Depolarization volume and correlation length in the homogenization of anisotropic dielectric composites

In conventional approaches to the homogenization of random particulate composites, both the distribution and size of the component phase particles are often inadequately taken into account. Commonly, the spatial distributions are characterized by volume fraction alone, while the electromagnetic response of each component particle is represented as a vanishingly small depolarization volume. The strong-permittivity-fluctuation theory (SPFT) provides an alternative approach to homogenization wherein a comprehensive description of distributional statistics of the component phases is accommodated. The bilocally-approximated SPFT is presented here for the anisotropic homogenized composite which arises from component phases comprising ellipsoidal particles. The distribution of the component phases is characterized by a two-point correlation function and its associated correlation length. Each component phase particle is represented as an ellipsoidal depolarization region of nonzero volume. The effects of depolarization volume and correlation length are investigated through considering representative numerical examples. It is demonstrated that both the spatial extent of the component phase particles and their spatial distributions are important factors in estimating coherent scattering losses of the macroscopic field.Comment: Typographical error in eqn. 16 in WRM version is corrected in arxiv versio

Electrical control of the linear optical properties of particulate composite materials

The Bruggeman formalism for the homogenization of particulate composite materials is used to predict the effective permittivity dyadic of a two-constituent composite material with one constituent having the ability to display the Pockels effect. Scenarios wherein the constituent particles are randomly oriented, oriented spheres, and oriented spheroids are numerically explored. Thereby, homogenized composite materials (HCMs) are envisaged whose constitutive parameters may be continuously varied through the application of a low-frequency (dc) electric field. The greatest degree of control over the HCM constitutive parameters is achievable when the constituents comprise oriented and highly aspherical particles and have high electro-optic coefficients

Density Matrix Renormalization Group study of 48^{48}Cr and 56^{56}Ni

We discuss the development of an angular-momentum-conserving variant of the Density Matrix Renormalization Group (DMRG) method for use in large-scale shell-model calculations of atomic nuclei and report a first application of the method to the ground state of $^{56}$Ni and improved results for $^{48}$Cr. In both cases, we see a high level of agreement with the exact results. A comparison of the two shows a dramatic reduction in the fraction of the space required to achieve accuracy as the size of the problem grows.Comment: 4 pages. Published in PRC Rapi

The Arbitration Profession in Transition: A Survey of the National Academy of Arbitrators

[From the Foreward]: That the experience, talents, and integrity of the members of the National Academy of Arbitrators are called on to resolve disputes beyond collective bargaining is not surprising. But The Arbitration Profession in Transition shows that this process is far more widespread, and is accelerating, beyond what most of us had speculated. The study provides the baseline for the new century as to the role of Academy members in the expanding use of ADR in employment and in conflicts concerning statutory rights. It is also a remarkable census of who the Academy is, notable for the extraordinarily high participation and cooperation of those studied. It has been compiled with dedication, care, and skill. It is more than a snapshot of a profession; it is an image worthy of contemplation as the Academy, and the users of arbitration and mediation, continue their quest for fairness and equity in the workplace. John Kagel, President –elect, National Academy of Arbitrators, June 1, 2000

Environment-dependent prey capture in the Atlantic mudskipper (Periophthalmus barbarus)

Few vertebrates capture prey in both the aquatic and the terrestrial environment due to the conflicting biophysical demands of feeding in water versus air. The Atlantic mudskipper (Periophthalmus barbarus) is known to be proficient at feeding in the terrestrial environment and feeds predominately in this environment. Given the considerable forward flow of water observed during the mouth-opening phase to assist with feeding on land, the mudskipper must alter the function of its feeding system to feed successfully in water. Here, we quantify the aquatic prey-capture kinematics of the mudskipper and compare this with the previously described pattern of terrestrial feeding. Prior to feeding in the aquatic environment, the gill slits open, allowing water to be expelled through the gill slits. The opposite happens in terrestrial feeding during which the gill slits remain closed at this point. In water, the expansive movements of the head are larger, amounting to a larger volume increase and are initiated slightly later than in the terrestrial environment. This implies the generation of strong suction flows when feeding in water. Consequently, the kinematic patterns of the hydrodynamic tongue during terrestrial feeding and aquatic suction feeding are similar, except for the amplitude of the volume increase and the active closing of the gill slits early during the terrestrial feeding strike. The mudskipper thus exhibits the capacity to change the kinematics of its feeding apparatus to enable successful prey capture in two disparate environments

Impacts on modal choices of new generation freights terminals

Increasing pollution, congestion of roads and worries about the spatial and environmental impacts of road transports have promoted the idea of transferring part of freight transportation from roads to railways and waterways. Given the limited density of these two modes' networks, this policy implies necessarily the development of inter-modal transports. But their operation on a large scale is meeting several problems : the additional cost of transferring the commodities from one mode or means to another, the size of investments in new technology equipment for terminals, specialized rolling stock and information systems, the involvement of several intermediaries plus the control and management of safety and reliability of the services. In the past, many innovative plans and projects for bundling and transshipping were developed, but many plans were abandoned, and despite a steady growth of inter-modal transports, the results obtained are still limited. At the present time, the most promising projects seem to be the introduction of new shuttle connections on transport links with important flows of transports. However, lower costs and better management of services could probably make attractive the organization of more complex schemes like hub-and-spokes organizations. The paper presents a methodology to model bundling concepts on multi-modal freight networks. It is based on the extensive use of virtual links as they are implemented in the NODUS software developed by GTM . Different configurations of inter-modal networks are modeled which are implemented in a digitized trans-European multi-modal network (rail, road and waterway). Cost functions are associated with every (virtual) link which corresponds to a particular transport operation. A matrix of origins and destinations throughout the European space is generated on the basis of global EUROSTAT statistics by the use of a weighted stochastic procedure. Given this transportation task a minimization of generalized costs can be made which assigns transport flows between paths, modes and means of transport. Hence, successive simulations for different configurations and various parameters' values provide a set of measures of their impacts, which can be used for assessing the interest of concrete inter-modal propositions. The indicators are the market shares, the total operating cost of the transportation task, the total cost of a particular operation, the distances covered, the times of transport, the service frequency required, the energy consumption, etc. This research is part of the EU Commission's TERMINET project which focuses on the potentialities of innovative bundling concepts for transport nodes and terminals.