Linear Reference Research Articles

Estimates of compression at low and high frequencies using masking additivity in normal and impaired ears.

Auditory compression was estimated at 250 and 4000 Hz by using the additivity of forward masking technique, which measures the effects on signal threshold of combining two temporally nonoverlapping forward maskers. The increase in threshold in the combined-masker condition compared to the individual-masker conditions can be used to estimate compression. The signal was a 250 or 4000 Hz tone burst and the maskers (M1 and M2) were bands of noise. Signal thresholds were measured in the presence of M1 and M2 alone and combined for a range of masker levels. The results were used to derive response functions at each frequency. The procedure was conducted with normal-hearing and hearing-impaired listeners. The results suggest that the response function in normal ears is similar at 250 and 4000 Hz with a mid level compression exponent of about 0.2. However, compression extends over a smaller range of levels at 250 Hz. The results confirm previous estimates of compression using temporal masking curves (TMCs) without assuming a linear off-frequency reference as in the TMC procedure. The impaired ears generally showed less compression. Importantly, some impaired ears showed a linear response at 250 Hz, providing a further indication that low-frequency compression originates in the cochlea.

Evaluation of the robustness of the polynomial segment models to noisy environments with unsupervised adaptation

Recently, the polynomial segment models (PSMs) have been shown to be a competitive alternative to the HMM in large vocabulary continuous recognition task [Li, C., Siu, M., Au-yeung, S., 2006. Recursive likelihood evaluation and fast search algorithm for polynomial segment model with application to speech recognition. IEEE Trans. on Audio, Speech and Language Processing 14, 1704–1708]. Its more constrained nature raises the issue of robustness under environmental mis-matches. In this paper, we examine the robustness properties of PSMs using the Aurora 4 corpus under both clean training and multi-conditional training. In addition, we generalize two unsupervised model adaptation schemes, namely, the maximum likelihood linear regression (MLLR) and reference speaker weighting (RSW), to be applicable for PSMs and explore their effectiveness in PSM environmental adaptation. Our experiments showed that although the word error rate differences between PSMs and HMMs became smaller under noisy test environments than under clean test environment, PSMs were still competitive under mis-match conditions. After model adaptation, especially with the RSW adaptation, the word error rates were reduced for both HMMs and PSMs. The best word error rate was obtained with RSW-adapted PSMs by rescoring lattices generated with the adapted HMMs. Overall, with model adaptation, the recognition word error rate can be reduced by more than 20%.

Parametric convergence and control of chaotic system using adaptive feedback linearization

Adaptive feedback linearization control technique for chaos suppression in a chaotic system is proposed. The dynamics of the system is altered so that the closed loop model matches with a specified linear reference model. The controller parameters are assumed to be unknown and are evolved using an adaptation law that aims to drive these parameters towards their ideal values so as to achieve perfect matching between the reference and the system model. A common external forcing signal to both chaotic Genesio system and reference system is considered and adaptation laws are derived considering Lyapunov function based stability. Simulation results show that the chaotic behavior is suppressed effectively with proposed controller. Analysis of linear and nonlinear parametric convergence is also shown through simulation, both with and without excitation using suitable forcing function.

Nonlinear torque and stator flux controller for induction motor drive based on adaptive input–output feedback linearization and sliding mode control

This paper describes a nonlinear to rque and stator flux controller for three phase induction motor (IM) drives on the basis of a space vector modulation (SVM) scheme. Using the IM fifth order model in a fixed “ab” axis reference frame with stator currents ( i sa , i sb) and stator fluxes ( ψ sa, ψ sb) as state variables, a sliding mode (SM) torque and flux controller is designed first in order to track a linear reference model, which has the desired dynamic behaviors for the IM drive system. The SM controller generates the reference voltages ( v as ∗ , v bs ∗ ) for a two level space vector modulation-pulse width modulation (SVM–PWM) inverter that feeds the motor. Then, the SM controller is combined with an adaptive input–output feedback linearization technique in order to preserve the system robustness with respect to stator and rotor resistances variations and uncertainties. Finally, simulations and comparative experimental results with the proposed control scheme are presented.

