In this article an algebraic approach to the fault detection for parabolic distributed-parameter systems is described. The modulation functions approach is used to obtain an algebraic fault detection equation, that on...
详细信息
Optical choppers with rotating wheels are some of the most used macroscopic optomechatronic devices for the controlled modulation, attenuation or obscuration of light in a wide area of applications. We discuss and com...
详细信息
Optical choppers with rotating wheels are some of the most used macroscopic optomechatronic devices for the controlled modulation, attenuation or obscuration of light in a wide area of applications. We discuss and compare the modulation functions produced by two types of chopper wheels: the classical device, with windows with linear edges, and the eclipse chopper (with windows with circular edges) that, to the best of our knowledge, we have introduced. This discussion is based on the analysis and the design we have previously developed for these various devices, for top-hat (constant over the entire section) light beam distributions. While the comparison of the different shapes of transmitted signals allows for the proper choice of the most appropriate device and parameters to obtain the modulation function that is fit for a certain application, the present work also presents the mechanical setup we have designed and manufactured for testing choppers with rotating wheels. A series of prototype wheels with different, optimized profiles were obtained for the purpose. The simulation and the electro-erosion programs for the wire electro-erosion of aluminum plates to manufacture the wheels are presented. An advantageous double wheel solution has been developed to obtain wheels with windows of different shapes and sizes, and the testing of this final assembly concludes the study.
In this paper, a data-driven or model-free approach is presented to design a fault detection system of continuous-time linear time-invariant (LTI) systems based on input and output data in the time domain. The main id...
详细信息
In this paper, a data-driven or model-free approach is presented to design a fault detection system of continuous-time linear time-invariant (LTI) systems based on input and output data in the time domain. The main idea is to directly identify the subspaces and their related matrices relevant for parity-space-based residual generation based on a modulated output equation by use of modulation functions and their properties. Therefore, the explicit model identification of the process for a model-based approach in a conventional two-step procedure can be avoided saving design effort especially for large-scale systems. A simulation of the resulting fault detection system is provided showing the effectiveness of the design approach. Copyright (C) 2022 The Authors.
The Hard X-ray Imager (HXI) is one of the scientific payloads onboard the Advanced Space-based Solar Observatory. As a telescope using Fourier space modulation, it contains fine sub-collimators to reach high angular r...
详细信息
The Hard X-ray Imager (HXI) is one of the scientific payloads onboard the Advanced Space-based Solar Observatory. As a telescope using Fourier space modulation, it contains fine sub-collimators to reach high angular resolution. The X-ray resolution of HXI needs to be verified on the ground before its launch. Therefore, an X-ray beam experiment was performed to evaluate the modulation capabilities of each sub-collimator in HXI. The X-ray beam facility for this experiment consisted of an X-ray machine with a 0.4 mm-diameter spot, a 26-meter beam tube with an adjustable diaphragm at the end to control the parallelism of the beam, and an experimental platform that could translate and horizontally rotate the instrument on it with high precision. A strategy for measuring these sub-collimators was then developed theoretically. Additionally, the stability of the instrument and the environment were monitored throughout the experiment. The results of the successful experiment are presented in this paper. The relevant parameters fitted from the measured modulation functions agree well with theoretical predictions. This proves the resolving ability of the HXI meets the requirements. The research also illustrates some side effects due to different incident energies and strengtheners.
An online model-based fault detection and isolation method for salient-pole permanent magnet synchronous motors over a finite horizon is proposed. The proposed approach combines parity-space-based residual generation ...
详细信息
An online model-based fault detection and isolation method for salient-pole permanent magnet synchronous motors over a finite horizon is proposed. The proposed approach combines parity-space-based residual generation and modulation-function-based filtering. Given the polynomial model equations, the unknown variables (i.e. the states, unmeasured inputs) are eliminated resulting in analytic redundancy relations used for residual generation. Furthermore, in order to avoid needing the derivatives of measured signals required by such analytic redundancy relations, a modulation-function-based evaluation is proposed. This results in a finite-horizon filtered version of the original residual. The fault detection and isolation method is demonstrated using simulation of various fault scenarios for a speed controlled salient motor showing the effectiveness of the presented approach. Copyright (C) 2021 The Authors.
In this paper, a data-driven or model-free approach is presented to design a fault detection system of continuous-time linear time-invariant (LTI) systems based on input and output data in the time domain. The main id...
