Rectangular Window Research Articles

Improvement of three-phase group transformers for powering the electric drive of submersible centrifugal pumps and comparison of their technical level indicators

The possibility of improving the power supply system of the electric drive of submersible pumps is indicated. The modernization is carried out by replacing the design of single-phase toroidal transformers composed into the group transformer, with spatial single-phase transformers with a radial electromagnetic system. The radial electromagnetic system is characterized by the convenience of embedding into shells of a limited diameter, by a shorter average turn length, and the absence of winding laying disadvantages. The main task is to determine and to analyze the technical level indicators for spatial twisted electromagnetic systems options. The objective function optimization method is used to solve the problem. The objective function contains technical condition dimensionless indicators as well as relative geometric controlled variables. The extremum of the objective function relative components is a function of the winding window, the conductive material of the winding and three universal identical geometric controlled variables which can be used for any of the existing electromagnetic systems variants. In accordance with the principle of electromagnetic equivalence, the same materials, the average values of the amplitudes of the magnetic flux induction in the rods and yokes, the filling factor of the magnetic circuit with steel, as well as cooling methods of the induction static devices are respectively used. The results of the comparative analysis of the technical level indicators (mass, active materials cost and active power losses) showed that the design of a twisted radial electromagnetic system with a rectangular cross-section of rods provides a significant reduction in mass, cost and losses, as compared to an equivalent analogue with a toroidal electromagnetic system

Evaluation of Filtering Techniques applied to simulated Electroencephalogram signals for Visual Evoked Potential Detection

Introduction: In this paper, it is presented an assessment of different windowing techniques and denoising methods applied to detect the Visual Evoked Potential (VEP) contained into the electroencephalographic (EEG) signals. The objective is to analyze advantages and disadvantages of each technique performance to identify correctly the VEP waveform and to quantify the latency which is a parameter commonly used as an indicator of ocular diseases. Method: Assessment of techniques was performed considering rigorous controlled conditions on the signal set, to assure that obtained results were linked just to the technique performances and avoid any undesirable effect due to the natural interference of acquisition of signals. For this reason, a simulated signals set was created based on a typical VEP waveform commonly registered around 100ms after an external stimulus was applied in the routine clinical study. Additionally, two evaluation stages were considered: fixed latency parameters stage and random latency parameters stage.Results: The best results without filter was with rectangular window and the use of elliptic filter can help to extract the VEP with a rectangular window too. For wavelet denoising the best result is Biorthogonal 2.6 wavelet with a Hamming window. Discussion or Conclusion: Five parameters were proposed to assessment the VEP extraction performed: signal noise ratio (SNR) mean square error (MSE), average latency (AL), latency standard deviation (LSD) and latency correlation variance (LCV) as representative factors to be considered on evaluations of VEP extraction methods. SNR and MSE were focused to assess the level of noise that remain in signal after windowing & denoising method was applied. In the other hand AL, LSD and LCV were oriented to evaluate the impact of the method on the VEP latency estimation.

Differences in Power Spectral Densities and Phase Quantities Due to Processing of EEG Signals.

There has been a growing interest in computational electroencephalogram (EEG) signal processing in a diverse set of domains, such as cortical excitability analysis, event-related synchronization, or desynchronization analysis. In recent years, several inconsistencies were found across different EEG studies, which authors often attributed to methodological differences. However, the assessment of such discrepancies is deeply underexplored. It is currently unknown if methodological differences can fully explain emerging differences and the nature of these differences. This study aims to contrast widely used methodological approaches in EEG processing and compare their effects on the outcome variables. To this end, two publicly available datasets were collected, each having unique traits so as to validate the results in two different EEG territories. The first dataset included signals with event-related potentials (visual stimulation) from 45 subjects. The second dataset included resting state EEG signals from 16 subjects. Five EEG processing steps, involved in the computation of power and phase quantities of EEG frequency bands, were explored in this study: artifact removal choices (with and without artifact removal), EEG signal transformation choices (raw EEG channels, Hjorth transformed channels, and averaged channels across primary motor cortex), filtering algorithms (Butterworth filter and Blackman–Harris window), EEG time window choices (−750 ms to 0 ms and −250 ms to 0 ms), and power spectral density (PSD) estimation algorithms (Welch’s method, Fast Fourier Transform, and Burg’s method). Powers and phases estimated by carrying out variations of these five methods were analyzed statistically for all subjects. The results indicated that the choices in EEG transformation and time-window can strongly affect the PSD quantities in a variety of ways. Additionally, EEG transformation and filter choices can influence phase quantities significantly. These results raise the need for a consistent and standard EEG processing pipeline for computational EEG studies. Consistency of signal processing methods cannot only help produce comparable results and reproducible research, but also pave the way for federated machine learning methods, e.g., where model parameters rather than data are shared.

