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1
Raynal, Michel. « On the Versatility of Bracha’s Byzantine Reliable Broadcast Algorithm ». Parallel Processing Letters 31, no 03 (27 mai 2021) : 2150006. http://dx.doi.org/10.1142/s0129626421500067.
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G. Bracha presented in 1987 a simple and efficient reliable broadcast algorithm for [Formula: see text]-process asynchronous message-passing systems, which tolerates up to [Formula: see text] Byzantine processes. Following an idea recently introduced by Hirt, Kastrato and Liu-Zhang (OPODIS 2020), instead of considering the upper bound on the number of Byzantine processes [Formula: see text], the present short article considers two types of Byzantine behavior: the ones that can prevent the safety property from being satisfied, and the ones that can prevent the liveness property from being satisfied (a Byzantine process can exhibit only one or both types of failures). This Byzantine differentiated failure model is captured by two associated upper bounds denoted [Formula: see text] (for safety) and [Formula: see text] for liveness). The article shows that only the threshold values used in the predicates of Bracha’s algorithm must be modified to obtain an algorithm that works with this differentiated Byzantine failure model.
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ABORISADE, D. O., A. S. SODIYA, A. A. ODUMOSU, O. Y. ALOWOSILE et A. A. ADEDEJI. « A SURVIVABLE DISTRIBUTED DATABASE AGAINST BYZANTINE FAILURE ». Journal of Natural Sciences Engineering and Technology 15, no 2 (22 novembre 2017) : 61–72. http://dx.doi.org/10.51406/jnset.v15i2.1684.
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Distributed Database Systems have been very useful technologies in making a wide range of information available to users across the World. However, there are now growing security concerns, arising from the use of distributed systems, particularly the ones attached to critical systems. More than ever before, data in distributed databases are more susceptible to attacks, failures or accidents owing to advanced knowledge explosions in network and database technologies. The imperfection of the existing security mechanisms coupled with the heightened and growing concerns for intrusion, attack, compromise or even failure owing to Byzantine failure are also contributing factors. The importance of survivable distributed databases in the face of byzantine failure, to other emerging technologies is the motivation for this research. Furthermore, It has been observed that most of the existing works on distributed database only dwelled on maintaining data integrity and availability in the face of attack. There exist few on availability or survibability of distributed databases owing to internal factors such as internal sabotage or storage defects. In this paper, an architecture for entrenching survivability of Distributed Databases occasioned by Byzantine failures is proposed. The proposed architecture concept is based on re-creating data on failing database server based on a set threshold value.The proposed architecture is tested and found to be capable of improving probability of survivability in distributed database where it is implemented to 99.6% from 99.2%.
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PAQUETTE, MICHEL, et ANDRZEJ PELC. « FAST BROADCASTING WITH BYZANTINE FAULTS ». International Journal of Foundations of Computer Science 17, no 06 (décembre 2006) : 1423–39. http://dx.doi.org/10.1142/s0129054106004492.
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We construct and analyze a fast broadcasting algorithm working in the presence of Byzantine component faults. Such faults are particularly difficult to deal with, as faulty components may behave arbitrarily (even maliciously) as transmitters, by either blocking, rerouting, or altering transmitted messages in a way most detrimental to the broadcasting process. We assume that links and nodes of a communication network are subject to Byzantine failures, and that faults are distributed randomly and independently, with link failure probability p and node failure probability q, these parameters being constant and satisfying the inequality (1 - p)2(1 - q) > 1/2. A broadcasting algorithm, working in an n-node network, is called almost safe if the probability of its correctness is at least 1 - 1/n, for sufficiently large n. Thus the robustness of the algorithm grows with the size of the network. Our main result is the design and analysis of an almost safe broadcasting algorithm working in time O( log 2 n) and using O(n log n) messages in n-node networks. Under a stronger assumption on failure probability parameters, namely (1 - p)2(1 - q)2 > 1/2, our algorithm can be modified to work in time O( log 2 n/ log log n), also using O(n log n) messages. The novelty of our algorithm is that it can cope with the most difficult type of faults, potentially affecting all components of the network (both its links and nodes), and that it is simultaneously robust and efficient.
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Wang, Shu-Ching, et Kuo-Qin Yan. « Byzantine Agreement under dual failure mobile network ». Computer Standards & ; Interfaces 28, no 4 (avril 2006) : 475–92. http://dx.doi.org/10.1016/j.csi.2005.03.004.
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FRIEDMAN, ROY, ACHOUR MOSTEFAOUI et MICHEL RAYNAL. « $\diamondsuit {\mathcal P}_{mute}$-BASED CONSENSUS for ASYNCHRONOUS BYZANTINE SYSTEMS ». Parallel Processing Letters 15, no 01n02 (mars 2005) : 169–82. http://dx.doi.org/10.1142/s0129626405002131.
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This paper presents a consensus protocol for asynchronous distributed systems made up of n processes, where up to f<n/4 processes can behave arbitrarily (Byzantine processes). The protocol assumes that the underlying system is equipped with an unreliable failure detector of the class [Formula: see text]. The failure detectors of the class [Formula: see text] ensure that (1) all mute processes are detected (a mute process is a process that, after some time, stops sending protocol messages), and (2) after some unknown but finite time, no correct process is suspected (mute processes are a subset of the Byzantine processes). The proposed protocol enjoys the following properties. It is based on the round coordinator paradigm and its design principle is particularly simple. Its message complexity is O(n2) per round. In addition to a round number, the message size is O(1), except for one message per round (sent by the round coordinator) whose size is O(n). The protocol does not use message "proofs", certificates, or application level signatures. When no process is faulty, all processes propose the same value, and the failure detector makes no mistake, the processes decide in one round (4 communication steps). Finally, when a process decides, it only needs a simple unreliable broadcast mechanism to prevent the other processes from deadlocking. All these features make the protocol attractive to cope with the net effect of Byzantine failures and asynchrony.
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Porada, Aleksandra. « Kardynał Bessarion i jego księgozbiór ». Bibliotekarz Podlaski Ogólnopolskie Naukowe Pismo Bibliotekoznawcze i Bibliologiczne 60, no 3 (21 décembre 2023) : 297–324. http://dx.doi.org/10.36770/bp.834.
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Cardinal Bessarion (ca. 1400–1472), a theologian born in Trebizond and educated in Byzantium, made a career in the hierarchy of the Byzantine clergy and attracted the attention of the imperial family. He was one of the most active participants of the Council of Ferrara-Florence (1438–1439). Following the failure of the church union in Constantinople, Bessarion came to work for the papal curia in Rome. As a cardinal he used his income and contacts to help Byzantine refugees and Greeks living under the rule of the Republic of Venice, especially after the fall of Constantinople. Fearing that the loss of statehood could mean that the heritage of Greek culture would fall into oblivion, Bessarion created a great library containing the masterpieces of Ancient Greek literature, the classical philosophical works, and the texts of the Eastern Church Fathers. In 1468, he donated this collection to the Republic of Venice, and in such a manner founded one of the first public libraries in Europe.
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Betancourt, Roland. « Faltering images : failure and error in Byzantine manuscript illumination ». Word & ; Image 32, no 1 (2 janvier 2016) : 1–20. http://dx.doi.org/10.1080/02666286.2016.1143766.
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Maurer, Alexandre, et Sebastien Tixeuil. « Tolerating Random Byzantine Failures in an Unbounded Network ». Parallel Processing Letters 26, no 01 (mars 2016) : 1650003. http://dx.doi.org/10.1142/s0129626416500031.
