核心技术原始创新引领智慧农业健康发展

智慧农业是充分运用人的智慧发展农业的新形态,它是农业发展的新阶段、新模式和新业态。农业信息技术的发展是智慧农业发展的必然要求,以农业大数据、云计算、物联网、人工智能、农业等离子体等新一代信息技术可以赋能智慧农业,为智慧农业的健康发展提供了新技术、新手段和新方案。农业信息化标准化是引导农业科技进步与创新的前提,是智慧农业发展的迫切需要;农业物联网与农业专用芯片是智慧农业发展的核心技术及装备;农业大数据与云计算是海量复杂农业信息处理的有力技术支撑;农业信息安全与区块链是保障农业信息安全、农产品质量认证与农业安全的关键;农业人工智能是提高农业劳动生产力、降低资源消耗、智能高效生产的必然选择;农业等离子体技术是发展健康农业、提升农产品品质切实有效的新手段。智慧农业核心关键技术原始创新自主可控,必将引领智慧农业健康发展。

Grapevine VlbZIP30 improves drought resistance by directly activating VvNAC17 and promoting lignin biosynthesis through the regulation of three peroxidase genes

Drought stress severely affects grapevine quality and yield,and recent reports have revealed that lignin plays an important role in protection from drought stress.Since little is known about lignin-mediated drought resistance in grapevine,we investigated its significance.Herein,we show that VlbZIP30 mediates drought resistance by activating the expression of lignin biosynthetic genes and increasing lignin deposition.Transgenic grapevine plants overexpressing VlbZIP30 exhibited lignin deposition(mainly G and S monomers)in the stem secondary xylem under control conditions,which resulted from the upregulated expression of VvPRX4 and VvPRX72.Overexpression of VlbZIP30 improves drought tolerance,characterized by a reduction in the water loss rate,maintenance of an effective photosynthesis rate,and increased lignin content(mainly G monomer)in leaves under drought conditions.Electrophoretic mobility shift assay,luciferase reporter assays,and chromatin immunoprecipitation-qPCR assays indicated that VlbZIP30 directly binds to the G-box cis-element in the promoters of lignin biosynthetic(VvPRX N1)and drought-responsive(VvNAC17)genes to regulate their expression.In summary,we report a novel VlbZIP30-mediated mechanism linking lignification and drought tolerance in grapevine.The results of this study may be of value for the development of molecular breeding strategies to produce drought-resistant fruit crops.

A Dual-Platform Laser Scanner for 3D Reconstruction of Dental Pieces

This paper presents a dual-platform scanner for dental reconstruction based on a three-dimensional(3D)laser-scanning method.The scanner combines translation and rotation platforms to perform a holistic scanning.A hybrid calibration method for laser scanning is proposed to improve convenience and precision.This method includes an integrative method for data collection and a hybrid algorithm for data processing.The integrative method conveniently collects a substantial number of calibrating points with a stepped gauge and a pattern for both the translation and rotation scans.The hybrid algorithm,which consists of a basic model and a compensation network,achieves strong stability with a small degree of errors.The experiments verified the hybrid calibration method and the scanner application for the measurement of dental pieces.Two typical dental pieces were measured,and the experimental results demonstrated the validity of the measurement that was performed using the dual-platform scanner.This method is effective for the 3D reconstruction of dental pieces,as well as that of objects with irregular shapes in engineering fields.

Development of series SQUID array with on-chip filter for TES detector

A cold preamplifier based on superconducting quantum interference devices(SQUIDs)is currently the preferred readout technology for the low-noise transition edge sensor(TES).In this work,we have designed and fabricated a series SQUID array(SSA)amplifier for the TES detector readout circuit.In this SSA amplifier,each SQUID cell is composed of a first-order gradiometer formed using two equally large square washers,and an on-chip low pass filter(LPF)as a radiofrequency(RF)choke has been developed to reduce the Josephson oscillation interference between individual SQUID cells.In addition,a highly symmetric layout has been designed carefully to provide a fully consistent embedded electromagnetic environment and achieve coherent flux operation.The measured results show smooth V-Φcharacteristics and a swing voltage that increases linearly with increasing SQUID cell number N.A white flux noise level as low as 0.28μφ;/Hz;is achieved at 0.1 K,corresponding to a low current noise level of 7 pA/Hz;.We analyze the measured noise contribution at mK-scale temperatures and find that the dominant noise derives from a combination of the SSA intrinsic noise and the equivalent current noise of the room temperature electronics.

