Search

Successive images of a scene are captured and then further processed to achieve the moving object tracking. However, due to modulation rate limitations of the spatial light modulator in single-pixel imaging (SPI) system, the imaging frame rate cannot meet the high-resolution and real-time requirements for object tracking. In this paper, we demonstrate a fast object tracking technique based on SPI with an ultra-low sampling rate that is independent of imaging. We construct modulation information that satisfies the projection conditions and can transform 2D images into 1D projection curves. The 1D projection curves, which provide the location information of the moving object, can be obtained with high resolution in real-time, and then the tracking of the moving object is realized. A background subtraction technique for tracking moving objects that removes static components from a scene is also proposed. The proposed technique is verified by computational simulations and laboratory experiments. In the laboratory experiments, we demonstrate that the proposed method can be used to track moving objects with less than 0.2% of the measurements established by the Nyquist criterion, and it presents 256 × 256 pixels at ∼ 177 fps. The reported technique accelerates the tracking speed of SPI and provides an efficient strategy for remote sensing and biomedical applications.

In previous studies, numerous dysregulated lncRNAs were identified using RNA-sequencing. Lung cancer is the most common malignant tumour worldwide and the second leading cause in cancer. The aim of this study is to investigate the function and mechanism of lincRNA00858 in the lung cancer. RT-PCR was used to detect the expression of lincRNA00858. Proliferation, invasion, and epithelial-mesenchymal transition (EMT) were examined by CCK8, transwell assay and western blot to evaluate the function of linc00858. Dual-luciferase reporter assay was used to identified the potential target of linc00858. Over-expression of linc00858 significantly promoted cell proliferation, invasion. We also found that linc00858 facilitated the EMT process. Dual-luciferase reporter assay revealed that linc00858 can bind with miR-3182 directly. Linc00858 can negatively regulate the expression of miR-3182. Further experiments demonstrated that MMP2 was the direct target of miR-3182. Rescue experiments revealed that linc00858 functioned through miR-3182/MMP2 axis. Taken together, we verified the role of an unknown linc00858 in lung cancer and provided its mechanism. Mechanistically, linc00858 acted as a competitive endogenous RNA to sponged miR-3182 and regulate MMP2 in lung cancer. Our study provided new clues for understanding the mechanism of lung cancer.

A new severe plastic deformation method, viz. integrated dual-directional extrusion and spiral deformation, was adopted to process AZ31 Mg alloy and found to be very effective for refining the grains and softening the texture. We also investigated how twinning in AZ31 alloy affected the dynamic recrystallization (DRX) during hot extrusion, revealing that multiple twins can offer increased nucleation sites and enough energy to trigger DRX. Moreover, even after dual-directional extrusion and spiral deformation, a misorientation angle of ~ 86° remained between the primary tension twin and matrix or ~ 60° between the secondary tension twin and primary twin, being induced by {10–12} tension twin variants (primary and secondary) and resulting in a dispersed misorientation angle distribution. Nucleation of DRX occurred at the tip of preexisting twins, although primary and secondary tension twins can also act as nucleation sites for DRX.

A new extrusion technique, integrated dual-directional extrusion and spiral deformation(DDES), is proposed and successfully applied to AZ31 Mg alloys with no cracks present in the alloys. Combining finite-element analytic, optical microscopy, and X-ray diffraction techniques, it is found that the DDES process may cause cumulative strains of 1.88 in Mg alloy billet. The average grain size of the alloys can be refined from 300 μm to 3.5 μm at a temperature of 573 K, and the basal texture is also dramatically weakened from 53.6 to 6.52. These improvements are mainly attributed to dynamic recrystallization induced by heavily accumulated strain at the spiral region. Further compressive tests are carried out on processed AZ31 Mg alloys, and the superior compressive strength and fracture strain can attain 395 MPa and 30.6 %, respectively, rendering this new deformation technique into a promising approach for further governing properties of Mg-based alloys.

