Academic literature on the topic 'Aktive filters for higher frequencies'
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Journal articles on the topic "Aktive filters for higher frequencies"
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Pinheiro, Ricardo Bressan, and José Roberto C. Piqueira. "Designing All-Pole Filters for High-Frequency Phase-Locked Loops." Mathematical Problems in Engineering 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/682318.
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Since the phase-locked loop (PLL) circuit was proposed in the 1930s, it is being used for a lot of situations when precise frequency and phase references are required. Among these applications, synchronous telecommunication networks experienced a strong development in order to support the explosive information traffic that the modern society demands. Consequently, bandwidth became a decisive parameter, implying higher and higher frequencies for the clock signals exchanged between the nodes of the networks and detected by PLLs. The necessity to improve clock precision that follows the bandwidth increase provoked the improvement of the filter component of the PLLs, avoiding instability and high-frequency components in the reference signals. Here, a technique of designing this kind of filter is presented, considering second-order filters, implying third-order PLLs. Simulations show that following this technique produces very fast tracking processes, enabling precise operation even for very high frequencies.
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Yagan, Rawana, Ferhat Katmis, and Mehmet C. Onbaşlı. "Engineered Magnetization Dynamics of Magnonic Nanograting Filters." Magnetochemistry 7, no. 6 (June 3, 2021): 81. http://dx.doi.org/10.3390/magnetochemistry7060081.
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Magnonic crystals and gratings could enable tunable spin-wave filters, logic, and frequency multiplier devices. Using micromagnetic models, we investigate the effect of nanowire damping, excitation frequency and geometry on the spin wave modes, spatial and temporal transmission profiles for a finite patterned nanograting under external direct current (DC) and radio frequency (RF) magnetic fields. Studying the effect of Gilbert damping constant on the temporal and spectral responses shows that low-damping leads to longer mode propagation lengths due to low-loss and high-frequency excitations are also transmitted with high intensity. When the nanowire is excited with stronger external RF fields, higher frequency spin wave modes are transmitted with higher intensities. Changing the nanowire grating width, pitch and its number of periods helps shift the transmitted frequencies over super high-frequency (SHF) range, spans S, C, X, Ku, and K bands (3–30 GHz). Our design could enable spin-wave frequency multipliers, selective filtering, excitation, and suppression in magnetic nanowires.
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Sengar, Kanchan, and Arun Kumar. "Fractional Order Capacitor in First-Order and Second-Order Filter." Micro and Nanosystems 12, no. 1 (January 21, 2020): 75–78. http://dx.doi.org/10.2174/1876402911666190821100400.
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Background: Fractional order Butterworth and Chebyshev (low-pass filter circuits, highpass filter circuits and band-pass filters circuits) types of first and second order filter circuits have been simulated and their transfer function are derived. The effect of change of the fractional order α on the behavior of the circuits is investigated. Objective: This paper presents the use of fractional order capacitor in active filters. The expressions for the magnitude, phase, the quality factor, the right-phase frequencies, and the half power frequencies are derived and compared with their previous counterpart. Methods: The circuits have been simulated using Orcad as well as MATLAB for the different value of α. We have developed the fractional gain and phase equations for low pass filter circuits, high pass filter circuits and band pass filter circuits in Sallen-Key topology. Results: It is observed that the bandwidth increases significantly with fractional order other than unity for the low pass as well as high pass and band pass filters. Conclusion: We have also seen that in the frequency domain, the magnitude and phase plots in the stop band change nearly linearly with the fractional order. If we compare the fractional Butterworth filters for low-pass and high-pass type with conventional filters then we find that the roll-off rate is equal to the next higher order filter.
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Yiannakopoulos, G., and P. J. van der Schaaf. "Evaluation of Accelerometer Mechanical Filters on Submerged Cylinders Near an Underwater Explosion." Shock and Vibration 5, no. 4 (1998): 255–65. http://dx.doi.org/10.1155/1998/513249.
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An accelerometer, mounted to a structure near an explosion to measure elasto-plastic deformation, can be excited at its resonant frequency by impulsive stresses transmitted within the structure. This results in spurious high peak acceleration levels that can be much higher than acceleration levels from the explosion itself. The spurious signals also have higher frequencies than the underlying signal from the explosion and can be removed by a low pass filter. This report assesses the performance of four accelerometer and filter assemblies. The assessment involves measurements of the response of a mild steel cylinder to an underwater explosion, in which each assembly is mounted onto the interior surface of the cylinder. Three assemblies utilise a piezoresistive accelerometer in which isolation is provided mechanically. In the fourth assembly, a piezoelectric accelerometer, with a built-in filter, incorporates both mechanical and electronic filtering. This assembly is found to be more suitable because of its secure mounting arrangement, ease of use, robustness and noise free results.
