Strong Interference Effects Research Articles

Fault feature extraction method of gear based on spectral amplitude modulation and autocorrelation analysis

Due to the strong noise interference and amplitude modulation effect, it is difficult to extract the impact characteristics of the fault gear from the spectrum of the fault signal. To tackle these issues, a gear fault feature extraction method based on spectral amplitude modulation (SAM) and autocorrelation analysis is proposed. First, the SAM method is used to decompose the signal into different components according to energy, and the optimal component with the most fault information is determined by combining kurtosis index and magnitude order selection range. Then, the optimal component is denoised using the autocorrelation function. Finally, the fault feature frequency is extracted by calculating the squared envelope spectrum of the denoised signal. The superiority of the method is verified by simulating the signal. Furthermore, the effectiveness and superiority of the method in gear fault diagnosis are verified by comparison with the fast kurtogram, cepstrum pre-whitening, and SAM.

Design of a three-nozzle for air spraying based on jet interference effect and numerical study of spraying process

Due to the problems of many round-trip time and low spraying efficiency when using single-nozzle, a three-nozzle structure is studied in this paper. The spraying process is numerically simulated by the method of computational fluid dynamics. The discrete phase model is used to predict the trajectory of droplets. The interference flow field is formed due to the entrainment of jet. Paint droplets are transported to the target under the action of gas flow field. The geometry of three-nozzle has a significant influence on the characteristics of the interference flow field. The influence of different distance (L) and axis angle (θ) between two adjacent paint holes on the interference gas flow field and coating thickness distribution are analyzed by changing the structure of three-nozzle. Numerical simulation results show that small L and θ result in strong interference effect, while the paint is mainly concentrated in the central region of the target, which is easy to cause overspray. With the gradual increase of L and θ, the strength of interference gradually decreases and the paint gradually spreads to both sides. However, the strength of interference would become very small when L and θ get too large, which is easy to cause an uneven coating film. According to the numerical simulation results, the best spraying effect can be obtained when L = 40 mm and θ = 30°. Compared with single-nozzle and double-nozzle, the effective coating film width of three-nozzle has increased by 414.3% and 176.9%, respectively, which improves the spraying efficiency.Article HighlightsFor the problem of low efficiency of single nozzle, this paper studies a three-nozzle based on jet interference effect.The coating film thickness distribution model is established based on numerical simulation, which avoids expensive and time-consuming experiments.Compared with single-nozzle and double-nozzle, the effective film width of three-nozzle has increased by 414.3% and 176.9%, respectively, which improved the spraying efficiency

Semi-empirical quantum optics for mid-infrared molecular nanophotonics.

Nanoscale infrared (IR) resonators with sub-diffraction limited mode volumes and open geometries have emerged as new platforms for implementing cavity quantum electrodynamics at room temperature. The use of IR nanoantennas and tip nanoprobes to study strong light-matter coupling of molecular vibrations with the vacuum field can be exploited for IR quantum control with nanometer spatial and femtosecond temporal resolution. In order to advance the development of molecule-based quantum nanophotonics in the mid-IR, we propose a generally applicable semi-empirical methodology based on quantum optics to describe light-matter interaction in systems driven by mid-IR femtosecond laser pulses. The theory is shown to reproduce recent experiments on the acceleration of the vibrational relaxation rate in infrared nanostructures. It also provides physical insights on the implementation of coherent phase rotations of the near-field using broadband nanotips. We then apply the quantum framework to develop general tip-design rules for the experimental manipulation of vibrational strong coupling and Fano interference effects in open infrared resonators. We finally propose the possibility of transferring the natural anharmonicity of molecular vibrational levels to the resonator near-field in the weak coupling regime to implement intensity-dependent phase shifts of the coupled system response with strong pulses and develop a vibrational chirping model to understand the effect. The semi-empirical quantum theory is equivalent to first-principles techniques based on Maxwell's equations, but its lower computational cost suggests its use as a rapid design tool for the development of strongly coupled infrared nanophotonic hardware for applications ranging from quantum control of materials to quantum information processing.

