bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoluminescence of a Pseudomorphic Si1−yCy/Si MQW Structure under Pressure
Authors: Liu Z. X. , Goñi A. R. , Brunner K. , Eberl K. , Syassen K. 
Published: July 2007

AbstractWe have measured photoluminescence (PL) spectra of a pseudomorphic Si1−yCy/Si (y = 0.0045) multiple quantum well (MQW) structure under hydrostatic pressure (0 to 8 GPa) and at low temperatures (10 to 70 K). The MQW‐related emission at energies below the Si band gap consists of bound and free exciton zere‐phonon lines and related Si‐Si TO phonon replicas. All MQW‐related PL peaks shift to lower energy with increasing pressure. The dependence of PL‐peak intensities and energies on excitation power density, temperature, and pressure are consistent with a type‐I band alignment throughout the pressure range investigated. Furthermore, the total band offset and the activation energies involved in the decay of the free and bound exciton emission show only a very small change with pressure.
Phase Diagram of InSb at High Pressures and Temperatures
Authors: Mezouar M. , Besson J. M. , Syfosse G. , Itié J. P. , Häusermann D. , Hanfland M. 
Published: July 2007

AbstractThe phase diagram of InSb has been studied by energy‐dispersive X‐ray diffraction with synchrotron radiation at pressures up to 8 GPa and temperatures up to 800 K in a Paris‐Edinburgh cell. At room temperature InSb transforms above 2.5 GPa from the zincblende structure to a sixfoldcoordinated orthorhombic structure with Pmm2 (Cmcm) space group (InSb IV). In previous studies it was proposed that another orthorhombic structure with Immm space group (InSb II) existed at higher temperature. We show that this phase is actually metastable, the InSb IV one being the stable form. The low‐pressure melting curve and the triple point position are confirmed and the high pressure melting curve as well as the phase boundaries between the high pressure phases have been determined precisely. A new pressure‐temperature phase diagram for InSb is established which eliminates contradictions in the previously proposed diagrams of its solid phases.
Nature of the Forbidden Gap in Insulating ABxB′1 − xO3 Crystals
Authors: Raevskii I. P. , Prosandeev S. A. , Osipenko I. A. 
Published: July 2007

AbstractThe electronic structure of a wide variety of ternary ABxB′1−xO3 perovskitetype insulating oxides in ordered phases has been analysed using the tight‐binding method. The cases considered me those in which A is divalent and the tetravalent B in ABO3 is replaced by a mixture with the same total number of valence electrons. Widths of the forbidden gaps obtained prove to be much larger than in perovskites of the ABO3 type with the same B ion. The results of the experimental electric conductivity and photoconductivity measurements are in good agreement with the computation.
Monoclinic Spin Hamiltonian Analysis of EPR Spectra of Mn2+ in BiVO4 Single Crystals
Authors: Yeom T. H. , Rudowicz C. , Choh S. H. , McGavin D. G. 
Published: July 2007

AbstractX‐band EPR spectra of Mn2+ in ferroelastic BiVO4 single crystals at room temperature taken in three orthogonal planes are analyzed using a twestage least‐squares fitting procedure. The absence of site splitting from the spectra shows unequivocally that Mn2+ lies on a site with two‐fold rotation symmetry, whose two fold axis is parallel to the monoclinic crystal axis. The low symmetry effects arising from the monoclinic site symmetry are evidenced by the observed coincidence of the extrema for transitions between different Zeeman levels along the monoclinic axis, and by the 180° rotational symmetry in the monoclinic plane and a small noncoincidence of the turning points in this plane. In the first stage, the spectra are fitted using the monoclinic form of the electronic Zeeman and fine structure terms (of second and fourth degree) appropriate for the crystallographically determined orientation of the monoclinic axis. In the second stage, fitting of the nuclear hyperfine tensor (A) and the nuclear quadrupole tensor (P) is carried out with fixed values of the electronic Zeeman tensor (g) and fine structure terms, i.e. the tensor (D) and the fourth‐degree terms, as obtained in the first stage. The principal axes of g, D, A, and P are found to be non‐coincident in the monoclinic plane, as would be generally expected for a monoclinic site.
X‐Ray and Bulk Magnetic Properties of the NiZn Ferrite System
Authors: Kakatkar S. V. , Kakatkar S. S. , Patil R. S. , Sankpal A. M. , Suryavanshi S. S. , Bhosale D. N. , Sawant S. R. 
Published: July 2007

