兴隆85cm望远镜的夜天光平场及Fringing效应

北京师范大学参与共建的85 cm光学望远镜是中国科学院国家天文台兴隆观测站的主力观测设备之一.利用该望远镜在2019年5月12日的非常规观测数据,构建了其在B、V、 R、 I 4个波段的夜天光平场,并与相应的天光平场进行了比较.发现天光平场改正的典型误差在0.5%左右,全视场最大可达1.5%–2.0%.同时,还构建了I波段夜天光背景的Fringing模型,并开放给该望远镜用户使用.

A threshold voltage model MOSFETs considering for high-k gate-dielectric fringing-field effect

In this paper, a threshold voltage model for high-k gate-dielectric metal-oxide-semiconductor field-effect transistors （MOSFETs） is developed, with more accurate boundary conditions of the gate dielectric derived through a conformal mapping transformation method to consider the fringing-field effects including the influences of high-k gate-dielectric and sidewall spacer. Comparing with similar models, the proposed model can be applied to general situations where the gate dielectric and sidewall spacer can have different dielectric constants. The influences of sidewall spacer and high-k gate dielectric on fringing field distribution of the gate dielectric and thus threshold voltage behaviours of a MOSFET are discussed in detail.

Influences of fringing capacitance on threshold voltage and subthreshold swing of a GeOI metal-oxide-semiconductor field-effect transistor

Models of threshold voltage and subthreshold swing, including the fringing-capacitance effects between the gate electrode and the surface of the source/drain region, are proposed. The validity of the proposed models is confirmed by the good agreement between the simulated results and the experimental data. Based on the models, some factors impacting the threshold voltage and subthreshold swing of a GeOI metal-oxide-semiconductor field-effect transistor（MOSFET） are discussed in detail and it is found that there is an optimum thickness of gate oxide for definite dielectric constant of gate oxide to obtain the minimum subthreshold swing. As a result, it is shown that the fringing-capacitance effect of a shortchannel GeOI MOSFET cannot be ignored in calculating the threshold voltage and subthreshold swing.

Fringing Red Sea Corals Survival: Is It Tide or Local Wind?

In this paper, we obtain tidal constituents and discuss observations of tidal and wind variations and its impact on water surface elevation at Zaki’s Reef;a fringing coral reef located in the Red Sea-Gulf of Suez. This manuscript focuses on investigating if tidal forces are playing a key role to keep the area’s unique coral reefs alive and well. Determining the reasons why coral species and community of organisms found here survive despite all stressors is critical, and such information may hold the key to the preservation of reefs elsewhere. Phase and amplitude for 35 tidal constituents were deducted from observations of water surface elevation at the study site (first of its kind). The main tidal constituents based on their amplitudes are: M2, N2, S2, K1, NU2, K2, 2Ns, L2, and MU2. The first five tidal constituents of the aforementioned list are enough to reproduce accurate predictions of tides at this location (R2 variance = 87.54% and RMS = 0.167). The Tidal Form number (0.07) at Zaki’s Reef indicates a fully semidiurnal dominated tidal regime. Moreover, the Sa and Ssa constituents obtained from nearby stations made no improvements on tidal prediction results. Spectral analysis results of the white noise (residuals) from observed water surface elevation are dominated by daily frequency, suggesting that local wind plays a key role in circulation at study site. Local wind generated southerly long-shore and year-round offshore wind stress with a mean of?-0.36 & 0.35 , respectively. The persistent longshore and offshore currents help transport oil patches/spills, from the two nearby ports, away from the reef. Yet, offshore wind stress, pushing water away from the shore, may cause more exposure of the reef to extreme atmospheric conditions. We hypothesize that the repeated reef exposure to the combined effect of tides and offshore wind stress over many years may have played a key role in selecting and then enhancing corals ability, through training, to become more adaptable to those harsh conditions. Training of corals over the years, may have led to the dominance of only six species, out of 35 coral species known to exist in the gulf. Those heat-adopted dominant species can be used to stimulate and revive impacted coral sites elsewhere.

