Pair Of Filters Research Articles

Investigation of erosion mechanism of tungsten-based cathode in Ar–N2 DC arc

Direct current arc has been used in a wide industrial field. Reducing in cathode erosion is an important issue for process cost reduction, however the erosion mechanism under molecular gas as plasma supporting gas has not been clarified yet. The purpose of this research is to elucidate the erosion mechanism of tungsten based cathodes in atmospheric pressure Ar–N2 DC arc. The metal vapor generated from the cathode surface was successfully visualized by a high speed camera system with a pair of band pass filters. Combing the visualization with the cahtode temperature measurements provides the tungsten vapor evaporation mechanism; tungsten vapor was generated not from the high temperature part of the cathode tip but from the peripheral part. The arc temperature measurement confirmed that ionization of tungsten atoms in the high-temperature region of the arc caused to this characteristic distribution of tungsten vapor. These findings advance the understanding of such electrode phenomena leading to increased use time of the electrode, and as a result the industrial use of N2 arcs is expected to expand.

Abstract 1187: Toward high-throughput, high-multiplex FFPE tumor tissue assays for translational research: 7-color, whole slide imaging

Abstract Background: Immuno-oncology research and predictive biomarkers discovery requires the ability to rapidly identify, quantify, and spatially map many cell sub-types of the tumor environment in FFPE tissue sections. Multiplexed immunofluorescence (IF) enables identification of multiple targets within separate spectral, or color, channels, which in turn enables more in-depth analysis of rare tissue material relative to traditional methods. Although many methods for multiplexed IF exist, they are often costly and require time-consuming assay development and long imaging times. The Ultivue® InSituPlex® technology enables rapid, optimized staining of multiple targets utilizing widely-used immunohistochemistry (IHC) staining and fluorescence imaging instrumentation. Here, we demonstrate the application of InSituPlex technology to image 6 targets and a nuclear counterstain in a 7-color single whole-slide scan, without linear unmixing-based image reconstruction. This technique expands the subtyping depth that can be achieved in a single imaging round and on a single section, and also increases sample-to-answer throughput with a streamlined, single-day workflow. Methods: InSituPlex technology was used to perform 6-plex immune profiling of different FFPE tumor sections. Slides were stained with a cocktail of primary antibodies using a Leica® Bond® RX autostainer and imaged on commercially available fluorescent slide scanners. Subsequent image analysis of the whole slide scans was carried out using Indica Labs HALO® software. Results: In this poster, we present an assay for pathology research that enables fast immuno-profiling in tumor tissues, using a streamlined staining workflow and 7-color imaging. Newly selected fluorophores were used with corresponding optical filter pairs, which increased the number of spectral channels available on commercially available slide scanners while limiting channel cross-talk. Analysis led to the identification of key immune cell phenotypes through marker colocalization without significant ambiguity between targets tagged with spectrally adjacent fluorescent labels. Conclusion: The newly-expanded fluorophore configuration of the InSituPlex technology enables high throughput identification of 6 targets and a nuclear counterstain on whole tumor sections, empowering translational and immuno-oncology research. Citation Format: Amanda J. Bares, Eloise M. Wheeler, Maël Manesse. Toward high-throughput, high-multiplex FFPE tumor tissue assays for translational research: 7-color, whole slide imaging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1187.

New results on approximate Hilbert pairs of wavelet filters with common factors

In this paper, we consider the design of wavelet filters based on the Thiran's common-factor approach proposed in [13] . This approach aims at building finite impulse response filters of a Hilbert-pair of wavelets serving as real and imaginary part of a complex wavelet. Unfortunately it is not possible to construct wavelets which are both finitely supported and analytic. The wavelet filters constructed using the common-factor approach are then approximately analytic. Thus, it is of interest to control their analyticity. The purpose of this paper is to first provide precise and explicit expressions as well as easily exploitable bounds for quantifying the analytic approximation of this complex wavelet. Then, we prove the existence of such filters enjoying the classical perfect reconstruction conditions, with arbitrarily many vanishing moments.

