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  • 1
    Electronic Resource
    Electronic Resource
    The flow in a narrow duct with an indentation or hump on one wall (1990)
    Springer
    Heat and mass transfer 25 (1990), S. 69-76 
    Details
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Diese Untersuchung befaßt sich mit der Strömung in einem schmalen Kanal mit einer Einbuchtung oder Wölbung an einer Wand, mit der Annahme, daß ε das Verhältnis der Kanallänge zu der Länge der Einbuchtung oder Wölbung klein ist. Dies ermöglicht, daß die beschreibenden Gleichungen vereinfacht werden können und eine analytische Lösung mit der AnnahmeRe (Re basierend auf der Kanallänge) gleich 0 (1) erhalten werden kann. Die einfache Lösung ist nicht mehr anwendbar, wennRe gleich 0 (ε−1) ist. Numerische Lösungen werden für den Fall erhalten, daßR=εRe gleich 0 (1) ist. Dies zeigt, daß es für hinreichend großesR Gebiete mit Gegenstrom sowohl in der Einbuchtung als auch an der flachen Wand gegenüber gibt und für den Fall einer Wölbung, daß diese stromabwärts existieren.
    Notes: Abstract This paper deals with the flow in a narrow duct with an indentation or hump on one wall, on the assumption that ε, the ratio of the duct width to the length of the indentation or hump, is small. This enables the governing equations to be simplified and an analytic solution is derived on the assumption thatRe (the Reynolds number based on duct width) is of 0 (1). This simple solution breaks down whenRe is of 0 (ε−1) and numerical solutions are obtained for the case whenR=εRe is of 0 (1). These show, forR sufficiently large, that there are regions of reversed flow both in the indentation and on the plane wall opposite to it, and for humps, regions of reversed flow downstream.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01590291
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  • 2
    Electronic Resource
    Electronic Resource
    Denitrification with and without maize plants (Zea mays L.) under irrigated field conditions (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 323-328 
    Details
    ISSN: 1432-0789
    Keywords: Key words Denitrification ; Denitrification potential ; Irrigated field ; Mineralizable carbon ; Effect of maize plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The study was conducted under irrigated field conditions to examine the effect of maize plants on denitrification. Both planted and unplanted field plots received 150kgNha–1 as urea. In a third treatment, which was also planted and received urea at 150kgNha–1, the soil nitrate N content was brought up to equal to that in the unplanted plots by applying additional doses of N as calcium nitrate. Soil cores were collected 24 and 72h after irrigation and the denitrification rate was measured by the acetylene inhibition method. Nitrate-N content, aerobically mineralizable C, microbial biomass carrying capacity and denitrification potential were also studied on field-moist soil. Maize plants grown under field conditions always had the potential to increase denitrification in conditions of both high and low water-filled porosity. When nitrate-N content of the planted soil decreased due to plant uptake, denitrification was reduced in the planted soils. However, when nitrate-N uptake by plants was compensated through additional doses of nitrate fertilizer, denitrification was always higher in planted than unplanted soil. The stimulatory effect of plants on denitrification was observed at both high and low soil nitrate-N concentrations, though it was more pronounced at high nitrate-N levels. The effect of plants on denitrification and related parameters was confined to the root zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050251
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  • 3
    Electronic Resource
    Electronic Resource
    Nitrous oxide emissions from an irrigated sandy-clay loam cropped to maize and wheat (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 189-196 
    Details
    ISSN: 1432-0789
