Frequency Matching Research Articles

Machine Learning-Enhanced ORB Matching Using EfficientPS for Error Reduction

Abstract The study comes up with a new way to improve the accuracy of image matching in binocular vision systems, especially those that are mounted on vehicles. It combines machine learning with the ORB (Oriented FAST and Rotated BRIEF) image-matching algorithms. Standard ORB matching frequently encounters mismatches in complex and repetitive environments. To minimize false positives in matches, our strategy utilizes the EfficientPS (Efficient Panoptic Segmentations) algorithm, a panoramic segmentation technique that uses machine learning in conjunction with ORB. The procedure begins with the EfficientPS approach, which delivers fine-grained and efficient segmentation of images, assigning semantic category labels and unique identifiers to each pixel. The ORB feature point matching process is refined using semantic data to filter out mismatches between foreground objects and the background effectively. This machine-learning-augmented method significantly decreases the frequency of erroneous matches in intricate settings. Empirical findings from the KITTI dataset demonstrate that in non-targeted environments, the accuracy of our proposed method (0.978) is marginally less than that of LoFTR (0.983). Still, it surpasses other methods when utilizing 50 ORB parameters. In more intricate situations, such as multi-target scenarios with an increased number of ORB parameters (200), our method maintains a high level of accuracy (0.883), outperforming the conventional ORB (0.732) and rivaling the performance of DL-BDLMR (0.790) and ORB-MFD-FPMC (0.835). Our method’s processing time is competitive and slightly higher than the standard ORB, but it improves accuracy. In scenarios without targets and with single targets, our method’s processing time (0.195 seconds and 0.211 seconds, respectively) is greater than that of ORB and ORB-MFD-FPMC. Yet, it is significantly lower than that of LoFTR. In multi-target scenarios, our method’s processing time (0.226 seconds) is considerably better than LoFTR’s (0.445 seconds), effectively balancing processing speed and accuracy. We highlight the efficacy of incorporating machine learning to enhance the robustness of image-matching algorithms in dynamic and complex environments.

Bearing Fault Feature Extraction via Adaptive Frequency Matching and Coupling Analysis

Bearing Fault Feature Extraction via Adaptive Frequency Matching and Coupling Analysis

Using Multiple Stator Windings and Multi-Level Converters for Frequency Matching in Microturbine Generators

Using Multiple Stator Windings and Multi-Level Converters for Frequency Matching in Microturbine Generators

The strength of the OH-bend/OH-stretch Fermi resonance in small water clusters.

A novel Raman jet-spectrometer is used to study the Fermi resonance between the OH bending overtone and OH stretching fundamental in small cyclic water clusters (H2O)n with n = 3, 4, 5. The new setup features a recirculating vacuum system which reduces the gas consumption by 2 to 3 orders of magnitude and enables long-term measurements of very weak Raman signals. Raman spectra measured from highly diluted expansions with unprecedented signal-to-noise ratio are presented and cluster-specific intensity ratios and effective coupling constants are derived using Markov-Chain Monte-Carlo methods, yielding a high probability for an almost "perfect" resonance for the tetramer and pentamer, i.e. a close frequency match of bend overtone and stretch fundamental with intensity ratios close to 1, but a larger coupling constant for the trimer, with best estimates close to W5 ≲ 50 cm-1 < W4 ≲ 60 cm-1 < W3 ≈ 65 cm-1.

Salmonella Saintpaul outbreak associated with cantaloupe consumption, the United Kingdom and Portugal, September to November 2023.

In September 2023, the UK Health Security Agency identified cases of Salmonella Saintpaul distributed across England, Scotland, and Wales, all with very low genetic diversity. Additional cases were identified in Portugal following an alert raised by the United Kingdom. Ninety-eight cases with a similar genetic sequence were identified, 93 in the United Kingdom and 5 in Portugal, of which 46% were aged under 10years. Cases formed a phylogenetic cluster with a maximum distance of six single nucleotide polymorphisms (SNPs) and average of less than one SNP between isolates. An outbreak investigation was undertaken, including a case-control study. Among the 25 UK cases included in this study, 13 reported blood in stool and 5 were hospitalized. One hundred controls were recruited via a market research panel using frequency matching for age. Multivariable logistic regression analysis of food exposures in cases and controls identified a strong association with cantaloupe consumption (adjusted odds ratio: 14.22; 95% confidence interval: 2.83-71.43; p-value: 0.001). This outbreak, together with other recent national and international incidents, points to an increase in identifications of large outbreaks of Salmonella linked to melon consumption. We recommend detailed questioning and triangulation of information sources to delineate consumption of specific fruit varieties during Salmonella outbreaks.