An online error calibration method for spaceflight TT&C systems based on LEO-ground DDGPS

To overcome the shortcomings of the traditional measurement error calibration methods for spaceflight telemetry, tracking and command (TT&C) systems, an online error calibration method based on low Earth orbit satellite-to-ground doubledifferential GPS (LEO-ground DDGPS) is proposed in this study. A fixed-interval smoother combined with a pair of forward and backward adaptive robust Kalman filters (ARKFs) is adopted to solve the LEO-ground baseline, and the ant colony optimization (ACO) algorithm is used to deal with the ambiguity resolution problem. The precise baseline solution of DDGPS is then used as a comparative reference to calibrate the systematic errors in the TT&C measurements, in which the parameters of the range error model are solved by a batch least squares algorithm. To validate the performance of the new online error calibration method, a hardware-in-the-loop simulation platform is constructed with independently developed spaceborne dual-frequency GPS receivers and a Spirent GPS signal generator. The simulation results show that with the fixed-interval smoother, a baseline estimation accuracy (RMS, single axis) of better than 10 cm is achieved. Using this DDGPS solution as the reference, the systematic error of the TT&C ranging system is effectively calibrated, and the residual systematic error is less than 5 cm.

Design of Pipelined IIR Filters Using Two-Stage Frequency-Response Masking Technique

A pipelined, high-speed infinite impulse response (IIR) filter based on the frequency-response masking (FRM) technique has been proposed by Johansson and Wanhammar. In their method, the bandedge shaping filters are a pair of IIR power complementary filters whose ${z}$ -transform functions are functions of ${z} ^{M}$ and the masking filters are linear phase finite impulse response (FIR) filters. The IIR bandedge shaping filters have $M$ delays in the feedback loop and can be pipelined by ${M}$ stages. In this brief, we present a two-stage FRM method for reducing the number of multipliers of the pipelined IIR filter proposed by Johansson and Wanhammar for a given magnitude response specification and a given number of pipeline stages in the feedback loop. In our design, all the subfilters are optimized jointly. We show that our two-stage masking design requires fewer multipliers if the number of pipeline stages in the feedback loop is larger than four.

Heart rate estimation from photoplethysmography signal for wearable health monitoring devices

Wearable wrist type health monitoring devices use photoplethysmography (PPG) signal to estimate heart rate (HR). The HR estimation from these devices becomes difficult due to the existence of strong motion artifacts (MA) in PPG signal thereby leading to inaccurate HR estimation. The objective is to develop a novel de-noising algorithm that reduces the MA present in PPG signal, resulting in an accurate HR estimation. A novel de-noising technique using the hierarchical structure of cascade and parallel combinations of two different pairs of adaptive filters which reduces MA from the PPG signal and improves HR estimation is proposed. The first pair combines normalized least mean squares (NLMS) and recursive least squares (RLS) adaptive filters and the second pair combines recursive least squares (RLS) and least mean squares (LMS) adaptive filters. The de-noised signals obtained from the first and second pairs are combined to form a single de-noised PPG signal by means of convex combination. The HR of the de-noised PPG signal is estimated in the frequency domain using a Fast Fourier transform (FFT). Performance of the proposed technique is evaluated using a dataset of 12 individuals performing running activity in Treadmill. It resulted in an average absolute error of 0.92 beats per minute (BPM), standard deviation of the absolute error of 1.17 beats per minute (BPM), average relative error of 0.72 and Pearson correlation coefficient of 0.9973.

Convolutional Sparse Coding Using Wavelets for Single Image Super-Resolution

In this paper, we propose the convolutional sparse coding based model in the wavelet domain for the task of single image super-resolution (SISR). The conventional sparse coding based approaches work on overlapping image patches and use the dictionary atoms to sparse code an image patch. Further, at the final stage, an overlap-add mechanism is used to get the final high-resolution image estimate. However, these algorithms fail to take into account the consistency present in the overlapping patches which limits their performance. We propose the use of wavelet integrated convolutional sparse coding approach where instead of dictionary atoms we utilize the convolution summations between the learned filters and their mappings for sparse representation based SISR. The use of wavelets is proposed owing to their unique directional and compact features. A pair of filters are learned along with a mapping function for each wavelet sub-band to exploit the consistency among patches. The proposed wavelet integrated convolutional sparse coding model helps capture useful contextual information. The proposed model is evaluated on publicly available datasets for different scale-up parameters. To show the efficacy of the proposed model we compare it with recent state-of-the-art algorithms. The visual results along with the quantitative ones indicate that the proposed model performs well for the tasks of super-resolution.

