141 research outputs found
Cross Ledger Transaction Consistency for Financial Auditing
No full textAuditing throughout a fiscal year is integral to organizations with transactional activity. Organizations transact with each other and record the details for all their economical activities so that a regulatory committee can verify the lawfulness and legitimacy of their activity. However, it is computationally infeasible for the committee to perform all necessary checks for each organization. To overcome this, auditors assist in this process: organizations give access to all their internal data to their auditors, who then produce reports regarding the consistency of the organization’s data, alerting the committee to any inconsistencies. Despite this, numerous issues that result in fines annually revolve around such inconsistencies in bookkeeping across organizations. Notably, committees wishing to verify the correctness of auditor-provided reports need to redo all their calculations; a process which is computationally proportional to the number of organizations. In fact, it becomes prohibitive when considering real-world settings with thousands of organizations. In this work, we propose two protocols, CLOSC and CLOLC, whose goals are to enable auditors and a committee to verify the consistency of transactions across different ledgers. Both protocols ensure that for every transaction recorded in an organization’s ledger, there exists a dual one in the ledger of another organization while safeguarding against other potential attacks. Importantly, we minimize the information leakage to auditors and other organizations and guarantee three crucial security and privacy properties that we propose: (i) transaction amount privacy, (ii) organization-auditor unlinkability, and (iii) transacting organizations unlinkability. At the core of our protocols lies a two-tier ledger architecture alongside a suite of cryptographic tools. To demonstrate the practicality and scalability of our designs, we provide extensive performance evaluation for both CLOSC and CLOLC. Our numbers are promising, i.e., all computation and verification times lie in the range of seconds, even for millions of transactions, while the on-chain storage costs for an auditing epoch are encouraging i.e. in the range of GB for millions of transactions and thousands of organizations
The German realism and the short stories of Costantinos Chatzopoulos
No full text[Δε διατίθεται περίληψη]This article is an analysis and a reevaluation of the main characteristics of the literary movement of the German ('bourgeois' or 'poetic') realism and of the short stories of Costantinos Chatzopoulos. My analysis confirms that the Greek author was greatly influenced by this literary movement, with which he became familiar during the ten years of his migration in Germany. In this study I try to retrace and register the main aesthetic and ideological implications of the German movement, as they are expressed in the narratives of Chatzopoulos in his attempt to define the Self and its main experiences at the dawn of the 20th century
Constantinos Chatzopoulos as a literary critic
No full textLa critique littéraire représente une part non négligeable de l’œuvre de Constantin Chatzopoulos (Agrinion 1868 - Brindisi 1920). Comparée aux autres genres littéraires, auxquels il a sacrifié (poésie, prose, traduction, essais politiques), elle demeure jusqu’à nos jours le volet le moins connu de son œuvre. La première démarche indispensable afin de proposer une étude de son œuvre critique la plus complète possible, était de réunir l’ensemble de ses articles, parallèlement à ceux qui déjà étaient connus. Tel est l’objectif de la première partie de ce travail qui fait le point de la recherche. La seconde partie, théorique, suit la critique littéraire de Chatzopoulos dans le cadre des deux périodes de son développement : a) l’influence symboliste et nietzschéenne (1898-1902) et b) l’influence sociologique et marxiste (1907-1916). Sont présentés, pour ces deux phases, les revues littéraires qui ont accueilli les textes de l’écrivain. Chatzopoulos représente un chapitre important de l’histoire de la pensée critique grecque, car son œuvre rend compte des courants esthétiques et idéologiques de son époque auxquels elle est intimement liée. Dans la Grèce des débuts du siècle passé, il fut le premier à introduire les principes sociologiques et marxistes dans l’approche d’une œuvre littéraire.Literary criticism represents an interesting part of the Constantinos Chatzopoulos’ (Agrinion 1968 - Prindisi 1920) writing creation. Until our days it remains the least known compared to other literature types, which he served (poetry, prose, translation, political essay). A condition for a fuller study of his work as a critic was the collection of his articles, in addition to those which were already known. Hence this is the aim of all the elements which compose the first research part of our thesis. The second, theoretical part of the thesis monitors the Chatzopoulos’ literary criticism works within the pale of the two phases it occurs: a) the symbolistic - nietzscheic (1898-1902) and sociological - marxist (1907-1916). In both stages the presentation of the literary publications in which works by the author appeared is preceded. Chatzopoulos represents an important asset in the history of the Greek critical thinking, because his work was associated with aesthetic and ideological movements of his time. In Greece of the early past century, he is the first to introduce the sociological and Marxist values into the approach of literary work
