Preserving architectural decisions through architectural patterns

Architectural decisions have emerged as a means to maintain the quality of the architecture during its evolution. One of the most important decisions made by architects are those about the design approach such as the use of patterns or styles in the architecture. The structural nature of this type of decisions give them the potential to be controlled systematically. In the literature, there are some works on the automation of architectural decision violation checking. In this paper we show that these works do not allow to detect all possible architectural decision violations. To solve this problem we propose an approach which: (i) describes architectural patterns that hold the architectural decision definition, (ii) integrates architectural decisions into an architectural model and, (iii) automates the architectural decision conformance checking. The approach is implemented using Eclipse modeling framework and its accompanying technologies. Starting from well-known architectural patterns, we show that we can formalize all those related to the structural aspect. Through two evaluations, we show that our approach can be adapted to different architecture paradigms and allows to detect more violations comparing to the existing approaches.     

Linearity, Persistence and Testing Semantics in the Asynchronous Pi-Calculus

In [C. Palamidessi, V. Saraswat, F. Valencia and B. Victor. On the Expressiveness of Linearity vs Persistence in the Asynchronous Pi Calculus. LICS 2006:59–68, 2006] the authors studied the expressiveness of persistence in the asynchronous π-calculus (Aπ) wrt weak barbed congruence. The study is incomplete because it ignores the issue of divergence. In this paper, we present an expressiveness study of persistence in the asynchronous π-calculus (Aπ) wrt De Nicola and Hennessy's testing scenario which is sensitive to divergence. Following [C. Palamidessi, V. Saraswat, F. Valencia and B. Victor. On the Expressiveness of Linearity vs Persistence in the Asynchronous Pi Calculus. LICS 2006:59–68, 2006], we consider Aπ and three sub-languages of it, each capturing one source of persistence: the persistent-input calculus (PIAπ), the persistent-output calculus (POAπ) and persistent calculus (PAπ). In [C. Palamidessi, V. Saraswat, F. Valencia and B. Victor. On the Expressiveness of Linearity vs Persistence in the Asynchronous Pi Calculus. LICS 2006:59–68, 2006] the authors showed encodings from Aπ into the semi-persistent calculi (i.e., POAπ and PIAπ) correct wrt weak barbed congruence. In this paper we prove that, under some general conditions, there cannot be an encoding from Aπ into a (semi)-persistent calculus preserving the must testing semantics.     

Effects of exposition to polluted environments on blood cells of the fish Prochilodus lineatus

In this study, we investigated the effects of contaminated water on the blood parameters of the fish Prochilodus lineatus exposed during 7 and 20 days. Blood was collected with heparinized syringes, and blood smears were prepared and stained with Leishman stain. Slides were examined and photographed using a Leica light microscope. Total white blood cell counts and differential counts of thrombocytes and leukocytes were obtained for statistical analysis. The group exposed to water samples from Lago Azul exhibited an increase in the number of leukocytes and in the total number of white blood cells, suggesting that the chemical contaminants in this environment were acting similarly to antigens in this fish species, causing the proliferation of defense cells. In the group exposed to detergent during 20 days, the number of thrombocytes decreased. These results suggest that the variations in the number of leukocytes were indicators of environmental pollution and that biodegradable detergents may, after a certain time of exposure, affect vital functions in fish, such as coagulation and prevention of infections, which directly involves thrombocytes.     

Fast dimensional inspection of deformable parts from partial views

One of the conventional ways to inspect deformable parts is to compare a data model against its nominal CAD model. This process assumes that the data model includes most of the visible surface including regions around fixation points where the part will be attached to others. This paper proposes a method to inspect deformable part by acquiring only regions that need to be inspected and then by applying to the CAD model a non-linear deformation using FEM modeling to minimize the differences with the partial views. The process first starts with a rigid alignment followed by an iterative process where the part's deformation is iteratively matched to the partial views. In this scheme, fixation points are not digitized and the non-linear part deformation calculations are estimated by interpolation. Test results performed on real parts compares favorably to deformation calculations using complete data model from the point-of-view of speed and accuracy.     

Registration and interactive planar segmentation for stereo images of polyhedral scenes

We introduce a two-step iterative segmentation and registration method to find coplanar surfaces among stereo images of a polyhedral environment. The novelties of this paper are: (i) to propose a user-defined initialization easing the image matching and segmentation, (ii) to incorporate color appearance and planar projection information into a Bayesian segmentation scheme, and (iii) to add consistency to the projective transformations related to the polyhedral structure of the scenes. The method utilizes an assisted Bayesian color segmentation scheme. The initial user-assisted segmentation is used to define search regions for planar homography image registration. The two reliable methods cooperate to obtain probabilities for coplanar regions with similar color information that are used to get a new segmentation by means of quadratic Markov measure fields (QMMF). We search for the best regions by iterating both steps: registration and segmentation.     

