Nanometrology guarantees the dimensional accuracy in nanomanufacturing. As integrated-circuit features shrink progressively, the conventional laser-wavelength traceability system becomes highly susceptible to ambient disturbances and fails to meet in situ production requirements. Referencing a quantized optical-lattice constant, a flattened traceability chain provides higher throughput and enhanced environmental robustness by reducing the number of calibration transfer steps. Its cornerstone is the self-traceable grating. The grating’s pitch is directly traceable to the 7S 3 →7P 4 0 transition frequency of chromium (Cr) atoms, which provides picometer accuracy. However, this accuracy is vulnerable to thermal expansion. We developed a thermo-mechanical coupling model to quantify temperature effects and analyze the pitch expansion. This model was validated by finite element simulation (FES). The analysis reveals a cooperative mechanism for stress relief. This mechanism involves interfacial constraints caused by the thermal expansion coefficient (CTE) mismatch between the substrate and the atomic layer. These constraints work in concert with a buffer layer to relieve stress. Within (20 ± 5) °C, the pitch expansion of a 212.78 nm Cr grating decreases from 0.5 to 0.04 pm °C −1 when silicon substrate is replaced by zero expansion glass. This represents an order-of-magnitude improvement. Pitch expansion scales linearly with buffer layer thickness, albeit with opposite slopes for the two substrates. The proposed model and optimization rules furnish theoretical and engineering guidance for boosting nanometrological precision, and fortifying traceability reliability.

Infrared thermography non-destructive testing technology has been widely used in the defect detection of composite structures due to its advantages, including non-contact operation, rapidity, low cost, and high precision. In this study, a laser-line scanning system combined with an infrared thermography was developed, along with a corresponding dynamic sequence image reconstruction method, enabling rapid localization of surface damages. Then, high-precision quantitative characterization of defect morphology in reconstructed images was achieved by integrating an edge gradient detection algorithm. The reconstruction method was validated through finite element simulations and experimental studies. The results demonstrated that the laser-line scanning thermography effectively enables both rapid localization of surface damages and precise quantitative characterization of their morphology. Experimental measurements of ceramic materials indicate that the relative error in detecting crack width is about 6% when the crack is perpendicular to the scanning direction, and the relative error gradually increases when the angle between the crack and the scanning direction decreases. Additionally, an alumina ceramic plate with micrometer-width cracks is inspected by the continuous laser-line scanning thermography. The morphology detection results are completely consistent with the actual morphology. However, limited by the spatial resolution of the thermal imager in the experiment, the quantitative identification of the crack width cannot be carried out. Finally, the proposed method is also effective for detecting surface damage of wrinkles in ceramic matrix composites. It can localize damage and quantify its geometric features with an average relative error of less than 3%, providing a new approach for health monitoring of large-scale ceramic matrix composite structures.

Carbon-based materials hold significant potential for electromagnetic absorption applications, however, the development of effective discrete dual-band absorbers remains a formidable challenge. In this study, we synthesized BaTiO3@reduced graphene oxide (BTO@rGO) composite aerogel via ascorbic acid-assisted thermal reduction, enhanced by a freeze-thaw treatment. This treatment induces a bimodal mesoporous structure, with pore size centered at 2.2 nm and 3.9 nm, which significantly boosts the aerogel's specific surface area of 15.95 m2 g-1 . Additionally, the freeze-thaw process enriches the rGO with defect dipoles and reduces the Ba2 + content on the surface sites. These structural and compositional features synergistically contribute to the composite's discrete dual-band absorption characteristic. Specifically, the composite achieves minimum reflection loss values of -13.8 dB in the C-band (4.7-5.7 GHz) and -20.7 dB in the Ku-band (15.4-17.6 GHz) at a thickness of 5.0 mm, which aligns well with the quarter-wavelength theory. This innovative structural design strategy, which transforms single-frequency absorbers into dual-frequency absorbers, offers a novel and effective approach for developing advanced dual-frequency absorbing materials.

