Review of Simultaneous Localization and Mapping Technology in the Agricultural Environment

Simultaneous localization and mapping(SLAM)is one of the most attractive research hotspots in the field of robotics,and it is also a prerequisite for the autonomous navigation of robots.It can significantly improve the autonomous navigation ability of mobile robots and their adaptability to different application environments and contribute to the realization of real-time obstacle avoidance and dynamic path planning.Moreover,the application of SLAM technology has expanded from industrial production,intelligent transportation,special operations and other fields to agricultural environments,such as autonomous navigation,independent weeding,three-dimen-sional(3D)mapping,and independent harvesting.This paper mainly introduces the principle,sys-tem framework,latest development and application of SLAM technology,especially in agricultural environments.Firstly,the system framework and theory of the SLAM algorithm are introduced,and the SLAM algorithm is described in detail according to different sensor types.Then,the devel-opment and application of SLAM in the agricultural environment are summarized from two aspects:environment map construction,and localization and navigation of agricultural robots.Finally,the challenges and future research directions of SLAM in the agricultural environment are discussed.

Lightweight Fish Bait Particle Counting Method Based on Pruning and Shift Quantization

In the process of aquaculture,monitoring the number of fish bait particles is of great significance to improve the growth and welfare of fish.Although the counting method based on onvolutional neural network(CNN)achieve good accuracy and applicability,it has a high amount of parameters and computation,which limit the deployment on resource-constrained hardware devices.In order to solve the above problems,this paper proposes a lightweight bait particle counting method based on shift quantization and model pruning strategies.Firstly,we take corresponding lightweight strategies for different layers to flexibly balance the counting accuracy and performance of the model.In order to deeply lighten the counting model,the redundant and less informative weights of the model are removed through the combination of model quantization and pruning.The experimental results show that the compression rate is nearly 9 times.Finally,the quantization candidate value is refined by introducing a power-of-two addition term,which improves the matches of the weight distribution.By analyzing the experimental results,the counting loss at 3 bit is reduced by 35.31%.In summary,the lightweight bait particle counting model proposed in this paper achieves lossless counting accuracy and reduces the storage and computational overhead required for running convolutional neural networks.

Current Situation and Development Proposals of Agricultural Facilities(Planting)Application in Beijing

Facility agriculture is an essential carrier for promoting stable production and supply.In2020,the planting area of facility agriculture in Beijing(290098000 m2)accounted for 29.06%of the total planting area of crops(998078000 m2),and the output value accounted for 46.56%.In2022,Beijing Agricultural Technology Extension Station organized relevant departments to summarize and evaluate the agricultural facilities in Beijing through consultation materials,interviews,questionnaires,and field trips,combining survey data and statistical data to draw the following conclusions.Facilities play a major supporting role in stabilizing production and ensuring supply.The number of traditional greenhouses is extensive and covers a large area,so special planning and classification upgrades are urgently needed.Facilities are rich in scientific and technological resources,but the mode of production is out of date.It is of great significance to improve the comprehensive production capacity of facility agriculture and promote the healthy and stable development of facility industry in Beijing to increase the utilization rate of facility agriculture land,strengthen the support of facility science and technology,and cultivate the socialized service organization of facility.

基于StaMPS-PS时序InSAR对流层延迟改正方法评估

时序分析是合成孔径雷达干涉测量(InSAR)的一项关键技术,它被广泛应用于监测广阔地区的地表缓慢形变。这种方法能够提供大范围、大面积的形变监测。其中,StaMPS PS方法凭借适用范围广、开源等优点,受到众多学者的使用。但在时序InSAR中,对流层延迟相位会导致形变监测精度的降低,因此,以合肥市为研究区域,分析了经验模型线性改正、GACOS(generic atmospheric correction online service for InSAR)改正和欧洲中期天气预报中心(ECMWF)最新发布的ERA5数据集改正,并对比这3种方法在时序InSAR反演形变速率中的改正效果。通过计算得到研究区的标准差,进行比较分析和验证。其中线性改正、ERA5和GACOS改正后的标准差分别降低了21.71%、16.14%、10.38%。对于合肥区域,这3种方法均可减弱对流层延迟的影响,且精度都有所提高,其中线性改正效果最好,适用性更高,ERA5和GACOS受天气以及地面监测点密度等影响,在该区域改正效果较差。