Tunable Directional Emission and Collective Dissipation with Quantum Metasurfaces

Subwavelength atomic arrays, recently labeled as quantum metamaterials, have emerged as an exciting platform for obtaining novel quantum optical phenomena. The strong interference effects in these systems generate subradiant excitations that propagate through the atomic array with very long lifetimes. Here, we demonstrate that one can harness these excitations to obtain tunable directional emission patterns and collective dissipative couplings when placing judiciously additional atoms nearby the atomic array. For doing that, we first characterize the optimal square array geometry to obtain directional emission patterns. Then, we characterize the best atomic positions to couple efficiently to the subradiant metasurface excitations and provide several improvement strategies based on entangled atomic clusters or bilayers. Afterward, we also show how the directionality of the emission pattern can be controlled through the relative dipole orientation between the auxiliary atoms and the one of the array. Finally, we benchmark how these directional emission patterns translate into to collective, anisotropic dissipative couplings between the auxiliary atoms by studying the lifetime modification of atomic entangled states.

Highly coherent illumination for imaging through opacity

Imaging through opacity has captured extensive attention in recent years for its promising applications in bioimaging systems and information extraction from scrambled light. Many optimized image reconstruction algorithms and advanced imaging scenarios are introduced and intensively studied in previous researches. However, intensity-based image reconstruction under the highly coherent light illumination is still a major challenge due to the strong interference effect. Here, we demonstrate that imaging through opacity can be implemented efficiently even under the highly coherent illumination with the aid of an intensity-based/incoherent deconvolution algorithm. Based on the experimental and theoretical analysis, we find the small phase correlation length of the diffuser plays a pivotal role in enabling the incoherent deconvolution operation for highly coherent illumination. Furthermore, the deconvolution algorithm shows insensitivity to the light coherence since the spatial frequencies of the object are well preserved in the spatial frequency spectrum of the speckle pattern. Our results provide a phase-information-free scheme for imaging through opacity under the highly coherent illumination. We anticipate our work would motivate the deep understanding of imaging using highly coherent illumination, increase the structural robustness of imaging systems and facilitate wavelength-sensitive imaging applications.

Color variations based on strong-interference effects in oxygen-defective tetragonal ZrO2–x films in nanometer thickness produced by oxidation of zirconium metal foil

A strong-interference film that absorbs visible light by using oxygen-deficient ZrO2–x was produced by heat treatment of Zr metal foil under a low partial pressure of oxygen. The oxygen-defective tetragonal ZrO2–x film contained nanocrystallites several nanometers in size and its thickness (t) increased from 30 to 140 nm on increasing the holding time during heat treatment. The color of the sample changed depending on the thickness of the oxygen-deficient ZrO2–x film from gold (t = 30 nm) through blue (t = 75 nm) to black (t = 140 nm). Thick ZrO2–x films (t ≧ 140 nm) absorbed all visible light, leading to the observed black color, whereas in thinner films (t < 140 nm), strong interference resulted in changes in the sample color, for example, from gold to blue.

Flow-induced cross-flow vibrations of long flexible cylinder with an upstream wake interference

