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  • 1
    Electronic Resource
    Electronic Resource
    Convective heat transfer in the thermal entrance region of parallel-flow noncircular duct heat exchanger arrays (1992)
    Springer
    Heat and mass transfer 27 (1992), S. 465-472 
    Details
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Die Untersuchung bezieht sich auf das konvektive Wärmeübertragungsverhalten eines Gleichstromwärmetauschers mit nichtkreisförmigen Strömungskanälen bei hydraulisch ausgebildetet, thermisch einlaufender Strömung unter Aufprägung einer adiabaten Randbedingung. Zwei Fälle komplizierter Geometrie, nämlich Kanäle mit gleichseitig dreieckigen und halbkreisförmigen Querschnitten, werden bezüglich des Wärmeübergangsverhaltens bei Gleichstromführung eingehend analysiert. Das sich entwickelnde Temperaturfeld in jedem Kanal von der eben spezifizierten Querschnittsform wird halbnumerisch durch Lösung der Energiegleichung unter Einsatz der Linienmethode (MOL) erhalten. Dieser Methode entsprechend erfolgt eine Umformung der Energiegleichung in ein System von Differentialgleichungen erster Ordnung, welches die Temperaturverteilung auf jeder Linie bestimmt. Die Temperaturverteilung im Einlaufgebiet wird unter Vorgabe von 16 oder weniger Linien über dem Kanalquerschnitt erhalten, wobei die gewählte Gitteranordnung drastische Einsparung an Rechenzeit ergibt. Repräsentative Kurven für das Isothermalfeld, den Verlauf der Mischtemperatur für jeden Kanal und die Gesamt-Nusseltzahl als Funktion relevanter Parameter im gesamten Einlaufgebiet sind in Diagrammform dargestellt. Es zeigt sich, daß die mittlere logarithmische Temperaturdifferenz (ΔT LM), der Wärmetauscherwirkungsgrad und die Anzahl der Übertragungseinheiten (NTU) folgende Werte annehmen: 0,247, 0,490 und 1,985 für halbkreisförmige Kanäle sowie 0,346, 0,466 und 1,345 für gleichseitig dreieckige Kanäle.
    Notes: Abstract Convective heat transfer properties of a hydrodynamically fully developed flow, thermally developing flow in a parallel-flow, and noncircular duct heat exchanger passage subject to an insulated boundary condition are analyzed. In fact, due to the complexity of the geometry, this paper investigates in detail heat transfer in a parallel-flow heat exchanger of equilateral-triangular and semicircular ducts. The developing temperature field in each passage in these geometries is obtained seminumerically from solving the energy equation employing the method of lines (MOL). According to this method, the energy equation is reformulated by a system of a first-order differential equation controlling the temperature along each line. Temperature distribution in the thermal entrance region is obtained utilizing sixteen lines or less, in the cross-stream direction of the duct. The grid pattern chosen provides drastic savings in computing time. The representative curves illustrating the isotherms, the variation of the bulk temperature for each passage, and the total Nusselt number with pertinent parameters in the entire thermal entry region are plotted. It is found that the log mean temperature difference (ΔT LM), the heat exchanger effectiveness, and the number of transfer units (NTU) are 0.247, 0.490, and 1.985 for semicircular ducts, and 0.346, 0.466, and 1.345 for equilateral-triangular ducts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01590047
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of inlet subcooling on two-phase flow oscillations in a vertical boiling channel (1989)
    Springer
    Heat and mass transfer 24 (1989), S. 25-36 
    Details
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung In dieser Arbeit werden die Ergebnisse einer experimentellen Untersuchung des Einflusses von Verbesserungen der Wärmeübertragung und der Eintrittsunterkühlung auf Instabilitäten der Zweiphasenströmung dargestellt. Zu diesem Zweck wurde ein einfacher Aufbau konstruiert und aufgebaut. Der Einfluß der Eintrittsunterkühlung wurde unter Benutzung verschiedener Wärmeübertragungsoberflächen und Eintrittstemperaturen bei einer konstanten Wärmezufuhr von 415 W untersucht. Als Testfluid wurde Freon-11 benutzt. Die Experimente wurden für sechs Heizrohre mit verschiedenen Wärmeübertragungsoberflächen durchgeführt. Die Eintrittstemperaturen lagen in diesem Bereich von −9.8°C bis 38°C. Die Ergebnisse zeigen, daß in dem Bereich der vorliegenden Untersuchungen das System mit einem Ansteigen der Eintrittsunterkühlung stabiler wird und daß dessen Instabilitätsgrenze sich zu niedrigeren Massenstromdichten bewegt. Die Amplituden und Perioden der Schwingungen steigen mit Zunahme der Eintrittsunterkühlung an. Für einige der getesteten Oberflächen existierte eine bestimmte Eintrittsunterkühlung, über bzw. unter welcher die Stabilität des Systems abnahm.
