bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular neural network for fast adaptive equalization
Authors: Perfetti Renzo 
Published: July 2007

AbstractThe use of an analogue neural network in the adaptive equalization of time‐varying communication channels is proposed. the network is used to compute the coefficients of a linear transversal filter. the settling time decreases as the filter order increases and as the signal‐to‐noise ratio decreases. Owing to the real‐time processing capabilities, the network can be useful when it is of interest to track fast variations, as in radio links. the special properties of the tap input correlation matrix result in a cellular network architecture which greatly simplifies the VLSI implementation. Simulation results are presented which point out very satisfactory performance.
Circuit theoretic approach to the tank‐hopfield A/D converter
Authors: Martinelli G. , Perfetti R. 
Published: July 2007

AbstractThe ‘neural’ A/D converter of Tank and Hopfield is analysed from the viewpoint of circuit theory. It is shown to be a particular case of the canonical non‐linear programming circuit of Chua and Lin. Several qualitative properties concerning the DC solutions are proved. A piecewise‐linear analysis of trajectories in the state space is carried out on the basis of the eigenvalues and eigenvectors of the corresponding dynamical matrix. It is shown that the eigenvalues are related to the driving point impedance of an RC one‐port network. Asymptotic expressions of the eigenvalues are derived for large N, N being the number of bits. It is shown that the dynamic behaviour represents a sort of successive‐approximation A/D conversion. However the conversion time does not increase appreciably as the number of bits increases. the cases of incorrect behaviour and the amount of the maximum conversion error are derived for N > 5. Simulation results are presented for N ≤ 5.
Switched capacitor circuit for 1/f noise generation using a power‐law circuit
Authors: Murao Kenji , Kohda Tohru 
Published: July 2007

AbstractA simple switched capacitor (SC) circuit is given which realizes a one‐dimensional discrete dynamical system Xn+1 = Xn + uxz generating intermittent chaos with a 1/f‐shaped power spectrum. an integrated circuit with a pair of logarithmic and antilogarithmic amplifiters can easily realize the power‐law term xz which plays a key role in generating l/fnoise. an inevitable small offset voltage ϵ in the SC circuit governs the cut‐off frequency of 1/f noise, and when the dynamical system is modified by introducing an effective ϵ, the ‘indirect method’ enables us to get the precise power spectrum in the modified system.
Chaos from a buck switching regulator operating in discontinuous mode
Authors: Tse C. K. 
Published: July 2007

AbstractA first‐order iterative map which describes the dynamics of a simple feedback buck switching regulator operating in discontinuous mode is derived. Analysis of this map shows that flip bifurcations occur at certain values of the feedback factor. Results from computer simulations and experiments reveal that the system exhibits a typical perioddoubling route to chaos under the particular operating condition studied in this paper. It is found that a special kind of randomness, arising from the ability of the system to ‘merge’ and ‘skip’ periods, constitutes a unique feature of the chaotic dynamics of switched‐mode converter circuits.
Exact solutions of cyclically symmetric oscillator equations with non‐linear coupling
Authors: Fox David 
Published: July 2007

AbstractKaplan and Yardeni have found very simple exact limit cycle solutions in cyclically symmetric systems of N oscillator equations with linear coupling in zero order of a perturbation parameter and non‐linear coupling in first order. In contrast with such solutions in other non‐linear systems, each of these limit cycles is a normal mode of the unperturbed equations, with no change in frequency. the sources of this simple behaviour are studied here with the equations expressed in terms of the normal mode co‐ordinates of the unperturbed system rather than in the original co‐ordinates. It is found that the simplicity of the Kaplan‐Yardeni solutions arises partly from an additional symmetry of the perturbation terms beyond the cyclic symmetry and partly from the specific choices of the perturbations. Extension of their systems to arbitrary N leads to the result that all such sets of equations have similar simple limit cycles. More general cyclically symmetric sets of equations are also discussed, with limit cycle solutions whose frequencies are shifted from the zero‐order values by easily calculated amounts or with solutions which are linear combinations of zero‐order normal modes.
A general approach to circuit equations
Authors: Tuma T. , Bratkovič F. 
Published: July 2007

