Showing papers by "Braunschweig University of Technology published in 1976"
TL;DR: A simple analytic formula for the microbending loss in monomode fibres of arbitrary refractive-index profile is presented in this paper, which essentially depends on the spot size of the fundamental fibre mode only.
Abstract: A simple analytic formula for the microbending loss in monomode fibres of arbitrary refractive-index profile is presented. This loss essentially depends on the spot size of the fundamental fibre mode only. Therefore W-fibres, for example, are as sensitive to microbending as conventional cladded-core fibres.
109 citations
TL;DR: In this paper, the authors presented new experimental vapour pressures of oxygen for the temperature range from 90 K up to the critical temperature Tc = 154.581 K. This equation, which contains only five coefficients, correlates the selected data set within their experimental accuracy and gives essentially different results from previous vapour-pressure equations for oxygen.
64 citations
01 Jan 1976
TL;DR: Free living stages of sedentary organisms can be considered adaptations to enable immobile species to exploit a scattered or transient ecological niche to prospect for and identify a congenial habitat.
Abstract: Free living stages of sedentary organisms can be considered adaptations to enable immobile species to exploit a scattered or transient ecological niche. The task to prospect for and to identify a congenial habitat is consigned, as a rule, to larvae or larva-like buds, that is to those stages which actually transform into the sessile phase. This is the case even if a metagenetic life cycle has provided the species with a dominant swimming phase capable of brooding the eggs throughout development until the settling stage. Eventually, the larvae are set free and they have to find a suitable substratum themselves. But how can larvae comply with such a task? Their sensory equipment is very limited and does not qualify them to locate an appropriate habitat from a distance. This applies especially to coelenterate larvae. They depend, therefore, on a hierarchy of key or sign stimuli indicative for their adult environment. Viewed in terms of behaviour, the larva displays appetitive or searching activity which continues until the larva is presented with a specific releasing stimulus triggering fixation and metamorphosis. The effective stimulus must be derived from characteristic substrate properties which can be explored by mechanoreceptors and/or a chemical contact sense (Crisp, 1974). Recognition of an adequate substratum, therefore, depends on physical contact or, at least, on a close range approach. The word ‘close’ can be defined in this context in relation to the various forces of adhesion.
41 citations
Journal Article•
37 citations
27 citations
TL;DR: In this article, the structure of the cobalt complex with O2 bridges was analyzed and the O O distance in the μ-peroxo cation 1a is 1.465 A and the Co O-O O-Co torsion angle is 60.7°.
Abstract: An je einem Salz der beiden chemisch und strukturell in enger Beziehung zueinander stehenden zweikernigen Co(III)-Komplexkationen [(en)2Co · μ(OH, O2) · Co(en)2]3+1a und [(en)2Co · μ(OH, O2) · Co(en)2]4+1b, haben wir eine Rontgenstrukturanalyse durchgefuhrt. In beiden Fallen liegen Racemate von ΔΔ- und ΔΔ-Kation-Isomeren vor. Der O–O-Abstand und der Co–O–O–Co-Torsionswinkel in dem μ-Peroxo-Kation 1a sind 1,465 A bzw. 60,7°. Die entsprechenden Werte fur das μ-Superoxo-Kation 1b betragen 1,339 A und 22,0°.
Cobalt Complexes with O2 Bridges: The Structure of the Cations μ-Hydroxo-μ-peroxo-bis[bis(ethylenediamine) cobalt (III)]3+and μ-Hydroxo-μ-superoxo-bis [bis (ethylenediamine) cobalt (III)]4+
X-ray structure determinations of one salt of each of the two chemically and structurally closely related dinuclear cobalt cations [(en)2Co · μ(OH, O2) · Co(en)2]3+1a and [(en)2Co · μ(OH, O2) · Co(en)2]4+1b have been performed. In both cases the cations exist as racemic mixtures of ΔΔ and ΔΔ isomers. The O–O distance in the μ-peroxo cation 1a is 1.465 A and the Co–O–O–Co torsion angle is 60.7°. The corresponding values for the μ-superoxo cation 1b are 1.339 A and 22.0°.
