bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Nef-Mediated Downregulation of Major Histocompatibility Complex Class I on Immune Response to Simian Immunodeficiency Virus
Authors: Swigut Tomek , Alexander Louis , Morgan Jennifer , Lifson Jeff , Mansfield Keith G. , Lang Sabine , Johnson R. Paul , Skowronski Jacek , Desrosiers Ronald
Published: November 2004

Functional activities that have been ascribed to the
nef
gene product of simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) include CD4 downregulation, major histocompatibility complex (MHC) class I downregulation, downregulation of other plasma membrane proteins, and lymphocyte activation. Monkeys were infected experimentally with SIV containing difficult-to-revert mutations in
nef
that selectively eliminated MHC downregulation but not these other activities. Monkeys infected with these mutant forms of SIV exhibited higher levels of CD8
+
T-cell responses 4 to 16 weeks postinfection than seen in monkeys infected with the parental wild-type virus. Furthermore, unusual compensatory mutations appeared by 16 to 32 weeks postinfection which restored some or all of the MHC-downregulating activity. These results indicate that
nef
does serve to limit the virus-specific CD8 cellular response of the host and that the ability to downregulate MHC class I contributes importantly to the totality of
nef
function.
BIPARTITIONING INTO OVERLAPPING SETS
Authors: HARALAMBIDES JAMES , TRAGOUDAS SPYROS
Published: November 2004

We consider a generalization of the min-cut partitioning problem where we partition a graph G=(V,E) into two sets V1 and V2 such that |V1∩V2|≤d, d<|V|, and such that |{(u, v)|u∈V1−V2, v∈V2−V1}| is minimized. The problem is trivially solvable using flow techniques for any fixed d, but we show that it is NP-hard for integer values of d. It remains NP-hard if we impose restrictions on the size of V1, i.e., |V1|=k, k∈Z+. The latter problem variation may apply in VLSI layout and hypertext partitioning. We present polynomial time algorithms for the special cases of solid grids and series-parallel graphs. Series-parallel graphs find applications in hypertext partitioning whereas grid graphs model the mapping of a class of Partial Differential Equation computations into parallel machines.
A NOTE ON THE ASYMPTOTIC PROBABILITIES OF EXISTENTIAL SECOND-ORDER MINIMAL GÖDEL SENTENCES WITH EQUALITY
Authors: SZWAST WIESŁAW
Published: November 2004

The minimal Gödel class is the class of first-order prenex sentences whose quantifier prefix consists of two universal quantifiers followed by just one existential quantifier. We prove that asymptotic probabilities of existential second-order sentences, whose first-order part is in the minimal Gödel class, form a dense subset of the unit interval.
THE QUINE-BERNAYS COMBINATORY CALCULUS
Authors: RAJA N. , SHYAMASUNDAR R.K.
Published: November 2004

We develop a theory for constructing Combinatory Versions of λ-calculi. Our theory is based on a method, used by Quine and Bernays, for the general elimination of variables in formulations of first-order logic. Our Combinatory Calculus presents a significant departure from those propounded by Schönfinkel and Curry. A non-trivial extension of Quine’s technique is developed, to go beyond the realm of first-order quantification theory, and cover the entire λ-calculus. The system consists of five Combinators, powerful enough to represent λ-abstractions over arbitrary terms. The Combinatory Calculus is shown to have the property of functional completeness. Algorithmic translations from the λ-calculus to the Combinatory Version, and vice-versa, are provided. The approach has the distinct advantage of being able to encode combinatory formulations of process algebras.
ON THE POWER OF ONE-WAY GLOBALLY DETERMINISTIC SYNCHRONIZED ALTERNATING TURING MACHINES AND MULTIHEAD AUTOMATA
Authors: SLOBODOVÁ ANNA
Published: November 2004

The alternating model augmented by a special simple form of communication among parallel processes—the so-called synchronized alternating (SA) model, provides (besides others) nice characterizations of the space complexity classes defined by nondeterministic Turing machines. The model investigated in this paper — globally deterministic synchronized alternating (GDSA) model—is obtained by a feasible restriction of nondeterminism in SA. It is known that it characterizes the deterministic counterparts of the nondeterministic space classes characterized by the SA model.

In the paper we resume in the investigation of GDSA solving the open questions about the computational power of the one-way GDSA models. It is known that in the case of space-bounded Turing machine and multihead automata, the one-way SA models are equivalent to their two-way counterparts. We show that the same holds for GDSA models. The results contribute to the knowledge about the model and imply new characterizations of the deterministic space complexity classes.
${\rm{MeV}}\mbox{-}\left( {\rm{C}} \right)_{\rm{2}}^{\rm{ + }} $-ION-INDUCED Cu K X-RAY EMISSION
Authors: Zonghuang Xia , Qian Wang , Dingyu Shen , Shuozhong Li
Published: November 2004

Cu K X-ray spectra for a copper target bombarded with ion beams of 1.4 [Formula: see text] ions, 2. 8 [Formula: see text] ions, and 3.0 MeV-Si+ ions have been measured with a Si(Li) detector. It is found that the Cu K X-ray spectrum for [Formula: see text] ion bombardments is almost same as that for C+ ion bombardments, whereas the spectrum for Si+ ion bombardments has a broad peak of MO X-rays in the low-energy region. The values of Kα/Kα+β for the Cu K X-rays are very close each other within the experimental uncertainty in these three cases. Thus, no multi-ionization effect is observed in the K X-ray emission by [Formula: see text] beam bombardments.
PIXE AS AN ESSENTIAL TOOL FOR RARE METAL BENEFICIATION AND EXPLORATION
Authors: MURAO SATOSHI , SIE SOEY H
Published: November 2004

