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  • Springer  (50)
  • American Institute of Physics  (25)
  • 1995-1999  (75)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Microsystem technologies 3 (1997), S. 145-154 
    ISSN: 1432-1858
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Technik allgemein
    Notizen: Abstract  In recent years, developments in the micro electronics industry have focused on semiconductors and semiconductor processes. However, microcircuit assembly technologies have lagged chip development. This has spurred research in interconnection and packaging creating many new technologies and enhancing integration. These new microelectronic technologies are enabling micro systems, and resulting in products, from portable work stations to advanced automotive electronics. This evolution of technology has also created the need to reexamine how we achieve a reliable system. Clearly, in highly competitive marketplaces, reliability is a key element in achieving successful products. To achieve a reliable product in a cost effective manner, “upstream problem solving” must be employed which focuses on root cause of failure. This paper provides an overview of the reliability assessment process needed to achieve effective microsystem development. A case study of reliability in a complex multi-chip module is presented which includes an assessment of the stochastic nature of via fatigue by applying Monte Carlo simulations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1432-1394
    Schlagwort(e): Key words. Gravimetric geoid determination ; Modified kernels ; Truncation error reduction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung
    Notizen: Abstract. A deterministic modification of Stokes's integration kernel is presented which reduces the truncation error when regional gravity data are used in conjunction with a global geopotential model to compute a gravimetric geoid. The modification makes use of a combination of two existing modifications from Vaníček and Kleusberg and Meissl. The former modification applies a root mean square minimisation to the upper bound of the truncation error, whilst the latter causes the Fourier series expansion of the truncation error to coverage to zero more rapidly by setting the kernel to zero at the truncation radius. Green's second identity is used to demonstrate that the truncation error converges to zero faster when a Meissl-type modification is made to the Vaníček and Kleusberg kernel. A special case of this modification is proposed by choosing the degree of modification and integration cap-size such that the Vaníček and Kleusberg kernel passes through zero at the truncation radius.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Insectes sociaux 43 (1996), S. 309-317 
    ISSN: 1420-9098
    Schlagwort(e): Myrmica tahoensis ; sex ratio ; relatedness ; microsatellite DNA ; sex allocation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Sex allocation was measured across six seasons in colonies of the facultatively polygynous antMyrmica tahoensis. The overall proportion of colonies that produced sexuals was constant throughout the study, but population-level sex ratios varied considerably. In 1991, 1993, and 1995, a significantly greater proportion of colonies produced females than in 1990, 1992, and 1994. Sex ratios were similar across six sites within individual years, suggesting a population-wide cause of sex-ratio variation. Individual colonies tended, on average, to produce similar sex ratios in consecutive years. Within-colony genetic relatedness, while strongly correlated with sex ratios within years, did not explain the year-to-year variation. It is suggested that extrinsic factors can limit the production of female sexuals, even when genetic relatedness is high enough to favor female production.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1432-0789
    Schlagwort(e): Crop rotation ; Field pea ; Mineral N ; Nitrogen fixation ; immobilisation ; Pisum sativum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The effects of soil incorporation with cereal straw (nil, 2.5, 5 and 10 t straw ha−1) and direct drilling on the proportion and amount of pea N derived from biological N fixation were investigated in three field experiments. Fixed N was determined by15N dilution using barley as a reference plant. The three sites were on acidic, red clay-loams in the cropping zone of southeastern Australia. Seasonal plant available soil N, as determined by the N accumulated in barley, was 31, 56 and 158 kg N ha−1, for the three sites. Incorporated straw reduced soil nitrate at sowing by 10–50 kg N ha−1 (0–30 cm), and 5 or 10 t straw ha−1 reduced barley uptake of N by 10–38 kg N ha−1. However, reducing plant available soil N was generally ineffective for increasing the N fixed by pea. Fixed N increased only at the site with the least plant-available N, and only one-third of the increase could be attributed to lower soil N uptake by pea. There was no evidence that direct drilling pea increased fixed N by decreasing crop uptake of soil N. It is proposed that a lower requirement for soil N by pea as compared to barley, and availability of mineral N beneath the soil layer treated with straw, minimise the effectiveness of straw incorporation for increasing the N fixed by pea.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1432-2056
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A large ultra-oligotrophic Antarctic freshwater lake, Crooked Lake, was investigated between January 1993 and November 1993. The water column supported a small phytoplankton community limited by temperature, nutrient availability and, seasonally, by low photosynthetically active radiation. Chlorophyll a concentrations were consistently low (〈1 g l−1) and showed no obvious seasonal patterns. Production rates were low, ranging from non-detectable to 0.56 g C l−1 h−1, with highest rates generally occurring towards the end of the austral winter and in spring. The pattern of carbon fixation indicated that the phytoplankton was adapted to low light levels. Chlorophyll a specific photosynthetic rates (assimilation numbers) ranged from non-detectable to 1.27 gC (g chlorophyll a)−1 h−1. Partitioning of photosynthetic products revealed carbon incorporation principally into storage products such as lipids at high light fluxes with increasing protein synthesis at depth. With little allochthonous input the data suggest that lake dynamics in this Antarctic system are driven by phytoplankton activity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Astrophysics and space science 224 (1995), S. 181-184 
