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Light’s orbital angular momentum (OAM) with inherent mode orthogonality has been suggested as a new way to the optical encryption. However, the dependence of annular intensity profiles on the topological charge complicates nanoscale light–matter interactions and hampers the ultra-secure encryption application. In this paper, we demonstrate ultra-secure image encryption by tightly focusing perfect optical vortex (POV) beams with controllable annular intensity profiles and OAM states. A simple scheme composed of single spatial light modulator to implement Fourier transform of an ideal Bessel mode with both amplitude and phase modulations is proposed to generate radius-controllable POV in tightly focused beams. Such focused POV beams with identical intensity profiles but varied local OAM density are applied to disorder-coupled gold nanorod aggregates to selectively excite electromagnetic hot spots for encoding information through photothermal deformation. As such, ultra-secure image encryption in OAM states of POV beams in combination with different polarizations can be achieved. Our results lay the ground for diverse nanophotonic applications harnessing the OAM division of POV beams.

High-order cylindrical vector beams possess flexible spatial polarization and exhibit new effects and phenomena that can expand the functionality and enhance the capability of optical systems. However, building a general analytical model for highly focused beams with different polarization orders remains a challenge. Here, we elaborately develop the vector theory of high-order cylindrical vector beams in a high numerical aperture focusing system and achieve the vectorial diffraction integrals for describing the tight focusing field with the space-variant distribution of polarization orders within the framework of Richards–Wolf diffraction theory. The analytical formulae include the exact three Cartesian components of electric and magnetic distributions in the tightly focused region. Additionally, utilizing the analytical formulae, we can achieve the gradient force, scattering force, and curl-spin force exerted on Rayleigh particles trapped by high-order cylindrical vector beams. These results are crucial for improving the design and engineering of the tightly focused field by modulating the polarization orders of high-order cylindrical vector beams, particularly for applications such as optical tweezers and optical manipulation. This theoretical analysis also extends to the calculation of complicated optical vortex vector fields and the design of diffractive optical elements with high diffraction efficiency and resolution. [ABSTRACT FROM AUTHOR]

This letter fully studies the coloured point cloud quality assessment in augmented reality (AR) environment through subjective test. Firstly, a point cloud dataset, named point cloud quality dataset‐AR, including ten reference point clouds and their 90 distorted versions is presented, which were generated using the reference software of video‐based point cloud compression across various combinations of geometry and texture quantization parameters. Then, the impact of geometry and texture distortions on perceived quality of point clouds in AR environment was discussed in detail. Moreover, the performance of existing objective point cloud quality assessment metrics on the proposed dataset is evaluated. The subjective dataset including the values of mean opinion score were released to public. [ABSTRACT FROM AUTHOR]

To obtain the theoretical basis and reference basis for the selection of low ductility aluminum alloy joining methods, three kinds of joints were obtained using 7075-T6 aluminum alloy sheets for clinching, self-piercing riveting (SPR), and resistance spot welding (RSW) joints, and the single-lap shear tests were performed on the three kinds of joints, and fatigue tests were conducted on the clinched joints and SPR joints. The fatigue fracture of the SPR joint was analyzed using scanning electron microscopy (SEM) and X-ray energy-dispersive spectroscopy (EDS). The results showed that the SPR joint demonstrated the best static performance, followed by the clinched joint and the RSW joint. In the case of the fatigue test, the SPR joint showed better fatigue performance than that of the clinched joint. The fatigue failure of the SPR joint and clinched joint is associated with fretting wear. Fretting wear of the SPR joint is more severe than that of the clinched joint. The debris produced by fretting led to microcracking phenomena in the plate. Under the action of alternating load, the microcracks continued to expand and generate macrocracks, and the joint was broken and finally failed. This fretting wear is the root cause of the failure of the SPR joint. Thus, the SPR joints exhibited the best mechanical properties. [ABSTRACT FROM AUTHOR]

Lightweight aluminum alloys are widely used in automotive structural parts. Clinching (press-joining) is one of the most promising alternatives to welding for joining aluminum alloys, and as the failure of the joint is mainly caused by fatigue, the fatigue properties of the clinched joints directly affect the reliability and safety of the connected specimens. To gain a deeper understanding of this phenomenon, the static mechanical and fatigue properties of Al7075 aluminum alloy single-lap clinched joints were studied using static strength and tensile-tensile fatigue tests. The F–N curves of the joints were fitted using a straight-line and three-parameter power function method. The fractured samples and wear scars were analyzed by scanning electron microscopy and energy-dispersive spectroscopy. The results showed that the neck of the clinched joint and the upper sheet near the joint experienced the highest degree of fatigue fracture, the fretting wear debris consisted mainly of alumina and metallic aluminum, and the fretting wear was of a mode that differed from the two modes identified in the literature that we have dubbed "upper sheet inter-sheet region fretting wear." [ABSTRACT FROM AUTHOR]

