2,907 research outputs found
Non-blocking generalized three-stage interconnection networks
No full textIn this paper multicast three stage multiple link interconnection networks are considered. Each network stage is composed by full multicast switching elements connected to the switching elements of adjacent stages through h links, with h>l. For such networks, called generalized three-stage interconnection networks, the necessary and sufficient condition for strict sense non blocking is presented. This results extend those currently available in literature for multicast networks only in case of single-link inter-stage connections. Moreover, it is also demonstrated that, in the worst case of unrestricted fanout, the Complexity of a NxN multicast multi-link network can be limited to O(N5/3). Such a complexity is lower than that relevant to a crossbar network of the same size for N/h>182
NA48 results on kaon and hyperon decays relevant to |
No full textNew results from the NA48 experiment on kaon and hyperon decays relevant to are reported here. For charged kaons we present measurements of and . On neutral kaon decays we report the measurements of and of form factors slopes. For hyperons we present results on the .New results from the NA48 experiment on kaon and hyperon decays relevant to |V_us| are reported here. For charged kaons we present measurements of BR(K+- -> pi0 e+- nu) and BR(K+- -> pi0 mu+- nu). On neutral kaon decays we report the measurements of BR(K_L -> pi+ pi-) and of K_L -> pi+- mu-+ nu form factors slopes. For hyperons we present results on the BR(Xi0 -> Sigma+ e- nu_e)
Broker bridging mechanism for providing anonymity in MQTT
No full textWith the growth of the number of smart devices the range of fields where they are used is growing too, and it is essential to protect the communication between them. In addition to data integrity and confidentiality, for which standard mechanisms exists, a security service that may also be required is anonymity, allowing entities to communicate with each other in such a way that no third party knows that they are the participants of a certain message exchange. In this paper we propose a mechanism for creating anonymous communications using MQTT protocol. The design of our solution is based on dynamic broker bridging mechanism and allows clients to subscribe and to publish to a topic remaining incognito
Blocking probability of three-stage multicast switches
No full textIn this paper, an analytical model for the evaluation of the blocking probability of a three stage STM switch in presence of multicast is presented. The basic characteristics of this model are: i) the elementary switches can assume any size; ii) multicast connections can be characterised by any fan-out distribution; iii) both single request and additive request scenarios are analysed. Moreover, three network operation alternatives are analysed, Le. multicasting is carried-out in: a) the first and the third stages; b) the second and the third stages; c) all the three stages. The model uses a mixed approach derived from approaches proposed by Lee and Jacobeus. The analytical results are compared with those arising from simulation. The good accordance of the two series of results demonstrates the soundness of the model assumptions
A key agreement protocol for P2P VoIP applications
No full textA crucial aspect when establishing a secure peer-to-peer communication channel is the negotiation of the security parameters used to protect the successive data communications, including the various encryption and authentication keys. There are different secure protocol (such as IPSec, TLS, SSH, etc.) currently defined with their own negotiation mechanisms; unfortunately they usually rely on a pre-established trust relationship or secure association based on a shared secret key, some digital certificates, or a public key infrastructure (PKI). In this work we propose a new alternative key agreement protocol for setting up multimedia sessions between user agents (UAs) without requiring any pre-shared key or trust relationship or PKI. When two UAs communicate for the first time, a new key is established through Diffie-Hellman algorithm and authenticated by end users through vocal reading of a short authentication string. The proposed protocol has been also implemented and integrated in a publicly available VoIP UA
Non-blocking multicast three-stage interconnection networks
No full textThis paper deals with non-blocking properties of multicast three-stage interconnection networks. The necessary and suflcient condition for a strictly non blocking three-stage network is found and demonstrated. This condition represents a real innovative result with respect to those already available in literature that only refer to sufjicient bounds. Moreover, it is also demonstrated that, in the worst case of unrestricted fan-out and with a simple assumption on the path selection algorithm, the complexity of a NxN multicast network can be limited to O(p '). Such complexity is lower than that relevant to a crossbar network of the same size
Using SIP as P2P Technology
No full textNowadays peer-to-peer (p2p) technologies are widely adopted and used for building even more sophisticated services: from ubiquitous file-sharing systems to the even more popular Internet telephony. In addition, the Session Initiation Protocol (SIP) has been used for different purposes. Due to its intrinsic generality and flexibility, it could be adopted to build and manage also p2p applications. Moreover, the p2p philosophy could be applied to the existing SIP architecture, to cope with issues such as Denial of Service (DoS). In this paper, we survey the state of the art of the joint use of p2p and SIP. Some hints and examples in using SIP as a core technological component of the p2p world are also presented.</jats:p
An Anonymization Protocol for the Internet of Things
No full textThe Internet of Things (IoT) is expected to pervasively interconnect billions of devices, denoted as "smart objects", in an Internet-like structure, which will extend the current Internet, enabling new forms of interactions between objects based on social relationships. In such a scenario, security is a difficult and challenging task, and proper mechanisms should be defined without introducing too much protocol overhead and processing load. In particular, in this paper we focus on the anonymity of the communications and we propose a solution particularly suitable for such a constrained scenario. In the proposed solution IoT nodes form an Onion Routing anonymity network completely based on a datagram transport (e.g., over UDP). Confidentiality is completely enforced by the anonymity network and no other security protocols, such as IPSec or DTLS, are required. The proposed solution has been also implemented and tested
Cascade Reactions: A Multicomponent Approach to Functionalized Indane Derivatives by a Tandem Palladium-Catalyzed Carbamoylation / Carbocylization Process
No full textA novel, multicomponent and stereoselective approach to functionalized indane derivatives is reported. It is based on a tandem process consisting of Pd-catalyzed oxidative carbamoylation of 2-(2-ethynylbenzyl)malonates with carbon monoxide, a secondary amine, and oxygen (with formation of a propiolamide intermediate), followed by carbocyclization, occurring through intramolecular addition of an in situ formed carbanion to the propiolamide moiety
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