bluuebunny/crossref_metadata_2025_split huggingface dataset:
A modified variable structure control algorithm for stabilization of uncertain dynamical systems
Authors: Nersisian Ashot , Zanasi Roberto 
Published: July 2007

AbstractA modified VS feedback is suggested for robust stabilization of continuous‐time dynamical systems in the presence of parametric and external time‐varying disturbances satisfying the ‘matching conditions’. The main feature of the proposed algorithm is that it contains additional switching ‘integral’ terms which track the unknown disturbances and make it possible to achieve the typical VSS robustness by using switching terms in the control law with arbitrarily small amplitude. This result can be achieved only if the derivatives of the disturbances are bounded.
A non‐recursive method for solving the general discrete‐time riccati equations related to the H∞ control problem
Authors: Chen Ben M. , Saberi Ali , Shamash Yacov 
Published: July 2007

AbstractIn this paper we propose a nonrecursive method for solving the general discrete‐time algebraic Riccati equation related to the H∞ control problem (H∞‐DARE). We have achieved this by casting the problem of solving a given H∞‐DARE to the problem of solving an auxiliary continuous‐time algebraic Riccati equation associated with the H∞ control problem (H∞‐CARE) for which the well known nonrecursive methods of solving are available. The advantages of our approach are: it reduces the computation involved in the recursive algorithms while giving much more accurate solutions, and it readily provides the properties of the general H∞‐DARE.
H∞‐control with measurement‐feedback for Pritchard‐Salamon systems
Authors: Keulen Bert Van 
Published: July 2007

AbstractIn this paper we extend the finite‐dimensional results for theH∞‐control problem with measurement‐feedback to a large class of infinite‐dimensional systems, allowing for a certain type of unboundedness in the input and output operators (the Pritchard‐Salamon class). The main result of the paper relates the solvability to the suboptimalH∞‐control problem to the existence of stabilizing solutions to certain operator Riccati equations. Furthermore, a characterization of all suboptimal controllers is given.
H∞control via measurement feedback for affine nonlinear systems
Authors: Isidori Alberto 
Published: July 2007

AbstractThis paper summarizes some recent results on the problem of disturbance attenuation via measurement feedback, with internal stability, for an affine nonlinear system. The solution of the problem is shown to be related to the existence of solutions of a pair of Hamilton‐Jacobi inequalities innindependent variables, associated with state feedback and, respectively, output‐injection design.
Robust H∞ identification of linear periodic discrete‐time systems
Authors: Arambel Pablo O. , Tadmor Gilead 
Published: July 2007

AbstractSystem identification algorithms for linear time‐invariant (LTI) systems have been developed recently, which provide induced norm bounds on the difference between the true system and the identified one. The error bounds then allow the use of robust control design techniques with guarantees on performance of the real system. This note concerns the adaptation of robust H∞ identification techniques to linear periodic discrete‐time (LPDT) systems. The paper focuses on the algorithm proposed by Helmicki et al.13 and is based on a frequency‐domain approach to LPDT systems.
Identification in ℋ︁∞ with nonuniformly spaced frequency response measurements
Authors: Akcay HÜSeyin , Gu Guoxiang , Khargonekar Pramod P. 
Published: July 2007

AbstractIn this paper, the problem of ‘system identification in ℋ︁∞’ is investigated in the case when the given frequency response data are not necessarily on a uniformly spaced grid of frequencies. A large class of robustly convergent identification algorithms is derived. A particular algorithm is further examined and explicit worst case error bounds (in the ℋ︁∞ norm) are derived for both discrete‐time and continuous‐time systems. An example is provided to illustrate the application of the algorithms.
Finite horizon H∞ with parameter variations
Authors: Subrahmanyam M. B. 
Published: July 2007

AbstractIn this paper we consider the finite horizon H∞ performance robustness problem with parameter variations. Assuming a nominal model, an iterative procedure is given to synthesize a suboptimal H∞ controller, which yields the required performance even under parameter variations. As a byproduct, an expression for the variation of performance due to parameter variations is given for this specific controller. An example which illustrates the methodology is worked out under parameter uncertainties.
Robust performance control of uncertain nonlinear systems: A self‐tuning approach
Authors: Lee T. S. , Chen B. S. 
Published: July 2007

