Separability for lattice systems at high temperature

Equilibrium states of infinite extended lattice systems at high temperature are studied with respect to their entanglement. Two notions of separability are offered. They coincide for finite systems but differ for infinitely extended ones. It is shown that for lattice systems with localized interaction for high enough temperature there exists no local entanglement. Even more quasifree states at high temperature are also not distillably entangled for all local regions of arbitrary size. For continuous systems entanglement survives for all temperatures. In mean field theories it is possible, that local regions are not entangled but the entanglement is hidden in the fluctuation algebra

Soil surface albedo and multispectral reflectance of short-wave radiation as a function of degree of soil slaking.

The feasibility of mapping the degree of soil slaking using remote sensing on the basis of reflected solar radiation was investigated in the laboratory. Relationships between soil surface reflection and wavelength of light were plotted for a range of soil moisture contents and degrees of soil slaking. Reflection tended to increase with decreasing moisture content. Slaking had little effect on reflection at high moisture contents, but slightly increased reflection at low moisture contents. The detection of slaking by spectral analysis is not recommended, while albedo measurements may be successful under dry conditions. (Abstract retrieved from CAB Abstracts by CABI’s permission

Codes on Graphs: Observability, Controllability, and Local Reducibility

Original manuscript: August 30, 2012This paper investigates properties of realizations of linear or group codes on general graphs that lead to local reducibility. Trimness and properness are dual properties of constraint codes. A linear or group realization with a constraint code that is not both trim and proper is locally reducible. A linear or group realization on a finite cycle-free graph is minimal if and only if every local constraint code is trim and proper. A realization is called observable if there is a one-to-one correspondence between codewords and configurations, and controllable if it has independent constraints. A linear or group realization is observable if and only if its dual is controllable. A simple counting test for controllability is given. An unobservable or uncontrollable realization is locally reducible. Parity-check realizations are controllable if and only if they have independent parity checks. In an uncontrollable tail-biting trellis realization, the behavior partitions into disconnected sub-behaviors, but this property does not hold for nontrellis realizations. On a general graph, the support of an unobservable configuration is a generalized cycle

Cross docking for libraries with a depot

Library organizations in the Netherlands show an increasing interest to employ depots for low-cost storage and demand fulfillment of item requests. Typically, all libraries in an organization have a shared catalog, and, on local unavailability, requests can be shipped from elsewhere in the organization. The depot can be used to consolidate shipment requests by making tours along all libraries, delivering requested items, but also picking up items that have to be stored at the depot, or that have to be shipped from one library to another. Cross docking and delayed shipments are two preferred methods for fulfilling requests that cannot be directly met using on-hand stock at the depot. In this paper, we compare these two methods from an inventory control perspective. We model the library system as a Markov Decision process. For one- and two-location systems, we derive analytical results for the average-cost optimal policy, showing that the decision to store items from the location at the depot satisfies a threshold structure depending on the number of rented items. For larger instances, an effective heuristic is proposed exploiting this threshold structure. In numerical experiments, important managerial insights are obtained by comparing cross docking and delayed shipments in different situations. Cross docking is shown to add most value in systems with low total stock, however, delayed shipments may achieve similar costs as cross docking when stock is high or when tours frequently visit all locations. Furthermore, effective decisions can be based on simple model formulations with memoryless rental time distributions