    Keywords: Key words Irrigation ; Maize ; Nitrous oxide ; Urea ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Nitrous oxide (N2O) emissions were measured from an irrigated sandy-clay loam cropped to maize and wheat, each receiving urea at 100 kg N ha–1. During the maize season (24 August–26 October), N2O emissions ranged between –0.94 and 1.53 g N ha–1 h–1 with peaks during different irrigation cycles (four) ranging between 0.08 and 1.53 g N ha–1 h–1. N2O sink activity during the maize season was recorded on 10 of the 29 sampling occasions and ranged between 0.18 and 0.94 g N ha–1 h–1. N2O emissions during the wheat season (22 November–20 April) varied between –0.85 and 3.27 g N ha–1 h–1, whereas peaks during different irrigation cycles (six) were in the range of 0.05–3.27 g N ha–1 h–1. N2O sink activity was recorded on 14 of the 41 samplings during the wheat season and ranged between 0.01 and 0.87 g N ha–1 h–1. Total N2O emissions were 0.16 and 0.49 kg N ha–1, whereas the total N2O sink activity was 0.04 and 0.06 kg N ha–1 during the maize and wheat seasons, respectively. N2O emissions under maize were significantly correlated with denitrification rate and soil NO3 –-N but not with soil NH4 +-N or soil temperature. Under wheat, however, N2O emissions showed a strong correlation with soil NH4 +-N, soil NO3 –-N and soil temperature but not with the denitrification rate. Under either crop, N2O emissions did not show a significant relationship with water-filled pore space or soil respiration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050419
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  • 4
    Electronic Resource
    Electronic Resource
    Denitrification losses from an irrigated sandy-clay loam under a wheat-maize cropping system receiving different fertilizer treatments (1997)
    Springer
    Biology and fertility of soils 26 (1997), S. 35-42 
    Details
    ISSN: 1432-0789
    Keywords: Key words Acetylene inhibition ; Denitrification ; Farmyard manure ; Irrigated wheat-maize ; Urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Studies were conducted on denitrification in the plough layer of an irrigated sandy-clay loam under a wheat-maize cropping system receiving different fertilizer treatments. The treatments were: N-100 (urea-N at 100kgha–1year–1), N-200 (urea-N at 200kgha–1year–1), FYM-16 (farmyard manure at 16 tonnes ha–1year–1), FYM-32 (farmyard manure at 32 tonnesha–1year–1) and the control (unfertilized). Averaged across sampling dates during the wheat season, the denitrification rate as measured by the C2H2-inhibition/soil-core incubation method was highest in N-200 (83gNha–1day–1), followed by FYM-32 (60gNha–1day–1, N-100 (51gNha–1day–1), FYM-16 (47gNha–1day–1) and the control (33gNha–1 day–1). During the maize growing season, average denitrification rate was highest in FYM-32 (525gNha–1day–1), followed by FYM-16 (408gNha–1day–1), N-200 (372gNha–1day–1, N-100 (262gNha–1day–1) and the control (203gNha–1day–1). Denitrification loss integrated over the whole vegetation period was at a maximum under FYM-32 (13.9kgNha–1), followed by N-200 (11.8kgNha–1), FYM-16 (10.6kgNha–1) and N-100 (8.0kgNha–1), whereas the minimum was observed for the control (5.8kgNha–1). Under both crops, denitrification was significantly correlated with water-filled pore space and soil NO3 –-N. The best multiple regression models accounted for 52% and 70% of the variability in denitrification under wheat and maize, respectively. Results indicated that denitrification is not an important N loss mechanism in this well-drained, irrigated sandy-clay loam under a wheat-maize cropping system receiving fertilizer inputs in the range of 100–200kgNha–1year–1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050340
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  • 5
    Electronic Resource
    Electronic Resource
    Carbon availability and microbial biomass in soil under an irrigated wheat-maize cropping system receiving different fertilizer treatments (1997)
    Springer
    Biology and fertility of soils 25 (1997), S. 63-68 
    Details
    ISSN: 1432-0789