Flow-induced vibration (FIV) of a flexible cylinder with an upstream wake interference at a subcritical Reynolds number is numerically investigated in this study. Two cylinders are installed in a tandem arrangement with the tandem separation between the cylinder centers set at 5.0 diameters. The downstream cylinder is flexible and placed in the wake of the stationary rigid upstream cylinder. A quasi-three-dimensional fluid-structure interaction (FSI) numerical methodology that couples the strip theory-based Lagrangian discrete vortex method with the finite-element method (FEM) for structural dynamics is developed to simulate the FIV response of the flexible cylinder with the upstream wake interference. The vortex-induced vibration (VIV) of an identical isolated cylinder is also numerically simulated as a contrast. This numerical study characterizes the dynamic response of the cylinder FIV with the upstream wake interference and sheds light on the FSI mechanisms responsible for the structural dynamic response. With the upstream wake interference, the cylinder FIV response shows two features distinct from the isolated VIV response: the vibration of large amplitude during the modal resonance branch transition and the extension of the modal resonance branch. The hydrodynamic coefficients database is constructed by the rigid cylinder forced vibration experiment to help explain the FSI properties of the FIV dynamic response. The lower added mass coefficient for the FIV with the upstream wake interference than the VIV of the isolated cylinder guarantees the synchronization between the vortex shedding frequency and the “true” natural frequency of the structure persisting to higher reduced velocity in a certain modal resonance response branch. The excitation coefficient distribution indicates that the cylinder FIV with the upstream wake interference reaches higher amplitude at high reduced velocity, instead of ceasing resonance as the isolated cylinder. The numerical wake visualization is shown and used to explain the correlation between the distribution of hydrodynamic coefficients along the cylinder span and the wake vortex mode. It is found that the upstream wake interference effect is strongly correlated with the vortex–structure interaction pattern between the upstream wake vortices and the downstream motion. When the upstream vortex impinges on the downstream cylinder and splits into subvortices, the effect of the upstream wake interference acting on the downstream cylinder reduces. When the downstream cylinder enters the gap between the upstream vortices over the entire vibration process, the upstream wake has a stronger interference effect on the downstream FIV response.

Manual and Spoken Cues in French Sign Language's Lexical Access: Evidence From Mouthing in a Sign-Picture Priming Paradigm.

Although Sign Languages are gestural languages, the fact remains that some linguistic information can also be conveyed by spoken components as mouthing. Mouthing usually tend to reproduce the more relevant phonetic part of the equivalent spoken word matching with the manual sign. Therefore, one crucial issue in sign language is to understand whether mouthing is part of the signs themselves or not, and to which extent it contributes to the construction of signs meaning. Another question is to know whether mouthing patterns constitute a phonological or a semantic cue in the lexical sign entry. This study aimed to investigate the role of mouthing on the processing of lexical signs in French Sign Language (LSF), according the type of bilingualism (intramodal vs. bimodal). For this purpose, a behavioral sign-picture lexical decision experiment was designed. Intramodal signers (native deaf adults) and Bimodal signers (fluent hearing adults) have to decide as fast as possible whether a picture matched with the sign seen just before. Five experimental conditions in which the pair sign-mouthing were congruent or incongruent were created. Our results showed a strong interference effect when the sign-mouthing matching was incongruent, reflected by higher error rates and lengthened reaction times compared with the congruent condition. This finding suggests that both groups of signers use the available lexical information contained in mouthing during accessing the sign meaning. In addition, deaf intramodal signers were strongly interfered than hearing bimodal signers. Taken together, our data indicate that mouthing is a determining factor in LSF lexical access, specifically in deaf signers.

Influence of wind yaw angle and pylon interference on the buffeting responses of cable-stayed bridges during construction

The present study focuses on the effects of wind yaw angle and pylon interference on the buffeting responses of bridge decks during construction. Two typical cable-stayed bridges with rhombus pylons (RPs) and single-column pylons (SPs) in the maximum double cantilever state were selected as research objectives. The influence of the wind yaw angle and pylon interference on the lateral, vertical and torsional buffeting displacements were systematically analyzed through full bridge model aeroelastic wind tunnel tests. The research results show that the maximum buffeting responses appear when the wind yaw angle is in the range of to The effects of the wind yaw angle on the buffeting responses become more obvious in cases of high mean wind speeds. The pylon interference effects on the lateral buffeting displacements are more significant than those on the vertical and torsional buffeting displacements. The strong pylon interference effects may lead to non-conservative buffeting response estimation results using traditional buffeting analysis methods. This study demonstrates that it is of paramount importance to take into consideration the combined effects of the wind yaw angle and pylon interference in the design of long-span cable-stayed bridges during their construction stages.