AbstractCompositions having the general formula Ni1−xZnxFe2O4 with x = 0.30, 0.35, 0.40, 0.45 have been sintered at 1100, 1150, 1200, and 1240°C to attain different microstructures. The grain size D for a particular composition increases linearly with increasing sintering temperature. The lattice parameter α and magnetization Ms are seen to be invariant with the change in sintering temperature. The coercive force Hc and the remanent ratio R = Mr/Ms are seen to depend on the sintering temperature and hence on D. α and M, are found to increase with the increase of the Zn content, whereas Hc values show a decreasing trend with the Zn content. The compositional, thermal, and microstructural variation of hysteresis parameters like Ms, Hc, and R = Mr/Ms reveal that magnetic grains in the compositions investigated are of multi‐domain type. This result is supported by ac susceptibility data.
A 90 day repeated oral toxicity study on plantamajoside concentrate from Plantago asiatica
Authors: Park Byung‐Gyu , Lee Hyun‐Sun , Jung Sung‐Hoon , Hong Chung‐Oui , Won Hye‐Jin , Park Ho‐Young , Ryu Yung‐Sun , Lee Sung‐Joon , Kim Kyoung‐Heon , Park Kuen‐Woo , Lee Kwang‐Won 
Published: July 2007

AbstractPlantago asiatica is distributed widely in East Asia. Since ancient times it has been used as a diuretic to treat acute urinary infections, and as an antiinflammatory, antiasthmatic, antioxidant, antibacterial, antihyperlipidemic and antihepatitis drug. The major compound, plantamajoside from P. asiatica, which is used as a marker compound in chemotaxonomic studies, was reported to have antibacterial activity, inhibition activity against cAMP phosphodiesterase and 5‐lipoxygenase and antioxidant activity. However, there are no reports on the safety of plantamajoside. This study assessed the toxic effects of plantamajoside concentrate (PC), the purity of which was above 80%, in rats following administration at dose levels of 0, 500, 1000 and 2000 mg/kg body weight/day for 13 weeks, as recommended by the OECD guidelines. The results showed that there were no differences in body weight, food intake, water consumption, relative organ weight or the hematological and serum biochemical values among the different dosage groups. No death or abnormal clinical signs were observed during the experimental period. Therefore, the results suggested that no observed adverse effect level (NOAEL) of the PC in rats after oral administration is considered to be greater than 2000 mg/kg in rats under the conditions employed in this study. Copyright © 2007 John Wiley & Sons, Ltd.
Robust control of a two‐axis, magnetic suspension, flexible‐beam system based on H∞ optimization theory
Authors: Zhou Tong , Fujita Masayuki , Matsumura Fumio 
Published: July 2007

AbstractThis paper deals with how to use H∞ optimization theory for the controller design of a two‐axis magnetic suspension, flexible‐beam system, which is a simplified model for a flexible magnetic bearing system. Both simulation and experimental results show that the designed system not only has good performance in robustness to the plant's parametric uncertainty and the unmodelled dynamics in the beam's vibration modes, mode shapes, etc., but also has good performance in response characteristics.
Flight controller design for uncertain and nonlinear plants with pilot compensation
Authors: Kobylarz T. , Horowitz I. M. , Houpis C. H. 
Published: July 2007