Identification of Spring Parameters for Deformable Object Simulation

Mass spring models are frequently used to simulate deformable objects because of their conceptual simplicity and computational speed. Unfortunately, the model parameters are not related to elastic material constitutive laws in an obvious way. Several methods to set optimal parameters have been proposed, but so far only with limited success. We analyze the parameter identification problem and show the difficulties, which have prevented previous work from reaching wide usage. Our main contribution is a new method to derive analytical expressions for the spring parameters from an isotropic linear elastic reference model. The method is described and expressions for several mesh topologies are derived. These include triangle, rectangle and tetrahedron meshes. The formulae are validated by comparing the static deformation of the MSM with reference deformations simulated with the finite element method.

Vibrational energy levels with arbitrary potentials using the Eckart-Watson Hamiltonians and the discrete variable representation

An effective and general algorithm is suggested for variational vibrational calculations of N-atomic molecules using orthogonal, rectilinear internal coordinates. The protocol has three essential parts. First, it advocates the use of the Eckart-Watson Hamiltonians of nonlinear or linear reference configuration. Second, with the help of an exact expression of curvilinear internal coordinates (e.g., valence coordinates) in terms of orthogonal, rectilinear internal coordinates (e.g., normal coordinates), any high-accuracy potential or force field expressed in curvilinear internal coordinates can be used in the calculations. Third, the matrix representation of the appropriate Eckart-Watson Hamiltonian is constructed in a discrete variable representation, in which the matrix of the potential energy operator is always diagonal, whatever complicated form the potential function assumes, and the matrix of the kinetic energy operator is a sparse matrix of special structure. Details of the suggested algorithm as well as results obtained for linear and nonlinear test cases including H(2)O, H(3) (+), CO(2), HCNHNC, and CH(4) are presented.

International Linear Collider gets reference design and cost estimate

But DOE warns that the design team's hope for completion of the 31-kilometer-long machine by 2019 may be too optimistic.

Linear Rheological Properties of the Semifluorinated Copolymer Tetrafluoroethylene-Hexafluoropropylene-Vinylidenfluoride (THV) with Controlled Amounts of Long-Chain Branching

Various semifluorinated polymers of narrow molar mass distributions and definitely changed molecular structure are employed as model substances to investigate the impact of the polymer architecture on key rheological properties in the linear range of shear flow. These model samples originate from free radical terpolymerizations of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidenfluoride (VDF), referred to as THV. They were tailored to cover a broad range of mass-average molar masses of a straight linear and of a long-chain branched topography. By the controlled incorporation of long-chain branches (LCB) into the fluoropolymers, a complex thermorheological behavior is observed. The effect of long-chain branching also becomes evident by dynamic-mechanical measurements represented by a plot of the angle δ versus the complex modulus |G*(ω)|. Compared to the linear reference materials for which η0 ∼ Mw3.8 was found, the zero-shear rate viscosity η0 of some of the branched polymers is significantly higher than that of a linear product with equivalent Mw, for others it comes to lie below the curve for linear samples. The experimental η0 (Mw) data of the branched THV are in good agreement with an approach proposed by Janzen and Colby using the structural information from the molecular characterization. Moreover, it was found that plotting η0 as a function of the intrinsic viscosity [η] more sensitively discriminates between the various long-chain branched samples than η0 (Mw). Comparing the sensitivity of methods based on rheological properties in solution and in the molten state, it is demonstrated that the linear behavior of the melts can very favorably be used to get an insight into the molecular architecture of THV polymers.

Artificial Neural Network Speed Profile Model for Construction Work Zones on High-Speed Highways

Speed profile models can be used as a diagnostic tool by highway engineers. Previous work has investigated relationships between operating speed and geometric roadway elements for permanent roadway conditions on predominantly two-lane rural roads. However, little research of this type has been directed specifically toward construction work zones. In this study, a speed profile model for construction work zones on high speed highways was developed using artificial neural networks and made available for use by practitioners through a MS EXCEL interface. The model inputs include horizontal and vertical alignment variables, cross section dimensions and traffic control features. A linear reference system is used for model input and output. Three categories of vehicles—cars, trucks, and all vehicles—were used in this study. Models for the 15th percentile speed, mean speed, and 85th percentile speed were developed.

