Fast network configuration in Software Defined Networking

Software Defined Networking (SDN) provides a framework to dynamically adjust and re-program the data plane with the use of flow rules. The realization of highly adaptive SDNs with the ability to respond to changing demands or recover after a network failure in a short period of time, hinges on efficient updates of flow rules. We model the time to deploy a set of flow rules by the update time at the bottleneck switch, and formulate the problem of selecting paths to minimize the deployment time under feasibility constraints as a mixed integer linear program (MILP). To reduce the computation time of determining flow rules, we propose efficient heuristics designed to approximate the minimum-deployment-time solution by relaxing the MILP or selecting the paths sequentially. Through extensive simulations we show that our algorithms outperform current, shortest path based solutions by reducing the total network configuration time up to 55% while having similar packet loss, in the considered scenarios. We also demonstrate that in a networked environment with a certain fraction of failed links, our algorithms are able to reduce the average time to reestablish disrupted flows by 40%

Factors affecting the impact of CAP scenarios on farm structure: an analysis based on stated intentions

Several authors have emphasised the effect of agricultural policy (such as SFP) as a driver of structural change. This paper aims to identify the determinants of the change in the use of productive factors under different policy scenarios. The analysis is performed ex ante, assessing the effect of CAP abolishment (as compared to the current CAP) on the use of productive factors, based on stated intentions by farmers. The results highlight the role of farm size, intensity and education in determining different patterns of reaction to policy changes. Also differences are identified among the three main component of structural change, land, capital and labour, with the latter being the less dependent upon the CAP

Construction and Application of Conceptual Framework as Research Tool: A Researcher’s Reflections

The importance of any study is demonstrated through the linkages made between research questions and larger theoretical concepts or policy, demonstrating how the particulars of the study serve to illuminate larger issues and, therefore, portraying the significance of the study. This theoretical concept or conceptual framework has the functions of building a foundation of the research; demonstrating how study advances knowledge; conceptualising the study; assessing the research design and instrumentation; and providing reference point for interpretation the findings. This paper outlines the author’s reflections on the building and application of a conceptual framework as a research tool.   Author’s aim is to share his experience with researchers, especially students, who may be required to apply the tool but may find difficulty developing one. Using author’s own (PhD) research topic, the paper firstly discusses the various stages that input to construct the framework and, secondly, considers how the choice of research methodology, data collection and analysis techniques are informed by the framework.   Key lesson is that a well-constructed conceptual framework has the potential of informing the choice of appropriate research methodology that in turn influences the data collection and analysis techniques, and even the research findings. This paper is expected to be of value to anyone seeking to better understand conceptual framework as a research tool, especially ‘young’ researchers who may be required to develop and apply one but may find it difficult doing so. Key Words: Conceptual framework; literature review; methodology; data collection method; data analysis metho

Network recovery from massive failures under uncertain knowledge of damages

This paper addresses progressive network recovery under uncertain knowledge of damages. We formulate the problem as a mixed integer linear programming (MILP), and show that it is NP-Hard. We propose an iterative stochastic recovery algorithm (ISR) to recover the network in a progressive manner to satisfy the critical services. At each optimization step, we make a decision to repair a part of the network and gather more information iteratively, until critical services are completely restored. Three different algorithms are used to find a feasible set and determine which node to repair, namely, 1) an iterative shortest path algorithm (ISR-SRT), 2) an approximate branch and bound (ISR-BB) and 3) an iterative multi-commodity LP relaxation (ISR-MULT). Further, we have modified the state-of-the-Art iterative split and prune (ISP) algorithm to incorporate the uncertain failures. Our results show that ISR-BB and ISR- MULT outperform the state-of-the-Art 'progressive ISP' algorithm while we can configure our choice of trade-off between the execution time, number of repairs (cost) and the demand loss. We show that our recovery algorithm, on average, can reduce the total number of repairs by a factor of about 3 with respect to ISP, while satisfying all critical deman

Assessing the effect of the CAP on farm innovation adoption. An analysis in two French regions

Literature on innovation adoption mechanism has emphasised the positive effect of Single Farm Payments (SFP) and Rural Development Payments on adoption of new technologies. In this context, the expected process of CAP reforming after 2013 is likely to strengthen the role of innovation in the European Union (EU). The objective of this paper is to identify the determinants of the adoption of future innovation, in particular in connection to past innovation, and to assess the role of agricultural policy in the promotion of innovation adoption. The analysis is applied to two regions (Centre and Midi-Pyrénées) in France. Two separate Count models are developed in order to explain famers’ stated intention concerning different intensities of innovation adoption under two different policy scenarios. Preliminary results highlight that the CAP strongly affects the decision to innovate and the innovation intensity, even if there is no statistical significance for the variable connected to the amount of payments or the level of payment per hectare

GRBs with optical afterglow and known redshift: a statistical study

We present a correlation between two intrinsic parameters of GRB optical afterglows. These are the isotropic luminosity at the maximum of the light curve (Lpeak) and the time-integrated isotropic energy (Eiso) radiated after the observed maximum. We test the correlation between the logarithms of (Eiso) and (Lpeak) and finally we value the effect of the different samples of GRBs in according with the first optical observation reduced to proper time.Comment: To be published in the proceedings of the conference "SWIFT and GRBs: Unveiling the Relativistic Universe", Venice, June 5-9, 200

