A Novel Trajectory Feature-Boosting Network for Trajectory Prediction.

Trajectory prediction is an essential task in many applications, including autonomous driving, robotics, and surveillance systems. In this paper, we propose a novel trajectory prediction network, called TFBNet (trajectory feature-boosting network), that utilizes trajectory feature boosting to enhance prediction accuracy. TFBNet operates by mapping the original trajectory data to a high-dimensional space, analyzing the change rules of the trajectory in this space, and finally aggregating the trajectory goals to generate the final trajectory. Our approach presents a new perspective on trajectory prediction. We evaluate TFBNet on five real-world datasets and compare it to state-of-the-art methods. Our results demonstrate that TFBNet achieves significant improvements in the ADE (average displacement error) and FDE (final displacement error) indicators, with increases of 46% and 52%, respectively. These results validate the effectiveness of our proposed approach and its potential to improve the performance of trajectory prediction models in various applications.

miR-3075 Inhibited the Migration of Schwann Cells by Targeting Cntn2.

Peripheral nerve injury is a complex biological process that involves the expression changes of various coding and non-coding RNAs. Previously, a number of novel miRNAs that were dysregulated in rat sciatic nerve stumps after peripheral nerve injury were identified and functionally annotated by Solexa sequencing. In the current study, we studied one of these identified novel miRNAs, miR-3075, in depth. Results of transwell-based cell migration assay showed that increased expression of miR-3075 suppressed the migration rate of Schwann cells while decreased expression of miR-3075 elevated the migration rate of Schwann cells, demonstrating that miR-3075 inhibited Schwann cell migration. Results of BrdU cell proliferation assay showed that neither miR-3075 mimic nor miR-3075 inhibitor would affect Schwann cell proliferation. We further studied candidate target genes of miR-3075 by using bioinformatic tools and analyzing gene expression patterns and found that miR-3075 might target contactin 2 (Cntn2). Previous study showed that Cntn2 regulated cell migration and myelination. Our current observation suggested that the biological effects of miR-3075 on Schwann cell phenotype might by through the negative regulation of Cntn2. Overall, our study revealed the function of a novel miRNA, miR-3075, and expanded our current understanding of the molecular mechanisms underlying peripheral nerve injury and regeneration.

Fabrication of continuous phase plates with small structures based on recursive frequency filtered ion beam figuring.

Large surface gradient and extensive mid-to-high spatial frequency in continuous phase plates (CPPs) with small structures make it difficult to achieve high-precision fabrication. An ion beam figuring (IBF) technology to fabricate CPPs with such characteristics is proposed in this paper. In order to imprint CPP microstructures with smaller spatial periods even down to 1mm in shorter time, we present a multi-pass IBF approach with different ion beam sizes based on the frequency filtering method. We discuss the selection principle and when to reduce ion beam sizes for different procedures to control dwell time and adequately exert the corrective capability in detail. This filtering method can obtains better surface quality in a faster way compared to the non filtering traditional IBF method. The experimental results verify this optimized method can effectively imprint complex microstructures with spatial period as small as 0.7 mm, surface peak-to-valleys (PV) smaller than 200nm and surface gradient as large as 1.8µm/cm to within 10 nm root-mean-square (RMS) of design specifications, which displays the advantages of our fabrication method.

Efficient fabrication of ultrasmooth and defect-free quartz glass surface by hydrodynamic effect polishing combined with ion beam figuring.

Material removal rate has greatly relied on the distribution of shear stress and dynamic pressure on the workpiece surface in hydrodynamic effect polishing (HEP). Fluid dynamic simulation results demonstrate that the higher rotation speed and smaller clearance will cause the larger material removal rate. Molecular dynamic (MD) calculations show the bonding energy of Si-O in the silicon-oxide nanoparticle is stronger than that in the quartz glass, and therefore the atoms can be dragged away from the quartz glass surface by the adsorbed silicon-oxide nanoparticle. The deep subsurface damage cannot be efficiently removed by HEP due to its extremely low removal rate. However, the subsurface damaged layer can be quickly removed by ion beam figuring (IBF), and a thinner layer containing the passivated scratches and pits will be left on the surface. The passivated layer is so thin that can be easily removed by HEP process with a low material rate under the large wheel-workpiece clearance. Combined with the IBF process, the subsurface damage and surface scratches have been efficiently removed after the HEP process. Meanwhile there are not obvious duplicated marks on the processed surface and the surface roughness has been improved to 0.130nm rms, 0.103nm Ra.

