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Wyszukujesz frazę "Hilbert" wg kryterium: Temat


Tytuł:
An inequality for imaginary parts of eigenvalues of non-compact operators with Hilbert-Schmidt Hermitian components
Autorzy:
Gil’, Michael
Powiązania:
https://bibliotekanauki.pl/articles/29519485.pdf
Data publikacji:
2024
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Hilbert space
linear operators
eigenvalues
Opis:
Let $ A $ be a bounded linear operator in a complex separable Hilbert space, $ A^∗ $ be its adjoint one and $ A_I := (A − A^∗)//(2i) $. Assuming that $A_I $ is a Hilbert-Schmidt operator, we investigate perturbations of the imaginary parts of the eigenvalues of $ A $. Our results are formulated in terms of the “extended” eigenvalue sets in the sense introduced by T. Kato. Besides, we refine the classical Weyl inequality $ \Sigma_{k=1}^\infty (Im \lambda_k (A))^2 ≤ N_2^2 (A_I) $, where $ λk(A) (k = 1, 2, . . .) $ are the eigenvalues of $ A $ and $ N_2(·) $ is the Hilbert-Schmidt norm. In addition, we discuss applications of our results to the Jacobi operators.
Źródło:
Opuscula Mathematica; 2024, 44, 2; 241-248
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conditional mean embedding and optimal feature selection via positive definite kernels
Autorzy:
Jorgensen, Palle E.T.
Song, Myung-Sin
Tiang, James
Powiązania:
https://bibliotekanauki.pl/articles/29519641.pdf
Data publikacji:
2024
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
positive-definite kernels
reproducing kernel Hilbert space
stochastic processes
frames
machine learning
embedding problem
optimization
Opis:
Motivated by applications, we consider new operator-theoretic approaches to conditional mean embedding (CME). Our present results combine a spectral analysis-based optimization scheme with the use of kernels, stochastic processes, and constructive learning algorithms. For initially given non-linear data, we consider optimization-based feature selections. This entails the use of convex sets of kernels in a construction of optimal feature selection via regression algorithms from learning models. Thus, with initial inputs of training data (for a suitable learning algorithm), each choice of a kernel K in turn yields a variety of Hilbert spaces and realizations of features. A novel aspect of our work is the inclusion of a secondary optimization process over a specified convex set of positive definite kernels, resulting in the determination of “optimal” feature representations.
Źródło:
Opuscula Mathematica; 2024, 44, 1; 79-103
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finitely additive functions in measure theory and applications
Autorzy:
Alpay, Daniel
Jorgensen, Palle
Powiązania:
https://bibliotekanauki.pl/articles/29519748.pdf
Data publikacji:
2024
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Hilbert space
reproducing kernel
probability space
Gaussian field
transforms
covariance
Itô integration
Itô calculus
generalized Brownian motion
Opis:
In this paper, we consider, and make precise, a certain extension of the Radon–Nikodym derivative operator, to functions which are additive, but not necessarily sigma-additive, on a subset of a given sigma-algebra. We give applications to probability theory; in particular, to the study of μ-Brownian motion, to stochastic calculus via generalized Itô-integrals, and their adjoints (in the form of generalized stochastic derivatives), to systems of transition probability operators indexed by families of measures μ, and to adjoints of composition operators.
Źródło:
Opuscula Mathematica; 2024, 44, 3; 323-339
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detection and identification of nonlinear contact dynamics at workpiece clamping positions
Autorzy:
Feng, Qi
Maier, Walther
Braun, Steffen
Möhring, Hans-Christian
Powiązania:
https://bibliotekanauki.pl/articles/2200257.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
nonlinearity
contact dynamics
clamping fixture
Hilbert transform
Opis:
All mechanical systems behave nonlinearly to a certain extent since there are always reasons for nonlinearities, such as friction and slip effects, in the actual structures. It is important to detect and identify the nonlinearity due to friction and contact in order to investigate their effect on the global behavior of the workpiece-fixture system. That is a prerequisite for modeling the dynamic contact behavior at the interface between the workpiece and clamping elements. In this research, the workpiece-fixture system was excited with a shaker using the swept sine signal. The nonlinearities could be detected by comparing and analyzing the frequency responses of the structures in Bode plots. However, the nonlinearities behaved differently at various frequencies within the observation range. Different mechanisms such as nonlinear stiffness and damping, micro-slip friction, are responsible for that. Then the nonlinear contact behavior at the clamping positions was successfully identified by means of the Hilbert transform. In addition, the clamping force directly influenced the nonlinear stiffness of the workpiece-fixture system.
