2,438 research outputs found
Implications of importance factor on seismic design from 2000 SAC-FEMA perspective
The seismic design of buildings uses global ductility factor and occupancy importance factor (IF) as two major fixed parameters in defining the safety of the structure. The study of performance variation of the structure with global ductility factor is available but there is hardly any study that provides information regarding the increase in the level of safety achieved by increasing the IF values. Being a building categorical dependent parameter, IF is used by the international seismic design codes for increasing the design loads of the structure. The change in the level of safety achieved through the variation in the value of the IFs for reinforced concrete (RC)–framed buildings will perhaps be an important and useful representation of the stakeholders for the approximate damage cost estimation. This article performs the structural safety assessment against seismic load using a standard structural reliability method with second-order hazard approximation to evaluate the effect of the IF on the level of safety and the cost associated with the building. Results show that an overall reduction of 50%–60% in the damage index of the selected buildings can be achieved by increasing the IF from a value of 1.0–2.0 with a consequent increase in the cost of the building
New limits for neutrinoless tau decays
Neutrinoless 3-prong tau lepton decays into a charged lepton and either two charged particles or one neutral meson have been searched for using 4.79fb^(-1) of data collected with the CLEO II detector at Cornell Electron Storage Ring. This analysis represents an update of a previous study and the addition of six decay channels. In all channels the numbers of events found are compatible with background estimates and branching fraction upper limits are set for 28 different decay modes. These limits are either more stringent than those set previously or represent the first attempt to find these decays
Exclusive and inclusive semileptonic decays of B mesons to D mesons
This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.43.651
Effects of grain by-products as supplements for stocker cattle grazing bermudagrass
Two experiments were conducted to compare corn, dried distillers’ grains (DDG), and pelleted soybean hulls (SH) as supplements for cattle grazing bermudagrass. In Exp. 1, 66 crossbred steers (306 ± 3.2 kg) were stratified by weight and allotted randomly to six 2.4-ha bermudagrass pastures for a 107-d study. One of three supplement treatments (corn, DDG, or SH) was assigned randomly to each pasture group and was offered at 0.5% (as fed) of body weight. Calves were weighed at 28-d intervals and supplement was adjusted after each weigh period. In Exp. 2, five ruminally cannulated steers grazed bermudagrass pasture and were individually fed supplements (corn, DDG, or SH) at 0.5% of body weight in a 3 x 3 replicated, incomplete Latin-square design with a 14-d adaptation and a 5-d sampling period. In Exp. 1, supplementation with DDG and corn increased (P \u3c 0.04) the average daily gain compared to supplementation with SH (0.89, 0.87, and 0.74 kg for DDG, corn, and SH, respectively). In Exp. 2, in situ dry-matter-disappearance kinetic measures of bermudagrass were not affected by type of supplementation. The potential extent of digestion for DDG (93%) was lower than for corn (97%, P = 0.01) and SH (96%, P = 0.06). Supplementation with corn or DDG at 0.5% of body weight improved the gain of stocker cattle grazing bermudagrass compared to supplementation with SH, but these differences were not explained by differences in bermudagrass degradation kinetic
Electronic branching ratio of the Ï„ lepton
This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.45.3976.Using data accumulated by the CLEO I detector operating at the Cornell Electron Storage Ring, we have measured the ratio R=Γ(τ→eν¯(e)ν(τ)) / Γ(1) where Γ(1) is the τ decay rate to final states with one charged particle. We find R=0.2231±0.0044±0.0073 where the first error is statistical and the second is systematic. Together with the measured topological one-charged-particle branching fraction, this yields the branching fraction of the τ lepton to electrons, Be=0.192±0.004±0.006
Algal amendment enhances biogenic methane production from coals of different thermal maturity
The addition of small amounts of algal biomass to stimulate methane production
in coal seams is a promising low carbon renewable coalbed methane
enhancement technique. However, little is known about how the addition of algal
biomass amendment affects methane production from coals of different thermal
maturity. Here, we show that biogenic methane can be produced from five coals
ranging in rank from lignite to low-volatile bituminous using a coal-derived
microbial consortium in batch microcosms with and without algal amendment.