A Local Agreement Filtering Algorithm for Transmission EM Reconstructions

We present LAFTER, an algorithm for de-noising single particle reconstructions from cryo-EM.Single particle analysis entails the reconstruction of high-resolution volumes from tens of thousands of particle images with low individual signal-to-noise. Imperfections in this process result in substantial variations in the local signal-to-noise ratio within the resulting reconstruction, complicating the interpretation of molecular structure. An effective local de-noising filter could therefore improve interpretability and maximise the amount of useful information obtained from cryo-EM maps.LAFTER is a local de-noising algorithm based on a pair of serial real-space filters. It compares independent half-set reconstructions to identify and retain shared features that have power greater than the noise. It is capable of recovering features across a wide range of signal-to-noise ratios, and we demonstrate recovery of the strongest features at Fourier shell correlation (FSC) values as low as 0.144 over a 2563-voxel cube. A fast and computationally efficient implementation of LAFTER is freely available.We also propose a new way to evaluate the effectiveness of real-space filters for noise suppression, based on the correspondence between two FSC curves: 1) the FSC between the filtered and unfiltered volumes, and 2) Cref, the FSC between the unfiltered volume and a hypothetical noiseless volume, which can readily be estimated from the FSC between two half-set reconstructions.

Species Richness, rRNA Gene Abundance, and Seasonal Dynamics of Airborne Plant-Pathogenic Oomycetes.

Oomycetes, also named Peronosporomycetes, are one of the most important and widespread groups of plant pathogens, leading to significant losses in the global agricultural productivity. They have been studied extensively in ground water, soil, and host plants, but their atmospheric transport vector is not well characterized. In this study, the occurrence of airborne Oomycetes was investigated by Sanger sequencing and quantitative PCR of coarse and fine aerosol particle samples (57 filter pairs) collected over a 1-year period (2006–2007) and full seasonal cycle in Mainz, Germany. In coarse particulate matter, we found 55 different hypothetical species (OTUs), of which 54 were plant pathogens and 29 belonged to the genus Peronospora (downy mildews). In fine particulate matter (<3 μm), only one species of Hyaloperonospora was found in one sample. Principal coordinate analysis of the species composition revealed three community clusters with a dependence on ambient temperature. The abundance of Oomycetes rRNA genes was low in winter and enhanced during spring, summer, and fall, with a dominance of Phytophthora, reaching a maximum concentration of ∼1.6 × 106 rRNA genes per cubic meter of sampled air in summer. The presence and high concentration of rRNA genes in air suggests that atmospheric transport, which can lead to secondary infection, may be more important than currently estimated. This illustrates the need for more current and detailed datasets, as potential seasonal shifts due to changing meteorological conditions may influence the composition of airborne Oomycetes. An insight into the dynamics of airborne plant pathogens and their major drivers should be useful for improved forecasting and management of related plant diseases.

Broadband c-Si metasurfaces with polarization control at visible wavelengths: applications to 3D stereoscopic holography.

