Viscous flow around three-dimensional macroscopic cavities in a granular material

Viscous flow around spherical macroscopic cavities in a granular material is investigated. The Stokes equation inside and the Darcy–Brinkman equation outside the cavities are considered. In particular, the interaction of two equally sized cavities positioned in tandem is examined in detail, where the asymptotic effect of the other cavity is taken into account. The present analysis gives a reasonable estimate on the volume flow into the cavity and the local enhancement of stresses. This is applicable to predict the microscale waterway formation in that material, onset of landslides, collapse of cliffs and river banks, etc.

Analyticity and Regge asymptotics in virtual Compton scattering on the nucleon

We test the consistency of the data on the nucleon structure functions with analyticity and the Regge asymptotics of the virtual Compton amplitude. By solving a functional extremal problem, we derive an optimal lower bound on the maximum difference between the exact amplitude and the dominant Reggeon contribution for energies $$\nu $$ ν above a certain high value $$\nu _h(Q^2)$$ ν h ( Q 2 ) . Considering in particular the difference of the amplitudes $$T_1^\text {inel}(\nu , Q^2)$$ T 1 inel ( ν , Q 2 ) for the proton and neutron, we find that the lower bound decreases in an impressive way when $$\nu _h(Q^2)$$ ν h ( Q 2 ) is increased, and represents a very small fraction of the magnitude of the dominant Reggeon. While the method cannot rule out the hypothesis of a fixed Regge pole, the results indicate that the data on the structure function are consistent with an asymptotic behaviour given by leading Reggeon contributions. We also show that the minimum of the lower bound as a function of the subtraction constant $$S_1^\text {inel}(Q^2)$$ S 1 inel ( Q 2 ) provides a reasonable estimate of this quantity, in a frame similar, but not identical to the Reggeon dominance hypothesis.

Correlated Evolution in the Small Parsimony Framework

When studying the evolutionary relationship between a set of species, the principle of parsimony states that a relationship involving the fewest number of evolutionary events is likely the correct one. Due to its simplicity, this principle was formalized in the context of computational evolutionary biology decades ago by, e.g., Fitch and Sankoff. Because the parsimony framework does not require a model of evolution, unlike maximum likelihood or Bayesian approaches, it is often a good starting point when no reasonable estimate of such a model is available.In this work, we devise a method for detecting correlated evolution among pairs of discrete characters, given a set of species on these characters, and an evolutionary tree. The first step of this method is to use Sankoff’s algorithm to compute all most parsimonious assignments of ancestral states (of each character) to the internal nodes of the phylogeny. Correlation between a pair of evolutionary events (e.g., absent to present) for a pair of characters is then determined by their (co-) occurrence patterns among their respective ancestral assignments. We implement this method: parcours (PARsimonious CO-occURrenceS) and use it to study the correlated evolution among vocalizations in the Felidae family, revealing some interesting results.The parcours tool is freely available at https://github.com/murraypatterson/parcours

Understanding the Aerodynamic Benefits of Drafting in the Wake of Cyclists

A new approach is presented to characterize the aerodynamic benefit from riding in the wake of another cyclist at different downstream locations. The method presented uses the dynamic pressure deficit in the wake of a cycling mannequin to estimate percentage drag savings. In the experiments, the time-averaged velocity behind a cycling mannequin was recorded in 1 × 0.95 m cross-planes by two four-hole pressure (Cobra) probes for four static leg positions (0°, 90°, 180°, and 270°). It was found that the wake of the cycling mannequin propagated to one side or the other as it developed downstream, depending on the strength of the two large-scale counter-rotating streamwise vortical structures shed off the hips of the mannequin. In the near wake, the complex wake dynamics resulted in an inaccurate prediction of the relative drag reduction based upon a dynamic pressure deficit. However, as the wake developed and stabilised further downstream, the dynamic pressure deficit was found to provide a reasonable estimate of the aerodynamic drag reduction of riding in the wake of the lead rider.

Improving Accounting and Analysis of Innovative Costs

Based on the goal set in the beginning of the work and formulated tasks, the research is devoted to the study of theoretical and normative bases of accounting and analysis of innovative costs of the enterprise. The essence of innovation and innovation costs as an object of accounting and analysis is investigated. The actual problems of accounting of expenses on innovations are analyzed. The methodical bases of the enterprise innovative cost analysis are investigated. Investigating the current issues of accounting for innovation costs before accounting for innovation costs has identified a key direction - displaying innovation costs as a separate accounting entity. The study provides recommendations on how to improve accounting and analysis of innovation costs, namely, the authors proposed an accounting approach that provides for the preliminary creation of additional analytical sections on the expense accounts and in the accounts, which keep records of capital investment and proposed to analyze innovation costs as part of a comprehensive analysis of innovation activity of the enterprise. An algorithm for analyzing enterprise innovation has been developed, which includes five stages of analysis, a system of indicators for analysis of innovation, a statement of sources of financing of innovation-investment activity and a statement of the volume of innovation costs, which will provide a well-reasoned and reasonable estimate of costs.