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In a context where networks grow larger and larger, their nodes become more likely to fail. Indeed, they may be subject to crashes, attacks, memory corruptions… To encompass all possible types of failure, we consider the most general model of failure: the Byzantine model, where any failing node may exhibit arbitrary (and potentially malicious) behavior. We consider an asynchronous grid-shaped network where each node has a probability λ to be Byzantine. Our metric is the communication probability, that is, the probability that any two nodes communicate reliably. A number of Byzantine-resilient broadcast protocols exist, but they all share the same weakness: when the size of the grid increases, the communication probability approaches zero. In this paper, we present the first protocol that overcomes this difficulty, and ensures a communication probability of [Formula: see text] on a grid that may be as large as we want (for a sufficiently small λ, typically [Formula: see text]). The originality of the approach lies in the fractal definition of the protocol, which, we believe, could be used to solve several similar problems related to scalability. We also extend this scheme to a 3-dimensional grid and obtain a [Formula: see text] communication probability for [Formula: see text].
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Karavites, Peter. « Gregory Nazianzinos and Byzantine hymnography ». Journal of Hellenic Studies 113 (novembre 1993) : 81–98. http://dx.doi.org/10.2307/632399.
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Frequent references have been made by several scholars to the use of Gregory's writings as a ‘mine’ for Byzantine hymnography. The discussions have usually stopped with three or four quick citations of the instances that best exemplify the borrowing. To date there has not been any systematic effort to research the topic in greater detail. This failure is understandable. Such a research presupposes knowledge not only of Gregory's writings, a major task in itself since his works occupy four volumes of PG, but also of Byzantine hymnography which is scattered throughout several volumes used by the Orthodox Church in its daily heortologion. Adding the possibilities that might exist among the mss of Grottaferrata and those that might exist in the Vatican Library, one can easily understand the magnitude of the task and its complexities. This paper attempts a limited but still daunting undertaking: the ferreting out of the borrowings from Gregory by the Byzantine hymnographers whose hymns are still used by the Orthodox Church. Beyond the obvious borrowings by the hymnographers from Gregory lies the insoluble problem of what may be directly borrowed and what indirectly. How can one prove that similarities or even identities in the language denote direct borrowing of one author from another? The complexities of such an investigation notwithstanding, the effort should be made, even on a limited scale, because of the interest and the challenge involved.
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Honoré, Wolf, Longfei Qiu, Yoonseung Kim, Ji-Yong Shin, Jieung Kim et Zhong Shao. « AdoB : Bridging Benign and Byzantine Consensus with Atomic Distributed Objects ». Proceedings of the ACM on Programming Languages 8, OOPSLA1 (29 avril 2024) : 419–48. http://dx.doi.org/10.1145/3649826.
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Achieving consensus is a challenging and ubiquitous problem in distributed systems that is only made harder by the introduction of malicious byzantine servers. While significant effort has been devoted to the benign and byzantine failure models individually, no prior work has considered the mechanized verification of both in a generic way. We claim this is due to the lack of an appropriate abstraction that is capable of representing both benign and byzantine consensus without either losing too much detail or becoming impractically complex. We build on recent work on the atomic distributed object model to fill this void with a novel abstraction called AdoB. In addition to revealing important insights into the essence of consensus, this abstraction has practical benefits for easing distributed system verification. As a case study, we proved safety and liveness properties for AdoB in Coq, which are the first such mechanized proofs to handle benign and byzantine consensus in a unified manner. We also demonstrate that AdoB faithfully models real consensus protocols by proving it is refined by standard network-level specifications of Fast Paxos and a variant of Jolteon.
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Marketos, S. G., A. G. Eftychiadis et A. Diamandopoulos. « Acute Renal Failure According to Ancient Greek and Byzantine Medical Writers ». Journal of the Royal Society of Medicine 86, no 5 (mai 1993) : 290–93. http://dx.doi.org/10.1177/014107689308600516.
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O'Sullivan, S. P. « The Turkish Conquest of Anatolia in the Eleventh Century ». Hawliyat 8 (10 janvier 2019) : 41–93. http://dx.doi.org/10.31377/haw.v8i0.335.
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The article describes the Turkish conquest of Anatolia in the second half of the eleventh century. An evaluation of the sources (almost all Greek) and a sum- mary of the successful Byzantine defence against the Arabs is followed by a detailed account of the principal stages of the Turkish conquest. The inadequacy of the sources, which become less and less informative as the conquest pro- ceeded, means that the final and most important stage of the Turkish advance, from 1081—85, must be conjectured. Nevertheless, the general outline of the con- quest is suffciently clear. The article concludes by identifying one of the main causes Of the debacle: the failure of imperial governments from Basil II (976—1025) to grasp the importance of defending Anatolia, as evidenced by the shift of byzantine interests to the Balkans.
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Chatterjee, Paroma. « The Byzantine Icon of the Virgin in the Church of the Blachernae : Michael Psellos on the Problem of Miraculous Timing ». Journal of Medieval and Early Modern Studies 51, no 2 (1 mai 2021) : 241–62. http://dx.doi.org/10.1215/10829636-8929059.
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This article looks closely at the report of a miracle that occurred in eleventh-century Constantinople in which the veil covering an icon of the Theotokos (Virgin) at the Blachernae church lifted itself miraculously. The report, scripted by the Byzantine polymath Michael Psellos, focuses in intriguing ways on the actions and nonactions of the veil when the icon presided over a judicial trial. The article contends that Psellos insists on the theme of timing (with regard to the lifting and otherwise of the veil) and the Blachernae icon's role in determining a critical, decisive moment in the arbitration of human affairs. This emphasis, in turn, bespeaks a broader concern over the timing of sacred icons during significant moments in Byzantine history as understood by contemporary chroniclers: namely, their failure to act in appropriate ways at critical moments when the empire itself was at stake.
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Kouris, Emmanouil-Georgios, Leonidas-Alexandros S. Kouris, Avraam A. Konstantinidis, Chris G. Karayannis et Elias C. Aifantis. « Assessment and Fragility of Byzantine Unreinforced Masonry Towers ». Infrastructures 6, no 3 (9 mars 2021) : 40. http://dx.doi.org/10.3390/infrastructures6030040.
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The seismic response of five cultural heritage towers erected between the 10th and 19th century AD are investigated herein. Firstly, their architectural and modal characteristics were studied in the light of seismic events that hit the monuments. There exist several historical reports of strong earthquakes, as well as damaged structures and collapses. The limit analysis is adopted to examine the post-elastic behavior of the towers up to collapse due to out-of-plane failure. Recurrent damage modes were collected from recent earthquakes and a classification of four possible collapse mechanisms in towers and slender masonry structures is here proposed: overturning, separation of perpendicular walls, diagonal cracking, and dislocation of the belfry. A thorough examination of the towers under investigation verified the proposed damage classification. The capacity curves were derived combining the capacity curves of each of the collapse mechanisms. Damage thresholds were defined on these curves in correspondence with damage states. The studied group of structures is representative of a wider typology. A statistical approach was adopted to describe damage with seismic intensity, and vulnerability curves were generated. The results of this study will improve the understanding of the performance and the collapse mechanisms of slender masonry structures under seismic loading and provide a characterization of seismic vulnerability for the studied cultural heritage types of towers.
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Islam, Nahida, Md Sazzadur Rahman, Imtiaz Mahmud, Md Nur Amin Sifat et You-Ze Cho. « A Blockchain-Enabled Distributed Advanced Metering Infrastructure Secure Communication (BC-AMI) ». Applied Sciences 12, no 14 (20 juillet 2022) : 7274. http://dx.doi.org/10.3390/app12147274.