Źródło:
Journal of Machine Engineering; 2023, 23, 1; 114--122
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detection of defects in a bearing by analysis of vibration signals
Autorzy:
Bouaouiche, Karim
Menasria, Yamima
Khalifa, Dalila
Powiązania:
https://bibliotekanauki.pl/articles/2203636.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
vibration signal
Hilbert transform
bearing
kurtogram
detection
sygnał drganiowy
transformata Hilberta
łożysko
Opis:
This work presents the analysis of vibration signals by an approach consists of several mathematical tools more elaborate such as the Hilbert transform, kurtogram, which allows the detection of vibration defects in a simple and accurate way. The steps or methods inserted in the process one complementary to the other as scalar indicators generally used in monitoring to follow the evolution of the functioning of a machine when an abnormal functioning it must make a diagnosis to detect the failing element through the use of a process. The determination of the defective organs at an optimal time is a very important operation in the industrial maintenance, which keeps the equipment in a good condition and ensures the assiduity of work. To see the effectiveness of fault detection by the proposed approach by analyzing the real vibration signals of a bearing type 6025-SKF available on the Case Western Reserve University platform.
Źródło:
Diagnostyka; 2023, 24, 2; art. no. 2023203
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Artificial Neural Network based on mathematical models used in quantum computing
Autorzy:
Ruciński, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/2201614.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Przyrodniczo-Humanistyczny w Siedlcach
Tematy:
neural modeling
Day-Ahead Market
Polish Power Exchange
Hilbert space
quantum inspired neural network
Opis:
The article is a proposition of a new approach to building a neural model based on the system of Day-Ahead Market operating at TGE S.A. The reason for the proposed method is an attempt to find a better model for the DAM system. The proposed methodology is based on using mathematical models used in quantum computing. All calculations performed on learning the Artificial Neuron Network are based on operations described in Hilbert space. The main idea of calculations is to replace the data from the decimal system into the quantum state in Hilbert space and perform learning operations for a neural model of the DAM system in a special manner which relay on the teaching model for each position of the quantum register for all data. The obtained results were compared to the “classical” neural model with the use of a comparative model.
Źródło:
Studia Informatica : systems and information technology; 2022, 2(27); 27--48
1731-2264
Pojawia się w:
Studia Informatica : systems and information technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diagnosis of multiple faults of an induction motor based on Hilbert envelope analysis
Autorzy:
Kabul, Ahmet
Ünsal, Abdurrahman
Powiązania:
https://bibliotekanauki.pl/articles/2052085.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Hilbert envelope analysis
induction motor
multiple faults
Opis:
Three phase induction motors are widely used in industrial processes and condition monitoring of these motors is especially important. Broken rotor bars, eccentricity and bearing faults are the most common types of faults of induction motors. Stator current and/or vibration signals are mostly preferred for the monitoring and detection of these faults. Fourier Transform (FT) based detection methods analyse the characteristic harmonic components of stator current and vibration signals for feature extraction. Several types of simultaneous faults of induction motors may produce characteristic harmonic components at the same frequency (with varying amplitudes). Therefore, detection of multiple faults is more difficult than detection of a single fault with FT based diagnosis methods. This paper proposes an alternative approach to detect simultaneous multiple faults including broken rotor bars, static eccentricity and outer/inner-race bearing faults by analysing stator current and vibration signals. The proposed method uses Hilbert envelope analysis with a Normalized Least Mean Square (NLSM) adaptive filter. The results are experimentally verified under 25%, 50%, 75%, 100% load conditions.