We have examined tin-polymetallic ore, a complex mixture of cassiterite (SnO2) and sulfides, by micro-PIXE. Tin-polymetallic ore is one of the major sources of technologically important “rare metals”, especially of indium and bismuth, usually as trace elements. In addition to such rare metals, silver is another important trace component in the ore. But the trace elemental distribution of tin-polymetallic deposit has not well been described due to the small size of constituent minerals, complex ore texture, and lack of analytical method to detect trace elements in a small area. PIXE with a proton microbeam could be an effective tool to solve this problem by delineating the distribution of these trace elements among carrier minerals with the required sensitivity. Thus we have applied PIXE with the CSIRO’s proton microprobe to a tin-polymetallic ore from Canada. The result showed that micro-PIXE is an essential tool to study trace element distribution in such a complex ore.
FISH OTOLITHS ANALYSIS BY PIXE: APPLICATION TO STOCK DISCRIMINATION
Authors: ARAI NOBUAKI , TAKAI NORIYUKI , SAKAMOTO WATARU , YOSHIDA KOJI , MAEDA KUNIKO
Published: November 2004

Fish otoliths are continuously dsposited from fish birth to its death along with encoding environmental information. In order to decode the information, PIXE was adopted as trace elemental analysis of the otoliths. Strontium to calcium concentration ratios of red sea bream otoliths varied among rearing stations. The Sr/Ca ratios of Lake Biwa catfishes also varied between male and female and among fishing grounds. The PIXE analysis was applied to the fish stock discrimination.
FERROMAGNETIC CHAIN EQUATIONS FROM CLOSED RIEMANNIAN MANIFOLDS ONTO S2
Authors: WANG YOUDE
Published: November 2004

In this paper we establish the existence of global weak solutions to ferromagnetic chain equations from closed Riemannian manifolds onto S2.
LINK COMPLEMENTS ARISING FROM ARITHMETIC GROUP ACTIONS
Authors: GRUNEWALD FRITZ , HIRSCH ULRICH
Published: November 2004

Let [Formula: see text] be a torsion-free subgroup acting discontinuously on 3-dimensional hyperbolic space [Formula: see text]. Assume further that Γ\ℍ3 has finite hyperbolic volume. The quotient-space Γ\ℍ3 is then a 3-manifold which can be compactified by the addition of finitely many 2-tori. This paper discusses a procedure which decides whether Γ\ℍ3 is homeomorphic to the complement of a link in S3. We apply our procedure to subgroups of low index in [Formula: see text], where [Formula: see text] is the ring of integers in [Formula: see text]. As a result we find new link complements having a complete hyperbolic structure coming from an arithmetic group. Finally we prove that up to conjugacy there are only finitely many commensurability classes of arithmetic subgroups [Formula: see text] so that Γ\ℍ3 is homeomorphic to the complement of a link in S3.
ENTROPY FOR CANONICAL SHIFTS AND STRONG AMENABILITY
Authors: HIAI FUMIO
Published: November 2004

When N⊂M is an inclusion of type II1 factors with finite index, let Γ be the canonical shift on the von Neumann algebra R generated by the derived tower of N⊂M, H(R|Γ(R)) the relative entropy, and H(Γ) the dynamical entropy. We characterize the equality cases of the inequalities [Formula: see text] in connection with the subexponential growth condition and the strong amenability condition. Also the topological entropy of Γ and the convergence of entropy increments on the derived tower are discussed.
VARIATION OF THE GIESEKER AND UHLENBECK COMPACTIFICATIONS
Authors: HU YI , LI WEI-PING
Published: November 2004

In this article, we study the variation of the Gieseker and Uhlenbeck compactifications of the moduli spaces of Mumford-Takemoto stable vector bundles of rank 2 by changing polarizations. Some canonical rational morphisms among the Gieseker compactifications are shown to exist. In particular, we proved that when the second Chern class is sufficiently large, these morphisms are genuine rational maps. Moreover, as a consequence of studying the morphisms from the Gieseker compactifications to the Uhlenbeck compactifications, we show that there is an everywhere-defined canonical algebraic map between two adjacent Uhlenbeck compactifications which restricts to the identity on some Zariski open subset.
AMPLE VECTOR BUNDLES WITH SECTIONS VANISHING ON PROJECTIVE SPACES OR QUADRICS
Authors: LANTERI ANTONIO , MAEDA HIDETOSHI
Published: November 2004

Let ɛ be an ample vector bundle of rank r≥2 on a compact complex manifold X of dimension n≥r+1 having a section whose zero locus is a submanifold Z of the expected dimension n–r. Pairs (X, ɛ) as above are classified under the assumption that Z is either a projective space or a quadric.
HERMITIAN-EINSTEIN INEQUALITIES AND HARDER-NARASIMHAN FILTRATIONS
Authors: BRADLOW STEVEN B.
Published: November 2004

Unstable holomorphic bundles can be described algebraically by Harder-Narasimhan filtrations. In this note we show how such filtrations correspond to the existence of special metrics defined by Hermitian-Einstein inequalities.
EPIMORPHISMS OF NEST ALGEBRAS
Authors: DAVIDSON KENNETH R. , HARRISON KENNETH J. , ORR JOHN LINDSAY
Published: November 2004

