Increase in the annual energy production due to a retrofit of vortex generators on blades

The aim of the current work was to analyze the effect of retrofitting vortex generators (VGs) on the blades of a constant RPM, pitch‐regulated, megawatt‐sized turbine suffering from surface roughness. Engineering modelling and experimental work were utilized, indicating that the degradation of energy production may be mitigated by the VGs. The modelling results indicated that the optimal configuration of VGs to maximize the annual energy production (AEP) depends on the degree of severity of surface roughness. Depending on blade surface condition and turbine characteristics, installation of VGs on an incorrect blade span or installation of too large VGs too far out on the blade may cause loss in the AEP. Therefore, engineering modelling is necessary before VGs may be retrofitted on a specific turbine. The modelling results indicated that the worse blade surface, the more gain may be obtained from the VGs. The work included a full‐scale experimental validation of the present engineering model, lasting 27 months and comprising six turbines where VGs were mounted on three, each with a neighboring turbine as a reference. The turbines were analyzed in pairs, and the influence of the VGs was judged upon the relative difference in energy production before and after the installation. The reason was to limit measurement uncertainty. The results showed that all three turbines increased their energy production after the installation. Results from the three pairs showed an average increase in the energy production of 3.3%, being satisfactorily close to the average 2.8% predicted by the present engineering tool.     

Kinetic limitations in the Mg-Si-H system

Magnesium silicide (Mg₂Si) has attracted interest as a hydrogen storage material due to favorable thermodynamics (ΔH_desorption = 36 kJ/mol H₂) for room temperature operation. To date, direct hydriding of Mg₂Si under hydrogen gas to form MgH₂ and Si has only been attempted at low pressure and has been hindered by poor kinetics of absorption. In this paper we study the dehydrogenation reaction with in-situ neutron powder diffraction and present results of our attempts to hydrogenate Mg₂Si under both hydrogen and deuterium gas up to temperatures of 350 °C and pressures of 1850 bar. Even under these extreme absorption conditions Mg₂Si does not absorb any measureable quantity of hydrogen or deuterium.     

Partition of Rare Earth Elements Between Sulfate Salts Formed by the Evaporation of Acid Mine Drainage

Acid mine drainage (AMD) contains rare earth element (REE) concentrations several orders of magnitude higher than those of the rest of natural waters and could be a secondary source of REEs. In arid to semiarid climates with a long dry season, the precipitation of efflorescent sulfates constitutes a transient storage of REEs. The REE partition among the Al–Fe–Mg–Ca sulfates formed by the evaporation to dryness of six different AMDs was investigated by statistical methods and by selective dissolution. The chemical composition of the evaporitic salts showed that only three principal components (PCs) could explain more than 80% of the variability in the six samples analyzed. PC1 was associated with Ca and light REEs and interpreted as gypsum, whereas PC2 was associated with Y and heavy REEs, which were not clearly associated with a major sulfate. Finally, PC3 included Mg, Fe and several transition metals (Cu, Ni, Co, Mn and Zn) and was interpreted as Fe(II)-Mg sulfates. Selective dissolution of the salt mixtures with solutions saturated in the major sulfates revealed that the REEs were only retained in gypsum and were practically absent from the rest of the sulfates. The incorporation of REEs into gypsum decreased from Pr-Nd to La and Lu and was strictly ruled by the differences in their atomic radii and that of Ca in eight-fold coordination. However, gypsum concentrated less than 20% of the REE inventory (<?1% for Sc); the rest probably formed one or more unidentified trace minerals. This indicates that gypsum may not be an efficient way to concentrate REEs from AMD.