Network Analysis in Geographic Information Science: Review, Assessment, and Projections

Network data structures were one of the earliest representations in geographic information systems (GIS), and network analysis remains one of the most significant and persistent research and application areas in geographic information science (GIScience). Network analysis has a strong theoretical basis in the mathematical disciplines of graph theory and topology, and it is the topological relationships inherent in networks that led to revolutionary advances in GIS data structures. Networks can represent an alternative datum for geo-location in the context of linear referencing and support a set of tools for graphical display known as dynamic segmentation. Many network location problems are among the most difficult to solve in terms of their combinatorial complexity and, therefore, provide both a challenge and an opportunity for GIScience researchers. Because elements of network analysis appear in a wide range of academic disciplines—from physics, to sociology, to neurobiology—there are ample opportunities for interdisciplinary investigations of emerging research topics.

Linear and Nonlinear Control Techniques for a Three-Phase Three-Level NPC Boost Rectifier

This paper deals with three control techniques for a three-phase three-level neutral-point-clamped (NPC) boost rectifier to study their relative performance. Linear, nonlinear, and nonlinear model reference adaptive control (MRAC) methods are developed to control power factor (PF) and regulate output and neutral point voltages. These controllers are designed in Simulink and implemented in real time using the DS1104 DSP of dSPACE for validation on a 1.2-kW prototype of an NPC boost rectifier operating at 1.92 kHz. The performance of boost converter with three control methods has been investigated respectively in steady state in terms of line-current harmonic distortion, efficiency, and PF and during transients such as load steps, utility disturbances, reactive power control, and dc-bus voltage tracking behavior. The linear PI controllers are characterized by reduced complexity but poor performance, whereas the nonlinear control technique has improved the converter performance significantly, while nonlinear MRAC exhibits much better performance in a wide operating range

Solution of the Schrödinger equation by a high order perturbation method based on a linear reference potential

The paper is devoted to the enhancement of the accuracy of the line-based perturbation method via the introduction of the perturbation corrections. We effectively construct the first and the second order corrections. We also perform the error analysis to predict that the introduction of successive corrections substantially enhances the order of the method from four, for the zeroth order version, to six and ten when the first and the second-order corrections are included. In order to remove the effect of the accuracy loss due to near-cancellation of like-terms when evaluating the perturbation corrections we construct alternative asymptotic formulae using a Maple code. We also propose a procedure for choosing the step size in terms of the preset accuracy and give a number of numerical illustrations.

A GIS-based infrastructure management system for municipalities

The infrastructure departments of the Portuguese municipalities must make great efforts in beginning or continuing to use advanced information technology tools to increase institutional productivity and effectiveness in managing infrastructure. At present, they use or are beginning to use independent management systems for each type of infrastructure, such as road pavements, bridges, signs, water pipelines, sewer pipelines, or parks. In the future, they need to begin development of an integrated infrastructure management system (IMS). This paper focuses on the issues and needs that emerged from studies in Portugal involving the implementation of transportation management systems in local municipalities. The functions of various participating divisions inside a municipal department are introduced and discussed. The issues and needs that must be fully understood and considered in the development of an integrated IMS are identified. Doing so involves determining and standardising an effective base linear referencing system, standardising data terminology, determining the shared data needs of the several divisions inside a department, and developing a comprehensive database design with special attention given to the types of data analysis functions performed by each division. The paper also describes the application of the integrated IMS in road maintenance management, road safety management and sewer network management using the same base linear referencing system.

Stationkeeping on unstable orbits: Generalization to the elliptic restricted three-body problem

We develop new methods for generating periodic orbits about the collinear libration points and for stabilizing motion on libration orbits using the general formalism of the elliptic restricted three-body problem (ER3BP). Calculation of periodic orbits is accomplished by formulating the ER3BP as a control problem. This approach yields halo-like orbits that do not exist without applying active control, having arbitrarily small amplitudes. Linearization about the libration points in pulsating coordinates yields an unstable linear parameter-varying (LPV) system with periodic coefficients. We introduce a continuous acceleration control term into the state-space dynamics and use an LPV-generalized version of the pole-assignment technique to find linear periodic reference trajectories. The nonlinear terms of the equations of motion are then treated as periodic disturbances. A disturbance-accommodating control is used to track the libration-point reference orbit in the presence of nonlinear periodic disturbances. Simulation experiments show that stationkeeping is robust to propulsive dispersions.

