Realistic Details Research Articles

View-Dependent Multiscale Fluid Simulation

Fluid flows are highly nonlinear and nonstationary, with turbulence occurring and developing at different length and time scales. In real-life observations, the multiscale flow generates different visual impacts depending on the distance to the viewer. We propose a new fluid simulation framework that adaptively allocates computational resources according to the viewer's position. First, a 3D empirical mode decomposition scheme is developed to obtain the velocity spectrum of the turbulent flow. Then, depending on the distance to the viewer, the fluid domain is divided into a sequence of nested simulation partitions. Finally, the multiscale fluid motions revealed in the velocity spectrum are distributed nonuniformly to these view-dependent partitions, and the mixed velocity fields defined on different partitions are solved separately using different grid sizes and time steps. The fluid flow is solved at different spatial-temporal resolutions, such that higher frequency motions closer to the viewer are solved at higher resolutions and vice versa. The new simulator better utilizes the computing power, producing visually plausible results with realistic fine-scale details in a more efficient way. It is particularly suitable for large scenes with the viewer inside the fluid domain. Also, as high-frequency fluid motions are distinguished from low-frequency motions in the simulation, the numerical dissipation is effectively reduced.

Interactive coupling between a tree and raindrops

ABSTRACTThis paper presents a novel approach for simulating the dynamic coupling between a tree and raindrops based on physical deformation and fluid simulation. By the approach, tree animation in the rain can be simulated in a two‐resolution way: branch motion and leaf motion. The branch is represented by the Euler–Bernoulli beam model, and the leaf petiole is represented by the three‐prism elastic model. Interaction coupling liquid motion on the hydrophilic surface with a flexible petiole is well implemented by a special design. To simplify the computation process, instead of the computation‐intensive three‐dimensional Navier–Stokes equations, shallow water equations are used to simulate the water dynamics together with the whole leaf deformation. Simulation has been also made to various phenomena incurred from the interactive coupling. These include, among others, part of impacting raindrops splashing into the air with the remaining flowing along the slant of the leaf and merging into larger ones or hanging on the blade boundary, with the leaf rebounding and vibrating after the drops fall off the leaf. A level‐of‐detail approach is exploited to accelerate rendering in views of different distances. The experimental results illustrate that the approach can be applied to efficiently generate realistic details of the interactive coupling between a tree and raindrops. Copyright © 2012 John Wiley & Sons, Ltd.

Analysis and algorithmic generation of hepatic vascular systems.

A proper geometric model of the vascular systems in the liver is crucial for modeling blood flow, the connection between the organ and the rest of the organism. In vivo imaging does not provide sufficient details, so an algorithmic concept for extending measured vascular tree data is needed such that geometrically realistic structures can be generated. We develop a quantification of similarity in terms of different geometric features. This involves topological Strahler ordering of the vascular trees, statistical testing, and averaging. Invariant features are identified in human clinical in vivo CT scans. Results of the existing “Constrained Constructive Optimization” algorithm are compared to real vascular tree data. To improve bifurcation angles in the algorithmic results, we implement a postprocessing step calibrated to the measured features. This framework is finally applied to generate realistic additional details in a patient-specific hepatic vascular tree data set.

New Technique: Sketch-based rotation editing

We present a sketch-based rotation editing system for enriching rotational motion in keyframe animations. Given a set of keyframe orientations of a rigid object, the user first edits its angular velocity trajectory by sketching curves, and then the system computes the altered rotational motion by solving a variational curve fitting problem. The solved rotational motion not only satisfies the orientation constraints at the keyframes, but also fits well the user-specified angular velocity trajectory. Our system is simple and easy to use. We demonstrate its usefulness by adding interesting and realistic rotational details to several keyframe animations.

