Fast Global Illumination on Dynamic Height Fields

We present a real-time method for rendering global illumination effects from large area and environmental lights on dynamic height fields. In contrast to previous work, our method handles inter-reflections (indirect lighting) and non-diffuse surfaces. To reduce sampling, we construct one multi-resolution pyramid for height variation to compute direct shadows, and another pyramid for each indirect bounce of incident radiance to compute inter-reflections. The basic principle is to sample the points blocking direct light, or shedding indirect light, from coarser levels of the pyramid the farther away they are from a given receiver point. We unify the representation of visibility and indirect radiance at discrete azimuthal directions (i.e., as a function of a single elevation angle) using the concept of a "casting set" of visible points along this direction whose contributions are collected in the basis of normalized Legendre polynomials. This analytic representation is compact, requires no precomputation, and allows efficient integration to produce the spherical visibility and indirect radiance signals. Sub-sampling visibility and indirect radiance, while shading with full-resolution surface normals, further increases performance without introducing noticeable artifacts. Our method renders 512×512 height fields (> 500K triangles) at 36Hz.     

Dimensional analysis of ionic transport problems in hydrated cement systems: Part 1. Theoretical considerations

The validity of the local equilibrium assumption in hydrated cement systems that a particular chemical reaction is instantaneous with respect to transport is examined using a dimensional analysis of electrochemical transport in cementitious materials. The transport equation parameters are scaled, resulting in a dimensionless equation. The dimensionless coefficient for each reaction/transport term determines its relative contribution to the overall process. The diffusion of ions in a reactive porous medium can be fully described on the basis of six independent dimensionless numbers. The analysis demonstrates that the kinetics of the reaction determine the appropriate time constant for the analysis. The formalism is applied to the dissolution of calcium hydroxide under an electrochemical potential gradient. The results are in agreement with previous observations and demonstrate quantitatively the local equilibrium hypothesis is valid in most practical cases where ions are transported by diffusion through a saturated material.     

4 beta, 15-Diacetoxyscirpenol induces cytotoxicity and alterations in phagocytic and Fc-receptor expression functions in chicken macrophages in vitro

Teleoperation is frequently performed with misalignments between operator or camera viewing direction and controller orientation. Examples of this occur in endoscopic surgery and in teleoperation with multiple camera views. The objective of this study was to find a method to automatically compensate for those misalignments so that human operators performing tasks under such scenarios could achieve levels of performance comparable to aligned conditions without additional training requirements. In this paper we report on a set of experiments conducted to test a method developed for that purpose. Participants were asked to track a randomly moving target on a computer display using a cursor controlled with a joystick. Performance was recorded under various visual-motor misalignments with and without automated compensation. Results indicated significant improvements in operator performance through use of automatic compensation only under certain types of misalignment. Actual or potential applications of this research include teleoperation and endoscopic surgery.     

Optimal actuation of nonlinear resonant systems

In this study, we examine a new approach for actuation of dynamical systems with minimum work and maximum amplitude while maintaining constraints on the actuation force. Two methodology issues are addressed in the paper: sensitivity analysis about the nonlinear transient response and exploration of the strongly nonlinear relationship between the two objectives and the actuation design variables. The optimization analysis is carried out on lightly damped Duffing systems. The formulation of the optimization problem is found ideally suited to resolve the difficulty of dependence of response on initial conditions. The tradeoff curve of work and amplitude is computed. The optimal actuation strove to compensate for the limited force amplitude by an abrupt change in the force in time. Finally the optimization procedure is demonstrated on the kinematic design of hovering insect flight. The optimal design gives 50% reduction in power consumption, with a larger cutback for an actuation with high acceleration.     

Optimal design of sustainable cellulosic biofuel supply chains: Multiobjective optimization coupled with life cycle assessment and input–output analysis

This article addresses the optimal design and planning of cellulosic ethanol supply chains under economic, environmental, and social objectives. The economic objective is measured by the total annualized cost, the environmental objective is measured by the life cycle greenhouse gas emissions, and the social objective is measured by the number of accrued local jobs. A multiobjective mixed‐integer linear programming (mo‐MILP) model is developed that accounts for major characteristics of cellulosic ethanol supply chains, including supply seasonality and geographical diversity, biomass degradation, feedstock density, diverse conversion pathways and byproducts, infrastructure compatibility, demand distribution, regional economy, and government incentives. Aspen Plus models for biorefineries with different feedstocks and conversion pathways are built to provide detailed techno‐economic and emission analysis results for the mo‐MILP model, which simultaneously predicts the optimal network design, facility location, technology selection, capital investment, production planning, inventory control, and logistics management decisions. The mo‐MILP problem is solved with an ε‐constraint method; and the resulting Pareto‐optimal curves reveal the tradeoff between the economic, environmental, and social dimensions of the sustainable biofuel supply chains. The proposed approach is illustrated through two case studies for the state of Illinois. © 2011 American Institute of Chemical Engineers AIChE J, 2012