Visual arts and entertainment related industries are continuously looking at promising innovative technologies to improve users' experience with state-of-the-art visualization platforms. This requires further developments on pixel resolution and device miniaturization which can be achieved, for instance, with high contrast materials, such as crystalline silicon (c-Si). Here, a new broadband stereoscopic hologram metasurface is introduced, where independent phase control is achieved for two orthogonal polarizations in the visible spectrum. The holograms are fabricated with a birefringent metasurface consisting of elliptical c-Si nanoposts on Sapphire substrate. Two holograms are combined on the same metasurface (one for each polarization) where each is encoded with four phase levels. The theoretical bandwidth is 110 nm with a signal to noise ratio (SNR) >15 dB. The stereoscopic view is obtained with a pair of cross-polarized filters in front of the observers' eyes. The measured transmission and diffraction efficiencies are about 70% and 15%, respectively, at 532 nm (the design wavelength). The metasurfaces are also investigated at 444.9 nm and 635 nm to experimentally assess their bandwidth performance. The stereoscopic effect is surprisingly good at 444.9 nm (and less so at 635 nm) with transmission and diffraction efficiencies around 70% and 18%, respectively.

Research on Iris Recognition Algorithm Based on Hough Transform

This paper proposes an iris recognition algorithm based on Hough transform. Firstly, the iris image is preprocessed, and the iris boundary is detected by Hough transform combined with Canny edge detection algorithm. Then, the annular iris region is normalized into a rectangular region by using the Rubber sheet algorithm; then the 1D Log-Gabor filter pair is used. The texture features of the normalized iris image are extracted, and the recognition algorithm based on the Hamming distance classifier is used for the final pattern matching according to actual needs. In this paper, the CASIA Iris Image Database V1.0 iris image database is used as the experimental object, and the simulation is performed on the MATLAB platform to verify the effectiveness of the iris recognition algorithm. Experiments show that the iris recognition method is feasible and effective.

Joint window and filter optimization for new waveforms in multicarrier systems

One of the demands of the next-generation wireless communication systems is being supportive to asynchronous traffic types. In order to meet this demand, many waveform candidates for next-generation wireless communication systems have low out-of-subband emissions (OOSBE) of the transmitted signal, and the popular ones deploy either filtering or windowing at the transmitter. In this paper, a joint windowing and filtering multi-carrier waveform based on a generalized orthogonal frequency division multiplexing (OFDM) system is proposed. A joint window and filter optimization problem to minimize OOSBE is also formulated. The optimization problem is first divided into two solvable subproblems using interior-point methods, and then an iterative algorithm is proposed to obtain the optimal window and filter pair. Simulation results suggest that the proposed joint windowing and filtering waveform has an advantage in suppressing OOSBE or enhancing spectral efficiency, and is more robust to frequency asynchronism compared to waveforms deploying only either filtering or windowing.

Direct detection of polarization multiplexed single sideband signals with orthogonal offset carriers.

We propose a novel direct detection (DD) scheme for polarization division multiplexed (PDM) single sideband (SSB) signals with two orthogonal carriers located at the opposite sides. Polarization diversity is realized with a pair of optical filters that are used to suppress the unwanted orthogonal carrier component. A PDM-SSB DD receiver is thus constructed without polarization de-rotation. The intra-polarization signal-signal beat interference (SSBI) can be mitigated by Kramers-Kronig detection or iterative SSBI cancellation. For inter-polarization SSBI mitigation, we propose a joint iterative SSBI cancellation method. The proposed PDM-SSB DD scheme is validated with a principle experiment of 40Gbaud PDM-SSB 16-ary quadrature amplitude modulation (16-QAM) signals. After 80km standard single-mode fiber (SSMF) transmission, the bit-error rates (BERs) achieve 20% hard-decision forward error correction (HD-FEC) threshold of 1.5 × 10-2. The performance of iterative SSBI cancellation, Kramers-Kronig detection, and joint iterative SSBI cancellation are evaluated for PDM-SSB signals with different carrier-to-signal ratios (CSPRs) through numerical simulations. Moreover, a multi-input-multi-output (MIMO) equalization scheme is proposed and validated with numerical simulation, which can suppress the linear inter-polarization crosstalk and relax the sharpness requirement of optical filter edges.