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The world is facing an urgent need to provide secure communication and data access control in advanced metering infrastructure (AMI) because conventional cryptographic key management and authentication protocols are at stake. The cryptography schemes entirely rely on trusted third parties (TTPs), leading to a single point of failure and increasing network overhead. In response to this inefficiency and security compromise, this study proposes a blockchain-enabled distributed AMI secure communication scheme. In the proposed work, smart contract (SC), an integrated part of the blockchain, is programmed to substitute traditional TTP-based transaction systems, which operate in a distributed, immutable, and trustworthy manner. In this paper, we implemented practical Byzantine fault tolerance (PBFT) consensus algorithm and Hyperledger Fabric (HLF) blockchain platform to ensure Byzantine fault tolerance in the blockchain transaction. Performance analysis shows that the proposed BC-AMI scheme has the advantage of incurring the least amount of communication and time costs compared with similar studies while ensuring security against some common cyber-attacks.
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Guba, Zoltán, István Finta, Ákos Budai, Lóránt Farkas, Zoltán Zimborás et András Pályi. « Resource analysis for quantum-aided Byzantine agreement with the four-qubit singlet state ». Quantum 8 (30 avril 2024) : 1324. http://dx.doi.org/10.22331/q-2024-04-30-1324.
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In distributed computing, a Byzantine fault is a condition where a component behaves inconsistently, showing different symptoms to different components of the system. Consensus among the correct components can be reached by appropriately crafted communication protocols even in the presence of byzantine faults. Quantum-aided protocols built upon distributed entangled quantum states are worth considering, as they are more resilient than traditional ones. Based on earlier ideas, here we establish a parameter-dependent family of quantum-aided weak broadcast protocols. We compute upper bounds on the failure probability of the protocol, and define and illustrate a procedure that minimizes the quantum resource requirements. Following earlier work demonstrating the suitability of noisy intermediate scale quantum (NISQ) devices for the study of quantum networks, we experimentally create our resource quantum state on publicly available quantum computers. Our work highlights important engineering aspects of the future deployment of quantum communication protocols with multi-qubit entangled states.
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Mella, Giovanni, Elena Ferrari, Elisa Bertino et Yunhua Koglin. « Controlled and cooperative updates of XML documents in byzantine and failure-prone distributed systems ». ACM Transactions on Information and System Security 9, no 4 (novembre 2006) : 421–60. http://dx.doi.org/10.1145/1187441.1187443.
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Chang, Jenghorng, et Fanpyn Liu. « A Byzantine Sensing Network Based on Majority-Consensus Data Aggregation Mechanism ». Sensors 21, no 1 (2 janvier 2021) : 248. http://dx.doi.org/10.3390/s21010248.
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In the current Internet of Things era, digital devices form complex interconnections. The statuses of objects of interest are monitored using sensors, and distributed wireless sensor networks are formed from numerous sensor nodes. Many Byzantine fault tolerance mechanisms in wireless sensor networks (WSNs) were proposed from Byzantine agreement which even with a few faulty nodes in a sensor network, most healthy nodes can reach a consensus, perform data transmission tasks, and maintain network operation. In this study, this mechanism was utilized together with the majority function technique; in particular, the proposed method uses original sensor signals to define a threshold to assert a binary value of one or zero, thereby performing data judgment and aggregation. This approach reduces node energy consumption and enables the nodes to quickly reach a consensus. Moreover, the operating performance of the network can be maintained even when problems such as node failure and faults occur within the fault tolerance range. Compared with existing algorithms, the proposed data aggregation mechanism exhibits a better network life cycle and can effectively extend the flexibility of network operations.
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Arthur, Paul, Girolamo Fiorentino et Anna Maria Grasso. « Roads to recovery : an investigation of early medieval agrarian strategies in Byzantine Italy in and around the eighth century ». Antiquity 86, no 332 (juin 2012) : 444–55. http://dx.doi.org/10.1017/s0003598x00062864.
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The cumulative power of botanical and chemical analysis is demonstrated here by our authors, who succeed in opening a window on Europe's most obscure period, in the south as in the north, the time after the Roman and then the Byzantine empire lost its hold. The emphasis here is on the rise in production and trade of cash crops in the eighth century as detected by survey, pollen, charcoal and residues. Taken together, the new data show a community well on the road to economic recovery after two centuries of recession and monetary failure.
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Zhang, Yansong, Bo Shen et Yingsi Zhao. « Rational Uniform Consensus with General Omission Failures ». Computational Intelligence and Neuroscience 2022 (31 août 2022) : 1–18. http://dx.doi.org/10.1155/2022/9544059.
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Generally, system failures, such as crash failures, Byzantine failures, and so on, are considered as common reasons for the inconsistencies of distributed consensus and have been extensively studied. In fact, strategic manipulations by rational agents are not ignored for reaching consensus in a distributed system. In this paper, we extend the game-theoretic analysis of consensus and design an algorithm of rational uniform consensus with general omission failures under the assumption that processes are controlled by rational agents and prefer consensus. Different from crashing one, agent with omission failures may crash or omit to send or receive messages when it should, which leads to difficulty of detecting faulty agents. By combining the possible failures of agents at the both ends of a link, we convert omission failure model into link state model to make faulty detection possible. Through analyzing message passing mechanism in the distributed system with n agents, among which t agents may commit omission failures, we provide the upper bound on message passing time for reaching consensus on a state among nonfaulty agents and message chain mechanism for validating messages. Then, we prove that our rational uniform consensus is a Nash equilibrium when n > 2 t + 1 , and failure patterns and initial preferences are blind (an assumption of randomness). Thus, agents have no motivation to deviate the consensus, which could provide interpretable stability for the algorithm in multiagent systems such as distributed energy systems. Our research strengthens the reliability of consensus with omission failures from the perspective of game theory.
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Задорнов, А. « Struggle for the Roman Inheritance : St. Emperor Justinian and King Theodoric ». Праксис, no 1(6) (15 juin 2021) : 76–83. http://dx.doi.org/10.31802/praxis.2021.6.1.005.
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В статье прослеживается разница в отношении классического римского наследия между византийским василевсом св. Юстинианом Великим и королём остготов Теодорихом. Эта разница проявляется как в официальной риторике, так и в правовом творчестве этих правителей. Именно нежелание Теодориха активно вводить римские правовые элементы в законодательство своего государства стало одной из причин неудачи интеграции италиков (коренного латинского населения) в структуры остготского королевства. Будучи зеркальным отражением «византийского синтеза» (с его элементами – римским правом, греческим языком, православным христианством), государство Теодориха не могло выдержать конкуренции с подлинным наследником Древнего Рима. The article shows the difference in relation to the classical Roman heritage between the Byzantine Vasileus of St. Justinian the Great and the King of the Ostrogoths Theodoric. This difference is manifested both in official rhetoric and in the legal work of these rulers. It was Theodoric’s unwillingness to actively introduce Roman legal elements into the legislation of his state that became one of the reasons for the failure to integrate the Italians (indigenous Latin population) into the structures of the Ostrogothic kingdom. Being a mirror reflection of the “Byzantine synthesis” (Roman law, Greek language, Orthodoxy), the state of Theodoric could not withstand competition with the true heir to ancient Rome.
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G.K.Sandhia, S. Nithyaselvakumari, V. Saidulu, Nor Hissam B. Sulaiman et Anas A. Salameh. « Enhancing the Security of Software Defined Mobile Networks (SDMN) based on Blockchain Technology ». International Journal of Interactive Mobile Technologies (iJIM) 17, no 04 (23 février 2023) : 117–33. http://dx.doi.org/10.3991/ijim.v17i04.37807.
