Groove Design and Microstructure Research of Ultra-Fine Grain Bar Rolling

New flat-oval groove rolling process of multi-direction deformation is proposed to manufacture ultra-fine grain bar. Application of new groove series can introduce uniform large plastic strain into whole cross section of the material, and meanwhile satisfy the requirements of shape and size. Principle of grain refinement, based on experimental research of small specimen, is that grain refinement of ferrite is mainly dynamic recrystallization when low-carbon alloy steel is at low temperature deformation. Relationship of grain size and z-factor is also obtained through experimental research, as well as ultra-fine ferrite grain less than 1 micron. To predict strain, shape, dimensions and grain size of the material in rolling process, numerical simulation model of the warm groove bar rolling process is established via nonlinear finite element method, and distribution of grain size of the final section is obtained via finite element subroutine. The result indicates that ultra-fine grain bar rolling can accomplish at low temperature region.

Target-adaptive optical phased array lidar

Lidar based on the optical phased array(OPA)and frequency-modulated continuous wave(FMCW)technology stands out in automotive applications due to its all-solid-state design,high reliability,and remarkable resistance to interference.However,while FMCW coherent detection enhances the interference resistance capabilities,it concurrently results in a significant increase in depth computation,becoming a primary constraint for improving point cloud density in such perception systems.To address this challenge,this study introduces a lidar solution leveraging the flexible scanning characteristics of OPA.The proposed system categorizes target types within the scene based on RGB images.Subsequently,it performs scans with varying angular resolutions depending on the importance of the targets.Experimental results demonstrate that,compared to traditional scanning methods,the target-adaptive method based on semantic segmentation reduces the number of points to about one-quarter while maintaining the resolution of the primary target area.Conversely,with a similar number of points,the proposed approach increases the point cloud density of the primary target area by about four times.

Silicon-based optical phased array with a reconfigurable aperture for“gaze”scanning of LiDAR

Light detection and ranging(LiDAR)serves as one of the key components in the fields of autonomous driving,surveying mapping,and environment detection.Conventionally,dense points clouds are pursued by LiDAR systems to provide high-definition 3D images.However,the LiDAR is typically used to produce abundant yet redundant data for scanning the homogeneous background of scenes,resulting in power waste and excessive processing time.Hence,it is highly desirable for a LiDAR system to“gaze”at the target of interest by dense scanning and rough sparse scans on the uninteresting areas.Here,we propose a LiDAR structure based on an optical phased array(OPA)with reconfigurable apertures to achieve such a gaze scanning function.By virtue of the cascaded optical switch integrated on the OPA chip,a 64-,128-,192-,or 256-channel antenna can be selected discretionarily to construct an aperture with variable size.The corresponding divergence angles for the far-field beam are 0.32°,0.15°,0.10°,and 0.08°,respectively.The reconfigurable-aperture OPA enables the LiDAR system to perform rough scans via the large beam spots prior to fine scans of the target by using the tiny beam spots.In this way,the OPA-based LiDAR can perform the“gaze”function and achieve full-range scanning efficiently.The scanning time and power consumption can be reduced by 1/4 while precise details of the target are maintained.Finally,we embed the OPA into a frequency-modulated continuous-wave(FMCW)system to demonstrate the“gaze”function in beam scanning.Experiment results show that the number of precise scanning points can be reduced by 2/3 yet can obtain the reasonable outline of the target.The reconfigurable-aperture OPA(RA-OPA)can be a promising candidate for the applications of rapid recognition,like car navigation and robot vision.

《版式电子文件长期保存格式需求》(DA/T 47-2009)解读

《版式电子文件长期保存格式需求》(DA/T 47-2009)是为规范版式电子文件长期保存格式而发布实施的档案行业重要标准。标准首次提出长期保存概念及其功能定位,明确了弱依赖导向的长期保存工作指导思想,技术处理上注重"自力更生",对其他门类电子文件格式管理同样具有很高的指导意义。本文介绍了规范编制的背景与意义,解读了版式文件格式管理的核心要点,并归纳总结了对电子文件长期保存工作的启示。

Germanium-on-silicon avalanche photodiode for 1550 nm weak light signal detection at room temperature