Train-induced ground vibration due to the irregularities of the soil

Many measurements of train induced ground vibrations show high amplitudes for a certain mid-frequency range. This ground vibration component cannot be well explained by dynamic loads of the train. Many characteristics indicate that the axle impulses, which are scattered by an irregular soil, are the excitation. This new understanding of railway-induced ground vibration is verified by numerical analysis. The response of the regular homogeneous and irregular inhomogeneous soils has been calculated by the finite-element method in frequency domain. A specific superposition of the impulse responses has been invented including time shift, axle sequence, track filter and hanning filter. The superposition yields the quasi-static component of the ground vibration which is restricted to very low frequencies and to the close near-field of the track. In case of an irregular soil of which the stiffness varies randomly in space, the superposition yields a mid-frequency ground vibration component from the scattering of the axle impulses. The existence and the importance of this component can thus be demonstrated by the calculations. Some rules of the influence of distance, train speed, soil stiffness, strength and width of the stiffness variation have been derived from the calculations. Many measurements show the unique explanation of the mid-frequency ground vibration component by the scattered axle impulses.

Parabolic pulse generation based on a multiply operation of two triangular pulses

A scheme of parabolic pulse generation is proposed and verified by simulations and experiments. Based on a multiply operation, a parabolic pulse can be obtained by carving a triangular envelope with a triangular time window. Theoretical analysis shows that an ideal dark parabolic pulse and frequency-doubled parabolic pulse can be generated under the triangular profile with the second-order approximation. The corresponding fitting degrees of the two types of parabolic pulses are beyond 99% and 97%, respectively. In the experiment, the flexibility is demonstrated, which perfectly agrees with the theoretical expectation.

Power Spectral Density Computation and Dominant Frequencies Identification from the Vibration Sensor Output under Random Vibration Environment

The objective of the modal and spectral analysis is to determine the vibration characteristics of structures such as natural frequencies, dominant frequencies and mode shapes. Such modal and spectral analyses have major relevance to the study of the dynamic properties of the structures undergoing dynamic vibration. Methods for the estimation of the power spectral density and identification of the dominant frequencies from the sensor responses under random vibrating environment are presented in this paper. Periodogram using FFT, Welch Method and MUSIC algorithm are used to analyse the known frequency sinusoids with additive white noise and output of the vibration sensor mounted on the test object. The resultant spectra obtained using the methods and their corresponding errors with the reference spectrum are analysed. The Welch method is further studied with three different windows, namely, Hann, Hamming and Blackman-Harris and with three different overlapping criteria viz. 0%, 25% and 50%. The same algorithm and methodology were adopted and compared in two different platforms: Mathematical Model Simulation and Hardware-In-Loop-Simulation. It is observed from the results that Welch Method with 25% overlap used in combination either with Hann or Blackman-Harris window yields more accurate results, compared to other combinations. Also, 25% overlap provides better execution time trade-off compared to 50% overlap.

Depth of Interaction Measurements Based on Rectangular Light Sharing Window Technology and Nine-Crystals-to-One-SiPM Coupling Method

Depth of interaction (DOI) decoding capability shows great application potential for positron emission tomography (PET), especially for high-resolution small-animal PET or long axial field of view PET systems. On the basis of GATE optical simulation results, we presented a novel $9\times 9$ lutetium–yttrium oxyorthosilicate array with 10-mm rectangular light-sharing windows (RLSWs) and assembly the detector with nine crystals coupled to one silicon photomultiplier (SiPM) method; this caused DOI-related position shifts in the crystal decoding spots of the flood map. Homogeneous radiation was used to establish transfer functions to convert spot shifts into DOI measurements. The conventional collimated radiation experiments were used to assess the accuracy of the DOI measurements. Flood map results show that 81 segmented crystals can be clearly resolved, including 16 crystals adjacent to two RLSW windows (M-type), 40 crystals adjacent to one RLSW window (E-type), and 25 crystals not adjacent to any RLSW window (C-type). The mean absolute error of all DOI-capable crystals, M-type crystals, and E-type crystals are 2.15 ± 0.61, 1.95 ± 0.50, and 2.23 ± 0.63 mm, respectively. The novel nine-crystals-to-one-SiPM coupling technology is a low cost approach for constructing high-performance DOI detector modules. Detectors using nine-crystals-to-one-SiPM coupling technology are good candidates for high-resolution preclinical PET and for total-body PET.

