Hindered motions in a ketonea-urea inclusion compound. An ESR and ENDOR study

We have studied by ESR and ENDOR spectroscopy the free radicals produced in γ-irradiated inclusion compound formed between the ketone 10-nonadecanone and urea. Only one type of long lived radical is formed by the removal of an α-proton from the ketone. The hyperfine (hf) coupling constants of the α- and β-protons of the radicals have been measured by ESR at different temperatures in the range 110–292 K and at different orientations of the crystals. The hf coupling of the γ-protons of the radical and of the urea protons have been studied by ENDOR. The temperature and angular dependences of the coupling constants have been analyzed in terms of the internal and overall motions of the radical inside the hexagonal channels formed by the urea molecules. It has been found that the radical cannot perform complete reorientations around the long molecular axis, but it undergoes restricted rotational diffusion. This process is explained by assuming a coupling between the rotational and translational degrees of freedom of the radical inside the urea channels.     

Tuning high-power laser diodes with as much as 0.38 W of power and M(2) = 1.2 over a range of 32 nm with 3-GHz bandwidth

Gain-guided diode lasers usually have emission wavelengths determined by the manufacturing process, with typically 0.5-1-nm bandwidth. Furthermore, their beam quality is rather poor. We show that external cavities allow for tunable narrow-bandwidth operation of gain-guided diode lasers. At the same time the beam quality is drastically improved; almost diffraction-limited light of more than 200 mW has been achieved over the whole tuning range from 910 to 942 nm with narrow bandwidth.     

Gasdynamische Untersuchung des Jouleschen Überströmversuches

Zusammenfassung Es wird die zeitabhängige Strömung beim Ausgleichsvorgang zwischen zwei endlichen Behältern untersucht. Den Überlegungen wird eine eindimensionale, reibungsfreie und quasistationäre Strömung zugrunde gelegt. Während bei überkritischer Strömung eine analytische Lösung möglich ist, wird das Problem bei unterkritischer Strömung numerisch gelöst.Dem Druckausgleich zwischen den beiden Behältern folgt ein isobarer Wärme- und Massenaustausch, bis sich das thermodynamische Gleichgewicht eingestellt hat.

---

Gasdynamical investigation of Joule's overflow experiment

The time-dependent flow of an exchange process between two big insulated tanks is considered. The problem is treated on the basis of a one-dimensional, inviscid and quasi-steady flow. An analytical solution is obtained for supercritical flow, while for subcritical flow the problem is solved numerically.After the pressure-equilibrium between the two-tanks an isobar heat and mass exchange follows, until the thermodynamic equilibrium is reached.

---

Formelzeichen a Schallgechwindigkeit - A engster Querschnitt - c Geschwindigkeit - c _p spezifische Wärme bei konstantem Druck - c _v spezifische Wärme bei konstantem Volumen - e innere Energie - i Enthalpie - m Masse - M Machzahl - p Druck - spezielle Gaskonstante - s Stromlinie, spezifische Entropie - t dimensionsbehaftete Zeit - T Temperatur - V Volumen - Konstante - Abkürzung - Volumenverhältnis - Verhältnis der spezifischen Wärmen - Dichte - dimensionslose Zeit Indizes 0 Zustand zur Zeitt=0 - 1 Zustand im Überdruckbehälter - 2 Zustand im Überströmbehälter - * Zustand im engsten Querschnitt - K kritisch - M Zustand bei Druckausgleich - E Endzustand bei Temperaturausgleich Herrn Prof. Dr. B. Schmidt in Dankbarkeit zum 60. Geburtstag gewidmet     

An analysis on forced convection in a channel filled with a Brinkman-Darcy porous medium: Exact and approximate solutions

An analysis was made to investigate non-Darcian fully developed flow and heat transfer in a porous channel bounded by two parallel walls subjected to uniform heat flux. The Brinkmanextended Darcy model was employed to study the effect of the boundary viscous frictional drag on hydrodynamic and heat transfer characteristics. An exact expression has been derived for the Nusselt number under the uniform wall heat flux condition. Approximate results were also obtained by exploiting a momentum integral relation and an auxiliary relation implicit in the Brinkmanextended Darcy model. Excellent agreement was confirmed between the approximate and exact solutions even in details of velocity and temperature profiles.     