大径中厚壁管道坡口对MAG焊操作的影响

多层多道焊是核电大直径厚壁管道常用的焊接工艺,坡口形式作为影响焊道层数和道数的直接因素,不仅决定了生产成本和效率,还进一步影响着焊接过程中焊缝排道及焊枪的可操作性。采用TIG打底、MAG进行填充、盖面,分别对20°、15°和9°的U形坡口进行了试验,分析了不同坡口形式下的电弧稳定性、焊缝排道和焊枪可操作性。结果表明:坡口尺寸对电弧稳定性影响较小;15°的U形坡口既可以使电弧对坡口两侧壁进行相对充分的加热和填充,又可以保证较小的填充量,打底焊可操作性好、焊接效率高。

Replication Kinetics of Coxsackievirus A16 in Human Rhabdomyosarcoma Cells

Coxsackievirus A16(CVA16),together with enterovirus type 71(EV71),is responsible for most cases of hand,foot and mouth disease(HFMD) worldwide.Recent findings suggest that the recombination between CVA16 and EV71,and the co-circulation of these two viruses may have contributed to the increase of HFMD cases in China over the past few years.It is therefore important to further understand the virology,epidemiology,virus-host interactions and host pathogenesis of CVA16.In this study,we describe the viral kinetics of CVA16 in human rhabdomyosarcoma(RD) cells by analyzing the cytopathic effect(CPE),viral RNA replication,viral protein expression,viral RNA package and viral particle secretion in RD cells.We show that CVA16 appears to first attach,uncoat and enter into the host cell after adsorption for 1 h.Later on,CVA16 undergoes rapid replication from 3 to 6 h at MOI 1 and until 9 h at MOI 0.1.At MOI 0.1,CVA16 initiates a secondary infection as the virions were secreted before 9 h p.i.CPE was observed after 12 h p.i.,and viral antigen was first detected at 6 h p.i.at MOI 1 and at 9 h p.i.at MOI 0.1.Thus,our study provides important information for further investigation of CVA16 in order to better understand and ultimately control infections with this virus.

我院医疗耗材采购流程管理的实践探索

复旦大学附属华山医院通过统一招标平台、采用集中采购的模式和流程进行医疗耗材采购。通过流程管理,使医疗耗材采购的全过程公开、公正、公平;保障院内后勤保障部门(集中采购中心)按照采购计划,高效率、低成本地完成年度医疗耗材采购任务,为患者和医院获得性价比高的医疗耗材品种,保障医疗耗材的安全性、有效性和经济性。

基于零电流换流的TSMC-PMSM系统模型预测转矩控制

双级矩阵变换器输入功率因数可控、体积小、功率密度高等优点受到了国内外学者的广泛关注。有限集模型预测控制具有实时性强,算法简单等优点,非常适用于双级矩阵变换器。针对双级矩阵变换器预测转矩控制系统,通过引入占空比调制的思想,提出了一种零电流换流的方法,计算出每个控制周期内逆变级有效电压矢量的占空比,剩余的零矢量作用时间平均分配到逆变级有效电压矢量的两边,使整流级在逆变级零矢量作用期间完成换相,通过仿真结果验证了本文所提算法的正确性。