SciTo Trends: Visualising Scientific Topic Trends
No full text<p>Presentation of the TPDL 2019 demo paper "SciTo Trends: Visualising Scientific Topic Trends".</p>
<p><a href="https://scito.imsi.athenarc.gr">SciTo Trends</a> is a platform that facilitates exploration of scientific topic trends and provides intuitive infographics to showcase the topics' popularity trends. </p>
<p>Full author list: Serafeim Chatzopoulos, Panagiotis Deligiannis, Thanasis Vergoulis, Ilias Kanellos, Christos Tryfonopoulos, Theodore Dalamagas</p>
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Have you asked your neighbors? A Hidden Market approach for device-to-device offloading
No full textDuring the last years, researchers have proposed solutions to help smartphones offload heavy tasks to remote entities in order to improve execution time and reduce energy consumption. Lately, inspired by the promising results of message forwarding in opportunistic networks, many researchers have proposed strategies for task offloading towards nearby mobile devices. None of these strategies, though, proposes any mechanism that considers selfish users and, most importantly, that motivates and defrays the participating devices who spend their resources. In this paper, we address these problems and propose the design of a framework that integrates an incentive scheme and a reputation mechanism. Our proposal follows the principles of the Hidden Market Design approach, which allows users to specify the amount of resources they are willing to sacrifice when participating in the offloading system. The underlying algorithm, that users are not aware of, is based on a truthful auction strategy and a peer-to-peer reputation exchange scheme. Extensive simulations on real traces depict how our designed mechanism achieves higher offloading rate and produces less traffic compared to three benchmark algorithms. Finally, we show how collaborating devices get rewarded for their contribution, while selfish ones get sidelined by others. © 2016 IEEE
Video compression in the neighborhood: An opportunistic approach
No full textThe proliferation of mobile devices combined with advances in the area of low-power wireless communication, such as Wi-Fi Direct and Bluetooth 4.0, gave rise to a new computation paradigm known as Device-to-Device (D2D) offloading. In this scenario, devices collaborate with each other using short wireless links to create ad-hoc P2P networks for distributed task execution. Experiments on human movement, a non-negligible factor in the D2D context, have shown that people move in group or meet frequently, which suggests that D2D is possible. In this work, we examine the case of parallel compression of smartphone recorded videos with the help of nearby devices. First, we present a mathematical formulation of the problem that optimizes the compression time on the number of nearby helping devices, and show that the problem can be mapped as a water-filling problem. Then, we present real results of the compression time and energy when the compression is performed on one device and when it is parallelized among collaborating devices. To obtain these results, we implemented an Android application that is able to detect nearby devices, connect with them using Wi-Fi Direct, send video chunks for compression, receive and merge compressed chunks into one full compressed video.</p
Keep your nice friends close, but your rich friends closer - computation offloading using NFC
No full textThe increasing complexity of smartphone applications and services necessitate high battery consumption but the growth of smartphones' battery capacity is not keeping pace with these increasing power demands. To overcome this problem, researchers gave birth to the Mobile Cloud Computing (MCC) research area. In this paper we advance on previous ideas, by proposing and implementing the first known Near Field Communication (NFC)-based computation offloading framework. This research is motivated by the advantages of NFC's short distance communication, with its better security, and its low battery consumption. We design a new NFC communication protocol that overcomes the limitations of the default protocol; removing the need for constant user interaction, the one-way communication restraint, and the limit on low data size transfer. We present experimental results of the energy consumption and the time duration of two computationally intensive representative applications: (i) RSA key generation and encryption, and (ii) gaming/puzzles. We show that when the helper device is more powerful than the device offloading the computations, the execution time of the tasks is reduced. Finally, we show that devices that offload application parts considerably reduce their energy consumption due to the low-power NFC interface and the benefits of offloading
