Partitioning Scenarios Research Articles

On the Steady State Correlation Functions of Open Interacting Systems

We address the existence of steady state Green-Keldysh correlation functions of interacting fermions in mesoscopic systems for both the partitioning and partition-free scenarios. Under some spectral assumptions on the non-interacting model and for sufficiently small interaction strength, we show that the system evolves to a NESS which does not depend on the profile of the time-dependent coupling strength/bias. For the partitioned setting we also show that the steady state is independent of the initial state of the inner sample. Closed formulae for the NESS two-point correlation functions (Green-Keldysh functions), in the form of a convergent expansion, are derived. In the partitioning approach, we show that the 0th order term in the interaction strength of the charge current leads to the Landauer-Buettiker formula, while the 1st order correction contains the mean-field (Hartree-Fock) results.

Improved wavefield reconstruction from randomized sampling via weighted one-norm minimization

Missing-trace interpolation aims to recover the gaps caused by physical obstacles or deliberate subsampling to control acquisition costs in otherwise regularly sampled seismic wavefields. Although transform-domain sparsity promotion has proven to be an effective tool to solve this recovery problem, current recovery techniques do not fully utilize a priori information derived from the locations of the transform-domain coefficients, especially when curvelet domain sparsity is exploited. We use recovery by weighted one-norm minimization, which exploits correlations between the locations of significant curvelet coefficients of different partitions, e.g., shot records, common-offset gathers, or frequency slices of the acquired data. We use these correlations to define a sequence of 2D curvelet-based recovery problems that exploit 3D continuity exhibited by seismic wavefields without relying on the highly redundant 3D curvelet transform. To test the performance of our weighted algorithm, we compared recoveries from different data sorting and partitioning scenarios for a seismic line from the Gulf of Suez. These tests demonstrated that our method is superior to standard [Formula: see text] minimization in terms of antialiasing capability, reconstruction quality and computational memory requirements.

Authigenic iron oxide proxies for marine zinc over geological time and implications for eukaryotic metallome evolution

Here, we explore enrichments in paleomarine Zn as recorded by authigenic iron oxides including Precambrian iron formations, ironstones, and Phanerozoic hydrothermal exhalites. This compilation of new and literature-based iron formation analyses track dissolved Zn abundances and constrain the magnitude of the marine reservoir over geological time. Overall, the iron formation record is characterized by a fairly static range in Zn/Fe ratios throughout the Precambrian, consistent with the shale record (Scott et al., 2013, Nature Geoscience, 6, 125-128). When hypothetical partitioning scenarios are applied to this record, paleomarine Zn concentrations within about an order of magnitude of modern are indicated. We couple this examination with new chemical speciation models to interpret the iron formation record. We present two scenarios: first, under all but the most sulfidic conditions and with Zn-binding organic ligand concentrations similar to modern oceans, the amount of bioavailable Zn remained relatively unchanged through time. Late proliferation of Zn in eukaryotic metallomes has previously been linked to marine Zn biolimitation, but under this scenario the expansion in eukaryotic Zn metallomes may be better linked to biologically intrinsic evolutionary factors. In this case, zinc's geochemical and biological evolution may be decoupled and viewed as a function of increasing need for genome regulation and diversification of Zn-binding transcription factors. In the second scenario, we consider Archean organic ligand complexation in such excess that it may render Zn bioavailability low. However, this is dependent on Zn-organic ligand complexes not being bioavailable, which remains unclear. In this case, although bioavailability may be low, sphalerite precipitation is prevented, thereby maintaining a constant Zn inventory throughout both ferruginous and euxinic conditions. These results provide new perspectives and constraints on potential couplings between the trajectory of biological and marine geochemical coevolution.

Hiding co-occurring prioritized sensitive patterns over distributed progressive sequential data streams

Recently, privacy preservation in data mining is an important area of research. It can be done in several ways. Hiding of sensitive patterns is one such important method. In a typical scenario, multiple parties may wish to collaborate to extract interesting global patterns from their integrated data items without revealing their respective local data to each other. Typical applications include finance, medical research, retail sales etc. In certain cases, there may be some patterns whose co-occurrence may lead to revelation of sensitive information. In the present work, hiding of co-occurring sensitive patterns dynamically from distributed progressive databases has been proposed. In addition in the proposed work dynamic priorities have also been coupled, along with the items. This helps to decide which patterns to hide from the set of sensitive patterns. The various partitioning scenarios for distributed databases that have been used include horizontal, vertical and arbitrary. In all such cases, the data is distributive progressive in nature i.e., old data items may become obsolete whereas new data items may be treated as more significant.