We study epimorphisms of one nest algebra onto another. Such maps are always continuous. Most are obtained from a compression to an interval followed by a similarity. The others factor through an ultraproduct of the discrete intervals of finite rank atoms. When the image nest has no infinite part, these maps are limits of compression maps along an ultrafilter.
STATIONARY DISCS OF FIBRATIONS OVER THE CIRCLE
Authors: ČERNE MIRAN
Published: November 2004

Stationary discs of fibrations over the unit circle ∂D are considered. It is shown that if all fibers of a fibration Σ⊆∂D×Cn over the unit circle ∂D are strongly pseudoconvex hypersurfaces in Cn, then for every stationary disc f of the fibration Σ one can define the partial indices of f. In the case all fibers of Σ are strictly convex, it is proved that all partial indices of a stationary disc f are 0. It is also proved that in the case a stationary disc f of the fibration Σ is non-degenerate, the only possible partial indices of f are 0, 1 and –1. In particular, these results give information on the polynomial hull of Σ and new proofs of results related to the smoothness of the Kobayashi metric on some strongly pseudoconvex domains in Cn.
ASYMPTOTIC ANALYSIS OF A HERMITIAN MATRIX INTEGRAL
Authors: MULASE MOTOHICO
Published: November 2004

The asymptotic expansion of a Hermitian matrix integral known as the Penner model is rigorously calculated.
SHAPE RECOGNITION USING A FIXED-SIZE VLSI ARCHITECTURE
Authors: CHENG H.D. , CHENG X.
Published: November 2004

Shape recognition is an important research area in pattern recognition. It also has wide practical applications in many fields. An attribute grammar approach to shape recognition combines both the advantages of syntactic and statistical methods and makes shape recognition more accurate and efficient. However, the time complexity of a sequential shape recognition algorithm using attribute grammar is O(n3) where n is the length of an input string. When the problem size is very large it needs much more computing time, therefore a high speed parallel shape recognition is necessary to meet the demands of some real-time applications. This paper presents a parallel shape recognition algorithm and also discusses the algorithm partition problem as well as its implementation on a fixed-size VLSI architecture. The proposed algorithm has time complexity O(n3/k2) if using k×k processing elements. When k=n, its time complexity is O(n). The experiment has been conducted to verify the performance of the proposed algorithm. The correctness of the algorithm partition and the behavior of the proposed VLSI architecture have also been proved through the experiment. The results indicate that the proposed algorithm and the VLSI architecture could be very useful to imaging processing, pattern recognition and related areas, especially for real-time applications.
A RECONFIGURABLE ARCHITECTURE FOR IMAGE PROCESSING AND COMPUTER VISION
Authors: BHANDARKAR SUCHENDRA M. , ARABNIA HAMID R. , SMITH JEFFREY W.
Published: November 2004

In this paper we describe a reconfigurable architecture for image processing and computer vision based on a multi-ring network which we call a Reconfigurable Multi-Ring System (RMRS). We describe the reconfiguration switch for the RMRS and also describe its VLSI implementation. The RMRS topology is shown to be regular and scalable and hence well-suited for VLSI implementation. We prove some important properties of the RMRS topology and show that a broad class of algorithms for the n-cube can be mapped to the RMRS in a simple and elegant manner. We design and analyze a class of procedural primitives for the SIMD RMRS and show how these primitives can be used as building blocks for more complex parallel operations. We demonstrate the usefulness of the RMRS for problems in image processing and computer vision by considering two important operations—the Fast Fourier Transform (FFT) and the Hough transform for detection of linear features in an image. Parallel algorithms for the FFT and the Hough transform on the SIMD RMRS are designed using the aforementioned procedural primitives. The analysis of the complexity of these algorithms shows that the SIMD RMRS is a viable architecture for problems in computer vision and image processing.
FACILITATING HIGH-PERFORMANCE IMAGE ANALYSIS ON REDUCED HYPERCUBE (RH) PARALLEL COMPUTERS
Authors: ZIAVRAS SOTIRIOS G. , SIDERAS MICHALIS A.
Published: November 2004

The direct binary hypercube interconnection network has been very popular for the design of parallel computers, because it provides a low diameter and can emulate efficiently the majority of the topologies frequently employed in the development of algorithms. The last fifteen years have seen major efforts to develop image analysis algorithms for hypercube-based parallel computers. The results of these efforts have culminated in a large number of publications included in prestigious scholarly journals and conference proceedings. Nevertheless, the aforementioned powerful properties of the hypercube come at the cost of high VLSI complexity due to the increase in the number of communication ports and channels per PE (processing element) with an increase in the total number of PE’s. The high VLSI complexity of hypercube systems is undoubtedly their dominant drawback; it results in the construction of systems that contain either a large number of primitive PE’s or a small number of powerful PE’s. Therefore, low-dimensional k-ary n-cubes with lower VSLI complexity have recently drawn the attention of many designers of parallel computers. Alternative solutions reduce the hypercube’s VLSI complexity without jeopardizing its performance. Such an effort by Ziavras has resulted in the introduction of reduced hypercubes (RH’s). Taking advantage of existing high-performance routing techniques, such as wormhole routing, an RH is obtained by a uniform reduction in the number of edges for each hypercube node. An RH can also be viewed as several connected copies of the well-known cube-connected-cycles network. The objective here is to prove that parallel computers comprising RH interconnection networks are definitely good choices for all levels of image analysis. Since the exact requirements of high-level image analysis are difficult to identify, but it is believed that versatile interconnection networks, such as the hypercube, are suitable for relevant tasks, we investigate the problem of emulating hypercubes on RH’s. The ring (or linear array), the torus (or mesh), and the binary tree are the most frequently used topologies for the development of algorithms in low-level and intermediate-level image analysis. Thus, to prove the viability of the RH for the two lower levels of image analysis, we introduce techniques for embedding the aforementioned three topologies into RH’s. The results prove the suitability of RH’s for all levels of image analysis.
ANALYSIS AND DESIGN OF PARALLEL THINNING ALGORITHMS—A GENERIC APPROACH
Authors: ZHANG Y.Y. , WANG P.S.P.
Published: November 2004

