基于地基激光雷达监测不同地表覆盖条件的土壤侵蚀试验研究

土壤侵蚀量是土壤退化风险评估的重要指标,地基激光雷达(TLS)为土壤侵蚀量动态监测提供新技术手段,但野外不同地表覆盖条件对监测精度的影响尚不明确。基于2019年11月和2021年7月在鹰潭红壤生态实验站获取的地表裸露、石块、稀疏象草、马尾松、马尾松+石块,马尾松+稀疏象草等不同地表覆盖条件的6个径流小区两期TLS数据,运用移动曲面拟合滤波和反距离加权插值方法估算土壤侵蚀量,结合实测侵蚀量数据评价TLS精度,并探讨不同地表覆盖条件下TLS的最小变化识别度(minLOD)。研究表明,TLS监测精度与土壤侵蚀量呈正相关关系,更适用于中等强度以上或长时间发生明显侵蚀的土壤侵蚀区监测。不同地表覆盖条件下minLOD为4～60 mm,TLS监测相对误差(RE)依次为：地表裸露(RE=–9.4%)<马尾松+石块(RE=12.6%)<石块(RE=15.5%)<稀疏象草(RE=–18.9%)<马尾松(RE=23.4%)<马尾松+稀疏象草(RE=–25.2%);地表覆盖条件不仅影响土壤侵蚀强度、地表粗糙度,也产生点云滤波及空间插值误差,进而影响TLS识别minLOD准确度和土...     

基于光学和超声联合定位的精密播种机导航技术研究

为了提高播种机的自主化作业水平,将光学和超声联合定位方法引入到了播种机导航系统的设计上,通过超声波测距和激光扫描的方法,实现了作业区域的定位和播种机行走路径的规划,从而提高了播种机作业的适应能力,提升了自主作业水平.为了验证方案的可行性,对基于光学和超声联合定位的导航系统进行了实验,并建立了一个有田垄的农田作业环境,展...     

脐橙表面农药残留的计算机视觉检测方法研究

经不同种类农药处理后,采集脐橙激光散射图像,通过对表面是否喷洒农药,以及表面喷洒不同种类农药的水果图像进行处理,用一元非线性方程拟合脐橙图像灰度值分布曲线。结果表明,脐橙图像灰度值在10~100范围内的灰度曲线拟合模型与农药残留是密切相关的,能用于区分脐橙表面是否存在农药残留。     

基于激光诱导击穿光谱的地下水中Fe和Mn的检测

采用激光诱导击穿光谱(LIBS)技术并结合在锌基板上液固转换的样品处理方法,对标准水溶液样品中Fe、Mn进行检测,并根据标准曲线法建立Fe、Mn的定量模型;再利用所建立的LIBS定量模型,对洞庭湖区地下水实际水样中Fe、Mn含量进行检测,并与电感耦合等离子体质谱法(ICP–MS)的检测结果进行比较。结果表明：得到Fe、Mn的LIBS定标曲线的决定系数均大于0.98,相对标准偏差均为4.3%,留一交叉验证均方根误差分别为0.024、0.007 mg/L,Fe、Mn的检出限分别为0.028、0.008 mg/L;采用LIBS对洞庭湖地下水实际水样中Fe、Mn含量检测的结果与ICP–MS的检测结果基本一致,平均相对误差小于10%。     

Evidence of diadromy in the French Polynesian Kuhlia malo (Teleostei: Percoidei) inferred from otolith microchemistry analysis

Abstract – Strontium/Calcium (Sr/Ca) and Barium/Calcium (Ba/Ca) ratios were measured in 60 otoliths of the French Polynesian flagtail Kuhlia malo. Both elemental ratios were needed to correctly distinguish residence in marine, brackish and fresh water. High Sr/Ca and low Ba/Ca around the nucleus of all otoliths provided evidence of marine residency during the early life of all individuals. At about 0.5 mm from the core, Ba/Ca increased rapidly and remained high in all otoliths. High and unstable Sr/Ca ratios were attributed to estuarine residency, whereas low and stable Sr/Ca ratios were attributed to freshwater residency. These chemical signatures inferred that following recruitment to rivers, some fish remained in the estuary, while others moved upstream. Some individuals shared their time between fresh and brackish waters later in life. The findings of this study have important implications for the protection of nearshore, brackish and freshwater environments for the conservation of this French Polynesian diadromous species.     