Digital optical phase conjugation (DOPC) emerges as a promising technique for controllable optical delivery in strongly scattering media. Notably, due to the long-standing challenges in accurate alignment of the wave-front sensor and spatial light modulator (SLM), conventional DOPC systems heavily rely on digital calibration for misalignments between these two devices, which will significantly increase the pixel crosstalk of the SLM and thus degrade the performance of DOPC systems. To circumvent this digital calibration for mitigation of the pixel crosstalk, here we propose and demonstrate a real-space alignment scheme for DOPC systems based on single-pixel imaging, which enables precise alignment of the SLM and wave-front sensor: (i) with off-plane alignment precision of submillimeter and milliradian for axial and angular positions, respectively, and (ii) with in-plane pixel match at subpixel resolution. With additional efforts on fidelity optimization of optical phase-conjugation, deformations on the phase-conjugated wave front can almost be removed and the DOPC system would exhibit ultrahigh performance, with peak-to-background ratio (PBR) approaching the theoretical limit (more than 90%) in the time-reversed optical refocusing test. It can be anticipated that all DOPC-based applications will tremendously benefit from this near-theoretical-limit performance of optical phase conjugation for improved capacity and practical utility.

Exploring interfacial engineering in metal oxide/reduced graphene oxide composite becomes a hotspot in the field of electromagnetic wave (EMW) absorption. In this work, three-dimensional (3D) porous ZnFe2O4/ reduced graphene oxide (ZFO/rGO) composite aerogel was synthesized in situ by a hydrothermal reduction method combined with freeze-drying technique. The results reveal that dispersed ZFO nanoparticles (NPs) are bonded to defect-rich 3D conductive rGO skeleton in a bridging mode with Fe-O-C, resulting in en-hanced conduction loss. Consequently, the defect-rich ZFO/rGO composite aerogel exhibits an outstanding EMW absorbing properties: a minimum reflection loss (RLmin) value of - 29.12 dB and an effective ab-sorption bandwidth (EAB with RL less than -10 dB) of 3.57 GHz at an ultra-thin matching thickness of 1.51 mm. This work provides a new strategy for constructing defect-rich graphene-based composite aerogel as an efficient EMW absorbing materials.(c) 2023 Elsevier B.V. All rights reserved.

Recently, non-magnetic carbon-based composite has been regarded as one of the most promising electromagnetic wave absorbing (EMWA) materials. How to realize high EMWA performances at ultra-thin matching thickness is a hot research topic. In this study, a strategy to construct three-dimensional (3D) porous BaTiO3@reduced graphene oxide (BTO@rGO) composite aerogel was performed by successively hydrothermal process, chemical reduction and freeze-drying. The results show that defect-rich BTO nanoparticles are dispersedly immobilized into 3D conductive rGO framework by a form of Ba2+ bonding to rGO, enhancing conduction loss and dipole polarization, which contributes to enhanced EMWA performance. As a result, a minimum reflection loss of-50.49 dB with a matching thickness of only 1.46 mm, along with an effective absorption bandwidth of 3.74 GHz (13.07 GHz-16.81 GHz) with a matching thickness of only 1.39 mm, is achieved for 3D porous BTO@rGO composite aerogel. Therefore, this study paves a way for designing and preparing excellent non-magnetic EMWA materials at ultra-thin matching thickness.

Owing to inherent signal amplification, solution-gated transistor biosensor (SGTB) features high sensitivity. Herein, an SGTB based on polycrystalline SnO2 thin film (PSTF) was fabricated, which was obtained by thermal oxidizing of Sn layer. In order to realize high sensitivity and low operating voltage of SGTB, the field-effect mobility ( $\mu _{\text {FE}}$ ) and electrical conductivity of PSTF can be tuned by changing the oxidation temperature and related grain size. Without doping, a high $\mu _{\text {FE}}$ (418.8 cm2/ $\text{V}\cdot \text{s}$ ) and a moderate conductivity ( $\sim $ 3.5 S/cm) of PSTF were realized with an optimum grain size of $\sim $ 23 nm. The L-cysteine (L-Cys) modified SGTB was applied to detect Hg $^{{2}+}$ in water with a low detection limit (4 nM), a wide linear range (4 nM– $7.4 \mu \text{M}$ ), a high sensitivity (0.46 lg $\mu \text{A}$ /lg $\mu \text{M}$ ), as well as a low operating voltage (0.5 V). The detection limit can meet the requirement of WHO for drinking water (5 nM).