Nonequilibrium steady states for interacting open systems: Exact results

Under certain conditions we prove the existence of a steady-state transport regime for interacting mesoscopic systems coupled to reservoirs (leads). The partitioning and partition-free scenarios are treated on an equal footing. Our time-dependent scattering approach is {\it exact} and proves, among other things the independence of the steady-state quantities from the initial state of the sample. Closed formulas for the steady-state current amenable for perturbative calculations w.r.t. the interaction strength are also derived. In the partitioning case we calculate the first order correction and recover the mean-field (Hartree-Fock) results.

Model to Describe the Binodal Curve on a Type 1 Ternary Phase Diagram

A regression curve based on a Weibull distribution model is generated to describe the binodal curve on a three component liquid-liquid ternary phase diagram. The methodology involves transforming the experimental phase partitioning data points of each mixture from the ternary phase diagram to equivalent Cartesian coordinates. The regression curve is then generated, and the regression curve becomes the Weibull-derived binodal curve by superimposing the regression curve onto the original ternary phase diagram. A total of seven regression curves for seven ternary mixtures are generated in this study. From the regression analysis, the resulting R2 value for each mixture is very close to one, indicating that there is strong correlation between the regression curve and the transformed experimental data points. The method developed in this research allows researchers to empirically describe a binodal curve, which is useful in analyzing and predicting the various phase partitioning scenarios of a three-component ...

Modelling climate change effects on the spatial distribution of mountain permafrost at three sites in northwest Canada

Spatial models of present-day mountain permafrost probability were perturbed to examine potential climate change impacts. Mean annual air temperature (MAAT) changes were simulated by adjusting elevation in the models, and cloud cover changes were examined by altering the partitioning of direct beam and diffuse radiation within the calculation for potential incoming solar radiation (PISR). The effects of changes in MAAT on equilibrium permafrost distribution proved to be more important than those due to cloud cover. Under a −2 K scenario (approximating Little Ice Age conditions), permafrost expanded into an additional 22–43% of the study areas as zonal boundaries descended by 155–290 m K − 1. Under warming scenarios, permafrost probabilities progressively declined and zonal boundaries rose in elevation. A MAAT change of +5 K, caused two of the areas to become essentially permafrost-free. The absolute values of these predictions were affected up to ±10% when lapse rates were altered by ±1.5 K km − 1 but patterns and trends were maintained. A higher proportion of diffuse radiation (greater cloud cover) produced increases in permafrost extent of only 2–4% while decreases in the diffuse radiation fraction had an equal but opposite effect. Notwithstanding the small change in overall extent, permafrost probabilities on steep south-facing slopes were significantly impacted by the altered partitioning. Combined temperature and PISR partitioning scenarios produced essentially additive results, but the impact of changes in the latter declined as MAAT increased. The modelling illustrated that mountain permafrost in the discontinuous zone is sensitive spatially to long-term climate change and identified those areas where changes may already be underway following recent atmospheric warming.

Thermodynamic consistency of Raoult’s Law and Henry’s Law approaches for multiphase organic aerosol partitioning

Partitioning of semivolatile organic compounds between gas, organic aerosol, and aqueous aerosol phases has been described in atmospheric models using Raoult’s Law and/or Henry’s Law, with activity coefficients accounting for nonideal behavior in the aerosol solutions. Raoult’s Law and Henry’s Law are thermodynamically consistent with each other as long as the parameters defining their different reference states are accurately known. Unfortunately, saturation vapor pressures, Henry’s law constants, and activity coefficients for organic aerosol compounds must typically be estimated. As a result, thermodynamic inconsistencies can arise when using Raoult’s and Henry’s Law approaches together due to errors in estimation methods. A test of predicted partitioning parameters for representative semivolatile organics suggests overall errors of at least an order of magnitude. Box model simulations with a simplified partitioning scenario demonstrate that these estimation errors can significantly alter partitioning for many compounds and, more importantly, that thermodynamic inconsistencies will lead to even greater errors than those due solely to uncertain parameters. To avoid these errors, a common reference state should be used to define equilibrium among all phases, improved estimation methods and measurements should continue to be pursued, and alternative reference states that better represent typical organic aerosol mixtures should be explored.