     

Fission Product Yields for 14 MeV Neutrons on U, U and Pu

We report cumulative fission product yields (FPY) measured at Los Alamos for 14 MeV neutrons on ²³⁵U, ²³⁸U and ²³⁹Pu. The results are from historical measurements made in the 1950s–1970s, not previously available in the peer reviewed literature, although an early version of the data was reported in the Ford and Norris review. The results are compared with other measurements and with the ENDF/B-VI England and Rider evaluation. Compared to the Laurec (CEA) data and to ENDF/B-VI evaluation, good agreement is seen for ²³⁵U and ²³⁸U, but our FPYs are generally higher for ²³⁹Pu. The reason for the higher plutonium FPYs compared to earlier Los Alamos assessments reported by Ford and Norris is that we update the measured values to use modern nuclear data, and in particular the 14 MeV ²³⁹Pu fission cross section is now known to be 15–20% lower than the value assumed in the 1950s, and therefore our assessed number of fissions in the plutonium sample is correspondingly lower. Our results are in excellent agreement with absolute FPY measurements by Nethaway (1971), although Nethaway later renormalized his data down by 9% having hypothesized that he had a normalization error. The new ENDF/B-VII.1 14 MeV FPY evaluation is in good agreement with our data.     

Bisphenol A based pyrazoloquinoline dimers as dopants for electroluminescent applications

A series of 1,3-methyl/phenyl (1,3-Me/Ph) bisphenol A based pyrazoloquinoline dimers (BAPQD) have been synthesized and characterized by spectroscopic methods. The obtained results demonstrate that recently synthesized dyes may be considered as promising materials for electroluminescent applications being used as dopants of PVK layers in OLED fabrication. The electroluminescent devices of the structure (ITO)/PVK:BAPQD-X/Ca/Al (X = 1–4) have been constructed and their current-voltage-luminescence characteristics are derived. In PVK host the 1,3-Me/Ph BAPQD derivatives emit light with different shades of blue color.     

Regulation of acetic acid production by homo-and heterofermentative lactobacilli in whole-wheat sour-doughs

The efficiency of sour-dough as a possible preservative agent of microbial spoilage of bread depends on its acetic acid content. As a secondary metabolite of sugar fermentation by lactic acid bacteria, acetic acid may be promoted in the presence of O₂ or H⁺ acceptors. This paper studies the influence of O₂ and high fructose content products (pure sugar, invert sugar, fructose syrup) addition on acetic acid production by hetero- (Lactobacillus brevis 25a, B-21, L-62;L. sanfrancisco L-99) and homofermentative (L. plantarum B-39) lactobacilli in whole-wheat sour-doughs [280 and 250 dough yield (DY)]. The pH and total titratable acidity (TTA) of sour-doughs after 44 h fermentation varied with DY and strain. As expected, the addition of O₂ promoted greater increases in TTA with heterofermentative lactobacilli (15–42%) than withL. plantarum (15%). Fructose addition was only effective for heterofermentative strains, but the overall effects were smaller than those observed for oxygenation. The ability of lactobacilli to produce acetic acid in sour-doughs without treatment varied from 0.16 g/100 g flour at 44 h (B-39, 280, 350 DY) to 0.47–0.65% (L-62, 280, 350 DY). The production of acetic acid was positively promoted by all treatments. Oxygenation was again the most effective way of inducing acetic acid production; increases ranged from 54% (B-21) to 269% (L-99, 350 DY). The addition of H⁺ acceptors had variable effects. Pure fructose resulted, in general, in greater increases than invert sugar of fructose syrup. The main effects were detected forL. brevis 25a (280 DY) B-21 (350 DY) andL sanfrancisco L-99 (350 DY) with increases ranging from 92 to 123%. The highest levels of acetic acid (1.02–1.04%) corresponded to sour-doughs (44 h, 35° C shaking 150 rpm) started with L-62 (280, 350 DY) or L-99 (350 DY).

