Mixing Calculations Research Articles

Erratum: Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements inHg184,186and two-state mixing calculations [Phys. Rev. C89, 024307 (2014)

Erratum: Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">Hg</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>184</mml:mn><mml:mo>,</mml:mo><mml:mn>186</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>and two-state mixing calculations [Phys. Rev. C<b>89</b>, 024307 (2014)

Mixed quantum classical calculation of proton transfer reaction rates: from deep tunneling to over the barrier regimes.

We present mixed quantum classical calculations of the proton transfer (PT) reaction rates represented by a double well system coupled to a dissipative bath. The rate constants are calculated within the so called nontraditional view of the PT reaction, where the proton motion is quantized and the solvent polarization is used as the reaction coordinate. Quantization of the proton degree of freedom results in a problem of non-adiabatic dynamics. By employing the reactive flux formulation of the rate constant, the initial sampling starts from the transition state defined using the collective reaction coordinate. Dynamics of the collective reaction coordinate is treated classically as over damped diffusive motion, for which the equation of motion can be derived using the path integral, or the mixed quantum classical Liouville equation methods. The calculated mixed quantum classical rate constants agree well with the results from the numerically exact hierarchical equation of motion approach for a broad range of model parameters. Moreover, we are able to obtain contributions from each vibrational state to the total reaction rate, which helps to understand the reaction mechanism from the deep tunneling to over the barrier regimes. The numerical results are also compared with those from existing approximate theories based on calculations of the non-adiabatic transmission coefficients. It is found that the two-surface Landau-Zener formula works well in calculating the transmission coefficients in the deep tunneling regime, where the crossing point between the two lowest vibrational states dominates the total reaction rate. When multiple vibrational levels are involved, including additional crossing points on the free energy surfaces is important to obtain the correct reaction rate using the Landau-Zener formula.

Partially-Averaged Navier–Stokes Simulations of High-Speed Mixing Environment

Accurate simulation of the fuel-air mixing environment is crucial for high-fidelity scramjet calculations. We compute the velocity fields of jet into supersonic freestream flow and cavity flow typical of scramjet flame-holding applications at different scale resolutions using the partially-averaged Navier–Stokes (PANS) method. We present a sequence of variable resolution computations to demonstrate the potential of PANS method for high-speed mixing environment calculations.

Dilution of 10Be in detrital quartz by earthquake-induced landslides: Implications for determining denudation rates and potential to provide insights into landslide sediment dynamics

The concentration of 10Be in detrital quartz (10Beqtz) from river sediments is now widely used to quantify catchment-wide denudation rates but may also be sensitive to inputs from bedrock landslides that deliver sediment with low 10Beqtz. Major landslide-triggering events can provide large amounts of low-concentration material to rivers in mountain catchments, but changes in river sediment 10Beqtz due to such events have not yet been measured directly. Here we examine the impact of widespread landslides triggered by the 2008 Wenchuan earthquake on 10Beqtz in sediment samples from the Min Jiang river basin, in Sichuan, China. Landslide deposit material associated with the Wenchuan earthquake has consistently lower 10Beqtz than in river sediment prior to the earthquake. River sediment 10Beqtz decreased significantly following the earthquake downstream of areas of high coseismic landslide occurrence (i.e., with greater than ∼0.3% of the upstream catchment area affected by landslides), because of input of the 10Be-depleted landslide material, but showed no systematic changes where landslide occurrence was low. Changes in river sediment 10Beqtz concentration were largest in small first-order catchments but were still significant in large river basins with areas of 104–105 km2. Spatial and temporal variability in river sediment 10Beqtz has important implications for inferring representative denudation rates in tectonically active, landslide-dominated environments, even in large basins. Although the dilution of 10Beqtz in river sediment by landslide inputs may complicate interpretation of denudation rates, it also may provide a possible opportunity to track the transport of landslide sediment. The associated uncertainties are large, but in the Wenchuan case, calculations based on 10Be mixing proportions suggest that river sediment fluxes in the 2–3 years following the earthquake increased by a similar order of magnitude in the 0.25–1 mm and the <0.25 mm size fractions, as determined from 10Beqtz mixing calculations and hydrological gauging, respectively. Such information could provide new insight into sediment transfer, with implications for secondary sediment-related hazards and for understanding the removal of mass from mountains.

