Filter Slope Research Articles

Pesticides trapping performance of vegetative filter strips in black soil region, Northeast China: controlled experiments and VFSMOD-W modeling

The Northeast black soil region in China is an important grain-producing area where various pesticides are extensively used to increase grain yields. However, this practice poses serious risks to the ecological health of soil and water systems, necessitating effective measures. Vegetative filter strips (VFS) are commonly used to mitigate agricultural diffuse pollutants, but their efficiency varies across different regions, requiring assessment. This study employed flume experiments, the VFSMOD-W model, and redundancy analysis (RDA) to evaluate the efficacy of VFS in runoff, sediment, and pesticide removal, as well as influencing factors. The results showed that VFS reduced outflow rate of runoff by 8 %–64 % and sediment by approximately 90 %, achieving load removal rates of 61 % and 95 % respectively. Pesticide load removal efficiency ranged from 37 % to 94 %, with higher efficiency for adsorbed pesticides like chlorpyrifos compared to water-soluble ones like atrazine. Interflow and vertical seepage were significant pathways for pesticide transport in VFS, with chlorpyrifos concentrations at 4 %–26 % and atrazine at 20 %–37 % of inflow concentrations. The VFSMOD-W model accurately predicted VFS efficiency (NSE > 0.90), and RDA results indicated that environmental factors could explain 86.7 % of the variation in VFS performance, with soil vertical saturated hydraulic conductivity (VKS) being the most influential factor, followed by rainfall intensity (T), saturated soil water content (OS), initial soil water content (OI), and filter slope for each segment (SOA). Optimizing soil moisture characteristic factors and increasing infiltration are crucial for VFS performance. Applying VFSMOD-W for precise VFS design can help reduce construction costs. In the future, long-term field monitoring and evaluation of VFS efficiency after implementation should be conducted in the black soil region of Northeast China to provide data supporting the improvement of VFSMOD-W simulation accuracy. This will also offer recommendations for the government in formulating VFS configuration schemes.

Optimal parameter selection for the THz-CCS system based on an incoherent light source.

Terahertz cross correlation spectroscopy (THz-CCS) systems using broadband incoherent light as the pumping source have received increasing attention from researchers in recent years. However, a comprehensive and in-depth understanding of THz-CCS is still needed to obtain a detailed optimization scheme. Here we systematically investigate the influences of the detection parameters, light propagation process, and pump source on the CCS signals. The impacts of the filter slopes and time constants in lock-in detection are revealed for optimizing the signal-to-noise ratio and bandwidth of the THz signal. By varying the optical fiber length and dispersion coefficient, the dispersion insensitivity of THz-CCS was experimentally demonstrated. The comparison of different pump sources (SLD and ASE) shows that the over-wide and non-flat pump spectrum may attenuate the CCS signal because of the energy waste brought by the photomixing process under the limited bandwidth of the photomixer. Our research may lead to a deeper understanding and further optimization of the THz-CCS system, which will promote the development and widespread application of what is to the best of our knowledge a new technique.

Effects of spectral resolution and smearing on gated word recognition

In a word gating task, listeners are presented with increasing amounts of word-onset information (a series of increasingly longer temporal “gates”), and following each gate, they are asked to indicate what they think the target word is. Listeners with normal hearing (NH) typically recognize a target word well before they “hear” the entire word. Listeners with cochlear implants (CIs), however, need to hear almost the entire target word (require a greater amount of word-onset information) to recognize it. Here, we hypothesized that the poor spectral resolution, due to the limited number of channels and interactions between adjacent channels, may have a negative impact on gated word recognition performance. We manipulated spectral resolution by using: (1) a noise-band vocoder with a variable number of spectral channels; and (2) a vocoder with variable carrier filter slopes to simulate channel interaction. We determined the minimum amount of word-onset information required to recognize spoken words. Initial results suggest that the gated word recognition performance remained roughly unchanged as the amount of spectral degradation applied increased up to some extent, beyond which it deteriorated. With eight channels, which resemble the spectral resolution available to most CI users, even the most focused stimulation yielded poorer results.