Two-axis multiple masses resonator with frequency and Q-factor matching

This paper reports a design and experimental results of a two-axis symmetric dynamically balanced resonator based on a triple mass system, whose frequency and Q-factor can be independently tuned. Two dynamically equivalent proof masses are connected by four coupling springs, and four coupling proof masses are implemented between them. The frequency and Q-factor of the anti-phase modes can be tuned independently of each other. The frequency is tuned by electrostatically softening the suspensions stiffness, and the Q-factor is adjusted by controlling the squeeze film damping through the mode coupling between the anti-phase and in-phase modes. The changes of frequency and mode coupling under different DC bias tunings are studied by FEA, which reveals the modification of the suspension stiffness only decreases the frequency and the modification of the inner stiffness of the coupling proof masses exerts a large effect on the mode shape, i.e. Q-factor, while a minor effect on the frequency. The as-fabricated frequency and Q-factor mismatches were evaluated as 5% and 7.7% in a fabricated device, respectively. A large adjustment of the Q-factor by 21% was observed by adding a 27 V DC voltage on the tuning electrodes inside the coupling proof masses, while the frequency was only decreased by as small as 810 ppm. A mode matching was achieved by electrostatic softening the suspensions of both main proof masses. Thanks to the decoupling between frequency and Q-factor, a frequency matching under 10 ppm and a Q-factor matching under 650 ppm were experimentally proved.

Design of dual-LSPR Bi/W18O49 composite and its red-light driven photocatalytic property in the photocatalytic degradation of PPCPs

Photocatalysis has become an increasingly popular method to treat pharmaceuticals and personal care products (PPCPs) in a water matrix due to its green and energy-saving nature. However, the development of high-efficiency catalysts to remove such refractory organic pollutants still faces many challenges. Herein, an urchin-like composite, Bi/W18O49, was designed and prepared via solvothermal process followed by magnetron sputtering method. The photocatalytic performance of Bi/W18O49 for PPCPs removal proved to be superior under red light (610 nm, 1.23E4 lm) compared with pure WO3 or W18O49, due to better light absorption property and frequency matching between the stronger plasmon resonance (dual-LSPR effect) and incident light irradiation. Thorough experiments were conducted to identify the unique properties of Bi/W18O49, and they demonstrated that the composite state contained plenty of oxygen vacancies and the dual-LSPR effect was vital to the efficient removal for pollutants, as the effect guarantees OV level, hot electron transfer, stable light response ability and more positive potential. The photocatalytic results show that the removal efficiency of trimethoprim, acetaminophen, and tetracycline by Bi/W18O49 could reach 93 %, 87 %, and 62 %, respectively. Combined with density functional theory (DFT) calculations and analysis, trapping tests, and LC-MS measurement, the degradation pathways of those pollutants were described in detail as well. Additionally, different influencing factors such as the concentration of catalyst and pollutants, pH of the solution, various inorganic and organic species were comprehensively investigated, and the reusability and stability property of the product performed well. To the best of our knowledge, this is the first time such Bi/W18O49 composite was prepared and applied in treating PPCPs, representing a new strategy for effective wastewater treatment via the construction of LSPR materials.

Electromechanical analysis of a bending‐torsion coupling piezoelectric energy harvester

SummaryPiezoelectric energy harvester devices have been widely used for collection of the vibration energy. Especially, the cantilever structure has been extensively studied to optimizing its energy harvesting performance. In this paper, a new type of bending torsion coupled piezoelectric energy harvester is proposed with the combination of the elastic connection and the optimized design of the eccentric mass. The energy harvesting performance under indirect impact load is analyzed by the theory of mechanical vibration and Hamiltonian principle. The geometry effect of the tip mass is investigated. The theoretical calculation method is verified by comparison with the finite element method. The results show that reasonable resistance selection and the frequency matching of the main structure and the energy capture structure will significantly change the energy harvesting effect. The frequency matching of the structures can be optimized by improving the eccentric arrangement. It is demonstrated that the proposed structure of the piezoelectric energy harvester has better energy harvesting efficiency as compared with the traditional structures.

