scholarly journals Range Assignment Problem on the Steiner Tree Based Topology in Ad Hoc Wireless Networks

2009 ◽  
Vol 5 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Rashid Bin Muhammad
Keyword(s):  
Steiner Tree ◽  
Ad Hoc ◽  
Ad Hoc Wireless Networks ◽  
Communication Graph ◽  
Relay Nodes ◽  
Range Assignment ◽  
Wireless Communication Network ◽  
Minimal Steiner Tree ◽  
The Cost ◽  
The Given

This paper describes an efficient method for introducing relay nodes in the given communication graph. Our algorithm assigns transmitting ranges to the nodes such that the cost of range assignment function is minimal over all connecting range assignments in the graph. The main contribution of this paper is the O(N log N) algorithm to add relay nodes to the wireless communication network and 2-approximation to assign transmitting ranges to nodes (original and relay). It does not assume that communication graph to be a unit disk graph. The output of the algorithm is the minimal Steiner tree on the graph consists of terminal (original) nodes and relay (additional) nodes. The output of approximation is the range assignments to the nodes.

Power Efficient Range Assignment for Symmetric Connectivity in Static Ad Hoc Wireless Networks

2005 ◽  
Vol 12 (3) ◽  
pp. 287-299 ◽  
Author(s):  
E. Althaus ◽  
G. Călinescu ◽  
I. I. Măndoiu ◽  
S. Prasad ◽  
N. Tchervenski ◽  
...  
Keyword(s):  
Wireless Networks ◽  
Ad Hoc ◽  
Ad Hoc Wireless Networks ◽  
Power Efficient ◽  
Range Assignment ◽  
Symmetric Connectivity

scholarly journals Robust Reoptimization of Steiner Trees

Algorithmica ◽  
2020 ◽  
Vol 82 (7) ◽  
pp. 1966-1988
Author(s):  
Keshav Goyal ◽  
Tobias Mömke
Keyword(s):  
Steiner Tree ◽  
Optimal Solution ◽  
Approximate Solutions ◽  
Problem Instance ◽  
Steiner Tree Problem ◽  
Performance Guarantees ◽  
Improved Performance ◽  
Algorithmic Technique ◽  
The Cost ◽  
The Given

Abstract In reoptimization, one is given an optimal solution to a problem instance and a (locally) modified instance. The goal is to obtain a solution for the modified instance. We aim to use information obtained from the given solution in order to obtain a better solution for the new instance than we are able to compute from scratch. In this paper, we consider Steiner tree reoptimization and address the optimality requirement of the provided solution. Instead of assuming that we are provided an optimal solution, we relax the assumption to the more realistic scenario where we are given an approximate solution with an upper bound on its performance guarantee. We show that for Steiner tree reoptimization there is a clear separation between local modifications where optimality is crucial for obtaining improved approximations and those instances where approximate solutions are acceptable starting points. For some of the local modifications that have been considered in previous research, we show that for every fixed $$\varepsilon > 0$$ ε > 0 , approximating the reoptimization problem with respect to a given $$(1+\varepsilon )$$ ( 1 + ε ) -approximation is as hard as approximating the Steiner tree problem itself. In contrast, with a given optimal solution to the original problem it is known that one can obtain considerably improved results. Furthermore, we provide a new algorithmic technique that, with some further insights, allows us to obtain improved performance guarantees for Steiner tree reoptimization with respect to all remaining local modifications that have been considered in the literature: a required node of degree more than one becomes a Steiner node; a Steiner node becomes a required node; the cost of one edge is increased.

A study of cane supply benefits associated with ad hoc mechanical harvesting to mitigate cutter absenteeism

2013 ◽  
pp. 532-538 ◽  
Author(s):  
Muhammad Kadwa ◽  
Carel N Bezuidenhout
Keyword(s):  
Supply Chain ◽  
South African ◽  
Ad Hoc ◽  
Sugar Mill ◽  
The South ◽  
Optimum Performance ◽  
Kwazulu Natal ◽  
Cane Quality ◽  
The Cost

