzymes and thatit is possible it determines the specificity of the phosphorylatedform of the substrates. In addition, the 6-phospho-ß-galactosidaseof S.aureus was modified by sitedirected mutagenesis of thecorresponding lacG gene hi order to replace residues Glul60and Glu375, which were suspected of being involved hi the generalacid catalysis of substrate hydrolysis, with glutamine residues.The mutant protein 160EQ retained some catalytic activity whilethe protein 375EQ was totally inactive. Glu375 is the activesite nudeophile of the 6-phospho-ß-galactosidase ofS.aureus. It is located in the sequence motif ENG where Glu358was identified as the catalytkally active nudeophile hi theß-glucosidase of Agrobacterium. 相似文献
85.
Comprehensive meta-analysis of integrity test validities: Findings and implications for personnel selection and theories of job performance. 总被引:1,自引:0,他引:1
Ones Deniz S.; Viswesvaran Chockalingam; Schmidt Frank L. 《Canadian Metallurgical Quarterly》1993,78(4):679
Conducted a comprehensive meta-analysis based on 665 validity coefficients across 576,460 data points to investigate whether integrity test validities are generalizable and to estimate differences in validity due to potential moderating influences. Results indicate that integrity test validities are substantial for predicting job performance and counterproductive behaviors on the job, such as theft, disciplinary problems, and absenteeism. The estimated mean operational predictive validity of integrity test for predicting supervisory ratings of job performance is .41. Results from predictive validity studies conducted on applicants and using external criterion measures (i.e., excluding self-reports) indicate that integrity tests predict the broad criterion of organizationally disruptive behaviors better than they predict employee theft alone. Despite the influence of moderators, integrity test validities are positive across situations and settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
86.
From dust till drawn 总被引:1,自引:0,他引:1
William Van Haevre Tom Van Laerhoven Fabian Di Fiore Frank Van Reeth 《The Visual computer》2007,23(9-11):925-934
We present a system for drawing pastel media in real-time as an effective alternative to most existing digital solutions that basically allow for drawing arbitrary strokes in a particular style. Our approach is focused on the simulation of the natural material itself and on its interaction with the drawing surface and the drawing tool. Upon free-form drawing, a bidirectional transfer of pigment takes place. In one direction, the paper surface is dusted with new pigment particles broken off the tip (i.e., the end of the drawing tool). A large part of these particles will be deposited or blended together with previously deposited ones whereas the remainder does not contribute to the drawing and is blown off. On the other hand, a certain amount of previously deposited pigment is scraped off and picked up again soiling the tip. This is noticeable in the next strokes to be drawn. Furthermore, both the tip and the paper surface are subject to weathering depending on the exerted pressure and friction of the drawing tool, and the bumpiness of the paper. As a result, the paper surface becomes slightly damaged, limiting the deposition of new pigment. The tip, on the other hand, becomes blunt making new strokes wider. From a stylistic point of view, similarly to traditional drawings our results convey the artists’ characteristics (e.g., the way of wielding the brush, skillfulness, feeling for the medium). Therefore, we believe that our system allows an artist to create realistically looking pastel images without losing his/her personal touch. 相似文献
87.
In Deutschland geh?rt der Einsatz von NEDAP-Wahlcomputern in immer mehr Gemeinden zum Alltag. Durch Untersuchungen zur Sicherheit
und Manipulierbarkeit konnten Erkenntnisse gewonnen werden, mit welchen Methoden manipulierte Software in den Wahlcomputer
eingebracht und Hardwarekomponenten ausgetauscht werden k?nnen. Dadurch ist erstmals eine Beurteilung der Eignung der NEDAP-Wahlcomputer
hinsichtlich der Anforderungen an manipulationsfeste, nachvollziehbare und transparente Wahlen m?glich. 相似文献
88.
CMOS scaling into the nanometer regime 总被引:11,自引:0,他引:11
Yuan Taur Buchanan D.A. Wei Chen Frank D.J. Ismail K.E. Shih-Hsien Lo Sai-Halasz G.A. Viswanathan R.G. Wann H.-J.C. Wind S.J. Hon-Sum Wong 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1997,85(4):486-504
Starting with a brief review on 0.1-μm (100 nm) CMOS status, this paper addresses the key challenges in further scaling of CMOS technology into the nanometer (sub-100 nm) regime in light of fundamental physical effects and practical considerations. Among the issues discussed are: lithography, power supply and threshold voltage, short-channel effect, gate oxide, high-field effects, dopant number fluctuations and interconnect delays. The last part of the paper discusses several alternative or unconventional device structures, including silicon-on-insulator (SOI), SiGe MOSFET's, low-temperature CMOS, and double-gate MOSFET's, which may lead to the outermost limits of silicon scaling 相似文献
89.
V.D. Sandberg L. Bayliss M. Dugan J.S. Frank T. Gordon G. Hart C.M. Hoffman G.E. Hogan H.S. Matis G.H. Sanders H.P. Von Gunten 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,234(3):512-516
A circuit is described that determines the average of the transit time of light from an event in a scintillation counter to the two ends of that counter. The design offers superior time resolution and a novel gating scheme that significantly reduces circuit dead-time. 相似文献
90.
In general, the performance of a KE penetrator against most targets increases with velocity regardless of the particular penetrator-target interaction mode. It is possible to show that there exists an optimum velocity which maximizes the performance of an impacting penetrator for a given expenditure of kinetic energy. Simple graphical methods are described that determine the optimum velocity from general performance-velocity plots. These graphical methods may also be applied to experimental data alone. In addition, simple analytic models which describe the velocity dependent penetration/perforation performance of KE penetrators are examined and extended. These models may be used to explicitly assess the influence of parameters such as target strength and density and penetrator mass, strength and density. For some of the models in this analysis, the explicit relations between the optimum striking velocity for a specific kinetic energy value and the penetrator-target parameters are described. 相似文献