Method for Controlling Full-Frequency Band Environment Vibration by Coordinating Metro Vibration Sources and Propagation Paths

Floating slab tracks (FSTs) are used to reduce the impact of vibration on precision instruments and historical relics along metro lines; however, ground vibration is universally amplified at the natural frequency of the tracks. In this study, a full-frequency control method that considers frequency matching for environmental vibrations, in combination with metro vibration sources and propagation paths, was developed based on the bandgap theory of the periodic structure. The effectiveness of this method was analysed by establishing a three-dimensional metro train–FST coupled model and a finite element analysis model of track bed–tunnel–soil–row piles. The results show that ground vibration can be reduced by approximately 3–5 dB at the natural frequency of the FST by adjusting the bandgap range of the periodic piles to 7–9 Hz, eliminating the adverse effect of vibration amplification at the natural frequency of the FSTs. The proposed control method shows good vibration control effects and can effectively minimise ground vibration in the full-frequency range.

Observational Evidence of the Four‐Wave Interaction Between Magnetospheric Whistler Mode Waves

AbstractWhistler mode wave is a crucial emission which can significantly affect the electron dynamics in the magnetosphere. The nonlinear three‐wave interaction between whistler mode waves has been frequently observed, while the four‐wave interaction between these waves is seldom reported. Here, we present two multiband whistler mode wave events by Van Allen Probes, in which the relatively weak wave bands occur exactly corresponding to the strong wave bands. We find that the frequencies of the weak and strong bands satisfy the frequency matching conditions of the four‐wave interaction, and the wave normal angles of the weak bands are almost within the possible ranges calculated from the wave vector matching conditions. Additionally, the cross‐correlation coefficients between the amplitudes of the weak bands and that of strong bands approach 0.80. These results indicate that the weak bands are very likely to be produced by the four‐wave interaction between whistler mode waves. Similar to the three‐wave interaction, the four‐wave interaction can extend the frequency of whistler mode waves from close to 0.5fce to a wider range in both the lower (0.26fce) and upper (0.78fce) bands, and thus potentially play an important role in the electron dynamics.

Does mixing inhaler devices lead to unchecked inhaler technique errors in patients with COPD? Findings from the cross-sectional observational MISMATCH study

BackgroundPatients with chronic obstructive pulmonary disease (COPD) may be prescribed multiple inhalers that require different techniques for optimal performance. Mixing devices has been associated with poorer COPD outcomes suggesting that...

Depletion of Lachnospiraceae Marks the Development of Antibiotic-Associated Neutropenia in Pediatric Patients

Prolonged antibiotic administration has been associated with peripheral cytopenias in up to 10-15% of patients. Of these, neutropenia is particularly notable because of the associated risk of severe bacterial infections. Yet, the mechanisms underlying antibiotic-associated neutropenia remain poorly understood. Recent studies in murine models demonstrate that antibiotics suppress hematopoiesis by depletion of the intestinal microbiota, with concomitant suppression of basal Type I interferon (IFN) and STAT1 signaling. Oral administration of the microbial metabolites that induce Type I IFN restores normal hematopoiesis in antibiotic-treated mice. These findings support a paradigm in which products of the intestinal microbiota enter the bloodstream and travel to the bone marrow where they promote production of growth cytokines that support normal hematopoiesis. To identify microbiota and microbiota-derived metabolites altered in patients with antibiotic-associated neutropenia, we enrolled pediatric patients receiving antibiotic therapy for a planned duration of fourteen days or more in a multicenter-IRB approved study. We analyzed pre- and post-treatment stool samples from 51 subjects by 16S rRNA sequencing and untargeted metabolomics profiling. Neutropenia occurred in 13% of prospectively enrolled subjects. In total, 10 neutropenic patients were included in the study, with 29 control patients selected by frequency matching for age, race, and ethnicity. Length of intravenous antibiotic treatment, total length of antibiotic treatment, length of stay and admission to the intensive care unit were correlated with the development of neutropenia, whereas type of antibiotic or type of infection were not. Based on 16S rRNA sequencing, alpha diversity was significantly decreased in the stool of patients with neutropenia but not in controls (p= 0.027 vs p= 0.059). Analysis of taxa abundance showed significant depletion of Lachnospiraceae in patients with neutropenia (p=0.043), while no significant difference was identified in controls. Lachnospiraceae are a main producer of short chain fatty acids and have been linked to hematopoietic stem cell transplant outcomes. Partial least square-discriminant analysis (sPLS-DA) showed that the metabolomes of neutropenic and control stools were similar at baseline. However, 17 metabolites were differentially abundant after antibiotic treatment in the neutropenic group but not in the control group including citrulline, tyrosine, and N-acetylglucosamine/N-acetylgalactosamine. Future work will assess whether these compounds can rescue antibiotic-associated neutropenia in the animal model. This is the first clinical study linking changes in the intestinal microbiota with antibiotic associated neutropenia. An improved understanding of the molecular mechanisms by which the microbiome sustains normal hematopoiesis will lead to ways to prevent and treat antibiotic-associated bone marrow suppression.