Hydro-chemical evolution of groundwater and mixing between aquifers: a statistical approach based on major ions

Geochemical analysis is a useful tool in hydrogeological assessment, particularly in constructing a conceptual model of a hydrogeological system. In this study, major ion concentrations of 53 groundwater samples from the coal-bearing aquifer in the Qidong coal mine, northern Anhui Province of China have been processed by statistical analysis for understanding either hydro-chemical characteristics or hydrological evolution, which will be useful for the safety of coal mining. The results suggest that most of the samples are Na–SO4 and Na–HCO3 types, and their hydro-chemical compositions are mainly controlled by dissolution of more soluble minerals (e.g. calcite) and weathering of silicate minerals (e.g. plagioclase). Two groups of samples have been subdivided by quantile and scatter plots of factor scores, one is related to different degrees of water–rock interactions and another is related to groundwater mixing. Moreover, four end members have been identified and the mixing calculation suggests that the groundwater samples affected by mixing have 20–100 % contribution from the loose layer aquifer (LA), and therefore, groundwater from the LA in the coal mine should be taken seriously during coal mining. The study demonstrated that statistical analysis is useful for connecting the hydrochemistry of groundwater with hydrological evolution of the aquifer.

Application of water chemistry as a hydrological tracer in a volcano catchment area: A case study of the Tatun Volcano Group, North Taiwan

In this paper, water chemistry is successfully applied to elucidate hydrological processes through the use of natural tracers in a hydrological system. The concept of a natural tracer is principally based on water–rock interaction. In this case, a volcanic watershed in the Tatun Volcano Group is examined with the hydrochemistry of the Peihuang Creek system analyzed in terms of acidic hydrothermal water. The application of principal component analysis demonstrates that the hydrochemistry of Peihuang Creek is dominated by mixing among three end members, Lujiaoken seep water, Matsao seep water and shallow circulated water. Conservative ions, such as halogens, reveal that recharge of shallow circulated water with low ionic concentration is dominant in the mountain area and gradually becomes insignificant in the plains area. Rare earth elements also confirm this derivation. In addition, rare earth elements demonstrate parallel pattern along the tributaries, which implies that the fractionation of rare earth elements is not considerable and dilution is the major factor attenuating the concentrations of rare earth elements. Therefore, the constant slope of REE pattern allows for semi-quantitative estimation of mixing proportion of the two major tributaries. The results show that Lujiaoken Creek supplies about 50% of waters to the downstream Peihuang Creek. Comparing commonly used nature tracers, such as Cl− and environmental isotopes, this study demonstrates that rare earth elements have the advantage of very low background concentrations and easily defined sources if fractionation is not considerable. Under this circumstance, the calculation of water mixing is applicable.

Does 'you are what you eat' apply to mangrove grapsid crabs?