Mesoscale Analysis of Homogeneous Dislocation Nucleation

We perform atomistic simulations of dislocation nucleation in two-dimensional (2D) and three-dimensional (3D) defect-free hexagonal crystals during nanoindentation with circular (2D) or spherical (3D) indenters. The incipient embryo structure in the critical eigenmode of the mesoregions is analyzed to study homogeneous dislocation nucleation. The critical eigenmode or dislocation embryo is found to be localized along a line (or plane in 3D) of atoms with a lateral extent, ξ, at some depth, Y*, below the surface. The lowest energy eigenmode for mesoregions of varying radius, rmeso, centered on the localized region of the critical eigenmode is computed. The energy of the lowest eigenmode, λmeso, decays very rapidly with increasing rmeso and λmeso ≈ 0 for rmeso≳ξ. The analysis of a mesoscale region in the material can reveal the presence of incipient instability even for rmeso≲ξ but gives reasonable estimate for the energy and spatial extent of the critical mode only for rmeso≳ξ. When the mesoregion is not centered at the localized region, we show that the mesoregion should contain a critical part of the embryo (and not only the center of embryo) to reveal instability. This scenario indicates that homogeneous dislocation nucleation is a quasilocal phenomenon. Also, the critical eigenmode for the mesoscale region reveals instability much sooner than the full system eigenmode. We use mesoscale analysis to verify the scaling laws shown previously by Garg and Maloney in 2D [2016, “Universal Scaling Laws for Homogeneous Dissociation Nucleation During Nano-Indentation,” J. Mech. Phys. Solids, 95, pp. 742–754.] for the size, ξ, and depth from the surface, Y*, of the dislocation embryo with respect to indenter radius, R, in full 3D simulations.

WHERE DID ALL THE PAGANS GO? THE NON-CHRISTIAN SARCOPHAGI OF FOURTH-CENTURY ROME

The number of Roman sarcophagi without explicit Christian iconography conventionally dated to the fourth century is not commensurate with any reasonable estimate of the number of well-to-do pagans. This article explores several possible explanations for the anomaly. One approach would be to attempt to correct the archaeological record by finding errors in the religious classification of monuments that exaggerate the Christian corpus, adding non-Christian sarcophagi that have escaped published inventories, or establishing a systematic misdating of pagan sarcophagi. Alternatively, the preserved monuments could be taken as an accurate reflection of original production, the shortfall implying some change in commemorative habits specific to non-Christians. The author concludes that neither of these theories is likely to reduce the pagan sarcophagus deficit substantially. Instead, the shortfall is ascribed mainly to differential rates of preservation. This hypothesis is consistent with certain medieval practices of reuse that suggest a higher probability of survival for antique sarcophagi bearing Christian imagery.

APARTMENT COMPOUNDS, HOUSEHOLDS, AND POPULATION IN THE ANCIENT CITY OF TEOTIHUACAN, MEXICO

We present three new analyses of existing data from past fieldwork at Teotihuacan. First, we confirm and refine the wealth-based housing typology of Millon's Teotihuacan Mapping Project (TMP). Second, we analyze the spatial configurations of excavated compounds, using network methods to identify the size and layout of individual dwellings within walled compounds. Third, we use those results to generate the first population estimate for the city based on measurements from the TMP map. We extrapolate the average sizes of dwellings from excavated compounds to the entire sample of mapped residences as depicted on the TMP map of the city. We generate a range of population estimates, of which we suggest that 100,000 persons is the most reasonable estimate for the Xolalpan-Metepec population of Teotihuacan. These analyses show that legacy data from fieldwork long past can be used to answer research questions that are relevant and important today.

Liquidated Damages

Chapter 23 considers contract provisions that liquidate—fix—damages for breach. Such provisions are reviewed with special scrutiny. The most general formulation of the special-scrutiny rule is that liquidated damages provisions are enforceable only if actual damages are difficult to estimate and the liquidated amount is a reasonable estimate of the actual loss from breach. It is sometimes incorrectly argued that the special-scrutiny rule rests on the premise that liquidated-damages provisions lend themselves to blameworthy exploitation and one-sidedness, that this premise is incorrect, and thus the special-scrutiny rule is incorrect. The true justification of the special-scrutiny rule, however,is that liquidated-damages provisions are systematically likely to reflect the limits of cognition.