Utilization of windowing effect and accumulated autocorrelation function and power spectrum for pitch detection in noisy environments

AbstractIn this paper, considering a progressing trend of recent techniques for pitch detection of speech in noisy environments, windowing effects are discussed analytically, and it is insisted that the Rectangular window should be proactively used instead of the popular Hanning or Hamming window. In a variety of noise environments, a performance comparison of the conventional pitch detection methods is conducted, and as a result, we take a standpoint to support the autocorrelation (ACF) method. Incorporating accumulation techniques, three types of pitch detection approaches are developed. Through experiments, it is shown that the three accumulation based approaches have the potential to provide better performance than recent state‐of‐the art methods for pitch detection without relying on a complicated post processing technique. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Study on thermodynamic functions of traditional building windows based on characters

The indoor light environment of the building has an extremely important influence on its own use function, and there are many factors that affect the indoor light environment of the building, such as the surrounding environment of the building, the interior decoration of the building, and the design of the window. The window is used as the building envelope. An important part of the structure is responsible for lighting and ventilation meet the requirements of the indoor environment. It exists as a lighting device for the building. The lighting performance of the windows not only meets people?s requirements for living comfort, but also consumes energy in the building. It will have a very important impact. A variety of window shapes start from different functional needs. The comprehensive use of these window shapes by traditional buildings together creates its unique thermodynamic function. This article analyzes cold regions based on the analysis method of thermodynamic functions. Solar heat gain from traditional building windows.

Window Functions with a Quasi-Rectangular Spectrum

The discrete Fourier transform (DFT) is carried out on a bounded time interval, which is equivalent to multiplying a signal under analysis by a rectangular window whose spectrum has the largest (among the other windows) side lobes. As a result, the effect called spectral leakage occurs. Multiplying the signal by the smoothing window reduces the splatter of its spectral components. There are several dozen variants of window functions as the DFT is used in a variety of problems. Of particular interest is the unique flat-top window, which is employed in broadband applications. In this study, we propose a new adjustable window with a quasi-rectangular spectrum and a method to reduce the level of the spectrum’s side lobes.

On the Design of Broadband Rectangular Waveguide Pressure Windows

In this article, the design of full-band rectangular waveguide pressure windows for high power applications is presented. The proposed design features a compact size, low loss, and a simplified fabrication process. A short impedance step is deployed to achieve a deep matching level over the full band of the standard waveguide. An approximate circuit model is proposed to select the initial dimensions for the proposed design to reduce the design time frame. Despite the wide use of pressure windows in many applications, the need for an accurate model still exists. The proposed model has been validated over different rectangular waveguide standards through numerical simulations with a maximum mean square error of 3%. Based on the proposed model, standard WR90 and WR28 waveguide Teflon-based windows are fabricated and measured. The measured results show a VSWR below 1.15 with an average low insertion loss of 0.08 dB. In addition, the pressure effect on the electrical performance of the pressure window is assessed. A pressure test is carried out, showing that the proposed pressure window designs are suitable for pressures up to 45 and 75 Ib/in 2 without any significant deterioration for WR90 and WR28 waveguide windows, respectively. The proposed pressure windows show superior electrical and mechanical specifications compared with both the state-of-the-art in the literature and the industrial products.

Multifrequency Vector Measurement System for Reliable Vehicle Magnetic Profile Assessment.

This paper describes the design and the performance of simultaneous, multifrequency impedance measurement system for four inductive-loop (IL) sensors which have been developed for vehicle parameters measurement based on vehicle magnetic profile (VMP) analysis. Simultaneous impedance measurement on several excitation frequencies increases the VMP measurement reliability because typical electromagnetic interferences (EMI) are narrowband, and should not simultaneously affect, in the same way, all measurement bands that are spread in the frequency, i.e., it is expected that at least one measurement band is disturbance-free. The system consists of two standard and two slim IL sensors, specially designed and installed, the analogue front-end, and an industrial computer with digital-to-analogue and analogue-to-digital converters accessed via field-programmable gate array (FPGA). The impedance of the IL sensors is obtained by vector measurement of voltages from auto-balancing bridge (ABB) front-end. Complex voltages are demodulated from excitation frequencies with FIR filters designed with the flat-top windows. The system is capable of delivering VMPs in real-time mode, and also storing voltages for off-line postprocessing and analysis. Field distributions and sensitivities of slim and standard IL sensors are also discussed. Field test confirmed assumed increased reliability of VMP measurement for proposed simultaneous multifrequency operational mode.

Long-Range Displacement Meters Based on Chipped Circular Patch Antenna.