AbstractNonlinear quantitative feedback theory (QFT) is used to design a flight control system for the nonlinear model of the YF‐16 aircraft (A/C) with C* as the controlled output. The resulting closed loop stability augmentation system (SAS), Pe(S), becomes part of the outer loop containing the pilot. The Neal‐Smith pilot model for a compensatory tracking task is used to develop a technique which allows the designer to synthesize compensation in the outer loop, which includes a free compensator Fp(S). The latter is chosen to minimize pilot workload, increase system bandwidth, and improve handling qualities ratings as per the Neal–Smith criteria, for the tracking task. The available pilot compensation abilities are then available for further increasing of system bandwidth to improve overall capabilities. This approach can be used at the early stages of flight control design, thus saving time and money over the current practice. Simulations in the time and frequency domains demonstrate that the desired performance is attained.
Robust output feedback stabilization of uncertain dynamic systems with bounded controllers
Authors: Hui Stefen , Żak Stanislaw H. 
Published: July 2007

AbstractWe propose a new class of infinitely many bounded output feedback controllers for uncertain dynamic systems with bounded uncertainties. No statistical information about the uncertainties is assumed. A variable structure systems approach is employed in the synthesis of the proposed output feedback controllers. The role of the system zeros in the output feedback stabilization using the variable structure approach is discussed. We show that the proposed controllers guarantee the practical stability of the closed‐loop system and give estimates of the regions of practical stability.
H∞ controller design for boilers
Authors: Pellegrinetti Gordon , Bentsman Joseph 
Published: July 2007

AbstractThis paper examines the ability of the H∞ design methodology to provide a solution to a gas‐ or oil‐fired boiler control problem, and addresses the nontrivial application issues of the H∞ design. The H∞ methodology is applied to an experimentally verified heating‐cogeneration boiler model which exhibits nonlinearities, instability, time delays, non‐minimum phase behaviour, and coloured noise disturbances with sensor noise in the frequency range of the significant plant dynamics. The design shows that, to satisfy performance criteria, a high order controller is needed. The paper also demonstrates a trade‐off between the reduction of controller order and the loss of controller performance.
Robust stability of large‐scale systems which contain time‐invariant lur'e‐type uncertainties in subsystems and norm‐bounded uncertainties in interconnections
Authors: Saeki Masami , Araki Mituhiko 
Published: July 2007

AbstractIn this paper a new frequency‐domain condition for the robust stability of a class of large‐scale systems is derived. It is assumed that each subsystem contains one time‐invariant nonlinearity satisfying a sector condition, and that the interconnecting functions are linearly bounded by the norms of the scalar outputs of subsystems. In deriving the above such Lur'e‐type Lyapunov functions of subsystems are constructed so that their weighted sum is a Lyapunov function of the overall system. This condition is potential to give a sharper result than the circle‐condition‐type result which was obtained previously. Furthermore, a method to estimate the domain of attraction using the above Lyapunov function is also given when the sector condition is satisfied only locally.
Bedeutung der Vakuumtechnik in der Metallpulver‐Technologie
Authors: Hohmann Michael , Ertl Manfred 
Published: July 2007

AbstractPowder‐Technology has developed into a significant and still increasing market. There is a demand for high quality meaning highest purity and spherical particle shape of the powder. In order to reach this aim metal alloys are melted under vacuum and atomized with intertgas. To improve the chemical purity the produced powder is treated under vacuum for instance by the static or dynamic degassing process.
Vakuumgerechte Werkstoffe und Verbindungstechnik
Authors: Mühlhoff Martin 
Published: July 2007

AbstractDetachable connections are used in cases where the operating time is not too long, or the arrangement of the vacuum equipment is required to be variable. Using detachable connections also allows access to the inner section of the vacuum equipment (for the purpose of service, maintenance, insertion of samples, etc.). Valves and vibration dampers e.g. are mainly flanged‐on.In general, these connections are more expensive than nondetachable ones (welding, soldering, melting, glueing) and provide almost the same high level of reliability of He‐tight, fittings, as far as leakages are concerned.
Zur Entwicklung der Oberflächenphysik
Authors: Jahrreiss Heribert 
Published: July 2007

