Significance Driven Hybrid 8T-6T SRAM for Energy-Efficient Synaptic Storage in Artificial Neural Networks

Multilayered artificial neural networks (ANN) have found widespread utility in classification and recognition applications. The scale and complexity of such networks together with the inadequacies of general purpose computing platforms have led to a significant interest in the development of efficient hardware implementations. In this work, we focus on designing energy efficient on-chip storage for the synaptic weights. In order to minimize the power consumption of typical digital CMOS implementations of such large-scale networks, the digital neurons could be operated reliably at scaled voltages by reducing the clock frequency. On the contrary, the on-chip synaptic storage designed using a conventional 6T SRAM is susceptible to bitcell failures at reduced voltages. However, the intrinsic error resiliency of NNs to small synaptic weight perturbations enables us to scale the operating voltage of the 6TSRAM. Our analysis on a widely used digit recognition dataset indicates that the voltage can be scaled by 200mV from the nominal operating voltage (950mV) for practically no loss (less than 0.5%) in accuracy (22nm predictive technology). Scaling beyond that causes substantial performance degradation owing to increased probability of failures in the MSBs of the synaptic weights. We, therefore propose a significance driven hybrid 8T-6T SRAM, wherein the sensitive MSBs are stored in 8T bitcells that are robust at scaled voltages due to decoupled read and write paths. In an effort to further minimize the area penalty, we present a synaptic-sensitivity driven hybrid memory architecture consisting of multiple 8T-6T SRAM banks. Our circuit to system-level simulation framework shows that the proposed synaptic-sensitivity driven architecture provides a 30.91% reduction in the memory access power with a 10.41% area overhead, for less than 1% loss in the classification accuracy.Comment: Accepted in Design, Automation and Test in Europe 2016 conference (DATE-2016

Ancillary Services in Hybrid AC/DC Low Voltage Distribution Networks

In the last decade, distribution systems are experiencing a drastic transformation with the advent of new technologies. In fact, distribution networks are no longer passive systems, considering the current integration rates of new agents such as distributed generation, electrical vehicles and energy storage, which are greatly influencing the way these systems are operated. In addition, the intrinsic DC nature of these components, interfaced to the AC system through power electronics converters, is unlocking the possibility for new distribution topologies based on AC/DC networks. This paper analyzes the evolution of AC distribution systems, the advantages of AC/DC hybrid arrangements and the active role that the new distributed agents may play in the upcoming decarbonized paradigm by providing different ancillary services.Ministerio de Economía y Competitividad ENE2017-84813-RUnión Europea (Programa Horizonte 2020) 76409

A new governance approach for multi-firm projects: lessons from Olkiluoto 3 and Flamanville 3 nuclear power plant projects

We analyze governance in two contemporary nuclear power plant projects: Olkiluoto 3 (Finland) and Flamanville 3 (France). We suggest that in the governance of large multi-firm projects, any of the prevalent governance approaches that rely on market, hierarchy, or hybrid forms, is not adequate as such. This paper opens up avenues towards a novel theory of governance in large projects by adopting a project network view with multiple networked firms within a single project, and by simultaneously going beyond organizational forms that cut across the traditional firm–market dichotomy. Our analysis suggests four changes in the prevailing perspective towards the governance of large projects. First, there should be a shift from viewing multi-firm projects as hierarchical contract organizations to viewing them as supply networks characterized by a complex and networked organizational structure. Second, there should be a shift in the emphasis of the predominant modes of governance, market and hierarchy towards novel governance approaches that emphasize network-level mechanisms such as self-regulation within the project. Third, there should be a shift from viewing projects as temporary endeavors to viewing projects as short-term events or episodes embedded in the long-term sphere of shared history and expected future activities among the involved actors. Fourth, there should be a shift from the prevailing narrow view of a hierarchical project management system towards an open system view of managing in complex and challenging institutional environments

The use and value of hierarchical governance and modeling in infrastructure network planning