AbstractComputer‐aided circuit analysis is a complex procedure which may be roughly divided into three steps. the first stage is device modelling, where quantitative properties of the participating electronic devices are determined. In the second step the circuit's topology in conjunction with the device equations is exploited in order to formulate a linearized nonsingular equation set. Eventually the equation set is solved iteratively in the third phase, yielding a solution vector of circuit variables.This paper deals with the second and third steps, where diverse sparse matrix methods are employed. Its aim is to provide a general mathematical form by which most matrix manipulation techniques can be described, thus enabling their classification on a theoretical level. Usually these methods are presented descriptively rather than strictly mathematically.The paper introduces a matrix reduction operator from which a general matrix operator equation is deduced. This operator equation can be used to describe entire analysis approaches. After some necessary definitions, the purpose of this paper is illustrated by studying several classical examples rather than giving many mathematical proofs. the selected examples involve some well‐known linear equation set solution methods as well as several typical equation set transformations.
A state space approach to the tangential interpolation problem with bounded real matrices
Authors: Piekarski Marian S. , Uruski Marceli 
Published: July 2007

AbstractThis paper presents a global solution of the tangential interpolation problem via state space concepts. the solution is obtained in two steps. the first step consists of factorization of the Nevanlinna‐Pick matrix and calculating the state space vectors of a passive n‐port network N. In the second step, using the state space vectors and the interpolation data, a passive minimal state space realization of N is derived from which the desired interpolating bounded real matrix is obtained. the presented approach involves only standard algebraic matrix procedures and provides the constructive algorithm for the interpolating matrix.
Simplified impedance broadband matching by the image parameter method: The RC case
Authors: Dehollain Catherine , Neirynck Jacques 
Published: July 2007

AbstractThe image parameter theory is now considered as outdated for filter design owing to the existence of very efficient optimization procedures for the effective behaviour of filters. Nevertheless, it allows one to exhibit very simple relations between the bandwidth and the values of the components. Hence it is ideally suited for the problem of impedance broiband matching where the bandwidth and some components are specified data. It is shown that it allows to make a straightforward distinction between well‐ and ill‐conditioned problems. In the first case the problem is reduced to a one‐dimensional optimization and an image parameter design provides very easily an equalizer optimal for all practical purposes. In the second case the values of the image parameter design provides excellent initial values for an optimization process.The method is applied here to the simplest problem, the RC load. In a separate paper it will be shown that it is easily extended to more complicated loads and the double‐matching problem.
Meixner‐like functions having a rational z‐transform
Authors: Brinker A. C. Den 
Published: July 2007

AbstractSquare‐summable causal functions can be expressed in a Meixner series. In principle, approximate filter synthesis is thus possible. However, Meixner filters are not realizable since the Meixner functions do not have a rational z‐transform. A set of orthonormal functions is constructed with the following properties. Like the Meixner functions, these functions are a generalization of the discrete Laguerre functions and they have a polynomial character as well. In contrast with the Meixner functions, they have the desired property of a rational z‐transform.
An analogue module generator for mixed analogue/digital asic design
Authors: Gielen G. , Debyser G. , Lampaert K. , Leyn F. , Swings K. , Van Plas G. Der , Sansen W. , Leenaerts D. , Veselinovic P. , van Bokhoven W. 
Published: July 2007

AbstractThis paper discusses the realization of an analogue module generator that forms part of a mixed analogue/digital design environment. It is able to design analogue functional modules such as like amplifiers, filters, etc., either in an automatic or in an interactive session, starting from performance specifications over topology selection, parameter optimization and simulation/verification down to lay‐out. the analogue module generator is integrated in a commercial EDA framework. Practical design results show the capabilities and efficiency of the system.
A discrete‐time approach to the steady state analysis and optimization of non‐linear autonomous circuits
Authors: Palà‐schönwälder Pere , Mirö‐sans J. M. 
Published: July 2007