    ISSN: 1572-946X
    Schlagwort(e): Abundances ; Molecular ; Infrared
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have observed C2H2 and HCN rovibrational transitions near 13µm in absorption against GL2591. We also have observed rotational transitions at 0.6-3 mm of CS, HCN, H2CO, and HCO+. Analysis of the rotational lines, which arise in the extended cloud around the source, shows that no single density model can explain all the data. Models with density and temperature gradients do much better; in particular models withn(r) αr −1.5 can reproduce the observed pattern of emission line strengths. The abundances show significant depletion compared to models of gas-phase chemistry. The rovibrational data were analyzed in comparison to the absorption line analysis of CO by Mitchellet al. (1989). Our data are consistent with the C2H2 and HCN absorption arising in the same warm (200 K) and hot (1010 K) components seen in CO, but we see little evidence for the cold (38 K) component seen in CO. The rovibrational lines from higher states (J ≥ 21) indicate that the hot HCN deviates from LTE, leading to a density of about 3 × 107 cm−3. Comparison of the two data sets shows that the rovibrational absorption of HCN, rather than arising in the extended envelope, must come from a region with a small angular extent. A model in which early-time gas phase abundances are preserved on grain mantles and released at high temperature can explain the data.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of paleolimnology 13 (1995), S. 179-191 
    ISSN: 1573-0417
    Schlagwort(e): maritime Antarctic ; Signy Island ; lakes ; sediments ; Pb-210 ; Cs-137 ; radionuclide fluxes ; climate change
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract Sediment cores from three lakes (Moss, Sombre and Heywood) in the maritime Antarctic (Signy Island, South Orkney Islands) have been successfully dated radiometrically by210Pb and137Cs. The core inventories of both fallout radionuclides are an order of magnitude higher than that which can be supported by the direct atmospheric flux at this latitude. The elevated values may be explained by fallout onto the catchment during the winter being delivered directly to the lakes during the annual thaw. Two of the lakes (Sombre and Heywood) show marked increases in sediment accumulation afterc. 1950. This appears to be associated with a documented rise in temperature in the South Orkney Islands, which has caused extensive deglaciation at Signy Island.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Marine biology 132 (1998), S. 179-186 
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The relationship between sperm characteristics and reproductive success was examined in male herring, Clupea harengus L. Males were categorised as being first-time or repeat spawners on the basis of their age; they were also grouped according to whether their sperm were immediately active and exhibited forward motion on contact with seawater (FM) or had little or only vibratory motion (VM). Unlike the Pacific herring C. pallasii Valencienes, Atlantic herring sperm is usually motile on contact with seawater. The age, weight and gonadosomatic index (testes mass as a percentage of somatic mass = GSI) were measured and used as characteristics for individual fish. Sperm traits measured were (1) adenosine triphosphate (ATP) concentration, (2) sperm count, (3) duration of sperm motility. Reproductive success for each male was estimated from the fertilisation rate and from the length of larvae at hatching. Fertilisation rates for all fish were generally 〉80%. The ATP concentration of non-activated spermatozoa was negatively correlated with fertilisation rate. Among repeat spawners, fish with higher GSIs produced larvae that were larger at hatching. Although VM sperm fertilised eggs at rates equivalent to fertilisation by FM sperm, the larvae produced by VM sperm were significantly smaller at hatching. Larval length tended to increase in parallel with the duration of sperm motility, but the relationship was not significant in these tests. The results did not indicate any age or size pattern to spawning readiness in male herring. Sperm that are not yet ready to be shed are not fully motile on contact with seawater, but are still capable of fertilising eggs that hatch successfully. There is likely to be a progression of males which come into spawning readiness within a spawning shoal; therefore it is possible that paternal influences would result in a progressive decrease in larval size over the spawning period in winter-spawning Celtic Sea herring.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    General relativity and gravitation 30 (1998), S. 877-885 
    ISSN: 1572-9532
    Schlagwort(e): BRANS-DICKE THEORY ; ITS LIMIT IN GENERAL RELATIVITY
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract It is argued that the Schwarzschild black hole solution follows as a unique limit of the Brans-Dicke Class I solutions, provided the correct iterated limit is taken. Such a uniqueness is essential for the validity of a recent version of the no-hair conjecture. A non-trivial modification to this version is proposed in order to exclude Brans-Dicke Class IV solutions which appear to represent scalar hair black holes in general.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Advances in computational mathematics 6 (1996), S. 325-331 
    ISSN: 1572-9044
    Schlagwort(e): finite-difference ; partial differential equation ; fully-implicit method ; plastic forming ; binder removal ; ceramics ; 65M10
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract A mathematical model is developed to quantify the degradation of binder used for plastic forming of ceramic components and the mass transport of the degradation products. A fully-implicit finite-difference method is used to obtain numerical solutions of a non-linear differential equation governing the degradation rate, diffusion coefficient and concentration. It is able to predict the critical linear heating rate below which defects due to boiling can be avoided. Examples are given to illustrate the use of the model to investigate the effect of ceramic powder, supporting powder bed and binder properties on the critical heating rate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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