苏州科技大学机构知识库
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Changlong Guo; Zhenping Xia; Chaochao Li; Hao Chen; Yuanshen Zhang
Laser & Optoelectronics Progress, 2024 61 (12) - ESCI

摘要 : Point cloud denoising is crucial for ensuring the quality of three-dimensional point clouds. However, existing denoising methods are extremely prone to error removal for object point clouds while removing noise points, and the error increases with the improvement of noise recognition accuracy. To address this issue, a point cloud denoising algorithm that incorporates improved radius filtering and local plane fitting is proposed. To achieve effective noise point removal, noise points are divided into far- and near-noise points based on their Euclidean distance from the object point clouds and are successively processed using different denoising strategies. First, the far-noise points are removed using improved radius filtering based on the density characteristics of the point clouds. Next, the near-noise points, which are closely located to the object point clouds and attached to their surfaces, are removed using a geometrical feature assessing the deviation of the point cloud from the local fitting plane. Finally, experiments are conducted on common point cloud datasets and the proposed method is validated by comparing its performance with that of three other advanced methods. The results show that the proposed method outperforms all three methods in all indexes under the same noise level. Our proposed method effectively improves the object point cloud recognition accuracy while achieving higher noise recognition accuracy, with the denoising accuracy reaching 95.9%.

Chaochao Li; Zhenping Xia; Yueyuan Zhang; Tao Huang; Changlong Guo
Laser & Optoelectronics Progress, 2024 61 (12) - ESCI

摘要 : As a strong competitor of the next-generation high-dynamic-range (HDR) display, liquid crystal displays (LCDs) with a minilight-emitting-diode (Mini-LED) backlight are an essential approach for developing new display technologies. LCDs with a Mini-LED backlight inevitably introduce the halo effect because of their structural characteristics, such as local dimming and light leakage. Therefore, to investigate the effect of ambient light on the halo perception of LCDs with a Mini-LED backlight, we propose a fundamental LCD with a Mini-LED backlight simulation model and design a systematic visual perception experiment based on the proposed model. Furthermore, we investigate halo perception under different ambient illuminances, Mini-LED backlight block sizes, and contrast ratios of liquid crystal panels. Additionally, we explore the influence mechanism of ambient light on halo perception based on actual light measurements. The results show that ambient light has a substantial effect on halo perception; ambient light can affect the contrast ratio of the image; and ambient illuminance is negatively correlated with halo perception intensity. Therefore, this study provides a reference for designing and optimizing LCDs with a Mini-LED backlight under different ambient light conditions.

Zixiong Peng; Zhenping Xia; Yueyuan Zhang; Chaochao Li; Yuanshen Zhang
Laser & Optoelectronics Progress, 2024 61 (10) - ESCI

摘要 : Three-dimensional (3D) imaging technology is widely used in augmented, virtual, and mixed realities. Dynamic virtual spatial distortion is an important factor that affects visual comfort. This study analyzes the processes involved in 3D image acquisition, display, and human eye perception to quantify the spatial distortion of virtual space in 3D imaging accurately. This study also simulates different spatial distortions that may occur in the process. The point cloud data of the object in the virtual space before and after distortion are compared and analyzed by first dividing and then aggregating. The quantitative model of static geometric distortion is thus established. The dynamic geometric distortion quantification model is obtained by combining the static model and the object motion attributes. The effectiveness of the proposed method is verified by simulating 10 different degrees of geometric distortion based on six groups of point clouds and comparing the subjective and objective consistencies between the proposed and classical method through subjective evaluation experiments. The results demonstrate that the proposed method has the best index performance in quantifying the geometric distortion of virtual space, and the Pearson's linear correlation coefficient obtained is 0.93, which accurately reflects the geometric distortion perceived by the test subjects. The research will provide a theoretical reference for the research in geometric distortion optimization and visual comfort improvement of 3D displays.