Link Reversal Algorithms

Link reversal is a versatile algorithm design technique that has been used in numerous distributed algorithms for a variety of problems. The common thread in these algorithms is that the distributed system is viewed as a graph, with vertices representing the computing nodes and edges representing some other feature of the system (for instance, point-to-point communication channels or a conflict relationship). Each algorithm assigns a virtual direction to the edges of the graph, producing a directed version of the original graph. As the algorithm proceeds, the virtual directions of some of the links in the graph change in order to accomplish some algorithm-specific goal. The criterion for changing link directions is based on information that is local to a node (such as the node having no outgoing links) and thus this approach scales well, a feature that is desirable for distributed algorithms. This monograph presents, in a tutorial way, a representative sampling of the work on link-reversal-based distributed algorithms. The algorithms considered solve routing, leader election, mutual exclusion, distributed queueing, scheduling, and resource allocation. The algorithms can be roughly divided into two types, those that assume a more abstract graph model of the networks, and those that take into account more realistic details of the system. In particular, these more realistic details include the communication between nodes, which may be through asynchronous message passing, and possible changes in the graph, for instance, due to movement of the nodes. We have not attempted to provide a comprehensive survey of all the literature on these topics. Instead, we have focused in depth on a smaller number of fundamental papers, whose common thread is that link reversal provides a way for nodes in the system to observe their local neighborhoods, take only local actions, and yet cause global problems to be solved. We conjecture that future interesting uses of link reversal are yet to be discovered. Table of Contents: Introduction / Routing in a Graph: Correctness / Routing in a Graph: Complexity / Routing and Leader Election in a Distributed System / Mutual Exclusion in a Distributed System / Distributed Queueing / Scheduling in a Graph / Resource Allocation in a Distributed System / Conclusion

Top quark anomalous couplings at the International Linear Collider

We present a study of the experimental determination of the forward-backward asymmetry in the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}t\overline{t}$ and in the subsequent $t\ensuremath{\rightarrow}Wb$ decay, studied in the context of the International Linear Collider. This process probes the elementary couplings of the top quark to the photon, and the $Z$ and the $W$ bosons at a level of precision that is difficult to achieve at hadron colliders. Measurement of the forward-backward asymmetry requires excellent $b$ quark identification and determination of the quark charge. The study reported here is performed in the most challenging all-hadronic channel ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}b\overline{b}q\overline{q}q\overline{q}$. It includes realistic details of the experimental environment, a full Monte Carlo simulation of the detector, based on the Silicon Detector concept, and realistic event reconstruction. The forward-backward asymmetries are determined to a precision of approximately 1% for each of the two choices of beam polarization. We analyze the implications for the determination of the $t\overline{t}Z$ and $Wt\overline{b}$ couplings.

Les représentations de l’ivresse dans la peinture hollandaise du XVIIe siècle

Ever since Antiquity the Dutch have had a reputation for drinking a lot of alcohol. Their painters are famous in Europe for their representations of drunkenness since the 16th century. In a moral context, these scenes represented vice and bad behaviour and this meaning continued to be popular to the end of that century. During the following one, painters used less brutal and crude scenes, favouring more idyllic compositions.The subject of drunkenness exists not only in genre painting but also had an important role in the history painting and was distinguished from other European schools only by more realistic details.

High-resolution subtropical summer precipitation derived from dynamical downscaling of the NCEP/DOE reanalysis: how much small-scale information is added by a regional model?

