bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of a notch filter with improved performance
Authors: Agarwal Rajeev , Plotkin E. I. , Swamy M. N. S. 
Published: July 2007

AbstractThe frequency response of a constrained notch filter (CNF) of Rao and Kung or Nehorai becomes ideal as the polecontraction factor α approaches unity while the transient duration approaches infinity. However, for practically useful values of α the phase and magnitude distortions so caused can reduce the allpass nature of the CNFs (i.e. the transparency property) and cause large errors. In this paper we define a measure for the transparency misadjustment and propose two suboptimal methods of minimizing these distortions. One of these methods is based on increasing the filter order by a strategic pole/zero placement. We present a closed‐form solution for this method. In the second method we increase the order by manipulating the error filter associated with the standard CNF; the coefficients of the resulting filter are determined directly. an important feature of these methods is the significant improvement in the transient performance.
Piecewise‐linear analysis of the Wien Bridge Oscillator
Authors: Perfetti R. 
Published: July 2007

AbstractThis paper presents a quantitative analysis of the Wien bridge oscillator based on a piecewise‐linear approximation of the op‐amp characteristic. Usually the circuit parameters are chosen in such a way that the linearized circuit has a pair of complex conjugate natural frequencies which lie slightly to the right of the jw‐axis. the frequency of oscillation is assumed to coincide with the value jω0 at which the poles cross the jω‐axis. However, this simplified approach is unable to predict the true frequency of oscillation and the amount of distortion. the aim of the present analysis is to determine the exact waveform, frequency and spectral content corresponding to the steady state behaviour. the phase plane is partitioned into three regions, in each of which the vector field is linear. the limit cycle corresponding to the steady state oscillation is reconstructed by using the Poincaré map method. Expressions for the frequency of oscillation and the Fourier coefficients are given which depend on a critical parameter representing the voltage gain of the amplifier.
On a self‐optimizing algebraic approach to symbolic analysis
Authors: Stefański Czeslsaw 
Published: July 2007

AbstractIn this paper a new approach to the symbolic analysis of linear networks is presented. A computer programme based on this approach is briefly described. It is shown that this method in computer applications considerably reduces the number of operations needed, the number of components in the final results and thus the computer time. the method is based on the tableau description of the analysed closed network. Descriptions of elements of the network are optimally chosen successively during the operation of the algorithm. the method presented seems to be the best so far among direct methods of fully symbolic analysis and considerably enhances the possibility of such an analysis.
Design of two‐dimensional scaled state space filters with fixed point arithmetic
Authors: Fahmy M. F. , Abo‐Zahhad M. , El‐Raheem G. A. 
Published: July 2007

AbstractIn this paper a new synthesis method has been proposed for the design of 2D scaled state space filters with fixed point arithmetic. It is based on constructing a non‐singular transformation matrix which minimizes the output noise power and maintains the signal‐scaling condition, besides zeroing some of the entries of the state matrices. As a result, simultaneous savings in both additions and multiplications are achieved. Numerical results are included to illustrate the performance of the proposed structures and to compare them with other structures.
Small‐signal harmonic analysis of non‐linear circuits
Authors: Jokinen Hannu , Valtonen Martti 
Published: July 2007

AbstractAn approximate harmonic analysis method for non‐linear circuits is introduced. the method solves the steady state, time domain representation as well as the frequency response of non‐linear circuits. It allows simulation of non‐ideal switched capacitor circuits composed of any kinds of linear components and non‐linear transistors as switches. All switches must have the same period, but they can be opened and closed at any time. the method proposed may also be applied to mixer analysis for the case of strong LO and weak RF signals. Examples are given to demonstrate that the method is efficient and sufficiently fast to be used in circuit design. the simulation results show good agreement with those obtained by harmonic balance and transient analysis.
Symbolic distortion analysis of non‐linear elements in feedback amplifiers using describing functions
Authors: Floberg Henrik , Mattisson Sven 
Published: July 2007

