An Algorithm Template for Domain-Based Parallel Irregular Algorithms

The parallelization of irregular algorithms has not been as widely studied as the one of regular codes. In particular, while there are many proposals of parallel skeletons and libraries very well suited to regular algorithms, this is not the case for irregular ones. This is probably due to the complexity of finding common patterns, behaviors and semantics in these algorithms. This is unfortunate, as the parallelization of irregular algorithms would benefit even more than that of regular codes from the higher degree of abstraction provided by skeletons. This work proposes to exploit the concept of domain defined on some property of the elements to process in order to enable the simple and effective parallelization of irregular applications. Namely, we propose to use such domains both to decompose the computations in parallel tasks and to detect and avoid conflicts between these tasks. A generic C++ library providing a skeleton for multicore systems built on this idea is described and evaluated. Our experimental results show that this library is a very practical tool for the parallelization of irregular algorithms with little programming effort.     

Amplification effect of platelet type nanoparticles on the orientation behavior of injection molded nylon 6 composites

The effect of platelet type nanoparticles and processing conditions; mold temperature and injection speed, on the development of local microstructure in injection molded nylon 6 parts was investigated. The molded parts exhibit two crystal forms (α and γ) of nylon 6 in varying proportions from skin to core. The γ crystals preferentially grow near the surface regions and α crystal fraction increases with distance from the surface in all molded parts. However, the spatial variation of crystal phases across the thickness in nanocomposites differs from that of unfilled nylon 6. Nanoplatelets induce high levels of orientation of the polymer matrix throughout the thickness of the molded part even at high mold temperatures where nonisothermal effects are highly suppressed and confined to very close proximity of surfaces. These high chain orientation levels observed in nanoparticle filled systems is a result of the shear amplification effect that occurs in small spaces between adjacent nanoparticles of differing velocity. The local preferential crystalline orientation of nylon 6 resin and nanoparticles across the thickness of the molded parts are investigated using a series of structure characterization techniques including microbeam wide angle X-ray, SAXS and TEM.     

Simultaneous Localization and Mapping Using Rao-Blackwellized Particle Filters in Multi Robot Systems

In this paper we investigate the problem of Simultaneous Localization and Mapping (SLAM) for a multi robot system. Relaxing some assumptions that characterize related work we propose an application of Rao-Blackwellized Particle Filters (RBPF) for the purpose of cooperatively estimating SLAM posterior. We consider a realistic setup in which the robots start from unknown initial poses (relative locations are unknown too), and travel in the environment in order to build a shared representation of the latter. The robots are required to exchange a small amount of information only when a rendezvous event occurs and to measure relative poses during the meeting. As a consequence the approach also applies when using an unreliable wireless channel or short range communication technologies (bluetooth, RFId, etc.). Moreover it allows to take into account the uncertainty in relative pose measurements. The proposed technique, which constitutes a distributed solution to the multi robot SLAM problem, is further validated through simulations and experimental tests.     

Comparison of machine learning algorithms for optimization and improvement of process quality in conventional metallic materials

This paper presents a particular problem dealing with the apparition of burr during the drilling process in the aeronautic industry. This burr cannot exceed a height limit of 127?μm as set out by the aeronautical guidelines and must be eliminated before riveting. If this is not performed, it can cause structural damage which would constitute a danger due to the lack of safety. Moreover, the industry needs to find an automated and optimised process in which the drilling and deburring can be carried out in real time, eliminating those other unnecessary tasks, in order to obtain high-quality pieces. The work presents the applicability of data mining and machine learning techniques so as to obtain a real time burr detection model. This model could be implanted in the computer numerical control of the machine allowing the whole process to be automated and optimised. These techniques can be applied to other types of processes.     

