Effect of alcohol addition on the movement of petroleum hydrocarbon fuels in soil

Groundwater contamination by fuel spills from aboveground and underground storage tanks has been of growing concern in recent years. This problem has been magnified by the addition of oxygenates, such as ethanol and methyl-tertiary-butyl ether (MTBE) to fuels to reduce vehicular emissions to the atmosphere. These additives, although beneficial in reducing atmospheric pollution, may, however, increase groundwater contamination due to the co-solvency of petroleum hydrocarbons and by the provision of a preferential substrate for microbial utilisation. With the introduction of ethanol to diesel fuel imminent and the move away from MTBE use in many states of the USA, the environmental implications associated with ethanol additive fuels must be thoroughly investigated. Diesel fuel movement was followed in a 1-m soil column and the effect of ethanol addition to diesel fuel on this movement determined. The addition of 5% ethanol to diesel fuel was found to enhance the downward migration of the diesel fuel components, thus increasing the risk of groundwater contamination. A novel method using soil packed HPLC columns allowed the influence of ethanol on individual aromatic hydrocarbon movement to be studied. The levels of ethanol addition investigated were at the current additive level (approx. 25%) for ethanol additive fuels in Brazil and values above (50%) and below (10%) this level. An aqueous ethanol concentration above 10% was required for any movement to occur. At 25% aqueous ethanol, the majority of hydrocarbons were mobilised and the retention behaviour of the soil column lessened. At 50% aqueous ethanol, all the hydrocarbons were found to move unimpeded through the columns. The retention behaviour of the soil was found to change significantly when both organic matter content and silt/clay content was reduced. Unexpectedly, sandy soil with low organic matter and low silt/clay was found to have a retentive behaviour similar to sandy subsoil with moderate silt/clay, but little organic matter. It was concluded that sand grains might have a more important role in the adsorption of petroleum hydrocarbons than first realised. This method has shown that soil packed HPLC columns can be used to provide a quick estimate of petroleum hydrocarbon, and possibly other organic contaminant, movement in a variety of different soil types.     

Abstract and reduced-context representations in fault-finding training

The ability to transfer problem-solving expertise to new situations is regarded as an important practical skill but it is known to be sensitive to contextual differences. Employing abstract and reduced-context training tasks has been proposed as a method of fostering transferable skill but the evidence supporting this approach is limited. The research reported here aimed at assessing the effectiveness of training with diagnostic tasks of varying degrees of contextual detail. The criterion test used to measure training effectiveness was a context-rich diagnostic task that involved locating faults in a representation of a water supply and drainage system (WSDS). In the first study reported (baseline study), subjects were trained and tested on the WSDS task. Various training interventions were employed and a set of diagnostic heuristics proved to be the most effective. Two pilot studies were then carried out to determine whether training with abstract diagnostic tasks could produce transfer to the criterion test, the WSDS. Little evidence of transfer was found; therefore, it was decided to incorporate some context into training but not so much as to obscure important, conceptual task features. This was achieved by constructing reduced-context representations (RCO) of the WSDS at more than one level of abstraction (main study). Training with those representations took less time than training with the WSDS but transfer to the criterion test (the WSDS) was equally efficient. During training with the RCO representations, a technique of refusing costly test information was employed which is thought to have helped subjects discover efficient search strategies and consistently transfer them to the criterion test. This was contrasted with the verbal diagnostic heuristics of the baseline study, which had proved to be effective, but which were not always transferred consistently to the criterion test. This raises the question as to whether diagnostic strategies are necessarily best conveyed solely in verbal form, if the intention is to train transferable skill.     

Incremental Learning of Linear Model Trees

A linear model tree is a decision tree with a linear functional model in each leaf. Previous model tree induction algorithms have been batch techniques that operate on the entire training set. However there are many situations when an incremental learner is advantageous. In this article a new batch model tree learner is described with two alternative splitting rules and a stopping rule. An incremental algorithm is then developed that has many similarities with the batch version but is able to process examples one at a time. An online pruning rule is also developed. The incremental training time for an example is shown to only depend on the height of the tree induced so far, and not on the number of previous examples. The algorithms are evaluated empirically on a number of standard datasets, a simple test function and three dynamic domains ranging from a simple pendulum to a complex 13 dimensional flight simulator. The new batch algorithm is compared with the most recent batch model tree algorithms and is seen to perform favourably overall. The new incremental model tree learner compares well with an alternative online function approximator. In addition it can sometimes perform almost as well as the batch model tree algorithms, highlighting the effectiveness of the incremental implementation. Editor: Johannes Fürnkranz     

Aging and bursting bubbles in trace-contaminated water

The rise speeds and top jet drop ejection heights of rising and bursting bubbles in water are measured as a function of bubble age. Equivalent spherical diameters range from 0.08 <d < 0. 125 cm. Various types of relatively surfactant-free water are used. Both rise speeds and top jet drop ejection heights decrease with bubble age. This is due to adsorption of surface-active materials on the bubble surface which increases the rigidity of the surface and decreases its surface free energy. In general, terminal values of rise speed and ejection height are not reached at the same bubble age. The ages at which these terminal values are reached are characteristically greater for larger bubbles in a given water sample. These ages are also characteristically greater for bubbles of a given size as the concentration of surface-active material in the water decreases.     