The addition of 0.1 g/l algal biomass resulted in maximum methane production
rates up to 37 days earlier and decreased the time required to reach maximum
methane production by 17–19 days when compared to unamended, analogous
microcosms. Cumulative methane production and methane production
rate were generally highest in low rank, subbituminous coals, but no clear
association between increasing vitrinite reflectance and decreasing methane
production could be determined. Microbial community analysis revealed that
archaeal populations were correlated with methane production rate (p = 0.01),
vitrinite reflectance (p = 0.03), percent volatile matter (p = 0.03), and fixed carbon
(p = 0.02), all of which are related to coal rank and composition. Sequences
indicative of the acetoclastic methanogenic genus Methanosaeta dominated
low rank coal microcosms. Amended treatments that had increased methane
production relative to unamended analogs had high relative abundances of the
hydrogenotrophic methanogenic genus Methanobacterium and the bacterial
family Pseudomonadaceae. These results suggest that algal amendment may shift
coal-derived microbial communities towards coal-degrading bacteria and CO2-
reducing methanogens. These results have broad implications for understanding
subsurface carbon cycling in coal beds and the adoption of low carbon renewable
microbially enhanced coalbed methane techniques across a diverse range of coal
geology
The effects of verbal information on children's fear beliefs about social situations
Two experiments explored the role of verbal information in changing children’s fearrelated beliefs about social situations. In Experiment 1, 118 6- to 8- and 12- to 13-year-olds heard positive, negative, or no information about individuals’ experiences of three social situations. Fear beliefs regarding each situation were assessed before and after this manipulation. Verbal information had no significant influence on children’s fear beliefs. In Experiment 2, the same paradigm was used with 80 12- to 13-year-olds, but the information took the form of multiple attitude statements about the situations expressed by groups of peers, older children, or adults. An affective priming task of implicit attitudes was used to complement the explicit questions about fear beliefs. Negative information influenced both explicit and implicit fear beliefs. The source of information and the child’s own social anxiety did not moderate these effects. Implications for our understanding of the socialisation of childhood fears are discussed
Variability of mechanical properties of cellular lightweight concrete infill and its effect on seismic safety
Cellular lightweight concrete (CLC) block masonry has gained popularity in the masonry market with the growing demand in the modern construction industry due to its various advantages, including a positive impact on the environment. Subsequently, the detailed characterization of its vital engineering properties should be studied for the development of the mathematical model, analysis, evaluation, and design of structures made of CLC block masonry. The present study investigates the variability in two important strength properties of CLC block masonry and proposes the most appropriate models for their statistical distribution to support probability-based structural analysis and design. This study shows that the assumption of a normal distribution in the absence of an appropriate uncertainty model can result in an inaccurate estimate of the seismic risk of an RC frame building infilled with CLC block masonry. The paper further assesses the seismic safety of a typical RC framed building infilled with CLC block masonry in relation to traditional brick masonry, considering the proposed uncertainty model. Although CLC block masonry results in a higher seismic risk compared with traditional brick masonry, it can be used as an infill material in high seismic areas because it results in a probability of failure within the acceptable limit
Analysis of hadronic transitions in Υ(3S) decays
This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.49.40.Using the CLEO II detector, we have measured the branching fractions for Υ(3S)→ππΥ(1S), Υ(3S)→ππΥ(2S), and the cascade Υ(3S)→Υ(2S)+X, Υ(2S)→π+π−Υ(1S), analyzing the exclusive mode where the daughter Υ state decays to a e(+)e(−) or μ(+)μ(−) pair, as well as the inclusive π(+)π(−) transitions where the final Υ state decays into hadrons. Properties of the ππ system are analyzed. Searches for the cascade decay Υ(3S)→π+π−h(b), h(b)→γη(b) and Υ(3S)→π0h(b) were also performed
Experimental tests of lepton universality in Ï„ decay
This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.55.2559.The branching fractions for τ→eνν(τ), μνν(τ), and hν(τ) are measured using data collected with the CLEO detector at the CESR e(+)e(-) collider: Be=0.1776±0.0006±0.0017, Bμ=0.1737±0.0008±0.0018, and B(h)=0.1152±0.0005±0.0012, where the first error is statistical, the second systematic, and h refers to either a charged π or K. Also measured is the τ mass, mτ=(1778.2±1.4) MeV. Lepton universality is affirmed by the relative branching fractions (B(μ)/B(e)=0.9777±0.0063±0.0087, B(h)/B(e)=0.6484±0.0041±0.0060) and the charged-current gauge coupling-constant ratios (g(μ)/g(e)=1.0026±0.0055, g(τ)/g(μ)=0.9990±0.0098). The τ mass result may be recast as a τ neutrino mass limit, m(ν)(τ)<60 MeV at 95% C.L
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