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Fursov, V. A. "Constructing a quadratic-exponential FIR-filter with an extended frequency response midrange." Computer Optics 42, no. 2 (July 24, 2018): 297–305. http://dx.doi.org/10.18287/2412-6179-2018-42-2-297-305.
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This article is concerned with synthesizing filter with finite impulse response (FIR-filters) employed to correct radially symmetric distortions such as defocusing. We propose a new parametric class of finite impulse response filters (FIR-filters) based on a model of the one-dimensional radially symmetric frequency response. In the proposed method, the one-dimensional frequency response is composed of quadratic and exponential functions. The two-dimensional impulse response of the filter is constructed by sampling one-dimensional impulse responses for all directions. The development consists in introducing an extended mid-frequency region of the frequency response, thus increasing the contribution of the frequencies to image correction. Examples are given in order to illustrate the possibility of the high-quality distortion correction. In particular, it is shown that the proposed method provides the restoration quality higher than that obtained when using an optimal Wiener filter (taken from OpenCV).
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Smirnov, A. V. "The analysis of conditions for preservation of gain-frequency and phase-frequency characteristics optimality under analog and digital filters transformation." Russian Technological Journal 8, no. 2 (April 14, 2020): 43–58. http://dx.doi.org/10.32362/2500-316x-2020-8-2-43-58.
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Prototype filters have wide usage for the design of filters with required quality indexes (QI) of gain-frequency response (GFR). The designed filter is obtained from a prototype filter b means of frequency transformation, which preserves these QI. But most of employed frequency transformations result in variations of QI of phase-frequency response (PFR). In this paper we proposed to use prototype filters that are Pareto-optimal for QI of GFR and PFR. Transfer functions of these filters may be found by means of heuristic optimization algorithms. This method will be efficient if the frequency transformation preserves the optimality of filters. It was shown that frequency transformation has this feature if it preserves the result of QI comparison (more or less) for filters with equal orders. Compliance of this criterion was checked for bilinear transformation of analog low pass filters (LPF) into digital LPF and for Konstantinidis transformation of digital LPF into other digital LPF. The analysis showed that Pareto-optimality for QI of GFR and PFR is preserved if the delay-frequency characteristic of the filter has a minimum at zero frequency and has a maximum at the upper boundary of the pass band. These conditions are complied for LPF with sufficiently small unevenness of GFR in the pass band and sufficiently fast decline of GFR at higher frequencies. Examples confirming these conclusions are given.
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Astel, Aleksander, Marcin Stec, and Iwona Rykowska. "Occurrence and Distribution of UV Filters in Beach Sediments of the Southern Baltic Sea Coast." Water 12, no. 11 (October 28, 2020): 3024. http://dx.doi.org/10.3390/w12113024.
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The interest in UV filters’ occurrence in the environment has increased since they were recognized as “emerging contaminants” having potentially adverse impacts on many ecosystems and organisms. Increased worldwide demand for sunscreens is associated with temperature anomalies, high irradiance, and changes in the tourist market. Recently, it has been demonstrated that personal care products, including sunscreens, appear in various ecosystems and geographic locations causing an ecotoxicological threat. Our goal was to determine for the first time the presence of selected organic UV filters at four beaches in the central Pomeranian region in northern Poland and to assess their horizontal and vertical distribution as well as temporal variation at different locations according to the touristic pressure. In this pioneering study, the concentration of five UV filters was measured in core sediments dredged from four exposed beaches (Darłowo, Ustka, Rowy, and Czołpino). UV filters were detected in 89.6% of collected cores at detection frequencies of 0–22.2%, 75–100%, 0–16.7%, and 2.8–25% for benzophenone-1 (BP-1), benzophenone-2 (BP-2), benzophenone-3 (BP-3), and enzacamene (4-MBC), respectively. In terms of seasonality, the concentration of UV filters generally increased in the following order: summer > autumn > spring. No detectable levels of 3-BC (also known as 3-benzylidene camphor) were recorded. No differences were found in the concentration of UV filters according to the depth of the sediment core. During the summer and autumn seasons, all UV filters were detected in higher concentrations in the bathing area or close to the waterline than halfway or further up the beach. Results presented in this study demonstrate that the Baltic Sea coast is not free from UV filters. Even if actual concentrations can be quantified as ng·kg−1 causing limited environmental threat, much higher future levels are expected due to the Earth’s principal climatic zones shifting northward.