Analysis of the Moebius Loop Magnetic Field Sensor

An analysis of the Moebius loop which provides the relationship between magnetic field and output voltage is presented. This analysis accounts for all of the loop electrical phenomena involved over the broad range of frequencies encountered in measurement of fast pulses; specifically, from dc to frequencies corresponding to a loop electrical diameter of from about 6.4 degrees to 12.8 degrees. In the usual application, the loop is small, so that this corresponds to high (typically much greater than 100 MHz) frequencies. It is found that the relationship given is valid up to the stated 6.4 degrees limit for any loop coax and connecting balanced line impedance combination, but that the validity of extensions above this limit depend on the relationship between these impedances. Loop response as a function of frequency is deduced, from which useful approximations are derived, one of which is that below a certain frequency, which is defined here, loop output voltage is proportional to the derivative of the field. Finally, a detailed numerical example is given.     

Natural history and treatment of renal vein thrombosis in children

The general features and problems of renal vein thrombosis in children are first discussed. The records of 11 children with this condition, 7 ill neonates and 4 older children with burns, are then reviewed, indicating the clinical course of the disease, how they were treated, the results, and pathological findings. From this study, the natural history is assembled and a protocol for treatment is proposed. Supportive therapy is necessary in all cases to correct dehydration and sepsis. Many children will develop a consumptive coagulopathy. Others will develop pulmonary emboli associated with thrombosis of the inferior vena cava. Anticoagulation should be achieved for these two conditions. Nonvisualization of affected renal units upon initial urographic examination virtually assures an atrophic, functionless kidney later. Nephrectomy will be required because of hypertension, persistent infection, and scarring. Thrombectomy may be attempted when bilateral nonvisualization on urography is associated with a positive venacavogram.     

The locus of interference in the perception of simultaneous stimuli.

In 3 experiments with 48 college students (18–33 yrs old), performance on well-practiced target detection tasks, both auditory and visual, was little influenced by the number of simultaneous nontargets, but suffered if simultaneous targets were detected separately. It is suggested that only targets need pass through a limited-capacity system leading to awareness (and hence availability for report); nontargets can be identified and rejected by earlier parallel, unconscious processes. Since nontarget words can be rejected on the basis of meaning, stimuli must be fully identified before the limited-capacity system. More generally, performance decrements due to divided attention are usually marked whenever simultaneous stimuli (psychophysical, verbal) must be identified separately and independently; under these circumstances all stimuli must pass through the limited-capacity system to awareness. (74 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measurement: The theory of numerical assignments.

Discusses generalizations of classical theories of measurement for concatenation (e.g., mass, length) and conjoint structures (e.g., momentum of mass–velocity pairs, loudness of intensity–frequency pairs). Results on additive representations are surveyed. Generalizations to nonadditive structures are outlined, and results are described leading to a definition of scale type in terms of the symmetries (automorphisms) of the underlying qualitative structure. For any measurement onto the real numbers, only 3 possible scale types exist that are both rich in symmetries but not too redundant: ratio, interval, and another lying between them. The possible numerical representations for concatenation structures corresponding to these scale types are described. The interval scale case leads to a generalization of subjective expected-utility theory that copes with some empirical violations of the classical theory. Partial attempts to axiomatize concatenation structures of these 3 scale types are described, and concepts are appended. Such structures are of interest because they make clear that there is a rich class of nonadditive concatenation and conjoint structures with representations of the same scale types as those used in physics. (56 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preprocessing of Signals from Bar-Coded Silicon Using a Microprocessor

Bar code is a useful method of data entry in an automated environment. The method is very popular in normal label reading (paper label with black bars on white background) because of it simplicity. However, for materials where the contrast is not good, such as silicon, the signal processing becomes more complex. This paper describes a signal-processing technique developed to measure the widths of the bars and spaces and classify them according to width sizes based on a Nearest Neighbor (NN) approach. The classified data can then be decoded to give the equivalent alphanumeric representation of the code.