The thermal lens (TL) effect induced by femtosecond laser pulses in chromium film is reported. A Fresnel diffraction theory is used to explain the TL effect. The intensity profile of the TL calculated by the theoretical model is in agreement with the experimental results. The contrast ratio of the TL is defined to describe the TL effect, and we find that the maximum contrast ratio of the TL effect is obtained when the probe beam is recorded at a characteristic distance. The dependence of the contrast ratio of the TL on different pump laser power levels and delay times is also investigated. Numerical simulations are also consistent with the experimental results. OCIS codes: 140.6810, 050.1960, 310.6860, 320.2250, 350.6830.

Double femtosecond laser pulses are usually generated by using a Michelson structure. We propose a novel and simple device by using two high-density transmissive gratings for generation of double pulses and conversion between single and double laser pulses by shifting one of the two gratings by a quarter period. The apparatus has the advantages of compact volume, simple structure, and convenience in manipulation. Experimental outputs of the double laser pulses are well verified in experiment, which can be properly explained by numerical simulation with the rigorous coupled-wave theory. This structure provides an interesting approach for generation of double pulses and conversion between single and double laser pulses for practical applications of the femtosecond laser. [c] 2010 Optical Society of America OCIS codes: 320.7080, 050.1950.

We present a femtosecond off-axis digital holography for investigating the dynamic reversible surface change of a metal film induced by femtosecond laser pulses with fluences near the ablation threshold. A reflection Michelson interferometer (RMI) and a transmission Mach--Zehnder interferometer (TMZI) are integrated in the same setup for recording digital holograms. The RMI is used to measure the laser-induced surface deformation of the metal film, while the TMZI is used to analyze the refraction index change of the metal film induced by the femtosecond laser pulses. Experimental results show that both surface modification and refraction index change of chromium metal film can be observed when femtosecond laser pulses are below and above the ablation threshold. Based on the experimental results, the physical processes of the metal induced by femtosecond laser pulses are given qualitatively. [c] 2010 Optical Society of America OCIS codes: 090.1995, 120.5050, 240.6648, 310.0310, 320.7120.

Due to occlusion among views and temporal inconsistency in depth video, spatio-temporal distortion occurs in 3D synthesized video with depth image-based rendering. In this paper, we propose a deep Convolutional Neural Network (CNN)-based synthesized video denoising algorithm to reduce temporal flicker distortion and improve perceptual quality of 3D synthesized video. First, we analyze the spatio-temporal distortion, and model eliminating spatio-temporal distortion as a perceptual video denoising problem. Then, a deep learning-based synthesized video denoising network is proposed, in which a CNN-friendly spatio-temporal loss function is derived from a synthesized video quality metric and integrated with a single image denoising network architecture. Finally, specific schemes, i.e., specific Synthesized Video Denoising Networks (SynVD-Nets), and a general scheme, i.e., General SynVD-Net (GSynVD-Net), based on existing CNN-based denoising models, are developed to handle synthesized video with different distortion levels more effectively. Experimental results show that the proposed SynVD-Net and GSynVD-Net can outperform deep learning-based counterparts and conventional denoising methods, and significantly enhance perceptual quality of 3D synthesized video. [ABSTRACT FROM AUTHOR]

During the last decades, the utilization of osmotic pressure-driven forward osmosis technology for wastewater treatment has drawn great interest, due to its high separation efficiency, low membrane fouling propensity, high water recovery and relatively low energy consumption. This review paper summarizes the implementation of forward osmosis technology for various wastewater treatment including municipal sewage, landfill leachate, oil/gas exploitation wastewater, textile waste-water, mine wastewater, and radioactive wastewater. However, membrane fouling is still a critical issue, which affects water flux stability, membrane life and operating cost. Different membrane fouling types and corresponding fouling mechanisms, including organic fouling, inorganic fouling, biofouling and combined fouling are therefore further discussed. The fouling control strategies including feed pre-treatment, operation condition optimization, membrane selection and modification, membrane cleaning and tailoring the chemistry of draw solution are also reviewed comprehensively. At the end of paper, some recommendations are proposed. [ABSTRACT FROM AUTHOR]