Development of high resolution resonance ionization mass spectrometry for trace analysis of 93mNb

⁹³Nb(n, n′)^93mNb reaction allows retrospective estimation of integrated fast neutron dose in nuclear reactor. We proposed isomer-selective trace analysis of ^93mNb by Resonance Ionization Mass Spectrometry (RIMS) combined with a gas-jet atomic source and an injection locked Ti:Sapphire laser system operated at several kHz. Resonant ionization spectroscopy of Nb in gas-jet using Ti:Sapphire laser was demonstrated.     

Characterization of an optical multilayer hydrophone with constant frequency response in the range from 1 to 75 MHz

The performance of an optical multilayer hydrophone for ultrasound measurements is investigated both in theoretical terms and experimentally. The optical measurement system comprises a thin high-finesse dielectric interference filter structure that is deposited onto a plane glass plate. An incident acoustic pressure wave deforms the layer system, and the induced variation of the optical reflectance is determined. Applying the concept of an optical off-axis detection scheme offers good sensitivity and a simple and low-cost setup. A primary interferometric calibration technique is applied to experimentally determine the pressure-voltage transfer function in the range from 1 to 75 MHz. Within the measurement uncertainty a constant transfer factor is obtained for the whole frequency range. Measurements of broadband ultrasound pulses are influenced neither by acoustic resonances of the very thin sensing element nor by diffraction phenomena that are known to cause waveform distortions in small probe hydrophone measurements. High temporal and spatial resolution is combined with high durability of the probe, which is why the optical multilayer hydrophone is well suited for use as a reference for secondary hydrophone calibration.     

Ein LIFO Branch and Bound Verfahren zur optimalen Altstoffbehälterallokation

Zusammenfassung In diesem Artikel wird auf ein Problem eingegangen, das sich im Rahmen einer abfallwirtschaftlichen Studie ergab, in der die Durchführbarkeit von Altstoffsammlungen im dichtverbauten Siedlungsgebiet untersucht wurde. Als wichtige Teilaufgabe war dabei eine platzminimale Altstoffbehälterkombination für jede Altstoffart und für jedes Haus des untersuchten Sammelgebietes zu ermitteln, wobei unter anderem die Zugänglichkeit des Behälterraumes für die Sammelmannschaft und dessen topographische Gegebenheiten zu beachten waren. Zur Lösung dieser Aufgabe, deren Formalisierung auf ein ganzzahliges LP führte, wurde ein LIFO Branch and Bound Verfahren entwickelt. Dieses wird an Hand der wesentlichen Bestandteile eines jeden Algorithmus vom Branch and Bound Typ: der Branching Strategie, der Bounding Strategie und der Search Strategie dargestellt. Der Algorithmus wurde in PL/I programmiert und hat seine Leistungsfähigkeit in zahlreichen Programmläufen unter Beweis gestellt.

---

Summary In this article a problem is treated which rose in the course of a research into the suitability for reconditioning used materials. This study analyzes the feasibility of scrap collection in densily populated, urban areas. One major aspect was to provide for a space saving combination of containers for every kind of scrap and for each house of the test area, bearing in mind the constraints given by the topographical conditions of the container room and its accessibility to the collection personnel. The formulation of this problem led to an all integer program. To solve this program a LIFO branch and bound algorithm was developed. The algorithm is presented by discussing its branching strategy, its bounding strategy and its search strategy, which constitute the essential parts of each procedure of the branch and bound type. The algorithm was programmed in PL/I and proved its efficiency in numerous runs.

     

Conformal field algebras with quantum symmetry from the theory of superselection sectors

According to the theory of superselection sectors of Doplicher, Haag, and Roberts, field operators which make transitions between different superselection sectors—i.e. different irreducible representations of the observable algebra—are to be constructed by adjoining localized endomorphisms to the algebra of local observables. We find the relevant endomorphisms of the chiral algebra of observables in the minimal conformal model with central chargec=1/2 (Ising model). We show by explicit and elementary construction how they determine a representation of the braid groupB which is associated with a Temperley-Lieb-Jones algebra. We recover fusion rules, and compute the quantum dimensions of the superselection sectors. We exhibit a field algebra which is quantum group covariant and acts in the Hilbert space of physical states. It obeys local braid relations in an appropriate weak sense.