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71.
72.
Seppo Pohjolainen 《Automatica》1987,23(6):719-728
Optimal tuning of robust multivariable controllers for stable parabolic distributed parameter systems is discussed. In order to evaluate the behaviour of the closed loop system, a quadratic criterion is selected. Then it is proved that the system may be decomposed into slow and fast subsystems, and that the value of the criterion will mainly depend on the slow subsystem. Tuning of the controller, for this subsystem, turns out to be a standard finite-dimensional quadratic regulator problem. Two examples are given to show the improvement due to the new selection of the control parameters. 相似文献
73.
Koskinen M Seppänen T Tong S Mustola S Thakor NV 《IEEE transactions on bio-medical engineering》2006,53(4):669-675
The ability to monitor the physiological effects of sedative medication accurately is of interest in clinical practice. During the anesthetic agent driven transition to unresponsiveness, nonstationary changes such as signal amplitude variations appear in electroencephalography. In this paper, it is studied whether the application of the approximate entropy (ApEn) method to electroencephalographic (EEG) signal produces a monotonic response curve during the transition from awareness to unresponsiveness. Data from fourteen patients, undergoing propofol anesthetic induction were studied. To optimize the ApEn performance, different parameter choices were carefully evaluated. It was assumed with our protocol, that the level of anesthesia changes monotonically with the elapsed induction time. The monotonicity of the ApEn change was assessed with the prediction probability statistic (PK). The monotonicity of the ApEn time-series depends on the parameters employed in the algorithm and the varying signal amplitude. Depending on the parameter values, the median PK value ranged from 0.886 to 0.527. Thus, a good directionality and concordance was observed, but the nonstationarity of the signal affected the results. In conclusion, EEG-based ApEn measure shows a nonlinear response during propofol induction. With a judicious choice of parameters, a monotonic response is confirmed using PK statistic. 相似文献
74.
During recent decades, zebrafish (Danio rerio) have become one of the most important model organisms in which to study different physiological and biological phenomena. The research field of carbonic anhydrases (CAs) and carbonic anhydrase related proteins (CARPs) is not an exception to this. The best-known function of CAs is the regulation of acid–base balance. However, studies performed with zebrafish, among others, have revealed important roles for these proteins in many other physiological processes, some of which had not yet been predicted in the light of previous studies and suggestions. Examples include roles in zebrafish pigmentation as well as motor coordination. Disruption of the function of these proteins may generate lethal outcomes. In this review, we summarize the current knowledge of CA-related studies performed in zebrafish from 1993–2021 that was obtained from PubMed search. 相似文献
75.
Simo-Pekka Hannula Hannu Hänninen Seppo Tähtinen 《Metallurgical and Materials Transactions A》1984,15(12):2205-2211
Hydrogen embrittlement of AISI 304-type austenitic stainless steels has been studied with special emphasis on the effects
of the nitrogen content of the steels. Hydrogen charging was found to degrade the mechanical properties of all the steels
studied, as measured by a tensile test. The fracture surfaces of hydrogen charged specimens were brittle cleavage-like whereas
the uncharged specimens showed ductile, dimpled fracture. In sensitized materials transgranular cleavage mode of fracture
was replaced by an intergranular mode of fracture and the losses of mechanical properties were higher. Nitrogen alloying decreased
the hydrogen-induced losses of mechanical properties by increasing the stability of austenite. In sensitized steels the stability
of austenite and nitrogen content were found to have only a minor effect on hydrogen embrittlement, except when sensitization
had causedα′-martensite transformation at the grain boundaries.
Formerly with Helsinki University of Technology, Laboratory of Physical Metallurgy, SF-02150 Espoo 15, Finland. 相似文献
76.
Algorithms and a computer software package for calculating thermophysical material properties of carbon and low-alloyed steels,
associated with the simulation of solidification processes, have been developed. The earlier studies on kinetic phase transformation
modeling are applied and are the base of the present work. The calculation algorithms are based on thermodynamic theory connected
to thermodynamic assessment data, as well as on regression formulas of experimental data, and they take into account the temperature,
the cooling rate, and the steel composition. The calculation algorithms and some results of calculations are presented in
this article. 相似文献
77.
78.
This paper summarizes some of the results in the field of diagnostic expert systems of the EUREKA MAINE EU 744 project FMSMAINT System. Methods and software have been developed to increase the lower-than-expected availability of expensive flexible manufacturing systems (FMS). In the work described in this paper a special emphasis has been put on efficiently integrating automatic data acquisition, data analysis supported by multimedia, and expert-system-based diagnostics. The software described has been installed in the industrial pilots participating in the project, and the modules have already also been taken to a commercial level. 相似文献
79.
Bend loss effects can be a significant concern in the design and performance of diffused, buried waveguide devices. Since diffused, buried waveguides typically do not have analytical mode solutions, the bend mode must be expressed as an expansion of straight waveguide modes. For the case of buried ion-exchanged waveguides, the bend loss is affected by bend radius, the duration of the ion exchange and burial processes, as well as the size of the mask opening used to create the waveguides and applied field during burial. The bend loss effects for each of these variables are explored under typical fabrication conditions. 相似文献
80.
Päivinen N Lammi S Pitkänen A Nissinen J Penttonen M Grönfors T 《Computer methods and programs in biomedicine》2005,79(2):151-159
This study concerns the detection of epileptic seizures from electroencephalogram (EEG) data using computational methods. Using short sliding time windows, a set of features is computed from the data. The feature set includes time domain, frequency domain and nonlinear features. Discriminant analysis is used to determine the best seizure-detecting features among them. The findings suggest that the best results can be achieved by using a combination of features from the linear and nonlinear realms alike. 相似文献