We consider the problem of distributed deterministic broadcasting in radio networks of unknown topology and size. The network is synchronous. If a node u can be reached from two nodes which send messages in the same round, none of the messages is received by u. Such messages block each other and node u either hears the noise of interference of messages, enabling it to detect a collision, or does not hear anything at all, depending on the model. We assume that nodes know neither the topology nor the size of the network, nor even their immediate neighborhood. The initial knowledge of every node is limited to its own label. Such networks are called ad hoc multi-hop networks. We study the time of deterministic broadcasting under this scenario.For the model without collision detection, we develop a linear-time broadcasting algorithm for symmetric graphs, which is optimal, and an algorithm for arbitrary n-node graphs, working in time O(n 11/6 ). Next we show that broadcasting with acknowledgement is not possible in this model at all.For the model with collision detection, we develop efficient algorithms for broadcasting and for acknowledged broadcasting in strongly connected graphs.

No abstract

No abstract

Aims and backgroundThe concept and acceptance of lean manufacture as a set of principles is now fairly rooted in the literature [1][2][3]. The principles behind lean production are not in themselves new; many of them can be traced back to the work of pioneers such as Deming[4], Taylor[5], Skinner [6] and more recently in the UK such investigators as Hill [7], Voss[8], and Lamming[9] . However, although the concept of lean production as now understood could have modelled from this literature, it was not until the Japanese auto industry was studied [1], that the total concept became clear.While there are some voices of discontent [10,11] to the adoption and ultimate effectiveness of lean production, nonetheless many case examples exist to demonstrate how companies are changing their production methods and management practices to become leaner and fitter. Indeed lean manufacture has been extended to encompass the whole spectrum of activities in the business such that world-class companies are seeking to become lean enterprises [9,12,13].However, both the original work and subsequent offerings have tended to restrict their field of analysis to similar industrial sectors, namely, high-volume or mass producers, in particular the automotive and electronic sectors. Little published work [14,15] seems to have explicitly addressed the issue of whether lean methods are suitable and applicable in industrial sectors which are characterized by highly differentiated, low-volume production of low repeatability. For want of a better term, we shall refer to such products as "super value goods"(SVG), since one of their defining characteristics [16] is the high value added through the total supply chain and hence the market price of the product. Examples of such products would include: power generation, aerospace airframe and engine manufacturers and the like. In order to fill this gap, researchers at Warwick Manufacturing Group (WMG) [17], embarked on a case study based investigation to compare and contrast the methods and practices currently being adopted in a potential SVG sector (civil aerospace) with a typical lean manufacture sector (automotive). This paper describes the in-company methodology developed and some of the main findings of the research.