In this paper, a generic approach for the analysis and design of parallel thinning algorithms is presented. The procedures for designing 4-subcycle/iteration, 2-subcycle/iteration, and 1-subcycle/iteration thinning algorithms are developed. The experimental results show that these thinning algorithms designed by proposed approach preserve image connectivity, produce thinner results, and obtain faster speed than many existing key thinning algorithms. As an example, a 1-subcycle/iteration algorithm and its experimental results were illustrated, which is in general about two times faster than others in the literature.
THE EFFECT OF INKDOTS FOR TWO-DIMENSIONAL AUTOMATA
Authors: ITO AKIRA , INOUE KATSUSHI , TAKANAMI ITSUO , WANG YUE
Published: November 2004

Recently, related to the open problem of whether deterministic and nondeterministic space (especially lower-level) complexity classes are separated, the inkdot Turing machine was introduced. An inkdot machine is a conventional Turing machine capable of dropping an inkdot on a given input tape for a landmark, but not to pick it up nor further erase it.

In this paper, we introduce a finite state version of the inkdot machine as a weak recognizer of the properties of digital pictures, rather than a Turing machine supplied with a one-dimensional working tape. We first investigate the sufficient spaces of three-way Turing machines to simulate two-dimensional inkdot finite automaton, as preliminary results. Next, we investigate the basic properties of two-dimensional inkdot automaton, i.e. the hierarchy based on the number of inkdots and the relationship of two-dimensional inkdot automata to other conventional two-dimensional automata. Finally, we investigate the recognizability of connected pictures of two-dimensional inkdot finite machines.
ON TOPOLOGY PRESERVATION IN 2-D AND 3-D THINNING
Authors: KONG T.Y.
Published: November 2004

An (m, n)-simple 1 in a binary image I has the property that its deletion “preserves topology” when m-adjacency is used on the 1’s and n-adjacency on the 0’s of I. This paper presents new, easily visualized, necessary and sufficient conditions for a 1 in I to be (m, n)-simple, for (m, n)=(26, 6), (18, 6), (6, 26) or (6, 18) when I is a 3-d image and (m, n)=(8, 4) or (4, 8) when I is a 2-d image.

Systematic and fairly general methods of verifying that a given parallel thinning algorithm always preserves topology are described, for the cases where 8-/26-adjacency is used on the 1’s and 4-/6-adjacency on the 0’s, or vice versa. The verification methods for 2-d algorithms are mainly due to Ronse and Hall; the methods for 3-d algorithms were found by Ma and Kong. New proofs are given of the correctness of these verification methods, using the characterizations of simple 1’s presented in this paper.
HUMAN FACE DETECTION USING SILHOUETTES
Authors: SAMAL ASHOK , IYENGAR PRASANA A.
Published: November 2004

Face detection is integral to any automatic face recognition system. The goal of this research is to develop a system that performs the task of human face detection automatically in a scene. A system to correctly locate and identify human faces will find several applications, some examples are criminal identification and authentication in secure systems. This work presents a new approach based on principal component analysis. Face silhouettes instead of intensity images are used for this research. It results in reduction in both space and processing time. A set of basis face silhouettes are obtained using principal component analysis. These are then used with a Hough-like technique to detect faces. The results show that the approach is robust, accurate and reasonably fast.
RECOGNITION OF UNCONSTRAINED HANDWRITTEN ENGLISH WORDS WITH CHARACTER AND LIGATURE MODELING
Authors: HA JIN-YOUNG , OH SE-CHANG , KIM JIN H.
Published: November 2004

In this paper, we proposed an approach for segmentation and recognition of unconstrained handwritten English words with character and ligature modeling. Viewing a handwritten word as an alternating sequence of characters and ligatures, a network of circularly interconnected hidden Markov models is constructed to model handwritten English words of indefinite length. Then the recognition problem is regarded as finding the maximal probability path in the network for given input sequence. From the path, optimal segmentation and associated character labels are obtained simultaneously without any explicit segmentation.
OPTOELECTRONIC LOGICAL-CIRCUITS CONTROLLED AUTOMOTIVE ELECTROLUMINESCENT DASHBOARD DISPLAY
Authors: PORADA ZBIGNIEW W.
Published: November 2004

