Estimation of failure probability of oil and gas transmission pipelines by fuzzy fault tree analysis

Failure of oil and gas transmission pipelines was analyzed by fault tree analysis in this paper. According to failure modes of pipeline: leakage and rupture, a fault tree of the pipeline was constructed. Fifty-five minimal cut sets of the fault tree had been achieved by qualitative analysis, while the failure probability of top event and the important analyses of basic events were evaluated by quantitative analysis. In conventional fault tree analysis, probabilities of the basic events were treated as precise values, which could not reflect real situation of system because of ambiguity and imprecision of some basic events. In order to overcome this disadvantage, a new method was proposed which combined expert elicitation with fuzzy set theories to evaluate probability of the events. As an example, failure probability of pipeline installation was assessed by using the proposed method, achieving its fuzzy failure probability of 6.4603×10⁻³. The method given in this article is effective to treat fuzzy events of FTA.     

西北典型工矿型城市街道尘埃重金属污染的环境磁学响应

以甘肃省白银市为研究区域,系统采集43个城区街道尘埃样品,并对其进行环境磁学和重金属元素特征分析.结果表明,白银市街道尘埃磁性特征以低矫顽力的磁铁矿和磁赤铁矿为主导,磁晶体粒径为较粗的假单畴(PSD)和多畴(MD)颗粒;样品低频磁化率(χlf)变化范围为(43.75~1 340.08)×10-8m3·kg-1,平均值为245.98×10-8m3·kg-1,与国内综合型大城市相比,白银市街道尘埃磁性矿物含量相对较低,但呈现明显的空间分布差异,表现为工业区高于带状交通区,带状交通区高于商业区,新城区磁性矿物含量较低;白银市各功能区污染源相对单一,工业污染对强磁性矿物的贡献占主导,污染程度空间分异显著.白银市街道尘埃样品中Cu、Pb、Zn整体含量较高,污染负荷指数(PLI)与低频磁化率(χlf)、非磁滞剩磁化率(χARM)、饱和等温剩磁(SIRM)、"软"剩磁(SOFT)相关性较高,且空间变化特征较为一致,表明反映磁性矿物含量的参数可以有效监测城市重金属污染,进而圈定重金属综合污染区域和范围,为进一步的城市污染治理工作提供快速有效的证据支持.     

Determination of bioconcentration potential of tetrachloroethylene in marine algae by 13C

The use of stable isotope of organic-carbon, organic-¹³C, as a tracer for the determination of the concentration of tetrachloroethylene (PCE), C_A, in Heterosigma akashiwo and Skeletonema costatum was examined. C_A determined by the ¹³C and GC methods showed good agreement with each other. This suggests that it is reasonable and reliable to determine the bioconcentration potentail of PCE in marine algae. Fitting values of bioconcentration potentail parameters, including uptake rate constant k₁, elimination rate constant k₂ and bioconcentration factor on the basis of dry weight BCF_D, were done not only to the time course for PCE uptake by the algae with the bioconcentration model, but also to experimental data for “percent inhibition(%)∼exposure concentration of PCE∼time” with the combined bioconcentration and probability model. The values obtained from the bioconcentration model were consistent with those from the combined bioconcentration and probability model. With the parameters (such as k₁, k₂, growth rate constant k_G, critical concentration of HOCs in the organism resulting in growth inhibition C_A¹ and spread factor S) the variability in toxicity (such as EC₁₀, EC₅₀, EC₇₀) can be estimated from the combined bioconcentration and probability model, which fits well with the experimental observations.     