Up-to-Date Optimization of the 90Y-PET/CT Reconstruction Protocol for Volumetric Quantification in Trans-Arterial RadioEmbolization (TARE) Procedures in the Era of Theranostics

(1) Background: New generation of PET-CT scanners allows performing volumetric dosimetry based on 90Y-activity distribution. The aim of this study was to perform an up-to-date evaluation of the optimal 90Y-PET-CT reconstruction parameters for a Siemens Biograph mCT scanner. (2) Methods: A cylindrical uniform phantom (P1), IEC NEMA Body-phantom (P2) and IEC NEMA Torso-phantom (P3) filled with 90Y were acquired. The matrix size and number of Equivalent Iterations (E.I.) were evaluated through the Recovery Coefficient (RC) and the Coefficient of Variation (CoV). The optimal post-reconstruction Gaussian Filter (GF) was assessed through an analysis of Root Mean Square Error (RMSE) and Full Width at Half Maximum (FWHM) in DVHs. (3) Results: For P1, RC values showed constant trends varying the matrix size (slope m = 1.25 × 10−3) or E.I. (slope m = −2.16 × 10−4). For P2, CoV decreased increasing the matrix size and it grew increasing the E.I. For P3, RMSE and mean dose values showed constant trends varying the Gaussian filter (slope m = 1.51 × 10−2) while FWHM decreased increasing filter. For smaller volumes, RMSE grew increasing the filter (from 34% to 74%) and the use of larger filters resulted in a dose underestimation (from 172 to 133 Gy). (4) Conclusions: The optimal reconstruction parameters for the Siemens Biograph mCT PET/CT scanner are presented, combining old metrics with new ones involving a dosimetric approach.

Lexical Effects on the Perceived Clarity of Noise-Vocoded Speech in Younger and Older Listeners.

When listening to degraded speech, such as speech delivered by a cochlear implant (CI), listeners make use of top-down linguistic knowledge to facilitate speech recognition. Lexical knowledge supports speech recognition and enhances the perceived clarity of speech. Yet, the extent to which lexical knowledge can be used to effectively compensate for degraded input may depend on the degree of degradation and the listener’s age. The current study investigated lexical effects in the compensation for speech that was degraded via noise-vocoding in younger and older listeners. In an online experiment, younger and older normal-hearing (NH) listeners rated the clarity of noise-vocoded sentences on a scale from 1 (“very unclear”) to 7 (“completely clear”). Lexical information was provided by matching text primes and the lexical content of the target utterance. Half of the sentences were preceded by a matching text prime, while half were preceded by a non-matching prime. Each sentence also consisted of three key words of high or low lexical frequency and neighborhood density. Sentences were processed to simulate CI hearing, using an eight-channel noise vocoder with varying filter slopes. Results showed that lexical information impacted the perceived clarity of noise-vocoded speech. Noise-vocoded speech was perceived as clearer when preceded by a matching prime, and when sentences included key words with high lexical frequency and low neighborhood density. However, the strength of the lexical effects depended on the level of degradation. Matching text primes had a greater impact for speech with poorer spectral resolution, but lexical content had a smaller impact for speech with poorer spectral resolution. Finally, lexical information appeared to benefit both younger and older listeners. Findings demonstrate that lexical knowledge can be employed by younger and older listeners in cognitive compensation during the processing of noise-vocoded speech. However, lexical content may not be as reliable when the signal is highly degraded. Clinical implications are that for adult CI users, lexical knowledge might be used to compensate for the degraded speech signal, regardless of age, but some CI users may be hindered by a relatively poor signal.

Adaptive auditory brightness perception

Perception adapts to the properties of prior stimulation, as illustrated by phenomena such as visual color constancy or speech context effects. In the auditory domain, only little is known about adaptive processes when it comes to the attribute of auditory brightness. Here, we report an experiment that tests whether listeners adapt to spectral colorations imposed on naturalistic music and speech excerpts. Our results indicate consistent contrastive adaptation of auditory brightness judgments on a trial-by-trial basis. The pattern of results suggests that these effects tend to grow with an increase in the duration of the adaptor context but level off after around 8 trials of 2 s duration. A simple model of the response criterion yields a correlation of r = .97 with the measured data and corroborates the notion that brightness perception adapts on timescales that fall in the range of auditory short-term memory. Effects turn out to be similar for spectral filtering based on linear spectral filter slopes and filtering based on a measured transfer function from a commercially available hearing device. Overall, our findings demonstrate the adaptivity of auditory brightness perception under realistic acoustical conditions.

