On the role of uncertainty in the limit states design of steel structures

1980 ◽  
Vol 7 (4) ◽  
pp. 588-596 ◽  
Author(s):  
P. Dumonteil
Keyword(s):  
Steel Structures ◽  
Mean Value ◽  
Limit States ◽  
Mean Values ◽  
Code Calibration ◽  
Risk Of Failure ◽  
Load Effects ◽  
Global Uncertainty ◽  
Random Nature

The study of current work on steel code calibration shows that uncertainties in member resistances, load effects, and structural analysis are most usually assumed to have mean values equal to unity. The risk of failure that would result from the apparent safety index is higher than borne out by experience. Perhaps more important is the fact that it is necessary to assume elastic and determinate properties. These restrictions are removed if the various uncertainties are examined separately. It is then shown that their combined effect leads to a global uncertainty of a random nature, whose mean value is less than 1.0. The actual risk of failure is 5–10 times lower than the apparent one.

Seasonal trends in the stable isotopic composition of snow and meltwater runoff in a subarctic catchment at Okstindan, Norway

2004 ◽  
Vol 35 (2) ◽  
pp. 119-137 ◽  
Author(s):  
S.D. Gurney ◽  
D.S.L. Lawrence
Keyword(s):  
Isotopic Composition ◽  
Mean Value ◽  
Mean Values ◽  
Stable Isotopic Composition ◽  
Meltwater Runoff ◽  
Stable Isotopic ◽  
The Mean ◽  
The Difference ◽  
Δ18o And Δd

Seasonal variations in the stable isotopic composition of snow and meltwater were investigated in a sub-arctic, mountainous, but non-glacial, catchment at Okstindan in northern Norway based on analyses of δ18O and δD. Samples were collected during four field periods (August 1998; April 1999; June 1999 and August 1999) at three sites lying on an altitudinal transect (740–970 m a.s.l.). Snowpack data display an increase in the mean values of δ18O (increasing from a mean value of −13.51 to −11.49‰ between April and August), as well as a decrease in variability through the melt period. Comparison with a regional meteoric water line indicates that the slope of the δ18O–δD line for the snowpacks decreases over the same period, dropping from 7.49 to approximately 6.2.This change points to the role of evaporation in snowpack ablation and is confirmed by the vertical profile of deuterium excess. Snowpack seepage data, although limited, also suggest reduced values of δD, as might be associated with local evaporation during meltwater generation. In general, meltwaters were depleted in δ18O relative to the source snowpack at the peak of the melt (June), but later in the year (August) the difference between the two was not statistically significant. The diurnal pattern of isotopic composition indicates that the most depleted meltwaters coincide with the peak in temperature and, hence, meltwater production.

scholarly journals Calibrating Partial Factors – Methodology, Input Data and Case Study of Steel Structures

2019 ◽  
Author(s):  
Vitali Nadolski ◽  
Árpád Rózsás ◽  
Miroslav Sýkora
Keyword(s):  
Input Data ◽  
Structural Reliability ◽  
Construction Materials ◽  
Steel Structures ◽  
Structural Performance ◽  
Limit States ◽  
Different Types ◽  
Load Effects ◽  
Previous Design

Partial factors are commonly based on expert judgements and on calibration to previous design formats. This inevitably results in unbalanced structural reliability for different types of construction materials, loads and limit states. Probabilistic calibration makes it possible to account for plentiful requirements on structural performance, environmental conditions, production and execution quality etc. In the light of ongoing revisions of Eurocodes and the development of National Annexes, the study overviews the methodology of probabilistic calibration, provides input data for models of basic variables and illustrates the application by a case study. It appears that the partial factors recommended in the current standards provide for a lower reliability level than that indicated in EN 1990. Different values should be considered for the partial factors for imposed, wind and snow loads, appreciating the distinct nature of uncertainties in their load effects.

Practical code calibration procedures

1979 ◽  
Vol 6 (1) ◽  
pp. 112-119 ◽  
Author(s):  
Andrzej S. Nowak ◽  
Niels C. Lind
Keyword(s):  
Probability Distributions ◽  
Design Standards ◽  
Limit States ◽  
Safety Level ◽  
Performance Factors ◽  
Code Calibration ◽  
Earthquake Load ◽  
Load Effects ◽  
Safety Indices ◽  
Selection Of

The paper deals with a procedure that can be used by a design standards committee to determine safety indices for structures and calculate optimum performance factors for limit states design. Six load components are considered: dead, sustained live, transient live, snow, wind, and earthquake load effects. The procedure is based on an approximation of the probability distributions by normal distributions in the design point situated on the failure boundary. The objective in selection of performance factors is closeness to a target safety level expressed in terms of the target safety index. A computer program was developed to be used in calibration. The procedure is illustrated by examples.

