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121.
Selfish Load Balancing and Atomic Congestion Games 总被引:1,自引:0,他引:1
We revisit a classical load balancing problem in the modern context of decentralized systems and self-interested clients.
In particular, there is a set of clients, each of whom must choose a server from a permissible set. Each client has a unit-length
job and selfishly wants to minimize its own latency (job completion time). A server's latency is inversely proportional to
its speed, but it grows linearly with (or, more generally, as the pth power of) the number of clients matched to it. This
interaction is naturally modeled as an atomic congestion game, which we call selfish load balancing. We analyze the Nash
equilibria of this game and prove nearly tight bounds on the price of anarchy (worst-case ratio between a Nash solution and
the social optimum). In particular, for linear latency functions, we show that if the server speeds are relatively bounded
and the number of clients is large compared with the number of servers, then every Nash assignment approaches social optimum.
Without any assumptions on the number of clients, servers, and server speeds, the price of anarchy is at most 2.5. If all
servers have the same speed, then the price of anarchy further improves to
We also exhibit a lower bound of 2.01. Our proof techniques can also be adapted for the coordinated load balancing problem
under L2 norm, where it slightly improves the best
previously known upper bound on the competitive ratio of a simple
greedy scheme. 相似文献
122.
Ferenc Bíró Zoltán Hajnal Csaba Dücső István Bársony 《Journal of Electronic Materials》2018,47(4):2322-2329
This work analyses the role of phase changes in TiO2/Pt/TiO2 layer stacks for micro-heater application regarding their stability and reliable operation. The polycrystalline Pt layer wrapped in a TiO2 adhesion layer underwent a continuous recrystallisation in a self-heating operation causing a drift in the resistance (R) versus temperature (T) performance. Simultaneously, the TiO2 adhesion layer also deteriorates at high temperature by phase changes from amorphous to anatase and rutile crystallite formation, which not only influences the Pt diffusion in different migration phenomena, but also reduces the cross section of the Pt heater wire. Thorough scanning electron microscopy, energy dispersive spectroscopy, cross-sectional transmission electron microscopy (XTEM) and electron beam diffraction analysis of the structures operated at increasing temperature revealed the elemental structural processes leading to the instabilities and the accelerated degradation, resulting in rapid breakdown of the heater wire. Owing to stability and reliability criteria, the conditions for safe operation of these layer structures could be determined. 相似文献
123.
The application of neutrality is a straightforward tool to preserve population diversity since it allows the genotype (on the represented search space) to be changed without affecting the corresponding fitness. To implement neutrality the literature suggests representational redundancy (more to one correspondence in genotype–phenotype mapping) although using it as a source of neutrality researchers uniformly reported better or worse results. Instead of applying representational redundancy here the utilization of pseudo redundancy as the source of neutrality is proposed, that is, neutrality is achieved by simple objective-fitness transformation while pseudo redundancy (as another redundancy interpretation) denotes more to one correspondence between objective-fitness domains by objective-fitness mapping. The contribution of this work is specified by the dynamic generational gap model introduced for evolutionary algorithms which appears when elitist strategy is used under neutrality by pseudo redundancy. This paper investigates the influence of dynamic generational gap model on the performance of a micro-genetic algorithm framework applied to achieve least cost water pump control policy for an industrial size water network distribution system. The presented constrained mixed-integer optimization problem is originated from the regional water network of the city of Sopron (60,000 citizens) located in Hungary. Here, the goal is to obtain intra-day pump schedule which minimizes the cost required for operation while satisfies the system constraints (water reservoir level limitations, pump flow and delivery regulations, pump energy consumption limitations) and fulfills the water requirement by the users. 相似文献
124.
Previous experimental results and theoretical considerations led to the conclusion that there are two autocatalytic reaction steps in the H2-oxidizing reaction of hydrogenase. One autocatalytic reaction occurs when the enzyme is mainly in inactive forms (Ni-A and/or Ni-B). This finding is supported by the special patterns of H2 oxidation in a thin-layer reaction chamber, and by the special, long lag phase observed. The autocatalytic step takes place between two enzyme forms, one of which also interacts directly with the terminal electron acceptor, i.e. the autocatalyst is an enzyme form in which [FeS]distal is reduced. During the autocatalytic interaction, an electron is passed from the autocatalyst to the other enzyme form. Inactive hydrogenase is used as a substrate in this autocatalytic step for another, activated hydrogenase molecule. 相似文献
125.
Journal of Mathematical Imaging and Vision - Up to an orientation-preserving symmetry, photographic images are produced by a central projection of a restricted area in the space into the image... 相似文献
126.
Csaba Rekeczky Botond Roska Erik Nemeth Frank S. Werblin 《International Journal of Circuit Theory and Applications》2001,29(2):197-239
In this paper, a vertebrate retina model is described based on a cellular neural network (CNN) architecture. Though largely built on the experience of previous studies, the CNN computational framework is considerably simplified: first‐order RC cells are used with space‐invariant nearest‐neighbour interactions only. All non‐linear synaptic connections are monotonic continuous functions of the pre‐synaptic voltage. Time delays in the interactions are continuous represented by additional first‐order cells. The modelling approach is neuromorphic in its spirit relying on both morphological and pharmacological information. However, the primary motivation lies in fitting the spatio‐temporal output of the model to the data recorded from biological cells (tiger salamander). In order to meet a low‐complexity (VLSI) implementation framework some structural simplifications have been made. Large‐neighbourhood interaction (neurons with large processes), furthermore inter‐layer signal propagation are modelled through diffusion and wave phenomena. This work presents novel CNN models for the outer and some partial models for the inner (light adapted) retina. It describes an approach that focuses on efficient parameter tuning and also makes it possible to discuss adaptation, sensitivity and robustness issues on retinal ‘image processing’ from an engineering point of view. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
127.
