18,864 research outputs found

    Application of Neural-Like P Systems With State Values for Power Coordination of Photovoltaic/Battery Microgrids

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    The power coordination control of a photovoltaic/battery microgrid is performed with a novel bio-computing model within the framework of membrane computing. First, a neural-like P system with state values (SVNPS) is proposed for describing complex logical relationships between different modes of Photovoltaic (PV) units and energy storage units. After comparing the objects in the neurons with the thresholds, state values will be obtained to determine the con guration of the SVNPS. Considering the characteristics of PV/battery microgrids, an operation control strategy based on bus voltages of the point of common coupling and charging/discharging statuses of batteries is proposed. At rst, the SVNPS is used to construct the complicated unit working modes; each unit of the microgrid can adjust the operation modes automatically. After that, the output power of each unit is reasonably coordinated to ensure the operation stability of the microgrid. Finally, a PV/battery microgrid, including two PV units, one storage unit, and some loads are taken into consideration, and experimental results show the feasibility and effectiveness of the proposed control strategy and the SVNPS-based power coordination control models

    Mitigating energy poverty: Potential contributions of combining PV and building thermal mass storage in low-income households

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    The issue of energy poverty has devastating implications for the society, and it has been aggravated in the past years due to the economic crisis and the increase of energy prices. Among the most affected are those with low incomes and living in inefficient buildings. Unfortunately, the bitter reality is that sometimes this part of the population are facing the next question: Heating, or eating? The declining prices of distributed energy technologies such as photovoltaics provides an opportunity for positive social change. Although their use does not address energy poverty directly, substantial contributions may be made. Measurements of indoor temperatures in a social housing district of southern Spain in 2017 have revealed the unbearable temperatures that the occupants have to endure, both in summer and winter. Using this district as a case study, the present work aims to evaluate the benefits of exploiting its rooftop PV potential to cover part of the electricity consumption of the district (reducing the energy bills), and use the surplus electricity to supply power for the heat pumps in the district. Optimal alternatives regarding maximum PV production, maximum self-sufficiency ratio and minimum investment costs have been found, considering as well different options when sharing the available electricity surplus to improve the thermal comfort of the occupants. As far as the authors know, no previous study has followed an approach aimed at energy poverty alleviation such as the one presented in this work. The results show that using the surplus electricity to heat or cool the whole dwellings would improve the thermal comfort of the occupants in average up to 11% in winter and 26% in summer. If all the PV generation was used or more buildings in the area were employed to install PV modules, improvements up to 33% in winter and 67% in summer could be obtained, reducing at the same time the thermal comfort differences among the dwellings of the district

    Limits to Modularity: A Review of the Literature and Evidence from Chip Design

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    This working paper has been prepared as part of the East-West Center's research project on Globalization of Knowledge Work: Why is Chip Design Moving to Asia. In this paper, Dieter assesses what we know about the limits to modularity and their impact on firm organization and industry structure. He focuses on evidence form chip design, drawing on interview on 2002 and 2003 with a sample of 60 companies and 15 research institutions that are involved in chip design in the US, Taiwan, Korea, China and Malaysia. It is summarized "stylized" propositions of the modularity literature that are well-established, as well as predictions that are controversial. In addition, important limits to modularity and relevant management responses were reviewed.

    Avionics test bed development plan

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    A development plan for a proposed avionics test bed facility for the early investigation and evaluation of new concepts for the control of large space structures, orbiter attached flex body experiments, and orbiter enhancements is presented. A distributed data processing facility that utilizes the current laboratory resources for the test bed development is outlined. Future studies required for implementation, the management system for project control, and the baseline system configuration are defined. A background analysis of the specific hardware system for the preliminary baseline avionics test bed system is included

    Unlocking the deployment of spectrum sharing with a policy enforcement framework

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    Spectrum sharing has been proposed as a promising way to increase the efficiency of spectrum usage by allowing incumbent operators (IOs) to share their allocated radio resources with licensee operators (LOs), under a set of agreed rules. The goal is to maximize a common utility, such as the sum rate throughput, while maintaining the level of service required by the IOs. However, this is only guaranteed under the assumption that all “players”respect the agreed sharing rules. In this paper, we propose a comprehensive framework for licensed shared access (LSA) networks that discourages LO misbehavior. Our framework is built around three core functions: misbehavior detection via the employment of a dedicated sensing network; a penalization function; and, a behavior-driven resource allocation. To the best of our knowledge, this is the first time that these components are combined for the monitoring/policing of the spectrum under the LSA framework. Moreover, a novel simulator for LSA is provided as an open access tool, serving the purpose of testing and validating our proposed techniques via a set of extensive system-level simulations in the context of mobile network operators, where IOs and several competing LOs are considered. The results demonstrate that violation of the agreed sharing rules can lead to a great loss of resources for the misbehaving LOs, the amount of which is controlled by the system. Finally, we promote that including a policy enforcement function as part of the spectrum sharing system can be beneficial for the LSA system, since it can guarantee compliance with the spectrum sharing rules and limit the short-term benefits arising from misbehavior

    The Mirroring Hypothesis: Theory, Evidence and Exceptions

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    The mirroring hypothesis predicts that the organizational patterns of a development project (e.g. communication links, geographic collocation, team and firm co-membership) will correspond to the technical patterns of dependency in the system under development. Scholars in a range of disciplines have argued that mirroring is either necessary or a highly desirable feature of development projects, but evidence pertaining to the hypothesis is widely scattered across fields, research sites, and methodologies. In this paper, we formally define the mirroring hypothesis and review 102 empirical studies spanning three levels of organization: within a single firm, across firms, and in open community-based development projects. The hypothesis was supported in 69% of the cases. Support for the hypothesis was strongest in the within-firm sample, less strong in the across-firm sample, and relatively weak in the open collaborative sample. Based on a detailed analysis of the cases in which the mirroring hypothesis was not supported, we introduce the concept of actionable transparency as a means of achieving coordination without mirroring. We present examples from practice and describe the more complex organizational patterns that emerge when actionable transparency allows designers to 'break the mirror.'Modularity, innovation, product and process development, organization design, design structure, organizational structure, organizational ties
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