ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

A wide-band high-sensitivity laser strainmeter (1991)

Crescentini, L. ; Renzella, G.

[S.l.] : American Institute of Physics (AIP)

Review of Scientific Instruments 62 (1991), S. 1206-1209

add to mindlist on the mindlist

Details

ISSN: 1089-7623

Source: AIP Digital Archive

Topics: Physics , Electrical Engineering, Measurement and Control Technology

Notes: A new laser strainmeter, inspired by those used in the first gravitational waves detectors, is presented. A wide-band feedback circuit controls the optical length of the reference arm of an unequal-arm Michelson interferometer by means of a Pockels cell. No modulation is added to the Pockels cell supply, since laser power fluctuations are proved to be of negligible effect if some care is taken in balancing the two outputs of the interferometer. A reset circuit follows variations in arm length greater than λ, obscuring the servo for 50 μs. As a consequence, an analog signal combined with a digital signal allow to detect any change in the arm length greater than 10−3 λ. The frequency band extends from continuous signals to 100 kHz.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1142516

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Butadiene/styrene/2-methyl-5-vinylpyridine terpolymer. Composition-conversion data in comparison with calculated values (1965)

Crescentini, L. ; Gechele, G. B. ; Zanella, A.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 9 (1965), S. 1323-1340

add to mindlist on the mindlist

Details

ISSN: 0021-8995

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Terpolymers from 1,3-butadiene, styrene, and vinylpyridine are important as rubbers, and, in latex form, as components of rubber-to-fabric adhesives. Three monomer mixtures having the approximate weight composition butadiene/styrene/2-methyl-5-vinylpyridine 70/15/15, 25/48/27, and 38.5/49/12.5 have been emulsion-polymerized at 30°C., and the terpolymer composition as a function of the conversion has been studied. The six monomer reactivity ratios have been determined by binary copolymerizations at 30°C. and checked by low conversion bulk terpolymerizations. Average and instantaneous composition-conversion curves have been calculated, on the assumption of a constant reaction volume, by numerical integration of the terpolymerization equations on electronic computer. Details, of general applicability, for calculations are given. The experimental results of the emulsion terpolymerizations fit satisfactorily the calculated curves over a wide range of conversions.

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/app.1965.070090412

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

Melting temperatures and polymer-solvent interaction for polycaprolactam (1963)

Gechele, G. B. ; Crescentini, L.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 7 (1963), S. 1349-1357

add to mindlist on the mindlist

Details

ISSN: 0021-8995

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Melting points of four polycaprolactam samples of different molecular weight and their mixtures with various diluents were determined. Heats of fusion and polymer-diluent energy of mixing parameters were calculated according to the theory of Flory. The heats of fusion were found to be about 38 cal./g. The experimental results (independence from molecular weight above a certain value, and from the nature of terminal groups, etc.) agree with the theory. However, in a few cases of poor solvents anomalous behavior can be suspected.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/app.1963.070070415

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

Properties of dilute solutions of poly(2-methyl-5-vinyl pyridine) (1966)

Garbuglio, C. ; Crescentini, L. ; Mula, A. ; [et al.]

New York : Wiley-Blackwell

Die Makromolekulare Chemie 97 (1966), S. 97-112

add to mindlist on the mindlist

Details

ISSN: 0025-116X

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Description / Table of Contents: Poly(2-methyl-5-vinylpyridin) wurde durch Blockpolymerisation hergestellt und nach der Elutionsmethode fraktioniert. Als Lösungsmittel-Fällungsmittelsystem wurde Cyclohexanon/n-Heptan benutzt. Die Fraktionen wurden viskosimetrisch analysiert; die Molekulargewichte wurden nach der Lichtstreuungsmethode bestimmt. Die folgende Viskositäts-Molekulargewichts-Beziehung gilt für den Molekulargewichtsbereich von etwa 6.104 bis 106 in Methyläthylketon als Lösungsmittel bei 25°C: [η]-M-Beziehungen sind auch für Methanol aufgestellt worden sowie für die drei Θ-Lösungsmittel n-Butylacetat bei 21,8°C, Methylisobutylketon bei 37,4°C und n-Amylacetat bei 48,2°C. Die FLORY-Konstante wurde aus Messungen im O-Zustand zu 83·10-3 cm3·g-1(g·mol-l)-l/2 bestimmt; sie ist im untersuchten Bereich temperatabhängig. Derselbe Wert wurde auch aus den Viskositäts- und Lichtstreuungs-Meßdaten nach der Methode von KURATA und STOCKBUYER erhalten. Die Ketted exibilität des Poly(2-methyl-5-viny1-pyridin) ist derjenigen von Polymeren mit ahnlicher Moleknlarstruktur vergleichbar, wie ä. B. Polystyrol, substituierte Polystyrole oder Poly(4-vinylpyridin). Die thermodynamischen Wechselwirkungs-Parameter Θ und Ψ wurden durch Viskosimetrie mit Lösungen in Methyläthylketon bestimmt. Die Abhängigkeit des zweiten Virialkoeffizienten vom Molekulargewicht in diesen Lösungen wurde mit theoretisch berechneten Werten verglichen.

