Abstract An invisible layer of knowledge is progressively growing with the emergence of situated visualizations and reality-based information retrieval systems. In essence, digital content will overlap with real-world entities, eventually providing insights into the surrounding environment and useful information for the user. The implementation of such a vision may appear close, but many subtle details separate us from its fulfillment. This kind of implementation, as the overlap between rendered virtual annotations and the camera’s real-world view, requires different computer vision paradigms for object recognition and tracking which often require high computing power and large-scale datasets of images. Nevertheless, these resources are not always available, and in some specific domains, the lack of an appropriate reference dataset could be disruptive for a considered task. In this particular scenario, we here consider the problem of wine recognition to support an augmented reading of their labels. In fact, images of wine bottle labels may not be available as wineries periodically change their designs, product information regulations may vary, and specific bottles may be rare, making the label recognition process hard or even impossible. In this work, we present augmented wine recognition, an augmented reality system that exploits optical character recognition paradigms to interpret and exploit the text within a wine label, without requiring any reference image. Our experiments show that such a framework can overcome the limitations posed by image retrieval-based systems while exhibiting a comparable performance.

Since the beginning of the 2010 decade, many improvements have been made in terms of Virtual Reality (VR) hardware technologies and software platforms. Such trend is expected to continue, pushing the penetration rate of VR headsets. In the meantime, two research questions emerge: (a) how 3D-based immersive environments may get to be used, and with which benefits, in place of 2D ones, and, (b) how to support such integration. We focus on the latter, taking as a case study SUMO, a well-known PC-based vehicular traffic simulation tool. To this aim, we adopt an approach based on the OpenGL intercept technique, with the implementation of the OGL2VR middleware, which has been extended to remove graphical artifacts and to include the on/off toggling of dynamic elements in a 3D scene. We here describe the solutions that have been embraced, as well as the challenges that still remain along this path, to render dynamic traffic animations in an immersive setting to support the use of a blended 2D/3D environment.

Virtual reality is slowly transitioning from a specialized laboratory-only technology, to a consumer electronics appliance. In this transition, two interesting research questions amount to how 2D-based content and applications may benefit (or be hurt) by the adoption of 3D-based immersive environments and to how to proficiently support such integration. Acknowledging the relevance of the former, we here consider the latter question, focusing our attention on the diversified family of PC-based simulation tools and platforms. VR-based visualization is, in fact, widely understood and appreciated in the simulation arena, but mainly confined to high performance computing laboratories. Our contribution here aims at characterizing the simulation tools which could benefit from immersive interfaces, along with a general framework and a preliminary implementation which may be put to good use to support their transition from uniquely 2D to blended 2D/3D environments.

In this paper we propose a theoretical model, which may be put to good use to analyze the energy consumption of a smartphone where a random number of different applications are assumed to run, for random intervals of time, consuming the available energy resources. The problem is formulated in terms of the following mobile application(s) parameters, namely: (i) the maximum possible running time, (ii) the average amount of energy consumed per time unit while running, (iii) the average number of apps that are employed during a given smartphone's usage. The model is solved in terms of the probability distribution function of the energy consumed on a given smartphone. The proposed model is then validated by simulation means, in order to prove its applicability in quantifying the amount of energy consumed.

The relationships between fashion and technology are, year by year, increasing in number and depth. Information and communication technologies (ICT) do not have an influence, in fact, only on the manufacturing processes behind the production of clothes and accessories, but nowadays have implications on the end products as well as on their advertisement. This is witnessed by the plethora of designers that are today considering the use of consumer electronics in their creations and by the number of fashion brands that are exploring non conventional communication strategies including the use of ICT platforms. On the other hand, also consumers have changed their habits and ways of approaching products: consider, as a relevant example, the large share of users that today buy fashion online rather than in a brick and mortar shop. Now, what is by many considered the fourth wave of consumer electronics, i.e., the advent of Virtual and Augmented Reality, may have important implications on such relationships, setting new paths for product discovery and brand communication. In this scenario, we here experiment with gamification and Virtual Reality, showing the result of presenting a fashion game to an audience of fashion experts. Our results confirm the promising opportunities that the use of such technologies may provide to such creative and commercial domain.

In this paper we propose event goodput, i.e., the fraction of events which may be successfully managed by a system, as a relevant metric to describe the performance of battery powered real-time sensor networks. Unlike other performance metrics as response, completion, maximum lateness times, all representing fundamental, but different, figures of merit for the description of the behavior of real-time systems, event goodput provides an immediate and a direct relation with the events which may be satisfactorily managed (or not) by a real-time application. We will show such metric well serves the purpose of describing the performance of battery powered, random event-driven networks, such as sensor networks deployed for surveillance and intrusion detection applications, operating in time critical scenarios. In essence, such real-time systems may be assessed in terms of the fraction of events which they successfully/unsuccessfully detect and report within a time interval of interest. The importance of such metric is here demonstrated providing a simulation model and results where the use of the event goodput metric is discussed in conjunction with those metrics which are traditionally utilized for the assessment of a real-time sensor networks.