Detection of subsurface trace impurity in polished fused silica with biological method.

Subsurface damage (SSD), especially photoactive impurities, degrades the performance of high energy optics by reduction in the laser induced damage threshold. As the polishing defects are trace content and lie beneath the surface, they are difficult to detect. We herein present a biological method to measure impurities on polished fused silica, based on the intense inhibiting ability about trace level of ceria on enzyme activity. And the enzyme activity is measured in the individual etching solutions of a sequential etching process. Results show that detectability of the biological method satisfies the needs of trace impurity detection with low cost and simple apparatus. Furthermore ceria can be used to tag SSD in lapped and polished optics.

Surface evaluation and evolution during hydrodynamic effect polishing for quartz glass.

Hydrodynamic effect polishing (HEP), a noncontact machining process, can realize the processed surface roughness as small as atomic level. To investigate the subsurface structure, the HEP processed quartz glass surface was etched by the hydrofluoric acid solution. It has been proved that HEP is a polishing method with the ability to process the surface with atomic-level flatness and damage-free surface/subsurface. It has been found that the microplastic scratches on the lap prepolished glass were obviously exposed when the thin redeposition layer was removed. Then the scratches were gradually removed and surface roughness decreased quickly as the removal depth increased. The surface becomes very smooth and the surface roughness maintains at an atomic level when the subsurface damage is removed clearly. The experimental results demonstrated that the defects such as the scratches parallel to the rotational axis of the wheel were firstly removed during the polishing process, and then the defects vertical to the wheel rotational axis were removed.

Ultrasmooth surface polishing based on the hydrodynamic effect.

This study will examine the feasibility of applying the hydrodynamic effect to ultrasmooth surface polishing. Differing from conventional pad polishing, hydrodynamic effect polishing is noncontact, as the polishing wheel is floated on the workpiece under the hydrodynamic effect. The material removal mechanism and the removal contour are analyzed in detail. Dynamic pressure and shear stress distribution on the workpiece are numerically simulated in three dimensions under different clearances between the polishing wheel and the workpiece, showing that the dynamic pressure distribution and the magnitude of shear stress on the workpiece are greatly influenced by the clearance. It is clearly demonstrated from fixed-point polishing experiments that material removal rates and contours are determined by the combined action of dynamic pressure and shear stress. A material removal analytic model is presented with the hydrodynamic effect polishing method. Finally, a polishing experiment is conducted on a quartz glass and the plastic scratches, cracks, and bumpy structures on the initial surface are clearly removed. Moreover, the processed surface roughness is improved to 0.145 nm rms, 0.116 nm Ra.

Material removal mode affected by the particle size in fluid jet polishing.

As a newly developed ultrasmooth polishing technique, fluid jet polishing (FJP) has been widely used for optical glass polishing. The size of the particle in the polishing slurry has a great influence on the material removal rate and quality of the processed surface. The material removal mode affected by the particle size is investigated in detail. Particle trajectories with different size are calculated by numerical simulations in the FJP process. Simulation results demonstrate that the particle with large size will seriously deviate from the fluid streamline and almost impact on the workpiece along a straight line in the initial incident direction. The larger is the particle size, the more deviation will occur. Impact models are established based on different particle trajectories. A polishing experiment was conducted to verify the feasibility of the mode. Experiment results show that the particle size has a great influence on the material removal mode in FJP with the same process parameters. Material is removed in the plastic mode with higher removal rate and worse surface roughness for a larger-sized particle, while the material removal occurring in the elastic mode has a much lower removal rate and smoother surface for the smaller-sized particle. Material is removed by chemical impact reaction between the particle and the surface within the elastic mode, and a smooth surface with no damage is obtained after the FJP process.