This study assesses the regional-scale summer precipitation produced by the dynamical downscaling of analyzed large-scale fields. The main goal of this study is to investigate how much the regional model adds smaller scale precipitation information that the large-scale fields do not resolve. The modeling region for this study covers the southeastern United States (Florida, Georgia, Alabama, South Carolina, and North Carolina) where the summer climate is subtropical in nature, with a heavy influence of regional-scale convection. The coarse resolution (2.5deg latitude/longitude) large-scale atmospheric variables from the National Center for Environmental Prediction (NCEP)/DOE reanalysis (R2) are downscaled using the NCEP Environmental Climate Prediction Center regional spectral model (RSM) to produce precipitation at 20 km resolution for 16 summer seasons (19902005). The RSM produces realistic details in the regional summer precipitation at 20 km resolution. Compared to R2, the RSM-produced monthly precipitation shows better agreement with observations. There is a reduced wet bias and a more realistic spatial pattern of the precipitation climatology compared with the interpolated R2 values. The root mean square errors of the monthly R2 precipitation are reduced over 93 (1,697) of all the grid points in the five states (1,821). The temporal correlation also improves over 92 (1,675) of all grid points such that the domain-averaged correlation increases from 0.38 (R2) to 0.55 (RSM). The RSM accurately reproduces the first two observed eigenmodes, compared with the R2 product for which the second mode is not properly reproduced. The spatial patterns for wet versus dry summer years are also successfully simulated in RSM. For shorter time scales, the RSM resolves heavy rainfall events and their frequency better than R2. Correlation and categorical classification (above/near/below average) for the monthly frequency of heavy precipitation days is also significantly improved by the RSM.

Stress distributions in a horizontal pressure vessel and the saddle supports

This paper presents analysis results of stress distributions in a horizontal pressure vessel and the saddle supports. The results are obtained from a 3D finite element analysis. A quarter of the pressure vessel is modeled with realistic details of saddle supports. In addition to presenting the stress distribution in the pressure vessel, the results provide details of stress distribution in different parts of the saddle separately, i.e. wear, web, flange and base plates. The effect of changing the load and various geometric parameters is investigated and recommendations are made for the optimal values of ratio of the distance of support from the end of the vessel to the length of the vessel and ratio of the length of the vessel to the radius of the vessel for minimum stresses both in the pressure vessel and the saddle structure. Physical reasons for favoring of a particular value of ratio of the distance of support from the end of the vessel to the length of the vessel are also outlined.

Analysis of Recurrent Networks of Pulse-Coupled Noisy Neural Oscillators

Synchronization of neural oscillators has been well studied by both theorists and experimentalists. However, realistic details are often disregarded for tractability. Here, we consider a recurrent network of pulse-coupled neural oscillators since synaptic communication is often mediated by spikes. Neurons receive many stochastic inputs that have effects depending on the state of the neuron; thus, we incorporate phase-dependent (multiplicative) noise. Previous analysis of neural oscillators with additive noise (not necessarily weak) cannot be directly applied here because this results in analytically intractable equations that possibly have singularities. However, assuming weak coupling and weak noise, we accurately and analytically characterize various phenomena by a linear stability analysis around an asymptotic steady-state density approximation. Depending on the phase resetting curve, the system can undergo a supercritical Andronov-Hopf bifurcation as the recurrent coupling strength of the oscillator is increased, leading to synchronous and oscillatory population activity. The analysis is extended to include recurrent input through synapses with kinetics—it generally stabilizes the incoherent state. Moreover, input via synapses can uncover a bifurcation that does not exist with instantaneous recurrent input. The analysis is further generalized to recurrent input that is a smooth function of the population firing rate. The results are applied to a closed-loop system of neural oscillators that receive feedback mediated by a noisy population of excitable integrate-and-fire neurons. Our results extend the power of perturbation methods for dealing with equations that, a priori, appear intractable.

Real time falling animation with active and protective responses

Combined with motion capture and dynamic simulation, characters in animation have realistic motion details and can respond to unexpected contact forces. This paper proposes a novel and real-time character motion generation approach which introduces a parallel process, and uses an approximate nearest neighbor optimization search method. Besides, we employ a support vector machine (SVM), which is trained on a set of samples and predicts a subset of our ‘return-to’ motion capture (mocap) database in order to reduce the search time. In the dynamic simulation process, we focus on designing a biomechanics based controller which detects the balance of the characters in locomotion and drives them to take several active and protective responses when they fall to the ground in order to reduce the injuries to their bodies. Finally, we show the time costs in synthesis and the visual results of our approach. The experimental results indicate that our motion generation approach is suitable for interactive games or other real-time applications.

