Narrow Results

The Markov Chain Modular (MCM) approach is proposed in this paper in order to solve part of the failure-state dependency problem. The MCM approach completely avoids the failure-state dependency problem by avoiding the combinatorial modeling. To quantitatively assess safety, a new Markov chain modeling technique is developed to represent an m + 2 state homogenous Markov chain model using a three-state Markov model. The transition rate functions of the three-state Markov model can be determined by the transition rates of the m + 2 state Markov chain model. Given a series system has N modules and each module has O(m) operational states, the MCM approach reduces the operational states to O(N × m²) as opposed to O(m^2N) by using the traditional Markov chain model.

We study hyperdefinable groups, the most general kind of groups interpretable in a simple theory. After developing their basic theory, we prove the appropriate versions of Hrushovski's group quotient theorem and the Weil–Hrushovski group chunk theorem. We also study locally modular hyperdefinable groups and prove that they are bounded-by-Abelian-by-bounded. Finally, we analyze hyperdefinable groups in supersimple theories.

A lattice L is coordinatizable, if it is isomorphic to the lattice L(R) of principal right ideals of some von Neumann regular ring R. This forces L to be complemented modular. All known sufficient conditions for coordinatizability, due first to von Neumann, then to Jónsson, are first-order. Nevertheless, we prove that coordinatizability of lattices is not first-order, by finding a non-coordinatizable lattice K with a coordinatizable countable elementary extension L. This solves a 1960 problem of Jónsson. We also prove that there is no statement equivalent to coordinatizability. Furthermore, the class of coordinatizable lattices is not closed under countable directed unions; this solves another problem of Jónsson from 1962.

Let G be a finite nonabelian p-group and F a field of characteristic p and let be the subalgebra spanned by class sums , where C runs over all conjugacy classes of noncentral elements of G. We show that all finite p-groups are subgroups and homomorphic images of p-groups for which . We also give the description of abelian-by-cyclic groups for which is an algebra with zero multiplication or is nil of index 2.

The main focus of this paper is on the problem of relating an ideal $I$ in the polynomial ring $\mathbb{Q}[x_1,\dots ,x_n]$ to a corresponding ideal in ${𝔽}_p[x_1,\dots ,x_n]$ where $p$ is a prime number; in other words, the reduction modulo$p$ of $I$. We first define a new notion of $\sigma$-good prime for $I$ which does depends on the term ordering $\sigma$, but not on the given generators of $I$. We relate our notion of $\sigma$-good primes to some other similar notions already in the literature. Then we introduce and describe a new invariant called the universal denominator which frees our definition of reduction modulo $p$ from the term ordering, thus letting us show that all but finitely many primes are good for $I$. One characteristic of our approach is that it enables us to easily detect some bad primes, a distinct advantage when using modular methods.

The existence and multiplicity of solutions for a class of quasilinear elliptic problems are established for the type

This paper presents the architecture used to develop a micro-robot for narrow pipes inspection. Both the electromechanical design and the control scheme will be described. In pipe environments it is very useful to have a method to retrieve information of the state of the inner part of the pipes in order to detect damages, leaks and holes. Due to the different types of existing pipes, a modular approach with different types of modules has been chosen in order to be able to adapt to the shape of the pipe and to chose the most appropriate gait. The micro-robot has been designed for narrow pipes, a field in which there are not many prototypes. The micro-robot incorporates a camera module for visual inspection and several drive modules for locomotion and turn (helicoidal, inchworm, two degrees of freedom rotation). The control scheme is based on semi-distributed behavior control and is also described. A simulation environment is also presented for prototype testing.

This paper is a further contribution to the extensive study by a number of authors of the subalgebra lattice of a Lie algebra. It is shown that, in certain circumstances, including for all solvable algebras, for all Lie algebras over algebraically closed fields of characteristic p > 0 that have absolute toral rank ≤ 1 or are restricted, and for all Lie algebras having the one-and-a-half generation property, the conditions of modularity and semi-modularity are equivalent, but that the same is not true for all Lie algebras over a perfect field of characteristic three. Semi-modular subalgebras of dimensions one and two are characterised over (perfect, in the case of two-dimensional subalgebras) fields of characteristic different from 2, 3.

The notion of a probabilistic modular space is given, and then some results in convexity is examined in such spaces.

Ceramic bearing surfaces have been used over the last 25 years as a clinical solution to the polyethylene wear debris which has been attributed as the major cause of aseptic loosening in total hip arthroplasties. Research has continued over the last 15 years to transpose the technology from the hip to the knee. Monolithic ceramic knee devices have been implanted, mainly in Japan, but the problem of the femoral fixation has remained. The improvement in the polyethylene materials, coupled with the more congruent knee designs, has focused the major issue to wear particle generation as opposed to fatigue or delamination.

The focus of the Brite EuRam project “Advanced Metal to Ceramic Joining Techniques To Optimise low-friction knee prostheses” was to address the issue of fixation in conjunction with the optimum ceramic bearing surface. This was achieved by the development of a biocompatible active alloy braze for joining medical grade Y-TZP zirconia to titanium alloy. Through optimised chemistry and processing conditions a high strength active alloy braze joint was obtained that satisfied all biological and mechanical requirements.

Extensive Finite Element analysis, mechanical, fatigue, wear and compression strength testing were performed to validate the new concept.

Within this paper, several robot organisms assembled from multiple CoSMO modules are presented. CoSMO is a mobile modular self-reconfigurable robot platform, capable of working autonomously on its own or connected to other modules building a robot organism. The paper provides an introduction of the possibilities and the diversity of the CoSMO platform and the resulting capabilities to solve different tasks depending on the circumstances.

Todays walking robots are capable of walking in a wide range of terrains. One key feature, especially for exploration of unknown or extraterrestrial areas, is however rarely seen: The ability to grasp and manipulate objects or to pick up samples. In this paper we present a robust, lightweight and very versatile gripper, especially designed to be used on a walking robots leg to enable LAURON V and other robots to use their legs for manipulation tasks.