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The blockchain involves future developments and new technologies. The emergence of a blockchain is a challenge for the conventional social organization and mode of activity. Data latency and mobile network capacity would no longer be a limitation for mobile users in next-generation networks of Software Defined Mobile Networks (SDMN). But there are many benefits to Software Defined Mobile Networking, it also contributes to certain security problems like DDoS / DoS attacks, unauthorized access, and single data point error. To enhance the security and privacy of the SDMN control plane, this paper proposes a new SDMN-based “Simplified Byzantine Fault Tolerance (SBFT)” algorithm to send signals between controllers and also set up an analysis study to investigate SBFT's security and results. However, there are many benefits of Software Defined Mobile Networking (SDMN), and then it helps to resolve other security concerns including DDoS / DoS attacks, unauthorized access, and single point failure. Blockchain, an evolving revolutionary technology, will offer creative approaches to address security issues in Software-Defined Mobile networks in an efficient way. This study proposes an SDMN-based Simplified Byzantine Fault Tolerance (SBFT) for enhancing the mobile network's security and privacy.
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Darabus, Carmen. « Bizanțul în filtrul balcanic – poezie română din a doua jumătate a secolului XX / Byzantium in Balkanic filter – Romanian poetry in the second part of twentieth century ». Swedish Journal of Romanian Studies 3, no 1 (17 avril 2020) : 64–70. http://dx.doi.org/10.35824/sjrs.v3i1.20416.
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Talking about Balkanism in Romanian contemporary poetry means to betray, to a certain extent required by degradation or alteration, some literary themes and motifs. Finding ourselves in a geographical area of cultural contaminations, the influence of other peoples in Balkans comes naturally: the nostalgia of Byzantium perfection, continuous reporting at an ideal time, abstraction of the chronology. Balkan themes and motives in poetry are identifiable from the early writings of Romanian literature, including the folklore, with Anton Pann, the Vacarescu and Conachi poets – and their ludic descriptivism – , to Ion Barbu, who strikes a metaphysical note in the Balkan motifs, and later, in the second part of twentieth century, with the species of parody. The Romanian native receptivity allowed continuous assimilations without creating an unpleasant heterogeneous feeling. This openness has contributed decisively in a formative way to bring Byzantium on a new soil in a perfect and saturated array; the perfectibility is not possible anymore, so the failure was natural, in a degraded status – Constantinople. Oriental-Byzantine gravity becomes in Oriental-Balkan tragedy or comedy, balance slid to one extreme, sometime becoming ridiculous. Contemporary poetry does not express any more a true lament, but a kind of parody (in ludic poetry) or sheer contempt (in the solemn poetry). The Balkan intelligence is not critical, but creative, with the risk of perpetuating monstrous forms, beyond good and evil. Byzantium established itself through a double filter – for the East and for the West – influencing and being influenced, in turn. Romanian poetry has the full sequence of themes and aesthetic formulae, from tragic to comic, often switching rapidly from one edge to the other, taking into account the old Thracian solemn part, then the proud Byzantium and its absorption in Constantinople – all rolling in a series of formal expressions reflected in themes and vocabulary.
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Mustafa, Ali, Muhammad Najam Ul Islam et Salman Ahmed. « Dynamic Spectrum Sensing Under Crash and Byzantine Failure Environments for Distributed Convergence in Cognitive Radio Networks ». IEEE Access 9 (2021) : 23153–67. http://dx.doi.org/10.1109/access.2021.3053254.
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Li, Qiong, Wennan Wang, Yizhao Zhu et Zuobin Ying. « BOppCL : Blockchain-Enabled Opportunistic Federated Learning Applied in Intelligent Transportation Systems ». Electronics 13, no 1 (28 décembre 2023) : 136. http://dx.doi.org/10.3390/electronics13010136.
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In this paper, we present a novel blockchain-enabled approach to opportunistic federated learning (OppCL) for intelligent transportation systems (ITS). Our approach integrates blockchain with OppCL to streamline the learning of autonomous vehicle models while addressing data privacy and trust challenges. We deploy resilient countermeasures, incentivized mechanisms, and a secure gradient distribution to combat single-point failure verification attacks. Additionally, we integrate the Byzantine fault-tolerant algorithm (BFT) into the node verification component of the delegated proof of stake (DPoS) to minimize verification delays. We validate our approach through experiments on the MNIST, SVHN, and CIFAR-10 datasets, showing convergence rates and prediction accuracy comparable to traditional OppCL approaches.
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Hena, M., et N. Jeyanthi. « A Three-Tier Authentication Scheme for Kerberized Hadoop Environment ». Cybernetics and Information Technologies 21, no 4 (1 décembre 2021) : 119–36. http://dx.doi.org/10.2478/cait-2021-0046.
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Abstract Apache Hadoop answers the quest of handling Bigdata for most organizations. It offers distributed storage and data analysis via Hadoop Distributed File System (HDFS) and Map-Reduce frameworks. Hadoop depends on third-party security providers like Kerberos for its security requirements. Kerberos by itself comes with many security loopholes like Single point of Failure (SoF), Dictionary Attacks, Time Synchronization and Insider Attacks. This paper suggests a solution that aims to eradicate the security issues in the Hadoop Cluster with a focus on Dictionary Attacks and Single Point of Failure. The scheme roots on Secure Remote Password Protocol, Blockchain Technology and Threshold Cryptography. Practical Byzantine Fault Tolerance mechanism (PBFT) is deployed at the blockchain as the consensus mechanism. The proposed scheme outperforms many of the existing schemes in terms of computational overhead and storage requirements without compromising the security level offered by the system. Riverbed Modeller (AE) Simulation results strengthen the aforesaid claims.
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Kumar T, Satish, Madhusudhan H S, S. M. F. D. Syed Mustapha, Punit Gupta et Rajan Prasad Tripathi. « Intelligent Fault-Tolerant Mechanism for Data Centers of Cloud Infrastructure ». Mathematical Problems in Engineering 2022 (8 février 2022) : 1–12. http://dx.doi.org/10.1155/2022/2379643.
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Fault tolerance in cloud computing is considered as one of the most vital issues to deliver reliable services. Checkpoint/restart is one of the methods used to enhance the reliability of the cloud services. However, many existing methods do not focus on virtual machine (VM) failure that occurs due to the higher response time of a node, byzantine fault, and performance fault, and existing methods also ignore the optimization during the recovery phase. This paper proposes a checkpoint/restart mechanism to enhance reliability of cloud services. Our work is threefold: (1) we design an algorithm to identify virtual machine failure due to several faults; (2) an algorithm to optimize the checkpoint interval time is designed; (3) lastly, the asynchronous checkpoint/restart with log-based recovery mechanism is used to restart the failed tasks. The valuation results obtained using a real-time dataset shows that the proposed model reduces power consumption and improves the performance with a better fault tolerance solution compared to the nonoptimization method.
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Goula, Konstantina, Theodora Fragkou, Ourania Drakoulogkona et Athanasios Diamandopoulos. « FP909POSSIBLE DESCRIPTIONS OF PATIENTS WITH METABOLIC ACIDOSIS DUE TO RENAL FAILURE ACCORDING TO ANCIENT GREEK AND BYZANTINE WRITINGS ». Nephrology Dialysis Transplantation 30, suppl_3 (mai 2015) : iii379—iii380. http://dx.doi.org/10.1093/ndt/gfv186.10.
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Firdaus, Muhammad, et Kyung-Hyune Rhee. « On Blockchain-Enhanced Secure Data Storage and Sharing in Vehicular Edge Computing Networks ». Applied Sciences 11, no 1 (4 janvier 2021) : 414. http://dx.doi.org/10.3390/app11010414.
