Lyapunov-based control for switched power converters

Beginning with fundamental properties such as passivity or incremental passivity of the network elements comprised by a switched power converter, the nominal open-loop operation of a broad class of such converters is shown to be stable in the large via a Lyapunov argument. The obtained Lyapunov function is then shown to be useful for designing globally stabilizing controls that include adaptive schemes for handling uncertain nominal parameters. Numerical simulations illustrate the application of this control approach in DC-DC converters     

Multifrequency averaging of DC/DC converters

This paper presents some of the issues involved in applying frequency-selective averaging to modeling the dynamic behavior of pulsewidth-modulated (PWM) DC-DC converters. We use the boost converter as an example to show the details involved in deriving some novel extended averaged models, and we use simulations to highlight the accuracy of the models even when traditional small-ripple conditions are not satisfied     

An adaptive digital controller for a unity power factor converter

This paper describes an adaptive digital controller for a unity power factor AC-DC power converter. The controller is based on a linear large-signal model of the boost power converter. A hardware design is presented and analyzed, followed by the software implementation of the control algorithm. Issues in digital control of power converters, such as quantization effects and fixed-point representation of system parameters, are examined in the context of this system. Experimental results are presented and compared with simulations     

Rational approximation via selective modal analysis

We describe a recently developed framework for exploring the structure of linear time-invariant models of large systems, and for constructing interpretable or physically-based, reduced-order models that reproduce selected modes of the original systems to a desired accuracy. Application of this framework to constructing lumped approximations for interconnections of lumped and distributed systems is briefly explored.Support for this work has come partially from the Electric Power Research Institute, Palo Alto, California, under Contract RP 1764-8 monitored by Dr. Neal Balu, and for the second author from the I.T.P. Foundation, Madrid, Spain.     

固态源输运系统推动铪基栅介质的应用

在生产中引入高介电常数绝缘材料/金属栅电极结构,需要采用全新的制造技术,前驱物和输运系统推动了铪基材料栅极绝缘层的应用。AID技术也促进了新一代栅电极材料的推广和应用。     

Coding approaches to fault tolerance in linear dynamic systems

This paper discusses fault tolerance in discrete-time dynamic systems, such as finite-state controllers or computer simulations, with focus on the use of coding techniques to efficiently provide fault tolerance to linear finite-state machines (LFSMs). Unlike traditional fault tolerance schemes, which rely heavily-particularly for dynamic systems operating over extended time horizons-on the assumption that the error-correcting mechanism is fault free, we are interested in the case when all components of the implementation are fault prone. The paper starts with a paradigmatic fault tolerance scheme that systematically adds redundancy into a discrete-time dynamic system in a way that achieves tolerance to transient faults in both the state transition and the error-correcting mechanisms. By combining this methodology with low-complexity error-correcting coding, we then obtain an efficient way of providing fault tolerance to k identical unreliable LFSMs that operate in parallel on distinct input sequences. The overall construction requires only a constant amount of redundant hardware per machine (but sufficiently large k) to achieve an arbitrarily small probability of overall failure for any prespecified (finite) time interval, leading in this way to a lower bound on the computational capacity of unreliable LFSMs.     

Dielectric spectroscopic studies on polypyrrole glucose oxidase films

An investigation was made into the dielectric spectroscopic characteristics of p-toluene sulfonate (PTS) doped polypyrrole (PPY) films in the presence and absence of immobilized glucose oxidase (GOX) in three different configurations: Al-PTS-PPY-Al-PTS-PPY/GOX-Al, and Al-PTS-PPY/GOX/β-D -glucose-Al, respectively. Measurement of dielectric loss and capacitance yielded valuable information about the dielectric properties of GOX immobilized in PTS doped PPY films. The effect of both the temperature and varying βD -glucose concentrations on the mobility of the charge carriers in these films was also systematically studied. © 1996 John Wiley & Sons, Inc.     

