Insensitive Bounds for the Stationary Distribution of a Single Server Retrial Queue with Server Subject to Active Breakdowns

The paper addresses monotonicity properties of the single server retrial queue with no waiting room and server subject to active breakdowns. The obtained results allow us to place in a prominent position the insensitive bounds for the stationary distribution of the embedded Markov chain related to the model in the study. Numerical illustrations are provided to support the results

Efficient Multihop Wireless Communications in VANETs

Oggigiorno, una quota rilevante dei veicoli presenti sul mercato è dotata di notevoli capacità computazionali, sensoriali e cognitive. Questi veicoli ``intelligenti'' otterrebbero un beneficio ancora maggiore da queste potenzialità, attraverso l'impiego delle cosiddette comunicazioni inter-veicolari (Inter-Vehicular Communications, IVCs), un insieme di protocolli, standard e tecnologie in grado di dotare i veicoli di capacità comunicative. In particolare, grazie alle tecnologie IVCs, i veicoli possono creare reti decentralizzate, ed auto-organizzate, comunemente note come Vehicular Ad-hoc NETworks (VANETs). Quest'ultime possono essere formate, sia fra veicoli, determinando la realizzazione di comunicazioni inter-veicolari pure (Vehicle-to-Vehicle communications, V2V), oppure coinvolgendo anche nodi fissi (ad esempio, posti ai lati delle strade), determinando la realizzazione di comunicazioni da veicolo verso infrastruttura (Vehicle-to-Infrastructure, V2I), o da infrastruttura verso veicolo (Infrastructure-to-Vehicle I2V). In questa tesi presenteremo una famiglia di protocolli di instradamento a passi multipli, adatti per un largo spettro di applicazioni nell'ambito delle VANET, quali la prevenzione di incidenti stradali, o applicazioni di raccolta dati, in scenari di tipo V2V, V2I, o I2V. Il primo protocollo che viene proposto è un nuovo schema di broadcasting probabilistico per reti lineari a passi multipli, noto come Irresponsible Forwarding (IF), secondo il quale ogni veicolo decide probabilisticamente se effettuare la ritrasmissione (broadcast) di un messaggio ricevuto. La probabilità di ritrasmissione è determinata sulla base della propria distanza dalla sorgente e della densità spaziale dei propri vicini. I vantaggi principali del protocollo IF rispetto alle soluzioni presenti in letteratura, sono costituiti dalla sua natura intrinsecamente distribuita, dalla bassa latenza, e dall'assenza di overhead, in quanto esso non prevede l'utilizzo di pacchetti ausiliari di supporto Successivamente, presenteremo un secondo protocollo di instradamento probabilistico, noto come Silencing Irresponsible Forwarding (SIF), che riprendendo le idee alla base di IF, permette di ottenere una maggiore efficienza (e.g., un minore numero di ritrasmissioni), senza penalizzarne l'affidabilità, e mantenendo valori di latenza comparabili ad IF. In seguito, verrà inoltre proposto un protocollo di clustering decentralizzato, noto come Cluster-Head Election IF (CHE-IF). Quest'ultimo si propone di sfruttare lo spontaneo processo di formazione di cluster effimeri di nodi nelle reti veicolari, in maniera distribuita ed efficiente. Per ottenere questo risultato, CHE-IF utilizza l'idea alla base di IF, ma introducendo dei pacchetti di controllo aggiuntivi, espressamente dedicati alla realizzazione di cluster di nodi. Infine, le prestazioni di tutti i protocolli proposti verranno testate mediante simulazioni numeriche in realistici scenari veicolari, quali autostrade e strade urbane, assumendo di utilizzare interfacce radio compatibili con lo standard IEEE 802.11p.Nowadays, most of the vehicles available on the market are provided by sensorial, computational, and cognitive skills. Vehicles can achieve a higher awareness level, by exploiting these potentialities through Inter-Vehicular Communications (IVCs), a set of technologies that gives networking capabilities to the vehicles. Leveraging on the IVC technology, vehicles can create decentralized and self-organized vehicular networks, commonly denoted as Vehicular Ad-hoc NETworks (VANETs). These networks can be formed between vehicles, leading to Vehicle-to-Vehicle communications (V2V), or they can also involve some fixed network nodes (e.g., access points or road side unit) leading to the so-called Vehicle-to-Infrastructure (V2I) and Infrastructure-to-Vehicle (I2V) communications. In this thesis we present a family of multihop broadcast forwarding protocols suitable for a wide range of VANETs applications, ranging from accident-preventing, to data collection applications, in V2V, V2I, or I2V scenarios. The first proposed protocol is a new probabilistic-based broadcasting scheme for multi-hop linear networks, denoted as Irresponsible Forwarding (IF), where each vehicle probabilistically rebroadcasts a received data packet on the basis of (i) its distance from the source and (ii) the spatial density of its neighbors. The main advantages of the IF protocol with respect to solutions present in the literature, are its inherently distributed nature, the low-latency, and the absence of overhead, since auxiliary supporting packets are not needed. On the basis of the IF concept, we will present an improved probabilistic forwarding protocol, denoted as Silencing Irresponsible Forwarding (SIF) protocol, able to guarantee a greater efficiency (e.g., a smaller number of retransmissions), without penalizing the reliability, and maintaining a comparable latency. Furthermore, we will propose a novel decentralized clustering protocol, denoted as Cluster-Head Election IF (CHE-IF), whose goal is which of exploiting the spontaneous formation of ephemeral clusters of vehicles in VANETs, in a distributed and efficient manner. This result is achieved by enhancing IF with some additional control messages, aimed at the creation of cluster of nodes. Finally, the performance of the proposed protocols will be tested through numerical simulations in realistic vehicular environments, such as highways and urban roads, by using radio interfaces compliant with the IEEE 802.11p standard