The practical application of sodium-ion hybrid capacitors is limited by their low energy densities resulted from the kinetics mismatch between cathodes and anodes, and the fire safety related to the flammable electrolyte-separator system. Hence, we report a rational design of metal–organic frameworks (MOFs, UiO-66) modified PVDF-HFP separator. High tensile strength and dimensional thermal stability of the separator reduce the risk of electrode short circuit caused by the separator deformation. MCC test demonstrates a reduction of 75% in peak heat release rate (pHRR), indicating an enhanced fire-resistant property of the separator. This is due to the transformation of UiO-66 into ZrO2 accompanied by the consumption of oxygen and the formation of the barrier char that suppresses further heat release. Quasi-solid-state electrolyte prepared based on this separator presents an enhanced ionic conductivity of 2.44 mS cm−1 and Na-ion transference number of 0.55, which are related to the high porosity (>70%) and electrolyte uptake (~320%) of the separator. Moreover, the open metal sites of UiO-66 can capture PF6–and consequently liberate the Na+ for faster migration, thus reducing the kinetics mismatch between cathodes and anodes. Such multifunctional separator enables the quasi-solid-state Na-ion hybrid capacitor to achieve high energy density (182 Wh kg−1 @31 W kg−1) and power density (5280 W kg−1 @22 Wh kg−1), as well as excellent cyclic stability (10,000 cycles @1000 mA g−1).

The microstructure and texture evolution of an AZ31 magnesium rolled sheet during quasi-static compression at strain rates of 10 − 3 s − 1 has been investigated by in situ electron backscattered diffraction. The influence of the initial and pre-deformed texture on the predominant deformation mechanisms during compression has been examined. It has been found that extensive grain reorientation due to {10 − 12} tensile twinning appeared when compressed along transverse direction. Tensile twin variants were observed under this loading condition, and different variants will cause an effect to the following deformation. Several twinning modes occurred with continuative loading along rolling direction.

Micropillar compression technique was employed to study the microscale deformation mechanisms of basal slip, twinning and non-basal slips at selected grains in a Mg-2 wt.% Y alloy. The results suggest a critical resolved shear stress (τCRSS) for basal slip 12.5 ± 1.7 MPa, and for twin nucleation and twin growth 38.5 ± 1.2 MPa and 33.8 ± 0.7 MPa, respectively. The higher values compared to those in pure Mg suggests a more balanced deformation in Mg alloy with Y addition. The activation of dislocations in the twinned orientation is highlighted, which leads to strong work hardening in twinned favorable orientation [ 10 1 ‾ 0 ] . In addition, at prismatic-slip favorable orientation [ 11 2 ‾ 0 ] , a twinning-to-prismatic slip transition was observed when elevating temperature from 25 °C to 100 °C and 250 °C. Specially at 250 °C, twinning was completely prohibited, and pure prismatic slip was triggered. The measured τCRSS for prismatic slip at 250 °C was 39.7 ± 0.3 MPa, much higher than that for pure Mg at the same temperature. Finally, at pyramidal-slip favorable orientation [ 0001 ] , an abnormal strengthening was observed at 100 °C and 250 °C due to activation of pyramidal slips. Decompositions of dislocations and Y segregation at stacking faults are the main mechanisms leading to the high-temperature strengthening in Mg–Y alloy.

In AZ31 magnesium alloy, {10–12} twin pair generated at grain boundary is easy to be observed. In current study, we trace the process of twins impacting grain boundaries and stimulating the nucleation of new twins in neighbouring grains by in situ electron backscatter diffraction (EBSD) technique. Multiple twin variants (caused by twin pair) inside one grain is found in EBSD map, which is considered as the cause of strain hardening for it significantly retard the rate of propagation and growth of twinning during subsequent deformation.

Electron backscattered diffraction serial image analyses on AZ31 magnesium alloy compressed along RD at different strain levels revealed that twin–twin interactions are found to correlate with mechanical hardening. Four typical twin–twin structures are investigated: (1) Parallel twins with single variant; (2) Interacting twins with single variant; (3) Parallel twins with double variants; (4) Interacting twins with double variants. We studied twin–twin interactions by combining experimental observations and Schmid factor analysis. Due to twins intersecting with each other, the limited growth rate of twins was observed in EBSD maps. The intersection between different twin variant pairs was found to retard the twin growth and promote the nucleation of new twins near intersection region. Besides, “Apparent crossing” twin structure is a limiting case, in which the twin is crossed by a couple of twins, and the interaction region grow slowly. Twin–twin boundary migration is also observed during deformation in this paper, which is considered as an important cause to prohibit twins for further propagate and growth. All these features can be related to twinning-induced hardening.