Gréta Gergely Filiz Cinar Sahin Gültekin Göller Onuralp Yücel Csaba Balázsi 《Journal of the European Ceramic Society》2013,33(12):2313-2319
Nano hydroxyapatite (nHA)–zirconia (ZrO2) composites have been produced by spark plasma sintering (SPS). During the SPS process low temperatures (600–950 °C) and short dwelling time (5 min) have been applied to avoid the decomposition of nHA as well as the reaction between nHA and ZrO2. The grain size of the sintered composites was between 200 and 1000 nm. Carbon diffusion was induced from the graphite die and layered composite structure was formed. These observations might be related to the spark plasma sintering side effects. The microstructure and mechanical properties of high hydroxyapatite content zirconia composites have been found to be influenced and strongly correlated with the specialties of SPS method. 相似文献
128.
Jong Chan PARK Csaba P. KOVESDY Uyen DUONG Elani STREJA Mehdi RAMBOD Allen R. NISSENSON Stuart M. SPRAGUE Kamyar KALANTAR‐ZADEH 《Hemodialysis international. International Symposium on Home Hemodialysis》2010,14(2):182-192
Recent studies indicate that serum alkaline phosphatase (AlkPhos), a surrogate of high turnover bone disease, is associated with coronary artery calcification and death risk in maintenance hemodialysis (MHD) patients. The association between AlkPhos and bone mineral density (BMD) is not well studied. We studied the association between AlkPhos and dual‐energy X‐ray absorptiometry‐assessed BMD in a group of MHD patients in Southern California. In 154 MHD patients, aged 55.3 ± 13.6 years, including 42% women, 38% Hispanics, 42% African Americans, and 55% diabetics, the mean serum AlkPhos was 121 ± 63 U/L (median: 101, Q25–75: 81–141); 36% had AlkPhos≥120 U/L and 50% had a total T‐score≤?1. Whereas the total BMD did not correlate with age (r=0.01, P=0.99) or body mass index (r=0.10, P=0.22), it correlated negatively with AlkPhos (r=?0.25, P=0.002), including after multivariate adjustment (r=?0.24, P=0.003). The proportion of patients with a high coronary artery calcification score>400 was incrementally higher across worsening BMD tertiles (P trend=0.04). The BMD was significantly worse in MHD patients with serum AlkPhos≥120 U/L compared with <120 U/L (1.01 ± 0.016 vs. 1.08 ± 0.013 g/cm2, respectively, P<0.001). The multivariate adjusted odds ratio of AlkPhos≥120 U/L for having a total T‐score1.0 was 2.3 (1.1–4.8, P=0.037). Among routine clinical and biochemical markers, serum AlkPhos≥120 U/L was a better predictor of total T‐score≤?1 in MHD patients. An association exists between higher serum AlkPhos and worse dual‐energy X‐ray absorptiometry‐assessed BMD in MHD patients. Given these findings, studies are indicated to examine whether interventions that lower serum AlkPhos improve BMD in MHD patients. 相似文献
129.
Pongrácz Péter; Molnár Csaba; Miklósi ádám; Csányi Vilmos 《Canadian Metallurgical Quarterly》2005,119(2):136
The authors investigated whether human listeners could categorize played-back dog (Canis familiaris) barks recorded in various situations and associate them with emotional ratings. Prerecorded barks of a Hungarian herding dog breed (Mudi) provided the sample. Human listeners were asked to rate emotionality of the vocalization and to categorize the situations on the basis of alternative situations provided on a questionnaire. The authors found almost no effect of previous experience with the given dog breed or of owning a dog. Listeners were able to categorize bark situations high above chance level. Emotionality ratings for particular bark samples correlated with peak and fundamental frequency and interbark intervals. The authors did not find a significant effect of tonality (harmonic-to-noise ratio) on either the emotionality rating or situation categorization of the human listeners. Humans' ability to recognize meaning suggests that barks could serve as an effective means of communication between dog and human. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
130.
Csaba Janáky Balázs Endrődi Krisztina Kovács Milan Timko András Sápi Csaba Visy 《Synthetic Metals》2010,160(1-2):65-71
Conducting polymer-based magnetic composites with controlled magnetic behaviour have been synthesized by chemical polymerization in nanoparticle containing organic media. Poly(3-thiophene-acetic-acid)–Fe3O4 hybrids have been prepared with five different iron-oxide contents, up to 20 m/m%, according to the results obtained by thermogravimetric analysis (TGA) and inductively coupled plasma atomic emission spectroscopic (ICP-AES) measurements. X-ray diffraction (XRD) and Mössbauer spectroscopic results gave direct evidences for the incorporation of both maghemite and magnetite. Photoacoustic Fourier transform infrared spectroscopic (PAS-FT-IR) measurements showed a chemical interaction between the polymer and the iron-oxide particles. SQUID investigations indicated a typical superparamagnetic behaviour for all samples, where saturation magnetization values proved to be tunable by the Fe3O4 content. After coating them onto electrode surfaces, basic electrochemical activity of the composite samples was demonstrated by cyclic voltammetry. 相似文献