Information on which weed species are present within agricultural fields is important for site specific weed management. This paper presents a method that is capable of recognising plant species in ...colour images by using a convolutional neural network. The network is built from scratch trained and tested on a total of 10,413 images containing 22 weed and crop species at early growth stages. These images originate from six different data sets, which have variations with respect to lighting, resolution, and soil type. This includes images taken under controlled conditions with regard to camera stabilisation and illumination, and images shot with hand-held mobile phones in fields with changing lighting conditions and different soil types. For these 22 species, the network is able to achieve a classification accuracy of 86.2%.
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•A convolutional neural network is designed to determine the species of seedlings.•The system is trained and tested on images of 22 plant species.•The images are taken under a variate of different lightning and soil conditions.•In total 86.2% the plants were classified correctly.
Atmospheric concentrations of organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs) and neutral per- and polyfluoroalkyl substances (PFAS) have been measured at Villum Research ...Station, Station Nord (North Greenland) in the period 2008–2013. Atmospheric concentrations of OCPs at the same site have been previously reported for the years 2008–2010. The detection frequency and the average concentrations of OCPs have not significantly changed since the previous study. PBDE congeners (∑13PBDEs) were measured for the first time in North Greenland at concentrations similar to those observed for other remote sites, confirming that these compounds are ubiquitous in the Northern Hemisphere. The ∑13PBDEs concentration ranged from not detected (n.d.) to 6.26 pg m−3. The BDE congeners found in more than 30% of the samples were BDE-17, BDE-28, BDE-47, BDE-71, BDE-99 and BDE-100. Also for neutral PFAS we present for the first time a multiyear series of measurements for North Greenland. The average sum of the seven measured neutral PFAS (∑7PFAS) ranged from 1.82 to 32.1 pg m−3. The most abundant compound was 8:2 FTOH (44% of ∑7PFAS), followed by 6:2 FTOH and 10:2 FTOH. Perfluoroalkyl sulfonamides (FOSA) and perfluoroalkyl sulfonamidoethanols (FOSE) were also detected but at much lower concentrations than FTOHs.
Temporal trends were investigated for all measured compounds but no significant trend in concentration was observed. Monthly average concentrations for the six years were calculated for each compound and the seasonal variation was investigated. Some OCPs and FTOHs showed seasonal variations, and in most cases a maximum was found during summer.
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•PBDEs and neutral PFASs are reported for the first time in the atmosphere of North Greenland.•Atmospheric concentrations of POPs do not show any trend in the period 2008–2013.•Some compounds showed seasonal variations, and in most cases a maximum was found during summer.•Temperature dependency was observed for a few of the investigated compounds.
Chlorinated pesticides, polybrominated- and polyfluorinated compounds have been measured in the atmosphere of North Greenland in the years 2008–2013.
A k‐means cluster analysis of a 5‐year aerosol particle size distribution data set from northeast Greenland is combined with measurements of coincident shorter field studies of aerosol equivalent ...black carbon (eBC) content, hygroscopic growth factor (HGF), and cloud condensation nuclei (CCN) concentrations. This led to five clusters strongly controlled by natural emissions (eBC 8–15 ng/m3) and three anthropogenic clusters with larger particle concentrations in the accumulation mode (eBC 29–77 ng/m3). The HGF and CCN properties of the eight aerosol clusters differ drastically. Anthropogenic clusters feature high growth factors (1.62–1.81) and low CCN κ values (0.10–0.46), while natural clusters show lower HGF (1.38–1.70) but remarkably higher κ values (0.35–0.51). Extrapolating the CCN properties on the basis of the cluster analysis to annual timescales suggests that biogenic organic aerosol may drive Arctic aerosol production during summer.
Plain Language Summary
The variability of the warming Arctic—particularly the decreasing sea ice extent—is likely to boost the control of the ocean on the atmospheric composition. Key factors controlling Arctic aerosol‐climate interactions are sources, chemical transformations, and removal mechanisms of aerosols and their precursor gases. However, knowledge on the composition and sources of summer aerosols is insufficient. To tackle this problem, we use an approach where aerosol particle size distributions, aerosol equivalent black carbon, hygroscopic growth factor, and cloud condensation nuclei measurements at Villum Research Station within the period 2012–2016 are synergistically combined. Our results suggest that marine sources of new particle formation and growth dominate summer Arctic background conditions. These aerosols are organic rich in nature. Elevated cloud condensation nuclei concentrations occurred when secondary Arctic biogenic organic aerosols were detected.
