工业风险:事故数据库的意义

处在工业发展背后的正是科学,而且人们习惯于假设纯科学的风险分析就足以使事故的频率和严重性下降到接近零的数值.这已经差不多实现了.但是,社会仍然认为剩余的风险不是太高.因此,需要考虑可以从最近和不久前发生的事故和准事故中提取的反馈数据的实体.信息技术和通讯的发展,国际合作的普及以及公益意识的提高,已经使得有可能编制和不断更新有关工业事故的数据库.本文叙述了法国ARIA数据库及其应用.     

Experimental analysis of Froude number effect on air entrainment in the hydraulic jump

A hydraulic jump is characterized by strong energy dissipation and mixing, large-scale turbulence, air entrainment, waves, and spray. Despite recent pertinent studies, the interaction between air bubbles diffusion and momentum transfer is not completely understood. The objective of this paper is to present experimental results from new measurements performed in a rectangular horizontal flume with partially developed inflow conditions. The vertical distributions of the void fraction and the air bubbles count rate were recorded for inflow Froude number Fr ₁ in the range from 5.2 to 14.3. Rapid detrainment process was observed near the jump toe, whereas the structure of the air diffusion layer was clearly observed over longer distances. These new data were compared with previous data generally collected at lower Froude numbers. The comparison demonstrated that, at a fixed distance from the jump toe, the maximum void fraction C _max increases with the increasing Fr ₁. The vertical locations of the maximum void fraction and bubble count rate were consistent with previous studies. Finally, an empirical correlation between the upper boundary of the air diffusion layer and the distance from the impingement point was derived.     

Advanced post-processing and correlation analyses in high-velocity air–water flows

The interest in air–water flows has not diminished in recent years, but it is accompanied by frequent citations of early, sometimes outdated articles. A basic issue is the inadequate, incomplete interpretation of air–water flow instrumentation by hydraulic engineers and researchers. This article comments on high-velocity air–water flow measurements by means of intrusive phase detection probes. This article focus on the bubbly flow structure of high-velocity air–water flow based upon measurements by means of intrusive phase detection probes. It is shown that some advanced post-processing techniques may yield expanded information on the air–water turbulent flow properties and bubbly flow structures. The outcomes demonstrate simple techniques in high-velocity air–water flow analysis.     

Experimental Study of Gas-Liquid Interfacial Properties in a Stepped Cascade Flow

Gas-liquid interface measurements were conducted in a strongly turbulent free-surface flow (i.e., stepped cascade). Local void fractions, bubble count rates, bubble size distributions and gas-liquid interface areas were measured simultaneously in the air-water flow region using resistivity probes. The results highlight the air-water mass transfer potential of a stepped cascade with measured specific interface area over 650 m^–1 and depth-average specific area up to 310 m^–1. A comparison between single-tip and double-tip resistivity probes suggests that simple robust single-tip probes may provide accurate, although conservative, gas-liquid interfacial properties. The latter device may be used in the field and in prototype plants. Notation a = specific interface area (m^–1); a _mean = depth-average specific interface area (m^–1): a _mean=frac1Y ₉₀limits sup> Y ₉₀ sup ₀(1–C)dy; C = local void fraction; C _gas = dissolved gas concentration (kg m^–3); C _mean = depth-average mean air concentration defined as: C _mean=1–d/Y ₉₀; C _s = saturation concentration (kg m^–3); D = dimensionless air bubble diffusivity (defined by [1]); d = equivalent clear-water flow depth (m): d=limits sup> Y ₉₀ sup ₀(1–C) dy; d_ab = air bubble diameter (m); d_c = critical flow depth (m); for a rectangular channel: d _c=sqrt[3]q _w ²/g; F = air bubble count rate (Hz); F _max = maximum bubble count rate (Hz), often observed for C=50%; g = gravity acceleration (m s^–2); h = step height (m); K _L = liquid film coefficient (m s^–1); K = integration constant defined as: K=tanh ^–1 sqrt0.1)+(2D)^–1 [1]; L = chute length (m); N = velocity distribution exponent; ———– ^*Corresponding author, E-mail: h.chanson@mailbox.uq.edu.au Q _w = water discharge (m³ s^–1); q _w = water discharge per unit width m² s^–1); t = time (s); V = local velocity (m s^–1); V _c = critical flow velocity (m s^–1); for a rectangular channel: V _c=sqrt[3]q _w g V _max = maximum air-water velocity (m s^–1); V ₉₀ = characteristic air-water velocity (m s^–1) where C = 90%; W = channel width (m); x = longitudinal distance (m) measured along the flow direction (i.e., parallel to the pseudo-bottom formed by the step edges); y = distance (m) normal to the pseudo-bottom formed by the step edges; Y₉₀ = characteristic distance (m) where C=0.90; Y ₉₈ = characteristic distance (m) where C=0.98; = slope of pseudo-bottom by the step edges; = diameter (m).     