Hang Xu; Yue Xue; Zhenqi Liu; Qing Tang; Tianyi Wang; Xichan Gao
Small science, 2024 4 (4) - ESCI

摘要 : A van der Waals (vdW) heterostructure is formed by combining multiple materials through vdW bonds. It can combine the advantages of electronic, optical, thermal, and magnetic properties of different 2D materials and has the potential to develop into the next generation of high-performance functional devices. Herein, the current research advances of vdW heterostructures are reviewed. First, current fabrication methods and physical structures of vdW heterostructures are summarized. The 2D/nD (n = 0, 1, 2, 3) mixed-dimensional heterostructures are discussed in detail. Second, a new type of vdW heterostructure is introduced based on two-dimensional electron gas with a nanoscale junction interface. Finally, the application prospects of vdW heterostructures in photoelectric and memory devices are further outlined by combing new applications in the neural networks. This review shows that vdW heterostructures have great advantages in high integration, energy harvesting, and logical operations, and it provides directions and suggestions for the future research and application of environmentally friendly, high-performance, and smart functional devices.

Hang Xu; Yue Xue; Zhenqi Liu; Qing Tang; Tianyi Wang; Xichan Gao
Small science, 2024 4 (4) - ESCI
Hui Wang; Jun Wang; Zhaoliang Cao
Laser & Optoelectronics Progress, 2024 61 (8) - ESCI

摘要 : A water contact angle measurement method based on the improved Faster RCNN is proposed to address the issues of low accuracy and poor reproducibility caused by manual intervention in traditional water contact angle measurement processes. First, the Faster RCNN backbone network VGG16 was replaced with ResNet101, and the attention mechanism model convolutional block attention module (CBAM) was added at the end of its residual block to enhance the network's ability to extract features. Second, the feature pyramid network (FPN) was incorporated to fully extract feature information at different scales, and the Focal loss function was introduced to solve the problem of imbalanced positive and negative class samples. Finally, edge detection and corner extraction were performed on the located water droplets, and then the iterative reweighted least squares (IRLS) method was used to fit the elliptical contour to calculate the contact angle angle. The experimental results show that the improved Faster RCNN object detection algorithm improves mean average precision by 10.794% and speed by 11 frame/s over the original algorithm. The average standard deviation of contact angle angle measurements is 0.109°.

Zhi Ye; Yunpeng Liu; Jiang Xu; Nan Xu; Juncai Dong; Haijun Chen
ACS ES&T Water, 2024 4 (4) - ESCI

摘要 : The efficiency and stability of in situ remediation of Cr(VI) contamination in underground water and soil are still challenging. In this study, a green tea (GT) synthesized nano-zerovalent iron (nZVI) nanocomposite supported by diatomite (DE) (nZVI@GT/DE) via tea polyphenols was designed. The synergetic effect of DE support and tea polyphenols wrapping increased the Fe(II) component in nZVI@GT/DE and its transportability. Compared to nZVI@GT/Mont (supported by Mont with sandwich structure), nZVI@GT/DE exhibited a notably higher capacity (>100 mg g–1) for immobilizing Cr(VI) and a more pronounced ability to release iron ions in solution (corrosion parameter: K ≈ 1.046). This was attributed to the combined effect of the unwrapping process of tea polyphenols coverage and the distinctive columnar porous structure of DE, which increased the exposure of α-Fe0 core for enhanced Cr(VI) reduction during their cotransport in the water-saturated soil system. X-ray absorption fine structure and X-ray photoelectron spectroscopy analyses confirmed that nZVI@GT/DE released more Fe(II) ions to reduce Cr(VI) to bidentate binuclear Cr(OH)3 (vs FeOCr2O3) complexes. This study unraveled the molecular mechanism and highlighted the Cr speciation transformation and physiochemical property changes of nZVI@GT/DE during their cotransporting when applied in situ remediation in complex subsurface of Cr(VI)-contaminated groundwater and soil system.