Lexical effects on the perceived clarity of noise-vocoded speech in younger and older listeners

When listening to degraded speech, such as speech delivered by a cochlear implant (CI), listeners can make use of linguistic knowledge to facilitate speech recognition. Yet, the extent to which linguistic knowledge can be effectively used to compensate for degraded input may depend of the level of degradation and the age of the listener. The current study investigated lexical effects in the compensation for degraded speech via noise-vocoder simulations of CI hearing in younger and older normal-hearing listeners. In two online experiments, listeners rated the clarity of noise-vocoded sentences, with varying filter slopes. Lexical information was provided in the form of text priming and/or the lexical content (i.e., lexical frequency and neighborhood density) of key words in the sentences. Results showed that lexical information from both text priming and the lexical content enhanced the perceived clarity of degraded speech, but the strength of the lexical effects depended on the level of degradation. Additionally, lexical information appeared to equally benefit younger and older listeners. Findings demonstrate that lexical knowledge may be used in cognitive compensation during the recognition of noise-vocoded speech in both younger and older listeners. However, these mechanisms may not be as effective when the signal is highly degraded.

Development of a storage phosphor imaging system for proton pencil beam spot profile determination.

Accurate two-dimensional (2D) profile measurements at submillimeter precision are necessary for proton beam commissioning and periodic quality assurance (QA) purposes and are currently performed at our institution with a commercial scintillation detector (Lynx PT) with limited means for independent checks. The purpose of this work was to create an independent dosimetry system consisting of an in-house optical scanner and a BaFBrI:Eu2+ storage phosphor dosimeter by: (a) determining the optimal settings for the optical scanner, (b) measuring 2D proton spot profiles with the storage phosphors, and (c) comparing them to similar measurements using a commercial scintillation detector. An in-house 2D laboratory optical scanner was constructed and spatially calibrated for accurate 2D photostimulated luminescence (PSL) dosimetry. Square 5×5cm2 BaFBrI:Eu2+ dosimeter samples were uniformly irradiated with line scans performed to determine the physical and electronic scanner settings resulting in the highest signal-to-noise ratios (SNR) at a sub-millimeter spatial resolution. The resultant spatial resolution of the scanner was then quantitatively assessed by measuring (a) line pairs on a standard X-ray lead bar phantom and (b) modulation transfer functions. Following this, 2D proton spot profiles from a Mevion S250i Hyperscan proton unit were obtained at 1, 10, 20, 30, 40, and 50 monitor unit (MU) settings at maximum energy (E0 =227.1MeV) and compared to baseline profiles from a commercial scintillation detector, where 1MU is calibrated to deliver 1Gy absolute proton dose-to-water under reference conditions, that is, 41×41 proton spots uniformly spaced by 0.25cm within a 10×10cm2 square field size at maximum energy (227.1MeV) in water at depth of 5cm at isocenter. The dosimetric system's sensitivities to (a) ±1mm positional shifts and (b) ±0.3mm beam lateral spread changes were quantitatively evaluated through a Gaussian fitting of the crossline and inline plots of the respective artificially shifted beam profiles. The physical scanner settings of (a) Δτ=27ms time interval between data samples, (b) vx =1.235cm/s scanning speed, (c) 1% laser transmission (0.02mW power) and (d) (Δx, Δy)=(0.33, 0.50mm) pixel sizes with electronic settings of (a) 300 microseconds time constant, (b) normal dynamic reserve, (c) 24dB/oct low pass filter slope, and (d) 160Hz chopping frequency resulted in the highest SNR while maintaining sub-millimeter spatial resolution. The BaFBr0.85 I0.15 :Eu2+ storage phosphor dosimeters were linear from 1 to 50MU and their profiles did not saturate up to 150MU. The scanner was able to detect lateral displacements of ±1mm in both the crossline and inline directions and ±0.3mm beam spread changes that were artificially introduced by varying the incident proton energy. Specific to our proton unit, proton energy changes of ±1MeV can also be detected indirectly via beam spread measurements. Our combined dosimetric system including an in-house laboratory optical scanner and reusable BaFBr0.85 I0.15 :Eu2+ storage phosphors demonstrated a sufficient spatial resolution and dosimetric accuracy to support its use as an independent proton spot measurement dosimeter system. Its wide dynamic range allows for other versatile applications such as proton halo measurements.