In tropical mangroves, brachyuran crabs have been observed to consume high percentages of leaf litter production. However, questions concerning their ability to assimilate this low-quality food remain, as stable isotope analysis of C and N does not seem to support assimilation. Individuals of the common eastern Australian mangrove grapsid Parasesarma erythodactyla feeding on a mangrove leaf litter or mangrove+microphytobenthos diet developed a significantly higher hepatosomatic index than those with access to only sediment. Lipid biomarker analysis and feeding experiments using 13C and 15N-enriched mangrove leaf litter confirmed rapid assimilation of mangrove C and N by P. erythodactyla. Eight-week feeding experiments utilizing three food types (mangrove leaf litter, microphytobenthos and prawn muscle) established different food-specific trophic discrimination values (Δδ13C and Δδ15N) that are significantly different from those commonly applied to mixing model calculations. The mean Δδ13C(crab-mangrove) of +5.45‰ was close to the mean and median literature values for grapsid-mangrove pairs in 29 past studies (+5.2±1.8‰ and +5.6‰, respectively), suggesting that this large discrimination may generally be characteristic of detritivorous grapsid crabs. Solutions from the IsoConc mixing model using our determined trophic discrimination values suggest significantly higher and dominant contributions of mangrove C to the diet than those based on the global mean trophic discrimination values. Our results reaffirm the physiological capacity for and important mediating role of grapsid crabs in processing low-quality mangrove C in tropical estuaries, and caution against the use of global trophic discrimination values in stable isotope analysis of food-web data, especially those involving detritivores. While recent studies have questioned the trophic significance of mangrove detritus in coastal food chains, the contribution of this productive carbon source needs to be re-assessed in the light of these data.

Geochemical Characteristics and Genetic Types of Natural Gas from Tazhong Area in the Tarim Basin, NW China

Plentiful natural gas has been discovered in Tazhong area in the Tarim Basin, and is mainly reservoired in Ordovician at the northern slope and in Carboniferous at the central fault horst. The analyses on natural gas components and carbon and hydrogen isotopes indicate that the natural gas in Tazhong area is mainly composed by alkanes with methane contents generally over 60%. The dryness indexes and N2 and CO2 contents are regionally different with low contents of H2S. The δ13C1 and δD1 values of alkane gas from the western part of northern slope are generally lower than −45‰ and −160‰ respectively, whereas those from the central and eastern parts are mainly higher than −45‰ and −160‰ respectively, and those from the central fault horst are mainly centralized in the ranges of −46.3‰∼−42.3‰ and −163‰∼−154‰ respectively. The alkanes display positive carbon and hydrogen isotopic series, and a few gas samples are partially reversed. The geochemical characteristics indicated that the alkane gas in Tazhong area was oil-associated and derived from the sapropelic organic matters. Natural gas from the western part of the northern slope was mainly generated in the early stage of oil cracking and was mixed by kerogen-cracking gas, and that from the central fault horst was mainly the products of oil cracking to a higher extent, whereas the gas from the central and eastern parts of the northern slope was mainly derived from the primary cracking of kerogen. The mixing analog calculation indicated that the high δ13CCO2 values was caused by the mixing of inorganic CO2 which had been generated in the dissolution reaction of reservoir carbonate rocks under acidic conditions.