This paper discusses the seemingly inespacable tension between two dominant approaches to governance that are implemented with regard to the planning, design and development of infrastructure networks, such as roads and railways. Roughly, these approaches can be framed in two styles of governance, the hierarchical and the consensual style (Smits, 1995). In today’s (western) societies, hierarchical approaches to governance seem to become more and more obsolete. This is especially the case with regard to ´problematic situations´ that have a large spatial and environmental impact. For example, the planning, design and development of infrastructure networks have such a widespread, trans-sectoral impact, that a top down approach is considered to be no longer viable. The impact of large scale projects (such as the Betuwelijn, the development of the Tweede Maasvlakte or the High Speed Train Network) spreads into spatial, environmental, financial, legal, economic (with regard to exploitation and maintenance) and social aspects of everyday life. As a consequence, it is more and more to be considered as ´a normal procedure´ to at least consult the stakeholders concerned. The almost inevitable involvement of large groups of stakeholders with different characteristics cannot be achieved with hierarchical approaches to governance. Top down is assumed to be inappropriate and thus, un-called for in these types of policy processes. Following this widely accepted assumption, consensual approaches are designed and implemented, under various appealing banners, such as co-production, open planning processes and participatory policy making. These appealing names lead to innovative forms of interaction and participation of stakeholders. Stakeholders are enticed to participate in design workshops, brainstorms, coffee table talks, internet based discussions and surveys and market consultations. Stakeholders are invited to information centres and travelling exhibitions. All these efforts are undertaken based on the assumption that (this time) ´government will really listen and make effective use of all ideas, concerns and energy´. The question arises how effective and efficient these participatory efforts have been thus far. Is a consensual style of governance a solution for the ever increasing complexity of the impact of large scale infrastructural projects? Or has the hierarchical style still have some value for this type of policy processes? And if so, what kind value is this? And in addition, can hierarchical and consensual styles of governance simultaneously be helpful in planning, design and development of infrastructural networks, and if so, how and to what extend? Or must they be considered to be ´natural enemies´ with regard to designing and implementing policy processes? In this paper these questions will be addressed by assessing a (virtual) case study, the further advancement of the road infrastructure network around the city of Rotterdam (also known as the Rotterdamse Ruit). Subsequently we will discuss the two dominant styles of governance, the hierarchical and consensual style. Second, we will describe the role and value of hierarchical (top down) and consensual (bottom up) approaches in planning, designing and development of (road) infrastructural networks and projects. Third, we will make an attempt to combine both approaches, into a hybrid, cross over like, approach that incorporates both hierarchical and consensual approaches in governance. And fourth, we will apply (test) our hybrid, cross over approach to our (virtual) case study, thus proposing an approach for future governance to support the further advancement of the (road) infrastructure network in and around Rotterdam.

Transforming Energy Networks via Peer to Peer Energy Trading: Potential of Game Theoretic Approaches

Peer-to-peer (P2P) energy trading has emerged as a next-generation energy management mechanism for the smart grid that enables each prosumer of the network to participate in energy trading with one another and the grid. This poses a significant challenge in terms of modeling the decision-making process of each participant with conflicting interest and motivating prosumers to participate in energy trading and to cooperate, if necessary, for achieving different energy management goals. Therefore, such decision-making process needs to be built on solid mathematical and signal processing tools that can ensure an efficient operation of the smart grid. This paper provides an overview of the use of game theoretic approaches for P2P energy trading as a feasible and effective means of energy management. As such, we discuss various games and auction theoretic approaches by following a systematic classification to provide information on the importance of game theory for smart energy research. Then, the paper focuses on the P2P energy trading describing its key features and giving an introduction to an existing P2P testbed. Further, the paper zooms into the detail of some specific game and auction theoretic models that have recently been used in P2P energy trading and discusses some important finding of these schemes.Comment: 38 pages, single column, double spac

Peer-to-peer and community-based markets: A comprehensive review

The advent of more proactive consumers, the so-called "prosumers", with production and storage capabilities, is empowering the consumers and bringing new opportunities and challenges to the operation of power systems in a market environment. Recently, a novel proposal for the design and operation of electricity markets has emerged: these so-called peer-to-peer (P2P) electricity markets conceptually allow the prosumers to directly share their electrical energy and investment. Such P2P markets rely on a consumer-centric and bottom-up perspective by giving the opportunity to consumers to freely choose the way they are to source their electric energy. A community can also be formed by prosumers who want to collaborate, or in terms of operational energy management. This paper contributes with an overview of these new P2P markets that starts with the motivation, challenges, market designs moving to the potential future developments in this field, providing recommendations while considering a test-case

A survey of simulation techniques in commerce and defence

Despite the developments in Modelling and Simulation (M&S) tools and techniques over the past years, there has been a gap in the M&S research and practice in healthcare on developing a toolkit to assist the modellers and simulation practitioners with selecting an appropriate set of techniques. This study is a preliminary step towards this goal. This paper presents some results from a systematic literature survey on applications of M&S in the commerce and defence domains that could inspire some improvements in the healthcare. Interim results show that in the commercial sector Discrete-Event Simulation (DES) has been the most widely used technique with System Dynamics (SD) in second place. However in the defence sector, SD has gained relatively more attention. SD has been found quite useful for qualitative and soft factors analysis. From both the surveys it becomes clear that there is a growing trend towards using hybrid M&S approaches