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Zhang, Xin, Wensheng Hou, Xiaoying Wu, Lin Chen, and Ning Jiang. "Enhancing Detection of SSMVEP Induced by Action Observation Stimuli Based on Task-Related Component Analysis." Sensors 21, no. 16 (August 4, 2021): 5269. http://dx.doi.org/10.3390/s21165269.
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Action observation (AO)-based brain-computer interface (BCI) is an important technology in stroke rehabilitation training. It has the advantage of simultaneously inducing steady-state motion visual evoked potential (SSMVEP) and activating sensorimotor rhythm. Moreover, SSMVEP could be utilized to perform classification. However, SSMVEP is composed of complex modulation frequencies. Traditional canonical correlation analysis (CCA) suffers from poor recognition performance in identifying those modulation frequencies at short stimulus duration. To address this issue, task-related component analysis (TRCA) was utilized to deal with SSMVEP for the first time. An interesting phenomenon was found: different modulated frequencies in SSMVEP distributed in different task-related components. On this basis, a multi-component TRCA method was proposed. All the significant task-related components were utilized to construct multiple spatial filters to enhance the detection of SSMVEP. Further, a combination of TRCA and CCA was proposed to utilize both advantages. Results showed that the accuracies using the proposed methods were significant higher than that using CCA at all window lengths and significantly higher than that using ensemble-TRCA at short window lengths (≤2 s). Therefore, the proposed methods further validate the induced modulation frequencies and will speed up the application of the AO-based BCI in rehabilitation.
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Lee, Hyeon Kyu, and Young-Seok Choi. "Enhancing SSVEP-Based Brain-Computer Interface with Two-Step Task-Related Component Analysis." Sensors 21, no. 4 (February 12, 2021): 1315. http://dx.doi.org/10.3390/s21041315.
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Among various methods for frequency recognition of the steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) study, a task-related component analysis (TRCA), which extracts discriminative spatial filters for classifying electroencephalogram (EEG) signals, has gathered much interest. The TRCA-based SSVEP method yields lower computational cost and higher classification performance compared to existing SSVEP methods. In spite of its utility, the TRCA-based SSVEP method still suffers from the degradation of the frequency recognition rate in cases where EEG signals with a short length window are used. To address this issue, here, we propose an improved strategy for decoding SSVEPs, which is insensitive to a window length by carrying out two-step TRCA. The proposed method reuses the spatial filters corresponding to target frequencies generated by the TRCA. Followingly, the proposed method accentuates features for target frequencies by correlating individual template and test data. For the evaluation of the performance of the proposed method, we used a benchmark dataset with 35 subjects and confirmed significantly improved performance comparing with other existing SSVEP methods. These results imply the suitability as an efficient frequency recognition strategy for SSVEP-based BCI applications.
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Smith, A. T., and C. M. Baker-Short. "Pharmacological separation of mechanisms contributing to human contrast sensitivity." Visual Neuroscience 10, no. 6 (November 1993): 1073–79. http://dx.doi.org/10.1017/s095252380001018x.
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AbstractTwo basic types of cholinergic receptor have been identified in nervous systems: nicotinic and muscarinic. In the mammalian visual system, the balance of evidence suggests that nicotinic activity is associated primarily with transmission and processing of information while muscarinic activity reflects modulatory influences arising in the brainstem and basal forebrain. We have measured contrast sensitivity functions using a two-alternative forced-choice procedure in young human volunteers with and without administration of nicotine (1.5 mg by buccal absorption) or the muscarinic antagonist scopolamine (1.2 mg orally). Scopolamine elevates contrast-detection thresholds uniformly at all spatial frequencies, consistent with blocking of a nonspecific arousal system. Nicotine, in contrast, improves sensitivity at low spatial frequencies (below about 4 cycle/deg); at higher spatial frequencies sensitivity is, if anything, impaired. Using counterphase gratings, we find that scopolamine elevates thresholds uniformly at all temporal frequencies. Nicotine lowers thresholds at high but not low temporal frequencies. The results obtained with nicotine suggest that contrast sensitivity reflects the activity of two mechanisms, or sets of spatiotemporal filters, that are pharmacologically distinct, the contrast sensitivity function reflecting the envelope of their sensitivities.