A non-iterative and effective procedure for simultaneous odometry and camera calibration for a differential drive mobile robot based on the singular value decomposition

Differential-drive mobile robots are usually equipped with video cameras for navigation purposes. In order to ensure proper operational capabilities of such systems, several calibration steps are required to estimate the video-camera intrinsic and extrinsic parameters, the relative pose between the camera and the vehicle frame and the odometric parameters of the vehicle. In this paper, simultaneous estimation of the aforementioned quantities is achieved by a novel and effective calibration procedure. The proposed calibration procedure needs only a proper set of landmarks, on-board measurements given by the wheels encoders, and the camera (i.e., a number of properly taken camera snapshots of the set of landmarks). A major advantage of the proposed technique is that the robot is not required to follow a specific path: the vehicle is asked to roughly move around the landmarks and acquire at least three snapshots at some approximatively known configurations. Moreover, since the whole calibration procedure does not use external measurement devices, it can be used to calibrate, on-site, a team of mobile robots with respect to the same inertial frame, given by the position of the landmarks’ tool. Finally, the proposed algorithm is systematic and does not require any iterative step. Numerical simulations and experimental results, obtained by using a mobile robot Khepera III equipped with a low-cost camera, confirm the effectiveness of the proposed technique.     

Improving Head Movement Tolerance of Cross-Ratio Based Eye Trackers

When first introduced, the cross-ratio (CR) based remote eye tracking method offered many attractive features for natural human gaze-based interaction, such as simple camera setup, no user calibration, and invariance to head motion. However, due to many simplification assumptions, current CR-based methods are still sensitive to head movements. In this paper, we revisit the CR-based method and introduce two new extensions to improve the robustness of the method to head motion. The first method dynamically compensates for scale changes in the corneal reflection pattern, and the second method estimates true coplanar eye features so that the cross-ratio can be applied. We present real-time implementations of both systems, and compare the performance of these new methods using simulations and user experiments. Our results show a significant improvement in robustness to head motion and, for the user experiments in particular, an average reduction of up to 40 % in gaze estimation error was observed.     

RF MEMS switches fabrication by using SU-8 technology

In this paper we present a novel process based on SU-8 technology for the fabrication of double clamped radio frequency (RF) micro-electro-mechanical system (MEMS) capacitive shunt switches in coplanar configuration. The key element of the exploited process is the MicroChem SU-8 2002 negative photoresist. The polymeric material is widely used in MEMS device processes because of its excellent thermal and chemical stability. In this paper, SU-8 polymer has been utilized in a double way to get suspended structures as double clamped beams: (1) SU-8 for the lateral supports, and (2) as a sacrificial layer for the release of the suspended membrane. Preliminary RF tests on the manufactured switches have been done, and the measured electrical performances are in good agreement with the performed simulations.     

A dynamic fuzzy cognitive map applied to chemical process supervision

This work develops an intelligent tool based on fuzzy cognitive maps to supervisory process control. Fuzzy cognitive maps are a neuro-fuzzy methodology that can accurate model complexly system using a causal-effect fuzzy reasoning. In the proposed approach, new types of concept and relation, not restricted to cause–effect ones, are added to the model resulting in a dynamic fuzzy cognitive map (D-FCM). In this sense, a supervisory system is developed in order to control a fermentation process. This process has a non-linear behavior and presents several problems, such as non-minimum phase and large accommodation time. The supervisor goal is to operate the process in normal and critical conditions. The expert knowledge about the process behavior in both conditions is used to build the D-FCM supervisor. Simulation results are presented in order to validate the proposed intelligent supervisor.     

Room temperature ferromagnetism of Co doped TiO2 using ion implantation and defect engineering

Ferromagnetic (FM) semiconductors obtained by doping ferromagnetic elements into a nonmagnetic semiconductor matrix are essential for the second generation of spintronics devices. In this study, we investigate Co doping behavior and subsequent magnetic properties in Co implanted and thermally annealed TiO₂. In TiO₂ single crystals, a decrease in the oxygen partial pressure during thermal annealing is found to enhance the Co substitutional fraction by increasing the concentration of oxygen vacancies. Magnetic properties determined from superconducting quantum interference device magnetometer (SQUID) measurements show that TiO₂ crystals with a large fraction of substitutional Co are ferromagnetic at room temperature. In addition to single crystals, the feasibility of Co doping via ion implantation is studied in sol–gel synthesized TiO₂ thin films. Results from grazing incidence X-ray diffraction (GIXRD) show that the implantation can produce Co doped TiO₂ thin films and that the Co incorporation into Ti lattice site accompanies the transition from rutile to anatase phase. These results show that ion beam synthesis is a useful tool for producing ferromagnetic TiO₂ with a high Curie temperature (T_C).