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The conventional architecture of vehicular ad hoc networks (VANETs) with a centralized approach has difficulty overcoming the increasing complexity of intelligent transportation system (ITS) applications as well as challenges in providing large amounts of data storage, trust management, and information security. Therefore, vehicular edge computing networks (VECNets) have emerged to provide massive storage resources with powerful computing on network edges. However, a centralized server in VECNets is insufficient due to potential data leakage and security risks as it can still allow a single point of failure (SPoF). We propose consortium blockchain and smart contracts to ensure a trustworthy environment for secure data storage and sharing in the system to address these challenges. Practical byzantine fault tolerance (PBFT) is utilized because it is suitable for consortium blockchain to audit publicly, store data sharing, and records the whole consensus process. It can defend against system failures with or without symptoms to reach an agreement among consensus participants. Furthermore, we use an incentive mechanism to motivate the vehicle to contribute and honestly share their data. The simulation results satisfy the proposed model’s design goals by increasing vehicular networks’ performance in general.
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Jiang, Wangxi, Xiaoxiong Wu, Mingyang Song, Jiwei Qin et Zhenhong Jia. « Improved PBFT Algorithm Based on Comprehensive Evaluation Model ». Applied Sciences 13, no 2 (13 janvier 2023) : 1117. http://dx.doi.org/10.3390/app13021117.
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Blockchain technology is well known due to the advent of Bitcoin. With the development of recent years, blockchain technology has been widely used in medicine, digital currency, energy, etc. The practical Byzantine fault-tolerant (PBFT) algorithm is a consensus algorithm widely used in consortium blockchains. Aiming to address the problems of the PBFT algorithm, low consensus efficiency due to high communication complexity, and malicious behavior of the primary node leading to consensus failure, an improved PBFT algorithm based on a comprehensive evaluation model (TB-PBFT) is proposed. First, nodes are divided into several groups based on the multi-formation control strategy of an unmanned aerial vehicle (UAV) cluster, which significantly reduces the communication complexity. Second, a comprehensive evaluation model combining the entropy method, TOPSIS method, and Borda count is proposed, which uses the behavior of nodes as an evaluation index, and the comprehensive score of nodes is obtained according to the preferences of other nodes. Finally, the highest ranking node is selected as the primary node through the comprehensive evaluation model to ensure the security and stability of the blockchain network. We analyze TB-PBFT algorithms and compare them with other Byzantine fault tolerance algorithms. Theoretical analysis and simulation results show that the TB-PBFT algorithm can improve node scalability and fault tolerance and reduce communication complexity and view switching probability. We also prove that the comprehensive evaluation model can improve the consensus success rate of the algorithm, and the feasibility and effectiveness of the improved consensus algorithm are verified. Hence, it can be applied to the consortium blockchain system effectively and efficiently.
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Stavi, Ilan, Tamir Rozenberg, Ashraf Al-Ashhab, Eli Argaman et Elli Groner. « Failure and Collapse of Ancient Agricultural Stone Terraces : On-Site Effects on Soil and Vegetation ». Water 10, no 10 (9 octobre 2018) : 1400. http://dx.doi.org/10.3390/w10101400.
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Ancient agricultural stone terraces, dated to the Roman and Byzantine ages, are prevalent across the Negev drylands of Southern Israel. The goal of these structures was to reduce hydrological connectivity by harvesting water runoff and controlling soil erosion, thus allowing cultivation of cereals. Land abandonment and the lack of maintenance have led to the failure and collapse of many of these stone terraces. The objective of this study was to assess the effect of failure and collapse of terraces on the on-site (on-field) geo-ecosystem functioning, as determined by vegetation cover and soil quality parameters. This was achieved by studying vegetal and soil properties in shrubby vegetation patches and inter-shrub spaces of intact-terrace plots and collapsed-terrace plots, as well as in the surrounding ‘natural’ lands. Mean cover of both shrubby and herbaceous vegetation was highest in intact terraces, intermediate in ‘natural’ lands, and lowest in collapsed terraces. The overall soil quality followed the same trend as the vegetation cover. Additionally, this study shows that the anthropogenic impact on geo-ecosystem functioning can be either beneficial or detrimental. While well maintained stone terraces benefit the soil and vegetation, abandoned and unmaintained terraces may result in accelerated soil erosion and land degradation.
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AZADMANESH, AZAD, AXEL W. KRINGS et BAHADOR GHAHRAMANI. « GLOBAL CONVERGENCE IN PARTIALLY FULLY CONNECTED NETWORKS (PFCN) WITH LIMITED RELAYS ». International Journal of Information Technology & ; Decision Making 02, no 02 (juin 2003) : 265–85. http://dx.doi.org/10.1142/s021962200300063x.
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In a distributed system, it is often necessary for nodes to agree on a particular event or to coordinate their activities. Applications of distributed agreement are many, such as Commit Protocols in distributed database systems, selection of a monitor node in a distributed system, detecting an intruder, or agreeing on the malicious behavior of a node. Among many forms of Distributed Agreement, one form is called Approximate Agreement (AA), in which the nodes, by exchanging their local values with other nodes, need to agree on values which are approximately equal to each other. Research on AA for fully connected networks is relatively mature. In contrast, the study of AA in partially connected networks has been very limited. More specifically, no general solution to the AA problem exists for such networks. This research solves the AA problem for a specific, scalable, partially connected network with limited relays. The research considers the worst failure mode of nodes, called Byzantine, and hybrid failure modes. The results show low communication cost in comparison to fully connected networks. The network is designed to take advantage of the results available for fully connected networks. Thus, the analysis for obtaining the expressions for Convergence Rate and Fault Tolerance becomes relatively easy.
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Song, Anping, et Cenhao Zhou. « FlexBFT : A Flexible and Effective Optimistic Asynchronous BFT Protocol ». Applied Sciences 14, no 4 (10 février 2024) : 1461. http://dx.doi.org/10.3390/app14041461.
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Currently, integrating partially synchronous Byzantine-fault-tolerant protocols into asynchronous protocols as fast lanes represents a trade-off between robustness and efficiency, a concept known as optimistic asynchronous protocols. Existing optimistic asynchronous protocols follow a fixed path order: they execute the fast lane first, switch to the slow lane after a timeout failure, and restart the fast lane after the slow lane execution is completed. However, when confronted with prolonged network fluctuations, this fixed path sequence results in frequent failures and fast lane switches, leading to overhead that diminishes the efficiency of optimistic asynchronous protocols compared with their asynchronous counterparts. In response to this challenge, this article introduces FlexBFT, a novel and flexible optimistic asynchronous consensus framework designed to significantly enhance overall consensus performance. The key innovation behind FlexBFT lies in the persistence of slow lanes. In the presence of persistent network latency, FlexBFT can continually operate round after round within the slow lane—the current optimal path—until the network conditions improve. Furthermore, FlexBFT offers the flexibility to combine consensus modules adaptively, further enhancing its performance. Particularly in challenging network conditions, FlexBFT’s experimental outcomes highlight its superiority across a range of network scenarios compared with state-of-the-art algorithms. It achieves a performance with 31.6% lower latency than BDT, effectively merging the low latency characteristic of deterministic protocols with the robustness inherent in asynchronous protocols.
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Liu, Jian, Wenlong Feng, Yu Zhang et Feiyang He. « Improvement of PBFT Algorithm Based on CART ». Electronics 12, no 6 (20 mars 2023) : 1460. http://dx.doi.org/10.3390/electronics12061460.