FlopCoin:A Cryptocurrency for Computation Offloading
No full textDuring the last years, researchers have proposed solutions to help smartphones improve execution time and reduce energy consumption by offloading heavy tasks to remote entities. Lately, inspired by the promising results of message forwarding in opportunistic networks, many researchers have proposed strategies for task offloading towards nearby mobile devices, giving birth to the Device-to-Device offloading paradigm. None of these strategies, though, offers any mechanism that considers selfish users and, most importantly, that motivates and defrays the participating devices who spend their resources. In this paper, we address these problems and propose the design of a framework that integrates an incentive scheme and a reputation mechanism. Our proposal follows the principles of the Hidden Market Design approach, which allows users to specify the amount of resources they are willing to sacrifice when participating in the offloading system. The underlying algorithm, that users are not aware of, is based on a truthful auction strategy and a peer-to-peer reputation exchange scheme. Extensive simulations on real traces depict how our designed mechanism achieves higher offloading rate and produces less traffic compared to three benchmark algorithms. Finally, we show how collaborating devices get rewarded for their contribution, while selfish ones get sidelined by others.</p
MyoKey: Inertial Motion Sensing and Gesture-Based QWERTY Keyboard for Extended Realities
No full textUsability challenges and social acceptance of textual input in a context of extended realities (XR) motivate the research of novel input modalities. We investigate the fusion of inertial measurement unit (IMU) control and surface electromyography (sEMG) gesture recognition applied to text entry using a QWERTY-layout virtual keyboard. We design, implement, and evaluate the proposed multi-modal solution named MyoKey. The user can select characters with a combination of arm movements and hand gestures. MyoKey employs a lightweight convolutional neural network classifier that can be deployed on a mobile device with insignificant inference time. We demonstrate the practicality of interruption-free text entry with MyoKey, by recruiting 12 participants and by testing three sets of grasp micro-gestures in three scenarios: empty hand text input, tripod grasp (e.g., pen), and a cylindrical grasp (e.g., umbrella). With MyoKey, users achieve an average text entry rate of 9.33 words per minute (WPM), 8.76 WPM, and 8.35 WPM for the freehand, tripod grasp, and cylindrical grasp conditions, respectively.</p
OPENRP:a reputation middleware for opportunistic crowd computing
No full textThe concepts of wisdom of crowd and collective intelligence have been utilized by mobile application developers to achieve large-scale distributed computation, known as crowd computing. The profitability of this method heavily depends on users' social interactions and their willingness to share resources. Thus, different crowd computing applications need to adopt mechanisms that motivate peers to collaborate and defray the costs of participating ones who share their resources. In this article, we propose OPENRP, a novel, lightweight, and scalable system middleware that provides a unified interface to crowd computing and opportunistic networking applications. When an application wants to perform a device-to-device task, it delegates the task to the middleware, which takes care of choosing the best peers with whom to collaborate and sending the task to these peers. OPENRP evaluates and updates the reputation of participating peers based on their mutual opportunistic interactions. To show the benefits of the middleware, we simulated the behavior of two representative crowdsourcing applications: message forwarding and task offloading. Through extensive simulations on real human mobility traces, we show that the traffic generated by the applications is lower compared to two benchmark strategies. As a consequence, we show that when using our middleware, the energy consumed by the nodes is reduced. Finally, we show that when dividing the nodes into selfish and altruistic, the reputation scores of the altruistic peers increase with time, while those of the selfish ones decrease. © 1979-2012 IEEE
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