AbstractIn this paper a method for the steady state analysis and optimization of non‐linear autonomous circuits is described. After discretizing the linear part of the circuit, a system of non‐linear algebraic equations is obtained. the final formulation is written entirely in the discrete‐time domain, making it unnecessary to repeatedly take direct and inverse DFTs during the solution process. Furthermore, it is shown that the resulting formulation may be viewed as a generalization of the harmonic balance equations. an analytic method for computing the exact partial derivatives of the resulting equations with respect to the samples of the variables, the oscillation period and the circuit element values is described, making the proposed approach efficient for both analysis and optimization. Different globally convergent techniques for solving the non‐linear system of equations are described, with emphasis on an algorithm based on fast simulated diffusion. Selected application examples are provided to validate the proposed approach.
Symbolic compaction with analogue constraints
Authors: Malavasi Enrico , Felt Eric , Charbon Edoardo , Sangiovanni‐Vincentelli Alberto 
Published: July 2007

AbstractA tool named SPARCS‐A for compaction of integrated circuits with analogue constraints is presented. the approach is structured in two steps. First a robust and efficient constraint graph compaction algorithm produces a compacted layout quickly, where parasitics are controlled so as to guarantee that the performance constraints are met. Next the layout produced by the first step is fed into a linear programming (LP) solver which enforces symmetries and performs global interconnect length minimization. the computational cost of the iterative LP solver is modest, because its initial state is the configuration found by the constraint graph algorithm and only symmetry constraints need to be enforced. With considerable computational efficiency this algorithm produces a compacted layout which satisfies the high‐level performance constraints and is feasible for practical use within industrial‐strength analogue synthesis systems. the use of such a compactor allows one to relax the requirements on parasitic control during placement and routing, thus improving the efficiency of the entire layout design process.
The analogic cellular neural network as a bionic eye
Authors: Werblin Frank , Roska Tamás , Chua Leon O. 
Published: July 2007

AbstractThe conception of the CNN universal machine has led quite naturally to the invention of the analogic CNN bionic eye (henceforth referred to simply as the bionic eye). the basic idea is to combine the elementary functions, the building blocks, of the retina and other 2 1/2 D sensory organs, algorithmically, in a stored programme of a CNN universal machine, through the use of artificial analogic programmes. the term bionic is defined in a rigorous way: it is a nonlinear, dynamic, spatiotemporal biological model implemented in a stored programme electronic (optoelectronic) device; this device is in our case the analogic CNN universal machine (or chip).The aim of this paper is to report on this new invention, particularly to electronic and computer engineers, in a tutorial way.We begin by summarizing (1) the biological aspects of the range of retinal function (the retinal universe), (2) the CNN paradigm and the CNN universal machine architecture and (3) the general principles of retinal modelling in CNN. Next we describe new CNN circuit and template design innovations that can be used to implement physiological functions in the retina and other sensory organs using the CNN universal machine. Finally we show how to combine given retinal functional elements implemented in the CNN universal machine with analogic algorithms to form the bionic retina. the resulting system can be used not only for simulating biological retinal function but also for generating functions that go far beyond biological capabilities. Several bionic retina functions, different topographic modalities and analogic CNN algorithms can then be combined to form the analogic CNN bionic eye. the qualitative aspects of the models, especially the range of dynamics and accuracy considerations in VLSI optoelectronic implementations, are outlined. Finally, application areas of the bionic eye and possibilities of constructing innovative devices based on this invention (such as the bionic eyeglass or the visual mouse) are described.
Simultaneous generation of fra‐2 conditional and fra‐2 knock‐out mice
Authors: Eferl Robert , Zenz Rainer , Theussl Hans‐Christian , Wagner Erwin F. 
Published: July 2007

