Search

Abstract: Artificial bee colony (ABC) algorithm is a relatively new optimization technique which has been shown to be competitive to other population-based algorithms. However, there is still an insufficiency in ABC regarding its solution search equation, which is good at exploration but poor at exploitation. To address this concerning issue, in this paper, we propose a novel ABC method called as EABC to improve the performance of ABC. In our method, in order to balance the exploration and the exploitation, two new search equations are presented to generate candidate solutions in the employed bee phase and the onlookers phase, respectively. Additionally, we use a more robust calculation to determine and compare the quality of alternative solutions. Experiments are conducted on a set of 48 benchmark functions and also two engineering optimization problems. The results show that EABC significantly improves the performance of ABC, offering faster global convergence, higher solution quality, and stronger robustness when compared with the other algorithms. [Copyright &y& Elsevier]

In this paper, we propose two protocols for generating super-resolving single-photon (SRSP) number-path-entangled states from general maximally number-path-entangled NOON states. It is our purpose to show that, contrary to popular belief, a field in a single-photon state can carry multifold phase information. We also show that both protocols generate the desired state with different probabilities depending on the type of detectors being used. Such SRSP number-path-entangled states preserve high resolving power but lack the requirement of a multiphoton absorbing resist, which may serve as a proof-of-principle prototype for quantum lithography in the future. [ABSTRACT FROM AUTHOR]

We study cooperative single-photon spontaneous emission from N multilevel atoms for different atomic distributions in optical vector theory. Instead of the average approximation for interatomic distance or the continuum approximation (sums over atoms replaced by integrals) for atomic distribution, the positions of every atom are taken into account by numerical calculation. It is shown that the regularity of atomic distribution has considerable influence on cooperative spontaneous emission. For a small atomic sample (compared with radiation wavelength), obtaining strong superradiance requires not only the uniform excitation (the Dicke state) but also the uniform atomic distribution. For a large sample, the uniform atomic distribution is beneficial to subradiance of the Dicke state, while the influence of atomic distribution on the timed Dicke state is weak and its time evolution obeys exponential decay approximately. In addition, we also investigate the corresponding emission spectrum and verify the directed emission for the timed Dicke state for a large atomic sample. [ABSTRACT FROM AUTHOR]

We study cooperative single-photon spontaneous emission from three multilevel atoms with one of them being excited for different atomic configurations in optical vector theory. The dynamic evolution is solved by finding the eigenvalues of a 3 x 3 matrix, and then the relevant decay rates and Lamb shifts are obtained analytically. It is shown that the symmetry of atomic configuration has a big influence on the super-radiance of the system. To obtain strong super-radiance requires not only the distances among the three atoms to be much shorter than the wavelength, but also to have symmetrical distribution. We also calculate the emission spectra and find that it normally has three peaks, but it has two peaks under the equilateral-triangle configuration. [ABSTRACT FROM AUTHOR]

Abstract: Particle swarm optimization (PSO) is a relatively new optimization algorithm that has been applied to a variety of problems. However, it may easily get trapped in a local optima when solving complex multimodal problems. To address this concerning issue, we propose a novel PSO called as CSPSO to improve the performance of PSO on complex multimodal problems in the paper. Specifically, a stochastic search technique is used to execute the exploration in PSO, so as to help the algorithm to jump out of the likely local optima. In addition, to enhance the global convergence, when producing the initial population, both opposition-based learning method and chaotic maps are employed. Moreover, numerical simulation and comparisons with some typical existing algorithms demonstrate the superiority of the proposed algorithm. [Copyright &y& Elsevier]

The communication accessibility of the lunar rover from the Earth to the Moon can provide a basis for the choice of ideal landing sites. In this paper, a mathematical model is established to study the communication accessibility affected by topography, by combining lunar digital elevation models (DEM) with known parameters related to lunar and earth' s orbit. The laser altimeter data obtained by 'Chang' E-1' can provide high accuracy DEM and can be as the data basis for this study. The research region is Sinus Iridum region (the preferred landing area of Chinese lunar exploration) and the lunar polar regions. The calculation period is from Oct. 1, 2013 to Oct. 30, 2013. The results show that (1) in the Sinus Iridum region, the communication condition between tracking stations (Beijing, Kunming, Shanghai and Urumchi) and the lunar rover is expedite, which is consistent with the region's flat terrain; (2) in the polar regions, the influence of topography on the communication condition is great because of the topography complexity. [ABSTRACT FROM AUTHOR]

In a solid-state circuit QED system, we extend the previous study of generating and stabilizing a two-qubit Bell state [ Phys. Rev. A 82 032335 (2010)] to a three-qubit GHZ state. In a dispersive regime, we employ the homodyne joint readout for multiple qubits to infer the state for further processing, and in particular we use it to stabilize the state directly by means of an alternate-flip-interrupted Zeno (AFIZ) scheme. Moreover, the state-of-the-art feedback action based on the filtered current enables not only a deterministic generation of the pre-GHZ state in the initial stage, but also a fast recovery from occasional error in the later stabilization process. We show that the proposed scheme can maintain the state with high fidelity if the efficient quantum measurement and rapid single-qubit rotations are available. [ABSTRACT FROM AUTHOR]