Seismic diffraction separation in the near surface: Detection of high-contrast voids in unconsolidated soils

Seismic diffractions carry the signature of near-surface high-contrast anomalies and need to be extracted from the data to complement the reflection processing and other geophysical techniques. Because diffractions are often masked by reflections, surface waves, and noise, careful diffraction separation is required as a first step for diffraction imaging. A multiparameter time-imaging method is used to separate near-surface diffractions. The implemented scheme makes use of the wavefront attributes that are reliable fully data-derived processing parameters. To mitigate the effect of strong noise and wavefield interference in near-surface data, our workflow incorporates two wavefront-based parameters, dip angle and coherence, as additional constraints. The output of the diffraction separation is a time trace-based stacked section that provides the basis for further analysis and applications such as time migration. To evaluate the performance of the proposed wavefront-based workflow, it is applied to two challenging field data sets that were collected over small culverts in very near-surface soft soil environments. The results of the proposed constrained workflow and the existing unconstrained approach are presented and compared. The proposed workflow demonstrates superiority over the existing method by attenuating more reflection and noise, leading to improved diffraction separation. The abundance of unmasked diffractions reveals that the very near surface is highly scattering. Time migration is carried out to enhance anomaly detection by focusing the isolated diffractions. Although strong diffractivity is observed at the approximate location of the targets, there are other diffracting zones observed in the final sections that might bring uncertainties for interpretation.

Post-capture processes contribute to statistical learning of distractor locations in visual search

People can learn to ignore salient distractors that occur frequently at particular locations, making them interfere less with task performance. This effect has been attributed to learnt suppression of the likely distractor locations at a pre-selective stage of attentional-priority computation. However, rather than distractors at frequent (vs rare) locations being just less likely to capture attention, attention may possibly also be disengaged faster from such distractors – a post-selective contribution to their reduced interference. Eye-movement studies confirm that learnt suppression, evidenced by a reduced rate of oculomotor capture by distractors at frequent locations, is a major factor, whereas the evidence is mixed with regard to a role of rapid disengagement However, methodological choices in these studies limited conclusions as to the contribution of a post-capture effect. Using an adjusted design, here we positively establish the rapid-disengagement effect, while corroborating the oculomotor-capture effect. Moreover, we examine distractor-location learning effects not only for distractors defined in a different visual dimension to the search target, but also for distractors defined within the same dimension, which are known to cause particularly strong interference and probability-cueing effects. Here, we show that both oculomotor-capture and disengagement dynamics contribute to this pattern. Additionally, on distractor-absent trials, the slowed responses to targets at frequent distractor locations—that we observe only in same-, but not different-, dimension conditions—arise pre-selectively, in prolonged latencies of the very first saccade. This supports the idea that learnt suppression is implemented at a different level of priority computation with same-versus different-dimension distractors.

Accurate estimation of line-of-sight rate under strong impact interference effect

In the process of the terminal guidance of a kinetic kill vehicle (KKV), it is very important to accurately estimate the line-of-sight (LOS) rate via the measurements of a target seeker onboard the KKV. The strong impact interference caused by the large lateral thrust produced by the thrusters on the KKV is a main factor that affects the measurements on the LOS angle. A method to estimate the impact interference and the LOS rate together via a Kalman filter is proposed to improve the estimation precision of the LOS rate. The observability of the system describing the missile-target relative motion model and the impact interference model is proved, and then a Kalman filter is designed. In the Kalman filter design, the continuous-discrete and two-stage filtering techniques are used because the system model is time-variant and high-order. Numerical simulation results show that by estimating the impact interference, the estimation precision of the LOS rate is increased, and so the miss distance of the KKV under the strong impact interference is reduced. The proposed continuous-discrete two-stage Kalman filter shows higher estimation precision and lower computational cost than the naive discrete augmented state Kalman filter.