AbstractLoss of function mouse models comprise knock‐out mice, where a gene is deleted in the germline, and conditional knock‐out mice with somatic deletion of a floxed allele in defined tissues. Both types of mice are used for comprehensive studies of gene functions in vivo. Here, we describe a simple method for simultaneous generation of mice with conditional or knock‐out alleles for the transcription factor fra‐2 (Fos‐related antigen 2) using a single embryonic stem (ES) cell clone. ES cells with a floxed fra‐2 allele were transiently transfected with a Cre‐recombinase expression plasmid and plated at low density. Most of the resulting ES cell colonies consisted of a mixture of cells that have either retained or lost the conditional allele. We demonstrate that these mixed ES cell clones can be directly used for generation of chimeras that give rise to offspring with conditional or knock‐out alleles simultaneously. This strategy shortens the time and reduces the number of germline transmission events to generate genetically modified mice. genesis 45:447–451, 2007. © 2007 Wiley‐Liss, Inc.
When positive and negative expectancies disrupt performance: regulatory focus as a catalyst
Authors: Keller Johannes , Bless Herbert 
Published: July 2007

AbstractThe present research investigates the impact of negative and positive stereotypic expectancies on cognitive test performance. A theoretical framework that relates expectancy effects to self‐regulatory processes as postulated by Regulatory Focus Theory (RFT) is presented. Building on the differential sensitivity hypothesis proposed in this theoretical model, we argue that when self‐regulation in a prevention focus is activated individuals are particularly sensitive with regard to negative cues and therefore negative expectancies are likely to result in poor test performance due to an apprehension about meeting minimal goal standards. Conversely, when self‐regulation is guided by a promotion focus individuals are particularly sensitive with regard to positive cues and hence likely to show impaired performance when confronted with positive expectancies due to an apprehension about meeting maximal goal standards. The results of four experiments, relying on both situational and chronic regulatory focus, support these assumptions. Copyright © 2007 John Wiley & Sons, Ltd.
Coating of open tubular capillaries with discoidal and spherical high‐density lipoprotein particles in electrochromatography
Authors: Vainikka Kati , Chen Jie , Metso Jari , Jauhiainen Matti , Riekkola Marja‐Liisa 
Published: July 2007

AbstractA new method was developed for the coating of fused‐silica capillaries with human high‐density lipoproteins (HDLs) for use in electrochromatography. The HDL particles used for the coating differed in particle shape and composition. Both discoidal and spherical particles formed a monolayer on the inner silica wall as confirmed by atomic force microscopy. The effect of coating conditions, such as HDL concentration and coating time, was investigated with spherical HDL particles. Examination of the influence of pH on the coating stability also allowed the determination of pI values for the HDL particles attached to the capillary wall. The pI values for spherical and discoidal HDL particles were close to 5.0. The repeatabilities of the EOF mobility and the retention factors of the uncharged steroid hormones used as model compounds were exploited in the evaluation of the coating stability. The optimal coating was achieved with 0.1 mg/mL HDL protein and 50 min flushing with coating solution followed by 15 min standing time. Electrochromatography with HDL‐coated open tubular capillaries offers a new tool for the study of HDL particle structure and transformations.
Voltage‐assisted capillary LC of peptides using monolithic capillary columns prepared by ring‐opening metathesis polymerization
Authors: Sedláková Pavla , Miksik Ivan , Gatschelhofer Christina , Sinner Frank M. , Buchmeiser Michael R. 
Published: July 2007

AbstractWe examined the use of monolithic capillary columns prepared via ring‐opening metathesis polymerization (ROMP) for peptide separation in voltage‐assisted capillary LC (voltage‐assisted CLC). In order to demonstrate their potential for peptide separation, ROMP‐derived monoliths with RP properties were prepared. The preparation procedure of monoliths was transferred from ROMP monoliths optimized for CLC. ROMP monoliths were synthesized within the confines of 200 μm id fused‐silica capillaries with a length of 37 cm. After optimization of the chromatographic conditions, the separation performance was tested using a well‐defined set of artificial peptides as well as two peptidic mixtures resulting from a tryptic digest of BSA as well as a collagenase digest of collagen. ROMP monoliths showed comparable performance to other monolithic separation media in voltage‐assisted CLC published so far. Therefore, we conclude that by optimizing the composition of the ROMP monoliths as well as by using the controlled manner of their functionalization, ROMP monoliths bear a great potential in CLC and CEC.
Carer burden in dementia—assessing the impact of behavioural and psychological symptoms via self‐report questionnaire
Authors: Neil Wendy , Bowie Peter 
Published: July 2007

