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101.
102.
The viscosities of hydrous haplogranitic melts synthesized by hydrothermal fusion at 2 kbar pressure and 800 to 1040° C have
been measured at temperatures just above the glass transition and at a pressure of 1 bar using micropenetration techniques.
The micropenetration viscometry has been performed in the viscosity range of 109 Pa s to 1012 Pa s. The samples ranged in water content from 0.4 to 3.5 wt%. For samples with up to 2.5 wt% H2O, the water contents have been determined using infrared spectroscopy obtained before and after each viscometry experiment
to be constant over the duration of the measurements. Above this water content a measurable loss of water occurs during the
viscometry.
The viscosity data illustrate an extremely nonlinear decrease in viscosity with added water. The viscosity drops drastically
with the addition of 0.5 wt% of water and then shallows out at water contents of 2 wt%. An additional viscosity datum point
obtained from the analysis of fluid inclusions in a water-saturated HPG8 confirms a near invariance of the viscosity with
the addition of water between 2 and 6 wt%. These measurements may be compared directly with the data of Hess et al. (1995,
in press) for the effects of excess alkali and alkaline earth oxides on the viscosity of HPG8 (also obtained at 1 bar). The
viscosity of the melts, compared on an equivalent molar basis, increases in the order H2O<(Li2O<Na2O< K2O<Rb2O,Cs2O<BaO<SrO<CaO<MgO< BeO). The extraordinary decrease in melt viscosity with added water is poorly reproduced by the calculation
scheme of Shaw (1972) for the range of water contents investigated here. The speciation of water in the quenched glasses can
be used to quantify the dependence of the viscosity on hydroxyl content. Considering only the hydroxyl groups as active fluidizers
in the hydrous melts the nonlinearity of the viscosity decrease and the difference with the effects of the alkali oxides becomes
larger. Consequences for degassing calcalkaline rhyolite are discussed.
Received: 17 August 1995/Accepted: 8 January 1996 相似文献
103.
The effects of the addition of Al2O3 on the large stable two liquid field in the SiO2-TiO2-CaO-MgO-FeO system were experimentally determined. The increase of Al2O3 content in the starting composition results in the decrease of critical temperature, phase separation and liquidus temperature of the two liquid field until it is rendered completely metastable. The shrinkage of the two liquid field indicates that Al2O3 is acting in the role of a network former and homogenizes the structure of the two melts. In this alkali-free system Al+3 utilizes the divalent cations, Ca+2 and Mg+2, for local charge balance with a preference for Ca+2 over Mg+2. Thus, AlO4 tetrahedra combine with SiO4 tetrahedra to form an aluminosilicate framework which polymerizes the SiO2-poor melt and makes it structurally more similar to the SiO2-rich melt. However, Ca+2 and Mg+2 are not as efficient in a charge balancing capacity as the monovalent K+ and Na+ cations. The lack of alkalis in this system limits the stability of AlO4 tetrahedra in the highly polymerized SiO2-rich melt and results in the preference of Al2O3 for the SiO2-poor melt. The partitioning systematics of Ti are virtually identical to those of Al. It is concluded that Ti occurs in tetrahedral coordination as a network forming species in both the high — and low — SiO immiscible melts. 相似文献
104.
Fridolin Weber Peter O. Hess Benno Bodmann José de Freitas Pacheco Dimiter Hadjimichef Marcelo Netz-Marzola Geovane Naysinger Moisés Razeira César A. Zen Vasconcellos 《Astronomische Nachrichten》2024,345(2-3):e230148
This paper focuses on the implications of a commutative formulation that integrates branch-cutting cosmology, the Wheeler–DeWitt equation, and Hořava–Lifshitz quantum gravity. Building on a mini-superspace structure, we explore the impact of an inflaton-type scalar field on the wave function of the Universe. Specifically analyzing the dynamical solutions of branch-cut gravity within a mini-superspace framework, we emphasize the scalar field's influence on the evolution of the evolution of the wave function of the Universe. Our research unveils a helix-like function that characterizes a topologically foliated spacetime structure. The starting point is the Hořava–Lifshitz action, which depends on the scalar curvature of the branched Universe and its derivatives, with running coupling constants denoted as . The corresponding wave equations are derived and are resolved. The commutative quantum gravity approach preserves the diffeomorphism property of General Relativity, maintaining compatibility with the Arnowitt–Deser–Misner formalism. Additionally, we delve into a mini-superspace of variables, incorporating scalar-inflaton fields and exploring inflationary models, particularly chaotic and nonchaotic scenarios. We obtained solutions for the wave equations without recurring to numerical approximations. 相似文献
105.