On biogeomorphology of Luhuitou fringing reef of Sanya City,Hainan Island,China

Based on comprehensive survey of 6 transects on Luhuitou fringing reef in Sanya City of Hainan Island, China, some features of its biogeomorphologic processes were found, including ( i ) three basic biogeomorphologic units: inner reef flat, outer reef flat and reef slope; (ii) two important biogeomorphologic boundary lines: up limit for live flat coral growing between inner and outer reef flats is Mean Lower Low Water of tropic tide±15 cm; the break in slope between reef flat and reef slope is Theoretical Lowest Tide ±15 cm; (iii) three types of reef flat profiles in response to distinctive Holocene sea level changes and dynamic condition: Luhuitou type responds to falling sea level and low wave energy; Xiaodonghai type to falling sea sevel and high wave energy; type for atolls of Nansha Islands to stable sea level and low wave energy; (iv) hermatypic coral community is the most essential member in coral reef ecosystem and plays the most important role in biogeomorphologic process. Over the past 30

A fringe jump counting method for the phase measurement in the HCN laser interferometer on EAST and its FPGA-based implementation

Electron density in fusion plasma is usually diagnosed using laser-aided interferometers. The phase difference signal obtained after phase demodulation is wrapped, which is also called a fringe jump. A method has been developed to unwrap the phase difference signal in real time using FPGA, specifically designed to handle fringe jumps in the hydrogen cyanide(HCN) laser interferometer on the EAST superconducting tokamak. This method is designed for a phase demodulator using the fast Fourier transform(FFT) method at the front end. The method is better adapted for hardware implementation compared to complex mathematical analysis algorithms, such as field programmable gate array(FPGA). It has been applied to process the phase measurement results of the HCN laser interferometer on EAST in real time. Electron density results show good confidence in the fringe jump unwrapping method. Further possible application in other laser interferometers, such as the POlarimeter-INTerferometer(POINT)system on EAST tokamak is also discussed.

Exploring Capillary Fringe Flow:Quasilinear Modeling with Kirchhoff Transforms and Gardner Model

Recent studies have underscored the significance of the capillary fringe in hydrological and biochemical processes.Moreover,its role in shallow waters is expected to be considerable.Traditionally,the study of groundwater flow has centered on unsaturated-saturated zones,often overlooking the impact of the capillary fringe.In this study,we introduce a steady-state two-dimensional model that integrates the capillary fringe into a 2-D numerical solution.Our novel approach employs the potential form of the Richards equation,facilitating the determination of boundaries,pressures,and velocities across different ground surface zones.We utilized a two-dimensional Freefem++finite element model to compute the stationary solution.The validation of the model was conducted using experimental data.We employed the OFAT(One_Factor-At-Time)method to identify the most sensitive soil parameters and understand how changes in these parameters may affect the behavior and water dynamics of the capillary fringe.The results emphasize the role of hydraulic conductivity as a key parameter influencing capillary fringe shape and dynamics.Velocity values within the capillary fringe suggest the prevalence of horizontal flow.By variation of the water table level and the incoming flow q0,we have shown the correlation between water table elevation and the upper limit of the capillary fringe.

Physics-informed deep learning for fringe pattern analysis

Recently,deep learning has yielded transformative success across optics and photonics,especially in optical metrology.Deep neural networks (DNNs) with a fully convolutional architecture (e.g.,U-Net and its derivatives) have been widely implemented in an end-to-end manner to accomplish various optical metrology tasks,such as fringe denoising,phase unwrapping,and fringe analysis.However,the task of training a DNN to accurately identify an image-to-image transform from massive input and output data pairs seems at best naive,as the physical laws governing the image formation or other domain expertise pertaining to the measurement have not yet been fully exploited in current deep learning practice.To this end,we introduce a physics-informed deep learning method for fringe pattern analysis (PI-FPA) to overcome this limit by integrating a lightweight DNN with a learning-enhanced Fourier transform profilometry (Le FTP) module.By parameterizing conventional phase retrieval methods,the Le FTP module embeds the prior knowledge in the network structure and the loss function to directly provide reliable phase results for new types of samples,while circumventing the requirement of collecting a large amount of high-quality data in supervised learning methods.Guided by the initial phase from Le FTP,the phase recovery ability of the lightweight DNN is enhanced to further improve the phase accuracy at a low computational cost compared with existing end-to-end networks.Experimental results demonstrate that PI-FPA enables more accurate and computationally efficient single-shot phase retrieval,exhibiting its excellent generalization to various unseen objects during training.The proposed PI-FPA presents that challenging issues in optical metrology can be potentially overcome through the synergy of physics-priors-based traditional tools and data-driven learning approaches,opening new avenues to achieve fast and accurate single-shot 3D imaging.