The strengthening mechanisms of hot-extruded AZ31 magnesium alloy by { 10 1 ¯ 2 } extension twinning lamellas during multi-pass compression are investigated in present study. The numbers of { 10 1 ¯ 2 } twinning lamellas increased dramatically with the ED-TD orthogonal compression. Grain refinement induced by { 10 1 ¯ 2 } twinning lamellas greatly improved the mechanical properties of reloading along ED and TD direction. In addition, the primary { 10 1 ¯ 2 } twinning lamella can be an effective way to strengthen material via twin-twin interaction during secondary twin growing and propagating.

A novel finding of this study is that localised de-twining caused by shear banding induced by uniaxial compression deformation was first found through in situ EBSD observation. The twinning deformation process showed in this paper consists of the following three steps: twinning, de-twinning and re-twinning, which needs more energy and larger load than the process of twin growth and coalescence and complete consumption. It is believed that localised de-twining deformation mechanism is one of the strengthening mechanisms in magnesium alloy. More interestingly, twinning and de-twinning deformation operate simultaneously in a single twinning system, which was not in good agreement with the prediction of previous reports [1] . It is the first time that such unusual deformation mechanism has been found in experimental results. According to the results and combining with theoretical analysis, uncertain local stress states in individual grains is the cause of unusual experimental phenomena. The back stress induced in a twin by the surrounding matrix plays an important role in localised de-twining during uniaxial compression.

Continuous { 10 1 2 } twin bands across neighboring grains was observed in a hot rolled AZ31 during the interrupted compression along the rolling direction. The variant selection in paired twins was studied by Schmid factor (SF) and geometric misorientation relationship. The results show that most mated twins possess high rank Schmid factors (SFs), however, they does not share the same twin variant. Furthermore, EBSD analysis indicates that the formation of paired twins is correlated with the orientation relationship between adjacent grains. Based on these observation and analysis, the mechanism of “sequential twinning” nucleation and synergetic growth during deformation are proposed. Above all, this twinning behavior is capable of transmitting the localized shear and releasing stress at the former twin-termination interfaces, which plays an important role in accommodating plastic strain and mediating multiple grains' deformation

The twinning and slipping modes of a rolled AZ31 magnesium alloy sheet were investigated through in situ compressive tests. A method based on scanning electron microscopy and electron backscattered diffraction measurements was used to identify activated twinning and slip systems. {10-12} tensile twins were present, but only occasionally. Contraction twins were not observed. Post deformation examination revealed the dominance of pyramidal slip.

We report synthesis of hierarchical SnO2 nanostructures by a facile hydrothermal method. Extensive structural characterizations demonstrate that the well-defined hierarchical nanostructures are composed of numerous one-dimensional nanorods, the diameter and density of which can be precisely tailored by adjusting the dosage of NaOH. Interestingly, with more NaOH added, smaller and denser nanorods are formed, which is consistent with the assumption. We proposed that the nucleation process was facilitated in such case leading to all-direction rapider growth. Moreover, the nucleation process could be started by the decomposition of preformed ZnSn(OH)6 induced by alkali etching. Based on the comparative experiments, a possible growth mechanism for hierarchical SnO2 nanostructures has been proposed and discussed in detail. The gas sensing properties of the as-prepared hierarchical SnO2 nanostructures were all tested. It was found that the S3 sample which assembled with smallest and densest nanorods showed the excellent sensitivities toward ethanol.

Multispectral imaging can acquire images of a scene in multiple spectral bands and has been widely applied in many fields, such as satellite remote sensing and geological exploration. Traditional multispectral imaging employs dispersive optical devices or narrowband filters to separate different wavelengths of light and then uses an array detector or many single-pixel detectors to retrieve them separately. These techniques suffer from large data volumes and low efficiency. In this paper, a spectral encoded strategy is proposed to realize multispectral imaging with computational ghost imaging technology. The projected illumination patterns are produced by means of deterministic orthogonal Hadamard basis patterns fused with random spectral encoded matrices, which represent different spectral information. The evolutionary compressive sensing technique is employed to restore the fused multispectral image of the color object of interest, and then a compressive sensing algorithm is applied to restore the spectral channel images. The validity of the technique is verified by a numerical simulation and an experiment. The proposed method allows a multispectral image simultaneously by only one single-pixel detector, which simplifies the structure of the spectral imaging setup and reduces the amount of data acquired and reconstruction time, and thus improving multispectral imaging efficiency.

