382 research outputs found

    Decomposition for Large-scale Optimization Problems with Overlapping Components

    Get PDF
    In this paper we use a divide-and-conquer approach to tackle large-scale optimization problems with overlapping components. Decomposition for an overlapping problem is challenging as its components depend on one another. The existing decomposition methods typically assign all the linked decision variables into one group, thus cannot reduce the original problem size. To address this issue we modify the Recursive Differential Grouping (RDG) method to decompose overlapping problems, by breaking the linkage at variables shared by multiple components. To evaluate the efficacy of our method, we extend two existing overlapping benchmark problems considering various level of overlap. Experimental results show that our method can greatly improve the search ability of an optimization algorithm via divide-and-conquer, and outperforms RDG, random decomposition as well as other state-of-the-art methods. We further evaluate our method using the CEC'2013 benchmark problems and show that our method is very competitive when equipped with a component optimizer

    Unitarily invariant norm inequalities for operators

    Full text link
    We present several operator and norm inequalities for Hilbert space operators. In particular, we prove that if A1,A2,...,AnB(H)A_{1},A_{2},...,A_{n}\in {\mathbb B}({\mathscr H}), then A1A2+A2A3+...+AnA1i=1nAiAi,|||A_{1}A_{2}^{*}+A_{2}A_{3}^{*}+...+A_{n}A_{1}^{*}|||\leq|||\sum_{i=1}^{n}A_{i}A_{i}^{*}|||, for all unitarily invariant norms. We also show that if A1,A2,A3,A4A_{1},A_{2},A_{3},A_{4} are projections in B(H){\mathbb B}({\mathscr H}), then &&|||(\sum_{i=1}^{4}(-1)^{i+1}A_{i})\oplus0\oplus0\oplus0|||&\leq&|||(A_{1}+|A_{3}A_{1}|)\oplus (A_{2}+|A_{4}A_{2}|)\oplus(A_{3}+|A_{1}A_{3}|)\oplus(A_{4}+|A_{2}A_{4}|)||| for any unitarily invariant norm.Comment: 10 pages, Accepted pape

    Facies analysis and paleoenvironmental reconstruction of Upper Cretaceous sequences in the eastern Para-Tethys Basin, NW Iran

    Get PDF
    Upper Cretaceous mixed carbonate-siliciclastic sequences are among the most important targets for hydrocarbon exploration in the Moghan area, located in the eastern Para-Tethys Basin. Despite of their significance, little is known about their facies characteristics and depositional environments. Detailed facies analysis and paleoenvironmental reconstruction of these sequences have been carried out in eight surface sections. Accordingly, four siliciclastic facies, eight carbonate facies and one volcanic facies have been recognized. Detailed facies descriptions and interpretations, together with the results of facies frequency analysis, standard facies models and Upper Cretaceous depositional models of Para-Tethys Basin, have been integrated and a non-rimmed carbonate platform is presented. This platform was affected by siliciclastic influx, in the form of coastal fan delta and submarine fans in the shallow- to deep-marine parts, respectively. This model is interpreted to be shallower in the central and northeastern parts of the Moghan area. Toward the southeast and southwest, this shallow platform turns into deep marine settings along steep slopes without remarkable marginal barriers

    Solving Ratio-Dependent Predator-Prey System with Constant Effort Harvesting using Variational Iteration Method

    Get PDF
    Due to wide range of interest in use of bio-economic models to gain insight into the scientific management of renewable resources like fisheries and forestry,variational iteration method (VIM) is employed to approximate the solution of the ratio-dependent predator-prey system with constant effort prey harvesting.The results are compared with the results obtained by Adomian decomposition method and reveal that VIM is very effective and convenient for solving nonlinear differential equations

    In-situ nanocomposite in friction stir welding of 6061-T6 aluminum alloy to AZ31 magnesium alloy

    Get PDF
    Prior to friction stir welding (FSW), silicon carbide (SiC) nanopowders were placed inside the groove on the adjacent side of magnesium sheet. In order to make a good distribution of these nanoparticles, first, friction stir processing (FSP) with a pinless tool was conducted on this side. Second, using a frustum pin tool, a combination of two travel speeds (25 and 35¿mm/min) and three rotation speeds (550, 600 and 650¿rpm) were employed to obtain the optimal conditions for FSW of AZ31 magnesium alloy to 6061 aluminum alloy. The joint fabricated at 35¿mm/min and 650¿rpm, exhibited improvement of 28% in tensile strength and enhancement about three times in elongation, compared with the joint without nanoparticles. SiC nanoparticles had an effective role on the grain refining of the stirred zone and improving the microstructural characteristics of the banded structure zone. Due to the decreased grain size and the presence of ceramic nanoparticles (SiC) with high value of hardness, the hardness level of the reinforced samples was greater than that of the non-reinforced samples. Fracture of the non-reinforced sample was completely brittle, while in the reinforced samples, fracture features changed to the ductile mode.Peer ReviewedPostprint (author's final draft

    Real-time seat allocation for minimizing boarding/alighting time and improving quality of service and safety for passengers

