Determination Of System Parameters Research Articles

The “K‐Correction” for Irradiated Emission Lines in LMXBs: Evidence for a Massive Neutron Star in X1822−371 (V691 CrA)

We study the K-correction for the case of emission lines formed in the X-ray-illuminated atmosphere of a Roche lobe-filling star. We compute the K-correction as a function of the mass ratio q and the disk flaring angle α using a compact binary code in which the companion's Roche lobe is divided into 105 resolution elements. We also study the effect of the inclination angle in the results. We apply our model to the case of the neutron star low-mass X-ray binary X1822-371 (V691 CrA), where a K-emission velocity Kem = 300 ± 8 km s-1 has been measured by Casares et al. Our numerical results, combined with a previous determination of system parameters, yields 1.61 M☉ ≤ MNS ≤ 2.32 M☉ and 0.44 M☉ ≤ M2 ≤ 0.56 M☉ for the two binary components (i.e., 0.24 ≤ q ≤ 0.27), which provide compelling evidence for a massive neutron star in this system. We also discuss the implications of these masses into the evolutionary history of the binary.

Real-time translational control of a MEMS comb resonator

Closed-loop control has been successfully applied to a microelectromechanical systems (MEMS) lateral comb resonator device in real-time to perform impulse disturbance damping and sinusoidal position control, enabled by the use of a through-wafer optical microprobe to obtain position feedback. This result leverages the application of lifetime, in-situ control of MEMS in order to provide quality assurance of microsystems in safety critical applications. A position feedback signal produced by a through-wafer optical microprobe has been used for comb resonator system model identification by two independent methods to accurately determine the effective mass, damping, and spring constant values of the device. After accurate determination of system parameters, closed-loop impulse disturbance damping and proportional-integral-differential (PID) translational control were applied. Closed-loop control results presented indicate controllability of such microstructures and response times on the order of the natural frequency of the device.

Doppler tomography of accretion in binaries

AbstractSince its conception, Doppler tomography has matured into a versatile and widely used tool. It exploits the information contained in the highly‐structured spectral line‐profiles typically observed in mass‐transferring binaries. Using inversion techniques akin to medical imaging, it permits the reconstruction of Doppler maps that image the accretion flow on micro‐arcsecond scales. I summarise the basic concepts behind the technique and highlight two recent results; the use of donor star emission as a means to system parameter determination, and the real‐time movies of the evolving accretion flow in the cataclysmic variable WZ Sge during its 2001 outburst. I conclude with future opportunities in Doppler tomography by exploiting the combination of superior data sets, second generation reconstruction codes and simulated theoretical tomograms to delve deeper into the physics of accretion flows. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Theory and arrangements of self-calibrating whole-body three-dimensional measurement systems using fringe projection technique

We report the basic concepts and experimental arrange- ments of self-calibrating 3-D measurement systems using structured- light illumination (fringe projection), which ensure a high number of ob- ject points, rapid data acquisition, and a simultaneous determination of coordinates and system parameters (self-calibration), making the system completely insensitive to environmental changes. Furthermore, it is un- necessary to have any marker on the object surface and a subsequent matching of the single views is not required to obtain a full-body mea- surement. For this purpose, the test object is successively illuminated with two grating sequences perpendicular to each other from at least two different directions, resulting in surplus phase values for each measure- ment point. Based on these phase values one can calculate the orienta- tion parameters as well as the 3-D coordinates simultaneously. Different measurement setups that have the ability to measure the entire surface (full-body measurement) are reported. Results are presented showing the power of this concept, for example, by measuring of the complete 3-D shape of specular technical surfaces, whereas the object volumes can differ strongly. Theoretical estimations proven by first measurements show a coordinate measurement accuracy of up to 10 25 of the measure- ment field size. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)01801-8)