Fast schemes for online record linkage

The process of integrating large volumes of data coming from disparate data sources, in order to detect records that refer to the same entities, has always been an important problem in both academia and industry. This problem becomes significantly more challenging when the integration involves a huge amount of records and needs to be conducted in a real-time fashion to address the requirements of critical applications. In this paper, we propose two novel schemes for online record linkage, which achieve very fast response times and high levels of recall and precision. Our proposed schemes embed the records into a Bloom filter space and employ the Hamming Locality-Sensitive Hashing technique for blocking. Each Bloom filter is hashed to a number of hash tables in order to amplify the probability of formulating similar Bloom filter pairs. The main theoretical premise behind our first scheme relies on the number of times a Bloom filter pair is formulated in the hash tables of the blocking mechanism. We prove that this number strongly depends on the distance of that Bloom filter pair. This correlation allows us to estimate in real-time the Hamming distances of Bloom filter pairs without performing the comparisons. The second scheme is progressive and achieves high recall, upfront during the linkage process, by continuously adjusting the sequence in which the hash tables are scanned, and also guarantees, with high probability, the identification of each similar Bloom filter pair. Our experimental evaluation, using four real-world data sets, shows that the proposed schemes outperform four state-of-the-art methods by achieving higher recall and precision, while being very efficient.

Interpolating seismic data via the POCS method based on shearlet transform

A method based on shearlet transform and the projection onto convex sets with L0-norm constraint is proposed to interpolate irregularly sampled 2D and 3D seismic data. The 2D directional filter of shearlet transform is constructed by modulating a low-pass diamond filter pair to minimize the effect of additional edges introduced by the missing traces. In order to abate the spatial aliasing and control the maximal gap between missing traces for a 3D data cube, a 2D separable jittered sampling strategy is discussed. Finally, numerical experiments on 2D and 3D synthetic and real data with different under-sampling rates prove the validity of the proposed method.

Multidimensional directional steerable filters — Theory and application to 3D flow estimation

In this paper, a thorough theoretical analysis on the construction of multi-dimensional directional steerable filters is given. Steerable filters have been constructed for up to three dimensions. We extend the relevant theory to multiple dimensions and construct multi-dimensional steerable filters, as well as quadrature pairs of such filters. Formulating the multi-dimensional motion estimation problem in the spatiotemporal frequency domain, it is shown that motion manifests itself as energy concentration along “motion hyper-planes” in that domain. Subsequently, using the constructed multi-dimensional filters, we formulate the “hyper-donut” mechanism, i.e. a mechanism to efficiently “measure” the “motion energy” on a “motion hyper-plane”. On top of that, rigorous mathematical analysis on the use of the constructed filters in the dense flow estimation task is given. Based on the theoretical developments, a steerable filter-based algorithm is formulated, in its simplest possible form, for estimating 3D flow in sequences of volumetric or point-cloud data. Experimental results on simulated and real-world data verify the validity of our arguments and the effectiveness of the proposed method.

Thermometry of combustion gas measuring two-band near-infrared emissions less than 1.1 μm from water molecules

Thermometry using two-band near-infrared (NIR) emissions less than 1.1 μm has been implemented for combustion gases formed on a flat flame burner. The gas temperature was calibrated using a SiC thin filament pyrometry (TFP) above 1500 K for H2/air and CH4/air mixtures. The emission spectra were measured with a spectrometer and a monochrome CMOS sensor with an image doubler and two bandpass filters. Two pairs of bandpass filters (850 nm/925 nm and 975 nm/925 nm) were tested to measure temperature. Results indicated that strong H2O emissions existed in the NIR region, and they became stronger with an increase in the temperature. The CO2 emission spectra in the NIR region were negligible compared to that of H2O. Calibration temperature lines were obtained as a function of the intensity ratio of the two-band emissions in the NIR region. Using a CMOS camera, the uncertainties of temperature were 59 K for 850 nm/925 nm and 145 K for 975 nm/925 nm. The resolutions were 0.7 K for 850 nm/925 nm and 1 K for 975 nm/925 nm. Using the calibration line, two-dimensional temperature measurements were performed for H2/air flames, CH4/air flames and Bunsen flames of 13A city gas. For the high temperature region above 1500 K, a quantitative two-dimensional temperature field was measured for lean and rich combustion. In addition, temperature measurement at high pressure was conducted for combustion gas of propane/air mixture with the equivalence ratio of 0.7 using a rapid compression machine. Temperature could be estimated using the calibration line obtained for the flat flame burner. We have demonstrated the performance and the possibility of thermometry two-band H2O emissions in the NIR region.

