The Effect of Microstructural Imperfections on Corrosion Fatigue of Additively Manufactured ER70S-6 Alloy Produced by Wire Arc Deposition

This study aims at evaluating the effect of microstructure imperfections on the corrosion fatigue performance of an ER70S-6 alloy produced by wire arc additive manufacturing (WAAM) process, in a 3.5% NaCl solution. For reference, a regular ST-37 alloy with relatively similar chemical composition was considered as a counterpart alloy. This was justified by the fact that the ER70S-6 alloy is usually used for conventional welding of ST-37 steel. The results obtained indicated that while the ST-37 alloy exhibited fatigue strength of 240 MPa in the corrosive solution, the additively manufactured ER70S-6 alloy showed fatigue strength of only 140 MPa. These differences were related to microstructural imperfections that are inherently produced during the WAAM process.</jats:p

Optimized Group Rekey for Group Communication systems

In this paper we describe an ecient algorithm for the management of group-keys. Our algorithm is based on a protocol for secure IP-multicast and is used to manage group-keys in group-communication systems. Unlike prior work, based on centralized key-servers, our solution is completely distributed and fault-tolerant and its performance is comparable to the centralized solution. 1 Introduction Increasingly many applications require multicast services, for example, teleconferencing, distributed interactive simulation, collaborative work. To protect multicast message content, such applications require secure multicast. A multicast group can be eciently protected using a single symmetric encryption key. This key is securely communicated to all group members which subsequentally use it to encrypt/decrypt group messages. The group-key is securely switched whenever the group membership changes, thereby preventing old members from eavesdropping on current group conversations. The challen..

The Architecture and Performance of Security Protocols in the EnsembleGroup Communication System

Ensemble is a Group Communication System built at Cornell and the Hebrew universities. It allows processes to create process groups within which scalable reliable fifo-ordered multicast and point-to-point communication are supported. The system also supports other communication properties, such as causal and total multicast ordering, flow control, etc. This paper describes the security protocols and infrastructure of Ensemble. Applications using Ensemble with the extensions described here benefit from strong security properties. Under the assumption that trusted processes will not be corrupted, all communication is secured from tampering by outsiders. Our work extends previous work performed in the Horus system (Ensemble's predecessor) by adding support for multiple partitions, efficient rekeying, and application defined security policies. Unlike Horus, which used its own security infrastructure with non-standard key distribution and timing services, Ensemble's security mechanism is based on off-the shelf authentication systems, such as PGP and Kerberos. We extend previous results on group rekeying, with a novel protocol that makes use of diamond-like data structures. Our Diamond protocol allows the removal of untrusted members within milliseconds

A Study of Group Rekeying

In this paper we study the key management problem, in the context of Group Communication Systems (GCS). GCSs are mid-sized systems, scaling up to 100 members. We present a side-by-side comparison of three ways of managing keys, studing bandwidth and latency

The architecture and performance of security protocols in the ensemble group communication system

Ensemble is a Group Communication System built at Cornell and the Hebrew universities. It allows processes to create process groups within which scalable reliable fifo-ordered multicast and point-to-point communication are supported. The system also supports other communication properties, such as causal and total multicast ordering, flow control, etc. This paper describes the security protocols and infrastructure of Ensemble. Applications using Ensemble with the extensions described here benefit from strong security properties. Under the assumption that trusted processes will not be corrupted, all communication is secured from tampering by outsiders. Our work extends previous work performed in the Horus system (Ensemble’s predecessor) by adding support for multiple partitions, efficient rekeying, and application defined security policies. Unlike Horus, which used its own security infrastructure with non-standard key distribution and timing services, Ensemble’s security mechanism is based on off-the shelf authentication systems, such as PGP and Kerberos. We extend previous results on group rekeying, with a novel protocol that makes use of diamond-like data structures. Our Diamond protocol allows the removal of untrusted members within milliseconds

A Study of Group Rekeying

In this paper we study the key management problem, in the context of Group Communication Systems (GCS). GCSs are mid-sized systems scaling up to 100 members. We present a side-by-side comparison of three ways of managing keys, studying bandwidth and latency

Using AVL Trees for Fault Tolerant Group Key Management

In this paper we describe an efficient algorithm for the management of group-keys for Group Communication Systems. Our algorithm is based on the notion of key-graphs, previously used for managing keys in large IP-multicast groups. The standard protocol requires a centralized key-server that has knowledge of the full key-graph. Our protocol does not delegate this role to any one process. Rather, members enlist in a collaborative eort to create the group key-graph. The key-graph contains n keys, of which each member learns log 2 n. We show how to balance the key-graph, a result that is applicable to the centralized protocol. We also show how to optimize our distributed protocol and provide a performance study of its capabilities