AbstractThis paper presents a new appoach based on the use of describing functions to obtain approximate symbolic expressions for the fundamental frequency component as well as for the second‐ and third‐order harmonics. A single soft or hard transconductance non‐linearity embedded in an arbitrary linear network is studied. Three examples are considered.
Gluten‐free but also gluten‐enriched (gluten+) diet prevent diabetes in NOD mice; the gluten enigma in type 1 diabetes
Authors: Funda David P. , Kaas Anne , Tlaskalová‐Hogenová Helena , Buschard Karsten 
Published: July 2007

AbstractBackgroundEnvironmental factors such as nutrition or exposure to infections play a substantial role in the pathogenesis of type 1 diabetes (T1D). We have previously shown that gluten‐free, non‐purified diet largely prevented diabetes in non‐obese diabetic (NOD) mice. In this study we tested hypothesis that early introduction of gluten‐enriched (gluten+) diet may increase diabetes incidence in NOD mice.MethodsStandard, gluten‐free, gluten+ modified Altromin diets and hydrolysed‐casein‐based Pregestimil diet were fed to NOD females and diabetes incidence was followed for 310 days. Insulitis score and numbers of gut mucosal lymphocytes were determined in non‐diabetic animals.ResultsA significantly lower diabetes incidence (p < 0.0001) was observed in NOD mice fed gluten‐free diet (5.9%, n = 34) and Pregestimil diet (10%, n = 30) compared to mice on the standard Altromin diet (60.6%, n = 33). Surprisingly, gluten+ diet also prevented diabetes incidence, even at the level found with the gluten‐free diet (p < 0.0001, 5.9%, n = 34). The minority of mice, which developed diabetes on all the three diabetes‐protective (gluten+, gluten‐free, Pregestimil) diets, did that slightly later compared to those on the standard diet. Lower insulitis score compared to control mice was found in non‐diabetic NOD mice on the gluten‐free, and to a lesser extent also gluten+ and Pregestimil diets. No substantial differences in the number of CD3+, TCR‐γδ+, and IgA+ cells in the small intestine were documented.ConclusionsGluten+ diet prevents diabetes in NOD mice at the level found with the non‐purified gluten‐free diet. Possible mechanisms of the enigmatic, dual effect of dietary gluten on the development of T1D are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
The relationship of weight suppression and dietary restraint to binge eating in bulimia nervosa
Authors: Lowe Michael R. , Thomas J. Graham , Safer Debra L. , Butryn Meghan L. 
Published: July 2007

AbstractObjective:Recent research has raised important questions about the relationships between weight suppression (WS) (discrepancy between highest‐ever and current weight), dietary restraint, and binge eating in bulimia nervosa (BN).Method:In the current study, these variables were studied cross‐sectionally through secondary analyses of baseline data collected in a multi‐site treatment study. Participants (N = 182) were treatment‐seeking women diagnosed with BN. Dietary restraint and binge eating were measured via the Eating Disorders Examination.Results:WS was directly and dietary restraint was inversely related to frequency of binge eating. The inverse relationship between dietary restraint and binge eating may be explained in part by the fact that the most restrained patients with BN had the greatest desire to lose weight.Conclusion:Implications of these findings for future research on the perpetuation and treatment of BN are discussed. © 2007 by Wiley Periodicals, Inc. Int J Eat Disord 2007
Depression and reliance on ease‐of‐retrieval experiences
Authors: Greifeneder Rainer , Bless Herbert 
Published: July 2007

AbstractThe relationship between level of depressive symptomatology and reliance on the ease‐of‐retrieval heuristic was investigated. In two studies, differences in ease‐of‐retrieval were instigated by means of the paradigm introduced by Schwarz and co‐workers. Subsequently, participants were screened for depressive symptoms with the Allgemeine Depressionsskala (ADS, Experiments 1 and 2) and the Beck Depression Inventory (BDI, Experiment 2). In both experiments, participants were randomly selected from a non‐clinical population. Results indicate that participants with low levels of depressive symptomatology relied on experienced ease or difficulty, whereas individuals with high levels of depressive symptomatology based their judgment on the accessible content information. Theoretical and practical implications of these findings are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Nanocrystalline hydroxyapatite/titania coatings on titanium improves osteoblast adhesion
Authors: Sato Michiko , Aslani Arash , Sambito Marisa A. , Kalkhoran Nader M. , Slamovich Elliott B. , Webster Thomas J. 
Published: July 2007