Time-of-flight (TOF) three-dimensional (3D) imaging is an effective means for remote sensing and target recognition. Fourier ghost imaging (GI) acquires the Fourier spectrum first, then applies an inverse Fourier transform (IFT) to retrieve the image of interest. The Fourier spectrum can be artificially processed when needed. The Fourier spectrum of some partially transmissive occluders is generally concentrated in high-frequency regions. These occluders can be removed by applying an IFT using the low-frequency spectrum coverage. This strategy is innovative in TOF 3D GI. In a TOF 3D GI system with DMDs, the high repetition rate and short-pulse laser is generally employed, which is mismatched with the lower modulation frequency of grayscale patterns. The grayscale Fourier patterns are decomposed into binary patterns. The detected intensities corresponding to the binary patterns are multiplied by the corresponding weighted coefficients, and are summed to form the Fourier spectrum slices at different distances. Then, an IFT is applied to retrieve the image cubes, furtherly to obtain the depth maps with the image cubes. Two 3D experiments are carried out to evaluate the proposed technique. The results indicate the reflectivity and depth maps can reveal the information of the 3D objects under 25 % spectrum coverage. From an imaging experiment through a partially transmissive occluder, we we find the reflectivity and the depth map obtained by the low-frequency Fourier spectral coverage are significantly better than those obtained reconstructions with complete spectral coverage. These preliminary results indicate TOF 3D Fourier GI has potential advantages in the removal of netting.

Single-pixel imaging has the ability to generate images at nonvisible wavelengths and under low light conditions and thus has received increasing attention in recent years. Fourier single-pixel imaging (FSI) utilizes deterministic basis patterns for illumination to greatly improve the quality of image reconstruction. However, the original FSI based on grayscale Fourier basis illumination patterns is limited by the imaging speed as the digital micro-mirror devices (DMD) used to generate grayscale patterns operate at a low refresh rate. In this paper, a new approach is proposed to increase the imaging speed of DMD-based FSI without reducing the imaging spatial resolution. In this strategy, the grayscale Fourier basis patterns are split into a pair of grayscale patterns based on positive/negative pixel values, which are then decomposed into a cluster of binary basis patterns based on the principle of decimalization to binary. These binary patterns are used to illuminate the imaged object. The resulting detected light intensities multiply the corresponding weighted decomposed coefficients and are summed, and the results can be used to generate the Fourier spectrum for the imaged object. Finally, an inverse Fourier transform is applied to the Fourier spectrum to obtain the object image. The proposed technique is verified by a computational simulation and laboratory experiments. Both static and dynamic imaging experiments are carried out to demonstrate the proposed strategy. 128 × 128 pixels dynamic scenes at a speed of ~9 frames-per-second are captured under 22 KHz projection rate using a DMD. The reported technique accelerates the imaging speed for DMD-based FSI and provides an alternative approach to improve FSI efficiency.

In this paper rolled AZ31 magnesium alloy was deformed by interrupted in situ compressive tests. Compressive and re-compressive tests were conducted along rolling direction (RD). It is discovered that the yield strength of re-compression is enhanced due to grain refinement by {10–12} tensile twins. Twinning activation and evolution are evidenced by electron backscatter diffraction. Correlations with grain orientation and boundary misorientation are observed in the region of twins that arise at grain boundaries. The distributions of grain boundary misorientation associated with twin nucleation are mapped. It is found that nucleation of twin is mainly controlled by the initial texture, and is more easy at low misorientation grain boundaries. The growth of twins depend on two modes: the thickening of the existing twin lamellae and new twins is nucleated at grain boundary. With increasing compressive strain, the growth and coalescence of twins eventually encompassed the whole grain. Meanwhile, the basal texture is weaker after compression due to the propagation and coalescence of tensile twins.

Computational ghost imaging is a robust and compact system that has drawn wide attentions over the last two decades. Multispectral imaging possesses spatial and spectral resolving abilities, is very useful for surveying scenes and extracting detailed information. Existing multispectral imagers mostly utilize narrow band filters or dispersive optical devices to separate lights of different wavelengths, and then use multiple bucket detectors or an array detector to record them separately. Here, we propose a novel multispectral ghost imaging method that uses one single bucket detector with multiplexed illumination to produce colored image. The multiplexed illumination patterns are produced by three binary encoded matrices (corresponding to red, green, blue colored information, respectively) and random patterns. The results of simulation and experiment have verified that our method can be effective to recover the colored object. Our method has two major advantages: one is that the binary encoded matrices as cipher keys can protect the security of private contents; the other is that multispectral images are produced simultaneously by one single-pixel detector, which significantly reduces the amount of the data acquisition.