26 citations
TL;DR: In field desorption mass spectrometry of ribodinucleoside phosphates the formation of nucleoside cyclophosphates can be used to determine the base sequence.
Abstract: In field desorption mass spectrometry of ribodinucleoside phosphates the formation of nucleoside cyclophosphates can be used to determine the base sequence.
25 citations
TL;DR: In this article, 1,2-Dichlorotetramethyldisilaries and their transformation into N,N′-Bis (organyl) octamethyltetrasiladiaza-cyclohexanes were prepared via aminolysis via equ.
Abstract: Organylaminolyse des 1,2-Dichlortetramethyldisilans fuhrt nach Rk. 3 zu den entsprechenden 1,2-Bis(organylamino)-Derivaten A 1–4. Sie liesen sich auf 3 verschiedenen Wegen (Rkk, 7, 8/9 bzw. 10/11) in die N,N′-variierten Tetrasiladiazacyclohexane B 2–5 uberfuhren. Physikalische, analytische und strukturelle Daten der neu dargestellten Verbindungen finden sich in Tab. 1–3. Das Bindungsinkrement (N)Si–Si(N) fur die Molrefraktionen MRE nach EISENLOHR wurde neu bestimmt zu 24,5, bisher 30,0.
Chemistry of Silicon-Nitrogen Compounds. CXXXI. 1,2-Bis (organylamino) - tetramethyldisilaries and their Transformation into N,N′-Bis (organyl) octamethyltetrasiladiaza-cyclohexanes
1,2-Bis(organylamino)disilanes A 1–4 were prepared via equ. 3 by aminolysis of 1,2-dichlorotetramethyldisilane and transformed by three different methods (equ. 7; 8/9 and 10/11) into the N,N′ variied tetrasiladiazacyclohexanes B 2–5. Physical, analytical and structural information can be taken from tables 1-3. The bond increments (N)SiSi(N) of the EISENLOHR molar refractions MRE were reinvestigated with 24.5 instead of 30.0.
20 citations
Journal Article•
18 citations
TL;DR: In this article, four allochthonous units with different styles of deformation are piled up above the Cherty Limestone (“Plattenkalk”), and the emplacement of the nappes is discussed.
16 citations
TL;DR: In this article, the main features of the IR and Raman spectra of several derivatives of type I (El = element of groups IVb, Vb, VIb) and of type II(El = Si, Ge, Sn, Ti, Zr) are reported.
Abstract: Die IR- und Raman-Spektren einer Reihe von Verbindungen vom Typ I (El = Element der IV., V. oder VI. Hauptgruppe) und Typ II (El = Si, Ge, Sn, Ti, Zr) werden auszugsweise mitgeteilt und hinsichtlich der Skelett-Streckschwingungen zugeordnet und ausgedeutet. Eine Variation von El wirkt sich auf nahezu alle Skelettschwingungen aus.
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The Vibrational Spectra of Mono and Spirocyclic Five-membered Ring Systems with NSiSiN Units
The main features of the i.r. and Raman spectra of several derivatives of type I (El = element of groups IVb, Vb, VIb) and of type II (El = Si, Ge, Sn, Ti, Zr) are reported. The stretching vibrations of the skeleton are assigned and discussed. Variation of El causes a shift of nearly all skeletal vibrations.
TL;DR: In this paper, a method for solving Roothaan's molecular orbital equations by means of SCF perturbation theory is presented, and an estimate of the accuracy of the third order expansion is made for the CNDO/2 approximation from a comparison of the results from direct calculations.
Abstract: A method for solving Roothaan's molecular orbital equations by means of SCF perturbation theory is presented. An estimate of the accuracy of the third order expansion is made for the CNDO/2 approximation from a comparison of the results from direct calculations. It is found that the third order theory is sufficiently accurate for quantitative studies.
TL;DR: In this article, it was proved that the theorem of H. Steinhaus remains valid, if R is replaced by certain topological measure spaces X, Y and a Hausdorff space Z and satisfies a special local (respectively global) solvability condition.
