Due to the growing use of Atomic Force Microscope (AFM) nanorobots in the moving and manipulation of cylindrical nanoparticles (carbon nanotubes and nanowires) and the fact that these processes cannot be simultaneously observed, a computer simulation of the involved forces for the purpose of predicting the outcome of the process becomes highly important. So far, no dynamic 3D model that shows changes in these forces in the course of process implementation has been presented. An algorithm is used in this paper to show in 3D, the manner by which the dynamic forces vary in the mentioned process. The presented model can simulate the forces exerted on the probe tip during the manipulation process in three directions. Because of the nonlinearity of the presented dynamic model, the effective parameters have been also studied. To evaluate the results, the parameters of the 3D case (cylindrical model) are gradually reduced and it is transformed into a 2D model (disk model); and we can observe a good agreement between the results of the two simulations. Next, the simulation results are compared with the experimental results, indicating changes in lateral force. With the help of the offered dynamic model, the cantilever deformation and the forces interacting between probe tip and particle can be determined from the moment the probe tip contacts the nanoparticle to when the nanoparticle dislodges from the substrate surface.

Aliases play an important role in online environments by facilitating anonymity, but also can be used to hide the identity of cybercriminals. Previous studies have investigated this alias matching problem in an attempt to identify whether two aliases are shared by an author, which can assist with identifying users. Those studies create their training data by randomly splitting the documents associated with an alias into two sub-aliases. Models have been built that can regularly achieve over 90% accuracy for recovering the linkage between these ‘random sub-aliases’. In this paper, random sub-alias generation is shown to enable these high accuracies, and thus does not adequately model the real-world problem. In contrast, creating sub-aliases using topic-based splitting drastically reduces the accuracy of all authorship methods tested. We then present a methodology that can be performed on non-topic controlled datasets, to produce topic-based sub-aliases that are more difficult to match. Finally, we present an experimental comparison between many authorship methods to see which methods better match aliases under these conditions, finding that local n-gram methods perform better than others.

We give a constructive proof showing that every finitely generated polynomial ideal has a Gröbner basis, provided the ring of coefficients is Noetherian in the sense of Richman and Seidenberg. That is, we give a constructive termination proof for a variant of the well-known algorithm for computing the Gröbner basis. In combination with a purely order-theoretic result we have proved in a separate paper, this yields a unified constructive proof of the Hilbert basis theorem for all Noether classes: if a ring belongs to a Noether class, then so does the polynomial ring. Our proof can be seen as a constructive reworking of one of the classical proofs, in the spirit of the partial realisation of Hilbert's programme in algebra put forward by Coquand and Lombardi. The rings under consideration need not be commutative, but are assumed to be coherent and strongly discrete: that is, they admit a membership test for every finitely generated ideal. As a complement to the proof, we provide a prime decomposition for commutative rings possessing the finite-depth property.

Program transformation is an appealing technique which allows to improve run-time efficiency, space-consumption, and more generally to optimize a given program. Essentially, it consists of a sequence of syntactic program manipulations which preserves some kind of semantic equivalence. Unfolding is one of the basic operations used by most program transformation systems and consists of the replacement of a procedure call by its definition. While there is a large body of literature on the transformation and unfolding of sequential programs, very few papers have addressed this issue for concurrent languages. This paper defines an unfolding system for Constraint Handling Rules programs. We define an unfolding rule, show its correctness and discuss some conditions that can be used to delete an unfolded rule while preserving the program meaning. We also prove that, under some suitable conditions, confluence and termination are preserved by the above transformation.

We consider structured specifications built from flat specifications using union, translation and hiding with their standard model-class semantics in the context of an arbitrary institution. We examine the alternative of sound property-oriented semantics for such specifications, and study their relationship to model-class semantics. An exact correspondence between the two (completeness) is not achievable in general. We show through general results on property-oriented semantics that the semantics arising from the standard proof system is the strongest sound and compositional property-oriented semantics in a wide class of such semantics. We also sharpen one of the conditions that does guarantee completeness and show that it is a necessary condition.

Let G be a string graph (an intersection graph of continuous arcs in the plane) with m edges. Fox and Pach proved that G has a separator consisting of $O(m^{3/4}\sqrt{\log m})$ vertices, and they conjectured that the bound of $O(\sqrt m)$ actually holds. We obtain separators with $O(\sqrt m \,\log m)$ vertices.

Thank you for the support in getting Network Science up and running. We are deeply appreciative of the work our associate editors, authors, and reviewers have put into realizing this vision of an interdisciplinary journal for network science. And of course, the journal would not be possible without the hard work of the editors of Network Science, who act as action editors for the submitted articles.

This paper presents a novel global path planning method for mobile robots. An improved grid map, called three-dimensional-like map, is developed to represent the global workspace area. The new environment model includes not only contour information of obstacles but also artificial height information. Based on this new model, a simple but efficient obstacle avoidance algorithm is developed to solve robot path planning problems in static environment. The proposed algorithm only requires simple distance calculations and several comparison operations. In addition, unlike other algorithms, the proposed algorithm only needs to deal with some obstacles instead of all. The research results show that this method is computationally efficient and can be used to find an optimal or near optimal path.

For decades Robotica has had a characteristic look and page layout that has served our readership well. However, recent advances in publishing technology make now an excellent time to experiment with some new ideas. From January 2014 we will be using an exciting new cover design concept that will include unique artwork featuring one or more of the topics covered in each issue. Moreover, we will be changing from our traditional double-column format to a new single-column one that will facilitate larger figures, tables and equations. At the end of this month's issue, we will include a sneak peek at the new page format via an article typeset in this new single-column style. We hope that our readership embraces this change. And we look forward to continuing to publish papers of high quality and broad international appeal.