Characterization of mobile LiDAR data collected with multiple echoes per pulse from crowns during foliation

Abstract

As a state-of-the-art technology for fine-scale forest investigation, mobile terrestrial light detection and ranging (LiDAR), also referred to as mobile laser scanning (MLS), recently has been increasingly exploited to improve its performance on this task. One potential solution is to apply special MLS systems with the capability of collecting multiple echoes per pulse (multi-echoes, for short) from canopies. The methodologies of this rationale turned out to perform better but still insufficiently for canopy properties retrieval, owing to their common defective premise. That is, the knowledge of the characteristics of MLS scan data comprising multi-echoes, so far, is in shortage, especially when regarding the dynamic process of tree foliation. As a pioneering work for this challenge, this study attempted to comprehensively analyze the characteristics of MLS multi-echoes collected from tree crowns during foliation. Specifically, new stable multi-echoes-related features were deduced under the schematic frame of relative quantification, in both spatial and temporal sense. “Relative” here briefly means the division operation deployed on the attributes of multi-echoes, individually in terms of the number of echoes, echo width and crown volume integrity, between their different return orders. Then, the “relative” schematic was primarily validated for more stably representing crown properties during foliation, based on the real data that was collected by the Sensei MLS system with a maximum of three echoes per pulse. Further, a case of tree species classification was examined using a linear discriminant classifier, and it was testified that the resultant temporal statistical rules of multi-echoes as the reverse clues can enhance the performance of MLS in applications.     

不同腔长下调Q激光器输出脉冲特性研究

从Nd3+:YAG脉冲激光器调Q技术出发,研究了不同腔长条件下电光调Q激光器输出脉冲的宽度、能量和峰值功率特征,得到了不同腔长的调Q激光器输出脉冲特性曲线。研究结果表明,激光器腔长的改变能较好地调节脉冲的输出特性,对脉冲激光器的灵活应用具有一定的指导意义。     

Inhibitory effects of furanone metabolites of a rhizobacterium, Pseudomonas jessenii, on phytopathogenic Aphanomyces cochlioides and Pythium aphanidermatum

An antagonistic rhizobacterium, Pseudomonas jessenii EC-S101, isolated from the rhizosphere of spinach, produces two related secondary metabolites, 3-[(1 R )-hydroxyoctyl]-5-methylene-2(5 H )-furanone (4,5-didehydroacaterin) (1) and 3-[(1 R )-hydroxyhexyl]-5-methylene-2(5 H )-furanone (2). This study demonstrated their in vitro inhibitory effects, in particular those of (1), against Aphanomyces cochlioides AC-5 and Pythium aphanidermatum PA-5. The compounds inhibited radial growth and induced morphological abnormalities characterized by hyperbranching and periodic swelling in AC-5 and PA-5 hyphae, respectively. Staining with rhodamine-phalloidin, which binds to plasma-membrane-associated filamentous-actin (F-actin), revealed that tip-specific actin filaments were remodelled into a plaque-like form at an early stage of encounter (up to 24 h) with (1) or (2), whereas at later stages of encounter (48 h), the plaques were eliminated, reflecting the disorganization of actin arrays in the morphologically abnormal AC-5 and PA-5 hyphae. A similar response of actin disorganization was observed in AC-5 and PA-5 hyphae upon treatment with latrunculin B (3), an actin-assembly inhibitor produced by a sea sponge. It is suggested that (1) and (2) caused actin disorganization and their inhibitory activities were comparable to that of (3). Further ultrastructural observations substantiated abnormal functioning and delocalization of F-actin-linked cell organelles.     

He—Ne激光照射对牛超排效果的影响机理

试验采用Ｈｅ－Ｎｅ激光穴位照射供体母牛，并结合纯化ＦＳＨ超排处理，以研究激光照射对牛超排效果的影响机理。结果表明：①Ｈｅ－Ｎｅ激光照射可提高牛超排效果，增加胚胎数和可用胚胎数，试验组头均胚胎数比对照组多２．２枚，头均可用胚胎数比对照组多１．９枚，差异显著（ｐ〈０．０５）；②Ｈｅ－Ｎｅ激光照射通过神经和体液调节，可显著提高血浆中ＦＳＨ（促卵泡素）水平，而ＦＳＨ水平升高是促使供体母牛卵泡发育，增加胚胎     

Cutting weeds with a CO2 laser

Stems of Chenopodium album . and Sinapis arvensis . and leaves of Lolium perenne . were cut with a CO₂ laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose–response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO₂ laser than C. album . When stems were cut below the meristems, 0.9 and 2.3 J mm⁻¹ of CO₂ laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close to the soil surface to obtain a significant effect. When cutting L. perenne plants with 2-true leaves at a height of 2 cm from the soil surface with a laser, the biomass decreased significantly compared with plants cut by scissors, indicating a delay in regrowth. This delay was not observed for the dicotyledonous plants nor for the other growth stages of L. perenne .