AbstractThe problem of output regulation with a guaranteed H∞ performance, besides robust stability, for a class of feedback linearizable nonlinear systems via self‐tuning controllers is investigated. The H∞ performance consists of the desired disturbance attenuation and internal finite L2‐gain stability. We show that, under the perturbations of matched parametric uncertainties, the sufficient condition for the existence of a self‐tuning controller reduces to the solvability of a single Hamilton‐Jacobi‐Isaacs inequality (or algebraic Riccati equation) which indicates that the design can be performed as if the system uncertainties were absent. Under certain situations, the sufficient condition is also necessary. Once a solution of this nonlinear differential inequality (or algebraic equation) is available, a desired self‐tuning controller with gradient‐type parameter estimator can easily be constructed. The present work falls into the category of singular nonlinear H∞ control since the desired H∞ performance does not require any penalty on control input variables. The results also provide an immediate application to H∞ self‐tuning model reference control in linear systems under full state measurement.
An explicit finite difference method for finite‐time observers
Authors: James Matthew R. 
Published: July 2007

AbstractIn this paper we present a numerical method for estimating the current state of a nonlinear control system. We use finite differences to discretize a modified version of the finite‐time observer equations in James. The discretized equations are simple and easily programmed. The convergence and accuracy of the scheme is proved, and the scheme enjoys a number of important properties: availability of rate of convergence estimates, good robustness characteristics, and the ability to handle certain types of discontinuities in the observations. The major disadvantage is that the number of grid points required increases exponentially with the number of state dimensions.
Stochastic robustness synthesis applied to a benchmark control problem
Authors: Marrison Christopher I. , Stengel Robert F. 
Published: July 2007

AbstractStochastic robustness synthesis is used to find compensators that solve a benchmark problem. The synthesis minimizes a robustness cost function that is the weighted quadratic sum of stochastic robustness metrics. These metrics — probability of instability, probability of actuator saturation, and probability of settling time violation — are estimated using Monte Carlo analysis. A simple search method minimizes the robustness cost by selecting values for the design parameters of a linear quadratic Gaussian regulator. The resulting compensators are robust, require low actuator authority, and compare well with previous designs.
Control of nonholonomic systems with extended base space dynamics
Authors: Reyhanoglu Mahmut , Bloch Anthony M. , Harris Mcclamroch N. 
Published: July 2007

AbstractThis paper extends certain results in Reference 1 to a more general class of nonholonomic systems with extended base space dynamics. This extension is important in applications for which control actuator dynamics are significant. These nonlinear control systems are referred to as nonholonomic control systems owing to certain nonintegrability assumptions which are made. The class of systems considered in this paper are characterized by general nonlinear base space dynamics that are input‐output decouplable. Controllability results for this class of nonholonomic control systems are presented.
LTR design of proportional‐integral observers
Authors: Niemann H. H. , Stoustrup J. , Shafai B. , Beale S. 
Published: July 2007

AbstractThis paper applies the proportional‐integral (PI) observer in connection with loop transfer recovery (LTR) design for continuous‐time systems. We show that a PI observer makes it possible to obtain time recovery, i.e., exact recovery fort→∞, under mild conditions. Based on an extension of the LQG/LTR method of proportional (P) observers, a systematic LTR design method is derived for the PI observer. Our recovery design method allows time recovery and frequency (normal) recovery to be done independently. Furthermore, we give explicit expressions for the recovery error when asymptotic recovery cannot be obtained. A design example demonstrates the advantages of time recovery in the non‐minimum phase case.
Bootstrap significance test of synchronous spike events—A case study of oscillatory spike trains
Authors: Ito Hiroyuki 
Published: July 2007

AbstractThe purpose of this monograph is two folds. Firstly, we introduce challenging spike data to the statistical analysis. The data of two neurons recorded from the cat visual pathway show various non‐stationary characteristics not fitted by the Poisson spike train. Spike firings of both neurons are strongly periodic and tightly synchronized. Our second purpose is a case study of applications of various statistical methods for the significance test of the time‐varying spike synchrony. We provide various general remarks to the statistical analysis of the synchronous spike activities. At first, we apply the unitary event analysis. The significance limit for the coincident spike events by the Poisson distribution is compared with the limit given by the non‐parametric test based on the bootstrap samplings. The bootstrap test performs superior to the Poisson test in two respects: (1) avoids false positives due to the sudden change of spike density; and (2) takes into account the non‐stationary change of the spiking pattern at different sampling windows. When the spike trains are highly periodic, the histogram of the number of accidental coincident spike events over the bootstrap samples has a systematically larger variance than the Poisson distribution. We find that a large variance originates from the correlation between the successive coincident spike events in the structured spike trains. The significance of the time‐varying synchrony is tested by another statistical method by Ventura et al., which is based on the adaptive smoothing method and the bootstrap significance test. Copyright © 2007 John Wiley & Sons, Ltd.
Youden Index and the optimal threshold for markers with mass at zero
Authors: Schisterman Enrique F. , Faraggi David , Reiser Benjamin , Hu Jessica 
Published: July 2007

