GRASP: A New Search Algorithm for Satisfiability

This paper introduces GRASP (Generic search Algorithm J3r the Satisfiabilily Problem), an integrated algorithmic J3amework 30r SAT that unifies several previously proposed searchpruning techniques and jcilitates identification of additional ones. GRASP is premised on the inevitability of conflicts during search and its most distinguishingjature is the augmentation of basic backtracking search with a powerful conflict analysis procedure. Analyzing conflicts to determine their causes enables GRASP to backtrack non-chronologically to earlier levels in the search tree, potentially pruning large portions of the search space. In addition, by 'ecording" the causes of conflicts, GRASP can recognize and preempt the occurrence of similar conflicts later on in the search. Einally, straighrward bookkeeping of the causali y chains leading up to conflicts a/lows GRASP to identij) assignments that are necessary jr a solution to be found. Experimental results obtained jom a large number of benchmarks, including many J3om the field of test pattern generation, indicate that application of the proposed conflict analysis techniques to SAT algorithms can be extremely ejctive jr a large number of representative classes of SAT instances

Boolean Satisfiability in Electronic Design Automation

Boolean Satisfiability (SAT) is often used as the underlying model for a significant and increasing number of applications in Electronic Design Automation (EDA) as well as in many other fields of Computer Science and Engineering. In recent years, new and efficient algorithms for SAT have been developed, allowing much larger problem instances to be solved. SAT “packages” are currently expected to have an impact on EDA applications similar to that of BDD packages since their introduction more than a decade ago. This tutorial paper is aimed at introducing the EDA professional to the Boolean satisfiability problem. Specifically, we highlight the use of SAT models to formulate a number of EDA problems in such diverse areas as test pattern generation, circuit delay computation, logic optimization, combinational equivalence checking, bounded model checking and functional test vector generation, among others. In addition, we provide an overview of the algorithmic techniques commonly used for solving SAT, including those that have seen widespread use in specific EDA applications. We categorize these algorithmic techniques, indicating which have been shown to be best suited for which tasks

Electrospinning system and process for large scale manufacturing of aligned 3D fiber matrices

This invention relates to the system and process of continuous electrospinning for the production of three-dimensional matrices of aligned polymeric fibres. The system of the present invention comprises an electrospinning capillary tube (3) with positive polarity, a set of multi-electrodes with negative polarity inserted in a peripheral support (15), having each electrode (7) controlled movement allowing its exposure or retraction-occultation to the electrospinning tube (3), a central collecting table (17) of electrospun fibres, which is covered with holes (6,16) connected to a chamber and to a vacuum pump (13). The formation of aligned three-dimensional matrices (30) occurs by deposition of layers, when exposing the electrodes (7) to the capillary tube (3), with the controlled distancing of the central collecting table (17), with respect to the electrospinning tube (3). The present invention has application in the medical field, in tissue engineering, in particular in regenerative medicine.submitte

Automated manufacturing of three-dimensional cell matrices with nanofibres of controlled alignment and uniform cell distribution

This invention relates to a system and a process for the automated manufacture of three-dimensional cell matrices by electrospinning from nanofibres of controlled alignment and uniform cell distribution throughout their thickness. From the implementation of the invention it is possible to obtain, in a totally automatic way and without manual intervention, three-dimensional cell matrices of aligned polymeric fibres, with a uniform cell distribution, throughout the thickness of the matrix, which may present several patterns of alignment of the nanofibres, throughout the thickness, being the cells of the selected tissues seeded, in an alternated way, over the layers of two-dimensional meshes of nanofibres, deposited throughout the thickness, thus making the matrix thickness to be dependent of the number of layers of deposited fibres, of the thickness of the fibres and of the degree of compaction between layers. In this way, the present invention has many applications in various areas, in the manufacture of products or structures, on a nanometric scale, which depend on high surface area, such as in biotechnology, in the pharmaceutical and in tissue engineering areas, in particular in regenerative medicine.publishe

A model for vortex formation in magnetic nanodots

We use Monte Carlo simulation to study the vortex nucleation on magnetic nanodots at low temperature. In our simulations, we have considered a simple microscopic two-dimensional anisotropic Heisenberg model with term to describe the anisotropy due to the presence of the nanodot edge. We have considered the thickness of the edge, which was not considered in previous works, introducing a term that controls the energy associated to the edge. Our results clearly show that the thickness of the edge has a considerable influence in the vortex nucleation on magnetic nanodots. We have obtained the hysteresis curve for several values of the surface anisotropy and skin depth parameter ($\xi$). The results are in excellent agreement with experimental data

Quantum Fields with Noncommutative Target Spaces

Quantum field theories (QFT's) on noncommutative spacetimes are currently under intensive study. Usually such theories have world sheet noncommutativity. In the present work, instead, we study QFT's with commutative world sheet and noncommutative target space. Such noncommutativity can be interpreted in terms of twisted statistics and is related to earlier work of Oeckl [1], and others [2,3,4,5,6,7,8]. The twisted spectra of their free Hamiltonians has been found earlier by Carmona et al [9,10]. We review their derivation and then compute the partition function of one such typical theory. It leads to a deformed black body spectrum, which is analysed in detail. The difference between the usual and the deformed black body spectrum appears in the region of high frequencies. Therefore we expect that the deformed black body radiation may potentially be used to compute a GZK cut-off which will depend on the noncommutative parameter $\theta$.Comment: 20 pages, 5 figures; Abstract changed. Changes and corrections in the text. References adde