Research on the Sound Insulation Performance of Composite Rubber Reinforced with Hollow Glass Microsphere Based on Acoustic Finite Element Simulation.

The composite rubber reinforced with hollow glass microsphere (HGM) was a promising composite material for noise reduction, and its sound insulation mechanism was studied based on an acoustic finite element simulation to gain the appropriate parameter with certain constraint conditions. The built simulation model included the air domain, polymer domain and inorganic particles domain. The sound insulation mechanism of the composite material was investigated through distributions of the sound pressure and sound pressure level. The influences of the parameters on the sound transmission loss (STL) were researched one by one, such as the densities of the composite rubber and HGM, the acoustic velocities in the polymer and inorganic particle, the frequency of the incident wave, the thickness of the sound insulator, and the diameter, volume ratio and hollow ratio of the HGM. The weighted STL with the 1/3 octave band was treated as the evaluation criterion to compare the sound insulation property with the various parameters. For the limited thicknesses of 1 mm, 2 mm, 3 mm and 4 mm, the corresponding optimal weighted STL of the composite material reached 14.02 dB, 19.88 dB, 22.838 dB and 25.27 dB with the selected parameters, which exhibited an excellent sound insulation performance and could promote the practical applications of the proposed composite rubber reinforced with HGM.

An improved graph convolutional network with feature and temporal attention for multivariate water quality prediction.

The analysis and prediction of water quality are of great significance to water quality management and pollution control. In general, current water quality prediction methods are often aimed at single indicator, while the prediction effect is not ideal for multivariate water quality data. At the same time, there may be some correlations between multiple indicators which the conventional prediction models cannot capture. To resolve these problems, this paper proposes a deep learning model: Graph Convolutional Network with Feature and Temporal Attention (FTGCN), realizing the prediction for multivariable water quality data. Firstly, a feature attention mechanism based on multi-head self-attention is designed to capture the potential correlations between water indicators. Then, a temporal prediction module including temporal convolution and bidirectional GRU with a temporal attention mechanism is designed to deal with temporal dependencies of time series. Moreover, an adaptive graph learning mechanism is introduced to extract hidden associations between water quality indicators. An auto-regression module is also added to solve the disadvantage of non-linear nature of neural networks. Finally, an evolutionary algorithm is adopted to optimize the parameters of the proposed model. Our model is applied on four real-world water quality datasets, compared with other models for multivariate time series forecasting. Experimental results demonstrate that the proposed model has a better performance in water quality prediction than others by two indices.

Study on Sound-Insulation Performance of an Acoustic Metamaterial of Air-Permeable Multiple-Parallel-Connection Folding Chambers by Acoustic Finite Element Simulation.

In order to achieve a balance between sound insulation and ventilation, a novel acoustic metamaterial of air-permeable multiple-parallel-connection folding chambers was proposed in this study that was based on Fano-like interference, and its sound-insulation performance was investigated through acoustic finite element simulation. Each layer of the multiple-parallel-connection folding chambers consisted of a square front panel with many apertures and a corresponding chamber with many cavities, which were able to extend both in the thickness direction and in the plane direction. Parametric analysis was conducted for the number of layers nl and turns nt, the thickness of each layer L2, the inner side lengths of the helical chamber a1, and the interval s among the various cavities. With the parameters of nl = 10, nt = 1, L2 = 10 mm, a1 = 28 mm, and s = 1 mm, there were 21 sound-transmission-loss peaks in the frequency range 200-1600 Hz, and the sound-transmission loss reached 26.05 dB, 26.85 dB, 27.03 dB, and 33.6 dB at the low frequencies 468 Hz, 525 Hz, 560 Hz, and 580 Hz, respectively. Meanwhile, the corresponding open area for air passage reached 55.18%, which yielded a capacity for both efficient ventilation and high selective-sound-insulation performance.