Fridolin Weber Peter O. Hess Benno Bodmann José de Freitas Pacheco Dimiter Hadjimichef Marcelo Marzola Geovane Naysinger Moisés Razeira César A. Zen Vasconcellos 《Astronomische Nachrichten》2024,345(2-3):e230152
This article focuses on the implications of the recently developed commutative formulation based on branch-cutting cosmology, the Wheeler–DeWitt equation, and Hořava–Lifshitz quantum gravity. Assuming a mini-superspace of variables, we explore the impact of an inflaton-type scalar field on the dynamical equations that describe the trajectories evolution of the scale factor of the Universe, characterized by the dimensionless helix-like function . This scale factor characterizes a Riemannian foliated spacetime that topologically overcomes the big bang and big crunch singularities. Taking the Hořava–Lifshitz action as our starting point, which depends on the scalar curvature of the branched Universe and its derivatives, with running coupling constants denoted as , the commutative quantum gravity approach preserves the diffeomorphism property of General Relativity, maintaining compatibility with the Arnowitt–Deser–Misner formalism. We investigate both chaotic and nonchaotic inflationary scenarios, demonstrating the sensitivity of the branch-cut Universe's dynamics to initial conditions and parameterizations of primordial matter content. The results suggest a continuous connection of Riemann surfaces, overcoming primordial singularities and exhibiting diverse evolutionary behaviors, from big crunch to moderate acceleration. 相似文献
106.
Peter O. Hess Fridolin Weber Benno Bodmann José de Freitas Pacheco Dimiter Hadjimichef Marcelo Netz-Marzola Geovane Naysinger Moisés Razeira César A. Zen Vasconcellos 《Astronomische Nachrichten》2024,345(2-3):e230162
This article focuses on the implications of a noncommutative formulation of branch-cut quantum gravity. Based on a mini-superspace structure that obeys the noncommutative Poisson algebra, combined with the Wheeler–DeWitt equation and Hořava–Lifshitz quantum gravity, we explore the impact of a scalar field of the inflaton-type in the evolution of the Universe's wave function. Taking as a starting point the Hořava–Lifshitz action, which depends on the scalar curvature of the branched Universe and its derivatives, the corresponding wave equations are derived and solved. The noncommutative quantum gravity approach adopted preserves the diffeomorphism property of General Relativity, maintaining compatibility with the Arnowitt–Deser–Misner Formalism. In this work we delve deeper into a mini-superspace of noncommutative variables, incorporating scalar inflaton fields and exploring inflationary models, particularly chaotic and nonchaotic scenarios. We obtained solutions to the wave equations without resorting to numerical approximations. The results indicate that the noncommutative algebraic space captures low and high spacetime scales, driving the exponential acceleration of the Universe. 相似文献
107.
The effects of a minimal length on the Kerr metric are studied within the pseudo-complex General Relativity (pcGR), which has a minimal length parameter and also depends on a -dependent metric, allowing for the accumulation of dark energy around a star. The relevant parameters are the rotational Kerr parameter , the mass of a black hole, and a parameter measuring the amount of dark energy accumulated. It is found that the metric is modified by a factor, depending on , resulting in a maximal acceleration. This factor shows several singularities. For small black holes, the corresponding effective potentials exhibit potential barriers, avoiding the increase of the black hole's mass. It is found that the effects of a minimal length are only of importance for very small mass black holes and vanish for macroscopic black holes. 相似文献
108.