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Beeinflussung der Essigsäurebildung durch homo- und heterofermentative Laktobacillen in Weizenvollkornsauerteigen

Zusammenfassung Die Haltbarkeit von Sauerteig-Brot gegen mikrobiologische Verderbnis beruht auf seinem Säuregehalt. Als sekundäres Stoffwechselprodukt der Zuckergärung durch Milchsäurebakterien, kann die Essigsäure-Bildung von Sauerstoff- oder Wasserstoffacceptoren gefördert werden. Diese Veröffentlichung befaßt sich mit dem Einfluß von Sauerstoff und Produkten mit hohem Fructosegehalt (Rohrzucker, Invertzucker, Fructose-Sirup) auf die Essigsäure-Bildung durch hetero- (Lactobacillus brevis B-21, 25a, L-62;L. sanfrancisco L-99) und homofermentative (L. plantarum B-39) Laktobacillen in Weizenvollkornsauerteigen (TA 280 und 350). ph-Wert und Säuregrad von Sauerteigen nach 44-stündiger Gärung waren verschieden je nach TA und Stamm. Wie erwartet, verursachte die Zugabe von Sauerstoff eine größere Zunahme des Säuregrades mit heterofermentativen Laktobacillen (15–42%) als mitL. plantarum (15). Fructose-Zugabe war nur wirksam für die heterofermentativen Stämme, aber die allgemeinen Wirkungen waren kleiner als die bei der Behandlung mit Sauerstoff beobachteten. Die Fähigkeit von Laktobazillen, ohne Behandlung in Sauerteigen Essígsäure zu bilden, schwankte zwischen 0.16 g/100 g Mehl (B-39, 280, 350 TA) und 0.47–0.65% (L-62, 280, 350 TA). Die Bildung von Essigsäure wurde durch alle Behandlungen gefördert. Die Behandlung mit Sauerstoff war wieder die effizienteste zur Förderung der Essigsäurebildung; der Anstieg schwankte zwischen 54% (B-21) und 269% (L-99, 350 TA). Die Zugabe von Wasserstoffacceptoren hatte verschiedene Effekte. Reine Fructose ergab im allgemeinen größere Anstiege als Invertzucker oder Fructose Sirup. Die Haupteffekte wurden beiL. brevis 25a (280 TA), B-21 (350 TA) undL. sanfrancisco L-99 (350 TA) mit Anstiegen von 92% bis 123% nachgewiesen. Die mit L-62 (280, 350 TA) oder L-99 (350 TA) hergestellten Sauerteige (44 h, 35 °C, 150 rpm schütteln) ergaben die höchste Gehalte an Essigsäure (1.02–1.04%).

     

Near infrared reflectance spectroscopy: Moisture content measurement for ceramic plaster

We measured moisture content of ceramic plaster using near infrared reflectance spectroscopy (NIRS) as required by the ceramic industry. The moisture content and the normalized spectral reflectance were measured and correlated at the wavelengths of the spectral absorptance peaks (α _λ ), spectral sensitivity peaks (S _λ ) and normalized sensitivity peaks (S _λn ), in the wavelength range of 900–2500 nm. The best model was obtained by the scanning method, normalizing the sensitivity and doing a minimization of the standard error of estimate (SE). The α _λ -peaks, s _λ -peaks and s _λn -peaks were not found at the same wavelength, for the three studied wavebands. The optimal model in terms of SE was the linear model at 1420 nm (s _λ -peak), for the ceramist drying range with a SE ₁₄₂₀ =1.25 (R²=0.96). The results indicate the feasibility of NIRS to non-contact moisture content measures of plaster in the studied range, even more for ceramist range.     

Anthratectone and Naphthotectone,Two Quinones from Bioactive Extracts of <Emphasis Type="Italic">Tectona grandis</Emphasis>

Two new quinones, (an isoprenoid quinone, and a dimeric anthraquinone) named naphthotectone and anthratectone, respectively, were isolated from bioactive leaf extracts from Tectona grandis. Their structures were determined by a combination of 1D and 2D NMR techniques. The bioactivity profile of naphthotectone was assessed using the etiolated wheat coleoptiles bioassay in aqueous solutions at concentrations ranging from 10⁻³ to 10⁻⁵M, as well as the standard target species lettuce, cress, tomato, and onion. Naphthotectone showed high level of activities in both bioassays. This fact, along with the presence of this compound as the major component in Tectona grandis, suggests that it may be involved in the allelopathic activity previously described for this species, and probably in other defense mechanisms.