Are yolk androgens and carotenoids in barn swallow eggs related to parental quality?

Recently, evidence is mounting that females can adaptively engineer the quality of their offspring via the deposition of yolk compounds, including carotenoids and androgens. In this study, we simultaneously consider how both carotenoids and androgens in egg yolk relate to parental quality in barn swallows (Hirundo rustica erythrogaster). First, we found no relationship between concentrations or amounts of yolk androgens and carotenoids. Yolk carotenoids decreased with laying order, whereas we found no relationship between yolk androgens and laying order. Second, we tested the Investment Hypothesis, which predicts that high-quality females or females paired to high quality mates, allocate differentially more of these yolk compounds to their offspring. For carotenoids, we mostly found evidence to counter predictions of the Investment hypothesis: (1) Carotenoid concentrations varied among females, (2) heavier eggs contained lower carotenoid concentrations, although heavier yolks contained greater amounts of carotenoids, (3) eggs of earlier-laying females had lower concentrations in their eggs, and (4) yolk carotenoids were not correlated with clutch size or male plumage ornamentation. For androgens, we found weak support for the Investment Hypothesis: (1) Yolk androgens varied among females, (2) heavier eggs and yolks contained greater amounts, although not concentrations of androgens, (3) females paired to more colorful males laid eggs with greater concentrations of androgens, and (4) no effects of laying date or morphological correlates of female quality on androgen concentrations in egg yolks. Overall, these findings suggest that each yolk compound may have different functions and therefore may be regulated by different mechanisms.     

Heuristic space–time design of monitoring wells for contaminant plume characterization in stochastic flow fields

An optimization methodology for designing groundwater quality monitoring networks applicable to stochastic flow fields is presented and evaluated. The approach sets itself apart from previous techniques by incorporating the time dimension directly into the objective function. This function is extremized using a directed partial enumeration strategy guided by physical considerations related to transport processes. The result is a set of monitoring well locations and a sampling schedule that minimizes plume characterization error while satisfying constraints on the maximum number of wells and allowable number of active wells. The method is evaluated using hypothetical plumes with varying degrees of heterogeneity. Results indicate that the proposed approach is successful in generating near-optimal sampling networks that satisfy all imposed constraints. Monitoring networks with as little as three active wells and a total of 12 wells are found to provide adequate plume characterization for low toxicity contaminants.     

A Survey of Ambient Air Levels of Lead in El Paso,Texas from 1972–1979

In an era when the cost of compliance with state and federal environmental laws is rapidly rising, sometimes entities, such as operators of waste sites, are unable to pay these and other operating costs and are forced to file for bankruptcy. Citing Midlantic Nat'l Bank v. N.J. Dep't of Envtl. Protection and state environmental laws, bankruptcy trustees may be suing PRPs in bankruptcy courts to share the costs to clean up debtors' waste sites. This article suggests strategies by which PRPs can avoid litigating such lawsuits in the bankruptcy courts and instead resolve them before state and/or federal forums—where they properly belong.     

Elimination des Zytostatikums Ifosfamid während der simulierten Zersetzung von Hausmüll im Labormaßstab

Drugs are emitted into the environment by hospitals, private households, veterinary and human practices. Remnants of these products are primarily disposed of in landfill sites. At the present, there is no information available about the behaviour of pharmaceutical drugs, like their anaerobic biodegradation or adsorption, in sanitary landfills. Some of these drugs, e.g. antineoplastic substances such as ifosfamide, are supposed to be cancerogenic, mutagenic, fetotoxic or embryotoxic. Therefore, we investigated the behaviour of ifosfamide during waste decomposition in a laboratory-scale lysimeter. Up to 50% of the ifosfamide was eliminated under methanogenic conditions; but the mechanism applying for the elimination remains unclear. As far as present day knowledge is concerned, the risk for the environment through the emission of emitting ifosfamide from sanitary landfills should be negligible.