Survey and evaluation of monocular visual-inertial SLAM algorithms for augmented reality

Although VSLAM/VISLAM has achieved great success,it is still difficult to quantitatively evaluate the localization results of different kinds of SLAM systems from the aspect of augmented reality due to the lack of an appropriate benchmark.For AR applications in practice,a variety of challenging situations(e.g.,fast motion,strong rotation,serious motion blur,dynamic interference)may be easily encountered since a home user may not carefully move the AR device,and the real environment may be quite complex.In addition,the frequency of camera lost should be minimized and the recovery from the failure status should be fast and accurate for good AR experience.Existing SLAM datasets/benchmarks generally only provide the evaluation of pose accuracy and their camera motions are somehow simple and do not fit well the common cases in the mobile AR applications.With the above motivation,we build a new visual-inertial dataset as well as a series of evaluation criteria for AR.We also review the existing monocular VSLAM/VISLAM approaches with detailed analyses and comparisons.Especially,we select 8 representative monocular VSLAM/VISLAM approaches/systems and quantitatively evaluate them on our benchmark.Our dataset,sample code and corresponding evaluation tools are available at the benchmark website http://www.zjucvg.net/eval-vislam/.

Predicting the Seasonal NDVI Change by GIS Geostatistical Analyst and Study on Driver Factors of NDVI Change in Hainan Island, China

As Hainan Island belonged to tropical monsoon influenced region, vegetation coverage was high. It is accessible to acquire the vegetation index information from remote sensing images, but predicting the average vegetation index in spatial distributing trend is not available. Under the condition that the average vegetation index values of observed stations in different seasons were known, it was possible to qualify the vegetation index values in study area and predict the NDVI (Normal Different Vegetation Index) change trend. In order to learn the variance trend of NDVI and the relationships between NDVI and temperature, precipitation, and land cover in Hainan Island, in this paper, the average seasonal NDVI values of 18 representative stations in Hainan Island were derived by a standard 10-day composite NDVI generated from MODIS imagery. ArcGIS Geostatistical Analyst was applied to predict the seasonal NDVI change trend by the Kriging method in Hainan Island. The correlation of temperature, precipitation, and land cover with NDVI change was analyzed by correlation analysis method. The results showed that the Kriging method of ARCGIS Geostatistical Analyst was a good way to predict the NDVI change trend. Temperature has the primary influence on NDVI, followed by precipitation and land-cover in Hainan Island.

The Design and Realization of Personalized E-commerce Recommendation System

According to demand and function of the e-commerce recommendation system demand, this paper analyze and design e-commerce and personalized recommendation, design and complete different system functions in different system level; then design in detail system process from the front and back office systems, and in detail descript the key data in the database and several tables. Finally, the paper respectively tests several main modules of onstage system and the backstage system. The paper designed electronic commerce recommendation based on personalized recommendation system, it can complete the basic function of the electronic commerce system, also can be personalized commodity recommendation for different users, the user data information and the user＇ s shopping records.

3D vision for virtual reality and augmented reality

3D vision is a kind of technology that allow computers to perceive,reconstruct and interact with the 3D world based on vision sensors.It is not only a hot academic topic in computer science,but also crucial to many applications,such as virtual reality(VR)and augmented reality(AR).For achieving high-quality effects of VR and AR,we need to recover the 6DoF camera pose,3D structure of the scene,and even the human interaction,so that people not only can see the lifelike virtual objects/scenes,but also the seamless fusion of virtual and real contents and even interact with them.We can leverage 3D vision technology to achieve this objective.For example,the simultaneous localization and mapping(SLAM)technique allows users to walk freely in a digital world wearing a VR/AR helmet by recovering the 6DoF movement of the helmet,and is also able to see the seamless mixture of real and virtual contents,and even the effect of their interaction with each other by reconstructing the geometry,textures and materials of the real environment.In this special issue,we have selected 6 papers(3 review papers,2 research articles and 1 case report)covering 3 most relevant 3D vision techniques for the VR/AR applications,including SLAM,3D reconstruction,object segmentation and tracking.

Single-photon frequency-modulated continuous-wave Lidar based on quantum compressed sensing

Frequency-modulated continuous-wave(FMCW)Lidar has the characteristics of high-ranging accuracy,noise immunity,and synchronous speed measurement,which makes it a candidate for the next generation of vehicle Lidar.In this work,an FMCW Lidar working at the single-photon level is demonstrated based on quantum compressed sensing,and the target distance is recovered from the sparse photon detection,in which the detection sensitivity,bandwidth,and compression ratio are improved significantly.Our Lidar system can achieve 3 GHz bandwidth detection at photon count rates of a few thousand,making ultra-long-distance FMCW Lidar possible.

