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1.
This paper addresses the problem of power control in a multihop wireless network supporting multicast traffic. We face the problem of forwarding packet traffic to multicast group members while meeting constraints on the signal-to-interference-plus-noise ratio (SINR) at the intended receivers. First, we present a distributed algorithm which, given the set of multicast senders and their corresponding receivers, provides an optimal solution when it exists, which minimizes the total transmit power. When no optimal solution can be found for the given set of multicast senders and receivers, we introduce a distributed, joint scheduling and power control algorithm which eliminates the weak connections and tries to maximize the number of successful multicast transmissions. The algorithm allows the other senders to solve the power control problem and minimize the total transmit power. We show that our distributed algorithm converges to the optimal solution when it exists, and performs close to centralized, heuristic algorithms that have been proposed to address the joint scheduling and power control problem. 相似文献
2.
A SAXS method for the quantitative assessment of the morphology of polymer layered silicate nanocomposites is proposed. Fitting the SAXS patterns, the number of clay layers, the periodicity of the layers in the tactoids, the thickness of the regions interposed between the clay platelets and their distributions can be measured. A good agreement with TEM data was obtained, avoiding the inconsistencies with microscopical observations often reported in the literature. 相似文献
3.
Predd Joel Pfleeger Shari Lawrence Hunker Jeffrey Bulford Carla 《Security & Privacy, IEEE》2008,6(4):66-70
This column goes beyond previous insider analyses to identify a framework for a taxonomy of insider threats including both malicious and inadvertent actions by insiders that put organizations or their resources at some risk. The framework includes factors reflecting the organization, the individual, the information technology system, and the environment. 相似文献
4.
Four PPG Avanel Series S surfactants (sodium alkyl polyether sulfonates) with varying ethylene oxide content (n = 3, 7, 9, and 15) were used to investigate the influence of the steric length in this type of electrosteric stabilizers on emulsion polymerization. The polymerization studies employing potassium persulfate as an initiator with styrene, methyl methacrylate, and vinyl acetate monomers showed no apparent change in particle size, number of particles, and polymerization rate with the changing steric length of the surfactant. Steric influences were observed in the redox-initiated systems of styrene, butyl acrylate, and methyl methacrylate. Increasing the ethylene oxide unit content from three to nine units decreased the rate of polymerization, the particle size and number in the polystyrene latexes. Polymerizations with the acrylates displayed the same trend except that the polymerization rate reached a minimum value at nine ethylene oxide units and increased when the surfactant containing 15 ethylene oxide units was used. 相似文献
5.
Walter Soares Leal Antônio Ricardo Panizzi Cintia Carla Niva 《Journal of chemical ecology》1994,20(5):1209-1216
The alarm pheromone system ofLeptoglossus zonatus (Dallas) adults was shown to be composed of hexyl acetate, hexanol, hexanal, and hexanoic acid. Single components tested in the field elicited dispersive behavior of over 70% of adults. 2-(E)-Hexenal, found in the secretion of nymphs, but not in the exudates of adults, was also active against adults. In addition, first-instar nymphs responded to the four components of the alarm pheromone of adults as well as to 2-(E)-hexenal, a component of their own alarm pheromone system. Adults and nymphs possess different alarm pheromone systems, which are not specific to their own life stage. That hemipteran alarm pheromone systems are not species-specific was supported by the fact that both adult and nymphL. zonatus responded to butanoic acid, an alarm pheromone of Alydidae, which was not found in this Coreidae species. 相似文献
6.
Xiaojing Zhang Yuquan Cai Xianwei Zhang Tariq Aziz Hong Fan Carla Bittencourt 《应用聚合物科学杂志》2021,138(22):50515
A eugenol-based silicone-containing monomer 4,4′-(1,1,3,3-tetramethyldisiloxane-1,3-dipropyl)bis-2-methoxyphenol(EUSi) was synthesized from eugenol and 1,1,3,3-tetramethyldisiloxane via the hydrosilylation reaction. And waterborne polyurethane (WPU) with excellent properties was obtained by using EUSi as a type of diol chain extender. The unique combination of rigidity and flexibility in the chemical structure of EUSi greatly facilitated the mechanical properties, thermal properties, and water resistance of WPU. With only a 3% dosage of EUSi, the maximum tensile strength was increased from 6.2 to 22.4 MPa, while the water absorption was decreased from 31.3% to a surprisingly 7.6%. Our work provides a new convenient strategy for the preparation of organosilicon-modified WPU with improved performance. 相似文献
7.