Purpose - This study proposes to discuss an up-to-date framework for service design as a means-end tool for modeling, designing, and developing the service systems (e-service) which can fulfil (semi-)automated value co-production between the service providers and the customers in a service. In order to achieve the goal of service innovation, this study raises concerns regarding how an innovative e-service can be a systematic service process according to the proposed service design framework. However, the framework takes into account a novel service classification and individual criteria. Design/methodology/approach - This study addresses an intelligent service design using design science. According to the proposed framework, the service systems (e-services) are implemented by simulation. In this study, either service classification or the counterparts of service performance measures emerged from the ecological symbiosis perspective through analytic and synthetic methods. The proposed service design framework defines two dimensions - continuity of co-production and mutual adaptability - characterized by the process of exchanging service/benefit and building relationship (i.e. partnership) involved within a service. The framework indicated how the interactions and the service/benefit exchange between the service provider and the consumer can work in a service process. The aim is to build a partnership by the service participants due to mutual adaptability in adapting to the counterpart of service (i.e. the service provider or the customer). Findings - Comparing with traditional service classification and service design, a more positive niche in systematic service innovation was established than before. According to the synthetic methodology, this study classifies the six categories of service based on ecological symbiosis perspectives. Examining individual service performance is derived from a set of criteria of species performance measures in ecological mutualism including proximate response, evolved dependence, and ultimate response. The service systems comply with the characteristics and criteria in the framework to demonstrate the sets of methodology for innovative service design. Practical implications - This study has yielded findings on both managerial insight on service innovation and the impact of service system design. Originality/value - The value of the framework is demonstrated through the diverse service systems. For example, digital content, interior design, or mobile phone design is characterized by service participants who embody knowledge-intensive attributes when engaged in their service process. In order to further complete a novel framework for service design, the question of evaluation that arises concerns the extent of ensuring the necessary service performance. [ABSTRACT FROM AUTHOR]

The structural network control principle for identifying personalized drug targets (SNCPDTs) is a kind of constrained multiobjective optimization (CMO) problem with NP-hard features, which makes traditional mathematical methods difficult to adopt. Therefore, this study designs a knowledge-embedded multitasking constrained multiobjective evolutionary algorithm (KMCEA) to solve the SNCPDTs by mining relevant knowledge. Specifically, the relationships between two optimization objectives (minimizing the number of driver nodes and maximizing prior-known drug-target information) and constraints (guaranteeing network control) are analyzed from the perspective of CMO. We find that two objectives are difficult to optimize; thus two single-objective auxiliary tasks are created to optimize two objectives respectively, so as to maintain diversity along the Pareto front. Furthermore, we find that two optimization objectives have a complex reverse relation and a simple positive relation with constraints, respectively; thus, a population initialization method and a local auxiliary task are designed for two single-objective auxiliary tasks, respectively, so as to improve the performance of the algorithm on two objective functions. Finally, KMCEA is used to solve two kinds of models with three kinds of datasets. Compared with various methods, KMCEA can not only effectively discover clinical combinatorial drugs but also better solve the SNCPDTs regarding convergence and diversity. [ABSTRACT FROM AUTHOR]

The article focuses on the novel approach on the use of stub-loaded resonators which enables the design of compact bandpass filters (BPF) in communications systems application in transferring desired bands of signals. It demonstrates the feasibility of developing a quad-band BPF on modified three-band filters. Details about the multiband bandpass filters on its use as wireless applications is also examined.

We construct electromagnetically induced transparency (EIT) by dynamically coupling a superradiant state with a subradiant state. The superradiant and subradiant states with enhanced and inhibited decay rates act as the excited and metastable states in EIT, respectively. Their energy difference determined by the distance between the atoms can be measured by the EIT spectra, which renders this method useful in subwavelength metrology. The scheme can also be applied to many atoms in nuclear quantum optics, where the transparency point due to counter-rotating wave terms can be observed. [ABSTRACT FROM AUTHOR]

Three new compounds (1-3), including a sesterterpenoid, aspterpenacid C (1), with an unusual 5/3/7/6/5 pentacyclic skeleton, together with seven known ones (4-10), were isolated from the ethanol extract of the traditional Chinese medicinal plant Swertia bimaculata. Their structures were elucidated on the basis of the methods of spectroscopic NMR, MS, and computational chemistry. The structure of 1 was further confirmed by single-crystal X-ray diffraction analysis. Compounds 1-10 were tested for activities on the inhibition of nitric oxide production and HIV-1 replication in vitro. Compound 1 exhibited moderate activity in inhibiting nitric oxide production (IC50 = 16.1 µM) and HIV-1 replication (EC50 = 1.35 µM). [ABSTRACT FROM AUTHOR]