Recent Progress of Full‑Field Three‑Dimensional Shape Measurement Based on Phase Information

Full-field three-dimensional(3D)measurement technology based on phase information has become an indispensable part of geometric dimension measurement in modern scientific research and engineering applications.This field has been developing and evolving for the study of highly reflective phenomena,diffuse reflections,and specular surfaces,and many novel methods have emerged to increase the speed of measurements,enhance data accuracy,and broaden the robustness of the system.Herein,we will discuss the latest research progress in full-field 3D shape measurement based on phase information systematically and comprehensively.First,the fundamentals of 3D shape measurement based on phase information are introduced,namely,phase-shifting and transform-based methods.Second,recent technological innovations are highlighted,including increases in measurement speed and automation and improvements in robustness in complex environments.In particular,the challenges faced by these technological advances in solving highly dynamic,composite surface measurement problems are presented,i.e.,with multiexposure techniques proposed for high dynamics that extend the dynamic range of the camera to reduce the effects of overexposure but increase the cost of time and have high hardware requirements,fringe adaptive techniques that overcome light variations but are computationally complex,and multipolarized camera techniques that reduce the effects of light variations but are sensitive to the light source.Third,the phase-shifting method combined with coding is proposed to improve the measurement speed,but the accuracy is slightly reduced.Deep learning techniques are proposed to cope with measurements in complex environments,but the dataset computation process is cumbersome.Finally,future research directions are suggested,and the challenges are presented.Overall,this work provides a reference for researchers and engineers.

面向具身智能的网格细胞群表征空间认知方法

与基于结构化场景建模的传统导航算法不同,哺乳动物通过内嗅皮层和海马体中多种神经细胞的分工协作构建认知地图,实现了适用于非结构化场景且具有强鲁棒性、泛化性的导航.随着认知神经科学、人工智能等领域的发展,类脑导航在近年来受到了广泛的关注,成为实现“具身智能”中机器人环境认知与导航功能的可行方案.本文结合大脑空间认知机理以及同时定位与地图构建算法,提出了一种基于网格细胞群表征模型的移动机器人认知地图构建系统.在该系统中,网格细胞模型与位置细胞模型协同配合完成了位置表征、路径积分的功能.基于公开真实数据集的实验,验证了该系统在认知地图构建任务中的有效性与网格细胞群表征模型的度量特性.此外,这种脑启发式的认知地图构建系统为进一步揭示人脑的空间认知机理提供了有效的实验环境.

A flat-based plasmonic fiber probe for nanoimaging

The difficulty of obtaining high-intensity localized light spots for optical probes leads to their lack of good applications in nanoimaging.Here we demonstrate a Fabry–Pérot resonance flat-based plasmonic fiber probe(FPFP).The simulation results show that the probe can obtain a nanofocusing spot at the tip with the radially polarized mode.The Fabry–Pérot interference structure is used to control the plasmon propagation on the surface of the probe,it effectively improves the local spot intensity at the tip.Furthermore,the experimental results verify that the FPFP(tip curvature radius is 20 nm)prepared by chemical etching method can obtain a nanofocusing spot at the tip.The nanoimaging of the gold slit structure demonstrates the nanoimaging capability of the FPFP,the 36.9 nm slit width is clearly identified by the FPFP.

Breaking the symmetry of colloidal 2D nanoplatelets:Twist induced quantum coupling

Twist provides a new degree of freedom for nanomaterial modifications,which can provide novel physical properties.Here,colloidal two-dimensional(2D)twisted CdSe nanoplatelets(NPLs)are successfully fabricated and their morphology can change from totally flat to edge-twisted,and then to middle-twisted with prolonged reaction time.By combining experiments and corresponding theoretical analyses,we have established the length-dependent relationships between the surface energy and twist,with a critical lateral dimension of 30 nm.We found that the defects formed during the synthesis process play a vital role in generating intense stress that develops a strong torsion tensor around the edges,resulting in edge-twisted and final middletwisted NPLs.Furthermore,due to the geometric asymmetry of twisted NPLs,the dissymmetry factor of single particle NPLs can reach up to 0.334.Specifically,quantum coupling occurs in middle-twisted NPLs by twisting one parent NPL into two daughter NPLs,which are structurally and electronically coupled.This work not only further deepens our understanding of the twist mechanism of 2D NPLs during colloidal synthesis,but also opens a pathway for applications using twistronics and quantum technology.