Notes: Poly(2-methyl-5-vinyl pyridine) was prepared by mass polymerization and elution fractionated. Cyclohexanone/n-heptane was used as solvent/nonsolvent pair. Fractions of various molecular weights were analyzed by viscosimetry and light scattering. The following intrinsic viscosity-molecular weight relation was obtained at 25°C. in methylethyl ketone by light scattering measurements on fractions with molecular weights ranging from ca. 6·104 to 106. [η]-M relations were also obtained in methanol and in three Θ-solvents, i.e. n-butyl acetate at 21.8°C., methylicobutyl ketone at 37.4°C., and n-amyl acetate at 48.2°C. The FLORY constant determined from the Θ-measurements was found to be constant with the temperature in the range considered. Its value is 83·10-3·cm3·g-1·(g.mole-1)-1/2. The same value was obtained by treating the viscosity and light scattering results in methylethyl ketone according to the KURATA and STOCKMAYER theory. The flexibility of the chains of poly(2-methyl-5-vinyl pyridine) was found to be similar to that of polymers of similar molecular structure such as polystyrene, substituted polystyrenes or poly(4-vinyl pyridine). The thermodynamic interaction parameters Θ and Ψ were determined in methylethyl ketone by viscosimetry. The experimental dependence of the second virial coefficient on molecular weight for the latter solvent was compared in detail with that calculated according to existing theoretical treatments.

Additional Material: 10 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/macp.1966.020970109

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

Phase separation, viscosity, and thermodynamic parameters for poly-2-methyl-5-vinylpyridine-diluent systems (1965)

Gechele, G. B. ; Crescentini, L.

New York : Wiley-Blackwell

Journal of Polymer Science Part A: General Papers 3 (1965), S. 3599-3611

add to mindlist on the mindlist

Details

ISSN: 0449-2951

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: Liquid-liquid phase separation has been investigated for several poly-2-methyl-5-vinylpyridine fractions in eleven solvents. The plots of precipitation temperatures against polymer volume fractions are shown for a few systems. The agreement between two curves calculated according to Flory and the experimental ones is only qualitative, and the calculated critical concentrations are much smaller than the experimental ones. Plots of reciprocal critical precipitation temperature against reciprocal square root molecular weight of the polymer are straight lines. From the intercepts and slopes the values of the thermodynamic paramerers θ and ψ were calculated. Intrinsic viscosities were determined for a fraction of 990,000 molecular weight in five solvents at various temperatures. Theta measurements yielded for Flory's constant K the value 8.4 × 10-4, which can be assumed to be constant with the temperature and the solvent. Moreover the parameter θ and ψ were calculated according to Flory and Fox, Kurata, Stockmayer, and Roig, and Kurata and Stockmayer. The viscometric ψ are different from each other and all much smaller than the ones from phase separation. An attempt is made to compare the above theories by utilizing intrinsic viscosity results on fractions of various molecular weights in n-propyl acetate and methyl isobutyl ketone. The results show nearly the same behavior for all the three theories.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pol.1965.100031022

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Unknown

A wide‐band high‐sensitivity laser strainmeter (1991)

Crescentini, L. ; Renzella, G.

American Institute of Physics

In: Review of Scientific Instruments. 1991; 62(5): 1206-1209. Published 1991 May 01. doi: 10.1063/1.1142516.

add to mindlist on the mindlist

Details

Publication Date: 1991-05-01

Print ISSN: 0034-6748

Electronic ISSN: 1089-7623

Topics: Electrical Engineering, Measurement and Control Technology , Physics

Published by American Institute of Physics

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER CURRENT

S·F·X

Fulltext

7

Unknown

Inversion of synthetic geodetic data for dip-slip faults: clues to the effects of lateral heterogeneities and data distribution in geological environments typical of the Apennines (Italy) (2013)

Amoruso, A., Barba, S., Crescentini, L., Megna, A.

Oxford University Press

In: Geophysical Journal International

add to mindlist on the mindlist

Details

Publication Date: 2013-01-11

Description: The inversion of geodetic data to obtain earthquake parameters is often performed by assuming that the medium is isotropic, elastic and either homogeneous or layered. The layered medium often offers the best estimate of the structure of the crust; however, predicted displacements and observed data may differ beyond the measurement errors. The slip distribution on the fault plane is usually obtained by dividing the best uniform slipping fault into an arbitrarily large number of subfaults and minimizing a cost function that includes a smoothness (Laplacian) term and a data misfit term. The smoothing factor controls the trade-off between the smoothness and the goodness-of-fit. The main focus of this work is the determination and effect of the smoothing parameter. We conducted several inversion tests of noiseless synthetic surface displacement due to faults embedded in media with properties consistent with the geology of the Central Apennines (Italy), where the 2009 April 6, L'Aquila earthquake occurred. We used the following three-step procedure: (i) global optimization with no smoothness constraint for a fault divided into a small number of equally sized equal-rake subfaults; (ii) selection of the best fault parameters using information criteria and (iii) evaluation of the slip amplitude distribution on an expanded fault after choosing the smoothing factor from trade-off curves or from cross-validation for different numbers of subfaults. We show that all of the fault features obtained by the inversion procedure, including the slip distribution, agree with those (‘true’) used in the forward modelling when the data cover the majority of the displacement field. Notable departures from the true slip distribution occur when a suboptimal smoothing factor (obtained from the trade-off curves or cross-validation) is used. If different crustal stratifications are used in the inversions, the best results are obtained for the stratification that is the closest to the true crustal structure. When we use more realistic GPS distributions, prominent spurious slip patches can be obtained. Modellers should use synthetic tests and sensitivity analyses as an initial step in the data inversion for source parameters.

Print ISSN: 0956-540X

Electronic ISSN: 1365-246X

Topics: Geosciences