In modern automotive vehicles, sophisticated measuring systems, which convert and display stored data to the driver, have been used. One of the basic problems is the mode of data transmission to the driver. A general usable mode for transmitting the driver's information is optical signalling which can be realized with the aid of electroluminescent dashboard displays. Automotive electroluminescent dashboard displays applied for data transmission may be controlled by optoelectronic logical circuits which are practically insensitive to electromagnetic interference. The most interesting are memory cells which contain two photoconducting (PC) and two electroluminescent (EL) units. Between a single EL unit and a single PC unit, optical feedback can be provided so that these two units constitute a bistable system. Experimental investigations of the above mentioned units will be presented.
ULTRA LIGHT ELECTRIC VEHICLES (EV)
Authors: WYCZALEK FLOYD A.
Published: November 2004

While this project reviewed the status of EV propulsion worldwide, and included European, American, and Japanese electric vehicles and the new Zebra sodium nickel chloride battery introduced by AEG of Daimler Benz at the September 1993 Frankfurt IAA motor show, and the November 1993 Tokyo motor show, this paper is limited in scope to showing results of a mathematical comparison which permits comparative assessment of 1993 EV automotive acceleration performance and the effects of vehicle configuration on the aerodynamic skin friction component of the total aerodynamic drag coefficient. Conclusions are: the major automobile manufacturers have been responsive, creative, and synergistic in developing and demonstrating significant improvements in acceleration performance and vehicle styling configuration strategies which may permit early deployment of ultralight electric vehicles with increased range. Consequently, the battery "Electric Vehicle" now has a brighter future.
ELECTRICAL VEHICLES IN THE CZECH REPUBLIC
Authors: CENEK M. , KAZELLE J. , NOR J. , VŠETEČKA L. , KOUDELÁK A.
Published: November 2004

This paper presents and evaluates the present state of advancement in the area of research and development, production and use of electromobiles in the Czech Republic.
GENERALIZED INSTANTANEOUS AMPLITUDE AND FREQUENCY FUNCTIONS AND THEIR APPLICATION FOR PITCH FREQUENCY DETERMINATION
Authors: FÖLDVÁRI RUDOLF
Published: November 2004

By defining an instantaneous frequency function it could be shown that if a signal is analytic, instantaneous frequency is analytic, too. A generalized instantaneous amplitude function could then be introduced which is also analytic in character. These functions — apart from an arbitrary constant phase — uniquely define the analytic time function. It could be proved that the transformation gives a true time-frequency representation which fulfills all the necessary requirements.

Moreover, the application of instantaneous parameters in connection with a Zwicker's filter bank makes it possible even to model human hearing. By applying a simplified hearing model, an efficient pitch-frequency detector able to decide between voiced-unvoiced signals with the same reliability as visual detection even at a 0 dB signal-to-noise ratio could be developed.
DIRECT-SEQUENCE SPREAD-SPECTRUM WITH TRANSFORM DOMAIN INTERFERENCE SUPPRESSION
Authors: KASPARIS TAKIS , GEORGIOPOULOS MICHAEL , MEMON QURBAN
Published: November 2004

The performance of a direct-sequence spread-spectrum (DS-SS) receiver employing new techniques for multiple non-stationary interference suppression is presented. These techniques are based on transform domain order statistics and they selectively suppress spectral components that are sufficiently large and narrow. Other important advantages are also discussed. The bit error rate performance is determined by Monte-Carlo simulations and it is compared to the performance of fixed notch filtering and of the well-known LMS algorithm. The effect of using data windowing is examined, and results with single-tone, narrow-band, stationary, non-stationary and multiple interference are presented. A comparison of the amount of computation required by the proposed transform domain approach to that of the time-domain LMS algorithm is also presented.
OPEN- AND CLOSED-LOOP DC AND SMALL-SIGNAL CHARACTERISTICS OF PWM BUCK-BOOST CONVERTER FOR CCM
Authors: KAZIMIERCZUK MARIAN K. , CRAVENS ROBERT
Published: November 2004

DC and small-signal circuit models of the PWM buck-boost converter for the continuous conduction mode (CCM) are derived. The models take into account parasitic components, such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor on-resistance, and the diode forward resistance and offset voltage. The component values and the parasitics were measured for a prototype converter. The dc voltage transfer function and the efficiency of the converter are derived from the dc model. Small-signal open-loop transfer functions are derived from the small-signal model. The derivation of the transfer function for an integral-lead controller with the loading effect of the voltage divider network in the feedback loop is given. Small-signal closed-loop transfer functions are derived. Bode plots are given for various transfer functions of the converter.
LOCAL AND GLOBAL STABILITY OF SWITCHING REGULATORS
Authors: CHUNG HENRY , IOINOVICI ADRIAN
Published: November 2004

A discrete-time model of closed-loop PWM regulators is derived to describe their dynamic behavior. No small-ripple approximations are required. The same model serves both local and global stability study: by discarding the nonlinear terms and using the z-transform, stability for small-signal perturbations is checked; by keeping the nonlinear terms (products of disturbances) and using the state-plane portrait, in which equilibrium points are located, stability for large-signal perturbations is studied. The theory is applied to a multiple feedback boost regulator operating in continuous conduction mode. Its local/global stability/instability for different values of the feedback gains is determined based on the new method.
APPLICATION OF SLIDING MODE CONTROL TO SWITCH-MODE POWER SUPPLIES
Authors: SPIAZZI G. , MATTAVELLI P. , ROSSETTO L. , MALESANI L.
Published: November 2004

Switch-mode power supplies represent a particular class of variable structure systems (VSS). Thus, they can take advantage of non-linear control techniques developed for this class of systems. In this paper the so called sliding mode control is reviewed and its application to switch-mode power supplies is discussed.