Linear and nonlinear hearing aid fittings – 1. Patterns of benefit

We evaluated the benefits of fast-acting WDRC, slow-acting AVC, and linear reference fittings for speech intelligibility and reported disability, in a within-subject within-device masked crossover design on 50 listeners with SNHL. Five hearing aid fittings were implemented having two compression channels and seven frequency bands. Each listener sequentially experienced each fitting for a 10-week period. Outcome measures included speech intelligibility under diverse conditions and self-reported disability. At a group level, each nonlinear fitting was superior to the linear references for benefits in listening comfort, listener satisfaction, reported intelligibility and speech intelligibility. Slow-acting AVC outperformed the fast-acting WDRC fittings for listening comfort, while for reported and measured speech intelligibility the converse was true. For listener satisfaction there were no group differences between the nonlinear fittings. Analysis in terms of fittings for individual listeners revealed subsets with definite divergences from the group data and hence a need for candidature criteria. There are systematic differences between the benefits of nonlinear and linear fittings, and also within nonlinear fittings with fast versus slow time constants. The patterns of benefit and individual optima depend on the domain of outcome being assessed.SumarioEvaluamos en cincuenta sujetos con SNHL los beneficios sobre la inteligibilidad del lenguaje de adaptaciones de auxiliares auditivos con WDRC de acción rápida, con AVC de acción lenta y con referencia lineal, así como la discapacidad reportada, con un diseño de enmascaramiento cruzado que permite juzgar las diferencias intra-sujeto y en función del propio dispositivo. Se implementaron cinco adaptaciones con dos canales de compresión y siete bandas de frecuencia. Cada sujeto utilizó secuencialmente las diferentes adaptaciones durante un período de diez semanas. Las medidas de resultado incluyeron inteligibilidad del lenguaje bajo diversas condiciones y la discapacidad auto-reportada. La adaptación con AVC de acción lenta superó la de WDRC de acción rápida en relación con la comodidad para escuchar, aunque para la inteligibilidad del lenguaje, tanto medida como reportada, ocurrió lo contrario. En relación con la satisfacción del sujeto, no existieron diferencias de grupo entre las adaptaciones no lineales. El análisis, en términos en adaptaciones para sujetos individuales, reveló sub-grupos con divergencias definitivas en relación a los datos grupales, y por tanto, la necesidad de establecer criterios para la selección de candidatos. Existen diferencias sistemáticas entre los beneficios de las adaptaciones lineales y no lineales, así como entre las adaptaciones no lineales y las constantes temporales rápidas versus las lentas. El patrón de beneficio y de optimización individual depende del ámbito de resultado bajo escrutinio.

A trajectory-oriented carriageway-based road network data model, part 3: Implementation

This is the final of a three-part series of papers which mainly discusses the implementation issues of the CRNM. The first two papers in the series have introduced the modeling background and methodology, respectively. An overall architecture of the CRNM has been proposed in the last paper. On the basis of the above discusses, a linear reference method (LRM) for providing spatial references for location points of a trajectory is developed. A case study is introduced to illustrate the application of the CRNM for modeling a road network in the real world is given. A comprehensive conclusion is given for the series of papers.