Źródło:
Metrology and Measurement Systems; 2022, 29, 1; 191-205
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asynchronous Demodulation Method for Four SSB arranged on Frequency Axis in Mobile Radio Path using Hilbert Transform
Autorzy:
Daikoku, Kazuhiro
Powiązania:
https://bibliotekanauki.pl/articles/1844503.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
asynchronous demodulation
4-SSB
ISB
mobile radio path
Hilbert transform
HF/VHF band telecommunications
tactical communications
underwater communications
Opis:
In this paper, an asynchronous demodulation method for a four-single sideband (SSB) signal arranged on the frequency axis is developed to support burst mode transmission in a mobile radio path and to achieve greater data throughputs. When a reduced pilot carrier is placed at the center of the 4-SSB signal, it is guarded by lower and upper sidebands, that is, this scheme is classified into a tone-in-band (TIB) system. Digital signal processing (DSP) processors are useful for implementing a Hilbert transform. However, we have for a long time neglected introducing it into the demodulation process of SSB signals.
Źródło:
International Journal of Electronics and Telecommunications; 2021, 67, 3; 445-450
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of multiband filtering, empirical mode decomposition and short-time fourier transform used to extract physiological components from long-term heart rate variability
Autorzy:
Adamczyk, Krzysztof
Polak, Adam G.
Powiązania:
https://bibliotekanauki.pl/articles/2052173.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heart rate variability
nonstationary signal analysis
multiband filtering
empirical mode decomposition
short-time Fourier transform
Hilbert transform
Opis:
Heart rate is constantly changing under the influence of many control signals, as manifested by heart rate variability (HRV). HRV is a nonstationary, irregularly sampled signal, the spectrum of which reveals distinct bands of high, low, very low and ultra-low frequencies (HF, LF, VLF, ULF). VLF and ULF components are the least understood, and their analysis requires HRV records lasting many hours. Moreover, there are still no well-established methods for the reliable extraction of these components. The aim of this work was to select, implement and compare methods which can solve this problem. The performance of multiband filtering (MBF), empirical mode decomposition and the short-time Fourier transform was tested, using synthetic HRV as the ground truth for methods evaluation as well as real data of three patients selected from 25 polysomnographic records with a clear HF component in their spectrograms. The study provided new insights into the components of long-term HRV, including the character of its amplitude and frequency modulation obtained with the Hilbert transform. In addition, the reliability of the extracted HF, LF, VLF and ULF waveforms was demonstrated, and MBF turned out to be the most accurate method, though the signal is strongly nonstationary. The possibility of isolating such waveforms is of great importance both in physiology and pathophysiology, as well as in the automation of medical diagnostics based on HRV.
Źródło:
Metrology and Measurement Systems; 2021, 28, 4; 643-660
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of Wearable EEG Device for Seizures Early Detection
Autorzy:
Gaidar, Viktoriia
Sudakov, Oleksandr
Powiązania:
https://bibliotekanauki.pl/articles/1844635.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
circuit design
statistical sampling
Hilbert-Huang transform
feature selection
Opis:
This paper presents the design of a wearable electroencephalography device and signal processing algorithm for early detection and forecasting of the epileptiform activity. The availability of the examination of functional brain activity for a prolonged period, outside of the hospital facilities, can provide new advantages in early diagnosis and intervention systems. In this study, the low-cost five-channel device is presented. The system consists of two main parts: the data acquisition and transmission units and processing algorithms. In order to create the robust epileptiform pattern recognition approach the application of statistical sampling and signal processing techniques are performed. The discrete wavelet and Hilbert-Huang transforms with principal component analysis are used in order to extract and select a low-dimension feature vector.
Źródło:
International Journal of Electronics and Telecommunications; 2021, 67, 2; 187-192
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance Evaluation of MC-CDMA Systems with Single User Detection Technique using Kernel and Linear Adaptive Method
Autorzy:
Fateh, Rachid
Darif, Anouar
Safi, Said
Powiązania:
https://bibliotekanauki.pl/articles/2058482.pdf
Data publikacji:
2021
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
BRAN channels
equalization
kernel method
MC-CDMA
reproducing kernel Hilbert space
Opis:
Among all the techniques combining multi-carrier modulation and spread spectrum, the multi-carrier code division multiple access (MC-CDMA) system is by far the most widely studied. In this paper, we present the performance of the MC-CDMA system associated with key single-user detection techniques. We are interested in problems related to identification and equalization of mobile radio channels, using the kernel method in Hilbert space with a reproducing kernel, and a linear adaptive algorithm, for MC-CDMA systems. In this context, we tested the efficiency of these algorithms, considering practical frequency selective fading channels, called broadband radio access network (BRAN), standardized for MC-CDMA systems. As far as the equalization problem encountered after channel identification is concerned, we use the orthogonality restoration combination (ORC) and the minimum mean square error (MMSE) equalizer techniques to correct the distortion of the channel. Simulation results demonstrate that the kernel algorithm is efficient for practical channel.