Real-Time Geometric Glint Anti-Aliasing with Normal Map Filtering

Real-time geometric specular anti-aliasing is required when using a low number of pixel samples and high-frequency specular lobes. Several methods have been proposed for mono-lobe bidirectional reflection distribution functions (BRDFs), but none for multi-lobe BRDFs, e.g., a glinty BRDF. We present the first method for real-time geometric glint anti-aliasing (GGAA). It eliminates most of the inconsistent appearing and disappearing of glints on surfaces with significant curvatures during animations. The technique uses the glinty BRDF of Chermain et al. [2020] and leverages hardware GPU-filtering of textures to filter slope distributions on the fly. We also improve this glinty BRDF by adding a correlation factor of slope. This BRDF parameter allows convergence to normal distribution functions that are not aligned on the surface's axes. Above all, this parameter makes glint rendering compatible with normal map filtering using LEAN mapping. Using GGAA increases the rendering time from 0.6 % to 4.2 % and it requires 1/3 more memory due to MIP mapping of tabulated slope distributions. The results are compared with references using a thousand samples per pixel.

The Perception of Multiple Simultaneous Pitches as a Function of Number of Spectral Channels and Spectral Spread in a Noise-Excited Envelope Vocoder.

Cochlear implant (CI) listeners typically perform poorly on tasks involving the pitch of complex tones. This limitation in performance is thought to be mainly due to the restricted number of active channels and the broad current spread that leads to channel interactions and subsequent loss of precise spectral information, with temporal information limited primarily to temporal-envelope cues. Little is known about the degree of spectral resolution required to perceive combinations of multiple pitches, or a single pitch in the presence of other interfering tones in the same spectral region. This study used noise-excited envelope vocoders that simulate the limited resolution of CIs to explore the perception of multiple pitches presented simultaneously. The results show that the resolution required for perceiving multiple complex pitches is comparable to that found in a previous study using single complex tones. Although relatively high performance can be achieved with 48 channels, performance remained near chance when even limited spectral spread (with filter slopes as steep as 144 dB/octave) was introduced to the simulations. Overall, these tight constraints suggest that current CI technology will not be able to convey the pitches of combinations of spectrally overlapping complex tones.

Brillouin Microwave Filter With Enhanced Skirt Selectivity Using a Birefringent Fiber

A technique to enhance the slope of a photonic microwave filter based on the stimulated Brillouin scattering is proposed. It relies on exploiting the polarization dependence of Brillouin gain in birefringent fibers. The presence of two orthogonal Brillouin gains/loss in birefringent fibers results in two filter responses that can be subtracted in a balanced photodetector to remove the slow Lorentzian decay of the natural Brillouin gain response. The experimental results show that a filter slope of 8.3 dB/oct can be obtained.

Reducing Simulated Channel Interaction Reveals Differences in Phoneme Identification Between Children and Adults With Normal Hearing.

Channel interaction, the stimulation of overlapping populations of auditory neurons by distinct cochlear implant (CI) channels, likely limits the speech perception performance of CI users. This study examined the role of vocoder-simulated channel interaction in the ability of children with normal hearing (cNH) and adults with normal hearing (aNH) to recognize spectrally degraded speech. The primary aim was to determine the interaction between number of processing channels and degree of simulated channel interaction on phoneme identification performance as a function of age for cNH and to relate those findings to aNH and to CI users. Medial vowel and consonant identification of cNH (age 8-17 years) and young aNH were assessed under six (for children) or nine (for adults) different conditions of spectral degradation. Stimuli were processed using a noise-band vocoder with 8, 12, and 15 channels and synthesis filter slopes of 15 (aNH only), 30, and 60 dB/octave (all NH subjects). Steeper filter slopes (larger numbers) simulated less electrical current spread and, therefore, less channel interaction. Spectrally degraded performance of the NH listeners was also compared with the unprocessed phoneme identification of school-aged children and adults with CIs. Spectrally degraded phoneme identification improved as a function of age for cNH. For vowel recognition, cNH exhibited an interaction between the number of processing channels and vocoder filter slope, whereas aNH did not. Specifically, for cNH, increasing the number of processing channels only improved vowel identification in the steepest filter slope condition. Additionally, cNH were more sensitive to changes in filter slope. As the filter slopes increased, cNH continued to receive vowel identification benefit beyond where aNH performance plateaued or reached ceiling. For all NH participants, consonant identification improved with increasing filter slopes but was unaffected by the number of processing channels. Although cNH made more phoneme identification errors overall, their phoneme error patterns were similar to aNH. Furthermore, consonant identification of adults with CI was comparable to aNH listening to simulations with shallow filter slopes (15 dB/octave). Vowel identification of earlier-implanted pediatric ears was better than that of later-implanted ears and more comparable to cNH listening in conditions with steep filter slopes (60 dB/octave). Recognition of spectrally degraded phonemes improved when simulated channel interaction was reduced, particularly for children. cNH showed an interaction between number of processing channels and filter slope for vowel identification. The differences observed between cNH and aNH suggest that identification of spectrally degraded phonemes continues to improve through adolescence and that children may benefit from reduced channel interaction beyond where adult performance has plateaued. Comparison to CI users suggests that early implantation may facilitate development of better phoneme discrimination.