铝-空气电池阳极材料及其电解液的研究进展

金属-空气电池自进入人们的视野以来,由于其高能量密度和容量、平稳的放电特性、对负载和温度的依赖性低和较低的制造成本等特点,受到越来越多的关注。其中,锂-空气电池因具有极大的应用潜力而引起了学者们极大的研究兴趣;然而,锂-空气电池对周围环境十分敏感,容易造成爆炸,存在安全隐患;此外,锂离子电池的大规模生产和应用造成了原材料锂价格的大幅上涨。为了实现电池的商业化应用,选用来源广泛、经济实惠的电极材料成为必不可少的条件。铝是地壳中含量最多的金属元素,具有矿藏丰富、质量轻、无污染、安全、价格低廉和回收利用率高等优点,是一种潜在的储能材料。铝的理论质量比容量为2 980 mAh·g^(-1),仅次于锂(3 860 mAh·g^(-1)),其体积比容量(8.04 Ah·cm-3)约是锂的四倍(2.05 Ah·cm-3),被认为是金属-空气电池最有吸引力的候选阳极材料,也是化石燃料最有吸引力的替代者之一。然而,铝在空气和水溶液中表面上自发形成的钝化膜会显著降低铝阳极材料的活性;在碱性溶液中,铝-空气电池存在的主要问题是铝阳极材料自腐蚀导致氢析出速率较高,库伦效率降低和含水电解液的流动性可能导致的多孔空气阴极中毛细管的渗透及泄漏。因此,近年来,学者们不断开展深入研究,探索出以下几种改善铝阳极的方法:通过向铝中添加合金元素Ga、In、Sn、Zn、Mg、Bi、Mn等来改变铝阳极材料的活性和减少析氢反应;对电解液添加剂进行研究,发现部分植物提取液作为电解液添加剂可以保持铝阳极活性,降低析氢腐蚀;开发离子液体、固态和凝胶电解液,一方面可以减小铝阳极自腐蚀,提高阳极利用率,另一方面可减小铝-空气电池体积,增加电池的灵活性。目前研究获得性能较好的碱性铝-空气电池的阳极材料有Al-Ga/In-Mg系列、Al-Ga/In-Mg-Sn系列、Al-Ga-In-Bi-Pb系列等合金,其中部分铝阳极合金已经实现了实际应用。近几年研究工作获得了羽扇豆提取物、茄属植物叶的提取物等绿色电解液添加剂,其可以保持铝阳极的电化学活性,降低腐蚀率。此外,研究发现,室温下低聚氟化氢离子液体作为电解液可以活化铝阳极,降低其腐蚀速率,一些便携式铝-空气电池采用固态或凝胶电解液已经在护理医疗设备、商用LED手表方面应用。本文主要从铝阳极材料、电解质和电解质添加剂三方面论述了其对铝-空气电池性能的影响,并简单阐述了铝-空气电池放电的基本原理、面临的挑战和最新研究进展及应用。首先,综述了铝与合金元素的合金化,以此减少铝的自腐蚀,提高电池性能;并介绍了通过一定的加工工艺来改善铝阳极电化学性能的方法。其次,探讨了水溶剂电解质和非水溶剂电解质在铝-空气电池中的应用。同时,也研究了电解质添加剂对铝-空气电池的电化学性能的影响。最后,进一步明确了空气电池未来的研究和发展方向。

基于图卷积的骨架行为识别

近年来,随着视频大规模增长,如何高效组织和分析这些海量视频,面临巨大的挑战,而人作为视频中的主体,如何有效分析其行为,成为学术界研究的一个热点。通过利用OpenPose,提取视频中人体的动态骨架序列,采用基于图卷积神经网络的方法,借助在大规模视频动作数据集上训练好的模型进行迁移学习,所提出的方法在自采集的室内监护视频数据集上,取得0.9的识别准确率。

304L不锈钢薄壁小径管焊缝的相控阵超声检测工艺

采用相控阵超声检测技术,通过声学特性分析、模拟仿真、试块设计和验证试验,对304L不锈钢薄壁小径管焊缝的相控阵超声检测进行了研究。试验结果表明,对于未熔合、未焊透、裂纹等面积型缺陷,相控阵超声和射线检测的检出率均为100%。对于体积型缺陷,相控阵超声检测能力和射线检测相当;对于直径0.5 mm以下的小缺陷,受缺陷形貌、性质的影响,其反射波幅存在一定偏差。另外,相控阵超声检测的可达性和自检测效率优于射线检测的,且具有可进行交叉施工,结果数据可复查,数据重复性好,无辐射风险。

BAS监控系统在医院中的具体应用与效果分析

以复旦大学附属华山医院北院的应用实践为例,介绍了BAS系统的部分功能,阐述了系统提供的节能措施,并分析了节能效果。

Design and Realization of a Novel Hybrid-Drive Robotic Fish for Aquaculture Water Quality Monitoring

