Intra-Domain Pathlet Routing

Internal routing inside an ISP network is the foundation for lots of services that generate revenue from the ISP's customers. A fine-grained control of paths taken by network traffic once it enters the ISP's network is therefore a crucial means to achieve a top-quality offer and, equally important, to enforce SLAs. Many widespread network technologies and approaches (most notably, MPLS) offer limited (e.g., with RSVP-TE), tricky (e.g., with OSPF metrics), or no control on internal routing paths. On the other hand, recent advances in the research community are a good starting point to address this shortcoming, but miss elements that would enable their applicability in an ISP's network. We extend pathlet routing by introducing a new control plane for internal routing that has the following qualities: it is designed to operate in the internal network of an ISP; it enables fine-grained management of network paths with suitable configuration primitives; it is scalable because routing changes are only propagated to the network portion that is affected by the changes; it supports independent configuration of specific network portions without the need to know the configuration of the whole network; it is robust thanks to the adoption of multipath routing; it supports the enforcement of QoS levels; it is independent of the specific data plane used in the ISP's network; it can be incrementally deployed and it can nicely coexist with other control planes. Besides formally introducing the algorithms and messages of our control plane, we propose an experimental validation in the simulation framework OMNeT++ that we use to assess the effectiveness and scalability of our approach.Comment: 13 figures, 1 tabl

Hyperuniformity in amorphous speckle patterns

Hyperuniform structures possess the ability to confine and drive light, although their fabrication is extremely challenging. Here we demonstrate that speckle patters obtained by a superposition of randomly arranged sources of Bessel beams can be used to generate hyperunifrom scalar fields. By exploiting laser light tailored with a spatial filter, we experimentally produce (without requiring any computational power) a speckle pattern possessing maxima at locations corresponding to a hyperuniform distribution. By properly filtering out intensity fluctuation from the same speckle pattern, it is possible to retrieve an intensity profile satisfying the hyperuniformity requirements. Our findings are supported by extensive numerical simulations.Comment: 13 pages, 7 figure

Effects of Oil Warm up Acceleration on the Fuel Consumption of Reciprocating Internal Combustion Engines

Abstract The homologation cycle of vehicles for private passenger transportation or for light duty applications considers a cold start from ambient temperature. The most part of harmful substances (≈ 60-65%) are produced during the thermal engine stabilization which occurs in the very of the driving cycle. This strongly influences also engine efficiency, i.e. fuel consumption. The more recent commitments on CO2, therefore, reinforce the concept of reducing warm up time encountering it in the low carbon engine technologies. Due to this importance, engine thermal management has been the subject of a huge interest opening the way to new components, technologies and control strategies. This regards not only the coolant fluid, which undoubtedly influences engine warm up, but also the lubricant:an its heating acceleration produces much faster benefits.. The purpose of this paper is to assess the effect of a faster oil heating during the homologation cycle on the fuel consumption. An experimental campaign has been done on an 3L Iveco F1C engine mounted on a dynamometer test bench operated in order to reproduce the NEDC. The engine OEM has been characterized and the effect of the oil temperature has been studied according to: (a) an external heat source which brings the oil at its stabilized temperature value before engine start, (b) an internal heat source represented by the exhaust gases which almost immediately reach a temperature value able to heat-up the oil. The effects on CO2 emissions during the cycle have been evaluated. The benefits are noteworthy and justify some oil circuit modifications

charge air subcooling in a diesel engine via refrigeration unit effects on the turbocharger equilibrium

Abstract The stringent regulations on fuel saving and emissions reduction in the transportation sector have become game-raisers in the development of present internal combustion engines for road applications, even if under-the-hood space constraints, downsizing and down-weighting prevent from adopting radical changes in the engine layout. Charge air cooling is the standard in present turbocharged diesel engines, to the point that a dedicated heat exchanger, fed by environmental air, is located downstream the compressor. The paper proves the option of an additional cooling through the cabin-heating unit - usually over-sized with respect to normal operation - very effective to increase charge air density and improve cylinder filling. The intercooler downstream the compressor would be provided with a lower thermal load, hence calling for smaller heat exchange surfaces, leading to reduced weight, space saving and no increased layout complexity. By pushing this idea forward, a properly sized cabin-heating unit could even supply enough air cooling to replace the intercooler instead of just assisting it, further raising the weight/space/layout advantages. In presence of an additional heat exchanger, the cooling efficiency would be no longer related to the vehicle speed and the benefit in terms of cylinder filling could be kept to the desired value on a wider operating range for the engine. Plus, the lower combustion temperatures associated with both a colder air and a more diluted charge approaching the chamber would also result in a more regular combustion process, in spite of a moderate penalty on the thermodynamic efficiency. The additional fuel consumption to compress the cooling fluid is always offset by the fuel saving with respect to normal operation and a beneficial effect is appreciated on emissions. Nonetheless, major variables to account for when evaluating the feasibility of such a layout are (i) the impact it has on the equilibrium of the turbocharger, i.e. on the efficiency at each operating point, (ii) to what extent the presence of a colder air affects the turbine/compressor matching and (iii) the rack position the ECU fixes at the VGT, to face both pressure losses at the additional evaporator and the different enthalpy content for both the air at the compressor outlet and the exhaust gases at the turbine inlet. A comprehensive experimental activity supported by a detailed 1D model of the engine unit, aimed at assessing the benefits of the air under-cooling, allowed to select the most appropriate cooling layout and, once validated based on the experimental evidence, to investigate the equilibrium at the turbocharger