Key Points
An extended analysis of marine biogenic new particle formation and growth dominating summer Arctic background conditions is presented
Direct measurements of low aerosol hygroscopic growth factors (HGFs) dominate the aerosol ultrafine population—aerosols is organic rich
Elevated cloud condensation nuclei concentrations occurred when Arctic background biogenic aerosols—secondary in origin—were detected
In this paper, three model-based fault diagnosis algorithms for robotic systems are designed, compared, simulated, and implemented. The first algorithm is based on a nonlinear adaptive observer ...(NLAO), where a sufficient condition for the convergence of the estimator is derived in terms of linear matrix inequality (LMI) under persistence of excitation condition. The second algorithm is based on an adaptive extended Kalman filter (AEKF). Unlike traditional approaches, where the fault parameters are considered as augmented state variables, the AEKF directly estimates the fault parameters from measurement data. The third algorithm is based on a cascade of a nonlinear observer (NLO) and a linearized adaptive Kalman filter (LAKF), called the adaptive exogenous Kalman filter (AXKF). The pros and cons for each algorithm are discussed. The performance of the algorithms is compared in a single-link joint robot system. Furthermore, the algorithms are implemented in a ball-balancing robot to detect and estimate the magnitude of the actuator faults.
Classroom Shared Drawing (CSD) er et program, hvor undervisere kan lade studerende svare ved at tegne individuelt eller gruppevis. De studerendes svar samles i lag, så man hurtigt kan se de ...studerendes forståelser og misforståelser af et givent fagligt område eller spørgsmål og hvor mange svar der afviger fra det korrekte. De studerendes svar er anonyme, men kan også gøres ikke-anonyme og dermed tjene som en form for summativ evaluering eller screening. Programmets største styrke er dog som formativt evalueringsredskab, da det kan anvendes løbende i undervisningen til at afdække de studerendes viden og færdigheder. Programmet kan anvendes på flere taksonomiske niveauer og egner sig ikke kun som redskab i fag, hvor det at tegne udgør en del af fagligheden (f.eks. matematik og fysik) ifm. grafer, men kan med fordel anvendes i alle fag, hvis man eksempelvis vil bede studerende om at forbinde det korrekte svar til det stillede spørgsmål med streger.
Recently, the term smartphone photogrammetry gained popularity. This suggests that photogrammetry may become a simple measurement tool by virtually every smartphone user. The research was undertaken ...to clarify whether it is appropriate to use the Structure from Motion-Multi Stereo View (SfM-MVS) procedure with self-calibration as it is done in Uncrewed Aerial Vehicle photogrammetry. First, the geometric stability of smartphone cameras was tested. Fourteen smartphones were calibrated on the checkerboard test field. The process was repeated multiple times. These observations were found: (1) most smartphone cameras have lower stability of the internal orientation parameters than a Digital Single-Lens Reflex (DSLR) camera, and (2) the principal distance and position of the principal point are constantly changing. Then, based on images from two selected smartphones, 3D models of a small sculpture were developed. The SfM-MVS method was used, with self-calibration and pre-calibration variants. By comparing the resultant models with the reference DSLR-created model it was shown that introducing calibration obtained in the test field instead of self-calibration improves the geometry of 3D models. In particular, deformations of local concavities and convexities decreased. In conclusion, there is real potential in smartphone photogrammetry, but it also has its limits.
Cholesterol tagged with the BODIPY fluorophore via the central difluoroboron moiety of the dye (B-Chol) is a promising probe for studying intracellular cholesterol dynamics. We synthesized a new ...BODIPY-cholesterol probe (B-P-Chol) with the fluorophore attached via one of its pyrrole rings to carbon-24 of cholesterol (B-P-Chol). Using two-photon fluorescence polarimetry in giant unilamellar vesicles and in the plasma membrane (PM) of living intact and actin-disrupted cells, we show that the BODIPY-groups in B-Chol and B-P-Chol are oriented perpendicular and almost parallel to the bilayer normal, respectively. B-Chol is in all three membrane systems much stronger oriented than B-P-Chol. Interestingly, we found that the lateral diffusion in the PM was two times slower for B-Chol than for B-P-Chol, although we found no difference in lateral diffusion in model membranes. Stimulated emission depletion microscopy, performed for the first time, to our knowledge, with fluorescent sterols, revealed that the difference in lateral diffusion of the BODIPY-cholesterol probes was not caused by anomalous subdiffusion, because diffusion of both analogs in the PM was free but not hindered. Our combined measurements show that the position and orientation of the BODIPY moiety in cholesterol analogs have a severe influence on lateral diffusion specifically in the PM of living cells.
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