Long‐term loads for a monopile‐supported offshore wind turbine

Accurate prediction of long‐term ‘characteristic’ loads associated with an ultimate limit state for design of a 5‐MW bottom‐supported offshore wind turbine is the focus of this study. Specifically, we focus on predicting the long‐term fore–aft tower bending moment at the mudline and the out‐of‐plane bending moment at the blade root of a monopile‐supported shallow‐water offshore wind turbine. We employ alternative probabilistic predictions of long‐term loads using inverse reliability procedures in establishing the characteristic loads for design. Because load variability depends on the environmental conditions (defining the wind speed and wave height), we show that long‐term predictions that explicitly account for such load variability are more accurate, especially for environmental states associated with above‐rated wind speeds and associated wave heights. Copyright © 2012 John Wiley & Sons, Ltd.     

Innovations in the ENHS reactor design and fuel cycle

A number of approaches were explored for improving characteristics of the encapsulated nuclear heat source (ENHS) reactor and its fuel cycle, including: increasing the ENHS module power, power density and the specific power, making the core design insensitive to the actinides composition variation with number of fuel recycling and reducing the positive void coefficient of reactivity. Design innovations examined for power increase include intermediate heat exchanger (IHX) design optimization, riser diameter optimization, introducing a flow partition inside the riser, increasing the cooling time of the LWR discharged TRU, increasing the minor actinides' concentration in the loaded fuel and split-enrichment for power flattening. Another design innovation described utilizes a unique synergism between the use of MA and the design of reduced power ENHS cores.

Also described is a radically different ENHS reactor concept that has a solid core from which heat pipes transport the fission power to a coolant circulating around the reflector. Promising features of this design concept include enhanced decay heat removal capability; no positive void reactivity coefficient; no direct contact between the fuel clad and the coolant; a core that is more robust for transportation; higher coolant temperature potentially offering higher energy conversion efficiency and hydrogen production capability.     

Analysis of the phase partitioning of additives in rubber‐modified plastics

The phase partitioning of additives in polymer blends has a large impact on the performance of the blend. Therefore, it is necessary to be able to quantify the level of the additives in each phase. A ¹H–NMR method is presented to determine the partitioning of additives between the rubber and rigid phases of a high‐impact polystyrene (HIPS) material. In one case, a HIPS material was modified with 2,6‐di‐tert‐butyl‐4‐methyl‐phenol (Ionol, CAS# 128‐37‐OMF) as a stabilizer for both phases. HIPS materials with varying levels of Ionol were melt‐blended by extrusion and the total level of additives was determined analytically for these standard materials. The ¹H–NMR method was used to determine the level of Ionol in the poly(butadiene) rubber phase. The Ionol was found to preferentially partition into the rubber phase with a partition coefficient of about 2. A second example of the same concept, instead utilizing ¹³C–NMR, involved the analysis of the partition coefficient for both Tinuvin P and Tinuvin 770 (CAS# 2440‐22‐4 and 52829‐07‐9), partitioning between the rigid and rubber phases of an ethylene–propylene–diene‐modified (EPDM) toughened styrene–ran–acrylonitrile (SAN) copolymer. The partition coefficient was determined to be 0.5 for Tinuvin P and 1.3 for Tinuvin 770. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1963–1970, 2001     

Rue and Brazilian peppertree essential oils inhibit the germination and initial development of the invasive plant lovegrass

ABSTRACT

Lovegrass (Eragrostis plana) is the most important invasive plant in pastures of southern Brazil. The research evaluated the potential of Ruta graveolens (rue) and Schinus terebinthifolius (Brazilian peppertree) essential oils (EOs) to inhibit germination and initial development of lovegrass. The in vitro treatments tested were control (distilled water), alcohol control, 0.001, 0.005, 0.01, 0.05 and 0.1% (v/v) of both EOs. Higher concentrations of these EOs were applied to germinated plants under greenhouse conditions. The EOs of both species were effective in reducing lovegrass germination, with emphasis on rue. Height and shoot dry mass, at greenhouse conditions, were significantly reduced by both EOs, especially when applied at a concentration of 1%. The results point to the potential of rue and Brazilian peppertree EOs for the formulation of natural herbicides.     

Alcohol cue reactivity, negative-mood reactivity, and relapse in treated alcoholic men.

Relapsed alcoholic individuals frequently report that negative emotional states trigger their return to drinking. A parametric laboratory study was conducted to assess the separate and combined effects of exposure to alcohol-related stimuli and induced negative moods in abstinent alcoholic persons. The authors also sought to determine if reactivity to alcohol cues or reactivity to negative mood induction predicted relapse soon after treatment. Men with alcoholism (N?=?50) undergoing inpatient treatment participated in a guided imagery procedure designed to induce negative moods and were then exposed to either their favorite alcoholic beverage or to spring water. Results indicated that both alcoholic beverage presentation and negative affect imagery led to increased subjective reporting of desire to drink. These effects were additive but not multiplicative (i.e., the interaction of mood state with beverage type was not significant). Reported urge to drink during the trial that combined negative mood imagery with alcoholic beverage exposure predicted time to relapse after inpatient discharge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