To optimize the dark current characteristic and detection efficiency of the 1550 nm weak light signal at room temperature,this work proposes a Ge-on-Si avalanche photodiode[APD]in Geiger mode,which could operate at 300 K.This lateral separate absorption charge multiplication APD shows a low breakdown voltage[V_(br)]in Geiger mode of-7.42 V and low dark current of 0.096 n A at unity gain voltage[V_(Gain)=1=-7.03 V].Combined with an RF amplifier module and counter,the detection system demonstrates a low dark count rate[DCR]of 1.1×10^(6) counts per second and high detection efficiencyηof 7.8%for 1550 nm weak coherent pulse detection at 300 K.The APD reported in this work weakens the dependence of the weak optical signal recognition on the low environment temperature and makes single-chip integration of the single-photon level detection system possible.

Three-terminal germanium-on-silicon avalanche photodiode with extended p-charge layer for dark current reduction

Germanium-on-silicon(Ge-on-Si) avalanche photodiodes(APDs) are widely used in near-infrared detection, laser ranging, free space communication, quantum communication, and other fields. However, the existence of lattice defects at the Ge/Si interface causes a high dark current in the Ge-on-Si APD, degrading the device sensitivity and also increasing energy consumption in integrated circuits. In this work, we propose a novel surface illuminated Ge-on-Si APD architecture with three terminals. Besides two electrodes on Si substrates, a third electrode is designed for Ge to regulate the control current and bandwidth, achieving multiple outputs of a single device and reducing the dark current of the device. When the voltage on Ge is -27.5 V, the proposed device achieves a dark current of 100 n A, responsivity of 9.97 A/W at -40 d Bm input laser power at 1550 nm, and optimal bandwidth of 142 MHz. The low dark current and improved responsivity can meet the requirements of autonomous driving and other applications demanding weak light detection.

Expanding the Coverage of Metabolic Landscape in Cultivated Rice with Integrated Computational Approaches

Genome-scale metabolomics analysis is increasingly used for pathway and function discovery in the post-genomics era.The great potential offered by developed mass spectrometry(MS)-based technologies has been hindered,since only a small portion of detected metabolites were identifiable so far.To address the critical issue of low identification coverage in metabolomics,we adopted a deep metabolomics analysis strategy by integrating advanced algorithms and expanded reference databases.The experimental reference spectra and in silico reference spectra were adopted to facilitate the structural annotation.To further characterize the structure of metabolites,two approaches were incorporated into our strategy,i.e.,structural motif search combined with neutral loss scanning and metabolite association network.Untargeted metabolomics analysis was performed on 150 rice cultivars using ultra-performance liquid chromatography coupled with quadrupoleOrbitrap MS.Consequently,a total of 1939 out of 4491 metabolite features in the MS/MS spectral tag(MS2T)library were annotated,representing an extension of annotation coverage by an order of magnitude in rice.The differential accumulation patterns of flavonoids between indica and japonica cultivars were revealed,especially O-sulfated flavonoids.A series of closely-related flavonolignans were characterized,adding further evidence for the crucial role of tricin-oligolignols in lignification.Our study provides an important protocol for exploring phytochemical diversity in other plant species.

On-chip generation of Bessel–Gaussian beam via concentrically distributed grating arrays for long-range sensing

Bessel beam featured with self-healing is essential to the optical sensing applications in the obstacle scattering environment.Integrated on-chip generation of the Bessel beam outperforms the conventional structure by small size,robustness,and alignment-free scheme.However,the maximum propagation distance(Z_(max))provided by the existing approaches cannot support long-range sensing,and thus,it restricts its potential applications.In this work,we propose an integrated silicon photonic chip with unique structures featured with concentrically distributed grating arrays to generate the Bessel-Gaussian beam with a long propagation distance.The spot with the Bessel function profile is measured at 10.24m without optical lenses,and the photonic chip’s operation wavelength can be continuously performed from 1500 to 1630 nm.To demonstrate the functionality of the generated Bessel-Gaussian beam,we also experimentally measure the rotation speeds of a spinning object via the rotational Doppler Effect and the distance through the phase laser ranging principle.The maximum error of the rotation speed in this experiment is measured to be 0.05%,indicating the minimum error in the current reports.By the compact size,low cost,and mass production potential of the integrated process,our approach is promising to readily enable the Bessel-Gaussian beam in widespread optical communication and micro-manipulation applications.