Źródło:
Journal of Telecommunications and Information Technology; 2021, 4; 1--11
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral properties of certain operators on the free Hilbert space ℑ [H1, . . . , HN] and the semicircular law
Autorzy:
Cho, Ilwoo
Powiązania:
https://bibliotekanauki.pl/articles/2049008.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
separable Hilbert spaces
free Hilbert spaces
jump operator
shift operators
jump-shift operators
semicircular elements
Opis:
In this paper, we fix N -many l$\text{}_{2}$-Hilbert spaces Hk whose dimensions are $n_{k} \in \mathbb{N}^{\infty} = \mathbb{N} \cup \{\infty\}$ for $k = 1, \ldots, N \in \mathbb{N} \backslash \{1\}$. And then, construct a Hilbert space $\mathfrak{F} = \mathfrak{F}[H_{1}, \ldots, H_{N}]$ induced by $H_{1}, \ldots, H_{N}$, and study certain types of operators on $\mathfrak{F}$. In particular, we are interested in so-called jump-shift operators. The main results (i) characterize the spectral properties of these operators, and (ii) show how such operators affect the semicircular law induced by $\bigcup_{k=1}^{N} \mathcal{B}_{k}$, where Bk are the orthonormal bases of $H_{k}$ , for k = 1, . . . , N.
Źródło:
Opuscula Mathematica; 2021, 41, 6; 755-803
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
General concept of the EMG controlled bionic hand
Autorzy:
Pieprzycki, Adam
Król, Daniel
Powiązania:
https://bibliotekanauki.pl/articles/93068.pdf
Data publikacji:
2020
Wydawca:
Państwowa Wyższa Szkoła Zawodowa w Tarnowie
Tematy:
EMG
neural-network
machine-learning
Fourier transform
Hilbert-Huang transform
Hodgkin-Huxley model
sieć neuronowa
nauczanie maszynowe
przekształcenie Fouriera
transformacja Hilberta-Huanga
model Hodgkina-Huxleya
Opis:
The article presents a general concept of a bionic hand control system using multichannel EMG signal, being under development at present. The method of acquisition and processing of multi-channel EMG signal and feature extraction for machine learning were described. Moreover, the design of the control system implementation in the real-time embedded system was discussed.
Źródło:
Science, Technology and Innovation; 2020, 8, 1; 26-34
2544-9125
Pojawia się w:
Science, Technology and Innovation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hilbert-Schmidtness of weighted composition operators and their differences on Hardy spaces
Autorzy:
Lo, Ching-on
Loh, Anthony Wai-keung
Powiązania:
https://bibliotekanauki.pl/articles/255723.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
weighted composition operators
Hardy spaces
compact operators
Hilbert-Schmidt operators
Opis:
Let u and φ be two analytic functions on the unit disk D such that φ (D) ⊂ D. A weighted composition operator uCφ induced by u and φ is defined on H2, the Hardy space of D, by [formula] for every ∫ in H2. We obtain sufficient conditions for Hilbert-Schmidtness of v,Cv on H2 in terms of function-theoretic properties of u and φ. Moreover, we characterize Hilbert-Schmidt difference of two weighted composition operators on H2.
Źródło:
Opuscula Mathematica; 2020, 40, 4; 495-507
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On some extensions of the a-model
Autorzy:
Jursenas, Rytis
Powiązania:
https://bibliotekanauki.pl/articles/255405.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
finite rank higher order singular perturbation
cascade (A) model
peak model
Hilbert space
scale of Hilbert spaces
Pontryagin space
ordinary boundary triple
Krein Q-function
Weyl function
gamma field
symmetric operator
proper extension
resolvent
Opis:
The A-model for finite rank singular perturbations of class [formula], is considered from the perspective of boundary relations. Assuming further that the Hilbert spaces [formula] admit an orthogonal decomposition [formula], with the corresponding projections satisfying [formula], nontrivial extensions in the A-model are constructed for the symmetric restrictions in the subspaces.
Źródło:
Opuscula Mathematica; 2020, 40, 5; 569-597
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł

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