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21.
One of the important aspects of a mobile ad hoc network (MANET) is the limitation of the amount of available energy and the network lifetime. The tremendous amount of using mobile nodes in wireless communication medium makes energy efficiency a fundamental requirement for MANETs. In this paper, we propose a novel energy aware clustering algorithm for the optimized link state routing (OLSR) routing protocol. This algorithm takes into account the node density and mobility and gives major improvements regarding the number of elected cluster heads. Our objective is to elect a reasonable number of cluster heads that will serve for hierarchical routing based on OLSR. The proposed algorithm aims to increase the network lifetime by considering the ad hoc residual energy while taking routing decisions. It also optimizes the delay of carried flows by adopting a selective forwarding approach based on a hierarchical routing model.  相似文献   
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Mechanics of Time-Dependent Materials - In the present paper, the predictive capabilities of some integral-based finite strain viscoelastic models under the time–strain separability...  相似文献   
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This paper proposes a design approach of continuous sliding mode control of uncertain systems, the uncertainty being norm bounded. The two steps of the design methodology are investigated. The existence step, in which we choose the sliding surface that gives good behaviour during the sliding mode, is formulated as a pole assignment of linear uncertain system in a sector through convex optimization. The solution to this problem is therefore numerically tractable via linear matrix inequalities (LMI) optimization. In the reaching step, we propose a continuous nonlinear control strategy ensuring a bounded motion about the ideal sliding mode, thus approximating the ideal dynamic behaviour in the presence of uncertainty. Finally, the validity and the applicability of this approach are illustrated by a flight stabilization benchmark example. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
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Abstract

The forestry industry in the Basque Country has experienced an abandonment of small-sized forests in which native and introduced species tend to regrow if unattended; thus, requiring an intervention under which proper forest management is implemented. This paper evaluates the potential fractionation of lignin and cellulose from six tree species coming from such mixed forests as a value-added use of wood discarded by logging within the frame of sustainable forest management. The species used were Northern red oak, common oak, common ash, Iberian white birch, sweet chestnut, and black locust. The different wood samples were treated with an Organosolv treatment and elemental chlorine-free bleaching to fractionate them to their main components, recovering the cellulose and the lignin. Cellulose was defibrillated via high-pressure homogenization to obtain cellulose nanofibers. The resulting lignin and cellulose nanofibers were analyzed. The results support the idea that this process offers the opportunity to treat different raw materials in the same process, with corresponding possible economic benefits.  相似文献   
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This paper presents a novel approach to contour approximation carried out by means of the B-snake algorithm and the dynamic programming (DP) optimization technique. Using the proposed strategy for contour point search procedure, computing complexity is reduced to O(N×M(2)), whereas the standard DP method has an O(N×M(4)) complexity, with N being the number of contour sample points and M being the number of candidates in the search space. The storage requirement was also decreased from N×M(3) to N×M memory elements. Some experiments on noise corrupted synthetic image, magnetic resonance, and computer tomography medical images have shown that the proposed approach results are equivalent to those obtained by the standard DP algorithm.  相似文献   
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PURPOSE: There is no consensus on the treatment of patients with Waldenstr?m's macroglobulinemia (WM) who develop primary or secondary resistance to frontline therapies. We report our experience on the activity and toxicity of fludarabine in 71 patients with WM resistant to prior chemotherapy regimens. PATIENTS AND METHODS: From January 1991 to June 1995, 71 patients were included in this retrospective study. The median age, median time from diagnosis to treatment, median immunoglobulin M (IgM) level, and median number of previous treatments were 68 years (range, 42 to 81), 5.9 years (range, 0.6 to 20), 35 g/L (range, 5 to 126), and two (range, one to four), respectively. RESULTS: Seventy-one patients received a median of six courses of fludarabine. Twenty-one (30%) responded with a partial response and 50 (70%) were considered as treatment failures. Forty-six patients died: 10 in the responder group and 36 in the failure group. Twenty-five patients were alive with a median follow-up time of 34 months. The overall median survival time of all treated patients was 23 months. The time to treatment failure was 32 months. The only factor that favorably influenced the response to fludarabine was a longer interval between the first treatment and the start of fludarabine. Pretreatment factors associated with shorter survival in the entire population were hemoglobin level less than 95 g/L (P = .02) and platelet count less than 75 x 10(9)/L (P = .02). CONCLUSION: The responses rate in this population with a poor prognosis is close to that reported in shorter series. Patients with WM who are resistant to alkylating agents should be identified early, so that salvage therapy with nucleoside analogs can be started without delay.  相似文献   
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