1,721,024 research outputs found
What are university satellite campuses for? A perspective on their contribution to Italian municipalities and regions
No full textThis paper is the first to present a long-term retrospective overview of the impact of Italian university satellite campuses (SCs), since Decree n. 509 of 1999 fostered a massive increase in the number of SCs, even in small municipalities around 10,000 residents. By drawing on a novel panel dataset aggregated at the urban level for the period 2000–20, findings show that SCs increased the number of graduates at the regional level. However, SCs alone have uneven effects on population trends and income at the urban level. They should be periodically reviewed and redesigned to address structural changes and local development
The co-evolution of ICT, skills and organization in publicadministrations: Evidence from new European country-leveldata
No full textDuring the past two decades a big effort has been made in exploring the complementar-ities between information and communications technology (ICT) adoption, investment inhuman capital and organizational change, and how these affect economic performance.Such investigations, however, remain substantially circumscribed to private sectors, whilethe role of these factors in public sector performance has been largely disregarded.In this paper we aim at filling this gap in empirical literature by combining different data-sources and constructing a panel of comparable data about output quality, input costs, ICTinvestments, skills and organizational changes in public administrations of 16 Europeancountries. We propose an index-based approach to the measurement of PA performancerelying on the adoption of public e-services as a proxy of revealed output quality, andprovide an econometric analysis of how the co-evolution of ICT, skills and organizationalfactors affects government effectiveness
About the Definition of PDIV and RPDIV in Designing Insulation Systems for Rotating Machines Controlled by Inverters
No full textThe partial discharge inception voltage (PDIV) and the repetitive partial discharge inception voltage (RPDIV) are key parameters for the characterization of the insulation system of rotating machines fed by power converters. In particular, these quantities have a fundamental role in the design and qualification of Type I insulation which has to last all life without partial discharges (PD). This paper analyzes the two definitions, taken from the IEC 60034-18-41 and IEC 60034-18-42 standards, and shows potential discrepancies which can affect significantly insulation system design, especially going from two-level inverter to sinusoidal waveforms
Life-based Geometric Design of HVDC cables. Part 1: Parametric Analysis
No full textThis study, in two parts, investigates the cable design of HVDC cables depending on life modelling of the insulating material. This paper is the first part, in which a parametric analysis is carried out, illustrating the way in which different parameters affect the lifebased feasible designs of an HVDC cable with known nominal voltage and ampacity. An
ad hoc Matlab code has been developed for this study. Results show great sensitivity of the lifetime to insulation geometry, as a slight variation in inner and outer insulation radii leads to a significant variation of cable life due mainly to the related electric field variation. The effect of temperature can be hardly observed in the life map due to the
predominant effect of electric field. Increasing the maximum conductor temperature may not necessarily extend the feasible design area, which is also limited by the maximum temperature drop across insulation thickness. The higher the applied voltage, the greater the cable dimensions. This study also emphasizes the need to keep a low enough value of
soil thermal resistivity, which considerably reduces the cable dimensions. Temperature coefficient of conductivity shows a nonlinear (mainly drastic) effect on the life. On the contrary, Field coefficient of conductivity shows a slight positive effect on the life. Part 2 of this study will investigate the effect of electrical and thermal transients on the lifebased geometric design of HVDC cables
A partial discharge-based health index for rotating machine condition evaluation
No full textIt is well known that partial discharge (PD) is a threat to electrical insulation in all electrical apparatus, but we also know that PD harmfulness, and thus damage, depends on the type of defect generating the PD. As an example, having corona PD in switchgear boxes, rather than surface PD on bushings or internal PD on cable terminations, will trigger completely different actions from maintenance managers, even if the amplitude of the first (corona PD) is much larger than those of the last (internal PD). Indeed, corona PD may not need any medium- to short-term action, surface PD can just require some careful periodic checking, and internal PD in cable joints/terminations will have to be addressed promptly