Meridional and vertical CO and CH4 distributions in the background troposphere (70°N-60°S; 0–12 km altitude) from scientific aircraft measurements during the stratoz III experiment (June 1984)

During the STRATOZ III experiment (June 1984) designed for a study of trace gases in the atmosphere, more than 2000 concurrent measurements of CO and CH₄ by gas chromatography were obtained from a series of flights aboard a scientific aircraft “Caravelle 116” between 70°N and 60°S, and up to a cruising altitude of 12 km, over the Atlantic Ocean and along the American, African and European continents.While a global interpretation of the data must await the examination of the whole series of compounds measured, a preliminary analysis of the results obtained for CO and CH₄ is reported here.The CO and CH₄ mixing ratios are found to be higher in the Northern Hemisphere than in the Southern, which reflects the meridional distribution of their sources and the influence of tropospheric photochemistry. A prominent CO difference between the two hemispheres is observed in the continental air (NH: 100–200 ppb; SH: 80–90 ppb) while the oceanic air is much more homogeneous (NH: 80–90 ppb; SH: 60–70 ppb). In the case of CH₄, a regular decrease is observed between the high latitudes of the Northern Hemisphere and those of the Southern.For the Southern Hemisphere, the CO values are in agreement with literature data, but for the Northern they are lower than previously reported. The CH₄ results suggest the possible existence of natural sources in the Southern Hemisphere (Amazonia; South Pacific).A comparison of the measurements made in the Southern Hemisphere with reliable data sets previously reported in the literature confirms an increase rate of 1.2 ± 0.3 % per year for CH₄, but does not provide any evidence for a long term variation of the CO content.The comprehensive data reported here will be of valuable interest to improve the understanding of the physico-chemistry of the troposphere and its evolution.     

Real-time,in situ measurements of atmospheric optical absorption in the visible via photoacoustic spectroscopy—IV. Visibility degradation and aerosol optical properties in Los Angeles

Aerosol light absorption (b_abs) has been measured in real-time in Los Angeles with a validated photoacoustic technique, and its impact on visibility degradation has been examined. These measurements were collected during ten days in the summer of 1987 for the Southern California Air Quality Study (SCAQS). Aerosol b_abs (λ = 514.5 nm) varied from an hourly average value of 7 × 10⁻⁶ m⁻¹ in the 3–4 and 4–5 a.m. periods of 13 July to 9 × 10⁻⁵ m⁻¹ in the 7–8 a.m. period of both 28 August and 3 September. This b_abs, which is due solely to elemental carbon (EC) showed a distinct diurnal pattern with low values at night, increasing around sunrise to higher values through mid-afternoon. Comparison of these data with aerosol light scattering data clearly illustrates that the contribution of aerosol light absorption to visibility degradation increases in importance under less polluted conditions. Other urban and rural studies show similar results.     

Developing and testing a hazard prediction task for novice drivers: A novel application of naturalistic driving videos

Introduction: Novice drivers’ inability to appropriately anticipate and respond to hazards has been implicated in their elevated crash risk. Our goal was to develop a driving hazard prediction task using naturalistic videos from the U.S. context that could distinguish between novice and experienced drivers. Method: Using the query builder from the SHRP 2 InSight Data Access Website, we identified a sample of 1034 videos for further review. Task criteria reduced these to 30 videos of near-crash events that were split into event and non-event segments and were used to develop the driving hazard prediction task (task). Participants, aged 16–20 years-old (22 novice and 19 experienced drivers) completed the task during which they watched event and non-event videos and were asked, “How likely was the driver of this car to get into a crash?” after each video. Overall ratings for hazardousness were calculated for experienced and novice drivers as well as a group difference score for hazardousness. Results: All participants rated event videos as more hazardous than non-event videos, but there was no main effect of group. Rather, there was a significant EventbyGroup interaction in which there were no group differences in hazard ratings for non-event videos, but experienced drivers rated event videos as more hazardous than novice drivers. Specific characteristics of the event videos, such as the hazard development period, were related to differences between novice and experienced drivers’ hazardousness ratings. Conclusion: To the best of our knowledge, this is the first use of naturalistic driving videos from an existing database as experimental stimuli. We found that the task discriminated between novice and experienced drivers’ ratings of hazardousness. This distinction suggests naturalistic driving videos may be viable stimuli for experimental studies. Practical Applications: The application of naturalistic driving video database for experimental research may hold promise.     