Presolar graphite from the Murchison meteorite: An isotopic study

We studied presolar graphite grains from four density fractions, KE3 (1.65–1.72g/cm3), KFA1 (2.05–2.10g/cm3), KFB1 (2.10–2.15g/cm3), and KFC1 (2.15–2.20g/cm3), extracted from the Murchison (CM2) meteorite, with the ion microprobe. One of the most interesting features of presolar graphite is that isotopic features depend on density. There are grains with 15N and 18O excesses, Si isotopic anomalies, high 26Al/27Al ratios (∼0.1), and Ca and Ti isotopic anomalies, including the initial presence of short-lived 41Ca and 44Ti. These isotopic features are qualitatively explained by nucleosynthesis in core collapse supernovae. We estimate that 76%, 50%, 7% and 1% of the KE3, KFA1, KFB1 and KFC1 grains, respectively, are supernova grains. We performed 3- and 4-zone supernova mixing calculations to reproduce the C, O (18O/16O) and Al isotopic ratios of the KE3 grains, using 15M⊙ model calculations by Rauscher et al. (2002). Isotopic ratios of grains with high 12C/13C ratios (>200) can be reproduced, whereas those of grains with ratios ⩽200 are hard to explain if we assume that graphite grains form in C-rich conditions.We compared the distributions of the 12C/13C ratios of KFB1 and KFC1 grains and their s-process 86Kr/82Kr ratios inferred from bulk noble gas analysis to model calculations of asymptotic giant branch (AGB) stars with a range of mass and metallicity. We conclude that KFB1 grains with 12C/13C⩾100 formed in the outflow of low-mass (1.5, 2 and 3M⊙) low-metallicity (Z=3×10−3 for 1.5, 2 and 3M⊙, Z=6×10−3 for 3M⊙ only) AGB stars and that KFC1 grains with 12C/13C⩾60 formed in those stars as well as in 5M⊙ stars of solar and/or half-solar metallicities. Grains with 12C/13C<20 in all the fractions seem to have multiple origins. Some of them formed in the ejecta of core-collapse supernovae. J stars and born-again AGB stars are also possible stellar sources.We calculated the abundances of graphite grains from supernovae and AGB stars in the Murchison meteorite to be 0.24ppm and 0.44ppm, respectively, whereas those of SiC grains from supernovae and AGB stars are 0.063ppm and 5.6ppm, respectively. In contrast to graphite, AGB stars are a dominant source of SiC grains.Since different mineral types have different residence times in the interstellar medium, their abundances in meteorites may not reflect original yields in stellar sources. Even if graphite grains are more easily destroyed than SiC grains, graphite grains from supernovae are more abundant than SiC grains from supernovae (0.24ppm vs. 0.063ppm), indicating that supernovae are a prolific producer of graphite grains. Graphite grains from AGB stars are less abundant than SiC grains from AGB stars (0.44ppm vs. 5.6ppm). This difference may reflect the difference in their parent stars: graphite grains formed in low-metallicity stars, while SiC grains formed in close-to-solar metallicity stars.

Prediction of excess molar volumes of selected binary mixtures from refractive index data

The excess molar volumes of twenty two binary mixtures containing various groups of organic compounds: alcohols (ethanol, 1-propanol, 1,2-propanediol, 1,3-propanediol and glycerol), ketone (acetone), ester (butyl lactate), lactam (N-methyl-2-pyrrolidone), PEGs (PEG 200, PEG 400) and aromatics (benzene, toluene and pyridine) were predicted from the refractive index data, using three types of equations coupled with several mixing rules for refractive index calculations: the Lorentz-Lorenz, Dale-Gladstone, Eykman, Arago-Biot, Newton, and Oster. The obtained results were analysed in terms of the applied equation and mixing rule and the nature of interactions between the mixtures? components.

Signature Splitting in 7/2 [633]vband of175Hf

In this paper, we present an explanation of signature splitting observed in the one quasiparticle rotational band (7/2[633]ν) of 175Hf in terms of one particle plus rotor model (PRM) calculations. The role of angular momentum dependence of the inertia parameter and rotational correction term appearing in Coriolis mixing calculations to explain signature effects is discussed.

Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements in Hg 184, 186 and two-state mixing calculations

Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements in Hg 184, 186 and two-state mixing calculations

Mixed mode crack growth simulation with/without overloads

In the present paper, mathematical models/procedures are developed in order to investigate the mixed mode crack growth process. The proposed procedures examine the fatigue life estimation and the crack path simulation under either constant amplitude loading or single overload. The fatigue life up to failure is calculated by employing two-parameter driving force model together with the equivalent stress intensity factor. The overload effect is theoretically analyzed by introducing the Wheeler’s retardation parameter. Further, the crack extension under Mode I/II conditions is experimentally investigated for two cracks emanating from two holes in the plate. Then, for the same mixed mode situation with two cracks, the crack growth paths are modeled by using the maximum principal stress criterion and the finite element method. The authors employ analytical and numerical approaches for the stress intensity factor calculations. The numerical investigation is performed by applying quarter-point (Q-P) singular finite elements. The efficiency of proposed procedures is verified through available crack growth data. The different mixed mode calculations are in a good correlation with crack growth observations.

