Investigation of potential extreme load reduction for a two‐bladed upwind turbine with partial pitch

This paper presents a wind turbine concept with an innovative design combining partial pitch with a two‐bladed (PP‐2B) turbine configuration. Special emphasis is on extreme load reduction during storm situations at standstill, but operational loads are also investigated. In order to compare the loads and dynamics of the PP‐2B turbine, a partial pitch three‐bladed (PP‐3B) turbine and a normal pitch regulated three‐bladed (3B) turbine are introduced on the basis of solidity similarity scaling. From the dynamic comparisons between two‐ and three‐bladed turbines, it has been observed that the blade vibrations are transferred differently from the rotor to the tower. For a three‐bladed turbine, blade vibrations seen in a fixed frame of reference are split with ±1P only. A two‐bladed turbine has a similar split of ±1P but also includes contributions on higher harmonics (±2P, ±3P, … etc.). Further on, frequency split is also seen for the tower vibrations, where an additional ±2P contribution has been observed for the two‐bladed turbine. Regarding load comparisons, the PP‐2B turbine produces larger tower load variations because of 2P excitation during the operational cases. However, extreme loads are reduced by approximately 20% for the PP‐2B and 18% for the PP‐3B compared with the 3B turbine for the parked condition in a storm situation. Moreover, a huge potential of 60% is observed for the reduction of the extreme tower bottom bending moment for the PP‐2B turbine, when the wind direction is from ±90° to the turbine, but this also requires that the turbine is parked in a T‐configuration. © 2014 The Authors. Wind Energy published by John Wiley & Sons, Ltd.     

On Surface Losses in Direct Metal Laser Sintering Printed Millimeter and Submillimeter Waveguides

Different lengths of WR3 (220–330 GHz) and WR10 (75–110 GHz) waveguides are fabricated through direct metal laser sintering (DMLS). The losses in these waveguides are measured and modelled using the Huray surface roughness model. The losses in WR3 are around 0.3 dB/mm and in WR10 0.05 dB/mm. The Huray equation model is accounting relatively good for the attenuation in the WR10 waveguide but deviates more in the WR3 waveguide. The model is compared to finite element simulations of the losses assuming an approximate surface structure similar to the resulting one from the DMLS process.     

Influence of Grain Refinement on Slurry Formation and Surface Segregation in Semi-solid Al-7Si-0.3Mg Castings

This study aims to evaluate the effect of grain refinement on slurry formation and surface segregation in semi-solid castings produced by the Rheometal™ process. The effect of two grain refiners, Al-8B and Al-5Ti-1B, on the slurry α-Al grain size, shape factor and solid fraction was evaluated. The results suggest that the addition of a grain refiner can affect the solid fraction obtained in the Rheometal^TM process and, consequently, reduce the solute content near the casting surface. Grain refiner addition resulted in a larger fraction of α-Al grains ≤ 60 µm for the refined alloys compared with the unrefined alloy. Additionally, the growth of α-Al slurry globules was greater for the unrefined alloy compared with the refined alloy during solidification in the die-cavity. A more homogeneous and finer microstructure was observed near the surface in the grain-refined castings compared with the unrefined castings. Evidence of significant liquid penetration was identified in some α-Al globules, indicating that disintegration of α-Al globules may occur during the Rheometal™ casting process.

     

New CAMAC based data acquisition and beam control system for Lund nuclear microprobe

A new CAMAC based data acquisition system has been installed at the Lund Nuclear Microprobe facility. This paper reports on the development and present status of the data acquisition system. The system is a true multiparameter CAMAC based system with fast Fera bus readout and in crate memory buffer. The user interface is based on Sparrow Kmax software for a Power Macintosh platform. The system read out and tag the event data with position on-line, which make fast on-line monitoring of spectra or element maps possible.Simultaneously, all data can be saved event by event for off-line analysis. The beam scanning part is software controlled through a timed D/A converter, this allows fast scanning of the beam. With a CCD-camera and video card the area to be analysed could be defined directly from the image, and the sample position can be moved. Any kind of irregular scan patterns could be defined.     