    Get PDF
    Rail is considered as one of the most important ways of transferring passengers. High passenger loads has implications on train punctuality. One of the important parameters affecting punctuality is the average boarding/alighting time. Organizing boarding/alighting flows not only reduces the risk of extended dwell time, but also minimizes the risk of injuries and improves the overall service quality. In this paper, we investigate the possibility of minimizing the boarding/alighting time by maintaining a uniform load on carriages through systematic distribution of passengers with flexible tickets, such as season or anytime tickets where no seat information are provided at the time of reservation. To achieve this, the proposed algorithm takes other information such as passenger final destination, uniform load of luggage areas, as well as group travelers into account. Moreover, a discrete event simulation is designed for measuring the performance of the proposed method. The performance of the proposed method is compared with three algorithms on different test scenarios. The results show the superiority of the proposed method in terms of minimizing boarding/alighting time as well as increasing the success rate of assigning group of seats to group of passengers

    Emerging role of non-coding RNAs in regulation of t-lymphocyte function

    Get PDF
    T-lymphocytes (T cells) play a major role in adaptive immunity and current immune checkpoint inhibitor-based cancer treatments. The regulation of their function is complex, and in addition to cytokines, receptors and transcription factors, several non-coding RNAs (ncRNAs) have been shown to affect differentiation and function of T cells. Among these non-coding RNAs, certain small microRNAs (miRNAs) including miR-15a/16-1, miR-125b-5p, miR-99a-5p, miR-128-3p, let-7 family, miR-210, miR-182-5p, miR-181, miR-155 and miR-10a have been well recognized. Meanwhile, IFNG-AS1, lnc-ITSN1-2, lncRNA-CD160, NEAT1, MEG3, GAS5, NKILA, lnc-EGFR and PVT1 are among long non-coding RNAs (lncRNAs) that efficiently influence the function of T cells. Recent studies have underscored the effects of a number of circular RNAs, namely circ_0001806, hsa_circ_0045272, hsa_circ_0012919, hsa_circ_0005519 and circHIPK3 in the modulation of T-cell apoptosis, differentiation and secretion of cytokines. This review summarizes the latest news and regulatory roles of these ncRNAs on the function of T cells, with widespread implications on the pathophysiology of autoimmune disorders and cancer

    An experiment for the measurement of the bound-beta decay of the free neutron

    Full text link
    The hyperfine-state population of hydrogen after the bound-beta decay of the neutron directly yields the neutrino left-handedness or a possible right-handed admixture and possible small scalar and tensor contributions to the weak force. Using the through-going beam tube of a high-flux reactor, a background free hydrogen rate of ca. 3 s1^{-1} can be obtained. The detection of the neutral hydrogen atoms and the analysis of the hyperfine states is accomplished by Lamb shift source type quenching and subsequent ionization. The constraints on the neutrino helicity and the scalar and tensor coupling constants of weak interaction can be improved by a factor of ten.Comment: 9 pages, 5 figures. Submitted to EPJ

    COVID-19 preventive behaviors and influencing factors in the Iranian population; a web-based survey

    Get PDF
    Background: COVID19 is a respiratory disease caused by a novel coronavirus. As there has been no definitive treatment for the disease so far, the only way to control the spread is to break the chain of infection. Our study aimed to analyze the preventive behaviors and influencing factors in the Iranian population. Methods: This cross-sectional study was a web-based survey in the Iranian population. We performed the study during the first peak of COVID-19 outbreak (from March 25th, 2020 to April 5th). We used demographic and Preventive behaviors questionnaires to collect the data. This web-based survey was publicized on the internet through the common platforms used by the Iranian population. This survey was released on the website “Porsline.com”. A total of 2097 acceptable questionnaires were filled. All data were analyzed, using Statistical Package for Social Sciences (SPSS) version 19. Results: 61.9% of the participants checked the hand-washing question as “Always”. 55.7 and 58.2% checked the wearing masks and gloves as “Always”, respectively. We found a significant relationship between gender and hand washing behavior (P = 0.006) and the use of masks and gloves (P < 0.001). Results showed that wearing gloves had a significant relation with the education status (P = 0.029) and economic status (P = 0.011). Wearing masks had a significant relation with economic status (P = 0.032). Overall women had better preventive behaviors. Conclusions: Preventive behaviors have a significant relation with some socio-demographic characteristics. According to the 3 main preventive behaviors of hand-washing, wearing masks and gloves 50% of the population has not taken these behaviors seriously

    Radiative recombination of bare Bi83+: Experiment versus theory

    Get PDF
    Electron-ion recombination of completely stripped Bi83+ was investigated at the Experimental Storage Ring (ESR) of the GSI in Darmstadt. It was the first experiment of this kind with a bare ion heavier than argon. Absolute recombination rate coefficients have been measured for relative energies between ions and electrons from 0 up to about 125 eV. In the energy range from 15 meV to 125 eV a very good agreement is found between the experimental result and theory for radiative recombination (RR). However, below 15 meV the experimental rate increasingly exceeds the RR calculation and at Erel = 0 eV it is a factor of 5.2 above the expected value. For further investigation of this enhancement phenomenon the electron density in the interaction region was set to 1.6E6/cm3, 3.2E6/cm3 and 4.7E6/cm3. This variation had no significant influence on the recombination rate. An additional variation of the magnetic guiding field of the electrons from 70 mT to 150 mT in steps of 1 mT resulted in periodic oscillations of the rate which are accompanied by considerable changes of the transverse electron temperature.Comment: 12 pages, 14 figures, to be published in Phys. Rev. A, see also http://www.gsi.de/ap/ and http://www.strz.uni-giessen.de/~k
    corecore