Polarization-insensitive plasmon nanofocusing with broadband interference modulation for optical nanoimaging

Delivering light to the nanoscale using a flexible and easily integrated fiber platform holds potential in various fields of quantum science and bioscience.However,rigorous optical alignment,sophisticated fabrication process,and low spatial resolution of the fiber-based nanoconcentrators limit the practical applications.Here,a broadband azimuthal plasmon interference nanofocusing technique on a fiber-coupled spiral tip is demonstrated for fiber-based near-field optical nanoimaging.The spiral plasmonic fiber tip fabricated through a robust and reproducible process can reverse the polarization and modulate the mode field of the surface plasmon polaritons in three-dimensionally azimuthal direction,resulting in polarization-insensitive,broad-bandwidth,and azimuthal interference nanofocusing.By integrating this with a basic scanning near-field optical microscopy,a high optical resolution of 31 nm and beyond is realized.The high performance and the easy incorporation with various existing measurement platforms offered by this fiber-based nanofocusing technique have great potential in near-field optics,tip-enhanced Raman spectroscopy,nonlinear spectroscopy,and quantum sensing.

Deep learning in two-dimensional materials:Characterization,prediction,and design

Since the isolation of graphene,two-dimensional(2D)materials have attracted increasing interest because of their excellent chemical and physical properties,as well as promising applications.Nonetheless,particular challenges persist in their further development,particularly in the effective identification of diverse 2D materials,the domains of large-scale and highprecision characterization,also intelligent function prediction and design.These issues are mainly solved by computational techniques,such as density function theory and molecular dynamic simulation,which require powerful computational resources and high time consumption.The booming deep learning methods in recent years offer innovative insights and tools to address these challenges.This review comprehensively outlines the current progress of deep learning within the realm of 2D materials.Firstly,we will briefly introduce the basic concepts of deep learning and commonly used architectures,including convolutional neural and generative adversarial networks,as well as U-net models.Then,the characterization of 2D materials by deep learning methods will be discussed,including defects and materials identification,as well as automatic thickness characterization.Thirdly,the research progress for predicting the unique properties of 2D materials,involving electronic,mechanical,and thermodynamic features,will be evaluated succinctly.Lately,the current works on the inverse design of functional 2D materials will be presented.At last,we will look forward to the application prospects and opportunities of deep learning in other aspects of 2D materials.This review may offer some guidance to boost the understanding and employing novel 2D materials.

湖北五峰后河国家级自然保护区鸟类多样性

为了解湖北五峰后河国家级自然保护区(以下简称后河保护区)鸟类物种多样性及其区系组成的变化,我们通过样线、红外相机调查和检索文献资料相结合的方法获得了后河保护区鸟类名录,并将其与后河保护区1999年科学考察结果进行对比分析。本研究于2017–2019年共在后河保护区内设置了82km的鸟类调查样线,共在309个位点上放置了红外相机,累计99,586个相机日。我们用“后河”“鸟类”“湖北省”等关键词搜索相关出版物,并查阅中国观鸟记录中心经审核后发布的鸟类信息,结合样线和红外相机调查结果形成后河保护区鸟类名录。共整理得到后河保护区鸟类255种,隶属于16目55科。其中,国家I级重点保护野生鸟类2种,包括中华秋沙鸭(Mergus squamatus)和金雕(Aquila chrysaetos);国家II级重点保护野生鸟类46种,包括红腹角雉(Tragopan temminckii)、棉凫(Nettapus coromandelianus)、松雀鹰(Accipiter virgatus)、灰林鸮(Strix aluco)、蓝鹀(Emberizasiemsseni)等。此外,后河保护区有11种中国特有鸟类,占我国特有鸟类种数(n=93)的11.83%。在区系成分上,后河保护区鸟类以东洋种为主(151种,占59.22%),其次为广布种(55种,占21.57%)。与1999年科学考察结果相比,鸟类增加了116种,其中有15种国家重点保护野生鸟类。在区系组成上,后河保护区内东洋种占比增加,包括分布区向北扩散的物种成分。此外,本次调查未记录到20世纪在保护区内有分布的白冠长尾雉(Syrmaticusreevesii)和海南鳽(Gorsachiusmagnificus)。本研究表明,后河保护区鸟类物种多样性高、特有种及珍稀濒危物种丰富,具有极高的保护价值和意义。通过对比分析后河保护区内野生鸟类动态变化,可为保护区生物多样性监测方案设计和保护对策的制定提供科学依据。

In-situ fabricated anisotropic halide perovskite nanocrystals in polyvinylalcohol nanofibers: Shape tuning and polarized emission