AbstractBulk hydroxyapatite (HA) and titania have been used to improve the osseointegration of orthopedic implants. For this reason, composites of HA and titania have been receiving increased attention in orthopedics as novel coating materials. The objective of this in vitro study was to produce nanophase (i.e., materials with grain size less than 100 nm) HA/titania coatings on titanium. The adhesion of bone forming cells (osteoblasts) on the composite coatings were also assessed and compared with single‐phase nanotitania and nano‐HA titanium coatings. Nanocrystalline HA powders were synthesized through wet chemistry and hydrothermal treatments at 200°C. Nanocrystalline titania powders obtained commercially were mixed with the nanocrystalline HA powders at various weight ratios. The mixed powders were then deposited on titanium utilizing a room‐temperature coating process called IonTite™. The results of the present study showed that such coatings maintained the chemistry and crystallite size of the original HA and titania powders. Moreover, osteoblasts adherent on single‐phase nanotitania coatings were well‐spread whereas they became more round and extended distinct filopodia on the composite and single‐phase HA coatings. Interestingly, the number of osteoblasts adherent on the nanotitania/HA composite coatings at weight ratios of 2/1 and 1/2 were significantly greater compared with single‐phase nanotitania coatings, currently‐used plasma‐sprayed HA coatings, and uncoated titanium. These findings suggest that nanotitania/HA coatings on titanium should be further studied for improved orthopedic applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Expression of the human β3 integrin subunit in mouse smooth muscle cells enhances IGF‐I‐stimulated signaling and proliferation
Authors: Xi Gang , Maile Laura A. , Yoo Sung‐Eun , Clemmons David R. 
Published: July 2007

AbstractOptimal stimulation of signal transduction and biological functions by IGF‐I in porcine smooth muscle cells (pSMC) requires ligand occupancy of the αVβ3 integrin. Binding of heparin‐binding domain (HBD) of vitronectin (VN) to the cysteine loop (C‐loop) region of β3 is required for pSMC to respond optimally to IGF‐I stimulation. Mouse smooth muscle cells (mSMC), which express a form of β3 whose sequence within the C‐loop region is different than porcine or human β3, do not respond optimally to IGF‐I, and IGF‐I stimulated β3 and SHPS‐1 phosphorylation which are necessary for optimal IGF‐I signaling were undetectable. VN also had no effect on IGF‐I stimulated the cell proliferation. In contrast, when human β3 (hβ3) was introduced into mSMC, there was an enhanced VN binding in spite of an equivalent amount of total β3 expression, and IGF‐I‐dependent β3, and SHPS‐1 phosphorylation were detected. In addition, there was enhanced IGF‐I‐stimulated Shc association with SHPS‐1, Shc tyrosine phosphorylation, Shc and Grb2 association, and MAP kinase activation leading to increased cell proliferation. These enhancements could be further augmented by adding a peptide containing the HBD of VN. To determine if these changes were mediated by the C‐loop region of β3, an antibody that reacts with that region of β3 was utilized. The addition of the hβ3 C‐loop antibody abolished VN‐induced enhancement of IGF‐I signaling and IGF‐I‐stimulated cell proliferation. These results strongly support the conclusion that optimal SMC responsiveness to IGF‐I requires ligand interaction with the C‐loop domain of hβ3. J. Cell. Physiol. 214: 306–315, 2008. © 2007 Wiley‐Liss, Inc.
Surface desorption atmospheric pressure chemical ionization mass spectrometry for direct ambient sample analysis without toxic chemical contamination
Authors: Chen Huanwen , Zheng Jian , Zhang Xie , Luo Mingbiao , Wang Zhichang , Qiao Xiaolin 
Published: July 2007