“A Lonely Cottage on the Vasilyevsky Island” and Pushkin’s Tales about st. Petersburg

Pushkin was not only a founder of the Petersburg text tradition; he was the first Russian author who wrote in the style of fantastic realism. Its main feature is a combination of a fantastic plot with realistic details, such as “The Queen of Spades,” “The Broze Rider,” and “A Small Cottage in Kolomna.” The article focuses on a grotesque oral story about the lonely cottage on the Vasilyevsky Island, told by Pushkin and written down and then published by his acquaintance Titov. Based on a hint contained in its introduction, it is argued that the story about a lonely cottage was composed by Pushkin as a sort of a secret funerary composition, which explains the gloomy atmosphere of the narrative. The article also draws parallels between this story and other works by Pushkin in the style of fantastic realism. As a founder of the Petersburg text tradition, it is shown how Pushkin’s picture of the world was moving from a deterministic vision to a probabilistic one.

Oriental Cities, Postmodern Futures: Naked Lunch, Blade Runner, and Neuromancer

When Leopold Bloom first walks out into the streets of Dublin in James Joyce's Ulysses, the reader is treated to a series of realistic details about this Irish urban landscape: street numbers, pavement, and the bread van from Boland's. But barely half a paragraph passes before Bloom begins to asso ciate this urban landscape with Someplace in the east (57). As Bloom walks, the landscape of Dublin is overlaid with that of an imagined oriental city: Walk along a strand, a strange land, come to a city gate . . . Wander through awned streets. Turbaned faces going by. Dark caves of carpet shops, big man, the terrible, seated crosslegged smoking a coiled pipe (57). Bloom's vision is, of course, built entirely on orien tal clich?s, as well as on images of imported commodities (carpet shops) and urban popular culture (the pantomime show of Turko the Terrible) that are less facets of the Orient than aspects of Dublin itself with oriental associations. Although Bloom's reverie may seem constructed from whole cloth, careful parsing of the allusions shows how the Western city itself is rich in oriental signifiers; Orientalism is already part of the European urban fabric. At the heart of the modernist canon, oriental tropes prove central to the construction of modernist urban space. But this oriental Dublin is also remarkable for its self-consciousness as a literary construction, as Bloom draws a distinction between his reverie and the actual East: Probably not a bit like it really. Kind of stuff you read: in the track of the sun. Sunburst on the titlepage. Bloom not only acknowledges the role of orientalist travelogue in constructing his vision of the city, but he even pinpoints his exact source: Frederick Thompson's In the Track of the Sun (1893). This image of the oriental sun is associated with fantasy and error: What Arthur Griffith said about the headpiece over the Freeman leader: a homerule sun rising up in the northwest from the laneway behind the bank of Ireland (57). Thus Joyce's orientalized Dublin, while demonstrating the degree to which Orientalism already, at the beginning of the twentieth century, structures the Western city, exposes urban Orientalism as a literary fiction. The complex role of oriental tropes in such modernist imaginings of

Multi-class kinematic wave theory of traffic flow

The kinematic wave theory of traffic flow was independently developed by Lighthill and Whitham [Lighthill, M.J., Whitham, G.B., 1955. On kinematic waves. II. A theory of traffic flow on long crowded roads. Procedings of Royal Society A 229, 281–345] and Richards [Richards, P.I., 1956. Shockwaves on the highway. Operations Research 4, 42–51]. The original LWR model was extended in different directions to incorporate more and realistic details. The distinction of classes in traffic flow has received considerable attention recently. This paper proposes a framework for the different existing multi-class extensions of the kinematic wave theory. It turns out that the difference between all models lies in the assumption on how several classes interact. A new model is proposed where classes interact on a non-cooperative way. Slow vehicles act as moving bottlenecks for the fast vehicles, while fast vehicles maximize their speed without influencing slower vehicles. This leads to anisotropic behaviour of the traffic stream. This means that vehicles only react on stimuli in front of them. The new multi-class model is presented and illustrated in the moving bottleneck example of Newell [Newell, G.F., 1998. A moving bottleneck. Transportation Research Part B 32(8), 531–537].