Analysis of Influencing Factors for Stackable and Expandable Acoustic Metamaterial with Multiple Tortuous Channels.

To reduce the noise generated by large mechanical equipment, a stackable and expandable acoustic metamaterial with multiple tortuous channels (SEAM-MTCs) was developed in this study. The proposed SEAM-MTCs consisted of odd panels, even panels, chambers, and a final closing plate, and these component parts could be fabricated separately and then assembled. The influencing factors, including the number of layers N, the thickness of panel t0, the size of square aperture a, and the depth of chamber T0 were investigated using acoustic finite element simulation. The sound absorption mechanism was exhibited by the distributions of the total acoustic energy density at the resonance frequencies. The number of resonance frequencies increased from 13 to 31 with the number of layers N increasing from 2 to 6, and the average sound absorption coefficients in [200 Hz, 6000 Hz] was improved from 0.5169 to 0.6160. The experimental validation of actual sound absorption coefficients in [200 Hz, 1600 Hz] showed excellent consistency with simulation data, which proved the accuracy of the finite element simulation model and the reliability of the analysis of influencing factors. The proposed SEAM-MTCs has great potential in the field of equipment noise reduction.

Effects of Aperture Shape on Absorption Property of Acoustic Metamaterial of Parallel-Connection Helmholtz Resonator.

A Helmholtz resonator (HR) with an embedded aperture is an effective acoustic metamaterial for noise reduction in the low-frequency range. Its sound absorption property is significantly affected by the aperture shape. Sound absorption properties of HRs with the embedded aperture for various tangent sectional shapes were studied by a two-dimensional acoustic finite element simulation. The sequence of resonance frequency from low to high was olive, common trapeziform, reverse trapeziform, dumbbell and rectangle. Meanwhile, those HRs for various cross-sectional shapes were investigated by a three-dimensional acoustic finite element simulation. The sequence of resonance frequency from low to high were round, regular hexagon, square, regular triangle and regular pentagon. Moreover, the reason for these phenomena was analyzed by the distributions of sound pressure, acoustic velocity and temperature. Furthermore, on the basement of the optimum tangent and cross-sectional shape, the sound absorption property of parallel-connection Helmholtz resonators was optimized. The experimental sample with optimal parameters was fabricated, and its average sound absorption coefficient reached 0.7821 in 500-820 Hz with a limited thickness of 30 mm. The research achievements proved the significance of aperture shape, which provided guidance for the development of sound absorbers in the low-frequency range.

Investigation and Optimization of the Impact of Printing Orientation on Mechanical Properties of Resin Sample in the Low-Force Stereolithography Additive Manufacturing.

The mechanical properties of resin samples in low-force stereolithography additive manufacturing were affected by the printing orientation, and were investigated and optimized to achieve excellent single or comprehensive tensile strength, compressive strength, and flexural modulus. The resin samples were fabricated using a Form3 3D printer based on light curing technology according to the corresponding national standards, and they were detected using a universal testing machine to test their mechanical properties. The influence of the printing orientation was represented by the rotation angle of the resin samples relative to the x-axis, y-axis and z-axis, and the parameters was selected in the range 0°-90° with an interval of 30°. The multiple regression models for the mechanical properties of the prepared resin samples were obtained based on least square estimation, which offered a foundation from which to optimize the parameters of the printing orientation by cuckoo search algorithm. The optimal parameters for the tensile strength, compressive strength and flexural modulus were 'α = 45°, ß = 25°, γ = 90°', 'ß = 0°, ß = 51°, γ = 85°' and 'α = 26°, ß = 0°, γ = 90°', respectively, which obtained the improvements of 80.52%, 15.94%, and 48.85%, respectively, relative to the worst conditions. The mechanism was qualitatively discussed based on the force analysis. The achievements obtained in this study proved that optimization of the printing orientation could improve the mechanical properties of the fabricated sample, which provided a reference for all additive manufacturing methods.