Using binaural beat sensitivity to explore mechanisms of bimodal temporal envelope beat sensitivity

Current cochlear implant (CI) fitting strategies aim to maximize speech perception through the CI by allocating all spectral information across the electrode array without regard to tonotopic placement of each electrode along the basilar membrane. For patients with considerable residual hearing in the non-implanted ear, this approach may not be optimal for binaural hearing. This study aims to explore fitting procedures in which CI maps better complement information from the acoustic ear by reducing the frequency mismatch between them. We investigate the mechanisms of binaural temporal-envelope beat sensitivity in normal-hearing listeners using bandpass filtered pulse trains with parameters including stimulus level, filter bandwidth, filter slope, and spectral overlap using bandpass filtered pulse trains. We find the minimum baseline interaural timing difference and spectral mismatch that normal-hearing listeners can tolerate while maintaining their ability to detect interaural timing differences. Initial results consistently demonstrate maximum sensitivity to binaural beats when place of stimulation is matched across ears. The outcomes of this study will provide new information on binaural interactions in normal-hearing listeners and guide methodology for incoming single-sided-deafness patients as we adjust their CI maps in an effort to reduce the frequency-mismatch. [Work supported by NIH grant F32DC016815-01.]

8-order filter based on 2-D photonic crystal with dual-mode microstrip resonators

The design of 8-order band-pass filter based on 2-D photonic crystal is suggested. Strip conductors in all dual-mode resonators are in the form of «irregular» rectangular frame with a gap and are connected at certain points with the ground. At optimal placement of such resonators on a substrate attenuation pole is observed on the amplitude-frequency characteristic of the filter, near low and high bandwidth slope that significantly improves its frequency-selective properties. The change of gap between input and output resonators allows to control the frequency of these poles.

Optimization design of chirp managed lasers by integral layer-peeling method

The chirp managed laser (CML) mainly includes a directly modulated laser followed by an optical spectrum reshaper (OSR) filter. In this paper, an integral layer-peeling method has been applied to synthesize the OSR filter with the desired reflection spectrum, which breaks the trade-off between the filter bandwidth and the filter slope steepness inherently existing in the FP etalon based filter, and hence greatly facilitates the optimization design of the OSR for a better transmission performance of a CML. Using this approach, we have, respectively, investigated the optimization design of the OSR filter in terms of the edge slope and the 3 dB bandwidth in the CML modulated at 10 and 25 Gb/s, through studying their transmission performances over the standard single-mode fiber. With the optimum design of OSR, the longest transmission distances at which the power penalty is 1 dB at a bit error rate of 10−12 are 135 and 18 km for the 10 and 25 Gb/s CML, respectively.

The perception of emotion and focus prosody with varying acoustic cues in cochlear implant simulations with varying filter slopes.