The usage of sensors is emerging in the nowadays scenario where safety related applications are more and more used. These applications have timing constraints that need to be met by the control system. Thus, guaranteeing timeliness properties is considered a key challenge for research on wireless sensor networks. Among the different components that need to address this problem, we focus on the communication subsystem and, in particular, on the MAC protocols that handles transmissions. To provide timeliness behavior, the employed MAC protocol has to provide a time-bounded service. The contribution of this paper is to investigate the performance of two wireless MAC protocols that can be employed in wireless sensor networks: IEEE 802.11e and WRT-Ring. The former is part of the well know IEEE 802.11 standard, whereas the latter has characteristics that well fit the requirements of wireless sensor networks. Results show that two protocols have similar performances for networks with limited devices and/or traffic, whereas when devices and/or traffic increases, WRT-Ring has to be preferred.

This paper illustrates the effects of the Hyper- Threading processor technology on the runtime performance of a parallel and distributed simulation middleware. A preliminary analysis of the middleware design and execution parameters is given to identify the tuning parameters and to evaluate the scalability of parallel simulation. A real testbed scenario has been illustrated, based on the ART'S parallel and distributed simulation middleware. The experimental analysis has provided some interesting guidelines about the way to adapt the parallel and distributed simulation middleware to Hyper-Threading and to increase the execution speed of the simulation.

The distributed and the Grid Computing architectures for the simulation of massively populated wireless systems have recently been considered of interest, mainly for cost reasons. Solutions for generalized proximity detection for mobile objects is a relevant problem, with a big impact on the design and the implementation of parallel and distributed simulations of wireless mobile systems. In this paper, a set of solutions based on tailored data structures, new techniques and enhancements of the existing algorithms for generalized proximity detection are proposed and analyzed, to increase the efficiency of distributed simulations. The paper includes the analysis of computation complexity of the proposed solutions and the performance evaluation of a testbed distributed simulation of ad hoc network models. Recent works have shown that the performance of distributed simulation of dynamic complex systems could benefit from a runtime migration mechanism of model entities, which reduces the communication overheads. Such migration mechanisms may interfere with the generalized proximity detection implementations. The analysis performed in this paper illustrates the effects of many possible compositions of the proposed solutions, in a real testbed simulation framework.

In this work we define and test a new framework obtained as the integration of two recently developed middlewares defined to support the parallel and distributed simulation of large scale, complex and dynamically interacting system models (like wireless and mobile network systems). In a distributed simulation of highly interacting system models, the main bottleneck may become the communication and synchronization required to maintain the causality constrains between distributed model components. We designed and implemented the ARTÌS middleware as a new framework incorporating a set of features that allow an adaptive optimization of the communication layer management in a distributed simulation scenario. ARTÌS has been integrated with GAIA, a dynamic mechanism for the runtime management and adaptive allocation of model entities in a distributed simulation. By adopting a runtime evaluation of causal bindings between model entities GAIA adapts the dynamic and time-persistent causal effects of model interactions to dynamic migration of model entities. Preliminary results demonstrate that the combined effect of ARTÌS management and GAIA heuristics leads to a significant reduction in the communication and synchronization overheads between the physical execution units. Simulation performance enhancements have been obtained also in worst-case modelling assumptions and simulation scenarios.

The simulation of ad hoc and sensor networks often requires a large amount of computation, memory and time to obtain significant results. The parallel and distributed simulation approach can be a valuable solution to reduce the computation time, and to support model components' modularity and reuse. In this work we perform a testbed evaluation of a new middleware for the simulation of large scale wireless systems. The proposed middleware has been designed to adapt and to scale over a heterogeneous distributed execution infrastructure. To realize a testbed evaluation of the considered framework we implemented and investigated a set of wireless systems' models. Specifically, we identified two classes of widely investigated wireless models: mobile ad hoc, and static sensor networks. In this work we present the performances of the simulation framework, with respect to the heterogeneous set of execution architectures, and the modeled systems' characteristics. Results demonstrate that the framework leads to increased model scalability and speed-up, by transparently adapting and managing at runtime the communication and synchronization overheads, and the load balancing.