AbstractThe Youden Index is often used as a summary measure of the receiver operating characteristic curve. It measures the effectiveness of a diagnostic marker and permits the selection of an optimal threshold value or cutoff point for the biomarker of interest. Some markers, while basically continuous and positive, have a spike or positive mass of probability at the value zero. We provide a flexible modeling approach for estimating the Youden Index and its associated cutoff point for such spiked data and compare it with the standard empirical approach. We show how this modeling approach can be adjusted to take covariate information into account. This approach is applied to data on the Coronary Calcium Score, a marker for
atherosclerosis. Published in 2007 by John Wiley & Sons, Ltd.
Vakuummeßgeräte für Totaldruck
Authors: Kündig Charles 
Published: July 2007

AbstractAdvances in the technical/technological development has resulted in a large growth of vacuum applications and the employment of vacuum techniques in almost all technical fields. In response to this expansion, the number of commercial vacuum gauges has increased. For the engineer or technician it has become more difficult, to make the right choice of the gauge. The present paper is intended as a guide. First, the most important measuring principles are dicussed. Thereafter modern equipment is decribed with application notes for different pressure ranges.
Stand der Kernfusionsforschung
Authors: Hofmann J. V. , Milch I. , Wagner F. 
Published: July 2007

AbstractThe aim of nuclear fusion research is to reproduce on earth the energy generating process of the sun and derive energy from the fusion of atomic nuclei. This is to be done by confining the fuel, a low‐density hydrogen plasma, in magnetic fields and heating it to high temperatures of over 100 million degrees.Research has made major progress on the way to a burning plasma. JET, the joint European experiment, is just a factor of 6 short of achieving plasma ignition. ITER, the test reactor now being planned in international cooperation, is intended to produce the first burning plasma providing energy over a long period.
Hochtemperatur‐Supraleitungs‐Technologie — Herstellung und Anwendungspotentiale
Authors: Auge J. , Barth R. 
Published: July 2007

AbstractThe discovery of high‐temperature‐superconductors, which exhibit a transition temperature above 77 K, was supposed to be the best way to achieve superconductivity at room temperature. The research of the recent years turned out, that further problems have to be solved. Especially the layered structure of the new ceramic superconductors reveals in several drawbacks in the preparation techniques. The purpose of this article is to give a comprehensive overview about different preparation techniques of high temperature superconductors. A summary of their cryoelectronic applications will be presented.
Properties of Si3N4and AIN Films Produced by Reactive Ion Plating and Gas Discharge Sputtering
Authors: Monz K. H. , Danh Nguyen Quang , Huter M. , Rille E. P. , Pulker H. K. 
Published: July 2007

AbstractThin films of Silicon‐ and Aluminiumnitride were produced by Reactive Low Voltage Ion Plating and low pressure dc‐Magnetron Sputtering. The films show excellent adherence, high hardness and abrasion resistance, and are dense and homogeneous. Both processes, applied at optimum conditions, enable the production of films with nearly identical optical properties. Such optimized deposition conditions in both processes yielded a mean refractive index of n550= 2.05 ± 0.03 for Si3N4and of n550= 2.12 ± 0.01 for AIN films. The region of high optical transmission was found to be between 0.23 and 9.5μm (Si3N4) and between 0.2 and 12.5 μm (AIN). In the visible range both metal nitride films are free of optical absorption (k <10−3). These materials, together with their oxynitride phases, offer interesting applications for the deposition of optical multilayer systems with very high spectral stability.
Thermochromes VO2 für die Beschichtung von Architekturglas
Authors: Christmann T. , Kriegseis W. , Niessner A. , Schalch D. , Scharmann A. , Werling M. 
Published: July 2007

AbstractIn recent years vanadium dioxide films were discussed as thermochromic window coatings. Up to now it is not possible to deposit films, the properties of which are well‐suited for technical application. In the following properties of reactively rf sputtered VO2 films on a laboratory scale are reported. Besides optical measurements, analytical techniques as photoelectron spectometry, electron energy loss spectrometry, and secondary ion mass spectrometry are applied to VO2 films for the first time. We expect that these investigations will result in a better understanding of the metal‐to‐semiconductor transition, and other film properties as for example electronic defects and diffusion profiles at the interfaces and their effects on the band structure, thus aiming at superior film processing. In the following a survey over first results is presented.
Sample Exposition System for Plasma Analysis of a Fusion Reactor
Authors: Alessandrini C. , Apicella M. L. , Bella L. Dalla , Maddaluno G. 
Published: July 2007