Evaluation of dual-tip micromanometers during 21-day implantation in goats

Investigative research efforts using a cardiovascular model required the determination of central circulatory haemodynamic and arterial system parameters for the evaluation of cardiovascular performance. These calculations required continuous beat-to-beat measurement of pressure within the four chambers of the heart and great vessels. Sensitivity and offset drift, longevity, and sources of error for eight 3F dual-tipped micromanometers were determined during 21 days of implantation in goats. Subjects were instrumented with pairs of chronically implanted fluid-filled access catheters in the left and right ventricles, through which dual-tipped (test) micromanometers were chronically inserted and single-tip (standard) micromanometers were acutely inserted. Acutely inserted sensors were calibrated daily and measured pressures were compared in vivo to the chronically inserted sensors. Comparison of the pre- and post-gain calibration of the chronically inserted sensors showed a mean sensitivity drift of 1.0±0.4% (99% confidence, n=9 sensors) and mean offset drift of 5.0±1.5 mmHg (99% confidence, n=9 sensors). Potential sources of error for these drifts were identified, and included measurement system inaccuracies, temperature drift, hydrostatic column gradients, and dynamic pressure changes. Based upon these findings, we determined that these micromanometers may be chronically inserted in high-pressure chambers for up to 17 days with an acceptable error, but should be limited to acute (hours) insertions in low-pressure applications.

Wear‐Contact Problems and Modeling of Chemical Mechanical Polishing

Wafer shape and contact pressure evolution during chemical mechanical polishing, and the characteristics of the steady‐state regime are analyzed on the basis of approaches developed in contact mechanics. Nonplanarity caused by the geometrical nonuniformity (erosion) and by the presence of different material on the surface (recess) is considered. The possibility of the process optimization and the determination of system parameters based on the polished surface profiles is discussed.

A Method for Bilinear System Identification

In this paper some new theoretical results from bilinear sytems theory are presented. New formulations of the concepts of span-reachability and observability are given. Based on these investigations standard results from linear systems theory, such as canonical forms and a rank test for the state space decomposition are transferred to bilinear systems theory. In particular, a procedure is outlined which, using recent theoretical results, enables the determination of system parameters from measured input/output data. This approach reduces the realization and identification problem of bilinear systems to that of matching a finite sequence of input/output parameters. On this basis it is possible to develop, for bilinear systems, algorithms analogous to the ones originated from well-known results for linear systems. To illustrate the achieved algorithms, the results of the identification of bilinear models for a translational hydraulic drive out of measured input/output data are presented.

Optimization of system parameters for throughput in a variable rectangular electron beam exposure system

Optimization of system parameters for throughput is investigated under the condition that performances of an electron optical system and an X–Y table system, and large‐scale integrated (LSI) pattern properties are given. The beam is deflected by a vector scanning method. The table is operated in a step and repeat mode. Exposure time is calculated from resist exposure time, settling time of beam deflection digital–analog converters, and table movement time. It is shown that there exist field sizes, aperture angles, and maximum beam sizes which minimize the exposure time. Optimum system parameters depend on LSI pattern properties. The concept of optimizing system parameters for throughput can be applied to system parameter determination in the development of a high throughput exposure system.

Kalman filter estimation of electrical machine parameters

The authors have reported on the computer implementation of a Kalman filter for the determination of system parameters. This paper describes the application of the technique in the determination of the parameters of a d.c. motor. The validity of the technique is confirmed by comparing the experimentally observed machine response with the theoretical response predicted from the estimated parameters.

Systems approach to problems of the design of automated test complexes. Report 2. Determination of system parameters

An increase in the complexity of solvable problems must be related, in final account, to the potentials of ATC; this, in turn, leads to the need for a more detailed investigation of both the parameters of the problem and also the corresponding characteristics of the projected ATC. This requires solutions in a multicriterial statement, i.e., modeling of the optimal selection in indicators. In plotting estimates of the criteria under consideration, the possibility of their mutual compensation is proposed. Although not rigid, the assumtion in question is, in our opinion, however, completely acceptable in practical situations. Further progress in engineering is impossible without the creation of new automated testing complexes, the requirements for which are growing more and more; this governs the need for the development of methods free from erroneous design solutions. In the evolution of our study, we considered the creation of a package of applied programs and dialogue procedures that can be used in automated systems invoked to assist developers in searches for optimal solutions.

Latency of visually evoked saccadic eye movements. I. Saccadic latency and the facilitation model.