Raman spectrum and electron back scattered diffraction (EBSD) were employed to study the resolution and repeatability of stress measurement at Si (001) and Si (111) nanoindentations. The results revealed that anisotropic stress distributions were generated around Si (001) and Si (111) nanoindentations. Both Raman and EBSD had good stress resolution when they were used to measure residual stress on monocrystalline silicon. The stress resolutions of Raman on Si (001) and Si (111) were 0.43 MPa and 3.64 MPa, respectively. The stress measurement repeatability of Raman on Si (001) and Si (111) were respectively 1.69 MPa and 32.58 MPa, which was attributed to the smaller compliance tensor part of Si (001) stress calculation equation. The stress resolutions of EBSD on Si (001) and Si (111) were 0.13 MPa and 0.22 MPa, respectively. The stress measurement repeatability of EBSD on Si (001) and Si (111) were respectively 39.22 MPa and 19.15 MPa.

Strain states, microstructures and dislocations at the crack tips of Si (001) and Si (111) were studied by employing Electron Back-Scattered Diffraction, Transmission Electron Microscope, Crosscourt software and Geometric Phase Analysis. The evolutionary mechanisms of microstructures in monocrystalline silicon were explored based on experimental results and classical fracture mechanics theories. The results revealed that the strain values at both sides of Si (001) crack were different among the six strain components. The strain distribution in the crack region was anisotropic. There were strain concentration zones at the crack tips of Si (001) and Si (111). The further crack propagation was inhibited by strain concentration zones. Many dislocations generated at the crack tips revealed that plastic deformation had happened. Dislocation generation was the root cause of plastic deformation and strain concentration. The initiation and movement of dislocations, and the nucleation and propagation of cracks were evolutionary mechanisms of two nonlinear microstructures, which were coexisting and competing and were the quasi-cleavage cracking mechanisms of cracks in silicon materials.

探究了基于不同原理(变温X射线衍射法、热分析法和光功率分析法)的相变温度的测量方法,并从测量机理上对测温方式进行了分析,最后讨论了不同测量方法的优劣及影响这些测温方法测量精度的因素.有助于揭示薄膜材料相变过程中物理化学性质的变化,为薄膜器件组装过程中的稳定性和质量可控性提供技术支撑.

As 3rd generation semiconductor, GaN material is promising for biosensor application, owing to its excellent chemical stability and high carrier mobility. Herein, GaN porous-layer (GNP) was self-assembly grown on GaN-coated sapphire substrate without doping by using simple low-temperature (LT) growth. The GNP with a pore density as high as similar to 2.1 x 10(3) mu m(-2) can be realized by optimizing the growth temperature (620 degrees C) and layer thickness (22.4 nm), and its normalized conductivity can be tuned by simply changing the thickness. The optimized GNP was applied to chemiresistive detection of Cu2+ with a limit of detection (LOD) as low as 8 fM, a fast response speed of 1.5 min, a wide linear range (8 fM similar to 8 nM) and good repeatability. The LOD was improved 1.25 similar to 10(6) fold compared with that of previously reported biosensor. The GNP biosensor features high sensitivity, simple structure, integratability, and low-cost. To our knowledge, it is the first time that GaN material was used for chemiresistive biosensor.

正确引导共享单车用户规范停车,是政府管理的重要举措.为此提出了利用聚类的原理、基于K均值的共享单车入栏检测算法.首先模拟产生服从高斯分布的随机单车定位数据;其次对定位数据进行聚类分组,不断迭代向均值移动确定每簇的中心点;最后将数据量最多的簇中心点作为单车的停放位置,对其进行入栏检测分析.用实际测得的单车定位数据验证入栏检测准确率,结果表明,在符合政府管理要求的条件下可准确检测单车是否入栏,正确率高达80％～100％,具有较好的实用价值.