Theory and verification of moiréfringes for x-ray three-phase grating interferometer

Dual-phase and three-phase grating x-ray interference is a promising new technique for grating-based x-ray differential phase contrast imaging.Dual-phase grating interferometers have been relatively completely studied and discussed.In this paper,the corresponding imaging fringe formula of the three-phase grating interferometer is provided.At the same time,the similarities and differences between the three-phase grating interferometer and the dual-phase grating interferometer are investigated and verified,and that the three-phase grating interferometer can produce large-period moiréfringes without using the analyzing grating is demonstrated experimentally.Finally,a simple method of designing three-phase grating and multi-grating imaging systems from geometric optics based on the thin-lens theory of gratings is presented.These theoretical formulas and experimental results provide optimization tools for designing three-phase grating interferometer systems.

Fringe家族基因在癌症中作用的研究进展

Fringe家族基因由疯狂边缘基因(LFNG)、躁狂边缘基因(MFNG)和激进边缘基因(RFNG)组成。Fringe家族基因编码的蛋白可修饰Notch受体来调控Notch信号通路,从而发挥调节细胞增殖、分化和凋亡等生物学功能。Genecards数据库分析了Fringe家族基因的染色体位置及生物学功能等。UCSCXenaShiny数据库整合癌症细胞系百科全书(CCLE)、癌症基因组图谱(TCGA)和基因型-组织表达(GTEx)数据分析了Fringe家族基因在泛癌细胞系、TCGA肿瘤组织和相对应的GTEx正常组织中的差异表达与预后价值。本文就Fringe家族基因在癌症中的作用作一综述。

Metropolitan Housing Development in Urban Fringe Areas-A Case Study of Three Metropolitan Cities of South Africa: Johannesburg, Ekurhuleni and Tshwane

Purpose:The metropolitan cities of Johannesburg,Ekurhuleni and Tshwane play an important role in the economy of the Gauteng province in South Africa.The region constitutes to 22.4 percent of the total population of South Africa and has a strong presence and contributes in areas of manufacturing sector,financial and business services,retail and wholesale trade,etc.The rapid urban population,increase in the informal settlements and socio-economic opportunities has resulted in considerable urban sprawl in and around the urban fringe areas of these metropolitan cities.The urban fringe areas of these metros often come under the influence of rapid urbanization process and pressures.Coupled with the economical and potential land dynamics and lack of priority of spatial development guidelines,these areas attract rapid and haphazard development from communities and developers.Research Design/Methodology:This research is based on a qualitative approach through a comprehensive literature review that included content analysis of key documents on housing sector such as IDPs(Integrated Development Plans),Municipal Annual Reports,Growth Development Strategies,and among other sectoral documents on housing sector.Some of the key priority issues considered in the housing sector included:eradication of housing backlogs,spatial restructuring of housing,provision of choice in terms of location,tenure and housing typology.Findings:The current paper discusses the approaches of metropolitan housing development processes in three metropolitan cities of South Africa from Gauteng region,namely:Johannesburg,Ekurhuleni and Tshwane.The paper discusses the existing housing sectoral scenario along with the fringe areas in three cities with focus on:formal and informal settlements,housing segregation and the backlogs,current institutional arrangements,role of public private participation,and scope for alternate mechanisms.The paper concludes in discussion on sustainable development options for housing development in urban fringe areas.

Modeling of cylindrical surrounding gate MOSFETs including the fringing field effects

A physically based analytical model for surface potential and threshold voltage including the fringing gate capacitances in cylindrical surround gate（CSG） MOSFETs has been developed.Based on this a subthreshold drain current model has also been derived.This model first computes the charge induced in the drain/source region due to the fringing capacitances and considers an effective charge distribution in the cylindrically extended source/drain region for the development of a simple and compact model.The fringing gate capacitances taken into account are outer fringe capacitance,inner fringe capacitance,overlap capacitance,and sidewall capacitance.The model has been verified with the data extracted from 3D TCAD simulations of CSG MOSFETs and was found to be working satisfactorily.