Yaozu Yang; Feixiang Huang; Fengming Xie; Qiang Zhang; Guo Yuan; Yingyuan Hu
Acta Optica Sinica, 2024 44 (8) - EI ESCI

摘要 : ObjectiveTo obtain novel and efficient thermally activated delayed fluorescence (TADF) materials, BPQPXZ and BPQTPA are synthesized using dibenzopyridoquinoxaline (BPQ) as acceptor (A) and triphenylamine (TPA) and phenoxazine (PXZ) as donors (D). The results show that the two materials have typical delayed fluorescence characteristics, a smaller energy gap (ΔEST) between singlet and triplet states, and a larger oscillator strength ( f ). The device based on BPQPXZ combined with a strong acceptor and a strong donor achieves deep-red emission with λEL at 660 nm. However, due to the influence of the energy-gap law, the external quantum efficiency (EQE) is only 1.0%. BPQTPA combined with a strong acceptor and a weak donor has a larger fluorescence quantum yield (82.7%) because of the weaker rigidity of TPA than that of PXZ. As a result, the donor and acceptor of BPQTPA have less distortion, more orbital overlap, and larger f . At the same time, the intramolecular charge transfer effect of BPQTPA is weakened, and the electron-donating ability of TPA is weaker than that of PXZ. BPQTPA exhibits a blue-shifted emission compared with BPQPXZ. Therefore, the device based on BPQTPA exhibits yellow emission with λEL at 555 nm. Compared with BPQPXZ, the turn-on voltage of BPQTPA is reduced to 2.8 V; the maximum current efficiency and power efficiency are increased by 32-fold and 36-fold, respectively, and the EQE is increased by 6-fold to 7.0%.MethodsIn this study, BPQPXZ and BPQTPA materials are synthesized using the Suzuki reaction and Buchwald-Hartwig reaction. The photophysical properties, electrochemical properties, thermal properties, and device performance of the two materials are investigated. Comparative analysis is conducted on the luminescent properties of two materials.Results and DiscussionsThe structures of two materials, BPQPXZ and BPQTPA, are verified by 1H nuclear magnetic resonance (1H NMR) spectroscopy and high-resolution mass spectrometry (HRMS). BPQPXZ exhibits deep-red emission with λPL at 655 nm, and BPQTPA exhibits yellow emission with λPL at 585 nm (Fig. 3). Compared with BPQPXZ, BPQTPA exhibits blue-shifted emission because of weaker electron-donating ability of TPA than PXZ. Similarly, the rigidity of TPA is weaker than that of PXZ, resulting in a greater degree of overlap between the HOMO and LUMO of BPQTPA, a higher oscillator strength, and a larger fluorescence quantum yield (82.7%) for BPQTPA, which is consistent with the density functional theory simulation results (Fig. 2). As shown in the transient PL decay spectra (Fig. 4), the delay component is observed, and such phenomena are typical behaviors of TADF. As shown in the cyclic voltammogram (Fig. 5), the HOMO levels of BPQTPA and BPQPXZ are -5.38 eV and -5.25 eV, respectively. The calculated LUMO levels are -3.00 eV and -3.27 eV for BPQTPA and BPQPXZ, respectively. BPQTPA shows better thermal stability with a higher decomposition temperature (Td, with 5% weight loss) of 492.6 °C than BPQPXZ (Td=439.2 °C). The higher thermal stability of BPQTPA can be ascribed to its better planarity than that of BPQPXZ. These devices based on BPQTPA and BPQPXZ achieve good performance (Fig. 7). The device based on BPQTPA exhibits much higher EQE (7.0%) than the device based on BPQPXZ (EQE is 1.0%), especially.ConclusionsIn this study, BPQTPA and BPQPXZ materials are designed and synthesized using BPQ with a highly rigid conjugated planar structure as an acceptor and TPA and PXZ as donors. The results show that two materials have typical delayed fluorescence characteristics. BPQTPA and BPQPXZ achieve good orbital separation between HOMO and LUMO, as well as a certain degree of orbital overlap, resulting in a smaller ΔEST and a larger oscillator strength. The device based on BPQPXZ combined with a strong acceptor and a strong donor achieves deep-red emission with λEL at 660 nm. However, due to the influence of energy-gap law, non-radiative decay is serious, with an EQE of only 1.0%, as well as low current and power efficiency. The device based on BPQTPA combined with a strong acceptor and a weak donor is less rigid than that based on BPQPXZ, making the degree of donor and acceptor distortion of BPQTPA less than BPQPXZ, and the degree of overlap between HOMO and LUMO orbitals of BPQTPA increases, so oscillator strength of BPQTPA is 2.2 times that of BPQPXZ. As a result, BPQTPA has a higher PLQY (82.7%). Meanwhile, due to the much weaker electron-donating ability of TPA than PXZ, the intramolecular charge transfer effect of BPQTPA is weakened, resulting in a significant blue-shift in both photoluminescence and electroluminescence peaks. The device based on BPQTPA exhibits yellow emission with λEL at 555 nm. Compared with BPQPXZ, the turn-on voltage of the device based on BPQTPA is reduced to 2.8 V, and the current efficiency and power efficiency are significantly improved by 32-fold and 36-fold, respectively. The EQE is increased by 6-fold to 7.0%. In particular, we investigate the effects of reasonable combinations of donor and acceptor on the photophysical and electroluminescent properties of materials through structure-activity relationships, and the study is of certain reference significance for the research on long-wavelength TADF materials.