Software components can give rise to several kinds of architectural mismatches when assembled together in order to form a software system. A formal description of the architecture of the resulting component-based software system may help to detect such architectural mismatches and to single out the components that cause the mismatches. In this article, we concentrate on deadlock-related architectural mismatches arising from three different causes that we identify: incompatibility between two components due to a single interaction, incompatibility between two components due to the combination of several interactions, and lack of interoperability among a set of components forming a cyclic topology. We develop a process algebra-based architectural description language called PADL, which deals with all three causes through an architectural compatibility check and an architectural interoperability check relying on standard observational equivalences. The adequacy of the architectural compatibility check is assessed on a compressing proxy system, while the adequacy of the architectural interoperability check is assessed on a cruise control system. We then address the issue of scaling the architectural compatibility and interoperability checks to architectural styles through an extension of PADL. The formalization of an architectural style is complicated by the presence of two degrees of freedom within the set of instances of the style: variability of the internal behavior of the components and variability of the topology formed by the components. As a first step towards the solution of the problem, we propose an intermediate abstraction called architectural type, whose instances differ only for the internal behavior of their components. We define an efficient architectural conformity check based on a standard observational equivalence to verify whether an architecture is an instance of an architectural type. We show that all the architectures conforming to the same architectural type possess the same compatibility and interoperability properties.

Formalizing the description of software systems helps to detect the presence of architectural mismatches that can arise when assembling software components together. The authors identify three causes of architectural mismatches: incompatibility between two components due to a single interaction, incompatibility between two components due to the combination of several interactions, and lack of interoperability among a set of components forming a cyclic topology. We then show how to deal with all of them within a uniform, process algebraic framework. We begin with the first two causes by strengthening a previously defined architectural compatibility check based on observational equivalences, in order to achieve a deadlock freedom result for the set of components interacting via a certain connection. We subsequently concentrate on the third cause by defining a novel architectural interoperability check based on observational equivalences, which guarantees absence of deadlock within a set of interacting components forming a cyclic topology. We finally assess the adequacy of our architectural interoperability check by applying it to the description of a cruise control system.

Architectural styles play an important role in software engineering as they convey codified principles and experience which help the construction of software systems with high levels of efficiency and confidence. We address the problem of formalizing and analyzing architectural styles in an operational setting by introducing the intermediate abstraction of architectural type. We develop the concept of architectural type in a process algebraic framework because of its modeling adequacy and the availability of means, such as Milner's weak bisimulation equivalence, which allow us to reason compositionally and efficiently about the well formedness of architectural types.

Systems of heterogeneous parallel processing are studied such as arising in parallel programs executed on distributed systems. A lower and an upper bound model are suggested to obtain secure lower and upper bounds on the performance of these systems. The bounding models are solved by using a matrix-geometric algorithmic approach. Formal proofs of the bounds are provided along with error bounds on the accuracy of the bounds. These error bounds in turn are reduced to simple computational expressions. Numerical results are included. The results are of interest for application to arbitrary fork-join models with parallel heterogeneous processors and synchronization.

The probability distribution of the overhead caused by the use of the checkpointing rollback recovery technique is evaluated in both cases of a single critical task and of an overall transaction-oriented system. This distribution is obtained in Laplace-Stieltjes transform form, from which all the moments can be easily calculated. Alternatively, inversion methods can be used to evaluate the distribution. The authors propose checkpointing strategies based on the above distribution in order to optimize performance criteria motivated, in the case of critical tasks, by real time constraints, and in the case of transaction-oriented systems, by the need of guaranteeing the users about the maximum system unavailability.>

Fault-tolerant computer systems may be evaluated by calculating their cumulative performance (e.g., number of processes jobs) over a finite mission time. A method for calculating the cumulative performance distribution assuming that the system fault-repair behavior can be modeled by a homogeneous Markov process is described. The method proposed for calculating the probability distribution of the accumulated reward over a finite mission is applicable to models of repairable and nonrepairable systems. The related solution algorithm shows a low polynomial computational complexity. The mathematical model is introduced, and the results already presented in the literature are surveyed. A comprehensive analysis of the time and space complexity of the proposed solution algorithm is presented. A numerical example is given.>

Today's concomitant needs for higher computing power and reliability has increased the relevance of multiple-processor fault-tolerant systems. Multiple functional units improve the raw performance (throughput, response time, etc.) of the system, and, as units fail, the system may continue to function albeit with degraded performance. Such systems and other fault-tolerant systems are not adequately characterized by separate performance and reliability measures. A composite measure for the performance and reliability of a fault-tolerant system observed over a finite mission time is analyzed. A Markov chain model is used for system state-space representation, and transient analysis is performed to obtain closed-form solutions for the density and moments of the composite measure. Only failures that cannot be repaired until the end of the mission are modeled. The time spent in a specific system configuration is assumed to be large enough to permit the use of a hierarchical model and static measures to quantify the performance of the system in individual configurations. For a multiple-processor system, where performance measures are usually associated with and aggregated over many jobs, this is tantamount to assuming that the time to process a job is much smaller than the time between failures. An extension of the results to general acyclic Markov chain models is included.

Performability, a composite measure for the performance and reliability, may be interpreted as the probability density function of the aggregate reward obtained from a system during its mission time. For large mission times we show that known limit theorems lead to an asymptotic normal distribution for the aggregate reward. For finite mission times and Markovian models we obtain the expressions for all moments of performability and give recursions to compute coefficients involved in the expressions. We illustrate the use of the results through an example of a multiple processor computer system.