Regulation of microwave absorbing performance of magnetic alloy/ferrite/carbon ternary composites by changing polydopamine-induced carbothermal reduction

Magnetic alloy/ferrite/nitrogen-doped carbon composites (CoFe/CoFe2O4/N–C) spheres were synthesized by controlled carbothermal reduction of Co-doped Fe2O3 nanospheres wrapped in polydopamine. Different dopamine hydrochloride dosages not only affected components and nanostructures, but also regulated the electromagnetic properties of CoFe/CoFe2O4/N–C composites. The results show that with the increase of dopamine hydrochloride dosage, graphitic degree of N-doped carbon layer would decrease after an initial increase, while the Ms values exhibit an opposite trend. All samples show similar μr spectra, and negative μ″ values can be obtained at high frequency, which should be related to eddy current and dielectric resonance. With the increment of polydopamine, εr would first increase due to generation of CoFe and the increase in graphitic degree, and then decrease owing to the agglomeration of spherical particles. Further research on microwave absorption shows that RL peak frequency coincides with the frequency of perfect impedance matching when good impedance matching has been achieved across a wide range of frequencies. Thanks to the synergistic effects of conduction loss, interfacial polarization, dipole polarization, natural resonance, eddy current, and complete interference cancellation, S-100 has a wide effective absorption bandwidth of 4.88 GHz at 2.0 mm and a low RL peak value of −70.48 dB at 1.95 mm. This work could offer new insights into multi-component magnetic MAMs design and illuminate the relationships between reflection loss, impedance matching, interference cancellation, phase composition, and composite structure.

Long-Term Usage of Proton Pump Inhibitors Associated with Prognosis in Patients with Colorectal Cancer.

The dose-response effect of proton pump inhibitors on colorectal cancer prognosis is still under exploration. This population-based study in Taiwan was designed to examine the effect of proton pump inhibitors on overall death, colorectal cancer-specific death, and recurrence in colorectal cancer patients with different cumulative proton pump inhibitor dose levels. This cohort study was based on the Taiwan Cancer Registry and Taiwan National Health Insurance Research Database from 2005 to 2020. After frequency matching with a 1:1 ratio, a total of 20,889 users with proton pump inhibitors and 20,889 without proton pump inhibitors were analyzed. The cumulative defined daily dose level of proton pump inhibitor was stratified to explore the dose-response relationship. A proton pump inhibitor exposure cumulative defined daily dose > 60 after colorectal cancer diagnosis had higher risk of all-cause death than non-proton pump inhibitor users with adjusted hazard ratios of 1.10 (95% CIs: 1.04-1.18). For recurrence, a proton pump inhibitor exposure cumulative defined daily dose > 60 had reduced recurrence risk with an adjusted hazard ratio of 0.84 (95% CIs: 0.76-0.93). This study demonstrated that the long-term use of proton pump inhibitors in patients with colorectal cancer was associated with an increased risk of death that related to the proton pump inhibitor exposure cumulative defined daily dose > 60 and had different dose-response effect in various dose level.