What fraction of the organic carbon in sacoglossans is obtained from photosynthesis by kleptoplastids? An investigation using the natural abundance of stable carbon isotopes

any sacoglossans (opisthobranch gastropods) have the potential for carbon acquisition from photosynthesis by plastids sequestered from their macroalgal food as well as by ingestion, digestion and assimilation of the organic carbon derived from the alga. A new method for obtaining a minimum estimate of the fraction of sacoglossan carbon supplied from photosynthesis by kleptoplastids is suggested, based on the mass balance of stable carbon isotopes at the natural abundance level. The method involves comparison of ¹³C/¹²C ratios in sacoglossans with those of the algae on which they are found. Differences in ratios between alga and sacoglossan are used to give a minimum estimate of carbon acquisition by kleptoplasty, granted assumptions about the range of ¹³C/¹²C fractionation values which can occur for marine photolithotrophs. The new method is applied to several green (ulvophycean) alga–sacoglossan associations from Rottnest Island, Western Australia, and the values compared with those obtained previously by other means. The method suggests values of up to 0.6 of the total carbon input to the sacoglossans from photosynthesis by their kleptoplastids. To improve the estimates of the minimum role of kleptoplastidy in the carbon nutrition of sacoglossans, further information is needed: (1) on the fidelity of a given sacoglossan to a given algal individual (or species), (2) on the ¹³C/¹²C ratio of the part of the alga ingested by the sacoglossan, and (3) on the allocation of dietary organic carbon and of kleptoplastidic photosynthate to carbon lost in respiration, mucopolysaccharide production and gametes (and hence not sampled with the animal). Received: 24 November 1999 / Accepted: 20 October 2000     

Hot spots and plumes: Observation by meteorological satellite

Many hot spots can be detected by Channel 3 of the sun-synchronous meteorological satellites NOAA 6–9. This is because that channel is much more sensitive to radiation from bodies in the temperature range 500–1500 K than to scattered sunshine or earth-temperature radiation. Hot bodies occupying only a small fraction of a pixel can be detected. The other channels are designed to receive much greater power from earth radiation (300 K) or scattered sunshine (6000 K).Plumes from chimneys are very difficult to detect because they are small and rapidly diluted and dispersed. Some flukes of illumination make them detectable occasionally; and some infrequent meteorological circumstances make them persistent and large. Ship trails are quite exceptional and very obvious, but they are very rare.     

Gaseous and particulate air pollution in the san gabriel mountains of southern california

In order to assess concentrations and daily patterns of air pollutants at a mountainous site in the South Coast Air Basin, a study was undertaken in the San Dimas Experimental Forest of the San Gabriel Mountains between April 1985 and October 1985. Continuous monitoring of O₃, NO, NO₂, SO₂, total S compounds and light scattering coefficient was conducted. Particulate aerosols were collected twice a week and concentrations of nitrate, ammonium and sulfate in fine (< 2.5 μm diameter) and coarse (> 2.5 μm diameter) modes were determined.For the June–August period, when the levels of photochemical smog were the highest, monthly 24-h average concentrations of the pollutants were: O₃, about 200 μg m⁻³; NO₂, 40–75 μg m⁻³; NO, 1–5 μg m ⁻³; and SO₂, 0.5–5 μgm⁻³. The concentrations of O₃ were about two times higher than in the neighboring stations of the South Coast Air Basin. O₃, SO₂ and total S concentrations peaked in the early afternoon, generally between 1500 and 1600 PST. Peak concentrations of NO occurred in the morning, generally between 1000 and 1100 PST. NO₂ concentrations typically peaked in the late afternoon between 1500 and 1800 PST, but occasionally (in 9 % of days) maximum NO₂ occurred in the morning, concurrently with the NO peaks. Daytime concentrations of the nitrate in fine aerosol fraction were generally between 100 and 600 nEq m ⁻³, those of ammonium between 50 and 300 nEq m ⁻³, and concentrations of sulfate between 60 and 250 nEq m⁻³. A 3-day denuder study showed that HNO₃can make up to 73 % of the total amount of total nitrate in the air. NO₂ was the most abundant N compound at Tan bark Flat (69–86% of the total amount of the monitored N compounds). Nitrate amounted to 9–15 %, HNO₃ to 4–11 %, ammonium to 3–9%, and NO to 1–2% of the total amount of the measured nitrogen compounds.