Compact Circularly Polarized Patch Antenna Using a Composite Right/Left-Handed Transmission Line Unit-Cell

A compact circularly polarized (CP) patch antenna using a composite right/left-handed (CRLH) transmission line (TL) unit-cell is proposed. The CRLH TL unit-cell includes a complementary split ring resonator (CSRR) for shunt inductance and a gap loaded with a circular-shaped slot for series capacitance. The CSRR can decrease the TM10 mode resonance frequency, thus reducing the electrical size of the proposed antenna. In addition, the asymmetry of the CSRR brings about the TM01 mode, which can be combined with the TM10 mode by changing the slot radius. The combination of these two orthogonal modes with 90° phase shift makes the proposed antenna provide a CP property. The experimental results show that the proposed antenna has a wider axial ratio bandwidth and a smaller electrical size than the reported CP antennas. Moreover, the proposed antenna is designed without impedance transformer, 90° phase shift, dual feed and ground via

Detecting Equilibrium Cells in DSMC to Improve the Computational Efficiency

DSMC in the large collision rate limit has previously been used as an approximate Euler solver [Pullin, J. Comput. Phys., v34, 1980, pp. 231--244, Lengrand et al. Rarefied Gas Dynamics 12, Progress in Astronautics and Aeronautics, v74, AIAA, 1981, p994, Merkle et al. Rarefied Gas Dynamics 12, Progress in Astronautics and Aeronautics, v74, AIAA, 1981, p256]. Macrossan [Rarefied Gas Dynamics 22, AIP Conference Proceedings 585, American Institute of Physics, New York, 2001, pp. 388--395] suggested that therefore a particle-only approach could be taken to flows which contain a mixture of rarefied and continuum or near-continuum conditions; in those parts of the flow that would more conventionally be solved by a continuum Navier-Stokes or Euler solver, DSMC could be invoked in its `Euler solver mode'. The regions where the Euler solver can be invoked were determined (as is usual in such hybrid codes) by evaluating the breakdown parameter which compares the local collision time to the flow transit time through a local characteristic flow length. The flow length is derived from the gradient of some flow property. Here we investigate a different, but related, approach to this problem. In regions where the Euler equations apply, the velocity distribution function has the Maxwell form. If the velocity distribution in a cell is examined after the particles have been moved, but before the collisions are calculated, it could be established that the cell is already in, or very close to, its equilibrium state. Such "equilibrium cells" may be found anywhere in the flow where the flow gradients are small; it is only when the movement of the particles brings to one `recipient cell' particles which started in different "donor cells" with different flow conditions that a non-equilibrium velocity distribution is established in the recipient cell. Here two different measures derived from the velocity distribution were used to identify the equilibrium cells: the ratio of shear stress to pressure and a measure of the departure of all temperature components from the overall kinetic temperature. These were evaluated from the time-averaged flow state found from flow samples taken before the collision calculations were performed. In the equilibrium cells there would appear to be no need to calculate any collisions; the effect of the collisions would merely be to bring about a new statistical representation of the same equilibrium distribution. To maintain stability it was found that new velocities must be established in these equilibrium cells. Two different methods were used to set new velocities in equilibrium cells. These were (1) Pullin's EPSM method by which new particle velocities are selected from an equilibrium distribution and (2) a form of `collision limiting' in which a reduced number of collisions are calculated in equilibrium cells. These methods were tested for a Mach 5, blunt body flow with freestream Knudsen numbers of 0.1 and 0.064. Savings of CPU times of 10% (over standard DSMC) were achieved. We believe the general method could lead to greater savings in the CPU times for flows at lower Knudsen numbers, where the collision calculations could become more time consuming

Mgb2 Nonlinear Properties Investigated under Localized High RF Magnetic Field Excitation