Development of Adjustable Parallel Helmholtz Acoustic Metamaterial for Broad Low-Frequency Sound Absorption Band.

For the common difficulties of noise control in a low frequency region, an adjustable parallel Helmholtz acoustic metamaterial (APH-AM) was developed to gain broad sound absorption band by introducing multiple resonant chambers to enlarge the absorption bandwidth and tuning length of rear cavity for each chamber. Based on the coupling analysis of double resonators, the generation mechanism of broad sound absorption by adjusting the structural parameters was analyzed, which provided a foundation for the development of APH-AM with tunable chambers. Different from other optimization designs by theoretical modeling or finite element simulation, the adjustment of sound absorption performance for the proposed APH-AM could be directly conducted in transfer function tube measurement by changing the length of rear cavity for each chamber. According to optimization process of APH-AM, The target for all sound absorption coefficients above 0.9 was achieved in 602-1287 Hz with normal incidence and that for all sound absorption coefficients above 0.85 was obtained in 618-1482 Hz. The distributions of sound pressure for peak absorption frequency points were obtained in the finite element simulation, which could exhibit its sound absorption mechanism. Meanwhile, the sound absorption performance of the APH-AM with larger length of the aperture and that with smaller diameter of the aperture were discussed by finite element simulation, which could further show the potential of APH-AM in the low-frequency sound absorption. The proposed APH-AM could improve efficiency and accuracy in adjusting sound absorption performance purposefully, which would promote its practical application in low-frequency noise control.

Development and Optimization of Broadband Acoustic Metamaterial Absorber Based on Parallel-Connection Square Helmholtz Resonators.

An acoustic metamaterial absorber of parallel-connection square Helmholtz resonators is proposed in this study, and its sound absorption coefficients are optimized to reduce the noise for the given conditions in the factory. A two-dimensional equivalent simulation model is built to obtain the initial value of parameters and a three-dimensional finite element model is constructed to simulate the sound absorption performance of the metamaterial cell, which aims to improve the research efficiency. The optimal parameters of metamaterial cells are obtained through the particle swarm optimization algorithm, and its effectiveness and accuracy are validated through preparing the experimental sample using 3D printing and measuring the sound absorption coefficient by the standing wave tube detection. The consistency between the experimental data and simulation data verifies feasibility of the proposed optimization method and usefulness of the developed acoustic metamaterial absorber, and the desired sound absorption performances for given conditions are achieved. The experimental results prove that parallel-connection square Helmholtz resonators can achieve an adjustable frequency spectrum for the low frequency noise control by parameter optimization, which is propitious to promote its application in reducing the noise in the factory.

Acoustic Metamaterials for Low-Frequency Noise Reduction Based on Parallel Connection of Multiple Spiral Chambers.

Acoustic metamaterials based on Helmholtz resonance have perfect sound absorption characteristics with the subwavelength size, but the absorption bandwidth is narrow, which limits the practical applications for noise control with broadband. On the basis of the Fabry-Perot resonance principle, a novel sound absorber of the acoustic metamaterial by parallel connection of the multiple spiral chambers (abbreviated as MSC-AM) is proposed and investigated in this research. Through the theoretical modeling, finite element simulation, sample preparation and experimental validation, the effectiveness and practicability of the MSC-AM are verified. Actual sound absorption coefficients of the MSC-AM in the frequency range of 360-680 Hz (with the bandwidth Δf1 = 320 Hz) are larger than 0.8, which exhibit the extraordinarily low-frequency sound absorption performance. Moreover, actual sound absorption coefficients are above 0.5 in the 350-1600 Hz range (with a bandwidth Δf2 = 1250 Hz), which achieve broadband sound absorption in the low-middle frequency range. According to various actual demands, the structural parameters can be adjusted flexibly to realize the customization of sound absorption bandwidth, which provides a novel way to design and improve acoustic metamaterials to reduce the noise with various frequency bands and has promising prospects of application in low-frequency sound absorption.