    Notes: Abstract In this work, results of experimental research to investigate the effects of heat transfer augmentation and inlet subcooling on two-phase flow instabilities are presented. For this purpose, a simple set-up was designed and built. The effect of inlet subcooling was investigated using different heat transfer surfaces and inlet temperatures at constant heat input of 415 W. Freon-11 has been used as the test fluid, and the experiments were carried out for six heater tubes having different heat transfer surfaces. Inlet temperatures were in the range of −9.8°C to 38°C. The results indicate that, in the range of present experiments, the system becomes more stable, that it's instability boundary moves into lower mass flow rates, with increase in the inlet subcooling. However, the amplitudes and the periods of the oscillations increase with increase in the inlet subcooling. For some of the tested surfaces there was a particular inlet subcooling, above and below which the system's stability decreased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599502
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal Degradation of Cotton Cellulose (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 93-98 
    Details
    ISSN: 1572-8943
    Keywords: degradation ; DTA ; flame retardant ; IR ; pyrolysis ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal degradation of cotton cellulose treated with chemical mixtures containing P and N was studied by thermal analysis, infrared spectroscopy, Char yield and limiting-oxygen-index (LOI). Our experiments demonstrated the following facts. The temperatures and activation energies of pyrolysis were lower for cotton cellulose treated with flame retardants than those for untreated samples and the values of Char yield and LOI were greater for treated cotton than those for untreated one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010132121811
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  • 4
    Electronic Resource
    Electronic Resource
    Magnetic properties of amorphous Bi2DyFe5O12 (1994)
    Springer
    The European physical journal 94 (1994), S. 369-372 
    Details
    ISSN: 1434-6036
    Keywords: 75.50Kj ; 75.70Ak ; 75.30Cr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Amorphous Bi2DyFe5O12 films have been prepared by rf sputtering technique. The magnetic properties, structure and effect of annealing have been investigated. The magnetization increases with increasing magnetic field and is not saturated at a high magnetic field of 65 kOe. In the temperature range 20 K〈T〈200 K the susceptibility can be described by a Curie-Weiss law with a Weiss constant of θ=−15 K. The effective paramagnetic moment for the iron ion (4.1 μ B ) is much smaller than the theoretical moment (5.9 μ B ). Above 200 K the slope in χ−1 vsT curve changes. The Weiss constant and effective paramagnetic moment for the iron ion increase. After annealing above 600°C the amorphous samples crystallize to a single garnet phase with the magnetization of 21 emu/g at 1.5 K and 7.2 emu/g at 300 K, which are the same as those of the bulk Bi2DyFe5O12 garnet ferrites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01317398
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  • 5
    Electronic Resource
    Electronic Resource
    Halo or skin in the excited states of some light mirror nuclei (2005)
    Springer
    The European physical journal 23 (2005), S. 11-17 
    Details
    ISSN: 1434-601X
    Keywords: 21.10.Gv Mass and neutron distributions ; 21.60.Jz Hartree-Fock and random-phase approximations ; 21.10.Dr Binding energies and masses ; 27.20.+n 6 ⩽ A ⩽ 19
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The properties of three pairs of mirror nuclei 13N- 13C, 15N- 15O and 21Na- 21Ne (these mirror nuclei are all made of a good inert core plus an unpaired valence nucleon) are investigated by using the nonlinear relativistic mean-field (RMF) theory. It is found that the calculated binding energies with two different parameter sets are very close to the experimental ones for both the ground states and the excited states except for the large deformed nuclei. The calculations show that the 2s1/2 excited states of 15N and of 21Na are both weakly bound with a proton halo and a proton skin (or a pigmy proton skin), respectively. In addition, the 1d5/2 excited state of 13C and the 2s1/2 excited state of 15O are also weakly bound with a neutron skin, respectively. The ratio of the valence nucleon radius to matter radius is deduced and it can be regarded as an additional criterion for the existence of exotic structure. The unbound 2s1/2 and 1d5/2 excited states of 13N are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epja/i2004-10074-0
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetic properties of Co0.3Fe2.7O4 films with (1 1 0) texture (1997)
    Springer
    Journal of materials science 16 (1997), S. 1558-1560 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018551914668
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  • 7
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    Enhancement of Zero Averaged Refractive Index Gaps Frequency Range by Using One-Dimensional Ternary Photonic Crystals Containing Negative-Index Materials (2009)