Studies on curcumin and curcuminoids XXI. Variation in the content of curcuminoids in Curcuma longa L. and Curcuma aromatica Salisb. from India during one season

Summary Three varieties ofCurcuma longa andC. aromatica were investigated during a growth period of 17 weeks with respect to the content of curcuminoids in the bulbs and fingers. A decrease in pigment production as a function of maturity of the rhizomes was observed. The total content of curcuminoids was equal inC. longa andC. aromatica, but with a slight difference in distribution between the fingers and bulbs in the two species. Taking the biomass into account, the fingers will be more beneficial for the isolation of curcuminoids than the respective bulbs.

---

Studien über Curcumin und Curcuminoide XXI. Unterschiede des Gehaltes an Curcuminoiden bei Curcuma longa L. und Curcuma aromatica Salisb. aus Indien während einer Saison

Zusammenfassung Drei Typen vonCurcuma longa undC. aromatica wurden während einer Wachstumsperiode von 17 Wochen auf ihren Curcuminoidgehalt in den Knollen und im Wurzelstock untersucht. Eine Abnahme der Pigmentproduktion in Abhängigkeit von dem Entwicklungsstadium der Rhizome wurde festgestellt. Der Gesamtgehalt an Curcuminoiden beiC. longa undC. aromatica war der gleiche, doch bestand ein geringer Unterschied in der Verteilung dieser zwischen Knolle und Wurzelstock bei den beiden Spezies. Bei Betrachtung der Biomasse ist der Wurzelstock für die Isolation von Curcuminoiden besser geeignet als die Knollen.

     

Failure Analysis of Modern Silicon Dice

Although the utilization of silicon dice in electronic devices has been in place for approximately 50 years, its widespread application has occurred more recently with the rapid expansion of the consumer markets for digital devices such as cameras, personal computers, video players, and smart phones. In particular, due to the recent market drive in the miniaturization and cost reduction of electronic products, silicon dice are often utilized without encapsulation and mounted directly to the substrate by means of conductive adhesives or BGA mounting. Silicon die often need to be thinned to a few hundred micrometers thickness to fit into compact devices and to reduce parasitics. The intrinsic brittle nature of silicon in combination with the lack of mechanical protection such as encapsulation has made fracture of bare dice a typical failure mechanism in handheld electronic devices. In the current work, we tested to failure {100} silicon dice and obtained mirror–mist boundary measurements for correlation to the fracture strengths of the parts. This work will also present various practical examples of how to reliably conduct failure analysis of fractured silicon dice. The intrinsic brittle nature of silicon in combination with the lack of mechanical protection such as encapsulation has made fracture of bare dice a typical failure mechanism in handheld electronic devices such as cameras, portable computers, tablets, media players, and smart phones. In these products, silicon dice are often utilized without encapsulation and are attached directly to the substrate by means of conductive adhesives or ball grid array mounting. Modern silicon dice used in these products typically have small dimensions and higher flexural strength compared to their predecessors. Prior silicon fractographic findings have investigated low strength failures. In the current work, we extend the quantitative fractography of silicon to the high failure stress regime. We have mechanically tested modern silicon dice to failure by four‐point bending and obtained mirror–mist boundary measurements for correlation to the fracture strengths of the specimens. Two key areas are addressed which improve the practical application of quantitative fractography to modern silicon dice: (1) application of silicon fractography to high flexural strength regimes and (2) development of a systematic means of reliably measuring fracture surface features.     

Analysis of Instability in Electrical Machines

While there exist numerous studies of electromechanical instabilities of specific electrical machines in constant or periodic speed operation, a broader perspective is not commonly offered. In contrast, a general machine model is used here to present essential and common features of these stability analyses. Fundamental issues are illuminated at this level of generality before specialization to the details of a specific machine. To begin, Park-transformable machines in constant-speed operation are considered. The local dynamics of these machines are linear and time-invariant. For such machines it is shown that instability may be analyzed in a useful way via systematically obtained reduced-order models. This is illustrated by significantly expanding an earlier study of a hybrid stepping motor. The more general situation in which the linearized models that govern local behavior are periodically varying is considered next. Classical Floquet theory is reviewed to provide the tools needed for stability analysis in this situation.