Experimental and Numerical Study of Static Behavior of Precast Segmental Hollow Bridge Piers.

To investigate the static performance of precast segmental hollow piers, two precast segmental hollow pier specimens were designed for static loading tests on the top of piers. The finite element model of precast segmental hollow piers was established by the finite element software Abaqus and verified based on the test results. Based on the experimental and finite element models, three optimal design solutions were proposed, and the calculation results of each solution were analyzed. The results show that precast segmental hollow pier mechanical behavior is similar to that of cantilevered bending members. The specimens present brittle damage characteristics after the destruction of the structure at the bottom of the pier pressure edge as the axis of the rigid body rotation. Following the test loading process, the bonding between the segments is good, except for the pier bottom damage surface of the rest of the bonding surface, which has no relative displacement. The calculation results of the finite element model are in good agreement with the test results and can effectively predict the load-displacement response of precast piers. Three optimized design solutions are proposed. The finite element simulation proves all three optimized design solutions show better overall ductility than the original solution and can effectively improve the performance of segmental precast hollow piers.

Optimal Design of Acoustic Metamaterial of Multiple Parallel Hexagonal Helmholtz Resonators by Combination of Finite Element Simulation and Cuckoo Search Algorithm.

To achieve the broadband sound absorption at low frequencies within a limited space, an optimal design of joint simulation method incorporating the finite element simulation and cuckoo search algorithm was proposed. An acoustic metamaterial of multiple parallel hexagonal Helmholtz resonators with sub-wavelength dimensions was designed and optimized in this research. First, the initial geometric parameters of the investigated acoustic metamaterials were confirmed according to the actual noise reduction requirements to reduce the optimization burden and improve the optimization efficiency. Then, the acoustic metamaterial with the various depths of the necks was optimized by the joint simulation method, which combined the finite element simulation and the cuckoo search algorithm. The experimental sample was prepared using the 3D printer according to the obtained optimal parameters. The simulation results and experimental results exhibited excellent consistency. Compared with the derived sound absorption coefficients by theoretical modeling, those achieved in the finite element simulation were closer to the experimental results, which also verified the accuracy of this optimal design method. The results proved that the optimal design method was applicable to the achievement of broadband sound absorption with different low frequency ranges, which provided a novel method for the development and application of acoustic metamaterials.

Adjustable Sound Absorber of Multiple Parallel-Connection Helmholtz Resonators with Tunable Apertures Prepared by Low-Force Stereolithography of Photopolymer Resin.

The variable noise spectrum for many actual application scenarios requires a sound absorber to adapt to this variation. An adjustable sound absorber of multiple parallel-connection Helmholtz resonators with tunable apertures (TA-MPCHRs) is prepared by the low-force stereolithography of photopolymer resin, which aims to improve the applicability of the proposed sound absorber for noise with various frequency ranges. The proposed TA-MPCHR metamaterial contains five metamaterial cells. Each metamaterial cell contains nine single Helmholtz resonators. It is treated as a basic structural unit for an array arrangement. The tunable aperture is realized by utilizing four segments of extendable cylindrical chambers with length l0, which indicates that the length of the aperture l is in the range of [l0, 4l0], and that it is tunable. With a certain group of specific parameters for the proposed TA-MPCHR, the influence of the tunable aperture with a variable length is investigated by acoustic finite element simulation with a two-dimensional rotational symmetric model. For the given noise spectrum of certain actual equipment with four operating modes, the TA-MPCHR sample with a limited total thickness of 40 mm is optimized, which is made of photopolymer resin by the low-force stereolithography, and its actual average sound absorption coefficients for the frequency ranges of 500-800 Hz, 550-900 Hz, 600-1000 Hz and 700-1150 Hz reach 0.9203, 0.9202, 0.9436 and 0.9561, respectively. Relative to common non-adjustable metamaterials, the TA-MPCHR made of photopolymer resin can reduce occupied space and improve absorption efficiency, which is favorable in promoting its practical applications in the noise pollution prevention.