0000000000214809
AUTHOR
Lin Li
Numerical study of a concept for major repair and replacement of offshore wind turbine blades
Repair and replacement of offshore wind turbine blades are necessary for current and future offshore wind turbines. To date, repair activities are often conducted using huge jack-up crane vessels and by applying a reverse installation procedure. Because of the high costs associated with installation and removal of offshore wind turbine components and the low profit margin of the offshore wind industry, alternative methods forinstallation and removal are needed. This paper introduces a novel concept for replacement or installation of offshore windturbine blades. The concept involves a medium-sized jack-up crane vessel and a tower climbing mechanism. This mechanism provides a stable platform …
Impact of Spectral Resolution on Quantifying Cyanobacteria in Lakes and Reservoirs: A Machine-Learning Assessment
Cyanobacterial harmful algal blooms are an increasing threat to coastal and inland waters. These blooms can be detected using optical radiometers due to the presence of phycocyanin (PC) pigments. The spectral resolution of best-available multispectral sensors limits their ability to diagnostically detect PC in the presence of other photosynthetic pigments. To assess the role of spectral resolution in the determination of PC, a large (N = 905) database of colocated in situ radiometric spectra and PC are employed. We first examine the performance of selected widely used machine-learning (ML) models against that of benchmark algorithms for hyperspectral remote sensing reflectance ( $R_{{rs}})$…
Optical types of inland and coastal waters
Inland and coastal waterbodies are critical components of the global biosphere. Timely monitoring is necessary to enhance our understanding of their functions, the drivers impacting on these functions and to deliver more effective management. The ability to observe waterbodies from space has led to Earth observation (EO) becoming established as an important source of information on water quality and ecosystem condition. However, progress toward a globally valid EO approach is still largely hampered by inconsistences over temporally and spatially variable in-water optical conditions. In this study, a comprehensive dataset from more than 250 aquatic systems, representing a wide range of condi…
A conjugated polymer with ethyl 2-(2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl) acetate units as a novel fluorescent chemosensor for silver(I) detection
Abstract A novel conjugated polymer ( P1 ) containing fluorene and ethyl 2-(2-(pyridin-2-yl)-1 H -benzo[ d ]imidazol-1-yl)acetate (PBMA) was designed and successfully synthesized through the Sonogashira coupling reaction. P1 shows high sensitivity and selectivity for Ag + detection in comparison to other metal cations. Upon addition of Ag + , the fluorescent emission of the polymer solution in THF was quenched dramatically, accompanying the color changed from blue to green. The detection limit for Ag + was 5 × 10 −8 mol L −1 . However, the similar copolymers P2 and P3 containing 2-(pyridin-2-yl)-1 H -benzo[ d ]imidazole and 2-(thiophen-2-yl)-1 H -benzo[ d ]imidazole, respectively, did not …
Advancing cyanobacteria biomass estimation from hyperspectral observations: Demonstrations with HICO and PRISMA imagery
Retrieval of the phycocyanin concentration (PC), a characteristic pigment of, and proxy for, cyanobacteria biomass, from hyperspectral satellite remote sensing measurements is challenging due to uncertainties in the remote sensing reflectance (?R) resulting from atmospheric correction and instrument radiometric noise. Although several individual algorithms have been proven to capture local variations in cyanobacteria biomass in specific regions, their performance has not been assessed on hyperspectral images from satellite sensors. Our work leverages a machine-learning model, Mixture Density Networks (MDNs), trained on a large (N = 939) dataset of collocated in situ chlorophyll-a concentrat…
Numerical Study on the Heading Misalignment and Current Velocity Reduction of a Vessel-Shaped Offshore Fish Farm
Recently, the concept of a vessel-shaped fish farm was proposed for open sea applications. The fish farm comprises a vessel-shaped floater, five fish cages, and a single-point mooring system. Such a system weathervanes, and this feature increases the spread area of fish waste. Still, the downstream cages may experience decreased exchange of water flow when the vessel heading is aligned with the current direction, and fish welfare may be jeopardized. To ameliorate the flow conditions, a dynamic positioning (DP) system may be required, and its power consumption should relate to the heading misalignment. This paper proposes an integrated method for predicting the heading misalignment between t…
Design optimization of mooring system: An application to a vessel-shaped offshore fish farm
Abstract Design optimization of mooring systems of offshore floating structures is a challenging task, partly because of the large number of design variables, complicated design constraints, nonlinear system behavior, and time-consuming numerical simulations. For engineering designs, efficient yet accurate approaches are needed. This paper proposes an integrated optimization methodology for design of mooring systems. The methodology integrates the design of experiments, screening analysis, time-domain simulations, and a metamodel-based optimization procedure. To demonstrate the methodology, the mooring system of a vessel-shaped offshore fish farm was designed considering the ultimate limit …
Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead
Goodson, William H. et al.
Role ambiguity among school principals in China and Finland
This study explores the role-ambiguity phenomenon among public secondary school principals in China and Finland. Organizational dysfunction caused by role ambiguity in professional organizations has been studied since the 1960s (Kahn et al, 1964). Although role ambiguity occurs most frequently in educational organizations, few studies on role ambiguity are found on school leaders. This study contributes to this topic by building a multidimensional knowledge structure of role ambiguity among school principals. It applies a qualitative design with case study as its approach. The data was collected through ten individual interviews with upper secondary school principals in Shanghai and the Cen…