Estimate of the random match frequency of acquired characteristics in footwear: Part I — Impressions in blood

The aim of this study was to estimate random match frequency of randomly acquired characteristics (RAC-RMF) for laboratory-simulated crime scene impressions. Part I of this investigation reports this metric using a dataset of more than 160 questioned impressions created in blood and deposited on tile. A total of 759 RACs were identified in the blood impressions and compared to RACs with positional similarity in test impressions from 1,299 unrelated outsoles. Geometric similarity was quantified using a combination of visual comparisons and mathematical modeling based on percent area overlap. Results indicated that RACs in blood impressions were typically smaller, and therefore exhibited a two-thirds increase in the number of indistinguishable pairs compared to their mated test impressions. For shoes contributing at least one RAC, relative RAC-RMF values ⩾ 0.0008 were encountered at a rate between 3.4% and 34% for the blood impressions examined in this study. Part II of this investigation provides analogous results based on dust impressions deposited on paper and tile. Although the results in Part I and Part II are specific to randomly acquired characteristics and do not translate into an impression-wide RMF estimate, this research shows that RACs in questioned impressions of the type expected in casework co-occur in position and geometry with RACs in non-mated test impressions. Since theoretical models have traditionally been the basis for estimating RAC-RMF in footwear, the overall contribution of this research to the forensic footwear community is a calibration of this estimate based on empirical data.

Adaptive Excitation Frequency Matching and Acoustic-Feature-Based Automatic Hammering Inspection System

Hammering tests are employed for detecting surface and internal damage; however, their accuracy depends on the experience and expertise of inspectors. Because automation techniques can address the limitations of manual hammering tests, researchers have developed automatic hammering inspection systems to replace or assist conventional hammering inspection. Although several studies on automatic hammering inspection have been reported, several challenges hinder the practical application of their results. The relative hammering frequency and identification algorithms for complex and diverse damage are critical factors in implementing developed techniques. In a previous study, an automatic hammering inspection device for rapid and automated damage detection in practical applications was developed. This device can remotely adjust the hammering angle and force to increase detection accuracy and efficiency. Furthermore, an artificial-intelligence-enhanced damage identification method was developed to identify fine concrete cracks accurately using acoustic data. This study developed an automatic hammering inspection system with an adaptive matching function and automatic damage identification to increase the accuracy and efficiency of damage detection. First, by imitating human auditory judgment, an adaptive matching algorithm for the excitation frequencies of different damage types was developed to determine the optimal excitation frequency. Second, the relationships between acoustic features and damage information were analyzed. Finally, two concrete specimens with artificial damage were tested using the proposed system, with the relationships between the acoustic features in the time and frequency domains, as well as the damage location and depth, investigated experimentally. The results show that the proposed system can accurately identify surface and internal damage distributions up to a depth of 100[Formula: see text]mm at 20[Formula: see text]mm intervals.

Estimate of the random match frequency of acquired characteristics in footwear: Part II — Impressions in dust

This study serves as Part II of an investigation into the random match frequency of randomly acquired characteristics (RAC-RMF) in footwear evidence. In Part I, RAC-RMF was estimated in a dataset of laboratory-simulated crime scene impressions deposited in blood. For Part II, a second dataset was created composed of impressions deposited in dust on paper or tile, with the latter lifted using gelatin or Mylar film. A total of 1,513 RACs were identified from more than 160 dust impressions and compared to RACs with positional similarity in test impressions from 1,299 non-mated outsoles. RACs of any size deposited in dust exhibited a 31% decrease in shoes with non-zero RAC-RMFs as compared to their mated test impressions, while those deposited in blood exhibited a 45% increase. When only considering shoes with at least one RAC deemed forensically-reliable (length ⩾ 2.8 mm), 3.1% of shoes contributing dust impressions and 3.4% of shoes contributing blood impressions exhibited relative RAC-RMFs at a value ⩾ 0.0008. Although each dataset resulted in a comparable rate for encountering non-zero RAC-RMFs, the estimate for dust was based on twice the number of RAC comparisons (154,477) than those performed when assessing blood (77,566). While these results are considered specific to the non-mated impressions and methods of analysis described herein, and continued work is required before rates can be fully understood and reported in forensic casework, this study encountered non-zero RAC-RMFs for shoes exhibiting at least one forensically-reliable RAC at a more frequent rate than any estimates previously reported.

