Fatigue assessment of offshore wind turbines on monopile foundations using multi‐band modal expansion

Offshore wind turbines (OWTs) are subjected to both quasi‐static loads originating from variations in the thrust force and dynamic loads linked to turbulence, waves and turbine dynamics. Both types of loads contribute to fatigue life progression and thus define the turbine's age. As a structural health monitoring solution, one could thus directly measure the stress history at fatigue critical locations. However, for OWTs on monopile foundations some fatigue critical locations are located below the seabed. Installing strain sensors at these hotspots is therefore impossible for existing wind turbines. This measurement restriction is overcome by reconstructing the full‐field response of the structure based on the limited number of accelerometers and strain sensors (installed at a few easily accessible locations) and a calibrated finite element model of the system. The system model uses a multi‐band modal expansion approach constituted of the quasi‐static and dynamic contributions. These contributions are superimposed to reconstruct the stress history at all degrees of freedom of the finite element model, and the subsequent assess fatigue life consumption at all fatigue hot spots of the OWT. In this paper, the proposed virtual sensing technique is validated by predicting the stresses in the transition piece with 12 days of consecutive measurements from an operational OWT. The data set contains both variations in environmental and operating conditions as well as extreme events. Finally, a full‐field strain assessment in the tower and foundation system of the OWT is demonstrated. Copyright © 2017 John Wiley & Sons, Ltd.     

A TRNSYS-based simulation framework for the analysis of solar thermal and heat pump systems

The modeling and simulation of combined solar and heat pump (SHP) systems is a challenging task as it requires expert knowledge in modeling as well as in the behavior of the real systems. As an example of a SHP system, this work considers parallel solar thermal and heat pump systems with ground or air source heat pumps for the efficient energy supply of buildings. An introduction to SHP systems and the considered system concepts is given and the challenges in designing new models within the simulation environment TRNSYS are described. Finally, a TRNSYS-based stand-alone tool (SHP-SimFrame) ispresented which enables users to analyze predefined SHP concepts with hardly any knowledge in modeling and simulation itself.     

Subsecond voltammetric separation between dopamine and serotonin in the presence of ascorbate

Although voltammetry has proved an important tool for unraveling the dynamics of specific neurotransmitter molecules during the past decade, it has been very difficult to monitor more than one neurotransmitter simultaneously. In this work, we present a voltammetric methodology that allows discrimination between dopamine and serotonin, two important neurotransmitter molecules with very similar electrochemical properties, in the presence of high concentrations of ascorbate. We combined the application of a novel large-amplitude/high-frequency voltage excitation with signal processing techniques valid for the analysis of nonstationary and nonlinear phenomena. This allows us to minimize the contribution from capacitance and preserve the faradaic features of the voltammetric response providing us with excellent voltammetric detail. Using appropriate voltage excitation parameters and defining specific regions in the voltage space, so-called voltage windows, we can measure the concentrations of dopamine and serotonin separately or independently in mixed solutions even in the presence of high concentrations of ascorbate. Because of the enhanced voltammetric detail of this new technique, it is also possible to explore effects attributed to interfacial phenomena such as adsorption/desorption and electrode fouling.     

Raymond J. Corsini (1914–2008).

Presents an obituary for Raymond J. Corsini, one of psychology’s most prolific authors and editors. Ray’s most important contributions include editing an award-winning four-volume encyclopedia of psychology (1994, Wiley), a dictionary of psychology (1999, Brunner/ Mazel), and one of the leading graduate texts on psychotherapy (Corsini & Wedding, 8th ed., 2008, Cengage), which was translated into more than a dozen languages. However, Ray took the greatest pride in the development of the Corsini 4-R system (also known as Individual Education), an innovative approach to school system reform reform based on democratic principles and Adlerian psychology. (The four Rs were responsibility, respect, resourcefulness, and responsiveness.) Corsini died in Honolulu on November 8, 2008. He is survived by his physician wife, Kleona Rigney, and his social worker daughter, Evelyn Anne Corsini. Both share Ray’s passionate commitment to Adlerian social interest. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of a smart packaging for the monitoring of fish spoilage

There is much interest from the fisheries industry in developing rapid methods to evaluate real-time freshness of fish and seafood products. Emphasis is on the ones that would reflect and account for the products history and their storage conditions from “harvest-to-home”. The development of a “smart packaging” that monitors the microbial breakdown products in the headspace of packaged fish is described. When fish spoils it releases a variety of basic volatile amines which are detectable with appropriate pH indicating sensors. These are prepared by entrapping within a polymer matrix a pH sensitive dye that responds, through visible color changes to the spoilage volatile compounds that contribute to a quantity known as total volatile basic nitrogen (TVB-N). Laboratory trials on fresh fish filets showed that the sensor accurately tracks the increase in amines concentration in the package headspace. The response was also found to correlate to changing microbial populations (total viable count or TVC and Pseudomonas spp.). In addition, leaching of the dye was assessed over time to assess the suitability of the sensor formulation for food packaging application.     