Sliding mode control extends the properties of hysteresis control to multi-variable environments, resulting in stability even for large supply and load variations, good dynamic response and simple implementation.

Application to dc–dc converters, as well as rectifiers and inverters, is analyzed and provisions to overcome the inherent drawbacks of sliding mode control, i.e. variable switching frequency and possible steady-state errors, are described. Experimental results are also reported, which allow a comparison between the sliding mode approach and other standard control techniques, e.g. current-mode control, showing its effectiveness.
PHYSICAL MODELING OF POWER SEMICONDUCTORS FOR THE CAE-DESIGN OF POWER ELECTRONIC CIRCUITS
Authors: VOGLER THOMAS , SCHRÖDER DIERK
Published: November 2004

CAE-tools can help to develop any traditional or novel power conversion topology more efficiently, by providing both the possibilities of investigation without the risk of destruction and of access to each signal in the circuit. However, a prerequisite are trustworthy simulation results both qualitatively for operation observation and quantitatively for power dissipation examination as well as for SOA control. This implies that precise power semiconductor models have to be used. In the variety of different possible modeling strategies there is only the strictly physical way which offers topology independent accurate results.

In this paper a new class of physical high performance and high accuracy circuit models for today's relevant power semiconductors (Power-Diode, GTO, IGBT, Power-MOSFET) is presented. A modular concept, handling typical features of power devices like ν-zones, MOSFET controlling units or diffusion zones as basic structures, is used which allows a considerable flexibility to model future devices time efficiently. The core of this modular concept, constituted by a module of the ν-zone, employs a universal and powerful solution technique of the ambipolar diffusion equation. This technique is the only possibility for circuit models to consider physically semiconductor technology measures for improving device characteristics, such as particle irradiation for lifetime reduction, step doping of substrate or epitaxial layers as well as double diffused layers.
PUSHING STANDARD CMOS TECHNOLOGIES INTO SMART POWER CONVERSION AND AMPLIFICATION
Authors: FINCO S. , BEHRENS F. H. , GUILHERME J. , CASTRO SIMAS M. I. , LANÇA M.
Published: November 2004

A smart power integrated circuit to be fabricated with standard CMOS technologies was developed in view to obtain a versatile, high performance and low cost basic building block, suitable for a wide range of low power applications. This circuit merges together two transistors, connected in a low-side/high-side switch configuration, with specific control and protection circuitries. These transistors are NMOS medium-voltage lateral structures, which use the lightly doped drain concept and are targeted to handle currents up to 2 A and to support 25 V at OFF state.

Experimental results on different applications and topologies show the applicability of the smart switching cell on portable systems power supplies and amplifiers (up to 20 W). Its performance also proves the ability of standard CMOS technologies to implement smart power circuits.
SOFT-SWITCHING PWM CONVERTER TECHNOLOGIES
Authors: HUA GUICHAO , LEE FRED C.
Published: November 2004

The switched-mode power conversion technologies have evolved from the basic PWM converters to resonant converters, quasi-resonant converters, multi-resonant converters, and most recently, to soft-switching PWM converters. In this paper, several typical resonant techniques and several soft-switching PWM techniques are reviewed, and their merits and limitations are assessed. The resonant techniques reviewed include the quasi-resonant converters, multi-resonant converters, Class-E converters, and resonant dc link converters; and the soft-switching PWM techniques reviewed include the zero-voltage-switched (ZVS) quasi-square-wave converters, ZVS-PWM converters, zero-current-switched PWM converters, zero-voltage- transition PWM converters, and zero-current-transition PWM converters.
REVERSE RECOVERY OF POWER pn JUNCTION DIODES
Authors: KAZIMIERCZUK MARIAN K.
Published: November 2004

A quasi-steady state approximation is used to derive expressions for the waveforms of minority carrier charge stored in p+nn+ power junction diodes driven by large-signal sinusoidal and ramp voltages. These waveforms are derived by solving a diode charge-control differential equation. Using the charge waveforms, the storage time is determined and the diode current and voltage waveforms are predicted. It is shown that three frequency ranges can be distinguished: (1) low-frequency range in which the reverse recovery is negligible, (2) mid-frequency range in which the reverse recovery is detrimental, but the diode is still of practical value, and (3) high-frequency range where the diode does not exhibit its rectifying properties. A simple method for measuring the minority carrier lifetime is proposed. Experimental results are given for an MR826 fast-recovery pn junction diode and a 31DQ06 Schottky diode for operating frequencies of up to 10 MHz. The theoretical and experimental results were in good agreement.
APPLICATION OF A BOOST RECTIFIER IN A HIGH PERFORMANCE DC DRIVE
Authors: RODRÍGUEZ J. , SUÁREZ A. , HERNÁNDEZ J. , ANDRADE H. , WIECHMANN E.
Published: November 2004

This paper presents the use of a single-phase voltage-doubler Boost rectifier, to generate a controlled DC voltage, which is applied to a four-quadrant chopper. The transistor chopper controls the speed of a separately excited DC machine.

The Boost rectifier permits the regeneration of energy from the motor to the single-phase mains, maintaining in all operating points a practically sinusoidal input current, with a THD of 2.5%.