Cheng Yang; Wen Jie Du; Ru-Li He; Yi-Rong Hu; Houqi Liu; Tianyin Huang
ACS ES&T Water, 2024 4 (3) - ESCI

摘要 : The fugitive emissions of greenhouse gases, primarily methane (CH4) and nitrous oxide (N2O), from water environments have aroused global concern. However, there are currently limited information about national-scale data of CH4 and N2O emissions from inland waters, such as lakes, rivers, and reservoirs, particularly in developing countries. This study employed machine learning techniques, based on the literature data and national water quality monitoring data, to reveal the CH4 and N2O emission patterns of China's inland waters at the third-level basin and daily resolution. Our results show significant seasonal variations in CH4 emissions, which were influenced by total nitrogen and chemical oxygen demand concentrations. Northern watersheds were identified as hotspots of CH4 emissions, with 57% higher CH4 flux than the other watersheds. In contrast, N2O had a relatively lower contribution to total carbon emissions and showed smaller temporal and spatial variations. The estimated total emissions of CH4 and N2O in China's inland waters in 2021 amounted to 80.22 Tg of carbon dioxide equivalent, accounting for 9–11% of China's terrestrial carbon sinks. This research provides valuable insights to guide the counting and control of greenhouse gas emissions from environmental water bodies.

Yi Bai; Zhenping Xia; Bowen Zhang; Zixiong Peng; Yuanshen Zhang
Laser & Optoelectronics Progress, 2024 61 (4) - ESCI

摘要 : Visually induced motion sickness has become a serious problem for users of virtual reality technology. Users immersed in a virtual reality environment generally suffer from dizziness, vomiting, and other symptoms. The distortion in stereoscopic image acquisition leads to virtual space distortion in human perception, which may be an important factor inducing and enhancing visually induced motion sickness. To study the effect of the distortion of stereoscopic video acquisition on visually induced motion sickness, a virtual spatial distortion model is constructed based on the theory of stereoscopic video acquisition. In addition, different levels of stereoscopic spatially distorted videos are obtained from lenses with three focal length parameters. Visual perception experiments were conducted to objectively and subjectively evaluate visually induced motion sickness under different spatial aberrations. The results show that when the angle of view of the acquired stereoscopic video does not match the stereoscopic visual angle of human eyes, the distortion of the video significantly affects the visually induced motion sickness, and the distortion of the stereoscopic video acquisition results in a more intense visually induced motion sickness. This paper presents a novel and systematic method to experimentally verify that distortions in virtual space caused by the mismatch between acquisition and perception parameters enhance visually induced motion sickness. The findings of this study can help put forward practical mitigation methods.