Which catchment characteristics control the temporal dependence structure of daily river flows? 下载免费PDF全文
Andrew Chiverton Jamie Hannaford Ian Holman Ron Corstanje Christel Prudhomme John Bloomfield Tim M. Hess 《水文研究》2015,29(6):1353-1369
Hydrological classification systems seek to provide information about the dominant processes in the catchment to enable information to be transferred between catchments. Currently, there is no widely agreed‐upon system for classifying river catchments. This paper develops a novel approach to classifying catchments based on the temporal dependence structure of daily mean river flow time series, applied to 116 near‐natural ‘benchmark’ catchments in the UK. The classification system is validated using 49 independent catchments. Temporal dependence in river flow data is driven by the flow pathways, connectivity and storage within the catchment and can thus be used to assess the influence catchment characteristics have on moderating the precipitation‐to‐flow relationship. Semi‐variograms were computed for the 116 benchmark catchments to provide a robust and efficient way of characterising temporal dependence. Cluster analysis was performed on the semi‐variograms, resulting in four distinct clusters. The influence of a wide range of catchment characteristics on the semi‐variogram shape was investigated, including: elevation, land cover, physiographic characteristics, soil type and geology. Geology, depth to gleyed layer in soils, slope of the catchment and the percentage of arable land were significantly different between the clusters. These characteristics drive the temporal dependence structure by influencing the rate at which water moves through the catchment and/or the storage in the catchment. Quadratic discriminant analysis was used to show that a model with five catchment characteristics is able to predict the temporal dependence structure for un‐gauged catchments. This method could form the basis for future regionalisation strategies, as a way of transferring information on the precipitation‐to‐flow relationship between gauged and un‐gauged catchments. © 2014 The Authors. Hydrological Processes by published by John Wiley & Sons, Ltd. 相似文献
109.
R. Hess 《Meteorology and Atmospheric Physics》2001,77(1-4):145-154
Summary Inaccurate specification of soil moisture contents can result in forecast errors up to several degrees centigrade. Since
direct measurements are rarely available, a variational method has been developed that assimilates synoptic measurements of
2 m-temperature in order to specify the moisture contents of the two soil layers of the Local Model at Deutscher Wetterdienst.
The analyzed values minimize a cost functional that expresses the differences between model forecast and observed screen-level
temperatures. The minimization is performed highly efficiently and only two additional forecasts are required but neither
tangent linear nor adjoint. Background state and background error covariance matrix are updated at each analysis step in a
Kalman-filter-like cycled scheme, which takes a model error into account. The soil moisture assimilation shows improved 2 m-temperature
forecasts in case of high radiative forcing by up to 3 °C for small areas in the presented 6-week trial run. It proved stability
and robustness for general weather conditions and has become operational at DWD for the LM on 14 March 2000.
Received August 21, 2000 Revised March 26, 2001 相似文献
110.
Luz M. Cisneros‐Dozal Jeffrey M. Heikoop Julianna Fessenden R. Scott Anderson Philip A. Meyers Craig D. Allen Marcey Hess Toti Larson George Perkins Michael Rearick 《第四纪科学杂志》2010,25(6):1001-1007
Elemental (C, N, Pb) and isotopic (δ13C, δ15N) measurements of cored sediment from a small bog in northern New Mexico reveal changes in climate during the Late Pleistocene and Holocene. Abrupt increases in Pb concentration and δ13C values ca. 14 420 cal. YBP indicate significant runoff to the shallow lake that existed at that time. Weathering and transport of local volcanic rocks resulted in the delivery of Pb‐bearing minerals to the basin, while a 13C‐enriched terrestrial vegetation source increased the δ13C values of the sedimentary material. Wet conditions developed over a 300 a period and lasted for a few hundred years. The Younger Dryas period (ca. 12 700–11 500 cal. YBP) caused a reduction in terrestrial productivity reflected in decreasing C/N values, δ15N values consistently greater than 0‰ and low organic content. By contrast, aquatic productivity increased during the second half of this period, evidenced by increasing δ13C values at the time of highest abundance of algae. Dry conditions ca. 8 000–6 000 cal. YBP were characterised by low organic carbon content and high Pb concentrations, the latter suggesting enhanced erosion and aeolian transport of volcanic rock. The range in δ13C, δ15N and C/N values in the sedimentary record fall within the range of modern plants, except during the periods of runoff and drought. The sedimentary record provides evidence of natural climate variability in northern New Mexico, including short‐ (multi‐centennial) and long‐(millennial) term episodes during the Late Pleistocene and Holocene. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献