Sub Farm Interface of the ATLAS Dataflow System

Sub Farm Interface is the event builder of the ATLAS（A Toroidal LHC ApparatuS） Dataflow System. It receives event fragments from the Read Out System, builds full events and sends complete events to the Event Filter for high level event selection. This paper describes the implementation of the Sub Farm Interface. Furthermore, this paper introduces some issues on SFI（Sub Farm Interface） optimization and the monitoring service inside SFI.     

A computer vision system for the detection and classification of vehicles at urban road intersections

The paper presents a real-time vision system to compute traffic parameters by analyzing monocular image sequences coming from pole-mounted video cameras at urban crossroads. The system uses a combination of segmentation and motion information to localize and track moving objects on the road plane, utilizing a robust background updating, and a feature-based tracking method. It is able to describe the path of each detected vehicle, to estimate its speed and to classify it into seven categories. The classification task relies on a model-based matching technique refined by a feature-based one for distinguishing between classes having similar models, like bicycles and motorcycles. The system is flexible with respect to the intersection geometry and the camera position. Experimental results demonstrate robust, real-time vehicle detection, tracking and classification over several hours of videos taken under different illumination conditions. The system is presently under trial in Trento, a 100,000-people town in northern Italy.     

Stabilized discontinuous Galerkin method for hyperbolic equations

In this work a new stabilization technique is proposed and studied for the discontinuous Galerkin method applied to hyperbolic equations. In order to avoid the use of slope limiters, a streamline diffusion-like term is added to control oscillations for arbitrary element orders. Thus, the scheme combines ideas from both the Runge-Kutta discontinuous Galerkin method [J. Scient. Comput. 16 (2001) 173] and the streamline diffusion method [Comput. Methods Appl. Mech. Engrg. 32 (1982)]. To increase the stability range of the method, the diffusion term is treated implicitly. The result is a scheme with higher order in space with the same stability range as the finite volume method. An optimal relation between the time step and the size of the diffusion coefficient is analyzed for numerical precision. The scheme is implemented using the object oriented programming philosophy based on the environment described in [Comput. Methods Appl. Mech. Engrg. 150 (1997)]. Accuracy and shock capturing abilities of the method are analyzed in terms of two bidimensional model problems: the rotating cone and the backward facing step problem for the Euler equations of gas dynamics.     

Design Issues for a Colour Photometric Stereo System

This paper presents the detailed performance analysis for a colour photometric stereo system proposed recently. The system recovers surface colour and surface normal for each surface patch separately, in the presence of highlights and shadows. The error analysis presented concerns every step of the algorithm, and it is based on the assumptions that errors may arise due to Gaussian image noise and errors in the accuracy with which the geometry of the illuminating set-up is known. The analysis is confirmed by experiments. The implications of this sensitivity analysis to the design of such a rig and the choice of threshold values for the algorithm are also discussed and recommendations to a designer are given.     

The general fault detection and isolation problem for 2D state-space models

In this paper, the fault detection and isolation problem for two-dimensional (2D) state-space models is investigated in a rather general setting, by assuming that disturbances may affect the system. In a recent contribution [M. Bisiacco, M.E. Valcher, Observer-based fault detection and isolation for 2D state-space models, Multidim. Systems Signal Process 17 (2006) 219–242], a complete theory of dead-beat (possibly unknown input) observer-based fault detectors and isolators (FDIs) has been developed. Here the wider class of 2D FDIs, which allow to detect and identify possible faults, without requiring a preliminary state estimation, is introduced, and necessary and sufficient conditions for the existence of a dead-beat FDI are derived. Constructive procedures for obtaining such FDIs, and comparisons with the results obtained in [M. Bisiacco, M.E. Valcher, Observer-based fault detection and isolation for 2D state-space models, Multidim. Systems Signal Process 17 (2006) 219–242], are also provided.     

WIRES: A Methodology for Developing Workflow Applications

Workflow management systems are becoming a relevant support for a large class of business applications, and many workflow models as well as commercial products are currently available. While the large availability of tools facilitates the development and the fulfilment of customer requirements, workflow application development still requires methodological guidelines that drive the developers in the complex task of rapidly producing effective applications. In fact, it is necessary to identify and model the business processes, to design the interfaces towards existing cooperating systems, and to manage implementation aspects in an integrated way. This paper presents the WIRES methodology for developing workflow applications under a uniform modelling paradigm – UML modelling tools with some extensions – that covers all the life cycle of these applications: from conceptual analysis to implementation. High-level analysis is performed under different perspectives, including a business and an organisational perspective. Distribution, interoperability and cooperation with external information systems are considered in this early stage. A set of “workflowability” criteria is provided in order to identify which candidate processes are suited to be implemented as workflows. Non-functional requirements receive particular emphasis in that they are among the most important criteria for deciding whether workflow technology can be actually useful for implementing the business process at hand. The design phase tackles aspects of concurrency and cooperation, distributed transactions and exception handling. Reuse of component workflows, available in a repository as workflow fragments, is a distinguishing feature of the method. Implementation aspects are presented in terms of rules that guide in the selection of a commercial workflow management system suitable for supporting the designed processes, coupled with guidelines for mapping the designed workflows onto the model offered by the selected system.     

Encoding Linear Logic with Interaction Combinators

The purpose of this paper is to demonstrate how Lafont's interaction combinators, a system of three symbols and six interaction rules, can be used to encode linear logic. Specifically, we give a translation of the multiplicative, exponential, and additive fragments of linear logic together with a strategy for cut-elimination which can be faithfully simulated. Finally, we show briefly how this encoding can be used for evaluating λ-terms. In addition to offering a very simple, perhaps the simplest, system of rewriting for linear logic and the λ-calculus, the interaction net implementation that we present has been shown by experimental testing to offer a good level of sharing in terms of the number of cut-elimination steps (resp. β-reduction steps). In particular it performs better than all extant finite systems of interaction nets.     

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.     

Automatic Generation of Language-based Tools

Many tools can be automatically derived from formal language definitions, such as compilers/interpreters, editors, analyzers, visualizers/animators, etc. Some examples of language-based tools generated automatically by the LISA system are described in the paper. In addition the specification of an algorithm animator and program visualizer, Alma, generated from an extended LISA input-grammar is discussed; LISA principles and code are reused in Alma implementation.