Preparation and Crystallization Kinetics of New Structurally Well-Defined Star-Shaped Biodegradable Poly(l-lactide)s Initiated with Diverse Natural Sugar Alcohols

This study presents syntheses, structural characterization, and crystallization kinetic investigation of new structurally well-defined star-shaped poly(l-lactide)s (PLLAs). First, a series of new 3- to 6-arm star-shaped PLLAs were synthesized through SnOct(2) catalyzed ring-opening polymerization of (l)-lactide with natural sugar alcohols of glycerol, erythritol, xylitol, and sorbitol as the favorable initiators. Subsequently, their chemical structures were characterized by means of GPC, NMR, and viscometer with respect to the star-shaped structures, demonstrating the well-defined arm structures as evidenced on the g(1/2)/g' values, where g and g' denote the ratios of mean-square radius of gyration and intrinsic viscosity of a star-shaped polymer to those of a linear structural reference with similar absolute molecular weight. Furthermore, spherulite morphologies and growth rates were studied by a polarized microscopy (POM) for the synthesized star-shaped PLLAs with different molecular weights, and it was found that the more arms of a star-shaped PLLA finally resulted in a lower spherulite growth rate. With regard to the crystallization kinetics of these star-shaped PLLAs, isothermal and nonisothermal crystallization were examined by differential scanning calorimeter (DSC). It was found that Avrami exponent n values of isothermal crystallization were almost independent of the isothermal crystallization temperature T(c) for different series of star-shaped PLLAs. In contrast, the values of Avrami exponent n were observed to strongly depend on the star-shaped structures with different arms, implying their distinct nucleation mechanisms, and the more arms of a star-shaped PLLA led to a slower isothermal crystallization rate. On the basis of a modified Avrami equation, new light was shed on the nonisothermal crystallization kinetics for the star-shaped PLLAs, and the activation energies were found to vary from 146.86 kJ/mol for the linear PLLA EG-3 to 221.23 kJ/mol of the star-shaped S-3, demonstrating much decreased crystallizabilities of star-shaped PLLAs with more arms.

Elimination of reference phase errors in phase-shifting interferometry

Based on the analysis of phase evaluation algorithms in phase-shifting interferometry (PSI), a novel compensation algorithm for reference phase deviations has been proposed to reduce the linear and quadratic reference phase deviations using interferometry signals. The algorithm evaluates the accurate phase shifts at each step from the interferograms, and then calculates the exact phase difference between the interference beams based on these phase shifts. A numerical simulation was performed and gave evidence to support this novel method. Investigations were performed on a Twyman–Green interferometer for gauge calibration to verify this method. Additional 10% linear and 1% quadratic phase deviations were added on purpose in the phase shifter device. The experiment demonstrates that, for the four- and five-bucket phase evaluation algorithms, the phase errors caused by the linear and quadratic reference phase deviations can be eliminated significantly using the proposed compensation method.

An efficient way to filter out data dependences with a sufficiently large distance between memory references

There are a number of data dependence tests that have been proposed in the literature. The most widely used approximate data dependence tests are the Banerjee inequality and the GCD test. In this paper we consider parallelization for microprocessors with the multimedia extensions. For the short SIMD parallelism extraction it is essential that, if dependency exists, then the distance between memory references is greater than or equal to the number of data processed in the SIMD register. This implies that some loops that could not be vectorized on traditional vector processors can still be parallelized for the short SIMD execution. In this paper we present an accurate and simple method that can filter out data dependences with a sufficiently large distance between memory references for linear array references within a nested loop. The presented method is suitable for use in a dependence analyzer that is organized as a series of tests, progressively increasing in accuracy, as a replacement for the GCD or Banerjee tests.

Supercritical Fluid Extraction: A Study on Metal Recovery and Regeneration of β‐Diketones and Organophosphorus Extractants

For the design of extraction processes that are feasible both environmentally and economically, suitable extractants are required that result in high extraction and that are recyclable. Therefore, the relation between metal‐complex stability and extractant dissociation at standard conditions has been investigated. Complex stability versus dissociation of extractants with non‐coordinating side chains resulted in a linear reference line. This line helps finding extractants optimised for both extraction (of metals) and recovery (of extractants and metals). The solubilities of acetylacetonate complexes with Cu, Zn, Ni, and Co in supercritical CO2 were determined. Regeneration experiments under supercritical conditions have been carried out using a packed countercurrent column. Metal recovery of Cu, Zn, Ni, and Co from supercritical CO2 into nitric acid was shown by decomplexation from both a β‐diketone (acetylacetone) and an organophosphorus compound (Cyanex 272).