Polymer dielectrics have broad applications in advanced electronics and power systems. However, they suffer from low energy density and poor breakdown performance at high temperatures, limiting their applications in high‐temperature environments. Herein, TiO2@Au@AlOx@Au nanofibers with double coulomb blockade nanolayers are obtained via a physical sputtering strategy to improve the high‐temperature energy storage performance of polyetherimide composites. Experimental studies and finite elemenet phase‐field simulations demonstrate that the double‐layer coulomb blockade effect and micro‐capacitor effect of Au nanoparticles synergistically enhance the breakdown strength and dielectric permittivity of polyetherimide composite at high temperatures. Notably, the composite exhibits ultra‐high discharged energy densities of 11.33 and 9.70 J cm−3 at 150 and 200 °C, respectively, along with high charge–discharge efficiencies of 93.4% and 84%, which far exceed that of the polymer nanocomposites reported so far. Furthermore, the composite exhibits excellent charge–discharge cycling performance (>50000 cycles at 400 MV m−1) and high‐power density (1.16 MW cm−3) at 200 °C, making it an ideal candidate for high‐temperature capacitors. Hopefully, these nanofibers not only serve as excellent nanofillers for high‐temperature energy storage dielectric composites but also holds tremendous potential and inspirational significance for other applications such as electronics, biomedical fields, optics, and catalysis. [ABSTRACT FROM AUTHOR]

Color images always exhibit a high correlation between luma and chroma components. Cross component linear model (CCLM) has been introduced to exploit such correlation for removing redundancy in the on-going video coding standard, i.e., versatile video coding (VVC). To further improve the coding performance, this paper presents a deep learning based intra chroma prediction method, termed as convolutional neural network based chroma prediction (CNNCP). More specifically, the process of chroma prediction is formulated to produce the colorful version from available information input. CNNCP includes two sub-networks for luma down-sampling and chroma prediction, which are jointly optimized to fully exploit spatial and cross component information. In addition, the outputs of CCLM are adopted as chroma initialization for performance enhancement, and the coding distortion level characterized by quantization parameter is fed into the network to release the negative affect from compression artifacts. To further improve the coding performance, the competition is performed between the conventional chroma prediction and CNNCP in terms of rate-distortion cost with a binary flag signalled. The learned CNNCP is incorporated into both video encoder and decoder. Extensive experimental results demonstrate that the proposed scheme can achieve 4.283%, 3.343%, and 4.634% bit rate savings for luma and two chroma components, compared with the VVC test model version 4.0 (VTM 4.0). [ABSTRACT FROM AUTHOR]

Background: Liver fibrosis is pathologically important in the liver cirrhosis progression. The epithelial–mesenchymal transition (EMT) is crucial for organ fibrosis. Macrophage‐stimulating protein (MSP) and its receptor tyrosine kinase, RON, promote cellular EMT. However, their role in liver fibrosis is unclear. Here, we clarify the biological profile, potential mechanisms and therapeutic targets of the MSP‐RON pathway in liver fibrosis. Materials and methods: Macrophage‐stimulating protein expression and its correlation with clinicopathological characteristics of cirrhosis were evaluated in 57 clinical cases and a control group. The effect of MSP‐RON pathway in liver fibrosis was determined in vitro and in vivo. The therapeutic effects of MSP or RON inhibition on liver fibrosis were evaluated in a mouse liver fibrosis model. Results: Macrophage‐stimulating protein is upregulated in liver cirrhosis, which was associated with poor patient prognosis. The MSP‐RON pathway promoted hepatocytes EMT. MSP‐RON‐induced EMT depends on the transforming growth factor beta (TGF‐β) pathway and is regulated by TGF‐β inhibitors. In animal models, an MSP blocking antibody and a small molecule inhibitor of RON, BMS‐777607, both inhibited liver fibrosis progression. Conclusion: Our study revealed that MSP is an important biomarker in liver cirrhosis progression and can be used to prognose patients. The MSP‐RON pathway promotes the EMT of hepatocytes and the progress of fibrosis via a TGF‐β related pathway. Consequently, we identified a new treatment strategy for liver cirrhosis through targeted inhibition of MSP/RON. This research increases the understanding of EMT‐modulated liver fibrosis and provides new insights into biomarkers and therapeutic targets of liver fibrosis. [ABSTRACT FROM AUTHOR]