    Springer
    Details
    Publication Date: 2009-11-10
    Print ISSN: 1866-6892
    Electronic ISSN: 1866-6906
    Topics: Physics
    Published by Springer
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  • 8
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    Structural heterogeneity and functional diversity of topologically associating domains in mammalian genomes (2015)
    Oxford University Press
    Details
    Publication Date: 2015-08-29
    Description: Recent chromosome conformation capture (3C) derived techniques have revealed that topologically associating domain (TAD) is a pervasive element in chromatin three-dimensional (3D) organization. However, there is currently no parameter to quantitatively measure the structural characteristics of TADs, thus obscuring our understanding on the structural and functional differences among TADs. Based on our finding that there exist intrinsic chromatin interaction patterns in TADs, we define a theoretical parameter, called aggregation preference (AP), to characterize TAD structures by capturing the interaction aggregation degree. Applying this defined parameter to 11 Hi-C data sets generated by both traditional and in situ Hi-C experimental pipelines, our analyses reveal that heterogeneous structures exist among TADs, and this structural heterogeneity is significantly correlated to DNA sequences, epigenomic signals and gene expressions. Although TADs can be stable in genomic positions across cell lines, structural comparisons show that a considerable number of stable TADs undergo significantly structural rearrangements during cell changes. Moreover, the structural change of TAD is tightly associated with its transcription remodeling. Altogether, the theoretical parameter defined in this work provides a quantitative method to link structural characteristics and biological functions of TADs, and this linkage implies that chromatin interaction pattern has the potential to mark transcription activity in TADs.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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  • 9
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    Spatial Colocalization of Human Ohnolog Pairs Acts to Maintain Dosage-Balance (2016)
    Oxford University Press
    Details
    Publication Date: 2016-08-19
    Description: Ohnologs –paralogous gene pairs generated by whole genome duplication– are enriched for dosage sensitive genes, that is, genes that have a phenotype due to copy number changes. Dosage sensitive genes frequently occur in the same metabolic pathway and in physically interacting proteins. Accumulating evidence reveals that functionally related genes tend to co-localize in the three-dimensional (3D) arrangement of chromosomes. We query whether the spatial distribution of ohnologs has implications for their dosage balance. We analyzed the colocalization frequency of ohnologs based on chromatin interaction datasets of seven human cell lines and found that ohnolog pairs exhibit higher spatial proximity in 3D nuclear organization than other paralog pairs and than randomly chosen ohnologs in the genome. We also found that colocalized ohnologs are more resistant to copy number variations and more likely to be disease-associated genes, which indicates a stronger dosage balance in ohnologs with high spatial proximity. This phenomenon is further supported by the stronger similarity of gene co-expression and of gene ontology terms of colocalized ohnologs. In addition, for a large fraction of ohnologs, the spatial colocalization is conserved in mouse cells, suggestive of functional constraint on their 3D positioning in the nucleus.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
    Published by Oxford University Press
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  • 10
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    Numerical analysis of the interactions of sheet cavitation and cloud cavitation around a hydrofoil (2015)
    Institute of Physics (IOP)
    Details
    Publication Date: 2015-01-16
    Description: Partial cavitation and cloud cavitation on NACA66(MOD) was studied based on PANS turbulence model combined with the Zwart cavitation model. The results agree well with the data from the experimental results. The existence of a kind of unsteady characteristics of cloud cavitation is analysed in details. The reasons for the inhibition mechanism of the sheet cavitation are discussed. Pressure shock wave occurs near the tailing edge of the hydrofoil when the collapse of cloud is so large leading to great influence on the cavity closed to the leading edge. The evolution of the pressure peak and its propagation toward the leading edge were investigated through the study of the time domain signal of the monitor points along the streamline of flow. Finally, the propagation of the pressure wave on the suction side was further investigated through analysing the spatial-time history of wall pressure.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics (IOP)
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