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In response to the problems of the practical Byzantine fault-tolerant algorithm (PBFT), such as random selection of master nodes and poor scalability, a CART-based PBFT optimization algorithm is proposed, namely the C-PBFT algorithm. First, the introduction of weighted impurity variables improves the CART algorithm, overcomes the mutual influence of attributes between nodes, and improves the classification accuracy. Secondly, through the point grouping mechanism, the nodes are divided into three types: consensus nodes, candidate nodes, and alternate nodes, which are dynamically adjusted based on node behavior to ensure the reliability of consensus nodes. Finally, the voting weight is introduced into the consensus node, and the consensus is reached by using the voting weight exceeding the threshold, which reduces the message transmission in the blockchain network and improves the efficiency of the algorithm operation. The experimental results show that the improved consensus algorithm has better performance in terms of delay, throughput, and fault tolerance and reduces the frequent switching of views caused by the failure of the master node.
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Kushch, Tatiana. « The Tunic of Christ and the Crown Jewels : Relics in the Byzantine Diplomacy of the Fourteenth Century ». Vestnik Volgogradskogo gosudarstvennogo universiteta. Serija 4. Istorija. Regionovedenie. Mezhdunarodnye otnoshenija 26, no 6 (28 décembre 2021) : 161–70. http://dx.doi.org/10.15688/jvolsu4.2021.6.14.
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ntroduction. This article discusses the “reliquary diplomacy” introduced by Emperor Manuel II Palaiologos during the Ottoman siege of Constantinople (1394–1402). The emperor widely used the relics in the creation of the anti-Ottoman alliance. This article addresses a specific case of this diplomatic practice, Manuel II Palaiologos’ request to Venice for a loan for the deposit on the Tunic of Christ and other relics. Methods. From the juxtaposition of sources and the comparative analysis of the fourteenth-century relations between Byzantium and Venice there are good reasons to discover the motives behind the Venetians’ denial of the emperors’ proposal. Analysis. After 1261 Constantinople kept numerous relics, particularly the Seamless Tunic of Christ and the Purple Robe. The sources in possession do not allow an unequivocal conclusion if the artifact offered to the Venetians was the Seamless Tunic or another one. In the author’s interpretation, the reason of Venice’s withdrawal from the deal was the empire’s bad “credit history.” In August 1343, the Senate of Venice gave credit of 30,000 gold ducats to the Empress Anna of Savoy for the deposit of the jewels of the crown. The Venetians permanently reminded Byzantium about the repayment of the debt and the ransom for the jewels, and, moreover, offered to take the island of Tenedos as a compensation. Therefore, the unsolved problem of the old debt made the new deal with the emperor hopeless in the Venetians’ eyes. Results. The case under analysis sheds light on the state of the Empire in the late fourteenth century. Manuel II Palaiologos put into the “diplomatic circulation” the relics which were convertible in the Christian West. The failure of his negotiations with Venice turned him to active search for other allies, whom he sent parts of the Tunic of Christ in order to gain their military and financial support.
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Wang, Rong, et Wei-Tek Tsai. « Asynchronous Federated Learning System Based on Permissioned Blockchains ». Sensors 22, no 4 (21 février 2022) : 1672. http://dx.doi.org/10.3390/s22041672.
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The existing federated learning framework is based on the centralized model coordinator, which still faces serious security challenges such as device differentiated computing power, single point of failure, poor privacy, and lack of Byzantine fault tolerance. In this paper, we propose an asynchronous federated learning system based on permissioned blockchains, using permissioned blockchains as the federated learning server, which is composed of a main-blockchain and multiple sub-blockchains, with each sub-blockchain responsible for partial model parameter updates and the main-blockchain responsible for global model parameter updates. Based on this architecture, a federated learning asynchronous aggregation protocol based on permissioned blockchain is proposed that can effectively alleviate the synchronous federated learning algorithm by integrating the learned model into the blockchain and performing two-order aggregation calculations. Therefore, the overhead of synchronization problems and the reliability of shared data is also guaranteed. We conducted some simulation experiments and the experimental results showed that the proposed architecture could maintain good training performances when dealing with a small number of malicious nodes and differentiated data quality, which has good fault tolerance, and can be applied to edge computing scenarios.
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Chen, Hu. « Dilemmas in Digital Forensics for Computer Equipment Security and Maintenance in Remote Ships ». Advanced Materials Research 490-495 (mars 2012) : 1382–86. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.1382.
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As remote ships have equipped a large number of computer equipments, the maintenance of such equipments confronts a great challenge. Since some embedded devices among them may be hacked by attackers or disabled by Byzantine failure, to discover the attacking originality and fault source present foremost importance. In this article, we discuss digital investigation and forensics as a general viewpoint. We point out some dilemmas that hinder the development of digital forensics, some of which may be fundamental problems. We propose to expand the concept of digital forensics to a wider scope so as to include digital investigation for information instead of only evidence. We also argue that the fostering of novel contributions should be relied on technical experts instead of law experts as emerging new techniques always result in new digital crimes. We promote the divorce between the technical experts who focus on the contribution of technologies, and legal authorities who are responsible to bridge the gap between technologies and standard/formalization. Digital forensics methods are encouraged to be publicly available, but the contributors should be aware of the possibility of anti-forensics.
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Schabel, Chris. « The Myth of the White Monks' “Mission to the Orthodox” : Innocent III, the Cistercians, and the Greeks ». Traditio 70 (2015) : 237–61. http://dx.doi.org/10.1017/s0362152900012381.
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In the early thirteenth century, numerous Cistercian monasteries were founded in the former Byzantine territories conquered in the context of the Fourth Crusade. According to the standard narrative, put forth in the 1970s, Pope Innocent III sent the Cistercians on a “mission to the Orthodox,” but the mission was a failure, because the White Monks soon abandoned almost all of their houses in Frankish Greece and Constantinople without having “converted” the Greeks. In the light of recent research on the aftermath of 1204 and on the Cistercian Order, this paper argues that the Frankish rulers took the initiative to found Cistercian monasteries in the Greek East for the same reason that they did so in the Latin West: to cater to the Latin rite aristocracy. This Cistercian mission was a success, since the Cistercian establishments in Greece generally existed as long as the Western nobility survived to patronize and protect them. There is no evidence that Innocent intended the Cistercians to be missionaries in Romania since, contrary to a once common assumption, the papacy did not view the Greeks as requiring the same kind of missionary activity that was deemed necessary in lands inhabited by pagans or heretics.
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Son, Minsung, et Heeyoul Kim. « Novel Lightweight Consensus Protocol for Reaching Blockchain Consensus in Low Bandwidth Network Environment ». International Journal of Emerging Technology and Advanced Engineering 13, no 3 (1 mars 2023) : 117–26. http://dx.doi.org/10.46338/ijetae0323_12.
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As blockchain technology makes rapid progress, attempts to use it in various environments are also increasing. Especially home networks and smart factories consisting of a small network of Internet of Things (IoT) devices with singlehop or a few hops are trying to adopt blockchain systems to guarantee the integrity of data and to protect privacy. However, in such low-bandwidth network environments, they encounter challenges because of the network cost for block consensus. This study proposes a lightweight blockchain consensus protocol suitable for these environments. The proposed protocol improves the existing PBFT protocol to reduce the network cost required for consensus. The main innovation is to reduce the number of phases for consensus from three phases to two phases while preserving Byzantine failure tolerance. These two phases guarantee the total order of clients’ transactions in the same view. And the simple viewchange process in the proposed protocol enables the change of the primary node for new block generation. The experimental result shows a significant performance improvement of block consensus over the PBFT. Using the proposed protocol can contribute to operating blockchain systems in various lowbandwidth network environments. Keywords—blockchain, consensus protocol, lightweight protocol, low bandwidth network, PBFT
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Karchagin, Evgeniy, Svetlana Tokareva et Dmitriy Yavorskiy. « The Concepts of Justice and Piety in the Byzantine Political and Philosophical Thought of the 4th Century ». Vestnik Volgogradskogo gosudarstvennogo universiteta. Serija 4. Istorija. Regionovedenie. Mezhdunarodnye otnoshenija 26, no 6 (28 décembre 2021) : 224–35. http://dx.doi.org/10.15688/jvolsu4.2021.6.18.