Mismatches between the precisions of representing the disparity, depth value and rendering position in 3D video systems cause redundancies in depth map representations. In this paper, we propose a highly efficient multiview depth coding scheme based on Depth Histogram Projection (DHP) and Allowable Depth Distortion (ADD) in view synthesis. Firstly, DHP exploits the sparse representation of depth maps generated from stereo matching to reduce the residual error from INTER and INTRA predictions in depth coding. We provide a mathematical foundation for DHP-based lossless depth coding by theoretically analyzing its rate-distortion cost. Then, due to the mismatch between depth value and rendering position, there is a many-to-one mapping relationship between them in view synthesis, which induces the ADD model. Based on this ADD model and DHP, depth coding with lossless view synthesis quality is proposed to further improve the compression performance of depth coding while maintaining the same synthesized video quality. Experimental results reveal that the proposed DHP based depth coding can achieve an average bit rate saving of 20.66% to 19.52% for lossless coding on Multiview High Efficiency Video Coding (MV-HEVC) with different groups of pictures. In addition, our depth coding based on DHP and ADD achieves an average depth bit rate reduction of 46.69%, 34.12% and 28.68% for lossless view synthesis quality when the rendering precision varies from integer, half to quarter pixels, respectively. We obtain similar gains for lossless depth coding on the 3D-HEVC, HEVC Intra coding and JPEG2000 platforms. [ABSTRACT FROM AUTHOR]

Heterojunction light-emitting diodes (LED) based on n-ZnO/CsPbBr3/p-GaN have been fabricated by using pulsed laser deposition (PLD). The effects of the CsPbBr3 interlayer on the electroluminescence (EL) performance of n-ZnO/p-GaN have been systematically studied. It was found that the CsPbBr3 interlayer plays an important role in the emission performance of the heterojunction LED. By adjusting the thickness of CsPbBr3, the emission peaks of the heterojunction LED change from violet to greenish-yellow, indicating that the electroluminescence characters can be tuned by the CsPbBr3 film thickness. Detailed emission mechanisms influenced by the CsPbBr3 film have been investigated using the Anderson band diagram. The results provide a new method for the fabrication of single-chip white LEDs. [ABSTRACT FROM AUTHOR]

MnV2O6 is a promising anode material for lithium ion batteries with high theoretical specific capacity, abundant reserves and inexpensive constituent elements. However, in the process of lithization and de-lithization, the MnV2O6 anode material will form an amorphous phase, leading to collapse of its original layered structure; this greatly decreases its lithium storage capacity and specific capacity and affects its long-term cycle performance. In this study, 2D accordion-like MnV2O6 nanosheets with Co-doping are obtained via a hydrothermal route. The cobalt ions partially replace the positions of the manganese ions, and the emergence of Co3+ ions is inferred to induce the formation of a built-in electric field in the electrode to enhance the electrochemical behaviour of MnV2O6, presenting a high capacity of 1005.9 mA h g−1 after hundreds of cycles. The capacitive contribution to the total capacity is investigated to obtain insight into the kinetic analysis of its electrochemical behaviour. This study sheds light on an effective strategy to obtain excellent electrochemical behavior of MnV2O6-based materials and other transition metal oxides as electrodes for lithium storage. [ABSTRACT FROM AUTHOR]

In this paper, a novel intra prediction method is proposed to improve the video coding performance, in which the generative adversarial network (GAN) is adopted to intelligently remove the spatial redundancy with the inference process. The proposed GAN-based method improves the prediction by exploiting more information and generating more flexible prediction patterns. In particular, the intra prediction is modeled as an inpainting task, which is accomplished with the GAN model to fill in the missing part by conditioning on the available reconstructed pixels. As such, the learned GAN model is incorporated into both video encoder and decoder, and the rate-distortion optimization is performed for the competition between GAN-based intra prediction and traditional angular-based intra prediction to achieve better coding performance. The proposed scheme is implemented into the high-efficiency video coding test model (HM 16.17) and the versatile video coding test model (VTM 1.1). The experimental results show that the proposed algorithm can achieve 6.6%, 7.5%, and 7.5% under HM 16.17 and 6.75%, 7.63%, and 7.65% under VTM 1.1 bit rate savings on average for luma and chroma components in the intra coding scenario. [ABSTRACT FROM AUTHOR]