AbstractWith special emphasis on the crucial influence of vacuum physics and its techniques, a survey of the development of solid surface physics from its rudimentary beginnings in the early 1960s to its present state is given. Research aims and basic methods, as well as shifts in the areas of interest, are treated in chronological order. Comparing the development of surface physics with that of older fields of physics, the question of predicting its future development is then posed.
Strahlungsofen für Kurzzeitglühungen — Aufbau, Funktionsweise und Testuntersuchungen an amorphem Fe40Ni40B20
Authors: Rank C. , Horváth J. , Werner M. , Frank W. 
Published: July 2007

AbstractA radiation furnace for rapidthermal‐annealing experiments is introduced, in which infrared lamps serve as heat sources. It can be regulated fast enough in order to produce temperature profiles which involve temperature variations within the order of seconds. The furnace was tested in self‐diffusion studies of 59Fe in amorphous Fe40Ni40B20. It was found that the Fe self‐diffusion coefficient obeys an Arrhenius law even at temperatures which are too high to be realized in a conventional furnace without the onset of crystallization.
Physikalische Grundlagen des Wärmeleitungs‐Vakuummeters
Authors: Ruschitzka M. , Jitschin W. 
Published: July 2007

AbstractIn the common design of a thermal conductivity vacuum gauge according to Pirani, a thin wire is heated by an electric current and the heat loss from the wire by the heat transfer of the surrounding gas is used to derive the gas pressure. Other mechanisms of heat loss are the thermal conductivity of the wire, which transports heat to its cold ends, and the thermal radiation. In the present paper the various mechanisms of heat loss in an axially symmetric setup are investigated in detail and described by analytical formulae. Operation of the sensor by a regulated power supply allows to keep the electrical resistance of the wire and thus the mean wire temperature constant. However, changes in gas pressure affect the temperature profile along the wire and, concomitantly, the heat transfer by the wire towards its ends and the loss by thermal radiation. Experimental data of the heating power vs. pressure obtained with nitrogen and hydrogen in a typical setup are presented and compared with calculated values.
Industrielle Gastrenntechnik mittels selektiver Membranen
Authors: Herbst Martin 
Published: July 2007

AbstractUsing membrane processes at plant engineering is an operation stage especially for a high efficient separation and recovery of organic solvent vapors.The operation of selective gas permeation in membrane modules is very flexible, so there are a lot of variations to create plants with integrated membrane stages for many different applications.The possibility to design compact and modular structured plants opens membrane process technology various applications and operative ranges. The application examples of existing plants show competent solutions of exhaust gas cleaning.
Vakuum‐Befüllverfahren beim Automobil
Authors: Nikutta Karl‐Heinz 
Published: July 2007

AbstractThe use of vacuum or vacuum pumps can be found in almost every branch of manufacturing.This is also true for the automobile industry, where the employment of vacuum as a positive solution for the problems associated with the correct and precise filling of the various fluid systems, without having any adverse effect on the environment or operating personnel.In addition to this, the use of vacuum as a technical process in the fluid filling procedure has had a marked improvement in the vehicles safety.
Teilchenstrahlinduzierte Prozesse an dielektrischen Oberflächen
Authors: Rupertus V. , Rothhaar U. , Köpfer P. , Lorenz A. , Oechsner H. 
Published: July 2007

AbstractThe possibilities for surface and depth profile analysis of dielectric samples with partially modified electron and mass spectrometric methods are described. The respective techniques have been employed for the quantitative characterization of electron and ion beam induced stoichiometry effects at glass surfaces.
Trockenlaufende Vakuumpumpen
Authors: Lamprecht Robert 
Published: July 2007

AbstractThe demand for dry running vacuum‐pumps from industry, research and development is increased steadily over the last years. Specially the fact of not having oil or pump sealing fluids in the swept volume is important for many sensitive applications in semiconductor and chemical industry. The article describes the most common construction principles which are used frequently. The question why drypumps is discussed as well as the diaphragm pump, piston pump, dry rotary vane pump, roots pump and claw and claw/roots combinations with their advantages and disadvantages. The very new scroll pump gives a new way on dry pumping in the future.
Ein plasmagestütztes Hochfrequenzverfahren zum niederenergetischen Ionenbeschuß von Isolatorwerkstoffen, insbesondere von Gläsern
Authors: Martin D. , Oechsner H. 
Published: July 2007