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Introduction. The article analyzes the transformations of the concept of justice in early Byzantine thought. The purpose of the article is to test the hypothesis that the semantic shifts in the meaning of the concept of justice in the philosophical and theological literature were due to political processes and events. Methods. The article analyzes the political philosophical and political theological texts of the fourth century: “Oration in Honor of Constantine on the Thirtieth Anniversary of His Reign” by Eusebius of Caesarea; “Panegyric in Honour of Constantius” and “The Heroic Deeds of Constantius” by emperor Julian (“The Apostate”); “On Kingship” by Synesius of Cyrene. In the course of the analysis, the methodological tools of the history of concepts were used. Analysis. The analysis revealed a conflict between the concepts of “justice” and “piety”. It was found that the analyzed texts violate the ancient political and philosophical correlation of these concepts in which piety is considered as a form of justice. In the texts of Eusebius of Caesarea, piety is presented as a particular virtue without any connection with justice. Moreover, the frequency of using the concept of “piety” in the sense of the ruler’s virtue significantly exceeds the frequency of using the concept of “justice” in the sense of political virtue. In the texts of the Emperor Justinian, the discursive status of “justice” is restored. However, in the political philosophy of Synesius of Cyrene, the correlation of the concepts of “justice” and “piety” prescribed by Eusebius of Caesarea is fixed. Results. These processes is due to the influence of religious discourse on political one which is quite understandable in the works of theologians, on the one hand, and the crisis of polis and republican political technologies and discourses in the situation of increasing complexity of administrative tasks faced by the Roman emperors of the 4th century, on the other hand which subsequently led to the formation of a specific Byzantine “taxis” – a socio-cultural order. In this regard, the texts of Emperor Julian can be considered as an unsuccessful attempt to restore the previous discourse, an attempt to restore justice to a dominant place among the virtues of the ruler. The failure of this attempt is attested from the texts of Synesius of Cyrene. All the above allows us to conclude that a new Christian-imperial political discourse is being generated in the corpus of philosophical and theological texts in which the concept of justice is given a relatively modest place.
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Jagdish, Mukta, Amelec Viloria, Jesus Vargas, Omar Bonerge Pineda Lezama et David Ovallos-Gazabon. « Modeling software architecture design on data storage security in cloud computing environments ». Journal of Intelligent & ; Fuzzy Systems 39, no 6 (4 décembre 2020) : 8557–64. http://dx.doi.org/10.3233/jifs-189172.
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Cloud-based computation is known as the source architecture of the upcoming generation of IT enterprise. In context to up-coming trade solutions, the Information Technology sections are established under logical, personnel, and physical control, it transfers application software and large database to appropriate data centers, where security and management of database with services are not trustworthy fully. So this process may face many challenges towards society and organizations and that not been well understood over a while duration. This becomes one of the major challenges days today. So in this research, it focuses on security-based data storage using cloud, which plays one of the important aspects bases on qualities of services. To assure user data correctness in the cloud system, a flexible and effective distributed technique with two different salient features was examined by utilizing the token called homomorphic with erasure-coded data for distributed verification, based on this technique it achieved error data localization and integration of storage correctness. Also, it identifies server misbehaving, efficient, and security-based dynamic operations on data blocking such as data append, delete, and update methods. Performance analysis and security show the proposed method is more effective resilient and efficient against Byzantine failure, even server colluding attacks and malicious data modification attacks.
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Arya, Mukesh Kumar, et Namit Gupta. « Adoptive Cloud Application in Semantic Web ». International Journal of Advance Research and Innovation 2, no 2 (2014) : 48–51. http://dx.doi.org/10.51976/ijari.221407.
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Cloud computing has been envisioned as the next-generation architecture of IT enterprise. In contrast to traditional solutions, where the IT services are under proper physical, logical and personnel controls, cloud computing moves the application software and databases to the large data centers, where the management of the data and services may not be fully trustworthy. This unique attribute, however, poses many new security challenges which have not been well understood. In this article, we focus on cloud data storage security, which has always been an important aspect of quality of service. To ensure the correctness of users' data in the cloud, we propose an effective and flexible distributed scheme with two salient features, opposing to its predecessors. By utilizing the homomorphic token with distributed verification of erasure-coded data, our scheme achieves the integration of storage correctness insurance and data error localization, i.e., the identification of misbehaving server (s). Unlike most prior works, the new scheme further supports secure and efficient dynamic operations on data blocks, including: data update, delete and append. Extensive security and performance analysis shows that the proposed scheme is highly efficient and resilient against Byzantine failure, malicious data modification attack, and even server colluding attacks.
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Liu, Song, Xiong Wang, Longshuo Hui et Weiguo Wu. « Blockchain-Based Decentralized Federated Learning Method in Edge Computing Environment ». Applied Sciences 13, no 3 (28 janvier 2023) : 1677. http://dx.doi.org/10.3390/app13031677.
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In recent years, federated learning has been able to provide an effective solution for data privacy protection, so it has been widely used in financial, medical, and other fields. However, traditional federated learning still suffers from single-point server failure, which is a frequent issue from the centralized server for global model aggregation. Additionally, it also lacks an incentive mechanism, which leads to the insufficient contribution of local devices to global model training. In this paper, we propose a blockchain-based decentralized federated learning method, named BD-FL, to solve these problems. BD-FL combines blockchain and edge computing techniques to build a decentralized federated learning system. An incentive mechanism is introduced to motivate local devices to actively participate in federated learning model training. In order to minimize the cost of model training, BD-FL designs a preference-based stable matching algorithm to bind local devices with appropriate edge servers, which can reduce communication overhead. In addition, we propose a reputation-based practical Byzantine fault tolerance (R-PBFT) algorithm to optimize the consensus process of global model training in the blockchain. Experiment results show that BD-FL effectively reduces the model training time by up to 34.9% compared with several baseline federated learning methods. The R-PBFT algorithm can improve the training efficiency of BD-FL by 12.2%.
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Nikitin, Valentin. « Metropoliet Isodoor van Moskou en het russische cesaropapisme ». Het Christelijk Oosten 45, no 1 (29 novembre 1993) : 4–14. http://dx.doi.org/10.1163/29497663-04601003.
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Metropolitan Isidor of Moscow and Russian Caesaropapism Moscovian Russia inherited the caesaropapism in the church-state relations from the Byzantine empire. This caesaropapism appeared for the first time when grand-duke Vasili II of Moscow deposed metropolitan Isidor after his return from the council in Florence. The later Russian sources on this council are highly tendentious. Unpartial study of the primary sources shows that Isidor was not the only Russian in favour of the union. Neither was the union as such the direct reason for his deposition. The reading of the bull in the Uspensky cathedral was quietly listened to by Vasili II, who of course knew of the result of the council. It was the insertion of the name of the pope in the Orthodox liturgy which aroused the anger of the people and the grand-duke. The author deplores the failure of the union of the Orthodox and Catholic churches. This union is a necessary condition for the survival of christianity in the modern world and for an authentic religious revival in Russia. In the commentary to the article of V. Nikitin, W. van den Bercken deals with the criticism which Nikitinʼs pro-Catholic article, originally published in Russkaya Mysl, received in conservative media, inclusive in the Journal of the Moscow Patriarchate, of which Nikitin was a collaborator. Now the author is working at the more ecumenically oriented Department for Religious Education and Catechesis of the Moscow Patriarchate.
