Polymorphic systems with arrays : decidability and undecidability

Polymorphic systems with arrays (PSAs) is a general class of nondeterministic reactive systems. A PSA is polymorphic in the sense that it depends on a signature, which consists of a number of type variables, and a number of symbols whose types can be built from the type variables. Some of the state variables of a PSA can be arrays, which are functions from one type to another. We present several new decidability and undecidability results for parameterised control-state reachability problems on subclasses of PSAs

On model checking data-independent systems with arrays without reset

A system is data-independent with respect to a data type X iff the operations it can perform on values of type X are restricted to just equality testing. The system may also store, input and output values of type X. We study model checking of systems which are data-independent with respect to two distinct type variables X and Y, and may in addition use arrays with indices from X and values from Y . Our main interest is the following parameterised model-checking problem: whether a given program satisfies a given temporal-logic formula for all non-empty nite instances of X and Y . Initially, we consider instead the abstraction where X and Y are infinite and where partial functions with finite domains are used to model arrays. Using a translation to data-independent systems without arrays, we show that the u-calculus model-checking problem is decidable for these systems. From this result, we can deduce properties of all systems with finite instances of X and Y . We show that there is a procedure for the above parameterised model-checking problem of the universal fragment of the u-calculus, such that it always terminates but may give false negatives. We also deduce that the parameterised model-checking problem of the universal disjunction-free fragment of the u-calculus is decidable. Practical motivations for model checking data-independent systems with arrays include verification of memory and cache systems, where X is the type of memory addresses, and Y the type of storable values. As an example we verify a fault-tolerant memory interface over a set of unreliable memories.Comment: Appeared in Theory and Practice of Logic Programming, vol. 4, no. 5&6, 200

A Project Study of the Brooding and Rearing of Four Hundred Barred Plymouth Rock Chicks

In the broad and scientific field of poultry production, there are certain phases that have proved to be problems to the average poultryman. The object, or purpose, of this treatise is to enlarge upon or bring to the attention of those who are interested in poultry, this phase of brooding and rearing so that they might be benefited by such information. It is quite impossible to cover everything on this phase; however, those things that are considered most important by the writer are treated through the careful conducting of this project in brooding and rearing. The four hundred Barred Plymouth Rock chicks used in this project were obtained at a day old from Waller, Texas Hatcheries at the price of $32.00. This cost factor should be considered, as the cost of chicks are important for the economical aspects of poultry brooding can never be left out completely. In order to furnish an adequate background for the reader, it is quite necessary that the two methods of brooding be mentioned. They are: natural and artificial brooding. Natural brooding is that brooding that is accomplished through the use of hens, and when only a few chickens are raised, the simplest method to brood is with hens. When the weather is cold, an average sized hen can brood from fifteen to eighteen chickens, but in warm weather the same hen can brood from twenty to twenty-five chickens. Artificial brooding is that brooding which is accomplished by means of some heat-supplying device other than that heat supplied by the hen. Artificial brooding is recommended for practically all poultry raisers, especially where considerable numbers of chicks are to be raised. The use of a brooder reduces the amount of labor required in brooding chicks and is more economical when a hundred or more chicks are raised annually. Also, when chicks are hatched in incubators, or when day-old chicks are bought from a commercial hatchery, the brooding of chicks with brooders is a practical necessity. Brooders may be classified as follows: lamp brooders, holding from 25 to 100 chicks; electric brooders of various sizes, accommodating from 50 to 500 chicks; stove brooders heated by coal, kerosene, or distillate oil with a capacity varying from 200 to 1,000 chicks; hot water pipe systems, the capacity of which is unlimited; battery brooders especially designed for brooding chicks in confinement1, and the gas brooder, the type which was used in this project. It is hoped that the information revealed and the conclusion reached will be remembered as one of the many contributing efforts to make the field of poultry more simple and easily accessible to those who are striving to be successful in poultry production. 1 Poultry Husbandry - Jul

A Proof of Entropy Minimization for Outputs in Deletion Channels via Hidden Word Statistics

From the output produced by a memoryless deletion channel from a uniformly random input of known length $n$, one obtains a posterior distribution on the channel input. The difference between the Shannon entropy of this distribution and that of the uniform prior measures the amount of information about the channel input which is conveyed by the output of length $m$, and it is natural to ask for which outputs this is extremized. This question was posed in a previous work, where it was conjectured on the basis of experimental data that the entropy of the posterior is minimized and maximized by the constant strings $\texttt{000}\ldots$ and $\texttt{111}\ldots$ and the alternating strings $\texttt{0101}\ldots$ and $\texttt{1010}\ldots$ respectively. In the present work we confirm the minimization conjecture in the asymptotic limit using results from hidden word statistics. We show how the analytic-combinatorial methods of Flajolet, Szpankowski and Vall\'ee for dealing with the hidden pattern matching problem can be applied to resolve the case of fixed output length and $n\rightarrow\infty$, by obtaining estimates for the entropy in terms of the moments of the posterior distribution and establishing its minimization via a measure of autocorrelation.Comment: 11 pages, 2 figure

Influência do uso de areia lavada na taxa de respiração de um latossolo vermelho distroférrico argiloso incubado com agregados íntegros e triturados

bitstream/item/66211/1/32008.pdfFERTBIO

Ubiquitous energy storage

This paper presents a vision of a future power system with "ubiquitous energy storage", where storage would be utilized at all levels of the electricity system. The growing requirement for storage is reviewed, driven by the expansion of distributed generation. The capabilities and existing applications of various storage technologies are presented, providing a useful review of the state of the art. Energy storage will have to be integrated with the power system and there are various ways in which this may be achieved. Some of these options are discussed, as are commercial and regulatory issues. In two case studies, the costs and benefits of some storage options are assessed. It is concluded that electrical storage is not cost effective but that thermal storage offers attractive opportunities

Information Security as Strategic (In)effectivity

Security of information flow is commonly understood as preventing any information leakage, regardless of how grave or harmless consequences the leakage can have. In this work, we suggest that information security is not a goal in itself, but rather a means of preventing potential attackers from compromising the correct behavior of the system. To formalize this, we first show how two information flows can be compared by looking at the adversary's ability to harm the system. Then, we propose that the information flow in a system is effectively information-secure if it does not allow for more harm than its idealized variant based on the classical notion of noninterference

Energy dissipation in soil samples during drained triaxial shearing

The discrete-element method was used to simulate drained triaxial compression of large-scale, polydisperse numerical samples at a range of void ratios while tracing all relevant energy components. The frictional dissipation and boundary work are almost equal regardless of sample density. The volumetric work reaches a steady value at large strain. However, the distortional work increases continually as sample deformation continues post-critical state. There is a preferential orientation for frictional dissipation at around 45° to the major principal stress direction. This matches the orientation at which there is the largest number of sliding contacts. The work equations, which are fundamental in most commonly used constitutive models, are linear when plotted against deviatoric strain. The modified Cam Clay work equation substantially over-predicts the frictional dissipation for dense samples. An alternative, thermodynamically consistent work equation gives a much better description of frictional dissipation and is therefore recommended to ensure accuracy in modelling