Broccoli leaf powder as an attractive by-product ingredient: effect on batter behaviour,technological properties and sensory quality of gluten-free mini sponge cake

Broccoli by-products, in particular leaves, are rich sources of nutritional and bioactive components thus could constitute a valuable food additive. Although an upsurge in quantity of gluten-free products is observed further studies are required on improvement of their nutritional quality and palatability. This study aimed to investigate the influence of broccoli leaf powder (BLP) on dough behaviour, and technological characteristics and sensory quality of gluten-free mini sponge cake (GFS). Broccoli leaf powder replaced an equivalent amount (2.5%, 5%, 7.5%; w/w) of corn and potato starches in GFS formulation. Applied BLP increased the instrumental firmness of GFS but sensorial attributes (elasticity, crustiness, mastication and adhesiveness) were similar to the control. All broccoli GFS were vividly green, had small size pores properly distributed. Among them, sample with 2.5% BLP was distinguished for its desirable sensory quality, despite a slightly perceived cabbage aroma and taste. Moderate amount of BLP allows to preserve a good quality GFS improving its attractiveness and palatability.     

In vitro fermentation of cereal dietary fibre carbohydrates by probiotic and intestinal bacteria

A range of probiotic and other intestinal bacteria were examined for their ability to ferment the dietary fibre carbohydrates β‐glucan, xylan, xylo‐oligosaccharides (XOS) and arabinoxylan. β‐Glucan was fermented by Bacteroides spp and Clostridium beijerinckii but was not fermented by lactobacilli, bifidobacteria, enterococci or Escherichia coli. Unsubstituted xylan was not fermented by any of the probiotic bacteria examined. However, many Bifidobacterium species and Lactobacillus brevis were able to grow to high yields using XOS. XOS were also efficiently fermented by some Bacteroides isolates but not by E coli, enterococci, Clostridium difficile, Clostridium perfringens or by the majority of intestinal Lactobacillus species examined. Bifidobacterium longum strains were able to grow well using arabinoxylan as the sole carbon source. These organisms hydrolysed and fermented the arabinosyl residues from arabinoxylan but did not substantially utilise the xylan backbone of the polysaccharide. Arabinoxylan was not fermented by lactobacilli, enterococci, E coli, C perfringens or C difficile and has potential to be an applicable carbohydrate to complement probiotic Bif longum strains in synbiotic combinations. © 2002 Society of Chemical Industry     

Pt‐Free Counter Electrode for Dye‐Sensitized Solar Cells with High Efficiency

Dye‐sensitized solar cells (DSSCs) have attracted widespread attention in recent years as potential cost‐effective alternatives to silicon‐based and thin‐film solar cells. Within typical DSSCs, the counter electrode (CE) is vital to collect electrons from the external circuit and catalyze the I₃^? reduction in the electrolyte. Careful design of the CEs can improve the catalytic activity and chemical stability associated with the liquid redox electrolyte used in most cells. In this Progress Report, advances made by our groups in the development of CEs for DSSCs are reviewed, highlighting important contributions that promise low‐cost, efficient, and robust DSSC systems. Specifically, we focus on the design of novel Pt‐free CE catalytic materials, including design ideas, fabrication approaches, characterization techniques, first‐principle density functional theory (DFT) calculations, ab‐initio Car‐Parrinello molecular dynamics (CPMD) simulations, and stability evaluations, that serve as practical alternatives to conventional noble metal Pt electrodes. We stress the merits and demerits of well‐designed Pt‐free CEs, such as carbon materials, conductive polymers, transition metal compounds (TMCs) and their corresponding hybrids. Also, the prospects and challenges of alternative Pt catalysts for their applications in new‐type DSSCs and other catalytic fields are discussed.     

