基于自适应多特征融合的路沿检测与跟踪方法研究

为减少路沿检测过程中存在的误检和漏检,以三维激光雷达为传感器,提出了一种新的路沿检测与跟踪方法。首先,对点云进行预处理,采用基于距离的滤波器对原始点云中存在的影响特征提取的干扰点进行滤除,以提高路沿点的提取精度,对滤波后的点云,采用地面平面分段拟合的地面分割方法提取地面点云;然后,利用高度差、平滑度与角度阈值等路沿空间特征,设计了一种自适应多特征融合的路沿点提取算法;其次,针对由障碍物遮挡所造成的部分路沿缺失问题,利用饶-布莱克维尔化粒子滤波跟踪器对路沿点进行跟踪预测;最后,将该方法应用于无人环卫车进行了多工况实验,结果表明该方法能准确地检测出道路的边界信息,有效地减少了路沿点的误检和漏检。

The bacterial diversity and community composition altered in the oxygen minimum zone of the Tropical Western Pacific Ocean

The oxygen minimum zones(OMZs)are globally expanding,yet the variation pattern of microbial communities related to dissolved oxygen levels remain unclear.Spatial variability of bacterial diversity and community composition(repre sented by 16 S rRNA)of six stations was investigated within the water column in the seamount area of Tropical Western Pacific Ocean(TWPO)in May 2019.The seawater has dissolved oxygen(DO)concentration of 3.01-6.68 mg/L and the core of the oxygen minimum zones was located between the depths of 650 m and 1750 m.The bacterial alpha-diversity showed unimodal pattern with the decreasing DO with depths and peaked in the upper oxycline(UO)of OMZs.The bacterial community structure of the mixed layer(ML)and the bottom layer clustered and separated from each other,while those of UO and the OMZ core(OM)clustered and overlapped.Overall,bacterial community composition transitioned from being Alphaproteobacteria and Gammaproteobacteria-dominant in ML to being Gammaproteobacteria and Nitrososphaeria/Deltaproteobacteria-dominant in UO and OM,and then changed to being Clostridia and unidentified Actinobacteria-dominant in the bottom layer.Moreover,both bacterial alpha-diversity and the abundant classes fitted varying sectioned functions with DO.The DO solely explained 40.37%of the variation of bacterial community composition among layers(P<0.001).The predicted function profiling showed that the water column was predominant by chemoheterotrophy,cyanobacteria,and photoautotrophy in ML,by chemoheterotrophy and nitrate/sulfide cycling in UO and OM,and by chemoheterotrophy and ferme ntation in the bottom layer.Our findings revealed the DO-associated variation in bacterial diversity and community composition,and help to clarify the potential responses of microbes and their involved biogeochemical processes to the expansion and intensification of OMZs.

Characteristics and biogeochemical effects of oxygen minimum zones in typical seamount areas,Tropical Western Pacific

As a serious consequence of ocean warming and increased stratification,a rapid decrease in dissolved oxygen(DO)content of the world’s oceans has attracted more and more attention recently.In open oceans,the decline of DO is characterized by the expansion of oxygen minimum zones(OMZs)in the ocean interior.Vast OMZs exist within the mesopelagic zones of the Tropical Western Pacific(TWP),but have gained very little attention.In this study,we focus on characteristics of OMZs in three typical seamounts areas(named Y3,M2,and Kocebu,respectively)of the TWP.Based on distributions of DO,the OMZs of the three seamounts areas are very different in scope,thickness,and the minimum oxygen content.The significantly different characteristics of OMZs at the seamounts are mainly because they are located in regions affected by different ventilation and consumption characteristic.To quantitatively describe the intensity of OMZs,a parameter,IOMZ,is firstly proposed.According to this quantitative parameter,the intensity order of OMZs for the three seamounts areas is Kocebu>M2>Y3.Potential biogeochemical effects of OMZs in the three seamounts areas are discussed using IOMZ.With higher IOMZ,the degradation of particulate organic carbon(POC)tends to be lower.Yet because of the limited data,their relationship still need more research to prove.However,if this relationship holds in global oceans,the presence of seamounts would—under climate warming with expanding OMZs—promote vertical transport of POC resulting in an enhanced biological pump.Our study provides a new way to quantitatively study the impact of OMZs on the efficiency of biological pump.

