COMPETITIVE ANALYSIS OF U.S. FOOD PROCESSING PLANTS

This paper presents a model-based approach for competitive analysis of manufacturing plants in the U. S. food processing industry. As part of this approach, plant competitiveness is measured using Operational Competitiveness Ratings Analysis (OCRA) -- a new non-parametric method of computing relative inefficiency. Drivers of competitiveness are identified in terms of policies related to plant structure and infrastructure. Policies related to plant structure are those decisions that are related with "bricks and mortar" and have long term implications, such as decisions related to plant size and capacity. Policies related to plant infrastructure are decisions related to how the " bricks and mortar" are used. These policies are typically under the direct control of the operations managers and have a short-term orientation, such as decisions related to equipment, quality, inventory, workforce and confusion-engendering activities (e.g. new product introductions and product variety). The empirical analysis is based on detailed cross-sectional data on 20 processed food manufacturing plants. With respect to plant structure, the results suggest that small sized food processing plants are competitive, and both capacity underutilization and overutilization are detrimental to plant competitiveness. Among the significant results with respect to plant infrastructure, equipment maintenance, quality management programs, packaging supplies inventory, workforce training and product variety are positively associated with plant competitiveness. The results also suggest that introduction of new products disrupts plant operations, at least in the short run, and is negatively associated with plant competitiveness.Agribusiness,

Increased security through open source

In this paper we discuss the impact of open source on both the security and transparency of a software system. We focus on the more technical aspects of this issue, combining and extending arguments developed over the years. We stress that our discussion of the problem only applies to software for general purpose computing systems. For embedded systems, where the software usually cannot easily be patched or upgraded, different considerations may apply

Stability of constant retrial rate systems with NBU input*

We study the stability of a single-server retrial queueing system with constant retrial rate, general input and service processes. First, we present a review of some relevant recent results related to the stability criteria of similar systems. Sufficient stability conditions were obtained by Avrachenkov and Morozov (2014), which hold for a rather general retrial system. However, only in the case of Poisson input is an explicit expression provided; otherwise one has to rely on simulation. On the other hand, the stability criteria derived by Lillo (1996) can be easily computed but only hold for the case of exponential service times. We present new sufficient stability conditions, which are less tight than the ones obtained by Avrachenkov and Morozov (2010), but have an analytical expression under rather general assumptions. A key assumption is that interarrival times belongs to the class of new better than used (NBU) distributions. We illustrate the accuracy of the condition based on this assumption (in comparison with known conditions when possible) for a number of non-exponential distributions

On the geometry of entangled states

The basic question that is addressed in this paper is finding the closest separable state for a given entangled state, measured with the Hilbert Schmidt distance. While this problem is in general very hard, we show that the following strongly related problem can be solved: find the Hilbert Schmidt distance of an entangled state to the set of all partially transposed states. We prove that this latter distance can be expressed as a function of the negative eigenvalues of the partial transpose of the entangled state, and show how it is related to the distance of a state to the set of positive partially transposed states (PPT-states). We illustrate this by calculating the closest biseparable state to the W-state, and give a simple and very general proof for the fact that the set of W-type states is not of measure zero. Next we show that all surfaces with states whose partial transposes have constant minimal negative eigenvalue are similar to the boundary of PPT states. We illustrate this with some examples on bipartite qubit states, where contours of constant negativity are plotted on two-dimensional intersections of the complete state space.Comment: submitted to Journal of Modern Optic