Intentional Islanding of Active Distribution Networks by GenSets: An Analysis of Technical Constraints and Opportunities

The willingness to improve the security and reliability of power supply to end-users, often pushed by prescriptions of national regulatory authorities, is bringing considerable challenges for distribution system operators. Islanding a portion of the public distribution network after a fault is considered a measure to mitigate the effects of service interruptions. This procedure is usually carried out by counterfeeding the grid through a generator set (GenSet). Even if this approach is widely adopted around the world, reenergizing the grid and keeping the electric island stable is not a trivial task. In this framework, the scope of this paper is to provide a set of technical guidelines for the usage of GenSets to supply public grids in emergency conditions. The goal is to highlight the static and dynamic limits of the GenSet operations and simplify their exploitation for the grid operators. The numerical analyses, which have been carried out through the RMS simulation tool of the DigSilent PowerFactory software, also aim to evaluate the technical constraints in the case of active networks, which involve distributed generation implementing regulations according to ENTSO-E and Italian technical standards

Flood impacts on a water distribution network

Floods cause damage to people, buildings and infrastructures. Water distribution systems are particularly exposed, since water treatment plants are often located next to the rivers. Failure of the system leads to both direct losses, for instance damage to equipment and pipework contamination, and indirect impact, since it may lead to service disruption and thus affect populations far from the event through the functional dependencies of the network. In this work, we present an analysis of direct and indirect damages on a drinking water supply system, considering the hazard of riverine flooding as well as the exposure and vulnerability of active system components. The method is based on interweaving, through a semi-automated GIS procedure, a flood model and an EPANET-based pipe network model with a pressure-driven demand approach, which is needed when modelling water distribution networks in highly off-design conditions. Impact measures are defined and estimated so as to quantify service outage and potential pipe contamination. The method is applied to the water supply system of the city of Florence, Italy, serving approximately 380 000 inhabitants. The evaluation of flood impact on the water distribution network is carried out for different events with assigned recurrence intervals. Vulnerable elements exposed to the flood are identified and analysed in order to estimate their residual functionality and to simulate failure scenarios. Results show that in the worst failure scenario (no residual functionality of the lifting station and a 500-year flood), 420 km of pipework would require disinfection with an estimated cost of EUR 21 million, which is about 0.5 % of the direct flood losses evaluated for buildings and contents. Moreover, if flood impacts on the water distribution network are considered, the population affected by the flood is up to 3 times the population directly flooded

Spin casting characterization: An experimental approach for the definition of runners design guidelines

The present attention to production cost and time reduction has encouraged many factories to employ some non-conventional technologies instead of the conventional ones for mould production. These specific non-conventional manufacturing technologies, aimed at achieving a significant time reduction for tools manufacturing, are commonly called rapid tooling techniques. Among these rapid tooling methodologies, it is possible to find one of the most direct and flexible techniques which enables, by using a non-cured silicone, the manual shaping of a physical object obtaining directly the mould after some additional handmade refinements. In order to know how the process parameters influence the final shape of the cast object, this work develops an experimental analysis for the estimation of a preliminary model for the process characterizatio

An Affordable Upper-Limb Exoskeleton Concept for Rehabilitation Applications

In recent decades, many researchers have focused on the design and development of exoskeletons. Several strategies have been proposed to develop increasingly more efficient and biomimetic mechanisms. However, existing exoskeletons tend to be expensive and only available for a few people. This paper introduces a new gravity-balanced upper-limb exoskeleton suited for rehabilitation applications and designed with the main objective of reducing the cost of the components and materials. Regarding mechanics, the proposed design significantly reduces the motor torque requirements, because a high cost is usually associated with high-torque actuation. Regarding the electronics, we aim to exploit the microprocessor peripherals to obtain parallel and real-time execution of communication and control tasks without relying on expensive RTOSs. Regarding sensing, we avoid the use of expensive force sensors. Advanced control and rehabilitation features are implemented, and an intuitive user interface is developed. To experimentally validate the functionality of the proposed exoskeleton, a rehabilitation exercise in the form of a pick-and-place task is considered. Experimentally, peak torques are reduced by 89% for the shoulder and by 84% for the elbow

Probing H2 autoionizing states with femto and attosecond laser pulses.

ABSTRACT: We show the relevance that molecular autoionizing states display in some recent experiments related to the symmetry-breaking in molecular-frame photoelectron angular distributions in H2 when exposed to intense xuv femtosecond laser pulses, and others related to the electron (proton) localization when subject to attosecond pump-probe laser schemes. Our theoretical method solves the time-dependent Schr¨odinger equation with an spectral method that expands the wave function in terms of H2 correlated stationary vibronic states including all electronic and vibrational degrees of motion. Time-resolved asymmetric electron angular distributions are obtained at specific proton kinetic energies due to the delayed autoionization from H2 doubly excited states, which induces interferences between gerade (1s(sigma)g) and ungerade (2p(sigma)u) ionization channels. We also study photoionization of H2 exposed to a xuv attosecond pump pulse plus a time-delayed IR femtosecond probe pulse. Fast alternating asymmetries in the proton ejection (electron localization) are obtained as a function of the time delay between the pump and the probe pulses. Finally, we deal with the process of (xuv) two-photon double ionization of H2 under the assumption of having both sequential and non-sequential absorption processes

Delay discounting in Parkinson's disease: A systematic review and meta-analysis

Delay discounting refers to the depreciation of the value of a reward as a function of the time it takes to obtain it. Growing evidence shows altered delay discounting in several pathological conditions, including neurological disorders. Here, we conducted a systematic review and meta-analysis of the published literature on delay dis-counting (DD) in Parkinson's Disease (PD). We found steeper DD in patients with PD, compared to healthy controls, both in "on" and "off" dopaminergic medication. These results confirm altered DD in PD and suggest an independent influence of the dopaminergic medication and the clinical condition itself on it. Also the effect of impulse control disorder and of pharmacological treatments are analysed

The Pseudotransannular Ring Opening of 1-Aminocyclohept-4-ene-derived Epoxides in the Synthesis of Tropane Alkaloids: Total Synthesis of (±)-Ferrugine

We have optimized a synthetic approach to (±)-Ferrugine in 8 steps starting from 5-aminocyclohept-1-ene and using the Brønsted acid-catalyzed pseudotransannular ring-opening of the epoxide derived from this cycloheptene as the key step for the construction of the 8-azabicyclo[3.2.1]octane central core. While attempting the enantioselective synthesis of this natural product from enantiopure 2-hydroxy-8-azabicyclo[3.2.1]octane we have found that this compound shows a pronounced tendency to racemize via an achiral symmetric aziridinium intermediate. This racemization side process has been studied in detail using both experimental and computational methods