AbstractPlasma diagnosis of a fusion reactor can be performed by means of samples which first are exposed to the plasma and then investigated by surface analysis techniques. Construction and tests of such a diagnosis system are described. This system uses a demountable sample chamber in which the samples can be transported under UHV conditions to a distant laboratory for surface analysis.
Ionenstrahltechnologien – Werkzeug für das 21. Jahrhundert
Authors: Mucha A. , Schröer A. 
Published: July 2007

AbstractDie Oberflächen‐ und Dünnschichttechnologie zeigte in den 10 Jahren ein kontinuierliches Wachstum und fand Eingang in eine Reihe neuer Anwendungsbereiche. Einige Produkte wie z.B. die CD‐Produktion oder wärmedämmendes Architekturglas wären ohne die Dünnschichttechnik nur äußerst schwer zu realisieren. Die Ionenstrahlverfahren stellen mit die jüngsten Entwicklungen auf diesem Gebiet dar und bieten dem Anwender neue Veredelungsmöglichkeiten seiner Werkstoffe. Die Beschichtung bzw. Modifizierung der Oberfläche kann auf nahezu alle Werkstoffklassen, wie z.B. Stahl, Polymere, Keramiken und Halbleiter durchgeführt werden.Die Ionenimplantation führt u.a. zur einer Härtung der Substratwerkstoffe im oberflächennahen Bereich. Da keine eigentliche Schicht aufgebracht wird, sind Schichtablösungen ausgeschlossen. Dadurch ist dieses Verfahren für den medizinischen, Pharmazeutischen oder lebensmitteltechnischen Bereich von hoher Bedeutung. Der modifizierte Erkstoff bleibt in seinen Vollmaterialeigenschaften unverändert und verhält sich zudem nicht toxisch.Durch den Ionenstrahlbeschuß konnte bei Präzisionswerkzeugen bis zu 10fache Standzeitveränderungen erzielt werden. Auch die Ionenstrahlbehandlung von Keramikbauteilen führt zu einem verbesserten Verchleißverhalten.In Kombination mit einer Beschichtungsquelle können unterschiedlichste Schichtsysteme haftfest bei Temperaturen unterhalb von 250°C abgeschieden werden. Die Ionenstrahlgestützte Beschichtung kann ebenfalls für nahezu alle Werkstoffklassen angewendet werden.Die Ionenstrahlverfahren werden auch in Ergänzung zu anderen Beschichtungstechnologien eingesetzt. Eine nachträgliche Stickstoffimplantation in hartverchromte Bauteile bewirkt eine deutliche Verbesserung des Verschleißverhaltens.Die Ionenstrahlverfahren — konventionelle Ionenimplantation, Ionenstrahlgestützte Beschichtung, Plasma‐Immersions‐Ionenimplantation — sind sehr flexible und leistungsfähige Techniken um Problemstellungen im Bereich der Hochleistungswerkstoffen zu bearbeiten und zu lösen.
Asymmetric Bipolar Pulsed DC
Authors: Sellers Jeff , Pfähler Jürgen 
Published: July 2007

AbstractZusammenfassung Asymmetric Bipolar Pulsed DC wurde als Energieform entwickelt, um isolierende Schichten in einem reaktiven PVD‐Prozess vom metallischen Target kostengünstig und mit hohen Raten langzeitstabil abzuscheiden. Die „Forward Power”︁ (negativer Bereich) arbeitet als Stromquelle, da Ionen bewegt werden müssen. Die „Revers Power”︁ (positiver Bereich) arbeitet als Spannungsquelle, da Elektronen zur Kompensation einer positiven Aufladung bewegt werden müssen. Mit dieser Technik wird die Targetvergiftung vermieden. Außer allen üblichen Parameter eines DCG (DC Generator) gibt es beim RPG (Reactive Plasma Generator) 3 weitere programmierbare Parameter:

Frequenz (50–250KHz)
Duty Cycle (0–40%)
Amplitude des positiven Anteils genannte Reverse Bias Voltage (50–120V) Damit kann der Anwender den RPG (Reactive Plasma Generator) schnell für einen bestimmten Prozess optimieren. Es werden auch andere Quellentechniken mit der vorliegenden verglichen und erörtert. Außerdem wird der Einsatz des RPG (Reactive Plasma Generators) in Verbindung mit PVD‐ und CVD‐Prozessen beschrieben.
Ausgasungsmessungen von Metallen, Plasten und Kohlenstoff
Authors: Schindler N. 
Published: July 2007

AbstractEs wird eine Meßapparatur zur gasartselektiven Gasabgabemessung vorgestellt und die notwendige Meßdatenaufbereitung beschrieben. Die damit gemessenen partiallen und totalen Gasabgaberaten von einigen wichtigen Metallen, Plasten, Kohlenstoffen und Schichten nach verschiedenen Vorbehandlungen werden dargestellt. Diese Gasabgaberaten werden quantitativ verglichen und qualitativ ausgewertet. Für jedes Gas wurde eine separate Leitwertkorrektur vorgenommen. Für Metalle wurde der Einfluß von gasabgabereduzierenden Schichten und von Reinigungsprozeduren untersucht. Die Messungen an verschiedenen Plasten zeigen den jeweiligen Anteil von Kohlenwasserstoffen an der Gesamtausgasung dieser Stoffe. Für Messungen an Graphitproben wird der Anteil der Wasserstoffausgasung diskutiert.
Lichtbogengestützte Prozesse zur Beschichtung von Kunststoffen
Authors: Hasse B. , Hinz H.‐P. , Müller R. , Siefert W. 
Published: July 2007

AbstractIn den letzten zehn Jahren haben plasmagestützte Beschichtungsverfahren verstärkt an Bedeutung gewonnen. Viele neue Schichteigenschaften sind erst durch diese Verfahren realisierbar geworden, wie beispielsweise hohe Haftung und Einstellbarkeit von Schichtstrukturen. Eines der neuen plasmagestützten Beschichtungsverfahren ist das lichtbogengestützte Aufdampfen. Die Funktionsweise dieses Verfahrens wird beschrieben ebenso wie die Eigenschaften der mit dieser Aufdampfquelle hergestellten Schichten.
Beschichtung von Kunststoffgehäusen zur Sicherung der elektromagnetischen Verträglichkeit elektronischer Geräte
Authors: Blasek G. 
Published: July 2007

AbstractDie zunehmende Belastung der Umwelt erfordert im Interesse der technischen Sicherheit sensibler Geräte und der Gesundheit der Menschen Maßnahmen, die elektromagnetische Verträglichkeit elektrisch/elektronischer Geräte zu gewährleisten. Eine wichtige Maßnahme ist die Schirmung bei den zunehmend eingesetzten Kunststoffgehäusen. Das stellt eine neue Herausforderung an eine produktive, kostengünstige Beschichtungstechnik. Für die massenweise Beschichtung von Gehäusen haben die galvanotechnischen und die vakuumtechnischen Verfahren die besten Voraussetzungen, mit Abstrichen sind auch das thermische Spritzen und das Leitlackieren geeignet. Aus ökologischer und wohl auch ökonomischer Sicht sind vakuumtechnische Verfahren günstiger als galvanotechnische und gewinnen an Bedeutung. Nachteilig sind aber die begrenzte Schichthomogenität und die thermische Belastung der Objekte. An der Verbesserung der Leistungsfähigkeit vakuumtechnischer Verfahren wird gearbeitet. Gute Chancen haben kombinierte vakuumtechnisch‐galvanotechnische Verfahren.
VAKUUMWAAGEN Teil 1: Einleitung und Makrowaagen
Authors: Robens Erich , Gast Theodor , Jenemann Hans R. 
Published: July 2007

AbstractWaagen, bei denen sich das zu wägende Gut im Vakuum befindet, werden als Vakuumwaagen bezeichnet. Makrowaagen sind für Lasten von mehr als 100 g ausgelegt. Zum Vergleich von Masseprototypen ohne Auftrieb wurden Vakuum‐Komparatorwaagen entwickelt. Große Vakuumwaagen werden zur Molekulargewichtsbestimmung und zur Messung der Gasdichte verwendet. Für chemische Untersuchungen unter reduziertem Gasdruck und zur thermogravimetrischen Analyse werden Vakuum‐Analysenwaagen mit elektrischer Meßwerterfassung eingesetzt. Zur Steuerung von Produktionsprozessen in kontrollierter Atmosphäre dienen Wägezellen unterschiedlicher Bauart.