Dissertations / Theses on the topic "Aktive filters for higher frequencies"
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Axman, Vladimír. "Obvody s moderními aktivními prvky." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-233441.
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PhD. thesis is deals about sekond order ARC filters for cascade synthezis of Active filters. Here are presented new configurations of second order filters with current conveyors usable for higher frequencies and new second order filters with current conveyors usable for electrical tunable filters. In PhD. Thesis are presented schematics and equations for new sekond order filters. There are presented also practical realizations of these filters and basic measure results.
Books on the topic "Aktive filters for higher frequencies"
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Fermüller, Cornelia. Motion Illusions in Man and Machine. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199794607.003.0006.
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At the level of mathematical abstraction, computing image motion amounts to an estimation problem and can be analyzed using the tools of statistics and signal processing. As shown in this chapter, intrinsic limitations to the estimation processes make it impossible to derive veridical estimates for all images. Image motion is estimated erroneously, and as a result higher level processes compute erroneous three-dimensional motion and moving scenes. Specifically, two limitations are discussed: (a) due to noise in image data, there is statistical bias that affects anisotropic patterns and (2) the filters computing changes in time are asymmetric (causal), using data only from the past but not the future, and misestimate on locally asymmetric intensity signals of certain spatial frequencies. Since these limitations are not an artifact of the hardware but are inherent to the computations, they will affect any system and thus create illusions in man and machine.
Book chapters on the topic "Aktive filters for higher frequencies"
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Banerjee, Amal. "Higher Frequencies (100’s of MHz to 10’s of GHz): Physical Constraints and Distributed Filters." In Automated Electronic Filter Design, 67–82. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-43470-4_4.
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Hari, Riitta, and Aina Puce. "Data Acquisition and Preprocessing." In MEG-EEG Primer, edited by Riitta Hari and Aina Puce, 89–97. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190497774.003.0007.
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This chapter introduces principles of MEG/EEG data acquisition and preprocessing. MEG and EEG are recorded as analog (continuous-value) signals, amplified, and then filtered to remove undesirable components with lower and higher frequencies relative to the signals of interest. The analog signals are transformed to digital form by sampling (also called digitization) at rates that avoid aliasing, a very serious signal distortion described in this chapter; the appropriate sampling frequencies are at least 2 times the highest frequency in the sampled data (so-called Nyquist criterion). Different filter types (lowpass, highpass, bandpass, and notch) and their cut-off frequencies and roll-offs are examined. Examples of pitfalls that can occur with incorrectly selected filters and sampling rates are presented.
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Nordin, Anis Nurashikin. "RF-MEMS Based Oscillators." In Advances in Wireless Technologies and Telecommunication, 120–55. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-0083-6.ch006.
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Today’s high-tech consumer market demand complex, portable personal wireless consumer devices that are low-cost and have small sizes. Creative methods of combining mature integrated circuit (IC) fabrication techniques with innovative radio-frequency micro-electro-mechanical systems (RF-MEMS) devices has given birth to wireless transceiver components, which operate at higher frequencies but are manufactured at the low-cost of standard ICs. Oscillators, RF bandpass filters, and low noise amplifiers are the most critical and important modules of any wireless transceiver. Their individual characteristics determine the overall performance of a transceiver. This chapter illustrates RF-oscillators that utilize MEMS devices such as resonators, varactors, and inductors for frequency generation. Emphasis will be given on state of the art RF-MEMS components such as film bulk acoustic wave, surface acoustic wave, flexural mode resonators, lateral and vertical varactors, and solenoid and planar inductors. The advantages and disadvantages of each device structure are described, with reference to the most recent work published in the field.
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Magee, Patrick, and Mark Tooley. "Electronics and Biological Signal Processing." In The Physics, Clinical Measurement and Equipment of Anaesthetic Practice for the FRCA. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199595150.003.0009.