Research of Rolling Bearing Selection Based on Hybrid Algorithm

According to selection of bearings for the impact of multiple factors and ambiguity, a mixed calculation method of variety of algorithms was presented. Problem was better solved to quantitative of the multiple factors. The unique results of the Selection were ensured. Through MFC, Pro/Toolkit of Pro/E interface was called to generate three-dimensional graphics of bearing automatically in VC++ platform. The three-dimensional graphics of bearing could be used directly in the assembly model of product.

The abundance, distribution, and isotopic composition of Hydrogen in the Moon as revealed by basaltic lunar samples: Implications for the volatile inventory of the Moon

In this study we have measured the OH contents and D/H ratios in apatite grains in lunar basalts. These new data considerably expand the limited dataset published so far. The data presented in this study also show that there is a major difference between high- and low-Ti mare basalts in terms of their OH and D/H systematics. Apatites in high-Ti basaltic samples display a relatively restricted range in OH contents (∼1500–3000ppm) with large δD variations (∼600–1000 ‰) whereas apatites in low-Ti Apollo basalts and lunar meteorites display a comparatively larger range in OH contents (∼500–15000ppm), each sample displaying relatively restricted variations in their D/H ratios. Analyses of apatites in basaltic meteorites Miller Range 05035 and LaPaz Icefield 04841 substantially expand the lower bound for δD values measured in apatites from Apollo mare basalts, down to δD values of ∼100‰. In these meteorites, high resolution mapping of the distribution of secondary ions of H and C was used to avoid cracks and hotspots. Together with mixing calculations for terrestrial contamination, this analytical protocol ensured that most of the values reported for MIL 05035 and LAP 04841 correspond to their actual lunar signatures. We interpret the large variations of apatite δD values in mare basalts between ∼200‰ and 1000‰ as a result of different amounts of degassing of H-bearing species initially dissolved in the basaltic parental melts. Indeed, the average δD values measured in different low-Ti basalts are consistent with ∼85–99% degassing of H as H2, starting from a δD value of 100‰. Degassing of H-bearing species essentially as H2 was favoured by the reduced nature of lunar magmas. In low-Ti mare basalts, apatite crystallisation occurred after degassing of the H-bearing species and the OH variations reflect different degrees of fractional crystallisation. In high-Ti mare basalts, large δD variations with relatively restricted range in OH contents imply that apatite crystallisation and degassing of H-bearing species were mostly coeval. Geochemical modelling integrating corrections for degassing and fractional crystallisation suggests that the mantle source regions of the different low-Ti mare basalts could have contained ∼5–50ppm H (equivalent to ∼45–450ppm H2O), which are similar to the estimated range of ∼60–350ppm water for the Earth’s upper mantle. Finally, the H isotopic composition of pre-degassed lunar hydrogen in mare basalts is consistent with a CI-chondrite-type value of ∼100‰, which is consistent with the increasing evidence suggesting that the Earth, Mars and the Moon might have accreted similar water of chondritic origin.

Application of Novel and Advanced Fuel Characterization Tools for the Combustion Related Characterization of Different Wood/Kaolin and Straw/Kaolin Mixtures

The increased demand for energy from biomass enforces the utilization of new biomass fuels (e.g., energy crops, short-rotation coppices, as well as wastes and residues from agriculture and the food industry). Compared to conventional wood fuels, these new biomass fuels usually show considerably higher ash contents and lower ash sintering temperatures, which leads to increased problems concerning slagging, ash deposit formation, and particulate matter emissions. One possibility to combat these problematic behaviors is the application of fuel additives such as kaolin. In contrast to the usual approach for the application of additives based on an experimental determination of an appropriate additive ratio, this study applies novel and advanced fuel characterization tools for the characterization of biomass/kaolin mixtures. In the first step the pure biomass fuels (softwood from spruce and straw) and the additive were chemically analyzed. On the basis of the analysis theoretical mixing calculations of promisi...