Abstract: The following result is due to H. Steinhaus [20]: “If A,B⊂R are sets of positive inner Lebesgue measure and if the function f: R x R→R is defined by f(x,y):=x+y (x,yɛR), then the interior of f(A x B) is non void”. In this note there is proved, that the theorem of H. Steinhaus remains valid, if
(1)
R is replaced by certain topological measure spaces X, Y and a Hausdorff space Z,
(2)
f is a continuous function from an open set T⊂X x Y into Z and satisfies a special local (respectively global) solvability condition in T,
(3)
A⊂X is a set of positive outer measure, B⊂Y contains a set of positive measure and A x B⊂T.
TL;DR: The attachment of a silicon atom to methylamino groups leads in the pure compounds I to VII to a HNCH coupling constant for the protons of J = 6-7 Hz.
Abstract: Die Nachbarschaft von Siliciumatomen zu einer Methylaminogruppe in den Verbindungen I bis VII fuhrt stets zu einer HNCH-Kopplung der Protonen mit J = 6–7 Hz in der reinen Substanz wie meist auch in Losung, nicht aber mehr in CH2Cl2 und CHCl3 Die einwandfreie Zuordnung der NMR-Signale von IV ergibt sich aus Abb 1 I–VII besitzen praktisch gleiche Basizitat, wie aus der gleichbleibenden Verschiebung von etwa 35 cm−1 der C–D-Streckschwingung im IR-Spektrum von CDCl3 zu erkennen ist
Chemistry of Silicon-Nitrogen Compounds CXXX NMR and IR Spectroscopic Investigations on Methylaminosilanes
The attachment of a silicon atom to methylamino groups leads in the pure compounds I to VII to a HNCH coupling constant for the protons of J = 6–7 Hz A similar effect is also observed in solution, except in CH2Cl2 and CHCl3 The correct assignment of the nmr signals for IV is shown in Fig 1 I to VII have practically the same basic properties as can be concluded from the invariable shift of the CD stretching vibration of 35 cm−1 for CDCl3
TL;DR: In this article, the microbending loss in single-mode W-fibres has been determined by calculating the coupling coefficients between the fundamental mode and the radiation modes, and it is shown that the micro bending loss is of the same order of magnitude, or even larger than, the microbending loss in comparable singlemode cladded-core fibres.
Abstract: The microbending loss in single-mode W-fibres has been determined by calculating the coupling coefficients between the fundamental mode and the radiation modes. It is shown that the microbending loss is of the same order of magnitude, or even larger than, the microbending loss in comparable single-mode cladded-core fibres.
TL;DR: A survey of possible speed-ups of matrix-multiplication by the methods due to S. Winograd and V. Straßen is given and formulas for the required additional core-memory are given.
Abstract: Diese Arbeit soll eine Ubersicht uber den moglichen Zeitgewinn geben, der durch den Einsatz der schnelleren Matrix-Multiplikationen von S. Winograd und V. Strasen erzielbar ist. Implementierungsfragen werden besprochen und der benotigte Zusatzspeicher wird ermittelt. Die Abschatzungen beruhen auf einem Rechner-Modell, welches den heutigen Rechenanlagen nachgebildet ist, und liefern daher realistische Ergebnisse.
TL;DR: In this article, the authors berichtet, die an Polyacrylamiden gelost in Wasser, Formamid, and Glykol, durchgefuhrt wurden.
Abstract: Es wird uber Messungen berichtet, die an Polyacrylamiden (Laborpraparate im BereichM=5⋅105 bis 5⋅106), gelost in Wasser, Formamid und Glykol, durchgefuhrt wurden.
TL;DR: In this paper, a charge control model of the pin diode is developed which fully accounts for the additional contact-layer storage charges, which greatly influence both the forward steady state and the turnoff transient (switching time and transition-loss).
