The long-term evolutions and the regional characteristics of atmospheric methane concentrations in Nagoya, 1983-1997

This study provides information on the long-term evolutions of the atmospheric methane (CH4) concentrations in Nagoya City, Japan, which were analyzed by using the continuous monitoring data observed at the eight observatory stations for 1983-1997. The 15-year records of the atmospheric CH4 concentrations were examined by means of a time-series analysis using a fast Fourier transform with a low-pass filter to elucidate the seasonal cycles and the long-term trends. The annual averages of the CH4 concentrations in Nagoya were 1.85 ppmv (parts per million by volume), 1.91 ppmv, and 1.90 ppmv in 1988, 1995 and 1997, respectively. Moreover, the annual average growth rate showed a drastic decrease from 17 ppbv (parts per billion by volume) year(-1) in 1992 to 2 ppbv year(-1) in 1993, and further down to 7 ppbv year(-1) in 1997. Comparison of the atmospheric CH4 records in Nagoya with those in global air of the northern hemisphere observed at Mauna Loa observatory in Hawaii, USA, allows us to estimate the excess concentration of CH4 in the urban atmosphere of Nagoya, which was 0.17 ppmv in 1988 and 0.15 ppmv in 1997. On a local scale, the atmospheric CH4 concentrations in the northern part of Nagoya City increased until 1992 and then gradually decreased from 1993 to 1997, although those in the south-western urban areas constantly increased at the averaged growth rate of 13 ppbv year(-1) for 1988-1997. The variation of the long-term trends of the CH4 concentrations in Nagoya may be ascribed to the emission changes from the CH4 sources due to the human activities such as waste dumping and landfills.     

Diurnal population cycle and metropolitan commuter exchange: a formal investigation of an urban pattern

"Diurnal population change in subareas of metropolitan regions is of increasing importance to urban geographers...and planners.... The urban context of daytime populations is that of commuting. Commuting, in turn, has been investigated almost exclusively within the setting of empirical economic research.... The purpose of the present study is to continue some recent attempts to find an alternative to the empirical economic approach to commuting, in advancing a formal demographic and spatial concept of diurnal population cycle." Data from the 1991 census of Canada are used. (EXCERPT)     

Analysis of point load test as a method for preliminary geotechnical classification of rocks

This paper deals with the analysis of the point load compression test made on irregular-shaped rock fragments, proposed in the late 50’s by Protodiakonov. An ample revision of the literature on the subject has been made, and a series of tests, using seven different types of rock materials, has been developed. The results obtained from these tests showed that parameters generally used in literature to relate the unconfined compressive (or tensile) strength of materials, resulting from point load tests, can lead to scattered results, due mainly to the scale effect, of great evidence in such tests. It seems possible to obtain compressive (and tensile) strength of rocks, if the ratio between failure load and the distance between load application poins, with a 3/2 exponent, is considered, in field work, as being the "point load strength index".

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Resume L’article présente une analyse critique de l’essai de compression sur échantillons irréguliers de roche, proposé par Protodiakonov vers la fin des années 50. Tout d’abord on a fait une révision de la littérature disponible sur le sujet et, après, une série d’essais sur sept types différents de matériaux. Les résultats obtenus ont montré que les paramètres plus utilisés, dans la littérature, pour définir la résistance à la compression (ou traction) des roches, d’après les essais ponctuels, peuvent provoquer une dispersion très importante des résultats. Cependant, il nous semble valable de suggérer la possibilité de déterminer, sur le chantier, la résistance à la compression (ou traction) des roches, si l’on considère le quotient entre la charge de rupture et la distance entre les deux points d’application de cette charge, le dénominateur à la puissance 3/2, comme "l’indice de charge ponctuelle".

     

Chemical and physical characteristics of a eutrophic reservoir and its tributaries: Long Lake, Washington

Surveillance on the Spokane River and its tributaries has shown that a major source of nutrients influencing the eutrophication of Long Lake was the effluent of the Spokane primary sewage treatment plant. Existing concentrations of nitrate nitrogen and orthophosphate increased threefold and tenfold, respectively, below the effluent. Of the influent phosphate phosphorus, 19 per cent was retained in the reservoir.A density current system was evident in Long Lake which altered vertical and longitudinal distribution of physical and chemical parameters. This current isolated a wedge of water on the reservoir bottom which became anaerobic. During the period of anaerobiosis, phosphate phosphorus and nitrogen maxima were present in the hypolimnion.     

Radon and 'King Solomon's Miners': Faynan Orefield, Jordanian Desert

Concentrations of 222Rn were measured in ancient copper mines which exploited the Faynan Orefield in the South-Western Jordanian Desert. The concentrations of radon gas detected indicate that the ancient metal workers would have been exposed to a significant health risk and indicate that any future attempt to exploit the copper ores must deal with the hazard identified. Seasonal variations in radon concentrations are noted and these are linked to the ventilation of the mines. These modern data are used to explore the differential exposure to radon and the health of ancient mining communities.     

The impact of preoxidation of SAS on biosorption efficiency on activated carbon

We have studied the process of a prolonged dynamic filtration on activated carbon in two biosorption systems — without preoxidation treatment of the initial matter and after ozonization. It has been shown that given the uniform load on activated carbon terms of the organic matter the efficiency of the biosorption process after preozonization is 2.3 times as small compared with that that without pretreatment, which correlates with the change of adsorption free energy.     

Distortional buckling of monosymmetric I-beams

A finite element method which is applicable to studying the distortional buckling of fabricated monosymmetric I-beams is briefly described. The method is used to demonstrate the effects of web slenderness on a monosymmetric I-beam whose smaller flange is in compression. A study is also made of the effects of monosymmetry on the distortional buckling of an I-beam with a slender web in uniform moment and moment gradient. Based on parameter studies using the finite element method, a design equation is developed which may be used to determine the distortional buckling stress of a monosymmetric I-beam under moment gradient.