Thunniform swimmers(tuna)have a swinging narrow sequence stalk and a moon-shaped tail fin,which performs poorly at slow speed,higher acceleration and turning maneuverability.In most cases,faster speed and higher maneuverability are mutually rejection for most marine creatures and their robotic opponents.This paper presents a novel hybrid tuna-like swimming robot for aquaculture water quality monitoring,which interleaves faster speed and higher maneuverability.The robotic prototype emphasizes on streamlining and enhanced maneuverability mechanism designs in conjunction with a narrow caudal propeller to the tail.The innovative design endows the robot to easily execute the multi-mode swimming gait,including forward swimming,turning,diving/surfacing.The capabilities of our robot are validated through a series of indoor swimming pool and field breeding ponds.The robotic fish can achieve a maximum speed up to about 1.16 m/s and a minimum turning radius less than 0.46 Body Lengths(BL)and its maximum turning speed can reach 78.6∘/s.Due to its high speed,maneuverability and relatively small size,the robotic fish shed light on intelligent monitoring in complex aquatic environments.

Spatiotemporal expression of leukemia inhibitory factor receptor protein during neural tube development in embryos with neural tube defects

Leukemia inhibitory factor receptor(LIFR),as a neuroregulatory cytokine receptor,generally shows a neuroprotective effect in central nervous system injuries.In this study,to understand the effect of LIFR on pathogenesis of neural tube defects,we explored spatiotemporal expression of LIFR at different stages of fetal development in normal and neural tube defect embryos.Spina bifida aperta was induced with all-trans retinoic acid on embryonic day 10 in rats,and the spatiotemporal expression of LIFR was investigated in spina bifida aperta rats and healthy rats from embryonic day 11 to 17.Real time-polymerase chain reaction and western blot assay were used to examine mRNA and protein expression of LIFR in healthy control and neural tube defect embryos.Results of the animal experiment demonstrated that expression of LIFR protein and mRNA in the spinal cords of normal rat embryos increased with embryonic development.LIFR was significantly downregulated in the spinal cords of spina bifida aperta rats compared with healthy rats from embryonic days 11 to 17.Immunohistochemical staining showed that the expression of LIFR in placenta and spinal cord in spina bifida aperta rat embryos was decreased compared with that in control embryos at embryonic day 15.Results from human embryo specimens showed that LIFR mRNA expression was significantly down-regulated in spinal cords of human fetuses with neural tube defects compared with normal controls at a gestational age of 24 to 33 weeks.The results were consistent with the down-regulation of LIFR in the animal experiments.Our study revealed spatiotemporal changes in expression of LIFR during embryonic neurulation.Thus,LIFR might play a specific role in neural tube development.All animal and human experimental procedures were approved by the Medical Ethics Committee of Shengjing Hospital of China Medical University,China(approval No.2016PS106K)on February 25,2016.

A Novel Aquila Optimizer Based PV Array Reconfiguration Scheme to Generate Maximum Energy under Partial Shading Condition

This paper develops a real-time PV arrays maximum power harvesting scheme under partial shading condition(PSC)by reconfiguring PV arrays using Aquila optimizer(AO).AO is based on the natural behaviors of Aquila in capturing prey,which can choose the best hunting mechanism ingeniously and quickly by balancing the local exploitation and global exploration via four hunting methods of Aquila:choosing the searching area through high soar with the vertical stoop,exploring in different searching spaces through contour flight with quick glide attack,exploiting in convergence searching space through low flight with slow attack,and swooping through walk and grabbing prey.In general,PV arrays reconfiguration is a problem of discrete optimization,thus a series of discrete operations are adopted in AO to enhance its optimization performance.Simulation results based on 10 cases under PSCs show that the mismatched power loss obtained by AO is the smallest compared with genetic algorithm,particle swarm optimization,ant colony algorithm,grasshopper optimization algorithm,and butterfly optimization algorithm,which reduced by 4.34%against butterfly optimization algorithm.