AbstractBackgroundThe relationship between the behavioural and psychological symptoms of dementia (BPSD) and negative outcomes in carers has been consistently demonstrated, however the quality of the assessment of the former in routine clinical settings is variable and validated interview‐based scales are frequently underutilised.AimsTo develop a carer self‐report questionnaire, the Behavioural and Psychological Symptoms Questionnaire (BPSQ), for the assessment of the neuropsychiatric symptoms of dementia and associated carer distress.MethodThe BPSQ was administered to the carers of 30 community‐dwelling older adults with diagnoses of Alzheimer's or vascular dementia and the results compared with interview assessment using the Neuropsychiatric Inventory (NPI).ResultsBPSD were present in 96.2% of patients. There was strong correlation (rs = 0.61, p < 0.001) between the BPSQ and interview with respect to measures of symptom frequency and severity. However, there was significant divergence between the two assessment schedules with respect to carer distress which was found to be significantly under‐reported in the initial interview (U = 64.00, z = −5.22, p < 0.0001).ConclusionsThe BPSQ is an effective tool to complement clinical interview in the assessment and monitoring of BPSD, and provides useful additional information with respect to carer distress, which currently may be under recognised. A follow‐up study is required to complete the work of validating the BPSQ. Copyright © 2007 John Wiley & Sons, Ltd.
Environmental controls on evapotranspiration from sparse grassland in Mongolia
Authors: Zhang Yinsheng , Kadota T. , Ohata T. , Oyunbaatar D. 
Published: July 2007

AbstractEnvironmental controls on evapotranspiration were investigated at a sparse grassland in Mongolia during 2003 and 2004. The study site was located on the southern periphery of the Eurasian cryosphere. Data from Eddy covariance, aerodynamic, and manual measurements were used in the analysis. A decoupling factor (Ω) was calculated to determine the relative importance of surface conductance and radiation to change in evapotranspiration rates. Higher evapotranspiration rates associated with a higher frequency of large Ω values revealed the importance of radiation forcing on evapotranspiration at this study site. As Ω increases', the aerodynamic conductance (ga) increased correspondingly but vegetation conductance (gC) decreased. Aerodynamic conductance (ga) was well fitted to an exponential function of the wind stress; gC clearly decreased as the vapour pressure deficit (d) increased; gC related to air temperature through d. Although grass cover was sparse at the study site, the anticipated effect of soil moisture on E and gS was only slightly suggested and thus not deducible. On the 10‐day‐interval time scale, the effect of vegetation cover on evapotranspiration was insignificant compared to that of surface soil moisture. Changes in soil evaporation, related to precipitation, mainly caused the very large inter‐annual differences in evapotranspiration. The relationship between evapotranspiration and surface bulk resistance at the study site could therefore be fit to an exponential function. Copyright © 2007 John Wiley & Sons, Ltd.
Wind direction dependency of water and energy fluxes and synoptic conditions over a tundra near Tiksi, Siberia
Authors: Kodama Yuji , Sato Norifumi , Yabuki Hironori , Ishii Yoshiyuki , Nomura Mutsumi , Ohata Tetsuo 
Published: July 2007

AbstractIn order to better understand the water cycle over tundra, micro‐meteorological observations were carried out over tundra near Tiksi, northeastern Siberia, and seasonal variations in the energy budget components were estimated for a period of 2 years. As an average for 1998 and 1999, net radiation was partitioned into a sensible heat flux of 25–30%, to a latent heat flux of 50–55%, and to a soil conductive heat flux of 15–25%. These ratios were changed by wind direction. The southwesterly winds were warm and dry, reducing sensible heat flux or changing its direction towards the ground surface, while northeasterly winds were cold, resulting in a sensible heat flux into the atmosphere from the tundra surface. Southwesterly winds were associated with cyclone intrusions into this area, and northeasterly winds were associated with anti‐cyclones. More frequent intrusions of cyclones would decrease the sensible heat flux and increase the latent heat flux. Copyright © 2007 John Wiley & Sons, Ltd.