Wavelength Dependent Nonlinear Spectroscopic Study of Third Harmonic Generation Probed by Rotational Maker Fringes Method

Efficient third-order nonlinearities of the Zinc Oxide and Al-doped Zinc Oxide were studied by Third Harmonic Generation (Third Harmonic Generation) Maker fringes to establish the effect Aluminum of Aluminum doping (Al-doping) on the cubic nonlinearities. Adding the Al-dopant to the Zinc Oxide crystal structure results in changes that affect the optical and nonlinear characteristics. Presented results indicate that the magnitude of X(3) was enhanced at single experimental wavelengths;however, across the broadband experimental spectrum, the effect of Al-doping remained relatively constant. The observed enhancement of third-order nonlinearity was purely from the bound electronic response. The observation is attributed to increased charge carriers and spontaneous polarization in the Zinc Oxide and Al-doped Zinc Oxide crystal structure.

DuFNet:Dual Flow Network of Real-Time Semantic Segmentation for Unmanned Driving Application of Internet of Things

The application of unmanned driving in the Internet of Things is one of the concrete manifestations of the application of artificial intelligence technology.Image semantic segmentation can help the unmanned driving system by achieving road accessibility analysis.Semantic segmentation is also a challenging technology for image understanding and scene parsing.We focused on the challenging task of real-time semantic segmentation in this paper.In this paper,we proposed a novel fast architecture for real-time semantic segmentation named DuFNet.Starting from the existing work of Bilateral Segmentation Network(BiSeNet),DuFNet proposes a novel Semantic Information Flow(SIF)structure for context information and a novel Fringe Information Flow(FIF)structure for spatial information.We also proposed two kinds of SIF with cascaded and paralleled structures,respectively.The SIF encodes the input stage by stage in the ResNet18 backbone and provides context information for the feature fusionmodule.Features from previous stages usually contain rich low-level details but high-level semantics for later stages.Themultiple convolutions embed in Parallel SIF aggregate the corresponding features among different stages and generate a powerful global context representation with less computational cost.The FIF consists of a pooling layer and an upsampling operator followed by projection convolution layer.The concise component provides more spatial details for the network.Compared with BiSeNet,our work achieved faster speed and comparable performance with 72.34%mIoU accuracy and 78 FPS on Cityscapes Dataset based on the ResNet18 backbone.

Optimal zero-crossing group selection method of the absolute gravimeter based on improved auto-regressive moving average model

An absolute gravimeter is a precision instrument for measuring gravitational acceleration, which plays an important role in earthquake monitoring, crustal deformation, national defense construction, etc. The frequency of laser interference fringes of an absolute gravimeter gradually increases with the fall time. Data are sparse in the early stage and dense in the late stage. The fitting accuracy of gravitational acceleration will be affected by least-squares fitting according to the fixed number of zero-crossing groups. In response to this problem, a method based on Fourier series fitting is proposed in this paper to calculate the zero-crossing point. The whole falling process is divided into five frequency bands using the Hilbert transformation. The multiplicative auto-regressive moving average model is then trained according to the number of optimal zero-crossing groups obtained by the honey badger algorithm. Through this model, the number of optimal zero-crossing groups determined in each segment is predicted by the least-squares fitting. The mean value of gravitational acceleration in each segment is then obtained. The method can improve the accuracy of gravitational measurement by more than 25% compared to the fixed zero-crossing groups method. It provides a new way to improve the measuring accuracy of an absolute gravimeter.