The national budget as the financial basis for the environmental policy in the EU countries

2021 ◽  
Vol 17 (8) ◽  
pp. 1567-1587
Author(s):  
Lyudmila P. KOROLEVA ◽  
Kseniya A. BELOVA ◽  
Mariya K. FROLOVA
Keyword(s):  
Environmental Policy ◽  
Environmental Protection ◽  
Mean Value ◽  
Environmental Taxes ◽  
Mean Values ◽  
Eu Countries ◽  
National Budget ◽  
Protection Costs ◽  
The Eu

Subject. The article discusses the role of the budgetary system in the EU countries in financing the environmental policy of States. We analyze the volume and structure of environmental taxes and national budgetary spending on environmental protection, and their equilibrium. Objectives. We trace modern trends in the environmental portion of the EU countries’ budgets and substantiate thresholds of budgetary revenue and expenditures with respect to the environment in the Russian Federation. Methods. The study is based on general, economic-statistical methods and methods of economic analysis of trend series. Results. Having analyzed ecotaxes and budgetary spending on environmental protection in 2010–2019, we traced the stabilizing tendency of the budgetary contribution to finance of the environmental policy in 27 EU countries in terms of income and expenditures for environmental protection, the differentiation of the above indicators across the EU countries. In the EU countries, local authorities are obviously in charge of financing environmental protection costs, maintaining the surplus of the environmental portion of national budgets. We measured the mean value of environmental taxes and national budget spending in environmental protection in 27 EU countries. Conclusions and Relevance. As the EU actively promotes sustainable development values, respective budgetary systems continue to make more or less the same contribution throughout 2010–2019, according to aggregate data of 27 EU countries. However, the contribution significantly differs as per data of certain EU countries. Assessing the adequacy and balance of the environmental portion of the Russian consolidated budget, mean values of the EU data can be used to substantiate thresholds of the indicators.

Review of resistance factor for steel: resistance distributions and resistance factor calibration

2002 ◽  
Vol 29 (1) ◽  
pp. 109-118 ◽  
Author(s):  
B J Schmidt ◽  
F M Bartlett
Keyword(s):  
Steel Structures ◽  
Companion Paper ◽  
Resistance Factor ◽  
Statistical Parameters ◽  
Limit States ◽  
Code Calibration ◽  
Load Combination ◽  
Current Value ◽  
Tension Members ◽  
Landmark Study

Changes in the Canadian steel industry warrant a review of the steel resistance factor in CSA Standard S16 (formerly S16.1) "Limit states design of steel structures", originally calibrated in the landmark study by Kennedy and Gad Aly in 1980. This paper presents statistical parameters for the bending, compression, and tension resistances of W, WWF, and HSS components produced since 1999 that have been derived from geometric and material properties presented in a companion paper. The resistance factor for steel was recalibrated for the live and dead load combination in the 1995 National Building Code of Canada. A resistance factor of 0.95 is suitable for laterally supported beams, stocky columns, and tension members failing by yield of the gross section, whereas the current value of 0.90 is appropriate for intermediate columns and tension members failing by fracture of the net section.Key words: code calibration, member resistance, reliability, resistance factor, safety, structural steel.

PRODUCTION OF PROSTAGLANDINS E AND Fα BY CORPORA LUTEA, CORPORA ALBICANTES AND STROMA FROM THE HUMAN OVARY

1976 ◽  
Vol 68 (3) ◽  
pp. 401-408 ◽  
Author(s):  
J. R. G. CHALLIS ◽  
A. A. CALDER ◽  
SUSAN DILLEY ◽  
CHRISTINE S. FORSTER ◽  
K. HILLIER ◽  
...  
Keyword(s):  
Luteal Phase ◽  
Mean Value ◽  
Prostaglandin E ◽  
Corpora Lutea ◽  
Synthetase Activity ◽  
Mean Values ◽  
Late Luteal Phase ◽  
Stromal Tissue ◽  
The Mean

SUMMARY This study has shown that corpora lutea, stromal tissue and corpora albicantes from human ovaries contain prostaglandin E (PGE) and PGFα, and that the two former tissues can synthesize these prostaglandins during incubation. Enhanced synthesis, especially of PGE, occurred on adding arachidonic acid to the incubation medium, and the presence of prostaglandin synthetase activity was conclusively demonstrated. In corpora lutea obtained during the early and mid-luteal phase, the mean concentrations of PGE and PGFα were 34·3 and 9·6 ng/g respectively (mean ratio PGE:PGFα = 3·7); similar values were found in three corpora lutea from women at 10–12 weeks of pregnancy. All these corpora lutea contained appreciable amounts of progesterone and oestradiol-17β. Prostaglandin levels were generally lower in corpora lutea obtained during the late luteal phase, although the PGE:PGFα ratio had increased to a mean value of 8·4. In corpora albicantes, the concentrations of both PGE and PGFα were significantly higher than the levels found in corpora lutea (P < 0·01), whilst the mean ratio of PGE:PGFα had fallen significantly to 1·8 (P < 0·01). Prostaglandin levels in stromal tissue varied considerably between individuals. The mean values were significantly lower than those of the corpora albicantes (P < 0·01) but not significantly different to corpora lutea at any stage. These findings are discussed in relation to the possible role of prostaglandins in ovarian steroidogenesis and corpus luteum regression in man.