A Simulation Exercise to Illustrate the Impact of an Enterprise System on a Service Supply Chain

In this paper, we present a computer-based simulation exercise designed to help students understand the impact of an enterprise system on business performance in a service supply chain. The particular service supply chain simulated in the exercise is a wireless telecommunications firm. In this exercise, students perform simulations to experience managing the supply chain of the telecommunications firm with and without an enterprise system. The simulator tracks their business performance. Then the results are used as the basis of discussion in a subsequent debriefing session. We describe the educational goals of the simulation exercise and how the exercise can be structured in order to achieve these goals. The latter is illustrated by the use of the simulation exercise in a master's level supply chain management course in the Red McCombs School of Business at the University of Texas at Austin. The simulator includes realistic details. In fact, it is based on the extensive consulting experiences of the first author with two North American telecommunications firms. We describe the simulator in detail under the various scenarios, explain how it was validated, and provide the simulator equations in system dynamics format in Appendix B.

The Translator’s ‘Magic’ Wand: Harry Potter’s Journey from English into French

Much has been written about the international phenomenon that the Harry Potter series has become and inevitably about the translations that contributed to its success. Eirlys E. Davis’s comparative analysis of some of these translations in particular shows dissimilarities between the strategies adopted in different languages and presents individual translators’ choices as inconsistent. This paper deals almost exclusively with the French translation of Harry Potter and the Philosopher’s Stone and reveals that, in the light of the ideological and cultural reality of the receiving corpus, patterns of translation techniques do appear. This paper looks at the transformative strategies and their effects in the target text, first focusing on the treatment of alien British values. Their transformation and disappearance indicate the need to produce a text morally suitable for its assumed readership: French youngsters. Indeed, it seems that the skopos of the target text – being read by French children – determined the translator’s decisions not only to smooth down extreme British otherness but also to reinforce the fantasy of Harry Potter’s world. Indeed, the French creates an utterly “other” world by strengthening its fantastic and magical aspects while undermining the sense of familiarity and credibility of the community portrayed. The shift from a child’s perspective in the original to an adult’s in the translation leads to numerous omissions of banal and realistic details, weakening the realness of the setting and the protagonists. I give textual and extra-textual examples of these transformative strategies which ultimately reduced Harry Potter à l’école des sorciers to a fairy tale and shaped the way it was perceived and received in France.

Regional climate model simulation of U.S. soil temperature and moisture during 1982–2002

The fifth‐generation PSU‐NCAR Mesoscale Model (MM5)‐based regional climate model (CMM5) capability in simulating the U.S. soil temperature and soil moisture annual cycle and interannual variability is evaluated by comparing the 1982–2002 continuous integration driven by the NCEP‐DOE AMIP II reanalysis (R‐2) with observations, the R‐2 derivatives and North American Land Data Assimilation System (NLDAS) products. For the annual cycle, the CMM5 produces more realistic regional details and overall smaller biases than the driving R‐2 and NLDAS outputs. The CMM5 also faithfully simulates interannual variations of soil temperature over the central United States and soil moisture in Illinois and Iowa, where observational data are available. The existing CMM5 differences from observations in soil temperature (moisture) cannot be fully explained by model biases in surface air temperature (precipitation). Inconsistencies between measurements taken under short grass versus model representations beneath other land cover types may play an important role. In particular, such measurements overestimate soil temperature in summer and fall while generating a 1‐month phase lead in the soil moisture annual cycle with respect to croplands in the model. The result emphasizes the need for more comprehensive study on model evaluation and bias understanding of soil temperature and soil moisture.