This paper presents a passive wireless long-range displacement sensor that is based on the circular patch antenna, and the detecting range of the sensor can be customized. The sensor consists of a chipped circular antenna with two opened rectangular windows, a substrate, and a ground plate with a sloping channel. No bonding between the antenna and the ground plate allows for the chipped antenna to slide along the sloping channel. The channel will drive the current flow on the plate once the chip is activated, increasing the effective electrical length and, consequently, decreasing the resonant frequency of the circular antenna. The sensing mechanism equates the measuring displacement to the relative movement of the antenna with respect to the ground that achieves the measurement of long-range displacement and, thus, the proposed sensor can avoid stress damage to the antenna due to excessive deformation. Three different range sensors were simulated in the the Ansoft high frequency structure simulator (HFSS). The results show that the resonance frequency of the antenna has a linear relationship with the varying chute depth beneath the chip. Three sensors were fabricated, and the experimental results also validated that the sensitivity of the sensor can be adjusted.

Commissioning and quality assurance of a novel solution for respiratory-gated PBS proton therapy based on optical tracking of surface markers

We present the commissioning and quality assurance of our clinical protocol for respiratory gating in pencil beam scanning proton therapy for cancer patients with moving targets. In a novel approach, optical tracking has been integrated in the therapy workflow and used to monitor respiratory motion from multiple surrogates, applied on the patients’ chest. The gating system was tested under a variety of experimental conditions, specific to proton therapy, to evaluate reaction time and reproducibility of dose delivery control. The system proved to be precise in the application of beam gating and allowed the mitigation of dose distortions even for large (1.4cm) motion amplitudes, provided that adequate treatment windows were selected. The total delivered dose was not affected by the use of gating, with measured integral error within 0.15cGy. Analysing high-resolution images of proton transmission, we observed negligible discrepancies in the geometric location of the dose as a function of the treatment window, with gamma pass rate greater than 95% (2%/2mm) compared to stationary conditions. Similarly, pass rate for the latter metric at the 3%/3mm level was observed above 97% for clinical treatment fields, limiting residual movement to 3mm at end-exhale. These results were confirmed in realistic clinical conditions using an anthropomorphic breathing phantom, reporting a similarly high 3%/3mm pass rate, above 98% and 94%, for regular and irregular breathing, respectively. Finally, early results from periodic QA tests of the optical tracker have shown a reliable system, with small variance observed in static and dynamic measurements.

Neighborhood Singular Value Decomposition Filter and Application in Adaptive Beamforming for Coherent Plane-Wave Compounding

Coherent plane-wave compounding (CPWC) is widely used in medical ultrasound imaging, in which plane-waves tilted at multiple angles are used to reconstruct ultrasound images. CPWC helps to achieve a balance between frame rate and image quality. However, the image quality of CPWC is limited due to sidelobes and noise interferences. Filtering techniques and adaptive beamforming methods are commonly used to suppress noise and sidelobes. Here, we propose a neighborhood singular value decomposition (NSVD) filter to obtain high-quality images in CPWC. The NSVD filter is applied to adaptive beamforming by combining with adaptive weighting factors. The NSVD filter is advantageous because of its singular value decomposition (SVD) and smoothing filters, performing the SVD processing in neighboring regions while using a sliding rectangular window to filter the entire imaging region. We also tested the application of NSVD in adaptive beamforming. The NSVD filter was combined with short-lag spatial coherence (SLSC), coherence factor (CF), and generalized coherence factor (GCF) to enhance performances of adaptive beamforming methods. The proposed methods were evaluated using simulated and experimental datasets. We found that NSVD can suppress noise and achieve improved contrast (contrast ratio (CR), contrast-to-noise ratio (CNR) and generalized CNR (gCNR)) compared to CPWC. When the NSVD filter is used, adaptive weighting methods provide higher CR, CNR, gCNR and speckle signal-to-noise ratio (sSNR), indicating that NSVD is able to improve the imaging performance of adaptive beamforming in noise suppression and speckle pattern preservation.

An accuracy improving method for composite grating phase measuring profilometry

An accuracy improving method for composite grating phase measuring profilometry (CGPMP) based on mixed filtering window is proposed. When CGPMP is used to carry out three-dimensional (3D) measurement, the phase-shifting deformed patterns can be demodulated effectively from the captured composite deformed pattern by proper filters. So the selection of the filtering window is very important. By analyzing the characteristics of noises and their different effects on the spectrum components along different orientations, searching for the best filtering window of the spatial spectrum along the two mutually orthogonal directions, a mixed filtering window to improve measuring accuracy is established. Digital simulating results show that the designedly mixed filtering window has better noise suppression than rectangular, triangular, Blackman and Hanning filtering windows. The experimental results show that the measuring error using the mixed filtering window equalizing noise and spectrum leakage is the smallest, and the root mean square error (RMSE) is reduced by 9.64%, and the measuring accuracy is improved effectively.