The Eston Sugar Mill is the newest in the South African KwaZulu-Natal sugar belt. Like most other mills, it can be argued that there are inefficiencies in the supply chain due to systematic issues, which reduce optimum performance. It was alleged that mill processes are slowed, or stopped, on Sundays, Mondays, as well as some Tuesdays and Wednesdays, due to pay-weekends, because of the associated cutter absenteeism. This increases the length of the milling season (LOMS), increases milling costs and reduces the average cane quality for the season. Data on cane deliveries to the Eston Mill, over a period of five seasons, were analysed to study the magnitude of the problem. It was statistically verified that cane shortages occur immediately after payweekends and it was conservatively estimated that cutter absenteeism occurs between 25–29 days per season, which increases the LOMS by six to ten days. The associated cost of this problem equated to an average of US$159,500 (approximately EUR120,000) per milling season. In this paper, an alternative harvesting system scenario is suggested, assuming that mechanical harvesters be used after a pay-weekend, to mitigate the impacts of cutter shortages. However, the solution is calculated to be risky. When the cost of new equipment was considered, only two of the five seasons were able to justify the associated costs.

GPS Aided GEO Augmented Navigation Enabled Energy Efficient Routing for Mobile Ad-hoc Wireless Networks

2017 ◽  
Vol 2 (7) ◽  
pp. 5-8
Author(s):  
Neeraj Verma ◽  
Kuber Mohan
Keyword(s):  
Energy Efficient ◽  
Ad Hoc ◽  
Mobile Ad Hoc Network ◽  
Critical Issue ◽  
Ad Hoc Wireless Networks ◽  
Energy Utilization ◽  
Energy Efficient Routing ◽  
Network Nodes ◽  
Mobile Ad Hoc ◽  
Hoc Networks

Energy is a critical issue in Mobile Ad-hoc Network. Nodes in Network are working in presence of limited or less energy due to dynamic nature of nodes or infrastructure less network. MANET has no infrastructure so nodes in MANET work on dynamic routing. In this way, energy proficient routing is required for reducing energy utilization. Energy proficient routing plans can extraordinarily reduce energy utilization and augments the lifetime of the networks. Scalability of Ad Hoc Networks can be enhanced by using land data, for example, in LAR, GPSR etc. They utilize physical area data; regularly from GPS (Global Positioning System).GPS empowers a gadget to decide their position as in longitude, Latitude and Altitude by getting this data from the satellites. There has been significant effort in proposing energy efficient routing protocols with the help of GAGAN (GPS Aided GEO Augmented Navigation) which have accuracy to approx One meter in India or its neighbor countries. GAGAN is a route framework which is helped by both GPS and nearby telemetry information to possibly give quicker and more exact situating and navigational information.

scholarly journals Adherence to French and ESGO Quality Indicators in Ovarian Cancer Surgery: An Ad-Hoc Analysis from the Prospective Multicentric CURSOC Study

Cancers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1593
Author(s):  
Alejandra Martinez ◽  
Witold Gertych ◽  
Christophe Pomel ◽  
Gwenael Ferron ◽  
Amelie Lusque ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Quality Indicators ◽  
Ad Hoc ◽  
Randomized Study ◽  
Institutional Quality ◽  
High Volume ◽  
Cost Utility ◽  
Case Volume ◽  
Tertiary Institutions ◽  
The Cost

Background: Quality Indicators for ovarian cancer (OC) have been developed by the European Society of Gynaecological Oncology (ESGO) and by the French National Cancer Institute (Institut National du Cancer, INCa). The aim of the study was to characterize OC care distribution in France by case-volume and to prospectively evaluate the adherence of high-volume institutions to INCa/ESGO quality indicators. Methods: The cost-utility of radical surgery in ovarian cancer (CURSOC) trial is a prospective, multicenter, comparative and non-randomized study that includes patients with stage IIIC-IV epithelial OC treated in nine French health care tertiary institutions. Adherence to institutional quality indicators were anonymously assessed by an independent committee. OC care distribution in France were provided by the nationwide database of hospital procedures. Results: More than half of patients are treated in low-volume institutions. Among the nine high-volume centers participating in the study, four (44.4%) met all institutional INCa/ESGO quality indicators. The other five (55.6%) did not fulfil one of the quality indicator criteria. Conclusions: Access to high-volume OC providers in France is restricted to a minority of patients, and yet half of the referral institutions included in this study failed to meet all recommended institutional quality indicators. It is mandatory that national authorities work both to improve OC centralization and to incorporate quality assurance programs into certified centers.

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