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This chapter continues the discussion of electricity but looks at the effect of connecting components together and briefly looks at the operational amplifier and active circuits (circuits discussed in the previous chapter have been passive ones, which involve no electronic circuits). It will then describe how the circuits can be used to process biological signals. If a resistor, an inductor and a capacitor are joined as in Figure 5.1, the magnitude of the voltage across the resistor (Vout) will vary as the input frequency, Vin, changes, because of the properties of the capacitor and inductor. The resistive action of inductor and capacitor oppose each other, and at a certain resonant frequency (r in the figure), the total AC resistance (impedance) will be at a minimum. The graph of reactance against frequency demonstrates this, and shows the minimum reactance at the resonant frequency. As the LC and R are forming a voltage divider, the voltage across R will be maximum at this frequency. At other input frequencies, the output voltage will be low. This simple circuit forms the basics of the passive band-pass filter, where the filter passes, or lets through, a certain band of frequencies (around the resonant frequency in this circuit). Frequencies lower or higher than the band-pass will be attenuated. Normally operational amplifiers (discussed in the next section) or digital filters are more effective and are used to achieve the same effect. Resonance is important for the understanding of the behaviour of transducers and this is discussed in Chapter 12. If a square wave is applied to the resistor capacitor network as shown in Figure 5.2, the capacitor charges up on the rising edge of the input with a time constant equal to the product of the resistance (Ω) and the capacitance (F), RC, and the output voltage will be Vouput = Vinput (1 − e−t /RC ). When the square wave is in the off state, or zero volts, the voltage will fall exponentially with the same time constant. It can be seen from the diagram that, with the appropriate values of R and C, the output from the network is a filtered version of the input.
Conference papers on the topic "Aktive filters for higher frequencies"
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Spadoni, A., and C. Daraio. "Vibration Isolation via Linear and Nonlinear Periodic Devices." In ASME 2009 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/detc2009-87620.
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The current manuscripts deals with the design of passive mechanical filters for vibration attenuation a low frequencies. Traditionally, this has been addressed employing dissipation as the attenuation mechanism. While such strategy provides broad-frequency effectiveness, attenuation at any given frequency is modest. Mass and stiffness-modulated periodic systems, on the other hand, exploit dispersion as the attenuation mechanism and represent an alternative to dissipation-based devices. Attenuation due to dispersion may be significantly higher than what is afforded by dissipation-based systems within a design frequency rage. The proposed assemblies, however, are not easily tailored to filter lowe-frequency vibrations. To this end, embedding such periodic systems into an elastic matrix yields a high-pass mechanical filter with tunable stop bands were waves are not allowed to propagate. Significant improvements in performance moreover may be obtained if intrinsically nonlinear devices are adopted. Specifically, a strongly nonlinear medium such as ordered granular media supports a limited number of waveforms, resulting in an efficient mechanical filter. Results reported here, in fact, suggest matrix-embedded sphere chains as highly tunable mechanical filters for vibration attenuation.
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Fronk, Matthew D., and Michael J. Leamy. "Internal Resonance of Plane Waves in Nonlinear Lattices." In ASME 2019 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/detc2019-97879.
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Abstract Recent studies have employed perturbation techniques to derive amplitude-dependent band structures in nonlinear periodic materials. The associated applications include amplitude-dependent filters, waveguides, and diodes. However, for a range of frequencies and wavenumbers, perturbation-based dispersion corrections for a single wave break-down due to internal resonance between the primary wave and its nonlinearity-induced higher-harmonics. This work presents a perturbation analysis of one-dimensional plane waves in lattices with internal resonances. The exchange of energy between propagating modes within the same branch of the lattice’s band structure is considered, and the stability of the energy exchange is assessed through a local analysis. Direct numerical integration of the lattice equations of motion validates the analytical expressions for energy exchange. These findings can be used to resolve discontinuities in band diagrams that do not account for internal resonances and may inspire new technology that enables long-range coherent signal transmission in nonlinear media.
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Veloz, Alejandro, Juan C. Romero Quintini, Mónica Parada, and Sergio E. Diaz. "Experimental Testing of a Magnetically Levitated Rotor With a Neural Network Controller." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69120.