Abstract: A charge-control model of the pin diode is developed which fully accounts for the additional contact-layer storage charges. This part of the storage charge is shown to greatly influence both the forward steady state and the turn-off transient (switching time and transition-loss). Needing limited mathematical efforts, the model seems well suited for analysis of complicated microwave networks with pin diodes, such as phase shifters, limiters, and frequency converters. As is demonstrated by numerical results, an optimal i-layer width may exist for certain applications.
01 Jan 1976
TL;DR: In this article, a mesa-shaped pin-photodiodes with high internal quantum efficiency at a lifetime below 100 ps using a grated highly reflecting back contact and total reflection at the top was presented.
Abstract: Thin-silicon-film mesa-shaped pin-photodiodes are presented, which exhibit high internal quantum efficiency at risetimes below 100 ps using a grated highly reflecting back contact and total reflection at the top. Theoretical and typical experimental data are given. Transparent photodiodes fabricated in a similar way are introduced, which can be inserted into an optical transmission path to take out a fraction of power without the need of an optical coupler.
TL;DR: A 2,B 2 and C 2 of the drug mebrophenhydramine from the class of benzhydryl ethers were synthesized for the first time by the steps shown in scheme 1, and they and their precursors I-III were characterized by their physical and chemical properties, and their structures confirmed by NMR, mass and infrared spectroscopy.
Abstract: Sila-analoguesA 2,B 2 andC 2 of the drug mebrophenhydramine from the class of benzhydryl ethers were synthesized for the first time by the steps shown in scheme 1, and they and their precursors I–III were characterized by their physical (Table 1) and chemical properties, and their structures confirmed by NMR, mass and infrared spectroscopy (Tables 3–5). The histaminolytic and anticholinergic effects ofA 2 andC 2 were investigated and compared with some structure-activity relationships of analogue carbon compounds.
TL;DR: In this paper, a new Hypothese for the Verdeckung von Reizen in verschiedenen Sinnesmodalitaten with einfacher Struktur is presented, in which the Reprasentation eines Reizes im sensorischen Register wird durch die Merkmalsanalyse des vorangegangenen Reizes kaum behindert, but dessen Ubertragung aus dem analysierenden System in das Kurzzeitgedachtnis eine bestimmte Zeit verzogert.
Abstract: Fur die Erklarung der Verdeckung von Reizen in verschiedenen Sinnesmodalitaten mit einfacher Struktur wurden in der Literature bisher im wesentlichen zwei verschiedene Erklarungskonzepte diskutiert: Die Summationshypotheses behauptet, das die Eindrucke von schnell aufeinanderfolgenden Reizen sich zu einer Gesamtreprasentation uberlagern, aus der die Einzelreize erschwert herauszuanalysieren sind, die Unterbrechungshypothese dagegen nimmt an, das die Verdeckung auf eine Storung der Verarbeitung des einen Reizes durch die kurzzeitig folgende Darbietung eines weiteren Reizes zuruckgeht. Zur Erklarung der gegenseitigen Verdeckung von taktil dargebotenen Buchstaben sind beide Hypothesen ungeeignet, weil sie die unterschiedliche Beeintrachtigung von Form- und Positionserkennung der Buchstaben nicht erfassen konnen. Deshalb wurde eine neue Hypothese aufgestellt: Die Reprasentation eines Reizes im sensorischen Register wird durch die Merkmalsanalyse des vorangegangenen Reizes kaum behindert, aber dessen Ubertragung aus dem analysierenden System in das Kurzzeitgedachtnis eine bestimmte Zeit verzogert. Diese Verzogerungshypothese wurde mit einem Experiment uberpruft, in dem 3 Vpn je etwa 12 Versuchsstunden lang die Erkennung von Buchstabenpaaren ubten. Da die Diskrimination zwischen den Buchstaben bei taktiler Darbietung sehr viel schwieriger als bei visueller ist, wurden nur 5 Buchstaben im Experiment verwendet. Die Ergebnisse des Experiments werden durch ein mathematisches Modell beschrieben. Bezuglich der numerischen Werte der freien Parameter machen die 3 Hypothesen unterschiedliche Vorhersagen. Die Parameterschatzung ergab eine gute Ubereinstimmung des Modells mit den Daten und zeigte eine Uberlegenheit des Konzeptes Verzogerung fur die Erklarung der gegenseitigen Verdeckung taktil dargebotener Buchstaben.
