Indirect iterative learning control for a discrete visual servo without a camera-robot model.

This paper presents a discrete learning controller for vision-guided robot trajectory imitation with no prior knowledge of the camera-robot model. A teacher demonstrates a desired movement in front of a camera, and then, the robot is tasked to replay it by repetitive tracking. The imitation procedure is considered as a discrete tracking control problem in the image plane, with an unknown and time-varying image Jacobian matrix. Instead of updating the control signal directly, as is usually done in iterative learning control (ILC), a series of neural networks are used to approximate the unknown Jacobian matrix around every sample point in the demonstrated trajectory, and the time-varying weights of local neural networks are identified through repetitive tracking, i.e., indirect ILC. This makes repetitive segmented training possible, and a segmented training strategy is presented to retain the training trajectories solely within the effective region for neural network approximation. However, a singularity problem may occur if an unmodified neural-network-based Jacobian estimation is used to calculate the robot end-effector velocity. A new weight modification algorithm is proposed which ensures invertibility of the estimation, thus circumventing the problem. Stability is further discussed, and the relationship between the approximation capability of the neural network and the tracking accuracy is obtained. Simulations and experiments are carried out to illustrate the validity of the proposed controller for trajectory imitation of robot manipulators with unknown time-varying Jacobian matrices.     

A comprehensive view of agent-oriented patterns

This paper presents a comprehensive framework for classifying, analyzing and describing agent-oriented software patterns. We present a two dimensional scheme for classifying agent-oriented patterns. We define agent-oriented pattern attributes and use these attributes in a process for analyzing and placing agent-oriented patterns within the classification scheme. Using the proposed classification scheme, we classify 28 patterns written by a variety of agent researchers, chosen from almost 100 patterns which we have studied.     

A unified theory of symmetry for nonlinear multiport and multiterminal resistors

Simple group-theoretic concepts are used to develop a rigorous and comprehensive theory of symmetry for nonlinear multiport and multiterminal resistors which do not rely on geometrical arguments or other ad hoc techniques normally invoked in such studies. This theory unifies all forms of symmetry, including rotation, reflection and complementary symmetry, into a single framework. It also includes all known nonlinear symmetry principles as special cases. Moreover, a general method for identifying all symmetry characteristics possessed by a nonlinear multiport and multiterminal element is given. The main results of this paper:

• 1 Several algorithms for synthesizing a nonlinear multiport or multiterminal element having any prescribed form of symmetry are presented. In particular, various examples are given which illustrate how these algorithms can be used to derive well-known symmetrical nonlinear circuit modules such as push-pull amplifiers, complementary-symmetric amplifiers, rectifiers, modulators, etc.;
• 2 A reduction algorithm is presented which allows a complicated symmetric element to be analysed by a much simpler reduced element;
• 3 A general principle is derived for applying symmetry to achieve frequency separation in nonlinear communication circuits where the even harmonic components are separated from the odd harmonic components.

     

Early Warning Signs of it Project Failure: The Dominant Dozen

The postmortem examination of failed IT projects reveals that long before the failure there were significant symptoms or “early warning signs.” This article describes the top 12 people- related and project-related IT project risks, based on “early warning sign” data collected from a panel of 19 experts and a survey of 55 IT project managers.     

Berry antioxidants: small fruits providing large benefits

Small berry fruits are consumed because of their attractive colour and special taste, and are considered one of the richest sources of natural antioxidants. Their consumption has been linked to the prevention of some chronic and degenerative diseases. The term ‘berry fruits’ encompasses the so‐called ‘soft fruits’, primarily strawberry, currants, gooseberry, blackberry, raspberry, blueberry and cranberry. The objective of this review is to highlight the nutraceutical value of berries and to summarize the factors affecting berry fruit antioxidants. Particular attention is given to postharvest and processing operation factors that may affect fruit phytochemical content. The structure–antioxidant relationships for phenolic compounds – the main group of antioxidants in this fruit group – are presented and major areas for future research are identified. © 2013 Society of Chemical Industry     

An Approach to Support Learning from International Experience with Water Policy

International experiences with water policy and governance arrangements are shared through various international meetings and reports. The underlying assumption is that these experiences provide useful information to policy makers who are looking for ways to improve water resources management in their home country or region. However, little has been written about analytical support for these potentially interested policy makers. They have to reach informed decisions about whether or not to initiate a process of policy transfer, about which foreign experiences to consider and about what parts of those experiences to copy, adapt, or reject. Providing such analytical support is complicated by the involvement of multiple actors in water resources management, who do not necessarily agree on these decisions. This paper outlines an approach to offer analytical support to these multiple actors in the initial phase of a policy transfer process. The approach is applied to the case of the Büyük Menderes river basin in Turkey, where local policy makers were engaged in a policy transfer process related to the EU Water Framework Directive. It is concluded that the outlined approach can be used to inform local policy makers, as it yielded new and valid information in the case. In the absence of overriding political concerns, such information would lead to different decisions in various phases of policy transfer, when compared to a process that lacks this analytical support.     

Embeddings for 4D Einstein equations with a cosmological constant

There are many ways of embedding a 4D spacetime in a given higher-dimensional manifold while satisfying the field equations. In this work, we extend and generalize a recent paper by Mashhoon and Wesson (Gen. Rel. Grav. 39, 1403 (2007)) by showing different ways of embedding a solution to the 4D Einstein equations in vacuum with a cosmological constant, in a Ricci-flat as well as anti-de Sitter 5D manifold. These embeddings lead to different physics in 4D, in particular, to non-equivalent cosmological terms as functions of the extra coordinate. We study themotion of test particles for different embeddings and show that there is a complete equivalence between several definitions of the effective mass of test particles measured in 4D, obtained from different theoretical approaches like the Hamilton-Jacobi formalism and the least action principle. For the case under consideration, we find that the effective mass observed in 4D is the same regardless of whether we consider null or non-null motion in 5D.     

Transforming generate-and-test programs to execute under committed-choice AND-parallelism

This paper concerns the exploitation of user transparent inherent parallelism of pure Prolog programs using program transformation. We describe a novel paradigmenumerate-and-filter for transforming generate-and-test programs for execution under the committed-choice model extended to incorporate multiple solutions based on set enumeration. The paradigm simulates OR-parallelism by stream AND-parallelism integrating OR-parallelism, AND-parallelism, and stream parallelism. Generate-and-test programs are classified into three categories:simple generate-and-test, recursively embedded generate-and-test, and deeply intertwined generate-and-test. The intermediate programs are further transformed to reduce structure copying and metacalls. Algorithms are presented and demonstrated by transforming the representative examples of different classes of generate-and-test programs to Flat Concurrent Prolog equivalents. Statistics show that the techniques are efficient.Funded in part by Cleveland Advanced Manufacturing Program through the State of Ohio as a part of its core research program grant to Center of Automation and Intelligent Systems Research, Case Western Reserve University and NSF equipment grant CDA-8820390 to Kent State University.