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Magnetic bearings represent a solution for high rotating speeds and sterile environments where lubrication fluids could contaminate. They can also be used in systems where maintenance is difficult or inaccessible, because they don’t require auxiliary lubrication systems and don’t suffer mechanic wear as they work with no contact between rotor and bearing stator. An important part of magnetic bearings is the controller; which is needed to stabilize the system. This controller is generally a PID in which tuning and/or filters design can be complicated for not well known systems. This work presents results of the development of a neural network controller, which is potentially easier to implement, to control the position of a magnetically suspended rotor. The proposed controller is based in the identification of the system inverse model. This is achieved first by implementing a simple PID capable of levitating the rotor, and then some excitations are applied to the rotor in order to acquire data of the position of the rotor and current in the actuators. Current and position data is used to train the artificial neural network for the controller. The controller was implemented in a numerical model and also in an experimental system with a rotor of 1.06kg and 300mm in length. The implementation of SISO, MISO and MIMO neural controllers (both with offline and online training) and a conventional PID with neural network compensation are compared. Structures and architectures of networks are shown. Vibration responses to: a constant force; a controlled impact and a constant acceleration ramp between 0 and 12500rpm are compared. Results in both, numeric model and experimental system, show that neural network controllers are capable of hovering the rotor and control vibrations. Peak-Peak amplitudes vs. rpm plots are similar to a conventional PID. In most cases, the neural network controllers show amplitudes slightly lowers on low frequencies and slightly higher on higher frequencies, except the conventional PID with neural network compensation case, were the system responses as with higher damping. Finally, a discussion is made about future steps in research to improve implementation of a neural controller that is potentially simpler and faster in terms of tuning and with a comparable performance to a conventional magnetic bearing PID controller.
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Poigai Arunachalam, Shivaram, Elizabeth M. Annoni, Suraj Kapa, Siva K. Mulpuru, Paul A. Friedman, and Elena G. Tolkacheva. "Robust Discrimination of Normal Sinus Rhythm and Atrial Fibrillation on ECG Using a Multiscale Frequency Technique." In 2017 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/dmd2017-3302.
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Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia affecting approximately 3 million Americans, and is a prognostic marker for stroke, heart failure and even death [1]. 12-lead electrocardiogram (ECG) is used to monitor normal sinus rhythm (NSR) and also detect AF. Although the persistent form of AF can be detected relatively easy, detecting paroxysmal AF is often a challenge since requiring continuous monitoring, which becomes expensive and cumbersome to collect lot of ECG data [1]. Several researchers have attempted to develop new methods to discriminate NSR and AF which are based on R-R interval analysis, linear methods, filtering, spectral analysis, statistical approaches such as entropy etc. which faces limitation of successfully detecting AF of all types with high sensitivity and specificity using short time ECG data [1–3]. The major issues with these approaches is that they often distort the ECG by several pre-processing steps with filters, do not provide reliable discrimination using short ECG time series data and many of them lack real-time capability that makes it difficult to trust the data for diagnosis and treatment. Both clinical and scientific communities recognize these difficulties and the necessity to develop novel methods that can enable accurate monitoring and detection of AF [2]. In addition, robust detection and classification algorithms are essential for delivering appropriate therapy for implantable cardioverter defibrillators (ICD) to provide lifesaving timely action. In this work, the authors propose and demonstrate the application of a multiscale frequency (MSF) approach [4] for accurate detection and discrimination between AF and NSR ECG traces taken from publically available Physionet database. The MSF approach takes into account the contribution from various frequencies in ECG and thus yield valuable information regarding the chaotic nature of AF. Therefore, we demonstrate that MSF can capture the complexity of AF which is associated with higher MSF value compared with NSR thus enabling robust discrimination e AF manifests itself with numerous chaotic frequencies within the body surface ECG,. We validate the feasibility of this technique to discriminate NSR from AF.
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González-Cruz, Claudia, Juan Jauregui, and Marco Ceccarelli. "Dynamic Characterization of a Two Degree of Freedom Planetary Gearbox During Varying Load Conditions." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91862.
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Abstract This paper presents the dynamic characterization of a two degree of freedom planetary gearbox prototype during the variation of the load condition. Tests with varying load are developed at three different operating speeds of the input shaft: 190, 380 and 590 rpm. The dynamic torques and vibrations on the input and output shafts are acquired during the experiments, such as the angular velocity of the output shaft. The experimental data are analyzed to evaluate the dynamics of the system during the exchange of operation between the first and second DOF operation. Then, the radial vibrations are analyzed during the operation of the second DOF by means of a methodology using different signal processing tools: first, the continuous wavelet transform is used to identify the nonlinear behavior and the main frequency content of the system; then, the vibrations are filtered by means of passband filters in order to keep the main frequencies of the system and delete any other; finally, the filtered signals are analyzed with both, the Kuramoto’s order parameter to quantify the dynamic synchronization of the gearbox and the phase diagram to characterize its stability. The results demonstrates the utility of the second DOF in the design of the planetary gearbox in order to avoid excessive torques in the components of the system. Furthermore, it is found that the synchronization of the system increases at higher operating speed, however, the system becomes unstable as the operating speed is increased.