An LSTM-Based Model for Person Identification Using ECG Signal

Electrocardiogram (ECG)-based biometrics are gaining popularity because of its robustness against falsification. In this letter, we have designed a new long short-term memory (LSTM) based framework for person identification using ECG signal. Our model learns the underlying temporal representation of an ECG signal by considering both intra-beat and inter-beat variations. We have shown that the LSTM model captures the intra-beat variations better for smaller ECG segments. Unlike most of the models in the literature, our model doesn't require the detection of any fiducial points. This is achieved by training the LSTM network with smaller segments of ECG signals, which are extracted by sliding a rectangular window. The effect of different window length on person identification accuracy is studied. The efficiency of the model is extensively tested on four databases; PTB, MIT-BIH arrhythmia database, ECG-ID, and CYBHi. An accuracy of 97.3% is obtained for 290 subjects of the PTB database. Similar results are also obtained for other databases, as well as 79.37% accuracy for CYBHi.

Different exposure windows to low doses of genistein and/or vinclozolin result in contrasted disorders of testis function and gene expression of exposed rats and their unexposed progeny

Living species including humans are continuously exposed to low levels of a myriad of endocrine active compounds that may affect their reproductive function. In contrast, experimental designs scrutinizing this question mostly consider the gestational/lactational period, select high unrealistic doses and, have rarely investigated the possible reproductive consequences in the progeny. The present study aimed at assessing comparatively a set of male reproductive endpoints according to exposure windows, gestational/lactational versus pre-pubertal to adulthood, using low doses of endocrine active substances in male rats as well as their unexposed male progeny. Animals were orally exposed to 1 mg/kg bw/d of genistein and/or vinclozolin, from conception to weaning or from prepuberty to young adulthood. A number of reproductive endpoints were assessed as well as testicular mRNA expression profiles, in the exposed rats and their unexposed progeny. Overall, the low dosage used only affected weakly most of classical reproductive endpoints. However, the gestational/lactational exposure to vinclozolin alone or combined to genistein significantly delayed the puberty onset. Contrasting with the gestational/lactational exposure, a decreased sperm production was found in the animals exposed to genistein and vinclozolin from the pre-pubertal period but also in their progeny for vinclozolin and the mixture. The expression level of several genes involved in meiosis, apoptosis and steroidogenesis was also affected differentially as a function of the exposure window in both exposed rats and unexposed offspring. We also provide further evidence that doses of endocrine active substances relevant with human exposure may affect the male reproductive phenotype and testicular transcriptome in the exposed generation as well as in the indirectly exposed offspring.

Effect of window configurations on its convective heat transfer rate

ASHRAE Standard 90.1 provides a useful guideline for the Window-to-Wall Ratio (WWR), stating that “the total vertical fenestration area shall be less than 40% of the gross wall area” However, different window configurations with the same WWR can perform thermally differently. In this paper, the effect of window configurations on the convective heat transfer rate of a window and downdraft velocity is investigated numerically at different Rayleigh numbers ranging from 1.7 × 106 to 1.7 × 1011. Parameters investigated in this study include window shape, heater location, and heater temperature. A convective heat transfer rate of each of the window models is evaluated using high-resolution 3-D steady Reynolds Averaged Navier-Stokes (RANS) based computational fluid dynamics (CFD) simulations. The heater and the window are modeled as isothermal plane boundaries, where the window possesses a cold temperature, and the natural convective heater is hotter than room temperature. The sensitivity of the window Nusselt number and downdraft velocity of the windows have been examined. The thermal performance ranking, from higher to lower, is horizontal rectangular, square, circular, and vertical rectangular window configuration, respectively. This implies that proper window geometry configuration selection can be used as one of the passive strategies for saving energy in buildings.

Modified pulse-phase thermography algorithms for improved contrast-to-noise ratio from pulse-excited thermographic sequences

Two modified algorithms for pulsed phase thermography were defined. The principle is to mask out parts of the thermal signal that only add noise but contain no significant information. A first algorithm uses a frequency dependent Gaussian window function. A second algorithm leads to a rectangular window function. The algorithms were tested on synthetic signals modeling a circular hidden defect in a plate and experimentally by flash excited thermography on a steel and a polymer sample. For both materials, a significant improvement of the contrast-to-noise ratio from the defects was obtained for higher analysis frequencies.