Platelet Activation in Muscle Contraction Headache and Migraine

Cephalalgia ◽  
1987 ◽  
Vol 7 (4) ◽  
pp. 239-243 ◽  
Author(s):  
Takao Takeshima ◽  
Tokio Shimomura ◽  
Kazuro Takahashi
Keyword(s):  
Muscle Contraction ◽  
Platelet Activation ◽  
Mean Value ◽  
Point Of View ◽  
Healthy Controls ◽  
Platelet Factor ◽  
Mean Values ◽  
Migraine Group ◽  
The Mean

In migraine, the role of platelets is regarded as an important factor. We investigated plasma beta-thromboglobulin (BTG), platelet factor 4 (PF4), and 5-hydroxytryptamine (5-HT) in migraine patients and muscle contraction headache (MCH) patients during headache-free periods. The mean values of the plasma BTG, PF4, and 5-HT concentrations in the migraine group and the MCH group were significantly higher than those in healthy controls. The mean value of the plasma BTG concentration was significantly higher in the migraine group than in the MCH group, but the differences in the mean plasma PF4 and 5-HT concentrations between the two groups were not significant. Continuous platelet activation exists in both MCH patients and migraine patients. From the biochemical point of view, we have provided evidence for a similarity between migraine and MCH.

Review of resistance factor for steel: data collection

2002 ◽  
Vol 29 (1) ◽  
pp. 98-108 ◽  
Author(s):  
B J Schmidt ◽  
F M Bartlett
Keyword(s):  
Yield Strength ◽  
Steel Production ◽  
Steel Structures ◽  
Companion Paper ◽  
Resistance Factor ◽  
Statistical Parameters ◽  
Limit States ◽  
Geometric Properties ◽  
Code Calibration ◽  
Landmark Study

Changes in the Canadian steel industry warrant a review of the steel resistance factor in CSA Standard S16 (formerly S16.1) "Limit states design of steel structures", originally calibrated in the landmark study by Kennedy and Gad Aly in 1980. This paper summarizes data collected in 1999 and 2000 to determine statistical descriptions of geometric and material properties of rolled W, WWF, and HSS shapes that represent current steel production. Distinct sub-populations have been encountered within a single grade of WWF or HSS material. The geometric properties of rolled W, WWF, and HSS shapes produced to CSA Standard G40.20 have not significantly changed from the values reported by Kennedy and Gad Aly. The statistical parameters for yield strength have improved significantly for HSS shapes, improved slightly for WWF shapes, and worsened slightly for rolled W shapes. Complete summaries of the statistical data are presented. In a companion paper, these data are used to review the resistance factor for steel.Key words: code calibration, geometric properties, reliability, steel, tensile strength, yield strength.

scholarly journals Observations of the Nonclassical Feature of Photon Bunching on a Beam Splitter using Coherent Photons along the Same Input Port

2021 ◽  
Author(s):  
Sangbae Kim ◽  
Byoung S. Ham
Keyword(s):  
Beam Splitter ◽  
Phase Locking ◽  
Mean Value ◽  
Input Port ◽  
Light Sources ◽  
Mean Values ◽  
Wave Nature ◽  
The Mean ◽  
Quantum Phenomena

Abstract One of the most striking quantum phenomena is photon bunching resulting from coincidently impinging two-indistinguishable photons on a beam splitter (BS) from two different input ports. Such a nonclassical feature has also been observed even between two independent light sources through either coherence optics resulting in phase locking or post-selected measurements such as quantum beating-based gating. Recently, BS physics regarding quantum features has been discussed using pure coherence optics based on phase basis superposition of the BS. Here, we experimentally demonstrate coherent photon bunching on a BS, where coherent photons come from the same input port. Although the mean values of both output photons are uniform and equal to each other, the mean value of the coincidence measurements between two output photons results in the nonclassical feature of photon bunching at a 50% rate. For this unprecedented result, we discuss the origin of indistinguishability for this quantum feature using the wave nature of a photon to understand the role of a BS in quantum mechanics.

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

Sign in / Sign up

Export Citation Format

Share Document