A Design of Two Sub-Stage Square-Root Nyquist Matched Filter

A pair of matched filters whose cascade response satisfies the Nyquist criterion can guarantee the inter-symbol interference (ISI)-free transmission for band-limited communication systems. For a linear phase finite impulse response square root Nyquist filter, it is necessary to strike a balance between the stop-band attenuation (SBA) and ISI performance. This paper proposes a novel approach for obtaining the square root Nyquist filter by adopting two sub-stage cascade filters group, which is known as the compensated half-band (HB) filter group (CHFG). The first sub-stage of the CHFG is a HB filter which can guarantee the required SBA performance on low computational complexity; whereas, the second sub-stage is an ISI compensation filter to ensure that the cascaded response of two CHFGs satisfies the Nyquist criterion. Theoretical analysis and experimental results show that the proposed CHFG can either achieve better SBA/ISI performance or reduce the computational complexity.

Быстродействующий алгоритм восстановления несущей частоты и кадровой синхронизации в модемах с QPSK-модуляцией

When demodulating signals in communication systems with QPSK modulation operating in the pulsed mode, the following problems arise: rapid elimination of the reference oscillator phase ambiguity and ensuring reliable frame synchronization for a given noise immunity. In most QPSK modems, the carrier frequency recovery and synchronization recovery tasks are separated and solved with the help of different functional modules, which is not the optimal solution from the point of view of increasing the energy efficiency. In this paper, we propos a fast algorithm for frame synchronization and recovery of the carrier frequency of a QPSK modem using Barker sequences as synchronization signals in conjunction with the coordinated processing. The simulation of the combined circuit is performed, which allows to eliminate the phase ambiguity of the reference oscillation with the simultaneous formation of the frame synchronization signal for various combinations of binary sync codes of the length N = 7. To obtain a reference oscillation, a stable quartz oscillator is used. An external adjustable phase shifter block abruptly changes the phase of the oscillator, and the phase ambiguity, which is multiple of 90°, is eliminated by parallel analysis of all possible rotations of the signal constellation plane in the units, each of which contains a pair of filters matched to the signal distributed over in two quadratures. The timing for the proposed scheme does not depend on the initial phase difference between the received and the initial signal constellations, while the circuit realization of a non-tunable oscillator is much simpler than that for a voltage controlled oscillator.

The Power of SOFIA/FORCAST in Estimating Internal Luminosities of Low-mass Class 0/I Protostars

Abstract With the Stratospheric Observatory for Infrared Astronomy (SOFIA) routinely operating science flights, we demonstrate that observations with the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST) can provide reliable estimates of the internal luminosities, L int, of protostars. We have developed a technique to estimate L int using a pair of FORCAST filters: one “short-wavelength” filter centered within 19.7–25.3 μm, and one “long-wavelength” filter within 31.5–37.1 μm. These L int estimates are reliable to within 30%–40% for 67% of protostars and to within a factor of 2.3–2.6 for 99% of protostars. The filter pair comprised of F 25.3 μm and F 37.1 μm achieves the best sensitivity and most constrained results. We evaluate several assumptions that could lead to systematic uncertainties. The OH5 dust opacity matches observational constraints for protostellar environments best, although not perfectly; we find that any improved dust model will have a small impact of 5%–10% on the L int estimates. For protostellar envelopes, the TSC84 model yields masses that are twice those of the Ulrich model, but we conclude that this mass difference does not significantly impact results at the mid-infrared wavelengths probed by FORCAST. Thus, FORCAST is a powerful instrument for luminosity studies targeting newly discovered protostars or suspected protostars lacking detections longward of 24 μm. Furthermore, with its dynamic range and greater angular resolution, FORCAST may be used to characterize protostars that were either saturated or merged with other sources in previous surveys using the Spitzer Space Telescope or the Herschel Space Observatory.