The medicalization of deviance in China

亞洲犯罪學學會Conference Theme: Asian Innovations in Criminology and Criminal JusticePart 5: Juvenile Delinquency and JusticeConrad and Schneider’s now classical work on the historical transformation of definitions of deviance from “badness” to “sickness” is relevant for the situation in China today, although with some modifications. The weakly founded medical/psychiatric profession and the strong political/ideological discourse in China leads to a strange combination of medicalization and moralization, even criminalization of deviance. The “sick” is often combined with the “bad”, and “sickness” is often seen as a secondary sign of “badness”. The pan-moralist tradition of ancient China seems to be closely combined with the Communist era’s strong belief in political-ideological correctness, and its strong belief in social engineering. It is interesting to note that my research on crime and deviance in China in the 1980s and 1990s seems to be confirmed by today’s discourse, although there are new moral panics and new forms of medical-moralistic definitions of deviance in China today. Still, the categories of deviance are very much socially constructed entities closely related to the moral-political order of present day China. I will use three cases to underline my argument. First, the type of deviance I call “majority deviance”, related to the case of the prejudice and dangers associated with the only-child. My second example has to do with what I term the “wayward girl” and the moral panics concerning so-called zaolian – or “premature love” among young girls. The third example is the new panic surrounding “internet addiction disorder” or IAD. While the “disco” and the “dance hall” were the sites of disorder in the 1980s and 90s, the wangba – or “internet bar” is now seen as the most dangerous site of crime and deviance.postprin

Autonomia: a movement of refusal: social movements and social conflict in Italy in the 1970's

This thesis examines the continuing significance in contemporary Italy of the Italian new social movement of 1973-83, Autonomia, by positing it as a movement of refusal: of capitalist work, of the party form, of the clandestine form of political violence, and of the politics of `taking power'. It was in discontinuity with the value systems of the reformist Old Left and the revolutionary New Left, but in continuity with contemporary Italian antagonist and global anti-capitalist movements. In defining the research subject, the concept of individual and collective autonomy emerges as a central characteristic of the Italian new social movements. Autonomy is understood not only as independence from the capitalist State and economy and their institutions of mediation, but also as the self-determination of everyday life, related to the needs, desires and subjectivity of what Italian `workerism' defined as the Fordist `mass worker' and the post-Fordist `socialised worker'. Using the `class composition' theoretical perspective of Autonomist Marxism to critique classical Marxism, neo-Marxism and new social movement theory's minimalisation of the political content of new social movements and dismissive analysis of Autonomia, the scope of research was limited to the interpretation of 48 interviews of former participants and observers, of primary texts produced by Autonomia and of secondary accounts based on `collective historical memory'. The thematic framework consists of chapters on workers' autonomy and the refusal of work; forms of political organisation and violence involving `organised', `diffused' and `armed' Autonomia; and on the youth counter-cultures and antagonist communication of `creative Autonomia' and the 1977 Movement. The thesis concludes that Autonomia expressed the violent social conflicts produced by the rapid transformation of an industrial into a post-industrial society, but ultimately was only a partial break from the traditions and practices of the Old and New Lefts, leaving an ambiguous legacy for contemporary Italian autonomous social movements

Annual Report

[Excerpt] The Commission is deeply concerned that some Chinese government policies designed to address growing social unrest and bolster Communist Party authority are resulting in a period of declining human rights for China’s citizens. The Commission identified limited improvements in the Chinese government’s human rights practices in 2004, but backward-stepping government decisions in 2005 and 2006 are leading the Commission to reevaluate the Chinese leadership’s commitment to additional human rights improvements in the near term. In its 2005 Annual Report, the Commission highlighted increased government restrictions on Chinese citizens who worship in state-controlled venues or write for state-controlled publications. These restrictions remain in place, and in some cases, the government has strengthened their enforcement