This study aimed to find the optimal filter slope for cochlear implant simulations (vocoding) by testing the effect of a wide range of slopes on the discrimination of emotional and linguistic (focus) prosody, with varying availability of F0 and duration cues. Forty normally hearing participants judged if (non-)vocoded sentences were pronounced with happy or sad emotion, or with adjectival or nominal focus. Sentences were recorded as natural stimuli and manipulated to contain only emotion- or focus-relevant segmental duration or F0 information or both, and then noise-vocoded with 5, 20, 80, 120, and 160 dB/octave filter slopes. Performance increased with steeper slopes, but only up to 120 dB/octave, with bigger effects for emotion than for focus perception. For emotion, results with both cues most closely resembled results with F0, while for focus results with both cues most closely resembled those with duration, showing emotion perception relies primarily on F0, and focus perception on duration. This suggests that filter slopes affect focus perception less than emotion perception because for emotion, F0 is both more informative and more affected. The performance increase until extreme filter slope values suggests that much performance improvement in prosody perception is still to be gained for CI users.

Noise in Load Cell Signal in an Automatic Weighing System Based on a Belt Conveyor

Noise in load cell signal in an automatic weighing system based on a belt conveyor has been examined experimentally in time and frequency domains to enhance signal quality. The noise frequency spectrum showed nonlinearly increasing multiple resonance peaks as speed increased. The noise reduction process using noise reduction algorithm, by sharply rejecting peak noise frequency component and afterward forming optimum pulse width ratio through filter slope control using selective switching of 6 LPF stages, was used for enhanced accuracy. The effectiveness of proposed method, controlling both cutoff frequency and slope of LPF, was evaluated by feeding 50 g test mass, and this noise reduction process showed better noise filtering with enhanced accuracy than fixed cutoff frequency control method. The ratio of top to bottom pulse width showed that LPF cutoff frequency above 5 Hz had the ratio above 50% up to 80 m/min speed range.

Photonic Microwave Filter With Steep Skirt Selectivity Based on Stimulated Brillouin Scattering

A method to enhance the filter slope of Brillouin-based photonic microwave filters is presented. This improvement is achieved by the combination of Brillouin gain and loss responses over phase-modulated signals. The experimental results show passband responses exhibiting a slope of 16.7 dB per octave, which corresponds with a threefold improvement in comparison to the natural Lorentzian response for the same gain.

Early landslide detection based on D-InSAR technique at the Wudongde hydropower reservoir

Differential interferometric synthetic aperture radar (D-InSAR) is an effective technique for geological disaster prevention. In this study, an early landslide detection method based on the D-InSAR technique is proposed. First, SAR data are used to monitor landslide deformation in the Wudongde hydropower reservoir. Then, the ground surface deformation is derived by using the D-InSAR technique, which includes both soil and non-soil deformations. To remove the non-soil deformation, the vertical deformation filter method and slope deformation filter method for extracting soil deformations are established, and the error of D-InSAR results is analyzed. By using two methods, Permanent Scatterers InSAR and Corner Reflectors InSAR, the errors caused by the atmospheric delay are estimated quantitatively. Additionally, the relationship between the landslide deformation and the temporal-spatial change of the SAR data is analyzed, and used to identify landslides. Finally, through the proposed early landslide detection method, the Jinpingzi landslide in the Wudongde area is investigated to validate the proposed method, and the other unknown landslides in this area are also detected, which demonstrates the feasibility of the proposed method. The outcome of this study provides a workable technique for early detection of landslides in valley reservoir areas.

Arrays of subcritical width rectangular speech bands with interpolated noise maintain intelligibility at high intensities

Speech intelligibility declines at high intensities for both normally hearing and hearing-impaired listeners. However, this rollover can be minimized by reducing speech in high frequency regions to an array of noncontiguous bands having vertical filter slopes (i.e., rectangular bands) and widths substantially narrower than a critical band. Normally hearing listeners were presented with “Predictability Low” sentences consisting of a 500-Hz lowpass pedestal band and an array of ten 4% bands spaced at approximately 1/3-octave (alternate ERBn) intervals from 1000 Hz to 8417 Hz. The pedestal band was fixed at 70 dB and the subcritical-band array varied from 55 to 100 dB in peak level. Intelligibility did not vary significantly for levels from 65 to 95 dB, ranging from 86 to 89%. Array intelligibility did significantly decrease to 82% when speech level was increased to 100 dB. However, intelligibility was restored to 88% when lower level rectangular noise bands (−30 dB relative spectrum level) were interpolated between speech bands. It is suggested that subcritical width filtering reduces rollover by limiting firing rate saturation to a subset of fibers within critical bands, and that interpolated noise further reduces saturation via lateral inhibition. Hearing aid applications will be discussed. [Research supported by NIH.]