The effect of inverter characteristics on partial discharge and life behavior of wire insulation
No full textIt has been demonstrated already that adjustable speed drives, and, in general, power electronics waveforms, can harm insulation systems of rotating machines, causing significant reduction of reliability and life. Indeed, the type of supply voltage made by repetitive impulses alters significantly the electric field distribution in the turn-to-turn and phase-to-ground insulation, and also the machine terminal peak voltage can be increased significantly, with respect to the expected value at the inverter output [1]-[11]
A systematic literature review of business-to-business platforms for the digital transformation of the manufacturing industry: taking stock and advancing through research
Full text linkThis systematic literature review aims to define the state of research on digital business-to-business platforms for manufacturing (DB2BPMs), by adopting a novel interdisciplinary approach. Previous studies have addressed this topic in a “compartmentalised” way, focusing either on the technical or on the economic domain, offering limited theoretical and practical insights into these platforms when creating value for the manufacturing industry. Current research gaps also concern the role of digital B2B platforms within the digital transformation of the manufacturing industry, and the conditions, innovations, and governance models that stimulate or hamper this transformation. Eighty-two articles, published between 1999 and March 31st, 2024, were scrutinized and systematised. A conceptualization of DB2BPMs is provided, based on our results, as well as an analysis of the barriers that hamper their adoption at firm, industry, and supply chain-level. All these levels involve a variety of actors and infrastructures, which may have multiple, or evolving roles. Innovation processes that DB2BPMs can stimulate are identified, in terms of: business model adoption (especially leveraging on the opportunities offered by digital servitisation), technological advancements and capabilities, and automation of tasks. The paper suggests further research on the following key categories: actors; value creation; trust and capabilities; governance; impact; and technological innovations. A selection of policy and practical implications is proposed, that seek to guide policymakers and practitioners when navigating the complexities of DB2BPMs
Simulations of Electric Field Dynamics for DC Partial Discharge Sequences
No full textThis paper is intended to contribute to research into the interpretation of PD measurements under DC conditions. A simple PD system comprising of a cylindrical air filled void surrounded by polypropylene based copolymers is considered. A DC ramp of 1 kV/s reaching 10 kV was applied to the system and PD activity recorded from the start of the ramp for 10 4 seconds. An equivalent simulation model was constructed and used to investigate the influence of different phenomena. It was demonstrated that surface conduction is likely to play a crucial role in the applied field dynamics, leading to the cessation of PD activity. It also appears that charge deployed by PDs must be undergoing rapid recombination in order to support the high repetition rate in the first 1000 s of the experiment. The future work required to develop a full PD activity model is discussed
Preliminary Experimental Investigation of the Effect of Superimposed Switching Impulses on XLPE-insulated HVDC Cables
No full textSwitching impulses superimposed onto rated DC voltage are a particularly-challenging kind of overvoltage which is applied to HVDC cable systems both in service and during qualification tests in the laboratory. This paper aims at a preliminary experimental study of the effect of Superimposed Switching Impulses on XLPE-insulated HVDC cables. It studies the effect of aging 0.15-mm XLPE specimens by applying a sequence of Superimposed Switching Impulses, defined according
to CIGRÉ technical Brochure 496. As illustrated in this paper, only preliminary results have been obtained so far from these tests. Such results show an increase in the conductivity in the aged specimens compared to non-aged specimens. An interfacial relaxation phenomenon is also noticed at low frequencies; however, no significant dipolar polarization can be noticed under the above-mentioned aging conditions
Measuring partial discharges in DC insulation systems. A challenge, but also a must
No full textThis paper has the aim of providing possible solutions for PD measurements, noise rejection and PD source identification focusing mainly on extruded cables. PD tests performed on defective cables under DC and AC indicate how PD DC measurements can be done effectively, and show that noise rejection and PD source identification approaches used nowadays for AC might be extended with good potentiality also to DC
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