REAL OPTION MODELS FOR SIMULATING DIGESTER SYSTEM ADOPTION ON LIVESTOCK FARMS IN EMILIA-ROMAGNA

Innovation and new technology adoption represent two central elements for the enterprise and industry development process in agriculture. The objective of this paper is to develop a farmhousehold model able to simulate the impacts of uncertainty in SFP, the selling price of energy and agricultural product prices parameters on the adoption of methane digester for biogas production. The model implemented is based on a real option approach that includes investment irreversibility and stochasticity in relevant parameters. The results show the relevance of uncertainty in determining the timing of adoption and emphasise the importance of predictability as a major component of policy design

Interannual variability of winter precipitation in the European Alps: relations with the North Atlantic Oscillation.

Abstract. The European Alps rely on winter precipitation for various needs in terms of hydropower and other water uses. Major European rivers originate from the Alps and depend on winter precipitation and the consequent spring snow melt for their summer base flows. Understanding the fluctuations in winter rainfall in this region is crucially important to the study of changes in hydrologic regime in river basins, as well as to the management of their water resources. Despite the recognized relevance of winter precipitation to the water resources of the Alps and surrounding regions, the magnitude and mechanistic explanation of interannual precipitation variability in the Alpine region remains unclear and poorly investigated. Here we use gridded precipitation data from the CRU TS 1.2 to study the interannual variability of winter alpine precipitation. We found that the Alps are the region with the highest interannual variability in winter precipitation in Europe. This variability cannot be explained by large scale climate patterns such as the Arctic Oscillation (AO), North Atlantic Oscillation (NAO) or the East Atlantic/West Russia (EA/WR), even though regions below and above the Alps demonstrate connections with these patterns. Significant trends were detected only in small regions located in the Eastern part of the Alps

Multi-Pulse Laser Wakefield Acceleration: A New Route to Efficient, High-Repetition-Rate Plasma Accelerators and High Flux Radiation Sources

Laser-driven plasma accelerators can generate accelerating gradients three orders of magnitude larger than radio-frequency accelerators and have achieved beam energies above 1 GeV in centimetre long stages. However, the pulse repetition rate and wall-plug efficiency of plasma accelerators is limited by the driving laser to less than approximately 1 Hz and 0.1% respectively. Here we investigate the prospects for exciting the plasma wave with trains of low-energy laser pulses rather than a single high-energy pulse. Resonantly exciting the wakefield in this way would enable the use of different technologies, such as fibre or thin-disc lasers, which are able to operate at multi-kilohertz pulse repetition rates and with wall-plug efficiencies two orders of magnitude higher than current laser systems. We outline the parameters of efficient, GeV-scale, 10-kHz plasma accelerators and show that they could drive compact X-ray sources with average photon fluxes comparable to those of third-generation light source but with significantly improved temporal resolution. Likewise FEL operation could be driven with comparable peak power but with significantly larger repetition rates than extant FELs

Egg quality from nera atriana, a local poultry breed of the Abruzzo region (Italy), and isa brown hens reared under free range conditions

The selection and diffusion in the poultry sector of hybrid breeds able to produce higher amount of meat and eggs, led over time to the erosion of genetic resources. One of the strategies that can be applied in order to stem such phenomenon, concerns the valorization of the animal products, meat or eggs, obtained from indigenous poultry breeds. Therefore, the aim of this study is to characterize the qualitative aspects of eggs obtained from the Nera Atriana hen, an Italian indigenous laying hen characteristic of the Abruzzo region, making a direct comparison with a commercial hybrid reared in the same environment and applying the same feeding protocol. The trial was conducted for a period of 5 months (from March to July 2019), in which 6 egg samplings were performed (one at the beginning and additional 5 on a monthly basis); each sampling involved the collection of 15 eggs per group of animals for a total of 90 eggs per genotype. Eggs were specifically subjected to evaluations of the physical parameters, including the yolk color, and analyses aimed at determining the content of total lipids, cholesterol, and β-carotene. In addition to this, the fatty acids profile and the electrophoretic pattern of the globular proteins of the yolk were characterized. Eggs from hybrid hens were characterized by higher total weight with significantly higher values specifically associated to albumen and yolk weight and to the albumen percentage. In the eggs obtained from the local hen, higher relative percentages were instead found in the quantity of shell and yolk; furthermore, in the same samples was observed a higher yolk redness, a cholesterol concentration tending to be lower although not significant (p = 0.0521), and a greater amount of saturated fatty acids which could justify a lower susceptibility of the food to oxidative processes following transformation with heat treatments. With regard to the fatty acid composition, differences were specifically observed for palmitic (C16:0) and palmitoleic (C16:1 cis-9) acids that showed higher relative percentages in eggs from local breed, and for the oleic acid (C18:1 cis-9) which was more represented in eggs from commercial hens. In conclusion, some interesting nutritional features, in a preliminary way, have been highlighted that could lead the consumer to prefer these “niche” products over those obtained from commercial hybrids