01 Jan 1976
TL;DR: In this paper, it was shown that the exploded wire gap could withstand voltages for 50 ms with peak values of 1.3 kV/cm wire length, at currents of 500 A and a current flow of 1 ms voltages of 140 kV could be generated with copper wires.
Abstract: Usually the application of exploding wires or foils for current breaking in magnetic energy storage systems is only efficient if the time of current flow through the wire or foil can be limited to around 100/us. A remarkable improvement in voltage generation by slowly explo-ding wires can be achieved by a special containment of the wire. Thus voltages of a few kV per cm wire length can be produced even after some ms of current flow through the wire. The properties of such wires allow a parallel operation with commercially available a. c. breakers with mechanically moved contacts. After a description of such a breaking unit results of tests with “tamped wires” are discussed. At currents of 500 A and a current flow of 1 ms voltages of 140 kV could be generated with copper wires, 95 cm long. Recovery behaviour tests with mainly resistive loads show, that the exploded wire gap could withstand voltages for 50 ms with peak values of 1.3 kV/cm wire length. The voltage steepness generated by the exploded wires depends on the time of current flow through the wire, the wire length, and its containment.
TL;DR: A parametric representation naturally connected with spline-conditions allows moreover a most simple and clear correction of splines and bisplines.
Abstract: Die bekannte Darstellung von Kurven und Flachen nach Pierre Bezier wird auf kubische und bikubische Splines angewendet. In dieser Darstellung sind die Spline-Bedingungen besonders anschaulich und daher leicht zu handhaben. Eine mit den Spline-Bedingungen auf naturliche Weise verbundene Parameterdarstellung gestattet auserdem eine hochst einfache und ubersichtliche Korrektur der Splines und Bisplines.
TL;DR: The conformation of their structure was possible by elemental analysis and by n.m.r., mass, i.e., and Raman spectra as mentioned in this paper, and they succeeded in preparing the four novel spirosilazane skeletons E, F, G, and H of the composition given in the title.
Abstract: Es gelang, die vier neuen Spirosilazangeruste E, F, G und H der im Titel angegebenen Gerusttypen in den jeweils permethylierten Vertretern uber die Reaktionen 1–5 zu synthetisieren und in ihren chemischen und physikalischen Eigenschaften zu charakterisieren. Die Strukturaufklarung erfolgte uber Elementaranalysen, 1H-NMR-, Massen-, IR- und Raman-Spektren.
Novel Inorganic Ring Systems. XXII. Novel Spirosilazanes of the Si5N4, Si5N5, Si5N4O, and Si7N8 Skeleton
We succeeded in preparing the four novel spirosilazane skeletons E, F, G, and H of the composition given in the title. The permethylated compounds of the mentioned systems have been characterized in their chemical and physical properties. The conformation of their structure was possible by elemental analysis and by n.m.r., mass, i.r., and Raman spectra.
TL;DR: The Tropfengrosenverteilung der dispersen Phase nicht bekannt ist as discussed by the authors, and the Auslegung von Vorrichtungen zum Trennen nicht mischbarer Flussigkeiten bereitet oft deshalb Schwierigkeitsen, weil the TropfENGrosen verteilerung of the dispersen phase nicht ist.
