Software developers are expected to protect concurrent accesses to shared regions of memory with some mutual exclusion primitive that ensures atomicity properties to a sequence of program statements. This approach prevents data races but may fail to provide all necessary correctness properties.The composition of correlated atomic operations without further synchronization may cause atomicity violations. Atomic violations may be avoided by grouping the correlated atomic regions in a single larger atomic scope. Concurrent programs are particularly prone to atomicity violations when they use services provided by third party packages or modules, since the programmer may fail to identify which services are correlated. In this paper we propose to use contracts for concurrency, where the developer of a module writes a set of contract terms that specify which methods are correlated and must be executed in the same atomic scope. These contracts are then used to verify the correctness of the main program with respect to the usage of the module(s). If a contract is well defined and complete, and the main program respects it, then the program is safe from atomicity violations with respect to that module. We also propose a static analysis based methodology to verify contracts for concurrency that we applied to some real-world software packages. The bug we found in Tomcat 6.0 was immediately acknowledged and corrected by its development team.

Event-Condition-Action languages are the commonly accepted para- digm to express and model the behavior of reactive systems. While numerous Event-Condition-Action languages have been proposed in the literature, differing e.g. on the expressivity of the language and on its operational behavior, existing Event-Condition-Action languages do not generally support the action compo- nent to be formulated as a transaction. In this paper, sustaining that it is important to execute transactions in reactive languages, we propose an Event-Condition- Transaction language, based on an extension of Transaction Logic. This exten- sion, called Transaction Logic with Events (T Rev ), combines reasoning about the execution of transactions with the ability to detect complex events. An impor- tant characteristic of T Rev is that it takes a choice function as a parameter of the theory, leaving open the behavioral decisions of the logic, and thereby allowing it to be suitable for a wide-spectrum of application scenarios like Semantic Web, multi-agent systems, databases, etc. We start by showing how T Rev can be used as an Event-Condition-Action language where actions are considered as transac- tions, and how to differently instantiate this choice function to achieve different operational behaviors. Then, based on a particular operational instantiation of the logic, we present a procedure that is sound and complete w.r.t. the semantics and that is able to execute T Rev programs

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Since the ratification of the Salamanca agreement in 1994 that it is the concern of schools to seek inclusive approaches that may lead all students to academic success through differentiated strategies and adaptations or curricular and environmental

Nowadays, simulation tools are available for calculating the thermal loads of multiple rooms of buildings, for given inputs. However, due to inaccuracies or uncertainties in some of the input data (e.g., thermal properties, air infiltrations flow rates, building occupancy), the evaluated thermal load may represent no more than just an estimate of the actual thermal load of the spaces. Accordingly, in certain practical situations, simplified methods may offer a more reasonable trade-off between effort and results accuracy than advanced software. Hence, despite the advances in computing power over the last decades, simplified methods for the evaluation of thermal loads are still of great interest nowadays, for both the practicing engineer and the graduating student, since these can be readily implemented or developed in common computational-tools, like a spreadsheet.The method of Mackey and Wright (M&W) is a simplified method that upon values of the decrement factor and time lag of a wall (or roof) estimates the instantaneous rate of heat transfer through its indoor surface. It assumes cyclic behaviour and shows good accuracy when the excitation and response have matching shapes, but it involves non negligible error otherwise, for example, in the case of walls of high thermal inertia.The aim of this study is to develop a simplified procedure that considerably improves the accuracy of the M&W method, particularly for excitations that noticeably depart from the sinusoidal shape, while not introducing a need for an excessive volume of data or complexity in the production of results.In the first simplified procedure discussed in the paper, a full-featured excitation is decomposed into a Fourier series and then the wall's thermal behaviour is reconstructed from the application of the M&W method to each of the N sinusoidal components. Even though this established approach can lead to the most accurate results, given a sufficiently high N, it requires the knowledge of the decrement factor and time lag associated to each component of the Fourier series, which can represent a considerable amount of data.The chief result of the research though is a novel procedure based on a parameter, γ, that weigh-averages the approximate solution obtained by considering a single term Fourier decomposition of the excitation and the solution by considering the actual excitation. The procedure is more accurate than the original M&W method and will be of interest to researchers with the means of generating values of γ for the walls which the end users of their research are interested in. It provides promising results for walls ranging from massive to negligible mass. It has been noticed that while using the same values of γ that had been optimized for the wall facing east, acceptable results are also obtained when altered external excitations are imposed, namely due to intermittency of the direct solar radiation or due to a distinct value of the external heat transfer coefficient. © 2015 Elsevier Ltd.

Abstract Probabilistic fatigue models are required to account conveniently for several sources of uncertainty arising in the prediction procedures for structural details, such as the scatter in material behaviour. In this paper, a procedure to derive probabilistic S-N fields for structural details [1] is applied to a notched geometry with elliptic central hole made of puddle iron from the Eiffel bridge, based on the local approaches supported by the probabilistic ɛa–N or Smith–Watson–Topper (SWT)–N fields [1,2]. This procedure suggests an extension of the fatigue crack propagation model proposed by Noroozi et al. [3,4] to structural details, in order to cover both the fatigue crack initiation and fatigue crack propagation, based on local strain approaches to fatigue. Both fatigue crack initiation and fatigue crack propagation mechanisms are accounted for in the proposed approach. The numerical results are compared with available experimental S-N fatigue data for the notched plate under consideration.

The wind energy production is a growing industry and the energy produced is renewable and environmentally cleaner than most of the energy production systems. The supports of the wind energy generators may be built with precast concrete elements. The precast solutions for these structures are competitive in comparison to other structural systems. The evolution of the technology for wind energy production shows a clear need for larger wind turbines and longer blades and, consequently, taller towers. The experience also shows that precast concrete solutions increase their competitiveness as the tower height increases. Offshore wind farms have some advantages in relation to onshore ones, which explains recent investments in this area. Also in this case, the durability of concrete in the sea when compared to steel, gives advantages to precast concrete in relation to other structural solutions. This paper shows the evolution of the supports of the wind energy generators and the advantages of the use of precast concrete towers.

This paper presents a remote laboratory linked with mobile devices for real data analysis on the field of power quality. A global system was developed from the power quality analyzer into the human machine interface devoted to the m-learning system. This m-learning system is intended to be used in a long life learning perspective. The developed remote laboratory is a good opportunity for people, even without deep knowledge on the field, to learn power quality principles in an applied way. Since the system is based on real data, is a good approach to give trainees practical knowledge on the field.

The improved characteristics of Tunnel FETs (TFETs) like steep sub-threshold swing and low off-currents make them an attractive choice for low power operations compared to MOSFETs and Multi-gate FETs like FINFETs. Such characteristics are favorable to digital design, but the drain current saturation in their output characteristics can also benefit the analog design. In this paper, it is shown by simulations that analog characteristics as voltage gain, power consumption and bandwidth are improved using TFETs compared to their counterparts, at a sub-22 nm technology node and 0.8 V supply voltage.