Chaining set partitions with applications in manufacturing system configuration planning

Knowing the number of candidate configurations is the first and critical step in manufacturing system configuration planning because it determines the methods for subsequent optimisation tasks. However, counting the total number of candidate configurations is a challenging partitioning problem due to the multiple sets of work elements that are often chained by the overlapping elements between adjacent sets. Starting with simple partitioning scenarios, this paper presents a new mathematical treatment and derives the formulas for calculating the number of candidate system configurations, which can eventually lead to algorithms for system configuration selection, simulation and optimisation.

Global fate and distribution of polycyclic aromatic hydrocarbons emitted from Europe and Russia

The long-range atmospheric transport (LRT) of polycyclic aromatic hydrocarbons (PAHs) is not fully understood and has hardly been addressed by model studies. By model experiments the LRT of PAH emissions into air from Europe and Russia is studied testing several scenarios of gas–particle partitioning and degradability by reaction with ozone and the hydroxyl and nitrate radicals for two PAHs, benzo[a]pyrene (BAP) and fluoranthene (FLT). The model used is the atmosphere general circulation model ECHAM5 with a dynamic modal aerosol sub-model, HAM, ozone and sulfur species chemistry and bidirectional mass exchange on 2D marine (ocean surface mixed layer) and terrestrial surfaces (top soil layer and vegetation surfaces). After 5 years the substances are found to be mostly distributed to the soil compartment (64–97% as the global mean, varying with substance and season), which after 10 years is still filling; 1–5% are found in air and 2–33% in ocean. It is found that the lifetime and vertical distribution of the substances in the atmosphere and the LRT potential are all significantly influenced by the partitioning and degradation scenario. The total environmental burden is higher when sorption to organic matter and black carbon are considered to determine gas–particle partitioning rather than adsorption to the surface of particulate matter. The effect is + 20 % for BAP but sevenfold for FLT. Concentrations in Arctic air are mostly underestimated by the model, which is partly explained by emissions not considered in the simulation. The comparison shows, however, that degradation of the sorbed BAP and FLT molecules should be significantly slower than the respective gaseous molecules and that absorptive partitioning is necessary to explain the LRT potential of FLT.

Plio‐Quaternary exhumation history of the central Nepalese Himalaya: 2. Thermokinematic and thermochronometer age prediction model

In the Himalaya and other active convergent orogens, linear relationships between thermochronometer sample age and elevation are often used to estimate long‐term exhumation rates. In these regions, high‐relief topography and nonvertical exhumation pathways may invalidate such one‐dimensional (1‐D) interpretations and lead to significant errors. To quantify these errors, we integrate apatite fission track (AFT) ages from the central Himalaya with a 3‐D coupled thermokinematic model, from which sample cooling ages are predicted using a cooling‐rate‐dependent algorithm. By changing the slip partitioning between faults near the Main Central thrust and the Main Frontal thrust system at the Himalayan range front, we are able to explore the significance of different tectonic scenarios on predicted thermochronometer ages. We find that the predicted AFT cooling ages are not sensitive to the different slip partitioning scenarios but depend strongly on erosion rate: Predicted ages are most consistent with kinematic models that produce erosion rates of 1.8–5.0 mm/yr. This range is considerably smaller than that derived from regression lines through the data (−2.6–12.2 mm/yr). The pattern of observed AFT ages shows more complexity than our models predict. None of the kinematic scenarios are able to fit >80% of all of the AFT data, most likely because erosion is spatially variable. Such complexities notwithstanding, we conclude that the use of thermokinematic modeling and thermochronologic data sets to explore detailed fault kinematics in rapidly eroding active orogens has great promise but requires integration of higher‐temperature (>∼350°C) data sets to maximize effectiveness.