Abstract: Die Auslegung von Vorrichtungen zum Trennen nicht mischbarer Flussigkeiten bereitet oft deshalb Schwierigkeiten, weil die Tropfengrosenverteilung der dispersen Phase nicht bekannt ist. Sie hangt ganz wesentlich von den hydrodynamischen Bedingungen im Stoffaustauschapparat und vom Koaleszenzverhalten der Flussigkeiten ab, das hauptsachlich von Stoffgrosen beeinflust wird. Vor der eigentlichen Trennung mussen stabile Emulsionen haufig durch geeignete Masnahmen gebrochen oder Dispersionen aus sehr kleinen Tropfchen mit mechanischen Vorrichtungen in gut trennbare Dispersionen uberfuhrt werden. Als Koaleszer wirken porose Materialien, Drahtgestricke sowie Fullkorper, die vom Flussigkeitsgemisch durchstromt werden. Auch Elektrokoaleszer lassen sich mit Erfolg einsetzen. Fur die eigentliche Trennung der beiden Phasen werden u. a. Absetzbehalter, Zyklone und Zentrifugen eingesetzt. Die Wirkungsweise und die Einsatzmoglichkeiten von Koaleszern und Abscheidern werden beschrieben und die bisher vorliegenden Berechnungsgrundlagen fur ihre Auslegung mitgeteilt. Anhand von Beispielen wird gezeigt, wie man bei der Auswahl und Auslegung derartiger Apparate vorgeht.
TL;DR: In this article, a new approximation method for the n -fermion problem is developed and tested within the exactly solvable model of Lipkin, Meshkov and Glick, which is compared with the exact solutions and RPA.
TL;DR: In this article, the eccentric anomaly is used as independent variable in such a way that the time transformation is given by a generalized Lagrange formalism, and the control terms in the equations of motion obtained by this modified Lagrangian give immediately a completely Lyapunov stable set of differential equations.
Abstract: In order to reduce the error growth during a numerical integration, a method for stabilizing the differential equations of Keplerian motion is offered. It is characterized by the use of the eccentric anomaly as independent variable in such a way that the time transformation is given by a generalized Lagrange formalism. The control terms in the equations of motion obtained by this modified Lagrangian give immediately a completely Lyapunov-stable set of differential equations. The equation of time integration is modified by a control term which leads to an integral which defined the time element for the perturbed Keplerian motion.
TL;DR: The derivatives of the 1,2,4-Trisila-3,5-diaza-cyclopentane ring system were obtained by reaction of 1, 2-bis(alkylamino)disilanes (A1, A2) with dihalosilanes as mentioned in this paper.
Abstract: Durch Reaktion von Dihalogensilanen mit 1,2-Bis(alkylamino)disilanen (A1, A2) konnten die Derivate B1–B6 des Titelringsystems und durch deren weitere Umsetzung die Verbindungen B7–B9 erstmalig dargestellt werden (Schema 1). B2 zeichnet sich durch eine ungewohnliche Stabilitat gegenuber neutralen wasrigen Losungen aus.
Chemistry of Silicon-Nitrogen Compounds. CXXXII. Derivatives of the 1,2,4-Trisila-3,5-diaza-cyclopentane Ring System
The derivatives B1–B6 of the title ring system could be prepared for the first time by reaction of 1,2-bis(alkylamino)disilanes (A1, A2) with dihalosilanes (Scheme 1). They were transformed by additional reactions with methanol or amines into B7–B9. The Cl2Si derivative B2 is characterized by an unusual stability against aqueous solutions.
TL;DR: The ring systems of Arsa- and Stibia-disila-diaza-cyclopentane are described in this article, where AsCl units in B 1-3 can be substituted leading to B 4-6.
Abstract: 1.2-Bis(alkylamino)disilane setzen sich mit AsCl3 bzw. SbCl3 zu den neuen funfgliedrigen Ringsystemen B bzw. C um. AsCl-Einheiten in B 1–3 lassen sich zu B 4–6 substituieren. Die Eigenschaften der neuen Verbindungen werden beschrieben. Ihre Strukturbestimmung erfolgte uber Elementaranalysen, Massen-, Protonenresonanz- und Infrarot-Spektren.
Novel Inorganic Ring Systems. XXVII. The Ring Systems of Arsa- and Stibia-disila-diaza-cyclopentane
1.2-Bis(alkylamino)disilanes react with AsCl3 and SbCl3 respectively to give the novel five membered ring systems B and C. AsCl units in B 1–3 can be substituted leading to B 4–6. The properties of the new compounds are described. Their structure was confirmed by elemental analysis, mass, proton n.m.r., and infrared spectroscopy.