The balancing of the two filter capacitors is achieved by using and additional control loop. A low cost microcontroller is used to control the DC voltage and the motor speed.
HARMONIC REDUCTION IN SINGLE-PHASE DIODE RECTIFIER CIRCUITS USING A SWITCH-CONTROLLED INDUCTOR
Authors: SARV VELLO
Published: November 2004

A novel design principle of a low-distorted single-phase rectifier using, instead of a time-variable transformer, an appropriate time-variable inductor is proposed and analyzed. Such a rectifier circuit contains a diode bridge, a switch-controlled current-shaping inductor, and a time-invariant smoothing capacitor. From the point of view of energy flow, the distortion reduction is based on the improvement of energy transfer and exchange processes. In the proposed circuit, the switch-controlled inductor realizes an appropriate controlled current source converting the active power of the second and other even harmonics into direct-current power. To implement the ideal undistorted rectification, continuous inductance variation is needed. Nevertheless, the suitable stepped variation of inductance enables us to synthesize diode rectifiers with the high power factor even using only the simplest diode switches.
MULTI-VALUED CONSTANT PROPAGATION ANALYSIS FOR USER INTERFACE REENGINEERING
Authors: MERLO ETTORE , GIRARD JEAN-FRANCOIS , HENDREN LAURIE , DE MORI R.
Published: November 2004

The definition and use of multi-valued constant propagation analysis (MVCP), which is an extension of simple constant propagation analysis, is presented in this paper in the context of a user interface reengineering process.

A brief description of the adopted COBOL/CICS user interface reengineering model, which makes use of an Abstract User Interface Description Language (AUIDL) to represent user interface structures and behavior, is also given.

The experimental context is described and results are shown and discussed. Suggestions for further directions of research and investigation are also presented.
HOW TO COMBINE NONMONOTONIC LOGIC AND RAPID PROTOTYPING TO HELP MAINTAIN SOFTWARE
Authors: LUQI  , COOKE DANIEL E.
Published: November 2004

This paper explores the possibility of automated support for detecting inconsistencies in software systems and requirements. The inconsistencies are introduced when the environment of the software system changes. We refer to the software environment as its context. We review the recent research progress on nonmonotonic logics, pointing out the significance of these results to software maintenance. We explain how a practical implementation of such logics can be obtained via a simple extension to logic programming in the form of an answer procedure that realizes the Extended Logic Semantics [7] for nonmonotonic logic programs that have a unique answer set (which is a large and useful class of logic programs).

We augment the existing automated capabilities of the Computer-Aided Prototyping System (CAPS) for rapid prototyping via the extension to logic programming to provide an improved automated capability for detecting certain kinds of inconsistencies created by implicit requirements changes. We illustrate the significance of this capability via an example prototype for a problem originally suggested by Lehman.
APPLYING CONCEPT FORMATION METHODS TO SOFTWARE REUSE
Authors: GODIN ROBERT , MINEAU GUY , MISSAOUI ROKIA , ST-GERMAIN MARC , FARAJ NAJIB
Published: November 2004

This paper describes an approach to software reuse that involves generating and retrieving abstractions from existing software systems using concept formation methods. The potential of the approach is illustrated through two important activities of the reuse process. First, the concept hierarchy generated by the concept formation methods is used for organizing and retrieving the artifacts inside a repository. Second, the generated concepts are used in identifying new abstractions that may be converted into new, more generic artifacts with better reuse potential. These experiments are part of a major software engineering research project involving many business and academic partners.
AUTOMATIC PROGRAMMING AND PROGRAM MAINTENANCE WITH GENETIC PROGRAMMING
Authors: PETRY FREDERICK E. , DUNAY BERTRAND DANIEL
Published: November 2004

Automatic programming is discussed in the context of software engineering. An approach to automatic programming is presented, which utilizes software engineering principles in the synthesis and maintenance of programs. As a simple demonstration, program-equivalent Turing machines are synthesized, encapsulated, reused, and maintained by genetic programming.

Turing machines are synthesized from input-output pairs for a variety of simple problems. When a problem is solved, the solution is encapsulated and becomes part of a software library. The genetic program uses the library to solve new problems by combining library components with program primitives to synthesize new programs. When a new problem is solved or a known problem is solved more efficiently, the genetic program maintains the library so as to keep it valid and efficient.
AN EVOLUTIONARY APPROACH TO PROGRAM TRANSFORMATION AND SYNTHESIS
Authors: CHO SUNG-BAE , RAY THOMAS S.
Published: November 2004

Efficiency is a problem in automatic programming, both in the programs produced and in the synthesis process itself. This paper presents a framework for using evolutionary mechanisms to guide program synthesis. A particular implementation of the framework, called Tierra, is described. Given a naive program and some limits on system resources, Tierra generates mutated programs and evolution proceeds by natural selection as the programs compete for Control Processing Unit (CPU) time and memory space. By applying the evolutionary mechanisms, Tierra has guided the automatic implementation of an efficient self-replicating program. The system is under continuing development; it is viewed more as a research tool than a prototype programming assistant; however, the performance of the system at present gives some hope for the ultimate feasibility of such systems.
GENERATING DATA ACCESS PROGRAMS FROM PCTE SCHEMAS WITH CONSTRAINTS
Authors: SAWADA ATSUSHI , MITSUDA NARUKI , AJISAKA TSUNEO , MATSUMOTO YOSHIHIRO
Published: November 2004