Multiphase BIST: A New Reseeding Technique for High Test-Data Compression

In this paper, a new reseeding architecture for scan-based built-in self-test (BIST), which uses a linear feedback shift register (LFSR) as test pattern generator, is proposed. Multiple cells of the LFSR are utilized as sources for feeding the scan chain of the circuit under test in different test phases. The LFSR generates the same state sequence in all phases, keeping that way the implementation cost low. A seed-selection algorithm is furthermore presented that, taking advantage of the multiphase architecture, manages to significantly reduce the number of the required seeds for achieving complete (100%) fault coverage. The proposed technique can be used either in a full BIST implementation or in a test-resource partitioning scenario, since the test-data storage requirements on the tester are very low. When a full BIST implementation is preferable, the multiphase architecture can also be combined with a dynamic reseeding scheme that uses combinational logic instead of a ROM in order to perform the reseedings. This way the implementation area of the BIST circuitry is further reduced. Experimental results demonstrate the advantages of the proposed LFSR reseeding approach over the already known reseeding techniques.

Impact limits of partitioning and transmutation scenarios on the radiotoxicity of actinides in radioactive waste

The used fuel discharged from nuclear power plants constitutes the main contribution to nuclear waste in countries which do not undertake reprocessing. As such, its disposal requires isolation from the biosphere in stable deep geological formations for long periods of time (some hundred thousand years) until its radioactivity decreases through the process of radioactive decay. Ways for significantly reducing the volumes and radiotoxicities of the waste and to shorten the very long times for which the waste must be stored safely are being investigated. This is the motivation behind the partitioning and transmutation (P&T) activities worldwide. This paper addresses the potential impact of P&T on the long-term disposal of nuclaer waste. In particular, it evaluates how realistic P&T scenarios can lead to a reduction in the time required for the waste to be stored safely. The calculations have been done independently by three research groups: ITU and FZK in Germany, and by the CEA in France.

Modular simulation software for modelling the impacts of alternative spent fuel management practices in the nuclear power industry

The authors describe the development of a modular software suite for application in the nuclear power industry. The approach incorporates nuclear data and fuel cycle architecture into a flexible and dynamic modelling environment. The software suite comprising MEEMS (mass, environment, economical modelling and simulation) and MPR (MEEMS pseudo reactor) was developed specifically to enable investigation of novel fuel cycle operations, such as partitioning and transmutation scenarios. The system has been used to model various nuclear fuel cycle scenarios and preliminary results indicate that the approach is a viable method with good prospects for industrial application.

Nitrogen Shortage in a Tomato Crop; Scaling up from Effects on Electron-Transport Rate to Plant Productivity

Optimization of nitrogen supply in a tomato plant is stepwise assessed, from chloroplast characteristics to whole crop performance. Experiments are reported in which important key processes are quantified in relation to the nitrogen content of leaves. Interactions of N effects with leaf aging and canopy light distribution are analyzed. A simulation model that integrates this knowledge is constructed. The results of three nitrogen partitioning scenarios for Rubisco suggest that optimization of the distribution of Rubisco between leaf layers is less important for plant productivity than within-leaf optimization of the photosynthetic apparatus

Dispersion modelling of dioxin releases from the waste incinerator at Avonmouth, Bristol, UK

A modified Gaussian atmospheric dispersion model, Industrial Source Complex (ISCST3), is used to estimate toxic equivalent ground level concentrations (GLC) of dioxins emitted from the Avonmouth municipal waste incinerator (MWI) in Bristol, UK. The sensitivity of the predicted GLC to various vapour and particle partitioning scenarios is reported. Predictions incorporating local terrain and actual emission data are used to estimate the mean incremental intake of dioxin due to MWI operation for local residents, through an existing multi-pathway human exposure model. Results are compared with predictions of incremental intake for a generalised MWI. The mean incremental dioxin intake for a hypothetical maximum exposed individual (HMEI) is shown to be up to 46.5% of the background intake compared to only 1.14% for the generalised MWI scenario. This indicates that the use of local terrain and emission data in MWI dispersion modelling is crucial for health risk assessments associated with human dioxin intake, especially in view of the current debate over the tolerable daily intake for dioxins.