Analysis of differences in nutrients chemistry in seamount seawaters in the Kocebu and M4 seamounts in Western Pacific Ocean

Comprehensive surveys were conducted in the Kocebu deep seamount and the M4 shallow seamount in the Western Pacific Ocean in March 2018 and May 2019,respectively.The distributions of nutrients in euphotic zone of the two seamount-areas were revealed,and the causative controlling factors were analyzed.Results show that the vertical distribution of nutrients in the two seamount-areas accorded with the general law of the oligotrophic ocean.The concentrations of NO_(3)-N,PO_(4)-P,and SiO_(3)-Si generally increased gradually with the increase of water depth,and they were extremely low in water layers within100 m.The area of high NO_(2)-N concentration well agreed with the Deep Chlorophyll Maximum Layer.On the other hand,the distribution of water masses and phytoplankton and hydrological conditions in the two seamount-areas were different,resulting in lower concentrations of NO_(3)-N,PO_(4)-P,and SiO_(3)-Si in the water layers below 100 m in the Kocebu seamount area than those in the M4 seamount area.In addition,NO_(2)-N was affected by the distribution of phytoplankton,and distributed mainly in the water layers of 150 and100 m.There was upwelling in the euphotic zone of M4 seamount area,causing accumulations of nutrients and phytoplankton around the seamount,forming a"seamount effect";however,no such an effect was found in Kocebu seamount area.Affected by the composition of biological community and the"seamount effect",the nitrogen limitation in the M4 seamount area was not significant,and the dissolved inorganic nitrogen(DIN):PO_(4)-P and SiO_(3)-Si:DIN were closer to the Redfield ratios.

工程与材料科学部重大项目立项与管理机制改革探索及思考

国家自然科学基金重大项目是国家自然科学基金委员会(简称“自然科学基金委”)资助体系中重要的项目类型之一,在发挥学科支撑和引领作用、推动产生原创性重大成果方面具有重要战略地位。本文全面回顾并分析了工程与材料科学部重大项目资助现状,重点阐述了当前在立项与管理机制方面存在的一些问题,阐明了重大项目深化改革的必要性和紧迫性,介绍了自然科学基金委工程与材料科学部的具体改革思路和举措,以及进行的实践和探索,提出了一些思考,为新时期国家自然科学基金重大项目深化改革提供了重要参考。

丹江口水库鱼类群落特征及其历史变化

为了解丹江口水库鱼类群落现状及历史变化,作者于2018–2019年采用多网目复合刺网采样和渔民渔获物调查的方式对丹江口水库进行了鱼类群落调查。本次调查共采集鱼类33种,隶属5目11科29属,以鲤科鱼类为主,占总数的63.6%。基于多网目复合刺网采样的鱼类群落多样性指数和单位努力捕捞量(catch per unit effort,CPUE,g·day^(-1)·m^(-2))在各采样点间具有一定的差异。目前丹江口水库以定居性、喜静缓流、杂食性和肉食性鱼类为主。与20世纪50年代和80年代的历史资料相比,丹江口水库鱼类物种丰富度先升高后下降;而生态类型则呈现杂食性鱼类、喜流水性鱼类和洄游性鱼类比例持续下降的趋势。2018–2019年丹江口水库鱼类组成与20世纪80年代的相似性指数为0.35(中等不相似),与20世纪50年代的相似性指数为0.29(中等不相似)。调查结果表明半个世纪以来丹江口水库鱼类群落结构发生了较大变化,目前趋于小型化和简单化。这些变化可能是由大坝建设、渔业放养、不合理捕捞、外来鱼类引入等人类活动所致。

A new mechanism of atmospheric CO2 absorption promoted by iron-nitrogen coupling in low-latitude oceans during ice age

It has been confirmed by a large number of studies that iron can significantly improve the carbon fixation level in the high-latitude oceans (Martinez-Garcia et al., 2014). Although there are many studies on the mechanism of ironcarbon coupling in the modem ocean, the research on ironnitrogen-carbon coupling is rare (Tagliabue et al., 2014;Song, 2010). It is of great significance for the prediction of future ocean changes to identify the key processes of modem ocean and analyze the past ocean changes.

Neighborhood form and CO2 emission： evidence from 23 neighborhoods in Jinan, China

To understand the household C02 emission level in China, as well as how much the neighborhoods＇ socio-economic or design factors could influence the CO2 emission, 23 neighborhoods in Jinan were investigated in 2009 and 2010. These neighborhoods fall into four different types： superblock, enclave, grid and traditional. The household CO2 emission includes sources of both in- home energy use and passenger transportation. The average CO2 emission per household is 7.66 t.a^-1, including 6.87 t in-home operational emission and 792 kg transportation emission. The household CO2 emission by neighborhood categories is 10.97, 5.65, 6.49, 5.40 t-household-1. a-1 for superblock, enclave, grid and tradi- tional respectively. Superblock has the highest average emission and also the highest percent （more than 25%） of transportation emission among four different types of neighborhoods. The residential CO2 emission of superb- lock neighborhoods in Jinan has already reached the level in developed countries nearly ten years ago. It is predictable that more superblock neighborhoods would be built in China with the fast urbanization. How to avoid the rapid household CO2 emission growth in the future would be a systematic issue. The study also found that in addition to income and apartment area, household density, land use mix and accessibility to public transportation are three primary factors which have significant impacts on CO2 emission. High density, mixed land use and convenient accessibility to public transportation tend to reduce household CO2 emission.