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Miller, Ryan. « Nonrational Belief Paradoxes as Byzantine Failures ». Logos & ; Episteme 13, no 4 (2022) : 343–58. http://dx.doi.org/10.5840/logos-episteme202213430.
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David Christensen and others argue that Dutch Strategies are more like peer disagreements than Dutch Books, and should not count against agents‘ conformity to ideal rationality. I review these arguments, then show that Dutch Books, Dutch Strategies, and peer disagreements are only possible in the case of what computer scientists call Byzantine Failures—uncorrected Byzantine Faults which update arbitrary values. Yet such Byzantine Failures make agents equally vulnerable to all three kinds of epistemic inconsistencies, so there is no principled basis for claiming that only avoidance of true Dutch Books characterizes ideally rational agents. Agents without Byzantine Failures can be ideally rational in a very strong sense, but are not normative for humans.
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ATTIYA, HAGIT, et AMIR BAR-OR. « SHARING MEMORY WITH SEMI-BYZANTINE CLIENTS AND FAULTY STORAGE SERVERS ». Parallel Processing Letters 16, no 04 (décembre 2006) : 419–28. http://dx.doi.org/10.1142/s0129626406002745.
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This paper presents fault-tolerant simulations of a single-writer multi-reader regular register in storage systems. One simulation tolerates fail-stop failures of storage servers and requires a majority of nonfaulty servers, while the other simulation tolerates Byzantine failures and assumes that two-thirds of the servers are nonfaulty. A construction of Afek et al. [3] is used to mask semi-Byzantine failures of clients that result in erroneous write operations. The simulations are used to derive Paxos algorithms that tolerate semi-Byzantine failures of clients as well as fail-stop or Byzantine failures of storage servers.
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Radicevic, Dejan. « The periodisation of IX-XI century necropoles in the lower Serbian Danube river basin ». Starinar, no 57 (2007) : 349–62. http://dx.doi.org/10.2298/sta0757349r.
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It is extremely difficult to periodise the IX-XI century necropoles in the lower Serbian Danube river basin because not enough research has been done on them. Our knowledge is mainly limited to individual graves or to graveyards that have partly been investigated. An examination of the necropolis in Grabovica provided most of the data for establishing the chronology for the graves in Mihajlovac and Prahovo. Besides finds that were identical to the specimens from Grabovica, the graves in Mihajlovac and Prahovo contained finds of earrings, indicating that they may be slightly older than the graves in Grabovica and that burials in those graveyards may have ceased in the first half of the X century. This was a time when the threat of Magyar invasion existed on the right bank of the Danube, downstream from the confluence with the Morava. The graveyard in Grabovica was obviously still in use for a little longer, however, the fact that burials stopped there could have only been connected with the events that led to the end of Bulgarian and reestablishment of Byzantine authority in the Danube river basin. The formation of the necropoles in Korbovo and Kostol may have occurred roughly around that time, given the increased frequency of finds connected with the growing influence of Byzantium. Burials next to the defence wall of the fortifications in Kostol may have begun during the last decades of the X century. The unusual position of the necropolis, right next to the fortress defence wall, indicates that this graveyard was probably formed in wartime circumstances. Otherwise, a more suitable place would have been used for burials, of the kind that certainly must have existed in the neighbourhood of the fortress. One could extend the period of burying the deceased in Kostol and Korbovo to the last quarter of the XI century, at most. The later graveyards in this region are characterised by types of finds that were not discovered in earlier graveyards. An important event at that time, the uprising in 1072, could be the reason for this change in the inventory of grave finds. Earlier literature describes how life ceased in several fortresses downstream from the confluence with the Morava because of that event. It was assumed that the local Slav population had taken part in the uprising, therefore, after its failure, the inhabitants of the Danubian towns, in Djerdap and downstream, were deported or abandoned the fortresses of their own accord.
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Gustafsson, Henrik. « Screen Violence from Settler Colonialism to Cognitive Capitalism ». Afterimage 49, no 3 (1 septembre 2022) : 23–45. http://dx.doi.org/10.1525/aft.2022.49.3.23.
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While the HBO show Westworld (2016–present, created by Lisa Joy and Jonathan Nolan) has gained much critical attention for its byzantine plotting and philosophical conundrums, the present discussion focuses instead on the basic premise on which the titular park operates, namely that the algorithms that govern human behavior can be disclosed by studying how human beings behave toward image beings. Under the guise of a tactile experience of a make-believe past, the park attractions clandestinely function as a large behavioral sensor, extracting actionable data from the guests who reveal their inner drives when interacting with the host environment. Taking its cue from the opening titles of the first season, the argument pivots on the master trope of the series: the machine-readable scroll of perforated paper that commands the automated performance of the player piano. This motif is examined through a double-pronged approach that aligns the anthropology of images developed by Hans Belting, which understands the relation between humans and images as the interactions between “hosts” and “guests,” with the archaeology of media and its dominant concern to uncover the prehistory of the automated control systems of the computer age. While Westworld proffers a timely allegory of biopolitical capture along the digital frontier, the show ultimately testifies to the failure to constructively engage with the precarious relation between hosts and guests that to an equal extent defines our contemporary moment. The initial problem raised by Westworld, the ethics of killing virtual beings, thus gives rise to a broader historical inquiry that concerns the inability of human societies to face the past and deal with the images they inherit.
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Maurer, Alexandre, et Sebastien Tixeuil. « Containing Byzantine Failures with Control Zones ». IEEE Transactions on Parallel and Distributed Systems 26, no 2 (1 février 2015) : 362–70. http://dx.doi.org/10.1109/tpds.2014.2308190.
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Maksimovic, Ljubomir. « Berroia in Stefan Dusan's politics ». Zbornik radova Vizantoloskog instituta, no 41 (2004) : 341–52. http://dx.doi.org/10.2298/zrvi0441341m.
Texte intégralRésumé :
Being one of the most important cities in Macedonia, Berroia automatically entered the horizon of Serbian politics once Stefan Dusan got involved into the Byzantine Civil War during the forties of the fourteenth century. The King's previous invasion of Macedonia, in the thirties, had been aimed directly towards Thessalonica and was a failure. Thus, in the second phase of his politics, in which Macedonia was used as a backing in the striving for the Empire, Thessalonica was temporarily left aside, although not before first Serres and then Berroia had been captured, so as to leave it completely isolated. Initially, it was Serres rather than Berroia that Dusan was focused on, its conquest in September 1345 leading immediately to the proclamation of the Empire. Afterwards ? in the first half of 1346 ? Berroia was also conquered and turned into an important Serbian stronghold, Thessalonica being thus cut off, which enabled the Serbs to await a more favorable time to capture it. At the same time, the conquest of Berroia paved the way for the Serbian invasion of Epirus and Thessalia. Emperor John VI Cantacuzenus was certainly aware of the consequences of such a strategic constellation. Thus, when he finally managed to neutralize the Zelots in Thessalonica, his first move towards the change of the situation was to recuperate Berroia and surrounding towns. This was such a severe blow for the Serbs, that it immediately became clear that even Dusan's imperial power might be endangered if his position in Macedonia further weakened. He reacted promptly and recaptured Berroia and other strongholds he had lost. The conquest of Berroia was lead by the nobleman Radoslav Hlapen, who first acted as a governor on behalf of Dusan, and after the death of the Emperor practically as an independent ruler of that part of Macedonia.