This paper presents how we developed a tool for generating data access programs from PCTE data schemas. We propose first an extended PCTE data model which allows constraints to be explicitly described between values of the data types. Our program generator analyzes this data model, which we call the constrained SDS, and generates a C++ library. A class of C++ is generated from each object type defined in the constrained SDS, and a set of member functions is generated from attribute types, link-types, and constraints defined in the SDS. The library provides convenient ways for accessing data which are stored according to the given constrained SDS. An example shows the benefits of using the program generator for tool development in PCTE.
COOAD: A CASE TOOL FOR OBJECT-ORIENTED ANALYSIS AND DESIGN
Authors: YAMAMOTO JUNICHI , OHSUGA AKIHIKO , HONIDEN SHINICHI
Published: November 2004

Although many CASE tools for object-oriented methods (OO CASE tools) have been proposed, few, if any, can verify that the constructed analysis and design models actually match the requirements of the system being developed. In order to realize this kind of verification, we propose a software development method amalgamating OO CASE tools and algebraic specification techniques. We are developing an experimental system named COOAD (CASE tool for Object-Oriented Analysis and Design) in order to examine the effectiveness of our proposition. COOAD supports object-oriented analysis and design, verification of the analysis and design, and generation of code. In this paper, we propose the software development method, introduce COOAD, and illustrate the facilities of COOAD with an example.
WHEN TO INHERIT AND WHEN NOT TO
Authors: KUO Y. S.
Published: November 2004

In object-oriented software development, it is generally accepted that inheritance should be used just to model a generalization/specialization relationship (i.e., an IS-A). This analysis/design guideline is too permissive. Some researchers thus advocate that a subclass should inherit the full behavior of its superclass. Behavior inheritance, however, is far too restricted. In this paper, we establish a formal model that can clearly differentiate IS-A from behavior inheritance. Under this model, IS-A and behavior inheritance can be decomposed into more fundamental concepts: subset and abstraction/concretization. Also, we are able to develop a set of refined guidelines regarding the use of inheritance.
PARTS: A TEMPORAL LOGIC-BASED REAL-TIME SOFTWARE SPECIFICATION METHOD SUPPORTING MULTIPLE VIEWPOINTS
Authors: KANG KYO C. , KO KWANG-IL
Published: November 2004

Areas of computer application are being broadened rapidly due to the rapid improvement of the performance of computer hardware. This results in increased demands for computer applications that are large and have complex temporal characteristics.

This paper introduces a real-time systems anlaysis method named PARTS. PARTS supports analyses from two viewpoints: external viewpoint, a view of the system from the user's perspective, and internal viewpoint, a view from the developer's perspective. These viewpoints are specified using formal languages, which are Real-Time Events Trace (RTET) for the external viewpoint, and Time Enriched Statechart (TES) and PARTS Data Flow Diagram (PDFD) for the internal viewpoint. All PARTS languages are based on the Metric Temporal Logic (MTL), and consistency of the specifications made from the two different viewpoints are analyzed based on the same MTL formalism.
TOWARDS AN OPEN SOFTWARE CONVERSION ARCHITECTURE
Authors: BAILES PAUL A. , ATKINSON STEVEN , CHAPMAN MURRAY , JOHNSTON DAN , PEAKE IAN
Published: November 2004

A generic architecture for the development and application of software conversion tools exposes the requirements set for appropriate enabling technologies. Extrapolation of this set beyond its satisfaction by existing proprietary technology then exposes the opportunity/need for open interfaces between separate components providing orthogonal dimensions of the overall functionality. Some novel aspects of the solutions considered include retrofitting persistence to an open compiler-compiler, and using the Unix file system as a persistent object store, while in the background the advent of standard interfaces to persistence technology suggests that the overall goal is feasible.
TRENDS IN LIFE-CYCLE MODELS FOR SE AND KE: PROPOSAL FOR A SPIRAL-CONICAL LIFE-CYCLE APPROACH
Authors: ALONSO F. , JURISTO N. , PAZOS J.
Published: November 2004

The ten-year gap between the emergence of Software Engineering (SE) and Knowledge Engineering (KE) has led to the two disciplines developing along different methodological lines. In this paper, we point out that, after having passed through a period during which they ignored each other, followed by a competitive phase, the two disciplines have now reached a meeting point. We see the need for a life-cycle model for systems that integrate traditional and knowledge-based software. Besides, software development in the 21st century will entail open requirements and technological tools that will evolve during the life-cycle. Finally, the paper discusses a proposal for a conical-type spiral life-cycle model that seeks to meet all those needs.
FACT UPDATES IN LOGIC DATABASES
Authors: HUANG YAN-NONG , DAHL VERONICA , HAN JIAWEI
Published: November 2004

A logic database has two components. One comprises the base knowledge, represented explicitly, called the extensional base. The other stores more general knowledge in the form of derivation rules, and is called the intensional base. One may calculate derived facts in advance and store (or materialize) them. Thus, the response time can be expected to speed up.

In this paper, we study a new evaluation technique for incrementally maintaining derived facts whenever updates occur on base facts. Our method is based on the seminaive evaluation so it is easy to implement; it is set-oriented, multiple updates may be dealt within a single manipulation; and insertion and deletion are treated uniformly. The method is evaluated analytically as well as experimentally.

We indicate the potential application of our incremental method to a computational linguistic problem, i.e., parsing incomplete sentences.

Related work in both areas of logic databases and computational linguistics are discussed.