In order to increase the accelerating gradient of Superconducting Radio Frequency (SRF) cavities, Magnesium Diboride (MgB2) opens up hope because of its high transition temperature and potential for low surface resistance in the high RF field regime. However, due to the presence of the small superconducting gap in the {\pi} band, the nonlinear response of MgB2 is potentially quite large compared to a single gap s-wave superconductor (SC) such as Nb. Understanding the mechanisms of nonlinearity coming from the two-band structure of MgB2, as well as extrinsic sources, is an urgent requirement. A localized and strong RF magnetic field, created by a magnetic write head, is integrated into our nonlinear-Meissner-effect scanning microwave microscope [1]. MgB2 films with thickness 50 nm, fabricated by a hybrid physical-chemical vapor deposition technique on dielectric substrates, are measured at a fixed location and show a strongly temperature-dependent third harmonic response. We propose that at least two mechanisms are responsible for this nonlinear response, one of which involves vortex nucleation and penetration into the film. [1] T. M. Tai, X. X. Xi, C. G. Zhuang, D. I. Mircea, S. M. Anlage, "Nonlinear Near-Field Microwave Microscope for RF Defect Localization in Superconductors", IEEE Trans. Appl. Supercond. 21, 2615 (2011).Comment: 6 pages, 6 figure

Trends and driving forces of China's virtual land consumption and trade

Land resources are important for China’s rapid economic development, especially for food and construction. China’s land resources are under tremendous pressures, and therefore land use is increasingly displaced to other parts of the world. This study analyses the evolution and driving forces of China’s land consumption from 1995 to 2015. The main results show that China’s land footprint increased from 8.8% of the global land resources under human use in 1995 to 15.7% in 2015. China’s domestic land resources are mainly used for serving domestic consumption. Moreover, China needs to import virtual land from foreign countries to satisfy 30.8% of its land demand. Among the three land use types of cropland, grassland and forests, grassland had the largest fraction in China’s land footprint from 1995 to 2000, while forest has become the largest one since 2000. China’s virtual land trade experienced a sharp increase in net imports from 9.4E + 04 km2 in 1995 to 3.4E + 06 km2 in 2015. Observing China’s virtual land network by a cluster analysis, this study concludes that China keeps tight relationships with Australia, Japan, Brazil and Korea for its cropland consumption, and Canada, USA, Mexico, Australia, Korea and Japan are relevant for its grassland consumption. In addition, decomposition analysis results show that affluence is the major driving factor for China’s land consumption, while changes in land use intensity could mitigate some of the related effects. Lastly, policy recommendations are proposed so that China can move toward sustainable land management

Spatial and statistical variability of soil properties for fields in BMPs in the Steppler sub-watershed, South Tobacco Creek Watershed, research design and preliminary results

Non-Peer Reviewe

Generation of spatially-separated spin entanglement in a triple quantum dot system

We propose a novel method for the creation of spatially-separated spin entanglement by means of adiabatic passage of an external gate voltage in a triple quantum dot system.Comment: 10 pages, 6 figure

CP Violation in Fermion Pair Decays of Neutral Boson Particles

We study CP violation in fermion pair decays of neutral boson particles with spin 0 or 1. We study a new asymmetry to measure CP violation in $\eta, K_L \rightarrow \mu^+\mu^-$ decays and discuss the possibility of measuring it experimentally. For the spin-1 particles case, we study CP violation in the decays of $J/\psi$ to $SU(3)$ octet baryon pairs. We show that these decays can be used to put stringent constraints on the electric dipole moments of $\Lambda$, $\Sigma$ and $\Xi$.Comment: 14p, OZ-93/22, UM-93/89, OITS 51

Finite dimensional integrable Hamiltonian systems associated with DSI equation by Bargmann constraints

The Davey-Stewartson I equation is a typical integrable equation in 2+1 dimensions. Its Lax system being essentially in 1+1 dimensional form has been found through nonlinearization from 2+1 dimensions to 1+1 dimensions. In the present paper, this essentially 1+1 dimensional Lax system is further nonlinearized into 1+0 dimensional Hamiltonian systems by taking the Bargmann constraints. It is shown that the resulting 1+0 dimensional Hamiltonian systems are completely integrable in Liouville sense by finding a full set of integrals of motion and proving their functional independence.Comment: 10 pages, in LaTeX, to be published in J. Phys. Soc. Jpn. 70 (2001