303 research outputs found

    Energy Requirements for Quantum Data Compression and 1-1 Coding

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    By looking at quantum data compression in the second quantisation, we present a new model for the efficient generation and use of variable length codes. In this picture lossless data compression can be seen as the {\em minimum energy} required to faithfully represent or transmit classical information contained within a quantum state. In order to represent information we create quanta in some predefined modes (i.e. frequencies) prepared in one of two possible internal states (the information carrying degrees of freedom). Data compression is now seen as the selective annihilation of these quanta, the energy of whom is effectively dissipated into the environment. As any increase in the energy of the environment is intricately linked to any information loss and is subject to Landauer's erasure principle, we use this principle to distinguish lossless and lossy schemes and to suggest bounds on the efficiency of our lossless compression protocol. In line with the work of Bostr\"{o}m and Felbinger \cite{bostroem}, we also show that when using variable length codes the classical notions of prefix or uniquely decipherable codes are unnecessarily restrictive given the structure of quantum mechanics and that a 1-1 mapping is sufficient. In the absence of this restraint we translate existing classical results on 1-1 coding to the quantum domain to derive a new upper bound on the compression of quantum information. Finally we present a simple quantum circuit to implement our scheme.Comment: 10 pages, 5 figure

    On Unconditionally Secure Distributed Oblivious Transfer.

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    This paper is about the Oblivious Transfer in the distributed model proposed by M. Naor and B. Pinkas. In this setting a Sender has n secrets and a Receiver is interested in one of them. During a set up phase, the Sender gives information about the secrets to m Servers. Afterwards, in a recovering phase, the Receiver can compute the secret she wishes by interacting with any k of them. More precisely, from the answers received she computes the secret in which she is interested but she gets no information on the others and, at the same time, any coalition of k − 1 Servers can neither compute any secret nor figure out which one the Receiver has recovered. We present an analysis and new results holding for this model: lower bounds on the resources required to implement such a scheme (i.e., randomness, memory storage, communication complexity); some impossibility results for one-round distributed oblivi- ous transfer protocols; two polynomial-based constructions implementing 1-out-of-n dis- tributed oblivious transfer, which generalize and strengthen the two constructions for 1-out-of-2 given by Naor and Pinkas; as well as new one-round and two-round distributed oblivious transfer protocols, both for threshold and general access structures on the set of Servers, which are optimal with respect to some of the given bounds. Most of these constructions are basically combinatorial in nature

    Growing e-waste management risk awareness points towards new recycling scenarios: The view of the Big Four's youngest consultants

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    The e-waste sector is characterised by a rapid growth at global level and therefore involves an area not yet sufficiently investigated in its risk management dimension. This research fills the gap of the absence of a holistic approach to risk identification and assessment in e-waste management, suggesting a new Risk Awareness Indicator (RAI). An integrated Multi-criteria decision analysis (MCDA)-Analytic Hierarchy Process (AHP) is proposed to calculate the new index. Weights and values will be proposed by twenty Big Four's youngest consultants (generation-Z and millennials). For e-waste, cyber risks related to personal data are critical in the collection phase, environmental risks in the transport phase, and financial and economic risks in the processing phase. Recycling scenarios pose less overall risk than landfill alternatives. The results can help policy makers to meet the circular economy targets set at the European Union level by implementing administrative and regulatory simplifications to support recycling supply chains and make them more efficient and resilient after the pandemic disruption. This work focuses on e-waste and the opinion of screenagers consultants, however the methodology used to design the RAI index makes it easy to replicate the analysis to other social settings and other waste supply chains

    Industry 4.0-based dynamic Social Organizational Life Cycle Assessment to target the social circular economy in manufacturing

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    Nowadays in manufacturing, the topic of sustainability plays a key role. However, over the years, economic crises and the climate change debate have focused the attention of scholars, industrialists and policy makers mainly on environmental sustainability, putting social sustainability on the back burner. This is also evident in the scientific literature which highlights several knowledge gaps. The digital transition of factories and Industry 4.0 technologies have not yet been fully exploited to correlate production and social metrics. As a result, there is a lack of adequate tools for monitoring social performance in the factory environment. In this context, the social dimension of the circular economy is still an under-researched topic. This study aims to fill these gaps by integrating Social Organizational Life Cycle Assessment (SO-LCA) and Industry 4.0 technologies in a blended methodological approach designed to dynamically monitor the social performance of a major manufacturing industry. Using primary data, a set of site-specific social indicators and indexes were created to assess the organization's social impact against key stakeholder categories and subcategories. Finally, within that set, those social metrics that the organization considers essential to moving toward the circular economy were identified. Therefore, this study, has contributed to fill the literature gaps by demonstrating that the digitization of production processes, not only enables the assessment of environmental impact, but can also play a key role in knowing the social performance of a manufacturing organization and to identify the hidden social dimension in the circular economy

    A unified approach to combinatorial key predistribution schemes for sensor networks

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    There have been numerous recent proposals for key predistribution schemes for wireless sensor networks based on various types of combinatorial structures such as designs and codes. Many of these schemes have very similar properties and are analysed in a similar manner. We seek to provide a unified framework to study these kinds of schemes. To do so, we define a new, general class of designs, termed “partially balanced t-designs”, that is sufficiently general that it encompasses almost all of the designs that have been proposed for combinatorial key predistribution schemes. However, this new class of designs still has sufficient structure that we are able to derive general formulas for the metrics of the resulting key predistribution schemes. These metrics can be evaluated for a particular scheme simply by substituting appropriate parameters of the underlying combinatorial structure into our general formulas. We also compare various classes of schemes based on different designs, and point out that some existing proposed schemes are in fact identical, even though their descriptions may seem different. We believe that our general framework should facilitate the analysis of proposals for combinatorial key predistribution schemes and their comparison with existing schemes, and also allow researchers to easily evaluate which scheme or schemes present the best combination of performance metrics for a given application scenario

    The Interaction of Hydrogen with the van der Waals Crystal γ-InSe

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    The emergence of the hydrogen economy requires development in the storage, generation and sensing of hydrogen. The indium selenide (γ-InSe) van der Waals (vdW) crystal shows promise for technologies in all three of these areas. For these applications to be realised, the fundamental interactions of InSe with hydrogen must be understood. Here, we present a comprehensive experimental and theoretical study on the interaction of γ-InSe with hydrogen. It is shown that hydrogenation of γ-InSe by a Kaufman ion source results in a marked quenching of the room temperature photoluminescence signal and a modification of the vibrational modes of γ-InSe, which are modelled by density functional theory simulations. Our experimental and theoretical studies indicate that hydrogen is incorporated into the crystal preferentially in its atomic form. This behaviour is qualitatively different from that observed in other vdW crystals, such as transition metal dichalcogenides, where molecular hydrogen is intercalated in the vdW gaps of the crystal, leading to the formation of "bubbles" for hydrogen storage
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