Schematic Representation of Large Biconnected Graphs

Suppose that a biconnected graph is given, consisting of a large component plus several other smaller components, each separated from the main component by a separation pair. We investigate the existence and the computation time of schematic representations of the structure of such a graph where the main component is drawn as a disk, the vertices that take part in separation pairs are points on the boundary of the disk, and the small components are placed outside the disk and are represented as non-intersecting lunes connecting their separation~pairs. We consider several drawing conventions for such schematic representations, according to different ways to account for the size of the small components. We map the problem of testing for the existence of such representations to the one of testing for the existence of suitably constrained $1$-page book-embeddings and propose several polynomial-time and pseudo-polynomial-time algorithms.Comment: Appears in the Proceedings of the 28th International Symposium on Graph Drawing and Network Visualization (GD 2020

Attitudes toward “Non-Traditional” Mothers: Examining the Antecedents of Mothers’ Competence Perceptions

Mothers are the protagonists in a widespread narrative that emphasizes motherhood as prolonged and exclusive attention to children, accompanied by references to natural competence in child-rearing skills. The present research aimed to investigate the linking mechanisms and conditional processes underlying the perception of mothers’ competence. Cisgender heterosexual Italian participants (N = 230) read one of four vignettes describing a situation in which a mother (i.e., heterosexual biological mother, heterosexual stepmothers, lesbian stepmother, and lesbian biological mother) interacts with her two children who had misbehaved. After reading the vignette, the participants rated the depicted mother’s competence and to what extent the children’s misbehaviour was attributable to the mother. Moderated-mediation analyses indicated that all the non-traditional mothers were perceived as being less competent compared to the heterosexual biological mother, by giving them greater responsibility for their children’s misbehaviour, among participants with medium–high levels of traditional gender-role beliefs. Sexual orientation and biology relatedness were not cumulative variables, but intersecting categories creating a unique way to perceive mothers. As the number of non-traditional families grows, negative societal attitudes toward non-traditional parents and their children should be increasingly considered

Computational Complexity of Traffic Hijacking under BGP and S-BGP

Harmful Internet hijacking incidents put in evidence how fragile the Border Gateway Protocol (BGP) is, which is used to exchange routing information between Autonomous Systems (ASes). As proved by recent research contributions, even S-BGP, the secure variant of BGP that is being deployed, is not fully able to blunt traffic attraction attacks. Given a traffic flow between two ASes, we study how difficult it is for a malicious AS to devise a strategy for hijacking or intercepting that flow. We show that this problem marks a sharp difference between BGP and S-BGP. Namely, while it is solvable, under reasonable assumptions, in polynomial time for the type of attacks that are usually performed in BGP, it is NP-hard for S-BGP. Our study has several by-products. E.g., we solve a problem left open in the literature, stating when performing a hijacking in S-BGP is equivalent to performing an interception.Comment: 17 pages with 6 figure

Upper bounds for the error in some interpolation and extrapolation designs

This paper deals with probabilistic upper bounds for the error in functional estimation defined on some interpolation and extrapolation designs, when the function to estimate is supposed to be analytic. The error pertaining to the estimate may depend on various factors: the frequency of observations on the knots, the position and number of the knots, and also on the error committed when approximating the function through its Taylor expansion. When the number of observations is fixed, then all these parameters are determined by the choice of the design and by the choice estimator of the unknown function. The scope of the paper is therefore to determine a rule for the minimal number of observation required to achieve an upper bound of the error on the estimate with a given maximal probability