Design of PI and PID controllers with transient performance specification

Proportional-integral-derivative (PID) controllers are widely used in industrial control systems because of the reduced number of parameters to be tuned. The most popular design technique is the Ziegler-Nichols method, which relies solely on parameters obtained from the plant step response. However, besides being suitable only for systems with monotonic step response, the compensated systems whose controllers are tuned in accordance with the Ziegler-Nichols method have generally a step response with a high-percent overshoot. In this paper, tuning methods for proportional-integral (PI) and PID controllers are proposed that, like the Ziegler-Nichols method, need only parameters obtained from the plant step response. The methodology also encompasses the design of PID controllers for plants with underdamped step response and provides the means for a systematic adjustment of the controller gain in order to meet transient performance specifications. In addition, since all the development of the methodology relies solely on concepts introduced in a frequency-domain-based control course, the paper has also a didactic contribution.     

Rational stabilising commutative controllers: parameterisation and characterisation of degrees of freedom

The Characteristic Locus Method constitutes a generalisation of the classical frequency response approach and as such provides a natural platform for design aimed at meeting specifications such as closed-loop stability and dynamic performance. However, to overcome problems of sensitivity to uncertainty, it is necessary to precondition the plant transfer function matrix (TFM) with the view to improving the orthogonality of the eigenvector functions. All that remains then is to use controllers which adjust the frequency response of the eigenfunctions of the TFM while leaving the eigenvectors unaltered. This implies the need for commutative controllers which may be irrational and may not be internally stabilising. The present paper gives a complete characterisation of the class of stabilising rational commutative controllers and derived necessary and sufficient conditions for the existence of this class. These ideas are illustrated by means of case study in which the degrees of freedom contained within the class of commutative controllers are deployed for the meeting design specifications on dynamic performance as well as tolerance to uncertainty.     

Application of the method of multipliers to the optimization of chemical processes

In this work the method of multipliers for the solution of nonlinear mathematical programs with inequality constraints was applied to the optimization of chemical processes realistic enough to illustrate the applicability of the algorithm. The method has proved remarkably effective for the problems studied.     

Primary endobronchial non-hodgkins lymphoma: description of a case and review of the literature]

Photosensitive epilepsy is relatively rare. However, a large proportion of individuals with epilepsy perceive that they are at an increased risk of a seizure whilst exposed to specific photic material. The difference between perceived and real risk may be due to inadequate education and misinformation. One half of the participants in the present survey could not recall being informed of the result of the 'gold standard' test for photosensitivity--intermittent photic stimulation during an electroencephalogram. Furthermore, approximately one-third of our sample were apparently given inaccurate and overcautious advice about their everyday exposure to photic material. Better information and advice is crucial to improve this situation in the future. The majority of people with epilepsy (>95%) who are not photosensitive can pursue activities that involve flickering or patterned light, encompassing educational, employment and leisure opportunities, without undue concern.     

p42/p44 mitogen-activated protein kinases activation is required for the insulin-like growth factor-I/insulin induced proliferation, but inhibits differentiation, in rat fetal brown adipocytes

Insulin-like growth factor I (IGF-I)/insulin induced cytosolic p42/p44 mitogen-activated protein kinase (MAPK) activation in a time-dependent manner in fetal brown adipocytes, reaching a maximum at 5 min. Concurrently, nuclear p42/p44 MAPKs were also activated by IGF-I and insulin. This cytosolic and nuclear MAPK activation was totally prevented by pretreatment with the MAPK kinase (MEK1) inhibitor, PD98059. These results indicate that MEK mediates the IGF-I/insulin-induced p42/ p44 MAPK activation. IGF-I and insulin also increased the number of cells in the S + G2/M phases of the cell cycle, PCNA levels, and DNA synthesis at 24 h. This IGF-I/insulin-induced proliferation was completely blunted by the presence of MEK1 inhibitor. In contrast, inhibition of MEK1 potentiated the IGF-I-induced uncoupling protein (UCP-1) and the insulin-induced fatty acid synthase mRNAs expression after short and long-term treatments. Moreover, transient expression of a transfected active MEK construct (R4F) decreased IGF-I-induced UCP-1 and insulin-induced fatty acid synthase mRNA expression. These results demonstrate that p42/p44 MAPKs are essential intermediates for the IGF-I/insulin-induced mitogenesis, but may have a negative role in the regulation of adipocytic and thermogenic differentiation in brown adipocytes.