Coarse-grained rigid blob model for soft matter simulations

We have developed a coarse-grained multiscale molecular simulation method for soft matter systems that directly incorporates stereochemical information. We divide the material into disjoint groups of atoms or particles that move as separate rigid bodies; we call these groups "rigid blobs," hence the name coarse-grained rigid blob model. The method is enabled by the construction of transferable interblob potentials that approximate the net intermolecular interactions, as obtained from ab initio electronic structure calculations, other all-atom empirical potentials, experimental data, or any combination of the above. We utilize a multipolar expansion to obtain the interblob potential-energy functions. The series, which contains controllable approximations that allow us to estimate the errors, approaches the original intermolecular potential as the number of terms increases. Using a novel numerical algorithm, we can calculate the interblob potentials very efficiently in terms of a few interaction moment tensors. This reduces the labor well beyond what is required in standard molecular-dynamics calculations and allows large-scale simulations for temporal scales commensurate with characteristic times of nano- and mesoscale systems. A detailed derivation of the formulas is presented, followed by illustrative applications to several systems showing that the method can effectively capture realistic microscopic details and can easily extend to large-scale simulations.

Tax Management of Stock Portfolios

Most taxable investors and their investment managers probably misunderstand the true value of tax deferral and proper tax lot management. Simulations based on historical S&P 500 returns allow the derivation of estimates of the tax alpha that can be achieved by tax deferral and selective turnover by tax lot. The simulations include realistic details of trading costs, loss carry-forwards, various turnover rates, short-term capital gains, and the estate tax. Long-term capital gains tax deferral is seen to be not very valuable until about the ten-year mark, but the step-up in cost basis at death can make shorter deferral times valuable, even after accounting for the estate tax. The real mechanism of tax deferral makes it more like a partnership with the government than an interest-free loan. These findings, like those of other research, call into question the efficacy of active management for long-term taxable investors.

On the tensorial nature of advective porosity

Field tracer tests indicate that advective porosity, the quantity relating advective velocity to Darcy flux, may exhibit directional dependence. Hydraulic anisotropy explains some but not all of the reported directional results. The present paper shows mathematically that directional variations in advective porosity may arise simply from incomplete mixing of an inert tracer between directional flow channels within a sampling (or support) volume ω of soil or rock that may be hydraulically isotropic or anisotropic. In the traditional fully homogenized case, our theory yields trivially a scalar advective porosity equal to the interconnected porosity ϕ, thus explaining neither the observed directional effects nor the widely reported experimental finding that advective porosity is generally smaller than ϕ. We consider incomplete mixing under conditions in which the characteristic time t D of longitudinal diffusion along channels across ω is much shorter than the characteristic time t H required for homogenization through transverse diffusion between channels. This may happen where flow takes place preferentially through relatively conductive channels and/or fractures of variable orientation separated by material that forms a partial barrier to diffusive transport. Our solution is valid for arbitrary channel Peclet numbers on a correspondingly wide range of time scales t D ⩽ t ≪ t H . It shows that the tracer center of mass is advected at a macroscopic velocity which is generally not collinear with the macroscopic Darcy flux and exceeds it in magnitude. These two vectors are related through a second-rank symmetric advective dispersivity tensor Φ. If the permeability k of ω is a symmetric positive-definite tensor, so is Φ. However, the principal directions and values of these two tensors are generally not the same; whereas those of k are a fixed property of the medium and the length-scale of ω, those of Φ depend additionally on the direction and magnitude of the applied hydraulic gradient. When the latter is large, diffusion has negligible effect on Φ and one may consider tracer mass to be distributed between channels in proportion to the magnitude of their Darcy flux. This is made intuitive through a simple example of an idealized fracture network. Our analytical formalism reveals the properties of Φ but is too schematic to allow predicting the latter accurately on the basis of realistic details about the void structure of ω and tracer mass distribution within it. Yet knowing the tensorial properties of Φ is sufficient to allow determining it indirectly on the basis of ω-scale hydraulic and tracer data, including concentrations that represent homogenized samples extracted from (or sensed externally across) an ω-scale plume.