Traditional Fourier ptychographic microscopy (FPM) requires the acquisition of multiple images, which limits the acquisition speed and increases storage requirements. Here, we present a compressed sampling method for FPM (CSFPM), wherein we randomly switch on a certain number of the source LEDs each time to collect compressed data and use it to recover an FPM low-resolution image set. Subsequently, we utilize a general FPM recovery algorithm to reconstruct a high-resolution image. We conduct simulations and experiments to validate the CSFPM feasibility and acquisition efficiency. Our results demonstrate that CSFPM reduces the acquisition-data amount by 49.59% and acquisition-time by 84.63% relative to traditional FPM.

Smart electricity meters are the data bases of monitoring, auditing, counting and analyzing of energy. The verification qualification rate of every single meter can be 99.99% with the fast development of electricity technology, but the risk of error drift still exists in using process. In this article we analyzed the evaluation method of metrological error of smart meters and evaluated the integral metrological level of a smart electricity meters.

As a high-resolution, non-destructive internal structure three-dimensional imaging technology, digital holographic microscopy tomography can provide advanced and safe detection technologies and research tools for the development of high-tech such as life sciences, clinical medicine, and new materials. In order to reduce the reconstruction time and improve the quality of reconstruction, the compressive sensing theory is applied to holographic imaging. Compressive holography technology can not only achieve the tomographic reconstruction of objects from a small amount of holographic data, but also solve the problem of crosstalk between the layer and the layer and the elimination of noise in the tomographic reconstruction process, and the effect is particularly obvious. In this paper, the dynamic compressive sensing theory is applied to the field of three-dimensional digital holographic microscopy, which is different from the fixed sampling method used in the general compressive holographic imaging. It achieved fast 3D digital holography and improved axial resolution. We obtained holographic tomography images at a sampling rate of 6.25%, doubling the axial resolution witho ut loss of reproduction image resolution.

This paper introduces the weak signal detection method by using compressive sensing principle.Input signal is modulated by a pseudo-random sequence.The secondary measuring was carried out on the basis of the original measuring by means of transforming the measurement matrix.The location of the signal in the dictionary can be accurately recognized by using compressive sensing recovery algorithm.The result has been proved by the simulation experiments.The noise and interfering signals within the weak signal can be eliminated as the small signal-to-noise ratio of-20 dB.The signal can be recovered completely with little signal amplitude error.

Hyperspectral imaging technology is playing an increasingly important role in the fields of food analysis, medicine and biotechnology. To improve the speed of operation and increase the light throughput in a compact equipment structure, a Fourier transform hyperspectral imaging system based on a single-pixel technique is proposed in this study. Compared with current imaging spectrometry approaches, the proposed system has a wider spectral range (400–1100 nm), a better spectral resolution (1 nm) and requires fewer measurement data (a sample rate of 6.25%). The performance of this system was verified by its application to the non-destructive testing of potatoes.

As bike-sharing has been emerging, it does not only satisfy people's large amounts of requirements of short distance travel, but also assists in eliminating URBAN ILLS, such as traffic congestion, environment contamination and so on. Its convenience of usage has been greatly promoted when getting rid of parking piles, but some newly situations, such as irregular parking behaviors lead to traffic environmental problems, which has an impact on the sustainable development of the bike-sharing. In this paper, high precision virtual electronic fence technology based on GNSS, intelligent terminal and precision orientation algorithm was proposed. Moreover, the bike-sharing's regular parking management and the accuracy of intelligent scheduling come true via BDS (compatible with GPS s GLONASS and GALILEO). Sub-meter positioning precision was achieved in the virtual electric fence technique, and the accuracy rate of lairaging of the bike-sharing has been more than 90%.

A spectral single-pixel imaging system facilitates effective image compression, but the imaging region is limited by its single detector. This paper presents a hyperspectral camera that allows extended-field coverage to be collected by one detector. Compressive data of a large field of view is achieved by our highly sensitive detection camera, which can be extended to near-infrared or infrared spectral monitoring. We acquire a hyperspectral datacube of 256×256 spatial pixels and 3 nm spectral resolution at a sampling rate of 25%. Finally, we apply our camera to monitoring fruit freshness nondestructively by differentiating a banana's ripeness over time.