Bone marrow and renal injury associated with haloalkene cysteine conjugates in calves

Almost 40 years ago, it was reported that cattle-feed which had been extracted with hot trichloroethylene and then fed to calves produced renal injury and a fatal aplastic anaemia. The toxic factor was subsequently identified as S-(1,2-dichlorovinyl)-L-cysteine (DCVC). These original findings have been confirmed, a single intravenous dose of DCVC at 4 mg/kg, or 0.4 mg/kg intravenously per day administered for 10 days to calves produced aplastic anaemia, and renal injury after a single dose of 4 mg/kg. The toxicity to calves of a number of other haloalkene cysteine conjugates has been examined to ascertain whether, like DCVC, they produce bone marrow and renal injury. Intravenous administration of the N-acetyl cysteine conjugate of DCVC produced renal but not bone marrow injury at a molar equivalent dose to DCVC, indicating that the calf can deacetylate the mercapturic acid and further that sufficient chemical had reached the kidney to be a substrate for the enzyme cysteine conjugate beta-lyase. However, intravenous administration of the alpha-methyl analogue of DCVC, which cannot undergo metabolism via the enzyme cysteine conjugate beta-lyase, was without toxicity at doses about five-fold higher than DCVC. These latter findings provide strong evidence that metabolism of DCVC via the enzyme beta-lyase is necessary for bone marrow and renal injury to occur. The cysteine conjugates of perchloroethylene and hexachloro-1,3-butadiene(HCBD) when given intravenously to calves at molar equivalent doses to DCVC, or above, did not produce either bone marrow or renal injury. In contrast, intravenous administration of the cysteine conjugate of tetrafluoroethylene (TFEC) produced severe renal tubular injury in calves without affecting the bone marrow. In vitro studies with these haloalkene cysteine conjugates showed, like DCVC, that they were good substrates for calf renal cysteine conjugate beta-lyase and toxic to renal cells as judged by their ability to reduce organic anion and cation transport by slices of calf renal cortex and inhibit the renal enzyme glutathione reductase. Calves were also dosed either orally or intravenously with HCBD to assess its toxicity. HCBD at higher molar equivalent doses than DCVC produced mid-zonal necrosis in the liver, renal tubular necrosis but no bone marrow injury in calves. The key findings emerging from these studies are (1) that none of the other cysteine conjugates, at molar equivalent doses to DCVC and above, produce bone marrow injury in calves, (2) TFEC produced only renal injury, suggesting that sufficient of the other conjugates had not reached the kidney for metabolism by beta-lyase to produce cytotoxicity and (3) that HCBD itself is more toxic than its cysteine or mercapturic acid conjugate, suggesting that pharmaco-kinetics and disposition are important factors in determining the toxicity of these conjugates to calves. Further studies are needed to understand the basis for the selective toxicity of DCVC to the bone marrow of calves.     

Partially dehydrochlorinated PVC. II. Reactions with dienophiles and hydroxylating agents

Samples of poly(vinylchloride) containing polyene sequences were made by partial dehydrochlorination by alkali in tetrahydrofuran solution, by alkali in dioxane, and thermally in dimethyl-formamide. The reactions of polyene PVC were followed by UV spectrophotometry. Dienophiles were found to have relative reactivities similar to those found in reactions with low molecular-weight dienes. The reaction with maleic anhydride yielded polymers which after hydrolysis contained carboxyl groups. Hydroxylation was made with osmium tetraoxide and performic acid. With the latter reagent the reaction proceeded to complete disappearance of the UV-absorption peaks from trienes and higher polyenes: Gel permeation chromatography analysis showed that hydroxylation could be made with only minor changes in molecular-weight distribution. The formation of gel upon thermal dehydrochlorination in DMF was shown to be due to physical cross linking probably arising by crystallization of polyene segments. The adhesion of the hydroxylated and carboxylated polymers to glass and stainless-steel surfaces was investigated. Films adhered stronger as the degree of dehydrochlorination of the polyene PVC used to make the derivative increased. Samples with long sequences adhered much stronger than those containing short sequences of corresponding degrees of total substitution.