Silencing long non-coding RNA HIF1A-AS2 inhibits proliferation, invasion and migration of cervical cancer cells in vitro

To explore the inhibitory effects of silencing long non-coding RNA (LncRNA) HIF1A-AS2 on epithelialmesenchymal transition (EMT) and tumor stem cell-like phenotype in cervical cancer cells. We designed 3 shRNA constructs for silencing HIF1A-AS2 in CaSki cells, and the shRNA with the strongest interference effect was selected for subsequent experiment. CaSki cells were transfected with shRNA-NC or Sh-HIF1A-AS2, and the changes in cell viability, invasion ability, EMT, expressions of EMT-related proteins, formation of cell spheres and expressions of stem cell markers were detected. Transfection with shRNA-NC and Sh-HIF1A-AS2 did not significantly affected the viability of CaSki cells (P > 0.05). Compared with the cells transfected with shRNA-NC, the cells transfected with Sh- HIF1A-AS2 showed significantly reduced invasion ability, expressions of vimentin N-cadherin, and cell sphere formation ability. HIF1A-AS2 silencing obviously lowered the rate of ABCG2-positive cells, significantly reduced the mRNA and protein expressions of Nanog, OCT4, and SOX2, and strongly enhanced the expression of E-cadherin in CaSki cells (P < 0.05). Silencing HIF1A-AS2 can inhibit proliferation, invasion and migration of cervical cancer cells in vitro.

Silencing the odorant coreceptor (Orco) disrupts sex pheromonal communication and feeding responses in Blattella germanica: toward an alternative target for controlling insect-transmitted human diseases.

The German cockroach, Blattella germanica, is one of the most severe pests of urban and rural areas. High-throughput genetic screening approaches indicate that the olfactory system of this pest is extremely powerful because it has an extensive array of olfactory receptor genes compared with many other insect species. Several of these genes have been identified previously, but their functions have not yet been characterized. This study describes the sequence of five transcriptomes of B. germanica adult male antennae, female antennae, maxillary palps, legs, and fifth-instar nymph antennae to investigate expression patterns of odorant receptors (ORs). Approximately 90% of ORs were found to be the most highly expressed genes in adult or nymph antennae. Additionally, every OR requires an odorant co-receptor (Orco) to become fully functional, and this was selected and successfully inhibited by injection of the corresponding double-stranded (ds)RNA targeting the Orco. A strong RNA interference (RNAi) effect was observed in which > 75% of Orco messenger RNA (mRNA) was clearly suppressed after 72 h of treatment. Olfactory behavioral assays showed that Orco-impaired B. germanica respond more slowly and show less attraction to one volatile sex pheromone and food resources compared with a control group. The results show that Orco plays a pivotal role in both sex pheromone and food-seeking olfactory processes, and provide an alternative genetic technique for controlling this urban pest species by olfactory disruption. © 2020 Society of Chemical Industry.

Effects of reward associations on components of attentional network

Previous research has revealed the influence of reward associations on attentional selection and control. The attentional network can be divided into three components according to its function: Alerting, orienting, and executive control. In the current research, we used training-test procedure and attention network test variant to investigate the effects of color-based reward associations on alerting (Experiment 1), orienting (Experiment 2), executive control (Experiment 3), as well as the interactions among these three networks (Experiment 4). The findings were as follows: Compared with colors previously associated with low reward, colors previously associated with high reward trigger stronger alerting and orienting effects (Experiments 1 and 2), and they had stronger interference effects when functioning as features of flanker distractor (Experiment 3). More importantly, reward associations had only a positive impact on the interaction of orienting by executive control but not on the interaction of alerting by executive control (Experiment 4). In summary, reward associations have different effects on the three attentional networks and can enhance the interaction of orienting by executive control.

Multi-color modulation of phase-changing optical coatings

Now, various display screens transmit massive information to people all the time and become an important window of human-computer interaction. Solid state optical coating utilizes optical interference effect and inherent optical properties of materials to achieve multiple colors. In this paper, between Fabry-Perot (F-P) cavity coating with dielectric layer and strong interference effect (SIE) coating without dielectric layer were compared. Effect of film thickness on F-P cavity optical phase change coating was studied. The results show that the F-P cavity coating with a dielectric layer has more reflective states than the coating without a strong interference effect, that is, potential for optical coating display. In addition, in the F-P cavity coating, by controlling the thickness of SiO2 and Ge2Sb2Te5 (GST) film, the optical coating shows rich color due to the change of F-P optical cavity length and strong interference effect of materials. We also carried out a study of the flexible substrate compatibility and substrate color of the two structures, and found that they are well compatible with flexible materials, and F-P is more sensitive to substrate color than SIE structures in terms of substrate color. Due to the far subwavelength layer thickness, most phase shift is accumulated on reflection at the interfaces, which makes the reflectance profile robust under tilted incidence.