    Keywords: Key words Microbial biomass ; Carbon availability ; Microbial biomass turnover ; Wheat-maize rotation ; Urea ; Farmyard manure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seasonal changes in carbon availability and microbial biomass were studied in soil under an irrigated wheat-maize cropping system receiving different fertilizter treatments over the past 10 years. Treatments included N-100 and N-200 (urea at 100 and 200kgNha–1 year–1, respectively), FYM-16 and FYM-32 (farmyard manure at 16 and 32tha–1 year–1, respectively) and a control (unfertilized). Aerobically mineralizable carbon (AMC; C mineralized after 10 days aerobic incubation at 30°C) increased (13–16%) under wheat at both rates of urea whereas under maize it increased (22%) only with the lower rate of urea. Farmyard manure also increased the content of soil AMC under both crops, the effect being two- to threefold higher under wheat than under maize. Urea application caused an 32–78% increase in the specific respiratory activity (SRA) under wheat but caused an 11–50% decrease during the maize season. Farmyard manure also resulted in a higher SRA under both crops but only at the higher application rate. Under wheat, microbial biomass C (MBC) decreased in urea-treated plots but showed a slight increase at the higher rate of FYM. During the maize season, MBC was higher under both urea (42–46%) and FYM (36–47%) treatments as compared to the control. Microbial biomass turnover rate was highest for FYM-32 (2.08), followed by FYM-16 and urea treatments (1.35–1.49); control plots showed a turnover rate of 0.82. The higher AMC and SRA during the active growth period of wheat than that of maize indicated that root-derived C from wheat was higher in amount and more easily degradable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050281
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  • 6
    Electronic Resource
    Electronic Resource
    Denitrification and total fertilizer-N losses from an irrigated cotton field (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 270-278 
    Details
    ISSN: 1432-0789
    Keywords: Key words Acetylene inhibition ; Denitrification ; Cotton ; Nitrous oxide entrapment ; 15N-balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In a 2-year field study, denitrification loss was measured from an irrigated sandy-clay loam under cotton receiving urea-N at 158–173 kg ha–1. An acetylene inhibition-soil core method was employed for the direct measurement of denitrification, considering also the N2O entrapped in the soil. Taking into account the N2O evolved from soil cores and that entrapped in the soil, a total of 65.7 kg N ha–1 and 64.4 kg N ha–1 was lost due to denitrification during the 1995 and 1996 cotton-growing seasons, respectively. Most (〉70%) of the denitrification loss occurred during June–August, a period characterized by high soil temperatures and heavy monsoon rains. On average, 35% of the denitrification-N2O was found entrapped in the soil and the amount of entrapped N2O was significantly correlated with head space N2O concentration and with water-filled pore space. 15N-balance during the 1996 growing season revealed a loss of 71.8 kg N ha–1. It was concluded that a substantial proportion of the fertilizer-N applied to irrigated cotton is lost under the semiarid subtropical climatic conditions prevailing in the Central Punjab region of Pakistan and that denitrification is the major N loss process under irrigated cotton in this region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050656
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  • 7
    Electronic Resource
    Electronic Resource
    Cyclic voltammetry of supported ''cluster'' catalysts containing Pt, Ru and Cu
    Amsterdam : Elsevier
    Applications of Surface Science 6 (1980), S. 62-70 
    Details
    ISSN: 0378-5963
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0378-5963(80)90056-2
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  • 8
    Electronic Resource
    Electronic Resource
    The hazard rate of new establishments - A first report
    Amsterdam : Elsevier
    Economics Letters 36 (1991), S. 409-412 
    Details
    ISSN: 0165-1765
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0165-1765(91)90207-2
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  • 9
    Electronic Resource
    Electronic Resource
    Anomalous magnetic quenching of ortho-positronium in a solution of nitrobenzene in isooctane
    Amsterdam : Elsevier
    Chemical Physics Letters 197 (1992), S. 141-144 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(92)86036-H
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  • 10
    Electronic Resource
    Electronic Resource
    The dynamics of corporate profits
    Amsterdam : Elsevier
    European Economic Review 33 (1989), S. 1625-1639 
    Details
    ISSN: 0014-2921
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0014-2921(89)90082-2
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