Carla G. Luciano Larissa Tessaro Rodrigo V. Lourenço Ana Mônica Q. B. Bittante Andrezza M. Fernandes Paulo J. A. Sobral 《应用聚合物科学杂志》2021,138(42):51246
Research on biopolymers-based active films produced with natural antioxidants and/or antimicrobials has gained attention over the last few years; however, anti-mold activity has been less studied than those of anti-bacteria. The aim of this work was the development and characterization of bi-layer films based on gelatin with natamycin and/or “Pitanga” leaf hydroethanolic extract in the second thin layer in order to determine the effects of these bioactive compounds on bi-layered film properties. The films were characterized regarding their moisture content and solubility in water, optical properties, microstructure, mechanical and thermal properties, water contact angle, water vapor permeability, UV/visible light transmission, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and antioxidant and anti-mold activities. Active films presented activity against Penicillium spp and Aspergillus niger and demonstrated antioxidant activity, as measured by ABTS •+ and DPPH • methods. Neither additive used in the films' second layer significantly affected the films' moisture content, thermal properties or the molecular interactions of the polymer matrix, assessed by FTIR, although some mechanical properties were affected, and the water contact angle. In conclusion, bi-layer films have reduced the quantity of additives required to maintain the antioxidant and anti-mold activities, as compared to similar monolayer films of the same thickness. 相似文献
8.
Andre Suslik Spritzer Jeremy Boy Pierre Dragicevic Jean‐Daniel Fekete Carla Maria Dal Sasso Freitas 《Computer Graphics Forum》2015,34(3):461-470
Node‐link infographics are visually very rich and can communicate messages effectively, but can be very difficult to create, often involving a painstaking and artisanal process. In this paper we present an investigation of node‐link visualizations for communication and how to better support their creation. We begin by breaking down these images into their basic elements and analyzing how they are created. We then present a set of techniques aimed at improving the creation workflow by bringing more flexibility and power to users, letting them manipulate all aspects of a node‐link diagram (layout, visual attributes, etc.) while taking into account the context in which it will appear. These techniques were implemented in a proof‐of‐concept prototype called GraphCoiffure, which was designed as an intermediary step between graph drawing/editing software and image authoring applications. We describe how GraphCoiffure improves the workflow and illustrate its benefits through practical examples. 相似文献
9.
We present the first step of a research aimed at automating a driven interactive 3D modeling of an existing architectural object. The method is based on oriented multi-image spherical panoramas produced by stitching techniques. The photogrammetric process has two steps: the creation of a semi-automatic process to find homolog points in two panoramas; the creation of parametric definitions for an interactive modeling creating points, segments, and surfaces based on the plotted points in the first step. By connecting these two steps, the creation of the model will be automatic, as we indicate the necessary points in just one panoramic photo. The principals of multi-view geometry and epipolar geometry were applied to simplify the calculation in the first step in order to create an automatic identification of the correspondent points in the other panorama. The epipolar geometry is described by both analytical and graphical programming, implementing in the first case a C++ application and in the second case a Rhinoceros and Grasshopper application. A case study of the Ponte Rotto in Rome (Italy) is presented. 相似文献
10.
Minimum Setup Minimum Aberration Two‐level Split‐plot Type Designs for Physical Prototype Testing 下载免费PDF全文
Linda Lee Ho Carla A. Vivacqua André Luís Santos de Pinho 《Quality and Reliability Engineering International》2016,32(3):1007-1020
Although new technologies allow for less effort in prototyping, physical testing still remains an important step in the product development cycle. Well‐planned experiments are useful to guide the decision‐making process. During the design of an experiment, one of the challenges is to balance limited resources and system constraints to obtain useful information. It is common that prototypes are composed of several parts, with some parts more difficult to assemble than others. And, usually, there is only one piece available of each part type and a large number of different setups. Under these conditions, designs with randomization restrictions become attractive approaches. Considering this scenario, a new and additional criterion, minimum setup, to construct split‐plot type designs is presented. Designs with the minimum number of setups of the more difficult parts, which are especially useful for screening purposes in physical prototype testing, are discussed. The use of the proposed criterion combined with minimum aberration for selecting a regular design is shown through a real application in testing car prototypes. As a tool to practitioners, catalogs of selected 32‐run minimum setup minimum aberration split‐split‐plot and split‐split‐split‐plot designs are presented. More complete catalogs are available as Supporting information. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献