204 research outputs found
Modularity of Convergence and Strong Convergence in Infinitary Rewriting
Properties of Term Rewriting Systems are called modular iff they are
preserved under (and reflected by) disjoint union, i.e. when combining two Term
Rewriting Systems with disjoint signatures. Convergence is the property of
Infinitary Term Rewriting Systems that all reduction sequences converge to a
limit. Strong Convergence requires in addition that redex positions in a
reduction sequence move arbitrarily deep. In this paper it is shown that both
Convergence and Strong Convergence are modular properties of non-collapsing
Infinitary Term Rewriting Systems, provided (for convergence) that the term
metrics are granular. This generalises known modularity results beyond metric
\infty
A Universal Machine for Biform Theory Graphs
Broadly speaking, there are two kinds of semantics-aware assistant systems
for mathematics: proof assistants express the semantic in logic and emphasize
deduction, and computer algebra systems express the semantics in programming
languages and emphasize computation. Combining the complementary strengths of
both approaches while mending their complementary weaknesses has been an
important goal of the mechanized mathematics community for some time. We pick
up on the idea of biform theories and interpret it in the MMTt/OMDoc framework
which introduced the foundations-as-theories approach, and can thus represent
both logics and programming languages as theories. This yields a formal,
modular framework of biform theory graphs which mixes specifications and
implementations sharing the module system and typing information. We present
automated knowledge management work flows that interface to existing
specification/programming tools and enable an OpenMath Machine, that
operationalizes biform theories, evaluating expressions by exhaustively
applying the implementations of the respective operators. We evaluate the new
biform framework by adding implementations to the OpenMath standard content
dictionaries.Comment: Conferences on Intelligent Computer Mathematics, CICM 2013 The final
publication is available at http://link.springer.com
Sparsity and cosparsity for audio declipping: a flexible non-convex approach
This work investigates the empirical performance of the sparse synthesis
versus sparse analysis regularization for the ill-posed inverse problem of
audio declipping. We develop a versatile non-convex heuristics which can be
readily used with both data models. Based on this algorithm, we report that, in
most cases, the two models perform almost similarly in terms of signal
enhancement. However, the analysis version is shown to be amenable for real
time audio processing, when certain analysis operators are considered. Both
versions outperform state-of-the-art methods in the field, especially for the
severely saturated signals
Принцип диалогичности извлечения экспертных знаний при оценке инноваций
В статье предлагается использовать принцип диалогичности при прогнозе эффективности инновационных продуктов на основе экспертных данных. Извлечение знаний экспертов в процессе диалога осуществляется с учетом их общественной роли и психофизиологических возможностей с пользованием компьютерных систем поддержки решений
Open continuum robotics–one actuation module to create them all
Experiments on physical continuum robot are the gold standard for evaluations. Currently, as no commercial continuum robot platform is available, a large variety of early-stage prototypes exists. These prototypes are developed by individual research groups and are often used for a single publication. Thus, a significant amount of time is devoted to creating proprietary hardware and software hindering the development of a common platform, and shifting away scarce time and efforts from the main research challenges. We address this problem by proposing an open-source actuation module, which can be used to build different types of continuum robots. It consists of a high-torque brushless electric motor, a high resolution optical encoder, and a low-gear-ratio transmission. For this article, we create three different types of continuum robots. In addition, we illustrate, for the first time, that continuum robots built with our actuation module can proprioceptively detect external forces. Consequently, our approach opens untapped and under-investigated research directions related to the dynamics and advanced control of continuum robots, where sensing the generalized flow and effort is mandatory. Besides that, we democratize continuum robots research by providing open-source software and hardware with our initiative called the Open Continuum Robotics Project, to increase the accessibility and reproducibility of advanced methods
Soft Robotics. Bio-inspired Antagonistic Stiffening
Soft robotic structures might play a major role in the 4th industrial revolution. Researchers have demonstrated advantages of soft robotics over traditional robots made of rigid links and joints in several application areas including manufacturing, healthcare, and surgical interventions. However, soft robots have limited ability to exert larger forces and change their stiffness on demand over a wide range. Stiffness can be achieved as a result of the equilibrium of an active and a passive reaction force or of two active forces antagonistically collaborating. This paper presents a novel design paradigm for a fabric-based Variable Stiffness System including potential applications
Banks' risk assessment of Swedish SMEs
Building on the literatures on asymmetric information and risk taking, this paper applies conjoint experiments to investigate lending officers' probabilities of supporting credit to established or existing SMEs. Using a sample of 114 Swedish lending officers, we test hypotheses concerning how information on the borrower's ability to repay the loan; alignment of risk preferences; and risk sharing affect their willingness to grant credit. Results suggest that features that reduce the risk to the bank and shift the risk to the borrower have the largest impact. The paper highlights the interaction between factors that influence the credit decision. Implications for SMEs, banks and research are discussed
Hall Effect of Spin Waves in Frustrated Magnets
We examine a possible spin Hall effect for localized spin systems with no
charge degrees of freedom. In this scenario, a longitudinal magnetic field
gradient induces a transverse spin current carried by spin wave excitations
with an anomalous velocity which is associated with the Berry curvature raised
by spin chirality, in analogy with anomalous Hall effects in itinerant electron
systems. Our argument is based on a semiclassical equations of motion
applicable to general spin systems. Also, a microscopic model of frustrated
magnets which exhibits the anamalous spin Hall effect is presented.Comment: 5 pages, title and presentation style are changed, accepted for
publication in Phys. Rev. Let
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