AbstractAmbient mass spectrometry, pioneered with desorption electrospray ionization (DESI) technique, is of increasing interest in recent years. In this study, a corona discharge ionization source is adapted for direct surface desorption chemical ionization of compounds on various surfaces at atmospheric pressure. Ambient air, with about 60% relative humidity, is used as a reagent to generate primary ions such as H3O+, which is then directed to impact the sample surface for desorption and ionization. Under experimental conditions, protonated or deprotonated molecules of analytes present on various samples are observed using positive or negative corona discharge. Fast detection of trace amounts of analytes present in pharmaceutical preparations, viz foods, skins and clothes has been demonstrated without any sample pretreatment. Taking the advantage of the gasless setup, powder samples such as amino acids and mixtures of pharmaceutical preparations are rapidly analyzed. Impurities such as sudan dyes in tomato sauce are detected semiquantitatively. Molecular markers (e.g. putrescine) for meat spoilage are successfully identified from an artificially spoiled fish sample. Chemical warfare agent stimulants, explosives and herbicides are directly detected from the skin samples and clothing exposed to these compounds. This provides a detection limit of sub‐pg (S/N ≥ 3) range in MS2. Metabolites and consumed chemicals such as glucose are detected successfully from human skins. Conclusively, surface desorption atmospheric pressure chemical ionization (DAPCI) mass spectrometry, without toxic chemical contamination, detects various compounds in complex matrices, showing promising applications for analyses of human related samples. Copyright © 2007 John Wiley & Sons, Ltd.
Methodical approach for the use of GC‐TOF MS for screening and confirmation of organic pollutants in environmental water
Authors: Portolés Tania , Pitarch Elena , López Francisco J. , Sancho Juan V. , Hernández Félix 
Published: July 2007

AbstractThe potential of gas chromatography coupled to time‐of‐flight mass spectrometry (GC‐TOF MS) for the screening of organic pollutants in water was explored. After a conventional SPE step with C18 cartridges, the comparison of spectra with available libraries together with an evaluation of the mass accuracy was the first approach used for the screening and confirmation of target analytes. However, at low analyte concentrations (i.e. below 0.1 µg/l), this procedure was not feasible and the use of the application manager TargetLynx was evaluated. This application allows the selection of up to five representative ions per analyte, measured with high mass accuracy, and their intensity ratio evaluation. Ion selection, extraction mass window and concentration levels were found to be the critical parameters. The reference compound used as ‘lock mass’ was also found to affect to the quality of information obtained in some particular cases.Full spectral acquisition data generated by the TOF MS analyzer allowed investigation of the presence of several analytes in samples in a post‐target style, without the need of reanalyze the water samples.Finally, a methodical approach was established for the reliable screening and confirmation of organic pollutants (PAHs, pesticides, octyl/nonyl phenols) in real‐world samples, which led to satisfactory results of ∼0.1 µg/l. Copyright © 2007 John Wiley & Sons, Ltd.
Temporal electronic structures of nonresonant Raman excited virtual states: a case study of ethylene thiourea
Authors: Fang Chao , Wu Guozhen 
Published: July 2007

AbstractAn algorithm is employed to elucidate molecular bond polarizabilities of ethylene thiourea including their temporal relaxation from Raman intensities, which provide much information concerning the electronic distribution of nonresonant Raman excited virtual states. The main character of the excited states of ethylene thiourea is that the excited electrons tend to flow to the molecular periphery because of electronic repulsion. It is noted that the bond electronic densities of the ground state can be mapped out by the bond polarizabilities at the final stage of relaxation. The relaxation time is shown to be proportional to the wavelength of the exciting light in agreement with Heisenberg's uncertainty principle, showing that the excitations are indeed not the stationary eigenstates. Copyright © 2007 John Wiley & Sons, Ltd.
Distributed parameter systems approach to the optimal cattle ranching problem
Authors: Derzko N. , Sethi S. P. , Thompson G. L. 
Published: July 2007

AbstractThis paper describes a maximum principle for distributed parameter systems, i.e. systems characterized by partial differential equations. The maximum principle is applied to solve the problem of a cattle rancher who must decide the number of cattle in different age groups to be bought and sold at each instant in order to maximize his profits.
Control design for magnetic suspension
Authors: Vincent Thomas L. 
Published: July 2007

