Traffic Partition in WDM/SONET Rings to Minimize SONET ADMs

SONET (Synchronous Optical NETworks) add-drop multiplexers (ADMs) are the dominant cost factor in the WDM(Wavelength Division Multiplexing)/SONET rings. The number of SONET ADMs required by a set of traffic streams is determined by the routing and wavelength assignment of the traffic streams. Previous works took as input the traffic streams with routings given a priori and developed various heuristics for wavelength assignment to minimize the SONET ADM costs. However, little was known about the performance guarantees of these heuristics. This paper contributes mainly in two aspects. First, in addition to the traffic streams with pre-specified routing, this paper also studies minimizing the ADM requirement by traffic streams without given routings, a problem which is shown to be NP-hard. Several heuristics for integrated routing and wavelength assignment are proposed to minimize the SONET ADM costs. Second, the approximation ratios of those heuristics for wavelength assignment only and those heuristics for integrated routing and wavelength assignment are analyzed. The new Preprocessed Iterative Matching heuristic has the best approximation ratio: at most 3/2.     

The contingent futures of the mobile present: automation as possibility

In this article we outline and demonstrate a design anthropological approach to investigating automated mobile futures as a processual opening up of possibilities, rather than as a process of technological innovation. To undertake this we investigate the example of how the car-smartphone relationship is configuring in the contingent circumstances of the mobile present and the implications of this for automated mobile futures. Our discussion is set in the context of the growing possibility that automonous driving (AD) features are increasingly part of everyday mobilities (even if unequally distributed globally) and in which personal mobile smart technologies and artificial intelligence (AI) will exist in some form and will interface with humans and be interoperable with other technologies. In developing this we draw on ethnographic understandings of how people live with the possibilities afforded by technologies in everyday life.     

Maintenance Default or Maintenance At Fault?: A Rejoinder

Maintenance default is a large problem and a number of reasons have been suggested for the cause. However, there are also philosophical questions as to whether maintenance is a desirable concept in the first place.     

The Ambiguity of Return Migration: Prolonged Crisis and Uncertainty in the Life Strategies of Young Romanian and Latvian Returnees

Drawing on qualitative research, this study endeavours to identify the determinants of return migration of young Romanians and Latvians in light of the most recent global economic crisis (GEC). The decision-making patterns of young returnees are examined by three main research questions. How do macro-events, such as the GEC, interfere with individual biographies creating specific return experiences? What can we say about the “crisis returnees”, their migration motivations and re-adaptation in the origin country? What are the main challenges of young adults facing life strategies in such uncertain periods? Data are drawn from 51 in-depth interviews with Romanian and Latvian young adults, carried out in late 2015 and early 2016. Findings show that return migration is associated with economic conditions, family life, feelings of homesickness, and re-adaptation experiences. Our results also confirm that youth transitions and migration have become more diversified and complex in the context of the economic crisis.     

Romanian social workers facing the challenges of neo-liberalism

ABSTRACT

With a history of almost 90 years, professional social work in Romania once flourished up until World War II. The Communist Party disbanded the profession in 1968 and it was reinstated after the fall of the Iron Curtain in 1989. Within the context of the socio-economic transition from a centralised to a free-market economy, Romanian social policy and social work have evolved from a Marxist/socialist-type ideology, one that advocates for state intervention, to a libertarian/neo-liberal-type ideology, which promotes both state withdrawal from welfare provision and individuals taking responsibility for their own welfare. These two trends continue to co-exist subject to sometimes divergent forces such as international institutions and internal Romanian social pressures. Using a qualitative approach, we explore how Romanian social workers are adapting to the neo-liberal realities and identify three types of perceived challenges: 1. those related to regulation, 2. linked with collaboration in social work activity and 3. those related to the social worker-client relationship. Under neo-liberal pressures, the social worker's role of agent of social change becomes marginalised in daily practice, leaving little power to influence agency policies that negatively impact clients.     

1.61-approximation for min-power strong connectivity with two power levels

Given a directed simple graph \(G=(V,E)\) and a cost function \(c:E \rightarrow R_+\), the power of a vertex \(u\) in a directed spanning subgraph \(H\) is given by \(p_H(u) = \max _{uv \in E(H)} c(uv)\), and corresponds to the energy consumption required for wireless node \(u\) to transmit to all nodes \(v\) with \(uv \in E(H)\). The power of \(H\) is given by \(p(H) = \sum _{u \in V} p_H(u)\). Power Assignment seeks to minimize \(p(H)\) while \(H\) satisfies some connectivity constraint. In this paper, we assume \(E\) is bidirected (for every directed edge \(e \in E\), the opposite edge exists and has the same cost), while \(H\) is required to be strongly connected. Moreover, we assume \(c:E \rightarrow \{A,B\}\), where \(0 \le A < B\). We improve the best known approximation ratio from 1.75 (Chen et al. IEEE GLOBECOM 2005) to \(\pi ^2/6 - 1/36 + \epsilon \le 1.61\) using an adaptation of the algorithm developed by Khuller et al. [SIAM J Comput 24(4):859–872 1995, Discr Appl Math 69(3):281–289 1996] for (unweighted) Minimum Strongly Connected Subgraph.