AbstractA novel plasma based radio frequency method for low energy charge compensated ion bombardment of dielectric surfaces is described. As a practical example, this technique is applied for a controlled removal of undefined leached surface layers on glass samples.
Konstruktion und Eigenschaften von turbinenartigen Hochvakuumpumpen
Authors: Hablanian M. H. 
Published: July 2007

AbstractTurbomolekularpumpen sind im wesentlichen Axialstrom‐Kompressoren, die zum Pumpen verdünnter Gase ausgelegt ind. Die ursprünglichen Entwickler übernahmen mehr oder weniger die herkömmlichen Stufenanordnungen von Axialstrom‐Kompressoren, wobei die Molekül‐Trajektorien zwischen den abwechselnd rotierenden und stehenden Schaufelblattreihen durch mathematische Modellrechnungen untersucht wurden. Moderne Entwicklungen sind Kombinations‐ und Hybrid‐Anordnungen, die aus Turbomolekular‐ und Turbokinetik‐Stufen im gleichen Gehäuse und auf derselben Achse montiert bestehen. Diese neuen Pumpen erreichen viel höhere (10 bis 100fach) Kompressionsverhältnisse, wodurch höhere Auslaßdrücke und der Einsatz von ölfreien Vorpumpen möglich werden.Derzeit werden vier Typen von Turbinenpumpen industriell gefertigt: mehrstufige Axialstrom‐Turbomolekularpumpen, Molekularkinetikpumpen (üblicherweise vom Holweck Typ), Hybridpumpen mit modifizierten Stufen am Auslaß aber gleicher Anzahl von Rotoren sowie Kombinationspumpen, die axiale Stufen mit zusätzlichen Kinetikpumpen im gleichen Gehäuse vereinigen. Turbinenartige Hochvakuumpumpen erlauben – im Gegensatz zu Dampfstrahlpumpen (Diffusionspumpen) und Kryopumpen – relativ einfache konstruktive Lösungen zur Erhöhung des Ausstoßdruckes, wobei selbst ein direkter Ausstoß in die Atmosphäre möglich ist.
Das Drehscheiben‐Vakuummeter als primäres Totaldruckmeßgerät im Hochvakuum
Authors: Chew A. D. , Chambers A. , Pert G. J. , Troup A. P. 
Published: July 2007

AbstractEin primäres Vakuummeter wurde entwickelt, das das Phänomen der Gasreibung zwischen zwei koaxialen Scheiben ausnutzt. Das Gerät besteht aus einer Siliziumscheibe mit 92 mm Durchmesser, die von einem kalibrierten Torsionsfaden über einer Rotorscheibe von gleicher Größe gehalten wird. Diese dreht sich mit Drehzahlen bis zu 51000 min−1. Moleküle, die den Rotor verlassen, übertragen durch die Gasreibung ein Drehmoment auf die aufgehängte Scheibe. Die dadurch verursachte Auslenkung wird optisch gemessen und beträgt 2° bei 10−6 mbar. Die für eine primäre Messung relevanten Faktoren wie Geometrie, Randeffekte und Akkommodationskoeffizient werden in diesem Artikel diskutiert. Der experimentelle Vergleich mit einem kommerziellen Gasreibungs‐Vakuummeter zeigt die universelle Anwendbarkeit des Drehscheiben‐Vakuummeters für primäre Totaldruckmessung im Hochvakuum mit einer Genauigkeit ±3% im 10−6 mbar Bereich.
Trockenlaufende Vakuumpumpen in der chemischen Industrie
Authors: Füssel U. 
Published: July 2007