Design of Highway Construction Mixing Materials Ratio Based on Genetic Algorithm

The manual work or Excel based material mixing ratio method has low computer application level and lays high computer capacity on design construction workers. It is difficult to obtain the most optimal technical and economic program from a number of optional programs. The paper built mathematical model of materials mixing ratio based on genetic and identified constraint conditions. Data pre-processing was performed according to the constructed model. According to specific circus of material mixing ratio calculation, the fitness function and various operators were designed and parameters of model were also configured. At the same time of meeting requirements of project quality, multiple target optimizations were considered to give new model and constraints. The highway construction mixing materials ratio calculation based on genetic algorithm achieves expected goal and improve accuracy and efficiency of operations.

GPU-accelerated Gibbs ensemble Monte Carlo simulations of Lennard-Jonesium

This work describes an implementation of canonical and Gibbs ensemble Monte Carlo simulations on graphics processing units (GPUs). The pair-wise energy calculations, which consume the majority of the computational effort, are parallelized using the energetic decomposition algorithm. While energetic decomposition is relatively inefficient for traditional CPU-bound codes, the algorithm is ideally suited to the architecture of the GPU. The performance of the CPU and GPU codes are assessed for a variety of CPU and GPU combinations for systems containing between 512 and 131,072 particles. For a system of 131,072 particles, the GPU-enabled canonical and Gibbs ensemble codes were 10.3 and 29.1 times faster (GTX 480 GPU vs. i5-2500K CPU), respectively, than an optimized serial CPU-bound code. Due to overhead from memory transfers from system RAM to the GPU, the CPU code was slightly faster than the GPU code for simulations containing less than 600 particles. The critical temperature Tc∗=1.312(2) and density ρc∗=0.316(3) were determined for the tail corrected Lennard-Jones potential from simulations of 10,000 particle systems, and found to be in exact agreement with prior mixed field finite-size scaling calculations [J.J. Potoff, A.Z. Panagiotopoulos, J. Chem. Phys. 109 (1998) 10914].

Quantum transport with two interacting conduction channels

The transport properties of a conduction junction model characterized by two mutually coupled channels that strongly differ in their couplings to the leads are investigated. Models of this type describe molecular redox junctions (where a level that is weakly coupled to the leads controls the molecular charge, while a strongly coupled one dominates the molecular conduction), and electron counting devices in which the current in a point contact is sensitive to the charging state of a nearby quantum dot. Here we consider the case where transport in the strongly coupled channel has to be described quantum mechanically (covering the full range between sequential tunneling and co-tunneling), while conduction through the weakly coupled channel is a sequential process that could by itself be described by a simple master equation. We compare the result of a full quantum calculation based on the pseudoparticle non-equilibrium Green function method to that obtained from an approximate mixed quantum-classical calculation, where correlations between the channels are taken into account through either the averaged rates or the averaged energy. We find, for the steady state current, that the approximation based on the averaged rates works well in most of the voltage regime, with marked deviations from the full quantum results only at the threshold for charging the weekly coupled level. These deviations are important for accurate description of the negative differential conduction behavior that often characterizes redox molecular junctions in the neighborhood of this threshold.

Advanced Combustor Concepts for Low Emissions Supersonic Propulsion

Novel lean-burn combustor concepts were designed and evaluated for supersonic aircraft propulsion, with a focus on cruise NOx emissions. Premixing to lean conditions is especially challenging at supersonic cruise because combustor inlet temperatures are high and autoignition times are short. However, combustor pressure is significantly lower than at takeoff, so at cruise this allows heated jet fuel to be vaporized before injection as an aid to mixing. Two concepts—differentiated by swirler aerodynamics, swirler size, and staging method—were evaluated in the work reported here, both using injection of vaporized jet fuel. Computational fluid dynamics (CFD) calculations of mixing and combustion were used to design hardware for each concept. Injectors for each were fabricated using stereolithography (SLA) for cold-flow mixing tests, and using metal fabrication for subsequent combustion tests. Combustion test results show that emissions index for NOx (EINOx) &lt; 5 was achieved for both concepts in single-sector tests at supersonic cruise combustor conditions.