Commensurate and incommensurate double moire interference in graphene encapsulated by hexagonal boron nitride

Interference of double moire patterns of graphene (G) encapsulated by hexagonal boron nitride (BN) can alter the electronic structure features near the primary/secondary Dirac points and the electron-hole symmetry introduced by a single G/BN moire pattern depending on the relative stacking arrangements of the top/bottom BN layers. We show that strong interference effects are found in nearly aligned BN/G/BN and BN/G/NB and obtain the evolution of the associated density of states as a function of moire superlattice twist angles. For equal moire periods and commensurate patterns with Δφ = 0° modulo 60° moire angle differences the patterns can add up constructively leading to large pseudogaps of about ∼ 50 meV on the hole side or cancel out destructively depending on their relative sliding, e.g. partially recovering electron-hole symmetry. The electronic structure of moire quasicrystals for Δφ = 30° differences reveal double moire features in the density of states with almost isolated van Hove singularities where we can expect strong correlations.

Critical Role of a Nanometer-Scale Microballoon Shell on Bulk Acoustic Properties of Doped Soft Matter.

A material's acoustic properties depend critically upon porosity. Doping a soft material with gas-filled microballoons permits a controlled variation of the porosity through a scalable fabrication process while generating well-tailored spherical cavities that are impermeable to liquids. However, evidence is lacking of how the nanometer-scale polymeric shell contributes to the overall effective material properties in the regime where the wavelength is comparable to the sample thickness. Here, we measure ultrasound transmission through a microballoon-doped soft material as a function of microballoon and impurity concentration, sample thickness, and frequency. The measured longitudinal wave speeds are an order of magnitude larger than those in similar systems where no shell is present, while the transverse wave speed is found to linearly increase with microballoon concentration, also in contrast to systems with no shell. Furthermore, we find the results are independent of the soft material's elastic moduli as well as a lesser contribution of the microballoon shell on material attenuation. The results are validated with a multiple scattering model and suggest the shell contributes significantly to the material's bulk acoustic properties despite its thickness being 4 orders of magnitude smaller than the acoustic wavelength. Our results demonstrate how a nanometer-scale interface between a gas cavity and a soft polymer can be used in the submicrometer design of acoustic materials, and are important for observations of such phenomena as strong interference effects in soft matter.

Electron quantum interference in epitaxial antiferromagnetic NiO thin films

The electron reflectivity from NiO thin films grown on Ag(001) has been systematically studied as a function of film thickness and electron energy. A strong electron quantum interference effect was observed from the NiO film, which is used to derive the unoccupied band dispersion above the Fermi surface along the Γ−X direction using the phase accumulation model. The experimental bands agree well with first-principles calculations. A weaker electron quantum interference effect was also observed from the CoO film.

Causal Inference with Bipartite Designs

Bipartite experiments are a recent object of study in causal inference, whereby treatment is applied to one set of units and outcomes of interest are measured on a different set of units. These experiments are particularly useful in settings where strong interference effects occur between units of a bipartite graph. In market experiments, for example, assigning treatment at the seller-level and measuring outcomes at the buyer-level (or vice-versa) may lead to causal models that better account for the interference that naturally occurs between buyers and sellers. While bipartite experiments have been shown to improve the estimation of causal effects in certain settings, the analysis must be done carefully so as to not introduce unnecessary bias. We leverage the generalized propensity score literature to show that we can obtain unbiased estimates of causal effects for bipartite experiments under a standard set of assumptions. We also discuss the construction of confidence sets with proper coverage probabilities. We evaluate these methods using a bipartite graph from a publicly available dataset studied in previous work on bipartite experiments, showing through simulations a significant bias reduction and improved coverage.