Establishment and Error Analysis of Model of Interference Fringe Contrast for Laser Tracing Measurement Optical System

A method was proposed to analyze the influences of the non-ideal spectroscopic performance of optical components and orientation errors of a laser tracing measurement optical system on the tracing measurement performance.A comprehensive model of the interference fringe contrast based on the laser tracing system s measurement principle was established in this study.Simulation results based on ZEMAX verified the model.According to the simulation results,the placement angle of the analyzer had a direct influence on the interference fringe contrast.When the angle of the polarized light to the analyzer’s transmission axis increased from 65°to 85°,each contrast of the four-way interference fringes decreased from 0.9996 to 0.3528,the interference fringe contrast is decreased by 65%.Under the split ratio of beam splitters in the interference part(BS 1)of 5∶5,when the splitting ratio of BS 2 changed from 2∶8 to 8∶2,the fringe contrast of the interference signals received by the photodetectors increased,but the injection light intensity onto the PSD reflected by BS 2 decreased.The significant influence of the tracing performance was verified by the experiments.When splitting ratio of BS 2 increased,the contrast of the interference fringes increased.Due to the weakening of the incident light intensity of the PSD caused by the change of BS 2 splitting ratio,the response time of the tracing system is increased by 23.7 ms.As a result,the tracing performance of the laser tracing measurement optical system was degraded.An important theoretical basis was provided to evaluate and improve the accuracy and reliability of laser tracing measurement systems.

Measurement of Shear Stress Acting on Flat Plate Using Oil Film Interferometry

Measurements of frictional resistance play an important role in engineering practice. There are several types of air resistance acting on an aircraft, for example. One of them, frictional resistance, accounts for half of the air resistance. Oil film interferometry is one of methods for measuring the frictional resistance. Oil dropped on an object is thinly stretched by the frictional resistance. The bright and dark fringe pattern is generated when monochromatic light is applied to the oil film. The gradient of the oil thickness decreases with the lapse of time, and thus the spacing between neighboring the dark lines increases. The rate at which the spacing increases is proportional to the frictional resistance. In this study, the frictional resistance acting on a small area on a plate was measured and compared with the theoretical value. As a result, these results qualitatively agree well with each other.

An Improved Angle Polishing Method for Measuring Subsurface Damage in Silicon Wafers

We present an improved angle polishing method in which the end of the cover slice near the glue layer is beveled into a thin,defect-free wedge,the straight edge of which is used as the datum for measuring the depth of subsurface damage. The bevel angle can be calculated from the interference fringes formed in the wedge. The minimum depth of the subsurface damage that can be measured by this method is a few hundred nanometers. Our results show that the method is straightforward, accurate, and convenient.

投影物镜小比率模型的计算机辅助装调

针对小比率模型光学系统光学元件数量较多,无法用每个补偿量去补偿对应失调量的问题,提出利用计算机辅助装调方法,通过建立系统的灵敏度矩阵找出偏心失调量和倾斜失调量的内在联系来缩小补偿量的选择范围。根据失调量敏感度的分析,提出了只用4个补偿量补偿系统波像差的想法,并对所选补偿参量的补偿效果进行仿真,以此近一步验证想法的可行性。光学系统初装完成后,将实际测得的系统波像差以36项Fringe Zernike多项式的形式代入灵敏度矩阵,计算得到补偿参量的补偿值和移动方向,用驱动器实现像质补偿。实验结果表明:系统波像差(RMS)由50.864 nm提高到25.993 nm,优于技术指标要求,证明了所选的4个补偿量的正确性和有效性。

Microstructure of Mg-8Zn-4Al-1Ca aged alloy

The microstructure of Mg-8Zn-4Al-1Ca aged alloy was investigated by TEM and HRTEM. The results show that the hardening produced in the Mg-8Zn-4Al-1Ca alloy is considerably higher than that in the Mg-8Zn-4A1 alloy. A dense dispersion of disc-like Ca2Mg6Zn3 precipitates are formed in Mg-8Zn-4Al-1Ca alloy aged at 160 ℃ for 16 h. In addition, the lattice distortions, honeycomb-looking Moir＆#233; fringes, edge dislocations and dislocation loop also exist in the microstructure. The precipitates of alloy aged at 160 ℃ for 48 h are coarse disc-like and fine dispersed grainy. When the alloy is subjected to aging at 160 ℃ for 227 h, the microstructure consists of numerous MgZn2 precipitates and Ca2Mg6Zn3 precipitates. All the analyses show that Ca is a particularly effective trace addition in improving the age-hardening and postponing the formation of MgZn2 precipitates in Mg-8Zn-4Al alloy aged at 160 ℃.