AbstractAuch in der chemischen Industrie werden in verstärktem Maße trockenlaufende Vakuumpumpen aus Umweltschutzgründen eingesetzt, weil kontaminierte Dicht‐ und Sperrmedien vermieden werden. Der Artikel beschreibt die speziellen Bedingungen für die eingesetzten Trockenläufer und zeigt an Hand typischer Beispiele ihre Einsatzmöglichkeiten in der chemischen Industrie.
Vakuummikrowellentrocknung in der Pharmazie
Authors: Altmeyer A. 
Published: July 2007

AbstractZunächst wird die Theorie der dielektrischen Erwärmung und der Mikrowellentrocknung in Ansätzen vorgestellt. Im Anschluß daran wird eine Vakuum‐Mikrowellentrocknungsanlage aus der pharmazeutischen Industrie (Verfahrensfließbild) beispielhaft dargestellt. Ein Vergleich mit der reinen Vakuumtrocknung, der Vakuumtrocknung mit Schleppgasunterstützung und der Wirbelschichttrocknung zeigt die Vorteile der Mikrowellentechnologie. Experimentell ermittelte Trocknungszeiten dieser Alternativ‐Verfahren werden verglichen. Schließlich werden einige kritische Aspekte aus pharmazeutischer Sicht gegenüber der Mikrowellentechnologie diskutiert.
Vakuum – Wirbelschicht
Authors: Luy B. , Tondar M. 
Published: July 2007

AbstractDie Vakuum‐Wirbelschicht ist ein neueres patentiertes Verfahren, das bei Verwendung organischer Lösemittel, aber auch bei Einsatz temperatur‐ und sauerstoffempfindlicher Produkte in Wirbelschichtprozessen angewandt wird. Das Verfahren wurde ausgehend von konventionellen Anlagen mit Inertisierungssystemen entwickelt. Hauptmerkmal ist die Erzeugung einer Wirbelschicht im unteren Grobvakuumbereich. Durch Erzeugen einer Wirbelschicht unterhalb des Mindestzünddrucks des jeweiligen Lösemittels können Inertgase vollständig vermieden werden. Daraus ergeben sich mehrere Vorteile: starke Reduzierung von Emissionen, Erhöhung der Rückgewinnung, Wiederverwendbarkeit des Lösemittels und Senkung von Investitions‐ und Betriebskosten. Eine Druckentlastungseinrichtung (Explosionsschutz), wie bei Frischluft‐Anlagen üblich, ist nicht erforderlich, so daß sich weitere Vorteile im Hinblick auf Anlagensicherheit und Emissionsverhalten im Havariefall ergeben (geschlossenes System).
Pervaporation – Ein Membranverfahren zur Trennung von Flüssigkeitsgemischen –
Authors: Stürken Kai 
Published: July 2007

AbstractDie Pervaporation ist ein schonendes und energiesparendes Membranverfahren für schwierige Trennungen. Der Artikel beschreibt das Verfahren und das Trennprinzip. Ferner wird auf die für einen Pervaporationsprozeß erforderlichen Komponenten eingegangen, wobei insbesondere die Bedeutung des Vakuums und der Vakuumerzeugung herausgestellt wird. Anwendungsbeispiele und Entwicklungstendenzen verdeutlichen den Einsatzbereich der Pervaporation zur Trennung flüssiger Gemische.
TQM: Anspruch und Wirklichkeit
Authors: Specht G. 
Published: July 2007

AbstractIn diesem Beitrag wird die Strategie des Total Quality Management erläutert, wobei einerseits die Darstellung der Zielsetzung von TQM und andererseits Hinweise für die praktische Einführung im Mittelpunkt stehen werden. In engem thematischen Zusammenhang stehen ferner Aspekte der Zertifizierung nach DIN ISO 9000 bis 9004 sowie des Controllings, weshalb auch hierauf kurz eingegangen werden soll. Grundlage dieses Beitrags bilden die in der Praxis gesammelten Erfahrungen eines mittelständischen Anlagenbau‐Unternehmens.