Composites of Co-Ti-Mn substituted M-type barium hexaferrite and CuO: Structural, optical, electromagnetic and X-band absorption for commercial applications

In this research, composites of M-type barium hexaferrite (BaFe12O19) substituted with Co-Ti-Mn and Copper oxide (CuO) have been prepared to mitigate electromagnetic pollution caused by cellphones (0.9–40 GHz) and 4G–5G networking technologies. X-ray diffraction (XRD), FTIR and transmission electron microscopy (TEM) were used to study structural and morphological analysis of synthesized composites. In the XRD analysis, the composite shows a pure phase of BaM hexaferrite and copper oxide, this was further confirmed by FTIR. Characteristic absorption bands of Co-Ti-Mn substituted BaM and CuO were observed at 260.9 cm−1, 265.2 cm−1 and 273.4 cm−1; these peaks suggest the formation of BaM and CuO phase. The optical and magnetic properties of synthesized samples were characterized by UV–visspectroscopy and Vibrating sample magnetometer (VSM). The UV-blue LED application is compatible with the band gap observed by UV–visspectroscopy. Hysteresis loops show that the magnetization (Ms), remnant magnetization (Mr) and coercivity (Hc) decreased with the increase of substitution (x). At room temperature, x = 0.10 (CTMC1) yields maximum values such Ms (35.84 emu/g), Mr ( 11.75 emu/g), and Hc (478.002 Oe). The complex permittivity and permeability were investigated in the X-band (8.2–12.4 GHz) using vector network analyzer (VNA). Composite with x = 0.15 (CTMC2) yielded an optimum value of reflection loss up to −35.79 dB at a matching frequency of 11.49 GHz and more than 90 % absorption bandwidth of 1.5 GHz. The results suggest that the synthesized composites have potential to be used as new generations of electromagnetic shielding materials.

Finding environmental discourse in historical newspapers: a topic model workflow for query disambiguation

&#x0D; &#x0D; &#x0D; Digitized historical newspapers are a treasure trove of information for our understanding of the past. As one popular application, the frequencies of query matches can be used to understand the prevalence of some discourse in a historical era. This requires the construction good queries: broad enough to capture diverse contexts and narrow enough to exclude irrelevant ones. For historical research in digital humanities, targeted queries that emphasize precision have been advised. In this paper, we develop an alternative approach, by using broad queries to cast a wider net and then using topic models built on the match contexts to filter out irrelevant matches. Specifically, we look for contexts discussing environmental issues throughout the 20th century using a corpus of two Australian newspapers. We report on a comparison of iteratively constructed narrow and broad queries and their precision and recall, and find our approach to discover roughly 7-10x more matches with a comparable level of accuracy. This combined approach can work well for focussed research projects where deliberate query construction and qualitative feedback on the results is feasible.&#x0D; &#x0D; &#x0D;

Vision protection therapy for prevention of neovascular age-related macular degeneration

To access the effect of vision protection therapy on neovascular conversion in age-related macular degeneration (AMD). Patient unidentified data aggregated by Vestrum Health, LLC (VH) from over 320 US retina specialists was analyzed to compare the conversion rate from dry to neovascular (wet) AMD in a practice employing VPT (VPT group) compared to those employing standard care alone (SCA group) between January 2017 through July 2023. 500,00 eyes were filtered then matched for neovascular conversion risk factors by propensity scoring and compared in a 10/1 ratio of 7370 SCA and 737 VPT treated eyes. SCA eyes had significantly fewer clinical encounters and shorter follow up than the VPT group. Despite this, the risk of neovascular conversion by PS was significantly lower in the VPT group compared to SCA (HR 5.73, p < 0.0001). Analysis matching the encounter frequency of both groups as a post-randomization variable produced a similar HR (HR 5.98, p < 0.0001). Because 9% of eyes in the VPT group were not treated with VPT due to bilateral early (low-risk) AMD, analysis comparing the SCA group to VPT-treated eyes was done that also showed significantly lower conversion rates in the VPT-treated eyes, with or without encounter frequency matching (HR 5.84, 5.65, p < 0.0001). Visual acuity was consistently better in VPT eyes compared to SCA eyes throughout the study time window. The advantage of VPT over SCA increased with increased SCA encounter frequency and higher conversion risk factors, including age and ICD10 coded dry AMD severity. Neovascular (wet) AMD is the main cause of irreversible visual loss worldwide. Consistent with two prior studies, the current study finds Vision Protection Therapy markedly more effective at both recognizing and preventing neovascular AMD than the current standard of care, benefiting the highest risk dry AMD eyes the most.