The latest video compression standard, High Efficiency Video Coding (HEVC), has greatly improved the coding efficiency compared to the predecessor H.264/AVC. However, equipped with the quadtree structure of coding tree unit partition and other sophisticated coding tools, HEVC brings a significant increase in the computational complexity. To address this issue, a coding unit (CU) decision method based on fuzzy support vector machine (SVM) is proposed for rate-distortion-complexity (RDC) optimization, where the process of CU decision is formulated as a cascaded multi-level classification task. The optimal feature set is selected according to a defined misclassification cost and a risk area is introduced for an uncertain classification output. To further improve the RDC performance, different regulation parameters in SVM are adopted and outliers in training samples are eliminated. Additionally, the proposed CU decision method is incorporated into a joint RDC optimization framework, where the width of risk area is adaptively adjusted to allocate flexible computational complexity to different CUs, aiming at minimizing computational complexity under a configurable constraint in terms of RD performance degradation. Experimental results show that the proposed approach can reduce 58.9% and 55.3% computational complexity on average with the values of Bjønteggard delta peak-signal-to-noise ratio as −0.075 dB and −0.085 dB and the values of Bjøntegaard delta bit rate as 2.859% and 2.671% under low delay ${P}$ and random access configurations, respectively, which has outperformed the state-of-the-art fast algorithms based on statistical information and machine learning. [ABSTRACT FROM AUTHOR]

We present a type of generalized circular Dammann gratings (GCDGs) with controllable impulse ring profiles. Different from impulse rings generated by traditional circular Dammann gratings, the intensity profile of impulse rings can be tuned by redesigning the phase structure of GCDGs. Also, the physical picture behind this controllable impulse ring profile is given clearly. As examples, four one-order binary (0, $\pi $ ) GCDGs are designed and fabricated for generation of impulse rings with four different intensity profiles. In addition, GCDGs with continuous-phase profile are also demonstrated for generation of multiple concentric equal-intensity impulse rings with different intensity profiles. This type of impulse rings with tunable intensity profiles will enrich the function of CDGs, and it should be of high interest for its potential applications in various realms, such as structured pumping laser, novel optical manipulation, generation of dark perfect vortices, and optical testing and measurement. [ABSTRACT FROM AUTHOR]

High Efficiency Video Coding (HEVC) improves the compression efficiency at the cost of high computational complexity by using the quad-tree coding unit (CU) structure and variable prediction unit (PU) modes. To minimize the HEVC encoding complexity while maintaining its compression efficiency, a binary and multi-class support vector machine (SVM)-based fast HEVC encoding algorithm is presented in this paper. First, the processes of recursive CU decision and PU selection in HEVC are modeled as hierarchical binary classification and multi-class classification structures. Second, according to the two classification structures, the CU decision and PU selection are optimized by binary and multi-class SVM, i.e., the CU and PU can be predicted directly via classifiers without intensive rate distortion (RD) cost calculation. In particular, to achieve better prediction performance, a learning method is proposed to combine the off-line machine learning (ML) mode and on-line ML mode for classifiers based on a multiple reviewers system. Additionally, the optimal parameters determination scheme is adopted for flexible complexity allocation under a given RD constraint. Experimental results show that the proposed method can achieve 68.3%, 67.3%, and 65.6% time saving on average while the values of Bjøntegaard delta peak signal-to-noise ratio are −0.093dB, −0.091dB, and −0.094dB and the values of Bjøntegaard delta bit rate are 4.191%, 3.842%, and 3.665% under low delay $P$ main, low delay main, and random access configurations, respectively, when compared with the HEVC test model version HM 16.5. Meanwhile, the proposed method outperforms the state-of-the-art fast coding algorithms in terms of complexity reduction and RD performance. [ABSTRACT FROM PUBLISHER]

To improve the coding efficiency and meanwhile reduce the complexity of the depth video encoder in 3D system, we present an efficient depth coding scheme based on the allowable depth distortion (ADD) in view synthesis. Firstly, we analyze the depth distortion in view synthesis and present a new ADD-based Rate Distortion (RD) optimization cost function to improve the mode/reference decision criteria. Then, we present an early mode and reference frame selection algorithm, which skips the unnecessary and complex mode and reference frame when the depth distortion is within the ADD interval. Meanwhile, the coding efficiency is improved by RD optimized mode decision and reference frame selection. The experimental results show that the proposed overall algorithm, which integrates the fast mode decision, reference frame selection and RD optimization, can reduce the depth coding complexity from 32.47 to 72.59, and 55.95 % on average over different test sequences. Meanwhile, the proposed algorithm achieves 1.34 and 1.58 dB average Bjontegaard Delta peak signal-to-noise ratio gain in terms of the view synthesis quality at low and high bit rate, respectively. In terms of the bit rate reduction, it reduces 54.66 and 49.60 % Bjontegaard Delta bit rate on average at low and high bit rate, respectively, while maintaining the same view synthesis image quality. [ABSTRACT FROM AUTHOR]