使DCI／DC变换器限流特性线性化的热敏电阻器网络

最近推出的各种集成式降压DC/DC变换器均已采取对外接低侧MOSFET同步整流器的电压降采样的方法．无需高侧电流检测电阻器。这种拓扑节省了检测电阻器的成本和印制电路板的空间．也适当提高了电路效率。但是．MOSFET的导通电阻与温度有很大的相关性它决定了限流大小、所幸的是，某些新型DC／DC变换器《如Maxim公司的MAX1714）可以从外部调整限流间值。图1的电路显示如何用一只热敏电阻器对电路的输出电流限制作出温度补偿。     

Robust optimal design using a second-order tolerance model

In this paper we present a general, quantitative method for developing designs that are robust to variation in design variables and parameters. Variation is defined in terms of tolerances which bracket the expected deviation of uncertain quantities about nominal values. We specifically address the case where input variations are assumed to be random variables that are normally distributed. The method incorporates a second-order tolerance model as part of a nonlinear optimization process. The second-order tolerance model makes it possible to estimate the skewness of function distributions, which are modeled with a three-parameter gamma distribution. We apply the method to determine robust designs for 11 test cases that span a variety of problems; robustness is verified with Monte Carlo simulation. The method enables a designer to understand and account for the effects of tolerances, making it possible to build robustness into an engineering design.     

n-Butyrate mediation of ganglioside expression of human and murine cancer cells demonstrates relative cell specificity

1. n-Butyrate, a short chain fatty acid produced by colonic fermentation, induces differentiation in human neoplastic cell lines, and reduces expression in vitro of a sialyltransferase that glycosylates N-linked glycoproteins in hepatoblastoma cells. Gangliosides are amphipathic, sialylated glycosphingolipids that undergo profound changes in many transformed cells and may protect neoplastic cells from host immune surveillance. Colonic mucosal cells are exposed to luminal short-chain fatty acid concentrations of up to 80 mmol/l, and there is some evidence that short-chain fatty acids may alter ganglioside expression in colon cancer cells. 2. Because of the importance of gangliosides in cancer pathogenesis, we investigated the effects of n-butyrate on ganglioside expression of colonic (human and murine) and non-colonic cancer cells. 3. Three separate colon cancer cell lines (LS174T, T84 and MCA-38), when butyrate treated, demonstrated striking amplification of specific individual gangliosides. However, the total lipid-bound sialic acid content of gangliosides of butyrate-treated LS174T cells diminished. In contrast to earlier reports, n-butyrate did not mediate expression of all gangliosides and specifically did not mediate expression of GM3. This effect persisted even after removal of butyrate. 4. In contrast, exposure of extracolonic cells to butyrate, including cervical cancer (HeLa) and laryngeal cancer (HEp-2) cell lines in this study and hepatoblastoma cells (Hep G2) in our previous work, caused no detectable changes in ganglioside expression. 5. In conclusion, our results indicate a relative tissue specificity of butyrate-mediated alterations in ganglioside expression that is not universal but is limited to specific gangliosides.     

Volatile, Potential Attractants from Ripe Coffee Fruit for Female Mediterranean Fruit Fly

Twenty-eight volatile compounds from freshly crushed, ripe, dark red coffee fruit, Coffea arabica, were identified by dynamic headspace analysis techniques. Identifications were made on the basis of a comparison of Kovats indices and GC-MS spectra for unknowns and authentic samples. Of the compounds identified, 10 were alcohols, nine were aldehydes, five were ketones, and four were monoterpenes. The five most abundant volatiles in decreasing order were hexanal (21%), 2-(E)-hexenal (11%), 3-methyl-1-butanol (9.0%), 3-methyl-1-butanal (8.5%), and 1-hexanol (8.4%). The five least abundant volatiles of the 28 identified, in increasing order, were decanal (0.19%), methyl hexanoate (0.33%), pulegone (0.44%), α-isomenthone (0.45%), and 2-nonanone (0.55%). In preliminary tests, many of the identified volatiles attracted more female Mediterranean fruit flies than the control.     

Use of predator odors as repellents to reduce feeding damage by herbivores

The effectiveness of predator odors (fecal, urine, and anal scent gland) in suppressing feeding damage by snowshoe hares was investigated in pen bioassays at the University of British Columbia Research Forest, Maple Ridge, British Columbia, Canada. A total of 28 bioassay trials tested the effects of these odors on hare consumption of willow browse and coniferous seedlings. Lynx and bobcat feces, weasel anal gland secretion, and lynx, bobcat, wolf, coyote, fox, and wolverine urines resulted in the most effective suppression of hare feeding damage. Novel odors of domestic dog urine and 2-methylbutyric acid did not reduce feeding. A field bioassay with lodgepole pine seedlings and weasel scent provided significant results comparable to the pen bioassays. The short-term (up to seven days) effectiveness of these treatments was more likely due to evaporative loss of the active repellent components of a given odor than habituation of hares to the stimulus. Predator odors as repellents have a biological basis compared with the anthropomorphic origins of commercial repellents. When encapsulated in weather-proof controlled-release devices, these odors could provide long-term protection for forestry plantations and agricultural crops which experience hare/rabbit feeding damage.