The paper deals with the initiation of visually guided saccades, in order to break down the saccadic reaction time into functionally different periods of time. It takes into account that spatial processing of information is so basic that modelling of saccadic control properties should include spatio-temporal arrangements. The output signal of the saccadic system was measured in response to visual stimuli in which the time between the appearance of a visual stimulus in the peripheral field and the disappearance of the central fixation point was varied. The variation of the mean saccadic latency time, measured with respect to the onset of the peripheral stimulus, as a function of stimulus asynchrony was highly significant. This variation may be represented by a so-called gap-overlap curve, which is characterized here by means of five parameters. A facilitation model is introduced to fit the results of the gap-overlap experiments. The facilitation model for the initiation of visually evoked saccades incorporates a mechanism which governs the efficiency of processing of signals that arise from a stimulus presented at a particular position in space. It explains how visual information may be affected by other sensory information before it is used to command further saccades. It allows determination of saccadic system parameters, such as the peripheral and the foveal afferent processing time, the central processing time for a saccade and the degree of facilitation. These quantities were found to be characteristic for the given test subjects, and where these data could be compared with neurophysiological data, the agreement was within the experimental error.

Identifiability of time-varying parameters in a class of linear dynamical systems

This paper deals with the problem of determining time-varying parameters in a system described by a linear differential equation from noise-free observations of input/output signals. For the special case of periodically varying parameters, two identifiability questions are discussed: 1) how to check whether the available experimental data allow unique determination of system parameters, and 2) how to design the experiment to accomplish this with a priori knowledge. Necessary and sufficient conditions for identifiability are obtained.

Spectroscopy of WZ Sagittae

WZ Sge was observed spectroscopically during quiescence in August 1978 and July 1979, before and after the December 1978 outburst. The same instrumental set up was used, namely the Image Photon Counting System on the Anglo-Australian Telescope. Time resolved spectra were obtained in phase over several orbital periods, in wavelength ranges covering Hβ and Hγ and also separately Hα. These data are being used to study the “before and after” changes in the emission line profiles, in the radial velocities of the S-wave and of the emission lines, and in the broad absorption line profiles. Additionally these features are being studied as a function of orbital phase in order to improve the determination of system parameters. When completed, the results will be published elsewhere.

A simple gradient algorithm for least squares estimation of system parameters

This note presents a simple gradient technique for least squares estimation of system parameters without involving matrix inverses. This technique is expected to be useful in the determination of system parameters for systems modelling and also in solving two point boundary value problems as noted in § 6. Computational steps are outlined in § 5.

Hydrologic studies using the Boussinesq equation with recharge term

The Boussinesq equation, which is used to describe one‐dimensional unconfined ground water movement, is modified to accept groundwater recharge as computed by a climatological soil‐moisture balance. It is solved efficiently by using a predictor‐corrector technique for nonlinear partial differential equations. The method is applied to studies of the effects of system parameters on groundwater and to the determination of system parameters by the inverse method. It is used to predict the effects of certain land development options on groundwater occurrence and on groundwater discharge to streams.

The conjugate-gradient method for optimal control problems with undetermined final time†

For solving non-linear control problems several methods exist, the conjugate-gradient method being one of the most successful. Gradient and conjugate-gradient methods have also been extended to treat control problems with undetermined final time. Two basic approaches have been suggested; one in which the final time in each iteration is determined by a search and the other in which the final time for the next iteration is computed. In both approaches the number of steps in the numerical integration procedure is variable. In this paper an alternative approach is suggested. By augmenting the control vector with one additional component the problem with undetermined final time is transformed to a problem with fixed final time. A fixed number of steps can then be used. The same approach can be applied to the determination of unknown constant system parameters or unknown initial conditions of the state vector and for the computation of the on-off control.

System parameter determination via linear functional estimation†

Abstract The system parameter determination problem is reduced to the solution of a set of algebraic equations by the use of estimates of linear functionals involving the observed time functions, i.e. input and output. The minimum variance unbiased estimates of linear functionals are derived using a variation of the Projection Theorem.

Some Applications of Dynamic Measurements in Pressurized Water Reactor Nuclear Power Plants

Results of statistical correlation measurements for obtaining information in a complex system are presented. Experiments were performed on four nuclear power plants using conventional plant instrumentation. Inherent fluctuations (noise), response to forced random, sinusoidal and step variations in reactivity were studied. Frequency domain analysis of the data was performed with a special purpose analog type analyzer for determining power and cross-power spectral densities. Results obtained demonstrate that 1) significant semi-quantitative information on the process can be obtained from power spectral analysis on inherent fluctuations: and 2) cross-power spectral techniques permit frequency response measurements and system parameter determination in commercial nuclear plants.