“署脆红”桃配套栽培技术

“署脆红”桃果大,全红,硬溶质,耐贮,产量高。为了能更好的栽培“署脆红”桃,本文结合其主要特性,从建园地选择、种植方法、土肥水管理、树体管理、花果管理、病虫害防治、适时采收等方面阐述相关要点,为种植者提供参考。

大型隔膜压滤机在酱油行业中的应用

本文介绍了隔膜压滤机的工作原理和在酱油压榨中的工艺流程,针对工艺流程分析了影响生产产量和质量的因素,并对影响产量和质量的因素开展了正、负相关性研究。根据研究对隔膜压滤机的选型给出了指导意见。

Advances in crop phenotyping and multi-environment trials

Efficient evaluation of crop phenotypes is a prerequisite for breeding, cultivar adoption, genomics and phenomics study. Plant genotyping is developing rapidly through the use of high-throughput sequencing techniques,while plant phenotyping has lagged far behind and it has become the rate-limiting factor in genetics, large-scale breeding and development of new cultivars. In this paper,we consider crop phenotyping technology under three categories. The first is high-throughput phenotyping techniques in controlled environments such as greenhouses or specifically designed platforms. The second is a phenotypic strengthening test in semi-controlled environments, especially for traits that are difficult to be tested in multi-environment trials(MET), such as lodging, drought and disease resistance. The third is MET in uncontrolled environments, in which crop plants are managed according to farmer's cultural practices. Research and application of these phenotyping techniques are reviewed and methods for MET improvement proposed.

Identification of maize seed varieties based on near infrared reflectance spectroscopy and chemometrics

False seeds can often be seen in the maize seed market,leading to a serious decline in maize yield.Those existing variety identification methods are expensive,time consuming,and destructive to seeds.The aim of this study is to develop a cheap,fast and non-destructive method which can robustly identify large amounts of maize seed varieties based on near-infrared reflectance spectroscopy(NIRS)and chemometrics.Because it is difficult to establish models for every variety in the market,this study mainly investigated the performance of models based on a large number of samples(more than 40 major varieties in the market).The reflectance spectra of maize seeds were collected by two modes(bulk kernels mode and single kernel mode).Both collection modes can be applied to identification,but only the single kernel mode can be applied to purity sorting.The spectra were pretreated with smoothing,the first derivative and vector normalization;and then principal component analysis(PCA),linear discriminant analysis(LDA)and biomimetic pattern recognition(BPR)were applied to establish identification models.The environmental factors such as producing areas and years have a significant influence on the performance of the models.Therefore,the method to improve the robustness of the models was investigated in this study.New indexes(correct acceptance degree(CAD),correct rejection degree(CRD)and correct degree(CD))were defined to analyze the performance of the models more accurately.Finally,the models obtained a mean correct discrimination rate of over 90%,and exhibited robust properties for samples harvested from different areas and years.The results showed that NIR technology combined with chemometrics methods such as PCA,LDA,and BPR could be a suitable and alternative technique to identify the authenticity of maize seed varieties.

Elimination of a Retrotransposon for Quenching Genome Instability in Modern Rice

Transposable elements(TEs)constitute the most abundant portions of plant genomes and can dramatically shape host genomes during plant evolution.They also play important roles in crop domestication.However,whether TEs themselves are also selected during crop domestication has remained unknown.Here,we identify an active long terminal repeat(LTR)retrotransposon,HUO,as a potential target of selection during rice domestication and breeding.HUO is a low-copy-number LTR retrotransposon,and is active under natural growth conditions and transmitted through male gametogenesis,preferentially inserting into genomic regions capable of transcription.HUO exists in all wild rice accessions and about half of the archaeological rice grains(1200–7000 years ago)and landraces surveyed,but is absent in almost all modern varieties,indicating its gradual elimination during rice domestication and breeding.Further analyses showed that HUO is subjected to strict gene silencing through the RNA-directed DNA methylation pathway.Our results also suggest that multiple HUO copies may trigger genomic instability through altering genome-wide DNA methylation and small RNA biogenesis and changing global gene expression,resulting in decreased disease resistance and yield,coinciding with its elimination during rice breeding.Together,our study suggests that negative selection of an active retrotransposon might be important for genome stability during crop domestication and breeding.