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Voltage control in low voltage grids: A comparison between the use of distributed photovoltaic converters or centralized devices
No full textIn this paper, three solutions for the control of voltage in Low Voltage (LV) grids with high photovoltaic (PV) penetration are simulated and compared. The first solution corresponds to the use of distributed PV converters to control voltage in their connection points. In other cases, a centralized control is performed, by using a Static Var Compensator or a transformer with On Load Tap Changer installed inside the MV/LV substation. Benefits on voltage profiles and reduction of losses are shown through simulations carried out on a real grid. The consumption and PV generation profiles come from accurate measurements performed in apartment and office buildings with 1-second time step
MV ground fault current distribution: An analytical formulation of the reduction factor
No full textGlobal Earthing Systems (GESs) are defined by international standards IEC 61936-1 and EN 50522 as an equivalent Earthing System (ES) created by the interconnection of local ESs. Thanks to this interconnection, just a percentage of the total fault current is injected to ground in a single ES, reducing the risk of electrocution. However, even if several experiments and models proved this effect, the identification and official certification is already a difficult task. If dangerous scenarios caused by a single line to ground fault can be easily evaluated for a specific MV feeder by measurement or analytic models (quite cumbersome to use), operative procedures valid for all the scenarios are not still available. In this work, a simplified formula to compute the reduction factor is presented, as well as its rationale. The proposed formula is easy to use and the results provided are sufficiently accurate, taking into account a desired safety margin. For this reason, it could be a valid tool for Distributor System Operators (DSO) and Certification Bodies and a step forward for the GES identification
An integrated model of achieving social sustainability in urban context through Theory of Affordance
No full textThe concept of "Affordance" is increasingly used among urban designers because it adds theoretical clarity to the understanding of the link between the environment, human behavior, and human needs fulfillment. Affordances emerge only when the different characteristics of individuals, such as their physical dimension and abilities, social needs and personal intentions are matched with the features of the environment. However, in formalizing social sustainability, a central issue to be addressed is the relationship between people and their environment in social sustainability processes. The definition of "Affordance " of a particular urban context will provide the means to make precise the opportunities for achieving social sustainability. With reviewing the related literature, it is concluded that the multidisciplinary relations between "Human Needs " and "Social Sustainability" with the aim of "Theory of Affordance" has been out of scholar's agenda. This paper fills this gap with proposing an integrated model of fulfilling human needs in the urban context through achieving social Sustainability with the aim of cognitive affordance
Measuring the size of tubules in phloem and xylem of plants
No full textThe paper is showing how to measure, by means of the segmentation of a SEM image, the cross-sections of the tubules in phloem and xylem of plants
Partial offloading of OpenFlow rules on a traditional hardware switch ASIC
No full textOpenFlow represents a new powerful paradigm that combines the flexibility of the software with the efficiency of a programmable hardware switch. However, such an approach is currently reserved for new hardware devices, specifically engineered for this paradigm. This paper presents our experience and findings about selectively offloading OpenFlow rules into a non-OpenFlow compatible hardware switch silicon, which enables existing (legacy) hardware ASICs to become compatible with the SDN paradigm. We describe our solution that transparently offloads the portion of OpenFlow rules supported by the hardware while keeping in software the remaining ones, and that is able to support the presence of multiple hardware tables although with limited capabilities in terms of matches and actions. Moreover, we illustrate the design choices used to implement all the basic functionalities required by the OpenFlow protocol (e.g., packet-in, packet-out messages) and then we demonstrate the considerable advantage in terms of performance that can be obtained by performing switching in hardware, while maintaining an SDN-type ability to program and to instantiate desired network operations from a central controller
Osteogenic evaluation of stem cell-seeded bioactive glasses containing strontium and cobalt in a critical size defect in rabbit femur
No full textRecent upgrades of the harmonic radar for the tracking of the Asian yellow-legged hornet
No full textThe yellow-legged Asian hornet is an invasive species of wasps, indigenous of the South-East Asia but quickly spreading in Southern Europe. Because of its exponential diffusion and its serious threat to the local honey bee colonies and to humans as well, restraint measures are under investigation. Among them, the harmonic radar described in (Ecology and Evolution, 6, 2016 and 2170) already proved to be a quite effective way to follow the hornets to their nests; it is in fact capable of tracking the flying trajectory of these insects, once equipped with a small transponder, in their natural environment. The aforementioned harmonic radar was upgraded after a period of intense experimentation; the capture of the hornets was enhanced as well, and other improvements were adopted in the mounting procedure of the transponder. Thanks to these upgrades, the flying capabilities of the hornets were not reduced and a huge collection of data was recorded. The main upgrade to the radar was the adoption of the vertical polarization of the radiated field, with the consequent redesign and manufacturing of the antennas and the different mounting of the transceiver on the insect. The installation of the radar on a telescopic tower drastically improved the maneuverability of the system and the capability to follow the insects' preferential flying directions. Eventually, the system was able to produce much more continuous traces with a clear indication of the most probable position of the nest. The maximum range of detection was also increased to 150 m
THERMAL CNT - Compute thermal conductivity of single-walled carbon nano-tubes via NEMD method
No full textThis software computes thermal conductivities of single-wall carbon nano-tubes (SW-CNT) via NEMD (non-equilibrium molecular dynamics) method. Two versions of the same program are available: a tool version for fast set-up and simulations and a step-by-step tutorial for students. The procedure used to compute the conductivity is outlined in the tutorial version of the program; more details can be found in E. Chiavazzo, P. Asinari, "Enhancing surface heat transfer by carbon nanofins: towards an alternative to nanofluids?" Nanoscale Research Letters 6 (2011) 249. The numerical solution is obtained using the GROningen MAchine for Chemical Simulations (GROMACS). In this program, we use harmonic potential for the phononic thermal transfer (OPLS-AA force field)