In the present study, a traveling wave wall (TWW) was employed to manipulate the vortex shedding behind a fixed circular cylinder based on a 2-D CFD numerical simulation method at a low Reynolds number of 200. The study mainly focused on four types of TWW propagation directions combined with nine different wave velocities to eliminate vortex shedding, and the lift and drag coefficients and vortex shedding modes at different propagation directions or velocities were analyzed in detail to access the effectiveness of the TWW flow control method. The control mechanism of eliminating wake stemming from the flow around a TWW-controlled circular cylinder was revealed by the boundary vorticity flux (BVF) and relative flow fields. The results show that the type of downstream propagating TWW can effectively eliminate the alternating wake. When the ratio of the wave velocity to the oncoming velocity is 2.0, the fluctuations of the lift coefficients descended to the lowest point. The averages of the drag coefficients decreased with increasing wave velocity and descended to the lowest point when the ratio of the wave velocity to the oncoming velocity was 5.0. Owing to the capture of small-scale vortices, there was a relatively larger level of vorticity in the wave valley of the TWW cylinder. The relative flow fields showed that the vortex shedding from the cylinder was completely eliminated and that the goal of eliminating the oscillating wake and suppressing the potential vortex-induced vibration (VIV) of flow around a cylinder was achieved. [ABSTRACT FROM AUTHOR]

The Bethe-Salpeter wave functions of SU(3) pure gauge glueballs are revisited in this study. The ground and the first excited states of the scalar and tensor glueballs are identified unambiguously through the variational method. We calculate the wave functions in the Coulomb gauge and use two lattice spacings to check the discretization artifacts. For the ground states, the radial wave functions are approximately Gaussian, and the size of the tensor glueball is roughly twice as large as that of the scalar glueball. For the first excited states, the radial nodes are clearly observed for both the scalar and the tensor glueballs, such that they can be interpreted as the first radial excitations. These observations may shed light on the theoretical understanding of the inner structure of glueballs. [ABSTRACT FROM AUTHOR]

The spectrum of cooperative light emission from ensembles of multilevel atoms is studied in optical vector theory and without applying the rotating-wave approximation. The effects of counter-rotating terms are included using a unitary transformation method. The spectra are analyzed and interpreted in terms of the radiative eigenmodes of tie atom ensemble. We further show how the qualitative features arise from the structure of the underlying two-particle dipole-dipole interaction induced by the the vacuum field. We predict that for a suitable modification of the ensemble properties, the sign of the cooperative Lamb shift can be reversed, while still maintaining strcng superradiant emission. Finally, we discuss the effects of finite detection resolution and of averaging over many realizations of the random distribution of atoms for given ensemble parameters. [ABSTRACT FROM AUTHOR]

Four (1-4) previously unknown lupane-type triterpenoidal saponins were isolated from the roots of Pulsatilla chinensis, along with six triterpene saponins (5-10). The structures of saponins 1-4 were determined as 23-hydroxy-3β-[(O-β-D-glucopyranosyl-(1→4)-α-L-arabinopyranosyl)]lup-20(29)-en-28-oic-acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester (1), 23-hydroxy-3β-[(O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-α-L-arabinopyranosyl)] lup-20(29)-en-28-oic-acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester (2), 3β-[(O-β-D-glucopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl)]lup-20 (29)-en-28-oic-acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester (3), and 3β-[(O-β-D-glucopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl)]lup-20(29)-en-28-oic-acid 28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester (4), on the basis of hydrolysis and spectral evidence, including 1D- and 2D-NMR and HR-ESI-MS analyses. These pure isolates (1-10) were tested for their anticomplement activity, using an in vitro assay of the complement system of the classical pathway. [ABSTRACT FROM AUTHOR]

In this article, the authors report that multiple notches are precisely positioned within the bandpass filter's bandwidth by using a composite resonator and several semicircular defected ground structures (DGSs). The authors say that the ultrawideband (UWB) bandpass filter, implemented with a combination of multiple-mode resonator (MMR) and simplified composite right/left-handed (SCRLH) structures, achieved the desired passband with low loss while also adding two notches with high rejection.

Reducing the effect of solar heat radiation on large reflector antennas is one of the important means to achieve high requirements for the electrical properties of the antennas with high operating frequency. By calculating the variation of solar incidence angles in a day, the temperature distribution, thermal stress field and thermal distortion of the reflector surface at each moment are obtained based on I-DEAS. In view of the important influence of the shadow on the structure of antennas, the impacts and rules of the temperature distribution at each moment on reflector are presented in the form of time-sharing-partitioning, which can help the engineers implement the temperature compensation and structural optimization of antennas. [ABSTRACT FROM AUTHOR]