详细信息
In this paper, a data-driven or model-free approach is presented to design a fault detection system of continuous-time linear time-invariant (LTI) systems based on input and output data in the time domain. The main idea is to directly identify the subspaces and their related matrices relevant for parity-space-based residual generation based on a modulated output equation by use of modulation functions and their properties. Therefore, the explicit model identification of the process for a model-based approach in a conventional two-step procedure can be avoided saving design effort especially for large-scale systems. A simulation of the resulting fault detection system is provided showing the effectiveness of the design approach.
An online model-based fault detection and isolation method for salient-pole permanent magnet synchronous motors over a finite horizon is proposed. The proposed approach combines parity-space-based residual generation ...
详细信息
An online model-based fault detection and isolation method for salient-pole permanent magnet synchronous motors over a finite horizon is proposed. The proposed approach combines parity-space-based residual generation and modulation-function-based filtering. Given the polynomial model equations, the unknown variables (i.e. the states, unmeasured inputs) are eliminated resulting in analytic redundancy relations used for residual generation. Furthermore, in order to avoid needing the derivatives of measured signals required by such analytic redundancy relations, a modulation-function-based evaluation is proposed. This results in a finite-horizon filtered version of the original residual. The fault detection and isolation method is demonstrated using simulation of various fault scenarios for a speed controlled salient motor showing the effectiveness of the presented approach.
The benefit of computational methods applying density functional theory for the description and understanding of modulated crystal structures is investigated. A method is presented which allows one to establish, impro...
详细信息
The benefit of computational methods applying density functional theory for the description and understanding of modulated crystal structures is investigated. A method is presented which allows one to establish, improve and test superspace models including displacive and occupational modulation functions from firstprinciples calculations on commensurate structures. The total energies of different configurations allow one to distinguish stable and less stable structure models. The study is based on a series of geometrically optimized superstructures of mullite (A(l4+2x)Si(2-2x)O(10-x)) derived from the superspace group Pham(alpha 01/2)0ss. Despite the disordered and structurally complex nature of mullite, the calculations on ordered superstructures are very useful for determining the ideal Al/Si ordering in mullite, extracting atomic modulation functions as well as understanding the SiO2-Al2O3 phase diagram. The results are compared with experimentally established models which confirm the validity and utility of the presented method.
We present in this paper our results regarding the modeling of the modulation functions of the light flux of optical choppers working with top-hat (constant) light beam distributions. Two configurations of chopper whe...
详细信息
ISBN:
(纸本)9780819486790
We present in this paper our results regarding the modeling of the modulation functions of the light flux of optical choppers working with top-hat (constant) light beam distributions. Two configurations of chopper wheels are considered: with windows with linear and with circular margins (the latter, to the best of our knowledge, we have introduced, works as an "eclipse" chopper). A rigorous analytical modeling has been performed for each type of device. For the first configuration, of windows with linear margins, all the four possible relationships between the diameter of the beam in the plane of the wheel and the dimensions of the window of the chopper have been considered and are discussed: (i) large wing and focused beam [in the plane of the wheel];(ii) large wing and beam of finite diameter in the plane of the wheel, but with a wing large enough to cover the section of the beam;(iii) narrow wing, finite diameter beam and large windows, so there is only one wing at a time in front of the beam section;(iv) narrow wings and windows, so there are more wings at a time in front of the beam section. A recent study covered experimentally case (ii) presented above, obtaining a particular signal function (with an approximate trapezoidal profile). The second and more general wheel configuration that we have proposed in a previous study, with windows with circular margins (for which by example choppers with circular windows are a particular case) is also discussed. Both outwards and inwards circular margins are considered. The modulation functions of this second type of devices are also derived, studied and compared to those for the first, classical types of wheels (with windows with linear margins), which are but a particular case of this second type of chopper. From this study, the various profiles of the function of the transmitted flux are obtained: rectangular, approximate trapezoidal, approximate triangular, sinusoidal, and with non-null values. The possible geometrie
Choppers are most used devices for the modulation of light. We have developed a unitary theory of the optical choppers with rotating wheels working with top-hat laser beams (with constant intensity distribution). A no...
详细信息
ISBN:
(纸本)9783319082653
Choppers are most used devices for the modulation of light. We have developed a unitary theory of the optical choppers with rotating wheels working with top-hat laser beams (with constant intensity distribution). A novel type of chopper has been introduced, with windows with non-linear edges. The different modulation functions (of the transmitted light flux) were obtained. From this analysis, design programs are developed and presented in this study to tackle with the diverse cases represented by the chopper configurations and by their constructive and functional parameters. Numerical simulations and modeling are carried out based on the mathematical theory we have previously developed. Rules of thumb result to choose the most appropriate type of device and its characteristic parameters with regard to the particular requirements of a specific application. Top-hat (with constant intensity), Gaussian, and Bessel laser beams are considered in this study.
暂无评论