We report an in-situ fabrication of halide perovskite (CH3NH3PbX3,CH3NH3 =methylammonium,MA,X =Cl,Br,I) nanocrystals in polyvinylalcohol (PVA) nanofibers (MAPbX3@PVA nanofibers) through electrospinning a perovskite precursor solution.With the content of the precursors increased,the resulting MAPbBr3 nanocrystals in PVA matrix changed the shape from ellipsoidal to pearl-like,and finely into rods-like.Optimized MAPbBr3@PVA nanofibers show strong polarized emission with the photoluminescence quantum yield of up to 72%.We reveal correlations between the shape of in-situ fabricated perovskite nanocrystals and the polarization degree of their emission by comparing experimental data from the single nanofiber measurements with theoretical calculations.Polarized emission of MAPbBr3@PVA nanofibers can be attributed to the dielectric confinement and quantum confinement effects.Moreover,nanofibers can be efficiently aligned by using parallel positioned conductor strips with an air gap as collector.A polarization ratio of 0.42 was achieved for the films of well-aligned MAPbBr3@PVA nanofibers with a macroscale size of 0.5 cm × 2 cm,which allows potential applications in displays,lasers,waveguides,etc.

A cross-linked polyacrylamide electrolyte with high ionic conductivity for compressible supercapacitors with wide temperature tolerance

The development of compressible supercapacitors (SCs) that is tolerant to wide temperature range has been severely hindered due to the poor ionic conductivity and absence of extra functions in conventional polymer electrolytes.Herein,a highly conductive and compressible hydrogel polyelectrolyte has been prepared from polyacrylamide cross-linked by methacrylated graphene oxide (MGO-PAM) and the polyelectrolyte can maintain its excellent elasticity at-30 ℃ as well as its original shape at 100 ℃.As a result,the SC based on the MGO-PAM polyelectrolyte outperformed those fabricated with the conventional poly(vinyl alcohol)(PVA)/H2SO4 electrolyte over a wide temperature window between-30 and 100 ℃.Meanwhile,the device shows an excellent cycling stability (capacitance retention of 93.3% after 8,000 cycles at-30 ℃ and 76.5 % after 4,000 cycles under 100 ℃) and a reversible compressibility (a high capacitance retention of 94.1% under 80% compression).Therefore,the MGO-PAM polyelectrolyte enables the fabrication of compressible SCs with a wide operating temperature,rendering new insights for developing next-generation robust and multifunctional energy-storage devices.

Design and experiment of the comb-brush harvesting machine with variable spacing for oil-tea camellia fruit

Oil-tea camellia tree is an important oil plant in China that has long flexible branches.The most challenging feature for the mechanized harvest of oil-tea fruits is that its flower and fruit grow synchronously.In order to improve the harvesting efficiency and avoid damaging the flower bud,a hand-held fruit harvesting machine with a variable spacing comb brush was proposed.The harvesting machine can generate three kinds of actuation to detach fruit when it runs.The main actuation results from the brushing of multiple comb fingers.The other two kinds of actuation result from the beating of comb fingers on the fruits and the branches.The finger spacing of the comb brush can be adjusted consequently through moving the spacing adjusting crossbar.Hence,when the finger spacing is smaller than the diameter of the oil-tea fruit,the fruit is brushed off,but the flower bud and leaf pass through the finger gap.When the finger spacing is bigger than the fruit diameter,the fruit stuck between the fingers is loosened to ensure the continuous operation of the machine.Nylon was used as the material of the brush finger to avoid damage,which can also reduce the overall weight.The dynamic simulation of the harvesting machine was carried out with ADAMS,and the acceleration of the front end of the comb finger and the variation of the finger spacing were analyzed.The prototype of the harvesting machine was built and tested in the field.Field experiment results showed that when the speed of the comb finger drive shaft was 480 r/min,the average harvesting percentage of oil-tea fruit was 80%,and the flower bud was seldom detached,which met the working requirements of oil-tea fruit harvesting.

A NEW PRECONDITIONING STRATEGY FOR SOLVING A CLASS OF TIME-DEPENDENT PDE-CONSTRAINED OPTIMIZATION PROBLEMS

In this paper, by exploiting the special block and sparse structure of the coefficient matrix, we present a new preconditioning strategy for solving large sparse linear systems arising in the time-dependent distributed control problem involving the heat equation with two different functions. First a natural order-reduction is performed, and then the reduced- order linear system of equations is solved by the preconditioned MINRES algorithm with a new preconditioning techniques. The spectral properties of the preconditioned matrix are analyzed. Numerical results demonstrate that the preconditioning strategy for solving the large sparse systems discretized from the time-dependent problems is more effective for a wide range of mesh sizes and the value of the regularization parameter.