AbstractThrough proper design, it is possible to build an electromagnetic bearing system, using a ferromagnetic rotor, such that there exists an equilibrium position in the magnetostatic field which is unstable only in the axial direction. In order to achieve axial stability, a regulator may be employed to vary the current in the coils whenever the rotor is displaced from the equilibrium position. The idea is to vary the current in such a way that the resultant change in the magnetic, field produces a restoring force to the rotor.This study is devoted to an investigation of the relative merits of various control laws which could be implemented by the regulator. The rotor is to be maintained in the vicinity of the equilibrium point even if an external force is present which enters the system as an unknown but bounded function of the system state and time.Recent magnetic suspension systems have been designed using a regulator based on linear state variable feedback. It is shown here that asymptotic stability cannot be maintained for the system in the presence of an external force if linear feedback control is used. The effect of an unknown but bounded external force on the system is vividly demonstrated by using qualitative methods to find the boundary of the set reachable under this force. Linear state variable feedback can maintain partial controllability of the system to some neighbourhood of the equilibrium point provided a simple inequality relationship between the feedback parameters and the bounds on the external force is maintained. Finally, it is shown that a game theoretic approach may be used for a nonlinear regulator design which will result in an asymptotically stable system in the presence of an unknown but bounded external force.
Sequential conjugate gradient‐restoration algorithm for optimal control problems with non‐differential constraints and general boundary conditions, part 2
Authors: Wu A. K. , Miele A. 
Published: July 2007

AbstractIn Reference 1, Wu and Miele developed the sequential conjugate gradient‐restoration algorithm for minimizing a functional subject to differential constraints, with or without non‐differential constraints, and general boundary conditions. In this paper, several numerical examples are presented. Some of these pertain to a quadratic functional subject to linear constraints, and some pertain to a non‐quadratic functional subject to non‐linear constraints. These examples demonstrate the feasibility as well as the convergence characteristics of the sequential conjugate gradient‐restoration algorithm.
Two methods for the solution of the dynamic programming algorithm on a multiprocessor cluster
Authors: Al‐Dabass D. 
Published: July 2007

AbstractThe dynamic programming algorithm is examined with a view to solving it on a multiprocessor cluster. The two methods of control‐space division and state‐space division are proposed, and their efficiency is analysed in detail. A practical example is given to illustrate the two methods using a two‐processor system, and the results are projected to find the minimum achievable time and optimum number of processors for this example.
Optimal active‐reactive hydro‐thermal schedules using functional analysis
Authors: El‐Hawary M. E. , Christensen G. S. 
Published: July 2007

AbstractA new approach to the hydro‐thermal optimal active and reactive power scheduling problem is proposed. The optimal schedules for a system with thermal and common‐flow hydro‐plants are obtained. The active‐reactive power balance model of the electric network is introduced. Although not as accurate as the load‐flow model, the present model is simpler. The scheduling problem is solved by use of the minimum norm formulation of functional analytic optimization.
Guaranteed cost solution of optimal control and game problems for uncertain systems
Authors: Mahalanabis A. K. , Rana R. 
Published: July 2007

AbstractA class of systems having white noise parameter variations is considered. Solutions of the infinite‐time quadratic optimal control (LQOC) and differential game (LQDC) problems are considered. It is shown that guaranteed cost solutions of these problems are possible if the effects of parameter uncertainties are first taken into account in a specified manner. The method is illustrated through a numerical example.
The effects of mismatch on an optimal control scheme for linear systems with control time delays
Authors: Hocken R. D. , Marshall J. E. 
Published: July 2007

AbstractAn essential feature common to control schemes for plants with time delays is the use of a plant model for purposes of prediction. Any difference between plant and model is referred to as mismatch. The paper is concerned with how mismatch affects the stability and performance of an optimal control scheme for linear systems with delay in control.
High‐order necessary optimality conditions for control problems with terminal constraints
Authors: Gorokhovik V. V. 
Published: July 2007

AbstractThis is a survey of high‐order necessary optimality conditions for control problems with inequality and equality terminal constraints. Both classical and Pontryagin extremals are considered. For classical extremals, the characteristics of necessary optimality conditions in terms of variations are given, and the investigations devoted to Kelley's conditions are discussed in detail. For Pontryagin extremals, two types of results are given: generalizations and extensions of matrix impulse optimality condition and high‐order maximum principle.