Comparison of two sealing coupling geometries for a direct fuel injector

The present paper describes some Finite Elements simulations carried out in order to investigate the contact problem in the sealing region of a direct fuel injector. In particular two different design solutions have been analyzed, both patent pending, one characterized by a conformal contact of two conic surfaces and the other one by a non-conformal contact between a cone and a sphere. Pressure distribution, contact width and von Mises equivalent stress have been calculated and employed as comparison parameters. Two different loading conditions have been considered: nominal loads and nominal loads plus undesired effects. Also deviations from the nominal geometry, obtained from profile detection of 40 samples, have been introduced for considering a real-like case. Numerical results stress the robustness of the non-conformal solution with respect to geometrical tolerances and real loading conditions.     

Shoot cuttings propagation of giant reed (Arundo donax L.) in water and moist soil: The path forward?

Giant reed (Arundo donax L.) is a perennial rhizomatous grass that can be regarded as an ideal crop for bioenergy production, owing to several intrinsic characteristics. Despite to the promising yield results obtained in many plot experiments, the cultivation of giant reed at field scale is still a challenge. Owing to the floral sterility of the species, rhizome propagation has been predominantly used to establish field plots experiments, although this method is unpractical and monetarily expensive. Giant reed is a hydrophytic plant that typically spread in riparian systems by flood-mediated fragmentation and dispersal of vegetative propagules. Since giant reed propagation is strictly dependent on temporary abundance of water, this plant characteristic might be exploited for fostering the diffusion of giant reed as a bioenergy field crop. The objectives of this paper were: i) to disseminate some techniques for shoot cutting propagation of giant reed in water and in moist soil; ii) to address the critical points that remain to be solved for a widespread diffusion of this species as a bioenergy field crop.     

A Framework for Engineering Interactions in Java-based Component Systems

This paper describes a Java-based framework for the development of component-based software systems supporting the specification of the logic of component interactions as a first-class aspect. Java is used as the reference development language.On the one side, the framework makes it possible to specify the logic of interaction at the component-level, in terms of input and output interfaces, the events generated and observed by a component, and related information about the management of the control flow. On the other side, it is possible to specify the logic of interaction at the inter-component level, providing a modelling and linguistic support for designing and (dynamically) programming the glue among the components, enabling general forms of observation, control and construction of the interaction space.As a result, the framework supports the coordination of components at different levels: from interoperability among heterogeneous and unknown components, to the support for dynamic introduction, removal and update of components, to general coordination patterns, such as workflow. The framework adopts first-order logic as the reference computational model for describing and defining the logic of interaction: the modalities adopted by components to interact, the coordination laws gluing the components and the interaction events occurring in the system are expressed as facts and rules. They compose the (evolving) logic theories describing and defining the interaction at the system level, and can be observed and controlled at runtime to allow dynamic re-configurability.     

Characterization of the loss allocation techniques for radial systems with distributed generation

In the restructured electricity industry, meaningful loss allocation methods are required in order to send correct signals to the market taking into account the location and characteristics of loads and generations, including the local sources forming the distributed generation (DG). This paper addresses the issues related to loss allocation in radial distribution systems with DG, with a three-fold focus. First, the key differences in the formulation of the loss allocation problem for radial distribution systems with respect to transmission systems are discussed, specifying the modeling and computational issues concerning the treatment of the slack node in radial distribution systems. Then, the characteristics of derivative-based and circuit-based loss allocation techniques are presented and compared, illustrating the arrangements used for adapting the various techniques to be applied to radial distribution systems with DG. Finally, the effects of introducing voltage-controllable local generation on the calculation of the loss allocation coefficients are discussed, proposing the adoption of a “reduced” representation of the system capable of taking into proper account the characteristics of the nodes containing voltage-controllable DG units. Numerical results are provided to show the time evolution of the loss allocation coefficients for distribution systems with variable load and local generation patterns.     

Reliable and efficient forwarding in ad hoc networks

This paper focuses on packet forwarding in ad hoc networks and proposes a new approach to improve performance of nodes communication. In particular, we present a lightweight mechanism for REliable and Efficient Forwarding (REEF), which mitigates the effects of adverse situations caused by cooperation misbehavior or network fault conditions. It exploits nodes’ local knowledge to estimates route reliability, and multi-path routing to forward packets on the most reliable route. REEF becomes also a security mechanism in case of a security association established between the communication parties. This additional feature makes the mechanism robust, guaranteeing trustworthiness of the reliability estimator and security of data transmission.A new approach to cooperation enforcing is also proposed. The classical method denies service to misbehaving nodes by, for example, not serving their forwarding requests. We approach the problem less drastically, differentiating the quality of service provided to nodes according to their behavior. In other words, traffic of misbehaving nodes will flow through the network slower than that one of reliable nodes.     

Ettringite and calcium sulfoaluminate cement: investigation of water content by near-infrared spectroscopy

Calcium sulfoaluminate (CSA) cement is a sulfate-based binder whose high-performance hydraulic behavior depends on the rapid formation of ettringite, when grinded clinker is hydrated in presence of gypsum. Ettringite is a calcium aluminum sulfate mineral characterized by high water content, estimated as 32 water molecules per formula unit. Three examples of utilization of near-infrared (NIR) spectroscopy are here shown. First of all, information on water distribution in pure ettringite was deduced and compared with infrared analyses. Then its thermal behavior has been followed up to 400 °C, allowing to improve the knowledge about water loss and thermal decomposition of this hydrated phase. Finally, the obtained results have been employed in order to follow hydration of CSA cement sample, demonstrating thus that NIR spectroscopy, being highly sensitive to water amount and distribution, can be an extremely useful tool for hydration studies.     

The PTB primary standard for electrical AC power

The present PTB primary standard allows power measurements with a measurement uncertainty of about 2.5 μW / VA (k = 2). It operates at voltages up to 240 V and currents up to 10 A in the frequency range from 16 Hz up to some kHz. This paper gives a short overview of the working principle of the standard and recent improvements.     

Synthesis and Structural Characterization of Trimetallic Perovskite-Type Rare-Earth Orthoferrites, LaxSm1–xFeO3

Ultrafine powders of trimetallic orthoferrites containing lanthanum and samarium in various ratios were synthesized by thermal decomposition at low temperatures of the corresponding hexacyano complexes to modulate the functional properties of these perovskite-type oxides. The precursors and their decomposition products were analyzed by simultaneous thermogravimetric and differential thermal analyses, X-ray diffractometry, and Raman spectroscopy. Single-phase trimetallic precursors and oxides were obtained. The crystal structure of the perovskite-type oxides was orthorhombic, and the lattice parameters were affected by the ionic size of the rare-earth elements present in the oxides. Raman spectra showed a broadening of the vibrational bands with increased lanthanum content. This was ascribed to some disorder in the oxygen sublattice, related to distortions of the cation–oxygen coordination, and to a reduction of the orthorhombic distortion in the unit-cell basal plane. Most of the Raman modes above 200 cm⁻¹, associated with the vibration of oxygen ions, showed a frequency increase with effective cation mass, defined as m _eff= xm _La+ (1 – x ) m _Sm, i.e., with samarium content. This was explained by assuming that the force constants increased with decreased Ln–O and Fe–O interatomic distances observed for high samarium content.