The optical microscopy with virtual image breaks a record: 50-nm resolution imaging is demonstrated

We demonstrate a new 'microsphere nanoscope' that uses ordinary SiO2 microspheres as superlenses to create a virtual image of the object in near field. The magnified virtual image greatly overcomes the diffraction limit. We are able to resolve clearly 50-nm objects under a standard white light source in both transmission and reflection modes. The resolution achieved for white light opens a new opportunity to image viruses, DNA and molecules in real time

Enhancing resilience by reducing critical load loss via an emergent trading framework considering possible resources isolation under typhoon

Leveraging distributed resources to enhance distribution network (DN) resilience is an effective measure in response to natural disasters. However, the willingness and economy of distributed resources are typically ignored. To address this issue, this paper proposes an emergent trading framework that uses parking lots (PLs) as resources to provide power support to critical loads (CLs) in a blackout due to typhoons. In this trading framework, an evolutionary Stackelberg game-based trading model is established to consider maximizing all stakeholders' economic benefits, considering possible resources isolation under typical fault scenarios caused by typhoons, and a benefit allocation mechanism is proposed for all stakeholders to motivate all stakeholders to participate in the trading. This framework allows that critical loads could reduce their load loss, parking lots could receive adequate compensation to stimulate them to participate in the trading, and distribution utility could ensure its economic benefits. Furthermore, an iterative evolutionary-Stackelberg solution set-up is applied to obtain the equilibria of the proposed framework. Simulation results on the modified IEEE 69-bus test system and IEEE 123-bus test system reveal the validity of the proposed method

Robust optimization in HTS cable based on design for six sigma

The nonuniform ac current distribution among the multilayer conductors in a high-temperature superconducting (HTS) cable reduces the current capacity and increases the ac loss. Various numerical simulation techniques and optimization methods have been applied in structural optimization of HTS cables. While the existence of fluctuation in design variables or operation conditions has a great influence on the cable quality, in order to eliminate the effects of parameter perturbations in design and to improve the design efficiency, a robust optimization method based on design for six sigma (DFSS) is presented in this paper. The optimization results show that the proposed optimization procedure can not only achieve a uniform current distribution, but also improve significantly the reliability and robustness of the HTS cable quality, comparing with those by using the particle swarm optimization. © 2008 IEEE

Robust optimization of multilayer conductors of HTS AC cable using PSO and perturbation analysis

For a High Temperature Superconducting (HTS) cable, a non-uniform AC current distribution among the multilayer conductors gives rise to increased AC losses. To get a uniform current distribution among the multilayer conductors, a constrained optimization model is constructed with continuous and discrete variables, such as the winding angle, radius and the winding direction of each layer. Under the constraints of the mechanical properties and critical current of the tape, the Particle Swarm Optimization (PSO) algorithm is employed for structural parameter optimization in both warm and cold dielectric type HTS cables. A uniform current distribution among layers is realized by optimizing the structural parameters. The perturbation analysis is employed to evaluate the parameters after optimization. It is found that the robust stabilizations are different among the various optimal results. The PSO is proved to be a more powerful tool than the Genetic Algorithm (GA) for structural parameter optimization. © 2006 IEEE

Cross section for charmonium absorption by nucleons

Journals published by the American Physical Society can be found at http://publish.aps.org/The cross section for J/psi absorption by nucleons is studied using a gauged SU(4) hadronic Lagrangian but with empirical particle masses, which has been used previously to study the cross sections for J/psi absorption by pion and rho meson. Including both two-body and three-body final states, we find that with a cutoff parameter of 1 GeV at interaction vertices involving charm hadrons, the J/psi-N absorption cross section is at most 5 mb and is consistent with that extracted from J/psi production from both photonuclear and proton-nucleus reactions

A survey on health-promoting lifestyle among community-dwelling older people with hypertension in Macau

2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Current distribution analysis for high temperature superconducting cable considering hysteresis characteristics

This paper presents a hysteresis model for Type-II high temperature superconductor (HTS) by using simplified Preisach Model, in which the Preisach distribution function μ-kα, β) is determined only based on the B-H limiting loop. The nonlinear dynamic circuit model of the superconductor is established. In the circuit model, the hysteresis inductance and hysteresis loss described by using simplified Preisach Model are deduced. Applying the hysteresis circuit model, the currents flowing in different superconductor layers of high temperature superconducting cable are simulated, as well as the hysteresis loss of the superconducting cable. The simulation results are verified by comparison with the data recorded in literatures. Finally, the influences of hysteresis on superconducting cable are analyzed and discussed. © 2010 - IOS Press and the authors. All rights reserved

Hydrogen adsorption capacity of adatoms on double carbon vacancies of graphene: A trend study from first principles

Structural stability and hydrogen adsorption capacity are two key quantities in evaluating the potential of metal-adatom decorated graphene for hydrogen storage and related devices. We have carried out extensive density functional theory calculations for the adsorption of hydrogen molecules on 12 different adatom (Ag, Au, Ca, Li, Mg, Pd, Pt, Sc, Sr, Ti, Y, and Zr) decorated graphene surfaces where the adatoms are found to be stabilized on double carbon vacancies, thus overcoming the "clustering problem" that occurs for adatoms on pristine graphene. Ca and Sr are predicted to bind the greatest number, namely six, of H2 molecules. We find an interesting correlation between the hydrogen capacity and the change of charge distribution with increasing H2 adsorption, where Ca, Li, Mg, Sc, Ti, Y, Sr, and Zr adatoms are partial electron donors and Ag, Au, Pd, and Pt are partial electron acceptors. The "18-electron rule" for predicting maximum hydrogen capacity is found not to be a reliable indicator for these systems. © 2013 American Physical Society

Study on the distribution regularity of gas volume in multiphase pump

In order to reduce the phase separation, air plug and turbulence vortex in the multiphase pump. The two-fluid model and the standard k-¦ turbulence model are selected, the distribution regularity of gas phase volume within the multiphase pump is researched using the CFD software about air-liquid two-phase under the different working conditions. The results of the study showed that the gas phase gathers at the rim when the gas-liquid two-phase enter into the impeller inlet, and the gas phase is gradually increased at the rim with the increase of the flow rate, the gas is concentrated in the hub at the second half of the impeller, and the most serious aggregation is the small flow rate condition. When the flow is constant, the gas obviously increases in the guide vane hub with the increase of the gas volume fraction. With the increase of the gas volume fraction, the uniformity of the gas phase in the circumferential direction is deteriorated in the inlet and the middle of impeller, and the lower gas volume fraction region is decreased in the impeller. The results of the study reveal the distribution regularity of gas volume within the multiphase pump, provide the reference basis for the design of the multiphase pump under the higher gas volume fraction

Effect of gas volume fraction on the vortex motion within the oil-gas multiphase pump

In order to research the regular pattern of the vortex within the oil-gas multiphase pump with the gas volume fraction changes, the standard K-epsilon turbulence model is selected, the gas-liquid two-phase flow field within the multiphase pump is calculated by the CFD software under the different gas volume fraction, the regular pattern of the vortex motion within the multiphase pump is analyzed under the different gas volume fraction. The results show that, from the impeller hub to the rim, the vortex in the guide vane is gradually become smaller, the vortex within the impeller is gradually obvious, and with the increase of the gas volume fraction, the flow separation, the backflow and the vortex phenomenon within the impeller and the guide vane are gradually increased. It is also found that the flow separation has a greater influence on the turbulent dissipation within the whole flow field, that is, the more serious the area of off flow, the greater the energy loss. The results provide an important theoretical basis for the optimal design of the structure of oil-gas multiphase pump