Self‐Assembly: I‐Motif Nanospheres: Unusual Self‐Assembly of Long Cytosine Strands (Small 8/2011)

The synthesis and characterization of novel DNA structures based on tetraplex cytosine (C) arrangements, known as i‐motifs or i‐tetraplexes, is reported. Atomic force microscopy (AFM) investigation shows that long C‐strands in mild acidic conditions form compact spherically shaped nanostructures. The DNA nanospheres are characterized by a typical uniform shape and narrow height distribution. Electrostatic force microscopy (EFM) measurements performed on the i‐motif spheres clearly show their electrical polarizability. Further investigations by scanning tunneling microscopy (STM) at ultrahigh vacuum reveals that the structures exhibit an average voltage gap of 1.9 eV, which is narrower than the voltage gap previously measured for poly(dG)–poly(dC) molecules in similar conditions.     

UV Absorption microspectrophotometry and digestibility of cell types of bermudagrass internodes at different stages of maturity

The walls of sclerenchyma, vascular bundle sheaths, and parenchyma at different maturities (internodes 2, 5, and 7 from the apex) of bermudagrass [Cynodon dactylon (L) Pers] were analyzed by UV absorption microspectrophotometry, and the results were related to wall digestibility. Sclerenchyma walls from internode 2 were degraded by rumen microorganisms, with only the middle lamella remaining. Undegraded sclerenchyma walls gave a UV absorption spectrum similar to that of p-coumaroyl and feruloyl arabinoxylo-trisaccharides isolated from bermudagrass cell walls. Absorption maxima occurred at ? 245 and 320 nm, together with a shoulder at ? 280 nm. Sclerenchyma from the older internodes 5 and 7 showed only partial degradation of the secondary wall adjacent to the lumen. Spectra of undegraded walls from these internodes showed absorption maxima at ? 245 and 285 nm with a shoulder at ? 320 nm. Spectra of sclerenchyma walls that included the middle lamellae gave a higher absorption at ? 320 nm than did wall layers excluding the middle lamellae. Vascular bundle sheaths generally were similar in digestion patterns and spectra to those of sclerenchyma. Parenchyma cells in internode 2, which were totally degradable, gave low absorbance. Parenchyma cell walls from internodes 5 and 7 were degraded except for the middle lamellae in cells nearest to the sclerenchyma; parenchyma cells nearest to the stem centre were totally degraded. Spectra of parenchyma wall regions that included middle lamellae were similar to the p-coumaroyl and feruloyl arabinoxylo-trisaccharides, and absorbance values were low compared with sclerenchyma and vascular walls. Results suggested that esteror ether-linked phenolic acids accounted for most of the UV absorption in young sclerenchyma and young and old parenchyma; lignin-like aromatics increased in older, poorly digested sclerenchyma as ester/ether-type compounds decreased. An estimation of the amount of ‘ferulic acid equivalents’ of the walls was made assuming all the absorbance at ? λ_max 320 nm was due to ferulic acid; older sclerenchyma walls had the highest values (160 mg g^?1 walls) and parenchyma walls the lowest (11 mg g^?1 walls).     

法国时装为何长胜不衰

为什么巴黎能引领国际时装风潮?为什么巴黎时装能长盛不衰?巴黎时装教育与其有何关联,其秘诀何在?     

The use of FT‐IR microspectroscopic mapping to study the effects of enzymatic retting of flax (Linum usitatissimum L) stems

Fourier transform infrared (FT‐IR) microspectroscopic mapping was investigated as a tool to study the effects of enzymatic retting of flax stems. The FT‐IR technique permitted the elucidation of the relative loss or changes in the distribution of key chemical components after treatment with enzymes or enzyme/chelator mixtures in association with visible changes in structure. Cross‐sections of Ariane flax stems were treated with SP 249 (a pectinase‐rich enzyme mixture from Novo Nordisk) at 0.5, 0.7 or 1.0 ml l^?1 concentration in pH 5 acetate buffer for 6 h at 40 °C. Flax stems treated with 0.5 or 0.7 ml l^?1 SP 249 and 50 mM oxalic acid as a chelator were also investigated by the technique. The results indicated that treatment with 0.5 ml l^?1 SP 249 alone was ineffective in releasing the fibre bundles from the surrounding tissue, but the release was increased by the addition of 50 mM oxalic acid as a likely chelator for the cations of pectate salts. However, the IR spectra of the bundles indicated that an insoluble oxalate salt remained on the tissue after this treatment. Increasing the concentration of SP 249 to 0.7 ml l^?1 plus 50 mM oxalic acid was effective in releasing the fibre bundles and generating some ultimate fibres with no detectable oxalate expectate salt residues. Increasing the SP 249 concentration to 1.0 ml l^?1 without using oxalic acid was effective in separating the fibre bundles into ultimate (individual) fibres, leaving no pectate salt residue and only a trace of pectic esters and/or acids. The use of infrared mapping, or so‐called chemical imaging, is shown to have advantages over visible imaging alone in that it can detect and locate the chemical species present after each treatment in relation to the anatomical features of the flax stem. This analytical tool shows promise as a technique by which to study the effects of enzymatic treatment of natural fibre materials. Published in 2002 for SCI by John Wiley & Sons, Ltd